Method and apparatus for drying a load of moist fibrous material, particularly a load of laundry

IS 2 139 447 T3

DESCRIPTION

Procedure and installation for drying a mass of wet fibrous matter, notably a mass of clothing.

The present invention relates to a process and an installation for drying a mass of huomeric fibrous material, notably a mass of clothes washed and placed in a washer-dryer machine or in a dryer.

In dryers known to date, various warm fluids have been used as the drying medium. It has notably used warm air blown into the interior of a dryer, at a temperature of the order of 120 ° C, but such a drying process has the disadvantage of being remarkably long and entailing a significant consumption of energy. To remedy this drawback, it has already been envisaged to use, for drying clothes, superheated steam placed in forced circulation through an enclosure containing clothes to be dried.

Document WO 89/04 392 discloses a method and an apparatus for drying, by means of superheated steam, a mass of laundry contained in an enclosure. The superheated steam is circulated through the enclosure, in a closed circuit, by means of a fan mounted in the upward direction of the enclosure and in a downward direction from a heat source so that the water vapor is pushed into the enclosure. that evaporates from clothing. At the beginning of a drying cycle, the air contained in the room is pushed through a vent to which a bypassed condenser has been connected.

Document EP-A-0 026 707 discloses a method and a drying installation in which the drying cycle consists of a first aeration phase in which it is circulated through an enclosure, which contains the material to be drying, water vapor produced by an independent steam generator and a second phase in which the water vapor evaporated from the huomide matter is circulated by means of a fan connected upwards of the enclosure, This water vapor passes through an overheater. A bypass capacitor is connected to the outlet of the chamber containing the huomed matter.

The present invention relates to improvements made to known drying processes and apparatuses which make it possible to notably reduce the overall duration of drying of a mass of fibrous material and to considerably reduce the cost of the drying installation.

For this purpose, this process of drying a mass of huomeric fibrous matter, notably a mass of damp clothes after washing, in which water vapor is passed through the mass of fibrous matter, in a closed circuit, on -heated to a temperature between 102^° and 180^°. C and sensitively to atmospheric pressure, characterized by the fact that it consists, before the drying phase with the superheated water vapor, of a previous phase of extraction of the air, present in the closed circuit, by means of steam of water.

The invention also has as its object an installation for drying a mass of huomeric fibrous material, notably a mass of huomeric clothing after washing, which consists of an enclosure in which the mass of huomeric clothing is housed, a steam generator, a superheater, a condenser, and a fan to circulate, in a main pipeline in a closed circuit, superheated steam at a temperature ranging from 102 to 180^° C, through the enclosure and the mass of fibrous fibrous matter that it contains, characterized by the fact that the fan designed to ensure the circulation of the water vapor consisted of a suction fan connected, in the main duct, in a downward direction. from the outlet of the enclosure, in order to create a slight depression in this enclosure, the condenser and the overheater are connected in series towards the top of the enclosure, The main pipeline was connected, on the blower side of the fan, on the one hand to a first open air solenoid valve, connected by bypass and on the other hand to a second solenoid valve connected in series and the steam generator was connected to the main line, downstream of the second solenoid valve, by means of a third solenoid valve.

The drying procedure and installation according to the present invention offer the advantage of allowing a simplification of the installation. In fact, the previous rinsing of the closed circuit of its air, by means of water vapor, before the drying phase itself, allows the installation to operate at atmospheric pressure and the temperature of the steam inside the enclosure. drying is therefore necessarily always greater than 100^° C for normal atmospheric pressure. According to the invention, the cost of a clothes dryer can be remarkably reduced in this way by the fact that it is not necessary to use sophisticated sealing devices (seals, etc ...).

A form of execution of the present invention will be described below, by way of non-limiting example, with reference to the attached drawing, whose only figure is a diagram of an installation for drying clothes by means of superheated steam, as follows the present invention.

The drying installation consists of an enclosure (1) in which the mass of fibrous matter to be dried is placed, which was considered, within the framework of the present description, as being humid clothing, as it appears after washing. The enclosure (1) can be constituted by a drum set in rotation by mechanical drive and that can rotate alternately in both directions, so that the laundry is removed. The enclosure (1) can also be constituted by a clothes dryer in which the pieces of clothes remain immobile and are suspended in an appropriate way. The enclosure (1) can also be of the type of continuous circulation of the pieces of clothing, from an entrance to the exit of the enclosure.

The enclosure (1) is attached to an outlet duct (2) in which a centrifugal fan (3) is housed that creates a depression in the enclosure.

ES 2 139 447 T3 (1) when it starts up. The outlet conduit (2) is connected to a main pipeline (4) connected in a closed circuit with the enclosure (1) and connected for this purpose to an inlet hole of this enclosure. This main channel (4) is intended for the circulation, in a closed circuit, of superheated water vapor and / or air, as will be specified later on. A solenoid valve (5) is attached to the duct (4), in the downward direction of the fan (3), which also forms an open-air valve, regulated for example to an absolute pressure of 1.05 bar. In the downward direction of the connection point of the solenoid valve (5) there is another solenoid valve connected, in series in the pipeline (4), and in the downward direction of this solenoid valve (6) another is connected in bypass. solenoid valve (7) attached to the top of a steam generator (8). In the pipeline that joins the solenoid valve (7) to the steam generator (8) there is connected a safety valve (9) regulated to an absolute pressure of 1.2 bars for example. The steam generator (8) was connected to a water source by means of a valve (11) and consists of an electric heating device (12) to cause the vaporization of the water contained in the generator (8).

