WO1998047985A1 - Procede et dispositif servant a traiter des dechets par gazeification - Google Patents

Procede et dispositif servant a traiter des dechets par gazeification Download PDF

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Publication number
WO1998047985A1
WO1998047985A1 PCT/JP1997/003814 JP9703814W WO9847985A1 WO 1998047985 A1 WO1998047985 A1 WO 1998047985A1 JP 9703814 W JP9703814 W JP 9703814W WO 9847985 A1 WO9847985 A1 WO 9847985A1
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Prior art keywords
gas
fluidized
temperature
bed reactor
wastes
Prior art date
Application number
PCT/JP1997/003814
Other languages
English (en)
Inventor
Hiroyuki Fujimura
Yoshio Hirayama
Shosaku Fujinami
Kazuo Takano
Masaaki Irie
Tetsuhisa Hirose
Shuichi Nagato
Takahiro Oshita
Toshio Fukuda
Original Assignee
Ebara Corporation
Ube Industries, Ltd.
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
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Publication date
Priority claimed from JP11743497A external-priority patent/JP4222645B2/ja
Application filed by Ebara Corporation, Ube Industries, Ltd. filed Critical Ebara Corporation
Priority to EP97909579A priority Critical patent/EP0979262B1/fr
Priority to DE69730870T priority patent/DE69730870T2/de
Publication of WO1998047985A1 publication Critical patent/WO1998047985A1/fr

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    • C—CHEMISTRY; METALLURGY
    • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
    • C10J—PRODUCTION OF PRODUCER GAS, WATER-GAS, SYNTHESIS GAS FROM SOLID CARBONACEOUS MATERIAL, OR MIXTURES CONTAINING THESE GASES; CARBURETTING AIR OR OTHER GASES
    • C10J3/00—Production of combustible gases containing carbon monoxide from solid carbonaceous fuels
    • C10J3/72—Other features
    • C10J3/721—Multistage gasification, e.g. plural parallel or serial gasification stages
    • C—CHEMISTRY; METALLURGY
    • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
    • C10J—PRODUCTION OF PRODUCER GAS, WATER-GAS, SYNTHESIS GAS FROM SOLID CARBONACEOUS MATERIAL, OR MIXTURES CONTAINING THESE GASES; CARBURETTING AIR OR OTHER GASES
    • C10J3/00—Production of combustible gases containing carbon monoxide from solid carbonaceous fuels
    • C10J3/46—Gasification of granular or pulverulent flues in suspension
    • C10J3/48—Apparatus; Plants
    • C10J3/482—Gasifiers with stationary fluidised bed
    • C—CHEMISTRY; METALLURGY
    • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
    • C10J—PRODUCTION OF PRODUCER GAS, WATER-GAS, SYNTHESIS GAS FROM SOLID CARBONACEOUS MATERIAL, OR MIXTURES CONTAINING THESE GASES; CARBURETTING AIR OR OTHER GASES
    • C10J3/00—Production of combustible gases containing carbon monoxide from solid carbonaceous fuels
    • C10J3/46—Gasification of granular or pulverulent flues in suspension
    • C10J3/54—Gasification of granular or pulverulent fuels by the Winkler technique, i.e. by fluidisation
    • C—CHEMISTRY; METALLURGY
    • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
    • C10J—PRODUCTION OF PRODUCER GAS, WATER-GAS, SYNTHESIS GAS FROM SOLID CARBONACEOUS MATERIAL, OR MIXTURES CONTAINING THESE GASES; CARBURETTING AIR OR OTHER GASES
    • C10J3/00—Production of combustible gases containing carbon monoxide from solid carbonaceous fuels
    • C10J3/46—Gasification of granular or pulverulent flues in suspension
    • C10J3/54—Gasification of granular or pulverulent fuels by the Winkler technique, i.e. by fluidisation
    • C10J3/56—Apparatus; Plants
    • C—CHEMISTRY; METALLURGY
    • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
    • C10J—PRODUCTION OF PRODUCER GAS, WATER-GAS, SYNTHESIS GAS FROM SOLID CARBONACEOUS MATERIAL, OR MIXTURES CONTAINING THESE GASES; CARBURETTING AIR OR OTHER GASES
    • C10J3/00—Production of combustible gases containing carbon monoxide from solid carbonaceous fuels
    • C10J3/58—Production of combustible gases containing carbon monoxide from solid carbonaceous fuels combined with pre-distillation of the fuel
    • C10J3/60—Processes
    • C10J3/64—Processes with decomposition of the distillation products
    • C10J3/66—Processes with decomposition of the distillation products by introducing them into the gasification zone
    • C—CHEMISTRY; METALLURGY
    • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
    • C10J—PRODUCTION OF PRODUCER GAS, WATER-GAS, SYNTHESIS GAS FROM SOLID CARBONACEOUS MATERIAL, OR MIXTURES CONTAINING THESE GASES; CARBURETTING AIR OR OTHER GASES
    • C10J3/00—Production of combustible gases containing carbon monoxide from solid carbonaceous fuels
    • C10J3/72—Other features
    • C10J3/82—Gas withdrawal means
    • C10J3/84—Gas withdrawal means with means for removing dust or tar from the gas
    • C—CHEMISTRY; METALLURGY
    • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
    • C10K—PURIFYING OR MODIFYING THE CHEMICAL COMPOSITION OF COMBUSTIBLE GASES CONTAINING CARBON MONOXIDE
    • C10K1/00—Purifying combustible gases containing carbon monoxide
    • C10K1/08—Purifying combustible gases containing carbon monoxide by washing with liquids; Reviving the used wash liquors
    • C10K1/10—Purifying combustible gases containing carbon monoxide by washing with liquids; Reviving the used wash liquors with aqueous liquids
    • C10K1/101—Purifying combustible gases containing carbon monoxide by washing with liquids; Reviving the used wash liquors with aqueous liquids with water only
    • C—CHEMISTRY; METALLURGY
    • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
    • C10K—PURIFYING OR MODIFYING THE CHEMICAL COMPOSITION OF COMBUSTIBLE GASES CONTAINING CARBON MONOXIDE
    • C10K3/00—Modifying the chemical composition of combustible gases containing carbon monoxide to produce an improved fuel, e.g. one of different calorific value, which may be free from carbon monoxide
    • C10K3/02—Modifying the chemical composition of combustible gases containing carbon monoxide to produce an improved fuel, e.g. one of different calorific value, which may be free from carbon monoxide by catalytic treatment
    • C10K3/04—Modifying the chemical composition of combustible gases containing carbon monoxide to produce an improved fuel, e.g. one of different calorific value, which may be free from carbon monoxide by catalytic treatment reducing the carbon monoxide content, e.g. water-gas shift [WGS]
    • C—CHEMISTRY; METALLURGY
    • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
    • C10G—CRACKING HYDROCARBON OILS; PRODUCTION OF LIQUID HYDROCARBON MIXTURES, e.g. BY DESTRUCTIVE HYDROGENATION, OLIGOMERISATION, POLYMERISATION; RECOVERY OF HYDROCARBON OILS FROM OIL-SHALE, OIL-SAND, OR GASES; REFINING MIXTURES MAINLY CONSISTING OF HYDROCARBONS; REFORMING OF NAPHTHA; MINERAL WAXES
    • C10G2300/00—Aspects relating to hydrocarbon processing covered by groups C10G1/00 - C10G99/00
    • C10G2300/10—Feedstock materials
    • C10G2300/1003—Waste materials
    • C—CHEMISTRY; METALLURGY
    • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
    • C10J—PRODUCTION OF PRODUCER GAS, WATER-GAS, SYNTHESIS GAS FROM SOLID CARBONACEOUS MATERIAL, OR MIXTURES CONTAINING THESE GASES; CARBURETTING AIR OR OTHER GASES
    • C10J2300/00—Details of gasification processes
    • C10J2300/09—Details of the feed, e.g. feeding of spent catalyst, inert gas or halogens
    • C10J2300/0913—Carbonaceous raw material
    • C10J2300/0946—Waste, e.g. MSW, tires, glass, tar sand, peat, paper, lignite, oil shale
