JPH10122538A - Control method of waste gas in refuse incineration plant - Google Patents

Abstract

PROBLEM TO BE SOLVED: To protect a dust collector and perform dust removal with high efficiency and removal of dioxin or the like without executing a volume control of combustion air of an incinerator which is difficult to be carried out and without affecting the prevention of the generation of white smoke. SOLUTION: This temperature control method heat-exchanges waste gas produced after water injection cooling with an indoor air at a first heat exchanger 4 an feeds into an incinerator as combustion air and heat-exchanges with a white smoke preventive indoor air with a second heat exchanger 5 of its supply system 13 and mixes the heated white smoke generation preventive indoor air with the waste gas which is dust-removed with a dust collector 6 and then exhausts the gas from an exhaust stack 11. In this case, the temperature of the waste gas in front of the dust collector 6 is detected. When the detected temperature exceeds a specified value, the amount of combustion air to the second heat exchanger is divided and reduced, thereby lowering the temperature of the combustion air to the incinerator 1 while the divided heated air is partially fed into the waste gas which has passed the duct collector 6 directly, thereby controlling the temperature of waste gas which flows into the dust collector 6 so that it may become a specified value.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for controlling the temperature of waste gas in a refuse incineration plant, and more particularly to a method for controlling the temperature of waste gas in a refuse incineration plant for incinerating a large amount of general waste such as municipal waste. Control method.

[0002]

2. Description of the Related Art Various types of refuse incineration plants for incinerating large amounts of general waste have been proposed.
The present invention cools the combustion waste gas from the incinerator by water injection,
The cooled waste gas and indoor air are heat-exchanged by a first heat exchanger to lower the temperature, and then exhausted to the atmosphere through a bag filter type dust collector, and the heated indoor air is burned to an incinerator. And heat exchange with the indoor air for preventing white smoke generation by the second heat exchanger in the supply system, and the heated indoor air for preventing white smoke generation is mixed with the waste gas removed by the dust collector. The target is the garbage incineration plant. The following is a supplementary explanation of the basic concept of this type of garbage incineration plant.

[0003] It goes without saying that it is a prerequisite for this kind of refuse incineration plant to efficiently perform refuse combustion, but it is sufficient to simply increase the combustion temperature of the incinerator. Not something. General wastes contain various substances, and even if incineration of combustibles can be performed almost satisfactorily, unless waste gas is completely burned (gasification), not only waste gas, but also dioxin etc. If non-flammable substances are partially mixed (although they are generally classified and removed in advance), the amount of dust will further increase. Therefore, this waste gas must be removed by a dust collector, generally a bag filter type dust collector. In other words, one of the restrictions imposed on the combustion of the garbage incineration plant is the presence of the dust collector (bag filter).

[0004] That is, various materials such as Teflon blend are widely used as filter cloths for bag filter type dust collectors. However, in addition to the performance limitations of the filter cloths, it is necessary to efficiently adsorb and remove harmful gases such as dioxin. So that the inlet temperature to the dust collector is generally between 200 ° C and 230 ° C.
It is regulated as follows. Therefore, it is necessary to suppress the inflow temperature of the waste gas from the incinerator into the dust collector below this temperature, and for that purpose, the combustion waste gas described above is cooled by water injection,
A method is adopted in which the waste gas after cooling and room air are heat-exchanged by a first heat exchanger to lower the temperature and then sent.

[0005] This cooling system has enabled the dust collector to function effectively and to perform sufficient dust removal. However, when the inlet temperature of the dust collector is relatively low, approximately 200 ° C to 230 ° C or less. In the meantime, the temperature becomes even lower by the time it exits the exhaust, and the generation of white smoke in the waste gas from the exhaust will be observed. White smoke contains water vapor particles of water jet used for cooling as described above and water and the like contained in garbage are contained in waste gas, which emerges from the exhaustion and comes into contact with low-temperature outside air. However, this white smoke itself is not harmful, but it appears to non-specialized general public to be an emission of harmful substances, which is a social problem.

