JP5180899B2 - Waste melting treatment method and waste melting treatment apparatus - Google Patents

Description

  The present invention relates to a waste melting process for drying and pyrolyzing waste and melting only the pyrolysis residue from which moisture and volatile components in the waste have been removed, and in particular, the pyrolysis residue connected to the upper part of the melting furnace. The present invention relates to treatment of ash falling from a grate of a grate portion to be generated.

  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 Wastes are 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 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 a lot of high-moisture waste such as raw garbage and volatile matter such as wood. Some have a large diameter. In conventional shaft 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 volatile matter. Melt. 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 charging waste or when undried / undried waste falls to the bottom of the furnace. Fluctuations 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. While achieving complete melting, the amount of exhaust gas and the amount of steam can be stabilized (Patent Document 5).

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

  In FIG. 2, 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 on 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 7 for blowing air and oxygen as an oxygen source, and an upper tuyere 8 for blowing air toward the lower end of the morning glory part 5 is arranged. 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 fed from the auxiliary material inlet 15 at the top of the melting furnace 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 pyrolysis residue melting part 3 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 4. Efficient drying and pyrolysis are performed by exchanging heat through the material. The pyrolysis residue produced by the drying / pyrolysis falls to the pyrolysis residue melting part 3 and is burned and melted by the heat source of the coke bed, and is discharged from the tap 14 of the hearth part 4. 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 apparatus of Patent Document 5, ash falls from the grate part, although a small amount. Usually, in a stoker-type incinerator, the blower hopper is either water-sealed in a water-sealed pit and discharged together with main ash, or connected to an ash treatment conveyor by a double damper or the like. In any case, the ash dropped from the grate is finally disposed of as fly ash or main ash. Furthermore, in order to process the ash, processing and transport facilities such as a conveyor and a water seal pit are required.

  Accordingly, the present invention provides a waste melting method and waste that can melt ash falling from the grate of the grate portion of the waste melting processing apparatus with a simplified facility and minimize the final disposal amount. A melt processing apparatus is provided.

  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 the waste melting treatment method using a melting furnace for removing hot water, the melting shaft includes a drying shaft portion for drying the waste and a grate portion for thermally decomposing the waste dried by the drying shaft portion to generate a pyrolysis residue. The waste is dried and pyrolyzed by passing the gas generated in the grate part and the melting furnace through the waste packed bed formed by charging from the top of the furnace into the drying shaft part. The gas that has passed through the waste packed bed is discharged from the top of the drying shaft portion, and the waste that has been dried and pyrolyzed at the drying shaft portion is further pyrolyzed at the grate portion to produce a pyrolysis residue, Supplying pyrolysis residue to bottom of melting furnace Upper and lower that can be opened and closed by an ash transport device located at the bottom of the blower hopper at the bottom of the grate to burn and melt the combustible material and the pyrolysis residue as a heat source It is a waste melting method characterized in that it is transported to and stored in an ash storage hopper provided with a damper and a lower damper, and is directly charged into the melting furnace from the ash storage hopper after storage.

  According to the second aspect of the present invention, after the accumulated ash is stored in the ash storage hopper, the upper damper is opened slightly, the purge gas is supplied into the ash storage hopper, and the remaining air in the ash storage hopper is driven out to the blower hopper side. The waste melting treatment method according to claim 1, wherein:

  According to the invention of claim 3, ash is introduced from the ash storage hopper into the melting furnace with the upper damper closed, then the lower damper is closed, the inside of the ash storage hopper is purged with a purge gas, and the purged exhaust gas is discharged. The waste melting method according to claim 1 or 2, wherein the gas is introduced into a combustion chamber installed at a subsequent stage of the shaft furnace type melting furnace.

  The invention of claim 4 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 melt 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 ash transport device for transporting ash dropped from the grate is provided at the bottom of the blow hopper below the grate of the grate portion, and an ash storage hopper for storing the ash transported to the transport outlet of the ash transport device is provided. The waste melting processing apparatus is provided with an upper damper and a lower damper that can be opened and closed above and below the ash storage hopper.

