BE1027670B1 - Cooler for cooling bulk goods - Google Patents

Abstract

The present invention relates to a cooler (10) for cooling bulk material (12), in particular cement clinker, having a first conveyor unit (14) with a plurality of conveyor elements for transporting the bulk material (12) in the conveying direction and an aeration floor (20) through which cooling gas can flow. for receiving the bulk material (12), and at least one side wall (34, 36) which is at least partially arranged above the ventilation base (20), at least one second conveyor unit (16) being provided for transporting the bulk material (12) in the conveying direction (F) which at least partially forms the side wall (34, 36).

Description

Cooler for cooling bulk material The invention relates to a cooler for cooling bulk material, in particular cement clinker, which has been previously burned in a furnace.

For cooling hot bulk material, such as cement clinker, for example, it is known that the bulk material is placed on an aeration base of a cooler through which a cooling medium, such as cooling gas, can flow. The hot bulk material is then moved from one end of the cooler to the other end for cooling, while cooling gas flows through it.

Various possibilities are known for transporting the bulk material from the beginning of the cooler to the end of the cooler. In the case of a so-called sliding grate cooler, the bulk material is transported by movable conveying elements that move in the conveying direction and against the conveying direction. The conveyor elements have a pushing edge that transports the material in the conveying direction.

From DE 100 18 142 B4 a cooler is known which has a plurality of conveyor elements that can be moved in the conveying direction and against the conveying direction. Each of the conveyor elements is connected to suitable transport mechanisms via a carrier element, which supports the conveyor elements movably on a machine frame structure. The material is transported in the conveying direction by means of a suitable movement pattern in the forward and return strokes.

From EP 2021692 B2 a cooler is known which has a plurality of conveyor elements that can be moved in the conveying direction and against the conveying direction. The conveyor elements are attached to a frame structure which is mounted on the machine frame via bearings. The conveying elements have a shape that enables them to be transported in the conveying direction.

The clinker bed usually rests on the conveyor elements and / or the aeration floor, with the clinker being difficult to transport when the clinker layer is thick. The material layer thickness for classically operated clinker coolers is usually between 400-800mm. This reduces the

The conveying efficiency of the cooler is considerable, which is why the transport of high layers of material in known coolers is not possible, or only very inefficiently. Based on this, it is the object of the present invention to provide a cooler with which the transport and simultaneous cooling of bulk material with a high material layer thickness, in particular greater than 400-800 mm, is possible. According to the invention, this object is achieved by a cooler having the features of the independent device claim 1. Advantageous developments result from the dependent claims. According to a first aspect, a cooler for cooling bulk material, in particular cement clinker, comprises a first conveyor unit which has a plurality of conveyor elements for transporting the bulk material in the conveying direction and an aeration base through which cooling gas can flow for receiving the bulk material. The cooler further comprises at least one side wall which is at least partially arranged above the ventilation base. The side wall is at least partially formed by a second conveyor unit for transporting the bulk material in the conveying direction and / or for reducing the friction between the bulk material and the side wall.

The cooler is preferably a clinker cooler which is arranged, for example, in connection with an oven, in particular a rotary kiln, for the production of cement clinker. The clinker has a conveying unit for transporting the material in the conveying direction, which has a ventilation base through which cooling gas can flow and which has a plurality of passage openings for admitting cooling air. The cooling air is provided, for example, by fans arranged below the ventilation floor, so that cooling air flows through the bulk material to be cooled in a cross-flow to the conveying direction. The ventilation base of the first conveyor unit preferably forms a plane on which the bulk material rests. The ventilation base is preferably formed partially or completely by the conveying elements, which are arranged next to one another and form a plane for receiving the bulk material.

The at least one side wall is arranged to the side and above the ventilation base and preferably forms a side delimitation to prevent bulk material from flowing out of the cooler.

The cooler preferably has a housing with two side walls and, for example, a top wall, the side walls preferably being parallel to one another.

