JP2010038535A - Waste melting treatment method and waste melting treatment device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a waste melting treatment capable of eliminating water content and volatile matter content in garbage by performing drying-thermal decomposition in pretreatment separately from combustion-melting to suppress consumption of cokes which have been used more than necessity in melting ash content, performing complete melting by heat of waste thermal decomposition residue and heat of a small amount of cokes, and stabilizing the amount of exhaust gas and steam flow. <P>SOLUTION: The drying-thermal decomposition of waste is performed by a pretreatment device 9 provided in a shaft furnace type waste melting furnace without utilizing a heat source of cokes charged into the shaft furnace type waste melting furnace, then the obtained thermal decomposition residue is supplied to the shaft furnace-type waste melting furnace, and the heat source of cokes is mainly utilized in combustion melting. <P>COPYRIGHT: (C)2010,JPO&amp;INPIT

Description

  The present invention relates to a waste melting treatment technology that reduces the amount of coke used by drying and pyrolyzing waste in a pretreatment device and melting only the pyrolysis residue from which moisture and volatile matter in the waste have been removed. .

  Waste such as general waste and industrial waste is charged into a waste melting furnace with a massive carbon-based combustible material such as coke together with limestone, and air or oxygen-enriched air is supplied from the tuyere provided in the furnace body. Blowing, drying, pyrolysis, combustion, and melting of waste to melt the waste are performed.

  In FIG. 3, in the shaft furnace type waste melting furnace 31, the waste is charged together with the auxiliary materials such as coke and limestone by the charging device 32 from the upper part of the furnace. The waste is discharged as slag from the tap 33 through processes of drying, thermal decomposition, combustion, and melting in the furnace. Some of the combustibles in the waste are carbonized and discharged as gas, and some are combusted by air and oxygen blown from the tuyere 34 in the lower part of the furnace, but the remaining combustibles are combustible. Dust is discharged from the top of the melting furnace 31 as dust.

  The combustible dust discharged from the top of the shaft furnace type waste melting furnace 31 is collected by the combustible dust collecting device 35, stored in the combustible dust storage tank 36, and then combusted by the combustible dust cutting device 37. It is blown into the furnace from the tuyere 34 that is cut out and supplies oxygen-enriched air. The exhaust gas that has passed through the combustible dust collector 35 is burned in the combustion chamber.

  In the waste melting treatment using a shaft furnace type waste melting furnace, the ratio of coke used as the main fuel for melting the treated material is large in the processing cost. Reduction is desired.

On the other hand, development for reducing CO ₂ derived from fossil fuels such as coal has been promoted from the viewpoint of preventing global warming, and coke derived from fossil fuels is also used as a melting heat source in shaft furnace type waste melting furnaces. Therefore, it is desired to reduce the amount of coke used in order to reduce the CO ₂ load on the environment.

  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), oxygen supplied from the lower blowing tuyere The ratio (B / A) of the theoretical oxygen amount (B) determined from the amount and composition of the combustible dust and coke collected and supplied from the lower air tuyeres to the amount (A) is 0.5 to 1. Enrichment of air or oxygen blown from the tuyere of coke filled in the furnace by a heating coil (Patent Document 2) In addition to reducing combustion with air, an alternating current is applied to the coke and induction heating is performed to inductively heat the waste to melt the waste (Patent Document 3) or biomass such as wood. And a method of (Patent Document 4) have been proposed.

