JP6183787B2 - Grate-type 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. Furthermore, unburned combustible gas contained in the combustion gas from the combustion chamber (referred to as unburned gas) receives and burns secondary combustion air in the secondary combustion chamber that is part of the waste heat boiler. (Called secondary combustion). After the secondary combustion, the combustion exhaust gas is recovered by a waste heat boiler.

  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. Because it becomes. 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 combusting at a low air ratio of 1.5 or less has been studied and disclosed in Patent Document 1. In this patent document 1, it is said that the following effects can be obtained by blowing high temperature gas into the combustion chamber from the ceiling of the combustion chamber of the waste incinerator.

  That is, promoting the thermal decomposition of waste by sensible heat and radiation of high temperature gas, promoting the combustion of combustible gas generated by thermal decomposition of waste by blowing high temperature gas containing oxygen, Gas is blown into the combustion chamber from the nozzle provided on the ceiling of the combustion chamber, and the flow of this high-temperature gas collides with the upward flow of combustible gas and combustion gas generated from waste, and the flow of gas flows directly above the waste layer. By forming a slow stagnation region, the flow of combustible gas becomes gentle, and the combustible gas is sufficiently mixed with the oxidant component, so that stable combustion is performed, and a flat flame is formed and kept standing. It is said that by burning high temperature gas into the combustion chamber, waste can be stably burned under low air ratio combustion operation.

  In such a grate-type waste incinerator, a dry region, a combustion start region, a main combustion region, and a post-combustion region are sequentially formed in the furnace from the upstream side in the waste movement direction. In the main combustion zone, the waste on the combustion grate is pyrolyzed and partially oxidized to generate a combustible gas, and the combustible gas and the solid content of the waste are combusted. When combustible gas burns, it forms a flame and burns. Thereafter, in the post-combustion region, unburned solids such as fixed carbon in the remaining waste are completely burned on the post-combustion grate. When solids burn, no flame is generated and soot burns.

  The main combustion region is a combustion region in which waste is thermally decomposed and partially oxidized to generate a combustible gas, and the combustible gas is combusted with a flame and the solid content of the waste is combusted. . The point at which combustion with a flame is substantially completed is called a burnout point, and becomes a boundary between the main combustion region and the post-combustion region. In the area after the burn-off point, a soot combustion area (post-combustion area) in which the unburned solid content in the waste is combusted.

JP2013-213652A

  In the combustion of waste in a waste incinerator, stable combustion of combustible gas generated by thermal decomposition of the waste suppresses the generation of harmful substances such as CO and NOx generated by the combustion. To make a big contribution. Therefore, in the waste incinerator described in Patent Document 1, high temperature gas is blown into the combustion chamber from a nozzle provided on the ceiling of the combustion chamber to stabilize combustion.

  According to such a waste incinerator of Patent Document 1, the high-temperature gas blown from the ceiling of the incinerator is increased in pyrolysis gas (combustible gas) and combustion gas generated by pyrolysis or combustion of waste. The counter flow field is effectively formed by colliding with the flow, and the stagnation region or the vertical circulation region is generated over a wide area. As a result, the flow of the combustible gas becomes gentle in the stagnation region or the circulation region, and stable combustion is performed. The flame is fixed in a flat shape, and an extremely stable combustion state is maintained.

  The waste incinerator of Patent Document 1 includes secondary combustion air blowing means for blowing secondary combustion air into the secondary combustion chamber, and the combustible gas contained in the gas discharged from the combustion chamber. Secondary combustion of unburned gas (unburned gas). In this way, combustion is stabilized by blowing high-temperature gas into the combustion chamber, and further, unburned gas is secondary-combusted in the secondary combustion chamber, so that oxygen, NOx, CO in exhaust gas discharged from the incinerator The concentration of NO is controlled within an appropriate range so that emission of harmful substances such as CO and NOx is less than the regulation value.

  In actual operation of a waste incinerator, even if it operates with standard operating standards, the combustion status in the incinerator may change and the amount of harmful substances in the exhaust gas discharged may change. Therefore, in the waste incinerator of Patent Document 1, secondary combustion air supply is performed based on a factor for monitoring the situation in the waste incinerator while maintaining the predetermined supply amounts of primary combustion air and high-temperature gas. The amount of harmful substances in the exhaust gas is controlled to be within a predetermined range by adjusting the amount to increase or decrease. By adopting such a combustion control method, even if the combustion status in the incinerator changes and the amount of harmful substances generated increases, the amount of harmful substances in the exhaust gas finally discharged from the waste incinerator is reduced. It is easy to control to be within a predetermined range, and furthermore, the combustion control system of the incinerator can be simplified. Here, as a factor for monitoring the situation in the waste incinerator, in Patent Document 1, for example, the exhaust gas in the vicinity of the outlet of the secondary combustion region where the secondary combustion of the unburned gas discharged from the combustion chamber is performed or in the boiler outlet It is preferable to use gas component concentrations of oxygen concentration, CO concentration, and NOx concentration.

