Device and Method for Drying or Heating and Cooling Bulk Material

Abstract

The device for drying or heating and cooling bulk material in accordance with the invention consists of a rotatable drum comprising means for receiving the bulk material in a first region and means for discharging the bulk material from a second region, wherein a central region is arranged between the first and second regions, said central region consisting of an annular structure with a first and a second diaphragm with central diaphragm apertures each, which form substantially two diaphragm planes parallel to each other, and comprise a plurality of transport channels closed toward the central region for transporting the bulk material from the first region to the second region of the rotatable drum through the central region, wherein the transport channels extend from the first to the second diaphragms at a non-90 angle relative to the two diaphragm planes.

Claims

1. A device for drying and/or heating and cooling bulk material, comprising: a rotatable drum with means receiving the bulk material in a first region and means for discharging the bulk material from a second region, wherein a central region is arranged between the first region and the second region, said central region consisting of an annular structure with a first diaphragm and a second diaphragm with central diaphragm apertures each, which form substantially two diaphragm planes parallel to each other, and comprise a plurality of transport channels closed toward the central region for transporting the bulk material from the first region to the second region of the rotatable drum, the transport channels extend from the first diaphragm to the second diaphragm at a non-90 angle relative to the two diaphragm planes, and the central region is divided by a separating wall parallel to the diaphragm planes for the separate guiding of the drying air and the cooling air and merely the transport channels are exempt from the separating wall.

2. The device according to claim 1, wherein the transport channels are distributed evenly over the annular structure.

3. The device according to claim 1, wherein through flow apertures for the gaseous media are provided in the central region in the rotatable drum next to the respective transport channels.

4. The device of claim 1, wherein the first region of the drum is configured for drying or heating or reaction procedure and the second region of the drum is configured for cooling or further reaction procedure of the bulk material.

5. The device of claim 1, wherein the first region and the second region of the drum are each provided with conveyor means for causing a transport of the bulk material into the transport channels and, after the exit thereof from the transport channels, a transport of the bulk material in the second region until a discharge of the bulk material.

6. The device of claim 1, further comprising a housing enclosing the central region for discharging or supplying the gaseous media.

7. The device according to claim 6, wherein the housing further comprises an exhaust duct at a top portion of the housing and a fine material at a portion of the housing.

8. The device of claim 1, wherein the entire device is inclined relative to horizontal in a direction of transport of the bulk material.

9. The device according to claim 8, wherein an angle of inclination ranges between 0.5 and 7.

10. A method for drying and/or heating and cooling bulk material, comprising the steps of: introducing a cold and/or moist bulk material in a drying region; rotating the drying region; introducing hot gases in the drying region; drying and transporting the bulk material within the drying region to a central region; transporting the dried, hot bulk material in transport channels closed toward the central region through the central region with apertures for the supplying and/or or discharging of gas; entering and/or existing of the hot gas through the through flow apertures in the central region and via the housing and the connected exhaust duct, wherein the central region is divided by a separating wall parallel to the diaphragm planes for the separate guiding of the drying air and the cooling air and merely the transport channels are exempt from the separating wall; transporting the dry, hot bulk material to the cooling region; introducing cooling air and cooling the dry, hot bulk material in a coflow or counterflow procedure; exhausting the heated cooling air; and discharging the dry, cooled bulk material.

11. The method according to claim 10, further comprising the step of: separating fine material in the central region, preferably by dropping caused by gravity.

12. The method of claim 10, further comprising the step of: returning the exiting, heated cooling air flow to the drying region as preheated drying air for drying the cold and at least moist bulk material, and associated heat recovery and/or waste heat utilization from the cooler exhaust air.

