Enhanced microwave heating systems and methods of using the same

ES 2 623 907 T3

DESCRIPTION

Improved microwave heating systems and methods of using them

Field of Invention

[0001] The invention relates to microwave systems for heating one or more objects, articles and / or loads

Background

[0002] Electromagnetic radiation, like microwave radiation, is a known mechanism for supplying energy to an object. The ability of electromagnetic radiation to penetrate and heat an object quickly and efficiently has proven advantageous in many chemical and industrial processes. Due to its ability to rapidly and completely heat an article, microwave energy has been used in heating processes where it is desired to quickly reach a prescribed minimum temperature, such as pasteurization and / or sterilization processes. Also, because microwave energy is generally non-invasive, microwave heating can be particularly useful for heating sensitive dielectric materials, such as food and pharmaceuticals. However, to date, the complexities and nuances of safely and efficiently applying microwave energy, especially on a commercial scale, have severely limited its application in various types of industrial processes. WO2005 / 023013 provides an example of a microwave system for heating multiple items.

[0003] Therefore, there is a need for an efficient, consistent, and cost-effective industrial scale microwave heating system suitable for use in a wide variety of processes and applications.

Resume

[0004] An embodiment not according to the present invention relates to a microwave system for heating multiple items. The system comprises a microwave chamber configured to receive the articles and a conveyor system to transport the articles through the microwave chamber along a transport axis. The system also comprises a first microwave launcher configured to propagate microwave energy into a microwave chamber along a first central launch axis, where a first launch tilt angle of at least 2 ° is defined and less than 15 ° between the first central launch axis and a plane normal to the transport axis.

[0005] Another embodiment not according to the present invention relates to a microwave system for heating multiple items. The system comprises a microwave chamber configured to receive the articles and a conveyor system to transport the articles through the microwave chamber along a transport axis. The system also comprises a first microwave launcher defining at least one launch opening for discharging microwave energy into the microwave chamber; and an essentially microwave transparent window disposed between the microwave chamber and the launch opening. The window has a chamber-side surface that defines a portion of the microwave chamber and at least 50 percent of the total surface area of ​​the chamber-side surface is oriented at an angle of at least 2 ° to the horizontal.

[0006] Yet another embodiment not according to the present invention relates to a process for heating multiple articles in a microwave heating system, the process comprising the steps: (a) passing multiple articles through a microwave heating chamber by means of a conveyor system, wherein the microwave heating chamber is at least partially filled with a liquid medium; (b) generating microwave energy using one or more microwave generators; (c) introducing at least a part of the microwave energy into the microwave chamber via at least one microwave launcher, wherein at least a part of the microwave energy introduced into the microwave chamber is discharged at an angle of inclination throw of at least 2 °; and (d) heating the articles in the microwave heating chamber using at least a portion of the microwave energy discharged therein.

[0007] An embodiment not according to the present invention relates to a microwave system for heating multiple items. The system comprises a microwave generator to generate microwave energy having a predominant wavelength (λ), a conveyor system to transport the articles along a transport axis, and a first microwave launcher to launch at least one part of the microwave energy to the items transported by the conveyor system. The first microwave launcher defines at least one launch opening with a width (Wi) and a depth (Di), where Wi is greater than Di, and is characterized in that 2

ES 2 623 907 T3

Di is not greater than 0.625 λ.

[0008] Another embodiment not according to the present invention relates to a microwave system for heating multiple items. The system comprises a microwave generator to generate microwave energy with a predominant wavelength (λ), a microwave chamber configured to receive the articles, and a microwave distribution system to direct at least a part of the microwave energy. from the microwave generator to the microwave chamber. The microwave distribution system comprises a first microwave launcher. The first microwave launcher defines a microwave inlet for receiving at least a portion of the microwave energy and at least one launch opening for discharging the microwave energy into the microwave chamber. The microwave inlet has a depth (dci) and the launch opening has a depth (d1). The d0 is greater than di.

[0009] Another embodiment not according to the present invention relates to a microwave system for heating multiple items. The system comprises a microwave chamber configured to receive the articles, a conveyor system to transport the articles through the microwave chamber along a transport axis, and a first microwave launcher that defines a microwave inlet and two or more launch openings configured to discharge microwave energy into the microwave chamber. The center points of the adjacent launch openings are laterally spaced from one another with respect to the transport axis.

[0010] An embodiment not according to the present invention refers to a microwave launcher comprising a microwave input to receive microwave energy with a wavelength (λ), at least one launch opening to discharge at least a part of microwave energy, and a pair of opposing launcher end walls and a pair of opposing launcher side walls defining a microwave pathway between them. The microwave pathway is configured to allow passage of microwave energy from the microwave inlet to the launch opening. The launcher also includes a pair of inductive iris panels respectively coupled to and extending inwardly from the pair of end walls. Each of the inductive iris panels extends partially within the microwave pathway to define between them an inductive iris through which at least a portion of the microwave energy sent from the microwave input to the launch opening can pass. .

[0011] Another embodiment not according to the present invention relates to a microwave system for heating multiple items. The system comprises a microwave generator to generate microwave energy with a wavelength (λ), a microwave chamber configured to receive the articles, a conveyor system to transport the articles through the microwave chamber along a transport shaft, and a microwave distribution system for directing at least a portion of the microwave energy from the microwave generator to the microwave chamber. The microwave distribution system comprises a first microwave splitter for dividing at least a portion of the microwave energy into two or more separate portions and at least one pair of microwave launchers, each defining a microwave input and at least one launch opening for discharging microwave energy into the microwave chamber. The microwave distribution system further comprises a first inductive iris arranged between the first microwave splitter and the launch opening of one of the microwave launchers.

Yet another embodiment not according to the present invention relates to a process for heating multiple articles in a microwave heating system, the process comprising the steps: (a) passing multiple articles through a microwave heating chamber to along one or more conveyor lines of a conveyor system; (b) generating microwave energy using one or more microwave generators; (c) dividing at least a part of the microwave energy into two or more separate portions; (d) discharging the microwave energy portions into the microwave heating chamber by two or more microwave launchers; (e) after the division of step (c) and before the discharge of step (d), passing at least one of the microwave energy portions through a first inductive iris; and (f) heating the articles in the microwave heating chamber using at least a portion of the microwave energy discharged therein.

[0013] An embodiment not according to the present invention relates to a method for controlling a microwave heating system comprising the steps of (a) generating microwave energy using one or more microwave generators; (b) passing multiple items through a water-filled microwave chamber via a conveyor system; (c) directing at least a portion of the microwave energy into the microwave chamber via one or more microwave launchers to thereby heat at least a portion of the articles; (d) during at least a portion of steps (a) to (c), determining a value for one or more parameters of the microwave system so as to provide at least one determined parameter value; (e) comparing the determined parameter value with a corresponding target parameter value to determine a difference; and (f), depending on the difference, taking an action with respect to the microwave heating system. The microwave system parameter (s) are selected from the group consisting of net microwave power,

ES 2 623 907 T3 temperature of the water in the microwave chamber, flow rate of the water through the microwave chamber, and speed of the conveyor system.

[0014] Another embodiment that does not follow the present invention relates to a method that controls a microwave heating system comprising the steps of (a) generating microwave energy with at least one microwave generator; (b) passing at least a portion of the microwave energy through a first waveguide segment; (c) discharging at least a portion of the microwave energy from the first waveguide segment into the microwave chamber via at least one microwave launcher to thereby heat multiple items; (d) determining a first value of net power discharged from the microwave launcher using a first pair of directional couplers; (e) determining a second value of net power discharged from the microwave launcher using a second pair of directional couplers, wherein the first and second pairs of directional couplers are independent of each other; (f) comparing the first value and the second value to determine a first difference; and (g) taking action with respect to the microwave heating system when the difference is greater than a predetermined amount.

[0015] An embodiment not according to the present invention relates to a variable phase short-circuit device for use in a microwave heating system. The device comprises a fixed section defining an essentially rectangular opening and a rotating section comprising a housing and a plurality of spaced, essentially parallel plates received in the housing. The housing comprises opposing first and second ends and the first end defines a second opening adjacent to the first opening of the fixed section. Each of the plates engages the second end of the housing and extends generally into the first and second openings. The rotatable section is configured to rotate relative to the fixed section about an axis of rotation that extends through the first and second openings.

[0016] Another embodiment not according to the present invention relates to a method for heating multiple articles in a microwave heating system comprising the steps of (a) passing the articles through a heating zone of a microwave chamber by means of a conveyor system, where each of the articles is kept within the heating zone for an article residence time (τ); (b) generating microwave energy with one or more microwave generators; (c) passing at least a portion of the microwave energy through a phase change device configured to cyclically change the phase of the microwave energy at a rate of phase change (t); (d) discharging at least a part of the microwave energy exiting the phase change device into the heating zone by at least one microwave launcher; and (e) heating the articles in the heating zone with at least a part of the microwave energy discharged therein, where the relationship of the article residence time and the rate of phase change (τ: ί) is of at least 4: 1.

[0017] An embodiment not according to the present invention relates to a microwave system for heating multiple items. The system comprises at least a microwave generator for generating microwave energy, a microwave chamber, a conveyor system for transporting the articles through the microwave chamber, and a microwave distribution system for directing at least a part of the microwave energy from the microwave generator to the microwave chamber. The microwave distribution system comprises at least three microwave allocation devices for dividing the microwave energy into at least three separate portions. The microwave distribution system further comprises at least three microwave launchers for discharging the separate portions of microwave energy into the microwave chamber. Each of the microwave allocation devices is configured to divide the microwave energy according to a predetermined power ratio, wherein the predetermined power ratio for at least one of the microwave allocation devices is not 1: 1.

[0018] Another embodiment not according to the present invention relates to a process for heating multiple articles using microwave energy comprising the steps of: (a) introducing the initial amount of microwave power into a microwave dispensing device; (b) using the microwave distribution device to divide the initial amount of microwave power into a first fraction of launching microwaves and a first fraction of distribution microwaves, wherein the power ratio of the first fraction of launching microwaves and the first distribution microwave fraction is not 1: 1; (c) using the microwave distribution device to divide the first distribution microwave fraction into a second launch microwave fraction and a second distribution microwave fraction; (d) introducing the first launch microwave fraction into a microwave heating chamber via a first microwave launcher; and (e) introducing the second launch microwave fraction into the microwave heating chamber via a second microwave launcher.

[0019] One embodiment of the present invention relates to a continuous process for heating multiple items in a

ES 2 623 907 T3 microwave heating system comprising the steps of (a) heating the articles in a heating zone so as to provide multiple thermal articles with an essentially uniform temperature; (b) heating the thermalized articles in a microwave heating zone so as to increase the average temperature of each article by at least 50 ° C, wherein at least a portion of the heating is carried out at a heating rate of at least 25 ° C per minute; and (c) cooling the heated items in a cooling zone. Items pass through each of the thermalization zone, microwave heating zone, and cooling zone via one or more conveyor systems, wherein the heating system has a total production rate of at least 20 containers per minute per transport line. During step (b), the heating includes discharging microwave energy into a microwave chamber of said microwave heating zone by at least one launcher, where said launcher includes a microwave inlet and first and second launch openings. Said launcher includes at least one partition wall arranged between said microwave inlet and said launch openings, where said partition wall at least partially defines said first and second launch openings, and where said discharge includes discharging a portion of said microwave energy into said microwave chamber for each of said first and second launch openings.

[0020] Another embodiment not according to the present invention relates to a microwave system for heating multiple items. The system comprises a thermalization chamber to thermalize the articles to an essentially uniform temperature, a microwave heating chamber arranged downstream of the thermalization chamber to heat the thermalized articles, and a cooling chamber arranged downstream of the heating chamber. Microwave to cool heated items to a lower temperature. The microwave heating chamber is configured to increase the average temperature of the articles by at least 50 ° C at a heating rate of at least 25 ° C per minute. The system comprises at least one transport system configured to transport the articles through the thermalization chamber, the microwave heating chamber, and the cooling chamber. The microwave system is configured to achieve a total production rate of at least 20 containers per minute per conveyor line.

[0021] An embodiment not according to the present invention relates to a process for heating multiple articles in a microwave heating system comprising the steps of (a) passing the articles through a pressurized microwave chamber via a conveyor system, wherein the microwave chamber is at least partially filled with a liquid medium; (b) generating microwave energy by one or more microwave generators; (c) introducing at least a portion of microwave energy into the microwave chamber by means of one or more microwave launchers; (d) heating the articles in the microwave chamber using at least a portion of the microwave energy introduced into it; and (e) during at least a portion of the heating step (d), agitating at least a portion of the liquid medium within the microwave chamber, wherein said agitation includes discharging multiple jets of fluid toward the articles at multiple positions within. microwave chamber.

[0022] Another embodiment not according to the present invention relates to a process for heating multiple articles in a microwave heating system comprising the steps of (a) thermalizing the articles in a thermalization chamber filled at least partially with a liquid medium to thereby produce thermalized articles with a substantially uniform temperature; and (b) heating the thermalized articles in a microwave chamber. The thermalization of step (a) includes discharging multiple jets of the liquid medium towards the articles at multiple locations within the thermalization chamber.

