CN102977960A - Process for co-producing and synthetic natural gas and food-grade carbon dioxide by using calcium carbide furnace gas - Google Patents
Process for co-producing and synthetic natural gas and food-grade carbon dioxide by using calcium carbide furnace gas Download PDFInfo
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- CN102977960A CN102977960A CN2012105309987A CN201210530998A CN102977960A CN 102977960 A CN102977960 A CN 102977960A CN 2012105309987 A CN2012105309987 A CN 2012105309987A CN 201210530998 A CN201210530998 A CN 201210530998A CN 102977960 A CN102977960 A CN 102977960A
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Abstract
The invention discloses a process for co-producing synthetic natural gas and food-grade carbon dioxide by using calcium carbide furnace gas. The process sequentially comprises the steps that after purified calcium carbide furnace gas is pressurized and mixed with medium-pressure steam and then the obtained mixture enters a shift-converter to carry out shift-conversion, the obtained gas enters a methanation reactor to carry out methanation, and then enters a decarbonization system to remove CO2; the gas subjected to CO2 removal is dried, and then enters a methane concentration system to carry out concentration, thereby obtaining synthetic natural gas; and the removed CO2 is prepared into food-grade CO2 through a recovery unit. The decarbonization system can adopt a PSA (pressure swing adsorption) dry decarburization process, and also can adopt a wet decarburization process. The wet decarburization is implemented by removing CO2 by using a thermokalite method or MDEA washing. A CO2 recovery unit has the functions of CO2 collecting, purifying, and purification by flash distillation. The methane concentration can be implemented by concentrating methane by using a PSA method, and also can be implemented by concentrating methane through low-temperature separation. The process disclosed by the invention is a packaged technology for co-producing synthetic natural gas and food-grade carbon dioxide by using calcium carbide furnace gas, which is suitable for industrial scale applications.
Description
Technical field
The invention belongs to industrial tail gas and recycle the field, be specially the technique of a kind of calcium carbide furnace gas co-production of synthetic natural gas and food-grade carbon-dioxide.
Background technology
China is the large calcium carbide of the first in the world producing country, and the calcium carbide production capacity was 2,500 ten thousand tons in 2011, accounted for 90.9% of global aggregated capacity, 1,738 ten thousand tons of output.The nucleus equipment of calcium carbide production is furnace of calcium carbide, distinguishes from principle and structure that calcium carbide is produced, and furnace of calcium carbide is divided into closed type calcium carbide furnace and open calcium carbide oven.1 ton of calcium carbide of every production, open calcium carbide oven produces 9000～12000m
3Ash-laden gas, closed type calcium carbide furnace produces 400～600m
3The dust-laden calcium carbide furnace gas.
99% is air in the flue gas of open furnace of calcium carbide discharging, without utility value.The enclosed calcium carbide furnace gas bibliographical information (hole is auspicious. the purification of calcium carbide furnace gas and utilization [J], and the Henan chemical industry, 2010,27(1): 25-29) consist of CO:70～95%, H
2: 2.5～10%, CO
2: 2.5～3.5%, O
2: 0.52～0.6%, CH
4: 2～4%, N
2: 1～2%, contain simultaneously tar, H
2S, COS, CS
2, thiophene, mercaptan, PH
3, NH
3, AsH
3, the impurity such as HCN.
Calcium carbide production reaction principle is that carbon material (being generally blue charcoal) and lime react, and generates calcium carbide (calcium carbide) and carbon monoxide (CO).In the calcium carbide actual production, because blue charcoal is air-dry not thorough, at high temperature produce a large amount of H in the calcium carbide production
2, on the other hand, calcium carbide furnace gas bag-type dust before the air inlet cabinet adopts the nitrogen blowback more, causes the furnace gas component fluctuation larger.Enclosed calcium carbide furnace gas component such as Ningxia Shizuishan City calcium carbide manufacturing enterprise is: CO:50～75%, H
2: 17～28%, CO
2: 1.5～6%, O
2: 0.5～2%, CH
4: 0.5～1.5%, N
2: 6～14%, contain simultaneously tar, H
2S, COS, CS
2, PH
3, NH
3, AsH
3, the impurity such as HCN.
