EP1373818A1

EP1373818A1 - Method and device for treating bulk products

Info

Publication number: EP1373818A1
Application number: EP02730030A
Authority: EP
Inventors: Hartmut Meyer; Thomas Staak
Original assignee: Claudius Peters Technologies GmbH
Current assignee: Claudius Peters Technologies GmbH
Priority date: 2001-03-20
Filing date: 2002-03-19
Publication date: 2004-01-02
Anticipated expiration: 2022-03-19
Also published as: US6926521B2; DE50203146D1; EP1373818B1; US20040115581A1; WO2002075230A1; DE10113516A1

Abstract

The invention relates to a method and a device for treating, especially cooling, a bulk product situated in the form of a layer (20) on a handling grid (10). Gas is guided upwards via the grid (10) and the layer (20). Said grid is moved back and forth in its entirety, the product layer (20) being held fast during the backwards movement. The level of movement frequency is selected so low that essentially no vertical mixing of the product layer (20) takes place. A baffle plate (30) or the like is provided in order to keep the layer (20) still. Avoiding vertical relative movement inside the product layer (20) improves the heat recovery.

Description

Method and device for treating bulk goods

It is known to treat bulk material with gas in that it is continuously conveyed in a layer over a grate and the gas flows through it. For the cooling of fired goods, for example cement clinker, so-called sliding grates are primarily used, which consist of overlapping rows of alternately fixed grating plates which are moved back and forth in the conveying direction (DE-A-37 34 043, DE-A-196 49 921). Cooling air is blown into the material bed through the grate plates, which causes cooling and is discharged above the material layer for heat recovery. Another known type of grate uses a stationary, air-permeable support base, over which the material layer is moved by means of scratches which move continuously in the conveying direction or reciprocating thrust elements (EP-A-718 578, WO00 / 31483). Yet another type of cooler uses a moving grate which moves continuously in an endless loop (DE-A 1 953 415). In all cases, efforts are made to recover the heat transferred from the goods to be cooled to the cooling gas as far as possible. Regardless of the type of cooler heat recovery has reached a relatively high level.

Surprisingly, it is possible to further increase the heat recovery by using a conveyor grate that is moved back and forth in its entirety, the good layer being held during the return stroke and the stroke frequency being chosen so low that there is essentially no vertical mixing of the Good shift takes place. The good layer is retained during the return stroke of the grate in that a stowage device is arranged at the end of the task in the area of the good layer, against which the good layer runs during the return stroke. The gap between the stowage device and the layer of material during the preliminary stroke is always immediately filled from the embankment stock of the material at the end of the task. The low internal material movement is based on the fact that a relative movement essentially only takes place between the material bed and the support plate, and this only during the return stroke of the support plate.

The improvement in heat recovery is based on the lower vertical mixing of the material bed. When the gas flows from bottom to top, the material in the bottom layer cools down first, while the material further up maintains a high temperature. The gas therefore leaves the material layer after it has been in contact with the layer with the highest temperature and has reached its temperature. On the other hand, in the known types of cooler, the conveying movement ensures that vertical mixing of the refrigerated goods assumes an average temperature. The gas therefore leaves the material layer at a correspondingly lower temperature. The same applies if the method is not used for heat exchange, but for mass transfer, for example for drying, or if the gas is not led from bottom to top but vice versa through the material layer.

The conveying principle to be used according to the invention is known in so-called push car feeders. These are conveyors, which are mainly used for the dosing of bulk goods from containers (DE-B-12 54 071). It could not be assumed that the application of this principle would lead to advantages in heat or mass transfer. On the contrary, the lack of, or very little, mixing of the material bed was felt to be a defect, because it enables the material bed to gain an internal cohesion that questions the even discharge from the end of the conveyor (DE-A-34 21 432) ). In the context of the invention, this supposed disadvantage turns out to be advantageous because the cohesion of the layer makes it more difficult to break out part of the layer under the dynamic force acting on the return stroke and thereby enables a longer support plate length.

