JP2004132648A - Combustion control method and combustion control device for gasification melting furnace - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a combustion control method and combustion control device for gasification melting furnace capable of suppressing the generation of unburnt gas, efficiently performing the melting treatment of char and surely making refuse pollution-free by stabilizing the combustion temperature and melting temperature. <P>SOLUTION: A controller 11 analyzes CO concentration in unburnt gas at the outlet of a gasification furnace 4 by an exhaust gas analyzer 7, calculates the combustion air quantity necessary for combustion of decomposed gas in a melting furnace 15 based on the analytic result, and adjusts combustion air regulating valves 12 and 14 to control the combustion air quantity to be supplied to the melting furnace 1. The controller further measures the outlet temperature of a melting part 32 by a thermometer 16, calculates the deviation of the measured temperature from a set target temperature, and controls the supply quantity of char by a char constant-rate feeder 10 based on the result, whereby the decomposed gas is perfectly burnt, and the temperature of the melting part is kept at a proper value to enable the sure melting of ash. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a combustion control method and a combustion control device for a gasification and melting furnace that combusts combustible gasification containing ash and char, after combustible gasification by pyrolyzing refuse, and melting ash. More particularly, the present invention relates to a combustion control technique capable of maintaining a combustion temperature and an ash melting temperature in an optimum state.
[0002]
[Prior art]
Disposal of refuse from households and businesses has become a social problem, and in particular, measures against dioxins generated during the incineration process of vinyl chloride and the like are serious problems. Furthermore, disposal of ash generated when a large amount of garbage is incinerated is also a major issue. Therefore, conventionally, refuse is thermally decomposed in a gasification furnace to generate a combustible gas containing ash and char, and then the combustible gas containing ash and char is burned at 1300 to 1400 ° C. in a melting furnace. A technique for melting ash, discharging the ash as granulated slag, and releasing combustion exhaust gas into the atmosphere in a harmless state has been developed.
[0003]
Related to this is a proposal described in Patent Document 1, for example. In this proposal, the combustion air flow rate was controlled by the oxygen concentration at the combustion furnace outlet, and the combustion temperature and ash melting temperature were not constant because the analysis did not analyze the amount of combustible gas components in the decomposition gas.
[0004]
[Patent Document 1]
JP 10-169947 A [0005]
[Problems to be solved by the invention]
However, in the above prior art, it is difficult to keep the combustion temperature and the ash melting temperature constant, and the furnace temperature becomes unstable due to various factors. As a result, unburned gas is generated or ash melting is not sufficiently performed. A state that cannot be performed has occurred.
[0006]
An object of the present invention is to stabilize the combustion temperature and the ash melting temperature, suppress the generation of unburned gas from the melting furnace outlet, efficiently perform the ash melting process, and surely detoxify garbage. An object of the present invention is to provide a combustion control method and a combustion control device for a gasification and melting furnace that can be processed.
[0007]
[Means for Solving the Problems]
In order to achieve the above object, the present invention relates to a combustion control method for a gasification and melting furnace, which supplies a quantity of char generated by thermal decomposition of refuse in a gasification furnace into a melting furnace, and supplies flammable gas in a decomposition gas. The amount of gas components is analyzed, the amount of air required for complete combustion of the cracked gas is calculated based on the analysis result, and the amount of air for burning the cracked gas supplied to the melting furnace is controlled. Measuring the temperature downstream of the melting part of the melting furnace, controlling the fixed amount of supply of char to the melting furnace based on the deviation between the measured temperature and the target temperature, and further controlling the flue downstream of the melting furnace. The oxygen concentration in the flowing exhaust gas is measured, and the amount of gas combustion air supplied to the melting furnace is controlled in accordance with the deviation between the measured oxygen concentration and the target oxygen concentration.
[0008]
Further, the present invention according to the combustion control device of the gasification and melting furnace analyzes the amount of combustible gas components in the cracked gas flowing out of the gasification furnace and the char quantitative supply device that supplies the char into the melting furnace. A gas analyzer, a thermometer that measures the temperature downstream of the melting part of the melting furnace, and the amount of air required for complete combustion of the cracked gas is calculated based on the analysis results analyzed by the gas analyzer and supplied to the melting furnace. Control means for controlling the amount of air for the decomposition gas combustion to be performed, and controlling the quantitative supply amount of the char to the melting furnace by the char quantitative supply device based on the deviation between the measured temperature measured by the thermometer and the target temperature. It has.
[0009]
BEST MODE FOR CARRYING OUT THE INVENTION
In the present invention, the char is separated from the cracked gas generated in the gasification furnace by the char separator, and the separated char is supplied to the melting furnace through the hopper and the char quantitative supply device, whereby the supply amount of the char varies. Try to prevent.
