CN101612512B - Carbon dioxide separating system and separating method - Google Patents

Carbon dioxide separating system and separating method Download PDF

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CN101612512B
CN101612512B CN2008101155589A CN200810115558A CN101612512B CN 101612512 B CN101612512 B CN 101612512B CN 2008101155589 A CN2008101155589 A CN 2008101155589A CN 200810115558 A CN200810115558 A CN 200810115558A CN 101612512 B CN101612512 B CN 101612512B
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carbon dioxide
absorbent
solution
absorbent solution
heat exchanger
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CN101612512A (en
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苏庆泉
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Priority to PCT/CN2009/000713 priority patent/WO2009155790A1/en
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    • BPERFORMING OPERATIONS; TRANSPORTING
    • B01PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01DSEPARATION
    • B01D53/00Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols
    • B01D53/14Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols by absorption
    • B01D53/1456Removing acid components
    • B01D53/1475Removing carbon dioxide
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B01PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01DSEPARATION
    • B01D53/00Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols
    • B01D53/14Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols by absorption
    • B01D53/1425Regeneration of liquid absorbents
    • CCHEMISTRY; METALLURGY
    • C01INORGANIC CHEMISTRY
    • C01BNON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
    • C01B32/00Carbon; Compounds thereof
    • C01B32/50Carbon dioxide
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B01PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01DSEPARATION
    • B01D2251/00Reactants
    • B01D2251/30Alkali metal compounds
    • B01D2251/302Alkali metal compounds of lithium
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B01PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01DSEPARATION
    • B01D2251/00Reactants
    • B01D2251/30Alkali metal compounds
    • B01D2251/304Alkali metal compounds of sodium
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B01PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01DSEPARATION
    • B01D2251/00Reactants
    • B01D2251/30Alkali metal compounds
    • B01D2251/306Alkali metal compounds of potassium
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B01PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01DSEPARATION
    • B01D2251/00Reactants
    • B01D2251/40Alkaline earth metal or magnesium compounds
    • B01D2251/402Alkaline earth metal or magnesium compounds of magnesium
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B01PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01DSEPARATION
    • B01D2251/00Reactants
    • B01D2251/40Alkaline earth metal or magnesium compounds
    • B01D2251/404Alkaline earth metal or magnesium compounds of calcium
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B01PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01DSEPARATION
    • B01D2257/00Components to be removed
    • B01D2257/50Carbon oxides
    • B01D2257/504Carbon dioxide
    • YGENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02CCAPTURE, STORAGE, SEQUESTRATION OR DISPOSAL OF GREENHOUSE GASES [GHG]
    • Y02C20/00Capture or disposal of greenhouse gases
    • Y02C20/40Capture or disposal of greenhouse gases of CO2
    • YGENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02PCLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
    • Y02P20/00Technologies relating to chemical industry
    • Y02P20/151Reduction of greenhouse gas [GHG] emissions, e.g. CO2

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  • Chemical & Material Sciences (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Organic Chemistry (AREA)
  • Engineering & Computer Science (AREA)
  • Analytical Chemistry (AREA)
  • General Chemical & Material Sciences (AREA)
  • Oil, Petroleum & Natural Gas (AREA)
  • Inorganic Chemistry (AREA)
  • Treating Waste Gases (AREA)
  • Gas Separation By Absorption (AREA)

Abstract

The invention relates to a carbon dioxide separating system and a separating method. The separating system comprises a carbon dioxide absorption tower, a carbon dioxide absorption solution regenerating tower, a generator, an absorber and a steam passage, wherein the carbon dioxide absorption tower is used for absorbing carbon dioxide in carbon-dioxide-containing gas; the carbon dioxide absorption solution regenerating tower is connected with a re-boiler and used for regenerating carbon dioxide absorption solution; a first generation heat exchanger and a second generation heat exchanger are arranged in the generator; the inside of the absorber is provided with an absorption heat exchanger which is connected to the re-boiler; the steam passage is communicated with the generator and the absorber; an inlet of the first generation heat exchanger is connected to an absorption solution outlet at the bottom of the carbon dioxide absorption solution regenerating tower, an outlet of the first generation heat exchanger is connected to an absorption solution inlet at the upper part of the carbon dioxide absorption tower; and an inlet of the second generation heat exchanger is connected to a gas outlet at the top of the regenerating tower. The system can realize separation and reclamation of the carbon dioxide in the smoke with extremely low energy consumption.

