JP6824642B2 - Waste incineration equipment and waste incineration method - Google Patents

Description

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

A grate-type waste incinerator is widely used as an incinerator for incinerating waste such as municipal waste. The outline of the configuration of a typical incinerator is as follows.

The grate-type waste incinerator has a three-stage grate (dry grate, combustion grate, and post-combustion grate) arranged in the direction of movement of the waste at the bottom of the combustion chamber that burns the waste. A secondary combustion chamber is connected at 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 below the downstream side of the post-combustion grate in the moving direction of the waste. Normally, the secondary combustion chamber is also a part of a waste heat boiler for waste heat recovery, and is a portion near the inlet thereof. In addition, a combustion primary air blowing mechanism for blowing combustion primary air from under each grate of the dry grate, the combustion grate, and the post-combustion grate is provided.

In such a grate-type waste incinerator, the waste input into the combustion chamber from the waste inlet is deposited on the dry grate and dried by the air from under the dry grate and the radiant heat in the furnace. At the same time, the temperature is raised and ignited. That is, immediately above the dry grate, a dry region is formed in the upstream space in the direction of waste movement, and combustion is performed 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 burning is sent from the dry grate onto the combustion grate, the waste is thermally decomposed to generate combustible gas, and the combustion is sent from under the combustion grate. Combustible gas and solids are burned by the primary air for use, and a main combustion region is formed in the space directly above the combustion grate. Then, unburned components such as fixed carbon are completely burned on the post-combustion grate, and a post-combustion region is formed in the space directly above the post-combustion grate. After that, the ash remaining after combustion is discharged to the outside from the ash drop port.

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

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 required for combustion of waste is usually 1.4 to 1. It is about 5. This is larger than the air ratio of 1.05 to 1.2 required for combustion of general fuel. The reason is that waste has more incombustible content and is inhomogeneous than liquid fuel and gaseous fuel as general fuel, so air utilization efficiency is low and a large amount of air is required for combustion. This is to become. However, if the amount of supplied air is simply increased, the amount of exhaust gas increases as the air ratio increases, so that a larger exhaust gas treatment facility is required accordingly.

If the waste can be burned without any trouble in the waste incinerator with the air ratio reduced, the amount of exhaust gas will be reduced and the exhaust gas treatment equipment will be compact, and as a result, the entire waste incineration facility will be miniaturized. Equipment costs can be reduced. In addition to this, the amount of chemicals used for exhaust gas treatment is also reduced, so that 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 cannot be recovered and is discarded into the atmosphere is reduced, and the efficiency of power generation using waste incineration waste heat is improved accordingly. Can be raised.

As described above, the advantage of performing low air ratio combustion is great, but on the other hand, there arises a problem that combustion becomes unstable in low air ratio combustion having an air ratio of 1.3 or less. That is, when waste is burned at a low air ratio, combustion becomes unstable and CO generation increases, the flame temperature rises locally and NOx rapidly increases, and a large amount of soot is generated. This causes a problem that harmful substances in the exhaust gas increase, and the local high temperature melts the waste and ash and adheres to the furnace wall to generate clinker, and the life of the refractory on the furnace wall is short. There is a problem of becoming.

Under such circumstances, a waste incinerator capable of stably burning at a low air ratio of 1.3 or less has been studied and is disclosed in Patent Document 1. According to Patent Document 1, the following effects can be obtained by removing the exhaust gas discharged from the waste incinerator and then blowing a high-temperature gas in which the exhaust gas and air are mixed into the combustion chamber.

That is, even under a low air ratio, the thermal decomposition of waste is promoted by the manifestation and radiation of high-temperature gas, and the combustible gas generated by the thermal decomposition of waste by blowing high-temperature gas containing oxygen. In addition to promoting combustion, high-temperature gas is blown into the combustion chamber from a nozzle provided on the side wall of the combustion chamber, and the flow of this high-temperature gas collides with the ascending flow of the combustible gas generated from the waste and the combustion gas. By forming a slow-flowing stagnation region directly above the waste layer, the flow of flammable gas is slowed down, and the flammable gas is sufficiently mixed with the oxidizing agent component supplied by the primary combustion air and high-temperature gas. Therefore, it has the effect of stable combustion, and by blowing high-temperature gas into the combustion chamber, it is possible to stably burn waste under low air ratio combustion operation.

In a waste incinerator, nitrogen contained in waste (the former) and nitrogen in the air (the latter) react at high temperatures to generate NOx. NOx by the former is called fuel NOx, and NOx by the latter is called thermal NOx. When the exhaust gas discharged from the incinerator is discharged from the chimney into the atmosphere, the NOx concentration in the exhaust gas must be below the regulation value, so NOx is removed by the denitration device of the exhaust gas treatment system, but the incinerator Suppressing the amount of NOx generated inside is a fundamental measure, and this is required.

In order to suppress the amount of NOx generated, in the waste incinerator disclosed in Patent Document 1, in addition to the above-mentioned blowing of high-temperature gas in which air and exhaust gas are mixed, the upper part of the blowing position of the high-temperature gas. Alternatively, a part of the exhaust gas from the incinerator is blown as circulating exhaust gas to the downstream side in the gas flow direction.

By blowing the circulating exhaust gas above the position where the high temperature gas is blown or downstream in the gas flow direction, the flame temperature is lowered above the combustion region stabilized by the blowing of the high temperature gas in the combustion chamber or downstream in the gas flow direction. It suppresses the generation of a local high temperature region, homogenizes the temperature in the furnace over a wide range, and more effectively suppresses the thermal NOx generated by the reaction of nitrogen in the air in the high temperature region. Further, by blowing a circulating exhaust gas having a low oxygen concentration (about 4 to 8% by volume), the region above the blowing position of the high-temperature gas or the region on the downstream side in the gas flow direction is brought closer to the reducing atmosphere, and the thermal NOx is reduced to N ₂ . It is said that the NOx concentration will be reduced.

International Publication No. 2004-092648

According to Patent Document 1, circulating exhaust gas is blown into the furnace from a hole provided in the side wall or ceiling of the combustion chamber, and the circulating exhaust gas stirs the gas in the furnace to suppress the generation of a local high temperature region (uniform temperature distribution). Therefore, it has the effect of suppressing the generation of highly temperature-dependent thermal NOx derived from nitrogen in the air. However, the effect is limited on fuel NOx derived from nitrogen in waste. This is because fuel NOx is more dependent on the oxygen concentration of the atmosphere when the waste is thermally decomposed and gasified than on the temperature. It is said that a large proportion of fuel NOx is generated in a waste incinerator. Conventionally, it has been difficult to say that effective measures have been taken against this fuel NOx.

In view of such circumstances, the present invention only suppresses the generation of thermal NOx in a waste incinerator that blows high temperature gas into a combustion chamber in order to perform a low air ratio combustion operation having an air ratio of 1.3 or less. An object of the present invention is to provide a waste incinerator and a waste incineration method that suppress the generation of fuel NOx, which is generated in a large proportion in a waste incinerator.

