Fire grate and hearth of stoker type incinerator

Abstract

To provide fire grates and a hearth of a stoker type incinerator capable of suppressing useless supply by enabling sufficient supply of combustion air to objects to be incinerated present on a hearth with fire grates arranged.SOLUTION: In fire grates, a base end side is supported, an undersurface of a tip side is brought into contact with a back surface of a fire grate on the downstream side in the conveyance direction of objects to be incinerated, an undersurface of the tip side of a fire grate on the upstream side in the conveyance direction is arranged to be brought into contact with a back surface, and there is formed a hearth of a stoker type incinerator that accepts on the back surface and conveys the objects to be incinerated by relative movement with the fire grate on the upstream or downstream side in the conveyance direction. In the fire grates, combustion air is configured to be supplied from a gap formed by noncontact between the back surface and the lower part of the tip end side of the fire grate on the upstream side in contact with the back surface during the relative movement, and the area of the gap is configured to be continuously or intermittently smaller due to the relative movement of the fire grate on the upstream side from the base end side to the tip side.SELECTED DRAWING: Figure 4

Description

Technical Field

[0001] The present invention relates to a grate and the hearth of a stoker-type incinerator.

Background Art

[0002] Patent Document 1 discloses a grate piece body R that forms a gas flow path for sending combustion gas into a space surrounded by an upper wall 1 and left and right side walls 2, and includes a front end wall 3 connected to the upper wall 1 and the left and right side walls 2. An opening 31 for blowing the combustion gas from the gas flow path to the outside is formed in the front end wall 3. The lower part of the tip of the grate piece body R and the upper wall 1 of the adjacent grate piece body R have a structure of a grate piece that reciprocally slides relative to each other while varying the elevation angle. A swing piece 43 that slides while being in surface contact with the upper wall surface of the adjacent grate piece body is provided at the lower part 32 of the tip of the grate piece body (see FIG. 10(a)).

[0003] Combustion air supplied from below the grate piece through a wind box is blown out from two openings 31, which are round holes formed in the front end wall 3, and the combustion air is supplied to the object to be incinerated on the hearth.

[0004] Patent Document 2 discloses a stepped sliding type stoker in which a fixed grate and a movable grate are alternately arranged in the front-rear direction. Each grate 3 includes a grate body 4 attached to a hearth frame 9, an air passage 5 formed from the rear side to the lower front side of the grate body 4, a sliding body 6 detachably provided on the front side of the grate body 4 and slidably engaged with the upper surface of the front grate body, a nozzle hole 7 formed between the front side of the air passage 5 and an adjacent grate body depending on a groove provided on the side of the grate body 4, and an air outlet 8 formed between the lower front end of the grate body 4 and the upper front end of the sliding body and communicating with the nozzle hole 7. A stepped sliding type stoker characterized by the above is disclosed (see FIG. 10(b)). Note that the reference numerals shown in FIGS. 10(a) and 10(b) are the same as those used in Patent Documents 1 and 2 and have no relation to the reference numerals used in the following embodiments section.

Prior Art Documents

Patent Documents

[0005] [Patent Document 1] JP 2003-97807 A [Patent Document 2] Patent No. 3732670 Summary of the Invention [Problem to be solved by the invention]

[0006] In the grate disclosed in Patent Document 1, combustion air is always blown out from a fixed opening consisting of two round holes formed in the front end wall, i.e., from the same position along the width of the fire bed, which causes the problem that it is difficult to supply combustion air evenly according to the thickness of the material to be incinerated piled up on the fire bed.

[0007] As a result, there was a problem that the materials to be incinerated burned locally in areas where they were thinly piled up, causing the grate temperature to rise due to the radiant heat generated by this, resulting in the grate burning more quickly than other grates.

[0008] The grate disclosed in Patent Document 2 is configured so that combustion air is supplied through wider slits than the grate disclosed in Patent Document 1, but it does not solve the problems of the thickness of the material to be incinerated and the amount of combustion air supplied, or the problem of abnormal localized combustion.

