Method for cooling solid residues of a combustion process

Abstract

A method for cooling solid residues of a combustion process, which are deposited onto the conveying surface of a conveyor belt of a conveying device and are conveyed in the direction of a solid residue outlet, wherein during conveying heat is transferred from the solid residues to a gaseous coolant. The method is characterized in that the conveyor belt is acted upon by coolant only on its side oriented away from the conveying surface, the conveyor belt is essentially impermeable to the coolant and at least part of the coolant heated by contact with the conveyor belt is extracted on that side oriented away from the conveying surface.

Claims

1. A conveying device, comprising: a conveyor belt with a conveying surface for conveying solid residues; and means for cooling the solid residues comprising a coolant supply for introducing a gaseous coolant and a coolant evacuation for extracting at least part of the coolant heated by the solid residues, wherein: the conveyor belt is essentially impermeable to the coolant, the conveyor belt is an endless conveyor belt that is guided around at least two rollers and forms a loop with a conveying strand and a return strand, the loop together with laterally arranged side walls enclosing a space to which are assigned the coolant supply and the coolant evacuation, the space between the conveying strand and the return strand is divided with a wall running essentially parallel to a plane of the conveying strand so as to form an interspace between the conveying strand and the wall, the coolant supply and the coolant evacuation being arranged in the interspace or being connected to the interspace, and the coolant supply and the coolant evacuation are configured such that the coolant is in contact only with a side of the conveyor belt oriented away from the conveying surface.

2. The conveying device as claimed in claim 1, wherein: the coolant supply comprises coolant supply pipes that are connected, via a side wall, to the space below the conveying strand and via which the coolant can be introduced on the side of the conveyor belt oriented away from the conveying surface, and the coolant evacuation comprises coolant evacuation pipes that are connected via a side wall to the space below the conveying strand and by means of which at least part of the coolant heated by contact with the conveyor belt is extracted.

3. The conveying device as claimed in claim 2, wherein coolant supply nozzle pipes connected to the coolant supply pipes have nozzle pipe openings in their uppermost region.

4. The conveying device as claimed in claim 1, wherein the space between the conveying strand and the return strand is divided into at least two compartments in the conveying direction, in each case at least one valve for controlling quantity of the coolant to be introduced being (i) assigned to the coolant supply and/or evacuation assigned to the different compartments or (ii) connected to the different compartments.

5. The conveying device as claimed in claim 1, wherein the coolant supply comprises gas nozzles whose openings are arranged at least in part at a distance of less than 30 cm.

6. A waste combustion plant comprising a conveying device, the conveying device comprising: a conveyor belt with a conveying surface for conveying solid residues; and means for cooling the solid residues comprising a coolant supply for introducing a gaseous coolant and a coolant evacuation for extracting at least part of the coolant heated by the solid residues, wherein: the conveyor belt is essentially impermeable to the coolant, the conveyor belt is an endless conveyor belt that is guided around at least two rollers and forms a loop with a conveying strand and a return strand, the loop together with laterally arranged side walls enclosing a space to which are assigned the coolant supply and the coolant evacuation, the space between the conveying strand and the return strand is divided with a wall running essentially parallel to a plane of the conveying strand so as to form an interspace between the conveying strand and the wall, the coolant supply and the coolant evacuation being arranged in the interspace or being connected to the interspace, and the coolant supply and the coolant evacuation are configured such that the coolant is in contact only with a side of the conveyor belt oriented away from the conveying surface.

7. A method for cooling solid residues of a combustion process, the method comprising: depositing the solid residues onto a conveying surface of a conveyor belt of a conveying device; and conveying the solid residues in the direction of a solid residue outlet, wherein: during the conveying heat is transferred from the solid residues to a gaseous coolant introduced by way of a coolant supply, the conveyor belt is acted upon by the coolant only on its side oriented away from the conveying surface, the conveyor belt is essentially impermeable to the coolant, the conveyor belt is an endless conveyor belt that is guided around at least two rollers and forms a loop with a conveying strand and a return strand, the loop together with laterally arranged side walls enclosing a space to which are assigned the coolant supply and a coolant evacuation, the space between the conveying strand and the return strand is divided with a wall running essentially parallel to a plane of the conveying strand so as to form an interspace between the conveying strand and the wall, the coolant supply and the coolant evacuation being arranged in the interspace or being connected to the interspace, and at least part of the coolant heated by contact with the conveyor belt is extracted on the side oriented away from the conveying surface by way of the coolant evacuation.

