Method and device for the continuously-controlled discharge of solids

Technical field The present invention relates to a method of unloading solids from silos through a polygonal or circular cross-section of the discharge opening, wherein the solid material flows through the silo continuously.

[0002] The invention furthermore relates to an unloading device for a solids silo with a polygonal or circular cross-section of the unloading opening and a silo for solids, the silo being provided for continuous flow of solid material.

Background Art [0003] During metered unloading from a silo with a rectangular or square chute opening, it is known that in a screw conveyor in which the screw has a constant core diameter and constant outer diameter and a constant pitch, the bulk material is discharged only from the rear area of ​​the silo, while a dead zone is created in the front area of ​​the silo. By adjusting the screw geometry, e.g. reducing the diameter of the core in the direction of transport and increasing the outer diameter or pitch of the screw, the screw can take loose goods along the entire outlet section, Dietmar SCHULZE "Basics and possibilities of the technique

-1 loose materials. Information on bulk materials in the bulk materials industry (Agrichema GmbH). "

[0004] From DE 3717748 (ZIPPE GMBH and CO, 6980 WERTHEIM) 26.05.1987 a plate heat exchanger is known for preheating bulk materials, in which the problem of uneven discharge of loose materials in the lower part of the heat exchanger has been eliminated by symmetrical arrangement of exhaust shafts equipped with flange mounted, unregulated shock conveyors with the same capacity.

[0005] In the case of bulk materials with very poor flow rates, such known solutions often lead to non-uniform mass flow of solid material through the apparatus cross section. If the bulk material in the silo is simultaneously heated or cooled or when a reaction occurs during the flow, the uneven mass flow can possibly lead to local temperature differences and thus to different product properties.

[0006] From DE 3214472 (EIRICH, HUBERT ET. AL.) 20.04.1982, an adjustable unloading device is known for a device for heating electrically conductive bulk materials in which the unloading speed and electric heating power are mutually adjusted to obtain as the unloaded product constant temperature options.

[0007] In the case of devices for heating electrically conductive bulk materials, the amount of input power at the electrodes depends on the resistance of the bulk material between the electrodes. Since the current through the bulk material tends to flow always along the path with the lowest resistance, this leads e.g. to an uneven flow

-2 mass through the cross-section of the silo device for temperature differences between areas with faster flow and areas with slower flow. Particularly with the changing flow properties of the input materials, for example as a result of the changing input temperature, material moisture or particle size distribution, no way has been found to influence the varying speed of silo discharge on solid materials.

[0008] US 2,865,848 describes a method for continuous contact of granular contact materials with liquid hydrocarbons to induce chemical transformation. The transformation process takes place inside the silo into which contact material is poured.

[0009] US 5,694,413 describes a method of continuous heat input into conductive bulk materials using their electrical resistance, in an oven chamber with an inlet opening and a chute device for continuous flow of bulk material, with electricity and the device being introduced into the material during flow for continuous heat input into electrically conductive loose materials using their electrical resistance, in a furnace chamber with an inlet opening and a device for the continuous discharge of bulk material and with at least one pair of electrodes for introducing electricity into the material during a continuous flow of material.

Disclosure of the invention [0010] The object of the present invention is to develop a method and unloading device for silos of solid materials and the silo itself for materials

-3 solids, which can be equipped with such an unloading device that enables controlled and even unloading of solids throughout the entire silo cross-section and thus serves to produce loose materials that undergo physical or chemical treatment during flow through the silo, especially heated or cooled , with homogeneous properties, especially with particularly small temperature differences. The invention in its preferred embodiment also enables automatic adaptation of the changing flow properties to the input materials used.

[0011] This task is solved by the objects of claim 1, 11 and 13.

[0012] The exit of the silo according to the invention divides the cross section of the outlet or outlet into several, mostly the same partial transverse sections, to which a continuous and regulated unloading unit is always connected. Streams of solid material flowing from regulated unloading bodies can, for example, be captured and discharged through the transport device underneath.

[0013] The uniform mass outflow of solid material from continuously operating unloading bodies is controlled in this case, depending on the measuring signals from several same measuring sensors that register the existing local mass flow or other measuring quantity in the respective partial silo sections and regulate transport efficiency by means of the discharge organ associated with the sensor in each case.

[0014] For recording local mass flow, for example, the amount of electrical power input in an electrically heated sensor may be used to maintain a given temperature at the sensor tip,

-4 Stefan GERL et al., "Transistor-based sensor for in-line measurement of residual moisture in resting heaps of material", Technical measurements, 1997, volume 64, NT 7/8, pp. 268-275, or for conductive bulk materials current the amount of current at opposite electrodes.

