JPH10318517A - Method of controlling combustion of fluidized bed incinerator and combustion controlling device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a method of controlling combustion of a fluidized bed incinerator and a combustion controlling device that are simple and does not cause variation of the nature of exhaust gas in spite of the variation of the quantity of a fuel such as fed waste. SOLUTION: A fluidized bed incinerator is structured storing fluidizing sand 5 inside a fluidized bed incinerator main body 1, enabling the supply of fluidizing air for fluidizing the sand 5, enabling the supply of secondary air together with the waste inside the fluidized bed incinerator main body 1 and combusting the waste inside the fluidized bed incinerator main body 1. In this case, three or more thermometers 13 to 15 are arranged to the inside of the fluidized bed incinerator main body 1 each of them with different height, the temperature distribution inside the fluidized bed incinerator main body 1 is obtained from the measured values by the thermometer 13 to 15, the quantity of the waste is increased or decreased, and the quantity of the secondary air and the quantity of the fluidizing air are decreased or increased according to the temperature distribution inside the fluidized bed incinerator main body 1 and the central position of combustion is set to the position of the thermometer positioned at the center of the vertical height among the thermometers 13 to 15.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a combustion control method and a combustion control device for a fluidized bed incinerator, and more particularly to a method for measuring a temperature distribution in an incinerator main body and keeping a combustion center at an appropriate position. The present invention relates to a combustion control method and a combustion control device that maintain a combustion state in which the characteristics of exhaust gas change little even when the amount of fuel, for example, the amount of waste input changes.

[0002]

2. Description of the Related Art Fluid bed incinerators have excellent combustion characteristics and are used as incinerators for municipal solid waste and industrial waste. However, continuous quantitative supply of municipal solid waste and industrial waste is difficult due to its nature, and when it is put into a fluidized bed incinerator, it burns in a short period of time. This leads to the problem of fluctuations in the exhaust gas quality and the characteristics of the combustion exhaust gas. As the properties of combustion exhaust gas, carbon monoxide CO, which is considered to have a high correlation with dioxin, has been attracting attention from the viewpoint of environmental problems.

[0003] CO generated by burning refuse is due to incomplete combustion, and is caused by low temperature conditions such that the reaction of further oxidizing CO to CO ₂ does not proceed. Therefore,
The amount of CO tends to decrease with increasing temperature.

[0004] In view of the above, in order to reduce CO, the inside of the incinerator has been controlled to a certain temperature range, for example, Japanese Patent Application Laid-Open No. Hei 4-203802.

[0005] In this method, the combustion chamber space into which the secondary air in the fluidized bed furnace is blown is divided into a large number of virtual segments each composed of a small section, and the space for each of the small sections is specified as a secondary air supply means and a downstream stream. A gas and / or thermometer for gas, for example, oxygen is installed, and the supply amount of the secondary air and the necessity for the secondary air so that the measured value of the gas and / or thermometer becomes a predetermined value for each of these virtual segments. Control the amount of fuel accordingly, eliminating uneven distribution of unburned gas in the combustion gas space,
The complete combustion of the fuel is intended.

[0006]

According to the above-mentioned publication, the temperature and the oxygen concentration of each virtual segment can be controlled independently, so that the optimum combustion for reducing the CO concentration and the nitrogen oxides can be achieved. A space for temperature and nitrogen concentration can be formed.

[0007] However, contrary to the above-mentioned effect, this publication requires installation of a gas concentration meter and / or a thermometer for each virtual segment, and thus has a problem in that the entire configuration is complicated.

The present invention has been made in order to eliminate the above-mentioned problems, and has a simple structure, but does not cause fluctuations in the properties of exhaust gas even when the amount of fuel, for example, the amount of waste, fluctuates. An object of the present invention is to provide a combustion control method and a combustion control device for a floor incinerator.