  However, the combustion control method described in Patent Document 1 has the following problems. That is, the gas component concentration in the exhaust gas is measured with a gas concentration meter, but since a response time of the gas concentration meter is required, there is a time delay between the time when the combustion state in the incinerator changes and the time when the measured value is obtained. As a result, timely increase / decrease control of the secondary combustion air supply amount may not be possible with respect to fluctuations in the actual combustion state in the incinerator.

  In view of such circumstances, the present invention can stably perform the combustion of waste in a waste incinerator that blows high-temperature gas from the furnace ceiling, and can suppress the generation amount of harmful substances such as CO and NOx. Grate-type waste incinerator and waste incineration method that can perform air ratio combustion operation without problems and that can realize timely combustion control against fluctuations in the actual combustion state in the incinerator It is an issue to provide.

  According to the present invention, the above-described problems are solved by the following configuration regarding the grate-type waste combustion furnace and the waste incineration method.

<Grate-type waste incinerator>
A grate-type waste incinerator comprising a grate and a combustion chamber for burning waste on the grate, and primary air blowing means for blowing primary air for combustion into the combustion chamber from under the grate And a high temperature gas blowing means for blowing high temperature gas downward from the ceiling of the combustion chamber, wherein the high temperature gas blowing means is a furnace in which the waste moves on the grate A hot gas inlet provided on the ceiling of the combustion chamber at a plurality of longitudinal positions, a hot gas supply means for supplying the hot gas to the hot gas inlet, a combustion chamber temperature measuring means for measuring the temperature in the combustion chamber, Grate-type disposal characterized by comprising high-temperature gas injection control means for controlling the amount of oxygen supplied by the high-temperature gas so that the temperature in the combustion chamber is kept within a predetermined range based on the measured value measured by the temperature measurement means in the combustion chamber Incineration Furnace.

In the present invention, the high temperature gas supply means is provided to supply a mixed gas of the return exhaust gas and the high temperature air, in which a part of the exhaust gas discharged from the incinerator is returned, as a high temperature gas,
Control of the amount of oxygen supplied by the high-temperature gas can control at least one of the flow rate of high-temperature gas supplied to the combustion chamber, the amount of high-temperature air to be mixed, and the amount of return exhaust gas to be mixed.

<Waste incineration method>
A combustion chamber provided with 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, and hot gas from the ceiling of the combustion chamber In a waste incineration method using a grate-type waste incinerator having a high-temperature gas blowing means that blows downward, it is provided on the combustion chamber ceiling at a plurality of positions in the furnace length direction, which is the direction of movement of the waste on the grate. The amount of oxygen supplied by the high-temperature gas so that the temperature in the combustion chamber is kept within a predetermined range based on the measured value of the temperature in the combustion chamber measured by the temperature measuring means in the combustion chamber. A waste burning method using a grate-type waste incinerator characterized by controlling

  In the present invention, a mixed gas of return exhaust gas and high-temperature air in which a part of the exhaust gas discharged from the incinerator is returned is supplied to the combustion chamber as a high-temperature gas, and the amount of oxygen supplied by the high-temperature gas is supplied to the combustion chamber It can be controlled by at least one of a high-temperature gas flow rate, a high-temperature air amount to be mixed, and a return exhaust gas amount to be mixed.

  If the temperature in the combustion chamber is within the predetermined range, the combustion of the waste in the combustion chamber is stably performed in a favorable state, the amount of harmful substances generated is small, and the concentration of the harmful substances in the exhaust gas is within the allowable range. However, if the type or amount of waste supplied to the incinerator fluctuates, the combustion of the waste may deviate from the preferable state, and as a result, the temperature in the combustion chamber is within the predetermined range. There are times when it comes off. According to the present invention, when the temperature in the combustion chamber is out of the predetermined range, the following countermeasures are taken in order to bring combustion into a preferable state. That is, when the temperature in the combustion chamber is lower than the predetermined range, it indicates that the combustion is inactive and the combustible gas generated by the thermal decomposition of the waste is not sufficiently burned, Since a large amount of CO remains and the CO concentration in the exhaust gas increases, the amount of oxygen supplied by the high-temperature gas is controlled to activate combustion, and the temperature in the combustion chamber is higher than the predetermined range. Occasionally, combustion is overactive, indicating that a high temperature field is generated, and the amount of NOx generated increases and the NOx concentration in the exhaust gas increases, so the amount of oxygen supplied by the high temperature gas And control to slow down combustion.

