JP2016186382A - Fire grate type waste incinerator and waste incineration method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a fire grate type waste incinerator and a waste incineration method that can stably combust waste.SOLUTION: A fire grate type waste incinerator comprises: a combustion chamber 2 for combusting waste on a fire grate 5; a secondary combustion chamber 10 for secondarily combusting combustible gas from the combustion chamber; primary air blowing means 7a-7c and 9 for blowing primary air for combustion into the combustion chamber from below the fire grate; hot gas blowing means 21 and 23 for blowing hot gas H into the combustion chamber; and secondary combustion air blowing means 12 and 17 provided in a gas outlet of the combustion chamber to blow secondary combustion air. The hot gas blowing means comprises: hot gas blowing ports 13a and 13b provided in a ceiling 2A of the combustion chamber; hot gas supply means 21 and 23 for supplying the hot gas to the hot gas blowing ports; monitoring means 31 for monitoring a flame visual recognition situation in the combustion chamber; and hot gas blowing control means 20 for controlling the amount of oxygen to be supplied by the hot gas from the hot gas blowing means on the basis of a flame visual recognition situation signal from the monitoring means.SELECTED DRAWING: Figure 1

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 hindrance with a reduced air ratio in a grate-type waste incinerator, the amount of exhaust gas will be reduced, and the exhaust gas treatment facility will be compact. As a result, the entire waste incineration facility will be The equipment cost can be reduced by downsizing. 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, the amount of CO generated increases, the flame temperature rises locally, NOx increases rapidly, and a large amount of soot is generated. As a result, there is a problem that harmful substances in the exhaust gas increase, and waste and ash are melted and adhered to the furnace wall due to local high temperatures, and clinker is generated. There is a problem of shortening.

  Under such circumstances, a grate-type waste incinerator that can stably burn at a low air ratio of 1.5 or less has been studied, and is disclosed in Patent Document 1. . According to Patent Document 1, the following effects are obtained by blowing high temperature gas into the combustion chamber from the ceiling of the combustion chamber of the grate-type 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, high-temperature gas blown from the ceiling of the incinerator is
It collides with the upward flow of pyrolysis gas (combustible gas) generated by pyrolysis or combustion of waste and combustion gas, effectively forms a counter flow field, and the stagnation region or the vertical circulation region covers a wide area Will be generated. 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 burn waste in a grate-type waste incinerator that blows high-temperature gas from the furnace ceiling, and suppresses the generation of harmful substances such as CO and NOx. It is possible to perform low-air ratio combustion operation without any problems, and furthermore, a grate-type waste incinerator and waste that can realize timely combustion control against fluctuations in the actual combustion state in the incinerator It is an object to provide a method for incineration.

  In the present invention, the above-described problems are solved by a waste incineration method using a grate-type waste incinerator or a grate-type waste incinerator configured as follows.

  When incomplete combustion occurs during the combustion of waste in the combustion chamber of a grate-type waste incinerator, the amount of carbon monoxide generated increases and exceeds the regulation value when exhaust gas is released into the atmosphere. The inventors focused on the fact that soot is generated in the combustion chamber during incomplete combustion, and it becomes impossible to grasp the combustion status by visually observing the flame in the combustion chamber from the outside of the furnace. We have come up with a grid-type waste incinerator and waste incineration method.

<Grate-type waste incinerator>
A grate-type waste incinerator according to the present invention includes a combustion chamber that includes a grate and burns waste on the grate, and is connected to the combustion chamber to secondary-combust combustible gas from the combustion chamber. A primary combustion chamber, primary air blowing means for blowing combustion primary air from under the grate into the combustion chamber, hot gas blowing means for blowing hot gas downward from the ceiling of the combustion chamber, and a gas outlet of the combustion chamber In the grate-type waste incinerator having a secondary combustion air blowing means for blowing secondary combustion air, the hot gas blowing means includes a hot gas blowing port provided on a ceiling of the combustion chamber, and a hot gas blowing High temperature gas supply means for supplying high temperature gas to the mouth, monitoring means for monitoring the flame visibility status in the combustion chamber, and the amount of oxygen supplied by the high temperature gas from the high temperature gas blowing means based on the flame visibility status signal from the monitoring means To control the high temperature Characterized in that it comprises a scan blow control means.

