JP5945929B2 - Waste gasification and melting equipment - Google Patents

Description

  The present invention relates to a vertical waste gasification and melting apparatus for pyrolyzing and gasifying waste and melting a pyrolysis residue.

  As a technology for treating waste such as municipal waste and shredder dust, gasification melting processing is known in which waste is pyrolyzed and gasified to generate flammable gas, and the pyrolysis residue is melted and discharged as slag. Yes.

  In this treatment method, the heat of combustion can be recovered by pyrolyzing and gasifying the waste, and after the residue is melted and discharged as slag, the amount to be finally disposed of in landfill disposal etc. It has the advantage that the volume can be reduced. There are several types of melting furnaces for performing such treatment, and one of them is a shaft type waste gasification melting furnace having a vertical shape.

  In this shaft-type waste gasification and melting furnace, for example, coke as fuel deposited at the bottom of the furnace is burned, and waste is put on the high-temperature coke, and pyrolyzed and partially oxidized to be gasified. At the same time, it is a furnace that performs a process of melting the residue into slag (see Patent Document 1).

  In the shaft-type waste gasification and melting furnace of Patent Document 1, the functions of the furnace body having a vertical cylindrical shape are roughly divided into three regions in the vertical (up and down) direction. That is, a high-temperature combustion zone having a coke bed in which coke is deposited at the bottom of the furnace is formed, a waste layer is formed on the high-temperature combustion zone, and a large space above the waste layer is formed above the furnace body. The free board part is made.

  In such a melting furnace, oxygen-containing gas is blown into the furnace in each of the three regions. The main combustion tuyeres are provided in the high-temperature combustion zone, and oxygen-enriched air is blown to obtain a melting heat source that burns the coke in the coke bed that has been charged and deposited to melt the pyrolysis residue of the waste. It is. In addition, the waste layer is provided with a sub tuyere, and air is blown to cause the waste deposited and flowed gently, and to thermally decompose and partially oxidize the waste. In addition, the free board part is provided with a third stage tuyere to partially burn part of the pyrolysis gas (combustible gas) generated by pyrolyzing waste and maintaining the inside at a predetermined temperature Air is blown.

  As described above, the shaft-type waste gasification and melting furnace is a facility capable of performing both pyrolysis gasification treatment and melting treatment in a single furnace as the waste falls in the furnace. The input waste is pyrolyzed to produce gas and residue. The coke in the coke floor is combusted by blowing oxygen-enriched air from the main tuyere to form a high-temperature combustion zone, and the pyrolysis residue of the waste is melted and discharged as slag and metal. The high-temperature gas generated by coke combustion in the high-temperature combustion zone heats the waste in the waste layer formed on the high-temperature combustion zone, and the waste is thermally decomposed by blowing air from the sub tuyere. The gas containing the combustible gas generated by the gas rises in the waste layer, and is discharged to the secondary combustion chamber outside the furnace from the exhaust flue provided in the upper part of the furnace through the free board part. The gas contains a large amount of combustible gas and is combusted in the secondary combustion chamber, and heat is recovered by the boiler to generate steam, which is used for power generation and the like. Exhaust gas treatment such as removing relatively coarse dust with a cyclone, cooling with a temperature reducing device, removing acid gas by reaction with an acid gas neutralizer, and removing dust with a dust collector And then released from the chimney to the atmosphere.

  In such a waste gasification and melting furnace, a coke bed in which coke is deposited at the bottom of the furnace is formed, and the coke burns to become a heat source for melting pyrolysis residues. Recently, coke derived from fossil fuels has been used. There is a demand to reduce the amount of carbon dioxide emission by reducing the amount and to reduce the operating cost of the waste melting furnace. On the other hand, as a whole, including the growth process of living organisms, by using massive biomass, which is organic resources derived from living organisms such as charcoal and charcoal obtained by heat-compressing sawdust from building waste as a substitute for coke, carbonized A waste melting method has been proposed in which the amount of carbon dioxide emission is reduced by an amount corresponding to a reduction in the amount of coke used without increasing carbon dioxide in the atmosphere (see Patent Document 2).

