JP2004077014A - Operation method of waste incinerator - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an operation method of a waste incinerator injecting a high-temperature gas into a combustion chamber, in particular, to provide the operation method of the waste incinerator for efficiently inhibiting the generation of CO and Dioxin in a low air-fuel ratio combustion operation method. <P>SOLUTION: The generation of CO and Dioxin can be reduced in the waste incinerator when a condition that a temperature T is positioned higher than an A-line in a drawing when a temperature in the high-temperature gas is T (°C), and the concentration of oxygen is C (vol.%), even though the temperature T (°C) of the high-temperature gas is less than 200 when the high-temperature gas is injected into the combustion chamber. The A-line is represented by T=exp(7.78-0.18C). <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a method for operating a waste incinerator for incinerating waste such as general waste, industrial waste, and sewage sludge.
[0002]
[Prior art]
Grate or fluidized bed waste incinerators are widely used as incinerators for incinerating waste such as municipal waste. FIG. 7 shows a schematic diagram of a typical example. The waste 32 put into the hopper 31 is sent to the drying stoker 33 through the chute, dried by the air from below and the radiant heat in the furnace, and heated to ignite. The refuse 32 that has ignited and started burning is sent to a combustion stoker 34, gasified by combustion air sent from below, and partly burned. Further, the unburned components in the waste are completely burned by the post-combustion stoker 35. The ash remaining after the combustion is taken out from the main ash chute 36.
[0003]
The combustion is performed in the main combustion chamber 37, and the generated combustion gas is discharged separately to the main flue 39 and the sub-flue 40 due to the presence of the intermediate ceiling 38. The exhaust gas passing through the main flue 39 contains almost no unburned components and contains about 10% of oxygen. The exhaust gas passing through the sub-flue 40 contains about 8% of unburned gas. These exhaust gases are mixed in the secondary combustion chamber 41, secondary combustion is performed, and the unburned gas is completely burned. Exhaust gas from the secondary combustion chamber 41 is sent to a waste heat boiler 43, and after being subjected to heat exchange, is discharged outside through a cooling tower, a bag filter and the like.
[0004]
In such a grate or fluidized bed waste incinerator, when incinerating waste, it is difficult to maintain a constant combustion state in the furnace because the waste consists of many substances with different properties. Therefore, it is inevitable that the distribution of the temperature and the concentration of the combustion gas in the main combustion chamber 37 become non-uniform over time and space.
[0005]
As a method for solving such a problem, Japanese Patent Application Laid-Open No. H11-211044 (Patent Document 1) discloses a method in which a high-temperature gas generated by a regenerative burner is blown into a main combustion chamber or a secondary combustion chamber of an incinerator. Is disclosed.
[0006]
Japanese Patent Application Laid-Open No. H11-223323 (Patent Document 2) discloses a method in which a high-temperature gas generated by a regenerative burner is blown into a furnace at a temperature of 800 ° C. or more. These techniques are all aimed at reducing unburned gas, harmful substances, and the like, which contain a large amount of CO and aromatic hydrocarbons, in exhaust gas generated in an incinerator.
[0007]
[Patent Document 1]
Japanese Patent Application Laid-Open No. H11-211044 [Patent Document 2]
JP-A-11-223323
[Problems to be solved by the invention]
However, in the technology disclosed in Japanese Patent Application Laid-Open No. H11-211044, since the oxygen concentration in the high-temperature gas is 20% or more, when such a high-temperature gas is blown into the incinerator, it suddenly enters the incinerator. Combustion proceeds, and a local high-temperature region may be formed. When the local high-temperature region is formed, for example, there is a problem that the generation amount of the harmful substance NOx increases.
[0009]
In addition, in the technique described in Japanese Patent Application Laid-Open No. 11-223323, in addition to the above-mentioned problems, since oxygen-containing gas is blown into the main combustion chamber at a temperature of 800 ° C. or more, thermal decomposition and partial oxidation of wastes are performed. The reaction is accelerated, and in some cases, CO may be generated.
[0010]
As described above, it is difficult to sufficiently reduce harmful substances including NOx, CO and dioxin in exhaust gas when incinerating waste by an incinerator such as a grate incinerator in any of the above techniques. There is a problem that there is.
