WO1995009327A1 - Method of feeding refuse onto an incinerator grate, and feed device for carrying out the method - Google Patents

Abstract

The method proposed for feeding refuse onto an incinerator grate is characterized in that the refuse (4) is divided into loads in the feed chute (1) and the material in the individual loads fed continuously on to the incinerator grate (2). The height at which the material is fed in can be varied. The device used to carry out the method consists of feed-control rods (9, 10), a refuse-transfer device (5) and a drop gate (7). The refuse (4) is divided into loads in the feed chute (1) by the control rods (9, 10) which are disposed at two levels one above the other. From the feed chute (1), the refuse falls on to the transfer device (5) which consists of several bar-like conveyor elements (18 to 24). The individual conveyor elements (18 to 24) are hollow, thus enabling them to be cooled by a coolant if necessary. The conveyor elements in the transfer device (5) are divided into two sets, the motion of one set being phase-staggered with respect to the other, thus enabling the refuse (4) to be fed continuously on to the incinerator grate (2). The height of the drop gate (7) at the chute exit can be adjusted. If necessary, conveyor elements like those in the transfer device (5) can be fitted in the drop gate (7).

Description

 Method for loading a waste incineration grate and loading device for carrying out the method

The present invention relates to a method for loading a waste incineration grate. Furthermore, the invention relates to a loading device for carrying out the method.

In most rubbish incineration plants used today, the rubbish reaches the charging device via the feed hopper, through the charging chute. This device mainly consists of a piston valve which, under hydraulic control, slowly pushes the waste towards the combustion grate. At the end of the loading device, the garbage falls onto the combustion grate by gravity. When the slider has reached the front, it is pulled back and the procedure starts again. This batch-wise loading of the garbage reaches the incineration grate unevenly and in portions. Since the garbage is compressed by the large weight of the rubbish in the loading chute, lumps form. During the loading process, it often happens that at the transition point from the loading chute to the combustion grate, such lumps uncontrollably on the Crash burn rust. This means that a larger amount of rubbish was being added to the incineration grate than was desired. This results in an irregular loading of the combustion grate with a large amount of dust and consequently the height of the garbage bed is not always the same thickness, which causes locally different combustion on the combustion grate and, in connection with this, an inhomogeneous flame pattern in the combustion chamber.

The pipe structure installed in the combustion chamber for heat exchange must be protected from the flames so that it is not damaged by the heat generated by the flames. The uneven layer thickness on the combustion grate and the resulting possible high flame peaks mean that the pipe construction in the combustion chamber is shielded sufficiently with a tamping. On the other hand, this ramming represents insulation that reduces heat exchange and thus reduces the steam output of the system. It is therefore desirable to keep the area that has to be covered with the tamping as small as possible.

The falling of garbage from the loading chute onto the incineration grate causes dust to develop, which is very undesirable, because the heat in the combustion chamber melts the dust particles on their surface and then attaches to the pipes and the ramming in the combustion chamber. Through these deposits of the melted dust particles on the pipes and on the one hand, the life of the materials is shortened on the ramming and, on the other hand, the deposition forms an insulation layer which further reduces the heat transfer, which means a reduction in the steam output. The cause of garbage falling from the loading chute is not only the lump formation and the batch-wise, batch-like conveying of the garbage onto the incineration grate, but also the high temperature in the area of the loading device. The heating of the waste in the area of the loading device is made possible by the large opening at the transition from the loading device to the combustion grate. Depending on the composition of the garbage, the garbage is gasified or ignited prematurely, which in turn causes garbage to fall onto the incineration grate, which in turn leads to additional dust formation in the combustion chamber.

The object of the present invention is now to provide a method for charging a waste incineration grate which ensures a uniform garbage bed height on the incineration grate and which prevents uncontrolled falling of waste from the charging chute onto the incineration grate, and the dust development in the combustion chamber is severe reduced. On the other hand, it is an object of this invention to provide a device for carrying out the method for loading the combustion grate, which works reliably and is inexpensive to manufacture. This object is achieved by a method for loading a waste incineration grate, which is characterized in that the waste is portioned in the loading chute and that the material of the individual portions is continuously fed to the incineration grate in a defined layer thickness.

The further object of the invention is achieved by a device for carrying out the method for loading a waste incineration grate. This device is characterized by means for portioning the rubbish in the feed chute and means for continuously feeding the material of the individual portions onto the combustion grate, and by a variable shaft opening for regulating the layer thickness of the rubbish being fed.

