Classifications

• • C—CHEMISTRY; METALLURGY
  • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
  • C10B—DESTRUCTIVE DISTILLATION OF CARBONACEOUS MATERIALS FOR PRODUCTION OF GAS, COKE, TAR, OR SIMILAR MATERIALS
  • C10B49/00—Destructive distillation of solid carbonaceous materials by direct heating with heat-carrying agents including the partial combustion of the solid material to be treated
  • C10B49/16—Destructive distillation of solid carbonaceous materials by direct heating with heat-carrying agents including the partial combustion of the solid material to be treated with moving solid heat-carriers in divided form
• • C—CHEMISTRY; METALLURGY
  • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
  • C10B—DESTRUCTIVE DISTILLATION OF CARBONACEOUS MATERIALS FOR PRODUCTION OF GAS, COKE, TAR, OR SIMILAR MATERIALS
  • C10B57/00—Other carbonising or coking processes; Features of destructive distillation processes in general
  • C10B57/18—Modifying the properties of the distillation gases in the oven
• • 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

Definitions

• the invention relates to a method for the gasification of organic substances and substance mixtures according to the preamble of claim 1.
• Pyrolysis gases with condensable substances and solid carbonaceous residues are implemented.
• the thermal energy required for pyrolysis is generated by burning the solid carbon-containing residue.
• the tar-containing pyrolysis gases become like this in a second reaction zone
• both the pyrolysis and the combustion of the solid carbon-containing residue take place in a fluidized bed.
• a reaction zone for the tar-containing pyrolysis gases is provided in the upper part of the pyrolysis fluidized bed reactor.
• the heat transfer medium, together with the solid carbon-containing residue, is discharged in part via the reactor head of the pyrolysis fluidized bed reactor and the remainder via a line which is arranged at the upper boundary of the fluidized bed and fed to the fluidized bed furnace. There the solid carbonaceous residue is burned and the heat transfer medium is heated.
• the heated heat transfer medium and the ash are discharged together with the exhaust gas from the fluidized bed furnace and separated in a gas-solid separator arranged above the pyrolysis fluidized bed reactor and fed to the reaction zone of the pyrolysis reactor, from which they fall again into the fluidized bed of the pyrolysis reactor ( Heat transfer medium circuit).
• the operation of the fluidized beds is very complex and it is hardly possible to control the reactions of the pyrolysis gases in the reaction zone.
• the invention has for its object to provide an easy to perform method for generating a gas with a high calorific value. A low proportion of condensate is preferred. Another object of the invention is to provide a simple device for carrying out the method.
• this object is achieved by the combination of features of claim 1.
• a reactant such as water vapor
• a reactant such as water vapor
• they are passed into an indirect heat exchanger in which the pyrolysis gases react with the reactant.
• the solid carbonaceous residue and the heat transfer medium are fed to a furnace.
• the combustion gases are passed through the indirect heat exchanger in such a way that their content is used for the reaction of the pyrolysis gases with the reactant.
• the ash of the solid carbon-containing residues drawn off from the furnace and the heat transfer medium are returned to the pyrolysis reactor at the end of the entry for the organic matter.
• the invention is based on the basic idea of dividing the gasification process into three simple process steps.
• a first process step the feed materials are rapidly pyrolysed.
• the aim is to keep as few condensable substances in the pyrolysis gases as possible.
• the rapid pyrolysis is ensured in that the pyrolysis of the starting materials is carried out at a temperature of 550 ° to 650 ° C.
• the pyrolysis gases are heated and reacted with steam to adjust the product gas quality.
• the reaction of the pyrolysis gases with water vapor is carried out at a temperature of 900 ° to 1000 ° C.
• the solid carbon-containing pyrolysis residues are burned.
• the heat generated is used for pyrolysis and the reaction of the pyrolysis gases with water vapor.
• the heat transfer medium is also heated in the furnace, which is subsequently conveyed back into the pyrolysis reactor.
• the heat transfer for the reaction of the pyrolysis gases with water vapor takes place in a heat exchanger which is heated by the exhaust gases from the furnace.
• each process step and the combination of the process steps can be designed according to the objective of the product gas quality.
• the primary goal in product gas quality is a high calorific value.
