JP5255509B2 - Waste melting treatment method and waste melting treatment apparatus - Google Patents

Description

  TECHNICAL FIELD The present invention relates to a waste melting process that melts only a thermal decomposition residue obtained by drying and pyrolyzing waste to remove moisture and volatile matter in the waste, and in particular, a waste melting method for adjusting to an optimum thermal decomposition state And a waste melting apparatus.

  Waste such as general waste and industrial waste is charged into a shaft furnace type waste melting furnace with a massive carbon-based combustible material such as coke together with limestone, and air or oxygen-rich from the tuyeres provided in the furnace body Waste is dried, pyrolyzed, burned, and melted by blowing chemical air.

In waste melting treatment using a shaft furnace type waste melting furnace, the proportion of coke used as the main fuel for melting the material to be processed is large, and the amount of coke used to save processing costs. It is desired to reduce the above. On the other hand, in order to reduce the CO ₂ load on the environment in order to prevent global warming, it is desired to reduce the amount of coke derived from fossil fuel used as a melting heat source.

  In order to reduce the amount of coke used, for example, a method of injecting combustible materials other than combustible dust together with combustible dust discharged from the top of the furnace through the tuyere (Patent Document 1), combustible supplied from the lower blower tuyere (Patent Document 2) in which the blowing conditions are changed in accordance with the blowing amount of the functional dust, coke filled in the furnace by the heating coil is reduced and burned by air blown from the tuyere or oxygen-enriched air, and the coke A waste melting treatment method (Patent Document 3) or a method of using biomass such as wood (Patent Document 4) is proposed in which waste current is melt-treated by energizing an alternating current and induction heating. .

  In the packed bed in the shaft furnace type gasification melting furnace, the temperature of the solid is raised by direct heat exchange, and the heat efficiency is good, but the waste contains high moisture waste such as garbage and volatile matter such as wood. There are many large diameters. In conventional shaft furnace type gasification and melting furnaces, some of these wastes are not sufficiently dried or fall to the bottom of the furnace without being gasified of volatiles, and burn with coke.・ Melting. Since moisture and volatile matter in the lower part of the furnace both lower the ambient temperature, it is necessary to increase the amount of coke used as a result in order to maintain the ambient temperature high and completely dissolve non-combustibles. Further, when using external combustion such as LPG as a substitute for coke, the amount of external combustion (coke + gas) used remained high. Also, in conventional shaft furnaces, the amount of steam and exhaust gas associated with the gasification of volatile matter in the packed bed, such as when waste is charged or when undried and unpyrolyzed waste falls to the bottom of the furnace. Variations in quantity occurred.

  Therefore, in the waste melting treatment, the present applicant removes moisture and volatile matter in the garbage by separating drying and thermal decomposition from combustion and melting in a grate, and drying and thermal decomposition of the waste. A waste melting process was proposed to prevent it from descending to the lower part of the furnace when it is not. This suppresses the decrease in the ambient temperature at the bottom of the melting furnace, suppresses the consumption of coke that is used in excess of the amount necessary for melting ash, and reduces the amount of heat that the pyrolysis residue has and the amount of heat of a small amount of coke. It is possible to achieve complete melting and stabilize the amount of exhaust gas and the amount of steam (Patent Document 5).

  The waste melting technique described in Patent Document 5 will be described with reference to FIG.

  In FIG. 3, the waste melting apparatus includes a drying shaft portion 1 that dries the charged waste, a grate portion 2 that thermally decomposes the dried waste to generate a pyrolysis residue, and a pyrolysis residue. It consists of a pyrolysis residue melting part 3 that burns and melts. The drying shaft portion 1 is disposed above the entrance side of the grate portion 2, and the pyrolysis residue melting portion 3 is disposed below the exit side of the grate portion 2, communicated with the crank shape and integrally connected. Yes.

  The pyrolysis residue melting part 3 includes a lower hearth part 4, a morning glory part 5 connected to the hearth part 4, and a shaft part on the morning glory part 5. The hearth part 4 includes a lower tuyere 8 for blowing air and oxygen as an oxygen source, and an upper tuyere 7 for blowing air from the morning glory part 5 to the lower end of the shaft part. A coke bed is formed in the pyrolysis residue melting part 3 in the same manner as the bottom of the shaft furnace type waste melting furnace. Auxiliary materials such as coke and limestone are input from the auxiliary material inlet 15 at the top of the shaft 6.