[0009] Incidentally, the waste that is put into an incinerator undergoes a series of incineration processes, including drying, gasification and combustion, and solid combustion, as it is transported from the upstream side to the downstream side of the hearth, which is made up of fire grates. As the incineration process progresses, the waste gradually reduces in volume, and in the downstream area of ​​the combustion zone where the gasification and combustion process progresses, the tip of the fire grate often becomes exposed above the waste layer.

[0010] Figures 8(a) through (g) show the behavior of the waste conveyed with the relative movement of the fixed grate and the movable grate, and the change in the combustion state of the waste. When the layer thickness of the waste is thin as shown in Fig. 8(a), when the movable grate advances, the waste deposited on the back surface of the fixed grate by the tip of the movable grate is pressed and conveyed forward. In this process, the waste deposited on the back surface of the fixed grate burns due to the air supplied from the nozzles on the tip side of the movable grate (see Fig. 8(b)). However, since the waste on the tip side of the fixed grate advances together with the downstream movable grate, air leakage occurs (see Fig. 8(b)), and then new waste is supplied by the upstream movable grate (see Fig. 8(c)).

[0011] After that, when the movable grate retracts, the waste disappears from the back surface of the downstream grate, and air leakage occurs (see Figs. 8(d) and (e)). When it retracts further, it is pressed by the tip of the upstream fixed grate, and new waste is conveyed to the back surface of the downstream grate.

[0012] Fig. 9 shows the deposition state of the waste layer existing at the tip of the movable grate during forward and backward movements. The combustible waste (unburned matter) near the tip of the grate burns out and turns into ash (burned shell) while the movable grate advances. Then, after retracting for a while, the waste (combustible waste and ash) disappears from the tip of the grate and air leakage occurs. However, when the retraction continues further, combustible waste is supplied from the upstream side. Note that the deposition state of the waste layer existing at the tip of the fixed grate is opposite to that of the movable grate.

[0013] In such a state, among the outlets of the combustion air formed at the tip of the grate, the discharge amount of the combustion air from the outlet that is exposed from the waste layer and has a small pressure loss increases, the air supply amount to the waste layer decreases, and combustion unevenness occurs. As a result, there was a problem that low air ratio combustion was impaired and efficient heat recovery in the waste heat boiler was inhibited.

[0014] In view of the above-described conventional problems, an object of the present invention is to provide a grate and a hearth of a stoker-type incinerator that can efficiently supply combustion air to the object to be incinerated existing on the hearth on which the grates are arranged and can suppress wasteful supply.

Means for Solving the Problems

[0015] To achieve the above object, the first characteristic configuration of the grate according to the present invention is that the base end side is supported, and the lower surface of the tip end side abuts against the back surface of the grate on the downstream side in the conveyance direction of the object to be incinerated, and the lower surface of the tip end side of the grate on the upstream side in the conveyance direction abuts against the back surface. It is arranged so as to abut, and forms a hearth of a stoker-type incinerator that receives and conveys the object to be incinerated on the back surface by relative movement with the grate on the upstream side or downstream side in the conveyance direction. A grate, configured such that combustion air is supplied from a gap formed by not abutting between the back surface and the lower part of the tip end side of the upstream grate abutting against the back surface during the relative movement, and along with the relative movement of the upstream grate from the base end side to the tip end side, the area of the gap is configured to continuously and / or intermittently decrease.

[0016] As the tip of the upstream grate moves from the base end side to the tip end side along the back surface of the grate adjacent to the downstream side, combustion air is discharged from a gap formed between the lower surface of the tip end side of the upstream grate and the back surface of the grate adjacent to the downstream side. Since the area of the gap decreases as the lower surface of the tip end side of the upstream grate moves from the base end side to the tip end side of the grate adjacent to the downstream side, the supply amount of combustion air decreases from the base end side to the tip end side of the grate adjacent to the downstream side. That is, the supply amount of combustion air can be ensured at the base end side where the probability of the existence of the garbage layer is high on the back surfaces of the grates adjacent to each other front and back, and the supply amount of combustion air at the tip end side where the probability of the existence of the garbage layer is low is restricted. As a result, combustion air can be efficiently supplied to the object to be incinerated, and wasteful supply can be suppressed.

