JP6090578B2 - Waste incinerator and waste incineration method - Google Patents

Description

  The present invention relates to a grate-type waste incinerator and a waste incineration method for incinerating waste such as municipal waste.

  Grate-type waste incinerators are widely used as incinerators for incinerating waste such as municipal waste. The outline of the configuration of the representative one will be described below.

  The grate-type waste incinerator has a three-stage grate (dry grate, combustion grate, and post-combustion grate) that is arranged in the direction of waste movement at the bottom of the combustion chamber that burns the waste. The secondary combustion chamber is connected to the outlet of the combustion chamber located above the post-combustion grate. The combustion chamber is provided with a waste inlet located above the dry grate. An ash drop port is provided at the downstream side of the post-combustion grate waste in the moving direction. Usually, the secondary combustion chamber is also a part of a waste heat boiler for waste heat recovery, and is in the vicinity of the inlet. Further, a combustion primary air blowing mechanism for blowing combustion primary air from below the grate of each of the dry grate, the combustion grate, and the post-combustion grate is provided.

  In such a grate-type waste incinerator, waste thrown into the combustion chamber from the waste inlet is deposited on the dry grate and dried by air from the bottom of the dry grate and radiant heat in the furnace. At the same time, the temperature is raised and ignition occurs. That is, immediately above the dry grate, a dry region is formed in the upstream space in the waste movement direction, and combustion occurs from the downstream space directly above the dry grate to the upstream space directly above the combustion grate. A starting region is formed. The waste that ignites in the combustion start area and starts combustion is sent from the dry grate onto the combustion grate, and the waste is pyrolyzed to generate combustible gas, and the combustion sent from the bottom of the combustion grate The primary air for combustion burns combustible gas and solid content, and a main combustion region is formed in the space immediately above the combustion grate. Further, unburned components such as fixed carbon are completely burned on the post-combustion grate, and a post-combustion region is formed in a space immediately above the post-combustion grate. Thereafter, the ash remaining after combustion is discharged to the outside from the ash drop opening.

  Thus, in the grate-type waste incinerator, the waste is burned by the primary combustion air blown from below the three-stage grate in the combustion chamber. Further, the unburned portion of the combustible gas contained in the combustion exhaust gas from the combustion chamber receives and burns secondary combustion air in the secondary combustion chamber.

  In a conventional grate-type waste incinerator, the ratio (air ratio) obtained by dividing the amount of air actually supplied into the incinerator by the theoretical amount of air necessary for combustion of the waste is usually about 1.6. . This is larger than 1.05 to 1.2 which is an air ratio necessary for combustion of general fuel. The reason for this is that waste has a higher incombustibility than liquid fuel or gaseous fuel as a general fuel and is inhomogeneous, so the efficiency of air utilization is low, and a large amount of air is required for combustion. It is to become. However, if the supply air is simply increased, the amount of exhaust gas increases as the air ratio increases, and accordingly, a larger exhaust gas treatment facility is required.

  If waste can be burned without any problems in a waste incinerator with a reduced air ratio, the amount of exhaust gas will be reduced, and the exhaust gas treatment facility will become compact. As a result, the entire waste incineration facility will be downsized. Equipment costs can be reduced. In addition, since the amount of chemicals used for exhaust gas treatment is reduced, the operating cost can be reduced. Furthermore, since the heat recovery rate of the waste heat boiler can be improved by reducing the amount of exhaust gas, the amount of heat that can not be recovered and discarded to the atmosphere is reduced, and the efficiency of power generation using waste incineration waste heat is reduced accordingly. Can be raised.

  Thus, the advantage of performing the low air ratio combustion is great, but on the other hand, the low air ratio combustion with the air ratio of 1.5 or less causes a problem that the combustion becomes unstable. In other words, when waste is burned at a low air ratio, combustion becomes unstable, CO generation increases, flame temperature rises locally, NOx increases rapidly, and soot is generated in large quantities. As a result, there is a problem that harmful substances in the exhaust gas increase, and waste and ash melt and adhere to the furnace wall due to local high temperatures, and clinker is generated, and the refractory life of the furnace wall is shortened. There is a problem of becoming.

  Under such circumstances, a waste incinerator capable of stably burning at a low air ratio of 1.5 or less has been studied and disclosed in Patent Document 1 (Patent Document 1) 1). In Patent Document 1, after discharging high temperature exhaust gas from the outlet side of the secondary combustion region of the waste incinerator and removing dust, it is mixed with air and blown into the combustion chamber as a high temperature gas (paragraph 0013). (Paragraph 0063).

  That is, promoting the thermal decomposition of waste by sensible heat and radiation of high temperature gas, accelerating the combustion of combustible gas generated by thermal decomposition of waste by blowing high temperature gas containing oxygen, Of the gas in the furnace is promoted by blowing air, and high-temperature gas is blown into the combustion chamber from a nozzle provided on the side wall of the combustion chamber (paragraph 0040). The flow of this high-temperature gas and combustible gas generated from waste And a rising flow of combustion gas collide to form a stagnation region where the flow is slow immediately above the waste layer, so that a planar combustion region is established, from which the radiation to the waste layer increases and is discarded. There is an effect such as promoting thermal decomposition of materials, and by blowing high temperature gas into the combustion chamber, it is said that the combustion of waste can be stably performed under a low air ratio combustion operation. In addition, the combustion of combustible gas generated by thermal decomposition of wastes is stably performed to suppress incomplete combustion, local high temperature generation, etc., and harmful substances such as CO and NOx generated by combustion It is said that the amount of generation can be suppressed.

JP 2004-84981 A

  In the waste incinerator disclosed in Patent Document 1, high-temperature gas is blown into the combustion chamber from a nozzle provided on the combustion chamber side wall. Depending on the state of the waste supplied to the waste incinerator, or in the case of an incinerator with a wide combustion chamber width (width in the direction perpendicular to the direction of movement of the waste on the grate), from the side wall The hot gas blown in does not reach the vicinity of the center of the combustion chamber, and the above effect is exerted evenly over the entire combustion chamber from the vicinity of the side wall to the center, and from the waste layer under the low air ratio combustion operation. It may not always be possible to stably combust the generated combustible gas.

  In view of such circumstances, the present invention is not limited to the size of the incinerator, regardless of the state of waste supplied to the waste incinerator, even when a low air ratio combustion operation with an air ratio of 1.5 or less is performed. Regardless of the size, the combustion of the waste can be performed stably throughout the combustion chamber, the generation amount of harmful substances such as CO and NOx can be suppressed, and the low air ratio combustion operation can be performed without any problems. It is an object to provide a simple grate-type waste incinerator and a waste incineration method.

  According to the present invention, the above-mentioned problems are solved by the following first to fourth inventions for the grate-type waste combustion furnace and the fifth to eighth inventions for the waste incineration method.

<Grate-type waste incinerator>
(1) 1st invention The grate-type waste incinerator which concerns on 1st invention is a grate-type waste incinerator, Comprising: The combustion chamber which comprises a grate and burns the waste on this grate, and combustion Primary air blowing means for blowing the primary air from below the grate into the combustion chamber; and hot gas blowing means for blowing high temperature gas downward from the ceiling of the combustion chamber, and the high temperature gas blowing means Is a two-stage high-temperature gas inlet in the first and second stages in the furnace length direction, which is the moving direction of waste on the grate, and a first-stage high-temperature gas supply means for supplying the first-stage high-temperature gas to the first-stage high-temperature gas inlet, And a post-stage hot gas supply means for supplying the post-stage hot gas to the post-stage hot gas inlet, and the pre-stage hot gas inlet is located at a position where the pre-stage hot gas is blown toward the region from the combustion start region to the main combustion region. The rear hot gas inlet is The high-temperature gas supply means and the high-temperature gas supply means are disposed from the combustion start area to the main combustion area. It is characterized in that at least one of the respective flow rates and oxygen concentrations of the front-stage high-temperature gas and the rear-stage high-temperature gas is controlled so that the oxygen concentration in the previous region is lower than the oxygen concentration in the rear-combustion region. Here, the “burn-out point” is a point where combustion with a flame ends.

(2) Second invention A grate-type waste incinerator according to the second invention is a grate-type waste incinerator, comprising a combustion chamber for burning waste on the grate, and a combustion chamber Primary air blowing means for blowing the primary air from below the grate into the combustion chamber; and hot gas blowing means for blowing high temperature gas downward from the ceiling of the combustion chamber, and the high temperature gas blowing means Is a two-stage high-temperature gas inlet in the first and second stages in the furnace length direction, which is the moving direction of waste on the grate, and a first-stage high-temperature gas supply means for supplying the first-stage high-temperature gas to the first-stage high-temperature gas inlet, And a post-stage hot gas supply means for supplying the post-stage hot gas to the post-stage hot gas inlet, and the pre-stage hot gas inlet is located at a position where the pre-stage hot gas is blown toward the region from the combustion start region to the main combustion region. The rear hot gas inlet is The high-temperature gas supply means and the high-temperature gas supply means are disposed from the combustion start area to the main combustion area. At least one of the flow rates and oxygen concentrations of the front-stage hot gas and the rear-stage hot gas so that the oxygen concentration in the region up to 0 to 2 dry volume% and the oxygen concentration in the rear combustion region to 5 to 8 dry volume% It is characterized by controlling.

(3) Third invention A grate-type waste incinerator according to the third invention is a grate-type waste incinerator, comprising a combustion chamber for burning waste on the grate, and a combustion chamber Primary air blowing means for blowing the primary air from below the grate into the combustion chamber; and hot gas blowing means for blowing high temperature gas downward from the ceiling of the combustion chamber, and the high temperature gas blowing means Is a two-stage high-temperature gas inlet in the first and second stages in the furnace length direction, which is the moving direction of waste on the grate, and a first-stage high-temperature gas supply means for supplying the first-stage high-temperature gas to the first-stage high-temperature gas inlet, A rear-stage high-temperature gas supply means for supplying a rear-stage high-temperature gas to the rear-stage high-temperature gas inlet, and the front-stage high-temperature gas inlet is provided on the ceiling from the rear of the drying stage grate to the rear of the combustion stage grate, The rear hot gas inlet is behind the rear of the combustion stage grate Provided on the ceiling up to the front of the combustion stage grate, the upstream hot gas supply means and the downstream hot gas supply means determine the oxygen concentration in the area from the combustion start area to the main combustion area, It is characterized in that at least one of the respective flow rates and oxygen concentrations of the front-stage hot gas and the rear-stage hot gas is controlled so as to be lower than the concentration.