In the pipeline (4) there is connected in series, downwards from the steam generator (8), a steam condenser (13) equipped with an air or water cooling circuit (14). The condenser (13) is regulated in such a way that the condensation temperature is always slightly higher than the saturation temperature corresponding to atmospheric pressure, that is, 100 C for normal atmospheric pressure. The condenser (13) contains a float (15) linked to a level sensor (16) that detects the water level in a condensate recuperator (17) located in the lower part of the condenser (13). Below the condensate recuperator (17) there is a condensate tank (18).

After the condenser (13), that is to say downwards in the direction of steam circulation, the main closed-circuit pipeline (4) consists of a solenoid valve (19) connected in series. The pipeline (4) was then connected to the inlet of an over-heater (21). This over-heater (21) consists of an electric heating circuit (22) that produces the overheating of water vapor at a temperature ranging from 102 ° C to 180 ° C. In the upward direction of the superheater (21), a solenoid valve (23) is connected to the duct (4) to allow an intake of air in the main circuit.

According to a variant, the steam generator (8) could be associated with the super-heater (21), forming a single and same unit that supplies super-heated steam from liquid water.

The installation can also consist of a dehydrator (24) connected in parallel to the solenoid valve (19) and joined to the main pipeline (4), on either side of the solenoid valve (19), by two pressure valves. solenoid (25) and (26). The dehydrator (24) consists of a matrix with a dehydrating material, capable of absorbing or adsorbing water vapor and that can be regenerated by heating by means of an electric heating device (27).

The temperature of the fluid (water vapor and / or air) that flows in the main circuit (4) was controlled by means of two thermic probes (28), (29) mounted respectively at the inlet and outlet of the enclosure (1 ), in order to detect the inlet T1 and outlet T2 temperatures of the steam that passes through the enclosure (1).

The different solenoid valves (5), (6), (7), (19), (23), (25), (26), the heating circuit b (12) of the steam generator (8), the The heating circuit (22) of the overheater (21) and the heating device (27) of the dehydrator (24) are connected to a general automatic control circuit (31) that regulates the operation of the installation. This device (31) was also connected to the centrifugal fan (3) to command the start-up and stop of this fan. The device (31) also receives information from the level sensor (16) of the condenser (13) and from the thermal probes (28) and (29).

The operation of the installation will now be described, putting into practice the drying procedure according to the present invention.

In the case of a discontinuous process, that is, the drying of successive batches of laundry, the drying process consists of a first phase in the course of which the humid air normally present in the main circuit (4) is replaced by steam from water, overheated or not, circulating in an open circuit. This humid air is found in the enclosure (1) and the humidity rate and the temperature of this air are variable. At the beginning of the first phase, the automated control device (31) causes several simultaneous operations, namely, the start-up of the steam generator (8), so that steam is produced in this generator at a temperature of 102^° C, the opening of the solenoid valves (5) and (7), the closing of the solenoid valve (6), the start-up of the fan (3) and eventually the start-up of the over-heater (21) . The fan (3) creates a depression inside the enclosure (1), although the steam produced by the steam generator (8) flows successively through the open solenoid valve (7), the main pipeline (4), the condenser (13) whose external cooling system stops during this phase and the solenoid valve (19) open and is introduced into the overheater (21), then in the enclosure (1) and this steam extracts the air contained in the main circuit and in the enclosure (1), this air is pushed to the outside, together with the water vapor, through the solenoid valve ( 5) open. This first phase of extraction and replacement of the humid air by water vapor, eventually overheated, lasts a predetermined time that can be easily calculated from the known volume of the installation. At the end of this first phase, only water vapor, overheated or not, circulates through the main pipeline (4), at atmospheric pressure, and the circuit no longer contains air. At this time, the control device

ES 2 139 447 T3 automatic (31) causes the closing of the solenoid valves (5), (7), the stopping of the steam generator (8) and the opening of the solenoid valve (6), which establishes a closed circuit for the subsequent circulation of steam.

The drying procedure then proceeds to a second phase or main phase in the course of which the laundry contained in the enclosure (1) is dried by the superheated steam and the water extracted from the laundry is continuously condensed into the condenser (13). At the beginning of this phase, the automatic control device (31) causes the superheater (21) to start up, if it was not already in service during the first air extraction phase. During the main drying phase, the fan (3) continues to rotate, causing the water vapor to circulate in a closed circuit, which is overheated in the superheater (21). In the condenser (13), a part of the water vapor is condensed and the condenser thus withdraws a progressively increasing quantity of water from the closed circuit, allowing the optimal operation of the clothes dryer. The power of the condenser (13) is subject to the steam outlet temperature T2 from the enclosure (1). In fact, as the drying progresses, the flow rate of water extracted from the clothes decreases, the temperature T1 increases and the power of the condenser (13) decreases. The level of the condensate collected in the recuperator (17) is detected by the float (15) that acts on the level sensor (16). This sensor (16) makes it possible, together with the temperature probes (28) and (29), to determine the end of drying. In other words, when the level sensor (16) detects that the level of the condensed water in the condensate recuperator (17) no longer varies practically and the temperature probes (28) and (29) indicate that the inlet temperatures T1 and T2 output are practically identical, it means that the laundry has reached its final drying point. At this time, the automatic control device (31) automatically stops the drying cycle.

The main phase of drying with the aid of superheated steam can optionally be followed by a third phase of drying by means of dry air.