In particular, the side wall has an angle of, for example, 10 ° to 90 °, preferably 30 ° to 60 °, in particular 45 °, to the ventilation base.

The side walls which lie opposite one another and adjoin the ventilation base preferably have the same angle to the ventilation base.

It is also conceivable that the side walls have different angles to the ventilation base.

The at least one side wall is in particular at least partially ventilated so that cooling air flows through the side wall into the bulk material.

For this purpose, the side wall preferably has a plurality of air passages which, for example, are arranged, in particular evenly spaced from one another, over the entire length of the side wall.

The conveyor elements of the first conveyor unit and the aeration base form the support surface for the bulk material to be cooled and are preferably arranged essentially horizontally.

Essentially, it is to be understood that slight gradients in the material flow direction of up to +/- 5 ° are included.

The ventilation floor is, for example, a grate and extends over the entire length of the cooler.

The conveying elements are preferably arranged to be movable in the conveying direction and preferably against the conveying direction of the bulk material.

The conveying elements of the first, bottom-side conveying device are preferably arranged parallel to the conveying elements of the second, lateral conveying unit.

The second conveyor unit preferably at least partially forms the side wall directly adjoining the first conveyor unit.

In particular, the conveyor unit forms the lower region of the side wall, preferably at least one third of the side wall.

The ventilation base of the first conveyor device is preferably designed in such a way that it can transport bulk material with a layer height of approximately at least 600 mm.

The second conveyor unit serves at least partially to convey the bulk material in the conveying direction or transversely to the conveying direction.

The second conveyor unit is used, for example, to reduce the friction between the bulk material and the side walls of the cooler.

A second conveyor unit, which at least partially forms a side wall of the cooler, offers the possibility of being able to transport high layer heights of at least 800 mm over the length of the cooler.

The side conveyor unit supports the bottom conveyor unit and also prevents material from sticking to the inside of the side walls.

According to a first embodiment, the second conveying device is designed in such a way that it transports the bulk material pneumatically and / or mechanically in the conveying direction.

The first conveyor unit is preferably designed such that it transports the bulk material mechanically, the second conveyor unit being designed such that it transports the bulk material at least partially or exclusively pneumatically, by means of compressed air.

It is also conceivable to design all of the cooler's conveyor units as pneumatic transport means.

Pneumatic transport of the bulk material offers a simple way of transporting the bulk material along the cooler.

In particular on the side walls, the pneumatic transport and the compressed air required for this reliably prevent the material from sticking to the side wall.

For the pneumatic transport of the material by means of the lateral conveyor units, for example, air pressures of 0.1 to 10 bar are applied and guided into the bulk material via nozzles, for example by means of compressed air pulses, in the side wall.

According to a further embodiment, the second conveyor device has at least one movable conveyor element.

The second conveyor device preferably has a plurality of movable conveyor elements.

A second conveying unit with movable conveying elements enables the bulk material to be conveyed in a targeted manner, preferably as a function of the conveying speed of the first conveying unit.

According to a further embodiment, the second delivery unit has at least one compressed air channel for letting compressed air into the cooler.

The second conveyor unit preferably has a plurality of compressed air channels, in particular nozzle openings, through which compressed air can flow into the cooler in a stationary or movable side wall element.

The compressed air channels are preferably arranged at a uniform distance from one another.

For example, the compressed air channels are subjected to a pressure of 0.1 to 10 bar.

According to a further embodiment, the first and / or the second conveyor unit has a plurality of conveyor elements movable in the conveying direction and against the conveying direction.

For example, at least one conveying element has a compressed air channel for letting compressed air into the cooler.

The ventilation base of the first conveyor unit is formed, for example, by a plurality of conveyor elements, each of which has openings for admitting cooling air into the cooler.

To transport the bulk material in the conveying direction, the conveying elements are preferably moved simultaneously in the conveying direction and non-simultaneously against the conveying direction.