At present the utilization ratio of China's calcium carbide furnace gas only 10%, and the overwhelming majority is directly discharged or " a point day lamp ", causes a large amount of wastings of resources and environmental pollution." calcium carbide industry " 12 " development program " proposes, and about 2,800 ten thousand tons, large-scale closed type calcium carbide furnace proportion was brought up to more than 80%, substantially realizes the target of calcium carbide furnace gas comprehensive utilization to control calcium carbide production capacity in 2015.Expect 2,400 ten thousand tons of China's calcium carbide output in 2015, account for 80% by closed type calcium carbide furnace, its output surpasses 1,920 ten thousand tons, and the calcium carbide furnace gas total amount of by-product surpasses 7,600,000,000 Nm
3, with CO concentration 50～75%, H
2Concentration 17～28% is calculated, and can make 20～2,800,000,000 Nm
3Pure methane, produce huge economic and social benefit.
China's conventional gas stock number is about 35-38 trillion Nm
3, account for 2% of world's total amount; Mining resources amount 10-12 trillion Nm wherein
3, the Sweet natural gas residual recoverable reserves only is equivalent to 6% of world average level per capita.Sweet natural gas is as a kind of high-quality clean energy, and the proportion in China's primary energy source consumption only is 3.9% at present, 23.7% the mean level (ML) well below the world.
Along with the development of urbanization, China's natural gas consumption speedup surpasses the output speedup, and import volume increases year by year.The China's natural gas consumption reached 1,072 hundred million Nm in 2010
3, inlet natural gas 16,600,000,000 Nm
3According to Development Research Center of the State Council's prediction, will be increased to 1,500 hundred million Nm to China's natural gas consumption in 2015
3, need import 40,000,000,000 Nm
3Be increased to 3,000 hundred million Nm to the year two thousand twenty consumption
3, 40% dependence on import is arranged when the time comes approximately.Country encourages the development and production of unconventional Sweet natural gas in recent years, comprises the research and development of the unconventional Sweet natural gases of preparation such as carrying out coal-seam gas, refuse embedded gas, shale gas, coke(oven)gas, to remedy the deficiency of Natural Gas Demand.
Component characteristics according to calcium carbide furnace gas are prepared into unconventional Sweet natural gas with it, simultaneously the by-product food-class CO
2, economically with technical all be feasible.
Food-class CO
2Be mainly used in beer and soda pop industry, tobacco industry, food fresh keeping and CO
2The supercritical extraction technique field.
Present China CO
2Consumption is well below developed country, not enough 5kg/a per capita, and the developed countries such as the U.S. reach more than the 15kg/a per capita.The U.S. is at the 80's of 20th century CO
2Demand reached 4,000,000 t/a.Along with the day by day raising of China's living standards of the people, estimate food-class CO
2Demand also will significantly increase.If by the existing per capita consuming level of the U.S., China every year is to food-class CO
2Demand will reach more than 1,000 ten thousand t.
Tobacco industry used the expanded pipe tobacco of freonll-11 originally, along with the raising of environmental requirement, and to the strict demand of foodstuff additive, was food-class CO
2Enter tobacco industry very large opportunity is provided.Liquid foodstuff level CO
2Be used for tobacco shred bulking, can make every case cigarette save 2.5kg raw material pipe tobacco, and the tobacco shred bulking quality also improve a lot.
Along with the popularization of green food, at the anti-corrosive fresh-keeping of food, vegetables, fruit and fishery products, the aspects such as the desinsection of grain and storage are food-class CO
2New Application Areas is provided.Store quickfrozen food, inflight meal, length refrigerated shipment, film studio and stage smoke screen effect, electronic component and metal cooling, the medical treatment food-class CO that all uses in a large number such as freezing
2
CO
2For the supercritical extraction technique of extraction agent has been obtained breakthrough development, CO at aspects such as Chinese medicine, food, spices, petrochemical complex, biochemical industry and environmental chemical engineerings
2Supercritical extraction will be subject to more and more people's favor as emerging, low-cost, a segregative abstraction technique.
Domestic CO
2Market demand is annual to increase by 15%～20%.CO
2Being the arch-criminal who causes " Greenhouse effect ", is again very widely raw material of purposes simultaneously, should be used.Along with CO
2The continuous expansion of Application Areas, CO
2Industrial requirement and food demand will increase substantially, market outlook are very wide.
At present domestic also without calcium carbide furnace gas synthetic natural gas processed, while by-product food-class CO
2Report.
Summary of the invention
The object of the invention is to, take the methanation technology of the converter technique of CO and CO as the basis, it is simple to design a kind of technique, is suitable for calcium carbide furnace gas co-production of synthetic natural gas and the food-class CO of industrial scale applications
2Complete set technology.