[0015] Local energy input via steam or liquid heat exchangers can also be recorded and used as a signal for local mass flow.

[0016] In addition, the mass flow of solid material can be determined directly at each chute in each partial section of the silo in connection with the discharge rate by the unloading unit.

[0017] In continuous flow silos, the mass flow is additionally adapted to the inflow stream at the unloading organ feed speed, thereby maintaining a constant material level in the silo during flow.

[0018] Thanks to the uniform, controlled unloading, it is possible to maintain, for example, even heating / cooling of the product throughout the entire cross-section of the silo, without local temperature variation of the product. At the same time, it is possible to fully use the capacity of the heat transfer device.

[0019] Alternatively, the discharge rate may be adjusted by individual discharge organs based on the temperature of the solid material. With the same heating power in all areas of the silo, the solid material undergoes greater heating in places where it stays longer. IN

- in the case of heating power distributed unevenly across the entire cross-section, stronger heating occurs in some areas, and weaker heating in others. If the temperature is now measured in the silo or in the area of ​​unloading organs, then the transport speeds of the unloading organs can be adjusted so that the solid material taken from all areas of the silo has the same temperature. In other words, the discharge speed in an area where the solids temperature is lower than the first setpoint is slowed down, but it is accelerated if the solids temperature measured there exceeds the second setpoint. In this way, a uniform output temperature of the solid material is determined in total, which in all partial cross-sections of the unloading unit is easily between the first and second setpoints (which can also be equal). All control methods known in the art can be used for this, e.g. PID control.

Brief description of the drawings [0020] The invention is exemplified and schematically in the drawings. Individual drawings show:

Fig. 1 schematic isometric view of a silo divided into four partial sections, with sensors for measuring mass flow, with a signal analysis unit and a control unit, and with adjustable hoppers,

Fig. 2 a top view of the rectangular silo unloading bottom along the cross-section Χ-Χ 'in Fig. 1 with four hoppers with a progressive screw pitch,

-6Fig.3

Fig. 4 current

Fig. 5,

Fig. 6,

Figure 7

Fig. 8

Fig. 9 schematic side view of a silo with continuous flow of solid materials, weighted silos with mass flow sensors, with a result analysis unit and a control unit and adjustable progressive discharge screws, schematic isometric view of a silo divided into four partial sections, with weights and adjustable discharge screws , with electrodes for heating conductive solid materials and with a unit for analysis of results and with a control unit, schematic isometric view of a silo divided into four partial sections, with a fill sensor, adjustable discharge screws, with heat exchanger elements, with mass flow sensors and with a unit for analysis of results and with a unit schematic isometric view of a silo divided into four partial sections, with adjustable discharge screws, with elements of the heat exchanger working as mass flow sensors and with a unit for analysis of results and with the unit schematic side view of the silo with adjustable sluices with paddle drums, schematic side view of the silo with adjustable screw conveyors with opposite discharge openings, schematic side view of the silo with adjustable

-7 screw conveyors with a central chute hole and with orthogonal conveyor device,

Fig. 10 schematic side view of a constant flow silo with a weighted negative cone, with a signal analysis unit and with a control unit and adjustable progressive screw weights.

[0021] Fig. 1 shows a rectangular silo 1 with a charge of solid material 2, which in the bottom area is divided into four identical sections 3, 4, 5 and 6. Each of sections 3, 4, 5 and 6 has its own, regulated in a manner continuous device or chute organ 8, 9 and W, e.g. a chute screw, which continuously discharges solid material 2 from a given section. Above each section 3, 4, 5 and 6 there is at least one mass flow sensor H, 12, 13 and 14 assigned to each section. Each of the same type of sensors 11, 12, 13 and 14 records the local flow of the charge of solid material 2 in the section in which the measuring field of each sensor is located. The signals Hą, 12a, 13a and 14a from the data of sensors 11, 12, 13 and 14 are directed to the signal analyzing unit and control unit 15. The signal analysis and control unit 15 generates setting signals 7a. 8a, 9a and 10a for regulated chute devices 7, 9 and 10 in such a way that the signals 11a, 12a, 13a and 14a from the sensors, proportional to the solid material stream have the same size, which indicates the same solid material stream in each section.

[0022] Fig. 2 shows a top view of the silo chute bottom along the section Χ-Χ 'of Fig. 1. In the section of the outlet section of the silo 16 each

-8 two snails 17, 18 next to each other and two snails 17, 19 and 18, 20 above each other. Snails can possibly have a progressive stroke. In the hopper area 21. where all the screw outlets reach, solid material discharged from the silo falls under the influence of gravity into connected parts of the installation (not shown). To obtain a stepless regulation of the emptying speed, each screw is fitted with a motor 22 with a frequency converter 23 or an adjustable gearbox (not shown). The speed of material discharge can therefore be individually adjusted in each section or in part of the cross-section of the unloading bottom 3, 4, 5 and 6 of the silo.