(4) Fourth invention A grate-type waste incinerator according to the fourth invention is a grate-type waste incinerator, comprising a combustion chamber for burning waste on the grate, and a combustion chamber Primary air blowing means for blowing the primary air from below the grate into the combustion chamber; and hot gas blowing means for blowing high temperature gas downward from the ceiling of the combustion chamber, and the high temperature gas blowing means Is a two-stage high-temperature gas inlet in the first and second stages in the furnace length direction, which is the moving direction of waste on the grate, and a first-stage high-temperature gas supply means for supplying the first-stage high-temperature gas to the first-stage high-temperature gas inlet, A rear-stage high-temperature gas supply means for supplying a rear-stage high-temperature gas to the rear-stage high-temperature gas inlet, and the front-stage high-temperature gas inlet is provided on the ceiling from the rear of the drying stage grate to the rear of the combustion stage grate, The rear hot gas inlet is behind the rear of the combustion stage grate Provided on the ceiling to the front of the combustion stage grate, the upstream hot gas supply means and the downstream hot gas supply means have an oxygen concentration of 0 to 2 dry volume% in the region from the combustion start region to the main combustion region. Further, at least one of the flow rate and the oxygen concentration of each of the upstream high-temperature gas and the downstream high-temperature gas is controlled so that the oxygen concentration in the post-combustion region is 5 to 8 dry volume%.

  In the present invention, in the first to fourth inventions, the first stage high temperature gas supply means uses a mixed gas or high temperature air of the return exhaust gas and the high temperature air to which a part of the exhaust gas discharged from the incinerator is returned as the first stage high temperature gas. It is preferable that the latter stage high temperature gas supply means supplies the return exhaust gas or the mixed gas of the return exhaust gas and the high temperature air as the rear stage high temperature gas.

  In the present invention, in the first to fourth inventions, the upstream hot gas supply means controls the oxygen concentration of the upstream hot gas to 12 to 21 dry volume%, and the downstream hot gas supply means sets the oxygen concentration of the downstream hot gas to 1 It is preferable to control to ~ 12dry volume%.

  In the present invention, in the first to fourth inventions, a secondary combustion chamber for secondary combustion of the gas discharged from the combustion chamber is provided, and the upstream hot gas supply means discharges the flow rate of the upstream hot gas from the secondary combustion chamber. It is preferable to control the exhaust gas amount to 6 to 18%, and the latter-stage hot gas supply means controls the flow rate of the latter-stage hot gas to 15 to 30% of the exhaust gas amount discharged from the secondary combustion chamber.

In the present invention, in the first to fourth inventions, the pre-stage hot gas supply means controls the hot gas blowing flow rate to be in a range represented by the following equation (1) in relation to the combustion chamber height. Then, it is preferable that the latter stage hot gas supply means adjust the hot gas blowing flow rate so as to be within a range represented by the following equation (2) in relation to the combustion chamber height.
0.0069X−1.3 ≦ Y ≦ 0.0153X−0.6 (1)
0.018X−1.0 ≦ Y ≦ 0.022X−0.4 (2)
Where X: combustion chamber height (mm)
Y: Hot gas blowing flow rate (m / sec)

  In the present invention, in the first or third invention, the upstream high temperature gas supply means and the downstream high temperature gas supply means have a lower oxygen concentration in the region from the combustion start region to the main combustion region than the oxygen concentration in the post combustion region. As described above, instead of controlling at least one of the flow rate and the oxygen concentration of each of the upstream hot gas and the downstream hot gas, the primary air for combustion and the hot gas blowing means are blown by the primary air blowing means. Regarding the air ratio of each region obtained by dividing the amount of air actually supplied into the furnace combined with the high-temperature gas by the theoretical amount of air required for combustion of waste, the pre-stage high-temperature gas supply means and the post-stage high-temperature gas supply The flow rate of each of the upstream hot gas and the downstream hot gas so that the means lowers the local air ratio in the region from the combustion start region to the main combustion region compared to the local air ratio in the post combustion region. It may control at least one of fine oxygen concentration.

  In the present invention, in the second or fourth invention, the front-stage high-temperature gas supply means and the rear-stage high-temperature gas supply means have an oxygen concentration of 0 to 2 dry volume% in the region from the combustion start region to the main combustion region, Instead of controlling at least one of the flow rate and the oxygen concentration of the front-stage hot gas and the rear-stage hot gas so that the oxygen concentration is 5 to 8 dry volume%, the primary air for combustion blown by the primary air blowing means The air ratio of each region obtained by dividing the amount of air actually supplied into the furnace by combining the hot gas blown by the hot gas blowing means with the theoretical air amount necessary for the combustion of waste The high-temperature gas supply means and the post-stage high-temperature gas supply means have a local air ratio in the region from the combustion start region to the main combustion region of 0.6 to 0.8, and a local air ratio in the post-combustion region of 1.3 to 1. 6 In may control at least one of each of the flow rate and oxygen concentration of the pre-stage hot gas and subsequent hot gas.

<Grate-type waste incineration method>
(5) Fifth Invention A waste incineration method according to the fifth invention is a waste incineration method using a grate-type waste incinerator provided with a combustion chamber, wherein primary combustion air is introduced from below the grate into the combustion chamber. Of the high-temperature gas injection ports provided in the first stage and the second stage in the furnace length direction, which is the direction of movement of waste on the grate, into the ceiling of the combustion chamber, from the high-temperature gas injection port of the previous stage, From the combustion start area to the main combustion area, and the rear stage hot gas is blown from the rear stage hot gas inlet toward the front part of the rear combustion area or the area immediately after the burnout point, and the combustion start area. To control at least one of the flow rate and the oxygen concentration of each of the front-stage hot gas and the rear-stage hot gas so that the oxygen concentration in the region from the main combustion region to the main combustion region is lower than the oxygen concentration in the rear combustion region. It is a feature.

(6) Sixth Invention A waste incineration method according to the sixth invention is a waste incineration method using a grate-type waste incinerator provided with a combustion chamber, wherein primary combustion air is introduced from below the grate into the combustion chamber. Of the high-temperature gas injection ports provided in the first stage and the second stage in the furnace length direction, which is the direction of movement of waste on the grate, into the ceiling of the combustion chamber, from the high-temperature gas injection port of the previous stage, From the combustion start area to the main combustion area, and the rear stage hot gas is blown from the rear stage hot gas inlet toward the front part of the rear combustion area or the area immediately after the burnout point, and the combustion start area. The flow rate and oxygen concentration of the front-stage hot gas and the rear-stage hot gas are adjusted so that the oxygen concentration in the region from the main combustion region to 0-2 dry volume% and the oxygen concentration in the post-combustion region is 5-8 dry volume%. Control at least one of them It is characterized by that.

(7) Seventh Invention A waste incineration method according to the seventh invention is a waste incineration method using a grate-type waste incinerator provided with a combustion chamber, wherein primary combustion air is introduced from below the grate into the combustion chamber. The combustion stage grate from the rear part of the drying stage grate out of the hot gas inlet provided in the front and rear stages in the furnace length direction, which is the direction of movement of waste on the grate, into the ceiling of the combustion chamber High temperature of the rear stage disposed on the ceiling from the rear part of the combustion stage grate to the front part of the rear combustion stage grate by blowing the front high temperature gas downward from the front high temperature gas inlet port arranged on the ceiling until Each of the front-stage hot gas and the rear-stage hot gas is blown downward from the gas inlet so that the oxygen concentration in the region from the combustion start region to the main combustion region is lower than the oxygen concentration in the post-combustion region. Less than the flow rate and oxygen concentration Both are characterized by controlling one.

(8) Eighth Invention A waste incineration method according to the eighth invention is a waste incineration method using a grate-type waste incinerator equipped with a combustion chamber, wherein primary air for combustion is introduced from below the grate into the combustion chamber. The combustion stage grate from the rear part of the drying stage grate out of the hot gas inlet provided in the front and rear stages in the furnace length direction, which is the direction of movement of waste on the grate, into the ceiling of the combustion chamber High temperature of the rear stage disposed on the ceiling from the rear part of the combustion stage grate to the front part of the rear combustion stage grate by blowing the front high temperature gas downward from the front high temperature gas inlet port arranged on the ceiling until The rear stage high temperature gas is blown downward from the gas inlet, the oxygen concentration in the region from the combustion start region to the main combustion region is 0 to 2 dry volume%, and the oxygen concentration in the post combustion region is 5 to 8 dry volume%. Each flow rate of upstream hot gas and downstream hot gas And at least one of oxygen concentration is controlled.

  In the present invention, in the fifth to eighth inventions, a mixed gas or high-temperature air of return exhaust gas and high-temperature air to which a part of the exhaust gas discharged from the incinerator is returned is blown as a pre-stage high-temperature gas, and the return exhaust gas and high-temperature air It is preferable to blow in a mixed gas or return exhaust gas as a post-stage high-temperature gas.

  In the present invention, in the fifth to eighth inventions, it is preferable to control the oxygen concentration of the upstream high temperature gas to 12 to 21 dry volume% and to control the oxygen concentration of the downstream high temperature gas to 1 to 12 dry volume%.

  In the present invention, in the fifth to eighth inventions, the grate-type waste incinerator includes a secondary combustion chamber for secondary combustion of the gas discharged from the combustion chamber, and the upstream high temperature gas blown from the upstream high temperature gas inlet The gas flow rate is adjusted to 6 to 18% of the amount of exhaust gas discharged from the secondary combustion chamber, and the flow rate of the latter stage hot gas blown from the latter stage hot gas inlet is 15 to 15% of the amount of exhaust gas discharged from the secondary combustion chamber. It is preferable to adjust to 30%.

In the present invention, in the fifth to eighth inventions, the flow velocity of the hot gas blown from the previous hot gas blower inlet is set within the range represented by the following equation (3) in relation to the combustion chamber height. It is preferable to adjust and adjust the flow rate of the hot gas blown from the hot gas blower port at the subsequent stage so as to be within the range represented by the following equation (4) in relation to the combustion chamber height.
0.0069X−1.3 ≦ Y ≦ 0.0153X−0.6 (3)
0.018X−1.0 ≦ Y ≦ 0.022X−0.4 (4)
Where X: combustion chamber height (mm)
Y: Hot gas blowing flow rate (m / sec)

  In the present invention, as described above, hot gas is blown from the ceiling of the combustion chamber, and the blow is blown into two stages, a front stage and a rear stage, and the front stage hot gas supply means and the rear stage hot gas supply means are burned. Control at least one of the flow rate and oxygen concentration of each of the upstream and downstream hot gases so that the oxygen concentration in the region from the start region to the main combustion region is lower than the oxygen concentration in the downstream combustion region As a result, the following effects are obtained.