  The invention according to claim 5 is the waste melting apparatus according to claim 4, wherein the ash conveying device is a scraper conveyor.

  The invention according to claim 6 is the waste melting treatment apparatus according to claim 4, wherein the ash conveying device is a screw conveyor.

  A seventh aspect of the present invention is the waste melting treatment apparatus according to the fourth aspect, wherein the ash conveying device is a vibration feeder.

  The invention according to claim 8 is the waste melting apparatus according to claim 4, wherein the ash conveying device is a pusher.

  The invention of claim 9 includes a purge gas injection pipe for injecting a purge gas into the ash storage hopper, and a purge exhaust gas pipe for introducing the purged exhaust gas into the combustion chamber installed at the rear stage of the shaft furnace type melting furnace. It is connected, It is a waste melting processing apparatus in any one of Claims 4-8 characterized by the above-mentioned.

  According to the present invention, the ash falling from the grate during operation is fed into the melting furnace via the ash storage hopper by the ash transport device, so that the equipment for discharging the ash can be simplified.

According to the present invention, the ash dropped from the grate can be put into a melting furnace and melted to be reused as slag, and the final disposal amount can be minimized. Further, the combination of the conveyor and the double damper can prevent detonation due to mixing of the oxidizing atmosphere (O ₂ ) of the blowing hopper below the grate and the reducing atmosphere (CO) of the melting furnace.

Further, unless purged in ash retention hopper with an inert gas such as N _2, air in the ash storage hopper is supplied to the melting furnace, it is conceivable to cause detonation, in the present invention, N ₂ Explosion can be prevented by purging the remaining air in the hopper by purging with.

Also, the inside of the ash storage hopper after ash charging is filled with CO gas, and detonation may occur if purge is not performed, but the purged CO gas is purged with N ₂ and the purged CO gas is removed from the combustion chamber. It is possible to prevent detonation and to supply ash to the melting furnace and stably melt it without changing the gas flow in the melting furnace or the atmospheric temperature caused by the purge exhaust gas.

It is the schematic of the waste melting processing apparatus of this invention. It is the schematic of the waste melting processing apparatus of patent document 5. FIG.

  The waste melting treatment apparatus of the present invention shown in FIG. 1 is the same as the waste melting treatment apparatus shown in FIG. 2 except for the structure of the ash treatment part dropped on the grate. The same reference numerals are given.

  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 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 drying shaft portion 1 is provided with a drying shaft portion tuyere 17 for blowing combustion air.

  The pyrolysis residue melting part 3 includes a lower hearth part 4 and a morning glory part 5 connected to the hearth part 4. 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 to the lower end of the morning glory part 5. 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 charged from the auxiliary material inlet 15 (FIG. 2) at the top of the melting furnace 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 known grate furnace grate, an inclined grate that slides back and forth is arranged in a staircase pattern.

  In the present invention, an ash transport device 19 for transporting ash is disposed at the bottom of the blower hopper 18 where ash falls from the grate 13. A scraper conveyor, a screw conveyor, a vibration feeder, a pusher, or the like can be used for the ash transport device 19. For example, in the scraper type, since the width of the scraper can be increased, it is not necessary to reduce the width of the bottom portion of the blower hopper 18 so that the height of the blower hopper 18 need not be increased. In the screw conveyor, the blower hopper must be narrowed down to the width of the screw conveyor, so that the height of the hopper is increased from the angle of repose, and the height of the waste melting treatment apparatus must be increased. However, facilities such as a water cooling structure are simple. In addition, the pusher has a long grate portion, the size of the equipment is increased, and further measures for equipment against thermal expansion are required, but the discharge performance is high. In this way, it is necessary to select an optimum ash transport device depending on the equipment.