• the hydrogen content is increased by the second process step, so that the product gas is very well suited for use as synthesis gas, and energetic use in connection with a fuel cell is also an option.
• the use for energy generation via a gas engine or gas turbine is of course possible.
• the reactant is water vapor.
• the addition of water vapor can be dispensed with if there is sufficient water vapor in the feedstock, for example if the feedstock does not dry or only to a small extent. It is also possible that the pyrolysis gases formed contain enough water vapor if enough water vapor is generated by the nature of the starting material in the pyrolysis. It is also possible to add water vapor in the pyrolysis stage.
• the feedstocks must be pretreated before they are sent to pyrolysis. Pretreatment is generally limited to drying and, if necessary, comminution. No great demands are made on the lumpiness of the starting material, since the pyrolysis is carried out in a moving bed with a heat transfer medium.
• a catalyst can be provided in the reaction of the pyrolysis gases with water vapor.
• Dolomite, calcite, nickel, nickel oxide, nickel aluminate or nickel spinel are preferably used as catalysts.
• dolomite it is advantageous that the dolomite is calcined at the reaction temperature of 900 ° to 1000 ° C. and that the calcium / magnesium oxide formed has particularly high catalytic activity.
• reaction temperature of 900 to 1000 ° C for the reaction of the pyrolysis gas with water vapor is advantageous because the sulfur sensitivity of the aforementioned catalysts is already greatly reduced in this temperature range. It is possible to regenerate the catalysts from time to time in situ by adding a little air at temperatures above 1000 ° C.
• the catalysts can also be used as a heat transfer medium. This procedure has the advantage that the
• Catalysts are periodically regenerated in the heat transfer circuit.
• part of the pyrolysis gas can be burned for heat generation.
• the combustion of part of the pyrolysis gas for heat generation is also necessary if the pyrolysis coke can be used as a material, e.g. B. for the production of activated carbon or charcoal or charcoal briquettes. So that the pyrolysis coke can be easily discharged, the grain size of the heat transfer medium is chosen so small that the heat transfer medium can be separated from the pyrolysis coke without any problems. Simple and inexpensive components which are known per se and are readily available can be used in the device according to the invention. The device according to the invention can be easily constructed with these components.
• the pyrolysis takes place in a moving bed reactor with the aid of a heat transfer medium.
• a shaft furnace is the first choice, to which the mixture of the feed material to be gasified and the heat transfer medium is fed from above. The mixture travels through the shaft furnace. Fast pyrolysis takes place due to the intimate contact of the feed material with the heat transfer medium.
• the pyrolysis can also be carried out in a rotating drum or in a deck oven, but here too the outlay on equipment would be greater.
• the mixture of the heat transfer medium and the pyrolysis residue can be transferred to the furnace using commercially available units such as screw conveyors, swivel gratings, rotary gratings or rotary feeders.
• screw conveyors In connection with grate firing, however, the use of feed tappets is preferred.
• underfeed firing the use of screw conveyors is preferred.
• Grate firing is preferred as the firing.
• the combustion gases are passed through an indirect heat exchanger, which also serves as a chemical reactor, in which the pyrolysis react with water vapor.
• Such heat exchangers are known, for example, in refineries as tube cracking furnaces or reformers.
• conveying elements such as vibrating troughs, bucket elevators or chain scraper conveyors can also be used to convey the heat transfer medium from the furnace into the shaft furnace.
• the requirements for the conveyor technology correspond to the requirements that occur in the steel industry or in the coke oven sector, so that no additional effort is required for the design of the units.
• the heat transfer medium must have sufficient mechanical, chemical and thermal stability in the temperature range from 600 to 1000 ° C. Fireproof materials such as sand, gravel, grit, aluminum silicates, corundum, greywacke, quartzite or cordierite are primarily used. The use of moldings made of metallic or non-metallic materials or combinations thereof, such as Steel or ceramic balls are also possible.
• the heat transfer medium must be fine enough to make intimate contact with the feed so that good heat transfer can take place.
• the particles of the heat transfer medium must be large enough that there is sufficient void volume through which the pyrolysis gases can flow.
• the heat transfer medium has a grain size of 1 - 40 mm.
• This grain size also has the advantage that the heat transfer medium can be easily separated from the ashes of the pyrolytic residue behind the furnace.
• a catalyst can be provided in the reaction of the pyrolysis gases with water vapor.