Since the stroke is not limited by the dimensions of the grate plates, as is the case with sliding gratings, it can be dimensioned much larger than is usual with sliding gratings. This increases the conveying effectiveness with a possibly lower number of strokes, which is preferably less than 20, more preferably less than 15 and preferably less than 10 min ^-1 on average. It is usually about half the size of that of sliding grids. The feature that the stroke frequency is chosen so low that there is essentially no vertical mixing of the good layer, the invention distinguishes it from such known methods in which the base carrying the good layer moves (vibrates) so quickly and possibly also with a vertical component ) is that this means that the material also gets into a vibration that promotes the vertical relative movement of the particles. Rather, the material layer should rest on the grate during the forward stroke and essentially also during the return stroke.

The invention does not require that there is no vertical mixing of the good layer at all. It is easy to see, however, that when using the mentioned conveying principle, the internal mixing of the material layer is considerably less than with the conveying principles previously used for cooling gratings.

The return stroke speed is expediently greater than the advance stroke speed because only the advance stroke causes an effective conveying. An important feature can be the use of a return stroke acceleration that is greater than the advance stroke acceleration. The greater the acceleration of the return stroke, the easier the adhesion between the support plate and the material bed is loosened, and the less the back pressure which has to be applied at the end of the material layer to hold it in place. However, as a rule, the acceleration of the return stroke should always remain below the acceleration of the release of the adhesive, because otherwise there is a risk that the layer of material will be loosened and mixed internally by violent movement. The acceleration of adhesive release is the acceleration at which the force of the good layer becomes greater than the static friction and consequently the layer no longer follows the return movement. Nevertheless, the mass effect can help to solve the adhesion between the goods and the support plate during the return stroke. For example, it may be expedient to increase the acceleration of the return stroke to more than a third of the acceleration of the release solution.

The treatment gas is expediently allowed to flow through the grate and the material layer from bottom to top, because this makes the adhesive solution easier. On the one hand, the contact force of the material bed decreases according to the pressure difference of the gas flow. On the other hand, the gas flow can cause a certain loosening of the boundary layer when it passes from the support plate into the material bed. Since it is desirable to facilitate the adhesive solution during the re-acceleration phase, it may be advantageous to keep the speed or the pressure of the treatment gas greater during the re-acceleration and / or during the entire re-stroke than during the pre-stroke.

You can provide the support plate with moving side walls. If this undesirably increases the friction of the goods during the return stroke, they can be omitted.

The support plate is expediently sealed on the sides with respect to the housing in order to largely rule out the failure of fine material. Such a seal is particularly important when the treatment air is pressed with overpressure from stationary chambers below the grate into the openings of the grate which is open on the underside, so that as little gas loss as possible occurs at the side edges of the grate. Corresponding points of view apply to the sealing of the support plate at its end of delivery or delivery. The sealing on the feed side is expediently made by a seal that overlaps the support plate and is pressed on its upper side

Sealing plate formed. Due to the fact that the sealing plate slides on the upper side of the support plate essentially without a gap, the passage of gas at this point is excluded or kept low. The sealing plate can be pressed onto the upper side of the support plate by a resilient force, in particular a spring. If a small gap can be tolerated instead of the absence of gaps, it is also possible to mount the sealing plate firmly at a short distance above the support plate. Since there are high temperatures at the end of the task, it is advisable not only the support plate, but also the

To make the sealing plate air-permeable and to apply a gas flow.

A support plate has a very long length compared to the grate plates of a chill grate cooler, namely at least several meters. The entire cooling grate can be formed by a uniform support plate. If there are reasons to limit the length of a support plate (for example to the order of 5 to 10 m) and a larger overall length of the grate is required, several support plates can be arranged one behind the other, which either cooperate with a common storage device at the end of the task or each with a special associated stowage device.

The support plate is usually arranged approximately horizontally. Depending on the conveying conditions, in particular the flow and friction properties of the material, one can also move in the conveying direction weakly rising or falling order can be selected.

An advantage of the invention is that less dust is generated by the reduced material movement and is fed into the furnace with the secondary air than in known coolers. On the one hand, this means that the furnace can be operated more effectively because the heat transfer between the flame and the fired material is not reduced by dust, and on the other hand, the effort for dedusting the exhaust air is reduced.

