JPH1163438A - Method for feeding oxygen to melting furnace - Google Patents

Abstract

PROBLEM TO BE SOLVED: To burn the toxic substance completely by calculating the oxygen concentration of a melting part based on the oxygen concentration of a cooling part and the oxygen supplying quantity to the melting part and the cooling part and controlling the oxygen supplying quantity to the melting part and the cooling part as that the oxygen concentration of the melting part may have an objective valve. SOLUTION: An oxygen concentration meter 18 is arranged to a cooling part 2, the oxygen concentration of a cooling part 2 is measured and the signals are output to the oxygen concentration controlling meter 19. The oxygen concentration signals output by an oxygen concentration control meter 19, the oxygen supplying quantity signals output from an air flow quantity control meter 13 to a melting part 1 and the oxygen supplying quantity signals from the air flow quantity control meter 17 to a cooling part 2 are input to a computing unit 20. The oxygen concentration of the cooling part 2 and the oxygen concentration of a melting part 1 are calculated by the computing unit 20 from the oxygen supplying quantity to the melting part 1 and the cooling part 2 and the oxygen supplying quantities to the melting part 1 and the cooling part 2 are controlled. Therefore, the toxic substance can be perfectly burned.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for supplying oxygen to a melting furnace used for melting waste and incinerated ash.

[0002]

2. Description of the Related Art A melting furnace as shown in FIG. 2, for example, is used for melting waste. The melting furnace includes a melting section 1 and a cooling section 2 for exhaust gas from the melting section, and wastes such as wastes and incinerated ash are continuously supplied to the melting section 1 from an inlet 3. The melting part 1 is provided with a burner 4 and an air supply nozzle 5, which melts the supplied melt at a high temperature of about 1300 ° C., and the melt is taken out as a molten slag from a discharge port 6 at the lower end of the furnace. It is.

Since the exhaust gas from the melting section 1 has a high temperature of about 1200 to 1300 ° C., if the exhaust gas is directly discharged to an exhaust gas processing apparatus 7 at a subsequent stage, there is a possibility that the equipment may be damaged. Therefore, in general, cooling air and cooling water are injected from a cooling air supply nozzle 8 and a cooling water supply nozzle 9 provided in the cooling unit 2 to cool the exhaust gas to 900 ° C. or less. The cooling air also has a role to completely burn and detoxify benzene, carbon monoxide, dioxin and the like contained in the exhaust gas of the melting part 1. In order to completely burn the harmful substances in this way, it is necessary to control the oxygen concentration in the melting part 1 and the oxygen concentration in the cooling part 2 to be optimum values during the operation.

By the way, in many cases, combustible gas such as pyrolysis gas generated from waste, which is the material to be melted, is supplied together with the material to be melted to the actual waste melting furnace. Since the composition and properties of the combustible gas vary greatly depending on the type of waste, it cannot be predicted in many cases. Moreover, as described above, since the melting portion 1 has a high temperature of about 1200 to 1300 ° C., an oxygen concentration meter cannot be installed to detect the oxygen concentration. As a result, conventionally, the oxygen concentration of the melting part 1 greatly fluctuates due to the change of the flammable gas or the material to be melted, and even if the oxygen concentration of only the cooling part 2 is controlled,
Benzene, carbon monoxide contained in the exhaust gas of the melting part 1,
In some cases, dioxin and the like could not be completely burned.

[0005] This problem can be solved by supplying an excess amount of air to the melting portion 1 which is sufficient to absorb fluctuations in the composition and properties of the combustible gas. But actually,
It is desirable that the hot melt 1 for melting the waste is as compact as possible, and supplying an excessive amount of air to the melt 1 causes a significant energy loss, so this method is not practical.

[0006] For the above-mentioned reasons, in a melting furnace for a material to be melted accompanied by a flammable gas such as a pyrolysis gas, whose composition tends to fluctuate, the fluctuation of the oxygen concentration in the melting part cannot be effectively controlled, and However, there is a problem that carbon monoxide, dioxin and the like cannot be completely burned.

[0007]

SUMMARY OF THE INVENTION The present invention solves the above-mentioned conventional problems and solves the problem when a combustible gas having a composition fluctuation such as a pyrolysis gas generated from waste is melted together with a material to be melted. The object of the present invention is to provide a method for supplying oxygen to a melting furnace in which the fluctuation of the oxygen concentration in the melting part is accurately controlled and the harmful substances can be completely burned.

[0008]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the present invention is directed to a melting furnace having a melting part of a material to be melted accompanied by a combustible gas and a cooling part of the exhaust gas. In the oxygen supply method, the oxygen concentration in the cooling section is measured, and the oxygen concentration in the melting section is calculated from the oxygen concentration and the amount of oxygen supplied to the melting section and the cooling section. It is characterized in that the amount of oxygen supplied to the melting section and the cooling section is controlled so as to be a target value.

According to the present invention, the oxygen concentration in the melting part is calculated from the oxygen concentration in the cooling part, which can be measured because of the low temperature, and the oxygen supply amounts to the melting part and the cooling part, which can also be measured,
Since the oxygen concentration in the fusion zone is grasped, the oxygen concentration in the fusion zone can be controlled to the optimum range even when the composition of the combustible gas fluctuates greatly. Therefore, according to the present invention, harmful substances can be completely burned in the furnace, and environmental pollution can be prevented.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described below. Although the term "air ratio m" appears in the following description, since the air ratio m and the oxygen concentration can be uniquely converted by the equation of m = 21 / (21-oxygen concentration), air The ratio m and the oxygen concentration represent the same physical quantity on different scales. FIG. 1 is a control system diagram showing a method for supplying oxygen to a melting furnace according to the present invention. Since the configuration of the melting furnace itself is the same as that of the conventional furnace shown in FIG. 2, corresponding parts are denoted by the same reference numerals. And the description is omitted.