According to a further embodiment, the conveying elements of the first and / or the second conveying unit are planks through which cooling air can flow.

In particular, the conveyor elements are arranged next to one another, preferably to form a plane, and each have a plurality of air passages for admitting cooling air into the cooler.

For example, the conveyor elements are designed as grate planks.

The ventilation floor comprises, for example, a plurality of the movable planks.

This enables the bulk material to be conveyed particularly easily.

According to a further embodiment, the first conveyor unit has conveyor elements which can be moved relative to the aeration base, the aeration base being static.

According to a further embodiment, the second conveyor unit has a static side wall element and conveyor elements which can be moved relative to the side wall element.

The conveying elements are preferably arranged above the aeration base and to the side of the static side wall element and each have a plurality of drivers, which in particular run transversely to the conveying direction.

The conveying elements are arranged parallel to one another and at the same time attached so as to be movable in and non-simultaneously against the conveying direction.

The conveyor elements are, for example, conveyor screws which are arranged parallel to one another in depressions in the aeration base or the static side wall element.

The side wall of the cooler preferably has an upper wall area and the second conveyor unit, the static side wall element of the second conveyor unit being firmly connected to the upper wall area and not being movable relative to it.

According to a further embodiment, the conveyor elements of the first and / or the second conveyor unit are vibration plates which are connected to a vibration drive.

The vibration drive is connected to the at least one vibration plate in such a way that it is set in vibration.

The cooler has at least one or a plurality of vibration drives, each of which is connected to at least one vibration plate in order to drive it.

The vibration plates have, for example, openings for admitting cooling air and / or compressed air channels for admitting compressed air into the cooler.

In particular, the vibration plates prevent bulk material from sticking to the side wall, in particular to the lower area of the side wall, while at the same time reducing the friction of the bulk material on the inner wall surface formed by the vibration plate and thus facilitating the transport of the bulk material along the side wall.

According to a further embodiment, the first and the second conveyor unit are designed in such a way that they operate according to the same conveyor principle.

According to a further embodiment, the first and the second delivery unit are designed in such a way that they operate according to different delivery principles.

According to a further embodiment, the first and / or the second conveyor unit each have openings for the passage of cooling air into the cooler.

According to a further embodiment, the second conveyor device extends over at least 20 to 50%, preferably 25 to 35%, in particular 30% of the height of the side wall.

It preferably extends the static side wall element or the at least one conveying element of the second conveying unit over the said height of the side wall.

With a high layer thickness of the bulk material of at least 600 mm, the pressure within the bulk material is high, especially in the lower third of the bulk material bed, and causes increased frictional resistance on the inner side wall.

A conveyor unit in the lower third of the side wall reduces this effect.

The cooler has, for example, a third delivery unit which at least partially forms a further side wall of the cooler.

In particular, the third conveyor unit is arranged opposite the second conveyor unit in the opposite side wall of the cooler.

The second and third conveying units are designed, for example, in such a way that they work according to the same conveying principle and have the same components.

The third conveyor unit is preferably configured identically to the second conveyor unit.

The third conveyor unit is designed, for example, as a pneumatic or mechanical transport means.

Description of the drawings The invention is explained in more detail below on the basis of several exemplary embodiments with reference to the accompanying figures.

Fig. 1 shows a cooler for cooling bulk goods according to an embodiment.

2 to 6 each show a cooler for cooling bulk goods according to a further exemplary embodiment.

1 shows a cooler 10 for cooling bulk material 12. The bulk material is, for example, cement clinker which falls from an oven, preferably a rotary kiln, into the cooler 10 and is cooled there.

The bulk material 12 to be cooled has, for example, a temperature of 1200 to 1450 ° C when it enters the cooler 10 and is cooled to a temperature of 50 to 200 ° C.

The cooler 10 has a first conveyor unit 14, a second conveyor unit 16 and a third conveyor unit 18, which each serve to transport the bulk material 12 in the conveying direction F.