[0009]

In order to achieve the above object, an invention according to claim 1 is characterized in that a fluidized medium is accommodated in a fluidized bed incinerator main body, and fluidized air for flowing the fluidized medium is supplied. A fluidized bed incinerator configured to be able to supply and configured to be able to supply secondary air together with fuel inside the incinerator main body, and to burn the fuel inside the incinerator main body. The detectors of at least three thermometers are arranged so that the height positions are different from each other, a temperature distribution inside the incinerator main body is obtained based on a detection value of the detector of each thermometer, and the temperature distribution is determined based on the temperature distribution. The amount of fuel and the amount of the secondary air and the amount of the fluidized air are controlled, and among the detection units of the respective thermometers, the detection value of the detection unit of the thermometer located substantially at the center of the vertical height is adjusted. The best flow A combustion control method of the incinerator.

In order to achieve the above object, an invention according to claim 2 is configured such that a fluidized medium is housed inside a fluidized bed incinerator main body, and fluidized air for flowing the fluidized medium can be supplied, And in the fluidized bed incinerator configured to be able to supply secondary air together with fuel inside the incinerator main body and burn the fuel inside the incinerator main body, the height positions in the vertical direction inside the incinerator main body are different from each other. As described above, the detection units of at least three thermometers are arranged, the temperature distribution inside the incinerator main body is obtained based on the detection value of the detection unit of each thermometer, and the amount of the fuel is increased or Decreasing and decreasing or increasing the amount of the secondary air and the amount of the fluidizing air, and setting the center position of the combustion at a position substantially at the center of the vertical height of the detection unit of each of the thermometers Of the detector A combustion control method for a fluidized bed incinerator which is adapted to match the location.

In order to achieve the above object, the invention according to claim 3 is configured such that a fluidized medium is housed inside a fluidized bed incinerator main body and fluidized air for flowing the fluidized medium can be supplied, And in the fluidized bed incinerator configured to be able to supply secondary air together with fuel inside the incinerator main body and burn the fuel inside the incinerator main body, the height positions in the vertical direction inside the incinerator main body are different from each other. Detectors of at least three thermometers arranged as described above, the temperature distribution inside the incinerator main body is obtained based on the detection values of the detectors of each thermometer, the amount of the fuel and the amount of the fuel based on the temperature distribution The amount of the secondary air and the amount of the fluidized air are controlled so that the detection value of the detection unit of the thermometer located substantially at the center in the vertical direction among the detection units of the respective thermometers is the highest. Control means for performing A combustion control apparatus for a fluidized bed incinerator that.

According to the invention corresponding to any one of the first to third aspects, the fluidized bed incinerator has a simple structure and does not change the exhaust gas properties even if the amount of fuel, for example, the amount of refuse charged, changes. And a combustion control device.

[0013]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a schematic configuration diagram of a fluidized bed incinerator and a combustion control device thereof for describing an embodiment of the present invention. In a fluidized bed incinerator main body (hereinafter, referred to as an incinerator main body) 1, refuse from a dust collector 2 is introduced through a refuse inlet 3 formed in the incinerator main body 1. .

One end of a pipe 4p is connected to the bottom of the incinerator main body 1, and a primary blower 4 is connected to the other end of the pipe 4p. The primary air (fluidized air) from the primary blower 4 causes The high-temperature fluidized sand 5 stored in the bottom of the inside of the main body 1 is fluidized, and the refuse introduced into the incinerator main body 1 comes into contact with the fluidized sand 5 and is thermally decomposed. It has become so.

The gas generated by the thermal decomposition is supplied to a combustion air outlet 7 formed in the center of the incinerator main body 1 by a secondary blower 6 connected to the incinerator main body 1 via a pipe 6p. The fuel is burned in contact with combustion air supplied to the incinerator body 1 via the incinerator.

One end of an exhaust gas pipe 8 is connected to the upper part of the incinerator main body 1, and the other end of the exhaust gas pipe 8 is connected to a heat recovery process section 9 such as a boiler, and an exhaust gas for desalination and deodorization. A chimney 12 is connected via a treatment process unit 10 and an induction blower 11, and the exhaust gas burned inside the incinerator main body 1 passes through the heat recovery process unit 9 and the exhaust gas treatment process unit 10 and is discharged from the chimney 12 by the induction blower 11. It has become so.