    • C—CHEMISTRY; METALLURGY
    • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
    • C10J—PRODUCTION OF PRODUCER GAS, WATER-GAS, SYNTHESIS GAS FROM SOLID CARBONACEOUS MATERIAL, OR MIXTURES CONTAINING THESE GASES; CARBURETTING AIR OR OTHER GASES
    • C10J2300/00—Details of gasification processes
    • C10J2300/16—Integration of gasification processes with another plant or parts within the plant
    • C10J2300/1603—Integration of gasification processes with another plant or parts within the plant with gas treatment
    • C10J2300/1606—Combustion processes
    • C—CHEMISTRY; METALLURGY
    • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
    • C10J—PRODUCTION OF PRODUCER GAS, WATER-GAS, SYNTHESIS GAS FROM SOLID CARBONACEOUS MATERIAL, OR MIXTURES CONTAINING THESE GASES; CARBURETTING AIR OR OTHER GASES
    • C10J2300/00—Details of gasification processes
    • C10J2300/16—Integration of gasification processes with another plant or parts within the plant
    • C10J2300/1693—Integration of gasification processes with another plant or parts within the plant with storage facilities for intermediate, feed and/or product
    • C—CHEMISTRY; METALLURGY
    • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
    • C10J—PRODUCTION OF PRODUCER GAS, WATER-GAS, SYNTHESIS GAS FROM SOLID CARBONACEOUS MATERIAL, OR MIXTURES CONTAINING THESE GASES; CARBURETTING AIR OR OTHER GASES
    • C10J2300/00—Details of gasification processes
    • C10J2300/18—Details of the gasification process, e.g. loops, autothermal operation
    • C10J2300/1807—Recycle loops, e.g. gas, solids, heating medium, water
    • C10J2300/1823—Recycle loops, e.g. gas, solids, heating medium, water for synthesis gas
    • C—CHEMISTRY; METALLURGY
    • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
    • C10J—PRODUCTION OF PRODUCER GAS, WATER-GAS, SYNTHESIS GAS FROM SOLID CARBONACEOUS MATERIAL, OR MIXTURES CONTAINING THESE GASES; CARBURETTING AIR OR OTHER GASES
    • C10J2300/00—Details of gasification processes
    • C10J2300/18—Details of the gasification process, e.g. loops, autothermal operation
    • C10J2300/1861—Heat exchange between at least two process streams
    • C—CHEMISTRY; METALLURGY
    • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
    • C10J—PRODUCTION OF PRODUCER GAS, WATER-GAS, SYNTHESIS GAS FROM SOLID CARBONACEOUS MATERIAL, OR MIXTURES CONTAINING THESE GASES; CARBURETTING AIR OR OTHER GASES
    • C10J2300/00—Details of gasification processes
    • C10J2300/18—Details of the gasification process, e.g. loops, autothermal operation
    • C10J2300/1861—Heat exchange between at least two process streams
    • C10J2300/1884—Heat exchange between at least two process streams with one stream being synthesis gas

Definitions

  • the present invention relates to a method and apparatus for treating wastes by gasification, and more particularly to a method and apparatus for treating wastes by two-stage gasification to recover metals or ash content in the wastes in such a state that they can be recycled and gases mainly composed of carbon monoxide (CO) and hydrogen gas (H 2 ) for use as synthesis gas of hydrogen gas or ammonia (NH 3 ).
  • gases mainly composed of carbon monoxide (CO) and hydrogen gas (H 2 ) for use as synthesis gas of hydrogen gas or ammonia (NH 3 ).
  • Ammonia is a mass-produced basic material for producing nitric acid, fertilizers including ammonium nitrate, ammonium sulfate and urea, acrylonitrile, caprolactam or the like.
  • Ammonia is catalytic synthesized from nitrogen gas (N 2 ) and hydrogen gas (H 2 ) under a high pressure.
  • Hydrogen gas has been produced by either steam reforming of natural gas or naphtha, or partial combustion, i.e., gasification of hydrocarbon such as crude oil, heavy oil, bottom oil, coal, pitch or petroleum coke.
  • a stoker furnace or a fluidized-bed furnace has heretofore been used for the incineration of the organic wastes.
  • this incineration has been problematic in respect to environmental conservation, or recycling of resources or energy.
  • large quantities of exhaust gas are discharged because of high air ratio, and toxic dioxins are contained in the exhaust gas.
  • metals which are discharged from the furnace are not good for recycling because they are severely oxidized, and landfill sites become scarce yearbyyear.
  • the number of waste treatment facilities which incorporate ash-melting equipments is increasing, however, a problem is encountered in the increase of construction cost and/or operating cost of the waste treatment facilities. Further, recently, there has been developing a tendency to utilize energy of the wastes more efficiently.
  • a method for treating wastes by gasification comprising: gasifying wastes in a fluidized-bed reactor at a relatively low temperature; introducing gaseous material and char produced in the fluidized-bed reactor into a high-temperature combustor; producing synthesis gas in the high-temperature combustor at a relatively high temperature; converting the synthesis gas by CO-shift reaction after scrubbing for removal of acid components; producing hydrogen gas by gas separation process; and supplying residual gas to the fluidized-bed in the fluidized-bed reactor.
  • the gas separation process may be carried out by one of pressure swing adsorption or hydrogen gas separation membrane.
  • a method for treating wastes by gasification comprising: gasifying wastes in a fluidized-bed reactor at a relatively low temperature; introducing gaseous material and char produced in the fluidized-bed reactor into a high- temperature combustor; producing synthesis gas in the high- temperature combustor at a relatively high temperature; converting the synthesis gas by CO-shift reaction; removing acid components in the gas from the CO-shift reaction to obtain hydrogen gas; supplying a part of the removed acid components to the fluidized-bed reactor.
  • Above-mentioned CO-shift reaction can be carried out after removal of the acid components in the synthesis gas.
  • an apparatus for treating wastes by gasification comprising: a fluidized-bed reactor for gasifying wastes at a relatively low temperature to produce gaseous material and char; a high-temperature combustor for producing synthesis gas at a relatively high temperature: a cooling chamber containing water for cooling the synthesis gas; a water scrubber for removing acid components from gas supplied from the cooling chamber; a CO-shift converter for carrying out CO-shift reaction to convert CO, H 2 0 in the gas from the water scrubber into C0 2 , H 2 ; a gas separator for separating gas into hydrogen gas and residual gas; and a pipeline for supplying the residual gas to the fluidized-bed reactor.
  • an apparatus for treating wastes by gasification comprising: a fluidized-bed reactor for gasifying wastes at a relatively low temperature to produce gaseous material and char; a high-temperature combustor for introducing synthesis gas at a relatively high temperature: a cooling chamber containing water for cooling said synthesis gas; a CO-shift converter for carrying out CO-shift reaction to convert CO and H 2 0 in the gas from said cooling chamber into C0 2 and H 2 ; an acid gas remover for removing acid components in the gas after CO-shift reaction; and a pipeline for supplying a part of said acid components to the fluidized-bed reactor.
  • the acid gas remover may be provided between the cooling chamber and the CO-shift converter.