[0023] Fig. 3 shows a silo 1 with solids 2 continuously discharging through it according to the invention.

[0024] Silo 1 is fed with bulk solid materials from above by means of a dosing unit 24, optionally a variable speed conveyor belt, while collecting solid material in the bottom area. To maintain a certain fill level inside the silo and prevent overfilling, the fill level is optionally recorded by means of a weighing device with weighing cells 26.

[0025] With the help of the analyzing and control unit 15, the measurement signals from the identical sensors H and 13 in terms of structure record the mass flow of solid material in each section 3, 5 of the silo discharge area and the level of filling inside the silo by means of weighing cells 26. The analyzing unit and control 15 controls based on input signals 11a. 13a and 26a with the speed of unloading organs 18, 20 by means of adjustable propulsion units 18a, 20a in such a way that the filling level inside the silo

-9 remained constant and all sensors 11. 13 for measuring the mass flow of solid material recorded the same amount of measurement signal 11a. 13a.

[0026] In another variant, more unloading bodies can be combined for regulatory purposes, for example 17 + 18 and 19 + 20 or 18 + 20 and 17 + 19.

[0027] Instead of the filling level inside the silo, the flow of solid materials provided by the dispensing body 24 can be used to regulate the discharge rate by the unloading bodies 18, 20.

Best embodiment of the invention [0028] Fig. 4 shows a rectangular silo 1 with a charge of solid material 2, which in the bottom area is divided into sections 3, 4, 5 and 6. Each of sections 3, 4, 5 and 6 has its own adjustable in a continuous manner with the device or the unloading body 8, 9 and W, e.g. with an unloading screw, which continuously discharges solid material 2 from a given section. To ensure a constant filling level, the entire silo 1 is placed on weighing cells 26. Alternatively, it is also possible to use fill level sensors 31 (Fig. 5).

[0029] In a particularly preferred embodiment of the invention, inside the silo 1, one or more, mostly identical electrodes 27 (pole +) are placed in the upper part over the entire silo, while in the bottom of each discharge section one or more, mostly identical electrodes 28a . 28b, 28c and 28d (gear -). Reverse polarity of electrodes 27 and 28a is also possible. 28b, 28c and 28d. Between the electrodes and the charge of solid material 2 sts

- electric conductivity 29 flows, the intensity of which depends on the resistance and thus on the temperature of the solid material between them. The current 27 'measured in the input wire is divided into the appropriate number of electrodes 28a, 28b, 28c and 28d in the unloading area, with the measured currents 28a', 28b ', 28c' and 28d 'on each electrode 28a, 28b, 28c and 28d varies depending on the solids resistance at each unloading section 3, 4, 5 and 6.

[0030] The measured currents 28a ', 28b', 28c 'and 28d' of the given electrodes 28a, 28b, 28c and 28d are directed to the analyzing and control unit 15. In addition, the analyzing and control unit 15 receives information about the current 27 'on the upper electrode 27 and with a silo mass obtained from weighing cells 26 and with a solid material temperature of 30 in the unloading area 21. The analyzing and control unit 15 generates such setting signals 7, 8, 9 and 10a for adjustable discharge devices 7, 8, 9 and 1Q so that currents 28a ', 28b', 28c 'and 28d' on electrodes 28a, 28b, 28c and 28d were of equal size and thus that there was an equal mass flow of solid material in each section, and in addition that the same level of silo filling was maintained.

[0031] In addition, the analyzing and control unit registers the temperature of all the solids discharged and regulates the power on the electrodes 27, 28a, 28b, 28c and 28d in such a way that the required final product temperature is obtained.

[0032] If more electrodes are used in the evacuation section, the measured currents are suitably combined to obtain a measurement signal useful for analysis.

Embodiments of the invention

[0033] Fig. 5 shows the variant of Fig. 4 and Fig. 1, in which the heating or cooling of the solid material takes place inside the silo 1, optionally by means of heat exchanger 32, through which steam, heating oil or liquid flows, which in another embodiment can also be electrically heated. The mass flow of solid material in each section 3, 4, 5 and 6 is recorded in accordance with Fig. 1 by means of a plurality of mass flow sensors U, 12, 13. 14 and signals 11a, 12a, 13a and 14a are directed to the analyzing and control unit 15, which on this basis generates appropriate setting signals for the emptying devices Z, θ, θ and 1θ as described in Fig. 1. Input of power 33 to the heating elements or cooling 32 inside the silo, controlled for example by the flow of the heating or cooling medium, takes place depending on the measured final temperature 30 at the discharge screw outlet.