As one method for preventing the generation of white smoke, a method of mixing heated air with waste gas that has passed through a dust collector as described above has been adopted. Therefore, as one method of heating the air mixed with the waste gas, FIG.
As shown in (1), the use of the calorific value of the waste gas of the incinerator is performed. That is, the high temperature (8
50 to 950 ° C.), the water is injected into the cooling chamber 3 to cool the waste gas to an appropriate temperature (200 to 400 ° C.), and the waste gas is led to the first heat exchanger 4 for combustion in the incinerator 1. After heating the working air, it is led to the white heat prevention air preheater, which is the second heat exchanger 5, and the second heat exchanger 5 is heated by passing indoor air (outside air or air inside the building of this plant). Then, by mixing the heated air with the waste gas that has passed through the dust collector 6, the temperature of the waste gas at the exhaust outlet 11 is increased, thereby suppressing the generation of white smoke.

[0007]

When operating such a garbage incineration plant, the nature (type) of the garbage to be incinerated
The combustion temperature fluctuates, and as a result,
When the inlet temperature of the dust collector 6 is a predetermined temperature (200 ° C. to 230
(° C or lower). These situations are
For example, using the cooling step by water injection described above, the temperature of the waste gas can be directly reduced by controlling and increasing the amount of water injection, but in this case, the water vapor particles in the waste gas Since the absolute amount increases, and even if the inlet temperature of the dust collector 6 can be controlled, the above-mentioned generation of white smoke is promoted, which is not a preferable solution.

In order to control the temperature of the waste gas, it is conceivable to control the combustion of the incinerator 1 as another method. One of the methods is to control the heating of the indoor air by the first heat exchanger. Then, there is a method of lowering the temperature of the combustion air to the incinerator 1. According to this method, if the supply amount of the indoor air to the first heat exchanger 4 is increased by controlling the supply blower of the indoor air (electric motor and / or damper control), the indoor air to the incinerator 1 is naturally increased. However, in this case, the absolute amount of room air to be supplied increases (air volume increases, that is, excessive supply of oxygen), and the heating temperature decreases and the absolute amount increases. Depending on the ratio, there may be a case where the combustion temperature of the incinerator 1 is rather increased, and it becomes very difficult to control the air flow rate for the heat exchange, and there is a problem that it is not practical as a waste gas temperature control. .

Further, in this case, the temperature of the combustion air to the incinerator 1 that has passed through the first heat exchanger 4 decreases, so that the air is provided between the first heat exchanger 4 and the incinerator 1. Since the temperature of the heat exchange of the second heat exchanger 5, which is the air preheater for preventing white smoke, decreases, it becomes difficult to raise the temperature of the white smoke preventing air to the exhaust port 11 to a predetermined high temperature. Yes, there is another problem that hinders the prevention of white smoke.
In FIG. 2, other members or means cited are:
The same reference numerals as those of members or means of the embodiment of the present invention shown in FIG. 1 which will be described later are cited, and the description is omitted here by referring to this.

The present invention does not perform such a difficult control as controlling the water injection for cooling the waste gas or controlling the air volume of the combustion air in the incinerator, and without affecting the prevention of the generation of white smoke. The temperature of the waste gas can be easily controlled based on the inlet temperature of the dust collector, and the proper temperature of the dust collector can be secured to protect the dust collector and to provide efficient dust removal and dioxin removal functions. It is another object of the present invention to secure an appropriate dust collector inlet temperature and balance the combustion efficiency of the incinerator in a high state.