  As described above, in the present invention, in the grate-type waste incinerator that blows high-temperature gas into the combustion chamber from the furnace ceiling and the waste incineration method, the temperature in the combustion chamber is a predetermined range indicating that the combustion is appropriate. As described above, since the amount of oxygen supplied to the combustion chamber is controlled by blowing high temperature gas, the combustion chamber is maintained so that proper combustion is performed, and the amount of harmful substances generated by combustion is small. The concentration of harmful substances in the exhaust gas is within the allowable range. In addition, the measurement target for monitoring the combustion status is the combustion chamber temperature, and the operation target for temperature control is the amount of oxygen supplied to the combustion chamber, so there is no delay from measurement to control and extremely smooth control is possible. Made.

  In the present invention, since the high temperature gas is blown from the ceiling of the combustion chamber, the following effects are obtained.

[Combustion stabilization effect by high-temperature gas injection]
Combustion generated by thermal decomposition of waste can be promoted by injecting hot gas downward from the blow-off port provided on the ceiling of the waste incinerator combustion chamber, and sensible heat and radiation of the high-temperature gas can accelerate the thermal decomposition of the waste. In addition, the downward flow of the hot gas and the upward flow of the combustible gas generated from the waste layer collide with the upward flow of the combustion gas, and the gas flow directly above the waste layer. Can be formed over a wide range in the width direction and the length direction of the combustion chamber, so that stable 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.

  As described above, by blowing high temperature gas, for example, even in low air ratio combustion where the air ratio is 1.5 or less, waste and generated combustible gas can be stably burned and discharged from the waste incinerator. The amount of harmful substances such as CO and NOx in the exhaust gas generated can be suppressed. 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 and operating costs can be reduced by making the furnace compact.

BRIEF DESCRIPTION OF THE DRAWINGS The schematic structure of the waste incinerator which concerns on one Embodiment of this invention is shown, (A) is a longitudinal cross-sectional view in the furnace length direction. It is sectional drawing of the furnace width direction explaining the combustion state in the waste incinerator shown in FIG.

  Embodiments of the present invention will be described below with reference to the accompanying drawings. 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.

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

<Basic configuration of grate-type incinerator>
FIG. 1 shows a schematic configuration of 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 (furnace length 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.

  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 waste flow direction of the combustion chamber 2, and throws the waste into the combustion chamber 2. It is a grate-type incinerator provided with a waste charging port 3 and a waste heat boiler 4 provided continuously above the downstream side (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. A waste layer W is formed on the lattice 5b.

  In the dry grate 5a, waste is mainly dried and ignited. In the combustion grate 5b, waste is thermally decomposed and partially oxidized, and the combustible gas and solid matter generated by the thermal decomposition are combusted. When the combustible gas burns, a flame is formed. On the post-combustion grate 5c, the unburned solids in the remaining waste are completely burned. When the solids in the waste burn, no flame is generated and the soot burns. The combustion ash after complete combustion is discharged from the ash drop opening 6.

  In the incinerator of this embodiment, the following regions are formed in the space in the combustion chamber 2 and in the space immediately above the waste layer.

  A dry region A1 is formed above the upstream range (front part) of the dry grate 5a in the waste flow direction, which is positioned directly above the dry grate 5a and below the waste input port 3. Is done.

  A combustion start region A2 is formed above the upstream range (front part) of the combustion grate 5b from the downstream range (rear part) 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, the main combustion region A3 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 A4 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 area A2 is an area 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 A3 is a combustion in which waste is thermally decomposed and partially oxidized to generate a combustible gas, and the combustible gas is combusted with a flame and the solid content of the waste is combusted. This is an area up to the point where the combustion with the flame is completed (burn-off point). In the area after the burnout point, the soot combustion area (post-combustion area A4) in which the solid unburned matter in the waste is combusted.

  The dry region A1, the combustion start region A2, the main combustion region A3, and the post-combustion region A4 will be described later again.