In order to solve the above-mentioned problems, the present invention is configured as the following first or second invention with respect to the waste incineration apparatus and the following third or fourth invention with respect to the waste incineration method.

[Waste incinerator]
<First invention>
In a waste incinerator equipped with a waste incinerator that burns waste in a combustion chamber equipped with a grate,
A primary air supply means that supplies the primary air for combustion from below the grate,
A circulating exhaust gas supply means that supplies a part of the exhaust gas of the incinerator as circulating exhaust gas from below at least one of the drying grate and the combustion grate,
A high-temperature gas supply means that supplies high-temperature gas from the side wall or ceiling of the combustion chamber,
It is provided with a mixed gas oxygen amount controlling means for controlling the oxygen amount of the mixed gas of the primary air supplied from below the dry grate and the combustion grate and the circulating exhaust gas.
The mixed gas oxygen amount control means sets the air ratio, which is the ratio of the oxygen amount of the mixed gas to the theoretical oxygen amount required for burning the waste on the dry grate and the combustion grate, within a predetermined range. A waste incinerator including a waste incinerator, which controls a primary air supply amount by a supply means and a circulating exhaust gas supply amount by a circulating exhaust gas supply means.

In the present invention, the mixed gas oxygen amount controlling means preferably controls the air ratio to 0.6 to 0.8.

In the present invention, the waste incinerator may further include a second circulating exhaust gas supply means for supplying a part of the exhaust gas of the incinerator from the side wall or the ceiling of the combustion chamber to the waste pyrolysis gas combustion region. ..

<Second invention>
In a waste incinerator equipped with a waste incinerator that burns waste in a combustion chamber equipped with a grate,
A primary air supply means for supplying primary air for combustion from below the dry grate and the combustion grate,
A circulating exhaust gas supply means that supplies a part of the exhaust gas of the incinerator as circulating exhaust gas from below at least one of the dry grate and the combustion grate and from below the post-combustion grate.
A high-temperature gas supply means that supplies high-temperature gas from the side wall or ceiling of the combustion chamber,
A mixed gas oxygen amount controlling means for controlling the oxygen amount of the mixed gas of the primary air supplied from below the dry grate and the combustion grate and the circulating exhaust gas supplied from below at least one of the dry grate and the combustion grate. Equipped with
The mixed gas oxygen amount controlling means sets the air ratio, which is the ratio of the oxygen amount of the mixed gas to the theoretical oxygen amount required for burning the waste on the dry grate and the combustion grate, within a predetermined range. Waste provided with a waste incinerator, which is characterized by controlling the supply amount of primary air by the supply means and the supply amount of the circulating exhaust gas supplied from below at least one of the dry grate and the combustion grate by the circulating exhaust gas supply means. Incinerator.

In the present invention, the mixed gas oxygen amount controlling means preferably controls the air ratio to 0.6 to 0.8.

In the present invention, the waste incinerator may further include a second circulating exhaust gas supply means for supplying a part of the exhaust gas of the incinerator from the side wall or the ceiling of the combustion chamber to the waste pyrolysis gas combustion region. ..

[Waste incineration method]
<Third invention>
In the waste incineration method in a waste incinerator equipped with a waste incinerator that burns waste in a combustion chamber equipped with a grate,
The primary air for combustion is supplied from below the grate,
Part of the exhaust gas from the incinerator is supplied as circulating exhaust gas from below at least one of the dry grate and the combustion grate.
Hot gas is supplied from the side wall or ceiling of the combustion chamber,
Controls the amount of oxygen in the mixed gas of the primary air and circulating exhaust gas supplied from below the dry grate and combustion grate,
The control of the oxygen content of the mixed gas is primary so that the air ratio, which is the ratio of the oxygen content of the mixed gas to the theoretical oxygen content required for burning the waste on the dry grate and the combustion grate, is within a predetermined range. A waste incineration method characterized by controlling the amount of air supply and the amount of circulating exhaust gas supplied.

In the present invention, it is preferable to control the air ratio to 0.6 to 0.8.

In the present invention, a part of the exhaust gas of the incinerator can be further supplied to the waste pyrolysis gas combustion region from the side wall or the ceiling of the combustion chamber.

<Fourth invention>
In the waste incineration method in a waste incinerator equipped with a waste incinerator that burns waste in a combustion chamber equipped with a grate,
The primary air for combustion is supplied from below the dry grate and the combustion grate,
A part of the exhaust gas from the incinerator is supplied as circulating exhaust gas from below at least one of the dry grate and the combustion grate and from below the post-combustion grate.
Hot gas is supplied from the side wall or ceiling of the combustion chamber,
Control the amount of oxygen in the mixed gas of the primary air supplied from below the dry grate and the combustion grate and the circulating exhaust gas supplied from below at least one of the dry grate and the combustion grate.
The control of the oxygen amount of the mixed gas is primary so that the air ratio, which is the ratio of the oxygen amount of the mixed gas to the theoretical oxygen amount required for burning the waste on the dry grate and the combustion grate, is within a predetermined range. A waste incineration method comprising controlling the amount of air supply and the amount of circulating exhaust gas supplied from below at least one of a dry grate and a combustion grate.

In the present invention, it is preferable to control the air ratio of the mixed gas to 0.6 to 0.8.

In the present invention, a part of the exhaust gas of the incinerator can be further supplied to the waste pyrolysis gas combustion region from the side wall or the ceiling of the combustion chamber.

<Principle of invention>
When waste in waste incinerators is thermally decomposed and gasified (or partial oxidation), nitrogen (N) content contained in the waste is predominantly released HCN, as NH _3. They are oxidized to fuel NOx, the conversion rate of which is affected by the oxygen concentration and temperature of the atmosphere in which the conversion reaction takes place. The effect of oxygen concentration is particularly large.

In the present invention, in a waste incinerator (mainly a stoker type incinerator) in such a situation, at least one of a dry grate and a combustion grate is added to the primary air for combustion sent from below the grate. The circulating exhaust gas from which a part of the exhaust gas from the incinerator is extracted is mixed and supplied to the combustion chamber as a mixed gas to incinerate the waste. Furthermore, the oxygen content of the mixed gas is controlled, and the dry grate and combustion are performed. The primary air supply amount and the circulating exhaust gas supply amount are controlled so that the air ratio, which is the ratio of the oxygen amount of the mixed gas to the theoretical oxygen amount required for combustion of waste on the grate, is within a predetermined range. ..

According to the present invention, by controlling the amount of oxygen in the mixed gas, it is possible to reduce the air ratio of the atmosphere in which the waste is thermally decomposed and partially oxidized, and the nitrogen contained in the waste reacts to generate a fuel. It is possible to suppress the generation of NOx and reduce the NOx contained in the exhaust gas and discharged. Therefore, the catalytic denitration equipment for removing NOx in the exhaust gas is unnecessary or reduced in scale. In the present invention, the circulating exhaust gas may be further blown from the side wall or the ceiling.

