JP5180917B2 - Waste melting treatment method and waste melting treatment apparatus - Google Patents

Description

  The present invention relates to a waste melting treatment technique for reducing the amount of coke used by drying and thermally decomposing waste and melting only pyrolysis residues from which moisture and volatile components in the waste have been removed.

  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 tuyere provided in the furnace body Blasting air is blown, and the waste is dried, pyrolyzed, burned, and melted to melt the waste.

  In FIG. 2, in the shaft furnace type waste melting furnace 31, the waste is charged together with auxiliary materials such as coke and limestone by a 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 pyrolyzed and discharged as gas, and some are combusted by air and oxygen blown from the tuyere 34 at the bottom of the furnace, while the remaining combustibles are combustible. It is discharged from the furnace top of the melting furnace 31 as a property 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, from the viewpoint of preventing global warming, coke derived from fossil fuels is used as a melting heat source, so that reduction of coke usage is also desired 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) obtained 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) A waste-melting method (Patent Document 3) in which waste is melted by reducing and burning with air and inductively heating the coke with an alternating current, or biomass such as wood And a method of use (Patent Document 4) have been proposed.

  In Patent Document 5, the residue containing unburned carbon generated in the stoker group is melted by the combustion heat of the unburned carbon, and resource is recycled by reforming the main ash without increasing the temperature of the stoker furnace. Is disclosed. This technology is intended to prevent the main ash and fly ash from being melted and fixed due to the high temperature of the stoker, and to improve the decrease in thermal efficiency due to the heat loss caused by cooling of the pyrolysis residue melting part. Stable gasification is achieved by partial combustion at a low temperature.

JP 2006-207911 A JP 2003-056820 A JP 2002-054810 A JP 2007-93069 A JP 2003-166705 A

  In the packed bed in the shaft furnace, the temperature of the solid is raised by direct heat exchange, and the heat efficiency is good, but the waste contains a large amount of volatile components such as high-waste garbage such as garbage and wood, and a large diameter Exists. In conventional shaft type gasification and melting furnaces, some of these wastes are not sufficiently dried or gasified in the volatile matter, so they descend 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 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 when waste is charged or when undried or 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.

  Further, in the stoker furnace of Patent Document 6, (1) the combustion exhaust gas passage in the drying / pyrolysis zone and the exhaust gas treatment zone from the residue treatment zone are individually separated, and the equipment cost is high. (2) the combustion exhaust gas passage Since the gas generated by the partial combustion in the stoker cannot be effectively used because the waste inlet is separated from the waste inlet, the drying means and the combustion means are used to partially burn the high-moisture waste in the stoker part. As a result, it was huge.

  Therefore, in the present invention, in the waste melting treatment, drying and thermal decomposition are performed in the drying shaft portion and the grate portion, and moisture and volatile matter in the waste are removed by performing separation from combustion and melting, By preventing the waste from descending to the bottom of the furnace without being dried or pyrolyzed, the temperature of the atmosphere at the bottom of the furnace is prevented from lowering, and the amount of coke consumed that exceeds the amount necessary for melting ash is reduced. The present invention provides a waste melting treatment technique capable of achieving complete melting with the heat quantity of the waste pyrolysis residue and the heat quantity of a small amount of coke, and stabilizing the exhaust gas quantity and the steam quantity.

  The waste melting treatment method of the present invention supplies waste and 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, and melts ash in the waste melted from the outlet of the hearth part and In a waste melting treatment method using a shaft furnace type waste melting furnace that discharges non-combusted water and discharges generated gas from the upper part of the furnace, the drying shaft part for drying the waste and the waste dried by the drying shaft part A grate part that pyrolyzes to produce a pyrolysis residue is connected to the upper part of the melting furnace, and waste that is charged by filling the drying shaft part from the top of the furnace is generated in the grate part and the melting furnace. The gas is dried and pyrolyzed with gas, and the gas that has passed through the waste packed bed is discharged from the top, and dried and pyrolyzed at the drying shaft, and further pyrolyzed at the grate to produce a pyrolysis residue And supplying the pyrolysis residue to a melting furnace. Characterized by combustion and melting the coke bed as a heat source to. By this method, it becomes possible to separate and dry waste / pyrolysis and combustion / melting. As a result, moisture or volatile matter in the waste is not brought into the melting furnace floor where the coke bed is formed, so it is possible to suppress the endothermic reaction accompanying moisture evaporation and gasification of the volatile matter, The atmosphere temperature in the hearth can be kept high.

  The invention of claim 2 is for drying and pyrolyzing the waste material charged in the drying shaft portion and the grate portion to a moisture content of 30% or less or a volatile content of 30% or less. Using this method, the heat absorption near the coke bed in the hearth can be controlled by controlling the heat absorption associated with gasification and gasification of the volatile matter. The amount can be reduced.

  According to the third aspect of the present invention, drying and pyrolysis can be performed more efficiently by supplying an oxygen source from the drying shaft tuyere or the grate unit and partially burning the waste.