[0034] Fig. 6 shows another variant of Fig. 5, in which the elements of the heat exchanger 32a, 32b, 32c and 32d, through which the heating or cooling medium flows, are simultaneously used as mass flow sensors, with each section 4, 5 and 6, a heat exchanger element 32a, 32b, 32c and 32d is allocated through which the heating or cooling medium flows. Based on the amount of energy input, determined by the analyzing and control unit 15 based on individually measured for each section mass flow or volume of refrigerant 36a, 36b, 36c and 36d and the temperature difference between input 34a, 34b, 34c and 34d and output 35a, 35b. 35c and 35d, set signals for evacuation devices 7, 8, 9 and 10 can be generated as described in figure 1.

[0035] Fig. 7 shows the variant of Fig. 3 in which the output of solid material into

12-part sections 37, 38 and 39 take place through a plurality of adjustable sluices with paddle wheels that dump the discharged solid material onto the underlying and continuously operating conveying device 40, which collects individual solid material streams and transports to a specific discharge point 41 Adjusting the speed of emptying sluices with paddle wheels is analogous to the previous description using mass flow sensors, not shown.

[0036] Fig. 8 shows yet another variant of Fig. 3, in which emptying takes place by means of screws 42, 43, which dump solid material emptied from partial sections 3 and 5 through opposite emptying holes 44, 45 to the below, continuously operating conveyor 46, which collects individual streams of solid material and transports to a specific discharge point. Also in this case, the speed control by the screws 42, 43 is analogous to the previous description based on not shown mass flow sensors.

[0037] Another variant of Fig. 8 shows Fig. 9, in which the solid material collected from partial sections 3 and 5 is transported through several discharge screws 47, 49 to the center of the silo 1 and all the flow of solid material is collected by an orthogonally arranged conveyor 48 with continuous operation and transported further to a specific point.

[0038] Fig. 10 shows the variant of Fig. 3 with a silo 1 with a negative cone through which solid material flows continuously. Silo 1 is fed from above by a dosing mechanism 24, possibly by a variable speed conveyor belt, and at the same time in the bottom area is continuously emptied. For

- maintaining a certain filling level inside the silo and avoiding overfilling, the filling level is optionally controlled by means of a weighing device with Weighing Cells 26. Emptying takes place through many weight screws 50 and 51 [0039] As a result of the construction of silo 1 with a negative cone, compaction is prevented solid material 2 in deeper layers by the dead mass of the solid material. The bulk density and thus also the electrical resistance of the embankment remain unchanged.

[0040] By means of the analyzing and control unit 15 the weights of the screw conveyors 50b and 51 b are recorded based on the speed of the given screw, the mass flow of solid material in each screw is calculated for each section 3, 5 of the silo emptying area. In addition, the filling level inside the silo is recorded by means of weight cells 26. Based on the input signals 50c, 51c and 26a, the analyzing and control unit 15 controls the speed of the emptying organs 50, 51 by means of adjustable drive units 50a, 51a in such a way that the filling level inside the silo remains unchanged, and the mass flows of solid material calculated based on mass 50c, 51c and screw speeds 50, 51. also remain unchanged. As an alternative to the weight in augers, for example, scales on a conveyor belt can be used.

[0041] In principle, the invention is not limited to said evacuation devices, but can be implemented by means of any any continuously operating and regulated evacuation unit. The same applies to the continuously working conveyor underneath

- emptying organs, which collect solid material coming out of the emptying devices and transport them further. Instead of a continuous conveyor, solid material coming out of the emptying bodies can also be directed directly to the connected apparatus. Also, the silo emptying opening is not limited to polygonal, usually rectangular or square, but can also be round.

[0042] For the purposes of the original disclosure, it is noted that any features resulting from the present description, drawings and claims made available to the skilled person, even when specifically described in connection with specific other features, can be combined individually and in any combination with other features or groups of features disclosed here, unless expressly excluded or the technical conditions of such combinations prevent or render them meaningless. Due to the shortness and legibility of the description, extensive disclosure of all possible combinations of features of the invention has been abandoned.

References [0043] DE 3717748 (ZIPPE GMBH U. CO, 6980 WERTHEIM) 26.05.1987; DE 3214472 (EIRICH, HUBERT ET. AL.) 20.04.1982; SCHULZE, Dietmar. Basics and possibilities of bulk materials technique. Information on loose materials in the bulk materials industry (Agrichema GmbH) .; GERL, Stefan, et al .. Transistor-based sensor for in-line measurement of residual humidity in resting dumps. Technical measurements, 1997, volume 64, No. 7/8, pp. 268-275.