By mixing the circulating exhaust gas with at least one of the dry grate and the combustion grate with the primary air for combustion sent from below the grate in this way and supplying this as a mixed gas to the combustion chamber. The amount of oxygen in the mixed gas can be controlled and supplied according to the waste composition and combustion conditions. At that time, it is preferable to control the amount of oxygen in the mixed gas for combustion so that the air ratio of the atmosphere near the waste layer on the grate, that is, the atmosphere in which the waste burns is 0.6 to 0.8. .. By doing so, it is possible to suppress the generation of fuel NOx generated by the reaction of nitrogen contained in the waste and reduce the NOx discharged to the exhaust gas. In addition, compared to supplying only primary air, by supplying a mixed gas, the flow rate of the gas supplied to the combustion chamber is increased, and the generation of local high temperature regions in the combustion chamber is suppressed by the dilution / stirring effect, etc., and the temperature is increased. It is also possible to realize uniform distribution, which is effective in suppressing the generation of NOx.

Conventionally, circulating exhaust gas is supplied to the combustion chamber space where the combustion of combustible gas generated by thermal decomposition of waste is generated, but this is effective in suppressing the generation of thermal NOx derived from nitrogen in the air. However, the effect on suppressing the generation of fuel NOx derived from waste nitrogen was low. According to the present invention, the mixed gas is placed from below the grate to directly above the waste layer so that the air ratio of the atmosphere in which the waste is thermally decomposed and partially oxidized is lowered within a predetermined range by controlling the oxygen content of the mixed gas. Since it can be blown directly into the waste thermal decomposition region, the air ratio of the atmosphere in which the waste is thermally decomposed and partially oxidized is lowered, and the generation of fuel NOx generated by the reaction of nitrogen contained in the waste is suppressed. Very effective in doing.

Further, in the present invention, in the waste incinerator, circulation is performed by extracting a part of the exhaust gas of the incinerator from the dry grate and the combustion grate to the primary air for combustion sent from below the grate. Exhaust gas is mixed and supplied to the combustion chamber as a mixed gas to incinerate the waste, control the amount of oxygen in the mixed gas, and the theoretical amount of oxygen required to burn the waste on the dry grate and the combustion grate. The primary air supply amount and the circulating exhaust gas supply amount are controlled so that the air ratio, which is the ratio of the oxygen amount of the mixed gas to the above, is within a predetermined range, and the circulating exhaust gas is supplied from below the post-combustion grate. ..

According to the present invention, by controlling the amount of oxygen in the mixed gas, it is possible to reduce the air ratio of the atmosphere in which the waste is thermally decomposed and partially oxidized, and the generation of fuel NOx can be suppressed, and later By supplying the circulating exhaust gas from below the combustion grate into the combustion chamber, the combustion chamber gas can be agitated to suppress the generation of local high temperature regions and suppress the generation of thermal NOx, and the generation of fuel NOx and thermal NOx can be suppressed. It is possible to reduce NOx contained in the exhaust gas and discharged.

As described above, according to the present invention, high-temperature gas is blown from the side wall or the ceiling of the combustion chamber above the grate, primary air for combustion is supplied from below the grate, and a dry grate and a combustion fire are further supplied. The circulating exhaust gas is supplied from below at least one of the lattices, a mixed gas is formed by the primary air and the circulating exhaust gas, and the mixed gas is directly blown into the waste layer on the grate to reduce the amount of oxygen in the mixed gas. Since the waste is burned within a predetermined range with the air ratio of the atmosphere where the waste is thermally decomposed and partially oxidized by control, in addition to suppressing the generation of thermal NOx by blowing the above high temperature gas above the grate, fire By supplying the mixed gas from below the lattice, it is possible to effectively suppress the generation of fuel NOx.

It is a schematic block diagram of the waste incineration apparatus as the 1st Embodiment of this invention. It is a schematic block diagram of the waste incineration apparatus as the 2nd Embodiment of this invention.

[First Embodiment]
Hereinafter, the basic configuration, each component, and the operation of the grate-type incinerator according to the embodiment of the present invention will be described.

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

<Basic configuration of grate type incinerator>
The grate-type waste incinerator 1 shown in FIG. 1 compacts the grate-type waste incinerator equipment by stably performing low-air ratio combustion by blowing high-temperature gas, which will be described later, from the side wall or ceiling. It is possible to significantly reduce equipment costs and operating costs.

The waste incinerator 1 according to the present embodiment is arranged above the combustion chamber 2 and the upstream side (left side in FIG. 1) in the waste flow direction of the combustion chamber 2, and puts the waste into the combustion chamber. This is a grate-type incinerator including a waste inlet 3 for the purpose and a waste heat boiler 4 connected 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, a grate (stalker) 5 for burning waste while moving it is provided. 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 input port 3, that is, from the upstream side.

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

In such an incinerator of the present embodiment, a layer of waste is formed on the dry grate 5a and the combustion grate 5b, and the combustion causes the waste on the grate in the space inside the combustion chamber 2. Immediately above the layer, various regions of a dry region, a combustion start region, a main combustion region, and a post-combustion region are formed as follows.

A dry region is formed above the upstream range (front portion) of the dry grate 5a in the waste flow direction, which is located directly above the dry grate 5a and corresponding to the lower side of the waste input port 3. To.

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

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

After that, a small amount of unburned components such as fixed carbon in the remaining waste are completely burned on the post-combustion grate 5c. After this, a post-combustion region is formed above the post-combustion grate 5c.

When the waste is burned in the combustion chamber 2, the moisture from the waste evaporates first in the dry region, then the thermal decomposition and the partial oxidation reaction occur in the combustion start region, and flammable gas starts to be generated. As described above, the combustion start region is a region in which flammable gas begins to be generated by thermal decomposition and partial oxidation of waste, and combustion of the combustible gas and the solid content of the waste begins. In the main combustion region, thermal decomposition and partial oxidation of waste are actively performed to generate flammable gas, and the combustible gas is burned with a flame and the solid content of the waste is burned. It is a combustion region, which is a region up to the point where combustion accompanied by a flame is completed (burn-out point). The region after the burnout point is the char combustion region (post-combustion region) where the solid unburned content (char) 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 combustion primary air supplied by the blower 8 is supplied to the above-mentioned air boxes 7a, 7b, 7c through the combustion primary air supply pipe 9 and its branch supply pipes 9a, 9b, 9c, and is supplied to each grate. It rises through 5a, 5b, and 5c and is supplied into the combustion chamber 2. The primary air for combustion supplied from below the grate is used for drying and burning the waste on the grate 5a, 5b, 5c, as well as the cooling action of the grate 5a, 5b, 5c, and the waste. It also has a stirring action.

