JPH09166309A - Operating method of waste melting furnace - Google Patents

Abstract

(57) [Abstract] [PROBLEMS] To provide a method of operation in which thermal decomposition gas generated from a melting furnace is wet-cleaned and the calorie of the gas recovered is significantly improved when the gas is recovered, thereby improving the utility value as a fuel. To do. SOLUTION: In a method of treating waste in a coke bed type waste melting furnace, a part of combustible gas generated from a tuyere arranged in a lower tuyere or more is 25
By burning a part of the combustible gas in the furnace with air of about 0 Nm ^{3, the} temperature of the gas at the top of the melting furnace is constantly maintained at 80
By controlling to a high temperature atmosphere of 0 to 1100 ° C, the tar in the high temperature combustible gas containing combustible dust and tar is completely gasified and pyrolyzed, and the gas with higher calorific value than before is recovered by performing wet gas treatment. In addition, a method of operating a waste melting furnace characterized by recovering combustible dust by a dust collector as a heat source.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a lumpy carbonaceous combustible substance such as coke or the waste itself as a heat source.
Heating with oxygen or air, municipal waste, various industrial wastes,
Alternatively, the present invention relates to a heating and melting treatment method of an intermediate treated product obtained by dehydration, drying, incineration, crushing treatment or the like.

[0002]

2. Description of the Related Art A waste melting treatment furnace has a pyrolysis furnace that pyrolyzes waste with high-temperature gas, and a melting furnace that produces high-temperature gas for pyrolysis by combustion and at the same time melts ash and inorganic substances. It is an efficient shaft furnace. The processing modes in the melting furnace are roughly divided into drying of waste, pre-tropical zone, carbonization zone,
It is divided into three zones of combustion / melting zone. The dust charged from the upper part of the furnace is dried and preheated in the drying zone (about 300 ° C), gasified in the thermal decomposition zone, and the residual ash and metal, ceramics, glass Approximately 200
Melted at 0 ° C.

To melt-treat such waste, the coke-blended waste is charged from the top of the shaft furnace,
An oxygen-containing gas or an oxygen-rich gas is blown into the furnace from the tuyere, and the carbonaceous matter generated by coke and pyrolysis is burned at a high temperature in the high-temperature hearth, and the dry zone, carbonization gasification zone and combustion melting in the furnace are performed. Technology to recover the generated gas from the melting furnace containing tar and dust by wet treatment of the high temperature combustion exhaust gas, which rises as a counter flow in the waste packed bed in the shaft, by gradually descending the zone to form molten slag. Is JP-A-5
It is disclosed in Japanese Patent Publication No. 4-94767. A method for purifying gas generated from a melting furnace is disclosed in Japanese Patent Laid-Open No. 54-10266.
No. 5 discloses this. A method of operating a waste melting furnace is disclosed in Japanese Patent Laid-Open No. 6-231668.

In the first disclosed technology, the wastewater generated in the purification process in the method of wet-cleaning the gas generated from the melting furnace is used as a concentrated waste liquid containing fine particles such as tar sludge and scum, and is pumped into the furnace for melting. It is a method of treating flammable gas cleaning wastewater in waste melting treatment that is characterized by decomposing, and it does not completely decompose tar in the generated gas and recover high calorie gas by gasifying tar at high temperature. Absent.

The second one is to pass the gas generated from the melting furnace through a moving packed bed type purification device to collect combustible dust and tar, and also to collect coke or limestone of the combustible dust and tar. Is a technique for charging and melting in a melting furnace, and does not decompose tar into gas at high temperature. The third one is a melting furnace that has at least the lower tuyeres on the hearth side of the melting furnace that melts waste, and has a plurality of upper tuyeres arranged above and below it, and the air supplied from the upper tuyeres. This promotes the combustion of combustible components in the waste in the furnace where the upper tuyeres are installed, and is not for burning the gas generated in the furnace to raise the furnace top gas temperature.

[0006]

Generally, in the case of melting and treating waste, combustible gas generated from a melting furnace contains combustible dust and tar. One method is to recover the combustible gas and the tar by using the generated gas with a wet water washing process and a bag filter, respectively, but the calorie of the gas alone is low, and the recovered tar is not combustible. However, there is a problem that a separation device for recovery is required. Under such conditions, the problem to be solved by the present invention is to perform a wet cleaning treatment of gas by completely pyrolyzing and gasifying tar contained in a combustible gas generated from a melting furnace. In addition, the downstream wet gas treatment device is simplified, the calorie of the recovered gas is greatly improved, and the utility value as a fuel is improved.

[0007]

Means for Solving the Problems In order to solve the above-mentioned problems, a feature of the present invention is that one of the combustible gases generated in a method of treating waste in a coke bed type waste melting furnace. Part from the tuyeres arranged in the lower tuyeres 1 or more, by burning about 250 Nm ³ of air per 1 ton of dust, a part of the combustible gas in the furnace is burned to keep the melting furnace furnace top gas temperature at 800 to 1100. It is an object of the present invention to provide a method of recovering a gas having a higher calorific value than before by controlling the temperature to 0 ° C., completely decomposing the tar in a high-temperature combustible gas containing combustible dust and tar, and performing a wet gas treatment.

