JPH11125414A - Method for controling combustion of combustion chamber of waste melting furnace - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a combustion chamber combustion control method for a waste melting furnace capable of supplying a proper amount of air without retardation for rapid combustion of char, and of dealing with the rapid combustion of char irrespective of active or inactive state. SOLUTION: A method of controlling combustion in a combustion chamber is adapted such that it includes a brightness detection sensor provided in a combustion chamber 1, where combustible gas involving combustible dust (char) produced in a waste melting furnace is combusted with combustion air in the combustion chamber, for detecting brightness in the combustion chamber, and a waste gas oxygen concentration adjusting meter 4 for detecting oxygen concentration in waste gas from the combustion chamber 1, a secondary air flow rate adjusting meter 7, and an air flow rate adjusting valve 11. In the method, a change rate of an output of the brightness detection sensor 5 is calculated with a change rate calculator 6, and when the foregoing change rate exceeds a specified value, rapid combustion of the char is judged, and hereby an air flow rate blowing into the combustion chamber 1 is increased.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to combustible gas and combustible dust (hereinafter referred to as "char") generated when treating waste such as general waste and industrial waste in a waste melting furnace. The present invention relates to a combustion control method for a combustion chamber for burning.

[0002]

2. Description of the Related Art Conventionally, combustible gas containing char generated in a waste melting furnace is collected by a dust remover, supplied to a combustion chamber together with the combustible gas, and burned by combustion air. .

FIG. 3 is a control system diagram of a conventional combustible gas combustion.

An exhaust gas oxygen sensor 3 is disposed at an exhaust gas outlet 2 of the combustion chamber 1, and a detection signal of the oxygen concentration of the oxygen sensor 3 is sent to an exhaust gas oxygen concentration controller 4, which outputs a secondary air flow rate. A signal is sent to the controller 7, and the secondary air flow controller 7 measures the flow rate with the secondary air flow meter 8 while opening the secondary air flow control valve 11 so that the oxygen concentration at the exhaust gas outlet 2 becomes constant. Adjust

Usually, the combustible gas components and chars discharged from the waste melting furnace are not constant and change every moment.
The occurrence of is suppressed.

As a method of controlling the combustion of a fluidized bed, Japanese Patent Publication No. 6-70481 discloses a method of installing a brightness detection sensor and an exhaust gas oximeter in a fluidized bed, and changing the combustion state in the furnace depending on the brightness. It is described that when the combustion state is active, the amount of flowing air is reduced for combustion control, and when the combustion is inactive, the amount of flowing air is increased.

[0007]

However, in the conventional combustion in the combustion chamber, if there is a large amount of excess air, dioxin is likely to be generated due to a decrease in the temperature of the combustion exhaust gas. Note that the dioxin generation suppression guideline specifies that the temperature is 850 ° C. for 2 seconds or more in the combustion chamber.

[0008] The increase in the amount of exhaust gas due to excess air is as follows.
It is uneconomical to increase the capacity of equipment such as an induction ventilator and an exhaust gas dust collector at the latter stage of the combustion chamber.

Further, the amount of generated char may increase rapidly due to the furnace condition of the waste melting furnace, and the abrupt combustion of the char in the combustion chamber may prevent the exhaust gas oxygen concentration from keeping the specified value.
O is generated, but correction by the exhaust gas oxygen sensor and the exhaust gas oxygen concentration controller cannot be made in time because measurement is delayed or exhaust gas oxygen concentration is measured after combustion.

Further, in the above-described method for controlling the combustion of a fluidized bed, since the amount of secondary combustion air is controlled by an exhaust gas oxygen concentration controller, it is not possible to cope with rapid combustion of char, and unburned CO is generated. is there.

According to the present invention, it is possible to supply an appropriate amount of air without delay with respect to rapid combustion of char, and to cope with rapid combustion of char regardless of whether the combustion state of the combustion chamber is active or inactive. The present invention provides a method for controlling combustion in a combustion chamber of a waste melting furnace.

[0012]

SUMMARY OF THE INVENTION The present invention provides a combustion chamber in which a combustible gas containing combustible dust generated in a waste melting furnace is burned by combustion air in the combustion chamber. A combustion chamber provided with a sensor for detecting the oxygen concentration in the exhaust gas from the combustion chamber and adjusting the flow rate of the air blown into the combustion chamber, a secondary air flow meter and an air flow control valve. In the combustion control method, the change rate of the output of the brightness detection sensor is calculated by a change rate calculator, and when the change rate exceeds a specified value, rapid combustion of the char is determined, and the air flow rate blown into the combustion chamber is determined. Is increased.

