KR100660757B1 - Method of operating waste incinerator and waste incinerator - Google Patents

Abstract

The present invention is the combustion of a waste gas in a hot gas at a temperature (T [° C.]) of 200 ° C. or higher and satisfying exp (7.78-0.18C) ≦ T ≦ exp (7.45-0.11C). It provides a method of operating a waste incinerator having a process of blowing it indoors. Where C represents the oxygen concentration (vol.%) In the hot gas. According to the method of the present invention, in a waste incinerator, it is possible to sufficiently reduce harmful substances such as NO _X and CO while performing low air specific combustion.

Hot gas, waste incinerator, combustion chamber, oxygen concentration, low air non-combustion

Description

Operation Method of Waste Incinerator and Waste Incinerator {METHOD OF OPERATING WASTE INCINERATOR AND WASTE INCINERATOR}

The present invention relates to an operation method of a waste incinerator for incineration of waste such as general waste, industrial waste, sewage sludge, etc., and a waste incinerator most suitable for carrying out the operation method.

As an incinerator for incineration of wastes such as municipal waste, grate-type or fluid floor waste incinerators are widely used. The representative example is shown in FIG. The waste 32 put into the hopper 31 is sent to the drying stocker 33 through the chute, dried by the air from below and the radiant heat in the furnace, and heated up and ignited. The waste 32 which ignites and combusts is sent to the combustion stocker 34, pyrolyzed and gasified by the combustion air sent from below, and part of it burns. In addition, the unburnt in the waste is completely burned in the afterburner stocker 35. Ash remaining after combustion is taken out from the main ash chute 36.

Combustion is performed in the combustion chamber 37, and the generated combustion gas is divided into the main flue 39 and the minor flue 40 by the presence of the intermediate ceiling 38, and discharged. Exhaust gas passing through the main flue 39 contains almost no flammable gas and contains about 10% or more of oxygen. Exhaust gas passing through the secondary flue 40 contains about 8% of flammable gas. These gases are mixed in the secondary combustion chamber 41, secondary combustion is carried out, and the combustible gas is completely burned. The exhaust gas from the secondary combustion chamber 41 is sent to the waste heat boiler 43, and after being heat exchanged, is discharged to the outside via a temperature reduction tower, a bag filter, and the like.

In such a grate-type or flow-floor waste incinerator, it is difficult to maintain a constant combustion state in the furnace when the waste is incinerated, because the waste is composed of a large number of materials having different properties. It is inevitable that the distribution of the concentration of the combustion gas becomes temporally and spatially nonuniform.

As a method for solving such a problem, Japanese Patent Laid-Open No. 11-211044 discloses a method of blowing hot gas generated by a regenerative burner into a combustion chamber or a secondary combustion chamber of an incinerator.

Further, Japanese Patent Laid-Open No. 11-223323 discloses a method of blowing hot gas generated by a regenerative burner into a furnace at a temperature of 800 ° C or higher.

Both of these techniques aim to reduce flammable gases, harmful substances, etc., which contain a large amount of CO and aromatic hydrocarbons in the exhaust gas generated in an incinerator.

However, in the technique disclosed in Japanese Patent Laid-Open No. 11-211044, since the oxygen concentration in the hot gas is 20% or more, if such hot gas is blown into the incinerator, there is a fear that the local high temperature region is formed by sudden combustion in the incinerator. have. When a local high temperature region is formed, for example, increase the amount of generation of NO _X harmful substances.

In addition, in the technique described in Japanese Patent Application Laid-Open No. 11-223323, in addition to the above problem, since the oxygen-containing gas is blown into the combustion chamber at a temperature of 800 ° C or higher, the thermal decomposition and partial oxidation reactions of the waste are promoted, and in some cases CO May occur.

Thus, it is difficult to fully reduce the toxic materials, including even hwagyeok child incinerator exhaust gas in the NO _X, CO and dioxins upon incineration of waste by incineration of the either of the techniques.

On the other hand, in the conventional waste incinerator, the ratio (air ratio) excluding the actual amount of air as the theoretical air amount necessary for burning the waste is 1. 7 to 2. 0 or so. This is 1.05-1. It is larger than 2. This is because the waste has a lot of incombustibles and is inhomogeneous, and a large amount of air is required to perform combustion. However, as the air ratio increases, the amount of exhaust gas also increases, and a large amount of exhaust gas treatment equipment is required as compared with a normal combustion furnace.

If the air ratio is reduced, the amount of exhaust gas is reduced, and the exhaust gas treatment equipment is compact. As a result, the entire waste incineration plant can be miniaturized, thereby reducing the equipment cost. Moreover, since the chemical | medical agent amount for waste gas processing can also be reduced, operation cost can be reduced. In addition, since the amount of heat lost without heat recovery can be reduced, the heat recovery rate of the waste heat boiler can be improved, and the power generation efficiency of waste power generation can be accompanied.