  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 P supplied by the blower 8 is supplied to the wind boxes 7a, 7b, 7c and 7d through the combustion primary air supply pipe 9, and combusts through the fire grates 5a, 5b and 5c. It is supplied into the chamber 2. The primary combustion air P supplied from below the grate is used for drying and burning the 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 an outlet on the downstream side of the combustion chamber 2, and an unburned portion (unburned gas) of the combustible gas in the gas discharged from the combustion chamber 2 near the inlet of the waste heat boiler 4. It becomes the secondary combustion area | region 10 which burns. 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 blows primary air into the combustion chamber from below the grate as follows. Means, high temperature gas injection means provided with hot gas injection ports at a plurality of positions in the furnace length direction on the ceiling of the combustion chamber, and high temperature gas injection means for injecting high temperature gas downward from the high temperature gas injection port, and further, an inlet portion of the waste heat boiler And a secondary combustion gas supply means for supplying a secondary combustion gas to the secondary combustion chamber.

<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. The primary air supply system passes the primary air P from the air supply source through the primary air supply pipe 9 for combustion, and the wind boxes 7a, 7b, 7c of the dry grate 5a, the combustion grate 5b, and the post-combustion grate 5c, respectively. , 7d from the branch supply pipe, and the combustion primary air supply 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 high temperature gas blowing means for blowing high temperature gas downward from the ceiling 2 </ b> A of the combustion chamber 2. The hot gas blowing means is provided with hot gas blowing ports 13 (13a, 13b, 13c, 13d, 13e) on the ceiling 2A of the combustion chamber at a plurality of positions in the furnace length direction, which is the moving direction of waste on the grate 5. Moreover, the hot gas inlet 13 is provided in the ceiling 2A from the rear part of the drying grate 5a to the front part of the rear combustion grate 5c in the furnace length direction. The high-temperature gas blowing means further controls the high-temperature gas supply device 24 that supplies high-temperature gas to the high-temperature gas blow-in port 13, a pipe that guides the high-temperature gas to the high-temperature gas blow-in port 13, and the high-temperature gas supply device 24. A hot gas blowing control device 22 is provided, and the hot gas supply device 24 has a damper 14 as a flow rate adjusting mechanism.

  The direction of the hot gas blowing port 13 is determined so that the hot gas is blown downward. Thus, the high temperature gas is provided from the high temperature gas inlet 13 so as to blow from the dry region A1 toward the front region of the post combustion region A4. Moreover, the hot gas from the hot gas blowing port 13e located on the most downstream side may be blown toward the region immediately after the fuel cut point.

  The hot gas inlet 13 is provided at a plurality of locations in the furnace width direction (a direction perpendicular to the paper surface in FIG. 1 and a left-right direction in FIG. 2).

  The hot gas supply device 24 mixes return exhaust gas and hot air to prepare a hot gas, and supplies the hot gas to the hot 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 hot gas supply device 24 adjusts the mixing ratio by adjusting the flow rates of the return exhaust gas and the hot air to adjust the temperature and oxygen concentration of the hot gas. Moreover, the high temperature gas supply device 24 may supply only high temperature air or only return exhaust gas as a high temperature gas.

  In the present embodiment, when preparing the high temperature gas by mixing the return exhaust gas and the high temperature air in the high temperature gas supply device 24, the mixing ratio is adjusted by adjusting the respective flow rates of the return exhaust gas and the high temperature air. The amount of oxygen supplied by the high temperature gas into the combustion chamber 2 can be adjusted by adjusting at least one of adjusting the oxygen concentration in the gas and adjusting the flow rate of the high temperature gas with the damper 14.

  The high temperature gas supplied from the high temperature gas supply means preferably has an oxygen concentration of 5 to 21 dry volume%, more preferably 12 to 21 dry volume%.

<High-temperature gas injection control device>
In this embodiment, it has combustion chamber temperature measuring means 16 for measuring the temperature in the combustion chamber, and a hot gas injection control device 22 for controlling the hot gas supply device 24 in response to a signal from the combustion chamber temperature measuring means 16. ing. In the combustion chamber 2, the furnace temperature changes in the furnace length direction in the range from the drying region A1 to the post-combustion region A4 in the furnace, and the combustion chamber temperature is measured in the main combustion region A3 where combustion is most conspicuous. Combustion chamber temperature measuring means 16 is provided. The combustion chamber temperature measuring means 16 is formed of, for example, a thermocouple, and is attached to side walls located at both ends in the furnace width direction in the main combustion region A3.

  The hot gas injection control device 22 receives the signal from the combustion chamber temperature measuring means 16 and controls the hot gas supply device 24 so that the combustion gas is burned by the hot gas supply device 24 so that the temperature in the combustion chamber falls within a predetermined range. The amount of oxygen supplied by the hot gas blown into the chamber is controlled. When the temperature in the combustion chamber is lower than the predetermined range, it indicates that the combustion is inactive and the combustion of the combustible gas is not sufficiently performed. Therefore, when the combustion chamber temperature is higher than the predetermined range, the combustion is overactive and the temperature is high. As the NOx generation amount increases and the NOx concentration in the exhaust gas rises, the amount of oxygen supplied by the high-temperature gas is reduced and the combustion is slowed down. To do.