[0008] When a waste substance undergoes thermal decomposition, it is generally decomposed into a residue, tar, thermal decomposition gas, and dry distilled water. It turned out to be high in calories. Therefore,
Lowering the height level of the waste in the melting furnace, increasing the temperature of the combustible gas generated, further, burned by the air charged from the tuyere arranged above the lower stage tuyere,
By keeping the gas temperature at the furnace top at 800 ° C or higher and charging the waste into the furnace in this high-temperature gas atmosphere, the injected waste is immediately dried and high-temperature carbonization starts, and the tar generated is removed from the furnace. Inside, it is completely decomposed into hydrocarbon gas by heat.

That is, conventionally, the treatment was carried out in three zones of drying / pre-tropical zone, carbonization zone, combustion / melting zone, but in the present invention, the inside of the furnace is dried in order to completely gasify tar at a higher temperature than in the past. It is processed in two zones: carbonization / pre-tropics and combustion / melting zone. The gasification of tar is completed if the temperature is 800 ° C or higher, but if the gas temperature at the furnace top is 1100 ° C or higher,
It was found that the flammable dust generated by the thermal decomposition of the waste adheres to the wall of the melting furnace and deteriorates the unloading of the waste. Therefore, depending on the amount of air charged from the tuyere, the gas temperature at the furnace top can be set to 8
It is desirable to control the temperature to be not lower than 00 ° C and not higher than 1100 ° C.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION The structure of a furnace will be described below with reference to FIG. That is, FIG. 1 is a view showing the structure of the waste melting furnace according to the present invention. The lower part of the furnace is a combustion / melting zone, and the lower tuyeres 1 are arranged. The upper tuyeres 2 are arranged on the morning glory part (B) and the upper part thereof. In the present invention, while monitoring the furnace top temperature, air of 250 Nm ³ / dust t is blown from the upper tuyeres 2 to make the furnace top gas temperature from 800 ° C. to 1100.
C. was controlled. Further, by lowering the height of filling the refuse, the temperature of the gas at the top of the furnace was increased, the amount of air blown from the upper stage was decreased, and it was effective in increasing the gas simple calories.

The processing flow of the exhaust gas from the waste melting furnace will be described with reference to FIG. The dust-mixed gas pyrolyzed in the melting furnace 3 passes through the cyclone 4, most of the dust is removed, and the cleaning tower 5 and the venturi scrubber 6 are passed, whereby HCl is removed. The purified gas is burned in a separate combustion furnace 12 after passing through the bag filter 7, and the combustible dust collected in the cyclone 4 for highly efficiently recovering waste heat is once stored in the hopper 8, It is blown quantitatively from the tuyere 2 of the melting furnace as a heat source. The cleaning liquid used for gas cleaning is stored in the liquid storage tank 9, processed in the cleaning liquid processing tank 10, and circulated and reused as the cleaning liquid via the cleaning liquid circulation pump 11.

In addition, the collected clean high-calorie gas is
Combustion using the equipment of the adjacent steelworks enables heat recovery with reduced equipment costs. Table 1 shows the calorific value of the combustible gas generated from the melting furnace and the amount of tar in the gas when the waste is pyrolyzed and melted, together with the values when the gas temperature at the furnace top is kept at the conventional temperature.

[0013]

[Table 1]

[0014]

According to the present invention, the following effects can be realized. (1) According to the present invention, in the case of recovering a gas by a wet process, it is possible to recover tar, which has been troublesome in separating and recovering it, as a gas having good handleability. (2) By thermally decomposing tar at a high temperature, it is possible to recover it as a hydrocarbon-based gas, and a flammable gas having a higher calorie than before can be recovered, which is of great industrial value. (3) In order to gasify the tar in the flammable gas generated from the melting furnace according to the present invention, the tar separation device, which was necessary when the generated gas from the conventional melting furnace is wet-processed, becomes unnecessary, and the downstream flow The wet gas treatment device of is simple and economical.

[Brief description of the drawings]

FIG. 1 is a view showing a structure of a waste melting furnace according to the present invention,

FIG. 2 is a diagram showing a processing flow of exhaust gas from a waste melting furnace.

[Explanation of symbols]

 1 Lower tuyeres 2 Upper tuyeres 3 Melting furnace 4 Cyclone 5 Washing tower 6 Venturi scrubber 7 Bag filter 8 Hopper 9 Storage tank 1 0 Washing liquid treatment tank 1 1 Washing liquid circulation pump 1 2 Combustion furnace

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI technical display location F23J 15/02 F23J 15/00 C 15/00 J

Claims (3)

[Claims] 1. A method for treating waste in a coke bed type melting furnace having a lower tuyeres in the hearth and an upper tuyer in the upper bosh, and the temperature in the furnace top of the melting furnace. Is kept in a high temperature atmosphere of 800 ° C to 1100 ° C, and the charged waste is immediately subjected to high temperature dry distillation to gasify the tar in the combustible gas generated in the furnace, thereby melting the waste. How to operate the furnace. 2. The air blown from the upper tuyere burns a part of the combustible gas in the furnace to maintain the ambient temperature in the furnace top at 800 ° C. to 1100 ° C. Operation method of waste melting furnace. 3. The combustible dust in the pyrolysis gas discharged to the outside of the furnace is recovered by a dust collector, while the gas is washed with water and recovered as a high-calorie gas. Operation method of the waste melting furnace described.