A waste heat boiler 4 is continuously provided at the outlet on the downstream side of the combustion chamber 2, and the vicinity of the inlet of the waste heat boiler 4 is a secondary combustion region 10 for burning unburned gas in the gas discharged from the combustion chamber 2. It has become. The secondary combustion gas is blown into the secondary combustion region 10 which is a part of the waste heat boiler, the unburned gas is secondarily burned, and after this secondary combustion, the combustion exhaust gas is recovered by the waste heat boiler 4. To. After the heat is recovered, the combustion exhaust gas discharged from the waste heat boiler is cooled by the temperature reducing tower 11, and the acid gas is neutralized by blowing in slaked lime or the like in an exhaust gas treatment device system (not shown), and dioxin and the like by activated carbon. The harmful substances are adsorbed and removed, and then sent to the dust collector 12, and the neutralization reaction product, activated carbon adsorbing the harmful substances, dust and the like are recovered. The combustion exhaust gas after being detoxified by the dust collector 12 and detoxified is attracted by the attraction fan 13 and discharged from the chimney 14 into the atmosphere.

In the grate-type incinerator having such a basic configuration, the waste incinerator 1 according to the present embodiment is a primary air supply means for blowing primary air for combustion into the combustion chamber 2 from under the grate 5. A high-temperature gas supply means for blowing high-temperature gas into the combustion chamber 2 from the side wall or the ceiling, and a part of the exhaust gas discharged from the waste incinerator 1 and cooled by the temperature reducing tower 11 and removed by the dust collecting device 12 are extracted. It is provided with a circulating exhaust gas supply means for blowing into the combustion chamber 2 from under the grate 5 as the circulating exhaust gas, and an oxygen amount controlling means for adjusting the oxygen amount of the mixed gas in which the primary air and the circulating exhaust gas are mixed. ing.

<Primary air supply means>
In the present embodiment, the waste incinerator 1 includes a primary air supply means including a blower 8 for supplying primary air as combustion air and a primary air supply pipe 9. The primary air supply means blows the primary air from the air supply source through the blower 8 and the primary air supply pipe 9, and the air boxes 7a, 7b, 7c of the dry grate 5a, the combustion grate 5b, and the post-combustion grate 5c, respectively. The branch supply pipes 9a, 9b, 9c are fed from the branch supply pipes 9a, 9b, 9c, and the branch supply pipes 9a, 9b, 9c are provided with dampers 16a, 16a 16b and 16c are provided.

<High temperature gas supply means>
In the present embodiment, the waste incinerator 1 blows a high-temperature gas in which a part of the circulating exhaust gas and high-temperature air are mixed diagonally downward from the side wall of the combustion chamber 2 or downward from the ceiling 15a. , 15b is provided with a high temperature gas supply means. By this high temperature gas supply means, high temperature gas is blown from the high temperature gas inlets 15a and 15b toward the region from the combustion start region to the main combustion region.

The high-temperature gas supply means includes a high-temperature gas supply source (not shown) provided outside the combustion chamber 2, high-temperature gas inlets 15a and 15b for blowing high-temperature gas into the combustion chamber 2, and dampers as a flow rate adjusting mechanism (FIG. (Not shown) and a high-temperature gas supply pipe 20 that leads from the high-temperature gas supply source to the high-temperature gas inlets 15a and 15b. A part of the circulating exhaust gas and high-temperature air are mixed at the high-temperature gas supply source to prepare a high-temperature gas adjusted to a predetermined temperature range and oxygen concentration range.

The high-temperature gas inlets 15a and 15b are located on the side wall or ceiling of the combustion chamber 2 in the area directly above the waste layer on the grate from the downstream side (rear part) of the dry grate 5a in the moving direction to the combustion grate 5b. It is provided so as to blow high temperature gas toward.

When the high temperature gas inlets 15a and 15b are provided on the side wall of the combustion chamber 2, the high temperature gas is ejected diagonally downward, and when the high temperature gas inlets 15a and 15b are provided on the ceiling of the combustion chamber 2, the high temperature gas is ejected. It is provided so that the direction is downward. Thus, the high temperature gas is blown from the high temperature gas injection ports 15a and 15b toward the region from the combustion start region to the main combustion region.

The high temperature gas inlets 15a and 15b may be provided at a plurality of locations in the furnace width direction (direction perpendicular to the paper surface in FIG. 1), and the high temperature gas inlets 15a and 15b may be provided at a plurality of locations. It may be arranged at a plurality of positions in the furnace length direction within the above setting range.

<Circulating exhaust gas supply means>
A circulating exhaust gas supply pipe 17 branched from the flue is provided on the downstream side of the dust collector 12, and the branched supply pipes 17a and 17b of the circulating exhaust gas supply pipe 17 pass through the blower 18 and the wind below the dry grate 5a. It is connected to the box 7a and the air box 7b below the combustion grate 5b, respectively. The circulating exhaust gas supply pipe 17 and the blower 18 constitute a circulating exhaust gas supply means. The branch supply pipes 17a and 17b are provided with dampers 19a and 19b as flow rate adjusting mechanisms that form a part of the oxygen amount control means described later.

The circulating exhaust gas from the circulating exhaust gas supply pipe 17 reaches the air boxes 7a and 7b through the branch supply pipes 17a and 17b, and the primary air from the branch supply pipes 9a and 9b of the primary air supply pipe 9 and the air box 7a. , 7b are mixed and mixed gas is blown into the waste layer on the dry grate 5a and the combustion grate 5b from below each of the dry grate 5a and the combustion grate 5b. Thus, to the waste on the dry grate 5a and the combustion grate 5b, a mixed gas in which the primary air and the circulating exhaust gas are mixed is supplied, and the oxygen amount of the mixed gas is adjusted to the air ratio of the atmosphere in which the waste burns. By controlling the gas to a predetermined range, the waste is burned under the air ratio controlled within the predetermined range, and the generation of fuel NOx is suppressed. Regarding the supply amount of the circulating exhaust gas, the NOx concentration in the exhaust gas is measured between the boiler 4 and the temperature reducing tower 11, and the supply amount of the circulating exhaust gas and the supply amount of the primary air are controlled based on the measured NOx concentration value. You may do so.

Further, from the circulating exhaust gas supply pipe 17, a branch supply pipe 20 is provided at the wake position of the blower 18 to guide a part of the circulating exhaust gas to the high temperature gas supply source, and one of the high temperature air and the circulating exhaust gas. The high-temperature gas mixed with the portion is blown into the combustion chamber 2 from the high-temperature gas outlets 15a and 15b.

<Mixed gas oxygen amount control means>
The mixed gas supplied from below to the dry grate 5a and the combustion grate 5b is supplied while being controlled to an oxygen concentration within a predetermined range. The present embodiment has a mixed gas oxygen amount control means for controlling the control.

The mixed gas oxygen amount controlling means sets the air ratio, which is the ratio of the oxygen amount of the mixed gas to the theoretical oxygen amount required for burning the waste on the dry grate 5a and the combustion grate 5b, within a predetermined range. Control the amount of mixed gas oxygen. Therefore, the mixed gas oxygen amount controlling means controls the primary air supply amount by the primary air supply means and the circulating exhaust gas supply amount by the circulating exhaust gas supply means, and the damper 16a as a flow rate adjusting mechanism of the primary air supply means, It is composed of 16b and dampers 19a and 19b as a flow rate adjusting mechanism of the circulating exhaust gas supply means. These flow rate adjusting mechanisms do not necessarily have to be dampers, and may be configured by, for example, valves or the like.