• a catalyst bed can be arranged in the heat exchanger.
• the catalyst bed is arranged inside or outside the tubes of the heat exchanger.
• a catalytically active material for the heat exchanger tubes such as. B. use corundum with nickel or nickel oxide. It is also possible behind the
• Heat exchanger to provide a fixed bed reactor with catalyst bed.
• reaction of the pyrolysis gases with steam is to be supported by a catalyst, it is recommended to dedust the hot pyrolysis gases with a filter before contact with the catalyst.
• 1 shows a block diagram of the method according to the invention
• 2 shows the mass and energy balance of the pyrolysis and reaction stages
• Fig. 3 shows the mass and energy balance of the furnace
• Fig. 4 is a schematic representation of an apparatus for performing the method according to the invention.
• the starting material can be a drying and / or comminuting device in which the starting materials are processed for the subsequent pyrolysis.
• the pretreated feed 1 is introduced into a pyrolysis 3.
• the pyrolysis 3 leaves a pyrolysis gas 5 and a pyrolysis coke 5a.
• the pyrolysis coke 5a is burned in a furnace 6.
• the heat from the furnace 6 is fed to the pyrolysis 3 via a heat coupling 7 and to a reaction zone 4 for pyrolysis gas via a heat coupling 7a.
• Furnace 6 are cooled and derived in a flue gas cleaning and cooling stage 17.
• the waste heat obtained with the flue gas cleaning and cooling stage 17 can e.g. B. can be used for drying in pretreatment stage 2.
• a feed water 9 is passed via a water treatment 10 and a pump 11 in a heat exchanger 12 which is arranged in the furnace 6.
• the generated steam 16 is passed into the reaction zone 4.
• a part that is not required can be expanded via a turbine 13 and further used as exhaust steam 16a.
• the pyrolysis gas 5 is fed to the reaction zone 4 with the water vapor 16.
• the pyrolysis gas and the cracked products of the condensables are reacted with steam to the desired product gas 15.
• the product gas 15 is then cleaned in a dedusting 8 and a fine dedusting and quench 14. It is also possible to supply part 19 of the product gas 15 to the pyrolysis 3.
• FIG. 2 shows the mass and energy balance of a pyrolysis stage 101 and a reaction stage 102 using the example of wood gasification.
• Wood 104 and heat transfer medium 104a are introduced into pyrolysis stage 101.
• the heat flow purple which results from the size and nature of the material flows from wood 104 and heat transfer medium 104a and the desired pyrolysis temperature, is added.
• the pyrolysis stage 101 leaves a mixture 105 of charcoal and heat transfer medium and the pyrolysis gas 106.
• the pyrolysis gas 106 enters the reaction stage 102.
• Heat loss 108 also occurs.
• the heat of reaction of charcoal formation 109 and water vapor 112 is also conducted into reaction stage 102.
• the product gas 107 leaves the reaction stage 102.
• a heat loss 110 also occurs.
• the quantity of heat 111 still to be supplied results from the heat and material flows that are supplied or removed.
• FIG. 3 shows the mass and energy balance of the charcoal furnace 103. The mixture flows
• the heat flows that emerge are the heat flow 111, which is led into the reaction stage 102, the heat flow purple, which is led into the pyrolysis stage 101, the excess heat 114 and the heat loss 115.
• FIG. 4 shows a device for carrying out the method according to the invention.
• a feedstock 401 is metered into a shaft furnace 403 via a lock 402.
• a heat transfer medium 414 is fed from a conveyor 409 to the shaft furnace 403 via a lock 410.
• the feedstock 401 and the heat transfer medium 414 migrate downward and mix, the heat contained in the heat transfer medium 414
• Feedstock 401 is pyrolyzed at about 600 ° C.
• the mixture of the heat transfer medium 414 and the pyrolysis coke 426 formed from the insert material 401 by pyrolysis is passed through a loading device 404 onto a grate 405 of a bricked-up furnace 407.
• the furnace 407 has a start-up burner 406.
• the pyrolysis coke 426 burns out on the grate 405, giving off heat. This heats the heat transfer medium 414 to approx. 1000 ° C.
• the heat transfer medium 414 consists of a coarse-grained material such as sand, gravel or split.