[0010]
Then, the concentration of combustible gas in the cracked gas is analyzed, and the amount of combustion air required for burning the cracked gas in the melting furnace is calculated based on the analysis result. The amount of combustion air supplied to the melting furnace is controlled based on the calculation result of the amount of combustion air, and the amount of combustion air required for melting the char is also calculated based on the result, and the combustion supplied to the melting furnace is calculated based on the result. By controlling the amount of air, complete combustion of the decomposition gas, that is, harmlessness of the discharged exhaust gas is achieved.
[0011]
In addition, a thermometer is installed at the outlet of the melting part of the melting furnace, that is, as close as possible downstream of the place where the ash is melted, and at a place that is not easily affected by the surrounding environment such as dust, and the temperature of the thermometer is measured. measure. By measuring the temperature at a location closer to the melting location and controlling the quantitative supply of the char as compared to the target temperature, it is possible to maintain a temperature suitable for melting the ash by burning the char.
[0012]
Furthermore, by analyzing the oxygen concentration of the flue connected downstream of the melting furnace and correcting the amount of combustion air supplied to the secondary combustion chamber of the melting furnace according to the deviation from the set target value, the unburned gas Can be completely combusted so as not to remain.
[0013]
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 is a configuration diagram illustrating an entire configuration of a waste treatment apparatus including a waste melting furnace according to an embodiment of the present invention.
[0014]
As shown in the figure, the waste treatment apparatus includes a dust supply device 1 for supplying a fixed amount of waste, a gasification furnace 4 for gasifying the waste, and a cyclone separator for separating char, which is a combustible solid in the generated decomposition gas. (Char separator) 8, Char quantitative supply device 10 for quantitatively supplying char separated by cyclone separator 8 to melting furnace 15, Melting section 32 for burning decomposed gas and char and melting ash, Exhaust gas discharged from melting section 32 It comprises a secondary combustion chamber 19 for burning unburned components therein, an air preheater 21 for processing exhaust gas discharged from the secondary combustion chamber 19, a cooling tower 24 and a bag filter 25.
[0015]
The refuse is supplied to the gasification furnace 4 by a dust supply device 1 which is a fixed-rate supply device. A diffuser 31 from which air and recirculated gas are blown out is provided below the gasifier 4, and dampers 3 and 5 and flow detectors 2 and 6 for adjusting respective flow rates are provided at the inlet of the diffuser 31. By adjusting the flow rates of the air and the recirculated gas from the air diffuser 31, thermal decomposition of the refuse is performed.
[0016]
At the outlet of the gasification furnace 4, a gas analyzer 7 is provided, and a cyclone separator 8 for separating char from decomposed gas is provided. Below the cyclone separator 8, a char hopper 9 for temporarily storing the separated char and a char quantitative supply device 10 for supplying a constant amount of the char to the melting furnace 15 are provided, and the char in the decomposed gas is separated from the decomposed gas. Thus, a fixed amount can be supplied to the melting furnace 15.
[0017]
The melting furnace 15 has a melting part 32 for swirling and melting the char, and a secondary combustion chamber 19 downstream of the melting part 32 for completely burning the unburned part in the exhaust gas. Maintain the melting temperature. Further, a slag screen 17 for collecting slag is provided between the melting part 32 and the secondary combustion chamber 19, and a thermometer 16 is installed in a gas path between the outlet of the melting part 32 and the slag screen 17. ing. The melting portion 32 is provided with an auxiliary burner 13 that assists in maintaining the temperature when the amount of char is insufficient. Downstream of the secondary combustion chamber 19, various exhaust gas treatment devices, that is, an air preheater 21, a cooling tower 24, a bag filter 25, and the like are provided, and an O ₂ concentration meter 26 and a CO concentration meter 27 are provided in the flue. Have been.
[0018]
Most of the exhaust gas flowing through the flue is discharged from the chimney 30 into the atmosphere, and a part of the exhaust gas is supplied into the gasification furnace 4 from the diffuser 31 via the damper 3 by the gas recirculation fan 29. Further, detection signals from the flow rate detectors 2 and 6, the gas analyzer 7, the thermometer 16, the O ₂ concentration meter 26, and the CO concentration meter 27 are inputted to the controller 11, and the controller 11 determines each char based on the calculation result. The output to the supply device 10, the auxiliary burner 13, and the combustion air control valves 12, 14, 20 is controlled.
[0019]
In the figure, 18 is an air preheater, 22 is a push-in blower, 23 is a secondary push-in blower, and 28 is an induction blower.
[0020]
FIG. 2 is a processing system diagram showing input / output signals of the controller 11 and calculation contents.
