Stoker-type combustion device

Abstract

This invention provides a hearth-type combustion apparatus having a cooling structure for the side grates that can also withstand operation at extremely high temperatures. The hearth-type combustion apparatus includes at least one pair of side grate units 100 respectively disposed on the inner surface of the furnace sidewall 10. Each side grate unit 100 includes: a side grate 30 opposite to the end faces of grates 12, 14, and 16; a movable beam 40 disposed along its length on the back side of the side grate 30 and connected to the side grate 30; and an elastic member 60 whose installation position can be adjusted by operation from outside the furnace sidewall 10. The side grate 30 is configured to be able to move freely towards the grate when force is applied inward by means of the movable beam 40 and the elastic member 60. The movable beam 40 has a cooling water inlet chamber 76 connected to a cooling water supply pipe 75 and a cooling water outlet chamber 78 connected to a cooling water return pipe 77. The cooling water outlet chamber 78 communicates with the cooling water inlet chamber 76.

Description

Technical Field

[0001] The present invention relates to a hearth-type combustion device used in waste incineration, and more particularly to a horizontally reciprocating hearth-type combustion device capable of absorbing thermal expansion of a grate and performing stable combustion. Prior Art

[0002] A known hearth-type combustion system used for waste incineration and other applications is a horizontally reciprocating hearth-type combustion system. This system features movable and fixed grates extending across the furnace sidewalls. These grates are arranged alternately in a staircase pattern along the direction of waste flow. The movable grates reciprocate relative to the fixed grates, stirring the waste while conveying it downward and combusting it. Such hearth-type combustion systems must absorb the thermal expansion of the grates and prevent gaps from forming between the grates and the furnace sidewalls.

[0003] Therefore, in conventional hearth-type combustion devices, side grates are placed on the inner surface of the furnace side wall opposite the grate end face to prevent combustion air leakage and refractory wall wear. A movable beam, biased by an elastic member, is placed in contact with the inner surface of the side grate (see, for example, Patent Document 1). This structure allows the side grates to advance and retract relative to the grate in response to thermal expansion of the grate, thereby absorbing the thermal expansion of the grate and, as a result, preventing the formation of gaps between the grate and the furnace side wall. Prior art literature Patent Literature

[0004] Patent Document 1: Japanese Patent No. 3871484

[0005] In recent years, hearth-type combustion systems have been required to operate at extremely high temperatures exceeding 1000°C to reduce dioxin emissions and efficiently recover heat. Furthermore, they are being required to reduce the amount of primary combustion air and lower the air ratio. This has led to the risk of extremely high temperatures within the furnace, causing burnout (high-temperature corrosion and wear) of castings such as grates and side grates. In particular, rapid burnout of the front end of grates and side grates at temperatures above approximately 500°C is known to be more severe.

[0006] However, although proposals have been made regarding cooling structures for grates in the past, no effective proposals have been made regarding cooling structures for side grates. Summary of the Invention

[0007] Therefore, an object of the present invention is to provide a hearth-type combustion apparatus having a side grate cooling structure capable of also coping with operation at extremely high temperatures.

[0008] In one embodiment, a hearth-type combustion device is provided, comprising: at least one pair of side grate units respectively arranged on the inner surface of the furnace side wall; and a plurality of grates arranged across the pair of side grate units. In the hearth-type combustion device, the side grate units comprise: side grates opposite to the end faces of the grate; movable beams arranged along the length direction of the back side of the side grate and connected to the side grate; and elastic components capable of adjusting the installation position by operation from the outside of the furnace side wall. The side grate is constructed to be urged inwardly by the movable beam and the elastic component and to be freely advanced and retreated toward the grate. The movable beam comprises: a cooling water inlet chamber connected to a cooling water supply pipe; and a cooling water outlet chamber connected to a cooling water return pipe, the cooling water outlet chamber being connected to the cooling water inlet chamber.

[0009] In one embodiment, the side grate unit further includes at least one cooling water block arranged between the movable beam and the side grate, the cooling water block having at least one cooling water flow path, the cooling water flow path having an inlet connected to the cooling water inlet chamber and an outlet connected to the cooling water outlet chamber. In one embodiment, the cooling water block is fixed to the back surface of the side grate using a filler, and the filler is mixed with a material having a higher thermal conductivity than the filler. In one embodiment, the cooling water inlet chamber and the cooling water outlet chamber extend along the length direction of the movable beam and over the entire length of the movable beam.