JP 2006-207911 A JP 2003-056820 A JP 2002-054810 A JP 2007-93069 A

  In the shaft furnace, the temperature of the solid is increased by direct heat exchange in the packed bed, and the heat efficiency is good, but the waste has a lot of high moisture waste such as raw garbage and volatile matter such as wood, and the diameter is large. There is something big. In conventional shaft type gasification and melting furnaces, some of these wastes are not sufficiently dried or gasified in the volatile matter, so they fall to the bottom of the furnace and burn and melt together with coke. . Since moisture and volatile matter in the lower part of the furnace both lower the atmospheric temperature, it is necessary to increase the amount of coke used as a result in order to maintain the atmospheric temperature high and completely melt the non-combustibles. Further, when using external fuel such as LPG as a substitute for coke, the amount of external fuel (coke + gas) used remains high. Also, in conventional shaft furnaces, the amount of steam and exhaust gas accompanying the gasification of volatile matter in the packed bed, such as when charging waste or when undried / undried waste falls to the bottom of the furnace. Fluctuations occurred.

  Furthermore, in the conventional shaft type gasification melting furnace, moisture and volatile components are not uniformly dried and gasified, and a gas drift phenomenon called blow-through may occur.

  Therefore, in the present invention, in the waste melting treatment, drying and thermal decomposition are performed in the pretreatment, and separated from combustion and melting to remove moisture and volatile matter in the waste, By preventing the temperature from dropping to the bottom of the furnace without being thermally decomposed, the temperature at the bottom of the furnace is prevented from lowering, and the consumption of coke used in excess of the amount necessary for melting ash is suppressed, resulting in waste heat. The present invention provides a waste melting treatment technique capable of achieving complete melting with the heat amount of the cracking residue and the heat amount of a small amount of coke and stabilizing the amount of exhaust gas and the amount of steam.

  The present invention, after utilizing the heat source of coke put into the shaft furnace type waste melting furnace, after drying and pyrolyzing the waste in the pretreatment device attached to the shaft furnace type waste melting furnace, The obtained pyrolysis residue is supplied into a shaft furnace type waste melting furnace, and the coke heat consumption of the shaft furnace type waste melting furnace is reduced by using a heat source of coke exclusively for combustion melting.

  According to the first aspect of the present invention, waste ash and non-combustible material are supplied from the upper part of the furnace and supplied with an oxygen source from the tuyeres at the lower part of the furnace and melted from the outlet of the hearth part. The waste inserted in the pretreatment device connected outside the shaft part of the shaft furnace type waste melting furnace in the shaft furnace type waste melting furnace in the shaft furnace type waste melting furnace that discharges the generated gas from the top of the furnace The product is dried and pyrolyzed to a moisture content of 30% or less or a volatile content of 30% or less, and the resulting pyrolysis residue is supplied from a pretreatment device into a furnace and melted. By this method, the dried and pyrolyzed pyrolysis residue is supplied to the coke bed in the hearth. As a result, the decrease in moisture and volatiles to the hearth is reduced, and it is possible to suppress the decrease in atmospheric temperature accompanying the evaporation of water and gasification of the volatiles in the hearth. It becomes possible to reduce the amount of coke used. In addition, by removing moisture and volatile components with the pretreatment device, fluctuations in the amount of gas generated from the melting furnace can be suppressed to less than that of the conventional furnace. As a result, the amount of steam and the amount of exhaust gas can be stabilized, and the exhaust gas treatment facility can be made more compact than a conventional furnace.

  Moreover, as shown in claim 2, the waste charged in the pretreatment device is dried and thermally decomposed by utilizing the radiant heat of the combustible gas generated by the combustion and melting of the pyrolysis residue and coke in the lower part of the furnace. Accordingly, the waste can be efficiently dried and thermally decomposed in the pretreatment apparatus.

  Further, the invention described in claim 3 is a method in which combustible gas generated in the lower part of the furnace is partially burned in the lower part of the furnace and its radiant heat is used. Since the radiant heat increases by partially burning the combustible gas generated in the lower part of the furnace, the waste can be dried and pyrolyzed more efficiently.

  In addition, by continuously supplying the pyrolysis residue into the shaft as described in claim 4, the generated gas calorie generated by the combustion and melting of the pyrolysis residue is stabilized, and the fluctuation of the steam amount and the exhaust gas amount is suppressed. can do. Alternatively, when partial combustion is performed in the pretreatment device as in the seventh aspect of the invention, the waste combustion in the pretreatment device can be stabilized by using radiant heat.