The flow rate of the fluidized air detected by the flow detector 6 from the air blower 22, the flow rate of the exhaust gas from the gas recirculation fan 29 detected by the flow detector 2, the flow rate of the recirculated gas, The flammable gas concentration and the theoretical combustion air amount are calculated by inputting the flammable gas concentration detected by the gas analyzer 7 to the controller 11, and the flammable gas combustion air regulating valve 14 is controlled.
[0021]
Further, the correction amount of the secondary air flow rate is calculated by the O ₂ concentration meter 26, the secondary air flow adjustment valve 20 is controlled, and the CO concentration is monitored by the CO concentration meter 27. Further, the temperature of the outlet of the melting section 32 is detected by the thermometer 16, the correction amount of the char supply amount is calculated, and the supply amount of the char fixed amount supply device 10 is controlled.
[0022]
If necessary, the control amount of the auxiliary burner is calculated, and the combustion amount of the auxiliary burner 13 is controlled by the auxiliary burner control panel. The correction value of the char supply amount corrects the current char supply amount to calculate the char theoretical combustion air amount (correction value), and controls the char combustion air adjustment valve 12.
[0023]
Next, a description will be given of combustion control in the gasification and melting step of the waste treatment apparatus having the above-described configuration. The amount of decomposition gas generated when the dust introduced by the dust supply device 1 is gasified in the gasification furnace 4 is approximately equal to the amount of the fluidized air flowing from the diffuser 31 and detected by the flow rate detectors 2 and 6. Equal to the sum of the flow rates of the circulating gas.
[0024]
Further, by analyzing the component amount of the combustible gas in the cracked gas, the flow rate of the combustible gas in the cracked gas can be calculated. In the present embodiment, CO is about 8 to 10% as a combustible gas contained in the cracked gas, and the other cracked gases are also compounds of carbon. Therefore, the concentration of the combustible gas at the outlet of the gasification furnace 4 is determined by a gas analyzer. Analysis is performed in step 7 to theoretically calculate the amount of air required for burning the combustible gas.
[0025]
Since the char contained in the decomposed gas is separated by the cyclone separator 8 and supplied to the melting part 32 separately from the decomposed gas, the decomposed gas incinerated in the secondary combustion chamber 19 according to the combustible gas flow rate calculated by the above calculation. The theoretical amount of combustion air required for combustion of the fuel can be calculated independently. The composition of the char is stable, and the theoretical amount of combustion air can be calculated from the fixed amount of char which is separately determined. The controller 11 controls each of the combustion air control valves 12 and 14 based on the above calculation results to stabilize combustion and maintain the combustion temperature.
[0026]
Furthermore, since it is very difficult to directly and accurately measure the temperature of the melting portion 32 in the melting furnace 15, the outlet temperature of the melting portion 32 close to the melting region of the char is measured by the thermometer 16, and the temperature with respect to the set target temperature is measured. The deviation from the measured temperature is calculated, and the supply amount of char is controlled based on the result. The ash melts at 1250 ° C. or higher, but 1300 to 1350 ° C. is suitable for melting, and this temperature range is the target value. If the amount of char accumulated in the char hopper 9 is sufficient and the melting temperature is 1250 ° C. or more, the supply amount of the char by the char quantitative supply device 10 is increased without depending on the auxiliary burner 13 even if the melting temperature is slightly lowered. As a result, the calorific value increases, and the melting temperature of the char can be maintained. However, if the amount of char is insufficient or the temperature of the melting portion has not reached 1250 ° C., the temperature of the melting portion 32 is controlled by the auxiliary combustion burner 13 to maintain the melting temperature.
[0027]
By carrying out such combustion control of the melting furnace 15, each part of the combustion state is stabilized, but the combustion temperature is also maintained at an appropriate temperature, further, the O ₂ concentration by the O ₂ concentration meter 26 provided in the flue portion And whether or not unburned gas is generated is determined based on the deviation between the set target concentration and the set target concentration (eg, 12%). That is, if the O ₂ concentration is less than 12%, the amount of air is insufficient and incomplete combustion occurs, so that the amount of combustion air is increased. If it exceeds 12%, the amount of combustion air is reduced because the amount of air is excessive. These controls are performed by adjusting the amount of combustion air supplied to the secondary combustion chamber 19 by the opening amount of the air control valve 20, thereby achieving complete combustion of the decomposition gas.
[0028]
Incidentally, the decomposition gas generated in the gasification furnace 4 is _{N 2,} CO _2, CO, H _2, H 2 O, and consists of the compounds of the CH or the like, most of which in _{N 2} with the exception of CO _2, and CO is there. Therefore, if the amount of N ₂ is subtracted from the amount of generated gas, the approximate amounts of CO ₂ and CO are obtained. That is, the same control as the above-described combustion control in the gasification melting step can be performed by analyzing the concentration of N _{2 in} the generated gas.