The mixed gas oxygen amount controlling means controls the amount of oxygen in the mixed gas to burn so that the air ratio of the atmosphere in which the waste is burned on the dry grate 5a and the combustion grate 5b is 0.6 to 0.8. It is preferable to do so. By doing so, it is possible to suppress the generation of fuel NOx generated by the reaction of nitrogen contained in the waste and reduce the NOx discharged to the exhaust gas.

It is preferable to control the amount of oxygen in the mixed gas so that the atmosphere in which the waste on the grate burns is an oxygen atmosphere having an air ratio of 0.6 to 0.8. The grounds for setting the air ratio to 0.6 to 0.8 are as follows. Air ratio is smaller than 0.6, the more the generation of NH ₃ and HCN, NOx is produced in the rear stream side from these, also instability and insufficient amount of oxygen required for waste is burned combustion Furthermore, it is unsuitable because the amount of combustible gas generated becomes excessive and the amount of unburned matter generated becomes excessive. If the air ratio is larger than 0.8, the atmosphere does not suppress the oxygen concentration, and fuel NOx Is unsuitable due to the large amount of oxygen generated, and therefore the air ratio is preferably 0.6 to 0.8.

In the present invention, the configuration of the pipeline for supplying the combustion primary air, the high temperature gas, and the circulating exhaust gas is not limited to the one shown in the figure, and may be appropriately selected depending on the scale, shape, application, etc. of the incinerator. ..

<Second circulating exhaust gas supply means>
In the present embodiment, as a preferred embodiment, a second circulating exhaust gas supply means for blowing a part of the circulating exhaust gas into the combustion chamber 2 is provided. A branch supply pipe 21 is branched from the above-mentioned circulating exhaust gas supply pipe 17 at the wake position of the blower 18, and a part of the circulating exhaust gas is provided in the circulating exhaust gas inlet 22 provided on the side wall or the ceiling of the combustion chamber 2. Is blowing into the combustion chamber 2. The circulating exhaust gas inlet 22 is provided above the positions of the high-temperature gas inlets 15a and 15b described above or on the downstream side in the furnace gas flow direction. In the region above the high temperature gas inlet or downstream in the furnace gas flow direction in the combustion chamber 2, the pyrolysis gas generated by the thermal decomposition of the waste is burned, and this waste pyrolysis gas combustion region Is designed to blow in circulating exhaust gas. In the illustrated example, it is preferably provided at a position above and downstream of the high temperature gas inlets 15a and 15b.

Next, an outline of the combustion state in the apparatus of the present embodiment configured as described above, supply of primary air, stabilization of combustion by supply of high temperature gas, suppression of NOx generation by supply of mixed gas of circulating exhaust gas and primary air, etc. The various actions will be described in sequence.

<Outline of combustion situation>
First, when waste is thrown into the waste inlet 3, the falling waste is deposited on the dry grate 5a and moves to the combustion grate 5b and the post-combustion grate 5c by the operation of each grate. Then, a layer of waste is formed on the dry grate 5a and the combustion grate 5b. Each grate receives primary air for combustion through the airboxes 7a, 7b, 7c, which causes the waste of each grate to be dried and burned as follows.

Waste is 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 and ignited in the downstream range, and combustion starts in the range up to the upstream range (front part) of the combustion grate 5b. To do. On the combustion grate 5b, the waste is mainly thermally decomposed and partially oxidized, combustible gas is generated, and the combustible gas and the solid content in the waste are burned. Combustion of waste is substantially complete on the combustion grate 5b. On the post-combustion grate 5c, unburned components such as fixed carbon in the remaining waste are completely burned. The combustion ash after complete combustion is discharged from the ash drop port 6. In the state where the waste is burning in this way, the dry region, the combustion start region, the main combustion region, and the post-combustion region are located in the space directly above the dry grate 5a, the combustion grate 5b, and the post-combustion grate 5c, respectively. It is formed.

As described above, the waste heat boiler 4 is continuously provided at 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 portion of the combustible gas generated in the combustion chamber 2 is guided to the secondary combustion region 10, where it is mixed and agitated with the secondary combustion gas (not shown), and the secondary combustion is performed. After the secondary combustion, the flue gas is recovered by the waste heat boiler 4. After the heat is recovered, the combustion exhaust gas discharged from the waste heat boiler 4 is cooled by the temperature reducing tower 11, neutralizing the acid gas by blowing in delime and the like, and adsorbing and removing harmful substances such as dioxin by activated carbon. Then, it is further sent to the dust collecting device 12, and the neutralization reaction product, activated carbon adsorbing harmful substances, dust and the like are recovered. The combustion exhaust gas after being detoxified by the dust collector 12 and detoxified is attracted by the attraction fan 13 and discharged from the chimney 14 into the atmosphere. As the dust collector 12, for example, a dust collector such as a bug filter type or an electrostatic dust collector can be used.

<Supply of primary air>
The primary air for combustion is supplied from the blower 8 through the primary air supply pipe 9 to the air boxes 7a, 7b, 7c provided at the lower parts of the dry grate 5a, the combustion grate 5b, and the post-combustion grate 5c, respectively. After that, it is supplied into the combustion chamber 2 through the grate 5a, 5b, 5c. The flow rate of the primary air supplied into the combustion chamber 2, that is, the flow rate supplied to the air boxes 7a, 7b, 7c is the branch supply pipes 9a, 9b, 9c provided by branching to each air box. It is adjusted by the flow rate adjusting dampers 16a, 16b, 16c provided in the above. As the primary air for combustion, the temperature is in the range of room temperature to 200 ° C., and air is used.

<Supply of circulating exhaust gas>
The circulating exhaust gas passes through the circulating exhaust gas supply pipe 17 branched from the flue on the downstream side of the dust collecting device 12, and the wind provided at the lower part of each of the dry grate 5a, the combustion grate 5b, and the post-combustion grate 5c. After being supplied to the boxes 7a, 7b, 7c, the mixed gas of the primary air and the circulating exhaust gas is the waste on the dry grate 5a and the combustion grate 5b from below the dry grate 5a and the combustion grate 5b, respectively. Supplied to the layer.

<Suppression of NOx generation by supplying a mixed gas of circulating exhaust gas and primary air>
In a waste incinerator, nitrogen contained in waste and nitrogen in the air react at high temperatures to generate NOx. When the exhaust gas discharged from the incinerator 1 is discharged from the chimney 14 into the atmosphere, the NOx concentration must be below the regulation value, so NOx is removed by the denitration device of the exhaust gas treatment system, but the incinerator 1 Suppressing the amount of NOx generated inside is a fundamental measure, and a mixed gas is supplied to realize this.