Note that an intermediate ceiling 12 is provided inside the incinerator main body 1 above the combustion air outlet 7. The configuration described above is a schematic configuration of a fluidized bed incinerator. In addition, the in-furnace thermometer (hereinafter, simply referred to as a thermometer) 13, 1
4, a combustion control device including a dust supply amount detecting means 16 and a dust supply amount / air amount control means 17 is provided.

The thermometer 13 is disposed at a lower part in the vertical direction inside the incinerator main body 1 and at a position close to the fluidized sand 5, and the thermometer 14 is provided at the center in the vertical direction inside the incinerator main body 1. The thermometer 15 is disposed near the outlet of the exhaust gas on the upper side in the up-down direction inside the incinerator main body 1, and the thermometers 13, 14, and 15 are provided inside the incinerator main body 1. The temperature can be measured, and this measured value is
The data is input to the air amount control means 17.

The dust supply amount / air amount control means 17 obtains the temperature distribution inside the incinerator main body 1 based on the measured values of the respective thermometers 13 to 15, and based on the temperature distribution, the amount of fuel, for example, the amount of waste and the amount of waste. In order to control the amount of the secondary air and the amount of the fluidized air, control signals are output to the dust blower 2, the secondary blower 6, and the primary blower 4, respectively.

Here, the temperature distribution obtained in the dust supply amount / air amount control means 17 is, for example, as shown in FIGS. 2 (a) to 2 (c). The center of combustion is where the combustion is most intense, so the temperature increases and the temperature decreases with distance from the center of combustion. In FIG. 2A,
The temperature of the in-furnace thermometer 13 at the lowest position in FIG. 2D is the highest, so that the center position of combustion is at a position lower than the in-furnace thermometer 13. In the case of the temperature distribution as shown in FIG. 2A, the combustion is completed only with the fluidizing air, and the secondary air cools the inside of the incinerator, so that the remaining CO may not be burned.

In FIG. 2 (b), the highest temperature of the in-furnace thermometer 3 in FIG. 2 (d) is the highest, and therefore, the center position of combustion is at a higher position than the in-furnace thermometer 3. become. In the case of the temperature distribution as shown in FIG. 2B, there is a possibility that incomplete combustion has occurred.

In FIG. 2 (c), the temperature of the in-furnace thermometer 14 located substantially at the center of the incinerator body 1 of FIG.
Thus, the center of combustion is approximately at the center of the incinerator. FIG.
In the case of the temperature distribution as shown in (c), the combustion of the refuse is completed by the secondary air and then cooled by the excess amount of the secondary air, which is an ideal combustion state. Further, in this state, even if the dust is temporarily over-injected and the center position rises for the combustion, there is a margin for the completion of the combustion in the incinerator.

The present invention uses the temperature distribution in the incinerator as an index in order to maintain a combustion state in which the exhaust gas properties fluctuate little, and the amount of refuse charged so that the temperature distribution as shown in FIG. It is characterized in that the amount of primary air and the amount of primary air (fluidized air amount) are controlled.

By maintaining the temperature distribution as shown in FIG. 2 (c), the center of combustion is stabilized almost at the center of the incinerator, and the temperature at which the refuse is completely burned is maintained. It is possible to obtain a sufficient residence time. In addition, since the center of combustion is almost in the center of the incinerator, even if a large amount of refuse is temporarily injected and the center of combustion rises, there is room to complete combustion in the incinerator, and the amount of waste input is low. Even if it fluctuates, it has little effect on exhaust gas properties.