As described above, although the advantages of low air non-combustion are large, combustion becomes unstable in low air non-combustion. In other words, in the conventional combustion technologies If combustion at a low air ratio, and the unstable combustion, increases the generation of CO or the flame temperature is to locally increase the NO _X is increasing or soot is generated in large quantities, or clinker occurs, or topical Due to the high temperature, the life of the refractory to the furnace is shortened.

The present invention provides a method of operating a waste incinerator for blowing hot gas into a combustion chamber, in particular an operation method capable of sufficiently reducing harmful substances such as NO _X and CO while performing low air non-combustion, and a waste incinerator suitable for implementing the operation method. The purpose is to provide.

This object is achieved by the operation method of the waste incinerators (i) to (iii) below.

Iii) A method of operating a waste incinerator having a step of blowing a hot gas having a temperature (T [° C.]) of 200 ° C. or more and satisfying the following formula (1) into a combustion chamber of a waste incinerator.

exp (7.78-0.18C) ≦ T ≦ exp (7.45-0.11C)... (One)

Ii) blowing a hot gas containing at least one of carbon dioxide and water vapor and oxygen at a temperature (T [° C.]) of 200 ° C or higher and satisfying the following expression (2) into a combustion chamber of a waste incinerator; Operation method of waste incinerator to have.

exp (8.05-0.23C) ≤ T ≤ exp (7.4-0-0.09C)... (2)

Iii) A method for operating a waste incinerator having a step of blowing a hot gas at a temperature (T [° C.]) below 200 ° C and satisfying the following equation (3) into the combustion chamber of the waste incinerator:

exp (7.78-0.18C) ≤ T. (3)

Iii) blowing a hot gas containing at least one of carbon dioxide and water vapor and oxygen at a temperature (T [° C]) below 200 ° C and satisfying the following equation (4) into the combustion chamber of the waste incinerator: Operation method of waste incinerator to have.

exp (8.05-0.23C) ≤ T. (4)

C in formulas (1) to (4) represents the oxygen concentration (vol.%) In the hot gas.

In addition, the operation method of the waste incinerator has an exhaust gas circulation system that circulates and blows the exhaust gas into the furnace, and the exhaust gas circulation facility mixes air with the exhaust gas to adjust the properties of the hot gas, and the combustion starting area in the furnace. It can be realized by a grate or a liquid floor incinerator equipped with a device for adjusting the oxygen concentration and temperature in the hot gas blown from the main combustion zone to the main combustion zone.

1 is a view showing an example of a conventional waste incinerator.

Fig. 2 is a diagram showing the relationship between the temperature and oxygen concentration of hot gas blown into a furnace.

3 is a view showing an example of a waste incinerator of the present invention.

4 shows a partial cross section of FIG. 3;

5 is a view showing an example of the exhaust gas circulation system in the waste incinerator of the present invention.

6 is a view showing another example of the exhaust gas circulation system in the waste incinerator of the present invention.

7 is a view showing a relationship between the temperature and oxygen concentration of hot gas blown into a furnace.

Fig. 8 is a diagram showing a relationship between the temperature and oxygen concentration of hot gas blown into a furnace.

9 is a view showing a relationship between the temperature and the oxygen concentration of the hot gas blown into the furnace.

Embodiment 1

The inventors investigated the relationship between the CO and NO _X generated in the combustion chamber, the oxygen concentration in the hot gas blown into the combustion chamber, and the temperature of the hot gas in the waste incinerator. As a result, as shown in FIG. 2, it was found that CO and NO _X in the exhaust gas can be simultaneously reduced by controlling the oxygen concentration in the hot gas and the temperature of the hot gas to an area surrounded by the A, B and C lines. .

When the temperature of the hot gas at the time of blowing into the furnace is T [° C.] and the oxygen concentration in the hot gas is C [vol.%], The A line is T = exp (7.78-0.18C) and the B line. Is denoted by T = exp (7.45-0.11C) and the C line by T = 200.

A hot gas having an oxygen concentration and a temperature in a region surrounded by A, B and C lines is blown into the combustion chamber to be heated by heat radiation and sensible heat from the hot gas to promote thermal decomposition of the waste. It is possible to form a stable flame stably by forming a stagnation region in which flammable gas and combustion air stay in the waste space. In addition, since the mixing of the combustible gas and the combustion air is promoted, the uniform and stable combustion is promoted, so that the generation of NO _X and CO can be greatly reduced.

In the region below the A line, the amount of oxygen is insufficient and the temperature of the gas to be blown is low, so the combustion of the combustible gas becomes unstable, and as a result, the generation of CO increases.

In the region above the B line, high temperature combustion occurs, resulting in excessively accelerated pyrolysis-gasification reaction of the waste, and an increase in NO _x because of the local combustion of combustible gases.