  An ash storage hopper 20 for temporarily storing the pyrolysis residue waste to be put into the pyrolysis residue melting portion is continuously provided on the carry-out side of the conveyor 19 of the pyrolysis residue melting portion 3. The ash storage hopper 20 includes an upper damper 21 that can be opened and closed on the upper side where the ash conveyed by the conveyor 19 is charged, and a lower damper 22 that can be opened and closed on the lower side, and is partitioned from the blower hopper 18 by the upper damper 21. The inside of the pyrolysis residue melting part 6 is partitioned by the lower damper 22.

Connected to the ash storage hopper 20 is a purge gas blowing pipe 23 for blowing a purge gas such as N ₂ that purges the gas in the ash storage hopper 20, and exhaust gas (purge gas, CO) purged by an inert gas purge. A purge exhaust gas pipe 24 to be introduced into the combustion chamber installed in the subsequent stage is connected.

  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 and pyrolysis are performed by exchanging heat through the waste. The pyrolysis residue generated by drying and pyrolysis falls into the shaft portion 6, is burned and melted by the heat source of the coke bed, and is discharged from the tap 14 of the hearth portion 3.

  The waste is dried and pyrolyzed by the drying shaft portion 1 and the grate portion 2, and the generated pyrolysis residue falls into the melting furnace 6 from the exit side of the grate portion 2 and is supplied and filled.

    After the waste charged in the grate part 2 is ignited by the burner 16, it is dried and pyrolyzed by self-combustion of combustibles or radiation of gas generated in the hearth, and the moisture is 30% or less or volatile matter Is dried to 30% or less. By providing a grate 13 between the drying shaft portion 1 and the pyrolysis residue melting portion 3, the moisture content is reduced to 30% or less or the volatile content is reduced to 30% or less, so that the remaining moisture and volatile content are filled in the lower layer of the shaft. It becomes possible to gasify by direct heat exchange at. As a result, since the atmospheric temperature in the lower part of the furnace is not lowered and the blow-through phenomenon can be suppressed, the amount of coke used can be reduced. Furthermore, since the volatile matter can be reduced by providing the grate 13, it becomes possible to suppress fluctuations in the exhaust gas and the amount of steam accompanying the gasification of the volatile matter in the packed bed. In addition, when the water content exceeds 30% or the volatile content exceeds 30%, the atmospheric temperature in the lower part of the furnace decreases in the same manner as in the conventional furnace, so coke must be used to maintain the atmospheric temperature, 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 packed bed of pyrolysis residue, the blown air and the pyrolysis residue are mixed to cause abnormal combustion or increase in the amount of pyrolysis residue scattering There is a possibility of doing. 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 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.

  In the present invention, when the ash that has fallen from the grate 13 is stored in the ash storage hopper 20, the upper damper 21 is opened as indicated by a broken line and the conveyor 19 is closed with the lower damper 22 closed as indicated by a broken line. The ash that is driven to fall from the grate 13 is transported and put into the ash storage hopper 20 for storage.

When a predetermined amount of ash is stored in the ash storage hopper 20, the conveyor 19 is stopped, and N ₂ is purged from the inert gas blowing pipe 23 to the ash storage hopper 20 with the upper damper 20 opened slightly. Residual air in the ash storage hopper is expelled to the blower hopper 18. Thereby, it is possible to prevent detonation by preventing the residual air in the hopper from flowing into the pyrolysis residue melting part 3.

After purging N ₂ , the upper damper 21 is closed as indicated by the solid line, and the lower damper 22 is opened as indicated by the solid line, and the ash in the ash storage hopper is charged into the melting furnace and melted.

After the ash is charged, the lower damper 22 is closed, the opening / closing valve of the inert gas blowing pipe 23 is opened, N ₂ is purged into the ash storage hopper 20, and the purged exhaust gas is passed through the purge exhaust gas pipe 24 to the combustion chamber. Introduce. After purging, close the on-off valve.

  When the purge is completed, the upper damper 22 is opened, and the above operation is repeated to transport and store the ash. It is possible to exhaust the purge exhaust gas to the melting furnace in the same way as when storing the ash in the ash storage hopper, but the exhaust gas from the storage hopper affects the gas flow in the melting furnace and the ambient temperature and is stable. May not be able to melt.