In the present embodiment, the mixed gas of the circulating exhaust gas and the primary air is blown from below the dry grate 5a and the combustion grate 5b, and the mixed gas having a lower oxygen concentration than the case where the conventional air is blown is supplied. Therefore, the atmosphere in which the waste burns on the grate is formed into an atmosphere having an air ratio within a predetermined range, and the generation of fuel NOx generated from the nitrogen of the waste is suppressed.

When supplying the mixed gas, the circulating exhaust gas supply amount and the primary air supply amount are adjusted by the mixed gas oxygen amount control means (dampers 16a, 16b, dampers 19a, 19b) to control the oxygen amount of the mixed gas, conventionally. By supplying a mixed gas with a lower oxygen concentration than when the air is blown in, the region from the combustion start region to the main combustion region, that is, the dry grate and the waste combustion space above the combustion grate The atmosphere is such that the air ratio is 0.6 to 0.8.

The amount of circulating exhaust gas supply and the amount of primary air supply are adjusted by the mixed gas oxygen amount control means, and the oxygen amount of the mixed gas is controlled to produce waste in an oxygen atmosphere with an air ratio of 0.6 to 0.8. By performing thermal decomposition and partial oxidation, it is possible to suppress the reaction of nitrogen contained in the waste to generate fuel NOx.

Further, by the air ratio is burned waste in an oxygen atmosphere at 0.6 to 0.8, combustible gas as the gas component _(CO, H 2, CmHn) and a reducing gas (CO, HCN, NHn, CmHn ) (CO, CmHn are flammable). The generated flammable gas is uniformly and stably burned in the planar combustion region formed as described above. The generated reducing gas is guided downstream in the combustion chamber 2 and used to decompose the generated NOx, and reduces the NOx concentration in the exhaust gas.

It is preferable to control the amount of oxygen in the mixed gas so that the atmosphere in which the waste on the grate burns is an oxygen atmosphere having an air ratio of 0.6 to 0.8. If the air ratio is less than 0.6, the amount of oxygen required for combustion of waste is insufficient and combustion becomes unstable, and the generation of reduced gas becomes excessive, resulting in NOx on the wake side from excess NHn. Is unsuitable because the amount of unburned gas generated becomes excessive due to the generation of flammable gas, and if the air ratio is larger than 0.8, the atmosphere does not suppress the oxygen concentration and fuel. Since the amount of NOx generated is large and unsuitable, the air ratio is preferably 0.6 to 0.8.

The NOx concentration is measured by a NOx concentration meter that measures the NOx concentration in the exhaust gas discharged from the waste heat boiler 4, and the oxygen amount of the mixed gas is controlled based on the measured NOx concentration to burn the waste on the grate. The supply amounts of the circulating exhaust gas and the primary air may be controlled so that the atmosphere is an atmosphere having an air ratio within a predetermined range.

<Combustion stabilization by blowing high temperature gas>
As can be seen in FIG. 1, high temperature gas is blown from the high temperature gas inlets 15a and 15b toward the region from the combustion start region to the main combustion region, and is downward or oblique toward the waste layer on the grate. It is blown down. Since it is preferable to blow a high temperature gas into a region where a flame is present and a large amount of flammable gas is present in order to stabilize combustion, the above high temperature is formed in a region from a combustion start region to a combustion region where a large amount of flammable gas is present. It blows gas.

High temperature blown downward by blowing high temperature gas from the high temperature gas inlets 15a and 15b into the region from the combustion start region to the combustion region in the combustion chamber 2 and downward or diagonally downward toward directly above the waste layer. The gas faces the ascending flow of the combustible gas and the combustion gas generated by the thermal decomposition / partial oxidation of the waste, and both gas flows collide with each other, resulting in a flat stagnation region or a slow-flowing region directly above the waste layer. A circulation region that circulates in the vertical direction is created. Since the gas flow speed is slow in these regions, a flame for burning flammable gas is standing, that is, a flat combustion region (flat flame) is standing just above the waste layer, and the flammable gas is present. It burns stably. As a result, it is possible to suppress the generation of harmful substances such as CO, NOx and dioxins and the generation of soot even in low air ratio combustion. Therefore, low air ratio combustion can be performed without any trouble.

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

Next, the preparation of the high temperature gas and the air outlet will be described in sequence.

<Preparation of high temperature gas>
The temperature of the high-temperature gas blown from the high-temperature gas inlet is preferably in the range of 100 to 400 ° C, more preferably about 200 ° C. When a gas having a temperature lower than 100 ° C. is blown in, the temperature inside the furnace drops, combustion becomes unstable, and the amount of CO generated increases. When a gas exceeding 400 ° C. is blown in, the flame temperature in the combustion chamber becomes extremely high, which causes problems such as promoting the formation of clinker.

The oxygen concentration of the high temperature gas is preferably about 5 to 30% by volume, preferably 5 to 15% by volume. As a result, the above-mentioned effects are more effectively exhibited, and the reduction of NOx and low CO of exhaust gas is further promoted.

As the high-temperature gas having the above-mentioned gas temperature and oxygen concentration, it is preferable to use a mixed gas of circulating exhaust gas and high-temperature air obtained by extracting a part of the exhaust gas collected by the dust collector 12. The temperature and oxygen concentration of the high-temperature gas are set in a desired range by adjusting the mixing ratio of the circulating exhaust gas and the air when preparing the high-temperature gas, the heating conditions of the circulating exhaust gas or the mixed gas of the circulating exhaust gas and the air, and the like.

<High temperature gas outlet>
Of the two high-temperature gas inlets 15a and 15b provided as the high-temperature gas supply means, the high-temperature gas inlet 15a in the front stage is located on the side wall or ceiling of the combustion chamber 2 on the downstream side in the moving direction of the waste of the dry grate 5a. It is provided at a position directly above the grate within the installation range from (rear part) to the upstream side (front part) of the combustion grate 5b in the moving direction.

Further, the high temperature gas inlet 15b in the latter stage is located on the side wall or ceiling of the combustion chamber 2 from the downstream side (rear part) in the moving direction of the waste of the combustion grate 5b to the upstream side (front part) in the moving direction of the rear combustion grate 5c. It is installed at a position directly above the grate within the installation range of.

A plurality of high temperature gas inlets 15a and 15b are arranged in the width direction of the combustion chamber 2, respectively. Further, a plurality of combustion chambers 2 may be arranged in each range in the length direction. The high temperature gas outlet may be a nozzle type or a slit type.

The high-temperature gas supply means faces the ascending flow from the waste so that a flat combustion region is formed over a wide range in the width direction and the length direction directly above the waste layer in the combustion chamber. By controlling the flow condition of the high temperature gas to a favorable state, at least of the arrangement position, the number of arrangements, the arrangement interval, the blowing direction, the shape of the blowing port, the blowing flow velocity of the high temperature gas, and the blowing flow rate of the high temperature gas blowing port. Set or adjust one. The countercurrent is a flow field created by the collision of the blown high-temperature gas with the flammable gas generated by the thermal decomposition / partial oxidation of waste and the ascending flow of the combustion gas.