JP 09-060830 A JP-A-2005-249310

  In order to reduce the amount of carbon dioxide emitted and reduce the operating cost of the waste melting furnace, in order to reduce the amount of coke used as fuel in the waste melting furnace, a block biomass as an alternative to coke as in Patent Document 2 Even if purchased and used, the bulk biomass to be purchased is not so cheap as compared with coke, so that there is a problem that the operating cost of the waste gasification and melting furnace cannot be reduced. In addition, since bulk biomass has not yet been stably supplied to the secondary market, there are problems with adjustments to purchase and delivery, and increased costs, and waste biomass gasification using bulk biomass. There is concern about whether the melting furnace can be operated stably.

  The present invention has been made in order to solve the above-described problems, and reduces the amount of coke used in a waste gasification melting furnace to reduce carbon dioxide emissions, and also provides a fuel for obtaining a melting heat source. Thus, it is an object of the present invention to provide a waste gasification and melting apparatus that can reduce the operating cost of the waste gasification and melting furnace and can perform stable operation.

  Biomass is classified by FAO (International Food and Agriculture Organization). As biomass, woody biomass such as forest land residue, thinned wood, unused trees, wood residue, construction waste, rice straw, rice husks, and papermaking Examples include unused biomass resources such as biomass, agricultural residues, livestock manure, and food waste. In the present invention, these biomasses are referred to as “biomass raw materials”.

The waste gasification and melting apparatus according to the present invention is a vertical waste gasification and melting furnace that thermally decomposes and gasifies input waste , forms a high-temperature combustion zone with coke, and melts the thermal decomposition residue of waste. And a secondary combustion chamber for secondary combustion of the combustible gas generated by gasification, and a boiler for recovering heat from the secondary combustion combustion gas and generating steam.

In such a waste gasification and melting apparatus, the present invention includes a carbide production apparatus that generates carbide from a biomass raw material and supplies the carbide to the waste gasification and melting furnace as an alternative fuel for coke. The reaction part has a reaction part that receives the biomass raw material and heats the biomass raw material to thermally decompose to produce carbide, and a heating part that heats the reaction part, and the reaction part inputs the produced carbide into a waste gasification and melting furnace. is connected to provide to the mouth, the heating unit is connected to at least one of the secondary combustion chamber and boiler so that receives a supply of waste heat recovered in at least one of the secondary combustion chamber and boiler It is characterized by being.

  According to the present invention having such a configuration, the biomass gasification and melting apparatus of the waste gasification and melting apparatus can be used without increasing carbon dioxide in the atmosphere when using the biomass raw material derived from living organisms as a whole including the growth process of living organisms. Carbide is obtained by a carbide production apparatus provided as a part, and burned in a waste gasification melting furnace as a fuel for obtaining a melting heat source. Therefore, the amount of coal coke supplied to the waste gasification and melting furnace is reduced by the amount of carbide used. This will reduce carbon dioxide emissions accordingly.

  In the present invention, the carbide manufacturing apparatus is preferably connected to the secondary combustion chamber so that the volatile gas generated together with the carbide in the carbide manufacturing apparatus is supplied as fuel to the secondary combustion chamber. By carrying out like this, the volatile gas produced | generated with a carbide | carbonized_material can be utilized for secondary combustion, and the volatile combustible content of biomass can be utilized effectively.

  In the present invention, the secondary combustion chamber and the boiler have a falling fly ash discharge unit that collects and discharges the falling fly ash in which the fly ash included in the exhaust gas has fallen, and the fall fly ash is removed by a carbide manufacturing apparatus. It is preferable that the falling fly ash discharge unit is connected to the carbide production device so as to be supplied to the carbide production device for mixing with the biomass raw material. By mixing the falling fly ash with the biomass raw material, the voids of the biomass raw material are filled with the fly ash in the carbide production apparatus, and a low oxygen atmosphere for carbonization is more reliably obtained.