13. The method of claim 10, further comprising the step of: for drying and/or heating and cooling the bulk material, using a device comprising: a rotatable drum with means for receiving the bulk material in a first region and means for discharging the bulk material from a second region, wherein a central region is arranged between the first region and the second region, said central region consisting of an annular structure with a first diaphragm and a second diaphragm with central diaphragm apertures each, which form substantially two diaphragm planes parallel to each other, and comprise a plurality of transport channels closed toward the central region for transporting the bulk material from the first region to the second region of the rotatable drum, the transport channels extend from the first diaphragm to the second diaphragm at a non-90 angle relative to the two diaphragm planes, and the central region is divided by a separating wall parallel to the diaphragm planes for the separate guiding of the drying air and the poling air and merely the transport channels are exempt from the separating wall.

14. The method according to claim 10, wherein the drying or heating or reaction procedure in the first region takes place in the counterflow between gas and bulk material instead of in the coflow.

15. The method according to claim 10, wherein the cooling or reaction procedure in the second region takes place in the coflow between gas and bulk material instead of in the counterflow.

16. The method of claim 11, wherein the separating of fine material is by dropping caused by gravity.

17. The device according to claim 8, wherein an angle of inclination ranges between 1 and 3.

Description

[0079] Two preferred embodiments of the present invention are illustrated in the Figures. There show:

[0080] FIG. 1 a schematic section through a device in accordance with the invention with a one-piece central region;

[0081] FIG. 2 a schematic section through a device in accordance with the invention with a two-piece central region;

[0082] FIG. 3 a schematic perspective illustration of the central region according to FIG. 1;

[0083] FIG. 4 a schematic side view of a central region in accordance with the invention;

[0084] FIG. 5 a schematic front view of a central region in accordance with the invention pursuant to FIG. 4.

[0085] FIG. 1 illustrates an embodiment of the device in accordance with the invention with an entry housing 1 at the left side. In its vicinity a device for the solid matter entry 2 is arranged through which the bulk material to be dried and to be cooled is introduced into the device in accordance with the invention. Likewise at the left 25 front side of the device in accordance with the invention a burner 3 is positioned which has the function of a conventional heating burner and sees to it that sufficient hot air is introduced into the device in accordance with the invention. As the case may be, the burner 3 comprises a combustion chamber for achieving a regular air entry temperature and for preventing the flame of the burner from burning overtly in the dryer. Pursuant to FIG. 1 the entry housing 1 is installed to be stationary and the drum of the device in accordance with the invention is mounted with the race 11 to rotate on the guide rollers 12. As a drive mechanism, a direct motor, a pinion with a gear, a sprocket or a chain drive may, for instance, be used. These technical solutions are known from the state of the art and have substantially the same effect and are exchangeable. They are not illustrated in FIG. 1 and FIG. 2.

[0086] When a particular amount of the bulk material is introduced in the entry housing 2, this amount has a particular temperature with a particular degree of moisture A.sub.0. This amount passes in the drying zone 6 through different drying states from A.sub.1 to A.sub.n, wherein A.sub.1 designates a rather moist state and A.sub.n a state which is almost dry, but heated. Likewise, the temperature T.sub.1 in the drying zone 6 changes from T.sub.1 which designates a rather high temperature to T.sub.n which designates a lower temperature.

[0087] The transport of the bulk material within the drying zone 6 of the drum may be performed by different technical measures. On the one hand, it is possible to carry out the transport within the drying zone 6 of the drum by conveying means available at the drum wall, for instance, in the form of guide vanes (not illustrated). Such conveying means have been known for a long time. It is likewise possible to incline the drum and to enable conveyance due to the angle of inclination. Basically, however, the use of guide vanes is to prefer since the mixing of the bulk material to be dried is of advantage and promotes drying.

[0088] As soon as the bulk material pursuant to FIG. 1 has reached the right edge of the drying zone 6, it will leave the region A and will enter the central region B in accordance with the invention. The central region B is confined on both sides by a diaphragm 8A, 8B. The central region B is passed by tunnel-like transport channels 9 through which the bulk material to be dried is conveyed from the drying zone 6 to the cooling zone 7. A preferred design of the central region B will be described in detail in FIGS. 3 to 5.

[0089] After leaving the drying zone 6 and/or the region A and the central region B, the bulk material should be substantially dry. As already shown schematically in FIG. 1, the drying zone 6 may be designed to be substantially longer than the cooling zone 7. In the cooling zone 7 and/or the region C the bulk material is cooled to a predetermined temperature and may leave the device in accordance with the invention as a dried, cooled material.

