JP2004116884A - Combustor for stoker type incinerator - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a combustor for a stoker type incinerator, having a cooling structure of a fire grate coping with very high temperature operation and performing high temperature incineration. <P>SOLUTION: This combustor for a stoker type incinerator includes: a fire grate 5, and a movable frame 5b and a fixing frame 5a for supporting it. The combustor is provided with a cast-made water cooled block 6 also serving as a fire grate fixing block and having a built-in water cooled pipe 8 disposed on the back part of the tip of the fire grate 5, and a means for circulating cooling water supplied from an external supply means to the water cooled pipe 6. In the combustor, the comparatively low-temperature fire grate part 19 and the fire gate of a comparative low temperature zone can be cooled by primary combustion air supplied by an air supply means to the lower part of the fire grate 5 and discharged to the furnace through a slit provided between the fire grates 5. A water line pipe 6 is provided with a cooled water supply pipe and a return pipe for each fire grate. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a stoker-type incinerator, and more particularly to a combustion device for a stoker-type incinerator with a grate cooling mechanism and a reciprocating stoker-type incinerator that performs a high-temperature incineration that intensively water-cools a high-temperature portion of a grate. .
[0002]
[Prior art]
[Patent Document 1] Japanese Utility Model Publication No. 4-49476 [Patent Document 2] Japanese Utility Model Publication No. 58-58234 [Patent Document 3] Japanese Patent Application Laid-Open No. 2001-173920 [Patent Document 4] Japanese Utility Model Publication No. 2-5228 In the combustion, the temperature of the furnace outlet was controlled to 950 ° C. or lower to suppress NOx. However, in recent years, high-temperature combustion of 1000 ° C. or more has been required for the purpose of dioxin reduction and high-efficiency heat recovery, and an operation in which the amount of primary combustion air is reduced and the air ratio is reduced is required, and the grate temperature becomes extremely high. In particular, in a stoker-type incinerator, there is a concern that a stoker grate for transferring an object to be treated may cause high-temperature corrosion. At about 500 ° C. or higher, the grate rapidly burns at the tip (high-temperature corrosion and wear). Conventionally, the grate has been cooled with primary combustion air. That is, in the process of supplying the primary combustion air into the furnace, cooling was performed via cooling fins provided on the lower surface of the grate. In this method, when incinerating waste containing a large amount of high-calorie refuse such as plastic, the grate temperature of the main combustion part exceeds about 600 ° C., and high-temperature corrosion cannot be suppressed. .
[0003]
In the combustion control, in the case of an incinerator with a boiler turbine, the primary combustion air is limited by the amount of heat generated and the amount of processing to control the evaporation amount (power generation amount control). Was sacrificed.
On the other hand, a method of forcibly cooling the high temperature part of the grate with a small amount of cooling air or cooling gas by air cooling of the grate has also been proposed, but high calorific value waste such as plastic is partially When the stoker burns, it is necessary to further increase the durability of the stoker.
In addition, a structure has been proposed to cool the grate by arranging complicated water-cooled piping directly on the grate, but a structure in which the water-cooled tube is cast directly into the grate, or a structure in which the water-cooled tube is in direct contact with the grate In such a structure, there are many opportunities to damage the cooling pipe due to wear of the grate or direct mechanical impact on the grate, etc.In cases where accidents due to leakage of cooling water forced the shutdown of the incinerator There is. In addition, the structure in which the water-cooled tube is directly cast into the grate causes a significant increase in the cost of the consumable grate, and requires replacement of the water-cooled tube when replacing the grate. Causes an increase.
[0004]
A grate with a cooling structure that cools the entire grate with water has also been proposed, but the temperature distribution of the grate is high at the tip, and the other parts are at a temperature sufficient for conventional air cooling, and water cooling is necessary. There is no.
If the entire grate is water-cooled, excessive heat recovery may occur, resulting in partial low-temperature parts, the purpose of high-temperature combustion, such as the generation of dioxins due to incomplete combustion and the replenishment of an external heat source to maintain high temperatures. Can be assumed.
As a mechanical harmful effect of the high temperature of the grate, there have been reported many cases in which the grate rises due to thermal expansion of the grate row, incombustibles enter the space, and a mechanical accident occurs. In addition, the metal in the dust is firmly welded to the upper surface of the grate, which causes an operation resistance, destabilizes the operation of the stoker, and requires a large driving force.