Conventionally, when controlling the inside of an incinerator to a certain temperature range for the purpose of improving the properties of exhaust gas, the control is usually performed by paying attention to the temperature at the furnace outlet. The temperature at the furnace outlet was changed to CO
By maintaining the temperature in the temperature range in which the gas burns, the properties of the exhaust gas are improved. However, in order to maintain this temperature, if a large amount of refuse is injected and the combustion load is increased, the combustion is most violent near the furnace outlet, and if the input of refuse is temporarily excessive, the combustion is completed. Without this, CO is generated, and the intended purpose cannot be achieved. In order to avoid this, the combustion control of the fluidized bed incinerator according to the present invention is performed as follows. (1) The dust fed into the incinerator main body 1 by the dust feeder 2 passes through the dust feed port 3 and the dust feed amount detecting means 16.
Detects the input amount. A reference value for the secondary air amount is obtained based on the detected amount of waste input and the amount of heat generated by the waste. (2) From the measurement results of the thermometers 13, 14, and 15, it is determined which temperature distribution is shown in (a) to (c) of FIG.
In the case of the temperature distribution of FIG. 2A or 2B, the following operation is performed to shift to the temperature distribution of FIG. (3) If it is determined that the temperature distribution is as shown in FIG. 2 (a), the secondary air that should originally act as combustion air is:
The inside of the incinerator main body 1 is cooled.

FIG. 3 shows how the concentration of CO in the exhaust gas fluctuates in such a temperature distribution. Since the temperature is low, the CO concentration is high as a whole, and CO is rapidly generated in response to a change in the amount of dust supplied. In order to shift this state to the appropriate temperature distribution state shown in FIG. 2C, the amount of waste is increased, the secondary air is reduced from the reference value obtained in (1), and incineration with excess air is performed. Cooling in the furnace is avoided, and at the same time, the primary air amount (fluidized air amount) is reduced within a range that does not hinder the discharge of incombustibles, the combustion speed is suppressed, and the center position of combustion is raised. (4) When it is determined that the temperature distribution is as shown in FIG. 2 (b), incomplete combustion may occur when the amount of waste input fluctuates. FIG. 4 shows how the concentration of CO in the exhaust gas fluctuates in such a temperature distribution.

Although the measured value of the thermometer 15 corresponding to the outlet of the incinerator main body 1 is sufficiently high, CO is rapidly generated in response to the change in the amount of dust supplied. This state is shown in FIG.
In order to shift to the appropriate temperature distribution state shown in (1), reduce the amount of waste, increase the amount of fluidized air, stop the combustion speed, and incinerate by increasing the secondary air from the reference value obtained in (1). The combustion in the furnace body 1 promotes the agitation of the waste gas, completes the combustion near the combustion air outlet 7, and lowers the center position of the combustion. (5) As a result of the operation of (3) or (4), when the temperature distribution is stabilized as shown in FIG.
FIG. 5 shows how the density changes. Compared to the case of FIG. 4, the measured value of the in-furnace thermometer 15 at the outlet of the incinerator main body 1 is almost the same, and the fluctuation of the amount of dust is almost the same. Has hardly happened.

According to the embodiment described above, at least three thermometers 1 for measuring the temperature inside the incinerator main body 1 are used.
3, 14 and 15 are arranged at different height positions in the vertical direction, and a temperature distribution inside the incinerator main body 1 is obtained based on the measured values, and the most By simply locating the center of combustion at a high position, even if the amount of dust supply fluctuates, it is possible to maintain a combustion state that allows sufficient combustion to complete in the incinerator, Deterioration can be avoided.

The in-furnace thermometers 13 to 15 are installed at one of the in-furnace thermometers 13 to 15 in the incinerator main body 1.
It is preferable that the other thermometers are installed at a position directly above the fluidized sand 5 and an outlet of the incinerator main body 1 so that the shape of the temperature distribution can be clearly understood as much as possible.

<Modifications> The present invention is not limited to the above-described embodiment, and can be modified as follows, for example. Even if the dust supply amount / air amount control means 17 shown in FIG. 1 is not provided, a means capable of displaying a temperature distribution, and a controller provided in each of the dust blower 2, the primary blower 4, and the secondary blower 6 are provided. If
This can be done manually by the operator as follows. Here, first, the relationship between the amount of air and the temperature will be described with reference to FIGS. When the input amount of refuse increases, it is equivalent to a decrease in both the primary air and the secondary air, and conversely, when the input amount of refuse decreases, the primary air and the secondary air relatively decrease. The following description is general, since it is equivalent to an increase in the amount of secondary air.