Description

Carbon dioxide separating system and separation method
Technical field
The present invention relates to the carbon dioxide separation technology of a kind of chemical industry and field of environment engineering, particularly a kind ofly can effectively remove the piece-rate system of carbon dioxide in the flue gas and the separation method of carbon dioxide.
Background technology
CO 2A large amount of dischargings of isothermal chamber gas are major reasons that causes global warming.Therefore, CO 2Emission problem caused the very big concern of international community.Reduce the CO of combustion of fossil fuel 2Discharging mainly contains two approach: the one, improve efficiency of energy utilization, the 2nd, separation of C O from combustion product gases 2, and be used, store or seal up for safekeeping.
At CO 2Remove in the technology, absorb CO with ammonia spray thermal power station boiler exhaust gas flue gas 2, not only can reach CO 2The purpose that reduces discharging can also obtain the high-quality chemical fertilizer.But, because carbonic hydroammonium can be decomposed into ammonia, water and CO under 60 ℃ the environment temperature being higher than 2, cause CO 2Again return atmosphere, so this CO 2The application of discharge-reducing method also needs further research.CO 2The technology that removes also have the CO of CaO carbonating-calcination cycle 2(CCR) technology of separation, polymeric membrane remove CO 2, O 2/ CO 2Circulating combustion technology and burning chemistry chains (CLC) technology etc.But often the industrializing implementation cost is higher for above-mentioned technology.
At CO 2Remove in the technology, very important a kind of method is to adopt solution absorption method to remove CO 2According to the difference of absorbent properties, can be divided into two big classes.One class is the Physical Absorption method, as WATER-WASHING METHOD, low-temperature rectisol method (Rectisol), polyglycol dimethyl ether process (Selexol), propene carbonate method.Another kind of is chemical absorption method, as hot potash method, and low hear rate Ben Feierfa, activation MDEA method, MEA process etc.Above-mentioned CO 2It is all very ripe to remove technology, has realized industrialization already at chemical field.
Someone has proposed to utilize chemical absorption method to separate and reclaims carbon dioxide from the burnt gas in thermal power plant scheme (please refer to: clear former positive height, from generating with reclaiming CO the boiler exhaust 2Test, the energy. resource, the energy. the resource science meeting, 1993, the 14th the volume, the 1st its, the 91-97 page or leaf).According to this scheme, although different with the difference of condition, the separation rate of recovery of carbon dioxide can reach more than 80%.Yet, adopt traditional chemical absorption method from combustion product gases, to separate and reclaim the required energy consumption of carbon dioxide up to 750~900kcal/kg-CO 2, the operating cost of therefore separating recovery is very high.
Summary of the invention
Main purpose of the present invention is, a kind of carbon dioxide separating system and separation method of low energy consumption is provided, and the carbon dioxide that is used for removing flue gas is discharged into the Atmospheric Carbon Dioxide amount with minimizing, thereby helps protecting environment.
The object of the invention to solve the technical problems realizes by the following technical solutions.According to a kind of carbon dioxide separating system that the present invention proposes, it comprises: carbon dioxide absorption tower is used for absorbing the carbon dioxide of carbon dioxide containing gas; Carbon dioxide absorption liquid regenerator is connected with reboiler, is used for the regenerating carbon dioxide absorption liquid; Generator is provided with first the heat exchanger and the second generation heat exchanger takes place in it, be filled with absorbent solution in this generator; Absorber is filled with absorbent solution in it, be provided with the absorption heat exchanger in this absorber, is connected in described reboiler; Steam channel is communicated with described generator and described absorber; The concentration of absorbing of absorbent solution is lower than the concentration of absorbing of absorbent solution in the absorber in the described generator; Described first inlet that heat exchanger takes place is connected in the absorption liquid outlet of above-mentioned carbon dioxide absorption liquid regenerator bottom, and first outlet that heat exchanger takes place connects the absorption liquid inlet on above-mentioned carbon dioxide absorption tower top; Described second inlet that heat exchanger takes place is connected in the gas vent at above-mentioned carbon dioxide absorption liquid regenerator top.