  In the present embodiment, when preparing the high temperature gas by mixing the return exhaust gas and the high temperature air in the high temperature gas supply device 24, the mixing ratio is adjusted by adjusting the respective flow rates of the return exhaust gas and the high temperature air. The high temperature gas supplied into the combustion chamber 2 by adjusting the oxygen concentration therein or by adjusting the flow rate of the high temperature gas by adjusting the opening of the damper 14 provided in the pipe for feeding the high temperature gas Adjust the amount of oxygen.

<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 waste heat boiler 4. The secondary combustion gas supply system feeds the secondary combustion gas Q from the secondary combustion gas supply source to the secondary combustion gas inlet 17 provided in the secondary combustion region 10 via the pipe 12. The pipe 12 is provided with a blower 18 and a damper 19 as a flow rate adjusting mechanism. The secondary combustion gas inlet 17 is provided on the peripheral wall of the waste heat boiler 4 so as to blow the secondary combustion gas (combustion secondary air) Q into the secondary combustion region 10 in the vicinity of the inlet of the waste heat boiler 4. Is provided. Most of the combustible gas generated in the combustion chamber 2 is combusted in the combustion chamber 2, and the remaining unburned gas corresponds to the vicinity of the inlet of the waste heat boiler 4 connected above the post-combustion grate 5c. The gas flows into the secondary 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. of the incinerator. Can be selected. In the present invention, the secondary combustion gas supply system is not essential.

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

<Overview of incineration>
First, when waste is input into the waste input port 3, the dropped waste is supplied into the combustion chamber 2 by a waste supply device (not shown) and deposited on the dry grate 5a. The operation moves on the combustion grate 5b and onto the post-combustion grate 5c, and forms a layer of waste W 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 A1 is formed above the upstream range (front part) of the dry grate 5a in the waste flow direction. A combustion start region A2 is formed above the upstream range (front part) of the combustion grate 5b from the downstream range (rear part) 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 main combustion region A3 is formed above the combustion grate 5b. This combustion region is a region up to a point (combustion point) where combustion with a flame is completed. 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-off point, the solid unburned portion (char) in the waste is burned, and a post-combustion region A4 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 Q, 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.

<High-temperature gas injection control>
Based on the measured value in the combustion chamber temperature measured by the combustion chamber temperature measuring means 16 for measuring the temperature in the combustion chamber of the incinerator, the temperature in the combustion chamber is supplied within the predetermined range using the high temperature gas as follows. Control the amount of oxygen to be used.

  As described above, if the temperature in the combustion chamber is within the predetermined range, the combustion of the waste in the combustion chamber is stably performed in a preferable state, the amount of harmful substances generated is small, and the concentration of the harmful substances in the exhaust gas is low. Indicates that it is within the allowable range, but if the type or amount of waste supplied to the incinerator fluctuates, the combustion of the waste may deviate from the preferred state. The room temperature may deviate from the predetermined range. That is, the quality of combustion in the combustion chamber can be determined by whether or not the temperature in the combustion chamber is within a predetermined range.

  Therefore, in the present embodiment, when the combustion state in the combustion chamber varies due to fluctuations in the amount and quality of waste supplied to the incinerator, the temperature in the combustion chamber also changes. When the value is out of the predetermined range, the combustion is controlled to be in a preferable state.

  That is, when the temperature in the combustion chamber is lower than the predetermined range, it indicates that the combustion is inactive and the combustible gas generated by the thermal decomposition of the waste is not sufficiently burned, Since a large amount of CO remains and the CO concentration in the exhaust gas increases, the amount of oxygen supplied by the high-temperature gas is increased to control the combustion to be activated. In order to increase the amount of oxygen, at the time of preparing the high temperature gas by mixing the return exhaust gas and the high temperature air in the high temperature gas supply device 24, at least of reducing the return exhaust gas amount and increasing the high temperature air amount. Doing one, changing the quantity ratio of both, increasing the oxygen concentration of the high temperature gas, or increasing the opening of the damper 14 to increase the supply amount of the high temperature gas, the high temperature gas into the combustion chamber Increase the amount of oxygen supplied. Furthermore, the oxygen supply amount may be increased by adjusting both the high temperature gas supply device 24 and the damper 14.

