JP4038536B2 - Reduction melting furnace and high temperature reducing gas recovery method using the same - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention suppresses the generation of dioxins by reducing the position where the pyrolyzed gas generated in the process of treating general waste and industrial waste, etc., in the process of processing is lower than the filling height level, and reducing gas. The present invention relates to a reduction melting furnace that recovers the energy of the gas and a high-temperature reducing gas recovery method using the same.
[0002]
[Prior art]
In recent years, the amount of general waste, so-called municipal waste, has increased, and most of these waste (hereinafter referred to as general waste, industrial waste, incinerated ash, incombustibles, etc.) has been reduced by incineration and incinerated. Landfilled in landfill as ash or incombustible. However, the increase in the amount of municipal waste generated is developing as a problem of shortage of final disposal sites such as incineration residue of municipal waste. In order to cope with these, a waste direct melting method has been proposed. As an example, general waste is made to be useful resources such as slag by a waste direct melting furnace to which iron manufacturing technology as disclosed in Patent Document 1 is applied. In the case of this waste direct melting furnace, the oxygen atmosphere is in an atmosphere of 3 to 21% and incineration is performed at 100 to 1200 ° C. As a result, incineration ash and unburned substances are actually obtained. is there.
[0003]
FIG. 4 is an overall schematic view of a conventional solid furnace type waste melting furnace. As shown in this figure, the reduction melting furnace 1 is composed of a shaft part 5, a morning glory part 6 and a furnace bottom part 7, and an upper tuyere 3 provided around the morning glory part and a lower stage feather provided around the lower part of the furnace. Air is supplied from the mouth 4. Coke and limestone are charged from the charging device 2 as waste and auxiliary materials from the upper part of the reduction melting furnace 1 having such a configuration. The charged waste and coke form a packed bed in the furnace, and the combustible waste and coke are reduced and burned by the air blown from the upper tuyere 3 and the lower tuyere 4. This combustion gas rises in the melting furnace from the lower part of the furnace and preheats, dries, and thermally decomposes the waste. Water vapor, pyrolysis gas, etc. generated in the process of preheating, drying and pyrolysis of the waste are discharged from a gas discharge pipe 8 provided in the upper part of the reduction melting furnace 1. On the other hand, the pyrolysis residue is in a molten state and discharged from the slag discharge hole 9 to the outside of the furnace.
[0004]
In the shaft furnace method and the solid furnace method for treating general waste and industrial waste described above, the waste supplied together with limestone and coke from the upper part of the melting furnace evaporates moisture in the preheating drying zone. The dried waste falls and is pyrolyzed into combustible gas and combustible material in the pyrolysis zone, and the combustible material burns in the combustion zone. The high-temperature combustible material combustion residue further falls to the melting zone together with the coke supplied in advance. An air supply tuyere is provided at the bottom of the furnace, and coke is burned at a high temperature by the oxygen-enriched air fed from the air feed tuyere and the combustible combustion residue is completely melted. The basicity of the melt is adjusted by limestone supplied in advance, and the melt is discharged from the tapping hole while maintaining appropriate fluidity. This method is excellent in that the property of the melt is stable and homogeneous, the utility value as various materials is high, and the final disposal amount is minimized.
[0005]
[Cited document]
(1) Patent Document 1 (Japanese Patent Laid-Open No. 2002-48321)
[0006]
[Problems to be solved by the invention]
However, in the shaft furnace method and the solid furnace method described above, waste and limestone or coke are introduced from the upper part of the melting furnace, and exhaust gas is discharged from the upper part of the furnace. Since it is discharged from the upper part from the level of the charged waste that has been input, it is an acidic exhaust gas that contains the moisture of the input waste in the exhaust gas as it is or has O ₂ remaining, and this input The temperature of the exhaust gas is constantly lowered from room temperature to about 100 ° C., and the composition of the exhaust gas varies greatly depending on the water in the waste that has been input, The composition of the exhaust gas includes N ₂ , O _2, and CO ₂ depending on the air in the input waste.
[0007]
As described above, since the conventional melting furnace is a method of exhausting exhaust gas from the top, the temperature of exhaust gas generated by processing general waste and industrial waste is lowered, and dioxins are generated. was there. On the other hand, since the temperature of the exhaust gas is lowered, there is a problem that the burner must be assisted by the secondary combustion in the next step. Therefore, the present situation is that the exhaust gas is only a waste gas that is discarded as it is.
