US3842516A

US3842516A - Shaft cooler construction

Info

Publication number: US3842516A
Application number: US00386542A
Authority: US
Inventors: W Speissegger; H Baumeler
Original assignee: Buehler AG
Current assignee: Buehler AG
Priority date: 1972-08-24
Filing date: 1973-08-08
Publication date: 1974-10-22
Anticipated expiration: 1991-10-22
Also published as: DE2342842A1; JPS5142032B2; DK145071C; FR2197151B1; DK145071B; DE2342842C3; DE2342842B2; GB1439285A; NL7309802A; CH555036A; IT991237B; ES416996A1; FR2197151A1; JPS4966452A

Abstract

A cooling tower for feed cubes comprises a plurality of vertically stacked tubular shaft elements each having a plurality of transversely spaced parallel air delivery roofs located at a first upper level and a plurality of transversely spaced air feed control roofs at a second lower level. The feed control roofs are located so that their peaks are oriented between a pair of the air delivery roofs. The air delivery roofs are connected laterally to a vertically disposed exhaust conduit which is arranged along side the shaft. The air feed control roofs are air permeable and have openings at their bottoms. A separator is provided in the connection between the exhaust conduit and the air delivery roofs. An air throttle is also located in the connection to the exhaust conduit and it is actuated by a flap which is engaged by the feed cubes as they are directed into the shaft elements over the air delivery roofs. The air throttle includes a locking arrangement to fix the extreme positions of the throttle. The elements are stacked above a lower cube discharge unit which is provided with a vibration generation system and the main direction of the vibration of the cube discharge element is oriented transverse to the air feed roofs.

Description

United States Patent Speissegger et al.

[ 51 Oct. 22, 1974 SHAFT COOLER CONSTRUCTION [75] Inventors: Werner Speissegger, Hauptwil; Hans Baumeler, Uzwil, both of Switzerland [73] Assignce: Gebruder Buehler AG, St. Gallen,

Switzerland [22] Filed: Aug. 8, 1973 [2]] Appl. No.2 386,542

[30] Foreign Application Priority Data Aug. 24, 1972 Switzerland 12577/72 [52] US. Cl 34/170, 34/10, 34/57, 34/20, 34/5 [51] Int. Cl. i. F26b 17/12 [58] Field of Search 34/10, 57 A, 20, 5, 170

[56] References Cited UNITED STATES PATENTS 278.356 5/1883 Nicsc 34/170 l.737,()6l ll/l929 Ryder 34/20 2,276,496 3/1942 Kennedy... 34/l70 3,332,780 7/1967 Smith 34/10 Primary Erartziner william J, Wye Attorney, Agent, or FirmMcGlew and Tuttle 5 7 ABSTRACT A cooling tower for feed cubes comprises a plurality of vertically stacked tubular shaft elements each having a plurality of transversely spaced parallel air delivery roofs located at a first upper level and a plurality of transversely spaced air feed control roofs at a second lower level. The feed control roofs are located so that their peaks are oriented between a pair of the air delivery roofs. The air delivery roofs are connected laterally to a vertically disposed exhaust conduit which is arranged along side the shaft. The air feed control roofs are air permeable and have openings at their bottoms. A separator is provided in the connection between the exhaust conduit and the air delivery roofs. An air throttle is also located in the connection to the exhaust conduit and it is actuated by a flap which is engaged by the feed cubes as they are directed into the shaft elements over the air delivery roofs. The air throttle includes a locking arrangement to fix the extreme positions of the throttle The elements are stacked above a lower cube discharge unit which is provided with a vibration generation system and the main direction of the vibration of the cube discharge element is oriented transverse to the air feed roofs.

VII

PATENTED E-2 SHEEIMIFd SHAFT COOLER CONSTRUCTION BACKGROUND OF THE INVENTION 1. FIELD OF THE INVENTION This invention relates in general to the construction of food material handling devices and, in particular, to a new and useful shaft cooler for feed cubes which includes a plurality of vertically stacked shaft elements each containing a plurality of transversely spaced parallel air delivery roofs at a first upper level and a plurality of transversely spaced air feed control roofs at a second lower level.