[0017] In addition to the above-described first characteristic configuration, the second characteristic configuration is such that a reference surface is formed on the back surface to maintain a contact state with the lower surface of the upstream grate during the relative movement, and single or a plurality of recesses forming the gap are continuously formed in a direction along the conveyance direction. The recess includes a displacement region where the formation position of the gap is displaced in the width direction intersecting the conveyance direction as the relative movement occurs.

[0018] The reference surface formed on the back surface of the grate contacts the lower surface of the upstream grate, and a gap is formed between the recess formed in the reference surface and the lower surface of the upstream grate. By forming the recess so as to include a displacement region where the formation position of the gap is displaced in the width direction intersecting the conveyance direction as the grate relatively moves, combustion air is evenly supplied to the object to be incinerated, and the occurrence of local abnormal combustion is effectively suppressed.

[0019] In addition to the above-described second characteristic configuration, the third characteristic configuration is such that the width and / or depth of the recess continuously and / or intermittently changes from the base end side to the tip end side.

[0020] By continuously and / or intermittently changing the width and / or depth of the recess from the base end side to the tip end side, the area of the gap formed between the recess formed in the reference surface and the lower surface of the upstream grate continuously and / or intermittently decreases.

[0021] In addition to the above-described first characteristic configuration, the fourth characteristic configuration is such that a first region with a convex surface protruding above the reference surface and a second region with a concave surface recessed below the reference surface are formed on the back surface so as to switch along the conveyance direction. During the relative movement, in the first region, the convex surface maintains a contact state with the lower surface of the upstream grate, thereby forming the gap between the reference surface and the lower surface of the upstream grate. In the second region, the reference surface maintains a contact state with the lower surface of the upstream grate, thereby forming the gap between the concave surface and the lower surface of the upstream grate.

[0022] Since the gap formed between the reference plane and the lower surface of the upstream grate in the first region and the gap formed between the concave surface and the lower surface of the upstream grate in the second region switch along the conveyance direction, the supply position of the combustion air changes accordingly, and the occurrence of local abnormal combustion is effectively suppressed.

[0023] The fifth characteristic configuration is that, in addition to the fourth characteristic configuration described above, the width and / or height of the convex surface in the first region change continuously and / or intermittently from the base end side to the tip end side, and the width and / or depth of the concave surface in the second region change continuously and / or intermittently from the base end side to the tip end side.

[0024] By changing the width and / or height of the convex surface in the first region from the base end side to the tip end side, the area of the gap becomes continuously and / or intermittently smaller, and by changing the width and / or depth of the concave surface in the second region from the base end side to the tip end side continuously and / or intermittently, the area of the gap becomes continuously and / or intermittently smaller.

[0025] The characteristic configuration of the furnace bed of the stoker-type incinerator according to the present invention is that the grates having any one of the first to fifth characteristic configurations described above are arranged and formed in the conveyance direction and the direction intersecting the conveyance direction.

[0026] Combustion air is evenly supplied to the waste to be incinerated in the furnace bed, and the supply of wasted combustion air in the region where the waste becomes thinner due to the incineration process is suppressed.

Effects of the Invention

[0027] As described above, according to the present invention, it has become possible to provide a grate and a furnace bed of a stoker-type incinerator that can efficiently supply combustion air to the waste present on the furnace bed where the grates are arranged and can suppress wasted supply.

Brief Description of the Drawings

[0028]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Figure 10

Mode for Carrying Out the Invention

[0029] An example of the furnace floor of a stoker-type incinerator and the grate forming the furnace floor will be described below with reference to the drawings.