  The invention of claim 5 is to supply combustible dust or combustible gas from the tuyeres at the bottom of the furnace. By combining these techniques, the amount of coke used can be further reduced.

  The invention of claim 6 is to fill the pyrolysis residue at a level of 0.5 m or more from the tuyere that is blowing. This makes it possible to suppress abnormal combustion due to the mixture of combustible gas, air and residue, stabilize the amount of exhaust gas, and make the equipment compact.

  Further, a waste is generated in the pretreatment device by providing a slit in a pusher provided in a step shape in the pretreatment device and blowing air, exhaust gas or oxygen-enriched air therefrom. Can be burned with stirring, and can be dried and pyrolyzed by the heat, so that waste can be uniformly dried and pyrolyzed, and clinker generation due to local high temperatures can be prevented. It becomes.

  According to a ninth aspect of the present invention, waste is dried and thermally decomposed by a pretreatment device using a part of waste heat, exhaust gas or reformed gas generated by combustion and melting of the waste. According to this method, the energy of the gas discharged from the melting furnace can be reused, and it is used for the amount of heat for drying and pyrolyzing the waste in the pretreatment device and for the combustion and melting of the waste. It is possible to further reduce the amount of external fuel used such as coke.

  In addition, since the pretreatment device is a kiln as described in claim 10, it is possible to reduce the amount of external fuel used by sufficiently stirring the waste in the pretreatment device and improving heat transfer. It becomes.

  According to the eleventh aspect of the present invention, auxiliary materials such as massive carbon-based combustible materials are supplied directly from the upper portion of the shaft furnace to the hearth without passing through the pretreatment device. By this method, auxiliary materials such as massive carbon-based combustible materials are not directly burned in the pretreatment device, but directly put into the hearth and only for the combustion and melting of the pyrolysis residue supplied from the pretreatment device. The amount of coke used can be reduced accordingly.

  The invention of claim 12 provides waste ash and non-combustible material in which waste and bulk 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, and melted from the outlet of the hearth part. In the waste melting treatment apparatus by the shaft furnace type waste melting furnace that discharges the hot water and discharges the generated gas from the upper part of the furnace, it was charged in the pretreatment device connected outside the shaft part of the shaft furnace type waste melting furnace. This is a waste melting treatment apparatus to which a pretreatment apparatus for drying and pyrolyzing waste to a moisture content of 30% or less or a volatile content of 30% or less and supplying the generated pyrolysis residue into the furnace is connected. The pyrolysis residue dried and pyrolyzed in the pretreatment device by this equipment is supplied to the hearth in a state where the temperature is raised to about 100 to 500 ° C., and is burned and melted. This makes it possible to maintain the hearth atmosphere temperature higher than in the case of reducing the amount of coke used. Moreover, since auxiliary materials such as coke are also preheated in the pretreatment device, it is possible to suppress a decrease in the atmospheric temperature of the hearth.

  Further, in the invention described in claim 13, a pretreatment device is connected so that a combustible gas generated by combustion and melting of pyrolysis residue and coke or its radiant heat can be used in the lower part of the shaft furnace. . The gas generated from the lower part of the furnace by the above apparatus can be used for drying and pyrolysis of waste in the pretreatment apparatus. As a result, it is possible to more efficiently dry and pyrolyze waste, suppress a decrease in the atmosphere temperature in the hearth, and reduce the amount of external fuel used such as coke.

  According to a fourteenth aspect of the present invention, an auxiliary material inlet is provided at the upper part of the shaft, and the auxiliary material inlet is directly supplied to the hearth part without going through the pretreatment device. By this equipment, co-materials such as coke are supplied directly to the hearth without burning in the pre-treatment device, so the coke that is supplied is used only for melting the pyrolysis residue supplied from the pre-treatment device. It is possible to reduce the amount of coke used.