FIG. 6 is a diagram showing the relationship between the primary air amount (fluidized air amount) and the lower furnace temperature (value measured by the in-furnace thermometer 13). FIG. 7A shows a case where the primary air amount is small.
It is a figure which shows the relationship between the amount of secondary air and the furnace intermediate | middle part temperature (value measured by the in-furnace thermometer 14). FIG. 7B is a diagram showing the relationship between the amount of secondary air and the temperature in the middle of the furnace (the value measured by the in-furnace thermometer 14) when the amount of primary air is large.

FIG. 8A shows that the primary air amount is small and FIG.
It is a figure which shows the relationship between the amount of secondary air and the furnace outlet temperature (value measured with the furnace internal thermometer 15) in the case of area | region S of (a). FIG. 8B is a diagram showing the relationship between the amount of secondary air and the furnace outlet temperature (the value measured by the in-furnace thermometer 15) in the case of the region T in FIG. . FIG. 8C is a diagram showing the relationship between the amount of secondary air and the temperature at the furnace outlet (the value measured by the in-furnace thermometer 15) when the amount of primary air is large.

The following can be seen from these figures. 1) Relationship between the amount of primary air and the temperature When the amount of primary air is increased, the amount of oxygen supplied to the lower part of the furnace increases, so that the ratio of refuse burning in the lower part of the furnace increases, and the temperature of the lower part of the furnace increases. Conversely, when the amount of primary air is reduced, the amount of oxygen supplied to the lower part of the furnace is reduced, so that the ratio of refuse burning in the lower part of the furnace is reduced, and the temperature of the lower part of the furnace is lowered. Also, the amount of primary air affects the relationship between the amount of secondary air and temperature.

2) Relationship between secondary air amount and temperature (a) When the primary air amount is small and unburned gas remains in the middle part of the furnace, the secondary air acts as combustion air. If the amount of secondary air is increased until then, the combustion in the middle part of the furnace increases, and the temperature in the middle part of the furnace rises (region S in FIG. 7A). In this case, since the combustion continues even in the upper part of the furnace, the furnace outlet temperature also increases.

Further, when the amount of secondary air is increased, the middle part of the furnace starts to be cooled due to excessive air, and the temperature of the middle part of the furnace falls (region T in FIG. 7A). In this case, since no further combustion occurs, the furnace outlet temperature falls.

(B) When the amount of primary air is large and combustion is completed in the lower part of the furnace, the secondary air cools the middle part of the furnace. Descends. The furnace outlet temperature also drops as does the furnace intermediate temperature. In any case, the temperature of the lower part of the furnace is not affected.

Using the relationships 1), 2)-(a) and 2)-(b), the operator can carry out the combustion control according to the present invention as follows. First, when the temperature distribution by the temperature distribution display means is as shown in FIG. 2A, the primary air is large and the combustion is completed in the lower part of the furnace, and the secondary air is acting as cooling air. In this case, an operation is performed so that the primary air is first reduced and the center position of the combustion is moved to the center of the furnace. As a result of reducing the primary air, a portion of the secondary air begins to act as combustion air. Here, the temperature distribution is further observed, and if the furnace outlet temperature is still low, the amount of secondary air also decreases. Conversely, the combustion position is too close to the furnace outlet,
When the temperature distribution becomes as shown in FIG. 2B, an operation is performed so as to shift the center position of combustion to the center of the furnace by increasing the secondary air.

Next, when the temperature distribution by the temperature distribution display means is as shown in FIG. 2 (b), the primary air is small and the secondary air is also small, and the state is close to incomplete combustion. In this case, first, the secondary air is increased to operate so that the combustion is completed in the central part of the furnace. If the temperature distribution cannot be shifted to the state shown in FIG. 2C only by the operation of the secondary air, the primary air is increased to operate to increase the rate of combustion at the lower part of the furnace. When the primary air is increased, part of the secondary air for combustion starts to act as cooling air, so that the secondary air amount also increases or decreases in conjunction with the increase.

[0039]

According to the present invention, a combustion control method and a combustion control apparatus for a fluidized bed incinerator which has a simple structure and does not cause fluctuations in the exhaust gas properties even if the amount of fuel, for example, the amount of waste, fluctuates. Can be provided.