  • the two-stage gasification in the present invention may be carried out under atmospheric pressure, but economically may be carried out under a pressure ranging 5 to 90 atm, preferably 10 to 40 atm.
  • a gasifying agent air and/or oxygen gas obtained by air separation may be used.
  • steam or carbon dioxide (C0 2 ) may be added to them.
  • the fluidized-bed temperature of the fluidized-bed reactor is preferably in the range of 450 to 950°C.
  • the wastes preferably has an average lower calorific value of 3500 kcal/kg or more. If the average lower calorific value of the wastes is 3500Kcal/kg or less, a supplementary fuel may be added to the wastes to allow the average lower calorific value to be 3500kcal/kg or more.
  • a supplementary fuel fossil fuel, which is generally used, such as coal or petroleum coke, may be used.
  • a revolving flow-type fluidized-bed reactor is preferably used.
  • a revolving flow of the fluidized medium is formed in the fluidized-bed by controlling linear velocity of fluidizing gas.
  • the revolving flow-type fluidized-bed is superior in dispersion and crushing functions of char to a bubbling-type fluidized-bed in which linear velocity of fluidizing gas is uniform.
  • the revolving flow-type fluidized-bed reactor is structurally simpler and smaller-sized, comparing to an externally circulating fluidized-bed reactor.
  • the revolving flow-type fluidized-bed reactor preferably has a vertically cylindrical shape because it is operated under pressurized condition.
  • gaseous material containing ash and char produced in the fluidized-bed reactor are gasified at a temperature higher than an ash melting point.
  • the temperature in the high-temperature combustor is 1200°C or higher.
  • the total amount of oxygen gas supplied to the fluidized-bed reactor and the high-temperature combustor may be in the range of 0.1 to 0.6 of the theoretical oxygen for combustion.
  • the amount of oxygen supplied to the fluidized-bed reactor may be in the range of 0.1 to 0.3 of the theoretical oxygen for combustion.
  • the fluidized-bed reactor has a reducing atmosphere, and thus metals in the wastes can be recovered in a non-corroded condition from the bottom of the fluidized-bed reactor .
  • the temperature in the high-temperature combustor is set at 1200°C or higher so that the temperature in the high-temperature combustor is 50 to 100°C higher than ash melting point, thus ash content is discharged as molten slag from the bottom of the combustor.
  • a gas separation unit for separating air into nitrogen gas and oxygen gas is provided.
  • means for supplying the separated nitrogen gas to an ammonia synthesis reactor, and means for supplying the separated oxygen gas to the fluidized-bed reactor and/or the high-temperature combustor may be provided.
  • Wastes which are used in the present invention may be municipal wastes, plastic wastes including fiber-reinforced plastics (FRP), biomass wastes, automobile wastes, low-grade coal, waste oil, and alternative fuels such as RDF (refuse- derived fuel) and SWM (solid-water mixture) made from the above wastes .
  • FRP fiber-reinforced plastics
  • biomass wastes biomass wastes
  • automobile wastes low-grade coal
  • waste oil waste oil
  • alternative fuels such as RDF (refuse- derived fuel) and SWM (solid-water mixture) made from the above wastes .
  • RDF reuse- derived fuel
  • SWM solid-water mixture
  • the alternative fuels include refuse-derived fuel which is produced by pulverizing and classifying municipal wastes, adding quicklime, and compacting for pelletization, and solid-water mixture which is produced by crushing municipal wastes, adding water and mixing, and converting to an oily fuel by hydrothermal reaction.
  • the biomass wastes include wastes from waterworks or sewage plants (misplaced materials, screen residues, sewage sludges, or the like), agricultural wastes (rice husk, rice straw, surplus products, or the like), forestry wastes (sawdust, bark, lumber from thinning, or the like), industrial wastes (pulp-chip dust, or the like), and construction wastes .
  • the low-grade coal includes peat which has low degrees of coalification, or refuse from coal dressing.
  • the present invention is also applicable to organic materials including oil shale, garbage, carcasses of beasts, waste clothing, waste paper, and any other material.
  • FIG. 1 is a schematic diagram of an apparatus for carrying out the treating method according to a first embodiment of the present invention
  • FIG.2 is a schematic diagram of an apparatus for carrying out the treating method according to a second embodiment of the present invention.
  • FIG.3 is a schematic diagram of an apparatus for carrying out the treating method according to a third embodiment of the present invention.
  • FIG.4 is a flow diagram showing a process for synthesizing ammonia (NH 3 ) from the wastes according to an embodiment of the present invention
  • FIG. 5 is a block diagram showing a process for producing ammonia (NH 3 ) from the wastes according to another embodiment of the present invention
  • FIG. 6 is a block diagram showing another process for producing hydrogen gas (H 2 ) from the wastes according to an embodiment of the present invention
  • FIG. 7 is a schematic diagram of a known apparatus for gasifying and combusting the wastes.
  • FIG. 8 is a graph showing pyrolysis characteristics of RDF in a nitrogen atmosphere.
  • the present invention among organic wastes, one or more of the municipal wastes, the refuse-derived fuel, the solid-water mixture, the plastic wastes, the fiber-reinforced plastic wastes, the biomass wastes, the automobile wastes, the low-grade coal, and the waste oil can be used.
  • fossil fuels such as coal or petroleum coke can be added to the organic wastes as a supplementary fuel.
  • the two-stage gasification in the present invention is a combination of gasification at a relatively low temperature and gasification at a relatively high temperature, and a fluidized-bed reactor is used for the gasification at the relatively low temperature and a high-temperature combustor is used for the gasification at the relative high temperature.
  • the fluidized-bed reactor used for the low-temperature gasification is maintained at a temperature ranging from 450 to 950°C to partially combust, i.e., gasify the supplied wastes .
  • Metals such as iron or copper in the wastes can be recovered in a non-corroded condition from the fluidized-bed reactor. The reason why metals are not oxidized is that a reducing atmosphere is formed in the fluidized-bed reactor.
  • Typical compound material of metal and plastics is a cable, and plastics which covers the copper wire is pyrolyzed and completely deleted in the fluidized-bed reactor and only the copper wire is recovered in a non-corroded condition suitable for recycling.
  • gas containing char and tar supplied from the fluidized-bed reactor is partially combusted, i.e., gasified instantaneously at a temperature of 1200°C or higher, and ash content is discharged as molten slag from the bottom of the high-temperature combustor.
  • gas containing char and tar supplied from the fluidized-bed reactor is partially combusted, i.e., gasified instantaneously at a temperature of 1200°C or higher, and ash content is discharged as molten slag from the bottom of the high-temperature combustor.
  • a swirling-type combustor is used as the high-temperature combustor, high load combustion can be performed to allow the combustor to be small-sized.
  • slag mist generated by combustion of char is attached to the inner wall of the combustor to form molten slag phase, thus achieving high slag recovery ranging from 80 to 90 %. This reduces the load of a heat recovery device and a dust collector provided downstream of the combustor.
  • a gasifying agent used in the fluidized-bed reactor a mixture of steam and oxygen gas obtained by air separation is used, while nitrogen gas obtained by air separation can be used for synthesis of ammonia.
  • a low-temperature separation, an adsorption process such as PSA or TSA, and a method using a separating membrane are applicable to the air separation.
  • gas whose mole ratio of H 2 to N 2 is 3:1 is produced, and the produced gas is used for synthesis of ammonia. That is, as a gasifying agent supplied to the fluidized-bed reactor, in order to avoid agglomeration or clinker, it is necessary to reduce oxygen gas content to the range of 20 to 30 %. If a mixture of oxygen gas and steam is used as a gasifying agent, a large amount of steam is required. However, in case of producing ammonia as a final product, it is possible to use air. This is because if nitrogen gas remains in the produced gas and the mole ratio of H 2 to N 2 is 3:1, the produced gas can be used for synthesis of ammonia as it is.