Technical scheme of the present invention is:
The technique of a kind of calcium carbide furnace gas co-production of synthetic natural gas and food-grade carbon-dioxide, this technique may further comprise the steps:
To be pressurized to 3-5MPa through the calcium carbide furnace gas after purifying first, calcium carbide furnace gas and middle pressure steam after supercharging are mixed into shift-converter, after the shift-converter transformationreation, enter methanator and carry out methanation, then enter decarbonization system and remove CO
2, removed CO
2The gas drying enter the methane upgrading system and carry out concentrate, make synthetic natural gas, the CO that removes
2Gas is through CO
2Recovery unit makes food-class CO
2Contain tar, dust, H in the calcium carbide furnace gas
2S, COS, CS
2, thiophene, mercaptan, PH
3, NH
3, AsH
3, the impurity such as HCN, before carry out this technique, need all impurity removals to make the volumn concentration of the tar, sulphur, phosphorus, arsenic, fluorine and the cyanogen impurity composition that wherein contain all less than 0.1ppm through purifying.
A kind of calcium carbide furnace gas of the Chinese invention patent (application number 201110196752.6) that the purification of calcium carbide furnace gas adopts the inventor to propose purifies disclosed purifying method in the concentrate CO technique.Because the CO among the application
2Need to reclaim food-class CO processed
2, the depickling jia bombardier in the Chinese invention patent 201110196752.6 can be omitted suddenly.
Supercharging: enter subsequent handling after calcium carbide furnace gas is pressurized to 3.0MPa～5.0MPa, except the pressure-losses of technical process itself, the working pressure of subsequent handling all carries out under this pressure again.Calcium carbide furnace gas after the supercharging mixes with middle pressure steam, and described middle pressure steam refers to that pressure is 1.6MPa-5.0MPa, temperature 200-265 ℃ saturated steam.Hybrid mode can be to mix at pipeline, also can mix in mixing tank.Need to prove, add steam pressure will with the calcium carbide furnace gas supercharging after pressure be complementary so that steam-energy adds smoothly.
Transformationreation refers under catalyst action, makes CO and steam reaction generate CO
2And H
2The reacting condition equation is:
CO+H
2O → CO
2+ H
2(formula 1)
The CO conversion is the key link during Coal Chemical Industry is produced, and is technological process important in synthetic ammonia, methyl alcohol and the process for making hydrogen.By the CO conversion, when consuming most of CO, convert available gas H to
2, H is provided for the downstream is synthetic
2Raw material.
Low temperature shifting process well known in the art is adopted in conversion, 200 ℃-250 ℃ of gas inlet air temperature, transformationreation is thermopositive reaction, utilize the pre-thermal conversion raw material of the gas air inlet after the conversion, when conversion process large-minded, when causing the reaction bed temperature to be higher than the catalyzer allowable temperature, can adopt the mode of classification charging multi-stage transformation to realize.For classification charging multi-stage transformation, be this area proven technique, be to realize easily.
The add-on of water vapour is according to the CO in the calcium carbide furnace gas and H
2Amount determine.Particularly, require the conversion degree by the add-on control CO of control water vapour, the H in the mixed gas after conversion
2Amount requires to satisfy follow-up methanation to H
2Demand.More particularly, the H in the unstripped gas
2Amount and the amounts of hydrogen sum that transformationreation generates can consume CO fully in follow-up methanation, that is to say the total H after conversion in the gas
2Amount is three times of remaining CO tolerance after the conversion at least.
After heat exchange, directly enter the methanator methanation through the gas after the conversion.Methanation is under catalyst action, makes CO and CO
2With H
2Reaction generates CH
4And water.
Calcium carbide furnace gas utilizes transformationreation liberated heat heating transformationreation air inlet, the CO that transformationreation generates after the shift-converter transformationreation
2Play dilution methanation air inlet effect with remaining water vapour, the high-temperature gas that goes out methanator reclaims heat by byproduct steam.
Described methanation reaction equation is:
CO+3H
2→ CH
4+ H
2O (formula 2)
CO
2+ 4H
2→ CH
4+ 2H
2O (formula 3)
The methanation technology of a kind of method for preparing synthesis gas from coke-oven gas of the Chinese invention patent (ZL200610021836.5) that methanation adopts the applicant to propose.280 ℃-300 ℃ of gas inlet air temperature, methane turns to thermopositive reaction, can utilize the hot gas byproduct steam after the methanation, and the steam of institute's by-product can be used as other purposes of this technique, also can be used for generating.Large-minded when the methanation processing, when causing the reaction bed temperature to be higher than the catalyzer allowable temperature, can adopt the mode of the multistage methanation of classification charging to realize.For the multistage methanation of classification charging, the disclosed technology of a kind of method for preparing synthesis gas from coke-oven gas (number of patent application 200910058611.1) that can adopt the applicant to propose.