2. DESCRIPTION OF THE PRIOR ART Some feeds are produced in cubes in order to bring them into a form which is favorable for the intake and digestion by the animals. It is desirable to make the protein of such cubes digestible. Protein is unpleasantly sticky when it is freshly pressed.

If cubes are to be produced which have the conventional physical properties, a shaft cooler is used after pressing which is suitable for this purpose. Shaft coolers have if possible only air permeable obstacles, otherwise the cubes would get stuck in the upper part of the shaft and would clog the entire cooler. In a known embodiment of this type, the entire cooler is composed of individual elements. Apart from the upper part and the discharge element, each shaft element has a pair of air ducts, in the center a triangular closed delivery duct, and at both sides thereof, there is a half feed duct. In the upper part of the shaft is arranged a combination screening and distributing unit which can, in addition, be connected directly to the discharge element. The output and the duration of the cooling process is determined by the number of shaft elements. A vibrating discharge device is provided at the lower end of the shaft which is equipped with a terminal sieve. A switch contact arranged in the upper part of the shaft switches the entire combination on or off, so that the cooler, once it is full, always remains full and secondary air exhaust is thus prevented. The total emptying of the cooler can be effected with a special switch.

Depending on the desired output and the necessary air throughout, a different number of fans can be used.

The freshly pressed feed cubes are characterized by great moisture and high temperature. But a high mois ture content and temperature are not advantageous, for storage, so that the feed cubes are treated with the socalled cube cooling. The frequently used saying that one rotten apple affects seven others also applies to a cube cooler. A cooler can have zones above which cubes are not cooled or poorly cooled. A small part of a relatively easily spoiling product is thus put into a relatively large amount and the entire production is thus jeopardized.

In the above mentioned feed cube cooler, such poorly working zones are always found. Thus, the cooled air exhaust duct is particularly susceptible to material deposits. Even a preliminary screening cannot eliminate all fine portions. Besides, cube abrasion is constantly caused by their rippling movement over the cascades. The product is deposited in the above described coolers mostly in the closed screen-duct unit opposite the exhaust. After a short time this part is filled with feed cube waste. The same process takes place in all superposed exhaust ducts. In the end effect,

no air exchange can take place anymore in the rear of the cooler, though the cubes descend at the same speed in this zone. I

The discharge element discharges cubes of varying quality. It has already been tried, particularly in these cube coolers, to prevent clogging during the operation by additional ventilation of the air exhaust duct by means of a secondary air opening. The uniformity of the cooling process can thus be slightly improved, but at the expense of the economy of the entire plant.

In these known cube collers two shaft elements are normally assigned to a fan. If the cooler has two shaft elements, the charge is at first only incompletely cooled at each product change and when the plant is started. The air takes the path of the least resistance at partial filling and flows as long as possible above the product column through the upper empty part of the shaft.

Another very annoying disadvantage appears with the arrangement of four and more shaft elements. As known, the heat and moisture are released much faster at high temperatures than at low temperatures. If the air is exhausted from the first, that is, from the highest element of a shaft cooler with an independent fan, the air supersaturated with humidity can cause the formation of condensed water with all its consequences in the exhaust line. This also results in great difficulties for the separation of dust, as well as for cleaning in general.

Another known shaft cooler for feed cubes has a central vertical air exhaust shaft, as well as ventilation flaps arranged in a great number on the two length sides over the entire height. The feed cubes themselves open these flaps by their own weight. Only those flaps are open which come into contact with the product. The upper empty part of the shaft remains closed for the passage of air. Unnecessary circulation of secondary air is thus prevented. This shaft cooler works equally well in any operating condition, whether full or partly filled. Smaller charges can be treated economically. The uniformity of the cooling and drying process is maintained in the entire cooler, since clogging of individual parts is not possible. supersaturated air is mixed in the central exhaust duct with the rest of the air. Condensed water problems do not appear in this known solution. The main difficulties of feed cube cooling are solved with this shaft cooler system and a disadvantage is only the relatively great overall height.