(1) Combustion stabilization effect by injecting high-temperature gas High-temperature gas is injected downward from the injection port provided in the ceiling of the waste incinerator combustion chamber, and the thermal decomposition of waste is promoted by sensible heat and radiation of the high-temperature gas. Can promote combustion of combustible gas generated by pyrolysis of waste, and further, downward flow of hot gas and upward flow of combustible gas and combustion gas generated from waste layer And a stagnation region where the gas flow circulates just above the waste layer or a circulation region in which the gas circulates in the vertical direction can be formed over a wide range in the width direction and the length direction of the combustion chamber. Combustion is performed, and a planar combustion region (flame) can be established. Further, the thermal decomposition of the waste can be further promoted by radiation of a standing flat flame or the like. Thus, by blowing high-temperature gas, waste and generated combustible gas can be stably burned even in low air ratio combustion where the air ratio is 1.5 or less, regardless of the size of the incinerator. And since combustion is stabilized, the generation amount of harmful substances such as CO and NOx in the exhaust gas discharged from the waste incinerator can be suppressed.

(2) NOx generation suppression effect by two-stage injection of high-temperature gas The high-temperature gas injected from the ceiling of the combustion chamber is controlled separately and blown into two stages, the first stage and the second stage. At least one of the respective flow rates and oxygen concentrations of the front-stage hot gas and the rear-stage hot gas is controlled so that the oxygen concentration in the area up to the main combustion area is lower than the oxygen concentration in the rear combustion area. Therefore, the combustion space is combined with the primary air for combustion so that a relatively low oxygen atmosphere is obtained in the region from the combustion start region to the main combustion region (front region), and in the rear combustion region (rear region). As a result, the waste is thermally decomposed and partially oxidized in a region preceding the low oxygen atmosphere to obtain a combustible gas and a reducing gas as gas components. In the area, By decomposing the reducing gas obtained pear was NOx in preceding region, it is possible to suppress the amount of NOx.

  As described above in (1) and (2) above, by blowing high temperature gas, for example, even in low air ratio combustion where the air ratio is 1.5 or less, the waste and generated combustible gas are stabilized. The amount of CO generated in the exhaust gas discharged from the waste incinerator can be suppressed. Furthermore, the amount of NOx generated in the exhaust gas discharged from the waste incinerator can be suppressed by decomposing NOx by the generated reducing gas by the two-stage blowing of the high-temperature gas at the front stage and the rear stage. In addition, because thermal decomposition and combustion of waste can be promoted, the volume of the combustion chamber can be reduced relative to the amount of waste incineration, the furnace height of the incinerator can be reduced, and waste incineration can be achieved. Equipment costs and operating costs can be reduced by making the equipment compact.

It is a lineblock diagram showing an outline of a waste incinerator concerning one embodiment of the present invention. It is sectional drawing of the combustion chamber width direction explaining the combustion state in the waste incinerator shown in FIG. It is sectional drawing of the combustion chamber length direction explaining the combustion state in the waste incinerator shown in FIG. It is a graph which shows the relationship between the blowing flow rate of high temperature gas, and the combustion chamber height of a waste incinerator.

  Hereinafter, the present invention will be described in detail according to various embodiments of the present invention. The technical scope of the present invention is not limited by these embodiments, and can be implemented in various forms without changing the gist of the invention. Further, the technical scope of the present invention extends to an equivalent range.

  First, prior to the description of this embodiment, regarding the stabilization of combustion by high-temperature gas injection according to the present invention, the structural comparison between the conventional waste incinerator and the waste incinerator of the present invention, and the present invention obtained. Summarize the effects that can be achieved.

  FIG. 2A shows a combustion state in a conventional waste incinerator (the waste incinerator described in Patent Document 1), and FIG. 2B shows a waste incineration according to an embodiment of the present invention. The combustion state in the furnace is shown, and with reference to this, the combustion state in the waste incinerator is related to the combustion stabilization in the high temperature gas blowing in the conventional waste incinerator and one embodiment of the present invention. The waste incinerator will be described for comparison.

  As shown in FIG. 2 (a), the conventional waste incinerator 20 has an inlet 23 in a side wall (a side wall facing in the furnace width direction perpendicular to the moving direction of the waste W on the grate 5) 21. The waste W on the grate 5 is burned by the combustion air A from below. When the waste W is burned, high temperature gas is blown obliquely downward from a blow port 23 provided in the side wall 21 of the combustion chamber, and the thermal decomposition rising from the high temperature gas and the waste layer W on the grate 5 is performed. The upward flow of the combustible gas and the combustion gas generated by the above is collided to form a stagnation region where the flow is slow immediately above the waste layer W. Therefore, a combustible gas is burned to form a planar combustion region (planar flame) D. In such a conventional incinerator, stable combustion can be obtained even in a low air ratio combustion operation, but in a combustion furnace having a large combustion chamber width (distance between the side walls), as shown in FIG. Since the hot gas blown from the blower port 23 does not reach the vicinity of the center of the combustion chamber and a stagnation region cannot be formed in the central portion, a planar combustion region cannot be formed, and the combustible gas is sufficient. There is a problem that it is not combusted and it becomes non-uniform combustion in the furnace width direction.

  In contrast, as shown in FIG. 2 (b), the waste incinerator 1 according to the embodiment of the present invention is provided with a plurality of inlets 13 in the ceiling width direction in the ceiling 22 and disposed on the grate 5. The object W is burned by the combustion air A from below. When the waste W is burned, high temperature gas is blown downward from the blowing port 13 provided on the ceiling 22, and the high temperature gas collides with the upward flow of the combustible gas and the combustion gas rising from the waste W. And a stagnation region where the flow is slow or a circulation region circulating in the vertical direction is formed immediately above the waste layer W, and the planar combustion region (planar flame) E is set in the furnace width direction and the furnace length direction (waste movement direction). Form uniformly. Thereby, even in an incinerator having a large furnace width, uniform and stable combustion is possible.

  Thus, in this invention, the following effects are acquired by inject | pouring hot gas downward from a combustion chamber ceiling.

  The effect of blowing hot gas downward from the ceiling of the combustion chamber will be described in detail.

  (1) The thermal decomposition of the waste W is promoted by the sensible heat and radiation of the high temperature gas.

  (2) The combustion of the combustible gas generated by the thermal decomposition of the waste W is promoted by blowing a high-temperature gas containing oxygen.

  (3) The hot gas is blown downward into the combustion chamber from the inlet 13 provided in the ceiling 22 of the combustion chamber, the downward flow of the high temperature gas, and the upward flow of the combustible gas and the combustion gas generated from the waste W Facing each other and forming a slow stagnation region or a circulation region in which the flow circulates in the vertical direction directly above the waste layer, the combustible gas is stably burned to form a planar combustion region (planar flame) , Standing.

  (4) The thermal decomposition of the waste W is promoted by radiation of the standing flat flame.

  Thus, by the actions (1) to (4), the waste W can be stably burned even under the low air ratio combustion operation. And since combustion is stabilized, combustible gas is fully combusted and the generation amount of harmful substances, such as CO and NOx, in the exhaust gas discharged from the incinerator can be suppressed.

  Hereinafter, the basic configuration, each component device, and operation of the grate-type incinerator of one embodiment of the present invention will be described.

  FIG. 1 is a schematic sectional side view showing a waste incinerator according to an embodiment of the present invention. First, a basic configuration of a waste incinerator and an overview of an incineration method according to an embodiment of the present invention will be described, and then details of each component device will be described. In this embodiment, the upstream side of the combustion chamber in the movement direction of the waste in the combustion chamber is referred to as a front portion, and the downstream side is referred to as a rear portion.

<Basic configuration of grate-type incinerator>
In the waste incinerator 1 shown in FIG. 1, the height of the combustion chamber 2 for burning the waste is 1 to 3 m, and the combustion chamber height of a conventional incinerator having a scale of about 100 tons / day of waste incineration is as high as that of the combustion chamber 2. Compared to being about 5 to 6 m, the height is ½ or less. Further, an example of the volume of the waste incinerator 1 is 90m ^3, equal to or less than about 1/2 of 190 m ³ of conventional incinerators. In this way, the grate-type waste incinerator facility is constructed by stably performing low air ratio combustion by blowing a high-temperature gas, which will be described later, downward from the ceiling, with the height of the combustion chamber 2 being 3 m or less. Can be made compact, and equipment costs and operating costs can be greatly reduced.

  The waste incinerator 1 according to the present embodiment is disposed on the combustion chamber 2 and on the upstream side (left side in FIG. 1) in the flow direction of the waste in the combustion chamber 2 so as to put the waste into the combustion chamber. This is a grate-type incinerator that includes a waste inlet 3 and a boiler 4 that is provided above the downstream side (the right side in FIG. 1) in the waste flow direction of the combustion chamber 2.

  At the bottom of the combustion chamber 2, there is provided a grate (stoker) 5 that burns while moving the waste. The grate 5 is provided in the order of the dry grate 5a, the combustion grate 5b, and the post-combustion grate 5c from the side closer to the waste inlet 3, that is, from the upstream side.

  In the dry grate 5a, waste is mainly dried and ignited. In the combustion grate 5b, waste is thermally decomposed and partially oxidized, and combustible gas and solid content generated by the thermal decomposition are combusted. On the post-combustion grate 5c, the remaining unburned matter in the waste is completely burned. The combustion ash after complete combustion is discharged from the ash drop opening 6.

  In such an incinerator of this embodiment, a waste layer is formed on the dry grate 5a and the combustion grate 5b, and due to the combustion, the space in the combustion chamber 2 is directly above the waste layer. The following regions are formed.

  A drying region is formed directly above the drying grate 5a and below the waste input port 3 and above the upstream range (front) in the waste flow direction of the drying grate 5a. The

  A combustion start region is formed above the upstream range (front) of the combustion grate 5b from the downstream range (rear) of the dry grate 5a. That is, the waste in the dry grate 5a is dried in the upstream range, ignited in the downstream range, and combustion starts in the range up to the upstream range (front) of the combustion grate 5b.

  The waste on the combustion grate 5b is thermally decomposed and partially oxidized here to generate a combustible gas, and the combustible gas and the solid content of the waste are combusted. The waste is substantially burned on the combustion grate 5b. Thus, a main combustion region is formed above the combustion grate 5b.

  Thereafter, the unburned matter such as fixed carbon in the remaining waste is completely burned on the post-burning grate 5c. A post-combustion region is formed above the post-combustion grate 5c.

  When the waste is incinerated, water evaporation occurs first, followed by thermal decomposition and partial oxidation reaction, and combustible gas begins to be generated. Here, the combustion start region is a region where combustion of waste starts and combustible gas begins to be generated by thermal decomposition and partial oxidation of the waste. The main combustion region is a combustion region where waste is thermally decomposed and partially oxidized to generate combustible gas, and the combustible gas is burned with a flame and the solid content of the waste is combusted. This is the region up to the point where combustion with flame is completed (burn-out point). In a region after the burn-out point, a char combustion region (post-combustion region) in which solid unburnt (char) in the waste is combusted is obtained.