[0023] An embodiment not according to the present invention refers to a closing gate device comprising a pair of spaced fixed elements having opposite sealing surfaces and defining a gate receiving space between the sealing surfaces, wherein each of the fixed elements defines a flow passage opening limited by one of the sealing surfaces, wherein the flow passage openings are substantially aligned with each other; and a gate assembly movable within the gate receiving space between a closed position where the gate assembly substantially blocks the flow passage openings and an open position where the gate assembly does not substantially block the flow passage openings. The gate assembly comprises a pair of spaced apart sealing plates and an actuating element arranged between the sealing plates, wherein when the gate assembly is in the closed position the actuating element is movable relative to the sealing plates between a retracted position and an extended position. The gate assembly further comprises at least one pair of bearings disposed between the seal plates, wherein movement of the actuator from the retracted position to the extended position causes the bearings to force the seal plates to separate from each other and towards a sealed position, where the sealing plates engage opposing sealing surfaces, wherein the movement of the actuator from the extended position to the retracted position allows the seal plates to retract from each other and to an unsealed position where the seal plates are disengaged from opposing sealing surfaces.

ES 2 623 907 T3

Another embodiment not according to the present invention relates to a method for moving one or more articles within a pressurized system comprising the steps of (a) passing one or more articles from a first pressurized process zone to a second zone process pressurized through a flow passage opening; (b) moving a pair of movable plates into the opening; (c) separating the plates from each other so as to seal the plates against a pair of opposing sealing surfaces that define the aperture at least partially, wherein the pair of sealed plates substantially isolate the first and second process zones from each other; (d) create a differential pressure of at least 15 psig over the pair of sealed plates; (e) depressurizing at least one of the first and second process zones to equalize the pressure on the pair of sealed plates; (f) moving the plates toward each other to detach the plates from the sealing surfaces; (g) moving the pair of plates out of the opening; and (h) removing the articles from the second process zone and bringing them back to the first process zone through the flow passage opening and / or inserting a new article into the second process zone through the opening. flow path.

[0025] An embodiment not according to the present invention relates to a microwave heating system for heating multiple articles. The system comprises a liquid-filled thermalization chamber, a liquid-filled microwave chamber configured to operate at a pressure greater than that of the thermalization chamber, and a pressure-locking system arranged between the thermalization chamber and the thermalization chamber. microwave. The pressure lock system comprises a pressure adjustment chamber, a first shut-off gate valve, and a second shut-off gate valve, wherein the first shut-off gate valve is coupled between the thermalization chamber and the chamber. pressure adjustment chamber, wherein the second shutoff gate valve is coupled between the pressure adjustment chamber and the microwave chamber.

[0026] Another embodiment not according to the present invention relates to a process for heating multiple articles in a microwave heating system comprising (a) passing a plurality of articles through a liquid-filled thermalization zone to thereby provide multiple thermalized items; (b) introducing at least a portion of the thermalized articles into a pressure setting zone, wherein the pressure setting zone is defined at least partially between a first and a second shut-off gate valve, wherein the first closing gate valve is in a first open position at least during a part of the introduction stage; (c) after the thermalized articles have been introduced into the pressure setting zone, moving the first shutoff gate valve from the first open position to the first closed position so as to substantially isolate the pressure setting zone from the thermalization zone; (d) moving the second shutoff gate valve from a second closed position to a second open position to allow items to transfer from the pressure setting zone to a liquid filled microwave heating zone; and (e) after the items have been removed from the pressure setting zone, moving the second shutoff gate valve from the second open position back to the second closed position to re-isolate the pressure setting zone. microwave heating zone pressure.

[0027] An embodiment not according to the present invention relates to a method for heating multiple articles comprising the steps of (a) heating a first test article in a small-scale model of a microwave heating system while transporting the first test article through a water-filled small-scale microwave chamber having a total internal volume of less than 50 cubic feet, wherein at least a part of the heating step (a) is carried out using microwave energy; (b) determining a first prescribed heating profile based on the heating of step (a), wherein the prescribed heating profile comprises at least one value for one or more microwave system parameters selected from the group consisting of net power discharged into the chamber, sequential microwave power distribution, average water temperature in the microwave chamber, water flow rate in the microwave chamber, and residence time of the article in the microwave chamber; and (c) heating a plurality of first commercial items in a large-scale microwave heating system while transporting the first commercial items through a water-filled large-scale microwave chamber having a total internal volume of at least 250 cubic feet. At least a part of the heating of step (c) is performed using microwave energy and wherein each of the first commercial items is substantially similar in size and composition to the first test article, wherein the heating of step (c ) is controlled with the first heating profile prescribed in step (b).

Brief Description of Drawings

[0028]

Fig. 1a is a process flow diagram describing an embodiment of a microwave heating system for heating one or more articles, particularly illustrating a system comprising a thermalization zone, a microwave heating zone, a zone optional dwell, a cooling zone, and a pair of pressure adjustment zones;

Fig. 1b is a schematic diagram of a microwave heating system 10 configured according to

ES 2 623 907 T3 an embodiment of the present invention, in particular each of the zones of the microwave heating system 10 indicated in the diagram provided in Fig. 1a;

Fig. 2a is a cross-sectional schematic end view of a process vessel configured in accordance with an embodiment of the present invention, particularly illustrating a conveyor system including a pair of conveyor lines arranged in a parallel configuration;

Fig. 2b is a schematic top sectional view of the process vessel shown in Fig. 2b illustrating in particular the arrangement of the transport lines spaced laterally from the transport axis extending through the vessel;

Fig. 2c is a cross-sectional schematic end view of another process vessel configured in accordance with another embodiment of the present invention, particularly illustrating a conveyor system including a pair of conveyor lines arranged in a stacked configuration;

Fig. 2d is a schematic side sectional view of the process vessel shown in Fig. 2c, illustrating, in particular, the arrangement of the transport lines spaced vertically from the transport axis extending through the vessel;

Fig. 3 is a perspective view of a carrier according to one embodiment of the present invention configured to secure and transport the items being heated through a liquid-filled process container;

Fig. 4a is a partial sectional side view of one embodiment of a microwave heating system that includes a pressure adjustment zone configured to transport one or more items from the thermalization zone to the microwave heating zone of the system. heating using a carrier transfer system;

Fig. 4b is a partial sectional side view of another embodiment of a microwave heating system that includes a pressure setting zone similar to that depicted in Fig. 4a, but particularly illustrating a carrier transfer system arranged almost completely within the pressure setting zone;

Fig. 4c is a partial schematic view of the pressure setting zone similar to those depicted in Figs. 4a and 4b, but illustrating another embodiment of the carrier transfer system for moving articles from the thermalization zone to the microwave heating zone;

Fig. 4d is a partial schematic view of the pressure setting zone similar to those depicted in Figs. 4a and 4b, but illustrating yet another embodiment of the carrier transfer system for moving articles from the thermalization zone to the microwave heating zone;

Fig. 5a is a partial sectional side view of a closing gate device configured in accordance with an embodiment of the present invention, particularly illustrating the gate assembly in an open position;

Fig. 5b is a partial sectional side view of the closing gate device shown in Fig. 5a, illustrating in particular the gate assembly in a closed position with the sealing plates in a retracted position;

Fig. 5c is a partial sectional side view of the closing gate device described in Figs. 5a and 5b, particularly illustrating the gate assembly in a closed position with the sealing plates in an extended position;

Fig. 5d is an enlarged partial view of the gate assembly described in Figs. 5a-c, illustrating in particular one embodiment of a bearing used to move the sealing plates of the gate assembly; Fig. 6a is a partial schematic sectional side view of a microwave heating zone configured according to an embodiment of the present invention, illustrating in particular the heating vessel and the microwave distribution system;

Fig. 6b is a top schematic view of a microwave heating zone configured according to an embodiment of the present invention illustrating in particular a configuration of microwave launchers in a heating system using a multi-line transport system;

Fig. 6c is a side schematic view of the microwave heating zone illustrated in Fig. 6b, illustrating in particular a group of microwave launchers configured to heat articles passing along a conveyor line;

Fig. 7a is a partial sectional side view of a microwave heating zone configured according to an embodiment of the present invention, illustrating in particular an inclined microwave launcher and showing the meaning of the term launch inclination angle (β);

Fig. 7b is a partial sectional side view of another embodiment of a microwave heating zone, particularly illustrating a microwave distribution system comprising a plurality of inclined launchers;

Fig. 8a is an enlarged partial sectional side view of a portion of a microwave heating zone, particularly illustrating one embodiment of a microwave window located near the discharge opening of at least one microwave launcher of the zone heating;

Fig. 8b is an enlarged partial sectional side view of a portion of a heating zone by

ES 2 623 907 T3 microwave, particularly illustrating another embodiment of a microwave window located near the discharge opening of at least one microwave launcher of the heating zone;

Fig. 8c is an enlarged partial sectional side view of a portion of a microwave heating zone, particularly illustrating yet another embodiment of a microwave window located near the discharge opening of at least one microwave launcher of the heating zone;

Fig. 9a is an isometric view of a microwave launcher configured in accordance with one embodiment of the present invention;

Fig. 9b is a longitudinal side view of the microwave launcher shown in Fig. 9a;

Fig. 9c is an end view of the microwave launcher shown in Figures 9a and 9b, particularly illustrating a launcher with a flared outlet;

Fig. 9d is an end view of another embodiment of the microwave launcher shown generally in Figures 9a and 9b, particularly illustrating a launcher with an inlet and an outlet of approximately the same size;

Fig. 9e is an end view of yet another embodiment of the microwave launcher shown generally in Figures 9a and 9b, particularly illustrating a launcher having a conical outlet; Fig. 10a is an isometric view of another microwave launcher configured in accordance with one embodiment of the present invention, particularly illustrating a launcher comprising a single microwave inlet and multiple microwave outlets;

Fig. 10b is a vertical cross-sectional view of the microwave launcher illustrated in Fig. 10a, particularly illustrating the multiple microwave outlets;

Fig. 10c is a vertical cross-sectional view of the microwave launcher shown in Figures 10a and 10b, particularly showing the pair of partition walls used to create individual microwave paths between the inlet and multiple outlets of the microwave launcher;

Fig. 11a is an isometric view of a microwave launcher configured according to yet another embodiment of the present invention, particularly showing an integrated inductive iris disposed between the inlet and outlet of the launcher;

Fig. 11b is a horizontal cross-sectional view of the microwave launcher illustrated in Fig. 11a; Fig. 11c is a horizontal cross-sectional view of another microwave launcher similar to the launcher shown in Fig. 11a, but including a pair of partition walls in addition to an inductive iris arranged between the inlet and outlet of the launcher;

Fig. 12a is a sectional side view of a phase change device configured in accordance with one embodiment of the present invention, particularly illustrating a piston-type tuning device including a single piston;

Fig. 12b is a schematic sectional side view of a phase change device configured in accordance with another embodiment of the present invention, particularly illustrating a piston-type tuning device including multiple pistons driven by a common rotary shaft;

Fig. 13a is a side perspective view of a phase change device configured according to yet another embodiment of the present invention, particularly illustrating a rotary phase change device;

Fig. 13b is a longitudinal cross-sectional view of the rotary phase change device shown in Fig. 13a;

Fig. 13c is a cross-sectional side view of the rotary section of the rotary phase change device shown in Figs. 13a and 13b, particularly showing the width and spacing of the plates arranged within the housing;

Fig. 13d is a cross-sectional side view of the fixed section of the rotary phase change device shown in Figs. 13a and 13b, particularly illustrating the dimensions of the fixed section; Fig. 13e is a side sectional view of a rotary phase change device configured in accordance with another embodiment of the present invention, particularly illustrating a drive system including a rotary crank element;

Fig. 13f is a sectional side view of a rotary phase change device configured in accordance with yet another embodiment of the present invention, particularly illustrating an actuation system including a group of compression springs;

Fig. 14a is a partial schematic side and sectional view of a microwave distribution system using two phase change devices for phase change and / or impedance tuning; Fig. 14b is a partial schematic sectional side view of a microwave heating container configured in accordance with one embodiment of the present invention, particularly illustrating a phase change device coupled to the container for use as a frequency tuner; 15a is a partial schematic sectional side view of a portion of a microwave heating system, particularly illustrating a thermalization zone including multiple fluid jet stirrers; Fig. 15b is an end view of a thermalization zone similar to that shown in Fig. 15a, particularly illustrating an embodiment in which the fluid jet stirrer is positioned

ES 2 623 907 T3 circumferentially within the thermalization zone;

Fig. 16 is a flow chart depicting the main steps of a method for controlling a microwave system according to an embodiment of the present invention;

Fig. 17 is a flow chart depicting the main steps of a method for determining net power discharged from at least one microwave launcher using two or more pairs of directional couplers; and Fig. 18 is an isometric representation of the location of thermocouples inserted into a test container to determine the minimum container temperature for determining the heating profile for an article according to one embodiment of the present invention.

Detailed description

[0029] The processes and microwave system for heating multiple articles according to various embodiments of the present invention are described below. Examples of articles suitable for heating in systems and processes of the present invention may include, but are not limited to, foods, medical fluids, and medical instruments. In one embodiment, the microwave systems described herein can be used to pasteurize and / or sterilize items that are heated. In general, pasteurization involves rapidly heating an article or articles to a minimum temperature of between 80 ° C and 100 ° C, while sterilization involves heating one or more articles to a minimum temperature of between 100 ° C and 140 ° C. . However, in one embodiment, pasteurization and sterilization can be carried out simultaneously or almost simultaneously and it is possible to configure many processes and systems to both pasteurize and sterilize one or more items. Various embodiments of microwave systems and processes configured to heat one or more types of articles will now be described in detail and with reference to the Figures.