8. The method as claimed in claim 7, wherein the temperature of the solid residues deposited onto the conveying surface is in a range from 200 C. to 500 C.

9. The method as claimed in claim 7, wherein the solid residues are cooled, while being conveyed to the solid residue outlet, to below 150 C.

10. The method as claimed in claim 7, wherein the heated coolant is used as a heating medium after extraction.

11. The method as claimed in claim 7, wherein the coolant is air.

12. The method as claimed in claim 7, wherein, for cooling the solid residues, the coolant is simply circulated in a space that is separate from the space in which the solid residues are arranged.

13. The method as claimed in claim 7, wherein the conveyor belt is acted upon by the coolant via gas nozzle openings that are arranged, at least in part, at a distance of less than 30 cm.

Description

(1) The invention is further clarified with reference to the appended figures, in which:

(2) FIG. 1 shows a furnace of a waste combustion plant comprising a combustion chamber, a waste supply, a combustion grate, a coarse clinker discard chute and a conveying device for carrying out the method according to the invention;

(3) FIG. 2 shows a section drawing of a conveying device according to the invention, in perspective view;

(4) FIG. 3 shows a detail view of part of a conveying device according to the invention, without the housing, for injecting and simultaneously evacuating coolant under the conveying surface; and

(5) FIG. 4 shows a detail view of part of a conveying device according to the invention, corresponding to FIG. 3, with the housing.

(6) As shown in FIG. 1, the waste combustion plant comprises a combustion chamber 2, upstream of which is mounted a waste supply 4 with an adjoining waste chute 6. The combustion chamber 2 comprises a combustion grate 10 which, in the embodiment shown, is divided into four grate sections (not shown) and is supplied with primary air via a primary air supply 11. Specifically, a funnel-shaped under-grate air chamber 14a, 14b, 14c, 14d is arranged underneath each of the grate sections, each of which chambers has opening into it a primary air supply line 16 and is designed to supply primary air via corresponding primary air ducts, through the combustion grate 10, to the combustion bed.

(7) The fine clinker components which, due to the construction of the grate, always fall through are discarded via the funnel necks 12a to 12d of the respective under-grate air chambers 14a to 14d onto a conveying device 1 which conveys them in the conveying direction F to a solid body outlet 17. The remaining clinker, which comprises larger clinker pieces, arrives at a coarse clinker discard chute 15.

(8) As shown in FIG. 2, the conveying device comprises a conveyor belt 38 which, in the embodiment shown, is in the form of an endless conveyor belt which is guided on support rollers 33 and forms a conveying strand 30on the conveying surface 37 of which the solid residues 32, that specifically are present in the form of clinker 321, are received and are conveyed in the conveying direction Fand a return strand 31.

(9) According to the embodiment shown in FIG. 1, the conveying device runs horizontally in a first section, to which there connects a second section running diagonally upward and in which the cooling of the clinker 321 takes place.

(10) In the specific embodiment shown in FIG. 1, coolant is introduced via a coolant supply 40 under the conveying surface 37 of the conveyor belt 38. The coolant supply 40 comprises, in principle, a coolant supply distribution pipe 41 which is connected to a coolant compressor 44 and via which the coolant is distributed into coolant supply pipes 43a to 43d which, in each case possibly, as shown in particular in FIG. 2, lead via a coupling pipe to a corresponding coolant inlet 42a to 42h.

(11) At least part of the coolant heated by contact with the conveyor belt 38 is extracted through a coolant evacuation. The coolant evacuation comprises, in principle, coolant outlets via which coolant is extracted in each case via coolant evacuation pipes assigned to a coolant outlet. The coolant evacuation pipes open into a coolant evacuation collecting pipe.

(12) It is of course also conceivable to choose a different number of coolant inlets and outlets, to choose a different geometry of the coolant supply and evacuation and a different arrangement thereof along the conveying device.