The first conveyor unit 18 comprises a ventilation base 20 on which the bulk material 12 to be cooled rests.

The ventilation base has in particular a plurality of openings 22 for admitting cooling air into the cooler 10 and is designed, for example, as a grate.

The cooling air preferably flows from a cooler area below the ventilation base 12 through the openings 22 and enters the bulk material 12.

The bulk material is preferably traversed by the cooling air transversely to the conveying direction F.

The ventilation floor 20 comprises, for example, a plurality of grate elements, in particular grate planks, which are arranged next to one another.

For example, the grate elements each have a plurality of cooling grids arranged one behind the other. It is also conceivable that the ventilation base 20 is designed in one piece. Furthermore, the ventilation base 20 of the first conveyor unit 14 has passages through which a conveyor element 24 extends in each case. By way of example, the first conveyor unit has nine conveyor elements which are arranged parallel to one another. The conveyor elements 24 have, for example, a T-shaped profile. The conveying elements preferably extend along the entire extent of the aeration base 12 and each have, for example, a plurality of catches 26 that extend transversely to the conveying direction F and are evenly spaced from one another.

The first conveyor unit 14 is, for example, a conveyor unit operating according to the push conveyor principle, the conveyor elements 24 being attached so as to be movable relative to the stationary aeration base 12. During operation of the cooler 10, the conveyor elements 24 are moved simultaneously in the conveying direction F and non-simultaneously against the conveying direction F, preferably according to the “walking floor principle”. Overall, this results in a movement of the bulk material 12 lying on the conveyor elements 24 and the aeration base 12 in the conveying direction, since the individually moved back conveyor elements 24 do not convey the bulk material 12. The support surface for the bulk material is formed in the first conveyor unit by the upwardly facing surfaces of the drivers 26 and of the aeration base 20 and extends, for example, essentially horizontally. Essentially horizontal is to be understood as a horizontal alignment and a slight slope of about 10 °.

Below the first conveying unit 14 of the cooler 10, two ventilation chambers 28 are arranged by way of example, in which there are preferably fans 30 which blow cooling air from below through the ventilation base 20.

The cooler 10 has a housing 32 which comprises two side walls 34, 36 and a top wall 38. The side walls 34, 36 extend, for example, essentially vertically and perpendicular to the aeration base 20 of the first conveyor unit 14. Each of the side walls 34, 36 includes a further one of the second and third conveyor units 16, 18. The second and third conveyor units 16, 18 each form the lower area of the side walls 34, 36 from. For example, the second and third conveyor units 16, 18 each include the entire lower region of the side walls 34, 36 pointing in the direction of the first conveyor unit 14.

The side walls 34, 36 each include an upper wall area 44, 46 and conveyor units 16, 18 adjoining them at the bottom. The first and second conveyor units 16, 18 each include a static side wall element 40, 42, which is located in the exemplary embodiment in FIG. 1 extends vertically by way of example. The static side wall element 40, 42 is, for example, one or a plurality of grate planks arranged next to one another, which are preferably arranged in alignment with the respective upper wall area 44, 46. It is also conceivable to design the static side wall elements 40, 42 as plates without passages for admitting cooling air or compressed air. In the exemplary embodiment in FIG. 1, one of the static side wall elements 40, 42 is designed with passages, for example as a grate plank, with cooling air flowing through it, which is blown through the static side wall element 40 by means of a fan 48. The cooling air can be constant or dynamically pulsating. The other of the two static side wall elements 40, 42 is designed, for example, as a plate without openings. The static side wall elements 40, 42 extend, for example, over the entire length of the cooler 10, parallel to the ventilation base. At least one static side wall element 40, 42 is preferably aligned perpendicular to the ventilation base. It is also conceivable to arrange one or more static side wall elements 40, 42 at an angle of approximately 30-90 °, preferably 40-80 °, in particular 45 °, to the ventilation base. The conveyor units 16, 18, in particular the static side walls 40, 42 extend, for example, over about a quarter of the height of the respective side wall 34, 36 of the cooler 10. It is also conceivable that the conveyor units 16, 18 extend over a third, half or extend the entire height of the side wall 34, 36 of the cooler 10.