A cascade-type guidance of the product through the ventilation ducts, for example, of the above described type, has the advantage that the cubes are subjected to constant rearrangement, rotation, etc. Cascade coolers permit a reduction of energy consumption and also permit a more favorable utilization of the space. The main advantage of the cascade coolers lies, however, in the relatively inexpensive construction, their disadvantage in the greater susceptibility to trouble, as far as clogging and irregular cooling are concerned.

SUMMARY OF THE INVENTION The air feed roofs are arranged over the shorter shaft dimensions, are permeable to air, are open at the bottom and extend parallel to each other.

The air delivery roofs are connected to an exhaust line.

The air delivery roofs connected to the exhaust line have a separator-type transition piece to retain the feed cubes in the shaft element.

With the solution according to the invention, the shortcomings of the known shaft coolers can be successfully avoided.

Particularly the arrangement of air feed roofs open at the bottom over the shorter dimension of the shaft elements, and the separator-type design of the transition piece of the air delivery roofs connected to the exhaust line results in a reliable cooling of the cubes in an air distribution which is otherwise only possible in the solution with a plurality of superposed and individually controlled flaps distributed over the large length sides. Nevertheless, all the advantages of the cascade cooler could not only be taken over, but even further improved.

Due to the fact that the air delivery roofs are connected to the exhaust line and are conducted over the shorter shaft dimension, no locally increased air flows can be determined with the usual measuring instruments, though the air velocity is relatively high in the air delivery roofs. The air velocity can even be so selected that individual smaller parts are moved by the air toward the exhaust duct. But, if a larger amount of partly uncooled cubes are driven into the exhaust duct, they provide a danger for the entire production when fed to the finished product, since they would become moldy after a few days.

But, particularly in the combination according to the invention, the transition from the air delivery roof into the exhaust line has the form of a separator so that the feed cubes can not leave the shaft element. All cubes have exactly the same stay period in the shaft cooler, even though some cubes perform a slight horizontal movement, due to the air flow.

The combination according to the invention, permits a very intensive cooling process. Measurements showed a surprisingly favorable power consumption.

Clogging of the air feed roofs, which are open at the bottom, is not possible for obvious reasons. The cooling air can enter from the bottom unhindered through the cube layer under the air delivery roof. The air permeable roof is little susceptible to clogging, as experience has shown, since the rippling movement of the cubes has a cleaning effect.

The connection of the air delivery roofs to a common exhaust line is very economical. This measure also prevents condensed water problems.

In a particularly advantageous embodiment, an air throttle is assigned to each shaft element. Particularly for the redistribution of the air, it was found surprisingly advantageous to arrange the air throttle on the suction side between the exhaust line and the air delivery roof. If the air throttle is only slightly opened, greater air velocities through the openings are produced, due to the fan characteristic. If the air throttle is arranged on the suction side, the velocity peaks have disappeared in the interior of the shaft element after a short distance of 2 to 3 dm. The amount of air can thus be regulated without any harmful effect on the treatment of the cubes. Besides, no special guide plates are required with this arrangement on the suction side.

In another advantageous embodiment, the air throttles of each shaft element have independent operating means controlled by the feed cubes. During the filling and during the emptying, each shaft element and each zone respectively can be connected and disconnected separately. There is no air circulation in the empty shaft part. The exact amount of air that participates effectively in the cooling process is put through so that the amount of air is regulated as a function of the amount of cubes in the proper sense.

In another advantageous embodiment, a finger flap lock is arranged between the air exhaust line and the cube discharge element. This permits to return very fine dust particles into the cube discharge element which have been pulled away from the shaft and is precipitated in the air exhaust line. As known, feed cubes have many abrasive constituents, such as minerals. If a large amount of abrasive dust is sucked off with the aspiration, primarily deflection points and bends of the air pipe are worn through in a very short time. The parts must be repaired after a short time or be replaced. Since the dust particles only require a fraction of the time for the treatment, compared to the cubes, there are no objections to a direct return into the finished cubes from a sanitary point of view.