[0090] Pursuant to FIG. 1 drying takes place in coflow, i.e. the drying gas flow with the temperature T.sub.1 to T.sub.n proceeds in the same direction as the material flow A.sub.1 to A.sub.n. In the cooling zone 7 cooling takes place in counterflow, though, i.e. the material flow C.sub.1 to C.sub.n takes place contrary to the direction of flow of the cooling air (KA) K.sub.1 to K.sub.n. This favors cooling. In accordance with the invention, both the heated cooler exhaust air K.sub.n and the moist dryer exhaust air T.sub.n exit through the central region as exhaust air EA. For this purpose the central region B comprises, between the two diaphragms 8A and 8B, two central diaphragm apertures 13A and 13B (see FIG. 4) which enable the dryer exhaust air T.sub.n and the cooler exhaust air K.sub.n to first of all flow through these central diaphragm apertures 13A and 13B so as to subsequently leave the device in accordance with the invention through the through flow apertures 14A to 14F (see FIG. 5).

[0091] Dusts and particles carried along with the drying or cooling air into the central region are either carried along with the exhaust air EA and may be separated from the air in subsequent separators (exhaust filter or cyclones not illustrated), or they fall as fine material FM in the central region downward and through the respective bottom through flow apertures 14 into the housing 4. The dried and cooled solid matter SM is output as an end product at the right side of the device in accordance with the invention pursuant to FIG. 1.

[0092] FIG. 2 illustrates the same device in accordance with the invention as FIG. 1 apart from the difference that the central region B is of two-piece design, i.e. the drying zone 6 is separated from the cooling zone 7 by a separating wall 10. Due to the spatial separation of the two regions it is also necessary that the exhaust air discharge and the fine material discharge also take place separately and thus also two separating regions are available in the housing 4. The dryer exhaust air is, pursuant to FIG. 2, designated with DEA and the cooler exhaust air with CEA. The two fine material discharges are designated with FM1 and FM2. The dried and cooled solid matter SM is output as an end product at the right side of the device according to the invention pursuant to FIG. 2.

[0093] FIG. 3 illustrates a schematic representation of a central region B in accordance with the invention with a plurality of baffles 15A to 15F. The function of the baffles 15A to 15F consists in favoring and supporting the introduction of the bulk material from the drying zone 6 and/or A to the central region B. The baffles are preferably slightly inclined so as to enable trickling in into the tunnel-like channels 9A to 9F.

[0094] FIG. 4 and FIG. 5 illustrate a preferred embodiment of the central region B, but without baffles. FIG. 4 illustrates a schematic side view, wherein, however, the drum wall which covers the transport channels 9D, 9E and 9F is not shown. Pursuant to FIG. 5 six tunnel-like transport channels 9A to 9F and six through flow apertures 14A to 14F are provided. The tunnel-like transport channels 9A to 9F extend from the one diaphragm 8A to the other diaphragm 8B, but the tunnel-like transport channels 9A to 9F proceed under a non-90 angle , preferably between 2 and 30. Due to the non-90 angle the technical effect is achieved that on clockwise rotation of the central region B the bulk material is conveyed into the tunnel-like transport channels 9A to 9F in the direction of the arrow AC and is there, comparable to a conveyor wheel, received in the drying zone 6 in the position 9D to 9F and is again discharged in the position 9A and 9B, but in the region of the cooling zone 7.

LIST OF REFERENCE NUMBERS

[0095] 1 entry housing [0096] 2 solid matter entry [0097] 3 burner [0098] 4 suction housing [0099] 5 exit housing [0100] 6 drying zone [0101] 7 cooling zone [0102] 8 diaphragm [0103] 9 tunnel-like transport channels [0104] 10 separating wall [0105] 11 race [0106] 12 guide rollers [0107] 13 diaphragm apertures [0108] 14 through flow apertures [0109] 15 baffles