  An exhaust gas outlet 9 and a waste charging inlet 10 are provided at the top of the drying shaft portion 1, and the waste charging inlet 10 is provided with a sealing lid 11 for preventing gas from blowing out during charging. . A waste supply device 12 is provided below the drying shaft portion 1.

  The grate part 2 includes a grate 13 that moves the waste charged from the drying shaft part 1 to the shaft part 6 while thermally decomposing the waste. Reference numeral 16 denotes an activation burner, and reference numeral 17 denotes a tuyere for blowing combustion air into the drying shaft portion.

  In the above-described configuration, the waste charged from the waste inlet 10 at the top of the drying shaft portion 1 is discarded in which the drying shaft portion 1 is filled with gas generated from the grate portion 2 and the hearth portion 3. Efficient drying and pyrolysis are performed by exchanging heat through the material. The pyrolysis residue generated by drying and pyrolysis falls into the pyrolysis residue melting part 3, burns and is melted by the heat source of the coke bed, and is discharged from the tap 14 of the hearth part 3. The exhaust gas passes through the waste of the drying shaft portion 1 and is exhausted from the exhaust gas outlet 9.

JP 2006-207911 A JP 2003-056820 A JP 2002-054810 A JP 2007-93069 A Japanese Patent Application No. 2008-183913

In the waste melting treatment apparatus shown in FIG. 3, if drying and pyrolysis in the grate portion are insufficient, it is necessary to compensate for the moisture drying heat amount in the pyrolysis residue melting portion, and complete combustion is caused. In such a case, it is necessary to supplement the amount of heat to melt the ash. Accordingly, if the waste is not properly dried and pyrolyzed, the amount of coke used in the pyrolysis residue melting part for supplementing the amount of heat increases, and the amount of CO ₂ emission increases.

  Therefore, the present invention is a waste that performs drying and pyrolysis of the waste in the grate portion, supplies the generated pyrolysis residue to the melting furnace, and melts it together with the massive carbon combustible material supplied from the upper part of the furnace. In the melting process, the gas component concentration in the furnace is measured at the grate where it is dried and pyrolyzed, and the measurement results are used to determine the drying and pyrolysis status of the waste. The present invention provides a waste melting treatment method and a waste melting treatment apparatus that change the air temperature and the amount of waste supply so that the waste drying / thermal decomposition state of the waste is optimized.

  In the first aspect of the invention, waste and a massive carbon-based combustible material are supplied from the upper part of the furnace, an oxygen source is supplied from the tuyeres at the lower part of the furnace, the waste is melted, and the molten material is supplied from the outlet of the hearth part. In a waste melting treatment method using a waste melting furnace for discharging hot water, a drying shaft portion for drying waste and a grate portion for generating thermal decomposition residue by pyrolyzing the waste dried by the drying shaft portion are melted. It is connected to the upper part of the furnace, and it is dried and pyrolyzed by passing the gas generated in the grate part and melting furnace through the waste packed bed formed by charging from the top of the furnace into the drying shaft part and pyrolyzing Residue is generated and the gas that has passed through the waste packed bed is discharged from the top of the drying shaft, and the generated pyrolysis residue is supplied to the melting furnace and burned and melted using the coke bed as the heat source. Analyze the concentration of gas components in the furnace Ascertain the drying / pyrolysis status of waste in the grate, and the grate speed, blown air volume, blown air so as to obtain the optimal waste drying / pyrolysis status based on the grasped drying / pyrolysis status A waste melting treatment method characterized by changing any one or two or more of temperature and waste supply amount.

The invention according to claim 2 is the waste treatment method according to claim 1, wherein the in-furnace gas component concentration is any one of CO concentration, O ₂ concentration, H ₂ concentration and CH ₄ concentration.

  A third aspect of the present invention is the waste treatment method according to the first or second aspect, wherein the CO concentration at which the optimum drying / pyrolysis state is achieved is 4 to 25% by volume.

A fourth aspect of the present invention is the waste disposal method according to the first, second, or third aspect, wherein the O ₂ concentration at which the optimum drying / pyrolysis state is achieved is 3% by volume or less.