The method according to the invention is explained on the basis of the schematic drawings and a feed device, for example, is described in detail.

It shows :

Figure 1: A schematic vertical section through an incinerator in the loading area;

Figure 2: A schematic horizontal section through the loading chute in the area of the feed control rods; Figure 3: A schematic plan view of the loading device;

FIG. 4: A schematic perspective illustration of two adjacent feed elements of the loading device;

Figure 5: A movement diagram of the feed elements of the loading device.

The method according to the invention for loading a waste incineration grate is explained with reference to FIG. 1. In the process, the garbage is portioned in the feed chute 1 and the material of the individual portions is fed continuously to the combustion grate 2. The material is fed in at a variable, adjustable feed height. By regulating the feed height of the refuse, a desired layer thickness of the material on the combustion grate 2 can be achieved.

The garbage passes through the feed hopper 3 into the feed chute 1. At the lower end of the feed chute 1, the garbage 4 arrives at the loading device 5. This charging device, the construction and mode of operation of which is described in more detail with reference to FIG. 3, continuously conveys the garbage 4 to the combustion grate 2 At the outlet of the feed chute 1 there is a height adjustable Lock 7. This lock 7 regulates the garbage bed height. In the example shown, the lock 7 only serves to regulate the height of the garbage bed. In an application (not shown here) of the method according to the invention, conveyor elements, such as those installed in the loading device 5, are also installed in the lock 7. This has the advantage that the waste is not only transported continuously from below, but also that conveyor elements move the waste forward from above. With certain garbage compositions, this measure is advantageous in order to improve the continuity of the transport.

In order to ensure optimal combustion in the combustion chamber 8, there is a negative pressure with respect to the atmosphere. For this reason, the feed chute 1 must be filled with garbage in the operating state of the incineration plant so that no outside air can enter the combustion chamber 8 from the side of the feed chute 1. The garbage in the loading chute acts as a locking pin and weighs several tons on the loading device. Depending on the composition of the rubbish, it is compressed to a greater or lesser extent, and when the waste is continuously transported from the loading device 5 to the incineration grate 2, blockages can occur at the lock 7. In order to avoid this, the loading device 5 is relieved in that the rubbish 4 is fed in portions from the loading chute 1 to the loading device 5. The portioning is done with feed control rods 9.10. For this purpose, these feed control rods 9, 10 are arranged one above the other in the feed chute 1 in two planes. These feed control rods 9, 10 consist of individual movable rods which can be pushed into the interior of the feed chute 1 and out of the feed chute 1 by means of a drive 16. In the example shown, four loading control rods are mounted on one level on two opposite walls of the loading chute 1. The arrangement of the loading control rods 9, 10 within the individual levels and their mode of operation is described with reference to FIG. 2.

First, the feed control rods 9 of the upper level are moved into the feed chute 1. As a result, the cross section of the feed chute 1 is narrowed by the retracted feed control rods so that the garbage 4 can no longer slide. The feed control rods 10 of the lower level are completely pulled out of the feed chute 1 and the waste below the upper feed control rods can fall onto the feed device 5 unhindered. As soon as the garbage 4 is transported away from the charging device 5 to the combustion grate to such an extent that the area of the lower level of the charging control rods 10 is free of garbage, these rods 10 close, ie they are moved into the charging chute 1. When they have reached their desired end position, the feed control rods 9 of the upper level are pulled out of the feed chute 1 and the rubbish 4 slides down to the lower level with the Feed control rods 10 after. Before the feed control rods 10 are withdrawn, however, in order to convey the waste onto the loading device 5, the feed control rods 9 are again inserted into the loading chute 1 in order to prevent the waste from slipping. Through this alternate retraction and retraction of the feed control rods 9, 10, the garbage is fed into the feed device 5 in portions. Thus, only the weight of the last garbage portion supplied is loaded on the loading device 5, and by the portionwise feeding of the garbage to the loading device 5, jams of the waste are prevented at the lock.

