JP3893200B2 - Method for preventing closure of slag outlet in combustion melting furnace of waste treatment equipment - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method for preventing closure of a slag discharge port in a combustion melting furnace of a waste treatment apparatus.
[0002]
[Prior art]
Conventional waste such as municipal waste from households and offices, or waste containing so-called combustibles, such as industrial waste such as waste plastic, car shredder dust, waste office equipment, electronic equipment, and chemical products Various types of treatment apparatus have been proposed and implemented, but in recent years, a waste treatment apparatus having a combustion melting furnace has attracted attention due to environmental problems, particularly the problem of dioxin generation.
[0003]
As shown in, for example, Japanese Patent Publication No. 6-56253, EP0340537, etc., the waste treatment apparatus having this combustion melting furnace is composed of pyrolysis gas and mainly non-volatile components. The pyrolysis residue is generated, and the pyrolysis gas, the combustible component separated from the pyrolysis residue, and the combustion air are supplied to the combustion melting furnace and burnt, and the combustion generated by this combustion The molten slag is melted to form molten slag, and this molten slag adheres to the inner wall of the combustion melting furnace and flows down, is discharged from the lower discharge port, is cooled and solidified, and high-temperature combustion gas is 2. Description of the Related Art A combustion melting furnace for a waste treatment apparatus is known that is cooled to form exhaust gas, and a part of the exhaust gas is supplied into the combustion melting furnace to control the temperature.
[0004]
[Problems to be solved by the invention]
By the way, in the combustion melting furnace of the waste treatment apparatus as described above, when performing maintenance, inspection, etc. of this combustion melting furnace, it is necessary to stop the operation. In this case, the molten slag is solidified in the vicinity of the slag discharge port. The slag outlet could be closed. That is, when the operation of the combustion melting furnace is stopped, first, the supply of the combustion melting furnace and the pyrolysis gas is stopped, and then the supply of combustion air is stopped. As a result, the temperature in the combustion melting furnace decreases due to natural cooling, but this temperature decrease is significant in the vicinity of the slag discharge port leading to the outside air. Therefore, the molten slag that adheres to the inner wall of the combustion melting furnace and flows down reaches the vicinity of the slag discharge port and is cooled and solidified. As a result, the slag discharge port is closed.
[0005]
When such a slag discharge port is closed, it is necessary to remove the solidified slag at the time of re-operation. As a result, not only the operation efficiency is lowered but also the combustion melting furnace may be damaged. There was a problem.
[0006]
[Means for Solving the Problems]
The present invention has been made to solve the conventional problems as described above, and heats and decomposes waste to produce pyrolysis gas and pyrolysis residue mainly composed of nonvolatile components. The slag is obtained by supplying the combustible component separated from the pyrolysis gas, the pyrolysis residue, and the combustion air to the combustion melting furnace and burning it, and melting the generated ash in the combustion melting furnace. at least the combustion melting adhere to the furnace inner wall is flow down, in a combustion melting furnace of the combustion melting furnace bottom of the waste was Unishi by Ru cooled and solidified was discharged from the slag discharge port processor, during shutdown of the combustion melting furnace in the furnace bottom of the furnace, at least one of a portion of a part of the exhaust gas or combustion air quenching the furnace bottom by supplying the molten slag to lower the flow so as to solidify on the inner wall surface of the combustion melting furnace It is characterized by that.
[0007]
Then, at least one part of the exhaust gas or part of the combustion air is supplied to the lower part of the combustion melting furnace, and when the operation of the combustion melting furnace is stopped, a part of the exhaust gas or one of the combustion air is supplied. It is preferable to take a method of supplying the part and quenching the lower part in the furnace.
[0008]
Further, it is preferable to provide a temperature detector at the lower part of the furnace and control the supply amount of a part of the exhaust gas or a part of the combustion air to the lower part of the furnace based on a signal from the temperature detector.
[0009]
Furthermore, an internal pressure detector is arranged in the combustion melting furnace, and a suction device arranged on the downstream side of the combustion melting furnace is controlled by a signal of this pressure detector, and the internal pressure of the combustion melting furnace is below a predetermined value, For example, it is controlled to be equal to or lower than atmospheric pressure. According to such a method, when the operation of the combustion melting furnace is stopped, the lower part is rapidly cooled, so the molten slag flowing down along the inner wall surface solidifies and adheres to the inner wall surface and reaches the vicinity of the slag discharge port. There is no. Therefore, closing of the slag discharge port can be prevented.