In the region below the C line, even if gas is blown, gas mixing is not sufficiently performed because the effect of the curling and stirring of the surrounding gas is small. As a result, the local high temperature zone is generated and NO _x is increased.

For example, when the oxygen concentration in the hot gas is 12%, the temperature of the hot gas which simultaneously achieves low NO _X and low CO is in the range of 280 to 500 ° C. When the oxygen concentration in the hot gas is 15%, the temperature of the hot gas which simultaneously achieves low NO _X and low CO is in the range of 200 to 330 ° C.

In the combustion chamber, a space of 400 ° C or higher and in which flammable gas exists is a region in which pyrolysis of waste is promoted or pyrolysis of waste is completed, and flammable gas is generated by pyrolysis of waste and This area exists. For example, in paper waste, pyrolysis starts at about 200 ° C and completes at about 400 ° C. In plastic waste, pyrolysis starts at about 400 ° C and completes decomposition at about 500 ° C. The hot gas does not start pyrolysis of waste, and even if blown into an area where only drying is performed, the effect of promoting low NO _x and low CO of the exhaust gas is small. Therefore, it is preferable that the blowing area of hot gas is 400 degreeC or more, and the space where flammable gas exists.

As described above, it is preferable to blow the hot gas into a region in which a large amount of flammable gas exists. In most waste incinerators such as a grate type and a flowing floor type, a region in which a large amount of flammable gas is present is burned from the combustion starting region. Area. Here, the combustion starting area is a region where flammable gas is generated by pyrolysis or partial oxidation of the waste and combustion of the waste starts. In addition, the main combustion zone is a zone where waste decomposition, partial oxidation and combustion are carried out, flammable gas is generated, and combustion is carried out with a flame, and combustion with a flame is completed (complete combustion point (Burn-). off point)). Therefore, it is preferable to set the hot gas blowing region from the combustion starting region to the main combustion region. In the grate-type incinerator, the combustion starting area is the upper space of the drying grate, and the main combustion area corresponds to the upper space of the combustion grate.                 

In general, primary air refers to the combustion air blown from the wind box under the grate in the case of grate, and from the wind box under the flow floor. In this invention, it is preferable to make the blowing amount of hot gas into 10 to 70% of this primary air amount for the following reasons. If the blowing amount of the hot gas is less than 10% of the primary air amount, the hot gas blowing effect may not be sufficiently exhibited because it does not have the momentum necessary for stirring the furnace gas. In addition, if the blowing amount of the hot gas exceeds 70% of the primary air amount, the effect of low NO _x and low CO of the exhaust gas is saturated, and it does not mean to increase the blowing amount of the hot gas. Increase the exhaust gas treatment equipment.

When the primary air amount used as a reference value of the hot gas blowing amount is less than or equal to the theoretical air amount necessary to completely burn the waste, the hot air blowing amount is preferably 10 to 70% of the theoretical air burning the waste. Do. The theoretical air volume is also determined from the nature of the waste.

Combustible gases from waste usually flow upwards. Therefore, if the blowing direction of the hot gas is upward, the flow rate of the combustible gas and the hot gas has the same velocity component, and the effect of stirring and the effect of retaining the flow of the flammable gas become smaller, so that the hot gas blowing effect is reduced. Reduce. On the contrary, when the blowing direction of the hot gas is horizontal or downward, the rising combustible gas and the hot gas are well stirred, and the flow of the flammable gas can be kept, thereby enhancing the blowing effect of the hot gas.

By blowing hot gas as a swirl flow, the stirring effect can be improved and the blowing effect of hot gas can be heightened more. In this case, the " blowing hot gas as the swirl flow " means that the hot gas flowing out from the blowing inlet is the swirl flow or the flow of the hot gas flowing out from the plurality of blowing holes is a swirl flow. Includes cases.

The operation method of the waste incinerator according to the present invention has an exhaust gas circulating facility for circulating and blowing exhaust gas into the furnace, and the exhaust gas circulating facility mixes air with the exhaust gas to adjust the properties of the hot gas and burn the furnace. It can be easily realized by a grate type or flow floor type waste incinerator equipped with a device for adjusting the oxygen concentration and temperature in the hot gas blown from the starting area to the main combustion area.

In this waste incinerator, if a nozzle for blowing hot gas into the furnace is provided at a position not exceeding 1/2 of the height of the combustion chamber, a stagnant region is formed by the hot gas blown from the nozzle just above the waste layer in the furnace. Therefore, the flame can be fixedly present directly above the waste layer in the furnace. Therefore, the pyrolysis of waste is performed more efficiently, and the burnout of the ceiling is reduced because the high temperature region is far from the ceiling. In addition, "combustion chamber height" is the height of the space where the main combustion is performed, and means the height from the grate or the floor to the location where the roof ceiling or the secondary combustion air is blown.

3 shows an example of the waste incinerator of the present invention.                 