[0010] In one embodiment, the cooling water inlet chamber is arranged below the cooling water outlet chamber. In one embodiment, the hearth-type combustion device further includes a flange for fixing the side grate unit to a frame structure of the furnace side wall. In one embodiment, the cooling water inlet pipe and the cooling water return pipe extend through the flange, and a gap between the flange and the cooling water inlet pipe, and a gap between the flange and the cooling water return pipe are sealed by sealing members, respectively. Effects of the Invention

[0011] According to the present invention, thermal expansion of the grate across the grate width is absorbed by the elastic force of the elastic member that applies force to the side grates. Furthermore, sealing between the grate and the side grates is achieved by the side grates being pressed against the grate end faces by the elastic force of the elastic member. Furthermore, the side grates are cooled by cooling water during operation. As a result, the side grates can also operate at extremely high temperatures. Simple diagram description

[0012] FIG1 is a diagram schematically showing the overall structure of a hearth-type combustion device according to one embodiment. FIG2 is a perspective plan view schematically showing a side grate unit according to one embodiment. FIG3 is a cross-sectional view of the side grate unit taken along line AA shown in FIG2 . FIG4 is a cross-sectional view of the side grate unit taken along line BB shown in FIG2 . FIG5 is a cross-sectional view taken along line CC of the side grate unit shown in FIG2 . FIG6 is a perspective plan view schematically showing a side grate unit according to another embodiment. Implementation Method

[0013] Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. Figure 1 schematically illustrates the overall structure of a hearth-type combustion device according to one embodiment. As shown in Figure 1 , within the incinerator, fixed grates 12 and movable grates 14 are arranged alternately in a stair-like pattern, straddling the furnace sidewalls 10 and along the direction of waste flow. Figure 1 depicts only one furnace sidewall 10. End grates 16 are located upstream of these grates 12 and 14. The fixed grate 12 is fixed to a fixed frame 18, while the movable grate 14 is fixed to a movable frame 26 that reciprocates via wheels 22 and rails 24 as a hydraulic cylinder 20 operates. Furthermore, scrapers 28 are attached to the fixed and movable grates 12, 14, respectively, and slide along the upper surface of the fixed or movable grate 12, 14, located below.

[0014] Furthermore, a pair of side grates 30 are disposed on the furnace sidewall 10 at positions facing the end surfaces of the fixed grate 12, movable grate 14, and end grate 16, respectively. A sealing block 32 is disposed above each side grate 30. FIG1 depicts only one side grate 30 and one sealing block 32 disposed above it.

[0015] As the movable grate 14 reciprocates, it stirs the garbage fed from the garbage hopper (not shown) while conveying it downward and burning it. At this point, the end faces of the fixed grate 12, movable grate 14, and end grate 16 press against the surface of the side grate 30, sealing it there. Seal blocks 32 also seal the gap between the side grate 30 and the furnace sidewall 10. The side grate 30 is a component of the side grate unit (described later) and faces the end faces of the grates 12 and 14.

[0016] FIG2 is a perspective top view schematically showing a side grate unit according to one embodiment, and FIG3 is a cross-sectional view of the side grate unit shown in FIG2 taken along line AA. FIG4 is a cross-sectional view of the side grate unit shown in FIG2 taken along line BB, and FIG5 is a cross-sectional view of the side grate unit shown in FIG2 taken along line CC.

[0017] The side grate unit 100 shown in FIG2 includes the side grate 30 described above and is disposed on the inner surface of the furnace side wall 10 (see FIG1 ). The side grate unit 100 is a unit that enables the side grate 30 to advance and retreat relative to the grates 12 and 14 and is used to cool the side grate 30.

[0018] As shown in Figures 2 and 3, a bracket 36 with an L-shaped cross section is mounted on the inner surface of a support frame 34 that supports the furnace side wall 10. The side grate 30 is slidably supported on the upper surface of this bracket 36. This structure allows the grate 12 (14, 16) to be supported by the bracket 36 without being hindered from moving due to thermal expansion.