  • the apparatus comprises a fluidized-bed reactor for partially combusting the organic wastes , a gasification chamber in the high-temperature combustor for partially combusting gaseous material and char from the fluidized-bed reactor at a high temperature, and a cooling chamber for cooling gas from the gasification chamber.
  • a fluidized-bed reactor for partially combusting the organic wastes
  • a gasification chamber in the high-temperature combustor for partially combusting gaseous material and char from the fluidized-bed reactor at a high temperature
  • a cooling chamber for cooling gas from the gasification chamber.
  • the apparatus further comprises a scrubber provided downstream of the cooling chamber for removing HCl and dust in the gas, a CO converter for converting CO and H 2 0 in the gas into C0 2 and H 2 , an acid gas remover for absorbing acid gas such as C0 2 , H 2 S and COS, a gas refiner for removing CO and C0 2 which are harmful to ammonia synthesis catalyst or making CO and C0 2 to be harmless, and a reactor for synthesizing NH 3 by reacting the refined H 2 with N 2 .
  • a scrubber provided downstream of the cooling chamber for removing HCl and dust in the gas
  • a CO converter for converting CO and H 2 0 in the gas into C0 2 and H 2
  • an acid gas remover for absorbing acid gas such as C0 2 , H 2 S and COS
  • a gas refiner for removing CO and C0 2 which are harmful to ammonia synthesis catalyst or making CO and C0 2 to be harmless
  • a reactor for synthesizing NH 3
  • the apparatus preferably comprises an air separator, and means for introducing the separated oxygen gas into the fluidized-bed reactor and/or the high-temperature combustor.
  • Metals such as iron or copper can be recovered in a non-corroded condition suitable for recycling.
  • the gasification and high-temperature combustion system can be combined with a hydrogen gas production facility and an ammonia production facility, whereby organic wastes including municipal wastes, plastic wastes, fiber-reinforced plastic wastes, low-grade coal, and waste oil are gasified in a lump to thus solve problems caused by incineration or dumping of the organic wastes and to effectively utilize the organic wastes.
  • a gasification and high- temperature combustion system which combines a fluidized-bed reactor and a high-temperature combustor.
  • sand such as silica or Olivine sand, alumina, iron granule, limestone, dolomite, or the like may be used.
  • the municipal wastes, the biomass wastes , the plastic wastes , and the automobile wastes are roughly crushed to a size of about 30 cm.
  • the refuse-derived fuel and the solid water mixture are used as they are.
  • the low-grade coal is crushed to a size of 40 mm or less.
  • the above wastes are separated and charged into a several pits, and well stirred and mixed in each of the pits, and then supplied to the fluidized-bed reactor.
  • the wastes in the pit may be supplied to the fluidized-bed reactor separately, or may be supplied to the fluidized-bed reactor after being mixed.
  • the organic wastes are supplied to the fluidized-bed reactor and gasified in the fluidized-bed at a temperature ranging from 450 to 950°C, and further gasified in the high-temperature combustor at a temperature of 1200°C or higher.
  • a gasifying agent oxygen gas, air and steam are mixed, and, if necessary, are preheated. Further, carbon dioxide may be used in place of steam.
  • the quantity of heat necessary for gasification at respective stages can be obtained by partial combustion of thewastes . This is called " internal heating type" .
  • Gas, tar and char are generated by gasification in the fluidized-bed. In case that the fluidized-bed temperature is low, the generating ratio of tar and char increases and the generating ratio of gas decreases.
  • the metals whose melting point is higher than the temperature of the fluidized-bed are discharged together with the fluidized medium and rubble from the bottom of the fluidized-bed reactor without being vaporized.
  • the discharged substances are supplied to a classifier, and classified into large size incombustibles containing metals on the screen and the small-size fluidized medium under the screen.
  • Valuables such as metals are sorted out from the incombustibles, and the fluidized medium is returned to the fluidized-bed reactor.
  • the fluidized-bed reactor has a larger diameter portion above the fluidized-bed which is called "freeboard". The freeboard serves to prevent carrying-out of the fluidized medium and char and to suppress pressure fluctuations .
  • a part of the gasifying agent is supplied into the freeboard to gasify gas and char in the freeboard at a temperature ranging from 600 to 950°C, and the fluidized bed is kept at a temperature ranging 450 to 650°C to recover metals, having a relatively low melting point, such as aluminum.
  • the gasification of the substances is carried out at a temperature of 1200°C or higher in the subsequent high-temperature combustor, thus producing gas mainly composed of H 2 , CO, C0 2 , N 2 and H 2 0. If air is not used as a gasifying agent, N 2 is not contained in the produced gas .
  • Ash content is converted into molten slag which is in turn discharged from the bottom of the gasification chamber and quenched by contacting with water in the cooling chamber, and the granulated slag is utilized as aggregate or other construction materials.
  • FIG. 8 shows the pyrolysis characteristics of RDF in a nitrogen gas atmosphere.
  • gaseous components including gas and tar as much as possible and solid components including combustible materials and ash content as little as possible.
  • Solid components namely char, have small diameter, are conveyed to the high-temperature combustor with the upward flow of the generated gas in the fluidized-bed reactor, but solid components having a large diameter is discharged together with incombustibles from the bottom of the reactor.
  • the generating ratio of solid components increases. If the generating ratio of solid components is high, the amount of the solid components discharged from the bottom of the reactor must be increased to prevent the solid components from being accumulated in the fluidized-bed. Solid components discharged from the reactor is reused after removing sand and incombustibles therefrom, but it is desirable to reduce the amount of solid components discharged from the reactor. Further, the reaction rate of pyrolysis becomes extremely slow at a temperature of 450 °C or less, and undecomposed materials tend to be accumulated on the fluidized-bed, and hence operation of the fluidized-bed reactor becomes difficult. Conversely, as the fluidized-bed temperature increases, the generating ratio of solid components decreases to be favorable for gasification of the wastes.
  • the critical temperature which does not cause the above phenomena depends on the wastes and kind of the fluidized medium, and is around 950°C. Consequently, the maximum fluidized-bed temperature is set to 950°C.
  • the wastes contain metals, and it is important to recover metals in a non-corroded condition suitable for recycling.
  • metals in order to recover aluminum having a melting point of 660°C, the fluidized-bed temperature is required to be lower than the melting point of aluminum.
  • gasification is carried out under a pressure ranging from 5 to 90 atm. However, it can be considered that gasification is carried out under atmospheric pressure and generated gas refining after a CO conversion is carried out under a pressure ranging from 30 to 40 atm.
  • a gasifying agent used in the fluidized-bed reactor a mixture of pure oxygen gas (0 2 ), obtained by low-temperature separation of air, and steam is generally used, but C0 2 recovered by an acid gas removal may be added to oxygen gas. Nitrogen gas obtained by low-temperature separation of air may be used in synthesis of ammonia (NH 3 ). Alternatively, air may be used as a part of gasifying agent.
  • solid fuel such as coal or petroleum coke having a high calorie and a stable property which is actually used for producing H 2 may be added to the wastes. That is, by adding coal, petroleum coke or heavy oil to the wastes so that it is contained at 20 to 40% of the whole, materials for gasification can be made stable both in quality and in quantity.
  • the quality of the wastes is lowered due to some cause during operation, and the concentration of H 2 or CO in the produced gas is lowered, the property of gas can be stable by increasing a mixing ratio of the solid fuel.
  • Coal used in the system is not low-grade coal which belongs to the wastes but a sub-bituminous coal or bituminous coal having high degrees of coalification.