Another advantage of the invention is that the entire airfoil is available for the supply of cooling air and cooling, while in the case of moving grate coolers and sliding beam coolers, in principle some areas are excluded from the supply of cooling air.

Another advantage of the invention is that the layer height is not subject to the limitation that must be observed in conventional coolers. A larger layer thickness favors heat recovery.

Finally, an advantage of the invention is that, owing to the lack of internal movement of the goods, the occurrence of liquid-like conditions in a part of the goods occurs less easily. This phenomenon is feared in known coolers because it leads to the fact that a flow of fine material which is in a liquid-like state shoots through a substantial part of the cooler length practically uncooled. Since the discharge of the material from a rotary kiln is associated with a grain size separation, this phenomenon occurs mainly on that side of the cooler, on which a larger fine fraction is to be expected as a result of this separation.

In addition, the grate used according to the invention opens up the possibility of taking passive or active precautions against the occurrence of such undesirable movement of easily flowing material. Passive precautions consist of means that inhibit the movement of the goods on the grate in the conveying direction, for example projections protruding from the support plate. Especially such projections are suitable, which mainly extend transversely to the conveying direction in the form of walls or strips or the like. Since the material flow mentioned occurs predominantly in the edge region of the grate, such flow obstacles can also protrude from the side wall into the material bed. Flow obstacles protruding from a stationary side wall can be used in particular if they are arranged above the normal layer height and therefore prevent the flow of material through when this takes place on the surface of the layer already resting on the support plate.

Active precautions can be formed by such flow obstacles, which are moved from case to case from the support plate or the moving or unmoved side wall from an inactive position into the area of the material flow to be prevented into an active position and can then be withdrawn again. They can also continuously protrude more or less far into the layer, the width of their intervention, ie their height or length, being controlled depending on the respective condition of the bed. It is known to use scanners to measure the surface temperature of the bed and to determine its temperature profile. If a rapid, hot material flow occurs in or on the bed, this can be seen in the temperature profile. On the basis of such a determination, the flow obstacle or the flow obstacles can be controlled.

It is also possible to have the flow obstacle or the obstacles only protrude into the layer in those work phases in which the layer is to move together with the support plate, i.e. during the forward stroke, while they are fully or partially retracted when the support plate is moved back.

If a flow obstacle is only to be effective in the upper region of the good layer, it can also be lowered onto or into the layer from above.

The flow resistance is greater in those width regions of the layer in which the layer contains a larger proportion of fines than in coarse-grained regions. According to the invention, this can be compensated for by driving the cooler in the fine-grained width ranges with a smaller layer thickness. For this purpose, the support plate can be arranged somewhat higher in these areas than in the coarse-grained areas. Since the fine-grained areas are generally on the edge, this results in an inclination in the transverse profile of the support plate from the fine-grained side to the center. If, due to the separation of the material in the cooler feed area, a larger proportion of fine material must be expected at both grate edges, the support plate height is allowed to drop from both sides in a V-shape towards the center. If the fine good proportion occurs only or predominantly on one of the two edges, a correspondingly asymmetrical inclination is sufficient.

The feature that the conveyor grate is moved back and forth in its entirety expresses the difference compared to sliding grids. However, it should not rule out that the grate designed according to the invention is only part of a larger grate system, this feature relating only to this part.

The reliable conveying operation depends on the fact that the material bed is carried along by the carrier plate during the forward stroke and that the carrier plate slides under the material bed during the return stroke. The entrainment of the material bed during the forward stroke is caused by the friction between the material bed and the support plate. The sliding of the support plate relative to the material bed during the return stroke depends on the frictional engagement between the material bed and the support plate being overcome by opposing forces. These counteracting forces include primarily the backlog resistance that the end of the task in the area of

Well-arranged stowage device exercises. It may be expedient to provide further devices which likewise exert a resistance on the material layer when the support plate moves back, or which reduce the frictional engagement between the material bed and the support plate in this movement phase. In particular, a device can be provided to increase the gas pressure acting on the good layer in the support plate or from the underside during the return stroke compared to the preliminary stroke. The friction-generating force with which the good bed rests on the support plate is then reduced on the return stroke in accordance with the pressure difference. Also diminished a strong gas supply during the return stroke the coefficient of friction between the goods and the support plate.