Referring now to Figures 1a and 1b, Figure 1a depicts a schematic representation of the main stages in a heating process. microwave according to an embodiment of the present invention, while Figure 1b represents an embodiment of a microwave system 10 operable to heat multiple items according to the process described in Figure 1a. As shown in Figures 1a and 1b, one or more articles can be initially introduced into a thermalization zone 12, where the articles can be thermalized at a substantially uniform temperature. Once thermalized, the articles can then optionally be passed through a pressure setting zone 14a before being introduced into a microwave heating zone 16. In microwave heating zone 16, articles can be rapidly heated using microwave energy discharged in at least a portion of the heating zone by one or more microwave launchers, generally illustrated as launchers 18 in Figure 1b. The heated articles can then optionally be passed through a dwell zone 20, where the articles can be kept at a constant temperature for a specified amount of time. The articles can then be moved to a cooling zone 22, where the temperature of the articles can be rapidly reduced to a suitable handling temperature. Thereafter, the cooled items can optionally be passed through a second pressure setting zone 14b before being removed from system 10 and used later.

[0031] Microwave system 10 can be configured to heat many different types of items. In one embodiment, the heated items in microwave system 10 can comprise foods, such as fruits, vegetables, meats, pasta, ready meals, and even beverages. In other embodiments, the heated items in a microwave system 10 may comprise packaged medical fluids or medical and / or dental instruments. Items processed within microwave heating system 10 can be of any suitable size or shape. In one embodiment, each item can have a length (longest dimension) of at least about 2 inches, at least about 4 inches, at least about 6 inches, and / or not more than about 18 inches, not more than about 12 inches, or no more than 10 inches; a width (second longest dimension) of at least about 1 inch, at least about 2 inches, at least about 4 inches, and / or not more than about 12 inches, not more than about 10 inches, or not more than about 8 inches ; and / or a depth (shortest dimension) of at least about 0.5 inches, at least about 1 inch, at least about 2 inches, and / or not more than about 8 inches, not more than about 6 inches, not more than about 4 inches. The articles may comprise individual items or packages that are generally rectangular or prism-like in shape or they may comprise a continuous web of connected items or packages that pass through the microwave system 10. The articles or packages may be constructed of any material, including plastics, celluloses, and other microwave-transparent materials, and may be passed through a microwave system 10 by one or more conveyor systems, the embodiments of which will be described in detail below. continuation.

According to one embodiment of the present invention, each of the described thermalization, microwave heating, dwell and / or cooling zones 12, 16, 20, and 22 can be defined within a single container, as represented by general shape in Figure 1b, while, in another embodiment, at least one of the stages described

ES 2 623 907 T3 above can be defined within one or more separate containers. According to one embodiment, at least one of the above-described steps can be carried out in a container that is at least partially filled with a fluid medium in which the items being processed can be at least partially submerged. The fluid medium can be a gas or liquid that has a dielectric constant greater than the dielectric constant of air, and in one embodiment, it can be a liquid medium that has a dielectric constant similar to the dielectric constant of the items being processed. . Water (or liquid medium comprising water) may be particularly suitable for systems used to heat edible articles and / or medical devices and articles. In one embodiment, additives such as oils, alcohols, glycols, and salts can optionally be added to the liquid medium to alter or improve its physical properties (eg, boiling point) during processing, if necessary.

[0033] Microwave system 10 may include at least one conveyor system (not shown in Figures 1a and 1b) for conveying items through one or more of the processing zones described above. Examples of suitable conveyor systems may include, but are not limited to, plastic or rubber conveyors, chain conveyors, roller conveyors, flexible or multi-flex conveyors, wire mesh conveyors, bucket conveyors, pneumatic conveyors, screw conveyors. , channel or vibrating conveyors, and combinations thereof. The conveyor system may include any number of individual conveyor lines and may be arranged in any suitable manner within the process vessels. The conveyor system used by the microwave system 10 can be configured in a generally fixed position within the container or at least a portion of the system can be adjusted in a lateral or vertical direction.

Turning now to Figures 2a-2d, embodiments of a process vessel 120 are provided which includes a conveyor system 110 disposed therein. In an embodiment generally depicted in Figures 2a and 2b, conveyor system 110 includes a pair of laterally spaced essentially parallel conveyor lines 112, 114 positioned in a generally juxtaposed configuration within container 120. As shown in the cutaway top view of container 120 in Figure 2b, transport lines 112 and 114 may be laterally spaced from each other and may be positioned on either side of a transport axis 122, which extends along of the length of the container 120 in the direction of transport of the articles passing through it. Although shown in Figure 2a as being generally at the same vertical elevation within the container 120, it should be understood that, in one embodiment, the conveying lines 112, 114 may also be positioned at different vertical elevations. Additionally, the conveyor system 110 depicted in Figures 2a and 2b may also include multiple pairs of laterally spaced conveyor lines (embodiment not shown), such that the pairs of laterally spaced conveyor lines are vertically spaced from each other along the vertical dimension of the container 120.

[0035] Another embodiment of a conveyor system 110 that includes a pair of conveyor lines 116, 118 vertically spaced, substantially parallel, and positioned in a stacked arrangement within the interior of container 120, is shown in Figures 2c and 2d. Conveyor lines 116 and 118 may be configured above or below conveyor axis 122, which may generally extend along the length of container 120, as shown in the cutaway side view of container 120 provided in FIG. 2d. Furthermore, in a manner similar to that described above, the container 120 shown in Figures 2c and 2d may also include multiple pairs of transport lines, laterally spaced from each other within the container. Furthermore, each conveying line of the pair may or may not be offset relative to the other in a lateral direction. In a further embodiment (not shown), the container 120 may include a single transport line, positioned in the middle third of the internal volume of the container 120, or positioned at or near the center line of the container. Additional details of conveyor systems according to various embodiments of the present invention will be described in detail below.

[0036] When a conveyor system is used to transport articles through a liquid-filled process vessel, one or more carriers or other holding mechanisms can be used to control the position of the articles during passage through the liquid medium. . One embodiment of a suitable carrier 210 is illustrated in Figure 3. As shown in Figure 3, the carrier 210 comprises a lower clamping surface 212a and an upper clamping surface 212b configured to hold any suitable number of articles 216 between them. In one embodiment, the top and / or bottom surfaces 212b, a may have a mesh, grid, or grid structure, as generally depicted in Figure 3, while, in another embodiment, one or both surfaces 212a, b they can have a substantially continuous surface. Carrier 210 can be constructed of plastic, fiberglass, or any other dielectric material and, in one embodiment, can be made of one or more microwave-compatible and / or microwave-transparent materials. In some embodiments, the material can be a dissipative material. In some embodiments, carrier 210 may comprise virtually no metal.

[0037] The upper and lower clamping surfaces 212a, 212b can be connected to each other by means of a locking device.

ES 2 623 907 T3 attachment, shown as attachment means 219 in Figure 3, and once assembled, carrier 210 can be attached or attached to the conveyor system (not shown in Figure 3) according to any attachment mechanism suitable. In one embodiment, at least one side (or edge) of carrier 210 may include one or more attachment mechanisms, such as upper and lower hooks 218a, 218b shown in Figure 3, to secure carrier 210 to a portion ( for example, a bar, a rail, a belt, or a chain) of the conveyor system (not shown). Depending on the thickness and / or weight of the articles 216, the carrier 210 may include only one of hooks 218a, 218b to hold the carrier 210 on the conveyor system. The conveyor system used to transport articles 216 can be configured to transport multiple carriers along one or more conveyor lines and the carriers can be arranged in a side-spaced and side-spaced configuration and / or a vertically spaced and stacked configuration as described above. When the conveyor system includes multiple conveyor lines, each conveyor line may include a single carrier to hold multiple items 216, or each conveyor line may hold multiple carriers stacked or laterally spaced from each other.

[0038] Referring again to Figures 1a and 1b, the articles included in the microwave system 10 are initially introduced into a thermalization zone 12, where the articles are thermalized to achieve a substantially uniform temperature. In one embodiment, at least about 85 percent, at least 90 percent, at least 95 percent, at least 97 percent, or at least 99 percent of all items removed from the thermalization zone 12 They have a temperature of about 5 ° C, 2 ° C, or 1 ° C with each other. As used herein, the terms "thermalize" and "thermalize" generally refer to a temperature balancing or equalizing step. Depending on the initial and desired temperature of the items being thermalized, the temperature control system of the thermalization zone 12, illustrated in Figure 1a as heat exchanger 13, can be a heating and / or cooling system. In one embodiment, the thermalization step can be carried out at ambient temperature and / or pressure, while, in another embodiment, the thermalization can be carried out in a pressurized and / or liquid-filled thermalization vessel at a pressure no more than 10 psig, no more than 5 psig, or no more than 2 psig. Items that undergo thermalization can have a mean residence time in a thermalization zone 12 of at least about 30 seconds, of at least about 1 minute, of at least about 2 minutes, of at least about 4 minutes, and / or no more than about 20 minutes, no more than about 15 minutes, or no more than about 10 minutes. In one embodiment, the items removed from the thermalization zone 12 may have a temperature of at least about 20 ° C, at least about 25 ° C, at least about 30 ° C, at least about 35 ° C, and / or or not more than about 70 ° C, not more than about 65 ° C, not more than about 60 ° C, or not more than about 55 ° C.

[0039] In an embodiment where thermalization zone 12 and microwave heating zone 16 are operated at substantially different pressures, items removed from thermalization zone 12 may first be passed through a pressure setting zone 14a prior to entering microwave heating zone 16, as generally depicted in Figures 1a and 1b. The pressure setting zone 14a can be any zone or system configured to transition the items being heated between a lower pressure area and a higher pressure area. In one embodiment, pressure adjustment zone 14a may be configured to transition articles between two zones having a pressure difference of at least about 1 psi, of at least about 5 psi, of at least about 10 psi, and / or not more than about 50 psi, not more than about 45 psi, not more than about 40 psi, or not more than about 35 psi. In one embodiment, microwave system 10 may include at least two pressure setting zones 14a, b as transition zones for items from an atmospheric pressure thermalization zone to a heating zone operating at elevated pressure prior to make the items return to atmospheric pressure, as described in detail below.

[0040] An embodiment of a pressure setting zone 314a disposed between a thermalization zone 312 and a microwave heating zone 316 of a microwave heating system 310 is illustrated in Figure 4a. Pressure adjustment zone 314a is configured to transition multiple articles 350, which may be attached within at least one carrier, from a lower pressure thermalization zone 312 and a higher pressure microwave heating zone 316. Despite Since in Figure 4a it is shown as a single carrier 352a, it is to be understood that the pressure adjustment zone 314a may be configured to receive more than one carrier. In one embodiment, the carriers can be received simultaneously, such that the pressure setting zone 314a contains multiple carriers at a time. In another embodiment, multiple carriers may be aligned and ready, for example, within thermalization zone 312, to be translated through pressure adjustment zone 314a, details of which will be described below.

[0041] In operation, one or more carriers 352a can be transferred from thermalization zone 312 to microwave heating zone 316, firstly, by opening a balancing valve 330 and allowing pressure between thermalization zone 312 and the pressure setting zone 314a is equalized. A gate device 332 can then be opened to allow carrier 352a to move from a conveyor line 340a arranged within thermalization zone 312 to a platform 334 within pressure adjustment zone 314a, 11

ES 2 623 907 T3 as shown in Figure 4a generally by the carrier 352b dotted line.

After that, the gate device 332 and the balancing valve 330 can be closed in sequence, re-isolating the pressure setting zone 314a from the thermalization zone 312. Next, another balancing valve can be opened 336 to allow the pressure to equalize between the pressure setting zone 314a and the microwave heating zone 316. Once equilibrium is achieved, another gate device 338 can be opened to allow carrier 352b to move onto another conveyor system 340b disposed within microwave heating zone 316, as generally shown on line carrier. points 352c in Figure 4a. The gate device 338 and the balancing valve 336 can then be closed in sequence, re-isolating the microwave heating zone 316 from the pressure setting zone 314a. The process can then be repeated to transport additional carriers from thermalization zone 312 to microwave heating zone 316 as needed.

[0043] According to one embodiment, each of the microwave heating 316 and thermalization 312 zones can be filled 5 with a non-compressible fluid or liquid such as, for example, water or solutions including water. As used herein, the term "filled" implies a configuration in which at least 50 percent of the specified volume is filled with the filling medium. The filling medium can be a liquid, typically a non-compressible liquid and can be or include, for example, water. In some embodiments, the filled volumes can be at least 75 percent, at least 90 percent, at least 95 percent, or 100 percent full of the fill medium. When the thermalization zone 312 and / or the microwave heating zone 316 are filled with a non-compressible fluid, the devices 332, 338 and / or pressure adjustment zone 314a may also include two or more flaps or one-way valves, which are shown as valves or flaps 342, 344 in Figure 4a, to prevent substantial fluid leakage between thermalization zone 312 and microwave heating zone 316 when gate devices 332 and 338 are open and carrier 352 passes between them.