  Wind boxes 7a, 7b, 7c, and 7d are provided below the dry grate 5a, the combustion grate 5b, and the post-combustion grate 5c in the combustion chamber 2, respectively. The combustion primary air A supplied by the blower 8 is supplied to the wind boxes 7a, 7b, 7c, 7d through the combustion primary air supply pipe 9, and combusts through the grate 5a, 5b, 5c. It is supplied into the chamber 2. The primary air A for combustion supplied from below the grate is used for drying and burning waste on the grate 5a, 5b, 5c, cooling action of the grate 5a, 5b, 5c, Has a stirring action.

  A waste heat boiler 4 is connected to the outlet on the downstream side of the combustion chamber 2, and the vicinity of the inlet of the waste heat boiler 4 is a secondary combustion region 10 for burning unburned gas in the gas discharged from the combustion chamber 2. It has become. The secondary combustion gas is blown into the secondary combustion region 10 which is a part of the waste heat boiler, and the unburned gas is subjected to secondary combustion. After this secondary combustion, the combustion exhaust gas is recovered by the waste heat boiler 4 as heat. . After heat recovery, the combustion exhaust gas discharged from the waste heat boiler is neutralized with acid gas by slaked lime, etc. and dioxins are adsorbed by activated carbon in an exhaust gas treatment system (not shown), and further to a dust removal equipment (not shown). The neutralized reaction product, activated carbon, dust and the like are collected. The combustion exhaust gas that has been dedusted and detoxified by the dust removing device is attracted by an attraction fan (not shown) and released from the chimney into the atmosphere. Further, a part of the combustion exhaust gas after being dust-removed by the dust removing device is used as a return exhaust gas to be described later.

  In the grate-type incinerator having such a basic configuration, the waste incinerator 1 according to the present embodiment includes a primary air blowing unit that blows primary combustion air into the combustion chamber from below the grate, and a furnace High temperature gas blowing means for blowing high temperature gas downward from the ceiling of the combustion chamber is provided.

<Primary air blowing means>
In the present embodiment, the waste incinerator 1 includes a primary air supply system of primary air that serves as combustion air. In the primary air supply system, the primary air A from the air supply source is branched to the wind boxes 7a, 7b, 7c, and 7d of the dry grate 5a, the combustion grate 5b, and the post-combustion grate 5c via the pipe line 9, respectively. The pipe 9 is provided with a blower 8 and a damper 11 as a flow rate adjusting mechanism.

<High-temperature gas blowing means>
In the present embodiment, the waste incinerator 1 includes a high temperature gas blowing means for blowing a high temperature gas downward from the ceiling of the combustion chamber. High temperature gas is blown in from the high temperature gas injection port at the front stage toward the region from the combustion start region to the main combustion region, and the high temperature gas is injected from the high temperature gas injection port at the front stage to the front of the post combustion region or burned. Blow toward the area immediately after the cut point.

  The high-temperature gas blowing means includes a front-stage high-temperature gas supply device 24 and a rear-stage high-temperature gas supply device 25 provided outside the combustion chamber 2, a front-stage high-temperature gas injection port 13 for blowing high-temperature gas into the combustion chamber 2, and a flow rate adjusting mechanism. And a damper 16 as a flow rate adjusting mechanism, and a conduit for guiding the high temperature gas to the high temperature gas injection ports 13 and 15.

  The upstream high temperature gas supply device 24 mixes the return exhaust gas and the high temperature air to prepare a high temperature gas, and supplies the high temperature gas to the upstream high temperature gas inlet 13. Here, the “returned exhaust gas” is a part of the exhaust gas after the exhaust gas discharged from the incinerator is neutralized by the exhaust gas treatment system and removed by the dust removing device. The high-temperature air is generated by heating air with a heater. The pre-stage high temperature gas supply device 24 adjusts the mixing ratio by adjusting the flow rates of the return exhaust gas and the high temperature air to adjust the temperature and oxygen concentration of the high temperature gas. Moreover, the front | former stage high temperature gas supply apparatus 24 may supply only high temperature air as high temperature gas. On the other hand, the rear-stage hot gas supply device 25 supplies the returned exhaust gas as a high-temperature gas to the rear-stage hot gas inlet 15. Further, the rear-stage hot gas supply device 25 may supply a mixed gas of the return exhaust gas and the high-temperature air as the rear-stage hot gas.

  The upstream high-temperature gas inlet 13 is directly above the grate in the range from the downstream side (rear part) of the waste grate 5a in the waste moving direction to the downstream side (rear part) of the combustion grate 5b. It is provided in the position. Moreover, the high temperature gas inlet 13 (13a, 13b, 13c) is arrange | positioned in the multiple positions (three places) of the furnace length direction within said range.

  The rear-stage high-temperature gas inlet 15 is provided at a position directly above the grate on the upstream side (front part) of the rear combustion grate 5 c on the ceiling of the combustion chamber 2. Further, the subsequent high-temperature gas injection port 15 may be provided on the downstream side (rear part) of the combustion grate 5b.

  In the hot gas blowing means, the directions of the hot gas blowing ports 13 and 15 are determined so that the hot gas is blown downward. Thus, the upstream hot gas is blown from the upstream hot gas inlet 13 toward the region from the combustion start region to the main combustion region, and the downstream hot gas is injected from the downstream hot gas inlet 15 to the front region of the rear combustion region. It is provided so that it blows toward. Moreover, the hot gas from the hot gas blowing port 15 in the subsequent stage may be blown toward the region immediately after the burnout point.

  The hot gas blowing ports 13 and 15 are provided at a plurality of locations in the furnace width direction (direction perpendicular to the paper surface in FIG. 1). Moreover, although the high temperature gas injection port 13 (13a, 13b, 13c) is arrange | positioned in three places of the furnace length direction within said range, regardless of this, the high temperature gas injection port 13 and 15 is said range. Each of them may be arranged at a plurality of positions in the furnace length direction.

<Secondary combustion gas supply means>
Further, the waste incinerator 1 of the present embodiment includes a secondary combustion gas supply system that blows the secondary combustion gas into the secondary combustion region 10 corresponding to the vicinity of the inlet of the boiler 4. The secondary combustion gas supply system feeds the secondary combustion gas C from the secondary combustion gas supply source through the pipe 12 to the secondary combustion gas inlet 17 provided in the secondary combustion region 10. The pipe 12 is provided with a blower 18 and a damper 19 as a flow rate adjusting mechanism. The secondary combustion gas blowing port 17 is provided on the peripheral wall of the boiler 4 so as to blow the secondary combustion gas C into the secondary combustion region 10 in the vicinity of the inlet of the boiler 4. Most of the combustible gas generated in the combustion chamber 2 is combusted in the combustion chamber 2, and the remaining unburned gas is secondary corresponding to the vicinity of the inlet of the boiler 4 connected above the post-combustion grate 5c. The gas flows into the combustion region 10 where secondary combustion gas is supplied and secondary combustion is performed.

  In the present invention, the configuration of the pipeline for supplying the primary air for combustion, the high-temperature gas, and the secondary combustion gas is not limited to those shown in the drawings, and may be appropriately selected depending on the scale, shape, application, etc. Can be selected.

  Next, an outline of the incineration situation in the apparatus of the present embodiment configured as described above, and actions by blowing in primary combustion air, high temperature gas, and secondary combustion air will be sequentially described.

<Overview of incineration>
First, when waste is introduced into the waste inlet 3, the dropped waste is supplied into the combustion chamber by a waste supply device (not shown) and deposited on the dry grate 5a. It moves onto the grids 5b and onto the post-combustion grate 5c, forming a waste layer on each grate. Each grate receives the primary air for combustion via the wind boxes 7a, 7b, 7c, 7d, whereby the waste in each grate is dried and burned.

  Wastes are mainly dried and ignited on the dry grate 5a. That is, the waste of the dry grate 5a is dried in the upstream range of the dry grate 5a, ignited in the downstream range of the dry grate 5a, and up to the upstream range (front part) of the combustion grate 5b. Combustion starts in the range. A dry region is formed above the upstream range (front part) of the dry grate 5a in the waste flow direction. A combustion start region is formed above the upstream range (front) of the combustion grate 5b from the downstream range (rear) of the dry grate 5a. On the combustion grate 5b, pyrolysis and partial oxidation of waste are mainly performed to generate a combustible gas. The combustible gas burns with a flame, and solids in the waste are combusted. A combustion region is formed above the combustion grate 5b. This combustion region is a region up to the point where combustion with flame is completed (burn-out point). The combustion of the waste is substantially completed on the combustion grate 5b. On the post-combustion grate 5c, unburned components such as fixed carbon in the remaining waste are completely burned. In the region after the burn-out point, the solid unburned part (char) in the waste is burned, and a post-combustion region is formed above the post-combustion grate 5c. The combustion ash after complete combustion is discharged from the ash drop opening 6. With the waste burning in this manner, as seen in FIG. 1, the space immediately above each grate 5a, 5b, 5c has a dry region A1, a combustion start region A2, a main combustion region A3, and a rear region. A combustion region A4 is formed.

  As described above, the waste heat boiler 4 is connected to the outlet of the combustion chamber 2, and the vicinity of the inlet of the waste heat boiler 4 is the secondary combustion region 10. Therefore, the unburned gas generated in the combustion chamber 2 is guided to the secondary combustion region 10, where it is mixed and stirred with the secondary combustion gas C, and undergoes secondary combustion. After the secondary combustion, the exhaust gas is recovered by the waste heat boiler 4. After heat recovery, the exhaust gas discharged from the waste heat boiler 4 is neutralized with acid gas by slaked lime, adsorbed dioxins with activated carbon, and sent to a dust removal device (not shown). The reaction product, activated carbon, dust, etc. are recovered. The exhaust gas that has been dedusted and detoxified by the dust remover is attracted by an attracting fan (not shown) and released from the chimney into the atmosphere. In addition, as said dust removal apparatus, dust removal apparatuses, such as a bag filter system and an electrostatic dust collection system, can be used, for example. Further, a part of the exhaust gas after being removed by the dust removing device is used as the return exhaust gas.

<Blowing primary air for combustion>
The primary air A for combustion passes from the blower 8 through the primary air supply pipe 9 for combustion, and wind boxes 7a, 7b, 7c provided at the lower portions of the dry grate 5a, the combustion grate 5b, and the post-combustion grate 5c, respectively. , 7d and then supplied into the combustion chamber 2 through the grate 5a, 5b, 5c. The flow rate of the combustion primary air A supplied into the combustion chamber 2 is adjusted by a flow rate adjusting damper 11 provided in the combustion primary air supply pipe 9, and further supplied to each wind box 7a, 7b, 7c, 7d. The flow rate to be adjusted is adjusted by a flow rate adjustment damper (not shown) provided in each supply pipe provided to be branched to each wind box. Further, the configurations of the wind boxes 7a, 7b, 7c, 7d and the combustion primary air supply pipe 9 for supplying the combustion primary air A are not limited to those shown in the figure, but the incinerator scale, shape, application, etc. Can be appropriately selected.