  Next, when the temperature in the combustion chamber is higher than the predetermined range, this indicates that combustion is overactive and a high temperature field is generated, and the amount of NOx generated increases and the NOx concentration in the exhaust gas increases. Therefore, the amount of oxygen supplied by the high-temperature gas is decreased, and the combustion is controlled to slow down. In order to reduce the oxygen amount, at the time of preparing the high temperature gas by mixing the return exhaust gas and the high temperature air in the high temperature gas supply device 24, at least of increasing the return exhaust gas amount and decreasing the high temperature air amount. Doing one and changing the quantity ratio between them to reduce the oxygen concentration of the high temperature gas, or reduce the opening of the damper 14 to reduce the supply amount of the high temperature gas. Reduce the amount of oxygen supplied. Furthermore, it is good also as adjusting both the hot gas supply apparatus 24 and the damper 14, and reducing oxygen supply amount.

  Further, when the temperature in the combustion chamber is within the predetermined range, the combustion in the combustion chamber is being performed satisfactorily, so the hot gas supply device 24 and the damper 14 are maintained as they are without adjustment.

<Blowing primary air for combustion>
The primary air P 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 P 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 a command from the fuel cut point position control means. Based on the above, the flow rate supplied to each wind box 7a, 7b, 7c, 7d is adjusted by the dampers 7a-1 to 7d-1 provided in the respective supply pipes that are branched from each wind box. Further, the configurations of the air boxes 7a, 7b, 7c, 7d and the combustion primary air supply pipe 9 for supplying the combustion primary air P are not limited to those shown in the figure, but the incinerator scale, shape, application, etc. Can be appropriately selected.

  As the primary air P 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 dry volume%. As the primary air P for combustion, any one 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, hot gas is blown from the hot gas inlet 13 (13a, 13b, 13c, 13d, 13e) from the dry region A1 toward the front region of the post-combustion region A4 and discarded. It is blown downward toward the material layer W.

  The hot gas is blown downward by blowing the hot gas downward into the region from the drying region A1 in the combustion chamber 2 to the front portion of the post-combustion region A4 and directly above the waste layer W from the hot gas blowing port 13. The high-temperature gas opposes the upward flow of combustible gas and combustion gas generated by thermal decomposition and partial oxidation of waste, and both gas flows collide with each other. A region or a circulation region that circulates in the vertical direction is generated. 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.

  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. In addition, the combustion of the combustible gas generated by the thermal decomposition of the waste is promoted by blowing in the high-temperature gas containing oxygen.

  Thus, the waste W can be stably burned even under the low air ratio combustion operation. As a result, it is possible to suppress the generation of harmful substances such as CO, NOx, and dioxins even in low air ratio combustion. For this reason, low air ratio combustion can be performed without hindrance.

  Next, the preparation of the high-temperature gas, the blowing port, the blowing flow rate, and the blowing of the secondary combustion gas will be sequentially described.

<Preparation of hot gas>
The temperature of the hot gas blown from the hot gas blowing port 13 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.

  Moreover, it is preferable that the oxygen concentration of the high temperature gas blown from the high temperature gas blowing port 13 is adjusted to 5 to 21 dry volume%, more preferably 12 to 21 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 high-temperature gas in the above range are as follows. If the oxygen concentration of the high-temperature gas is lower than the lower limit, the region from the drying region A1 to the main combustion region A3 becomes excessively low-oxygen atmosphere due to the blowing of the high-temperature gas, and the amount of combustible gas generated by the thermal decomposition of the waste is Excessive amount of unburned gas (unburned gas) in the combustible gas that flows into the secondary combustion area without being burned in the combustion chamber is unsuitable, and is unsuitable. If the oxygen concentration is higher than the upper limit, flammable This is unsuitable because high temperature field is generated due to excessive combustion of the gas and the amount of NOx generated is unsuitable. Therefore, the oxygen concentration of the high temperature gas is preferably 5 to 21 dry volume%, and the above problem occurs when the oxygen concentration is 12 to 21 dry volume%. Is more preferable because it can be surely avoided.

  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 high-temperature gas so that the high-temperature gas has the gas temperature and oxygen concentration described above. It is done. 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.

<High temperature gas inlet>
The hot gas inlet 13 is provided at a position directly above the grate in the range from the dry grate 5a to the upstream side (front part) in the moving direction of the rear combustion grate 5c on the ceiling of the combustion chamber 2.

  A plurality of hot gas inlets 13 are arranged in the width direction of the combustion chamber 2. The hot gas inlet 13 may be a nozzle type or a slit type.

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

  In FIG. 1, the hot gas is blown downward from the hot gas blowing port 13 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.