[0011]

According to the present invention, there is provided a method for controlling the temperature of waste gas in a refuse incineration plant according to the present invention. The waste gas after cooling and the indoor air are passed through the first heat exchanger 4.
After the heat is exchanged to lower the temperature, the air is exhausted to the atmosphere via a bag filter type dust collector 6, and the heated room air is sent to the incinerator 1 as combustion air and the second heat The heat is exchanged with the indoor air for preventing white smoke generation by the exchanger 5, and the heated indoor air for preventing white smoke generation is mixed with the waste gas removed by the dust collector 6 and then exhausted from the exhaust port 11. A method for controlling the temperature of waste gas in a garbage incineration plant, wherein the temperature of waste gas is detected before the dust collector 6, and when the detected temperature exceeds a predetermined value, the temperature to the second heat exchanger 5 is controlled. The amount of the combustion air is divided and reduced to lower the temperature of the combustion air to the incinerator 1, and a part of the divided heated air is directly sent to the waste gas passing through the dust collector 6, whereby The collection Temperature of the waste gas flowing into the machine 6 is controlled to be a predetermined value, it was taken means of.

In the present invention, when the detected temperature of the waste gas in front of the dust collector 6 is lower than a predetermined value, the amount of combustion air to the second heat exchanger 5 is increased, and the amount of combustion air to the incinerator 1 is increased. It is preferred that the temperature of the combustion air is increased to control the temperature of the waste gas flowing into the dust collector 6 to a predetermined value.

In the present invention, a system 13 for supplying combustion air from the first heat exchanger 4 to the second heat exchanger 5 is provided.
A branch 16 which leads to a white smoke generation indoor air supply system 14 extending from the second heat exchanger 5 to the dust collector 6, a control valve 17 is interposed in the branch 16, and the control valve is connected to the branch 16. 17 is preferably controlled based on the result of detecting the temperature of the waste gas before the dust collector 6.

[0014]

BEST MODE FOR CARRYING OUT THE INVENTION The indoor air referred to in the present invention refers to outside air or purified air in a building of an incineration plant, which is distinguished from the odor of a garbage pit. The bag filter type dust collector has a known structure, and a known bag filter (filter cloth) may be used. The first heat exchanger refers to heat exchange between waste gas and room air, and the first heat exchanger refers to heat exchange between the heated room air and separately introduced room air (for preventing white smoke). Although there is a difference, a special structure is not required, and the structure may be a known structure. Further, the temperature of the waste gas to be controlled (detected) is set by the dioxin adsorption / removal function, the performance of the dust collector to be used, and the like.
The temperature is C to 230 ° C., but the numerical value is not particularly limited.

According to the present invention, by detecting the temperature of the waste gas in front of the dust collector, the inlet temperature of the dust collector is reliably detected, and when the detected temperature exceeds a predetermined value, that is, in the incinerator, dust is removed. The combustion situation changes due to the nature etc.,
When the amount of heat increases and the temperature of the waste gas rises, the amount of combustion air to the second heat exchanger is divided and reduced to lower the temperature of combustion air to the incinerator. as a result,
The heat exchange with the indoor air for preventing the generation of white smoke, which sends a certain amount of air, lowers the temperature of the combustion air to the incinerator, reducing the amount of heat supplied to the incinerator and reducing the amount of air By doing so, combustion can be suppressed, and the temperature of the waste gas can be controlled to decrease.

Further, the part of the divided heated air is
By branching as high-temperature air that has not passed through the second heat exchanger and being directly sent to the waste gas that has passed through the dust collector, the temperature of the indoor air for preventing the generation of white smoke to be supplied to the exhaust port increases, and the white smoke is generated. The prevention action is rather improved. In this way, the waste gas temperature is detected just before the dust collector, and based on this, the control of water injection that goes against the prevention of white smoke generation, or the quantitative control of combustion air that is difficult to reliably control the combustion of the incinerator. Instead, the inlet temperature of the dust collector can be reliably controlled to a predetermined value only by dividing the combustion air after passing through the first heat exchanger and using the divided air as indoor air for preventing the generation of white smoke.
In addition, as described above, it is not necessary to control the water injection or the quantitative control of the combustion air in the present invention. However, these may be performed in parallel within a range that suppresses the above-described adverse effects. In addition, the present invention is not impaired by the combined use thereof.

If the combustion state changes due to the nature of dust and the like and the temperature of the waste gas drops, the temperature of the waste gas detected before the dust collector falls below a predetermined value. The amount of combustion air to the second heat exchanger is increased to increase the temperature of the combustion air to the incinerator, so that the temperature of the waste gas flowing into the dust collector is controlled to a predetermined value. Thereby, the thermal efficiency of the incinerator can be improved and rapid incineration can be maintained.