[0011]
Conventionally, in a waste incinerator, a ratio (air ratio) obtained by dividing an actual air amount by a theoretical air amount necessary for combustion of the waste is about 1.7 to 2.0. This is larger than the air ratio of 1.05 to 1.2 required for normal combustion. The reason for this is that waste has a large amount of non-combustible components and is inhomogeneous, so that a large amount of air is required to perform combustion. However, as the air ratio increases, the amount of exhaust gas also increases, and large exhaust gas treatment equipment is required as compared with a normal combustion furnace.
[0012]
If the air ratio is reduced, the amount of exhaust gas is reduced, and the exhaust gas treatment facility is made compact. As a result, the entire waste incineration facility can be reduced in size and the facility cost can be reduced. In addition to this, the amount of chemicals for exhaust gas treatment can be reduced, so that operating costs can be reduced. Further, since the amount of heat lost due to the inability to recover heat can be reduced, the heat recovery rate of the waste heat boiler is improved, and accordingly, the power generation efficiency of waste power generation can be increased.
[0013]
As described above, although the advantage for the low air ratio combustion is great, there is a problem that the combustion becomes unstable in the low air ratio combustion. That is, according to the conventional combustion technology, when the combustion is performed at a low air ratio, the combustion becomes unstable, the generation of CO increases, the flame temperature locally rises, the NOx rapidly increases, and a large amount of soot is generated. There is a problem that the life of the refractory of the furnace is shortened due to the occurrence of clinker, clinker, or local high temperature.
[0014]
Furthermore, in the techniques described in the above two documents, high-temperature air is blown, but there is a problem that the emissivity of the high-temperature air is low, and the combustion gas cannot be sufficiently heated by radiant heat transfer. Therefore, there is a problem that there is a limit in reducing CO and NOx in the exhaust gas.
[0015]
The present invention has been made in view of such circumstances, and in a method of operating a waste incinerator that blows gas into a combustion chamber, particularly in a low air ratio combustion operation method, it is possible to efficiently suppress the generation of CO and dioxin. It is an object of the present invention to provide a method of operating a waste incinerator capable of reducing waste.
[0016]
[Means for Solving the Problems]
A first means for solving the above-mentioned problem is that, in a combustion chamber of a waste incinerator, the temperature T [° C.] is less than 200 and the concentration of oxygen contained therein [vol. %] A method for operating a waste incinerator characterized by blowing a high-temperature gas having a relationship with C in the range represented by the following formula (Claim 1).
T ≧ exp (7.78-0.18C) (1)
[0017]
In a waste incinerator, the inventors have found that the relationship between the effect of lowering CO and NOx by blowing high-temperature gas into the combustion chamber, the oxygen concentration in the high-temperature gas blown into the combustion chamber, and the temperature of the high-temperature gas is as follows. A survey was conducted. When the temperature of the high-temperature gas to be blown is lower than 200 ° C., the effect of reducing NOx is reduced. In general, when the temperature of the high-temperature gas is lower than 200 ° C., the thermal decomposition of waste is considerably accelerated. Since the effect of blowing high-temperature gas is not so high, another application has been filed in which the properties of high-temperature gas to be blown are specified within a range in which the temperature of high-temperature gas is limited to 200 ° C. or higher.
[0018]
However, even when the temperature is lower than 200 ° C., if the expression (1) is satisfied, there is an effect of suppressing the generation of CO and dioxin. When the waste contains biomass and wood chips, thermal decomposition is started even at a temperature lower than 200 ° C., and unburned gas is generated. In these cases, the temperature at which thermal decomposition starts is generally 100 ° C. or higher.
[0019]
Therefore, even if the temperature of the high-temperature gas is lower than 200 ° C., when unburned gas is generated, an effect of reducing CO and dioxin can be expected by blowing the high-temperature gas satisfying the expression (1). In this case, although the effect of reducing NOx is smaller than when the temperature of the high-temperature gas is 200 ° C. or higher, it can be dealt with by providing a denitration facility.