  In addition, since the lower tuyere of the furnace is a tuyere that supplies combustible dust or combustible gas, the combustible dust or combustible gas can be used as a substitute for coke. The amount used can be reduced.

  Since the present invention removes moisture and volatile matter by separating drying / pyrolysis from combustion / melting in the pretreatment device, the ambient temperature that has been lowered by the moisture and volatile matter that has fallen to the bottom of the furnace without being removed conventionally. It is possible to reduce the amount of coke used to maintain

  In addition, the present invention performs thermal decomposition in a pretreatment device, and melts only the thermal decomposition residue, thereby reducing fluctuations in the amount of generated gas due to moisture drying and gasification of volatile matter in the packed bed. The amount of exhaust gas is stabilized.

It is the schematic which shows one Example of the waste fusion processing apparatus used in this invention. It is the schematic which shows another Example of the waste-melt-processing apparatus used in this invention. It is explanatory drawing of the conventional waste fusion processing equipment.

  The present invention will be described with reference to the drawings.

  In FIG. 1, the shaft furnace type waste melting furnace includes a shaft portion 1, a morning glory portion 2 connected to the shaft portion 1, and a hearth portion 3 below the morning glory portion 2, similar to the conventional one. The hearth part 3 is provided with a lower tuyere 4 for blowing air and oxygen as an oxygen source, and an upper tuyere 5 for blowing air from the morning glory part 2 to the lower end of the shaft part 1 is arranged.

  An exhaust gas outlet 6 for exhausting gas generated in the furnace is provided at the top of the furnace. Further, a secondary air inlet 7 for burning the pyrolysis gas generated in the furnace may be provided in the middle of the shaft portion 1.

  A pretreatment device 9 for drying and pyrolyzing waste is integrally connected to a pyrolysis residue inlet 8 formed in an intermediate portion of the shaft portion 1. The pyrolysis residue generated by drying and pyrolysis of waste (including ASR and the like) in the pretreatment device 9 is continuously dropped and supplied from the pyrolysis residue inlet 8 into the shaft portion 1 and filled.

  Waste is charged from a waste inlet 11 at the top of the pretreatment device 9, and auxiliary materials such as coke and limestone are charged from a secondary material inlet 14 at the top of the shaft.

  In the pretreatment device 9, the charged waste is heated by an ignition burner and then dried and thermally decomposed by self-combustion of the combustible material, waste heat, radiant heat, or the like. The waste is dried and pyrolyzed in the pretreatment device 9 to dry the moisture to 30% or less or the volatile content to 30% or less.

  In the shaft furnace, the temperature of the solid is raised by direct heat exchange in the packed bed, and the heat efficiency is good, but the waste is high in moisture, such as raw garbage, and volatile matter such as wood is large in diameter. Things exist. In a conventional shaft type gasification and melting furnace, a part of these wastes are lowered to the lowest part of the furnace without being sufficiently dried or gasified of volatile matter, and combusted and melted with coke. Since moisture and volatile matter in the lower part of the furnace both lower the atmospheric temperature, it is necessary to increase the amount of coke used as a result in order to maintain the atmospheric temperature high and completely melt the non-combustibles.

  By setting the moisture content to 30% or less or the volatile content to 30% or less in the pretreatment device, the remaining moisture and volatile content can be gasified by direct heat exchange in the packed bed below the shaft. Since the atmosphere temperature in the lower part of the furnace is not lowered and the blow-through phenomenon can be controlled, the amount of coke used can be reduced. Furthermore, by reducing the volatile matter in the pretreatment device, 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 way as in conventional furnaces, so coke must be used to maintain the atmospheric temperature, and coke is used. The amount cannot be reduced.