On one side (left side of FIG. 3) of the combustion chamber 1, a hopper 2 for introducing the waste 3 into the combustion chamber 1 is provided. The bottom of the combustion chamber 1 is provided inclined so that the grate (stocker) which burns while moving the waste 3 may descend as it moves away from the hopper 2. This grate has two steps and is divided into three parts. These three gratings are called the dry stocker 4, the combustion stocker 5, and the post combustion stocker 6 from the side closer to the hopper 2. As shown in FIG. The drying stocker 4 mainly carries out drying and ignition of the waste 3. The combustion stocker 5 mainly carries out combustion of the waste 3, which is burned and pyrolyzed at the same time, releasing combustible gas together with the combustion gas. The combustion of the waste 3 in the combustion stocker 5 is substantially completed. On the after-burner stocker 6, the unburnt in the remaining waste 3 is completely burned. The combustion residue after complete combustion is discharged from the main chute 7.

In the lower part of each grate, the wind box 8 which connects the supply pipe for supplying combustion air is installed.

The main flue 9 and the minor flue 10 are provided below and above the combustion chamber 1 on the opposite side to the hopper 2, and the secondary combustion chamber 12 of the waste heat boiler 11, which is part of the gas cooling system, is provided. This connection is provided. In the combustion chamber 1, a barrier (intermediate ceiling) 13 for classifying combustion gas is provided near the outlet of the combustion chamber 1, and the flow of the combustion gas is divided into the main flue 9 and the minor flue 10. It is classified.

The waste 3 is introduced into the combustion chamber 1 from the hopper 2 and the combustion air is supplied to the waste 3 moving through the grate phase through the respective supply pipes and wind boxes 8. Dry and burn again.

The nozzle 14 is provided in the side wall of the combustion chamber 1, The hot gas of the temperature which is 200 degreeC or more from this nozzle 14 and satisfy | fills said Formula (1) is blown into the combustion chamber 1, and is blown. . The nozzle 14 is provided in the upper part of the drying stocker 4 and the upper left side of the combustion stocker 5. When the waste 3 is cooled, evaporation of water first occurs, followed by pyrolysis and partial oxidation. The pyrolysis reaction here takes place at a temperature of about 200 ° C. and is approximately completed at a temperature of about 400 ° C. The nozzle 14 is provided in the part (rear end part) of the drying stocker 4 and the front end of the combustion stocker 5, and hot gas is blown in. Depending on the type of waste 3, the pyrolysis reaction may be completed at a higher temperature. In this case, it is preferable to provide the nozzle 14 also at the rear end side (right side of the drawing) than the position shown in FIG.

As described above, the nozzle 14 is preferably installed at a height position not exceeding half of the height of the combustion chamber.

As described above, the combustion of the combustible gas can be promoted by blowing a hot gas into the space where the temperature is 400 ° C or higher and where the combustible gas exists. Therefore, the nozzle is mounted on the side wall, the ceiling, It may be provided at the entrance of the intermediate ceiling 13 and the secondary combustion chamber 12.

As the blowing amount of the hot gas, considering the exhaust gas treatment or the like is preferable as little as possible. However, when the blowing amount is small, CO is more likely to be generated and complete combustion is not possible. For this reason, as mentioned above, it is preferable to set it as 10-70% of blow-in amount of the primary air blown in from the wind box 8. As shown in FIG. Thereby, generation | occurrence | production of CO can be suppressed to the extent that it does not have a problem. Therefore, it is preferable to add or subtract the blowing amount in the range of 10 to 70% of the primary air amount while monitoring the amount of CO or NO _X emitted. In particular, depending on the type of waste (3), the amount of primary air blown in may be less than the theoretical air amount required to burn the waste (3), in which case a large amount of hot gas is blown into the waste (3). It is desirable to promote the complete combustion of and to prevent the generation of CO. When it is known that the amount of primary air blown in is small, as described above, the amount of hot gas to be blown may be in the range of 10 to 70% of the theoretical air amount required to burn the waste 3. .

When the nozzle 14 is installed in the horizontal or downward direction, it is possible to accelerate the combustion of the combustible gas by retaining the flow of the combustible gas in which the hot gas ejected from the nozzle rises. It is preferable to install the nozzle facing downward in the sense of prompting the retention action. If the angle is too large, the hot gas does not touch the entire width direction, so it is particularly preferable to set it in the range of 10 to 20 ° downward from the horizontal direction. desirable.

In order to show the arrangement | positioning of the nozzle in FIG. 3 to FIG. 4, A-A 'cross section figure (horizontal cross section: FIG. 4A, FIG. 4B) and B-B' cross section figure (vertical cross section: FIG. 4C) of FIG. In FIG. 4, the structure not related to the present invention is omitted.

In FIG. 4A, the hot gas 19 is blown out from the pair of nozzles 14 provided opposite the width direction of the furnace wall 17, and collides with each other in the center of the furnace. Therefore, in the center of the furnace, a stagnant region 15 is formed in which the movement of the furnace gas is slow, and combustion is stably performed.