[0019] On the back side of the side grate 30, a movable beam 40 is disposed, extending substantially the entire length of the side grate 30 in the longitudinal direction. At least one cooling block 70 is disposed between the movable beam 40 and the side grate 30. In the illustrated example, the side grate unit 100 includes four cooling blocks 70, and the movable beam 40 is connected to the side grate 30 via the cooling blocks 70.

[0020] The cooling block 70 is fixed to the movable beam 40 by welding, for example, and to the back of the side grate 30 by a filler (e.g., a heat-resistant adhesive). The filler, such as the heat-resistant adhesive, completely blocks the gap between the back of the side grate 30 (a casting) and the bonding surface of the cooling block 70, thereby achieving efficient heat exchange between the cooling block 70 and the side grate 30. It is preferable to uniformly mix a substance with a higher thermal conductivity than that of the filler (e.g., copper powder) into the filler. By mixing such a substance into the heat-resistant adhesive at a specified ratio, more efficient heat exchange between the cooling block 70 and the side grate 30 is achieved.

[0021] The type of filler is arbitrary as long as the cooling block 70 can be fixed to the side grate 30. For example, the filler can be a heat-resistant adhesive or a heat-resistant mortar.

[0022] The movable beam 40 is composed of a main body 42, for example, with an H-shaped cross section; upper and lower cover members 43 and 44, respectively, which close the upper and lower openings of the main body 42; and side cover members 45 and 46, which close the end surfaces of the main body 42. In this embodiment, the main body 42 is made of so-called H-shaped steel. The upper and lower cover members 43 and 44 extend along the entire length of the main body 42 and are secured to the main body 42 by welding. The side cover members 45 and 46 are secured by welding to the end surfaces of the main body 42, whose upper and lower openings are closed by the upper and lower cover members 43 and 44. By closing the upper, lower, left, and right openings of the main body 42 with the cover members 43, 44, 45, and 46, sealed upper and lower spaces are formed within the movable beam 40. The upper and lower spaces formed in the movable beam 40 function as the cooling water inlet and outlet chambers, described later.

[0023] The lower cover member 44 of the movable beam 40 is slidably supported on a support plate 52 connected to the furnace sidewall 10 via legs 72. In one embodiment, the bottom plate of the support box 50, which provides both support and sealing for the furnace sidewall 10, can be used as the support plate 52. The movable beam 40 is arranged so as to slide easily along the furnace width on the support plate 52.

[0024] The side grate unit 100 also includes at least one guide tube 54 extending within the furnace side wall 10 and a flange 74 for connecting the guide tube 54 to the furnace side wall frame structures 81, 82. In this embodiment, the side grate unit 100 includes two guide tubes 54. Each guide tube 54 is secured to a through-hole in the flange 74, which is then secured to the furnace side wall frame structures 81, 82 using fasteners such as bolts. With the flange 74 secured to the frame structures 81, 82, the side grate unit 100 is secured to the furnace side wall frame structures 81, 82. By loosening the fasteners, the side grate unit 100 can be pulled out of the furnace.

[0025] A cylindrical head member 56, fixed to the side of the movable beam 40, is loosely fitted into the incinerator-side end of each guide tube 54. Furthermore, an adjustment bolt 58 is housed within each guide tube 54, with its quadrangular prism-shaped head 58a exposed. A large-diameter guide portion 58b is formed at the tip of the adjustment bolt 58, loosely fitting into the guide tube 54. A coil spring 60, serving as an elastic member, is embedded between the large-diameter guide portion 58b and the head member 56.

[0026] A nut 64, which is threadedly engaged with the adjustment bolt 58, is fixed to the outer shell 62 of the furnace side wall 10 via a flange 66. Thus, the mounting position of the coil spring 60 can be adjusted by rotating the adjustment bolt 58 from outside the furnace side wall using, for example, a wrench.