Purpose of the present invention can also adopt following technical measures to realize.
Preferably, the carbon dioxide separating system that embodiments of the invention propose, it also comprises absorbent crystallizer, this absorbent crystallizer comprises: the crystallizer absorbent solution inlet is connected in absorber absorbent solution outlet and generator taphole by pipeline; The crystallizer weak solution exports, and is connected in the absorbent solution inlet of generator by pipeline; And contain the crystallization solution delivery outlet, be connected in the absorbent solution inlet of absorber by pipeline.
Preferably, the carbon dioxide separating system that embodiments of the invention propose, it comprises that also absorbent solution is from heat exchanger, be arranged on described absorbent crystallizer and generator and the pipeline that absorber is connected, be used to enter the absorbent solution of absorbent crystallizer, from the weak solution of absorbent crystallizer output with from the heat exchange between the crystallization solution of containing of absorbent crystallizer output.
Preferably, the carbon dioxide separating system that embodiments of the invention propose, it also comprises gas-liquid separator, is connected in the outlet of the second above-mentioned generation heat exchanger.
Preferably, the carbon dioxide separating system that embodiments of the invention propose, also be provided with the external heat source heater in the described generator, be used to add the absorbent solution in the heater, to compensate owing to the radiation loss of system and the shortage of heat that the crystallizer cooling loss causes.
The object of the invention to solve the technical problems can also realize by the following technical solutions.A kind of carbon dioxide separation method according to the present invention's proposition, be used for separating the carbon dioxide of carbon dioxide containing gas, this method may further comprise the steps: contact with carbon dioxide containing gas with carbon dioxide absorption liquid, absorb the carbon dioxide in the carbon dioxide containing gas; Carbon dioxide absorption liquid behind the absorbing carbon dioxide is heated, regenerates then, and the absorbent solution that gas that regeneration forms and liquid divide two-way to be used to heat a low concentration, and produce working substance steam; The laggard promoting the circulation of qi liquid of absorbent solution that the gas that regeneration forms has heated above-mentioned low concentration separates, and obtains carbon dioxide; The liquid that regeneration forms has heated the carbon dioxide that is used for absorbing carbon dioxide containing gas after the absorbent solution of above-mentioned low concentration as carbon dioxide absorption liquid once more; Above-mentioned working substance steam is absorbed by the absorbent solution of another higher concentration and discharges and absorbs heat, the described carbon dioxide absorption liquid that absorbs after heat is used to heat above-mentioned absorbing carbon dioxide.
Preferably, the carbon dioxide separation method that embodiments of the invention propose, the difference of the absorbent molar fraction of the absorbent solution of wherein said low concentration and the absorbent solution of high concentration is greater than 0.1.
Preferably, the carbon dioxide separation method that embodiments of the invention propose, the absorbent solution of part low concentration wherein and the absorbent solution of part high concentration are cooled, and form crystallization, carry out Separation of Solid and Liquid then;
Weak solution after the Separation of Solid and Liquid is mixed with described lower concentration absorbing solution, contains crystallization solution and described high concentration absorbent solution.
Preferably, the carbon dioxide separation method that embodiments of the invention propose, it also comprises: the absorbent solution of the part low concentration before above-mentioned being cooled and absorbent solution, the weak solution after the Separation of Solid and Liquid of part high concentration and contain and carry out heat exchange between the crystallization solution.
Preferably, the carbon dioxide separation method that embodiments of the invention propose adopts external source that the absorbent solution of part low concentration and the absorbent solution of part high concentration are cooled off.
Preferably, the carbon dioxide separation method that embodiments of the invention propose, described carbon dioxide absorption liquid are the mixture of solution of potassium carbonate and aminated compounds solution one of them or several materials.
Preferably, the carbon dioxide separation method that embodiments of the invention propose, wherein said aminated compounds is monoethanolamine, diethanol amine, triethanolamine, diisopropanolamine (DIPA), methyl diethanolamine or diglycolamine.