[0030] Fig. 1 shows an example of the furnace chamber of a stoker-type incinerator 100. The furnace chamber is covered with a refractory wall W and includes a furnace floor B configured by a stoker mechanism provided with a plurality of grates 10. Combustion air supplied from a forced draft fan to a wind box installed below the furnace floor B is configured to be supplied to the garbage, which is the material to be incinerated, on the furnace floor B through the grates 10.

[0031] Each grate 10 includes a fixed grate group 10A whose base end is swingably supported by a cylindrical support rod C1 horizontally mounted on a fixed frame C, and a movable grate group 10B whose base end is swingably supported by a cylindrical support rod D1 horizontally mounted on a movable frame D that reciprocates along the waste conveyance direction with respect to the fixed frame C. The fixed grate group 10A and the movable grate group 10B are alternately arranged along the waste conveyance direction. A plurality of grate groups 10A, 10B arranged side by side in the width direction are sandwiched by a pair of side plates disposed on both side portions of the furnace chamber, and the side plates are pressed by springs from the outside toward the center direction.

[0032] When the movable frame D is reciprocally driven by a hydraulic mechanism E, the movable grate group 10B and the fixed grate group 10A relatively move along the waste conveyance direction, and the waste to be incinerated on the furnace floor B is conveyed downstream while being agitated.

[0033] A combustion burner is provided in the ceiling portion of the furnace chamber, which is used for raising the temperature inside the furnace during furnace startup. When the calorific value of the waste is low, the waste to be incinerated on the furnace floor B is burned while being agitated and conveyed by the heat of the combustion burner.

[0034] In FIG. 1, a main combustion zone mainly for gasification combustion is formed by the central furnace floor B, and furnace floors are separately provided on the upstream side and the downstream side. A drying zone mainly for drying the waste to be incinerated is formed by the upstream furnace floor Bu, and a post-combustion zone for ashing the solid matter after gasification combustion is formed by the downstream furnace floor Bd. Note that the upstream furnace floor Bu and the central furnace floor B may be integrally formed.

[0035] Each grate 10 constituting each of the above-described furnace floors Bu, B, and Bd is shown in FIGS. 2 to 4. Each grate 10 is composed of a casting having a substantially rectangular parallelepiped shape with an open bottom, and includes left and right side walls 11, 12, an upper wall 13 (in the following description, the upper surface of the upper wall is also referred to as "rear surface 13"), and a front end wall 14. Further, three arcuate locking claws 15 are formed on the base end side in the direction opposite to the front end wall 14. Inside the rear surface 13, three reinforcing ribs 16 that also function as cooling fins are formed.

[0036] The tip side of the back surface 13 is bent with a predetermined curvature and is continuous with the front end wall 14, and the lower edge portion of the front end wall 14 is formed in a straight line. The left and right side walls 11, 12 continuous with the front end wall 14 are formed as inclined walls where the lower end side of the outer surface is slightly inclined inward. A front end bottom wall 17 continuous with the lower end of the front end wall 14 is formed on the tip side of the bottom. The front end bottom wall 17 becomes the lower surface that contacts the back surface 13 of the grate 10 on the downstream side in the conveyance direction of the object to be incinerated.

[0037] In FIG. 1, an example is shown in which the surface enclosing the tip of each grate 10 is in a horizontal posture, but the enclosing surface may be configured to be inclined along the conveyance direction of the object to be incinerated. For example, it may be configured to be inclined downward along the conveyance direction of the object to be incinerated.

[0038] Further, on the upper edge portion of the grate 10 among the left and right side walls 11, 12, an overhanging portion 18 in which a flat surface with a predetermined width protrudes outward in the width direction is formed. Further, among the left and right side walls 11, 12, insertion holes H, H for connecting adjacent grates 10 are formed at positions about 1 / 3 from the tip side and the base end side along the longitudinal direction of the grate 10.