[0008]
Means to be Solved by the Invention
In order to solve the above-mentioned problems, the inventors have made extensive developments. As a result, the high temperature gas generated in the melting furnace and the filling height level of the waste charged in the melting furnace and the coke A reduction melting furnace having a riser at a position lower than a filling height level and a method using the same are provided. The gist of the invention is that
(1) In a reduction melting furnace for waste, at a lower position than a charging damper gate valve disposed at the lower end of the charging inlet, and from a filling height level of waste and coke charged in the melting furnace. A reductive melting furnace characterized in that a riser pipe is disposed at a position where the exhaust gas height level is as low as 3 m or more , and high temperature reducing gas can be recovered from the riser pipe.
[0009]
( 2 ) When discharging high-temperature gas generated from the melting furnace of waste, the waste and coke put into the melting furnace at a position lower than the charging damper gate valve disposed at the lower end of the charging inlet. It has a riser pipe that can discharge high-temperature reducing gas at a position 3m or more lower than the filling height level of the exhaust gas, and melts the input waste to overheat the waste water. Steam, waste is thermally decomposed into a high-temperature reducing gas of 320 ° C. or higher and converted into a high-temperature reducing gas having a residual oxygen content of 0.5% or less, and then the high-temperature reducing gas is discharged from the riser as energy. A high temperature reducing gas recovery method characterized by recovering.
( 3 ) The waste melting furnace described in ( 2 ) is melted at a high temperature of 1000 to 2600 ° C., and the amount of residual oxygen discharged from the riser is controlled to a high temperature reducing gas temperature and concentration of 0.5% or less. It is in the high temperature reducing gas recovery method characterized by this.
[0010]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the present invention will be described in detail with reference to the drawings.
FIG. 1 is an overall schematic view of a reductive melting furnace according to the present invention. As shown in FIG. 1, the waste damper gate valve 10 is opened from the charging device 2 provided in the upper part of the reduction melting furnace 1 and the waste supplied together with limestone and coke is gradually lowered, and the waste and coke. Is reached, and is pyrolyzed into combustible gas and combustible material in the pyrolysis zone of the waste and fuel coke packed bed 12, and the combustible material burns in the combustion zone. The high-temperature combustible material combustion residue further falls to the melting zone 13 together with the coke supplied in advance. The upper bottom tuyere 3, the middle tuyere tuyere 17 and the lower tuyere tuyere 4 are provided in the furnace bottom 7, and the coke is burned at a high temperature by the oxygen-enriched air supplied from the air supply tuyere, and the combustible combustion residue 14 To completely melt. The melt is discharged from the slag discharge hole 9 while the basicity is adjusted by the limestone supplied in advance and the appropriate fluidity is maintained. Reference numeral 16 denotes a melt dripping zone.
[0011]
On the other hand, the gas discharge port 12 is at a lower position than the input damper gate valve 10 disposed at the lower end of the input port 2 into which the waste is input, and from the filling level 11 of the waste and coke charged into the melting furnace. A rising pipe 15 capable of discharging the high temperature reducing gas is provided at a low position. The position of the riser 15 is preferably provided immediately above the waste in a molten state as much as possible. The riser 15 is provided at a location where there is no influence of the melt, and the O ₂ content is drastically reduced and the hot reducing gas is rich. There is a need. For that purpose, it is optimal to provide at a position lower than the filling height level of 3 m. Thereby, it can be recovered as a high-temperature reducing gas.
[0012]
FIG. 2 is a diagram showing the relationship between the distance between the filling height level and the exhaust gas height level and the H ₂ gas concentration. As shown in this figure, it can be seen that when the distance between the filling height level and the exhaust gas height level exceeds 3 m, the H ₂ gas concentration is rapidly increased. FIG. 3 is a graph showing the relationship between the distance between the filling height level, the exhaust gas height level, and the residual O ₂ concentration. As shown in this figure, as in the case where the distance between the filling height level and the exhaust gas height level is H ₂ gas concentration, when the distance between the filling height level and the exhaust gas height level exceeds 3 m, the residual O ₂ It can be seen that the concentration decreases. As can be seen, it can be seen that if the distance between the filling height level and the exhaust gas height level is designed to be 3 m or more, a gas having a high H ₂ gas concentration that does not contain the residual O ₂ concentration can be recovered.
[0013]
Reductive melting of a structure having a riser pipe at a position lower than the filling height level of waste and the filling height level of coke charged in the melting furnace with the high-temperature gas generated in the melting furnace as described above Since the furnace was made into a furnace, the exhaust gas temperature was lower than the waste and coke filling height level, so it approached the red hot coke at the bottom of the furnace 1300-2400 ° C, and the exhaust gas temperature was 800-2000 ° C, Generation of dioxins is suppressed, H ₂ O is decomposed into H ₂ , and other wastes are also thermally decomposed at high temperature, so that they are discharged as reducing gases such as H ₂ and CO gas. Moreover, it is a reducing melting furnace that can be controlled to a high-temperature reducing gas. Therefore, this gas can be recovered not as waste gas but as energy gas.