  When there are a plurality of high-temperature gas injection ports 13, the high-temperature gas does not necessarily have to be injected from each of the high-temperature gas injection ports 13 at an equal flow rate, and the scale, shape, application, waste property, quantity, waste layer thickness of the incinerator For example, the flow velocity of each high-temperature gas blow-in port 13 can be appropriately changed so as to be different.

  By blowing the hot gas downward from the blow-off port provided on the ceiling of the waste incinerator combustion chamber, the downward flow of the hot gas and the upward flow of combustible gas and combustion gas generated from the waste layer It is possible to form a stagnation region where the gas flow stagnates just above the waste layer or circulates in the vertical direction over the waste layer over a wide range in the combustion chamber width direction and furnace length direction. Regardless of the size of the incinerator, that is, the width and height of the combustion chamber, waste and combustible gas generated even in low air ratio combustion with an air ratio of 1.5 or less Can be burned stably. 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.

  When there are a plurality of high-temperature gas injection ports 13 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 high-temperature gas injection port 13 at an equal flow rate. Depending on the use or waste properties, amount, waste layer thickness, and the like, the flow rate of blow from each hot gas blow-in port 13 can be appropriately changed.

<Injection of secondary combustion gas>
The secondary combustion gas Q 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 dry volume%. As the secondary combustion gas Q, 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 Q in the direction in which the swirling 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 Q, only the secondary air for combustion supplied by the blower, the gas adjusted by adjusting the oxygen concentration by mixing the diluent with the secondary air for combustion after the blower is supplied, and 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.

  As described above, according to the present invention, the combustion chamber temperature, which is an index of the combustion state in the combustion chamber, is supplied to the combustion chamber by blowing high-temperature gas so as to be within a predetermined range indicating that the combustion state is appropriate. Since the amount of oxygen to be controlled is controlled, the combustion chamber is maintained so that proper combustion is performed, the amount of harmful substances generated by the combustion is suppressed, and the concentration of harmful substances in the exhaust gas falls within an allowable range. In addition, the measurement target for monitoring the combustion status is the combustion chamber temperature, and the operation target for temperature control is the amount of oxygen supplied to the combustion chamber, so there is no delay from measurement to control and extremely smooth control is possible. Made.

  Furthermore, 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 into the combustion chamber, and the planar combustion region can be fixed and disposed of. 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 and length of the combustion chamber. A waste incinerator and a waste incineration method capable of reducing the generation amount of harmful gases such as CO and NOx are 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 5 Grate 5a Dry grate 5b Combustion grate 5c Post combustion grate 13 (13a, 13b, 13c, 13d, 13e) Hot gas injection port 16 Combustion chamber temperature measurement means 22 High temperature gas injection Control device 24 Hot gas supply device

Claims (4)