The second and third conveyor units 16, 18 each have at least one conveyor element 50, 52, which correspond to the conveyor elements 24 described above and are mounted so as to be movable relative to the respective static side walls 40, 42 in the conveying direction F and counter to the conveying direction F. The

Carriers of the conveyor elements 50, 52 extend essentially parallel to the respective static side walls 40, 42. When the cooler 10 of FIG. 1 is in operation, the bulk material 12 is moved in the conveying direction by means of the first, second and third conveyor units 14, 16, 18, the second and third conveying units 16, 18 preventing the bulk material 12 from sticking to the inside of the side walls 34, 36 and additionally causing the bulk material 12 to be conveyed by moving the conveying elements 50, 52. The conveying elements 50, 52 are moved, for example, simultaneously with the conveying elements 24 of the first conveying unit 14 in the conveying direction F and at the same time against the conveying direction F. It is also conceivable that the first and / or the second conveyor unit 16, 18 each have a plurality of conveyor elements 50, 52. In this case, the conveying elements in the conveying unit 16, 18 would move according to the principle of a walking floor conveyor in order to enable the highest possible conveying efficiency.

Depending on the requirements, the second and third conveyor units can be identical or different. Fig. 2 shows the cooler 10 according to a further embodiment. The elements denoted by the same reference symbols correspond to the elements described with reference to FIG. 1. In contrast to the exemplary embodiment in FIG. 1, the conveying units 14, 16, 18 are designed in such a way that they can be operated according to a different conveying principle, namely that of a moving floor conveyor, in particular according to the “walking floor principle”. The conveyor units 14, 16, 18 each have a ventilation base 20, which is formed from a plurality of planks 54, 56, 58, the planks 54, 56, 58, for example, having passages for admitting cooling air into the bulk material 12. The planks 54, 56, 58 are each arranged to be movable in the conveying direction F and counter to the conveying direction F independently of one another. To transport the bulk material 12 in the conveying direction F, all the planks 54, 56, 58 are moved simultaneously in the conveying direction and at the same time avoiding the conveying direction F, so that the bulk material 12 as a whole experiences a movement in the conveying direction. For example, in the exemplary embodiment in FIG. 2, cooling air flows through only the first and second conveyor units 14, 16. The third conveyor unit 18 has planks 58 which have no passages for cooling air. Optionally, all conveyor units are designed in such a way that cooling air flows through the planks 54, 56, 58, each

Planks 54, 56, 58 has passages for cooling air and is designed, for example, as a grate.

In the exemplary embodiment in FIG. 1, the side walls 34, 36 each include a conveyor unit 16, 18, this having two parallel planks 56, 58, for example.

The conveyor units 16, 18 can also each have only one or a plurality of planks, for example two, four or six planks.

The planks 54, 56, 58 preferably extend over the entire length of the cooler 10 and move like a walking floor conveyor.

The second and third conveying units 16, 18 can, for example, be designed identically or in mirror image, with or without cooling air, which can be designed to be pulsating.

FIG. 3 shows a further exemplary embodiment of a cooler 10, this essentially corresponding to the exemplary embodiment in FIG. 2 with the difference that the conveyor units 16, 18 contained in the side walls are arranged at an angle to the first conveyor unit 14 that is approximately 20-60 °, preferably 30-50 °, in particular 45 °.

Furthermore, the second and third conveyor units 16, 18 each have three planks 56, 58, for example, which can be moved simultaneously in conveying direction F and non-simultaneously against conveying direction F, for example according to the “walking floor principle”.