• Part of this mixture of heat transfer medium 414 and ash is returned via conveyor 409 and lock 410 into shaft furnace 403, in which heat transfer medium 414 releases the heat absorbed in furnace 407 to feed 401.
• a smaller part of the mixture of ash from the pyrolysis coke 426 and the heat transfer medium 414 is discharged via a cooling 411 and a sieve 412.
• the ashes of the pyrolysis coke 426 are separated as fine material 413 by the sieve 412 from the coarser heat transfer medium 414, the heat transfer medium 414 being returned to the process. This removal is not necessary if the feed material to be gasified contains no ash-forming components.
• Pyrolysis gas is withdrawn from the upper region of the shaft furnace 403 via a line 403a and passed into a heat exchanger 417.
• the pyrolysis gas also contains higher hydrocarbons and tars and other organic, in particular aromatic, compounds as condensable constituents.
• the heat exchanger 417 is heated to a temperature of approximately 950 ° C. by the exhaust gases from the furnace 407. At this temperature, the pyrolysis gas and the condensable substances react with water vapor contained in the pyrolysis gas.
• water vapor 416 is fed into line 403a for the reactions in heat exchanger 417.
• air 415 can also be supplied for a partial combustion of the pyrolysis gas.
• a catalyst can be provided in the heat exchanger to improve the cracking of the tars carried along.
• a product gas leaves the heat exchanger 417, the proportions of carbon monoxide and hydrogen have been maximized.
• This gas is passed through a heat exchanger 421 for waste heat use and into a scrubber 422 for gas cleaning.
• a product gas 425 is drawn off via an induced draft fan 423.
• the waste heat from the heat exchanger 421 can be used to heat the pyrolysis gas to the reaction temperature for the reaction with water vapor.
• Both the furnace 407 and the heat exchanger 417 are operated at a pressure which deviates only slightly from the atmospheric pressure and is generally somewhat lower than this.
• the induced draft fans 423 for the product gas 425 and 420 for the exhaust gas 424 are regulated and matched to one another in such a way that the pyrolysis gas is passed through the heat exchanger 417 and not through the bed of the
• the wood contains 3% ash (anhydrous) and otherwise consists essentially of 50% carbon, 6% hydrogen, 42% oxygen and 1.9% nitrogen, free of water and ash.
• the upper calorific value is 17.9 MJ / kg when anhydrous.
• the thermal carburetor output is 4.97 MW.
• the pyrolysis is carried out at 600 ° C. and the reaction with steam at 950 ° C.
• the working pressure is atmospheric pressure. Gravel with a grain size of 3 mm to 15 mm is used as the heat transfer medium. The gravel is heated from 600 ° C to 950 ° C.
• the circulating volume of the heat transfer medium is 5 times the wood input, ie 5000 kg per hour.
• the shaft furnace has a height of 4.5 m and a diameter of 1.5 m - this corresponds to a moving bed volume of 7.5 3 .
• the dwell time in the shaft furnace is two hours.
• the enthalpy current of the charcoal in the furnace is 1.86 MW. This is sufficient to generate a steam flow of 0.45 MW (360 kg / h at 950 ° C and atmospheric pressure) and to cover the heat requirement of the reaction of the pyrolysis gas with water vapor in the amount of 0.84 MW.
• the firing efficiency is 85%. After taking into account the heat loss and the loss due to the exhaust gas flow, there remain 0.26 MW. This generated 324 kg / h of superheated steam, which was expanded via a turbine and used as heating steam. The cold gas efficiency is 79%.

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• Chemical & Material Sciences (AREA)
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• Organic Chemistry (AREA)
• Materials Engineering (AREA)
• Chemical Kinetics & Catalysis (AREA)
• General Chemical & Material Sciences (AREA)
• Processing Of Solid Wastes (AREA)
• Industrial Gases (AREA)
• Organic Low-Molecular-Weight Compounds And Preparation Thereof (AREA)
• Gasification And Melting Of Waste (AREA)
• Production Of Liquid Hydrocarbon Mixture For Refining Petroleum (AREA)

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• 1997
  • 1997-12-16 DE DE19755693A patent/DE19755693C1/de not_active Expired - Fee Related
• 1998
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  • 1998-12-15 WO PCT/EP1998/008217 patent/WO1999031197A1/de active IP Right Grant
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