[0027] Here, the movable beam 40 is provided along the longitudinal direction of the side grate 30, extending substantially the entire length of the side grate 30. Therefore, by using at least one coil spring 60 to press the movable beam 40 toward the side grate 30 from any longitudinal position, the side grate 30 can be biased (pressed) toward the grates 12, 14, and 16 within the furnace. Consequently, the pressing mechanism, such as the guide tube 54 and the adjustment bolt 58, can be positioned at any position relative to the side grate 30, allowing the mounting position of the coil spring 60 to be adjusted from outside the furnace side wall 10.

[0028] A gap S is provided between the end surfaces of the side grate 30 and the inner surface of the furnace side wall 10. This gap S functions as an expansion margin to absorb the movement of the side grate 30 associated with the thermal expansion of the grates 12 (14, 16). Furthermore, a sealing block 32 is provided above the gap S to seal the gap S. The sealing block 32 is formed, for example, from a heat-resistant casting.

[0029] Since the gap S between the side grate 30 and the furnace side wall 10 is sealed by the sealing block 32, incineration ash and incombustible materials are prevented from entering through the gap S. Therefore, the gap S can be maintained for a long period of time, and the problem of abnormal wear between the side grate 30 and the grate 12 (14, 16) is eliminated. As a result, the replacement cycle of the side grate 30 can be extended.

[0030] In this embodiment, the coil spring 60 is first retracted using the adjustment bolt 58. In this state, the grates 12, 14, 16 and the side grate 30 are positioned to their desired positions. Next, the coil spring 60 is advanced using the adjustment bolt 58, moving the side grate 30 toward the grates 12, 14, 16. The elastic force of the coil spring 60 presses the surface of the side grate 30 against the end surfaces of the grates 12, 14, 16. This operation prevents the formation of gaps between the surface of the side grate 30 and the end surfaces of the grates 12, 14, 16 during the initial operation. Furthermore, the sealing block 32 is installed to seal the upper portion of the gap S between the side grate 30 and the furnace side wall 10. Furthermore, after a certain period of operation, the furnace conditions can be observed and the elastic force of the coil spring 60 can be readjusted.

[0031] When the hearth-type combustion device is operated, the side grates 30 retreat outward against the elastic force of the coil springs 60 as the grates 12, 14, and 16 thermally expand in the furnace width direction. At this time, the thermal expansion of the grates 12 (14, 16) is absorbed by the elastic force of the coil springs 60, and the sealing between the grates 12 (14, 16) and the side grates 30 is achieved by the side grates 30 being pressed against the end surfaces of the grates 12 (14, 16) by the elastic force of the coil springs 60.

[0032] In this embodiment, the side grate unit 100 includes a cooling block 70 disposed between the side grate 30 and the movable beam 40 to cool the side grate 30. Furthermore, the side grate unit 100 includes a cooling water supply pipe 76 that supplies cooling water to a cooling water inlet chamber 75, which serves as the lower space formed in the movable beam 40, and a cooling water return pipe 78 that returns the cooling water supplied to the movable beam 40. The cooling water return pipe 78 is connected to a cooling water outlet chamber 77, which serves as the upper space formed in the movable beam 40.

[0033] Furthermore, the cooling block 70 includes at least one cooling water flow path 70a formed within the cooling block 70 and having an inlet connected to a cooling water inlet chamber 75 and an outlet connected to a cooling water outlet chamber 77. Cooling water supplied from the cooling water supply pipe 76 to the cooling water inlet chamber 75 fills the cooling water inlet chamber 75 and then flows into the cooling water flow path 70a. Cooling water passing through the cooling water flow path 70a flows into the cooling water outlet chamber 77, filling the cooling water outlet chamber 77. Cooling water then flows from the cooling water outlet chamber 77 through the cooling water return pipe 78 to the outside of the side grate unit 100. In this embodiment, the cooling water inlet chamber 75 communicates with the cooling water outlet chamber 77 via the cooling water flow path 70a formed in the cooling block 70.

[0034] The cooling blocks 70, cooled by cooling water flowing through the cooling water flow path 70a, exchange heat with the side grates 30 in contact with them, thereby cooling the side grates 30. This maintains the temperature of the side grates 30 during operation below 500°C, particularly below 350°C. As a result, damage to the side grates 30 can be prevented, and their lifespan can be prevented from being shortened due to high temperatures.