[0044] Transport of carrier 352 from thermalization zone 312 through pressure setting zone 314a and into microwave heating zone 316 can be accomplished by one or more automatic article transfer systems, some of which various embodiments are illustrated in Figures 4b-4d. In some embodiments, automatic transfer system 380 may include one or more transfer devices, disposed within thermalization zone 312, pressure adjustment zone 314a, and / or microwave heating zone 316 to move the carrier. 352 into and / or out of the pressure setting zone 314a. In one embodiment shown in Figure 4b, transfer system 380 includes two gear transfer devices 381, 382 configured to engage teeth 353 disposed along the lower edge of carrier 352 and rotate, as indicated by arrows 392a, b to pulling carrier 352 out of thermalization zone 312 and / or pushing carrier 352 toward microwave heating zone 316. As shown in Figure 4b, the first and second gear transfer devices 381, 382 remain substantially stationary (in terms of lateral movement) during transport of the carrier 352 and are almost entirely, or fully, arranged within pressure setting zone 314a.

[0045] In contrast, some embodiments of the automatic transfer system 380 may include one or more transfer devices that can move laterally (ie, move in the direction of transport) during transport of the carrier 352 inward and / or or outside the pressure setting zone 314a. As depicted in an embodiment shown in Figure 4c, a portion of the automatic transfer system 380 may be disposed in the thermalization zone 312 and / or the microwave heating zone 316 and can be configured to extend into or retract from the zone. pressure setting 314a. In the system 380 shown in Figure 4c, the transfer devices include a pusher arm 381 configured to push the carrier 352 toward the pressure setting zone 314a and a pull arm 382 to pull the carrier 352 toward the heating zone. by microwave 316. Neither push arm 381 nor pull arm 382 are disposed within pressure adjustment zone 314a; rather, each is configured to extend into and retract from pressure adjustment zone 314a, as shown generally by arrows 394a, b in Figure 4c.

According to another embodiment depicted in Figure 4d, the automatic transport system 380 includes a platform 334 having a movable portion 384, which is configured to extend into and retract from the thermalization and / or heating zone 312. by microwave 316 to thereby transport carrier 352 into and out of microwave heating and thermalization zones 312, 316, as generally shown by arrows 396a and 396b. Unlike the embodiment illustrated in Figure 4c, the automatic transfer system 380 depicted in Figure 4d is primarily disposed within the pressure adjustment zone 314a and is configured to extend out of and retract back into the adjustment zone. pressure 314a.

Regardless of the specific configuration of the transfer devices used by the automatic item transfer system 380, the transfer system can be automated, or controlled, 12

ES 2 623 907 T3 by an automatic control system 390, as illustrated in Figures 4a and 4b. Although not specifically depicted in the embodiments illustrated in Figures 4c and 4d, it is to be understood that such control systems 390 can also be used in these embodiments. The automatic control system 390 can be used to control the movement and / or timing of at least one of the first and second balancing valves 330, 336, the first and second gate valves 332, 338, and the first and second gate valves. second transfer device 381, 382 of the automatic article transfer system 380. In one embodiment, the control system 390 can adjust the position, speed, and / or timing of these devices or elements to ensure that the carriers within the system move in a continuous and constant manner.

Turning now to Figures 5a-5d, an embodiment of a gate shutter device 420 is provided, suitable for use as a gate device 332 and / or 338 in the microwave system portion 310 illustrated in Figures 4a. and 4b. The shut-off gate valve device 420 is illustrated in Figures 5a-d generally comprising a pair of spaced apart fixed elements 410, 412 having opposing sealing surfaces 414a, b and defining a gate receiving space 416 therebetween. Each of the spaced apart fixed elements 410, 412 may define a flow opening 418a, b, which is bounded by one of the sealing surfaces 414a, b. Each of the flow openings 418a, b is substantially aligned with one another so that articles can pass through the cumulative opening when the gate valve device 420 is open.

The closing gate device 420 further comprises a gate assembly 422, which is configured to be received within the gate receiving space 416 and is movable therein between a closed position (as shown in the Figures 5b and 5c), in which gate assembly 422 substantially blocks flow openings 418a, b, and an open position (as shown in Figure 5a), wherein the gate assembly 422 does not substantially block the flow ports 418a, b. In one embodiment, gate assembly 422 comprises a pair of spaced apart seal plates 424, 426 and an actuator 428 disposed between seal plates 424, 426. When gate assembly 422 is configured in the closed position, actuator 428 is movable, relative to sealing plates 424, 426, between a retracted position (as shown in Figure 5b) and an extended position (as shown in Figure 5b). shown in Figure 5c). In one embodiment shown at 5a-c, gate assembly 422 comprises at least one pair of bearings 430 disposed within the space defined between opposing sealing plates 424, 426, which is located in gate receiving space 416 when the assembly gate 422 is in a closed position, as particularly shown in Figures 5b and 5c. When the actuator 428 is moved from a retracted position, as illustrated in Figure 5b, to an extended position, as depicted in Figure 5c, at least one bearing of pair 430 can force at least one of the plate plates. sealing 424, 426 outwardly, moving both away from each other and into a sealing position, as shown in Figure 5c.

[0050] In one embodiment, one or more of the pair 430 bearings may be secured, clamped, or at least partially housed within at least one of the sealing plates 424, 426 and / or actuator 428. According to one embodiment , at least one of the bearings 430a may be fixedly attached to the actuator 428, as shown in the enlarged partial view of the gate assembly 422 provided in Figure 5d. As actuator 428 travels downward into gate receiver space 416, one of the pair's bearings 430a may contact one of the sealing plates 424, 426 (shown as plate 426 in Figure 5d ) and can move along a ramp (or slot) 427 of them. As the bearing travels through slot 427 (or along ramp 427), an outward pressure is exerted on seal plate 426, thereby moving it in a direction as indicated by arrow 460. A Although it is shown to include a single pair of bearings 430, it should be understood that any number of bearings can be used, positioned along the vertical length of actuator 428 and / or sealing elements 424, 426.

[0051] When in a sealing position, as shown in Figure 5c, at least a portion of the sealing plates 424, 426 physically engages or contacts the respective one of the opposing sealing surfaces 414a, b, thereby forming a substantially fluid-tight seal. In one embodiment, each of the sealing plates 424, 426 comprises a resilient seal 423, 425 for engaging the sealing surfaces 414a, b when the sealing plates 424, 426 are in the sealing position. When the actuator 428 is moved from the extended position, as shown in Figure 5c, back to the retracted position, as shown in Figure 5b, the sealing plates 424, 426 retract towards each other at the unsealed position, as shown in Figure 5b. In the unsealed position, the seal plates 424, 426 disengage from the opposing seal surfaces 414a, b, but can remain disposed within the gate receiving space 416. In one embodiment, the seal plates 424, 426 may deflect toward the unsealed position and may include at least one deflection device 429 (eg, a spring or springs) to bias seal plates 424, 426 toward the unsealed position.

ES 2 623 907 T3

[0052] Referring again to Figures 1a and 1b, articles that leave the thermalization zone 12, and optionally pass through the pressure setting zone 14a, as described, can then be introduced into the thermalization zone. microwave heating 16. In microwave heating zone 16, articles can be rapidly heated with a heat source using microwave energy. As used herein, the term microwave energy refers to electromagnetic energy with a frequency between 300 MHz and 30 GHz. In one embodiment, various configurations of microwave heating zone 16 can utilize microwave energy with a frequency of about 915 MHz. or a frequency of about 2.45 GHz, both of which have been designated industrial microwave frequencies. In addition to microwave energy, microwave heating zone 16 can optionally utilize one or more heat sources such as, for example, conductive or convective heating or other conventional heating methods or devices. However, at least 85 percent, at least 90 percent, at least 95 percent, or substantially all of the energy used to heat the items within microwave heating zone 16 may be microwave energy of a microwave source.

According to one embodiment, the microwave heating zone 16 can be configured to increase the temperature of the articles above a minimum threshold temperature. In an embodiment where microwave system 10 is configured to sterilize multiple items, the minimum threshold temperature (and the minimum operating temperature of microwave heating zone 16) can be at least about 120 ° C, at least about 121 ° C, at least about 122 ° C and / or not more than about 130 ° C, not more than about 128 ° C, or not more than about 126 ° C. The microwave heating zone 16 may operate at approximately ambient pressure, or it may include one or more pressurized microwave chambers operating at a pressure of at least about 5 psig, of at least about 10 psig, of at least about 15 psig, and / or not more than about 80 psig, not more than about 60 psig, or not more than about 40 psig. In one embodiment, the pressurized microwave chamber may be a liquid-filled chamber with an operating pressure such that the items being heated can reach a temperature above the normal boiling point of the liquid medium employed therein.

The articles that pass through the microwave heating zone 16 can be heated to the desired temperature in a relatively short period of time which, in some cases, can minimize damage or degradation of the articles. In one embodiment, articles passing through microwave heating zone 16 may have an average residence time of at least about 5 seconds, of at least about 20 seconds, of at least about 60 seconds, and / or no. more than about 10 minutes, no more than about 8 minutes, or no more than about 5 minutes. In the same or other embodiments, microwave heating zone 16 may be configured to increase the average temperature of the items being heated by at least about 20 ° C, by at least about 30 ° C, by at least about 40 °. C, at least about 50 ° C, at least about 75 ° C and / or not more than about 150 ° C, at not more than about 125 ° C, or not more than about 100 ° C, at a rate of heating of at least about 15 ° C per minute (° C / min), at least about 25 ° C / min, at least about 35 ° C / min and / or not more than about 75 ° C / min, not more than about 50 ° C / min, or not more than about 40 ° C / min.

Turning now to Figure 6a, one embodiment of a microwave heating zone 516 is illustrated as generally comprising a microwave heating chamber 520, at least one microwave generator 512 for generating microwave energy, and a system of microwave distribution 514 to direct at least a portion of the microwave energy from generator 512 to microwave chamber 520. Microwave distribution system 514 comprises multiple waveguide segments 518 and one or more microwave launchers, shown as launchers 522a-f in Figure 6a, to discharge microwave energy into microwave chamber 520. As Shown in Figure 6a, microwave heating zone 516 may further comprise a conveyor system 540 for conveying items 550 to be heated through microwave chamber 520. Each of the components of microwave heating zone 516 according to various embodiments of the present invention is immediately discussed in detail.

The microwave generator 512 can be any suitable device for generating microwave energy of a desired wavelength (λ). Examples of suitable microwave generator types may include, but are not limited to, magnetrons, klystrons, traveling wave tubes, and gyro-trons. Although illustrated in Figure 6a as including a single generator 512, it should be understood that microwave heating system 516 can include any number of generators arranged in any suitable configuration. For example, in one embodiment, microwave heating zone 516 may include at least 1, at least 2, at least 3, and / or no more than 5, no more than 4, or no more than 3 microwave generators, depending of the size and layout of the microwave distribution system 514. Specific embodiments of a microwave heating zone including multiple generators will be discussed in detail below.

[0057] Microwave chamber 520 can be any chamber or container configured to receive multiple items. Microwave chamber 520 can be of any size and can have one of a variety of different shapes in section. For example, in one embodiment, chamber 520 may have a cross section of 14

ES 2 623 907 T3 is generally circular or elliptical, while, in other embodiments, it may have a generally square, rectangular or polygonal cross-sectional shape. In one embodiment, microwave chamber 520 may be a pressurized chamber and, in the same or other embodiments, may be configured to be at least partially filled with a liquid medium (a liquid-filled chamber). Microwave chamber 520 may also be configured to receive at least a portion of the microwave energy discharged from one or more microwave launchers 522 and, in one embodiment, may be configured to allow formation of a stable wave pattern (or stationary) in it. In one embodiment, at least one dimension of microwave chamber 520 may be at least about 0.30λ, at least about 0.40λ, or at least about 0.50λ, where λ is the wavelength of microwave energy discharged into it.

[0058] Microwave distribution system 514 comprises multiple waveguides or waveguide segments 518 to direct at least a portion of microwave energy from generator 512 to microwave chamber 520. Waveguides 518 may be designed and constructed to propagate microwave energy of a specific predominant mode, which may be the same or different than the mode of microwave energy generated by generator 512. As used herein, the term "mode" refers to a generally fixed cross-sectional field model of microwave energy. In one embodiment of the present invention, waveguides 518 can be configured to propagate microwave energy in a TExy mode, where x and y are integers within the range of 0 to 5. In another embodiment of the present invention, waveguides 518 may be configured to propagate microwave energy in a TMab mode, where a and b are integers within the range of 0 to 5. It should be understood that, as used herein, the above defined ranges of Values ​​a, b, x, and y as used to describe a microwave propagation mode are applicable throughout this description. In one embodiment, the predominant mode of microwave energy propagated through waveguides 518 and / or discharged by launchers 522a-f may be selected from the group consisting of TE10, TM01, and TE₁₁.

As shown in Figure 6a, a microwave distribution system 514 further comprises one or more microwave launchers 522a-f, each defining at least one launch opening 524a-f for discharging microwave energy into a chamber. microwave 520. Although illustrated in Figure 6a as including six microwave launchers 522a-f, it should be understood that microwave distribution system 514 may include any number of launchers arranged in any desirable configuration. For example, a microwave distribution system 514 may include at least 1, at least 2, at least 3, at least 4, and / or no more than 50, no more than 30, or no more than 20 microwave launchers. Launchers 522a-f can be of the same or different types of launchers and, in one embodiment, at least one of launchers 522a-f can be replaced with a reflective surface (not shown) to reflect at least a portion of the energy from microwave discharged from the other launchers 522 into microwave heating chamber 520.