  In the present invention, secondary combustion air blowing control means for controlling the amount of oxygen supplied by the secondary combustion air from the secondary combustion air blowing means based on the flame visual recognition status signal from the monitoring means is further provided. can do.

  In the present invention, the monitoring means for monitoring the flame visibility status in the combustion chamber is an imaging means for imaging the combustion status in the combustion chamber, and the flame visibility status signal quantifies the image signal from the imaging means as a predetermined value. It can be made to be the difference compared.

<Waste incineration method with grate-type waste incinerator>
A waste incineration method using a grate-type waste incinerator according to the present invention includes a combustion chamber having a grate and burning the waste on the grate, and a combustible gas from the combustion chamber connected to the combustion chamber. A secondary combustion chamber for secondary combustion, primary air blowing means for blowing combustion primary air into the combustion chamber from under the grate, and hot gas blowing means for blowing high temperature gas downward from the ceiling of the combustion chamber; In a waste incineration method using a grate-type waste incinerator having a secondary combustion air blowing means for blowing secondary combustion air provided at a gas outlet of a combustion chamber, from a high temperature gas blowing port provided on the ceiling of the combustion chamber Supply high temperature gas to the combustion chamber, monitor the flame visibility in the combustion chamber by monitoring means, and control the amount of oxygen supplied by the high temperature gas from the high temperature gas blowing means based on the flame visibility status signal from the monitoring means Features To.

  In the present invention, the amount of oxygen supplied by the secondary combustion air from the secondary combustion air blowing means can be controlled on the basis of the flame visibility status signal from the monitoring means.

  In the present invention, the monitoring means for monitoring the flame visibility status in the combustion chamber is an imaging means for imaging the combustion status in the combustion chamber, and the flame visibility status signal digitizes the image signal from the imaging means and compares it with a predetermined value. The difference can be made.

  In such a grate-type waste incinerator and a waste incineration method according to the present invention, the monitoring means monitors the flame visibility in the combustion chamber, and based on the flame visibility signal from the monitoring means, the high temperature The amount of oxygen supplied by the gas blowing means and, optionally, the secondary combustion air blowing means is controlled by the high temperature gas blowing control means or the secondary combustion air blowing control means.

  Further, the monitoring means for monitoring the flame visibility status in the combustion chamber is an imaging means for imaging the combustion status in the combustion chamber, and the flame visibility status signal is a difference obtained by quantifying the image signal from the imaging means and comparing it with a predetermined value. Can be. An image obtained by imaging the combustion state in the combustion chamber is processed by the imaging means, and the brightness, color, flame shape, etc. are digitized and compared with predetermined values obtained by imaging during normal combustion, and based on the difference. The amount of oxygen supplied by the high temperature gas injection control means or the secondary combustion air injection control means is controlled.

  As described above, the present invention is obtained by monitoring the combustion status in the combustion chamber by the monitoring means for monitoring the flame visibility status in the combustion chamber, and obtained by imaging during normal combustion based on the flame visibility status signal from the monitoring means. Since the amount of oxygen supplied by the hot gas to be injected or the secondary combustion air in addition to this is controlled as compared with the predetermined value, the amount of oxygen supplied can be controlled appropriately and quickly. The effect is obtained.

It is a longitudinal section showing a schematic structure of a grate type waste incinerator concerning one embodiment of the present invention.

  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 a grate-type waste incinerator according to an embodiment of the present invention will be described.

<Basic configuration of grate-type waste incinerator>
FIG. 1 shows a schematic configuration of a grate-type waste incinerator according to an embodiment of the present invention. First, the basic configuration of the grate-type waste incinerator and the outline of the incineration method according to one embodiment of the present invention will be described, and then the details of each component device will be described. In this embodiment, the upstream side (left side in FIG. 1) 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 grate-type 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 the waste is disposed in the combustion chamber 2. A grate-type waste provided with a waste inlet 3 for charging into the inside, and a waste heat boiler 4 provided continuously above the downstream side (right side in FIG. 1) in the flow direction of the waste in the combustion chamber 2 It is an incinerator.