[0020]
FIG. 1 shows the relationship between the temperature of the high-temperature gas and the oxygen concentration in this means. In general, the use of a high-temperature oxygen-enriched gas in the air increases the amount of NOx generated. Therefore, it is preferable that the oxygen concentration be 21% or less.
[0021]
In FIG. 1, line A corresponds to T = exp (7.78-0.18C), line B corresponds to C = 21, and line C corresponds to T = 200. By blowing high-temperature gas with the oxygen concentration and temperature in the area surrounded by the A-line, B-line, and C-line into the combustion chamber, the thermal decomposition of waste is promoted and a stable flame is established on the waste layer. Can be done. Further, since the mixed combustion of the unburned gas is promoted, uniform and stable combustion is performed, and the generation of harmful substances such as CO and dioxin can be reduced.
[0022]
A second means for solving the above-mentioned problem is that at least one of carbon dioxide and water vapor is contained in a combustion chamber of a waste incinerator, and the temperature T [° C.] is less than 200; Concentration [vol. %] A method for operating a waste incinerator characterized by blowing a high-temperature gas having a relationship with C in the range represented by the following formula (Claim 2).
T ≧ exp (8.05-0.23C) (2)
[0023]
In this means, at least one of carbon dioxide and water vapor is contained in the high-temperature gas blown into the combustion chamber. Since the emissivity of carbon dioxide and water vapor is higher than that of nitrogen or oxygen, heat radiation from high-temperature gas containing these gases heats waste or unburned gas generated from waste, and is stable even at low air ratio combustion. Combustion is performed. As a result, the generation of CO and dioxin can be efficiently reduced.
[0024]
The inventors conducted the investigation described in the description of the first means also in the case of blowing a high-temperature gas containing at least one of carbon dioxide and water vapor. As a result, even if the temperature of the high-temperature gas containing at least one of carbon dioxide and water vapor is lower than 200 ° C., it is found that blowing a high-temperature gas satisfying the expression (2) has an effect of reducing CO and dioxins. Was.
[0025]
A preferable range of the temperature and the oxygen concentration of the high-temperature gas is a region surrounded by lines D, E, and F in FIG. The D line corresponds to T = exp (8.05-0.23C), the E line corresponds to C = 21, and the F line corresponds to T = 200. By blowing a high-temperature gas containing at least one of carbon dioxide and water vapor having a temperature and an oxygen concentration in this range into the combustion chamber, an effect of reducing CO and dioxin in exhaust gas can be obtained.
[0026]
In many waste incinerators of the grate type, the fluidized bed type and the like, a place where unburned gas starts to be generated is a combustion start region. Therefore, it is preferable to blow high-temperature gas into the combustion start region.
[0027]
Further, it is preferable that the blowing amount of the high-temperature gas is 10% to 70% of the primary air amount. The primary air is air blown for the purpose of burning waste, and is air blown in a conventional waste incinerator that does not blow hot gas. Generally, it is blown from below the grate in the case of a grate furnace, and below the fluidized bed in the case of a fluidized bed furnace.
[0028]
If the amount of high-temperature gas blown is less than 10% of the amount of primary air, there is no momentum required for gas stirring in the furnace, and the effect of high-temperature gas blown may not be sufficiently exhibited. If the amount of high-temperature gas blown exceeds 70% of the amount of primary air, the effect of lowering NOx and CO in exhaust gas is saturated, and it is not only meaningless to increase the amount of high-temperature gas blown but also unnecessarily. It is not preferable because the amount is increased and the number of exhaust gas treatment facilities is increased.
[0029]
In the above-described case, the primary air amount is used as the reference value of the hot gas blowing amount. In some cases, however, the primary air amount may be equal to or less than the theoretical air amount required to completely burn the waste. In such a case, it is preferable that the blowing amount of the high-temperature gas be 10% to 70% of the theoretical air amount for burning the waste. The theoretical amount of air is determined from the type of waste.