4B shows another example, in which the directions of the nozzles 14 are such that their central axes are parallel to each other and are spaced apart by a predetermined interval, and the hot gas 19 is spaced apart by a predetermined distance in the center of the furnace. have. For this reason, the turning area 20 is formed in the center part of the furnace.

In this example, the stagnant region 15 or the turning region 20 is formed in plan view at the center of the furnace. Therefore, as described above, the flame is stabilized and the mixing of the gases is promoted.

In FIG. 4A, the size of the stagnant region 15 can be controlled by changing the flow velocity of the hot gas ejected from the two nozzles 14 in the same manner. In addition, by providing a difference in the flow rate of the hot gas ejected from both nozzles 14, the left and right positions of the furnace in the stagnant region 15 can be changed. In addition, by changing the direction of the nozzle 14 in the longitudinal direction of the furnace and in the same direction, the longitudinal position of the furnace of the stagnant region 15 can be changed.

In FIG. 4B, the size of the turning area 20 can be changed by changing the distance between the two nozzles 14. In addition, by providing a speed difference in the two hot gases 19, the widthwise position of the furnace in which the turning area 20 is formed can be changed. In addition, the speed of the swirl flow can be changed by changing the speeds of the two hot gases 19 equally.

In FIG. 4C, a vertical section of the furnace is shown. On the furnace walls 17 on both sides, the hot gas 19 blown from the nozzle 14 installed in the downward direction collides with the rising combustible gas 21 to condense the stagnant region 15. The figure that forms the shape is shown. In the stagnant region 15, as a result of the stable combustion, a stable flame is formed. As a result, unlike in the prior art, even in low air rate combustion, the instability of combustion in the combustion starting region is not amplified, and the generation of soot is suppressed, so that uniform and stable combustion can be expected.

Moreover, in order to exert stirring effect, it is also effective to blow hot gas into the furnace from the nozzle 14 as a swirl flow.

In addition, the combustion speed is preferably at least 10 [m / s] or more because there is an effect of stabilizing combustion by blowing hot gas to sufficiently agitate the gas near the furnace side wall.

The flame in the furnace when no hot gas is blown is volatile. If the hot gas is blown into the furnace as above, the flame in the furnace becomes a transparent flame and the Roman tower (stocker) is observed from the furnace wall. You can do it. This is considered to be because the slow combustion of the combustible gas was performed by blowing hot gas. Therefore, it is also possible to observe the transparency of the flame in the furnace and to use it as a criterion for determining whether or not hot gas is properly blown.

In the above embodiment, it is effective for the reduction of trace harmful substances such as CO, NO _X and dioxins.

In FIG. 3, although the furnace which has the intermediate ceiling 13 is shown, it cannot be overemphasized that this invention is applicable also to the furnace which does not have such an intermediate ceiling. In addition, although hot gas is blown into the combustion chamber 1, hot gas may be blown into the secondary combustion chamber 12. The hot gas may be blown from one side of the furnace. It may be blown from the middle ceiling or the ceiling, not from the side of the furnace.

As the hot gas ejected from the nozzle 14, a mixed gas of circulating exhaust gas and air is suitable. The circulating exhaust gas is a part of the exhaust gas discharged from the waste incinerator, and returns to the combustion chamber to reduce harmful substances and reduce the amount of exhaust gas.

If the circulating exhaust gas satisfies the conditions of the hot gas of the present invention, it may be blown into the furnace as it is, but if it is lower than 200 ° C. and the oxygen concentration is low, the hot air may be heated by a hot air production apparatus or a hot blast furnace. What is necessary is just to mix this with a circulating exhaust gas, and to blow into a furnace as a hot gas satisfying the conditions of this invention.

When the temperature of the exhaust gas from the secondary combustion chamber 12 is sufficiently high and the oxygen concentration is high, it can be mixed with air and blown in by using it instead of the high temperature air without installing a high temperature air production apparatus. In addition, as long as the temperature of the exhaust gas from the secondary combustion chamber 12 is 200 ° C. or more, and the relationship between the oxygen concentration and the temperature satisfies the above formula (1), the exhaust gas may be directly blown into the furnace.

In case of using the exhaust gas from the incinerator as a whole or part of the hot gas, sodium or potassium salts contained in the dust contained in the exhaust gas are attached to the pipe wall of the pipe to cause corrosion or to close the pipe. There is concern. In addition, when the dust is blown into the furnace without removing the dust, there is a possibility that the concentration of the hazardous substances emitted by the harmful substances (for example, dioxin) contained in the dust is rather increased. Therefore, it is desirable to remove dust in the exhaust gas. As a method of vibration damping, well-known methods, such as a filter system and a cyclone system, can be used. The filter method includes a filter cloth and a ceramic filter. When the exhaust gas temperature is high, the ceramic filter has excellent durability and heat resistance. Filter cloths made of metal fibers are also effective depending on the operating temperature. In addition, a vibration damper of a moving bed type can also be used. The place where dust is removed is preferably as close as possible to the ejection opening because the pipe before the vibration is shortened.