[0010]
As a quenching means for the lower part of the combustion melting furnace, a part of the exhaust gas used for temperature control in the combustion melting furnace is supplied to the lower part of the furnace, or is usually supplied to the lower part of the combustion melting furnace. By using the secondary and tertiary combustion air as the cooling medium, the lower part in the furnace can be rapidly cooled without providing a special cooling device.
[0011]
The molten slag is usually attached to the inner wall of the combustion melting furnace at about 1,300 ° C. and flows down. According to the knowledge of the present inventor, the molten slag has a large viscosity at about 1,200 ° C. , Solidify at about 100 ° C and stop flowing. Therefore, the rapid cooling of the lower part of the combustion melting furnace should be rapidly lowered to at least about 1,100 ° C. Therefore, the lower temperature in the combustion melting furnace is detected, and the supply amount of a part of exhaust gas or a part of combustion air as a cooling medium is controlled. And when temperature falls to the predetermined value of about 1,100 degreeC, supply of a part of exhaust gas or a part of combustion air will be stopped.
[0012]
On the other hand, the pressure in the furnace rises by supplying a part of the exhaust gas or a part of the combustion air to the lower part of the combustion melting furnace. When the pressure in the furnace rises, the remaining combustion gas etc. is released into the atmosphere from the slag discharge port etc., so the pressure in the combustion melting furnace is detected and the suction device is set so that this pressure is below atmospheric pressure To control.
[0013]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, an embodiment of a method for preventing closure of a slag discharge port in a combustion melting furnace of a waste treatment apparatus according to the present invention will be described with reference to FIGS.
[0014]
FIG. 1 is a system diagram of the waste treatment apparatus 1. This waste treatment apparatus 1 is mainly composed of a pyrolysis reactor 2 and a combustion melting furnace 3. More specifically, the waste a is supplied into the pyrolysis reactor 2 by a screw feeder 6 having a charging unit 4 and a driving device 5. The pyrolysis reactor 3 is constituted by a horizontal rotary drum, for example, and a low oxygen atmosphere is formed inside by an induction blower 7 as a suction device. In the pyrolysis reactor 2, the heated air b heated by the high-temperature air heater 8 disposed on the rear side of the combustion melting furnace 3 is supplied from the line L ₁ and discarded by indirect heating. The product is heated to 300 ° C. to 600 ° C., usually about 450 ° C. The waste a is pyrolyzed to produce pyrolysis gas G ₁ and pyrolysis residue c. The pyrolysis gas G ₁ and pyrolysis residue c are separated by the discharge device 9, and pyrolysis gas G ₁ is supplied to the burner 10 of the combustion melting furnace 3 via the line L ₂ , while the pyrolysis residue c is cooled by the cooling device 11 and then supplied to the separation device 12, where a combustible component mainly composed of carbon is used. It is separated into d and an incombustible component e such as rubble. The separated non combustible material e is recovered in the container 13, the combustion component d is a combustion melting furnace via a line L ₃ having a control valve V ₁ after being pulverized is supplied for example to 1mm or less in grinder 14 3 in the high temperature range of about 1,300 ° by the pyrolysis gas G ₁ supplied from the line L ₂ and the combustion air f supplied from the line L ₄ by the forced blower 15. Burned. A line of combustion air f is supplied to the burner 10 by a primary air line L ₄₁ having a control valve V _2, and a part thereof is provided at a lower portion through a secondary air line L ₄₂ having a control valve V _3. The secondary air nozzle 16 is supplied to a tertiary air nozzle 17 via a tertiary air line L ₄₃ having a control valve V _4, and so-called multi-combustion is performed in order to achieve low NOx. The combustion ash produced by such combustion and the ash contained in the combustible component become molten slag g and adhere to the inner wall of the combustion melting furnace 3 and flow down from the lower slag discharge port 18 into a water tank (not shown). On the other hand, the combustion gas G ₂ is recovered by the high-temperature air heater 8 and then recovered by the waste heat boiler 19 through the line L ₅ and is removed by the dust collector 20 and the gas cleaning device 21. And it is cleaned and becomes a relatively low temperature exhaust gas G ₃ , a part is released from the chimney 22 to the atmosphere, and the other part is supplied by the forced blower 23 through the line L ₆ as the cooling device 11 hanate gas. Further, another part of the exhaust gas G ₃ is supplied to the combustion melting furnace 3 via the line L ₇ by the forced air blower 24, and the temperature 25 of the combustion melting furnace 3 is controlled by an electric thermocouple. The temperature detector 25 is a pressure detector, and the temperature detector 25 and the pressure detector 26 are provided in the lower part of the combustion melting furnace 3, and their signals S ₁ and S ₂ are respectively controlled by a control device 27. Is input. The control device 27 includes a storage device 28, a comparator 29, an arithmetic device 30, and a signal creation device 31. Reference numeral 32 denotes a power generation device that generates electric power from the steam X generated in the waste heat boiler 19.