For methanation reaction, above-mentioned formula 2 is CO and H
2Methanation is CO than formula 3
2With H
2Methanation is much easier.After conversion, enter in the gas of methanator H
2Excessive, excessive H
2At first with CO reaction, CO gas is by the consumption of the overwhelming majority, CO after the transformationreation
2Also be greatly excessive in mixed gas, the reaction follow-up phase, in the situation that reaction bed temperature raises, excessive CO
2With remaining H
2Methanation, the H of the overwhelming majority
2Be consumed.
Behind above-mentioned conversion and methanation reaction, the CO in the calcium carbide furnace gas and H
2Be converted to CH
4, CO
2And water, also contain original N in the calcium carbide furnace gas
2, unreacted trace amounts of CO and H
2
Decarburization:Gas after the methanation enters decarbonization system and removes CO after cooling and gas-water separation
2
Described decarbonization system can adopt the dry method decarbonization process, also can adopt the wet method decarburization technique.Described dry method decarburization refers to adopt the PSA technology with CO
2From mixed gas, separate; Described wet method decarburization comprises that thermokalite method or MDEA washing remove CO
2These two kinds of decarbonization methods all are well known in the art, and large-scale application is in industrial production.
Described dry method decarburization adopts the PSA technology with CO
2From mixed gas, separate.PSA is the difference according to loading capacity and the adsorption rate on sorbent material of different components in the raw material source of the gas, and the method that active princlple is separated and purifies.This dry method removes CO
2The disclosed method of PSA purifying carbon dioxide technology (Chinese patent ZL8805938.2) that technique can adopt the applicant to propose is carried out CO
2Separated and collected.
Described wet method decarburization adopts thermokalite to wash or the MDEA washing removes CO
2Further, following technique is adopted in the wet method decarburization:
Enter from the bottom, absorption tower after condensation, gas-water separation from methanator mixed gas out, pass through the absorption tower from bottom to top, absorption agent after the regeneration (lean solution) enters from top, absorption tower, pass through the absorption tower from top to bottom, the absorption agent of countercurrent flow fully contacts in the absorption tower with mixed gas, the CO in the gas
2Be absorbed.
Absorbed CO
2Absorption agent be called rich solution, to the regenerator column thermal regeneration.CO after regeneration
2From absorption agent, parse, after cooling, collect.
Absorption agent after the regeneration is called lean solution, and the lean solution that goes out the regenerator column bottom enters the top, absorption tower and recycles after cooling.
Out unabsorbed gases enters the methane upgrading system after purifying from the top, absorption tower.
Food-class CO processed 2 Technique:Above-mentioned CO through dry method or the collection of wet method decarburization unit
2Enter food-class CO processed
2Technique unit comprises CO
2Collection, purification, condensation, flash distillation make food-class CO after purifying
2
CO
2Collection refer to: for adopting the wet method decarbonization process, absorb CO
2Absorption agent through thermal regeneration, the CO of absorption
2Separate from absorption agent, absorption agent is resolved, and the absorption agent after the parsing recycles, isolated CO
2Collected; For the dry method decarbonization process, be to utilize sorbent material that the characterization of adsorption of different components is realized CO
2Separation, reach and collect CO
2Purpose.
Purification is comprised of three adsorbers, and purpose is impurity and the water that removes in the gas.
This workshop section adopts pressure-variable adsorption (PSA) and Temp .-changing adsorption (TSA) technology, utilizes sorbent material loading capacity under different pressures to there are differences and select the characteristic of adsorbing, and removes the impurity in the gas, and sorbent material is selected molecular sieve or silica gel.
Three adsorber continuous circulations use, an adsorber job, and two adsorbers then are in the adsorbent reactivation state in addition.
Enter condensation workshop section through the gas after the purifying treatment.In condensation workshop section, major equipment is vaporizer-condenser, and gas enters vaporizer-condenser, and refrigeration agent also enters vaporizer-condenser simultaneously.As refrigeration agent and CO
2After the heat exchange, gas phase CO
2Be condensed into liquid phase CO
2, refrigeration agent then is vaporized, and recycles by water cooler, ice maker.
Come the liquid phase CO of self-condensation workshop section
2Enter purifier and carry out the gas-liquid separation purification, remove liquid CO
2In H
2, CH
4, N
2Deng gaseous impurities, obtain product food-class liquid CO from the purifier bottom
2
Purifier bottom product liquid CO out
2Deliver to liquid CO
2Basin is for filling bottle or tankage car.
The methane concentrate:Gas after the decarburization enters the methane upgrading system after drying.Drying is to utilize molecular sieve or silica gel that the strong absorption property of water is removed water in the gas.Gas drying is to know in the ability and proven technique, and dehumidification system is comprised of two towers, and wherein one is used another regeneration, and two drying towers are used alternatingly.