  • FIG. 7 shows a reference example of a gasification and high-temperature combustion system used for incinerating, i.e. completely combusting, the wastes.
  • the apparatus shown in FIG. 7 includes a hopper 1, a constant feeder 2 for feeding wastes , and a fluidized-bed reactor 3 having a fluidized-bed 4 therein.
  • the fluidized-bed reactor 3 has a freeboard 5 and a burner 6, and is connected to a trommel 7 which is connected to a bucket conveyor 8.
  • the apparatus further includes a swirling-type high-temperature combustor 9 having a primary combustion chamber 10, a secondary combustion chamber 11 and a slag separation chamber 12.
  • the swirling-type high-temperature combustor 9 has burners 13.
  • FIG. 1 The apparatus shown in FIG. 7 includes a hopper 1, a constant feeder 2 for feeding wastes , and a fluidized-bed reactor 3 having a fluidized-bed 4 therein.
  • the fluidized-bed reactor 3 has a freeboard 5 and a burner 6, and is connected to a trommel 7 which is connected to a bucket conveyor 8.
  • the apparatus further includes a swirling-type high-temperature comb
  • the organic wastes " a” which, if necessary, have been crushed are supplied to the hopper 1, and then supplied by a constant feeder 2 to the fluidized-bed reactor 3.
  • Air “b” as a gasifying agent is introduced into the fluidized-bed reactor 3 from a bottom thereof, forming a fluidized-bed 4 of silica sand, over a distributor in the fluidized-bed reactor 3.
  • the organic wastes "a” are charged into the fluidized-bed 4, contacted with oxygen gas in the air within the fluidized-bed 4 which is kept at a temperature ranging from 450 to 650°C, and quickly pyrolized and gasified.
  • the fluidized medium and incombustibles are discharged from the bottom of the fluidized-bed reactor 3 and fed to the trommel 7 by which the incombustibles "c" are removed.
  • the separated silica sand "d” is returned to the fluidized-bed reactor 3 through the bucket conveyor 8 from an upper end thereof.
  • the discharged incombustibles "c” contain metals .
  • the fluidized-bed 4 is kept at a temperature ranging from 500 to 600 °C so that iron, copper and aluminum can be recovered in a non-corroded condition.
  • the produced gas " e" discharged from the fluidized-bed reactor 3 is supplied into the primary combustion chamber 10 of the swirling-type high-temperature combustor 9 , and combusted at a high temperature of 1200°C or higher while being mixed with preheated air “b” " in a swirling flow thereof.
  • the combustion is completed in the secondary combustion chamber 11, and the generated exhaust gas “e.” is discharged from the slag separation chamber 12. Because of the high temperature in the swirling-type high-temperature combustor 9, ash content in the char is converted into slag mist and trapped by molten slag phase on an inner wall of the primary combustion chamber 10 by the centrifugal forces of the swirling flow.
  • the molten slag flows down on the inner wall and enters the secondary combustion chamber 11, from which slag " f" is discharged through a bottom of the slag separation chamber 12.
  • the primary and secondary combustion chambers 10 and 11 are provided with the respective burners 13 for start-up. In this manner, combustion is carried out at an air ratio of about 1.3, and conversion of ash content into molten slag are carried out.
  • FIG.1 shows a two-stage gasification system of the present invention.
  • the system shown in FIG. 1 serves to produce synthesis gas for ammonia, having a pressure ranging from 5 to 90 atm.
  • the system comprises a fluidized-bed reactor 3 and a swirling-type high-temperature combustor 17.
  • the fluidized-bed reactor 3 is connected to a rock hopper 14 which is connected to a screen 15.
  • the swirling-type high-temperature combustor 17 is also connected to a rock hopper 14 ' .
  • the screen 15 is connected to the fluidized-bed reactor 3 through a fluidized medium circulating line 16.
  • the swirling-type high-temperature combustor 17 has a high-temperature gasification chamber 18 and a cooling chamber 19 therein.
  • "a ' " represents coal or petroleum coke for a supplementary fuel
  • " g" represents a mixture of oxygen gas and air as a gasifying agent
  • "g"' represents oxygen gas.
  • the wastes "a” which have been crushed are supplied to the fluidized-bed reactor 3 at a constant rate through a rock hopper (not shown) .
  • Amixture of oxygen gas and air is introduced as a gasifying agent "g" into the fluidized-bed reactor 3 from a bottom thereof, forming a fluidized-bed 4 of silica sand over a distributor in the fluidized-bed reactor 3.
  • the wastes " a” are charged into the fluidized-bed 4 and contacted with the gasifying agent "g" within the fluidized-bed 4 which is kept at a temperature ranging from 750 to 850 °C and under a pressure of 40 atm, and are rapidly pyrolized and gasified.
  • the fluidized medium and incombustibles are discharged from the bottom of the fluidized-bed reactor 3, pass through the rock hopper 14, and then are supplied to the screen 15 by which the incombustibles "c" are separated.
  • the silica sand "d" under the screen 15 is conveyed through the fluidized medium circulating line 16 comprising a bucket conveyor, and returned to the fluidized-bed reactor 3 through a rock hopper (not shown) .
  • the discharged incombustibles "c” contain metals, and iron, copper and the like can be recovered in a non-corroded condition.
  • the generated gas "e 2 " discharged from the fluidized-bed reactor 3 is supplied into the high-temperature gasification chamber 18 of the swirling-type high-temperature combustor 17, and gasified at a high temperature of 1300 °C or higher while being contacted with the gasifying agent " g "' in a swirling flow thereof. Because of the high temperature in the swirling-type high-temperature combustor 17, ash content in the generated gas is converted into slag mist which enters into the cooling chamber 19 together with the gas. In the cooling chamber 19, the slag "f” is quenched into granulated slag, and the granulated slag is discharged to the outside of the high-temperature combustor 17 through the rock hopper 14'.
  • FIG. 2 is a schematic view showing an embodiment of the present invention, which includes a fluidized-bed reactor, a swirling-type high-temperature combustor, and peripheral equipments thereof.
  • the apparatus shown in FIG. 2 serves to produce synthesis gas having a pressure of approximately 40 atm.
  • the apparatus includes a revolving flow-type fluidized-bed reactor 3 and a swirling-type high-temperature combustor 17.
  • the apparatus shown in FIG. 2 is different from that shown in FIG. 1 in that the fluidized-bed reactor 3 is an internally circulating type, and that substances discharged from a bottom of the fluidized-bed reactor 3 are separated by a screen 15 and large size incombustibles "c" on the screen and the fluidized medium d under the screen are independently depressurized by rock hoppers 14, respectively.
  • This embodiment offers the following advantages : Even when the roughly crushed wastes are supplied to the fluidized bed, the wastes are swallowed in the bed without being accumulated on the bed.
  • the char Since the char is uniformly dispersed in the fluidized-bed, the gasification of the char is promoted.
  • the pulverization of the char is carried out by the revolving flow of the fluidized medium.
  • the large size incombustibles "c" are smoothly discharged from the fluidized bed. Since hot spots are not generated in the fluidized bed, the troubles such as agglomeration or clinker are prevented.
  • FIG.3 is a schematic view showing a two-stage gasification system, according to another embodiment of the present invention, which includes a fluidized-bed reactor, a swirling-type high-temperature combustor, and peripheral equipment thereof.
  • the apparatus shown in FIG. 3 serves to produce synthesis gas having a pressure of approximately 40 atm.
  • the apparatus shown in FIG. 3 includes a revolving flow-type fluidized-bed reactor 3 and a swirling-type high- temperature combustor 9.