Furthermore, the invention provides the possibility of providing links connected to the support plate which engage less (preferably not at all) during the return stroke and engage more strongly in the material bed during the forward stroke. The resistance to movement that the material bed finds on the return stroke can also be increased in that the support plate is provided with side walls delimiting the material bed, the clearance between which increases in the conveying direction or narrows in the opposite direction. If these side walls are connected to the support plate, they reduce the frictional connection between the material bed and the walls during the return stroke of the support plate.

Means can also be provided which increase the frictional engagement between the material bed and stationary parts of the device during the return stroke compared to the preliminary stroke. These include holding members connected to the fixed structure of the device, which engage more strongly in the return stroke and less (preferably not at all) in the material bed during the forward stroke. A stationary pair of side walls delimiting the material bed can also be provided, the clear distance of which increases in the conveying direction. Should the material bed show the tendency to move together with the support plate during the return stroke, the increasing narrowing due to the side walls would lead to increased frictional resistance. Finally, stationary devices can be provided within the material bed, which preferably oppose the material movement in the conveying direction with less resistance than the movement in the opposite direction. If the material is fed to the device unevenly over time, as is the case, for example, with coolers for material to be fired, to which the material is supplied from a furnace, a different one can appear on the support plate

Set the layer height. This can be counteracted by varying the conveying speed (stroke frequency, stroke amplitude). Instead of or in addition, the invention provides for the possibility of using a layer height limiter. This is a wall that is arranged at the beginning of the conveyor above the support plate and the lower edge of which is at a distance from the support plate that corresponds to the desired thickness of the material bed.

The invention is explained in more detail below with reference to the drawing which illustrates advantageous exemplary embodiments. 1 shows a schematic side view, FIG. 2 shows a partial view on a larger scale, FIG. 3 shows a partial section of the side seal,

4 shows an embodiment with a plurality of support plates connected in series, FIG. 5 shows a schematic longitudinal section of an embodiment variant in which the support plate is provided with transverse ribs,

6 shows a schematic longitudinal vertical section,

Fig. 7 is a schematic horizontal section and

Fig. 8 shows another embodiment variant in longitudinal section.

The cooler for firing material, for example cement clinker, arranged in a housing 1 comprises a section 6 designed according to the invention. cut upstream, which is located below the shaft indicated by its walls 3, in which the material coming from the furnace is thrown off in the direction of arrow 4. It comes to an embankment 5, which forms on the preferably inclined surface 2 of the inlet section. The surface 2 can be of conventional design, for example consist of grate plates to which cooling air is applied, stationary or partially moved. Means for mechanically loosening the material can be provided, which counteract the caking of the material or crush larger pieces. The inclination of the surface 2 is expediently chosen so that on the one hand it remains on its cool good, which protects it from the direct influence of the good coming hot from the oven, and on the other hand larger pieces of the good continue to move due to their gradient.

Instead of the inclined surface 2, differently designed devices for receiving and conveying the material thrown off the oven can be provided, as are known in the prior art, for example, in front of moving grate coolers. They can also be missing entirely; i.e. that the cooler section 6 extends back into the discharge area 4. This is possible without further ado because, due to its conveying principle, it never empties completely and therefore there is a protective layer of good on it in every operating condition, even when starting from a standstill.

The cooler section 6 is mainly formed by a support plate 10. This consists, for example, of a framework 11 with attached, adjoining metal sheets 12, which can be covered with a hard layer 13 as wear protection. The support plate rests on a swing frame men 14, which is movably mounted on rollers 15 in the conveying direction 16. A hydraulic drive 17 sets it in a reciprocating motion, preferably with an amplitude of 10 to 80 cm, more preferably of 30 to 50 cm, and a frequency of normally 5 to 10 min ^"1 , which expediently depends on the thickness of the the bed 20 located on the support plate 10 is regulated and can rise to, for example, 30 min ⁻¹ in the event of an abnormally large amount of material, for example the layer thickness of the material is 50 to 200 cm.