  As described above, the present invention includes a carbide production apparatus as a part of the waste gasification and melting apparatus, obtains carbide from the biomass raw material by the carbide production apparatus, and uses the carbide as waste of the waste gasification apparatus. Since it was decided to supply it to the gasification and melting furnace as fuel, it was obtained from biomass without increasing carbon dioxide in the atmosphere using biomass raw materials derived from living organisms as a whole, including the growth process of living organisms. As a result of burning the carbide in the waste gasification and melting furnace as fuel, the amount of coal coke supplied as fuel to the waste gasification and melting furnace will be reduced by the amount of carbide used, and the amount of carbon dioxide emissions will be reduced accordingly. Will be reduced.

1 is a schematic configuration diagram of a waste gasification and melting apparatus as one embodiment of the present invention. 1 is a carbide manufacturing apparatus in the apparatus, and (A), (B), and (C) show schematic configuration diagrams of various examples.

  Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. The present embodiment is characterized in that a carbide manufacturing apparatus is provided in addition to the vertical waste gasification and melting furnace. Hereinafter, each apparatus which comprises the waste gasification melting apparatus of this embodiment including these apparatuses, and those relationship are demonstrated.

  The waste gasification and melting apparatus of one embodiment of the present invention shown in FIG. 1 has a shaft-type waste gasification and melting furnace 1 (hereinafter referred to as a gasification and melting furnace 1) having a vertical shape, and the gas In the upper part of the gasification and melting furnace 1, waste as a processing target to be gasified and melted, coal coke as fuel (hereinafter referred to as “coke”), biomass carbide (hereinafter referred to as “carbide”), and slag components An inlet 2 for introducing limestone as the adjusting material into the furnace is provided, and a gas outlet 3 for exhausting the gas in the furnace to the outside of the furnace is provided on the upper side. In addition, an outlet 4 for discharging molten slag and molten metal is provided at the bottom of the gasification melting furnace 1.

  The internal space of the gasification melting furnace 1 is roughly divided into three regions in the vertical direction. From the lower side, the lower shaft part I formed in the lower part of the furnace, the middle shaft part II located above it, and the upper part The region has the formed free board part III. Each of these parts I, II, and III is an area having the following functions. That is, the lower shaft portion I is a region where a high temperature combustion zone is formed by burning coke and carbides deposited in the lower portion of the furnace, and the middle shaft portion II is formed by the accumulation of waste put on the high temperature combustion zone. The area where the waste in the waste layer is thermally decomposed, the free board part III, is an area where the combustible gas generated by the combustion of the waste is partially burned.

  Above the gasification melting furnace 1, a supply device (not shown) for supplying waste such as municipal waste, coke and carbide, and limestone used as a component adjusting material for the generated slag is disposed. Waste, coke, carbide, and limestone supplied from this supply device are conveyed by a conveyer (not shown) and charged into the furnace through the charging port 2 at the top of the furnace.

  A tuyere that blows oxygen-containing gas into the respective parts of the lower shaft part I, the middle shaft part II, and the free board part III formed in the gasification melting furnace 1 is provided on the furnace wall. That is, the lower shaft portion I is provided with a main tuyere 5 that burns deposited coke and carbide to form a high-temperature combustion zone and blows in oxygen-enriched air for melting the pyrolysis residue. Part II is provided with a sub tuyere 6 that partially burns the waste deposited and deposits and blows in air to cause thermal decomposition while allowing the waste to flow gently. A three-stage tuyere 7 for blowing air for partially burning a combustible gas generated by thermal decomposition of an object and maintaining the interior at a predetermined temperature is provided.

  A secondary combustion chamber 10 is connected to the gas discharge port 3 and receives the combustible gas generated by pyrolyzing the waste in the gasification melting furnace 1 and combusts it. The secondary combustion chamber 10 has an air blowing port 11 through which air for secondary combustion is blown, and a volatile gas supply port that receives volatile gas from a carbide production device 13 described later and supplies the volatile gas to the secondary fuel chamber 10. Is provided, and a falling fly ash discharge unit 10A is provided in the lower part. A boiler 12 that recovers heat from the combustion gas obtained by burning the combustible gas in the secondary combustion chamber 10 is provided in communication with the secondary combustion chamber 10.