  • the apparatus shown in FIG. 3 is different from that shown in FIG. 2 in that the substances discharged from the fluidized-bed reactor 3 are separated by the screen 15 after being depressurized by a rock hopper 14, and the swirling-type high-temperature combustor has two high-temperature gasification chambers 10 and 11.
  • the substances discharged from the bottom of fluidized-bed reactor after being depressurized by a rock hopper 14 which is normally used for high-temperature fine particles, are separated into the incombustibles "c" and the fluidized medium "d" by the screen 15.
  • the high-temperature combustor is not composed of a single vertically cylindrical chamber, but is composed of a combination of a vertical chamber 10 and a lateral chamber 11.
  • molten slag can stay in the combustor for a longer time, which makes it possible to reduce unburned carbon and to accelerate evaporation of metals having a low-melting point such as zinc and lead.
  • FIG. 4 is a flow diagram showing a process for producing ammonia (NH 3 ) from organic wastes according to an embodiment of the present invention.
  • the process comprises a step 100 of gasification, a step 200 of CO conversion, a step 300 of acid gas removing, a step 400 of gas refining with liquid nitrogen, a step 500 of ammonia synthesizing, and a step 600 of sulfur recovering.
  • a gasifying agent supplied to the fluidized-bed reactor a mixture of oxygen gas and steam is used.
  • An apparatus for carrying out the above process includes a gas scrubber 21, a low-temperature air separator 23, a fluidized-bed reactor 24 for carrying out a first-stage gasification of organic wastes, a high-temperature combustor 25 for carrying out a second-stage gasification at a high temperature, a CO converter 36, an absorption tower 40, a condensate tank 41, a C0 2 stripping tower 44, a H 2 S stripping tower 50, an adsorption tower 53, a liquid nitrogen scrubber 56, and a cooler 57.
  • the apparatus further includes a compressor 58 for nitrogen gas, a compressor 59 for oxygen gas, a compressor 60 for synthesis gas, an ammonia synthesis tower 62, an ammonia refrigerator 68, an ammonia separator 70, and an ammonia storage tank 72.
  • the apparatus further includes heat exchangers 38, 39, 48, 52, 64 and 66, and pumps 30, 46 and 54.
  • the symbols i, j and q represent air, oxygen gas (0 2 ) and sulfur (S), respectively.
  • Air “i” is separated into oxygen gas “j” and nitrogen gas “k” by the air separator 23.
  • the separated oxygen gas is compressed by the compressor 59, and supplied to the fluidized-bed reactor 24 and the high-temperature combustor 25 as a gasifying agent.
  • the nitrogen gas “k” is compressed by the compressor 58, and used for synthesis of ammonia.
  • a low- temperature separation method is generally used for separating air.
  • organic wastes " a" and supplementary fuel “a'” are gasified at a temperature ranging from 750 to 850°C and under a pressure of about 40 atm in the fluidized-bed reactor 24, and then gasified in the high- temperature combustor 25 at a temperature of 1200 °C or higher to generate gas containing CO, H 2 , H 2 0 and C0 2 as main components by being reacted with oxygen gas "j" and steam “m” .
  • the temperature in the high-temperature combustor 25 is mainly adjusted by controlling the feed rate of oxygen gas.
  • the high-temperature combustor 25 is of a direct-quench type, and has a high-temperature gasification chamber 18 at an upper part thereof and a cooling chamber 19 at a lower part thereof.
  • the generated gas is quenched in direct contact with water in the cooling chamber 19, and then discharged from the high- temperature combustor 25. By this quenching, a large amount of steam is generated and mixed with the generated gas .
  • Most of the slag generated in the high-temperature gasification chamber 18 is removed.
  • the slurry of the slag and water is supplied to a slag treatment process (not shown) .
  • the generated gas which is accompanied by the large amount of steam, is discharged from the cooling chamber 19, and cleaned in a venturi scrubber (not shown) and then the gas scrubber 21 to remove the dust therefrom. Thereafter, the gas is supplied to the step 200 of CO conversion.
  • the scrubbing water in the bottom of the water scrubber 21 is supplied to the cooling chamber 19 by the circulating pump 30, and the part of the scrubbing water is supplied to the slag treatment process (not shown).
  • the gas containing steam from the step 100 of gasification is supplied to the step 200 of CO conversion.
  • the gas from the water scrubber 21 is preheated by the heat exchange with a gas from a first-stage catalyst bed to a temperature suitable for the CO conversion by the heat exchanger 38, and then supplied to the CO converter 36.
  • CO converter 36 carbon monoxide (CO) in the gas reacts with the accompanied steam (H 2 0) in the presence of catalyst to produce hydrogen gas (H 2 ) and carbon dioxide (C0 2 ) .
  • the CO converter 36 comprises two-stage catalyst beds.
  • the inlet gas temperature of the first-stage catalyst bed is 300°C as an example and the exit gas temperature of the first-stage catalyst bed is 480°C as an example.
  • the inlet gas temperature of the second-stage catalyst bed is 300 °C as an example.
  • the total conversion ratio in the first- and second- stage catalyst beds is 90% or more, and the concentration of CO in the dry gas from the CO converter 36 is 1 to 2% .
  • the gas passing through the CO converter 36 is cooled by the heat exchanger 39 to approximately 40 °C, and separated in the condensate tank 41 into condensed water and gas, and then cooled to -17 °C by the heat exchange with a part of purified gas from the top of the liquid nitrogen scrubber 56. Thereafter, the cooled gas is supplied to the step 300 of acid gas removing in which a physical absorption process, i.e. Rectisol process, is carried out to remove impurities including hydrogen sulfide (H 2 S), carbonyl sulfide (COS) and carbon dioxide (C0 2 ), from the gas supplied from the step 200 of CO conversion.
  • a physical absorption process i.e. Rectisol process
  • the gas cooled to -17 °C is introduced into the absorption tower 40 in which acid gas is absorbed by being contacted with liquid methanol of approximately -60°C countercurrently.
  • the gas discharged from the absorption tower 40 contains carbon dioxide (C0 2 ) ranging from 10 to 20 ppm and hydrogen sulfide (H 2 S) of approximately 0.1 ppm.
  • C0 2 carbon dioxide
  • H 2 S hydrogen sulfide
  • Hydrogen (H 2 ) and carbon monoxide (CO) in addition to carbon dioxide (C0 2 ) and hydrogen sulfide (H 2 S) are dissolved in the methanol drawn from the absorption tower 40.
  • the methanol In order to recover hydrogen (H 2 ) and carbon monoxide (CO) from the methanol, the methanol is released its pressure to vaporize hydrogen (H 2 ) and carbon monoxide (CO) therefrom.
  • the vaporized hydrogen and carbon monoxide are compressed by a compressor for recirculation.
  • the methanol is supplied to the C0 2 stripping tower 44, and depressurized therein and stripped by nitrogen gas, whereby carbon dioxide (C0 2 ) in the methanol is mostly vaporized, and recovered, if necessary.
  • the recovered carbon dioxide may be used for synthesis of urea or production of liquid carbon dioxide.
  • the methanol containing condensed hydrogen sulfide (H 2 S) is taken out from the bottom of the C0 2 stripping tower 44 and supplied to the heat exchanger 48 by the pump 46. After preheating by the heat exchanger 48, the methanol is supplied to the H 2 S stripping tower 50 in which it is indirectly regenerated by steam. Hydrogen sulfide enriched gas discharged from the top of the H 2 S stripping tower 50 is cooled by the heat exchanger 52, and then supplied to the step 600 of sulfur recovering in which sulfur "q" is recovered. The methanol drawn from the bottom of the H 2 S stripping tower 50 is cooled and is supplied to the top of the absorption tower 40 by the circulating pump 54.