  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 such a grate-type waste 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 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. Combustion of waste begins in the combustion start region, and combustible gas begins to be generated by thermal decomposition and partial oxidation of the waste. In the main combustion area, the waste is thermally decomposed and partially oxidized to generate a combustible gas. The combustible gas is burned with a flame and the solid content of the waste is burned. The main combustion region is a region up to a point (combustion point) where combustion with a flame is completed. In the area after the burnout point, it becomes a soot combustion area (post-combustion area) in which solid unburned matter in the waste burns.

  Wind boxes 7a, 7b, and 7c are provided below the dry grate 5a, the combustion grate 5b, and the post-combustion grate 5c in the combustion chamber 2, respectively. The primary combustion air P supplied by the blower 8 is supplied to the wind boxes 7a, 7b, 7c through the primary air supply pipe 9 for combustion, and the combustion chamber 2 through the grate 5a, 5b, 5c. Supplied in. 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 chamber 10 which burns. The secondary combustion gas is blown into the secondary combustion chamber 10 which is a part of the waste heat boiler, the unburned gas is secondarily burned, and the combustion exhaust gas is recovered by the waste heat boiler 4 after this secondary combustion. . 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 waste incinerator having such a basic configuration, the grate-type waste incinerator 1 according to the present embodiment sends the primary combustion air from below the grate into the combustion chamber as follows. Primary air blowing means for blowing, hot gas blowing means for blowing hot gas downward from this hot gas blowing opening provided at multiple positions in the furnace length direction on the ceiling of the combustion chamber, and furnace length on the ceiling of the combustion chamber Return exhaust gas blowing means provided with return exhaust gas inlets at a plurality of positions in the direction and blowing the return exhaust gas downward from the return exhaust gas inlet, and further, secondary combustion air to the secondary combustion chamber provided at the inlet of the waste heat boiler Secondary combustion air blowing means. The hot gas blowing means is controlled by a hot gas blowing control apparatus, and the secondary combustion air blowing means is controlled by a secondary combustion air blowing control apparatus.

<Primary air blowing means>
In the present embodiment, the grate-type waste incinerator 1 includes primary air blowing means for primary air serving as combustion air. The primary air blowing means 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. The combustion primary air supply pipe 9 is provided with a blower 8 and a damper 11 as a flow rate adjusting mechanism.

  The primary air P for combustion passes through the primary air supply pipe 9 for combustion from the blower 8 and wind boxes 7a, 7b, provided in the lower portions of the dry grate 5a, the combustion grate 5b, and the post-combustion grate 5c, respectively. After being supplied to 7c, it is supplied into the combustion chamber 2 through each 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. Further, the configurations of the air boxes 7a, 7b, 7c and the combustion primary air supply pipe 9 for supplying the combustion primary air P are not limited to those shown in the drawings, and may be appropriately determined depending on the scale, shape, use, etc. of the incinerator. Can be selected.

<High-temperature gas blowing means>
In the present embodiment, the grate-type waste incinerator 1 includes a high-temperature gas blowing device 21 that blows a high-temperature gas downward from the ceiling 2 </ b> A of the combustion chamber 2. The hot gas blowing device 21 is provided with hot gas blowing ports 13a and 13b 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, via a damper 23 as a flow rate adjusting mechanism. It is connected to the.

  The hot gas inlet 13a is provided above the dry grate 5a, and the other hot gas inlet 13b is provided above the upstream range (front) of the combustion grate 5b.

  As will be described in detail later, the hot gas blowing device 21 receives the hot air HA and the return exhaust gas E, and mixes them into the hot gas H to adjust the flow rate by the damper 23. , 13b is blown into the furnace.