  In FIG. 1, a grate 10 is used as the pretreatment device 9. The waste introduced from the waste inlet 11 of the pretreatment device 9 is dried by the heat of self-combustion after being ignited by the ignition burner, and is thermally decomposed while being moved by the grate 10. The generated cracked gas is exhausted into the shaft portion 1 and exhausted as combustion or exhaust gas. In addition, it can replace with the grate 10 and the carbonization apparatus which generate | occur | produces a thermal decomposition residue by thermal decomposition, such as a carbonization kiln, can be utilized. In a dry distillation kiln, waste can be dried and pyrolyzed with a part of waste heat generated by waste treatment such as steam, exhaust gas, or a gas obtained by reforming generated gas.

  If the position of the pyrolysis residue inlet 8 to which the pretreatment device 9 is connected is 0.5 m or less where the pyrolysis residue is filled, the blown air and the residue mix to cause abnormal combustion, or the pyrolysis residue is scattered The amount may increase. Further, if the distance between the inlet and the air outlet (tuyere) is 10 m or more, the charged pyrolysis residue is scattered and the fluctuation of the amount of exhaust gas becomes large.

  The waste thrown into the pretreatment device 9 is dried by utilizing pyrolysis residue and gas generated by combustion of coke, heat generated by self-combustion or waste heat, and pyrolyzed by dry distillation. The generated pyrolysis residue falls from the pyrolysis residue inlet 8 into the shaft portion 1 and is filled. The upper part of the packed bed is about 650 ° C. in a CO atmosphere. The fallen pyrolysis residue is burned and melted and discharged from the tap 12 of the hearth part 3. The exhaust gas is exhausted from the exhaust gas outlet 6 at the top of the furnace, and heat is recovered. Auxiliary materials such as coke may be introduced together with the waste from the waste input port and preheated by the pretreatment device 9, but the auxiliary material is directly input from the auxiliary material input port 14 to the hearth. However, since the loss due to combustion in the pretreatment device is reduced, the effect of reducing the amount of coke used is great.

  By performing drying and pyrolysis in the pretreatment device, it is possible to reduce the amount of coke used conventionally other than ash melting. As a result of the test, it was confirmed that if only the carbonization residue was melted, it could be completely melted at a coke usage of 1% with respect to the waste. On the other hand, conventionally, the lower limit was 2% for waste treatment without pretreatment + gas blowing technology.

  In the conventional shaft furnace type waste melting furnace, drying, pyrolysis, combustion and melting are performed in one process, so fluctuations in the amount of steam and exhaust gas occur when charging waste or blowing through. Was.

  In the present invention, it is possible to suppress fluctuations in the amount of steam or exhaust gas accompanying gasification of volatile matter in the packed bed by reducing moisture and volatile matter by performing drying and thermal decomposition in the pretreatment. Become.

  In this invention, you may use together with the combustible dust tuyere blowing technique by the triple pipe tuyere described in Unexamined-Japanese-Patent No. 2005-098676. Furthermore, biomass coke may be used instead of the coke described in Patent Document 5. Moreover, you may use together the coke ratio reduction technique by the preheating of combustible dust tuyere blowing air.

  2, the same members as those in FIG. 1 are denoted by the same reference numerals, and the description thereof is omitted.

    The waste melting treatment apparatus shown in FIG. 2 uses gas and scattered dust combustion with the upper portion of the shaft portion 1 for melting the pyrolysis residue as a free board 13. In that case, the tuyere that sends the combustion air may not be in the pyrolysis residue packed bed. The freeboard 13 has an oxidizing atmosphere of 900 ° C. due to combustion of the generated combustion gas, and the radiant heat in the freeboard 13 can improve the efficiency of drying and thermal decomposition in the pretreatment device 9.

    The pyrolysis residue dropped and filled is burned and melted and discharged from the tap 12 of the hearth part 3. The exhaust gas is exhausted from the exhaust gas outlet 6 at the top of the furnace.