The methane upgrading system is to adopt the method for separating with CH
4Separated and collected from mixed gas.Separation method can be used the PSA method, also can use low temperature processing.For low temperature processing, require CO in the gas of cryogenic separation system
2Volumn concentration is lower than 50ppm.If the methane concentrate adopts low temperature processing, and PSA dry method decarbonization process is adopted in the front end decarburization, then needs again decarburization before gas enters cryogenic separation system, thereby with CO in the gas
2Volumn concentration is lower than 50ppm; If the wet method decarbonization process is adopted in the front end decarburization, can be directly with the CO in the gas after the methanation
2Take off to volumn concentration and be lower than 50ppm, gas need not again decarburization before entering cryogenic separation system.
Above-mentioned used PSA concentrate methane technology, the method in the Chinese patent (ZL85103557) " methane in the pressure swing adsorption process enrichment coal mine mash gas " that can propose with reference to the applicant also can be with reference to other PSA separation of methane methods of the prior art.
Above-mentioned low temperature processing is a kind of liquefaction fractionation process flow process, method in the Chinese patent (ZL200410040155.4) " low ternperature separation process concentrate methane technology " that can propose with reference to the applicant also can be with reference to other low ternperature separation process methane method of the prior art.
Synthetic natural gas after the methane concentrate can make compressed natural gas (CNG), also can make natural gas liquids (LNG), also can make gas.
To CO
2Purification refer to remove impurity and water in the gas.Utilize sorbent material to the characterization of adsorption of impurity composition, reach the purpose of purification, clean unit comprises cooling, gas-water separation and the drying of gas, and cleaner is comprised of three adsorbers, and scavenging agent is molecular sieve or silica gel.
Compared with prior art, beneficial effect of the present invention is:
(1) proposes first the calcium carbide furnace gas co-production of synthetic natural gas of energy industrial scale and the technique of food-grade carbon-dioxide among the application, calcium carbide furnace gas can be prepared synthetic natural gas, simultaneously the by-product food-class CO
2, install stable, the advantage that reliability is high, heat utilization ratio is high, the effect that reach the recycling of industrial discharge gas, energy-saving and emission-reduction, turns waste into wealth:
(2) calcium carbide furnace gas directly enters methanator after conversion and heat exchange, need not decarburization, need not heating, need not cooling, simple flow, the CO after the conversion in the gas
2Play dilution methanation air inlet with water vapor.
(3) adopt this technique, decarbonation process adopts the wet method decarbonization process, and the methane concentrate adopts low-temperature liquefaction technique, only needs a step decarburization, and technical process is simple.
(4) amount of heat is all emitted in furnace gas conversion and methanation, by the appropriate design to whole technical process, can realize the comprehensive utilization of each operating unit heat, need not extraneous supplemental heat source, but and by-product high-quality steam.
(5) calcium carbide furnace gas can be produced highly purified methane product after this Technology, and is for sale as CNG, LNG or gas, also can be used as the Chemical Manufacture raw material, produces simultaneously food-class CO
2
Description of drawings
Fig. 1 is schematic flow sheet of the present invention.
Embodiment
The present invention is described in further detail below in conjunction with embodiment.
But this should be interpreted as that the scope of the above-mentioned theme of the present invention only limits to following embodiment.
Embodiment 1
Table 1 calcium carbide furnace gas component
| Component | H 2 | N 2 | CO | CO 2 | CH 4 | Pressure MPa | Flow Nm 3/h |
| V％ | 28.00 | 14.00 | 50.00 | 6.00 | 2.00 | 0.003 | 10000 |
Will10000Nm
3The compressed machine of calcium carbide furnace gas after/h purifies is compressed to 3.0MPa, be to enter the transformationreation preheater after 234 ℃, the saturation steam of pressure 3.0MPa mix to be heated to 200 ℃ in mixing tank with flow 2500kg/h, temperature, enter afterwards shift-converter, under catalyst action, transformationreation occurs in 61% CO in the gas, hot gas after the conversion enters the conversion preheater and carries out the preheating material gas mixture, and after being cooled to 280 ℃, enter the methanation reaction system, methanation reaction occurs under catalyst action.The methanation reaction system is comprised of two methanators, waste heat boiler is set behind every grade of methanation reaction reclaims heat, byproduct steam.