  The high-temperature gas blowing device 21 mixes the return exhaust gas E and the high-temperature air HA to prepare a high-temperature gas, and blows the high-temperature gas H into the furnace through the high-temperature gas blowing ports 13a and 13b. 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 “hot air” is generated by heating air with a heater. The hot gas blowing device 21 adjusts the mixing ratio by adjusting the flow rates of the return exhaust gas E and the hot air HA to adjust the temperature and oxygen concentration of the hot gas. The high temperature gas blowing device 21 may supply only the high temperature air HA or only the return exhaust gas E as the high temperature gas H.

  In this embodiment, when mixing the return exhaust gas E and the high temperature air HA by the high temperature gas blowing device 21 to prepare the high temperature gas, the mixing ratio is adjusted by adjusting the flow rates of the return exhaust gas E and the high temperature air HA. By adjusting at least one of adjusting the oxygen concentration in the high temperature gas and adjusting the flow rate of the high temperature gas with the damper 23, the amount of oxygen supplied by the high temperature gas into the combustion chamber 2 can be adjusted.

<Returning exhaust gas blowing means>
Moreover, the grate-type waste incinerator 1 includes a return exhaust gas blowing device 22 that returns a part of the exhaust gas after dust discharged from the exhaust gas pipe 4a. The return gas blowing device 22 is connected to the return gas blowing ports 14a and 14b via a damper 24 as a flow rate adjusting mechanism.
The return gas inlet 14a is provided above the downstream range (rear part) of the combustion grate 5b, and the other return gas inlet 14b is provided above the rear combustion grate 5c.

  The return exhaust gas blowing device 22 receives a part of the exhaust gas discharged from the exhaust gas pipe 4a and dedusted by a dust collector (not shown), and adjusts the flow rate by the damper 24 from the return exhaust gas injection ports 14a and 14b. It comes to blow in.

<Secondary combustion gas supply means>
Further, the grate-type waste incinerator 1 of the present embodiment has a secondary combustion air supply system for blowing the secondary combustion air to the upstream side of the secondary combustion chamber 10 corresponding to the vicinity of the inlet of the waste heat boiler 4. I have. The secondary combustion air supply system feeds the secondary combustion air Q from the secondary combustion air supply source to the secondary combustion air inlet 17 provided on the upstream side of the secondary combustion chamber 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 air blowing port 17 is provided at the gas outlet of the combustion chamber 2 so as to blow the secondary combustion air Q upstream of the secondary combustion chamber 10 in the vicinity of the inlet of the waste heat 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 corresponds to the vicinity of the inlet of the waste heat boiler 4 connected above the post-combustion grate 5c. It flows into the secondary combustion chamber 10 where it is subjected to secondary combustion with secondary combustion air. Since the secondary combustion air Q is blown in the horizontal direction from the secondary combustion air blowing port 17, mixing and stirring with the unburned gas secondary combustion air Q is promoted, and combustion of the unburned gas is surely performed. The direction is preferably determined in this way.

  In the present invention, the configuration of the pipeline for supplying the primary air for combustion, the high-temperature gas, the return exhaust gas, and the secondary combustion air is not limited to the illustrated one, and the scale, shape, application, etc. of the incinerator Can be appropriately selected.

<High-temperature gas injection control device and secondary combustion air injection control device>
In this embodiment, it has the high temperature gas blowing control apparatus 20 and the secondary combustion air blowing control apparatus 30, and the high temperature gas blowing control apparatus 20 mixes the high temperature air HA and the return exhaust gas E to the high temperature gas blowing apparatus 21. At least one of issuing a command for adjusting the ratio and issuing a command for adjusting the flow rate at the damper 23 is performed. On the other hand, the secondary combustion air blowing control device 30 issues a command to the damper 19 to adjust the amount of secondary combustion air blown from the secondary combustion air blowing port 17 provided in the secondary combustion chamber 10.