  The carbide manufacturing apparatus 13 has a reaction part formed as an internal space in the cylinder and a heating part that applies heat to the reaction part from the outside. For example, as shown in FIG. 2 (A), the inside of the cylinder 13A is used as a reaction part, and an annular cylinder-shaped jacket 13B that surrounds the outer peripheral surface of the cylinder 13A and forms an annular space is used as a heating part. be able to. The carbide production apparatus 13 receives the biomass raw material in the reaction section, the heating section receives the waste heat supplied from the secondary combustion chamber 10 or the boiler 12, and uses this as a heat source to reduce the biomass raw material in the reaction section. It is thermally decomposed in an oxygen atmosphere to generate carbides and combustible volatile gases, which are discharged. As a method for supplying waste heat from the secondary combustion chamber 10 or the boiler 12, the generated steam may be supplied, or a heat medium exchanged with the steam may be supplied. As such, food residues, wood chips and the like having a high retained heat amount are preferable. Such a carbide manufacturing apparatus 13 is connected so as to supply the generated carbide to the inlet 2 of the waste gasification melting furnace 1, and the volatile gas generated together with the carbide to the secondary combustion chamber 10. Connected to supply.

  The carbide manufacturing apparatus 13 is not limited to the example of FIG. 2 (A). For example, as shown in FIG. 2 (B), a cylinder 13A ′ sealed as a reaction unit and a jacket as a heating unit provided around the cylinder 13A ′ It is good also as an apparatus which has 13B 'and the stirring member 13C' rotates in the said cylinder 13A '.

  Further, as shown in FIG. 2 (C), the carbide manufacturing apparatus 13 is provided with a jacket 13B ″ as a heating part on the outer periphery of the horizontal cylinder 13A ″ as a reaction part as a horizontal type, and the horizontal cylinder 13A ′. It is good also as arrange | positioning the stirring conveyance member 13C '' which has a spiral blade in 'and is rotationally driven by motor 13D' '. In this case, the biomass raw material can be supplied to the reaction section from the left end opening of the horizontal cylinder 13A ″, the carbide can be taken out from the right end opening, and the biomass raw material can be supplied and the carbide taken out continuously.

  In FIG. 1, the exhaust gas discharged from the exhaust section 12A that is the outlet of the boiler 12 connected to the secondary combustion chamber 10 can be released to the atmosphere by removing dust and acid gas by an exhaust gas processing device (not shown). It is detoxified and released into the atmosphere via a chimney.

  In such a waste gasification and melting apparatus, the carbide manufacturing apparatus 13 is connected to the gasification and melting furnace 1 so as to supply the carbide generated from the biomass raw material as fuel to the gasification and melting furnace 1, and the above-mentioned When carbonized raw material is carbonized to produce carbide by the carbide production device 13, the vaporized carbonization gas contains a combustible gas. Therefore, as a preferred embodiment, the volatile gas produced at the same time is used as fuel for the secondary combustion chamber 10. It is connected to the secondary combustion chamber 10 so as to be supplied, and this volatile gas is combusted in the secondary combustion chamber 10 so that the combustion heat is recovered by the boiler 12 so that the thermal energy of the biomass raw material can be used effectively. It has become.

  Further, the secondary combustion chamber 10 and the boiler 12 are, as a preferred embodiment, at least part of the fallen fly ash from the secondary combustion chamber 10 and the boiler 12 and the fall fly ash through the fall fly ash discharge unit 10A. 13 is connected to the carbide producing apparatus 13 so as to be fed to the biomass raw material to be mixed.

  Operation of the waste gasification and melting apparatus in the present embodiment configured as described above is performed as follows.