It is preferable to take out exhaust gas from the place where the temperature of exhaust gas is high. In the case of incinerators with waste heat boilers, it is effective to remove them from the boiler. In the boiler section, it is possible to extract the hot exhaust gas of 800 ° C. In addition, such high temperature exhaust gas can effectively remove the harmful substances contained therein.

As a high temperature air production apparatus, a heat storage burner, a regulator, the apparatus which mixes air and oxygen with the combustion gas from the combustion burner of a hot stove, etc. can be used. The heat storage burner prepares a pair of heat storage bodies, heats the first heat storage body by the hot exhaust gas from the combustion burner, heats the second heat storage body which is already heated and heats it, and heats it by the hot exhaust gas. It is an apparatus which can be performed by switching heating of a heat storage body, and heating of the air by a heat storage body.                 

In the case of mixing the hot air from the hot air production device and the circulating exhaust gas, it is preferable to mix the air by the ejector device and blow it into the furnace. In other words, when the high-temperature air is led to the ejector apparatus, and the circulating exhaust gas is mixed with the circulating exhaust gas and blown into the furnace, a special moving part such as a fan for sucking the circulating exhaust gas is not required. At the same time, dust troubles are reduced.

Table 1 shows the characteristics (oxygen concentration and temperature) of the hot gas that is blown into the furnace when the burner combustion gas of the hot stove, the dilution air, and the circulating exhaust gas are mixed and the hot gas is blown into the furnace. It shows correspondence between an operation factor and an operation method for improving the properties of the hot gas blown into the furnace when out of the scope of the invention. For example, when the oxygen concentration is lower than the range of the present invention and the temperature is lower than the range of the present invention, the combustion gas of the combustion burner is increased to increase the temperature of the hot gas to be blown, and the exhaust gas circulation amount is reduced and the dilution air amount ( The amount of air mixed with the hot gas) is increased so as to be within the scope of the present invention. When the oxygen concentration is lower than the range of the present invention and the temperature is higher than the range of the present invention, only the amount of dilution air is increased to increase the oxygen concentration.

Table 1

Characteristics of blown gas (compared to the scope of the present invention) Manipulation Factors and Operation Methods Oxygen concentration Temperature Hot air burner combustion Dilution air volume Circulating Exhaust Gas low low increase increase decrease high - increase - high low increase decrease increase high decrease decrease increase

The example in which the hot gas is blown so as to form the stagnant region or the turning region in the furnace has been described. It is preferable to do so in terms of stability of combustion as described in the prior art. In the present invention, since the purpose is to stabilize combustion in the main combustion region from the combustion starting region, the temperature and oxygen concentration of the hot gas are If it is in the range, it is not necessary to blow hot gas to form a stagnant area or a turning area.

5 shows an example of the exhaust gas circulation system in the waste incinerator of the present invention.

As shown in detail in FIG. 5, the exhaust gas from the combustion chamber 1 is led to the waste heat boiler 11, and is secondly burned in the secondary combustion chamber 12, which is a part thereof, and then heat-exchanged in the waste heat boiler 11, It is cleaned in the exhaust gas treatment facility 22 and is released into the atmosphere from the chimney 23.

At this time, part of the exhaust gas is sucked by the blower 24 from the downstream side of the exhaust gas treatment facility and guided to the gas mixing device 25. Hot gas combustion gas such as burner combustion gas is introduced into the gas mixing device 25 through the high temperature combustion gas control valve 26, and dilution air is introduced through the dilution air control valve 27. In the gas mixing device 25, the exhaust gas, the hot combustion gas, and the dilution air are mixed to adjust the hot gas. This hot gas is blown into the combustion chamber 1. The oxygen concentration in this hot gas is controlled by the oxygen concentration control device 29. In the oxygen concentration regulating device 29, the opening degree of the dilution air control valve 27 is adjusted so that the oxygen concentration in the hot gas becomes a predetermined concentration. In addition, the temperature of the hot gas is controlled by the temperature control device (28). In the temperature control apparatus 28, the opening degree of the high temperature combustion gas control valve 26 is adjusted so that the temperature of hot gas may become the range shown by said Formula (1).

As described above, since the oxygen concentration and temperature in the hot gas blown into the combustion chamber are controlled, the oxygen concentration and temperature in the hot gas blown into the combustion chamber can be maintained in an appropriate range. When it is desired to adjust the flow rate and flow rate of the hot gas to be blown, the rotation speed of the blower 24 may be adjusted.

6 shows another example of the exhaust gas circulation system shown in FIG. 5. In this example, only the point where the exhaust gas is taken out is the outlet of the waste heat boiler 11 differs from the example shown in FIG.