[0060] When microwave distribution system 514 includes two or more launchers, at least some of the launchers may be generally disposed on the same side of microwave chamber 520. As used herein, the words "same side launchers" refer to two or more launchers generally located on the same side of a microwave chamber. Two or more launchers on the same side may also be axially spaced from each other. As used herein, the term "axially spaced" refers to spacing in the direction of transport of the articles through the microwave system (ie, spacing in the direction of extension of the transport shaft). In addition, one or more launchers 522 may also be laterally spaced from one or more launchers 522 in the system. As used herein, the term "laterally spaced" refers to spacing in the direction perpendicular to the direction of transport of the articles through the microwave system (ie, spacing perpendicular to the direction of extension of the transport axis). For example, in Figure 6a, launchers 522a-c and 522d-f are disposed on respective first and second sides 521a, b of microwave chamber 520 and launcher 522a is axially spaced from launcher 522b and 522c, as is the launcher 522e is axially spaced from launchers 522f and 522d.

[0061] Furthermore, as shown in the embodiment depicted in Figure 6a, the microwave distribution system 514 may comprise at least two (eg, two or more) pairs of launchers arranged facing or opposite each other. As used herein, the term "opposed launchers" refers to two or more launchers located on generally opposite sides of a microwave chamber. In one embodiment, the opposing launchers may face each other. As used herein with respect to opposed microwave launchers, the term "faced" will denote launchers whose central launch axes are substantially aligned with each other. For simplicity, the launch center axis 523c of the launcher 522c and the launch center axis 523d ​​of the launcher 522d are the only launch center axes illustrated in Figure 6a. However, it should be understood that each of the launchers 522a-f includes similar launch shafts.

The opposing launchers may be generally aligned with one another, or they may be offset from one or more other launchers disposed on the opposite side of microwave chamber 520. In one embodiment, a 15

ES 2 623 907 T3 pair of opposed launchers may be a pair of staggered launchers, so that the discharge openings 524 of launchers 522 are not completely aligned with each other. Pitchers 522^to and 522e constitute an exemplary pair of opposed launchers arranged in an offset configuration. Offset opposing launchers may be offset from one another axially or laterally. As used herein with respect to opposed microwave launchers, the term "axially offset" refers to launchers whose central launch axes are axially spaced from each other. As used herein with respect to opposed microwave launchers, the term "laterally staggered" refers to launchers whose central launch axes are laterally spaced from each other. In another embodiment, a pair of opposed launchers may be directly opposed launchers, such that the discharge openings of the pair of launchers are substantially aligned. For example, launchers 522c and 522d shown in Figure 6a are configured as a pair of opposed launchers.

[0063] In some embodiments, microwave heating zone 516 may include two or more transport lines that operate simultaneously with each other. An exemplary multi-line conveyor system 540 is shown in Figures 6b and 6c. As shown in Figures 6b and 6c, conveyor system 540 may be configured to convey multiple items 550 in a conveying direction generally represented by arrow 560 in Figure 6b. In one embodiment, conveyor system 540 may include at least two substantially parallel and laterally spaced conveyor lines, such as, for example, first, second, and third conveyor lines 542a-c shown in Figure 6b. Conveyor lines 542a-c may, in one embodiment, comprise individual conveyor systems, while, in another embodiment, each conveyor line 542a-c may be parts of a complete conveyor system. Conveyor system 540 and / or conveyor lines 542a-c can be any type of suitable conveyor or conveyor system, including those previously discussed in detail.

The microwave heating system 516 depicted in Figures 6b and 6c includes multiple microwave launchers 522 that may be divided or organized into at least two groups of two or more microwave launchers. Each of the first, second, and third transport lines 542a-c can be configured to receive microwave energy from respective first, second, and third groups of microwave launchers. In one embodiment, a launcher group may refer to one or more axially spaced launchers, generally positioned along the direction of transport (e.g., launcher group 522a-d, launcher group 522e-h, and / or the group of launchers 522i-l shown in Figure 6b), while, in the other embodiment, a group of launchers may include one or more pairs of opposing launchers located on different sides of a microwave chamber (for example, groups that include a pair of 522a and 522m launchers, the group that includes pair of 522b and 522n launchers, group that includes pair of 522c and 522o launchers, and a group that includes pair of 522d and 522p launchers, as shown in Figure 6c). When the group of launchers comprises one or more pairs of opposed launchers, the launchers may be arranged in a staggered configuration (not shown) or may be directly opposite each other (for example, facing each other), as illustrated in Figure 6c. . According to one embodiment, at least one generator, shown as generator 512a in Figure 6b, may be configured to supply microwave energy to at least one group of microwave launchers.

[0065] As particularly shown in Figure 6b, individual microwave launchers 522 from adjacent conveying lines 542 may be arranged in a staggered configuration relative to each other in the conveying direction. In one embodiment, one or more microwave launchers on the same side 522a-1 may be axially offset from each other. For example, in the embodiment shown in Figure 6b, launchers 522a-d associated with the first conveyor line 542a are arranged in an offset configuration with respect to each of the respective launchers 522e-h associated with the second conveyance line. 542b with respect to and / or along the direction of transport 560. As used herein with respect to same side microwave launchers, the term "axially offset" will denote launchers that are axially spaced from each other by a distance greater than 1/2 the maximum axial dimension of the launcher launch openings. As used herein with respect to same-sided microwave launchers, the term laterally offset will denote launchers that are laterally spaced from one another by a distance greater than 1/2 of the maximum lateral dimension of the launch openings of the launchers.

Furthermore, in the same or another embodiment, the microwave launchers associated with non-adjacent conveyor lines (eg, first and third conveyor lines 542a, c) may be arranged in substantially aligned configurations with each other, such as it is illustrated in launcher arrangements 522a-d relative to launchers 522i-I shown in Figure 6b. Alternatively, at least a portion of launchers 522i-l associated with third conveying line 542c may be offset relative to launchers 522a-d of first conveying line 542a and / or second conveying line 542b (embodiment not shown) . Although generally depicted in Figure 6b as including little or no space between adjacent conveyor line launchers, it should be understood that, in one embodiment, there may be some space between line launchers 16

Adjacent ES 2 623 907 T3 (eg 522a and 522e launchers, 522b and 522f launchers, etc.). In addition, individual launchers 522 may have any suitable design or configuration and, in one embodiment, may include at least one feature of one or more embodiments of the present invention that will be described in detail herein.

Turning now to Figure 7a, a partial view of one embodiment of a microwave heating zone 616 is shown. The microwave heating zone 616 includes at least one microwave launcher 622 that defines a launch opening 624 for discharge energy into a microwave chamber 620. As shown in Figure 7a, microwave launcher 622 is configured to discharge microwave energy along a central launch axis 660 toward a conveyor system 640 configured to transport multiple items 650 within microwave chamber 620 along the way. along a transport shaft 642. In one embodiment, the central launch axis 660 may be inclined such that an inclined launch angle, β, is defined between the central launch axis 660 and a plane normal to the transport axis 642, illustrated as plane 662 in FIG. 7a. According to one embodiment, the launch tilt angle β can be at least about 2 °, at least about 4 °, at least about 5 ° and / or not more than about 15 °, not more than about 10 °. , or no more than about 8 °.

Turning now to Figure 7b, another embodiment of a microwave heating system 616 is shown including two or more launchers 622a-c, each configured to discharge energy into microwave chamber 620 along respective axes. 660a-c inclined launch centers. In an embodiment where the microwave heating system 616 includes two or more inclined launchers, the central launch axes of the launchers, especially the launchers on the same side, may be substantially parallel to each other, as generally illustrated by the axes launch centers 660a, b of launchers 622a, b shown in Figure 7b. As used herein, the term "substantially parallel" means within 5 ° of parallelism. In the same or another embodiment, the central launch axes of two or more launchers, especially opposing launchers, within the microwave heating zone 616 may be substantially parallel or substantially aligned, as illustrated by launch axes 660a, c of microwave launchers 622a, c in Figure 7b. When the microwave heating zone 616 comprises n inclined microwave launchers having central launch axes oriented as described above, each launcher may define a respective launch inclination angle at, within the ranges described above. In one embodiment, each of the launch pitch angles in of each launcher may be substantially the same, while, in another embodiment, at least one of the pitch pitch angles in may be substantially different from one or more of the other launch tilt angles.

[0069] Referring again to Figure 6a, at least one of the launch openings 524a-f of the launchers 522a-f of the microwave system 516 may be at least partially covered by a substantially microwave transparent window 526a-f arranged between each launch opening 524a-f and the microwave chamber 520. The microwave transparent windows 526a-f can function to prevent fluid flow between the microwave chamber 520 and the microwave launchers 522a-f while allowing a substantial portion of the microwave energy from the launchers 522a-f to pass through. its through. The 526a-f windows can be made of any suitable material, including, but not limited to, one or more thermoplastic materials or glasses such as glass-filled Teflon, polytetrafluoroethylene (PTFE), polymethylmethacrylate (PMMA), polyetherimide ( PEI), aluminum oxide, glass, and combinations thereof. In one embodiment, windows 526a-f may have an average thickness of at least about 4mm, at least about 6mm, at least about 8mm, and / or not more than about 20mm, not more than about 16mm, or no more than about 12mm and can withstand a pressure difference of at least about 40 psi, at least about 50 psi, at least about 75 psi, and / or not more than about 200 psi, from not more than about 150 psi, or not more than about 120 psi without breaking, cracking, or otherwise damaged.

[0070] Figures 8a-c generally depict various embodiments of suitable configurations for microwave launcher windows. As shown in Figures 8a-c, each of the microwave windows 726 defines a chamber side surface 725 that may optionally define at least a portion of the side wall 721 of the microwave chamber 720. According to one embodiment shown in Figure 1, the surface of the camera side 725 of the window 726 can be configured such that at least 50 percent, at least 65 percent, at least 75 percent, at least one 85 percent, or at least 95 percent of the total surface area of ​​the camera side 725 is oriented at an angle of inclination, α, from the horizontal. The angle of inclination α can be at least about 2 °, at least about 4 °, at least about 8, at least about 10 ° and / or not more than about 45 °, not more than about 30 °, or no more than about 15 ° from the horizontal, illustrated as a dotted line 762. In other embodiments, the angle of inclination, α, may also be defined between the axis of elongation 762 of the microwave chamber 720 and / or a transport axis (not shown in Figures 8a-c) when, for example, these axes are parallel to horizontal.

[0071] The chamber side surface 725 of the window 726 may be oriented from the horizontal

ES 2 623 907 T3 regardless of whether the launcher 722 is oriented with a pitch angle, as described above, or not. In one embodiment, window 726 may be substantially flat and sloped from horizontal (as shown in Figure 8a), while, in the same or another embodiment, the chamber-side surface 725 of window 726 may include a or more convexities (as shown in Figure 8b) or concavities (as shown in Figure 8c). When the chamber-side surface 725 is not substantially flat, one or more (on) total slant angles can be formed as described above. Depending on the exact configuration of the camera-side surface 725, the multiple tilt angles formed by it may be the same or different from other tilt angles formed by the same surface 725.

[0072] As previously discussed, the microwave launchers 522a-f depicted in Figure 6a may have any suitable configuration. Various views of a microwave launcher 822 configured in accordance with one embodiment of the present invention are provided in Figures 9a-f. Referring initially to Figure 9a, microwave launcher 822 is illustrated as comprising a set of opposite side walls 832a, b, and a set of opposite end walls 834a, b, which collectively define a substantially rectangular launch opening 838. When the launch opening 838 comprises a rectangular shaped opening, it may have a width (W1) and a depth (D1) defined, at least in part, by the end edges of the side walls 832a, b and 834a, b, respectively. In one embodiment, the side walls 832a, b may be wider than the end walls 834a, b, so that the length of the lower end edge of the side walls 832a, b, shown as W1 in Figure 9a, may be greater. than the length of the lower end edge of the end walls 834a, b, shown in Figure 9a with the identifier D1. As shown in Figure 9a, the elongated portion of side walls 832a, b, and end walls 834a, b may also collectively define a path 837 through which microwave energy can propagate as it passes from the microwave input. 836 to the at least one launch opening 838 defined by launcher 822.

[0073] When used to discharge microwave energy into a microwave chamber, the launch opening 838 may be elongated in the direction of extension of the microwave chamber (not shown) or in the direction of conveying the articles therein. . For example, in one embodiment, the side walls 832a, b, and end walls 834a, b of the launcher 822 can be configured such that the maximum dimension of the launch opening 838 (shown in Figure 9a as W1) can be aligned substantially parallel to the direction of extension of the microwave chamber and / or the direction of transport of the articles passing through it. In this embodiment, the end edges of the side walls 832a, b can be oriented parallel to the direction of extension (or the direction of transport), while the end edges of the end walls 843a, b can be aligned substantially perpendicular to the direction extension or transport within the microwave chamber (not shown in Figure 9).

[0074] Figures 9b and 9c respectively provide views of a side wall 832 and an end wall 834 of the microwave launcher 822 illustrated in Figure 9a. It should be understood that, while only one of the side or end walls 832, 834 is shown in Figures 9b and 9c, the other of the pair may have a similar configuration. In one embodiment, at least one of the side wall 832 and the end wall 834 can be flared so that the inlet dimension (width W0 or depth D0) is smaller than the outlet dimension (width W1 or depth D1), as illustrated respectively in Figures 9b and 9c. When flared, each of the side and end walls 832, 834 defines respective flare width and depth angles, 0w and 0d, as shown in Figures 9b and 9c. In one embodiment, the flare width and / or depth angles 0w and / or 0d may be at least about 2 °, at least about 5 °, at least about 10 °, or at least about 15 °. and / or not more than about 45 °, not more than about 30 °, or not more than about 15 °. In one embodiment, the flare width and / or depth angles 0w and 0d may be the same, while, in another embodiment, the values ​​of 0w and 0d may be different.