However, when the melting furnace is small and the purge gas in the ash storage hopper greatly affects the flammability in the grate, or when the melting furnace is large and the influence of the purge gas in the melting furnace is negligible Open the upper damper and accept the ash into the ash storage hopper, then close the upper damper and open the open / close valve of the inert gas blowing pipe 23 to purge N ₂ into the ash storage hopper and remove the purged exhaust gas A method of introducing the gas into the combustion chamber through the purge exhaust gas pipe 24 may be adopted. In this case, the after charged with ash to the melting furnace, once after it closed lower damper 22, the N ₂ while the slightly open from the inert gas purging pipe 23 to purge the ash storage hopper 20 ash storage hopper The CO gas inside is expelled to the melting furnace. Thereby, it is possible to prevent detonation by preventing the CO gas in the hopper from flowing into the blower hopper 18.

1: Drying shaft part 2: Stoker 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 inlet 11: Sealing lid 12: Waste supply device 13: Grate 14: Outlet 15: Sub-material inlet 16: Burner 17: Drying shaft tuyere 18: Blower hopper 19: Ash transport device (conveyor) 20: Ash storage hopper 21: Upper damper 22: Lower damper 23: Purge gas injection pipe 24: Purge exhaust gas pipe

Claims (9)

Waste from a 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 at the hearth In the melt processing method,
A drying shaft portion for drying waste and a grate portion for thermally decomposing the waste dried by the drying shaft portion to generate a pyrolysis residue are connected to the upper part of the melting furnace, and the furnace is connected to the drying shaft portion. Waste is dried and pyrolyzed by passing the gas generated in the grate and melting furnace through the waste packed bed formed from the top, and the gas that has passed through the waste packed bed is for drying. Waste discharged from the top of the shaft part, dried and pyrolyzed at the drying shaft part is further pyrolyzed at the grate part to produce a pyrolysis residue, and the pyrolysis residue is supplied to the bottom of the melting furnace. Burning and melting the massive carbon combustible substance and the pyrolysis residue as a heat source,
The ash dropped from the grate of the grate part is transported and stored in an ash storage hopper equipped with an upper damper and a lower damper that can be opened and closed vertically by an ash carrier arranged at the bottom of the blower hopper below the grate. A waste melting treatment method characterized in that, after storage, the ash storage hopper is directly charged into a melting furnace.   The accumulated ash is stored in the ash storage hopper, and then the upper damper is opened slightly to supply a purge gas into the ash storage hopper to expel residual air in the ash storage hopper to the blower hopper side. The waste melting method according to 1.   After the ash from the ash storage hopper is put into the melting furnace with the upper damper closed, the lower damper is closed, the inside of the ash storage hopper is purged with the purge gas, and the purged exhaust gas is removed from the shaft furnace type melting furnace. The waste melting method according to claim 1, wherein the waste melting method is introduced into a combustion chamber installed at a subsequent stage. 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 ash transport device for transporting ash dropped from the grate is provided at the bottom of the blower hopper below the grate of the grate,
An ash storage hopper for storing the ash transported to the transport outlet of the ash transport device is provided,
A waste melting treatment apparatus, comprising an upper damper and a lower damper that can be opened and closed above and below an ash storage hopper.   The waste melting apparatus according to claim 4, wherein the ash conveying device is a scraper conveyor.   5. The waste melting apparatus according to claim 4, wherein the ash conveying device is a screw conveyor.   5. The waste melting apparatus according to claim 4, wherein the ash conveying device is a vibration feeder.   The waste melting apparatus according to claim 4, wherein the ash conveying device is a pusher.   A purge gas injection pipe for injecting purge gas into the ash storage hopper and a purge exhaust gas pipe for introducing the purged exhaust gas into the combustion chamber installed at the rear stage of the shaft furnace type melting furnace are connected. A waste melting apparatus according to any one of claims 4 to 8.

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