[0039] Bolts and nuts are preferably used as the connecting fittings. After inserting bolts through the respective insertion holes H of adjacent grates 10 and tightening them with nuts, the bolts and nuts are welded and fixed in a slightly loosened state, so that there is a slight play between adjacent grates 10. Note that a predetermined number (3 to 4 in this embodiment) of grates among the grates adjacent in the width direction are connected to each other with bolts and nuts as a unit.

[0040] In this way, a plurality of grates 10 are arranged adjacent to each other in the width direction of the furnace chamber, and the locking claws 15 on the base end side are swingably engaged with the support rod C1 of the fixed frame C or the support rod D1 of the movable frame D (see FIG. 1), so that each grate 10 is swingably supported around the support rods C1, D1. The grate 10 supported by the support rod C1 becomes a fixed grate, and the grate 10 supported by the support rod D1 becomes a movable grate.

[0041] Figure 4 shows a state in which the front end side of the grate 10U located upstream in the conveying direction of the material to be incinerated, that is, the lower end of the front end wall 14 and the front end bottom wall 17 (shown by the semi-transparent rectangular area surrounded by the dashed-dotted line in the figure), abuts against the back surface 13 of the grate 10D on the downstream side in the conveying direction of the material to be incinerated. As the grates 10U and 10D move relative to each other, the front end bottom wall 17 of the upstream grate 10U reciprocates in the conveying direction of the material to be incinerated on the upper part of the back surface 13 of the downstream grate 10D.

[0042] As shown in Fig. 2(a), Fig. 3(a), (b), and Fig. 4, on the back surface 13 of each grate 10, a reference surface 13R is formed to maintain the abutting state with the front end bottom wall 17 of the upstream grate 10 when each grate 10 moves relatively, and a recess 13D that forms an air supply port G serving as a gap for supplying combustion air between the front end bottom wall 17 of the upstream grate 10 is continuously formed in a direction along the conveying direction of the material to be incinerated.

[0043] The recess 13D is a flat surface recessed from the reference surface 13R and has a groove structure formed on an inclined surface whose recess depth gradually decreases from the base end side to the tip end side, and includes a displacement region 13A in which the formation position of the air supply port G continuously displaces in the width direction intersecting the conveying direction as the grate 10 moves relatively.

[0044] Details will be described based on Fig. 4. The state where the front end bottom wall 17 (the dashed-dotted line indicated by the reference numeral 17), which is the lower surface of the upstream grate 10U, is located at the base end side of the downstream grate 10D is shown in the left figure of Fig. 4(a). The state where the front end bottom wall 17 is located at the central part of the downstream grate 10D is shown in the left figure of Fig. 4(b). The state where the front end bottom wall 17 is located at the tip end side of the downstream grate 10D is shown in the left figure of Fig. 4(c). The positions of the air supply ports G formed correspondingly are shown in the right figures.

[0045] In the present embodiment, the displacement region 13A is formed at the longitudinal center of the grate 10, and the recesses 13D are formed on both sides in the width direction on the proximal end side of the grate 10 with the displacement region 13A interposed therebetween, and are formed at the center in the width direction on the distal end side of the grate 10, and are continuously formed in a direction along the conveyance direction of the object to be incinerated.

[0046] In the right figure of Fig. 4(a), the air supply port G formed on the proximal end side of the displacement region 13A of the grate 10U is indicated by a thick line. In the right figure of Fig. 4(b), the air supply port G formed in the displacement region 13A of the grate 10U is indicated by a thick line. In the right figure of Fig. 4(c), the air supply port G formed on the distal end side of the displacement region 13A of the grate 10U is indicated by a thick line. The total length in the width direction of each thick line is constant, but the length in the height direction is long on the proximal end side and short on the distal end side. That is, it is shown that the recess 13D is formed such that the opening area of the air supply port G formed as the grate 10 moves decreases from the proximal end side to the distal end side.