1: Shaft portion 2: Morning glory portion 3: Furnace floor portion 4: Lower tuyere 5: Upper tuyere 6: Exhaust gas outlet 7: Secondary air inlet 8: Pyrolysis residue inlet 9: Pretreatment device 10: Grate 11: Waste inlet 12: Outlet 13: Free board 14: Sub-material inlet 31: Waste melting furnace 32: Charger 33: Outlet 34: Tuyere 35: Flammable dust collector 36: Flammable Dust storage tank 37: Combustible dust cutting device

Claims (15)

  Waste and massive carbon-based combustible materials are supplied from the top of the furnace, oxygen source is supplied from the tuyeres at the bottom of the furnace, and molten ash and non-combustibles are discharged from the outlet of the hearth, and from the top of the furnace In the waste melting method using the shaft furnace type waste melting furnace for discharging the generated gas, the waste material charged in the pretreatment device connected outside the shaft portion of the shaft furnace type waste melting furnace has a moisture content of 30% or less. Alternatively, a waste melting method comprising drying and pyrolyzing to a volatile content of 30% or less, and supplying the generated pyrolysis residue into a furnace from a pretreatment device for melting.   2. The drying and pyrolysis of the waste charged in the pretreatment device is performed by using the thermal decomposition residue in the lower part of the furnace and the radiant heat of the combustible gas generated by the combustion and melting of the coke. The waste melting treatment method described.   The waste according to claim 1, wherein the combustible gas generated in the lower part of the furnace is partially burned in the upper part of the furnace, and the waste is dried and thermally decomposed in a pretreatment device using the radiant heat. Melt processing method.   The waste melting treatment method according to any one of claims 1 to 3, wherein the thermal decomposition residue is continuously supplied from the pretreatment device into the shaft portion.   The waste melting method according to any one of claims 1 to 4, wherein combustible dust or combustible gas is supplied from the tuyeres at the bottom of the furnace.    The waste melting treatment method according to any one of claims 1 to 5, wherein the pyrolysis residue is filled at a level of 0.5 m or more from the blowing tuyere.   The waste melting method according to any one of claims 1 to 6, wherein the waste is directly dried and thermally decomposed by the pretreatment device by partially burning the waste with the pretreatment device.   The waste melting method according to claim 7, wherein a slit is provided in a pusher provided in a step shape in the pretreatment device, and air, exhaust gas, or oxygen-enriched air is blown from the slit.   The waste heat generated by combustion / melting of the waste, exhaust gas, or part of the reformed gas is used to dry and pyrolyze the waste in a pretreatment device. The waste melting method of crab.   The waste melting method according to claim 9, wherein the pretreatment device is a kiln.   The waste melting treatment method according to any one of claims 1 to 10, wherein auxiliary materials such as a massive carbon-based combustible material are supplied directly from the upper portion of the shaft furnace to the hearth without passing through the pretreatment device. .   Waste and massive carbon-based combustible materials are supplied from the top of the furnace, oxygen source is supplied from the tuyeres at the bottom of the furnace, and molten ash and non-combustibles are discharged from the outlet of the hearth, and from the top of the furnace Outside the shaft part of the shaft furnace type waste melting furnace that discharges the generated gas, the charged waste is dried and pyrolyzed to a moisture of 30% or less or a volatile content of 30% or less, and the generated pyrolysis residue is furnace A waste melting treatment apparatus characterized by being connected to a pretreatment apparatus to be supplied inside.   The disposal according to claim 12, wherein a pretreatment device is connected so that combustible gas generated by combustion and melting of pyrolysis residue and coke or radiant heat thereof can be used in a lower portion of the shaft furnace. Material melting processing equipment.   The waste melting apparatus according to claim 12 or 13, wherein an auxiliary material inlet for supplying auxiliary material such as massive carbon-based combustible material directly to the hearth is provided at the upper part of the shaft furnace.   The waste melting apparatus according to any one of claims 12 to 14, wherein the tuyere at the lower part of the furnace is a tuyere supplying flammable dust or flammable gas.

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