[0030]
The unburned gas generated from the waste usually flows upward. Therefore, when the blowing direction of the high-temperature gas is upward, the flow of the unburned gas and the flow of the high-temperature gas have velocity components in the same direction, and the effect of the stirring becomes small, and the effect of the high-temperature gas blowing is reduced. On the other hand, if the blowing direction of the high-temperature gas is horizontal or downward, the rising unburned gas and the high-temperature gas are well stirred, and the blowing effect of the high-temperature gas can be enhanced. Generally, the factor that is effective in blowing high-temperature gas is said to be 3T. These are temperature (Temperature), stirring (Turbulence), and residence time (Time). In particular, by blowing high-temperature gas downward, the stirring (Turbulence) and residence time (Time) can be improved.
[0031]
Further, by blowing the high-temperature gas as a swirling flow, the stirring effect can be enhanced, and the blowing effect of the high-temperature gas can be enhanced. “Injecting a high-temperature gas as a swirl flow” means that the high-temperature gas flowing out from the outlet is a swirl flow, and the flow of the high-temperature gas flowing from a plurality of outlets is combined into a swirl flow. Including cases.
[0032]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 3 is a diagram illustrating an example of a waste incinerator that implements a method for operating a waste incinerator according to an embodiment of the present invention. Reference numeral 1 in FIG. 3 denotes a main combustion chamber, and on one side of the main combustion chamber 1 (left side in FIG. 3), a hopper 2 for charging waste 3 into the main combustion chamber 1 is provided. I have.
[0033]
At the bottom of the main combustion chamber 1, a mesh-shaped grate (stoker) that burns while moving the waste 3 is provided so as to be inclined downward as it moves away from the hopper 2. This grate has two steps, which are divided into three parts. These three grate are called a dry stoker 4, a burning stoker 5, and a post-burning stoker 6 from the side closer to the hopper 2. In the drying stoker 4, drying and ignition of the waste 3 are mainly performed. In the combustion stoker 5, the waste 3 is mainly burned. The waste 3 is burned and thermally decomposed, and releases unburned gas together with the combustion gas. In the combustion stoker 5, the combustion of the waste 3 is substantially completed. On the post-combustion stoker 6, the unburned portion of the waste 3 remaining slightly is completely burned. The combustion residue after complete combustion is discharged from the main ash chute 7.
At the lower part of each grate, a wind box 8 connected to a supply pipe for supplying combustion air is provided.
[0034]
A main flue 9 and a sub flue 10 are provided below and above the main combustion chamber 1 on the side opposite to the hopper 2, and these are provided with secondary combustion of a waste heat boiler 11 which is a part of a gas cooling system. A chamber 12 is provided connected. In the main combustion chamber 1, an intermediate ceiling 13 for diverting the combustion gas is provided near the outlet of the main combustion chamber 1, and divides the flow of the combustion gas into the main flue 9 and the auxiliary flue 10. ing.
[0035]
As shown in FIG. 3, the waste 3 is put into the main combustion chamber 1 from the hopper 2, and the combustion air is supplied to the waste 3 moving on the grate through each supply pipe and the wind box 8. The waste 3 is dried and burned.
[0036]
A nozzle 14 is provided on a side wall of the main combustion chamber 1, and a high-temperature gas is blown into the main combustion chamber 1 from the nozzle 14. The high-temperature gas is adjusted so that the temperature at the time of injection is less than 200 ° C. and the relationship between the temperature and the oxygen concentration satisfies the above expression (1) or (2).
[0037]
In FIG. 3, the nozzle 14 is provided above the drying stoker 4. When the waste 3 is incinerated, evaporation of water occurs first, followed by thermal decomposition and partial oxidation. Here, when the waste 3 contains biomass or wood chips, the thermal decomposition reaction occurs at a temperature of about 100 ° C. In the example shown in FIG. 3, the nozzle corresponds to the portion of the drying stoker 4, so the nozzles 14 are provided at these positions to blow the high-temperature gas.
[0038]
The amount of high-temperature gas to be blown is preferably as small as possible in consideration of exhaust gas treatment and the like. However, when the blowing amount is small, CO is likely to be generated, and complete combustion cannot be performed. For this reason, it is desirable that the blowing amount is 10% to 70% of the primary air amount blown from the wind box 8. As a result, the generation of CO can be suppressed to a level that causes no problem. As described above, the amount of the high-temperature gas to be blown is preferably as small as possible within a range in which the object is achieved. Therefore, it is preferable to adjust the blowing amount in the range of 10% to 70% of the primary air amount while monitoring the amount of CO and NOx discharged.