[0005]
[Problems to be solved by the invention]
In view of the above prior art, the present invention provides a stoker-type incinerator combustion device capable of high-temperature incineration, which has a grate cooling structure capable of suppressing generation of dioxin and efficiently recovering heat and capable of operating at extremely high temperatures. The task is to
[0006]
[Means for Solving the Problems]
In order to solve the above-mentioned problem, the present invention provides a combustion apparatus for a stoichiometric incinerator including a grate, a movable frame supporting the grate, and a fixed frame. ), A cast water-cooling block also serving as a grate fixing block having a built-in water-cooling tube, and means for circulating cooling water supplied to the water-cooling pipe of the block from an external supply means. This is a combustion device for an incinerator.
In the combustion device, the tip portion of the grate is hot, but the other portions are relatively cold, and at least one of the grate portion and the grate tip portion has a relatively low temperature. The grate of the section is provided with a means for cooling the air in the process of discharging the primary combustion air supplied by the air supply means to the lower part of the grate into the furnace through the slit provided between the grate as usual. Therefore, since the cooling can be performed to a sufficiently safe temperature, the entire grate is cooled by a combination of water cooling and air cooling, thereby preventing an adverse effect due to excessive cooling. In addition, the water cooling block that cools the grate is provided with a cooling water supply pipe and a return pipe for each grate, and is connected to a common supply main pipe and a return main pipe, so that the cooling water separates the individual grate. It can be cooled evenly.
[0007]
Further, in the combustion device, the water-cooling block has a shape that is cast and processed in accordance with the cross-sectional shape of the lower surface of the grate having cooling fins that also serve as reinforcing ribs of the grate, and the grate is fitted into the water-cooling block. The water-cooling block is fixed to the grate receiving frame. The grate is fitted with reinforcing ribs serving as cooling fins on the lower surface of the water-cooling block, and is integrated. By applying or filling a filler such as mortar having a high conductivity, the thermal conductivity can be increased, and the cooling effect can be further enhanced. In addition, the grate is fitted into the water-cooled block by a simple spacer inserted between the grate and the grate receiving beam. Yes, when replacing the grate, it is not necessary to remove or connect the cooling pipe, and only the grate can be removed, so that the replacement operation with high assembly accuracy can be performed in a relatively short time.
The grate is integrated with the individually fixed water-cooled block and fixed, so that the grate can maintain a stable position even if it receives mechanical external force such as lifting or spreading due to thermal expansion of the grate or bite of incombustibles. Can be maintained.
It is preferable that the cooling water introduced into the water cooling pipe has a means for controlling water quality and a mechanism for controlling the flow rate of the cooling water so that the grate temperature is 400 ° C. or less.
[0008]
BEST MODE FOR CARRYING OUT THE INVENTION
Next, the present invention will be described in detail. In a stoker-type incinerator combustion apparatus, a plurality of grate receiving beams are set on a movable frame and a fixed frame that support a stoker grate, and a plurality of grates are arranged on each receiving beam. ing. A water cooling block is fixed to the steel plate frame welded and fixed to the receiving beam, and cooling pipes built in the water cooling block are arranged in pairs for each piece of grate, and are installed in the cooling water supply branch pipe and the return branch pipe. Each is connected. The cooling water supplied from the outside is circulated through the cooling pipe via the cooling main pipe and branch pipe to cool the water-cooled block, thereby indirectly cooling the high-temperature part of the grate integrated with the block and returning to the branch. Return to the external cooling device via the pipe and main pipe. The quality of the cooling water is controlled for the purpose of preventing scale adhesion and corrosion in the piping, and the cooling water that has exchanged heat with the grate is cooled in a cooling tower, etc., treated with water, and recirculated as cooling water. Used.
[0009]
On the other hand, the primary combustion air is supplied from the under-furnace window box below the grate as before, and after contacting with the back of the grate, it is supplied to the inside of the furnace from the slit provided between the grate. Is also cooled. In a relatively low temperature range other than the water cooling section, the air cooling sufficiently suppresses burnout.
Since the water-cooled block is assembled in accordance with the complicated back surface shape of the cast steel grate, it is required to have a complicated shape and dimensional accuracy, so that it is required to be a cast product and further need to be manually finished. In addition, a filler such as a high-conductivity mortar can be applied or filled in the gap for the purpose of bringing the grate and the water-cooling block closer together, increasing the thermal conductivity, and further enhancing the cooling effect. On the other hand, when the water-cooling block is made of a material having a non-dense structure such as cast iron, since water may penetrate, cooling water cannot be supplied directly into the cast product. It has a cast-in structure. The material of the grate and the water-cooled block is heat-resistant cast iron or heat-resistant cast steel, and the material is selected according to the temperature and the corrosive environment of gas and molten salt.