The metal sheets 12 of the support plate 10 contain uniformly distributed air passage slots 21, which can be designed according to the principles known from grate plates (see, for example, EP-A-811 818). They can be provided with pockets 22 for collecting the fine material which falls through when the air flow is switched off and which is carried away by the air flow during the operation which is then resumed and is returned to the material layer.

In the example shown, it is assumed that the chambers 23 under the support plate 10 are pressurized by a fan 35, so that there is an air flow directed from bottom to top through the openings 21. The support plate 10 can also be designed as a cover plate of a closed box, the cooling air being supplied to the box interior through flexible hoses or the like. As is known from sliding grates, individual sections of the support plate 10 can be separately applied and, if necessary, with different pressure.

The side edges of the support plate 10 are not closer to the adjacent housing wall 25 according to FIG. 3 by one seal 26 shown sealed. This prevents the diarrhea of fine material and, if necessary, the passage of cooling air.

At the end of the support plate 10 on the feed side, a storage plate 30 is arranged in the height region of the good layer 20. It can be provided just before the support plate or above it. The support plate takes along the goods lying on it during its forward stroke. At the foot of the embankment 5 there is a gap in the good layer 20, which immediately fills with the good flowing from the embankment 5. On the return stroke, the good layer 20 initially still adheres to the support plate until it jams on the storage plate 30. As soon as the ram force exceeds the frictional force between the good layer 20 and the support plate 10, the good layer stops while the support plate 10 moves further back under it. In order for the storage device to be able to perform this function, it does not necessarily have to be plate-shaped. It is also not necessary for the stowage device to be located directly at the loading end of the support plate, although this is advantageous. Rather, the dynamic pressure can also be transmitted through the embankment 5, which descends to the level of the support plate, to a force-receiving surface located further away from the support plate 10. This force-receiving surface can be formed, for example, by surface 2 or wall 3, which are then drawn down correspondingly deep.

In order to seal the moving end of the support plate 10 against the stationary components, a sealing plate 32 is provided, whose end pointing in the conveying direction 16 rests on the upper side of the support plate 10. The other end of the sealing plate 32 is pivotally mounted at 33 and is tightly connected to the storage plate 30 in a manner not shown. A spring 34 presses the sealing plate 30 onto the support plate 10 essentially without a gap via a lever arm.

The discharge-side end of the support plate 10 is expediently also sealed off from the stationary devices, for example by a spring steel strip (not shown) which lies against the underside of the support plate without a gap.

The air blowing into the good layer 20 from bottom to top reduces the support pressure of the good layer due to its counter pressure and loosens up its lowermost area a little. The friction between the good layer and the support plate is therefore less than with push-wagon feeders, and the conveying length can be correspondingly longer. Furthermore, the

Reverse acceleration at the transition from the forward to the return stroke can be used to facilitate the release of the goods adhering to the support plate.

The surface of the support plate is expediently designed in such a way that the least possible friction against the material is achieved. However, it can make sense, particularly in the initial area of the support plate, to choose a surface shape which leads to cool material being retained as a protective layer under the hot material lying above it. For example, according to FIG. 5, the support plate 10 'is provided for this purpose with transverse ribs 18, the height of which is expediently between 5 and 15 cm and the distance in the direction 16 is, for example, between 10 and 30 cm. It should not significantly exceed the feed length and is preferably less than this. The effect of the cross ribs is that good in the troughs that are formed between the ribs it is noted that the support plate protects against the direct action of hot goods and against wear. Such devices for holding a cool material layer do not need to cover the entire surface of the support plate, but can be limited to those areas in which otherwise a particularly high load on the support plate would have to be expected. They can also have other shapes, provided that they are suitable for holding the goods.

If a very large cooler length is required, which cannot be managed with a support plate length, several support plates 10 or groups of such support plates can be connected in series, each with associated storage devices 30, according to the example in FIG. 4.

If, because of the lack of internal material movement, the particles tend to adhere to one another more strongly, which supports the cohesion of the material bed in its respective form, this is advantageous in the context of the invention, because this reduces the risk that the material bed in the initial region of the support plate under the Backstroke evens back pressure acting on it.