[0015]
In the embodiment of normal operation in the combustion melting furnace 3 in the waste treatment apparatus 1 having such a configuration, the control valves V _{1 to} V ₄ and the pusher blower 24 are controlled by a control device (not shown), and the temperature in the combustion melting furnace 3 is about. The supply of the combustible component d, the pyrolysis gas G ₁ or a part of the exhaust gas G ₃ is controlled so as to be 1,300 ° C.
[0016]
When the operation of the pyrolysis residue 3 is stopped during such normal operation, the control valve V ₁ is first controlled to stop the supply of the combustible component d and the pyrolysis gas G supplied from the line 2. By discharging ₁ from a line (not shown), the supply to the combustion melting furnace 3 is stopped. Then, the signal S ₁ of the temperature detector 25 is input to the comparator 29 of the control device 27, where it is compared with a predetermined value previously input to the storage device 28, for example, a signal S ₃ having a temperature in the vicinity of 1,100 ° C. Then, the difference signal S ₄ is input to the arithmetic unit 30. The proportional signal S ₅ by the variable difference is input to the signal generating apparatus 31, where the control signal S ₆ is applied to the forced draft fan 15 and the control valve V ₂ ~V _4. More specifically, the control blower 15 is actuated by the control signal S _{6 and} at least the control valves V ₃ and V ₄ are opened, and the secondary air and the tertiary air that are part of the combustion air are provided below the combustion melting furnace 3. There is provided as a cooling medium, of course the case open primary air control valve V ₂ optionally may be used as a cooling medium. In this case the detected pressure in the combustion melting furnace 3 by the pressure tester 26, a predetermined value is input in advance to the signal S ₂ is comparator 29 is input to the same to and stored device 28, for example, the atmospheric pressure after being compared, the control signal S ₇ via the operation unit 30 and the signal generating apparatus 31 is provided to attract the blower 7 as a suction device, is controlled so that at least a combustion pressure in the melting furnace 3 is less than atmospheric pressure.
[0017]
FIG. 2 shows another embodiment, in which the same reference numerals as those in FIG. 1 denote the same names. Line L ₇₁ branch line L ₇ are fed to the combustion melting furnace 3 a portion of the exhaust gas G ₃ is provided in this embodiment, the other end of the line L ₇₁ is connected to the lower portion of the combustion melting furnace 3 ing. Then, by supplying a control signal S ₆ from the control device 27 to the pusher fan 24 and the control valves V ₅ and V ₆ , at least a part of the exhaust gas G ₃ is supplied as a cooling medium to the lower part of the combustion melting furnace 3. The rapid cooling can be performed so that the rapid cooling rate is 50 to 500 ° C./min. According to the knowledge of the present inventor, as shown in FIG. 3, the flow rate of the molten slag g is 1 to 5 m / min when the temperature is 1,300 ° C., but the velocity decreases as the temperature decreases. It was found that when the temperature was around 1,100 ° C., it solidified and did not flow down. In order to reduce the temperature in the combustion melting furnace 3 to about 1,100 ° C. by natural cooling, about 0.1 to 0.5 H is required. The slag g almost reaches the vicinity of the slag discharge 18 and is cooled and solidified. As described above, the molten slag g is solidified on the inner wall of the combustion melting furnace 3 by rapidly cooling to the temperature at which the molten slag g solidifies. As a result, it is possible to prevent the slag discharge port 18 from being closed.