[0010]
The water-cooling block has a concave and convex configuration with cooling fins that also serve as reinforcing ribs for the grate, and the lower end of the grate is integrated as a structure that hooks to the lower surface of the water-cooling block. And the vertical movement can be restrained. The length of the grate is constrained by a conventional structure.
The stoker incinerator combustion device is configured by combining a plurality of units having the same structure (FIG. 1), and the grate temperature of each unit is highest in the latter stage of the drying zone and the main combustion zone, and is higher than that of the main combustion zone. Zone is the lowest. In the present invention, water cooling or air cooling can be selected for each stoker unit or each grate row.
According to the present invention, by effectively and reliably cooling the grate based on the above-described configuration, burnout (corrosion and abrasion) of the grate is suppressed and durability is enhanced, and metal welding and abnormal expansion at high temperatures are prevented. In addition, the prevention of biting by incombustible substances is obtained, so that mechanical stability can be maintained. As a result, it is possible to provide a combustion device for a stoker incinerator that can cope with a desired high-temperature combustion.
[0011]
Next, the present invention will be described with reference to the drawings.
FIG. 1 is a configuration diagram showing an example of the furnace bottom of the stoker-type incinerator of the present invention. In FIG. 1, a multi-stage stoker 2 is arranged on a stoker furnace bottom 1. The configuration of the stoker 2 has four zones of a drying stoker 2a, a combustion I stoker 2b, a combustion II stoker 2c, and a post-combustion stoker 2d in the flow direction of the refuse. different. Also, the number of divided units is different. The grate temperature of each zone is different, and the grate cooling method (water cooling, air cooling) can be freely selected for each grate row.
FIG. 2 shows an enlarged sectional view of the stoker portion of FIG. The stoker unit shown in FIG. 2 employs a reciprocating reciprocating system in rows and columns, which keeps the gap between the grate uniform and minimizes blow-through and dust of the combustion air. In addition, the fixed frames 5a and the movable frames 5b are alternately arranged to effectively transfer, invert, and agitate the refuse.
[0012]
The main parts of the present invention are the grate 5, the water cooling block 6, and the frame structure 7 shown in FIG. 2 (side view of the stoker) or FIG. Regardless of the movable grate receiving beam 7b or the fixed grate receiving beam 7a, the receiving beam includes a frame 7 for fixing the water cooling block 6. The water-cooling block 6 is fixed to the frame 7 by bolts or the like, and includes a water-cooling tube 8. As shown in FIG. 4, the water cooling pipe has a supply pipe 8a and a return pipe 8b, and the supply branch pipe 9a and the return branch pipe are connected to the water cooling block 6 and the fixed frame 7, respectively. 9b. The supply branch pipe 9a and the return branch pipe 9b are similarly arranged regardless of a movable or fixed grate receiving beam, and are connected to the supply main pipe 10a and the return main pipe 10b along the stoker frame. Since the movable frame moves with a stroke of about 400 mm, each main pipe is connected to an external main pipe by a flexible joint.
[0013]
FIG. 4 shows a grate width cross-sectional view of the cooling unit. The grate 5 is paired with the water-cooling block 6 for each piece, and the water-cooling block has an uneven shape 11 corresponding to a reinforcing rib shape also serving as a cooling fin on the grate surface, and the grate 5 is fitted therein. By doing so, they can be integrated. The method of setting the grate on the receiving beams 7a and 7b and the water cooling block 6 is as follows. The groove 12 at the rear of the grate is inserted into the flat steel 13 on the upper surface of the receiving beam, and then slid to the rear side of the grate. The protrusion 14 is fitted into the lower part of the water cooling block. Needless to say, at this time, the concave and convex portions of the grate rib also need to be aligned with the same position of the water-cooling block. The final fixing of the grate is completed by inserting the spacer 15 into the gap formed by the flat steel 13 and the grate rear groove 12 on the grate receiving beam. In this procedure, the grate is positioned and fixed. In this way, in the grate replacement work, there is no need to perform the work of attaching and detaching the water cooling tube, and only the grate can be replaced easily as in the case of the conventional (air-cooled) grate.
[0014]
The small gap 16 formed by the grate 5 and the water-cooling block 6 is coated and filled with mortar or the like having a high thermal conductivity to further enhance the cooling effect of the grate.