The invention of claim 5 supplies waste and a massive carbon-based combustible material from the upper part of the furnace, supplies an oxygen source from the tuyeres at the lower part of the furnace, melts the waste, and melts the molten substance from the outlet of the hearth part. Connected to the upper part of the melting furnace for discharging hot water are a drying shaft part for drying waste and a grate part for further pyrolyzing the waste dried and pyrolyzed in the drying shaft part to generate a pyrolysis residue, An exhaust gas outlet for discharging the gas that has passed through the waste filling layer formed by charging from the top of the furnace into the drying shaft portion is provided at the top of the drying shaft portion, and further, the gas component in the furnace in the grate portion By analyzing the concentration, the means for grasping the drying / pyrolysis status of the waste in the grate part, and the optimum waste drying / pyrolysis status based on the drying / pyrolysis status grasped by the grasping means Grate speed, air blow The amount, blowing air temperature, a waste melting treatment apparatus characterized by means for changing over one or two or waste supply amount are provided.

  A sixth aspect of the present invention is the waste treatment apparatus according to the fifth aspect, wherein the gas analyzing means is a laser analyzer.

Since the present invention can accurately grasp the state of drying and pyrolysis by measuring the gas component concentration in the grate furnace, it becomes possible to properly dry and pyrolyze waste, and to perform drying and pyrolysis. By optimizing, it is possible to effectively use the energy of the waste, and as a result, it is possible to minimize the amount of external fuel used such as coke used in the melting furnace and the amount of CO ₂ emission.

In the present invention, the grate portion is measured by measuring the CO concentration, O ₂ concentration, H ₂ concentration and CH ₄ concentration, and managing the CO concentration in the range of 4 to 25% by volume and the O ₂ concentration in the range of 3% by volume or less. It becomes possible to make the combustible part in the thermal decomposition residue produced | generated by 20 to about 20-65 mass%. If the combustible fraction in the waste pyrolysis residue is about 20 to 65% by mass, the combustible component in the pyrolysis residue and the use of external fuel such as coke are minimized in the melting furnace installed after the grate. It becomes possible.

  If the combustible content in the waste is too high, it means that it can only be done until the waste is dried. In the melting furnace connected to the grate part, it is necessary to supplement the amount of heat to volatilize the volatile matter, such as coke. It is difficult to minimize the amount of external fuel used. On the other hand, if the combustible content in the pyrolysis residue is too low, it means that the pyrolysis residue is incinerated, and by using the combustible content in the pyrolysis residue effectively in the melting furnace, the amount of external fuel used such as coke Is difficult to minimize. As described above, in the melting furnace, it is very important to control the combustible content in the pyrolysis residue generated in the grate portion within an appropriate range.

  Furthermore, by performing drying / pyrolysis with a grate structure, it becomes possible to freely change the drying / pyrolysis state of waste estimated from the concentration of gas components in the furnace. For example, if it is surmised that the drying / pyrolysis of waste is insufficient from the concentration of gas components in the furnace, the pyrolysis residue is transferred to the melting furnace after accelerating the drying / pyrolysis by increasing the residence time in the grate. Can be supplied.

  In addition, by controlling the gas component concentration in the furnace with a laser analyzer, it becomes possible to control the drying and pyrolysis of the grate waste without causing a time lag in the gas analysis time. It is possible to reduce the amount of external fuel used such as coke.

It is the schematic of the waste melting processing apparatus of this invention. It is a graph showing the relationship between the combustible content of the CO concentration and the O ₂ concentration and in the dust. It is the schematic of the waste-melt-processing apparatus which isolate | separates drying and thermal decomposition and combustion melting.

  In FIG. 1, a waste melting treatment apparatus includes a drying shaft portion 1 for drying charged waste, a grate portion 2 for thermally decomposing dried waste to generate a pyrolysis residue, and a pyrolysis residue. It consists of a pyrolysis residue melting part 3 that burns and melts. The drying shaft portion 1 is disposed above the entrance side of the horizontal grate portion 2, and the pyrolysis residue melting portion 3 is disposed below the exit side of the grate portion 2 and communicates with the crank shape and is integrally connected. Has been. The drying shaft portion 1 is provided with a drying shaft portion tuyere 17 for blowing combustion air as necessary.

  The melting furnace 6 includes a lower hearth part 4, a morning glory part 5 connected to the hearth part 4, and a shaft part on the morning glory part 5. In some cases, the shaft portion is not provided. The hearth part 4 is provided with a lower tuyere 8 for blowing air and oxygen as an oxygen source, and the morning glory part 5 is provided with an upper tuyere 7 for blowing air. An activation burner 16 is provided at the upper part of the melting furnace 6. A coke bed is formed in the pyrolysis residue melting part 3 in the same manner as the bottom of the shaft furnace type waste melting furnace. Auxiliary materials such as coke and limestone are input from the auxiliary material inlet 15 at the top of the shaft 6.