In a very advantageous embodiment, the cross sectional area of the separator-type transition piece is partly closed relative to the shaft element, but it has an extension protruding downwardly into the interior of the shaft with a down pointing bevel surface. By deflecting and reducing the air velocity, it is thus possible to achieve in a very effective manner a precipitation of entrained cubes or coarse dust particles in the air delivery roof. The cubes slide constantly back into the shaft at the same level. This measure permits very high air velocities through the air delivery roofs. Due to a special design of the transition piece in the form of a separator, the cubes remain in the most desirable zone according to their condition. The uniformity of the cooling and feeding process is maintained this way. Very fine particles which are carried along can be returned into the charge with an air exhaust line extended up to the discharge element.

In another embodiment, the air permeable supporting and guiding surfaces of the air control roofs can be formed by plates formed of a single part. The portion of the ineffective surfaces can thus be greatly reduced. The free passage area for the air is maximally increased. The cooling and drying process are improved. Even at these smallest areas, the freshly pressed and sticky feed cubes cannot form a harmful cushion."

In another advantageous embodiment, the cube discharge element has a known regulating flap which can be used with particular advantage in a screening device combined with the cube discharge element.

In another embodiment, the shaft cooler has means which permit a periodic change of the air throughout. The cooling process can thus be greatly intensified. These means can be assigned with great advantage to individual shaft elements, particularly to the cube discharge element, where a separation can be effected together with a corresponding height of charge.

Accordingly, it is an object of the invention to provide an improved shaft cooler for feed cubes which comprises a plurality of vertically stacked tubular shaft elements each having a plurality of transversely spaced parallel air delivery roofs at a first upper level and a plurality of transversely spaced air feed control roofs at a second lower level and which includes an exhaust conduit arranged alongside the shaft which is connected laterally to the air delivery roofs and which includes a separator in the connection therebetween, the air feed control roofs being air permeable and having openings at their bottoms.

A further object of the invention, is to provide a shaft cooler which is simple in design, rugged in construction and economical to manufacture.

For an understanding of the principles of the invention, reference is made to the following description of typical embodiments thereof as illustrated in the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS In the Drawings:

FIG. 1. is a vertical sectional view of a shaft cooler constructed in accordance with the invention;

FIG. 2 is a side elevational view of the shaft cooler shown in FIG. 1;

FIG. 3 is a top plan view of the shaft cooler;

FIG. 4 is an elevational view partily in section of a pendulum suspension for the discharge apparatus shown in the cooler of FIG. 1;

FIG. 5 is an enlarged transverse sectional view of a single element of the shaft cooler shown in FIG. 1;

FIG. 6 is a section taken along the line VIVI of FIG. 5; 9

FIG. 7 is an enlarged partial sectional view of the air throttle operating mechanism for the flaps shown in FIGS. 5 and 6;

FIG. 8 is a section taken along the line VIIIVII-'I of FIG. 7;

FIG. 9 is a transverse sectional view of the discharge element at the lower portion of the shaft cooler shown in FIG. 1;

FIG. 10 is a view similar to FIG. 9 showing a screen with the unit;

FIG. 11 is top plan view of a single baffle roof element for the air delivery roofs and air feed control roofs shown in FIG. 1; and

FIG. 12 is a transverse section taken along the line XII-XII of FIG. 11.

GENERAL DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring to the drawings in particular the invention embodied therein comprises a shaft cooler which is made up of a plurality of individual shaft elements 1 which are stacked vertically and which also includes an upper shaft part or entrance part 2 and a lower shaft part or cube discharge element 3. The upper shaft part 2 has an inlet 4 for the feed cubes and it is closed by

side walls

5,5 and end

walls

5,5. The

end walls

5,5 have openings 6. A level gauge flap 7, as shown in FIG. 1, is connected to a limit switch 9 by control means (not shown) which in turn are connected to vibration generators 10 which are part of the tube discharge element 3.