When the rate of change of the output of the brightness detection sensor exceeds a specified value, the air necessary for the initial combustion is filled with the excess air of the secondary combustion air and increased until the air becomes insufficient. In order to catch up with the air amount and to compensate for the delay in the correction by the exhaust gas oxygen concentration controller, the increase in the combustion air amount is maintained for a time corresponding to the delay time of the exhaust gas oxygen concentration controller.

[0014]

FIG. 1 is a control system diagram of the combustion of combustible gas according to the present invention.

An exhaust gas oxygen sensor 3 for detecting the oxygen concentration in the exhaust gas is disposed at an exhaust gas outlet 2 of the combustion chamber 1, and a detection signal of the oxygen concentration of the exhaust gas oxygen sensor 3 is sent to an exhaust gas oxygen concentration controller 4.

The combustion chamber is provided with a brightness detection sensor 5 composed of a photo sensor for measuring the condition in the furnace. A signal from the brightness detection sensor 5 is sent to a change rate calculator 6.

The secondary air flow controller 7 receives a flow rate measurement signal from the secondary air flow meter 8 and inputs the signal of the exhaust gas oxygen concentration controller 4 and the signal of the change rate calculator to the adder 9. The signal from the adder 9 is input to the secondary air flow controller 7.

The signal of the secondary air flow controller 7 is input to the adder 10 together with the signal of the change rate calculator 6,
The signal of 0 is sent to the secondary air flow control valve 11 to adjust the opening of the secondary air flow control valve 11.

Next, the control method of the present invention will be described.

FIG. 2 is a control flow chart of the combustion of combustible gas according to the present invention.

If the change rate does not exceed the specified value as a result of calculation by the change rate calculator 6 from the output of the brightness detection sensor 5, the secondary air flow rate control valve is set to the normal secondary air flow rate SV. The normal opening MV is set. The specified value of the change rate is 6
Set to about%.

When the rate of change exceeds the specified value, it is determined that the char is burning rapidly, and the adder 9 adds the correction value ΔSV to the normal secondary air flow rate SV so that the secondary air flow rate becomes SV + ΔSV. The flow control valve from the normal opening MV to MV + ΔM
V to increase the amount of combustion air.

When the brightness in the combustion chamber changes, combustion has already occurred, and the air required for initial combustion is 2
The excess air amount of the next combustion air is applied so that the air amount increased in the above determination catches up until this air becomes insufficient. To compensate for the delay of the correction by the exhaust gas oxygen concentration controller, the time corresponding to the delay time of the exhaust gas oxygen concentration controller,
Maintain the increase in combustion air volume. After elapse of a certain time, for example, when t1 = 40 seconds and t2 = 10 seconds elapse, the secondary air flow rate follows the correction by the exhaust gas oxygen concentration controller.

[0024]

The secondary air flow rate is corrected using the change in brightness as a feedforward element for the secondary air flow rate, so that it has good follow-up performance with respect to rapid combustion. In addition, to capture changes in brightness and use the rate of change,
Can control combustion regardless of inactivity.

[Brief description of the drawings]

FIG. 1 is a control system diagram of combustion of combustible gas according to the present invention.

FIG. 2 is a control flowchart of the combustion of combustible gas according to the present invention.

FIG. 3 is a control system diagram of a conventional combustible gas combustion.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Combustion chamber 2 Exhaust gas outlet 3 Exhaust gas oxygen sensor 4 Exhaust gas oxygen concentration controller 5 Brightness detection sensor 6 Change rate calculator 7 Secondary air flow controller 8 Secondary air flow meter 9, 10 Adder 11 Secondary air flow control valve

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁶ Identification code FI F23G 5/50 ZAB F23G 5/50 ZABH

Claims (2)

[Claims] 1. A combustion chamber for burning a combustible gas containing combustible dust generated in a waste melting furnace with combustion air in a combustion chamber is provided with a brightness detection sensor for detecting the brightness of the combustion chamber. A brightness detection sensor in a combustion control method for a combustion chamber provided with an exhaust gas oxygen concentration controller, an air flow controller and an air flow control valve for detecting the oxygen concentration in the exhaust gas from the exhaust gas and adjusting the air flow rate blown into the combustion chamber. Calculating the rate of change of the output of the waste with a rate-of-change calculator, and when the rate of change exceeds a specified value, judges that the char is rapidly burning and increases the flow rate of air blown into the combustion chamber. A combustion chamber combustion control method for a melting furnace. 2. When the rate of change of the output of the brightness detection sensor exceeds a specified value, the air required for the initial combustion is filled with the excess air of the secondary combustion air, and increases until the air becomes insufficient. 2. The method according to claim 1, wherein an increase in the amount of combustion air is maintained for a time corresponding to the delay time of the exhaust gas oxygen concentration controller in order to make the exhausted air amount catch up and compensate for a delay in correction by the exhaust gas oxygen concentration controller. A method for controlling combustion in a combustion chamber of a waste melting furnace as described in the above.