In the example of FIG. 5, since the exhaust gas is taken out from the rear of the exhaust gas processing facility 22, the dust in it is removed, and exhaust gas is clean. However, the temperature of exhaust gas is falling.

On the other hand, in the example of FIG. 6, since the exhaust gas is taken out from the outlet of the waste heat boiler 11, the temperature of exhaust gas is high. However, since this exhaust gas contains dust, the exhaust gas is sent to the blower 24 after the dust is removed by the vibration damper 30 provided in the pipe leading to the blower 24.

6, since the temperature of exhaust gas is high, the high temperature combustion gas manufacturing apparatus and the high temperature combustion gas control valve 26 can be omitted.

In the example of FIGS. 5 and 6, the high temperature combustion gas such as burner combustion gas and the dilution air are mixed with the circulating exhaust gas, and the gas combustion device is replaced with the high temperature combustion gas produced by the high temperature air production apparatus as described above. You can also lead to In this case, the oxygen concentration of the hot gas may be adjusted by adjusting the amount of air introduced into the hot air production apparatus instead of adjusting the dilution air into the gas mixing apparatus.

Embodiment 2

The inventors have also found that a method of operating a waste incinerator blowing hot gas into the combustion chamber, in which the hot gas containing at least one of carbon dioxide and water vapor effective to fully reduce the harmful substances such as NO _X and CO. This is because the radiation rate of carbon dioxide and water vapor is higher than that of nitrogen and oxygen, so that the heat radiation from the hot gas containing these gases is efficiently heated and the combustible gas generated from the waste is efficiently heated, so that even if low air non-combustion is performed, This is because combustion is carried out.

As in the case of Embodiment 1, the relationship between the CO and NO _X generated when blowing hot gas into the combustion chamber, the oxygen concentration in the hot gas blown into the combustion chamber, and the temperature of the hot gas was investigated. As shown, when the oxygen concentration in the hot gas and the temperature of the hot gas are controlled in an area surrounded by the A, B, and C lines, that is, the temperature of the hot gas is 200 ° C or higher, and the above equation (2) is satisfied. It became clear that CO and NO _X in exhaust gas can be reduced simultaneously. In Fig. 7, line A is T = exp (8.05-0.23C), line B is T = exp (7.4-0-0.09C) and line C is T = 200.

For example, when the oxygen concentration in the hot gas is 12%, the temperature of the hot gas which simultaneously achieves low NO _X and low CO is in the range of 200 to 550 ° C. When the oxygen concentration in the hot gas is 15%, the temperature of the hot gas which simultaneously achieves low NO _X and low CO is in the range of 200 to 400 ° C.

It is effective to use exhaust gas discharged from a combustion furnace as a high temperature gas containing at least one of carbon dioxide and water vapor.

The blow-in area of the hot gas is 400 ° C. or more, as in the first embodiment, and is a space in which flammable gas exists, and it is preferably from the combustion start area to the main combustion area.

In addition, when a waste incinerator having a waste heat boiler is used so that the hot gas contains a gas derived from the waste heat boiler or from the outlet of the waste heat boiler, the sensible heat in the exhaust gas can be effectively used to increase the thermal efficiency.

In addition, when a waste incinerator having an exhaust gas treatment facility is used to make the hot gas include a gas of 800 ° C. or lower derived from an upstream of the exhaust gas treatment facility, the sensible heat in the exhaust gas can be effectively used as in the case described above. I can raise it.

The operation method of the waste incinerator of the present invention can be realized by the waste incinerator as shown in FIG. 3 described in the first embodiment. In the method of the present invention, at least one of carbon dioxide and water vapor and oxygen is contained from the nozzle 14 provided on the side wall of the combustion chamber 1, and a hot gas having a temperature of 200 ° C. or more and satisfying the above expression (2) is a combustion chamber. The thing described in Embodiment 1 can be applied as it is except blowing in (1).

Embodiment 3

In Embodiment 1 and 2, although the temperature of the hot gas blown into a combustion chamber was 200 degreeC or more, the present inventors discovered that even if it is less than 200 degreeC, there exist conditions which can suppress CO and dioxin generation | occurrence | production.

That is, when the waste contains biomass or sawdust, since the temperature at which pyrolysis starts is generally 100 ° C. or more, pyrolysis occurs even when the temperature is less than 200 ° C., and flammable gas is generated. Therefore, when the temperature and oxygen concentration of the hot gas are optimized, the effect of reducing CO or dioxin can be expected. In this case, the effect of reducing the NO _X compared to the case where the temperature of the hot gas is less than 200 ℃ jakeunde, it is possible to reduce the NO _X by providing a nitrate removal system.