  The grate part 2 includes a grate 13 that moves the waste charged from the drying shaft part 1 to the melting furnace 6 while thermally decomposing the waste. In the grate portion 2, as in a well-known stoker furnace, inclined grate that slides back and forth is arranged stepwise.

  The grate portion 2 is provided with gas analyzing means for analyzing the concentration of gas components in the furnace. A laser analyzer 18 that continuously analyzes gas is suitable for the gas analysis means. The continuous analysis of the laser analyzer enables accurate combustion control with no analysis time difference.

  In the above configuration, the waste charged from the waste inlet 10 at the top of the drying shaft portion 1 is filled with the gas generated from the grate portion 2 and the pyrolysis residue melting portion 3 in the drying shaft portion 1. Efficient drying is performed by heat exchange through the waste. The pyrolysis residue generated by drying and pyrolysis falls and fills from the grate portion 2 into the shaft portion 6, is combusted and melted by the heat source of the coke bed, and is discharged from the outlet 14 of the hearth portion 3. . The exhaust gas is exhausted from the exhaust gas outlet 9 of the drying shaft portion 1 and then recovered.

  The waste in the grate 2 is ignited by the burner 16 and then dried and pyrolyzed by self-combustion of combustibles or radiation of gas generated in the hearth, and the moisture content is 30% or less or the volatile content is 30% or less. Allow to dry. By providing a grate part 2 between the drying shaft part 1 and the pyrolysis residue melting part 3 so that the water content is 30% or less or the volatile content is 30% or less, the remaining water and volatile matter are contained in the pyrolysis residue melting part. 3 can be gasified by direct heat exchange in the packed bed. As a result, since the atmospheric temperature is not lowered in the pyrolysis residue melting part 3 and the blow-through phenomenon can be suppressed, the amount of coke used can be reduced. The blow-out phenomenon that occurs in the conventional shaft furnace type waste melting furnace occurs as a result of waste being not efficiently dried and thermally decomposed. By performing the separation separately in the section 2, the amount of exhaust gas can be stabilized, and blow-by can be prevented.

  Furthermore, since the volatile matter can be reduced by drying and thermal decomposition of the grate portion 2, it is possible to suppress fluctuations in the exhaust gas and the amount of steam accompanying the gasification of the volatile matter in the packed bed. If the water content exceeds 30% or the volatile content exceeds 30%, the atmospheric temperature in the lower part of the furnace will decrease in the same manner as in the conventional shaft furnace type melting furnace, so coke is used to maintain the atmospheric temperature. Therefore, the amount of coke used cannot be reduced.

    When the position of the exit side of the grate part 2 is 0.5 m or less from the upper surface of the pyrolysis residue packed bed of the pyrolysis residue melting part 3, the blown air and the pyrolysis residue are mixed to cause abnormal combustion, There is a possibility that the amount of decomposition residue will increase. Moreover, if the distance between the outlet side where the pyrolysis residue is introduced and the tuyere is 10 m or more, the introduced pyrolysis residue is scattered, and the fluctuation of the amount of exhaust gas becomes large.

In the present invention, by continuously analyzing the CO concentration, H ₂ concentration, CH ₄ concentration and unreacted O ₂ concentration generated during drying / pyrolysis of the waste in the grate portion 2 by the laser analyzer 18, drying is performed.・ Understand the pyrolysis status and adjust the operating conditions based on the results to obtain the optimal drying and pyrolysis status.

  In FIG. 2, if the ratio of combustible matter in the waste is too high, it means that only the drying can be performed, and it is necessary to supplement the amount of heat for volatilizing the volatile matter. On the other hand, if the proportion of combustible matter in the waste is too low, it means that it is ashed, and it is necessary to compensate for the amount of heat for melting the ash.

For example, by controlling the O ₂ concentration to 3% by volume or less and the CO concentration to 4 to 25% by volume, the combustible content in the waste can be reduced to about 20 to 65% by mass, and the waste can be carbonized. It becomes. As is clear from FIG. 2, when the CO concentration is 4% by volume or less, it is either not dried or thermally decomposed or completely burned. When the CO concentration is out of the range of 4 to 25% by volume, it is necessary to compensate for the amount of heat by changing the amount of coke used in order to ensure stable melting.