  As the primary air A for combustion, it is preferable to use a gas having a temperature in the range of room temperature to 200 ° C. and an oxygen concentration in the range of 15 to 21% by volume. As the primary air A for combustion, any of air, oxygen-containing gas and return exhaust gas may be used, or a mixed gas thereof may be used.

<Combustion stabilization by hot gas injection>
As seen in FIG. 1, the hot gas is blown from the hot gas inlet 13 (13a, 13b, 13c) at the preceding stage toward the region from the combustion start area A2 to the main combustion area A3, and the hot gas at the latter stage. From the inlet 15, it is blown toward the front region of the post-combustion region A4, and as a whole, in the region from the combustion start region A2 in the combustion chamber 2 to the front portion of the post-combustion region A4, It is blown downward toward the waste layer W. In order to stabilize the combustion, it is preferable to blow high-temperature gas into a region where there is a flame and a large amount of combustible gas. Therefore, before the combustion start region A2 which is a region where a large amount of combustible gas is present, Hot gas is blown into the area up to the section.

  From the front stage high temperature gas inlet 13 and the rear stage hot gas inlet 15, the high temperature gas is directed from the combustion start area A2 in the combustion chamber 2 to the front part of the rear combustion area A4 and directly above the waste layer W. The high-temperature gas blown downward is opposed to the upward flow of combustible gas and combustion gas generated by thermal decomposition and partial oxidation of the waste, and both gas flows collide with each other. A flat stagnation region with a slow flow or a circulation region that circulates in the vertical direction is formed immediately above the layer W. Since these regions have a slow gas flow rate, a flame in which the combustible gas burns is fixed, that is, a planar combustion region (planar flame) is present immediately above the waste layer W, and the combustible gas is present. Is stably burned. As a result, generation of soot can be suppressed while suppressing generation of harmful substances such as CO, NOx, dioxins and the like even in low air ratio combustion. For this reason, low air ratio combustion can be performed without hindrance.

  In addition to the fact that wastes are heated by thermal radiation and sensible heat of high-temperature gas, and thermal decomposition and partial oxidation are promoted, a planar combustion region (planar flame) is present directly above the waste layer. The waste is heated by thermal radiation and sensible heat from the flat flame, and thermal decomposition and partial oxidation are further promoted.

<NOx reduction by high-temperature gas two-stage injection>
In a waste incinerator, nitrogen contained in waste and nitrogen in the air react at high temperatures to generate NOx. When exhaust gas discharged from the incinerator is discharged from the chimney into the atmosphere, the NOx concentration must be below the regulation value, so NOx is removed in the exhaust gas treatment system, but the amount of NOx generated in the incinerator Suppressing this is a fundamental measure, and this is desired. In the present embodiment, the high temperature gas is blown from the two stages of the high temperature gas blowing port of the former stage and the latter stage, and when the high temperature gas is blown from the high temperature gas blowing port 13 of the previous stage, a low oxygen atmosphere is formed to generate the reducing gas. Since NOx is decomposed by this reducing gas, the amount of NOx generated can be suppressed.

  FIG. 3 is a cross-sectional view in the length direction of the combustion chamber for explaining the combustion state in the waste incinerator. As shown in FIG. 3, first, when blowing the front-stage hot gas from the front-stage hot gas inlet 13, at least one of the oxygen concentration and the supply amount of the front-stage hot gas was adjusted and combined with the primary air for combustion. Adjusting the oxidant supply amount, the region from the combustion start region A2 to the main combustion region A3 is, for example, a low oxygen atmosphere having an oxygen concentration of 0 to 2 dry volume% (local air ratio is 0.6 to 0.8). And By pyrolysis and partial oxidation of waste in a low oxygen atmosphere, combustible gas and reducing gas (CO, HCN, NHn, CmHn) are generated as gas components (CO and CmHn are combustible). The generated combustible gas is burned uniformly and stably in the planar combustion region formed as described above. The reducing gas is used so as to be led downstream in the combustion chamber and decompose NOx. When a low oxygen atmosphere is formed in the region from the combustion start region A2 to the main combustion region A3, if the local air ratio is smaller than 0.6, the generation of reducing gas becomes excessive, and excess NHn causes NOx on the downstream side. Is generated, or the generation of flammable gas is excessive and the generation of unburned gas is excessive, which is not suitable. If the oxygen concentration is higher than 2 dry volume% (air ratio is 0.8), a low oxygen atmosphere is generated. In other words, the amount of reducing gas generated is small and unsuitable. Therefore, the oxygen concentration in the region from the combustion start region A2 to the main combustion region A3 is preferably 0 to 2 dry volume% (air ratio is 0.6 to 0.8). .

  Next, when the rear-stage hot gas is blown from the rear-stage hot gas inlet 15, at least one of the oxygen concentration and the supply amount of the rear-stage hot gas is adjusted, and the oxidant supply amount combined with the combustion primary air is adjusted. Then, the region of the post-combustion region A4 is, for example, an oxygen-excess atmosphere having an oxygen concentration of 5 to 8 dry volume% (local air ratio is 1.3 to 1.6). If the oxygen concentration in the oxygen-excess atmosphere is less than 5 dry volume% (air ratio is 1.3), the solid combustion of the waste is not performed sufficiently and becomes unburned and unsuitable, and the oxygen concentration becomes 8 dry volume% (local air ratio). Is larger than 1.6), the amount of NOx generated increases and becomes unsuitable. Therefore, the oxygen concentration in the post-combustion region A4 is preferably 5 to 8 dry volume% (air ratio is 1.3 to 1.6).

  The supply amount of the high-temperature gas is adjusted, for example, by the front-stage high-temperature gas supply device 24 and the rear-stage high-temperature gas supply device 25 adjusting the blower flow rate of the blower that sends the high-temperature gas and the opening degree of the dampers 14 and 16. The The adjustment of the oxygen concentration of the high temperature gas will be described later.

  In the waste incinerator of the embodiment of FIG. 1, the high temperature gas blowing means adjusts the oxygen concentration of the high temperature gas according to the contents described later in the front stage high temperature gas supply device 24 and the rear stage high temperature gas supply device 25, or the high temperature gas. By adjusting the supply amount of the hot gas supplied to the inlets 13 and 15 by adjusting the blower air flow rate and adjusting the opening of the dampers 14 and 16, respectively, the region from the combustion start region A2 to the main combustion region A3 and the rear The oxygen concentration (local air ratio) in the front region of the combustion region A4 is controlled within a predetermined range.

  In the present embodiment, as shown in FIG. 3, an oximeter 31 is provided on the furnace wall of the combustion chamber and measures the oxygen concentration in the region from the combustion start region A2 to the main combustion region A3 in the combustion chamber 2, The oxygen concentration is measured by an oxygen concentration meter 32 that measures the oxygen concentration in the front region of the rear combustion region A4, and the oxygen concentration (air ratio) in each region is set within a predetermined range based on the measured oxygen concentration. In addition, the supply amount of hot gas or the oxygen concentration is controlled.

NOx generated from the combustion start region A2 to the post-combustion region A4 reacts with the above-described reducing gas in an oxygen-excess atmosphere and is decomposed, and the NOx content in the exhaust gas is reduced and discharged. In addition, of the reducing gas that contributes to the reaction with NOx, the excess of HCN and NHn reacts with oxygen in an oxygen-excess atmosphere and is decomposed or N ₂ is not emitted as it is. Does not occur.

  In order to extract the exhaust gas from the incinerator and discharge it from the chimney, the in-furnace gas is attracted by a fan, and the in-furnace gas is guided toward the exhaust gas outlet. In the present embodiment, the distance in the furnace length direction between the upstream hot gas inlet 13 and the upstream hot gas inlet 15 is set so that the in-furnace gas passes in a time of 0.5 to 1.5 seconds. It is preferable to do. It is preferable to react the generated reducing gas with NOx within the above time because the reaction efficiency becomes high. If this time is slower than 1.5 seconds, the amount of radicals in the reducing gas reacting with NOx is increased, and the reaction with NOx is greatly reduced. If it is earlier than 0.5 seconds, the reducing gas and NOx are reduced. This reaction is not suitable because NOx remains and NOx is generated from excess NHn, and thus the above time is preferably 0.5 to 1.5 seconds.

  Next, the preparation of the high temperature gas, the inlet, the injection flow velocity / injection amount, the injection of the secondary combustion gas, and the oxygen amount ratio distribution for carrying out the low air ratio combustion will be sequentially described. .

<Preparation of hot gas>
The temperature of the hot gas blown from the hot gas blowing ports 13 and 15 is preferably in the range of 100 to 400 ° C, more preferably about 150 to 200 ° C. When a gas having a temperature of less than 100 ° C. is blown, the temperature in the furnace decreases, combustion becomes unstable, and the amount of CO generated increases. When a gas exceeding 400 ° C. is blown, the flame temperature in the combustion chamber becomes extremely high, which causes problems such as promotion of clinker generation. By setting the temperature of the high-temperature gas to about 150 to 200 ° C., the occurrence of the above-described problem can be suppressed and the energy for heating the air can be set to an appropriate range, which is more preferable.

  Further, the oxygen concentration of the high temperature gas (also referred to as “pre-stage high-temperature gas”) blown from the front-stage high-temperature gas injection port 13 is 12 to 21 dry volume%, and the high-temperature gas injected from the rear-stage high-temperature gas injection port 15 ( The oxygen concentration of the “hot gas” is preferably adjusted to 1 to 12 dry volume%. Thereby, the above-mentioned effect is exhibited more effectively, and the reduction of NOx and the reduction of CO of exhaust gas is further promoted.

  The grounds for setting the oxygen concentration of the pre-stage hot gas in the above range are as follows. When the region from the combustion start region A2 to the main combustion region A3 is in a low oxygen atmosphere, if the oxygen concentration of the pre-stage high temperature gas is lower than the lower limit, the generation of reducing gas becomes excessive, and excess NHn leads to the downstream side. This is unsuitable because NOx is generated or flammable gas is excessively generated and unburned gas is excessively generated. If the oxygen concentration is higher than the upper limit, a low oxygen atmosphere is not achieved, and the amount of reducing gas generated is low. Therefore, the oxygen concentration of the pre-stage hot gas is preferably 12 to 21 dry volume%.

  The grounds for setting the oxygen concentration of the latter-stage hot gas in the above range are as follows. When the front region of the post-combustion region A4 is in an oxygen-excess atmosphere, if the oxygen concentration of the post-stage hot gas is lower than the lower limit, the solid combustion of the waste is not performed sufficiently and becomes unburned and unsuitable, If it is higher than the upper limit, the amount of NOx generated increases, which is inappropriate. Therefore, the oxygen concentration of the latter stage hot gas is preferably 1 to 12 dry volume%.