The first heat exchanger supplies a combustion air supply system to the second heat exchanger, and the second heat exchanger supplies a room air supply system for preventing white smoke from the dust collector. In the case where a branching passage is provided, a control valve is interposed in the branching passage, and the control valve is controlled based on a temperature detection result of the waste gas in front of the dust collector, the temperature control is performed by the branching passage and the control valve. It can be carried out only by the simple structural attachment, and can be carried out at low cost where the simplicity of the control method is considered.

[0019]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A preferred embodiment of a method for controlling the temperature of waste gas in a refuse incineration plant according to the present invention will be described below in detail with reference to the drawings. FIG. 1 is a flow sheet schematically showing the flow of waste gas and air and the control system of the refuse incineration plant of the present invention. 1 indicates a refuse incinerator, and 2 indicates the furnace body.
The combustion waste gas from the incinerator 1 is led to the cooling chamber 3 and cooled to about 300 to 400 ° C. by water injection,
It is led to the first heat exchanger 4 via a.

The first heat exchanger 4 is provided for preliminarily heating the combustion air sent into the incinerator 1 by making effective use of the calorific value of the waste gas from refuse incineration. 8
Is a blower, which performs heat exchange by sending the combustion air to the first heat exchanger 4. The blower 8 is used to suck clean indoor air of a plant building from a place where the combustion air is also used as white smoke prevention air as described later and is directly exhausted from an exhaustion. I have.

The waste gas after cooling and the room air are heat-exchanged by the first heat exchanger 4 to lower the temperature, and then exhausted to the atmosphere through the exhaust port 11 through the bag filter type dust collector 6. That is, the waste gas from the incinerator 1 is exhausted from the discharge projection 11 by the negative pressure of the induction blower 10 of the dust collector 6. The room air heated by the first heat exchanger 4 is sent to the incinerator 1 as combustion air.
The heat is exchanged with the indoor air for preventing the generation of white smoke.

The second heat exchanger 5 is similarly supplied with indoor air by a blower 9 as indoor air for preventing the generation of white smoke, and after being heated, passes through a supply system 14 to a dust collector 10.
Is connected to a duct 15 from the exhaust gas to the exhaust port 11 and mixed with the dust-removed waste gas to raise the temperature of the waste gas, thereby preventing the generation of white smoke.

The waste gas that has passed through the first heat exchanger 4 is guided to the dust collector 6 via a duct 4b. Before the dust collector 6, a temperature detector 7 having a known configuration is provided. It is configured to detect the temperature of the waste gas at the entrance of the dust collector 6. The detected temperature is the control temperature, but is set to 200 ° C. in this case. Needless to say, this temperature may be appropriately changed and set depending on the performance of the bag filter, the performance of the dioxin removing means, and the like. Then, the output of the temperature detector 7 is input to the controller 12.

On the other hand, a supply system 13 between the first heat exchanger 4 and the second heat exchanger 5 has a branch connecting the supply system 13 and the supply system 14 for white smoke generation preventing indoor air. A passage 16 is provided, and a control valve (or damper) 17 for controlling the flow rate (including fully open and fully closed) is provided in the branch passage 16.
Is interposed. The control valve 17 is controlled to open and close by the controller 12. The controller 12 may be a normal servo motor.

Therefore, when the detected temperature exceeds a predetermined value, the amount of combustion air to the second heat exchanger 5 is divided and reduced by opening the control valve 17 of the branch passage 16, and the fixed-volume blower 9 controls the combustion in the incinerator 1 by reducing the temperature of the combustion air to the incinerator 1 by the heat exchange with the white smoke generation preventing air, whereby the temperature of the waste gas flowing into the dust collector 6 Is controlled so as to be a predetermined value, and the divided part of the heated air is directly sent to the waste gas passed through the dust collector 6 to enhance the effect of preventing the generation of white smoke.