In FIG. 2, when the O ₂ concentration is too high, it means that the garbage is not combusted, which means that (1) it has been ashed and there is no food available. It means one of the states of not performing enough and not igniting. By setting the O ₂ concentration to 3% by volume or less, the combustible content in the waste can be reduced to about 20 to 65% by weight, and the waste can be appropriately dried and thermally decomposed. Furthermore, detonation due to staying mixing of CO gas and O ₂ can be suppressed by setting the O ₂ concentration to 3% by volume or less. The O ₂ concentration is preferably 1% by volume or less, and if it is 1% by volume or less, the volatile components in the waste are almost volatilized, and it is estimated that the state is in an optimum thermal decomposition state.

Although there is a range depending on the waste quality, the H ₂ concentration and CH ₄ concentration generated during the thermal decomposition of the waste are measured, and the grate speed, the blown air amount, the blown air are set so that the optimum pyrolysis state, that is, the concentration becomes high Adjust operating conditions such as temperature and waste supply rate.

In order to obtain an optimal drying / pyrolysis situation, the CO concentration, H ₂ concentration, CH ₄ concentration and O ₂ concentration are continuously analyzed, and in particular, the grate so that the values of the CO concentration and the O ₂ concentration are within the above-mentioned ranges. Adjust operating conditions such as speed, air volume, air temperature, and waste supply speed.

1: Drying shaft part 2: Grate part 3: Pyrolysis residue melting part 4: Hearth part 5: Morning glory part 6: Melting furnace 7: Lower tuyere 8: Upper tuyere 9: Exhaust outlet 10: Waste equipment Inlet 11: Sealing lid 12: Waste supply device 13: Grate 14: Outlet 15: Secondary material inlet 16: Burner 17: Drying shaft part tuyere 18: Laser analyzer

Claims (6)

By a waste melting furnace that supplies waste and massive carbon-based combustible material from the top of the furnace, melts the waste by supplying an oxygen source from the tuyeres at the bottom of the furnace, and discharges the melt from the outlet of the hearth In the waste melting treatment method,
A drying shaft section for drying waste and a grate section for thermally decomposing the waste dried by the drying shaft section to generate pyrolysis residue are connected to the upper part of the melting furnace, and the top of the furnace is placed in the drying shaft section. By passing the gas generated in the grate and melting furnace through the waste packed bed formed by charging from the furnace, it is dried and pyrolyzed to produce a pyrolysis residue, and the gas that has passed through the waste packed bed is It discharges from the top of the shaft for drying, supplies the generated pyrolysis residue to the melting furnace, burns and melts it using the coke bed as a heat source, and analyzes the concentration of gas components in the furnace in the grate section. Grasp the waste drying / pyrolysis situation, and based on the grasped drying / pyrolysis situation, grate speed, blown air volume, blown air temperature, waste supply so as to achieve the optimum waste drying / pyrolysis situation Any one or two Waste melt processing method characterized by changing the least. The waste treatment method according to claim 1, wherein the gas component concentration in the furnace is any one of a CO concentration, an O ₂ concentration, an H ₂ concentration, and a CH ₄ concentration.   The waste treatment method according to claim 1 or 2, wherein a CO concentration that achieves the optimum drying / pyrolysis state is 4 to 25% by volume. The waste disposal method according to claim 1, 2 or 3, wherein the O ₂ concentration that provides the optimum drying / pyrolysis condition is 3% by volume or less. Supply waste and massive carbon-based combustible material from the top of the furnace, supply oxygen source from the tuyeres at the bottom of the furnace, melt the waste, and discharge the melt from the outlet of the hearth to the top of the melting furnace The drying shaft portion for drying the waste and the grate portion for further thermally decomposing the waste dried and pyrolyzed in the drying shaft portion to generate a pyrolysis residue are connected,
An exhaust gas outlet for discharging the gas that has passed through the waste packing layer formed by charging from the furnace top into the drying shaft portion is provided at the top of the drying shaft portion,
Further, by analyzing the concentration of gas components in the furnace in the grate part, the means for grasping the drying / pyrolysis state of waste in the grate part, and the drying / pyrolysis state grasped by the means for grasping It is characterized in that means for changing one or more of the grate speed, the amount of air blown, the temperature of air blown, the amount of waste supply is provided so as to achieve the optimum waste drying / pyrolysis situation Waste melting treatment equipment.   6. The waste treatment apparatus according to claim 5, wherein the gas analysis means is a laser analyzer.

Images