The mixed gas main component that goes out the methanation reaction system is CO
2, CH
4, N
2And water vapour, other has a small amount of unreacted completely CO and H
2This mixed gas enters water cooler and is chilled to and enters air water separator behind the normal temperature and isolate liquid water, enters the dehumidification system dehydration, and dehumidification system is comprised of two towers, wherein use, another regeneration, siccative is selected molecular sieve, and mixed gas enters the PSA system after drying.
Decarburization and concentrate methane all adopt the PSA technology.The PSA system is comprised of three parts, i.e. PSA1, PSA2 and PSA3.
PSA1 is by being the PSA system that is made of 8 adsorbers and a series of time variable control valve.Pass into unstripped gas by inlet end, half gas product that exit end obtains is sent into PSA2 as unstripped gas.In the PSA system, every adsorber experiences successively absorption (A), multistagely all falls (EiD), inverse put (D), find time (V), multistagely all rises (EiR), fills eventually (FR) at different time; The CO that is adsorbed
2Component by inverse put, find time to desorb rear as food-class CO processed
2Unstripped gas collected, adsorbed gas does not enter the concentrated methane of PSA2.
PSA2 enters PSA2 concentrated methane from PSA1 through the gas of decarburization by being the PSA system that is made of 10 adsorbers and a series of time variable control valve.In the PSA system, every adsorber experiences successively absorption (A), multistagely all falls (EiD), displacement (RP), inverse put (D), find time (V), multistagely all rises (EiR), fills eventually (FR) at different time; The methane component that is adsorbed by inverse put, find time to obtain the product synthetic natural gas, adsorption tower is finished desorption process simultaneously.Absorption waste gas enters the concentrated methane of PSA3 again.Inverse put and the gas major part of finding time be as product synthetic natural gas output battery limit (BL), and small part is forced into behind the 0.15MPa as displacement gas.Displacement waste gas is sent into the feed gas compressor entrance and is entered after compression PSA1 again.
PSA3 is by being the PSA system that is made of 8 adsorbers and a series of time variable control valve.Absorption waste gas from PSA2 enters again concentrated methane of PSA3, in the PSA3 system, every adsorber experiences successively absorption (A), multistagely all falls (EiD), inverse put (D), find time (V), multistagely all rises (EiR), fills eventually (FR) at different time; The component that is adsorbed is by inverse put and find time to obtain desorb, enters the PSA1 system after inverse put and the incoming stock air compressor supercharging of the gas of finding time.
Food-class CO
2Preparation: the CO that collects through PSA1 outlet
2Gas enters vaporizer-condenser, and refrigeration agent also enters vaporizer-condenser simultaneously.As refrigeration agent and CO
2After the heat exchange, gas phase CO
2Be condensed into liquid phase CO
2, refrigeration agent then gasifies, and recycles by water cooler, ice maker.
Come the liquid phase CO of self-condensation workshop section
2Enter the purifier distilation, utilize the difference of each gas boiling point to remove liquid CO
2In H
2, CH
4, N
2Deng gaseous impurities, obtain product food-class liquid CO from the purifier bottom
2
Purifier bottom product liquid CO out
2Deliver to liquid CO
2Basin is for filling bottle or tankage car.
Each operation material balance of table 2
Embodiment 2
Table 3 raw material calcium carbide gaseous fraction
| Component | H 2 | N 2 | CO | CO 2 | CH 4 | Pressure MPa | Flow Nm 3/h |
| V％ | 17.00 | 6.00 | 75.00 | 1.50 | 0.50 | 0.003 | 20000 |
20000Nm
3The compressed machine of calcium carbide furnace gas after/h purifies is compressed to 5.0MPa, be that 265 ℃, pressure are to enter the transformationreation preheater after the saturation steam of 5.0MPa mixes to be heated to 250 ℃ in pipeline with flow 8600kg/h, temperature, enter afterwards the transformationreation system, the transformationreation system is comprised of two reactors, waste heat boiler is set after every reaction reclaims heat, byproduct steam.Under catalyst action, transformationreation occurs in 70% CO in the gas, and the hot gas after the conversion enters conversion preheater preheating material gas, and enters the methanation reaction system after heat exchange to 300 ℃, under catalyst action methanation reaction occurs.The methanation reaction system is comprised of three methanators, waste heat boiler is set behind every grade of methanation reaction reclaims heat, byproduct steam.
The mixed gas main component that goes out the methanation reaction system is CO
2, CH
4, N
2And water vapour, other also has a small amount of unreacted completely CO and H
2This mixed gas enters water cooler and is chilled to enter behind the normal temperature and enters the decarburization unit after air water separator is isolated liquid water.
The MDEA decarbonization system is selected in decarburization.