[0035] In this embodiment, the side grate unit 30 includes four cooling blocks 70, and each cooling unit 70 includes two cooling water flow paths 70a. However, as long as the side grate 30 can be cooled to a specified temperature or below (e.g., below 500°C, particularly below 350°C), the number of cooling blocks 70 and the number of cooling water flow paths 70a can be arbitrarily selected.

[0036] Furthermore, in this embodiment, the cooling water supplied to the plurality of cooling blocks 70 is temporarily stored in the cooling water inlet chamber 75, while the cooling water discharged from the plurality of cooling blocks 70 is temporarily stored in the cooling water outlet chamber 77. Specifically, the cooling water inlet chamber 75 functions as an inlet buffer zone for the cooling water supplied to the cooling blocks 70, while the cooling water outlet chamber 77 functions as an outlet buffer zone for the cooling water discharged from the cooling blocks 70. By providing these cooling water inlet chambers 75 and cooling water outlet chambers 77, which function as buffer zones, cooling water can be supplied to each cooling water flow path 70a at a uniform flow rate and recovered from each cooling water flow path 70a at a uniform flow rate. As a result, the side grate 30 can be uniformly cooled throughout its entirety.

[0037] In this embodiment, the cooling water inlet chamber 75 is located below the cooling water outlet chamber 77. This structure allows cooling water, heated by heat exchange with the side grates 30, to flow into the cooling water outlet chamber 77, located above the cooling water inlet chamber 75. This prevents the cooling water in the cooling water inlet chamber 75 from being heated by the cooling water in the cooling water outlet chamber 77. As a result, the side grates 30 can be effectively cooled.

[0038] As shown in Figures 4 and 5 , the cooling water supply pipe 76 and the cooling water return pipe 78 extend through the flange 74. Therefore, the side grate unit 100 further includes a sealing member (first sealing member) 88 that seals the gap between the cooling water supply pipe 76 and the flange 74, and a sealing member (second sealing member) 89 that seals the gap between the cooling water return pipe 78 and the flange 74. Seal members 88 and 89 prevent exhaust gas generated within the furnace from leaking out of the side grate unit 100.

[0039] As the side grates 30 and grates 12 (14, 16) advance and retreat relative to the furnace sidewall 10 in response to thermal expansion, the cooling water supply pipe 76 and the cooling water return pipe 78 advance and retreat relative to the flange 74. Therefore, the first sealing member 88 is, for example, a gland packing that allows the cooling water supply pipe 76 to slide and seals the gap between the cooling water supply pipe 76 and the flange 74. Similarly, the second sealing member 89 is, for example, a gland packing that allows the cooling water return pipe 78 to slide and seals the gap between the cooling water return pipe 78 and the flange 74.

[0040] As shown in Figure 4 , the side grate unit 100 may also include a flow regulator (e.g., a mass flow controller) 90 capable of regulating the flow rate of cooling water within the cooling water supply piping 76. The flow regulator 90 is controlled based on, for example, the measurement value of a thermometer 93 (see Figure 2 ) attached to the side grate 30 and measuring the temperature of the operating side grate 30. More specifically, the flow regulator 90 regulates the flow rate of cooling water within the cooling water supply piping 76 so that the temperature of the side grate 30 measured by the thermometer 93 matches a predetermined set temperature.

[0041] Although not shown, the side grate unit 100 may include a thermometer for measuring the temperature of the cooling water in the cooling water supply pipe 76 and a thermometer for measuring the temperature of the cooling water in the cooling water return pipe 78, instead of the thermometer 93. In this case, the flow regulator 90 is controlled based on the difference between the temperature of the cooling water in the cooling water supply pipe 76 and the temperature of the cooling water in the cooling water return pipe 78. In one embodiment, the side grate unit 100 may include only a thermometer for measuring the temperature of the cooling water in the cooling water return pipe 78. In this case, the flow regulator 90 is controlled based on the temperature of the cooling water in the cooling water return pipe 78.

[0042] Fig. 6 is a perspective top view schematically showing a side grate unit of another embodiment. Since the structure of this embodiment not specifically described is the same as that of the above embodiment, its repeated description is omitted.