[0014]
Hereinafter, the present invention will be specifically described with reference to examples.
【Example】
Using the reduction melting furnace based on FIG. 1, coke and limestone are charged into the reduction melting furnace 1 from the top of the reduction melting furnace 1 as waste and auxiliary materials. Municipal waste was treated as waste. The municipal waste is composed of 8.2% ash, 18.5% moisture, and 73.3% combustible material. Air and oxygen are supplied from the mouth 17 and the lower tuyere 4. About 27% of the throughput of waste 395kg / h, coke and limestone waste, air is 12Nm ³ / h, the air and oxygen are upper tuyere 3 Nm ³ / h, middle tuyere 3 Nm ³ / It was blown under the conditions of h, lower tuyere 6 Nm ³ / h. Waste and coke charged in the reduction melting furnace form a packed bed in the furnace, and the waste is melted by air and oxygen blown from the upper tuyere 3, the middle tuyere 17 and the lower tuyere 4 The water in the treated waste is converted into superheated steam, and the waste is thermally decomposed into a high-temperature reducing gas of 320 ° C. or more and 2000 ° C. or less and converted into a high-temperature reducing gas having a residual oxygen content of 0.5% or less.
[0015]
This combustion gas rises in the reduction melting furnace from the lower part of the furnace, and is discharged from the riser 15 which can discharge the high temperature reducing gas at a position lower than the filling height level of waste and coke charged in the melting furnace. And collect it as energy. The temperature of the discharged gas and the dioxin concentration in the conventional case are 98 to 220 ° C., whereas in the present invention, the gas temperature is as high as 875 to 2000 ° C., and the dioxin concentration is 0.42 ng− for TEQ / Nm ^3, it can be seen that depleted the 0.002ng-TEQ / Nm ^3. In addition, since the discharged gas temperature can be recovered higher than before, the power generation using the high-temperature gas is significantly increased and the energy recovery rate is increased.
[0016]
【The invention's effect】
As described above, the temperature of the gas discharged by the present invention is 320 ° C to 2000 ° C higher than that of the conventional method, the dioxin concentration is greatly reduced, and the power generation utilizing the high temperature gas is also greatly increased, resulting in energy recovery. On the other hand, the rate becomes high, and it becomes a CO-rich state, and there is an extremely excellent effect such that the generated reducing gas can be used as fuel.
[Brief description of the drawings]
FIG. 1 is an overall schematic view of a reduction melting furnace according to the present invention.
FIG. 2 is a diagram showing the relationship between the distance (Δh) between the filling height level and the exhaust gas height level and the H ₂ gas concentration.
FIG. 3 is a graph showing a relationship between a distance (Δh) between a filling height level and an exhaust gas height level and a residual O ₂ concentration.
FIG. 4 is an overall schematic diagram of a conventional solid furnace type waste melting furnace.
DESCRIPTION OF SYMBOLS 1 Reduction melting furnace 2 Charging apparatus 3 Upper tuyere 4 Lower tuyere 5 Shaft part 6 Morning glory part 7 Furnace lower part 8 Gas discharge pipe 9 Slag discharge hole 10 Input damper gate valve 11 Filling height level 12 Packing bed 13 Melting zone 14 Combustible residue 15 Ascending pipe 16 Melting drip zone 17 Middle tuyere 18 Exhaust gas height level 19 Δh (filling height level minus exhaust gas height level)

Claims (3)

In a reductive melting furnace for waste, the exhaust gas height is lower than the input damper gate valve disposed at the lower end of the charging inlet and the exhaust gas height is higher than the filling height level of waste and coke charged in the melting furnace. A reductive melting furnace characterized in that a riser pipe is arranged at a low position with a level distance of 3 m or more , and high temperature reducing gas can be recovered from the riser pipe. When discharging high-temperature gas from the waste melting furnace, the filling height of the waste and coke charged into the melting furnace is lower than the charging damper gate valve disposed at the lower end of the charging inlet. It has a riser pipe that can discharge high-temperature reducing gas at a position where the distance of the exhaust gas height level is 3 m or more lower than the height level, melts the waste that has been thrown in, and makes the water in waste superheated steam, The waste is thermally decomposed into a high-temperature reducing gas of 320 ° C. or higher and converted into a high-temperature reducing gas having a residual oxygen content of 0.5% or less, and then the high-temperature reducing gas is discharged from the riser and recovered as energy. A high-temperature reducing gas recovery method characterized by the above. A waste melting furnace according to claim 2, wherein the waste is melted at a high temperature of 1000 to 2600 ° C, and the amount of residual oxygen discharged from the riser is controlled to a high temperature reducing gas temperature and concentration of 0.5% or less. High temperature reducing gas recovery method.

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