The blowing speed of the high-temperature gas from the high-temperature gas inlet is adjusted by, for example, adjusting the air flow rate of a blower (not shown) that sends the high-temperature gas or adjusting the flow rate by adjusting the opening degree of the damper.

As described above, according to the present invention, a stable stagnation region or a circulation region can be formed in the vicinity directly above the waste layer in the combustion chamber by blowing high-temperature gas, and a flat combustion region is settled to make waste. Regardless of the size of the incinerator, even when low air ratio combustion with an air ratio of 1.5 or less is performed, combustion stability is maintained over the entire width and length directions of the combustion chamber. In addition, by blowing a mixed gas with an adjusted amount of oxygen from below the dry grate and the combustion grate, the waste is thermally decomposed and partially oxidized under an oxygen atmosphere with an air ratio within a predetermined range, and then discarded. Provided are a waste incineration apparatus and a waste incineration method capable of suppressing the reaction of nitrogen contained in a substance to generate fuel NOx and reducing the amount of harmful gas such as CO and NOx generated. Further, since combustion can be performed at a lower air ratio than before, the total amount of exhaust gas discharged from the incinerator can be further significantly reduced, and a waste incineration device and a waste incineration method capable of improving the recovery efficiency of waste heat are provided. ..

<Second circulation exhaust gas supply>
The circulating exhaust gas, which is a part of the exhaust gas discharged from the incinerator 1, is blown into the combustion chamber 2 above the blowing position of the high-temperature gas or downstream in the furnace gas flow direction as the second circulating exhaust gas. The downstream side in the gas flow direction means the downstream side with respect to the gas flow direction in the furnace. The gas in the furnace mainly means combustible gas and combustion exhaust gas generated in the combustion chamber. In the region above the blowing position of the high temperature gas in the combustion chamber 2 or on the downstream side in the gas flow direction in the furnace, the pyrolysis gas generated by the thermal decomposition of the waste is burned. Here, as the circulating exhaust gas that is a part of the exhaust gas discharged from the incinerator, a gas that is discharged from the incinerator 1 and cooled by the temperature reducing tower 11 and removed by the dust collector 12 is extracted. (Gas temperature: about 150 to 200 ° C., oxygen concentration: about 4 to 8% by volume) can be used. Further, the circulating exhaust gas may be a mixture of a part of the exhaust gas and air.

By blowing the circulating exhaust gas above the blowing position of the high temperature gas or downstream in the gas flow direction (waste pyrolysis gas combustion region) by the second circulating exhaust gas means, it is stabilized by blowing the high temperature gas in the combustion chamber 2. It lowers the flame temperature above the converted combustion region or downstream in the gas flow direction, prevents the generation of a wide range of high temperature regions, and effectively suppresses the generation of thermal NOx. Further, by blowing the circulating exhaust gas having a low oxygen concentration (about 4 to 8% by volume), the region above the blowing position of the high-temperature gas or the region on the downstream side in the gas flow direction is brought closer to the reducing atmosphere, and the generation of NOx is suppressed.

Here, by blowing the circulating exhaust gas from the circulating exhaust gas inlet 22 into the upper part of the gas stagnation region or the downstream side region in the gas flow direction formed by the blowing of the high temperature gas, the upper side of the stagnation region or the downstream side in the gas flow direction is blown. By suppressing the generation of the local high temperature region in, that is, averaging the temperature distribution, and further averaging the oxygen concentration distribution by promoting stirring in the region, the generation of thermal NOx is suppressed and the amount of oxygen is reduced. By supplying a controlled mixed gas from below the grate, the generation of fuel NOx is further suppressed effectively by suppressing the generation of fuel NOx due to the combustion of waste in an oxygen atmosphere where the air ratio is within a predetermined range. It will be possible to achieve.

The purpose of the second circulating exhaust gas inlet 22 is to average the gas temperature distribution and oxygen concentration distribution above the gas stagnation region or the region downstream in the gas flow direction formed by blowing high-temperature gas. Therefore, it is not essential to provide at least a pair facing each other or so that the gas blowing direction is horizontal or downward.

[Second Embodiment]
Next, only the points different from the first embodiment of FIG. 1 will be described with respect to the second embodiment shown in FIG. 2, and the common points will be designated by the same reference numerals, and the description thereof will be omitted.

In the first embodiment, the primary air supply pipe 9 is connected to each of the air box 7a of the dry grate 5a, the air box 7b of the combustion grate 5b, and the air box 7c of the post-combustion grate 5c to supply the primary air. However, in the second embodiment of FIG. 2, the primary air is not supplied to the air box 7c of the post-combustion grate 5c. Instead, the branch supply pipe 17c of the circulating exhaust gas supply pipe 17 is connected to the air box 7c of the post-combustion grate 5c via a damper 19c. Thus, the post-combustion grate 5c is supplied with the circulating exhaust gas instead of the primary air.

As described above, in the present embodiment, the unburned solid content on the post-combustion grate 5c is burned by supplying the circulating exhaust gas from the branch supply pipe 17c below the post-combustion grate 5c, and the combustion chamber It is possible to suppress the generation of thermal NOx by stirring the gas of the above and suppressing the generation of the local high temperature region.

Since most of the waste is substantially burned on the combustion grate 5b, the amount of unburned solids existing on the post-combustion grate 5c is small, so that the amount of oxygen required for burning the unburned solids is It can be covered by the amount of oxygen contained in the circulating exhaust gas. It is preferable that the air ratio, which is the ratio of the amount of oxygen supplied by the circulating exhaust gas to the amount of theoretical oxygen required for burning the unburned solids on the post-combustion grate 5c, is 1.0 or more.

In the present embodiment, in the waste incinerator 1, at least one of the dry grate 5a and the combustion grate 5b is used as one of the exhaust gas of the waste incinerator 1 in the primary air for combustion sent from below the grate. The circulating exhaust gas from which the parts have been extracted is mixed, and this is supplied to the combustion chamber 2 as a mixed gas to incinerate the waste, the oxygen amount of the mixed gas is controlled, and the waste on the dry grate 5a and the combustion grate 5b is controlled. The primary air supply amount and the circulating exhaust gas supply amount are controlled so that the air ratio, which is the ratio of the oxygen amount of the mixed gas to the theoretical oxygen amount required for combustion, is within a predetermined range, and below the post-combustion grate 5c. It is supposed to supply the circulating exhaust gas from.

According to this embodiment, by controlling the amount of oxygen in the mixed gas, it is possible to reduce the air ratio of the atmosphere in which the waste is thermally decomposed and partially oxidized, and the generation of fuel NOx can be suppressed, and later By supplying the circulating exhaust gas from below the combustion grate 5c into the combustion chamber, the combustion chamber gas can be agitated to suppress the generation of local high temperature regions and the generation of thermal NOx can be suppressed, and fuel NOx and thermal NOx can be suppressed. It is possible to suppress the generation and reduce the NOx contained in the exhaust gas and discharged.