(13) The solid body outlet 17 connects at the end, as viewed in the conveying direction F, of the conveyor belt 38, and in the embodiment shown is in the form of a discard chute into which the cooled clinker 321 is discarded.

(14) The cooling, brought about according to the invention in the conveying device, and corresponding coolant supplies and coolant evacuations, are further illustrated with reference to FIG. 2.

(15) As shown in the section drawing according to FIG. 2, the conveying device 1 has an elongate housing 39, coolant inlets, of which only two coolant inlets 42c and 42d are shown, coolant outlets, of which only the coolant outlet 22c is partially shown, and coolant supply nozzle pipes 45a to 45d.

(16) The conveying strand 30 and the return strand 31 of the conveyor belt 38 form a loop which, together with the lateral side walls 391 and 392 of the housing 39, encloses a space 47. Coolant is supplied to the coolant supply nozzle pipes 45a to 45d via corresponding coolant supply pipes, for example 43b. Via these coolant supply nozzle pipes, the coolant is introduced into the space 47, on that side of the conveyor belt 38 oriented away from the conveying surface 37.

(17) The coolant supply nozzle pipes shown in section in FIG. 2 are generally oriented at right angles to the side wall and, in this figure, are reproduced in a slightly distorted perspective for the sake of clarity.

(18) Openings on the coolant outlets, such as the coolant outlet 22d with openings 25d shown in FIG. 3, serve to evacuate, to the coolant evacuation collecting pipe 21, at least part of the coolant heated by contact with the conveyor belt 38. The purely exemplary representation according to FIG. 3 shows a supply coupling pipe 46b which is connected, via a coolant inlet 42d, to four coolant supply nozzle pipes 45a to 45d, via which air is introduced on that side of the conveyor belt oriented away from the conveying surface. In the specifically shown embodiment, the coolant supply nozzle pipes 45a to 45d are closed at their ends oriented away from the coolant inlet 42d and have, in their uppermost region, in each case four nozzle pipe openings 36a to 36d, via which the coolant is introduced in a distributed manner over the entire width of the conveyor belt 38.

(19) At least part of the coolant heated by contact with the conveyor belt 38 is evacuated, by means of the openings 25d on the coolant outlet 22d, to the coolant evacuation collecting pipe 21.

(20) It is of course also possible to choose a different arrangement, cross section geometry and number of the coolant supply nozzle pipes and of the openings. It is also conceivable that the coolant supply nozzle pipes do not cover the entire width of the conveyor belt. In another embodiment, the coolant supply pipes are not connected to coolant supply nozzle pipes but merely open, via openings at the inlets, into the space 47 and thus introduce the coolant.

(21) FIG. 4 represents a specific example of an air supply and corresponds to FIG. 3 with the housing: two coolant inlets 42c and 42d, arranged in the side wall 392, are connected to a coolant supply pipe 43b via a supply coupling pipe 46b. This construction unit is repeated four times in the embodiment of FIG. 1; they are in each case connected to the same coolant supply distribution pipe 41, via which a coolant compressor 44 feeds the coolant into the space 47 under the conveying strand.

LIST OF REFERENCE SIGNS

(22) 1 conveying device 2 combustion chamber 4 waste supply 6 waste chute 10 combustion grate 11 primary air supply 12a-12d funnel neck 14a-14d under-grate air chamber 15 coarse clinker discard chute 16 primary air supply line 17 solid residue outlet 20 coolant evacuation 21 coolant evacuation collecting pipe 22a-22h coolant outlet 23a-23d coolant evacuation pipe 25d coolant outlet opening 26b evacuation coupling pipe 30 conveying strand 31 return strand 32, 321 solid residues, clinker 33 (support) roller of the conveyor belt 36a-36d nozzle pipe opening 37 conveying surface 38 conveyor belt 39 housing of the conveying device 391, 392 side wall of the housing 40 coolant supply 41 coolant supply distribution pipe 42a-42h coolant inlet 43a-43d coolant supply pipe 44 coolant compressor 45a-45d coolant supply nozzle pipe 46a-46d supply coupling pipe 47 space F: conveying direction