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,
In a grate-type waste incinerator having hot gas blowing means for blowing hot gas downward from the ceiling of the combustion chamber,
The hot gas blowing means includes a hot gas blowing port provided on the ceiling of the combustion chamber at a plurality of positions in the furnace length direction, which is a moving direction of waste on the grate, and a high temperature gas for supplying the hot gas to the hot gas blowing port. A gas supply means, and a combustion chamber temperature measuring means for measuring a temperature of a main combustion region in which the waste in the combustion chamber is pyrolyzed and partially oxidized to generate a combustible gas and the combustible gas and the solid content of the waste are combusted ; A high-temperature gas injection control means for controlling the amount of oxygen supplied by the high-temperature gas so that the temperature of the main combustion region in the combustion chamber is within a predetermined range based on the measurement value measured by the temperature measurement means in the combustion chamber;
The high-temperature gas supply means is configured so that the flow rates of the high-temperature gas blown from the respective high-temperature gas blowing ports provided at a plurality of positions in the furnace length direction are different from each other.
When the temperature measurement value in the main combustion region is lower than the predetermined range, the high temperature gas blowing control means determines that the combustion is inactive and the combustible gas containing CO is not sufficiently burned, and the high temperature gas Increases the amount of oxygen supplied by the gas to activate the combustion in the main combustion region, sufficiently burns the combustible gas, suppresses the increase in the CO concentration in the exhaust gas due to the remaining CO, and combustion When the hot gas supply means is controlled so that the temperature of the indoor main combustion region is within a predetermined range, and the temperature measurement value of the main combustion region is higher than the predetermined range, combustion is overactive and a high temperature field is generated. Reducing the amount of oxygen supplied by the high-temperature gas and slowing down combustion in the main combustion region, suppressing the generation of high-temperature fields, and increasing the amount of NOx generated increases the NOx concentration in the exhaust gas The main combustion in the combustion chamber Grate type waste incinerator characterized that you control the hot gas supply means to the temperature of the region within a predetermined range. The high temperature gas supply means is provided to supply a mixed gas of the return exhaust gas and the high temperature air, in which a part of the exhaust gas discharged from the incinerator is returned, as a high temperature gas,
Hot gas blower control means performs control of supplying oxygen by the high temperature gas, the hot gas flow rate supplied to the combustion chamber, the hot air volume to be mixed, by controlling at least one of the return amount of exhaust gas to be mixed,
The high temperature gas blowing control means reduces the return exhaust gas amount when preparing the high temperature gas by mixing the return exhaust gas and the high temperature air in the high temperature gas supply means when increasing the amount of oxygen supplied by the high temperature gas. At least one of increasing the amount of high-temperature air and changing the quantity ratio of both to increase the oxygen concentration of the high-temperature gas and at least one of increasing the supply amount of the high-temperature gas, When increasing the amount of oxygen supplied by the high temperature gas and decreasing the amount of oxygen supplied by the high temperature gas, the amount of the return exhaust gas is reduced when preparing the high temperature gas by mixing the return exhaust gas and the high temperature air by the high temperature gas supply means. At least one of increasing and decreasing the amount of hot air is performed, and the quantity ratio of both is changed to reduce the oxygen concentration of the hot gas, and the supply of the hot gas. By at least one of reducing the amount, grate type waste incinerator of claim 1, Ru reduce the amount of oxygen supplied by the hot gas into the combustion chamber. A combustion chamber provided with 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, and hot gas from the ceiling of the combustion chamber In a waste incineration method using a grate-type waste incinerator having a hot gas blowing means for blowing downward,
A hot gas supply step you supplied from the hot gas blowing port provided on the ceiling of the combustion chamber at a plurality of positions of the furnace length direction is the moving direction of the waste on the grate of the hot gas into the combustion chamber,
Based on the measured value of the temperature in the main combustion area where the waste in the combustion chamber is pyrolyzed and partially oxidized to generate combustible gas and the combustible gas and the solid content of the waste are combusted. A high-temperature gas injection control step for controlling the amount of oxygen supplied by the high-temperature gas so that the temperature of the main combustion region in the combustion chamber is within a predetermined range ;
In the high temperature gas supply process, the flow rates of the high temperature gas blown from the respective high temperature gas injection ports provided at a plurality of positions in the furnace length direction are different from each other.
The high temperature gas injection control step determines that the combustion is inactive and the combustible gas containing CO is not sufficiently burned when the temperature measurement value in the main combustion region is lower than the predetermined range, and the high temperature gas Increases the amount of oxygen supplied by the gas to activate the combustion in the main combustion region, sufficiently burns the combustible gas, suppresses the increase in the CO concentration in the exhaust gas due to the remaining CO, and combustion When the temperature of the indoor main combustion region is within a predetermined range and the measured temperature value of the main combustion region is higher than the predetermined range, it is determined that combustion is overactive and a high temperature field is generated, and is supplied by a high temperature gas. Reducing the amount of oxygen generated and slowing down combustion in the main combustion region, suppressing the generation of high-temperature fields, suppressing the increase in NOx concentration in the exhaust gas due to the increase in NOx generation amount, and the main combustion region in the combustion chamber to a temperature within a predetermined range Waste combustion process according grate type waste incinerator characterized. In the high temperature gas supply process, a mixed gas of the return exhaust gas and the high temperature air in which a part of the exhaust gas discharged from the incinerator is returned is supplied to the combustion chamber as a high temperature gas,
In the hot gas blowing control step, the amount of oxygen supplied by the hot gas is controlled by at least one of the flow rate of hot gas supplied to the combustion chamber, the amount of hot air to be mixed, and the amount of return exhaust gas to be mixed and supplied by the hot gas. When increasing the amount of oxygen, at least one of reducing the amount of return exhaust gas and increasing the amount of hot air when preparing the high temperature gas by mixing the return exhaust gas and high temperature air in the high temperature gas supply process. The amount of oxygen supplied by the high temperature gas into the combustion chamber is increased by at least one of increasing the oxygen concentration of the high temperature gas by changing the quantity ratio between the two and increasing the supply amount of the high temperature gas. When reducing the amount of oxygen supplied by gas, increase the amount of return exhaust gas when preparing the high temperature gas by mixing the return exhaust gas and high temperature air in the high temperature gas supply process. At least one of reducing the amount of hot air and changing the quantity ratio of the two to reduce the oxygen concentration of the hot gas and at least one of reducing the amount of hot gas supplied , waste combustion process according grate type waste incinerator according to claim 3, Rukoto reduces the amount of oxygen supplied by the hot gas into the combustion chamber.

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