When the detected temperature of the waste gas in front of the dust collector 6 falls below a predetermined value, the control valve 17 is throttled or closed, and the amount of combustion air to the second heat exchanger 5 is reduced. By increasing the temperature, the temperature of the combustion air to the incinerator is increased, thereby controlling the combustion in the incinerator 1 to increase the temperature to an appropriate temperature, thereby performing efficient incineration.

In the figure, reference numeral 18 denotes a blower for sucking the odor of the garbage pit and burning and decomposing it by using the incinerator 1, which is connected to the incinerator 1 and the path of the waste gas by a duct. In the drawings, symbols and flows that are unnecessary for the description of the present invention will not be described in detail.

[0028]

According to the method for controlling the temperature of waste gas in the refuse incineration plant of the present invention, even if the combustion temperature (calorific value) increases due to the nature of the refuse, the inlet temperature is detected just before the dust collector. Then, based on this, the temperature of the combustion air to the incinerator heated and exchanged by the first heat exchanger is divided and branched, and a part is used as white smoke generation prevention air. The temperature can be reduced to the required value by the filter, and the combustion of the incinerator can be suppressed without the adverse effect of the conventional temperature control by water injection and quantitative control of the combustion air, thereby protecting the dust collector. It is possible to always exhibit excellent dust removal function and dioxin removal function. In addition, while the conventional control method such as increasing the water injection promotes the generation of white smoke, the present invention directly discharges some of the branched high-temperature combustion air without passing through the second heat exchanger. It also has the advantage of increasing the effect of preventing the generation of white smoke.

[Brief description of the drawings]

FIG. 1 is a flow sheet of a method for controlling a waste gas temperature in a refuse incineration plant according to the present invention.

FIG. 2 is a flow sheet in a garbage incineration plant showing the prior art.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Incinerator 4 1st heat exchanger 5 2nd heat exchanger 6 Dust collector 11 Discharge 13 Supply system 14 Supply system 16 Branch path 17 Control valve

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁶ Identification code FI F23N 5/02 345 F23J 15/00 K J

Claims (3)

[Claims] The waste gas from the incinerator 1 is cooled by water injection, and the cooled waste gas and indoor air are heat-exchanged by a first heat exchanger 4 to lower the temperature. The heated indoor air is sent to the incinerator 1 as combustion air, and heat is exchanged with the indoor air for preventing white smoke generation by the second heat exchanger 5 in the supply system 13 thereof. A method for controlling the temperature of a waste gas in a refuse incineration plant in which the heated indoor air for preventing white smoke generation is mixed with the waste gas removed by the dust collector 6 and then exhausted from the exhaust port 11. When the temperature of the waste gas is detected before the dust collector 6, and when the detected temperature exceeds a predetermined value, the amount of combustion air to the second heat exchanger 5 is divided and reduced to reduce the incinerator 1 temperature.
In addition, the temperature of the combustion air is reduced, and a part of the divided heated air is directly sent to the waste gas that has passed through the dust collector 6, so that the temperature of the waste gas flowing into the dust collector 6 becomes a predetermined value. A method for controlling the temperature of waste gas in a garbage incineration plant. 2. When the detected temperature of waste gas before the dust collector 6 is lower than a predetermined value, the amount of combustion air to the second heat exchanger 5 is increased to increase the combustion air to the incinerator 1. 2. The method for controlling the temperature of waste gas in a refuse incineration plant according to claim 1, wherein the temperature of the waste gas is controlled so that the temperature of the waste gas flowing into the dust collector 6 becomes a predetermined value. 3. A system for supplying combustion air from the first heat exchanger 4 to the second heat exchanger 5 is provided in the second heat exchanger 5.
A branch 16 is provided to the indoor air supply system 14 for preventing white smoke from reaching the dust collector 6 and a control valve 17 is interposed in the branch 16, and the control valve 17 is disposed in front of the dust collector 6. 3. The method for controlling the temperature of waste gas in a refuse incineration plant according to claim 1, wherein the control is performed based on a result of detecting the temperature of the gas.