According to one embodiment, the flare depth angle 0d may be less than the flare width angle 0w. In some embodiments the flare depth angle 0d may be no more than about 0 °, such that the inlet depth D0 and the outlet dimension D1 of the microwave launcher 822 are substantially the same, as illustrated in the illustrated embodiment. in Figure 9d. In another embodiment, the flare depth angle 0d may be less than 0 °, so that D1 is less than D0, as shown in Figure 9e. When the launcher 822 comprises a flare depth angle of less than 0 ° and / or the depth D1 of the launch opening 838 is less than the depth D0 of the microwave inlet 836, the microwave launcher 822 may be a launcher frustoconical with a generally inverse profile. In an embodiment where the microwave launcher 822 comprises n launch openings, between 1 and n of the openings may have a depth and / or width less than or equal to the depth and / or width of the launcher's entrance. Additional embodiments of multi-aperture launchers are described in detail below.

ES 2 623 907 T3

According to one embodiment of the present invention, the depth Di of the launch opening 838 may be no more than about 0.625 λ, no more than about 0.5 λ, no more than about 0.4 λ, no more than about 0.35 λ, or no more than about 0.25 λ, where λ is the predominant mode wavelength of microwave energy discharged from launch port 838. While wishing not to be bound by theory, it is believed that by minimizing the depth Di of launch opening 838, the microwave field created near launch opening 838 is more stable and uniform than would be created with launchers having greater depths. In an embodiment where the microwave launcher 822 comprises n launch openings, the depth of each launch opening, dn, may be no greater than about 0.625 λ, no greater than about 0.5 λ, no greater than about 0, 4 λ, not greater than about 0.35 λ, or not greater than about 0.25 λ. When the microwave launcher 822 has multiple openings, each opening can have a depth that is the same or different than one or more of the other launch openings on the same launcher.

[0077] Referring now to Figures i0a-c., Another embodiment of a microwave launcher 922 suitable for use in microwave heating systems described herein is illustrated as comprising a single microwave inlet 936 and two or more launch openings. , shown as launch or discharge ports 938a-c, for discharging microwave energy from them. The microwave launcher 922 illustrated in Figures i0a-c includes separate first, second, and third launch openings 938 ac, which are laterally spaced from each other. Although it has been described herein as defining three launch openings, it should be understood that the launcher 922 may include any suitable number of launch openings, including at least 2, at least 3, at least 4 and / or no more than i0. , no more than 8, or no more than 6. The spacing between each first, second, and third launch apertures 938a-c can be at least about 0.05 λ, at least about 0.075 λ, or at least about 0.10 λ, and / or no more than about 0.25 λ, no more than about 0, i5 λ, or no more than about 0, i λ, where λ is the wavelength of the predominant mode of microwave energy discharged from launcher 922.

[0078] In one embodiment, each of the first, second, and third launch openings is separated by one or more partitions 940a, b disposed within the interior of launcher 922, as shown in Figures i0a-c. The partitions 940a, b normally have a thickness equal to the desired spacing between the discharge openings 938a-c. When the microwave launcher comprises n partitions, the microwave launcher 922 defines (n + i) separate launch openings and (n + i) separate microwave pathways 937a-c defined between the microwave inlet 836 and each launch opening 938a. -c, as shown particularly in Figure i0c. As shown in Figure i0c, each of the microwave paths 937a-c has a length, Li-L₃, which extends from the inlet 936 to a point perpendicular to the respective launch opening 938a-c. Each Li- L₃ it can be substantially the same, or at least one of the Li, L2, and L3 can be substantially different. According to one embodiment, particularly shown in Figure i0c, one or more paths 937a-c may be longer than one or more other paths 937a-c.

[0079] When one or more paths 937a-c are of different lengths than one or more distinct paths, the dimensions (Li, L2, and / or L3) of paths 937a-c can be adjusted so that the phase velocity of the microwave energy propagating through it accelerates at a faster rate within the longer microwave paths (for example, Li and L3 in Figure i0c) than through the shorter paths (for example, L2 in Figure i0c). While the theory is not intended to condition, the hypothetical case is that such adjustment can be carried out to ensure uniform synchronization of the individual wave portions, thus creating a uniform wavefront as microwave energy is discharged. in chamber 520. When microwave launcher 922 includes a single partition, only two microwave paths are created (embodiment not shown) and the length of each path is substantially the same. Therefore, little or no control of the phase velocity of the microwave energy passing through paths of equal length may be necessary.

In the same or another embodiment, each of the launch openings 938a-c can define a depth, di-₃, as generally represented in Figure i0b. In one embodiment, each of the depths from di to d3 may be substantially the same, while, in another embodiment, at least one of the depths did3 may be different. As discussed earlier, one or more of the di-d3 can be no more than about 0.625λ, no more than about 0.5λ, no more than about 0.4λ, no more than about 0.35λ, or no more than about 0.25λ, where λ is the predominant mode wavelength of microwave energy discharged from launch port 938a-c. Furthermore, in one embodiment, at least one of the dimensions di-d3 may be less than or equal to the depth du of the inlet 936, as previously described in detail. As shown in Figure i0b, the depths, di-₃, of each of the launch openings 938a-c do not include the thickness of the partitions 940a, b, when present.

[008i] Again referring to Figures 6a, in one embodiment, the microwave distribution system 5i4 of the microwave heating zone 5i6 may include at least one microwave distribution device 525a, b for allocating or distributing energy from microwave in chamber 520 by multiple launchers 522a-c and 522d-f. On

In one embodiment, the microwave distribution manifold 525a, b may include at least three microwave allocation devices configured to divide the microwave energy from the generator 512 into two or more separate portions before discharging them from at least some of microwave launchers 522a-f. As used herein, the term "microwave allocation device" refers to any device or article that functions to divide microwave energy into two or more separate portions, according to a predetermined relationship. As used herein, the term "predetermined energy ratio" refers to the ratio of the amount of energy of each resulting separate portion exiting a specific microwave allocation device. For example, a microwave allocation device configured to divide the energy that passes through it at a 1: 1 energy ratio would be configured to divide the power that is introduced into it into two substantially equal portions.

[0082] However, in one embodiment of the present invention, at least one of the microwave allocation devices, shown as inductive irises 570a-h and T-shaped or splitter or two-way 572 in Figure 6a, of the system Microwave distribution switch 514 may be configured to have a predetermined power ratio other than 1: 1. For example, one or more 570ah or 572 microwave allocation devices may be configured to divide the microwave energy passing through them according to a predetermined energy ratio of at least about 1: 1.5, from at least about 1: 2, at least close to 1: 3 and / or no closer than 1:10, no closer than 1: 8, or no closer than 1: 6.

Each of the 570a2-h and / or 5 allocation devices used by the microwave distribution system 514 can be configured to discharge energy according to the same ratio, or one or more 570ah allocation devices can be configured with a power ratio different. The allocation devices 570a-h and 572 may be configured so that substantially the same amount of power is discharged from each of the launchers 522a-f, while, in another embodiment, the allocation devices 570a-h and 572 may be collectively designed to deflect and discharge more power from one or more launchers 522a-f, discharging less power through the rest of the launchers 522a-f. The specific power ratios used by each of the 570a-h and 572 microwave allocation devices, as well as the general pattern or configuration of microwave power allocation within the system, can depend on a variety of factors including, for for example, the type of items being heated, the desired operating conditions of the microwave heating zone 516, and the like.

[0084] In practice, an initial amount of microwave energy can be fed into microwave distribution system 514 and may be divided into two portions as it passes through divider 572. In one embodiment, the two portions of microwave energy that output from divider 572 may be of approximately the same power, while, in another embodiment, one of the two portions may have more power than the other. As shown in Figure 6a, each portion can pass to a respective manifold 525a, b, optionally passing through phase change device 530 before entering manifold 525a, b. Described now with respect to microwave distribution manifold 525a, it should be understood that an analogous operation is applicable to a lower manifold 525b shown in Figure 6a.

[0085] Microwave power exiting divider 572 and optionally phase shift device 530 (embodiments to be described in detail below) can then pass through a microwave allocation device, shown as iris 570a, where the power can be divided into a first launch microwave fraction and a first distribution microwave fraction. The first launch microwave fraction may be directed toward launcher 522a and may be discharged through outlet 524a. The first distribution microwave fraction can be propagated down the waveguide 518 to the additional microwave launchers 522b, c. According to one embodiment, the power ratio of the first launch microwave fraction to the first distribution microwave fraction exiting the iris 570a may be no greater than about 1: 1, no greater than about 0.95: 1, not greater than about 0.90: 1, not greater than about 0.80: 1, not greater than about 0.70: 1, or not greater than about 0.60: 1. In one embodiment, the power ratio of the first launch microwave fraction to the first distribution microwave fraction is not 1: 1.

[0086] As the first distribution microwave fraction propagates towards launchers 522b, it can subsequently be divided into a second launch microwave fraction directed towards launcher 522b that will be discharged via launch outlet 524b, and a second distribution microwave fraction propagating downwardly through waveguide 518 toward launcher 522c. In one embodiment, the ratio of the second launch microwave fraction to the second distribution microwave fraction can be at least about 0.80: 1, at least about 0.90: 1, at least about 0.95: 1 and / or no more than about 1.2: 1, no more than about 1.1: 1, no more than about 1.05: 1, or it can be about 1: 1. Subsequently, the remainder of the microwave energy (eg, the entirety of the second distribution microwave fraction) can then be directed to the final microwave launcher 522c and discharged from the launch outlet 524c.

ES 2 623 907 T3

According to another embodiment (not shown in Figure 6a), the microwave distribution system 514 may include a microwave distribution manifold 525a, b having more than three launchers. For example, when the microwave distribution manifold 525 includes n launchers, all stages except stage (n-1) of division can be carried out such that the ratio of the fraction of launching microwaves to the fraction of microwave distribution is not 1: 1. For each of the stages except stage (n-1), the power ratio can be no greater than about 1: 1, no greater than about 0.95: 1, no greater than about 0.90: 1, not greater than about 0.80: 1, not greater than about 0.70: 1, or not greater than about 0.60: 1, while the division stage (n-1) can be carried out such that the ratio from the launch microwave fraction to the second distribution microwave fraction can be at least about 0.80: 1, at least about 0.90: 1, at least about 0.95: 1 and / or not more than about 1.2: 1, not more than about 1.1: 1, not more than about 1.05: 1, or it can be about 1: 1. The distribution microwave fraction (n-1) can then be sent, mostly or all, as a launch microwave fraction n to be discharged into the microwave chamber by microwave launcher n.

[0088] In addition to one or more irises 570a-h positioned within microwave distribution system 514, one or more launchers 522 may also include at least one inductive iris disposed within the launcher, as shown in an embodiment illustrated in the Figures 11a and 11b. Alternatively, one or more irises 570b and / or 570d may be arranged within launchers 522a and / or 522b, respectively, instead of being arranged within a waveguide as shown in Figure 6a.

[0089] An embodiment of a microwave launcher 1022 is shown in Figure 11a that includes an inductive iris disposed therein. Launcher 1022 may include at least one inductive iris 1070 located between its microwave input 1036 and one or more launch apertures 1038, as generally illustrated in Figures 11a and 11b. As shown in Figures 11a and 11b, iris 1070 can be defined by a pair of inductive iris panels 1072a, b arranged on opposite sides of launcher 1022. Although shown as being coupled to opposite narrower end walls 1034a, b of launcher 1022, it should be understood that the first and second iris panels 1072a, b may also be coupled to opposite side walls 1032a, b wider of launcher 1022 As shown in Figures 11a and 11b, The first and second iris panels 1072a, b extend inwardly in the microwave pathway 1037 defined between the microwave inlet 1036 and the launch opening 1038 in a direction that is generally transverse to the direction of microwave propagation through road 1037. In one embodiment, the iris panels obstruct at least 25 percent, at least 40 percent, or at least 50 percent, and / or no more than 75 percent, no more than 60 percent, or no more than 55 percent of the total area of ​​the microwave path 1037 in the situation in which they are arranged. When the microwave launcher 1022 comprises two or more launch openings, as shown in Figure 11c, the first and second iris panels 1072a, b may be configured to obstruct at least a portion of each of the launch openings 1038a. -c from launcher 1022.

As shown in Figure 11a, the first and second iris panels 1072a, b can be substantially coplanar and can be substantially normal to the central launch axis of the microwave launcher 1022. In some embodiments, the iris panels 1072a , b can be spaced from both the microwave inlet 1036 and the launch opening 1038 of the microwave launcher 1022. For example, the iris panels 1072a, b may be separated from the microwave input 1036 of the launcher 1022 by at least 10 percent, at least 25 percent, or at least 35 percent of the minimum distance between the microwave inlet 1036 and launch opening 1038 of launcher 1022. Additionally, the iris panels 1072a, b may be spaced from the launch opening 1038 of the launcher 1022 by at least 10 percent, 25 percent, or 35 percent of the maximum distance (L) measured between the microwave input. 1036 and the launch opening 1038 of the launcher 1022.