Reference numeral 10 denotes a blower for sending air to an air supply nozzle 5 of the melting section 1.
1 and the flow meter 12 are connected. Reference numeral 13 denotes an air flow controller, which controls an air supply amount (oxygen supply amount) to the melting portion 1. Similarly, reference numeral 14 denotes a blower for sending air to the cooling air supply nozzle 8 of the cooling unit 2, and a flow control valve 15 and a flow meter 16 are connected before and after the blower. Reference numeral 17 denotes an air flow controller, which controls an air supply amount (oxygen supply amount) to the cooling unit 2.

The cooling unit 2 is provided with an oxygen concentration meter 18, which measures the oxygen concentration of the cooling unit 2 and outputs a signal to the oxygen concentration controller 19 as in the conventional case. As described above, since the melting portion 1 has a high temperature of about 1200 to 1300 ° C. and has a large amount of dust, an oxygen concentration meter cannot be installed.
Therefore, in the present invention, the oxygen concentration of the melting part 1 is calculated from the oxygen concentration of the cooling part 2 and the above-described oxygen supply amounts to the melting part 1 and the cooling part 2. Therefore, the oxygen concentration signal from the oxygen concentration controller 19, the oxygen supply amount signal from the air flow controller 13 to the melting unit 1, and the oxygen supply amount signal from the air flow controller 17 to the cooling unit 2 are , And 20 are input to the arithmetic unit 20. The calculation of the oxygen concentration of the molten portion in the calculator 20 is performed as follows.

The current supply amounts of oxygen to the melting part 1 and the cooling part 2 measured by the flow meter 12 and the flow meter 16 are denoted by w ₁ and w ₂ , respectively, and are measured by the oxygen concentration meter 18 in the cooling part 2. The current air ratio of the cooling unit 2 calculated from the oxygen concentration is m. At this time, oxygen of w ₁ + w ₂ is supplied to the entire furnace, and in this state, the air ratio of the cooling unit 2 that hits the outlet of the furnace is m. At this time, only oxygen of w ₁ is supplied to the melted portion 1. Therefore, the oxygen supply amount is w
A is an air ratio m _X fusion zone 1 _{1, (w 1 + w 2} ): m
= W _1: it can be calculated from the relationship of m _X.

Since the optimum air ratio (oxygen concentration) between the melting part 1 and the cooling part 2 is known as, for example, 1.2 and 1.5, the calculated air ratio m _X of the melting part 1 is intended.
The computing unit 20 is operated by the air flow controller 13 so as to approach 1.2.
To control the amount of oxygen supplied from the air supply nozzle 5 to the melting portion 1. In the case where the optimum air ratio is as described above, it is sufficient to supply 1.2 / 1.5 of the oxygen supply amount to the entire furnace to the melting unit 1 and supply 0.3 / 1.5 to the cooling unit 2. The flow signal B is also supplied to the flow controller 17.
To control the amount of oxygen supplied from the cooling air supply nozzle 8 to the cooling unit 2.

By performing such control, even when the composition of the flammable gas entrained in the material to be melted fluctuates greatly, the oxygen concentration in the melted portion 1 can be controlled to an optimum range.
Therefore, according to the present invention, the harmful substances can be completely burned in the furnace without supplying excessive oxygen to the melting portion 1, and the pollution of the environment can be prevented.

Incidentally, reference numeral 21 in FIG. 1 denotes a thermometer of the melting portion 1, and the burner 4 is controlled by a temperature controller 22.
Reference numeral 23 denotes a thermometer of the cooling unit 2, and the temperature controller 24 controls the amount of cooling water supplied from the cooling water supply nozzle 9.

[0017]

As described above, according to the present invention, the oxygen concentration in the melting portion is calculated from the measurable oxygen concentration in the cooling portion and the measurable oxygen supply amounts to the melting portion and the cooling portion.
Since the oxygen supply amount to the melting part and the cooling part is controlled so that the calculated oxygen concentration of the melting part becomes the target value, the composition of the flammable gas entrained in the melt is unknown. In addition, the oxygen concentration in the molten zone can be controlled to the optimal range,
Hazardous substances can be completely burned in a furnace to prevent environmental pollution. In addition, according to the present invention, since an excessive amount of oxygen is not supplied to the melting portion, there is an advantage that energy loss can be avoided.

[Brief description of the drawings]

FIG. 1 is a control system diagram showing an embodiment of the present invention.

FIG. 2 is a sectional view showing a conventional example.

[Explanation of symbols]

1 melting section, 2 cooling section, 3 inlet, 4 burner, 5
Air supply nozzle, 6 outlet, 7 exhaust gas treatment device, 8 cooling air supply nozzle, 9 cooling water supply nozzle, 10 blower, 11 flow control valve, 12 flow meter,
13 air flow controller, 14 blower, 15 flow control valve, 16 flow meter, 17 air flow controller, 18 oxygen concentration meter, 19 oxygen concentration controller, 20 arithmetic unit, 21
Thermometer, 22 Temperature controller, 23 Thermometer, 24 Temperature controller

Claims (1)

[Claims] 1. A method for supplying oxygen to a melting furnace having a melting part of a material to be melted accompanied by a combustible gas and a cooling part of the exhaust gas, wherein the oxygen concentration in the cooling part is measured, Calculate the oxygen concentration of the melting part from the concentration and the oxygen supply amount to the melting part and the cooling part, and control the oxygen supply amount to the melting part and the cooling part so that the calculated oxygen concentration of the melting part becomes the target value. A method for supplying oxygen to a melting furnace.