  • H 2 S condensed hydrogen sulfide
  • the supplied gas containing a trace amount of carbon monoxide (CO), carbon dioxide (C0 2 ), argon (Ar) and methane (CH 4 ) is cleaned with supercooled liquid nitrogen to thereby remove such gases.
  • Hydrogen gas is not absorbed by the liquid nitrogen, because hydrogen gas has a lower boiling point than nitrogen gas. Therefore, purified hydrogen enriched gas containing nitrogen gas is obtained from the top of the liquid nitrogen scrubber 56.
  • the purified gas from the top of the liquid nitrogen scrubber 56 is mixed with nitrogen gas having high pressure which is compressed by the compressor 58 after passing through the cooler 57 so that the molar ratio of hydrogen gas to nitrogen gas is adjusted to approximately 3 suitable for ammonia synthesis , and the mixed gas is supplied to the step 500 of ammonia synthesizing.
  • a part of nitrogen gas compressed by the compressor 58 is cooled and liquefied by the cooler 57, and supplied to the liquid nitrogen scrubber 56, in which the supplied nitrogen gas contacts with the gas supplied from the bottom of the liquid nitrogen scrubber 56 countercurrently, and impurities including carbon monoxide (CO), carbon dioxide (C0 2 ), argon (Ar) and methane (CH4) in the gas are absorbed by liquid nitrogen, and removed.
  • the liquid nitrogen which has absorbed the impurities such as carbon monoxide (CO) , carbon dioxide (C0 2 ) , argon (Ar) and methane (CH4) is drawn from the bottom of the liquid nitrogen scrubber 56, and depressurized and used as a fuel for a boiler.
  • the gas supplied from the gas refining step 400 is compressed to a pressure of 150 atm as an example in the first-stage of the compressor 60, and then the compressed gas is mixed with the recirculating gas from the ammonia separator 70. Thereafter, the mixed gas is compressed to a pressure of 165 atm in the second-stage of the compressor 60, and then supplied to the ammonia synthesis tower 62.
  • the ammonia synthesis tower has two-stage catalyst beds composed of Fe- base catalyst.
  • the inlet gas of the ammonia synthesis tower 62 has a pressure of 164 atm and a temperature of 250°C.
  • the ammonia synthesis reaction is carried out while the synthesis gas passes through the catalyst beds.
  • N 2 + 3H 2 2NH 3 While the gas passes through the catalyst beds, its temperature exceeds 500°C once, however, it is cooled by the cooled recirculating gas introduced into the ammonia synthesis tower 62.
  • the ammonia from the ammonia synthesis tower 62 has a pressure of 160 atm and a temperature of 450°C.
  • the ammonia is cooled to around room temperature by the heat exchangers 64 and 66, and further cooled by the ammonia refrigerator 68, and hence most of ammonia is condensed.
  • the condensed ammonia is separated into liquid ammonia and gas in the ammonia separator 70, and the liquid ammonia is fed to the ammonia storage tank 72.
  • the separated gas is supplied to the second-stage of the compressor
  • the mixture of oxygen gas and steam is used as the gasifying agent.
  • the gasifying agent is not limited to the above, and a mixture of air and oxygen gas can also be used.
  • the amount of air depends on the amount of nitrogen gas required for synthesis of ammonia. Since the produced gas includes nitrogen gas required for the ammonia synthesis, a methanation process is preferred to the gas refining process with liquid nitrogen.
  • FIG. 5 is a block diagram showing a process in which the produced gas obtained by two-stage gasification of the wastes is separated into hydrogen gas and residual gas and the thus obtained residual gas is reused in a fluidized-bed reactor 110 as a fluidizing gas.
  • the process comprises a primary gasification in a fluidized-bed reactor 110, a secondary gasification in a swirling-type high-temperature combustor 112, a water scrubber 114, an acid gas removing step 116, a CO conversion step 118, a hydrogen gas separation step 120, and a circulating gas compressor 122.
  • " a" represents wastes
  • " g ' " represents oxygen gas.
  • the wastes crushed to a desired size is supplied above the fluidized-bed of hard silica sand in the low-temperature fluidized-bed reactor 110.
  • oxygen gas "g ' " and a fluidizing gas are supplied to the lower part of the fluidized-bed reactor 110.
  • the fluidized-bed temperature is maintained at a temperature ranging from 450 to 950°C. Under such condition, the wastes are quickly pyrolyzed and gasified by a partial oxidation.
  • gas, tar and char are produced.
  • Most of tar and char is carried with the upward flow of the generated gas and introduced into the swirling-type high-temperature combustor 112, and is decomposed into unrefined gas mainly composed of carbon monoxide(CO) , carbon dioxide(C0 2 ) , hydrogen gas (H 2 ) , and water(H 2 0) by a partial oxidation therein at a temperature of 1350°C and under a pressure of 40 atm.
  • the high temperature unrefined gas is quenched in the cooling chamber at the lower part of the swirling-type high-temperature combustor 112, and then scrubbed to remove impurities such as hydrogen chloride (HCl)and dust in the water scrubber 114.
  • impurities such as hydrogen chloride (HCl)and dust in the water scrubber 114.
  • acid gas such as carbon dioxide(C0 2 ) , hydrogen sulfide(H 2 S) and carbonyl sulfide (COS) is removed from the gas.
  • CO and H 2 0 are converted in the presence of catalyst into H 2 and C0 2 by CO conversion reaction. If necessary, the steam used for the CO conversion is added to the gas at a saturator (not shown) in the carbon monoxide conversion step 118.
  • the desulfurized gas is supplied to the CO conversion step, either high-temperature conversion catalyst (Fe-base) or low-temperature catalyst (Cu-base) may be used as CO conversion catalyst, thus improving the CO conversion rate.
  • the refined gas from the CO conversion step 118 which is composed of H 2 , C0 2 , H 2 0 and a small amount of CO, is separated into high purity of H 2 and residual gas mainly composed of C0 2 and CO by either a pressure swing adsorption method or a hydrogen gas separation membrane method.
  • the residual gas is compressed by the circulating gas compressor 122, and then supplied to the fluidized-bed reactor 110 together with oxygen gas g' from the bottom thereof as a part of fluidizing gas.
  • the running cost of the plant increases.
  • the produced gas contains a large amount of nitrogen gas.
  • the residual gas is preferably reused as a part of gasifying agent.
  • the N 2 from an air separation apparatus (not shown) is added to the H 2 gas separated in the hydrogen separation step 120, and sent to the ammonia synthesis step.
  • the H 2 can be taken out from the hydrogen separation step 120 without N 2 being added.
  • the amount of inert gas other than N 2 and H 2 is as small as possible to reduce the amount of purge gas .
  • the produced gas contains a large amount of hydrocarbon.
  • the produced gas is partially-combusted and reacts with steam in the swirling-type high-temperature combustor 112 to be converted into CO, C0 2 , H 2 and H 2 0.
  • the gasification temperature in the swirling-type high-temperature combustor 112 is not high enough, the produced gas discharged from the swirling-type high-temperature combustor 112 contains unreacted hydrocarbon such as CH 4 or C 2 H 4 .
  • the unreacted hydrocarbon serves as the inert gas in the ammonia synthesis step. Therefore, in order to reduce the amount of the unreacted hydrocarbon, the gasification temperature in the swirling-type high-temperature combustor 112 is preferably 1300°C or higher.
  • FIG. 6 is a block diagram showing another embodiment of FIG.5 in the present invention.
  • the process comprises a lst-stage gasification in a fluidized-bed reactor 110, a 2nd-stage gasification in a swirling-type high-temperature combustor 112, a water scrubber 114, an acid gas removing step (1st) 116, a CO conversion step 118, an acid gas removing step (2nd) 121, and a circulating gas compressor 122.