  In the present embodiment, a monitoring window 32 is provided on the rear wall of the combustion chamber 2, and the flame visibility state is monitored by imaging the combustion state in the combustion chamber 2 through the monitoring window 32 outside the furnace. A camera 31 is provided as a monitoring unit, and the camera 31 is connected to or includes a unit that performs image processing of the captured image and digitizes brightness, color, flame shape, and the like as image information. A digitized image information signal is generated. The image processing and the digitization processing may be performed by a hot gas injection control device 20 and a secondary combustion air injection control device 30 described later. This image information signal is used as a flame visual recognition status signal.

  The said monitoring means is connected so that the said flame visual recognition status signal may be sent to the above-mentioned hot gas blowing control apparatus 20 and the secondary combustion air blowing control apparatus 30. FIG. The high-temperature gas injection control device 20 and the secondary combustion air injection control device 30 were obtained on the basis of imaging in a state where combustion in the combustion chamber 2 is normal, that is, no flame is generated and a flame is visible. Each has or shares a predetermined value of the flame visibility signal and compares it with the numerical value of the flame visibility signal obtained from imaging of the actual combustion state that changes every moment from the monitoring means. The hot gas blowing control device 20 controls the hot gas blowing device 21 and the damper 23, and the secondary combustion air blowing control device 30 controls the damper 19 of the pipe 12 described later. These control points will be described later.

  Next, an outline of the incineration status, high temperature gas injection control, and secondary combustion air injection control in the apparatus of the present embodiment configured as described above 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 wind boxes 7a, 7b, 7c, 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. 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. 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 burnout point, the solid unburned portion (char) in the waste is burned, and the burned ash after complete combustion is discharged from the ash drop opening 6.

  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 chamber 10. Therefore, the unburned gas generated in the combustion chamber 2 is guided to the secondary combustion chamber 10 where it is mixed and stirred with the secondary combustion air Q to undergo 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. A part of the exhaust gas after being removed by the dust removing device is used as the return exhaust gas E.

<High-temperature gas injection control and secondary combustion air injection control>
Based on the flame visualizing status signal obtained by the camera 31 that images the combustion status in the combustion chamber of the grate-type waste incinerator and digitized, so that the combustion in the combustion chamber is in a good state, that is, incomplete combustion In order to prevent the occurrence of the problem, the supply amount of the high-temperature gas and the secondary combustion air is controlled by the high-temperature gas injection control device 20 and the secondary combustion air injection control device 30 under the following procedure.

  When incomplete combustion occurs during the combustion of waste in the combustion chamber of a grate-type waste incinerator, the amount of carbon monoxide generated increases and exceeds the regulation value when exhaust gas is released into the atmosphere. At the time of incomplete combustion, soot is generated in the combustion chamber, and it becomes impossible to grasp the combustion state by visually checking the flame in the combustion chamber from the outside of the furnace.

  In the present invention, such a combustion state in the combustion chamber is directly captured by the camera 31, and the captured image is image-processed, and the brightness, color, flame shape, and the like as image information are converted into numerical values indicating the flame visibility state. Compared with a predetermined value obtained by imaging at the time of normal combustion, the supply amount of the hot gas to be blown in or secondary combustion air in addition to this is controlled based on the difference.

  The imaging obtained by the camera 31 in the actual actual combustion situation is digitized by brightness, color, flame shape, etc. so as to be easy to determine, for example, calculating the time average value thereof, It is compared with a reference value obtained in advance during normal combustion, and it is determined whether or not the difference is within an allowable range. For example, if a large amount of soot (smoke) is generated due to incomplete combustion, a dark image can be obtained. In this case, the supply amount of hot gas is increased based on the difference until the above value falls within the reference value range. For example, it increases 1.2 to 1.5 times the normal state, or at the same time, the supply amount of the secondary combustion air is also increased, for example, 1.5 to 3 times the normal state.

  If the difference between the numerical value indicating the flame visibility and the reference value is within the allowable range, it is determined that the combustion state in the combustion chamber has been improved and the normal combustion state has been achieved, and the supply amount of high-temperature gas and secondary combustion air Is controlled to return to the normal state.