A major advantage of the cooler according to the invention is that the material is protected. It is therefore also suitable for sensitive goods such as Expanded clay. It also has the advantage that it is easier to achieve a uniform air distribution than in grate types in which internal material movement takes place.

The compressed air supply 35 to the chamber 23 is controlled so that the pressure during the return stroke is greater than during the Advancing stroke. This reduces the friction of the material bed 20 on the support plate 20. Less energy is required to retract the support plate under the bed 20.

The remaining of the material bed relative to the moving back support plate can also be promoted in that the material bed is bordered laterally by stationary walls 36, the inner surfaces of which are inclined at an angle 37 with respect to the direction of movement of the support plate 10 in such a way that their distance in Funding direction expanded. If the material bed 20 tends to follow the support plate during the return movement, it is increasingly narrowed by the inner surfaces of the walls 36, as a result of which a restraining force is exerted on the material bed 20 in addition to the backing resistance of the end face 30. When the walls 36 are connected to and move with the support plate, the walls reinforce the frictional engagement with the material during the preliminary stroke.

Instead of or in addition to this inclination, retaining devices 38 can be provided in the walls 36 or in other stationary structures of the device, only one of which is indicated in FIG. 7. These are slides or flaps or the like, which are controlled by means of a drive 39 in such a way that they protrude into the material bed 20 during the return stroke of the support plate 10 in order to hold it in place while they are retracted during the advance stroke of the support plate 10 , Such retention devices can also act on the material bed 20 from above or through the support plate 10 from below. In Fig. 6 it is indicated that a similar retaining device 40 with drive 41 is arranged in the support plate. It moves back and forth with the support plate. During the forward stroke of the support plate, the retaining device 40 projects into the material bed in order to take it along with the support plate.

During the return stroke of the support plate, it is withdrawn from the material bed so as not to hinder the relative movement between the material bed and the support plate. A large number of the retaining devices 38, 40 can be arranged in a suitable manner along the course of the material bed.

According to FIG. 8, transverse, stationary beams 45 are provided above the support plate 10, which inhibit a return movement of the material bed together with the support plate 10 during its return stroke. Their cross-section is preferably chosen so that the inhibition of the material movement in the back direction is stronger than in the conveying direction. In the example shown, they have a triangular shape with a tip pointing counter to the conveying direction and are arranged at a short distance above the support plate 10.

6 illustrates a layer height limiter 42 which is arranged in the cooler housing 1 as a fixed or height-adjustable wall. Its lower edge 43 determines the maximum height of the material bed 20. In the conveying direction in front of the wall

42, a buffer space is formed, in which the embankment 5 forms a buffer volume in the event of a temporarily greater amount of material.

The distance of the wall 42 from the storage plate 30 should be smaller than the height of the lower edge 43 of the wall 42 above the support plate 10.

Claims

claims

1. A method for treating, in particular for cooling, a bulk material layer (20) lying on a conveying grate (10) by means of a gas stream guided through the grate and the good layer, characterized in that the conveying grate (10) is moved back and forth in its entirety , whereby the good layer (20) is held during the return stroke and the stroke frequency is chosen so low that essentially no vertical mixing of the good layer takes place.

2. The method according to claim 1, characterized in that the stroke frequency is less than 20.

3. The method according to claim 1 or 2, characterized in that the return stroke speed is greater than the forward stroke speed.

4. The method according to any one of claims 1 to 3, characterized in that the return stroke acceleration is greater than the forward stroke acceleration.

5. The method according to any one of claims 1 to 4, characterized in that the return stroke acceleration is less than the adhesion solution acceleration.

6. The method according to any one of claims 1 to 5, characterized in that the return stroke acceleration is one third acceleration of the release solution.

7. The method according to any one of claims 1 to 6, characterized in that the gas flow is directed from the bottom upwards.

8. The method according to claim 7, characterized in that the gas speed or the pressure acting on the grate is greater during the return stroke acceleration than during the forward stroke.

9. Device for treating, in particular cooling, bulk material with a gas, which has a grate (10) which conveys a layer (20) of the bulk material from a feed end to a discharge end, which has gas passage openings and with means for producing the grate (10) and the gas layer passing through the material layer (20), characterized in that the grate (10) is formed by a support plate (10) moved back and forth in the conveying direction, at the end of which a device (30) for stowing the good layer is provided when it moves back.