A single one of the shaft elements 1 are indicated in FIGS. 5 and 6 on an enlarged scale. Each element 1 includes a central air feed roof 1] which is in communication with the surrounding air through openings 12 in the

side walls

14 and 15. In addition there are two half through openings 16 and 16' of end walls 14' and '.v

In accordance with the invention, two

air delivery roofs

17 and 18 are arranged in spaced parallel relationships above the air

feed control roofs

11, 13 and 13 and they are arranged in a symmetrical arrangement therewith. The side wall 14 is closed from the

air delivery roofs

17 and 18 but the opposite side wall 15 has openings 19 and 19' which are connected through a transition piece or separator passage 20 to a downwardly opening connecting flange 20' of an air throttle 21. As shown in FIGS. 3 and 6, the transition piece 20 is a tubular part that includes a large cross-sectional lower end connected to the openings 19 and 19' for

roofs

17 and 18 and a smaller cross-sectioned upper end connected to the inlet of air throttle 21. Because of the rapid change in cross-sectional area from an enlarged inlet section to a small diameter section at the outlet to the exhaust line 22, the air velocity is changed and large particles are separated from the air flow and slide back into the tower. The connection also continues into a vertical air exhaust line 22 which is arranged alongside the drop shaft. All of the

delivery roofs

17 and 18 are formed by an upper angle 25 and by two lower angles 26 and air permeable plates 27 which are inserted therebetween similar to roof tiles. Between the air exhaust line 22 and the cube discharge element 3 is arranged a flap lock 28. (See FIG. 2)

The air throttle 21 which is shown in detail in FIGS. 5 to 8 is controlled by a flap 30 which is held in a rest position by a counterweight 32 which is carried on a shaft 31. The rest position corresponds to the closed position of the air throttle 21. A lever 33 is also carried on the shaft 31 and it is displaceably mounted on the opposite side thereof with a sliding bush 34 on the operating rod 35. The operating rod 35 has locking discs 36 on each side of the sliding bush 34 which determin the end position of the air throttle 21.

The cube discharge element 3 is screwed by four suspended pendulums 40 on a base 39 of a square support 41 with flanges 42. Around the supports 41 are arranged four rubber blocks 43 each, which are held with a bush 44 and connected to the suspended pendulum 40. On the cube discharge element 3 is secured a similar support 41' over flanges 42'. The support 41' is in turn mounted by rubber blocks 43' with a bush 44 on the suspended pendulum 40. Due to these suspended pendulums, known under the trade name ROSTA, the cube discharge element can perform a damped vibration movement particularly in a preferential direction (A). Though small movements in transverse direction thereto are possible, the transverse connections are more damped. The cube discharge element is shown in FIG. 9 on a larger scale. For reasons of transportation the cube withdrawal element 3 is connected directly to the base 39. The cube discharge element has two flatly inclined bottoms 30 with lateral shoulders 51. Above each bottom is arranged a roof 52 which prevents direct issuance of the feed cubes into the bottom 50.

The method of operation of the shaft cooler;according to the invention is as follows with reference to FIG. 1 to 6:

The freshly pressed feed cubes, with excess water content, are filled hot through the.inlet 4. The cubes ripple downward over the cascade-type

air control roofs

17, 18 as well as 11, I3 and 13. The first cubes arrive at the discharge apparatus 3 and form a natural angle of repose relative to the

air feed roofs

11, 13, 1.3 of the bottom shaft element.

During the filling of the firstcubes, care must be taken at the same time for a sufficient air throughput, otherwise the cubes would stick particularly to the air control roofs, which represent obstacles for the cubes.

While the cooling and the removal of excess water are effected progressively, the discharge apparatus remains disconnected.

If the level of the feed cubes exceeds the level gauge flaps 7, these are pressed down by the weight of the cubes against the restoring force of counterweights 8.

The rotary movement of the level gauge flaps 7 is at the same time transmitted to the limit switch 9. The limit switch 9 starts the vibration generator in the end position so that the shaking movement causes the discharge of the finished cubes. The level gauge flaps 7 ensure that the shaft cooler does not run idle unnecessarily. The uniformity is thus ensured during the entire operating period.

In an industrial type laboratory test uniform air distribution was determined by means of an aneometer. Particularly, the discharged cubes had in all four corners, a surprisingly uniform temperature, which proves the good cooperation of the combination according to the invention. Though the air velocity was selected so high that small cubes could be carried along on the surface, only fine dust particles were found in the exhaust line.

Particularly advantageous, is the arrangement of an air throttle 21 between air exhaust line 22 and the

air delivery roofs

17, 18.