  In this way, when the combustion situation in the combustion chamber changes due to fluctuations in the amount and quality of waste supplied to the grate-type waste incinerator, the brightness and color of the image obtained from the camera imaging also changes, so the image A numerical value obtained by digitizing information is compared with a predetermined reference value, and the supply amount of the high-temperature gas and secondary combustion air is adjusted to control the combustion to be in a preferable state.

  In addition, the camera captures the combustion status in the combustion chamber, obtains information indicating the flame viewing status from the captured image, and controls the supply amount of the high-temperature gas and secondary combustion air. When the operator monitors and determines that the flame cannot be visually recognized, the supply amount of the high-temperature gas and the secondary combustion air may be controlled.

DESCRIPTION OF SYMBOLS 1 Grate-type waste incinerator 2 Combustion chamber 2A Ceiling 7a-7c Primary air blowing means (wind box)
9 Primary air blowing means (combustion primary air supply pipe)
10 Secondary combustion chamber 12 Secondary combustion air blowing means (pipe)
13a, 13b Hot gas inlet 17 Secondary combustion air injection means (secondary combustion air inlet)
20 High-temperature gas injection control device 30 Secondary combustion air injection control device

Claims (6)

A grate-type waste incinerator comprising a grate and a combustion chamber that burns waste on the grate, and a secondary that is connected to the combustion chamber and secondary burns combustible gas from the combustion chamber A combustion chamber, primary air blowing means for blowing combustion primary air into the combustion chamber from below the grate, hot gas blowing means for blowing high temperature gas downward from the ceiling of the combustion chamber, and a gas outlet of the combustion chamber In a grate-type waste incinerator having secondary combustion air blowing means provided and blowing in secondary combustion air,
The high-temperature gas blowing means includes a high-temperature gas blow-in opening provided on the ceiling of the combustion chamber, a high-temperature gas supply means for supplying high-temperature gas to the high-temperature gas blow-in opening, a monitoring means for monitoring the flame visibility in the combustion chamber, and a monitoring A grate-type waste incinerator comprising: high-temperature gas blowing control means for controlling the amount of oxygen supplied by the high-temperature gas from the high-temperature gas blowing means based on a flame visibility signal from the means.   The secondary combustion air blowing control means for controlling the amount of oxygen supplied by the secondary combustion air from the secondary combustion air blowing means based on the flame visibility status signal from the monitoring means is further provided. Grate-type waste incinerator.   The monitoring means for monitoring the flame visibility status in the combustion chamber is an imaging means for imaging the combustion status in the combustion chamber, and the flame visibility status signal is a difference obtained by quantifying the image signal from the imaging means and comparing it with a predetermined value. The grate-type waste incinerator according to claim 1 or 2. A waste incineration method using a grate-type waste incinerator comprising a combustion chamber provided with a grate and burning waste on the grate, and a combustible gas from the combustion chamber connected to the combustion chamber. A secondary combustion chamber for subsequent combustion, primary air blowing means for blowing combustion primary air from below the grate into the combustion chamber, hot gas blowing means for blowing high temperature gas downward from the ceiling of the combustion chamber, and combustion In a waste incineration method by a grate-type waste incinerator having secondary combustion air blowing means for blowing secondary combustion air provided at a gas outlet of the chamber,
High temperature gas is supplied to the combustion chamber from a high temperature gas injection port provided on the ceiling of the combustion chamber, and the flame visibility status in the combustion chamber is monitored by monitoring means, and the high temperature gas injection means is based on the flame visibility status signal from the monitoring means A waste incineration method using a grate-type waste incinerator characterized by controlling the amount of oxygen supplied by high-temperature gas from the grate.   5. The disposal by the grate-type waste incinerator according to claim 4, wherein the amount of oxygen supplied by the secondary combustion air from the secondary combustion air blowing means is controlled based on a flame visibility status signal from the monitoring means. Incineration method.   The monitoring means for monitoring the flame visibility status in the combustion chamber is an imaging means for imaging the combustion status in the combustion chamber, and the flame visibility status signal is a difference obtained by quantifying the image signal from the imaging means and comparing it with a predetermined value. A waste incineration method using a grate-type waste incinerator according to claim 4 or 5.

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