[0039]
In particular, when the type of the waste 3 is changed, the amount of the primary air to be blown may be smaller than the theoretical amount of air required for burning the waste 3, and in this case, a large amount of hot gas Is preferably blown to promote complete combustion of the waste 3 to prevent generation of CO.
[0040]
If it is known that the amount of the primary air to be blown is small, the amount of the hot gas to be blown may be in the range of 10% to 70% of the theoretical air amount required for burning the waste 3. Good.
[0041]
In FIG. 3, nozzles 14 are provided on both sides of the furnace, and hot gas is blown from the nozzles 14. The nozzle is preferably provided horizontally or downward. In this manner, the rising unburned gas and the high-temperature gas spouted from the nozzle cause a stirring action to promote the combustion of the unburned gas. In order to promote the stirring action, it is preferable that the nozzle is provided downward. However, if the nozzle is too angled, the high-temperature gas will not reach the entire furnace width direction. Therefore, it is particularly preferable that the angle is in the range of 10 to 20 degrees downward.
[0042]
Furthermore, in order to exert a stirring action of the high-temperature gas on the entire furnace width direction, the blowing speed of the high-temperature gas is set to 20 W [m / s] or more when the furnace width is W [m]. By performing such high-speed blowing, a stagnation region of unburned gas is formed in the incinerator. As a result, the residence time of the unburned gas in the furnace becomes longer, and the reaction time with the high-temperature gas becomes longer, so that the reaction is sufficiently performed. In order to form the stagnation region, it is particularly effective to place the nozzle downward.
[0043]
FIG. 4 shows an AA ′ sectional view and a BB ′ sectional view to show the arrangement of the nozzles in FIG. However, in FIG. 4, structures not related to the present invention are not shown. In FIG. 4, 15 is a stagnation area, 17 is a furnace wall, 18 is a furnace ceiling, 19 is an air flow, 20 is a swirling portion, and 21 is unburned gas.
[0044]
High-temperature gas is ejected from a pair of nozzles 14 provided on the left and right sides of the furnace wall 17 to become a high-temperature gas (flow) 19, which is a plan cross-sectional view taken along the line AA '(a). As you can see, they collide with each other at the center of the furnace. Therefore, the stagnation region (combustion stable region) 15 in which the movement of the gas in the furnace is slow and stagnates is formed in the central portion of the furnace.
[0045]
FIG. 4B is a plan sectional view showing another embodiment. The directions of the nozzles 14 are such that their central axes are parallel to each other and are separated by a predetermined distance, and the hot gas 19 passes by a predetermined distance at the center of the furnace. Therefore, a swirling flow portion (swirl region) 20 is formed at the center of the furnace.
[0046]
That is, in this embodiment, the stagnation region 15 or the swirling flow portion 20 is formed at the center of the furnace when viewed in plan. Therefore, as described above, the flame is stabilized and the mixing of the gases is promoted.
[0047]
In FIG. 4A, the size of the stagnation region 15 can be controlled by changing the flow velocity of the hot gas ejected from the two nozzles 14 in the same manner. Further, by providing a difference in the flow rate of the high-temperature gas ejected from both nozzles 14, the position of the stagnation region 15 in the left-right direction of the furnace can be changed. Furthermore, by changing the direction of the nozzle 14 in the same direction as the front-rear direction of the furnace, the position of the stagnation region 15 in the front-rear direction of the furnace can be changed.
[0048]
In FIG. 4B, the size of the swirling flow portion 20 can be changed by changing the interval between the two high-temperature gases 19. Further, by providing a speed difference between the two high-temperature gases 19, the position in the left-right direction of the furnace in which the swirling flow portion 20 is formed can be changed. Further, by changing the speeds of the two hot gases 19 in the same manner, the speed of the swirling flow can be changed.
[0049]
FIG. 4C is a cross-sectional view taken along the line BB ′ of FIG. 3, in which the high-temperature gas 19 blown out from the nozzles 14 provided on the furnace walls 17 on both sides in a downward direction is mixed with the rising unburned gas 21. This shows a state in which a stagnation region 15 is formed by collision. In the stagnation region 15, as a result of stable combustion, a stable diffusion flame is formed. As a result, unlike the prior art, even under low air ratio combustion conditions, the combustion instability in the combustion start region is not amplified, soot and the like are suppressed, and uniform and stable combustion can be expected.