  • a represents wastes
  • "g ' " represents oxygen gas.
  • the wastes "a” crushed to a desired size is supplied above the fluidized-bed of hard silica sand in the fluidized-bed reactor 110.
  • the internal pressure of the fluidized-bed reactor 110 is about 40 atm.
  • the fluidized-bed temperature is maintained at a temperature ranging from 450 to 950°C. Under such condition, the wastes are quickly pyrolyzed and gasified by a partial oxidation.
  • gas, tar and char are produced.
  • Most of the char is pulverized and carried with the upward flow of the gas, and introduced into the high-temperature combustor 112, and is decomposed into unrefined gas mainly composed of CO, C0 2 , H 2 and H 2 0 by a partial oxidation therein at a temperature of 1350°C and under a pressure of 40 atm.
  • the high temperature unrefined gas is quenched in the cooling chamber at the lower part of the swirling-type combustor 112, and then scrubbed to remove impurities such as hydrogen chloride(HCl) and dust in the water scrubber.
  • acid gas removing step (1st) 116 acid gas such as C0 2 , H 2 S and COS is removed from the gas.
  • CO conversion step 118 C0 2 and H 2 0 are converted in the presence of catalyst to H 2 and C0 2 by CO conversion reaction.
  • the steam used for the CO conversion is added to the gas at a saturator (not shown) in the CO conversion step 118.
  • C0 2 is removed in the acid gas removing step (2nd) 121 to obtain gas mainly composed of H 2 .
  • C0 2 removed in the acid gas removing step 121 is compressed by the circulating gas compressor 122, and then supplied to the bottom of the fluidized-bed reactor 110 together with oxygen "g'" as a part of fluidizing gas.
  • the obtained gas mainly composed of H 2 may be taken out without N 2 being added.
  • H 2 after N 2 is added, is sent to the ammonia synthesis step to produce ammonia.
  • the usage and application of the obtained H 2 gas is not limited.
  • the method and apparatus for treating wastes by two-stage gasification according to the present invention offers the following advantages :
  • Hydrogen gas which is a material for ammonia (NH 3 ) can be produced from organic wastes which are inexpensive and available in our own country. Thus, production cost of hydrogen gas is remarkably reduced.
  • Metals such as iron or copper can be recovered in a non-corroded condition suitable for recycling.
  • gasification facilities, hydrogen gas producing facilities and ammonia synthesis facilities are constructed adjacently to one another, and thus combined organically in respect to utilization of materials to enhance functions of all the facilities as a total system.
  • the gasification facilities can be operated stably against deterioration in property of produced gas by increasing mixing ratio of the supplementary fuel. 5.
  • the gas produced in the two-stage gasification is refined and separated into hydrogen gas and the residual gas including carbon monoxide and carbon dioxide, and the thus obtained residual gas can be utilized as a fluidizing gas in the fluidized-bed reactor. Therefore, shortage of fluidizing gas caused by plant scaleup can be solved.
  • the present invention is suitable for a waste treatment system in which wastes such as municipal wastes, plastic wastes, or biomass wastes are treated by two-stage gasification to recover metals or ash content in the wastes in such a state that they can be recycled and gases mainly composed of carbon monoxide (CO) and hydrogen gas (H 2 ) for use as synthesis gas of hydrogen gas or ammonia (NH 3 ).
  • wastes such as municipal wastes, plastic wastes, or biomass wastes
  • gases mainly composed of carbon monoxide (CO) and hydrogen gas (H 2 ) for use as synthesis gas of hydrogen gas or ammonia (NH 3 ).

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Abstract

Procédé et dispositif servant à traiter des déchets par gazéification en deux étapes et permettant de récupérer la teneur en métaux ou en cendres des déchets, de façon à pouvoir les recycler, ainsi que les gaz contenant de l'oxyde de carbone (CO) et de l'hydrogène gazeux (H2) afin de les utiliser en tant que gaz de synthèse d'ammoniac (NH3) ou pour produire de l'hydrogène gazeux. On gazéifie ces déchets dans un réacteur à lit fluidisé (3) à basse température. Puis on introduit le matériau gazeux et le produit de carbonisation obtenus dans le réacteur à lit fluidisé (3) dans une chambre de combustion (17) à température élevée, dans laquelle ils sont gazéifiés à température élevée, et on convertit la teneur en cendres en scories en fusion. Après épuration à l'eau et réaction de conversion de CO, on sépare le gaz en H2 et en gaz résiduel. On alimente ensuite le réacteur à lit fluidisé (3) en gaz résiduel en tant que gaz fluidisant.
PCT/JP1997/003814 1997-04-22 1997-10-22 Procede et dispositif servant a traiter des dechets par gazeification WO1998047985A1 (fr)

Priority Applications (2)

Application Number Priority Date Filing Date Title
EP97909579A EP0979262B1 (fr) 1997-04-22 1997-10-22 Procede et dispositif servant a traiter des dechets par gazeification
DE69730870T DE69730870T2 (de) 1997-04-22 1997-10-22 Verfahren und vorrichtung zur behandlung von abällen durch vergasung

Applications Claiming Priority (2)

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JP9/117434 1997-04-22
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WO2007048058A2 (fr) 2005-10-21 2007-04-26 Taylor Biomass Energy, Llc Procede et systeme de gazeification associee a une extraction de goudron in-situ
WO2010006584A2 (fr) * 2008-07-12 2010-01-21 Dinano Ecotechnology Llc Procédé de production de diesel synthétique
EP2285939A1 (fr) * 2008-05-15 2011-02-23 Enersol Power Llc Système de gazéification d un matériau organique amélioré par un courant de chaleur rayonnante
CN103429335A (zh) * 2011-01-19 2013-12-04 沙特***石油公司 包括对重质烃原料的超临界水处理和硫吸附的方法
CN114074919A (zh) * 2020-08-13 2022-02-22 国家能源投资集团有限责任公司 城市垃圾转化生产氢气的方法

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WO2007048058A2 (fr) 2005-10-21 2007-04-26 Taylor Biomass Energy, Llc Procede et systeme de gazeification associee a une extraction de goudron in-situ
EP1940736A2 (fr) * 2005-10-21 2008-07-09 Taylor Biomass Energy, LLC Procede et systeme de gazeification associee a une extraction de goudron in-situ
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EP2285939A1 (fr) * 2008-05-15 2011-02-23 Enersol Power Llc Système de gazéification d un matériau organique amélioré par un courant de chaleur rayonnante
EP2285939A4 (fr) * 2008-05-15 2012-12-05 Enersol Power Llc Système de gazéification d un matériau organique amélioré par un courant de chaleur rayonnante
WO2010006584A2 (fr) * 2008-07-12 2010-01-21 Dinano Ecotechnology Llc Procédé de production de diesel synthétique
WO2010006584A3 (fr) * 2008-07-12 2010-07-22 Dinano Ecotechnology Llc Procédé de production de diesel synthétique
CN103429335A (zh) * 2011-01-19 2013-12-04 沙特***石油公司 包括对重质烃原料的超临界水处理和硫吸附的方法
CN114074919A (zh) * 2020-08-13 2022-02-22 国家能源投资集团有限责任公司 城市垃圾转化生产氢气的方法

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CN1137249C (zh) 2004-02-04
DE69730870D1 (de) 2004-10-28
CN1253577A (zh) 2000-05-17
EP0979262B1 (fr) 2004-09-22
ES2229339T3 (es) 2005-04-16
DE69730870T2 (de) 2005-09-29

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