  In this embodiment, a mixed gas or high-temperature air of return exhaust gas and high-temperature air that returns a part of the exhaust gas discharged from the incinerator is used as the pre-stage high-temperature gas so that the high-temperature gas has the gas temperature and oxygen concentration described above. Used as the rear stage high-temperature gas is a return exhaust gas or a mixed gas of the return exhaust gas and high-temperature air. As the return exhaust gas, a part of the exhaust gas that has been subjected to neutralization treatment of acid gas, dioxins treatment, and dust removal treatment by the above-described exhaust gas treatment system and dust removal device is used for the exhaust gas discharged from the incinerator. . The high-temperature air is generated by heating air by heat exchange with steam generated by a waste heat boiler. In this embodiment, the return exhaust gas, the return exhaust gas and high-temperature air mixed gas, and the high-temperature air are heated by heat exchange with the steam generated in the waste heat boiler as necessary, and the temperature and oxygen concentration are set to the predetermined values. It is blown into the combustion chamber as a high-temperature gas that satisfies the following conditions.

  In this way, adjusting the mixing ratio of the return exhaust gas and hot air when preparing the high temperature gas, the return exhaust gas, the return exhaust gas and high temperature air mixed gas, the heating conditions of the high temperature air, etc., the temperature of the high temperature gas, oxygen Bring the concentration to the desired range.

<High temperature gas inlet>
The upstream high-temperature gas inlet 13 is within the range from the downstream side (rear part) of the waste grate 5a in the movement direction to the downstream side (rear part) of the combustion grate 5b in the movement direction of the waste grate 5a. It is provided at a position directly above the grate.

  The rear-stage high-temperature gas inlet 15 is provided at a position directly above the grate on the upstream side (front) in the moving direction of the rear combustion grate 5 c on the ceiling of the combustion chamber 2.

  A plurality of front-stage high-temperature gas injection ports 13 and rear-stage high-temperature gas injection ports 15 are arranged in the width direction of the combustion chamber 2. In the embodiment shown in FIG. 1, the hot gas inlets 13 are arranged at three locations in the furnace length direction within the above range, but the hot gas inlets 13 and 15 are not limited to the above range. Each of them may be arranged at a plurality of positions in the furnace length direction. The hot gas blowing ports 13 and 15 may be nozzle type or slit type.

  The state of the flow of the high-temperature gas facing the upward flow from the waste is favored so that a planar combustion region is formed over a wide range in the width direction and the length direction immediately above the waste layer in the combustion chamber. In order to control, at least one of the arrangement position, the number of arrangements, the arrangement interval, the blowing direction, the shape of the blowing port, the blowing flow rate and the blowing flow rate of the hot gas is set or adjusted.

  In FIG. 1, the hot gas is blown downward from the hot gas blowing ports 13 and 15 toward the waste layer. Here, as a blowing direction of the high temperature gas, it is desirable to blow in a blowing direction in an angle range from a perpendicular to the waste layer to 20 °. This is because the flow field generated by the collision of the blown hot gas with the combustible gas generated by thermal decomposition and partial oxidation of waste and the upward flow of the combustion gas is used as the counter flow field. This is because an appropriate counter flow field is not formed when the entraining direction is in a range larger than 20 ° from the perpendicular to the waste layer.

<High-temperature gas blowing flow rate>
As will be described below, the upper and lower limits of the appropriate range of the hot gas injection flow rate corresponding to the combustion chamber height were clarified, and the preferred range was determined.

  Opposite the upward flow of combustible gas and combustion gas generated from waste, high temperature gas is blown downward from the ceiling of the combustion chamber to form an appropriate stagnation region or circulation region directly above the waste layer. In order to establish the combustion region, it is necessary to appropriately impinge the hot gas blown into the upward flow from the waste layer, and it is necessary to increase the flow velocity as the combustion chamber height increases. However, if the flow rate is made too high, the high temperature gas blows directly into the waste layer, causing the waste to cool down or scatter the waste, resulting in unstable combustion. , Fly ash increases and is not preferable. Therefore, an upper limit of the flow rate of the hot gas is determined by obtaining a flow rate that does not adversely affect the waste layer. Further, the lower limit of the flow rate of the hot gas is determined from the limit flow rate at which the stagnation region or the circulation region can be formed. In this way, an appropriate range of the hot gas flow rate is determined in accordance with the combustion chamber height.

  By examining the amount of harmful substances generated as an indicator of the impact on the combustion stability of waste, we determined the appropriate range of the high-temperature gas flow rates for the front and rear stages according to the combustion chamber height. Specifically, for a waste incinerator with a certain combustion chamber height, when the flow rate of high-temperature gas is changed variously, the concentration of harmful substances such as CO and NOx in the exhaust gas discharged from the waste incinerator is investigated, The range of high-temperature gas flow velocity that can suppress the generation of gas, that is, stable combustion, is determined, and the case where the combustion chamber height is different is examined in the same way, and the flow rate of the high-temperature gas relative to the combustion chamber height is The preferred range was clarified. Such a range is a range having an upper limit and a lower limit as shown in FIG. 4 showing the relationship of the flow velocity of the hot gas to the combustion chamber height.

  The lines indicating the upper and lower limits of the appropriate range of the hot gas blowing flow rate are the following (5) to (8) as the relational expression between the hot gas blowing flow rate (Y) and the combustion chamber height (X). )

[Pre-stage hot gas]
Upper limit: Y = 0.0153X−0.6 (5)
Lower limit: Y = 0.0069X−1.3 (6)
[Last stage hot gas]
Upper limit: Y = 0.022X−0.4 (7)
Lower limit: Y = 0.018X-1.0 (8)
Where Y: Hot gas blowing flow rate (m / sec)
X: Combustion chamber height (mm)

  The waste incinerator and the waste incineration method of the present invention can be achieved by setting the flow velocity of hot gas to an appropriate range as defined by the relational expression indicating the upper and lower limits with respect to the combustion chamber height. In the incinerator with a wide range of combustion chamber heights, the appropriate blowing conditions of the high temperature gas blown downward from the combustion chamber ceiling inlet are clarified. The combustion of waste is stable even under low air ratio combustion.

  An appropriate range in accordance with the combustion chamber height of the hot gas injection flow rate is a range indicated by the following relational expressions (9) and (10).

[Pre-stage hot gas]
0.0069X−1.3 ≦ Y ≦ 0.0153X−0.6 (9)
[Last stage hot gas]
0.018X−1.0 ≦ Y ≦ 0.022X−0.4 (10)
Where Y: Hot gas blowing flow rate (m / sec)
X: Combustion chamber height (mm)

  Combustion gas and combustion gas generated by pyrolysis and partial oxidation of waste by changing the flow rate of hot gas blown downward from the blow-off port of the combustion chamber ceiling according to the height of the combustion chamber. To form a slow stagnation area with a flat flow or a circulation area that circulates in the vertical direction above the waste layer W, and to establish a flat combustion area directly above the waste layer W. Combustible gas can be stably burned, and a combustion promotion effect and combustion stabilization effect can be reliably obtained by low air ratio combustion operation regardless of the combustion chamber height.

  For example, the high-temperature gas blowing speed is controlled by, for example, dampers 14 and 16 as a flow rate adjustment mechanism provided in a blower for adjusting the blower amount of a blower that sends the high-temperature gas to the upstream high-temperature gas supply device 24 and the subsequent high-temperature gas supply device 25, respectively. It is adjusted by adjusting the opening degree of the gas and adjusting the flow rate of hot gas.

  When there are a plurality of hot gas gas inlets 13 and 15, the hot gas does not necessarily have to be blown from the hot gas inlets 13 and 15 at the same flow rate, and the scale, shape, application or waste property, amount, Depending on the waste layer thickness or the like, the blowing flow rate from each of the hot gas blowing ports 13 and 15 can be appropriately changed so as to be different.

  High temperature gas is blown downward from the blow-off port provided on the ceiling of the waste incinerator combustion chamber, and the flow velocity of the high temperature gas to be blown is in an appropriate range with respect to the height of the combustion chamber. Combustion gas generated from the material layer collides with the upward flow of the combustion gas, and the stagnation region where the gas flow circulates just above the waste layer or the circulation region where it circulates in the vertical direction is the width direction and length of the combustion chamber. Since it can be formed over a wide range of directions, a planar combustion region can be established, and the air ratio is 1. regardless of the size of the incinerator, that is, the width and height of the combustion chamber. Even in low air ratio combustion of 5 or less, waste and generated combustible gas can be stably burned. And since combustion is stabilized, the generation amount of harmful substances such as CO and NOx in the exhaust gas discharged from the waste incinerator can be suppressed. Furthermore, the thermal decomposition of waste can be promoted by radiation of a standing flat flame, etc., so the amount of waste supplied to the grate (grate load) and the amount of waste heat supplied to the combustion chamber (furnace) Load) can be increased. For this reason, the volume of the combustion chamber can be reduced relative to the amount of waste incineration, the furnace height of the incinerator can be reduced, and the waste incineration equipment can be made compact to reduce equipment costs and operating costs. Can do.

<High-temperature gas injection flow rate>
The upper and lower limits of the appropriate range of the hot gas blowing flow rate corresponding to the amount of waste to be put into the incinerator and the calorific value generated by burning the waste were clarified, and the preferred range was determined. If the amount of waste put into the incinerator is large, or if the amount of heat generated by burning the waste is large, the amount of combustible gas and combustion gas generated from the waste increases. Opposite the upward flow of combustible gas and combustion gas generated from waste, high temperature gas is blown downward from the ceiling of the combustion chamber to form an appropriate stagnation region or circulation region directly above the waste layer. In order to establish the combustion region, it is necessary to appropriately collide the hot gas injected into the upward flow from the waste layer, and if the amount of combustible gas and combustion gas generated increases, the hot gas injection flow rate increases. There is a need to. However, if the flow rate is increased too much, it blows directly into the waste layer and the hot gas collides with it, cooling the waste or splashing the waste, causing unstable combustion. , Fly ash increases and is not preferable. Therefore, an upper limit of the flow rate of the high temperature gas is determined by obtaining a flow rate that does not adversely affect the waste layer. Further, the lower limit of the flow rate of the hot gas is determined from the limit flow rate at which the stagnation region or the circulation region can be formed. Thus, an appropriate range of the high-temperature gas flow rate is determined in accordance with the amount of waste and the amount of heat generated by waste.