Particularly if the air ducts are opened or closed, according to another embodiment of the invention, by the flap 30 as a function of the cube level, an optimum economical operation of the cooler can be achieved. The flap 30 arranged in the shaft element 1 is connected with the air throttle 21 over actuating means: shaft 31, lever 33 and operating rods 35.

In another embodiment of the invention, locking discs 36 are arranged on the operating rod 35 on both sides of a sliding bush 34 of the lever 33.

These locking discs 36 permit the fixing of the extreme values of the air throttle 21, and they can thus prevent complete closing of the air throttle 21 or complete opening of the latter. The counterweight 32 can in addition be displaced relative to the shaft 31. In this way, the air throttle 21 can be used as an air regulating device proper. Depending on the position of the counterweight 32, even the degree of opening of the air throttle can be influenced in dependence on the amount of cubes above the flap and the corresponding shaft element respectively.

Depending on the properties of the feed cubes, it may be of advantage to put through different amounts of air in the superposed shaft elements and zones, since it is desirable, for example, to have a slow initial cooling and maximum cooling at the end.

The air-throttle, particularly in combination with a level-gauge-dependent regulating device, permits optimum use for largest and smallest cubes, due to the arrangement of shaft elements and zones.

In a further development of the idea of the invention, the upper shaft part 2 has openings6 which permit a 81 particularlly gentle precooling zone. In this way, the cooling process and the delivery of the excess water is very uniform over the entire cube cross section. The frequently dreaded shock cooling does not appear.

Experience has shown again and again that there is a certain optimum dimension of the cube layer thickness in the treatment of feed cubes in shaft coolers, which is about 250 to 300 mm. If the layer thickness (c) is increased substantially beyond this amount, the quality of the cubes deteriorates.

It was found that there is an optimum ratio between the layer thickness of the cubes in the cooler and the horizontal longitudinal dimension (B) of this layer, for the following reasons:

1. A maximum utilization of the volume of the cooler should be achieved. This results in a few small air control roofs and large dimensions of the shaft element base;

2. The air velocity should be selected as high as possible in order to achieve a more intensive treatment. This results in a great number of air control roofs;

3. The air distribution should be uniform. This results in a short longitudinal dimension (B) of the cube layer; and

4. The lowering of the material in the shaft should be uniform, without expensive auxililary devices and this results in small dimensions of the shaft element base.

From these contradictory requirements has resulted an optimum ratio of layer thickness (c) to layer length (B) of about 1:4 to 1:5. The horizontal dimension (B) of the layer should not be substantially below 1.0 m to be economical, but must not exceed 1.5 m to prevent quality deterioration. A length of 1.2 m was found to be optimal.

As far as the lowering of material and the utilization of the space are concerned, a very advantageous solu-.

tion was found with the arrangement of two pairs of horizontal

air feed roofs

11, 13, and 13' as well as of

air delivery roofs

17, 18, which together with the optimum length of 1.2 m, represents today the most advantageous design.

As known, the lowering is determined not only by the form of the shaft element and of the air control roofs, but also, at least in extreme cases, by the discharge element 3.

Particularly in cascade coolers, vibrating discharge elements have been used with very good results.

The method of operation, particularly the uniform lowering of the shaft cooler according to the invention, can be further improved in a particularly advantageous manner in that the main vibration direction of the cube discharge element 3 points transversely to the air control roofs (l1,l3,17,18) in the direction of the longer shaft element dimension (A).

According to another feature of the invention, a vertical wall 23 (FIG. 5) can be arranged between the

air feed roofs

11 and 13 as well as 11' and 13' of the shaft elements. Together with the preferred vibration direction over the longer shaft dimension, an absolutely uniform lowering of the cubes could be observed, particularly in the bottom shaft element 3, which is also a prerequisite for a uniform quality of the end product.

Another safety measure is achieved by making the cube dosing flaps 53 adjustable by a wheel 54 arranged along the narrow sides of the discharge element as shown in FlGS. 9 and 10. The cube dosing flaps 53 together with a roof 52 form a dosing gap. The cubes are delivered over the two narrow sides (B) into the bottom 50.