  Further, as in the invention of claim 4, by thermally decomposing at an air ratio of 1.0 or less in the grate portion, the fixed carbon and volatile matter in the waste are removed from the hearth portion without completely burning the waste. It can be used as a combustion source in

  According to the invention of claim 5, the pyrolysis residue generated in the grate portion is continuously supplied to the pyrolysis residue melting portion. By the above method, it is possible to stably perform combustion and melting of the pyrolysis residue in the pyrolysis residue melting portion.

  Moreover, by supplying the pyrolysis residue produced | generated in the stoker part to the pyrolysis residue fusion | melting part to the level of 0.5 m or more from the tuyere which blows like 6th aspect, combustible gas, air, and residue Therefore, it is possible to suppress abnormal combustion due to mixing, stabilize the amount of exhaust gas, and make the equipment compact.

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

  The invention of claim 8 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 9 is characterized in that waste and 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, and molten ash and non-combustibles are melted from the outlet of the hearth part. The shaft part for drying and pyrolyzing the waste in the shaft furnace type waste melting furnace that discharges the generated gas from the furnace top, and the waste that has been dried and pyrolyzed in the drying shaft part is further pyrolyzed And a grate part for generating a pyrolysis residue is connected to the upper part of the shaft furnace type melting furnace. With this device, the pyrolysis residue dried and pyrolyzed at the drying shaft and grate can be supplied directly to the hearth, so the atmospheric temperature drop due to moisture evaporation and gasification of volatile matter is suppressed, The atmospheric temperature can be maintained high, and the amount of coke used can be further reduced.

  Further, according to the tenth aspect, the top portion of the drying shaft portion is provided with a waste charging inlet and an exhaust gas outlet, and the waste filling layer is dried and thermally decomposed by passing the gas through and discharged from the top.

  Moreover, it becomes possible to supply auxiliary materials, such as coke, directly to a hearth part by installing the supply port of auxiliary materials, such as a waste material and a massive carbonaceous combustible material, in the upper part of a melting furnace like Claim 11, Loss due to combustion or the like in the drying shaft and the grate portion can be eliminated. As a result, the amount of coke used can be further reduced.

  In addition, by using the tuyere according to claim 12, it becomes possible to dry and thermally decompose waste more efficiently.

  In the present invention, by providing a grate between the shaft and the bottom of the furnace, drying and pyrolysis are separated from combustion and melting to remove moisture and volatile components. It is possible to reduce the amount of coke that has been used to maintain the ambient temperature that has been reduced by minutes.

  Further, the present invention performs pyrolysis by providing a grate between the shaft and the bottom of the furnace, and melts only the pyrolysis residue to reduce the amount of gas generated by drying of moisture and gasification of volatile matter in the packed bed. Fluctuations are reduced and the amount of steam or exhaust gas can be stabilized.

It is the schematic which shows one Example of the waste-melting processing apparatus provided with the grate 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, a waste melting treatment apparatus of the present invention includes a drying shaft portion 1 for drying charged waste, a grate portion 2 for thermally decomposing the dried waste to generate a pyrolysis residue, It comprises a pyrolysis residue melting portion 3 for burning and melting the pyrolysis residue. 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 6 on the morning glory part 5. The hearth part 4 includes a lower tuyere 7 for blowing air and oxygen as an oxygen source, and an upper tuyere 8 for blowing air from the morning glory part 5 to the lower end part of the shaft part 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 shaft portion may not be provided.

  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 supply device may be a pusher or a grate.

  The grate part 2 includes a grate 13 that moves the waste charged from the drying shaft part 1 to the pyrolysis residue melting part 3 while thermally decomposing the waste.

  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.

  Waste (including ASR) is dried and pyrolyzed by the drying shaft 1 and the grate 2 and the generated pyrolysis residue falls into the shaft 6 from the exit side of the grate 2 and is supplied. Filled.

  After the waste charged in the grate part 2 is ignited by the burner 16 for heating, it is dried and thermally decomposed by self-combustion of combustibles or radiation of gas generated in the hearth part, and moisture is 30% or less. Alternatively, the volatile content is dried to 30% or less.

  In a conventional shaft furnace type gasification melting furnace, the temperature of solids is raised by direct heat exchange in the packed bed, and the heat exchange rate is good, but in the waste, high moisture waste such as garbage, wood Some of them have many volatile components such as large diameters. In conventional shaft furnace type gasification and melting furnaces, some of these wastes are lowered to the bottom of the furnace without being fully dried or gasified, and burned 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 providing a grate between the drying shaft and the bottom of the furnace, the moisture content is reduced to 30% or less or the volatile content to 30% or less. As a result, the atmosphere temperature in the lower part of the furnace is not lowered, and the blow-through phenomenon can be suppressed, so that the amount of coke used can be reduced. Furthermore, by providing a grate between the shaft and the bottom of the furnace, it is possible to reduce fluctuations in the exhaust gas and the amount of steam accompanying gasification of the volatile matter in the packed bed by reducing the volatile matter.

  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.