The height of the garbage bed, that is the layer thickness of the garbage on the combustion grate 2, is regulated with the lock 7. This lock 7 can be raised and lowered hydraulically in the vertical direction, for example, and depending on the set position, the outlet opening 6 has a defined height from the loading chute 1 and from the loading device 5 to the combustion grate 2. This height also corresponds to the layer thickness of the waste which is fed to the combustion grate 2 by the loading device 5. With this adjustable lock, a desired layer thickness of waste can be set on the combustion grate. In the drawing 1, the combustion grate 2 is inclined downward away from the loading device 5. However, the method according to the invention is also suitable for combustion grates that are horizontal are arranged, or also for gratings that rise away from the loading device 5.

Through the lock 7, the opening to the charging chute is reduced in such a way that no heat can penetrate into the charging chute 1. This prevents the undesired falling of the rubbish 4 onto the combustion grate 2. The result is a reduction in dust formation. The dust particles, which melt on the surface due to the heat 'in the combustion chamber 8, accumulate on the tubes 11 of the boiler and on the tamping 12. These deposits are extremely undesirable because they reduce the life of both the tubes 11 and the tamping 12 and thus shorten the travel time of the incinerator. They also form an insulating layer, which results in a reduction in heat exchange. As a result of the reduction of the dust in the combustion chamber, which is achieved with the method according to the invention, the boiler is fogged up with dust less high and therefore an extension of both the service life of the boiler and the evacuation is achieved. This increases the travel time of the incineration plant and, because of the increased number of heat exchangers, also increases the technical efficiency of such an incineration plant.

Due to the uniform height of the garbage bed, which is achieved through the continuous loading of the combustion grate 2 with the loading device 5 and through the height-adjustable lock 7, the combustion in the combustion chamber 8 is regular and controllable, that is to say that the flame height is uniformly high and a geometrically defined fire can thus be started. As a result, the necessary height of the ramming 12 in the combustion chamber 8 can be considerably reduced, which increases the usable area of the boiler and, in conjunction therewith, improves the utilization of the heat.

In the conventional incineration plants, the distance from the rear wall 13 with the tubular construction 11 mounted on this wall to the charging chute 1 must be large enough to avoid overheating of the waste in the charging chute 1. In these systems, the heat reaches the feed chute 1 through the opening 6, which is very large there to avoid clogging. In the method according to the invention, the lock 7 prevents the waste in the feed chute from heating up. As a result, the distance between the rear wall 13 of the combustion chamber 8 and the charging chute 1 can be reduced by eliminating the need for a fire blanket in the region of the opening 6. The space gained by the removal of the primer is used to enlarge the pipe construction. This means that the surface available for heat exchange can be enlarged and the combustion heat of the refuse can be better used.

FIG. 2 shows a schematic cross section through the feed chute 1 in the area of the feed control rods 9. These feed control rods 9, 10 for portioning the waste 4 in the feed chute 1 are arranged one above the other in two levels and can be moved by means of a drive 16 transversely to the direction of conveyance of the waste 4 into the interior of the feed chute 1 and out of the feed chute 1. The drive is hydraulic, with the impact force of the individual rods being adjustable with a hydraulic control. The drive is also conceivable with electric motors. In the example shown, four loading control rods are mounted in one plane on two opposite walls 14, 15 of the loading chute 1. In the example described, the rods are moved hydraulically and can be fully extended from the loading chute. In the opposite direction, they can be retracted up to about half the inner width of the loading chute. The dimensions of these rods are designed so that each individual rod is able to bear the load of the refuse above it in the loading chute 1. The hydraulic control of the feed control rods 9, 10 is force-controlled, the drives of the individual rods being connected to one another and being operated by a common control unit, not shown here. This means that, for example, a rod blocked by a hard object 17 in the refuse cannot be moved further into the feed chute 1, but the other rods can, however, be inserted unhindered up to their end position. The two levels of the feed control rods 9, 10 are constructed identically. The rods 9, 10 can be positioned via a central control, and by means of the alternating one Retracting and retracting the rods into and out of the feed chute 1, the garbage 4 is delivered in portions to the loading device 5.

FIG. 3 shows a schematic top view of the loading device 5. This loading device consists of several feed elements 18-24. The number of feed elements used depends on the size of the feed chute 1. In the example shown, seven feed elements 18-24 are mounted in the feed device 5. The feed elements form a kind of platform, which forms the lower end of the loading chute 1. The individual feed elements 18-24 have the shape of a bar on the outside. The area on which the rubbish lies is structured. The feed elements are hollow on the inside and connections are provided on the underside so that the feed elements 18-24 can be connected to a cooling system if necessary. For temperature control, a cooling medium is pumped through the feed elements, which cools the rubbish on the loading device 5. Of course, the procedure can also be reversed and, if necessary, a temperature-controlled medium can flow through the feed elements in order to heat the waste lying on it.