Returning again to Figure 6a, the microwave distribution system 514 is illustrated as further comprising one or more devices or to increase the uniformity and / or intensity of the microwave field created within the microwave heating chamber 520 . For example, in one embodiment, the microwave distribution system 514 may include one or more devices designed to modify and / or control the location and intensity of the constructive interference bands of the microwave field created within each individual heating zone 580a. -c, which are respectively defined between launcher pairs 522a and 522f, 522b and 522e, and 522c and 522d. In one embodiment, said device may be a phase change device, schematically shown in Figure 6a as device 530, operable to cyclically change the phase of microwave energy passing through it.

[0092] As items 550 move along conveyor system 540 within microwave chamber 520, each item 550 can have an average residence time (τ), within each individual heating zone 580a-c , of at least about 2 seconds, of at least about 10 seconds, of at least about 15 seconds and / or of not more than about 1 minute, of not more than about 45 seconds, or of not more than about 30 seconds. In one embodiment, the average dwell time (τ) for items 550 may be greater than 21

ES 2 623 907 T3 phase change speed (t) for which the phase change device 530 is configured. For example, the ratio of the average residence time of articles passing through one of the individual zones of 580a-c heating the phase change rate of device 530 (τ: ί) can be at least about 2: 1, at least about 3: 1, at least about 4: 1, at least about 5: 1 and / or no more than about 12: 1, no more than about 10: 1, or no more than about 8: 1.

The phase shifting device 530 can be any suitable device for rapidly and cyclically shifting the phase of microwave energy passing through the microwave distribution system 514. According to one embodiment, phase change device 530 may be configured to shift microwave energy passing through it at a phase change rate (t) of at least about 1.5 cycles per second, of at least about 1.75 cycles per second, or of at least about 2.0 cycles per second and / or of no more than about 10 cycles per second, of no more than about 8 cycles per second, and / or of no more than about 6 cycles per second. As used herein, the term "phase change rate" refers to the number of complete phase change cycles completed per second. A complete phase change cycle refers to a phase change from 0 ° to 180 ° and back to 0 °. Although it is shown to include a single phase change device 530, it should be understood that any suitable number of phase change devices may be utilized within the microwave distribution system 514.

In one embodiment, phase shift device 530 may comprise a plunger-type tuning device capable of operating to move in a generally linear fashion (eg, up-down motion) within a cylinder to thereby cause the phase of microwave energy passing through is cyclically shifted. Figures 12a and 12b illustrate two embodiments of a plunger type tuner device 1130a, b suitable for use in a microwave distribution system 514. Figure 12a depicts a single plunger phase change device 1130a including a plunger 1132 operable to move within a single cylinder 1134 by an automatic actuator 1136. Figure 12b illustrates another embodiment of a phase change device comprising a multiple piston phase change device including a plurality of pistons 1132a-d arranged and operable to move within a number of corresponding cylinders 1134a-d. Plungers 1132a-d may be actuated by a single automatic actuator 1136, which may be connected to each of plungers 1132a-d via a rotatable cam shaft 1138. Any of the plunger-type tuners 1130a, b can be connected to a coupler, such as a short-slot hybrid coupler (not shown in Figures 12a and 12b) and can be used in a microwave distribution system. 514 as a phase change device 530 as described above.

[0095] Another embodiment of a suitable phase change device is shown in Figures 13a-e. Compared to the phase change device or tuning devices illustrated in Figures 12a and 12b, the phase change devices illustrated in Figures 13a-e are rotary phase change devices. For example, as shown in Figures 13a-c, one embodiment of a rotary phase change device 1230, also referred to as a variable phase short, may comprise a fixed section 1210 defining a first substantially rectangular opening 1212 and a rotating section 1240 located proximate said first opening 1212. As shown in Figure 13a, a clearance 1213 may be defined between the rotating section 1240 and the fixed section 1210 and, in one embodiment, a microwave choke (not shown) may be at least partially disposed within the space 1213 to prevent interference. Microwave energy leakage from stationary and rotating sections 1210 and 1240.

[0096] Rotatable section 1240 comprises a housing 1242 and multiple spaced substantially parallel plates 1244a-d received within housing 1242. As shown in Figure 13a, housing 1242 comprises a first end 1243a and a second end 1243b and the first End 1243a defines a second opening 1246 adjacent the first rectangular opening 1212 of fixed section 1210. As indicated by arrows 1290, 1292 in Figure 13a, rotatable section 1240 can be configured to rotate relative to fixed section 1210 about an axis of rotation 1211 extending through first and second openings 1212, 1246, as shown. shown generally in Figures 13a-c.

As shown in particular in Figures 13b and 13c, housing 1242 has a length (Lh), a width (Wh), and a depth (Dh). In one embodiment, at least one of Lh, Wh, and Dh are about 0.5λ, about 0.65λ, about 0.75λ, and / or not more than about 1λ, not more than about 0.9λ. , or no more than about 0.75λ, where λ is the wavelength of microwave energy whose variable phase short circuit 1230 is configured to pass between the first and second openings 1212 and 1246. In one embodiment, at least one of the dimensions Wh and Dh is at least about 0.5λ and both are not more than about λ. As generally shown in Figures 13a-c, the cross-sectional shape of housing 1242 is substantially square, such that the Wh: Dh ratio is no greater than about 1.5: 1, no greater than about 1.25: 1, or no greater than about 1.1: 1.

The fixed section 1210 may be of any suitable shape or size and may comprise a waveguide.

ES 2 623 907 T3 circular or rectangular. In one embodiment shown in Figure 13d, the first substantially rectangular opening 1212 may have a width (Wr) and a depth (Dr) such that the Wr: Dr ratio is at least about 1.1: 1, at less about 1.25: 1, or at least about 1.5: 1. The width of the first apertures 1212 of the fixed section 1210 and the width of the second aperture 1246 of the rotatable section 1240 are substantially equal, such that the ratio Wh: Wr is at least about 0.85: 1, at least about 0.95: 1, or at least about 0.98: 1 and / or no more than about 1.15: 1, no more than about 1.05: 1, or no more than about 1.01: 1.

As shown generally in Figure 13a, each of the plates 1244a-d may be coupled to the second end 1243b of the housing 1242 and may extend generally toward the first end 1243a of the housing 1242 in a direction toward the first. and second openings 1212 and 1244. Each of the plates 1244a-d can have an extension distance or length, shown as Le in Figure 13b, of at least about 0.1λ, of at least about 0.2λ, of at least about 0.25λ. and / or not more than about 0.5λ, not more than about 0.35λ, or not more than about 0.30λ. Additionally, as particularly shown in Figure 13c, one or more of the plates 1244a-d may have a thickness, k, of at least about 0.01λ, of at least about 0.05λ, and / or of no more than about 0.10λ, or no more than about 0.075λ, where λ is the wavelength of microwave energy introduced into housing 1242 through a first aperture 1212. Adjacent plates 1244a-d may be separated by a spacing distance, j, which may be greater than, ones equal to, or less than the thickness of each plate. In one embodiment, j can be at least about 0.01λ, at least about 0.05λ, and / or no more than about 0.10λ, or not more than about 0.075λ. Therefore, in one embodiment, the ratio of the cumulative surface area of ​​the distal ends of the plates 1244a-d, generally illustrated as the shaded regions in Figure 13c, to the total internal exposed surface area of ​​the second end 1243b of the housing 1242, generally illustrated as the unshaded regions in Figure 13c, can be at least about 0.85: 1, at least about 0.95: 1, or at least about 0.98: 1 and / or from no more than about 1.15: 1, no more than about 1.10: 1, or no more than about 1.05: 1.

[0100] Variable phase short circuit 1230 may be configured to rotate at a speed of at least about 50 revolutions per minute (rpm), of at least about 100 rpm, of at least about 150 rpm, and / or of no more than about 50 rpm. 1000 rpm, not more than about 900 rpm, or not more than about 800 rpm around the axis of rotation 1211, as illustrated in Figure 13a. In one embodiment, at least a portion of the movement of the rotary variable phase short circuit 1230 may be accomplished by means of an actuator 1270 coupled to an automatic controller and / or an automatic control system (not shown). In another embodiment, at least a portion of the movement may be carried out manually and may optionally include periods of non-rotation.

[0101] Additional embodiments of rotary phase change devices 1233 and 1235 suitable for use in a microwave distribution system 514 of Figure 6a are illustrated, respectively, in Figures 13e and 13f. As shown in the embodiment depicted in Figure 13e, the rotary phase change device 1233 may include a rotary crank element 1237 coupled by a tie rod 1239 to a plunger 1241 disposed within a waveguide 1243. As crank element 1237 rotates as indicated by arrow 1261, rod 1239 facilitates general up-down movement of piston or plunger 1241 within waveguide 1243, as indicated by arrow 1263 in Figure 13e. Another embodiment of a rotary phase change device 1235 is illustrated in Figure 13f, including a cam 1245 coupled to a rod extension, which may be integrated with or coupled to a plunger 1241 disposed within waveguide 1243. When cam 1245 rotates, rod extension 1247 moves plunger or piston 1241 with a general up-and-down motion within cylinder 1243, as generally indicated by arrow 1263. Also, in accordance with one embodiment, the changeover device Rotary phase 1235 may further comprise one or more diverting devices 1249 (eg, one or more springs) to facilitate movement of plunger 1241 within waveguide 1243 in an upward direction.

[0102] In addition to being used as a rotary phase change device, the variable phase short circuit 1230 (or optionally, the rotary phase change devices 1233, 1235) can also be configured to be used as a tuning device such as for example, an impedance tuner to detune or cancel unwanted reflections and / or as a frequency tuner to match the frequency of the generator to that of the cavity.

[0103] Turning now to Figure 14a, an embodiment of a microwave distribution system 1314 is illustrated that employs two variable phase shorts 1330a, b as an impedance tuner to cancel or minimize reflected power. As shown in Figure 14a, each of the variable phase shorts 1330a, b may be connected to adjacent outputs of a coupler 1340, which may be a short-slot hybrid coupler. In operation, each of the variable phase shorts 1330a, b can be individually adjusted to a desired position such that the impedance tuner detunes the reflected energy from the microwave launcher 1322 back to the generator 1312. According to one embodiment, one or both of the variable phase shorts 1330 a, b may be further adjusted as necessary during the microwave process in order to accommodate changes in the reflection coefficient of the items being heated. In one embodiment, additional adjustments may be 23

ES 2 623 907 T3 less be partially carried out using an automatic control system (not shown).

[0104] Variable phase shorts as described herein can also be used as frequency tuners to match the cavity frequency to the generator frequency. In accordance with this embodiment, one or more variable phase shorts, shown as variable phase short 1330c in Figure 14b, may be directly coupled to individual ports spaced along a resonant microwave chamber 1320. In this embodiment, the phase variable short circuit 1330c can be rotated continuously or sporadically and its position can be adjusted manually or automatically depending on changes within the microwave chamber 1320 and / or the items being processed therein. (not shown). As a result of this adjustment of the variable phase short circuit 1330c, the frequency of the microwave energy within the cavity can be more closely matched to the frequency of the generator (not shown).

[0105] Referring again to the microwave heating system 510 illustrated in Figure 6a, heating of articles 550 passed through microwave chamber 520 can be more rigorously and efficiently carried out by, for example, increasing the heat transfer coefficient between the articles and the fluid medium that surrounds them. One embodiment of a microwave chamber 1420 configured to facilitate heating of articles 1450 more quickly and efficiently through changes in the heat transfer coefficient within microwave heating chamber 1420 is illustrated in Figure 15a. In one embodiment, the heat transfer coefficient within microwave chamber 1420 can be increased, at least in part, by agitating the liquid or gaseous medium within chamber 1420, using one or more stirring devices such as, for example, one or more fluid jet agitators 1430a-d configured to turbulently discharge one or more fluid jets into the interior of microwave chamber 1420. In one embodiment, the fluid jets discharged into microwave chamber 1420 can be a liquid or vapor jet and can have a Reynolds number of at least about 4,500, at least about 8000, or at least about 10,000.

[0106] Structurally, fluid jet agitators 1430a-d can be any device configured to discharge multiple jets to articles 1450 at multiple locations within microwave chamber 1420. In one embodiment, the fluid jet stirrers 1430 may be spaced axially along the central axis of elongation 1417 of the microwave chamber 1420 such that at least a portion of the jets are configured to discharge in a generally perpendicular direction. to the central axis of elongation 1417. In another embodiment, particularly illustrated in Figure 15b, one or more fluid jet stirrers 1430a-b may be positioned circumferentially within microwave chamber 1420 such that at least a portion of the jets are directed radially toward inward toward the central axis of elongation 1417 of chamber 1420. Although shown in Figure 15a as generally continuous along a portion of the circumference of microwave chamber 1420, it is to be understood that fluid jet stirrer 1430a may also include multiple distinct jets, radially spaced from each other along along at least a portion of the circumference of chamber 1420, each positioned to discharge a jet of fluid toward the central axis of elongation 1417 of chamber 1420.

[0107] As shown in Figure 15a, fluid jet stirrers 1430a-d may be located along one or more sides of microwave chamber 1420 and may be interspersed (alternately) with one or more launchers. microwave 1422. The use of one or more agitators 1430a-d can increase the heat transfer coefficient between the fluid medium within the microwave chamber 1420 and the articles 1450 by at least about 1 percent, at least about 5 percent, by minus about 10 percent, or at least about 15 percent, compared to the heat transfer coefficient of an inactive chamber, ceteris paribus. In the same or another embodiment, one or more similarly configured and / or operated jets may be included within one or more other zones of microwave system 10 including thermalization and / or dwell zones 12 and / or 20, previously illustrated at Figures 1a and 1b.