In order to exert a stirring action, it is also effective to blow high-temperature gas into the furnace from the nozzle 14 as a swirling flow.
[0050]
The above embodiment is effective in reducing trace harmful substances such as CO and dioxin. Although FIG. 3 shows a furnace having the intermediate ceiling 13, it goes without saying that the present invention can be applied to a furnace having no such barrier. Further, the blowing of the hot gas may be performed from one side surface of the furnace. Further, the air may be blown from the ceiling instead of from the side of the furnace.
[0051]
In these embodiments, it is appropriate to use a mixed gas of circulating exhaust gas and air as the high-temperature gas ejected from the nozzle 14. Recirculated exhaust gas is a part of the exhaust gas discharged from the waste incinerator is returned to the main combustion chamber to recover its sensible heat, reburn unburned components, and make effective use of residual oxygen in the exhaust gas. Or something.
[0052]
When the exhaust gas is used as a high-temperature gas or as a part of the high-temperature gas, since the emissivity of carbon dioxide and water vapor contained therein is high, the heat of the high-temperature gas is effectively transferred to the unburned gas by heat radiation. be able to.
[0053]
If the circulating exhaust gas satisfies the limitations of the present invention, it may be blown into the furnace as it is, but the temperature of the circulating exhaust gas that is usually used is low, and the oxygen concentration is lower than 10%. For this reason, high-temperature air is produced by a high-temperature air production device or a hot blast stove, and the high-temperature air is mixed with the circulating exhaust gas. When the temperature is lower than 200 ° C., the relationship between the oxygen concentration and the temperature becomes The gas is blown into the furnace as a hot gas to be filled.
[0054]
In the above embodiment, an example has been described in which high-temperature gas is blown so as to form a stagnation region and a swirl region in the furnace. This is preferable in terms of combustion stability, but in the present invention, since the purpose is to form a stable combustion region above the combustion start region, it is not always necessary to form a stagnation region and a swirl region. There is no need to inject hot gas.
[0055]
FIG. 5 shows an outline of an exhaust gas circulation system in a waste incinerator which is an example of an embodiment of the present invention. As shown in detail in FIG. 3, the exhaust gas from the main combustion chamber 1 is guided to a waste heat boiler 11, where the exhaust gas is subjected to secondary combustion in a secondary combustion chamber 12 which is a part thereof. Is performed in the exhaust gas treatment equipment 22, and is emitted to the atmosphere from the chimney 23.
[0056]
In this embodiment, the exhaust gas is sucked by a blower 24 from the rear of the exhaust gas treatment equipment and guided to a gas mixing device 25. High-temperature combustion gas such as burner combustion gas is introduced into the gas mixing device 25 via a high-temperature combustion gas control valve 26, and dilution air is introduced via a dilution air control valve 27.
[0057]
The gas mixing device 25 mixes exhaust gas, high-temperature combustion gas, and dilution air to generate high-temperature gas. This high-temperature gas is blown into the main combustion chamber 1. The oxygen concentration in the high-temperature gas is adjusted by the oxygen concentration adjusting device 29. The oxygen concentration adjusting device 29 adjusts the opening degree of the dilution air adjusting valve 27 so that the oxygen concentration in the high-temperature gas becomes a predetermined concentration. The temperature of the high-temperature gas is adjusted by the temperature adjusting device 28. The temperature control device 28 adjusts the opening of the high-temperature combustion gas control valve 26 so that the temperature of the high-temperature gas falls within the range shown by the expression (1) or (2).
[0058]
As described above, in this embodiment, since the function of adjusting the oxygen concentration and the temperature in the high-temperature gas blown into the main combustion chamber is provided, the oxygen concentration and the gas in the high-temperature gas blown into the main combustion chamber are provided. Can be kept in an appropriate range. When it is desired to adjust the flow rate and flow velocity of the high-temperature gas to be blown, an operation such as adjusting the rotation speed of the blower 24 may be performed.