10. The device according to claim 9, characterized in that the storage device is formed by a stationary storage surface (30).

11. The device according to claim 9 or 10, characterized in that the support plate (10) is sealed on the sides against a housing (25).

12. The device according to one of claims 9 to 11, characterized in that the support plate is provided with moving side walls.

13. Device according to one of claims 9 to 11, characterized in that the support plate (10) is free of moving side walls.

14. Device according to one of claims 9 to 13, characterized in that the support plate (10) is sealed at the feed end and / or discharge end against stationary components.

15. The apparatus according to claim 14, characterized in that the seal provided at the end of the task is formed by a support plate (10) overlapping and yieldingly pressed on the upper side of the sealing plate (32).

16. The method according to claim 15, characterized in that the sealing plate (32) is permeable to air and acted upon by a gas stream.

17. Device according to one of claims 9 to 16, characterized in that the gas flow is directed from the bottom upwards.

18. Device according to one of claims 9 to 17, characterized in that a plurality of support plates (10) with a common stowage device (30) are provided at the end of the task.

19. Device according to one of claims 9 to 17, characterized in that a plurality of support plates (10) or groups of support plates, each with a storage device (30) are arranged one behind the other.

20. Device according to one of claims 9 to 19, characterized in that the support plate is equipped with means for holding a thin layer of material in relation to the height of the material bed.

21. The apparatus according to claim 20, characterized in that the devices are formed by ribs and / or troughs.

22. Device according to one of claims 9 to 21, characterized in that means for inhibiting the flow of material are provided.

23. The device according to claim 22, characterized in that the means for inhibiting the flow of material are provided in the edge region of the grate.

24. The device according to claim 22 or 23, characterized in that the means for inhibiting the flow of material are firmly connected to the support plate.

25. Device according to one of claims 22 to 24, characterized in that the means for inhibiting the flow of material are movable.

26. The apparatus according to claim 25, characterized in that a control device for moving the means for inhibiting the material flow is provided depending on the condition of the material bed.

27.The device according to one of claims 9 to 26, characterized in that means for reducing the frictional engagement between the material bed (20) and the support plate (10) are provided during the return stroke compared to the preliminary stroke.

28. The apparatus according to claim 27, characterized in that a device for increasing the gas pressure acting in the support plate (10) during the return stroke compared to the preliminary stroke is provided.

29. The device according to claim 27, characterized in that with the support plate (10) connected, less on the return stroke and stronger in the forward stroke engaging holding members (40) are provided.

30. Device according to one of claims 9 to 27, characterized in that two stationary or together with the support plate (10) moving, the material bed (20) delimiting side walls are provided, the clear distance increases in the conveying direction.

31.Device according to one of claims 9 to 30, characterized in that means for increasing the frictional engagement between the material bed (20) and stationary parts of the device during the return stroke are provided in comparison with the preliminary stroke.

32.Device according to claim 31, characterized in that with the fixed structure (36) of the device connected, stronger during the return stroke and less during the forward stroke engaging in the material bed (20) holding members (38) are provided.

33. Apparatus according to claim 32, characterized in that a pair of walls (36) enclosing the material bed (20) laterally is provided, the clear distance of which increases in the conveying direction.

34. Device according to one of claims 9 to 33, characterized in that a layer height limiter (42, 43) is provided at the end of the task.

35.Device according to one of claims 1 to 34, characterized in that above the support plate (10) at a height which is less than the height provided for the material bed (20), at least one crossbeam (45) at a distance from the end of the task and is provided by the end of the delivery.

36. Apparatus according to claim 35, characterized in that the bar (45) opposes the material flow in the conveying direction a lower resistance than in the opposite direction.

37. Apparatus according to claim 35 and 36, characterized in that the beam (45) is arranged closer to the support plate (10) than the height provided for the material bed.

38. Device according to one of claims 35 to 37, characterized in that the at least one bar (45) has a flat triangular profile with the tip pointing counter to the conveying direction.