The upper wall areas 44, 46 of the side walls 32, 34 each adjoin a conveyor unit 16, 18 and extend essentially in the vertical direction, perpendicular to the first conveyor unit 14. FIG. 4 shows the cooler 10 according to a further exemplary embodiment.

The elements denoted by the same reference symbols correspond to the elements described with reference to FIG. 1, 2 or 3.

In contrast to the exemplary embodiments described above, the conveyor units 14, 16, 18 of the cooler in FIG. 4 each have a plurality of conveyor screws 60 which extend in the conveying direction F.

The first delivery unit 14, which forms the base of the cooler 10, has a ventilation base 20, which has a plurality of openings 22 for admitting cooling air into the cooler 10.

The aeration base 20 also has, for example, depressions 62 in each of which a screw conveyor 62 is arranged.

The depressions 62 are arranged transversely to the conveying direction F, for example, evenly spaced from one another, the conveyor screws 60 each being partially arranged within the depression.

The lateral conveyor units 16, 18 each have, for example, a static side wall element 40, 42, in each of which a recess for at least partially receiving a conveyor screw 64, 66 is formed.

For example, the lateral conveyor units 16, 18 each have a conveyor screw 64, 66, with a plurality of conveyor screws, for example two or three, also being conceivable.

By way of example, only the first and second conveyor units 14, 16 have cooling air flowing through them.

Cooling air can also flow through the third delivery unit, the static side wall element having passages for cooling air and being connected to at least one fan 30, 48.

In the conveying direction F, the conveying units 14, 16, 18 have, for example, a plurality of conveying screws arranged one behind the other, which are arranged together in a recess 62.

When the cooler 10 of FIG. 4 is in operation, the bulk material 12 is transported in the conveying direction F by means of the conveying screws, in particular continuously.

The screw conveyors of the lateral conveyor units 16, 18 prevent the material from sticking to the side walls 34, 36 and also support the conveyance of the bulk material 12 in the conveying direction F.

FIG. 5 shows a further exemplary embodiment of a cooler 10, this essentially corresponding to the exemplary embodiment in FIG. 2 with the difference that the conveyor units 16, 18 comprised in the side walls 34, 36 each include a static side wall element 40, 42, each of which has a plurality of passages through which compressed air can flow into the cooler 10.

The passages are, for example, nozzle-shaped.

Each conveying unit 16, 18 is assigned, for example, a compressed air generator 68, which guides compressed air to the passages of the side wall elements 40, 42.

Static and / or dynamic or pulsating ventilation through the side wall elements 40, 42 via a fan 48, as for example in FIG. 1, 2 or 4, with an optional downstream valve, in particular a pulsator, is also conceivable.

The pulsator ensures a pulsating flow of cooling air into the bulk material through the passages in the side wall elements 40, 42. The pulsating ventilation of the cooler side walls reduces the wall friction effects so that high layers of material are made possible in the cooler.

The side wall elements 40, 42 can be acted upon wholly or partially with pulsating cooling air. The passages can be arranged in the lower third or in the middle of the side wall elements 40, 42. An arrangement in the upper third of the side wall elements 40, 42 is also conceivable in order to counter the Red River problem. The ventilation of the side wall elements 40, 42 can be identical or different. For example, only one of the side wall elements 40, 42 is acted upon by pulsating air. For the ventilation of the side wall elements 40, 42, for example, ventilation boxes are attached in the side wall elements 40, 42.

The first conveyor unit 14 corresponds, for example, to the conveyor unit 14 shown in FIG. 3, which works according to the “walking floor principle”. Another exemplary embodiment comprises, for example, a first conveyor unit 14 according to FIG. 1 or 3.