As described above, the grate 5 and the water-cooled block 6 are integrated, and the grate high-temperature portion can be effectively cooled.
On the other hand, the primary combustion air is supplied from the combustion air duct 18 to the lower furnace wind box 17, and the low temperature portion 19 of the grate 5, the stoker frames 5a and 5b, and the stoker parts (the drive shaft 20, the wheels 21, the drive arms 22, and the like). After cooling, it is discharged into the furnace through a slit provided between the grate.
[0015]
【The invention's effect】
In the present invention, the following effects can be obtained by employing the above-described configuration.
(1) The indirect water cooling through the grate's water-cooling block can effectively and safely cool the grate tip of the main combustion section, which is susceptible to burnout (high-temperature corrosion and abrasion). It has a cooling structure that can be stably maintained at 400 ° C. or lower and has a remarkably higher cooling effect than conventional air cooling.
(2) Because of the combined use with air cooling and the cooling structure of one piece of grate, water can be cooled with a limited range of the stoker, and excessive cooling of the incinerator can be suppressed.
(3) By reducing the grate temperature, the thermal expansion of the grate is suppressed, the metal deposition on the grate surface is also suppressed, and the grate is securely fixed, so that the mechanical stability of the stoker is remarkably improved. Be improved. As a result, the chance of shutting down the furnace due to an accident can be significantly reduced.
[0016]
(4) In the work of replacing the grate, the work of removing and attaching the water cooling tube is not required, and the work load can be made approximately the same as the conventional grate replacement.
(5) By arranging the water cooling tube in a block separated from the grate, it is possible to provide a highly safe structure with respect to a water leak accident caused by abrasion, impact force or the like directly received by the grate.
(6) A design in which the grate life is set to about 50,000 hours or more can be achieved.
(7) As described above, a stoker-type incinerator combustion device having a cooling structure capable of coping with high-temperature incineration for the purpose of dioxin reduction can be provided.
[Brief description of the drawings]
FIG. 1 is a configuration diagram showing an example of a furnace bottom portion of a stoker type incinerator of the present invention.
FIG. 2 is an enlarged sectional view of a combustion unit of the stoker type incinerator of FIG. 1;
FIG. 3 is a partially enlarged view of a grate and a frame part of FIG. 2;
FIG. 4 is a sectional view of a grate width of the cooling unit in FIG. 3;
[Explanation of symbols]
1: stoker type incinerator, 2: stoker, 3: intermediate partition, 5: grate, 5a: fixed frame, 5b: movable frame, 6: water cooling block, 7: frame structure, 7a, 7b: receiving beam, 8: Water-cooled pipe, 8a: supply pipe, 8b: return pipe, 9a: supply branch pipe, 9b: return branch pipe, 10a: supply main pipe, 10b: return main pipe, 11: uneven, 12: groove, 13: flat steel, 14 : Convex portion, 15: spacer, 16: minute gap, 17: furnace bottom wind box, 18: combustion air duct, 19: low temperature portion

Claims (7)

In a combustion apparatus for a stoichiometric incinerator provided with a grate, a movable frame supporting the grate, and a fixed frame, a casting-type water cooling device serving as a grate fixed block having a built-in water cooling tube on the back surface of the tip of the grate. A combustion device for a stoichiometric incinerator, comprising a block, and means for circulating cooling water supplied to a water cooling pipe of the block from an external supply means. In the combustion device, at least a part of the grate is cooled by air while the primary combustion air supplied by the air supply means to the lower part of the grate is discharged into a furnace through a slit provided between the grates. 2. A stoker-type incinerator combustion apparatus according to claim 1, further comprising: The stoker type incinerator combustion apparatus according to claim 1, wherein the water-cooling block for cooling the grate includes a cooling water supply pipe and a return pipe for each grate. The stoker type incinerator combustion apparatus according to claim 1, wherein the water-cooled block has a shape cast and processed in accordance with a cross-sectional shape of a lower surface of a grate. The stoker type incinerator combustion apparatus according to claim 4, wherein a filler having high thermal conductivity is applied or injected into a gap between the grate and the water cooling block. 5. The combustion apparatus according to claim 4, wherein the grate is fitted into the water-cooled block by a simple spacer inserted between the grate and the grate receiving beam. . The cooling water introduced into the water cooling pipe is provided with means for controlling water quality, and a mechanism for controlling a flow rate of the cooling water so that the grate temperature is 400 ° C. or less is provided. 5. The combustion device for a stoichiometric incinerator according to any one of items 4 to 4.

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