[0047] When the front end bottom wall 17, which is the lower surface on the distal end side of the upstream grate, passes through the displacement region 13A as the two grates 10 move relative to each other, the formation position of the air supply port G continuously displaces in the width direction intersecting the conveyance direction. Accordingly, combustion air is uniformly supplied from the air supply port G to the object to be incinerated as a whole, and the occurrence of local abnormal combustion is effectively suppressed.

[0048] Furthermore, as the upstream grate 10U moves from the proximal end side to the distal end side, the area of the gap serving as the air supply port G is configured to continuously decrease, so the supply amount of combustion air decreases from the proximal end side to the distal end side of the downstream adjacent grate 10D.

[0049] That is, on the downstream side of the combustion zone where the thickness of the garbage layer tends to be thin, the supply amount of combustion air at the proximal end side where the probability of the presence of the garbage layer is relatively high on the back surfaces of the adjacent grates 10U and 10D can be ensured, and the supply amount of combustion air at the distal end side where the probability of the presence of the garbage layer is relatively low is restricted. As a result, combustion air can be efficiently supplied to the object to be incinerated, and wasteful supply can be suppressed.

[0050] Incidentally, the area of the gap serving as the air supply port G may be configured to decrease intermittently as the upstream grate moves from the proximal end side to the distal end side. For this purpose, it is sufficient that the width and / or depth of the recess 13D is configured to change continuously and / or intermittently from the proximal end side to the distal end side.

[0051] In other words, the grate 10 is configured such that combustion air is supplied from a gap formed by not contacting the lower part of the distal end side of the upstream grate that contacts the back surface during relative movement. As the upstream grate moves from the proximal end side to the distal end side, the area of the gap is configured to decrease continuously and / or intermittently.

[0052] Fig. 5(a) shows a pair of grates 10 in which the reference surface 13R formed on the back surface 13 of the grate 10 and the shape of the recess 13D are inverted and symmetric. As shown in Fig. 5(b), by alternately arranging the pair of grates 10 along the conveying direction of the object to be incinerated, it may be possible to supply combustion air uniformly to the object to be incinerated over the entire furnace floor.

[0053] Figs. 6(a) to (g) show the patterns in plan view of the recesses 13D formed in the above-described grate. In each case, it is provided with one or a plurality of recesses 13D formed such that the depth continuously or stepwise becomes shallower from the proximal end side to the distal end side of the grate, or the width of the recess 13D continuously or stepwise becomes narrower from the proximal end side to the distal end side of the grate.

[0054] For each of the grates in Figs. 6(b) to 6(g), in the same manner as the embodiment described with reference to Figs. 5(a) and (b), a pair of grates 10 in which the shape of the reference surface 13R and the recess 13D are inverted and symmetric is configured, and by alternately arranging the pair of grates 10 along the conveying direction of the object to be incinerated, it may be possible to supply combustion air uniformly to the object to be incinerated over the entire furnace floor.

[0055] Figures 7(a) and (b) show still another embodiment. On the back surface 13 of the fire grate 10, a first region in which a convex surface 13H protruding above the reference plane 13R is formed and a second region in which a concave surface 13L recessed below the reference plane 13R is formed are formed so as to switch along the conveyance direction.

[0056] When the fire grate 10 moves relatively, by maintaining a contact state between the convex surface 13H in the first region and the front end bottom wall 17 which is the lower surface of the upstream fire grate 10U, an air supply port is formed as a gap between the reference plane 13R and the front end bottom wall 17 which is the lower front of the upstream fire grate 10U. By maintaining a contact state between the reference plane 13R and the front end bottom wall 17 which is the lower surface of the upstream fire grate 10U in the second region, an air supply port is formed as a gap between the concave surface 13L and the front end bottom wall 17 which is the lower surface of the upstream fire grate 10U.

[0057] Since the gap formed between the reference plane and the lower surface of the upstream fire grate in the first region and the gap formed between the concave surface and the lower surface of the upstream fire grate in the second region switch along the conveyance direction, accordingly, the supply site of the combustion air changes, and the occurrence of local abnormal combustion is effectively suppressed.