[0043] The side grate unit 100 of the hearth-type combustion apparatus shown in FIG6 differs from the above-described embodiment in that the cooling block 70 is omitted. Therefore, in this side grate unit 100, the movable beam 40 is directly connected to the side grate 30. The main body 42 of the movable beam 40 is formed with at least one (two in FIG6 ) communication hole 96 that connects the cooling water inlet chamber 75 with the cooling water outlet chamber 77.

[0044] The cooling water flowing from the cooling water supply pipe 76 into the cooling water inlet chamber 75 flows into the cooling water outlet chamber 77 through the communication hole 96 , passes through the cooling water return pipe 78 , and is discharged from the side grate unit 100 .

[0045] Because the movable beam 40, through which cooling water flows, is directly connected to the side grate 30, heat is exchanged between the side grate 30 and the movable beam 40, thereby cooling the side grate 30. The movable beam 40 is fixed to the back of the side grate 30 with a heat-resistant adhesive. As mentioned above, copper powder can also be mixed into the heat-resistant adhesive. In one embodiment, the heat-resistant adhesive can also be a heat-resistant paste.

[0046] The above-described embodiments are described with the goal of enabling those with ordinary skill in the technical field to which the present invention pertains to the implementation of the present invention. Various modifications of the above-described embodiments are readily implementable by those with ordinary skill in the art, and the technical concepts of the present invention are also applicable to other embodiments. Therefore, the present invention is not limited to the described embodiments and should be interpreted within the broadest scope consistent with the technical concepts defined by the claims.

[0047] 10: Furnace side wall 12:Fixed grate 14: Movable grate 16: End grate 18: Fixed frame 20: Hydraulic cylinder 22: Wheels 24: rail 26: Movable frame 28: Scraper 30: Side grate 32: Sealing block 36: Bracket 40: Movable beam 42: Subject 43, 44, 45, 46: Cover parts 52: Support plate 54: Guide tube 56: pipe head (piece) component 58: Adjusting bolt 60: Coil spring (elastic component) 64: Nut 70: Cooling Block 70a: Cooling water flow path 74: flange 75: Cooling water inlet chamber 76: Cooling water supply pipe 77: Cooling water outlet chamber 78: Cooling water return pipe 81, 82: frame structure 88, 89: Sealing parts 90:Flow regulator 93:Thermometer 96: connecting hole

Claims

1. A hearth-type combustion device comprising: at least a pair of side grate units respectively disposed on the inner surface of a furnace sidewall; and a plurality of grates arranged across the pair of side grate units, each side grate unit comprising: a side grate opposite to an end face of the grate; a movable beam disposed along its length on the back side of the side grate and connected to the side grate; an elastic member capable of adjusting its installation position by operation from outside the furnace sidewall; and at least one cooling block disposed between the movable beam and the side grate, the side grate being configured to be freely movable toward and back toward the grate by means of the movable beam and the elastic member, the movable beam comprising: a cooling water inlet chamber connected to a cooling water supply pipe; and a cooling water outlet chamber connected to a cooling water return pipe, the cooling water outlet chamber communicating with the cooling water inlet chamber, the cooling block having at least one cooling water flow path having an inlet communicating with the cooling water inlet chamber and an outlet communicating with the cooling water outlet chamber.

2. The hearth-type combustion device as described in claim 1, wherein, The cooling block is fixed to the back of the side grate using a filler, which contains a substance with a higher thermal conductivity than the filler itself.

3. The hearth-type combustion device as described in claim 1 or 2, wherein, The cooling water inlet chamber and the cooling water outlet chamber extend along the length of the movable beam, covering its entire length.

4. The hearth-type combustion device as described in claim 1, wherein, The cooling water inlet chamber is located below the cooling water outlet chamber.

5. The hearth-type combustion device as described in claim 1, wherein, It also has a flange that secures the side grate unit to the frame structure of the furnace side wall.

6. The hearth-type combustion device as described in claim 5, wherein, The cooling water supply pipe and the cooling water return pipe extend through the flange, and the gap between the flange and the cooling water supply pipe, and the gap between the flange and the cooling water return pipe are respectively sealed by sealing components.

Images