[0059]
FIG. 6 shows a modification of the exhaust gas circulation system shown in FIG. This example is different from the example shown in FIG. 5 in that the place where the exhaust gas is taken out is the outlet of the waste heat boiler 11, and the function as a whole is the same. Therefore, only the parts different from FIG. 5 will be described. . In the example shown in FIG. 5, since the exhaust gas is taken out from the rear of the exhaust gas treatment equipment 22, dust in the exhaust gas is removed and the exhaust gas is clean. However, the temperature has dropped.
[0060]
In the example shown in FIG. 6, since the exhaust gas is taken out from the outlet of the waste heat boiler 11, high temperature exhaust gas can be used. However, since this exhaust gas contains dust and has the above-mentioned adverse effects, a dust removing device 30 is provided in a pipe leading to the blower 24, and the exhaust gas that has been cleaned by removing dust is sent to the blower 24. I have.
In this case, since the temperature of the exhaust gas is high, the high-temperature combustion gas production device and the high-temperature combustion gas control valve 26 can be omitted.
[0061]
In the examples shown in FIGS. 5 and 6, an example is shown in which high-temperature combustion gas such as a burner combustion gas and dilution air are mixed into the circulating exhaust gas. Instead of the high-temperature combustion gas, it can be led to a gas combustion device. In this case, instead of introducing and adjusting the dilution air into the gas mixing device, the amount of air introduced into the high-temperature air producing device may be adjusted to adjust the oxygen concentration of the high-temperature gas.
[0062]
【The invention's effect】
As described above, according to the present invention, in a method of operating a waste incinerator in which a high-temperature gas is blown into a combustion chamber, particularly in a low air ratio combustion operation method, waste that can efficiently suppress the generation of CO and dioxin is provided. It is possible to provide a method of operating a material incinerator.
[Brief description of the drawings]
FIG. 1 is a diagram showing a relationship between a temperature of a high-temperature gas blown into a furnace and an oxygen concentration.
FIG. 2 is a diagram showing a relationship between a temperature of a high-temperature gas blown into a furnace and an oxygen concentration.
FIG. 3 is a diagram showing an example of a waste incinerator to which an embodiment of the present invention is applied.
FIG. 4 is a view showing a partial cross section of FIG. 3;
FIG. 5 is a diagram showing an outline of an exhaust gas circulation system in a waste incinerator which is an example of an embodiment of the present invention.
FIG. 6 is a diagram showing an outline of an exhaust gas circulation system in a waste incinerator which is an example of an embodiment of the present invention.
FIG. 7 is a schematic diagram showing an example of a conventional waste incinerator.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Main combustion chamber, 2 ... Hopper, 3 ... Waste, 4 ... Dry stoker, 5 ... Burning stoker, 6 ... Post-burning stoker, 7 ... Main ash chute, 8 ... Wind box, 9 ... Main flue, 10 ... Secondary flue, 11: Waste heat boiler, 12: Secondary combustion chamber, 13: Intermediate ceiling, 14: Nozzle, 15: Stagnation area, 17: Furnace wall, 18: Furnace ceiling, 19: Hot gas, 20: Swirling flow Part (swirl area), 21 ... unburned gas, 22 ... exhaust gas treatment equipment, 23 ... chimney, 24 ... blower, 25 ... gas mixing device, 26 ... hot combustion gas control valve, 27 ... dilution air control valve, 28 ... temperature Adjustment device, 29 ... Oxygen concentration adjustment device

Claims (2)

In the combustion chamber of a waste incinerator, the temperature T [° C.] is less than 200 and the concentration of oxygen contained therein [vol. %] A method for operating a waste incinerator, wherein high-temperature gas having a relationship with C in a range represented by the following formula is blown.
T ≧ exp (7.78-0.18C) (1) The combustion chamber of the waste incinerator contains at least one of carbon dioxide and water vapor, has a temperature T [° C.] of less than 200, and contains the concentration of oxygen contained therein [vol. %] A method for operating a waste incinerator, wherein high-temperature gas having a relationship with C in a range represented by the following formula is blown.
T ≧ exp (8.05-0.23C) (2)

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