Enter from the bottom, absorption tower after condensation, gas-water separation from methanator mixed gas out, pass through the absorption tower from bottom to top; MDEA solution (lean solution) after the regeneration enters from top, absorption tower, and by the absorption tower, the MDEA of countercurrent flow fully contacts in the absorption tower with mixed gas, the CO in the gas from top to bottom
2Be absorbed.
Absorbed CO
2Absorption agent be called rich solution, to the regenerator column thermal regeneration.CO after regeneration
2From the MDEA rich solution, parse, after cooling, collect.
MDEA after the regeneration is called lean solution, and the lean solution that goes out the regenerator column bottom enters the top, absorption tower and recycles after cooling.
Out unabsorbed gases enters the methane upgrading system after drying from the top, absorption tower.Drying means is identical with embodiment 1, and siccative adopts silica gel.
Food-class CO processed
2Implementation method is identical with embodiment 1.
The methane concentrate adopts low temperature processing.
Decarbonization gas flows through precool heat exchanger device, main heat exchanger and liquefaction interchanger successively, and temperature reduces gradually, again through the rectifying tower evaporator cools to～-132 ℃, after throttling, enter rectifying tower middle part and separate.Gas phase is as the gas that rises, and a small amount of gas is condensed in the condenser of rectifying tower cat head does phegma, and partially liq is heated by vaporizer at the bottom of rectifying tower, and gas rises and the phegma heat and mass.From rectifier bottoms liquid LNG product out, in crossing cold heat exchanger, cross the LNG storage tank that cold rear cooling box is sent into the user; Rectifying tower ejects the residual gas that comes and passes through first the cold heat exchanger re-heat, is followed successively by liquefaction interchanger and main heat exchanger again cold is provided, and sends ice chest after the re-heat as the moisture eliminator resurgent gases.
Adopt nitrogen to provide cold as cryogen.Nitrogen enters in the precool heat exchanger device and cools off after nitrogen compressor supercharging, cooling, minute two-way after entering main heat exchanger and being cooled to-62 ℃; One the tunnel enters booster expansion turbine, returns the liquefaction interchanger after the adiabatic expansion; Cooling is continued by providing cold to the rectifying tower top condenser first behind the throttling valve reducing pressure by regulating flow in another road, provides cold with expansion gas for main heat exchanger again, enters the circulating nitrogen gas compressor behind the cooling box, forms the expander refrigeration circulation of a closure.
Each operation material balance of table 4
Embodiment 3
Table 5 raw material calcium carbide gaseous fraction
| Component | H 2 | N 2 | CO | CO 2 | CH 4 | Pressure MPa | Flow Nm 3/h |
| V％ | 23.00 | 10.00 | 62.00 | 4.00 | 1.00 | 0.003 | 30000 |
30000Nm
3The compressed machine of calcium carbide furnace gas after/h purifies is compressed to 4.0MPa, be that 250 ℃, pressure are to enter the transformationreation preheater after the saturation steam of 4.0MPa mixes to be heated to 220 ℃ in mixing tank with flow 10000kg/h, temperature, enter afterwards the transformationreation system, the transformationreation system is comprised of three reactors, waste heat boiler is set after every reaction reclaims heat, byproduct steam.Under catalyst action, transformationreation occurs in 66% CO in the gas, and the hot gas after the conversion enters conversion preheater preheating material gas mixture, and enters the methanation reaction system after being cooled to 290 ℃, under catalyst action methanation reaction occurs.The methanation reaction system is comprised of four methanators, waste heat boiler is set behind every grade of methanation reaction reclaims heat, byproduct steam.
The mixed gas main component that goes out the methanation reaction system is CO
2, CH
4, N
2And water vapour, other also has a small amount of unreacted completely CO and H
2This mixed gas enters water cooler and is chilled to enter behind the normal temperature and enters the decarburization unit after air water separator is isolated liquid water.
The implementation method of decarburization unit is identical with embodiment 1
CO after the decarburization
2Collection and food-class CO processed
2Implementation method is identical with embodiment 1.
Methane concentrate synthetic natural gas processed is identical with embodiment 2, adopts low temperature processing, and entering cryogenic system at gas needs first again decarburization, with CO in the gas
2Volumn concentration takes off to being lower than 50ppm, and decarbonization method is identical with the decarbonization method of embodiment 2.