FIG. 6 shows a further exemplary embodiment of a cooler 10, this essentially corresponding to the exemplary embodiment in FIG. 5 with the difference that the conveyor units 16, 18 included in the side walls 34, 36 each include a static side wall element 40, 42 that is plate-shaped is formed and, for example, has a plurality of air passages for admitting cooling air into the radiator. A vibration device 70 is attached to each of the static side wall elements 40, 42, by means of which the static side wall elements 40, 42 are vibrated. Preferably, only the static side wall elements 40, 42 are set into vibrating oscillation by the respective vibration device 70, 72. Such a conveyor unit 16, 18 supports the transport of the bulk material 12 in the conveying direction and prevents the material from sticking to the side walls 34, 36.

The conveying techniques shown in FIGS. 1-6 represent only an extract from the technical possibilities. In general, practically all conveying techniques from bulk material technology are conceivable for the first, second and third conveying units.

LIST OF REFERENCE NUMERALS 10 cooler 12 bulk material 14 first conveyor unit 16 second conveyor unit 18 third conveyor unit 20 ventilation base 22 openings 24 conveyor elements 26 driver 28 ventilation chamber 30 fan 32 housing 34 side wall 36 side wall 38 top wall 40 static side wall element 42 static side wall element 44 wall area 46 wall area 48 fan 50 conveying element 52 conveying element 54 planks 56 planks 58 planks 60 screw conveyor 62 recess 64 screw conveyor 66 screw conveyor 68 compressed air generator 70 vibration device 72 vibration device

Claims (13)

Claims 1. Cooler (10) for cooling bulk material (12), in particular cement clinker, comprising a first conveyor unit (14) with a plurality of conveyor elements for transporting the bulk material (12) in the conveying direction and an aeration base (20) through which cooling gas can flow for receiving the Bulk material (12), and at least one side wall (34, 36), which is at least partially arranged above the aeration base (20), characterized in that at least one second conveyor unit (16) for transporting the bulk material (12) in the conveying direction (F) and / or is provided to reduce the friction between the bulk material (12) and the side wall (34, 36), which at least partially forms the side wall (34, 36). 2. Cooler (10) according to one of the preceding claims, wherein the second conveying device (16) is designed such that it transports the bulk material (12) pneumatically and / or mechanically in the conveying direction. 3. Cooler (10) according to one of the preceding claims, wherein the second conveyor device (16) has at least one movable conveyor element (50, 52, 56, 58, 64, 66). 4. cooler (10) according to any one of the preceding claims, wherein the second conveyor unit (16) has at least one compressed air channel for letting compressed air into the cooler (10). 5. Cooler (10) according to one of the preceding claims, wherein the first and / or the second conveyor unit (14, 16) has a plurality of conveyor elements (24, 50, 52, 54, 56, 58) movable in the conveying direction and counter to the conveying direction. having. 6. Cooler (10) according to one of the preceding claims, wherein the conveyor elements (50, 52, 54, 56, 58) of the first and / or the second conveyor unit are planks through which cooling air can flow. 7. Cooler (10) according to one of the preceding claims, wherein the first conveyor unit (14) has conveyor elements (24) which are movable relative to the ventilation base (20), wherein the ventilation base (20) is static. 8. cooler (10) according to any one of the preceding claims, wherein the second conveyor unit (16) comprises a static side wall element (40, 42) and conveyor elements (50, 52) which are movable relative to the side wall element (40, 42). 9. Cooler (10) according to one of the preceding claims, wherein the conveyor elements (40, 42) of the first and / or the second conveyor unit are vibration plates which are connected to a vibration device (70, 72) for vibrating the vibration plates. 10. cooler (10) according to any one of the preceding claims, wherein the first and the second conveyor unit (14, 16) operate on the same conveying principle. 11. Cooler (10) according to one of the preceding claims 1-9, wherein the first and the second conveyor unit (14, 16) operate according to different conveying principles. 12. Cooler (10) according to one of the preceding claims, wherein the first and / or the second conveyor unit (14, 16) has / have openings (22) for the passage of cooling air. 13. Cooler (10) according to one of the preceding claims, wherein the second conveyor device (16) extends over at least 20-40%, preferably 25-35%, in particular 30% of the height of the side wall (34, 36).