8 shows the relationship between the temperature of the hot gas and the oxygen concentration. The hot gas of temperature and oxygen concentration in the area surrounded by the A, B, and C lines is blown into the combustion chamber, that is, the temperature of the hot gas is 200 ° C. When it is less than and satisfies the above formula (3), it became clear that the thermal decomposition of the waste can be promoted and a stable flame can be stably present on the waste layer. At this time, since mixed combustion of the combustible gas is promoted, uniform and stable combustion is performed, and generation of harmful substances such as CO and dioxins can be reduced. In Fig. 8, line A is T = exp (7.78-0.18C), line B is C = 21 and line C is T = 200.                 

The reason why the oxygen concentration is 21% or less is because an oxygen incubator is necessary to make oxygen larger than 21%, which is not preferable.

Also in the case where the temperature of the hot gas is less than 200 ° C., the inclusion of at least one of carbon dioxide and water vapor in the hot gas as in the case of Embodiment 2 is effective for suppressing the generation of CO and dioxins.

In this case, as shown in FIG. 9, the temperature and oxygen concentration of the hot gas are controlled to a region surrounded by the D line, the E line, and the F line, that is, the temperature of the hot gas is less than 200 ° C., and the above equation (4). ) Needs to be satisfied. In Fig. 9, the D line has T = exp (8.05-0.23C), the E line has C = 21, and the F line has T = 200.

Moreover, also when the temperature of said hot gas is less than 200 degreeC, the thing described in Embodiment 1 can be applied as it is except the conditions of the hot gas blown in.

Claims (16)

A method of operating a waste incinerator, characterized by comprising a step of blowing a hot gas having a temperature (T [° C.]) of 200 ° C or more and satisfying the following formula (1) into a combustion chamber of a waste incinerator. exp (7.78-0.18C) ≦ T ≦ exp (7.45-0.11C)... (One) Where C represents the oxygen concentration (vol.%) In the hot gas. The method of claim 1, And an area in which the hot gas is blown in the combustion chamber is 400 ° C. or higher and a space in which flammable gas exists. The method of claim 1, And a region in which the hot gas is blown in the combustion chamber is from a combustion start region to a main combustion region. The method of claim 1, A method for operating a waste incinerator, characterized in that the blowing of hot gas is 10 to 70% of the primary air volume. The method of claim 1, A method for operating a waste incinerator, wherein the blowing amount of hot gas is 10 to 70% of the theoretical air amount for burning the waste. The method of claim 1, Method for operating a waste incinerator, characterized in that the blowing direction of the hot gas is horizontal or downward direction. The method of claim 1, A method for operating a waste incinerator, characterized by blowing hot gas as a swirl flow. Having a step of blowing at least one of carbon dioxide and water vapor and oxygen, at a temperature of 200 [deg.] C. or higher, and satisfying the following formula (2), into a combustion chamber of a waste incinerator: Operation method of waste incinerator. exp (8.05-0.23C) ≤ T ≤ exp (7.4-0-0.09C)... (2) Where C represents the oxygen concentration (vol.%) In the hot gas. The method of claim 8, And an area in which the hot gas is blown in the combustion chamber is 400 ° C. or higher and a space in which flammable gas exists. The method of claim 8, And a region in which the hot gas is blown in the combustion chamber is from a combustion start region to a main combustion region. The method of claim 8, A method of operating a waste incinerator, characterized in that the hot gas comprises a gas derived from the waste heat boiler or from the outlet of the waste heat boiler using a waste incinerator having a waste heat boiler. The method of claim 8, A method of operating a waste incinerator, characterized in that the hot gas comprises a gas of 800 ° C. or less derived from upstream of the exhaust gas treatment facility using a waste incinerator having an exhaust gas treatment facility. A method of operating a waste incinerator, characterized by having a step of blowing a hot gas at a temperature (T [° C.]) of less than 200 ° C and satisfying the following formula (3) into a combustion chamber of a waste incinerator. exp (7.78-0.18C) ≤ T. (3) Where C represents the oxygen concentration (vol.%) In the hot gas. Having a step of injecting at least one of carbon dioxide and water vapor and oxygen into a combustion chamber of a waste incinerator at a temperature (T [° C.]) of less than 200 ° C and satisfying the following equation (4): Operation method of waste incinerator. exp (8.05-0.23C) ≤ T. (4) Where C represents the oxygen concentration (vol.%) In the hot gas. In a grate-type or flow-floor waste incinerator having an exhaust gas circulation system that circulates and blows exhaust gas into a furnace, The exhaust gas circulation system, Mixing means for adjusting hot gas by mixing at least air with the exhaust gas; Oxygen concentration adjusting means for adjusting the oxygen concentration in the hot gas; Temperature control means for controlling the temperature of the hot gas; And a blowing means for blowing the hot gas into a range of the main combustion region from the combustion starting region in the combustion chamber of the incinerator. The method of claim 15, The blowing means further comprises a nozzle, The nozzle is a waste incinerator, characterized in that installed in a position not more than 1/2 of the height of the combustion chamber.

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