[0108] Again referring to Figures 1a and 1b, after being removed from microwave heating zone 16, the heated articles can then optionally be directed to a temperature retention zone 20, in which temperature retention can be maintained. temperature of the articles at or above a certain minimum threshold temperature for a specified residence time. As a result of this maintenance step, the items removed from the retention zone 20 can have a more uniform heating profile and fewer cold spots. In one embodiment, the minimum threshold temperature within holding zone 20 may be the same as the minimum required temperature within microwave heating zone 16, and it may be at least about 120 ° C, at least about 121 ° C. , at least about 122 ° C, and / or not more than about 130 ° C, not more than about 128 ° C, or not more than about 126 ° C. The average residence time of the articles passing through the retention zone 20 can be at least about 1 minute, at least about 2 minutes, or at least about 4 minutes and / or not more than about 20 minutes, no more. of about 16 minutes, or no more than about 10 minutes. The retention zone 20 can be operated at the same pressure as the microwave heating zone 16 and can, in one embodiment, be at least partially defined within a pressurized and / or liquid-filled chamber or container.

ES 2 623 907 T3

[0109] After exiting the retention zone 20, the heated articles from the microwave system 10 can then be introduced into a cooling zone 22, where the heated articles can be rapidly cooled by contact with one or more chilled fluids. In one embodiment, the cooling zone 22 may be configured to cool the articles by at least about 30 ° C, at least about 40 ° C, at least about 50 ° C, and / or not more than about 100 ° C, not more than about 75 ° C, or not more than about 50 ° C for a period of at least about 1 minute, at least about 2 minutes, at least about 3 minutes and / or not more than about 10 minutes, not more than about 8 minutes, or no more than about 6 minutes. It is possible to use any suitable type of fluid as the cooling fluid in the cooling zone 22, including, for example, a liquid medium as described above with respect to the microwave heating zone 16 and / or a gaseous medium.

[0110] In accordance with an embodiment generally depicted in Figures 1a and 1b, the microwave heating system 10 may also include a second pressure adjustment zone 14b arranged downstream of the microwave heating zone 16 and / or the retention zone 20, when it exists. The second pressure setting zone 14b may be configured and operated in a manner similar to that described above with respect to the first pressure setting zone 14a. When present, the second pressure adjustment zone 14b may be located downstream of the cooling zone 22, such that a substantial portion or almost all of the cooling zone 22 operates at an elevated (super atmospheric) pressure similar to the pressure under which microwave heating zone 16 and / or retention zone 20 operate. In another embodiment, the second pressure adjustment zone 14b can be arranged within the cooling zone 22, so that a part of the cooling zone 22 can operate at a super-atmospheric pressure similar to the pressure of the heating zone. microwave 16 and / or retention zone 20 while another part of cooling zone 22 can operate at approximately atmospheric pressure. When removed from the cooling zone 22, the cooled articles may have a temperature of at least about 20 ° C, at least about 25 ° C, at least about 30 ° C, and / or not more than about 70 ° C, no more than about 60 ° C, or no more than about 50 ° C. Once removed from the cooling zone 22, the cooled and treated items can then be removed from the microwave heating zone 10 for further storage or use.

[0111] In accordance with one embodiment of the present invention, one or more methods are provided to control the operation of the microwave heating system 10, for example, to ensure a constant and continuous exposure to microwave energy for each article or container passing through microwave heating system 10. The major steps of one embodiment of a method 1500 suitable for controlling the operation of microwave system 10 are represented by individual blocks 1510-1530 in Figure 16.

[0112] As depicted in Figure 16, the first step of control method 1500 is to determine a value for one or more microwave system parameters related to microwave heating zone 16, as depicted by block 1510. Examples of microwave system parameters may include, but are not limited to, net power discharged, speed of the conveyor system, and temperature and / or flow rate of the water contained within the microwave heating chamber. Subsequently, as shown in block 1520 of Figure 16, the resulting determined value for the specific parameter can then be compared to a corresponding target value for the same parameter in order to determine a difference. Based on the difference, one or more actions can be taken to adjust the operation of microwave system 10, as depicted in block 1530 of Figure 16. In one embodiment, the adjustment of the microwave heating system 10 can be undertaken when, for example, the magnitude of the difference is at least 5 percent, at least 10 percent, or at least 20 percent of the value. of the target value and / or the determined value for the specific parameter of the microwave system. In one embodiment, at least a part of the method described above can be carried out using an automatic control system.

[0113] In one embodiment, microwave heating system 10 may utilize the basic steps of the above-described control method 1500 to ensure compliance with safety and / or regulatory requirements of items (eg, food and / or fluids or medical instruments) that are being heated inside. According to this embodiment, the one or more parameters of the microwave system can be selected from the group consisting of minimum net power discharged, maximum speed of the transport system, and minimum temperature and / or minimum flow rate of the water within the heating chamber by microwave. In one embodiment, the minimum temperature of the water in the microwave chamber may be at least about 120 ° C, at least about 121 ° C, at least about 123 ° C, and / or not more than about 130 ° C, not more than about 128 ° C, or no more than about 126 ° C, while the minimum flow rate can be at least about 1 gallon per minute (gpm), at least about 5 gpm, or at least about 25 gpm. The maximum speed of the conveyor system, in one embodiment, can be no greater than about 15 feet per second (fps), no greater than about 12 fps, or no greater than 10 fps, and the minimum net power discharged can be at least about 50 fps. kW, at least about 75 kW, or at least about 100 kW. When the 1500 control method is used to ensure product safety or regulatory compliance, the one or more actions taken to adjust the operation of the microwave heating system 10 may include, but are not limited to, stopping the conveying system. , turn off one or more 25

ES 2 623 907 T3 generators, remove, isolate and re-process or dispose of one or more items exposed to undesirable conditions, and combinations thereof.

[0114] In the same or another embodiment, the microwave heating system 10 can also utilize the basic steps of the control method 1500 to ensure quality and uniformity between items (eg, food and / or fluids or medical instruments ) that get hot. According to this embodiment, the microwave parameters may include net power discharged, speed of the conveyor system, and the temperature and / or flow rate of the water contained within the microwave heating chamber. In one embodiment, the temperature of the water in the microwave chamber can be at least about 121 ° C, at least about 122 ° C, at least about 123 ° C, and / or not more than about 130 ° C, not higher than about 128 ° C, or no higher than about 126 ° C, while the flow rate can be at least about 15 gallons per minute (gpm), at least about 30 gpm, or at least about 50 gpm. The speed of the conveyor system, in one embodiment, can be controlled to be a speed no greater than about 5 feet per second (fps), no greater than about 7 fps, no greater than about 10 fps, and the net power discharged may be at minus about 75 kW, at least about 100 kW, or at least about 150 kW. When the 1500 control method is used to ensure product quality or uniformity, the one or more actions taken to adjust the operation of the microwave heating system 10 may include, but are not limited to, stopping the conveying system, shutting down one or more generators, remove, isolate and re-process or dispose of one or more items exposed to undesirable conditions, and combinations thereof.

[0115] To perform the comparison of step 1520 of the method 1500 shown in Figure 16, one or more of the target values ​​for at least one of the parameters of the microwave system described above can be determined prior to heating the articles in the microwave system 10. Determining the magnitude of these target values ​​can be accomplished by first creating a prescribed heating profile for the specific type of item to be heated using a small scale microwave system. For example, in one embodiment, one or more items of a specific type (eg, food, medical devices, or medical fluids) are first loaded into a microwave chamber of a small scale microwave heating system. In one embodiment, the articles loaded into the small-scale heating chamber may be of only one type, so that the determined resulting prescribed heating can be specifically applied to that type of article in a larger-scale heating system. In one embodiment, the item may be a specific type and / or size of packaged food (eg, a ready-to-eat 8-ounce package of meat) or it may be a packaged medical fluid (eg, saline) or types and / or specific containers for medical or dental instruments.

[0116] Once loaded into the microwave chamber of the small scale microwave heating system, the article can be heated by introducing microwave energy into the chamber via one or more microwave launchers. During this heating period, which may include multiple heating runs, a prescribed heating profile can be determined for the item being heated. As used herein, the term "prescribed heating profile" refers to a set of target values ​​of a variety of suggested or recommended parameters for use when heating a specific type of article. In addition to including target values, prescribed heating profiles can also be expressed, at least in part, as a function of time and / or position of the article. In one embodiment, the prescribed heating profile may include at least one target value for one or more of the microwave system parameters including, but not limited to, net power discharged, sequential microwave power distribution (i.e. specifications regarding timing, location and amount of microwave energy discharged), temperature and / or flow rate of the fluid (e.g. water) in the microwave chamber, and / or residence time of the article within the microwave chamber. In addition, the prescribed heating profile may also include target or minimum values ​​for one or more parameters (eg, temperature, fluid flow rate, pressure, and article residence time) relative to thermalization, retention, and / or cooling zones. , 20, 22 of the microwave heating system 10.

[0117] Once a prescribed heating profile has been determined, multiple such items can be loaded into a large scale microwave heating system and then heated according to the prescribed profile determined with the small scale microwave system , optionally using an automatic control system. In one embodiment, the small-scale microwave heating system may be a batch or semi-batch system and / or may comprise a liquid-filled chamber having a total internal volume less than 100 cubic feet, less than 50 feet. cubic, or less than 30 cubic feet. In the same or another embodiment, the large-scale microwave system may be a continuous or semi-continuous process carried out at least partially in a pressurized or liquid-filled microwave chamber having a total internal volume of at least 100 cubic feet, at least 250 cubic feet, or at least 500 cubic feet. The steps described above can then be repeated as many times as necessary to create specific prescribed heating profiles for any number of different items. Subsequently, target values ​​of one or more parameters described above can be determined and used in comparison step 1520 of method 1500 shown in Figure 16. After that and based on the difference, one or more of the aforementioned actions can be carried out 26

ES 2 623 907 T3 above to ensure uniform heating of the final product.

[0118] One aspect of ensuring uniform heating is ensuring that a constant and measurable power is discharged into the heating zone. In one embodiment, a method is provided for controlling the net power discharged within the microwave heating system 10. As used herein, the term net power discharged refers to the difference between the forward and reflected power within a waveguide or launcher. . As used herein, the term forward power refers to power that propagates in an intended direction from the generator to a load, while the term reflected power refers to power that propagates in an undesired direction. , usually from the load back to a waveguide or launcher and to the generator.

[0119] The main steps of a method 1600 for determining the net power discharged from at least one microwave launcher using two or more pairs of directional couplers are summarized in the flow diagram provided in Figure 17. As represented in the blocks 1610 and 1620, first and second values ​​for net power discharged can be determined using two independent pairs of directional couplers. Each pair of directional couplers may include one coupler to measure forward power and another to measure reflected power, and one or more devices or systems to calculate the difference, to provide respective first and second values ​​for net power discharged. According to one embodiment, at least one of the net power values ​​can be used to adjust or control the output of the microwave generator, while the other can be used to reinforce or validate the other.

[0120] Once values ​​have been obtained from each pair of couplers, the first and second net power values ​​can be compared to determine a difference, as illustrated in block 1630, and based on the difference, one can act to adjust the operation of the microwave heating system, as depicted in block 1640. In one embodiment, the action may be executed when the difference exceeds a predetermined value, such as a value that is at least about 1 percent, at least 2 percent, or at least 5 percent of the first and / or second previously determined net power values. In one embodiment, an action can also be performed when the difference is at least 1 percent, at least 2 percent, or at least 3 percent of the lower of the first and second net power values. In another embodiment, an action may also be executed if one of the first or second net power values ​​is below a predetermined minimum and / or exceeds a predetermined maximum. Depending, at least in part, on the items being processed and the difference determined, the action may include, but is not limited to, shutting down a generator or conveyor system, increasing or reducing generator output, and / or withdrawing , isolate and dispose of or re-process one or more items that were put into the microwave heating chamber when the difference exceeded the predetermined value

[0121] The microwave heating systems of the present invention may be commercial scale heating systems capable of processing a large volume of articles in a relatively short time. Unlike conventional retorts and other small-scale systems that use microwave energy to heat multiple items, microwave heating systems as described herein can be configured to achieve total productivity of at least about 15 packages per minute. per conveyor line, of at least about 20 containers per minute per conveyor line, of at least about 25 containers per minute per conveyor line, or at least about 30 containers per minute per conveyor line, which far exceeds the productivity that can be achieved by other heating systems.

[0122] As used herein, the term packages per minute refers to the total number of 8-ounce ready-to-eat packages filled with whey gel that can be processed by a given microwave heating system, as follows process: An 8-ounce ready-to-eat food container filled with whey gel pudding marketed by Ameriqual Group LLC (Evansville, Indiana, USA) is connected to multiple temperature probes placed in the pudding in at least five positions equidistant spaced along each x-, y- and z- axis, originating from the geometric center of the container, as shown in Figure 18. The package is then placed in a microwave heating system to be evaluated and heated until each of the probes registers a temperature above the specified minimum temperature (eg, 120 ° for sterilization systems). The time required to achieve such a temperature profile, as well as physical and dimensional information about the heating system, can then be used to calculate total container productivity per minute.