  As an indicator of the impact on the combustion stability of waste, by examining the amount of generated harmful substances, the appropriate range of the flow rate of high-temperature gas at the front and rear stages in accordance with the amount of waste and the amount of heat generated by the waste can be determined. Determined. Specifically, in the case of a certain amount of waste and waste heat generation, the concentration of harmful substances such as CO and NOx in the exhaust gas discharged from the waste incinerator is investigated by changing the flow rate of high-temperature gas. The amount of high-temperature gas flow that can suppress the generation of waste, that is, stable combustion, is determined, and the same consideration is given to the case where the amount of waste and the amount of heat generated by the waste are different. The preferable range of the flow rate of the hot gas with respect to is clarified. Here, the amount of exhaust gas discharged from the secondary combustion chamber (secondary combustion chamber exhaust gas amount) is used to correspond to the waste amount and waste heat generation amount, and the flow rate of the high-temperature gas with respect to the secondary combustion chamber exhaust gas amount The preferred range was clarified.

  It is preferable that the flow rate of the hot gas blown from the upstream hot gas blowing port (the sum of the flow rates of the plurality of blowing ports) is adjusted to 6 to 18% of the amount of exhaust gas discharged from the secondary combustion chamber. Moreover, it is preferable that the flow rate of the hot gas blown from the subsequent hot gas blowing port (the sum of the flow rates of the plurality of blowing ports) is adjusted to 15 to 30% of the amount of exhaust gas discharged from the secondary combustion chamber. When the flow rate of the hot gas is less than the lower limit, the blown hot gas cannot be appropriately collided with the upward flow from the waste layer, and the stagnation region or the circulation region cannot be formed. In addition, if the gas flow rate is higher than the upper limit, the waste layer is adversely affected.

  The high-temperature gas blow-in flow rate is adjusted, for example, by the front-stage high-temperature gas supply device 24 and the rear-stage high-temperature gas supply device 25 adjusting the flow rate of the blower sending the high-temperature gas and the openings of the dampers 14 and 16, respectively. It is adjusted by etc.

  When there are a plurality of high-temperature gas injection ports 13 and 15 in the furnace width direction or the furnace length direction of the combustion chamber, the high-temperature gas does not necessarily have to be injected from each of the high-temperature gas injection ports 13 and 15 at an equal flow rate. Depending on the scale, shape, application or waste property, amount, waste layer thickness, etc., the blow flow rate from each of the high temperature gas blow ports 13, 15 can be appropriately changed.

  In response to fluctuations in the amount of combustible gas and combustion gas generated from the waste in the combustion chamber 2, high-temperature gas injection is performed so that the planar combustion region is fixed immediately above the waste layer W without fluctuation. It is preferable to adjust the flow rate. When the state of the planar combustion region changes, the combustion state of the combustible gas changes and the CO concentration, oxygen concentration, etc. in the combustion exhaust gas change, so the CO concentration and oxygen concentration of the exhaust gas discharged from the boiler are monitored as monitoring factors. You may make it adjust the blowing flow rate of hot gas according to the measurement and the change.

<Injection of secondary combustion gas>
The secondary combustion gas is blown into the secondary combustion region 10 and the unburned gas from the combustion chamber 2 is subjected to secondary combustion. As the secondary combustion gas, it is preferable to use a gas having a temperature in the range of room temperature to 200 ° C. and an oxygen concentration in the range of 15 to 21% by volume. As the secondary combustion gas, air, a gas containing oxygen, a return exhaust gas, or a mixed gas thereof may be used.

  It is preferable to install one or more secondary combustion gas inlets 17 so that gas can be blown in the direction in which the swirling flow is generated in the secondary combustion region. By blowing the secondary combustion gas C in the direction in which the swirl flow is generated in the secondary combustion region 10, the gas temperature and oxygen concentration distribution in the secondary combustion region 10 can be made uniform and averaged. Subsequent combustion is performed stably, generation of a local high temperature region is suppressed, and exhaust gas can be further reduced in NOx. Furthermore, since the mixing of the unburned gas and the oxidant is promoted, the combustion stability is improved and complete combustion can be achieved, so that the exhaust gas can be reduced in CO.

  As the secondary combustion gas C, only the secondary air for combustion supplied by the blower, the gas in which the diluent is mixed with the secondary air for combustion after supply of the blower and the oxygen concentration is adjusted, after passing through the dust removing device Only the return exhaust gas from which a part of the exhaust gas is extracted, or a gas in which the secondary air for combustion and the return exhaust gas are mixed can be used.

  Diluents such as nitrogen and carbon dioxide are conceivable.

  It is preferable to adjust the flow rate of the secondary combustion gas so that the gas temperature in the secondary combustion region 10 is in the range of 800 to 1050 ° C. When the gas temperature in the secondary combustion region 10 is less than 800 ° C., the combustion of the unburned gas becomes insufficient and the CO in the exhaust gas increases. Moreover, when the gas temperature in the secondary combustion area | region 10 exceeds 1050 degreeC, the production | generation of clinker in the secondary combustion area | region 10 will be encouraged, and NOx will increase further.

<Distribution of oxygen amount ratio to achieve low air ratio combustion>
Next, the oxygen amount ratio distribution of the blown gas for realizing the low air ratio combustion in the waste incinerator of the present embodiment will be described.

  Ratio Q1 of the amount of oxygen (Y1) per unit time supplied by the primary combustion air blown from below the grate into the main combustion chamber with respect to the theoretical amount of oxygen (X) per unit time required for burning the waste = Y1 / X) and the ratio Q2 (= Y2 / X) of the amount of oxygen (Y2) per unit time supplied by the high-temperature gas blown into the region from the combustion start region in the combustion chamber to the front part of the post-combustion region And the ratio Q3 (= Y3 / X) of the amount of oxygen (Y3) per unit time supplied by the secondary combustion gas blown into the secondary combustion region is expressed by the following equations (11) and (12): Preferably, each gas is blown so as to satisfy the following expressions (13) and (14). Combustion at a lower air ratio with an air ratio of 1.3 or less by controlling the ratio of blowing each gas so that the following equations (13) and (14) are satisfied. Can be realized.

Q1: Q2: Q3 = 0.75 to 1.10: 0.05 to 0.40: 0.10 to 0.40 ……… (11)
1.0 ≦ Q1 + Q2 + Q3 ≦ 1.5 ………………………………………… (12)
Q1: Q2: Q3 = 0.80 to 1.0: 0.10 to 0.30: 0.10 to 0.30 ………… (13)
1.1 ≦ Q1 + Q2 + Q3 ≦ 1.3 ……………………………………… (14)
Here, the theoretical oxygen amount (X) per unit time required for the combustion of the waste is the combustion per unit mass of the waste determined from the properties and components of the waste put into the main combustion chamber. It is determined by the product (Nm ³ / hr) of the required oxygen amount (Nm ³ / kg) and the waste incineration rate (kg / hr) in the incinerator.

  The value of Q1 is a ratio of the oxygen amount per unit time (Y1) supplied by the combustion primary air supplied from below the grate into the main combustion chamber to the theoretical oxygen amount, and the combustion primary Adjust by increasing or decreasing the air flow rate. In addition, the value of Q2 is adjusted by increasing or decreasing the flow rate of the hot gas blown into the region from the combustion start region in the main combustion chamber to the front portion of the post-combustion region. The value of Q3 is adjusted by increasing or decreasing the flow rate of the secondary combustion gas blown into the secondary combustion region.

  In the following, Q1 + Q2 + Q3 is described as λ.

  By setting the above ratios Q1, Q2, and Q3 within the range of the above formula, low oxygen ratio combustion (1.0 ≦ λ ≦ 1.5) (ie, equivalent to low air ratio combustion) is performed in a waste incinerator. Even in this case, the generation amount of harmful gases such as CO and NOx can be reduced, and the total amount of exhaust gas discharged from the incinerator can be greatly reduced.

<Distribution of oxygen amount ratio to realize combustion at a lower air ratio (with an air ratio of 1.3 or less)>
More preferable distribution ratios that can achieve stable low air ratio combustion by suppressing the generation of unburned waste and harmful substances are as follows: Q1: Q2: Q3 = 0.90: 0.15: 015, λ Based on = 1.20, Q1, Q2, and Q3 are adjusted within the above range with λ in the range of 1.1 to 1.3 based on the composition and properties of the waste put into the incinerator.

  As described above, according to the present invention, a stable stagnation region or a circulation region can be formed in the vicinity of the waste layer in the combustion chamber by blowing high-temperature gas. Regardless of the size of the incinerator, even when low air ratio combustion with an air ratio of 1.5 or less is performed, the stability of combustion is maintained over the entire width direction and length direction in the combustion chamber, In addition, a waste incinerator and a waste incineration method in which the generation of NOx is suppressed by blowing high temperature gas from two stages of high temperature gas injection ports, and the generation amount of harmful gases such as CO and NOx can be reduced. Provided. Furthermore, since the combustion can be performed at a lower air ratio than before, the total amount of exhaust gas discharged from the incinerator can be further greatly reduced, and a waste incinerator and a waste incineration method that can improve the recovery efficiency of waste heat are provided. The

  In addition, the thermal decomposition of waste can be promoted by radiation of standing flat flames, etc., so the amount of waste supplied to the grate (grate load) and the amount of waste supplied to the combustion chamber (furnace Load) can be increased. For this reason, the volume of the combustion chamber can be reduced with respect to the amount of waste incineration, the furnace height of the incinerator can be reduced, and the waste incineration equipment can be made compact, thereby reducing the equipment cost and operation cost. be able to.

DESCRIPTION OF SYMBOLS 1 Waste incinerator 2 Combustion chamber 5a Dry grate 5b Combustion grate 5c Post combustion grate 13,15 High-temperature gas blowing means 24 Pre-stage high-temperature gas supply device 25 Post-stage high-temperature gas supply device

Claims (16)