In Figure 4, two of these feed elements 18-24, which are made of sheet metal, are shown in a schematic, perspective view. The feed elements are structured on the surface to better convey the waste. to be able to. In the example shown, the feed elements 18, 19 have a sawtooth-like structure with coarse teeth. However, this structure can also be finer. Likewise, the shape of the structure can be adapted according to the needs for the continuous transport of the waste. On the underside of the feed elements 19-24, the connecting pieces 25 are attached in order to be able to connect them to a cooling or heating system, if necessary, in order to temper the garbage lying on the feed elements.

The feed elements 18-24 alternately perform a stoking movement so that they continuously convey the garbage stored on them towards the combustion grate 2. In the case of the feed elements 18-24 shown schematically in FIG. 3, the non-adjacent feed elements are in each case firmly connected to one another and simultaneously carry out the same movement sequence. A diagram of the movement sequence is shown in FIG. If, for example, the feed elements 18, 20, 22, 24 are in their foremost position, that is to say closest to the combustion grate 2 - this position corresponds to the number 26 in the diagram in FIG. 5 - then this group of feed elements 18, 20 22.24 lowered until they have reached the lowest point 27. The feed elements are then withdrawn and raised again until they have returned to the top position. In the now following forward movement, the feed elements 18, 20, 22, 24 convey the garbage lying on them in the direction Burn grate. The second group of feed elements performs the same sequence of movements as the one just described, except that this movement is out of phase. As soon as the one group of feed elements 18, 20, 22, 24 has reached the foremost point and the backward movement begins, the second group has reached the rearmost point 28 and begins with the forward movement. This opposite movement sequence of the two groups of feed elements ensures a continuous loading of the combustion grate.

The lock 7 shown in FIG. 1, which can be hydraulically or electrically driven, only serves to regulate the height of the garbage bed in the exemplary embodiment. In an embodiment not shown here, conveyor elements are installed in the lock as they are installed in the loading device 5. This means that the waste is continuously moved forward from below as well as from above with conveyor elements.

Claims

claims 1. A method for loading a garbage combustion grate (2), characterized in that the garbage (4) is portioned in the feed chute (1) and that the material of the individual portions of the combustion grate (2) is continuously in a defined layer thickness is fed. 2. The method according to claim 1, characterized in that the continuous supply of the material takes place in a variable and controllable feed height which does not exceed the optimal layer thickness of the material on the combustion grate (2). 3. The method according to any one of the preceding claims, characterized in that the continuous feeding takes place by means of temperature-adjustable feed elements (18-24). 4. Apparatus for carrying out the method for loading a waste incineration grate, characterized by means (9, 10) for portioning the waste (4) in the loading chute (1), by means (5) for continuously feeding the material of the individual Portions on the combustion grate (2), as well as through a variable shaft opening (6) to regulate the layer thickness of the refuse supplied. 5. The device according to claim 4, characterized in that the means for portioning the garbage (4) in the feed chute (1) are feed control rods (9, 10) which by means of a drive (16) in the interior of the feed chute (1) and can be moved out of the loading chute (1). 6. The device according to claim 5, characterized in that the loading control rods (9, 10) for portioning the refuse in the loading chute (1) are arranged one above the other in two planes. 7. The device according to claim 5 or 6, characterized gekennzeich¬ net that the feed control rods (9,10) are hydraulically actuated, the impact force of the individual feed control rods (9,10) is adjustable with a hydraulic control. 8. The device according to claim 4, characterized in that the means (18-24) for continuously feeding the material of the individual portions onto the combustion grate (2) are feed elements (18-24), these feed elements are coupled to one another such that the non-adjacent feed elements (18,20,22,24); (19,21,23) are connected to each other and form a group and these groups are so movable to each other that they perform an opposite movement. 9. The device according to claim 8, characterized in that the feed elements (18-24) on the outside generally have the shape of a bar, the surface on which the rubbish lies has a structure that these feed elements (18-24) made of sheet metal are manufactured, are hollow on the inside and have on their underside connecting pieces (25) for the supply and discharge of a medium to be flowed through them. 10. Device according to one of the claims 4 to 9, characterized in that the opening (6) of the loading chute (1) is adjustable in height by means of a hydraulic lock (7).