  In the gasification and melting furnace 1, waste, coke, biomass carbide, and limestone from the supply device are respectively charged into the furnace by a predetermined amount through the inlet 2 provided in the upper part of the gasification and melting furnace 1. Oxygen-enriched air or air is blown into the furnace from the tuyere 5, sub tuyere 6, and three-stage tuyere 7, respectively. Waste introduced from the inlet is deposited on the middle shaft part II in the furnace to form a waste layer, and from the hot gas rising from the high temperature combustion zone of the lower shaft part I and the sub tuyere 6 It is dried by blown air and then pyrolyzed. A part of the combustible gas generated by pyrolysis is burned by the air blown from the three-stage tuyere 7 in the free board part III, and the atmospheric temperature is maintained at a temperature of 850 ° C. or more, thereby decomposing the tar content. The generated gas is sent to the secondary combustion chamber 10 provided outside the furnace through the gas discharge port 3 provided in the upper part of the gasification melting furnace 1 for the secondary combustion. Air is blown and burned, and the combustion gas is sent to the boiler 12 to recover heat. The residue resulting from the thermal decomposition of the waste in the waste layer of the middle shaft part II descends, reaches the lower shaft part I where the high temperature combustion zone where the coke is burned is formed, and remains in the lower shaft part I The fixed carbon as the combustible material burns, and the incombustible material melts into molten slag and molten metal. Molten slag and molten metal are discharged from the tap 4, supplied to a water granulating device (not shown) provided outside the furnace, cooled and solidified, and the cooled and solidified granulated slag and granulated metal are recovered. .

  A part of the fly ash discharged accompanying the generated gas sent from the gasification melting furnace 1 to the secondary combustion chamber 10 falls to the lower hopper portion of the secondary combustion chamber 10 and the lower hopper portion of the boiler 12. Then, it is collected from the falling fly ash discharge unit 10A as falling fly ash. At least a part of the falling fly ash collected from both the hopper parts is mixed with the biomass raw material and supplied to the carbide manufacturing apparatus 13. At least a part of the fly ash collected by the falling fly ash discharge unit 10 </ b> A is transferred to a biomass material supply unit (not shown) of the carbide manufacturing apparatus 13 by a transfer unit. The fall fly ash collected from the fall fly ash discharge unit 10A may be temporarily stored in a storage tank or the like and transported from the storage tank or the like to a biomass raw material supply unit (not shown) of the carbide manufacturing apparatus 13. In the carbide manufacturing apparatus 13, the falling fly ash fills the voids of the biomass raw material, so that the oxygen in the voids can be reduced and the atmosphere can be carbonized efficiently. Fly ash is discharged together with carbide from a carbide discharge section (not shown).

  At least a part of the waste heat recovered in the secondary combustion chamber 10 and the boiler 12 from the combustion gas generated by the combustion in the secondary combustion chamber 10 is supplied to the carbide manufacturing device 13 as a heat source to the carbide manufacturing device 13. Is done.

  In the carbide manufacturing apparatus 13, the biomass raw material from the biomass raw material supply unit is supplied into the reaction unit together with the fly ash collected from the secondary combustion chamber 10 and the boiler 12. In the reaction section, a temperature of 350 to 500 ° C. is obtained by indirect heating from waste heat of the combustion gas in the secondary combustion chamber 10 and the boiler 12 in a low oxygen atmosphere state where the gap between the biomass raw materials is filled with fly ash. Pyrolysis and carbonization proceed under thermal decomposition. The reason why the carbonization atmosphere temperature is set to a temperature range of 350 to 500 ° C. is that if it is lower than 350 ° C., the thermal decomposition reaction efficiency of the biomass raw material is lowered, and if it is higher than 500 ° C., the strength of the member forming the reaction part is lowered This is because troubles occur.

  Volatile gas generated when the biomass raw material is pyrolyzed is discharged from a volatile gas discharge unit (not shown). Thus, carbide and fly ash are discharged from the carbide discharge section, and volatile gas is discharged from the volatile gas discharge section.

  The carbide discharged from the carbide discharge section is supplied as fuel to the gasification melting furnace 1 together with the mixed fly ash and used as a heat source for melting. Fly ash is melted together with the pyrolysis residue in the high-temperature combustion zone, and is discharged out of the furnace from the tap 4 as slag and metal. Volatile gas discharged from the volatile gas discharge section is supplied as fuel to the secondary combustion chamber 10, and this dry distillation gas is combusted in the secondary combustion chamber 10, and the combustion heat is recovered by the boiler 12 to heat the biomass raw material. Energy can be used effectively.