A grate-type waste incinerator,
A combustion chamber comprising a grate and burning waste on the grate;
Primary air blowing means for blowing primary air for combustion into the combustion chamber from under the grate,
Hot gas blowing means for blowing the hot gas downward from the ceiling of the combustion chamber,
The high-temperature gas blowing means includes a first-stage and second-stage high-temperature gas injection port in the furnace length direction, which is a moving direction of waste on the grate, and a first-stage high-temperature gas injection port that supplies the first-stage high-temperature gas to the first-stage high-temperature gas injection port. A high-temperature gas supply means, and a latter-stage high-temperature gas supply means for supplying the latter-stage high-temperature gas to the latter-stage high-temperature gas inlet,
The front-stage high-temperature gas inlet is disposed at a position where the front-stage high-temperature gas is injected toward the region from the combustion start region to the main combustion region, and the rear-stage high-temperature gas inlet is the front of the rear-combustion region. Or it is arranged at a position to blow toward the area immediately after the burnout point,
The preceding high-temperature gas supply means and the latter-stage high-temperature gas supply means are arranged so that the oxygen concentration in the region from the combustion start region to the main combustion region is lower than the oxygen concentration in the post-combustion region. A grate-type waste incinerator characterized by controlling at least one of gas flow rate and oxygen concentration. A grate-type waste incinerator,
A combustion chamber comprising a grate and burning waste on the grate;
Primary air blowing means for blowing primary air for combustion into the combustion chamber from under the grate,
Hot gas blowing means for blowing the hot gas downward from the ceiling of the combustion chamber,
The high-temperature gas blowing means includes a first-stage and second-stage high-temperature gas injection port in the furnace length direction, which is a moving direction of waste on the grate, and a first-stage high-temperature gas injection port that supplies the first-stage high-temperature gas to the first-stage high-temperature gas injection port. A high-temperature gas supply means and a post-stage high-temperature gas supply means for supplying a post-stage high-temperature gas to a post-stage high-temperature gas injection port, and the front-stage high-temperature gas injection port is a region from the combustion start region to the main combustion region. Is disposed at a position where the rear-stage hot gas blowing port is disposed at a position where the rear-stage high-temperature gas is blown toward the front portion of the rear combustion region or the region immediately after the burnout point,
The front-stage high-temperature gas supply means and the rear-stage high-temperature gas supply means have an oxygen concentration in the region from the combustion start region to the main combustion region of 0 to 2 dry volume%, and an oxygen concentration in the post-combustion region of 5 to 8 dry volume%. Thus, the grate-type waste incinerator characterized by controlling at least one of the flow rate and oxygen concentration of each of the upstream and downstream hot gases. A grate-type waste incinerator,
A combustion chamber comprising a grate and burning waste on the grate;
Primary air blowing means for blowing primary air for combustion into the combustion chamber from under the grate,
Hot gas blowing means for blowing the hot gas downward from the ceiling of the combustion chamber,
The high-temperature gas blowing means includes a first-stage and second-stage high-temperature gas injection port in the furnace length direction, which is a moving direction of waste on the grate, and a first-stage high-temperature gas injection port that supplies the first-stage high-temperature gas to the first-stage high-temperature gas injection port. A high-temperature gas supply means and a post-stage high-temperature gas supply means for supplying a post-stage high-temperature gas to a post-stage high-temperature gas injection port, and the front-stage high-temperature gas injection port extends from the rear of the drying stage grate to the rear of the combustion stage grate Provided in the ceiling, and a rear hot gas inlet is provided in the ceiling from the rear part of the combustion stage grate to the front part of the rear combustion stage grate,
The preceding high-temperature gas supply means and the latter-stage high-temperature gas supply means are arranged so that the oxygen concentration in the region from the combustion start region to the main combustion region is lower than the oxygen concentration in the post-combustion region. A grate-type waste incinerator characterized by controlling at least one of gas flow rate and oxygen concentration. A grate-type waste incinerator,
A combustion chamber comprising a grate and burning waste on the grate;
Primary air blowing means for blowing primary air for combustion into the combustion chamber from under the grate,
Hot gas blowing means for blowing the hot gas downward from the ceiling of the combustion chamber,
The high-temperature gas blowing means includes a first-stage and second-stage high-temperature gas injection port in the furnace length direction, which is a moving direction of waste on the grate, and a first-stage high-temperature gas injection port that supplies the first-stage high-temperature gas to the first-stage high-temperature gas injection port. A high-temperature gas supply means and a post-stage high-temperature gas supply means for supplying a post-stage high-temperature gas to a post-stage high-temperature gas injection port, and the front-stage high-temperature gas injection port extends from the rear of the drying stage grate to the rear of the combustion stage grate Provided in the ceiling, and a rear hot gas inlet is provided in the ceiling from the rear part of the combustion stage grate to the front part of the rear combustion stage grate,
The front-stage high-temperature gas supply means and the rear-stage high-temperature gas supply means have an oxygen concentration in the region from the combustion start region to the main combustion region of 0 to 2 dry volume%, and an oxygen concentration in the post-combustion region of 5 to 8 dry volume%. Thus, the grate-type waste incinerator characterized by controlling at least one of the flow rate and oxygen concentration of each of the upstream and downstream hot gases. The pre-stage high-temperature gas supply means supplies, as the pre-stage high-temperature gas, a mixed gas or high-temperature air of return exhaust gas and high-temperature air in which a part of the exhaust gas discharged from the incinerator is returned,
5. The grate-type waste incinerator according to claim 1, wherein the rear-stage high-temperature gas supply means supplies the return exhaust gas or the mixed gas of the return exhaust gas and the high-temperature air as the rear-stage high-temperature gas. . The pre-stage hot gas supply means controls the oxygen concentration of the pre-stage hot gas to 12 to 21 dry volume%,
The grate-type waste incinerator according to any one of claims 1 to 5, wherein the latter-stage hot gas supply means controls the oxygen concentration of the latter-stage hot gas to 1 to 12 dry volume%. A secondary combustion chamber for secondary combustion of the gas discharged from the combustion chamber;
The pre-stage hot gas supply means controls the flow rate of the pre-stage hot gas to 6 to 18% of the amount of exhaust gas discharged from the secondary combustion chamber,
The grate according to any one of claims 1 to 6, wherein the post-stage hot gas supply means controls the flow rate of the post-stage hot gas to 15 to 30% of the amount of exhaust gas discharged from the secondary combustion chamber. Type waste incinerator. The front-stage hot gas supply means controls the hot gas injection flow rate so as to be within the range expressed by the following equation (1) in relation to the combustion chamber height, and the rear-stage hot gas supply means The grate-type disposal according to any one of claims 1 to 7, wherein the blowing flow velocity is adjusted so as to fall within a range represented by the following equation (2) in relation to the combustion chamber height: Incinerator.
0.0069X−1.3 ≦ Y ≦ 0.0153X−0.6 (1)
0.018X−1.0 ≦ Y ≦ 0.022X−0.4 (2)
Where X: combustion chamber height (mm)
Y: Hot gas blowing flow rate (m / sec) A waste incineration method using a grate-type waste incinerator with a combustion chamber,
Blow primary air for combustion into the combustion chamber from below the grate,
Among the hot gas inlets provided in the first stage and the second stage in the furnace length direction which is the moving direction of the waste on the grate on the ceiling of the combustion chamber,
From the upstream hot gas inlet, the upstream hot gas is injected toward the region from the combustion start region to the main combustion region, and from the downstream hot gas inlet, the downstream hot gas is fed to the front of the post combustion region or the burn-out point. The flow rate and oxygen of the upstream hot gas and the upstream hot gas are reduced so that the oxygen concentration in the region from the combustion start region to the main combustion region is lower than the oxygen concentration in the post combustion region. A waste incineration method characterized by controlling at least one of the concentrations. A waste incineration method using a grate-type waste incinerator with a combustion chamber,
Blow primary air for combustion into the combustion chamber from below the grate,
Among the hot gas inlets provided in the first stage and the second stage in the furnace length direction which is the moving direction of the waste on the grate on the ceiling of the combustion chamber,
From the upstream hot gas inlet, the upstream hot gas is injected toward the region from the combustion start region to the main combustion region, and from the downstream hot gas inlet, the downstream hot gas is fed to the front of the post combustion region or the burn-out point. The first stage high-temperature gas is blown toward the immediately following region so that the oxygen concentration in the region from the combustion start region to the main combustion region is 0 to 2 dry volume%, and the oxygen concentration in the post combustion region is 5 to 8 dry volume%. A waste incineration method characterized by controlling at least one of a flow rate and an oxygen concentration of each of the latter-stage hot gases. A waste incineration method using a grate-type waste incinerator with a combustion chamber,
Blow primary air for combustion into the combustion chamber from below the grate,
Of the high-temperature gas inlets provided on the ceiling of the combustion chamber in the furnace length direction, which is the moving direction of the waste on the grate, in the first stage and the second stage, from the rear part of the dry stage grate to the combustion stage grate Blowing high-temperature gas from the rear stage of the combustion stage grate to the front part of the rear combustion stage grate from the rear part of the combustion stage grate to the front part of the rear combustion stage grate. The flow rate of the upstream hot gas and the downstream hot gas is set so that the downstream hot gas is blown downward from the mouth and the oxygen concentration in the region from the combustion start region to the main combustion region is lower than the oxygen concentration in the downstream combustion region. And a method for incinerating waste, wherein at least one of oxygen concentration is controlled. A waste incineration method using a grate-type waste incinerator with a combustion chamber,
Blow primary air for combustion into the combustion chamber from below the grate,
Of the high-temperature gas inlets provided on the ceiling of the combustion chamber in the furnace length direction, which is the moving direction of the waste on the grate, in the first stage and the second stage, from the rear part of the dry stage grate to the combustion stage grate Blowing high-temperature gas from the rear stage of the combustion stage grate to the front part of the rear combustion stage grate from the rear part of the combustion stage grate to the front part of the rear combustion stage grate. The upstream high temperature gas is blown downward from the mouth, the oxygen concentration in the region from the combustion start region to the main combustion region is 0 to 2 dry volume%, and the oxygen concentration in the post combustion region is 5 to 8 dry volume%. A waste incineration method comprising controlling at least one of a flow rate and an oxygen concentration of each of a gas and a post-stage hot gas.   A mixed gas or high-temperature air of return exhaust gas and high-temperature air in which a part of the exhaust gas discharged from the incinerator is returned is blown as a pre-stage high-temperature gas, and a mixed gas or return exhaust gas of the return exhaust gas and high-temperature air is used as a post-stage high-temperature gas. The waste incineration method according to any one of claims 9 to 12, wherein blowing is performed.   14. The oxygen concentration of the first-stage high-temperature gas is controlled to 12 to 21 dry volume%, and the oxygen concentration of the second-stage high-temperature gas is controlled to 1 to 12 dry volume%. Grate-type waste incineration method. The grate-type waste incinerator has a secondary combustion chamber for secondary combustion of the gas discharged from the combustion chamber,
Adjust the flow rate of the pre-stage hot gas injected from the pre-stage high-temperature gas inlet to 6 to 18% of the exhaust gas amount discharged from the secondary combustion chamber,
The disposal according to any one of claims 9 to 14, wherein the flow rate of the latter-stage hot gas blown from the latter-stage hot gas inlet is adjusted to 15 to 30% of the amount of exhaust gas discharged from the secondary combustion chamber. Incineration method. The high-temperature gas blown from the high-temperature gas blow-in port at the rear stage is adjusted so that the flow velocity of the high-temperature gas blown from the high-temperature gas blow-in port at the front stage is within the range represented by the following equation (3) in relation to the combustion chamber height. The waste according to any one of claims 9 to 15, wherein the gas blowing flow rate is adjusted so as to fall within a range represented by the following equation (4) in relation to the combustion chamber height: Incineration method.
0.0069X−1.3 ≦ Y ≦ 0.0153X−0.6 (3)
0.018X−1.0 ≦ Y ≦ 0.022X−0.4 (4)
Where X: combustion chamber height (mm)
Y: Hot gas blowing flow rate (m / sec)

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