  When the position of the exit side of the grate part 2 is 0.5 m or less that fills the pyrolysis residue, the blown air and the residue may be mixed to cause abnormal combustion, or the amount of pyrolysis residue scattered may increase. There is sex. Moreover, if the distance between the outlet side to be introduced and the tuyere is 10 m or more, the charged pyrolysis residue is scattered and the fluctuation of the exhaust gas amount becomes large.

  The waste thrown into the drying shaft portion 1 is dried by heat generated by partial combustion in the grate portion 2 and gas generated from the bottom of the furnace, and thermally decomposed in the grate portion 2. The generated thermal decomposition residue falls into the thermal decomposition residue melting part 3 and is filled. The air ratio in the grate part 2 is set to 1.0 or less, and only the pyrolysis residue that has been dried and pyrolyzed is melted. When the air ratio exceeds 1.0, only the ash is supplied to the hearth, and the combustible residue of the pyrolysis residue cannot be used to maintain the furnace floor atmosphere temperature, reducing the amount of coke used. Can not do it. Considering stable partial combustion, the air ratio is preferably 0.1 to 0.8 if possible. The upper part of the packed bed is about 600 ° C. in a CO atmosphere. The fallen pyrolysis residue is combusted and melted and discharged from the tap 14 of the hearth. The exhaust gas is exhausted from the exhaust gas outlet 9 of the drying shaft portion 1 and then recovered. When the air ratio is 0.1 or less, the waste in the grate cannot be self-combusted, and external fuel is supplied to the melting furnace without being necessary or dried and dry distilled, and an extra amount of coke is required. The air temperature is a room temperature of 30 ° C. to 40 ° C. or preheated air.

  By using the drying shaft part 1 and the grate part 2 for drying and pyrolysis more efficiently than the conventional shaft furnace type waste melting furnace, it is possible to reduce the amount of coke used other than the conventional ash melting it can. As a result, it was sufficient to fill the pyrolysis residue melting portion 3 with only the amount of heat necessary for melting only the dried and pyrolyzed pyrolysis residue. As a result of the test, it was confirmed that if only the pyrolysis 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.

  The blow-through 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 at 1 and the grate portion 2, it is possible to stabilize the amount of exhaust gas and prevent blow-through.

  Unlike the stoker furnace of the cited document 5, there is a drying shaft portion 1 above the grate portion 2, and the gas generated from the grate portion 2 and the pyrolysis residue melting portion 3 is filled in the drying shaft portion 1. Efficient drying and pyrolysis can be performed by exchanging heat with waste.

  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, in the present invention, biomass coke described in Patent Document 4 may be used as coke.

1: Drying shaft part 2: Grate part 3: Pyrolysis residue melting part 4: Hearth part 5: Morning glory part 6: Shaft part 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: Temperature rising burner 17: Drying shaft tuyere

Claims (12)

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 treatment method by the shaft furnace type waste melting furnace that discharges the generated gas,
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. Waste that has been charged from the inside is dried and pyrolyzed by the gas generated in the grate and melting furnace, and the gas that passed through the waste packed bed is discharged from the top, dried at the drying shaft, and pyrolyzed A waste melting process characterized by further pyrolyzing the generated waste in a grate part to produce a pyrolysis residue, supplying the pyrolysis residue to a melting furnace, and burning and melting using a coke bed as a heat source Method.   2. The waste melting method according to claim 1, wherein the waste charged in the drying shaft portion and the grate portion is dried and thermally decomposed to a moisture content of 30% or less or a volatile content of 30% or less.   3. The waste is partially burned by an oxygen source supplied from a tuyere or grate provided on a drying shaft, and the waste is dried and pyrolyzed by the heat source. Waste melting treatment method.   The waste melting treatment method according to any one of claims 1 to 3, wherein a pyrolysis residue obtained by pyrolysis is melted at an air ratio of 1.0 or less in the grate portion.   The waste melting treatment method according to any one of claims 1 to 4, wherein the thermal decomposition residue generated in the grate portion is continuously supplied to the thermal decomposition residue melting portion.   The waste according to any one of claims 1 to 5, wherein the pyrolysis residue generated in the grate part is supplied to the pyrolysis residue melting part at a level of 0.5 m or more from the tuyere that is blowing air. Melt processing method.   The auxiliary material such as a massive carbon-based combustible material is supplied directly from the upper part of the shaft furnace to the hearth part without passing through the drying shaft part and the grate part. Waste melting treatment method.   The waste melting method according to any one of claims 1 to 7, wherein combustible dust or combustible gas is supplied from the tuyere.   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 A shaft part for drying waste in a shaft furnace type waste melting furnace for discharging generated gas, and a grate for generating pyrolysis residue by further thermally decomposing waste dried and pyrolyzed in the drying shaft part A waste melting apparatus characterized in that a portion is connected to an upper portion of the shaft furnace type melting furnace.   The waste melting apparatus according to claim 9, wherein a top of the drying shaft portion is provided with a waste inlet and an exhaust gas outlet.   11. The waste melting apparatus according to claim 9, wherein a supply port for auxiliary materials such as waste and massive carbon-based combustible material is installed in the upper part of the melting furnace.   The waste melting apparatus according to any one of claims 9 to 11, wherein a tuyere is provided in the drying shaft portion.

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