[0058] And, in the first region, the width and / or height of the convex surface 13H change continuously and / or intermittently from the base end side to the tip end side, and in the second region, the width and / or depth of the concave surface 13L change continuously and / or intermittently from the base end side to the tip end side, so that the area of the gap is configured to become continuously and / or intermittently smaller.

[0059] All of the fire grates described above are air-cooled fire grates cooled using heat dissipation fins, but it goes without saying that the present invention is also applicable to a water-cooled fire grate in which a passage for cooling water is formed inside.

[0060] Incidentally, the above-described embodiment is merely an example of the present invention, and it goes without saying that the specific structure, shape, material, size, etc. of each part can be appropriately changed and designed within the range in which the operational effects of the present invention are exhibited.

Explanation of Symbols

[0061] 10: Fire grate 10A: Fixed fire grate group 10B: Movable fire grate group 10U: Upstream fire grate 10D: Downstream fire grate 11, 12: Side walls 13: Back surface (upper wall) 13D: Recess 13R: Reference plane 13A: Displacement region 14: Front end wall 16: Reinforcing rib 17: Front end bottom wall (lower surface) 100: Stoker-type incinerator B: Hearth (combustion zone) Bu: Hearth (drying zone) Bd: Hearth (afterburning zone) C: Fixed frame C C1: Support rod D: Movable frame D1: Support rod G: Air supply port (gap) H: Insertion hole

Claims

1. A grate that forms the hearth of a stoker-type incinerator. The base end side is supported, and the lower surface of the tip end side abuts against the back surface of the grate on the downstream side in the conveyance direction of the object to be incinerated. The lower surface of the tip end side of the grate on the upstream side in the conveyance direction abuts against the back surface. The grate is configured such that combustion air is supplied from a gap formed by not abutting between the back surface and the lower part of the tip end side of the upstream grate that abuts against the back surface during the relative movement, and the area of the gap is configured to continuously and / or intermittently decrease as the upstream grate moves relative to the grate on the upstream or downstream side in the conveyance direction from the base end side to the tip end side. The grate is configured such that combustion air is supplied from a gap formed by not abutting between the back surface and the lower part of the tip end side of the upstream grate that abuts against the back surface during the relative movement. The grate is configured such that the area of the gap continuously and / or intermittently decreases as the upstream grate moves relative to the grate on the upstream or downstream side in the conveyance direction from the base end side to the tip end side.

2. A reference surface is formed on the back surface to maintain an abutting state with the lower surface of the upstream grate during the relative movement. A single or a plurality of recesses that form the gap are continuously formed along the conveyance direction on the reference surface. The grate according to claim 1, wherein the recesses include a displacement region in which the formation position of the gap is displaced in the width direction intersecting the conveyance direction as the relative movement occurs.

3. The grate according to claim 2, wherein the width and / or depth of the recess continuously and / or intermittently change from the base end side to the tip end side.

4. A first region with a convex surface protruding above the reference surface and a second region with a concave surface recessed below the reference surface are formed on the back surface so as to switch along the conveyance direction. During the relative movement, in the first region, the convex surface maintains an abutting state with the lower surface of the upstream grate, so that a gap is formed between the reference surface and the lower surface of the upstream grate. In the second region, the reference surface maintains an abutting state with the lower surface of the upstream grate, so that a gap is formed between the concave surface and the lower surface of the upstream grate. The grate according to claim 1.

5. The grate according to claim 4, wherein in the first region, the width and / or height of the convex surface change from the base end side to the tip end side, and in the second region, the width and / or depth of the concave surface continuously and / or intermittently change from the base end side to the tip end side.

6. The furnace floor of the stoker-type incinerator in which the fire grates according to any one of claims 1 to 5 are arranged in the conveying direction and the direction intersecting the conveying direction.

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