[0029]
【The invention's effect】
As described above, according to the first aspect of the present invention, the amount of air required for complete combustion of the decomposed gas is calculated based on the result of analyzing the component amount of the combustible gas in the decomposed gas and supplied to the melting furnace. The amount of air for combustion of the cracked gas is controlled, so that the amount of air required for the combustion of the cracked gas burned in the melting furnace is kept optimal, preventing the emission of unburned gas in the exhaust gas. As a result, the exhaust gas can be rendered harmless.
[0030]
According to the second aspect of the present invention, the temperature downstream of the melting part in the melting furnace is measured, and the fixed amount of char supplied to the melting furnace is controlled based on the deviation between the measured temperature and the target temperature. When the temperature of the melting part of the furnace is slightly lowered, the temperature of the melting part can be maintained at an appropriate temperature without using unnecessary fuel.
[0031]
According to the third aspect of the present invention, the oxygen concentration in the exhaust gas flowing through the flue downstream of the melting furnace is measured, and the gas combustion supplied to the melting furnace according to the deviation between the measured oxygen concentration and the target oxygen concentration. Since the amount of air for use is controlled, even if the decomposed gas causes incomplete combustion for some reason, the required amount of air can be immediately supplied, so that complete combustion of the decomposed gas can be achieved.
[Brief description of the drawings]
FIG. 1 is a configuration diagram illustrating an overall configuration of a refuse treatment apparatus according to an embodiment of the present invention.
FIG. 2 is a processing system diagram showing input / output signals and operation contents of a controller according to the embodiment of the present invention.
[Explanation of symbols]
1: dust supply device, 2, 6: flow rate detector, 3, 5: damper, 4: gasifier, 7: gas analyzer, 8: cyclone separator (char separator), 9: char hopper, 10: char quantitative Supply device, 11: controller, 12, 14, 20: combustion air regulating valve, 13: auxiliary burner, 15: melting furnace, 16: thermometer, 17: slag screen, 18: air preheater, 19: secondary combustion chamber , 21: air preheater, 22, 23: forced draft fan, 24: temperature reducing tower 25: bag filter, 26: _{O 2} concentration meter, 27: CO concentration meter, 28: induced draft machine 29: gas recirculation fan, 30: chimney, 31: diffuser pipe, 32: melting part

Claims (4)

A gasification melting furnace that separates a char from a decomposition gas containing ash and char generated by thermally decomposing garbage in a gasification furnace and guides the char and the decomposition gas together into a melting furnace to melt the ash. In the combustion control method,
While quantitatively supplying the char into the melting furnace, analyze the component amount of the combustible gas in the decomposition gas, calculate the amount of air required for complete combustion of the decomposition gas based on the analysis result, A method for controlling combustion of a gasification and melting furnace, wherein an amount of air for combustion of the cracked gas supplied to the melting furnace is controlled. 2. The combustion control method for a gasification and melting furnace according to claim 1, wherein a temperature downstream of a melting portion of the melting furnace is measured, and a fixed amount of char is supplied to the melting furnace based on a deviation between the measured temperature and a target temperature. A combustion control method for a gasification and melting furnace, characterized in that the amount is controlled. The method for controlling combustion of a gasification and melting furnace according to claim 1, wherein an oxygen concentration in an exhaust gas flowing through a flue downstream of the melting furnace is measured, and the oxygen concentration is measured according to a deviation between the measured oxygen concentration and a target oxygen concentration. A combustion control method for a gasification and melting furnace, wherein an amount of gas combustion air supplied to the melting furnace is controlled. A gasifier for thermally decomposing garbage, and a char separator for separating char from a cracked gas containing ash and char generated in the gasifier, and guiding both the char and the cracked gas In the combustion control device of the gasification melting furnace to melt,
A char quantitative supply device for quantitatively supplying the char into the melting furnace, a gas analyzing means for analyzing a component amount of a combustible gas in a cracked gas flowing out of the gasification furnace, and a downstream of a melting part of the melting furnace. A thermometer that measures the temperature of the gas, and calculates the amount of air required for complete combustion of the decomposed gas based on the analysis result analyzed by the gas analysis means, and supplies the air for the decomposed gas combustion supplied to the melting furnace. Control means for controlling the amount of the char, and controlling the quantitative supply of char to the melting furnace by the char quantitative supply device based on a deviation between the measured temperature measured by the thermometer and the target temperature. A combustion control device for a gasification and melting furnace.

Images