[0018]
In the above embodiment, a case where a part of the combustion air is separately supplied to the lower part of the combustion melting furnace 3 has been described. However, these may be supplied together.
[0019]
【The invention's effect】
As is clear from the above description, according to the method for preventing closure of the slag discharge port in the combustion melting furnace of the waste treatment apparatus according to the present invention, the lower part of the combustion melting furnace is rapidly cooled when the combustion melting furnace is stopped. As a result, the molten slag adhering to the inner wall surface and flowing down is cooled and solidified, and as a result, the slag discharge port can be prevented from closing.
[0020]
Furthermore, by using a part of the exhaust gas or a part of the combustion air as the cooling medium, there is an effect that it is possible to prevent the slag discharge port from being closed without providing a special device.
[Brief description of the drawings]
FIG. 1 is a system diagram for implementing a method for preventing closure of a slag discharge port in a combustion melting furnace of a waste treatment apparatus according to the present invention.
FIG. 2 is a system diagram showing another embodiment of a method for preventing closure of a slag discharge port in a combustion melting furnace of a waste treatment apparatus according to the present invention.
FIG. 3 is a graph showing the relationship between the flow rate of molten slag and the temperature.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Waste disposal apparatus 2 Pyrolysis reactor 3 Combustion melting furnace 4 Input part 5 Start-up apparatus 6 Screw feeder 7 Induction fan 8 High temperature air heater 9 Discharge apparatus 10 Burner 11 Cooling apparatus 12 Separation apparatus 13 Container 14 Crushers 15, 23 24 Air blower 16 Secondary air nozzle 17 Tertiary air nozzle 18 Slag outlet 19 Waste heat boiler 20 Dust collector 21 Gas scrubber 22 Chimney 25 Temperature detector 26 Pressure detector 27 Controller 28 Storage device 29 Comparator 30 Arithmetic unit 31 Signal generator 32 Power generator

Claims (5)

Waste is heated and pyrolyzed to produce pyrolysis gas and pyrolysis residue mainly composed of non-volatile components. Combustion components and combustion air separated from the pyrolysis gas and pyrolysis residue preparative burned by supplying the combustion melting furnace, resulting ash was flow down the molten slag by melt adhered to the furnace inner wall in the combustion melting furnace, cooled and discharged from the combustion melting furnace bottom of the slag discharge port supply in a combustion melting furnace by Ru solidified was Unishi waste treatment apparatus, in the furnace bottom of at least the combustion melting furnace during operation stop of the combustion melting furnace, a portion of at least one of a portion of the exhaust gas or combustion air by quenching the lower furnace and waste disposal closure method for preventing slag discharge port in the combustion melting furnace of the apparatus, characterized in that the molten slag to lower flow and to solidify on an inner wall surface of the combustion melting furnace . A temperature detector is arranged at the bottom of the combustion melting furnace and a control device is provided, and a signal from the temperature detector is input to the control device, and a part of the exhaust gas or combustion air is detected by the control signal generated by the control device. The method for preventing closure of a slag discharge port in a combustion melting furnace of a waste disposal apparatus according to claim 1, wherein a part of the supply amount is controlled. An exhaust gas suction device is provided on the downstream side of the combustion melting furnace, a pressure detector is provided in the combustion melting furnace, a signal of the pressure detector is input to the control device, and the control signal generated by the control device by controlling the suction device, the closing method for preventing slag discharge port in the combustion melting furnace waste disposal apparatus according to claim 1 you wherein the Turkey to retain the pressure in the combustion melting furnace to a predetermined value or less . The method for preventing closure of a slag discharge port in a combustion melting furnace of a waste treatment apparatus according to any one of claims 1 to 3 , wherein the lower temperature of the combustion melting furnace is rapidly cooled so as to be 1,100 ° C or lower. The method for preventing closure of a slag discharge port in a combustion melting furnace of a waste treatment apparatus according to claim 1 or 4 , wherein the rapid cooling is performed so that the rapid cooling rate is 50 to 500 ° C / min.

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