Of great advantage is the arrangement of two symmetrically opposed vibration generators 10 arranged along the shorter dimension of the cube discharge element 3, which influence each other, as known, in such a way that wobbling movements are impossible and only horizontal vibrations transverse to the connecting pipe 55 are generated in the direction of the length side (A).

Very advantageous is the arrangement of a screen 56 between the roof 52 and the bottom 50.

The cube dosing flap 53 is lifted by rotating the hand wheel 54. Between the roof 52 and the cube dosing flap 53 is formed a dosing gap 49. The roof 52 is connected with the vibrating bottom 50 and receives the same vibration from the vibration generator 10. The discharge of the cubes is thus ensured, despite the non-vibrating cube dosing flap 53. It is of particular advantage that the cubes are discharged over the narrow side B to the screen 56. All cubes take thus the longest possible way to the outlet 58. Fine particles can be discharged through a separate duct 57. Without great energy expenditure, the finished cubes can be reliably liberated of the undesired dust portion by the customer with this solution. The screening itself is qualitatively very good, since it is carried out over the longer path.

The means for periodically changing the air throughout can be assigned either to a single shaft element or to all shaft elements jointly and thus to the air exhaust line 22. If the means are assigned to a single shaft element, they are preferably installed in the range of the transition piece 20. To this end a flap with a centrally arranged shaft in the transition piece can be set in rotation. This flap can be driven with a low-speed geared motor, which is arranged preferably on the outside of the transition piece 20. During each revolution of the flap, the air passage is opened and closed twice. This results in great fluctuations of the amount of air or of the air velocities through the cube layer to be cooled. These air pulsations can intensify and increase the cooling process. The same rotating flap can be provided at the upper end in the air exhaust line 22. From a strictly operational point of view, it would even be possible to arrange the air generator itself (not shown) or a fan in the pump range that is, in the normally undesired range in which the air fluctuates periodically between 0 and any value. Such a solution, however, would require large dimensions of the fan wheel.

While specific embodiments of the invention have been shown and described in detail to illustrate the application of the principles of the invention, it will be understood that the invention may be embodied otherwise without departing from such principles.

What is claimed is:

l. A cooling tower for feed cubescomprising a plurality of vertically stacked tubular shaft elements each having a plurality of transversely parallel air delivery roofs at a first upper level and a plurality of transversely spaced air feed roofs at a second lower level, saidair feed roofs being air permeable and open at the bottom side thereof, said air delivery roofs and said air feed roofs all comprising roof-like structures with downwardly diverging top roof walls, an exhaust conduit arranged alongside said shaft cooler and connected laterally to said air delivery roofs, and a transition piece forming a separator in the connection between said exhaust conduit and said air delivery roofs.

2. A cooling tower, according to claim 1, including an air throttle connected between said exhaust conduit and said air delivery roofs.

3. A cooling tower, according to claim 2, wherein said air throttle comprises a throttle valve and a connection between said air delivery roofs and said exhaust conduit, a flap located at the entrance to said tubular shaft elements defiectable by the material entering said elements and connected to said throttle to actuate said throttle in accordance with the engagement thereof by said feed cubes.

4. A cooling tower, according to claim 3, including an operating rod arranged between said air throttle and said flap having locking discs for fixing the extreme position of said air throttle.

5. A cooling tower, according to claim 1, including a discharge for the feed cubes arranged below said tubular shaft elements and a flap lock arranged between saidair exhaust conduit and the lowermost one of said tubular shaft elements and said discharge element.

6. A cooling tower, according to claim 1, wherein said air delivery roofs and said air feed roofs are formed of several loosely inserted air permeable plates.

7. A cooling tower, according to claim 1, wherein said .air feed roofs comprise at least a pair of delivery roofs overlying a respective side of at least one air feed roof.

8. A cooling tower, according to claim 7, wherein there is at least a partial air feed roof arranged below the exterior side of each air delivery roof.

'9. A cooling tower, according to claim 8, wherein said air delivery roofs and said air feed roofs have a length of from 1.0 to L5 m, preferably 1.2 m.