Each operation material balance of table 6
Claims (10)
1. the technique of a calcium carbide furnace gas co-production of synthetic natural gas and food-grade carbon-dioxide is characterized in that this technique may further comprise the steps:
Calcium carbide furnace gas after will purifying first carries out supercharging, and calcium carbide furnace gas and middle pressure steam after supercharging are mixed into shift-converter, after the shift-converter transformationreation, enters methanator and carries out methanation, then enters decarbonization system and removes CO
2, removed CO
2The gas drying enter the methane upgrading system and carry out concentrate, make synthetic natural gas, the CO that removes
2Gas is through CO
2Recovery unit makes food-class CO
2
2. the technique of calcium carbide furnace gas co-production of synthetic natural gas according to claim 1 and food-grade carbon-dioxide, it is characterized in that: the calcium carbide furnace gas after the described purification refers to after purifying, and the volumn concentration of tar, sulphur, phosphorus, arsenic, fluorine and cyanogen impurity composition is all less than the gas of 0.1ppm.
3. the technique of calcium carbide furnace gas co-production of synthetic natural gas according to claim 1 and food-grade carbon-dioxide, it is characterized in that: described supercharging refers to the pressure of calcium carbide furnace gas is increased to 3-5MPa; Described middle pressure steam refers to that pressure is 1.6-5.0MPa, and temperature is 200-265 ℃ saturated steam.
4. the technique of calcium carbide furnace gas co-production of synthetic natural gas according to claim 1 and food-grade carbon-dioxide is characterized in that: described transformationreation refers under catalyst action, makes CO and steam reaction generate CO
2And H
2Described methanation is under catalyst action, makes CO and CO
2With H
2Reaction generates CH
4And water.
5. the technique of calcium carbide furnace gas co-production of synthetic natural gas according to claim 1 and food-grade carbon-dioxide, it is characterized in that: calcium carbide furnace gas is after the shift-converter transformationreation, utilize transformationreation liberated heat heating transformationreation air inlet, the gas of conversion after by heat exchange directly enters methane reactor and carries out methanation, the CO that transformationreation generates
2Play dilution methanation air inlet effect with remaining water vapour, the high-temperature gas that goes out methanator reclaims heat by byproduct steam.
6. the technique of calcium carbide furnace gas co-production of synthetic natural gas according to claim 1 and food-grade carbon-dioxide, it is characterized in that: described decarbonization system refers to adopt the technique of dry method decarburization or the technique of wet method decarburization, and described dry method decarburization refers to adopt the PSA technology with CO
2From mixed gas, separate; Described wet method decarburization comprises that thermokalite method or MDEA washing remove CO
2
7. the technique of calcium carbide furnace gas co-production of synthetic natural gas according to claim 1 and food-grade carbon-dioxide is characterized in that: described CO
2Recovery unit comprises CO
2Collection, to CO
2Purification, to CO
2Carry out making food-class CO after flash distillation is purified
2Process; CO
2Collection refer to: for adopting the wet method decarbonization process, absorb CO
2Absorption agent through thermal regeneration, the CO of absorption
2Separate from absorption agent, absorption agent is resolved, and the absorption agent after the parsing recycles, isolated CO
2Collected; For the dry method decarbonization process, be to utilize sorbent material that the characterization of adsorption of different components is realized CO
2Separation, reach and collect CO
2Purpose.
8. the technique of calcium carbide furnace gas co-production of synthetic natural gas according to claim 7 and food-grade carbon-dioxide is characterized in that: described to CO
2Purification refer to remove impurity and water in the gas, utilize sorbent material to the characterization of adsorption of impurity composition, reach the purpose of purification, clean unit comprises cooling, gas-water separation and the drying of gas, cleaner is comprised of three adsorbers, and scavenging agent is molecular sieve or silica gel.
9. the technique of calcium carbide furnace gas co-production of synthetic natural gas according to claim 1 and food-grade carbon-dioxide, it is characterized in that: described methane upgrading system concentrate refers to adopt the method for separation with CH
4Separated and collected from mixed gas, separation method can be used the PSA method, can be low temperature processing also, for low temperature processing, requires CO in the gas of cryogenic separation system
2Volumn concentration is lower than 50ppm.
10. according to claim 6 or the technique of calcium carbide furnace gas co-production of synthetic natural gas claimed in claim 9 and food-grade carbon-dioxide, it is characterized in that: if PSA dry method decarbonization process is adopted in decarburization, and the methane concentrate adopts low temperature processing, before entering cryogenic separation system, gas needs again decarburization, thereby with CO in the gas
2Volumn concentration is lower than 50ppm; If the wet method decarbonization process is adopted in decarburization, can be directly with the CO in the gas after the methanation
2Take off to volumn concentration and be lower than 50ppm, gas need not again decarburization before entering cryogenic separation system.
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| CN103343025A (en) * | 2013-06-08 | 2013-10-09 | 东华工程科技股份有限公司 | Process for synthesizing natural gas employing methanation of calcium carbide furnace gas |
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