1 Incinerator 2 Combustion chamber 5a-5c Grate 5a Dry grate 5b Combustion grate 8, 9 Primary air supply means 8 Blower 9 Primary air supply pipe 16a, 16b Mixed gas Oxygen amount control means (damper)
17, 18 Circulating exhaust gas supply means 17 Circulating exhaust gas supply pipe 18 Blower 19a, 19b Mixed gas oxygen amount control means (damper)
20 High temperature gas supply means (branch supply pipe)

Claims (12)

In a waste incinerator equipped with a waste incinerator that burns waste in a combustion chamber equipped with a grate,
A primary air supply means that supplies primary air for combustion from below the dry grate, combustion grate, and post-combustion grate,
A part of exhaust gas of the incinerator, at the drying grate and the layer of waste layer on at least one of the grate of the combustion grate is contacted with waste as circulation flue gas, the waste within the layer after rise pass A circulating exhaust gas supply means that supplies from below at least one of the dry grate and the combustion grate so as to blow directly into the waste thermal decomposition region that forms the space directly above the material layer .
A high-temperature gas supply means for supplying high-temperature gas at 100 to 400 ° C. from the side wall or ceiling of the combustion chamber,
A mixed gas oxygen amount controlling means for controlling the oxygen amount of the mixed gas of the primary air supplied from below the dry grate and the combustion grate and the circulating exhaust gas supplied from below at least one of the dry grate and the combustion grate. Equipped with
The mixed gas oxygen amount control means sets the air ratio, which is the ratio of the oxygen amount of the mixed gas to the theoretical oxygen amount required for burning the waste on the dry grate and the combustion grate, within a predetermined range. A waste incinerator including a waste incinerator, which controls a primary air supply amount by a supply means and a circulation exhaust gas supply amount by a circulating exhaust gas supply means. The waste incinerator including the waste incinerator according to claim 1, wherein the mixed gas oxygen amount control means controls the air ratio to 0.6 to 0.8. The waste incinerator is further provided with a second circulating exhaust gas supply means for supplying a part of the exhaust gas of the incinerator from the side wall or the ceiling of the combustion chamber to the waste pyrolysis gas combustion region. A waste incinerator including the waste incinerator according to claim 2. In a waste incinerator equipped with a waste incinerator that burns waste in a combustion chamber equipped with a grate,
A primary air supply means for supplying primary air for combustion from below the dry grate and the combustion grate,
A part of exhaust gas of the incinerator, at the drying grate and the layer of waste layer on at least one of the grate of the combustion grate is contacted with waste as circulation flue gas, the waste within the layer after rise pass A circulating exhaust gas supply means for supplying from below at least one of the dry grate and the combustion grate and from below the post-combustion grate so as to blow directly into the waste thermal decomposition region forming the space directly above the material layer .
A high-temperature gas supply means for supplying high-temperature gas at 100 to 400 ° C. from the side wall or ceiling of the combustion chamber,
A mixed gas oxygen amount controlling means for controlling the oxygen amount of the mixed gas of the primary air supplied from below the dry grate and the combustion grate and the circulating exhaust gas supplied from below at least one of the dry grate and the combustion grate. Equipped with
The mixed gas oxygen amount controlling means sets the air ratio, which is the ratio of the oxygen amount of the mixed gas to the theoretical oxygen amount required for burning the waste on the dry grate and the combustion grate, within a predetermined range. Waste provided with a waste incinerator, which is characterized by controlling the supply amount of primary air by the supply means and the supply amount of the circulating exhaust gas supplied from below at least one of the dry grate and the combustion grate by the circulating exhaust gas supply means. Incinerator. The waste incinerator including the waste incinerator according to claim 4, wherein the mixed gas oxygen amount control means controls the air ratio to 0.6 to 0.8. The waste incinerator is further provided with a second circulating exhaust gas supply means for supplying a part of the exhaust gas of the incinerator from the side wall or the ceiling of the combustion chamber to the waste pyrolysis gas combustion region. A waste incinerator including the waste incinerator according to claim 5. In the waste incineration method in a waste incinerator equipped with a waste incinerator that burns waste in a combustion chamber equipped with a grate,
Primary air for combustion is supplied from below the dry grate, combustion grate and post-combustion grate.
A part of exhaust gas of the incinerator, at the drying grate and the layer of waste layer on at least one of the grate of the combustion grate is contacted with waste as circulation flue gas, the waste within the layer after rise pass Supply from below at least one of the dry grate and the combustion grate so as to blow directly into the waste thermal decomposition region that forms the space directly above the material layer .
A high temperature gas of 100 to 400 ° C. is supplied from the side wall or ceiling of the combustion chamber.
Control the amount of oxygen in the mixed gas of the primary air supplied from below the dry grate and the combustion grate and the circulating exhaust gas supplied from below at least one of the dry grate and the combustion grate.
The control of the oxygen content of the mixed gas is primary so that the air ratio, which is the ratio of the oxygen content of the mixed gas to the theoretical oxygen content required for burning the waste on the dry grate and the combustion grate, is within a predetermined range. A waste incineration method characterized by controlling the amount of air supply and the amount of circulating exhaust gas supplied. The waste incineration method according to claim 7, wherein the air ratio of the mixed gas is controlled to 0.6 to 0.8. The waste incineration method according to claim 7 or 8, wherein a part of the exhaust gas of the incinerator is further supplied from the side wall or the ceiling of the combustion chamber to the waste pyrolysis gas combustion region. In the waste incineration method in a waste incinerator equipped with a waste incinerator that burns waste in a combustion chamber equipped with a grate,
The primary air for combustion is supplied from below the dry grate and the combustion grate,
A part of exhaust gas of the incinerator, at the drying grate and the layer of waste layer on at least one of the grate of the combustion grate is contacted with waste as circulation flue gas, the waste within the layer after rise pass It is supplied from below at least one of the dry grate and the combustion grate and from below the post-combustion grate so as to blow directly into the waste pyrolysis region that forms the space directly above the material layer .
A high temperature gas of 100 to 400 ° C. is supplied from the side wall or ceiling of the combustion chamber.
Control the amount of oxygen in the mixed gas of the primary air supplied from below the dry grate and the combustion grate and the circulating exhaust gas supplied from below at least one of the dry grate and the combustion grate.
The control of the oxygen amount of the mixed gas is primary so that the air ratio, which is the ratio of the oxygen amount of the mixed gas to the theoretical oxygen amount required for burning the waste on the dry grate and the combustion grate, is within a predetermined range. A waste incineration method comprising controlling the amount of air supply and the amount of circulating exhaust gas supplied from below at least one of a dry grate and a combustion grate. The waste incineration method according to claim 10, wherein the air ratio of the mixed gas is controlled to 0.6 to 0.8. The waste incineration method according to claim 10 or 11, wherein a part of the exhaust gas of the incinerator is further supplied from the side wall or the ceiling of the combustion chamber to the waste pyrolysis gas combustion region.

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