10. A cooling tower, according to claim 9, including a discharge element disposed below all of said tubular shaft elements, said discharge element having a vibration generator connected to a vibration member overwhich the cubes are fed when they are discharged, said member being arranged to discharge the feed cubes transverse to the air feed roofs.

11. A cooling tower, according to claim 9, including a vertical wall 23 arranged between air feed roofs of each individual shaft element.

12. A cooling tower, according to claim 1, including .a discharge part below said tubular shaft elements having an inclined wall adjacent the top thereof, a dosing flap overlying said inclined wall extending transversely of said shaft element, said dosing flaps forming together with said inclined wall a dosing gap between which the feed cubes are passed, and hand wheel adjusting means connected to said flap for adjusting the gap.

13. A cooling tower, according to claim 9, wherein each tubular shaft element includes a downwardly extending bottom wall extending downwardly from each side and underlying said inclined wall the gap formed between said inclined wall and said flap discharging overarespective bottom wall and including a screen overlying said bottom wall.

14. A cooling tower, according to claim 13, including a connecting pipe extending transversely of said discharge element and two vibration generators connected to said connecting pipe at spaced locations.

said vibration generators to discharge the cubes through the lower end of said drop shaft.

18. A cooling tower, according to claim 1, wherein the connection between said exhaust conduit and said air feed roofs include a transition piece having a flow area reduction, said shaft element being partly closed but having an extension extending into said transition piece which opens at its narrow end into said exhaust

Claims

1. A cooling tower for feed cubes comprising a plurality of vertically stacked tubular shaft elements each having a plurality of transversely parallel air dElivery roofs at a first upper level and a plurality of transversely spaced air feed roofs at a second lower level, said air feed roofs being air permeable and open at the bottom side thereof, said air delivery roofs and said air feed roofs all comprising roof-like structures with downwardly diverging top roof walls, an exhaust conduit arranged alongside said shaft cooler and connected laterally to said air delivery roofs, and a transition piece forming a separator in the connection between said exhaust conduit and said air delivery roofs.

3. A cooling tower, according to claim 2, wherein said air throttle comprises a throttle valve and a connection between said air delivery roofs and said exhaust conduit, a flap located at the entrance to said tubular shaft elements deflectable by the material entering said elements and connected to said throttle to actuate said throttle in accordance with the engagement thereof by said feed cubes.

5. A cooling tower, according to claim 1, including a discharge for the feed cubes arranged below said tubular shaft elements and a flap lock arranged between said air exhaust conduit and the lowermost one of said tubular shaft elements and said discharge element.

7. A cooling tower, according to claim 1, wherein said air feed roofs comprise at least a pair of delivery roofs overlying a respective side of at least one air feed roof.

9. A cooling tower, according to claim 8, wherein said air delivery roofs and said air feed roofs have a length of from 1.0 to 1.5 m, preferably 1.2 m.

12. A cooling tower, according to claim 1, including a discharge part below said tubular shaft elements having an inclined wall adjacent the top thereof, a dosing flap overlying said inclined wall extending transversely of said shaft element, said dosing flaps forming together with said inclined wall a dosing gap between which the feed cubes are passed, and hand wheel adjusting means connected to said flap for adjusting the gap.

13. A cooling tower, according to claim 9, wherein each tubular shaft element includes a downwardly extending bottom wall extending downwardly from each side and underlying said inclined wall the gap formed between said inclined wall and said flap discharging over a respective bottom wall and including a screen overlying said bottom wall.

15. A cooling tower, according to claim 1, including means for periodically changing the air throughout said cooler.

16. A cooling tower, according to claim 1, including means for periodically changing the air throughput and each of said tubular shaft elements.

17. A cooling tower, according to claim 1, including a top shafT portion enclosing all of said tubular shaft elements having an inlet port and a flap level control contained in said top shaft portion responsive to the amount of feed cubes directed into said inlet to operate said vibration generators to discharge the cubes through the lower end of said drop shaft.

18. A cooling tower, according to claim 1, wherein the connection between said exhaust conduit and said air feed roofs include a transition piece having a flow area reduction, said shaft element being partly closed but having an extension extending into said transition piece which opens at its narrow end into said exhaust conduit.