[Brief description of the drawings]

FIG. 1 is a view for explaining a first embodiment of a combustion control device for a fluidized bed incinerator according to the present invention.

FIG. 2 shows an example of the arrangement of a thermometer in the incinerator main body of FIG.
The figure for demonstrating a temperature distribution.

FIG. 3 is a diagram showing a state of a change in a dust supply amount and a change in a concentration of CO in exhaust gas when excessive secondary air is introduced into the incinerator main body of FIG. 1 to cool the incinerator.

FIG. 4 has a sufficient temperature at the outlet of the incinerator main body of FIG. 1,
The figure which shows the mode of the fluctuation | variation of the amount of dust supply and the density | concentration of CO in exhaust gas at the time of high combustion load.

FIG. 5 is a diagram showing a state of a change in dust supply amount and a change in the concentration of CO in exhaust gas when the temperature distribution is appropriately maintained by applying the combustion control method according to the present invention.

FIG. 6 is a view showing a relationship between a primary air amount and a furnace lower temperature for explaining a combustion control method of a fluidized bed incinerator according to the present invention.

FIG. 7 is a diagram showing the relationship between the amount of secondary air and the temperature in the middle of the furnace for explaining the combustion control method of the fluidized bed incinerator of the present invention.

FIG. 8 is a diagram showing the relationship between the amount of secondary air and the furnace outlet temperature for explaining the combustion control method of the fluidized bed incinerator of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Fluidized-bed incinerator main body 2 ... Dust supply device 3 ... Garbage inlet 4 ... Primary blower 5 ... Fluid sand 6 ... Secondary blower 7 ... Combustion air blow-off port 13-15 ... Furnace thermometer 16 ... Dust supply amount Detecting means 17: Dust supply amount / air amount control means

Claims (3)

[Claims] 1. A fluidized medium is housed inside a fluidized bed incinerator main body, fluidized air for flowing the fluidized medium is supplied, and secondary air is supplied together with fuel into the incinerator main body. In a fluidized bed incinerator configured to be capable of burning the fuel inside the incinerator main body, at least three thermometer detectors are arranged inside the incinerator main body such that the height positions in the vertical direction are different from each other. ,
Determine the temperature distribution inside the incinerator main body based on the detection value of the detection unit of each thermometer, control the amount of the fuel and the amount of the secondary air and the amount of the fluidized air based on the temperature distribution, A combustion control method for a fluidized bed incinerator wherein the detection value of the detection unit of the thermometer located substantially at the center in the vertical direction among the detection units of the thermometers is maximized. 2. A fluidized medium is housed inside a fluidized bed incinerator main body, fluidized air for flowing the fluidized medium is supplied, and secondary air is supplied together with fuel into the incinerator main body. In a fluidized bed incinerator configured to be capable of burning the fuel inside the incinerator main body, at least three thermometer detectors are arranged inside the incinerator main body such that the height positions in the vertical direction are different from each other. ,
The temperature distribution inside the incinerator main body is obtained based on the detection value of the detection unit of each thermometer, and the amount of the fuel is increased or decreased based on the temperature distribution, and the amount of the secondary air and the amount of the fluidized air are calculated. Fluidized bed incinerator wherein the center position of the combustion is made to coincide with the position of the detection part of the thermometer which is located substantially at the center in the vertical direction among the detection parts of the respective thermometers. Combustion control method. 3. A fluidized medium is housed inside a fluidized bed incinerator main body, fluidized air for flowing the fluidized medium is supplied, and secondary air is supplied together with fuel into the incinerator main body. In a fluidized bed incinerator configured to be capable of burning the fuel inside the incinerator main body, detection units of at least three thermometers arranged inside the incinerator main body so as to have different vertical height positions. And calculating a temperature distribution inside the incinerator main body based on a detection value of a detection unit of each thermometer, and controlling an amount of the fuel, an amount of the secondary air, and an amount of the fluidized air based on the temperature distribution. And control means for making the detection value of the detection unit of the thermometer located substantially at the center of the height in the vertical direction among the detection units of the respective thermometers the highest. Combustion of the fluidized bed incinerator comprising: Control device.