  In the present invention, the heat of the combustion gas obtained by burning the combustible gas generated in the gasification melting furnace by the carbide manufacturing apparatus using the biomass raw material as the carbonized raw material and the waste heat recovered from the secondary combustion chamber and the boiler as the heat source. Since the carbide is produced using energy, the following effects can be obtained.

  ・ Waste heat recovered from at least one of the secondary combustion chamber and boiler of the waste gasification and melting device, ie, disposal, as an alternative to part of the coke that forms the high-temperature combustion zone in the waste gasification and melting furnace Since the carbide produced using the combustion heat of the combustible gas obtained from the product is used, the amount of coke used can be reduced, and the operating cost of the waste gasification melting furnace can be reduced.

  ・ Uses carbonized raw material as carbonized raw material, and uses carbonized waste heat recovered from at least one of the secondary combustion chamber and boiler of the waste gasification and melting furnace as a heat source. It can be used as an alternative fuel that is cheaper than coke.

  ・ Since part of the waste supplied to the gasification melting furnace can be used as carbonization raw material, the amount of waste to be melted in the gasification melting furnace can be reduced. As a result, the amount of coke required can be reduced.

  ・ The thermal energy to produce carbides uses the thermal energy of the combustion gas that burned the combustible gas generated in the gasification melting furnace, so compared to using the carbide produced by the thermal energy that burned the fuel separately, It is inexpensive and can reduce the amount of coke used at low cost.

  ・ Fly ash is mixed with waste and supplied to the carbide production equipment, and it is possible to easily build a low oxygen atmosphere by filling the gap between the waste with fly ash so that oxygen does not exist in the voids. can do. In addition, by supplying the carbide and fly ash discharged from the carbide manufacturing equipment into the gasification melting furnace, the fly ash is melted and discharged as slag and metal, so it is discharged from the gasification melting furnace with the generated gas. The amount of fly ash that needs to be collected and collected by the dust collector and detoxified can be reduced, and the fly ash treatment cost can be reduced.

  ・ By supplying carbonization gas generated when carbonizing waste in the carbide production equipment to the secondary combustion chamber and burning it and recovering heat from the combustion gas, the amount of heat generated by combustibles in the waste is effectively increased. Available.

DESCRIPTION OF SYMBOLS 1 Waste gasification melting furnace 10 Secondary combustion chamber 10A Falling fly ash discharge part 12 Boiler 13 Carbide manufacturing apparatus

Claims (3)

A waste-type waste gasification melting furnace that pyrolyzes and gasifies the input waste , forms a high-temperature combustion zone with coke, and melts the pyrolysis residue of the waste, and secondary combustion of the combustible gas generated by gasification In a waste gasification and melting device comprising a secondary combustion chamber that performs and a boiler that recovers heat from the combustion gas that has been subjected to secondary combustion and generates steam,
It is equipped with a carbide production device that produces carbide from biomass raw materials and supplies this carbide to a waste gasification and melting furnace as an alternative fuel for coke ,
The carbide manufacturing apparatus has a reaction part that receives a biomass raw material and heats the biomass raw material to thermally decompose to produce carbide, and a heating part that heats the reaction part ,
The reaction unit is connected to supply the generated carbide to the inlet of the waste gasification melting furnace,
Heating unit, waste gases, characterized in that it is connected to at least one of the secondary combustion chamber and boiler so that receives a supply of waste heat recovered in at least one of the secondary combustion chamber and boiler Melting equipment.   2. The disposal according to claim 1, wherein the carbide manufacturing apparatus is connected to the secondary combustion chamber so as to supply a volatile gas generated together with the carbide in the carbide manufacturing apparatus as a fuel to the secondary combustion chamber. Product gasification melting equipment. The secondary combustion chamber and the boiler have a falling fly ash discharge part that collects and discharges the falling fly ash from which the fly ash contained in the exhaust gas has fallen,
The fall fly ash discharge section is connected to the carbide production apparatus so as to supply the fall fly ash to the carbide production apparatus for mixing with the biomass raw material in the carbide production apparatus. The waste gasification and melting apparatus described in 1.

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