Preferably, the carbon dioxide separation method that embodiments of the invention propose, wherein said absorbent solution is made up of working medium and absorbent, and described working medium is the mixture of water, ammonia, methyl alcohol and ethanol one of them or several materials; Described absorbent is LiBr, LiCl, LiNO 3, Li 2SO 4, ZnCl 2, ZnBr 2, NaCl, KCl, Na 2SO 4, K 2SO 4, NaBr, KBr, CaCl 2And MgBr 2The mixture of one of them or several materials.
The present invention compared with prior art has tangible advantage and beneficial effect.The absorption reaction of carbon dioxide is a strong exothermal reaction, and the regenerative response of carbon dioxide absorption liquid is the back reaction of carbon dioxide absorption reaction, is strong endothermic reaction.Existing carbon dioxide chemical absorbing technology as shown in Figure 3 is in order to improve the CO of absorption liquid 2Absorbability, usually adopt external refrigeration water that the carbon dioxide absorption liquid that enters the absorption tower is cooled off, work under lower temperature to guarantee the absorption tower, simultaneously more thorough for the regeneration that makes absorption liquid, adopt external heat source the absorption liquid in the regenerator to be heated with the assurance regenerator usually and under the temperature that is higher than the absorption tower operating temperature, work as regenerated heat.As seen, existing carbon dioxide chemical absorbing technology on the one hand need be by external refrigeration water to a large amount of more low-grade heat of environmental emission, and need to drop into a large amount of external drive thermal source on the other hand, thereby be one and not only consumed energy but also the process of water consumption than high-grade.By above technical scheme as can be known, the carbon dioxide separating system that the present invention proposes is actually carbon dioxide chemical absorbing technology and absorption heat pump circulating technology is organically combined, more low-grade heat that absorbs that the carbon dioxide absorption process is emitted in effect by absorption heat pump circulation promotes to can be used for the regenerated heat than high-grade of carbon dioxide absorption liquid regeneration, thereby realizes reducing significantly or need not external refrigeration water and external drive thermal source.Therefore, compare with existing carbon dioxide separating system, the carbon dioxide separating system that the present invention proposes has the advantage of low energy consumption, low operating cost.
Above-mentioned explanation only is the general introduction of technical solution of the present invention, for can clearer understanding technological means of the present invention, and can be implemented according to the content of specification, below with preferred embodiment of the present invention and conjunction with figs. describe in detail as after.
Description of drawings
Fig. 1 is the schematic diagram of the carbon dioxide separating system of the embodiment of the invention 1.
Fig. 2 is the schematic diagram of the carbon dioxide separating system of the embodiment of the invention 2.
Fig. 3 is the schematic diagram of existing carbon dioxide separating system.
The specific embodiment
Reach technological means and the effect that predetermined goal of the invention is taked for further setting forth the present invention, below in conjunction with accompanying drawing and preferred embodiment, to its specific embodiment of carbon dioxide separating system, structure, feature and the effect thereof that foundation the present invention proposes, describe in detail as after.
Seeing also shown in Figure 1ly, is the schematic diagram of the carbon dioxide separating system of the embodiment of the invention 1.This carbon dioxide separating system mainly comprises: carbon dioxide absorption tower 10, carbon dioxide absorption liquid regenerator 40, generator 21 and absorber 22.
Described carbon dioxide absorption tower 10 is used for absorbing the carbon dioxide of carbon dioxide containing gas.Described carbon dioxide absorption tower 10 comprises: at the bottom of the tower 11, be used to hold carbon dioxide absorption liquid; Packing layer 12 is arranged on the medium position in this carbon dioxide absorption tower 10, its role is to make carbon dioxide absorption liquid and the gas that enters in the tower that bigger contact interface is arranged; Air supply opening 16 is arranged under the above-mentioned packing layer 12, is used for providing in the absorption tower carbonated unstrpped gas; Exhaust outlet 15 is arranged on the top of carbon dioxide absorption tower 10, is used to discharge the gas after the carbon dioxide separation; Sprinkling equipment 13 is arranged on the above-mentioned packing layer 12, is used for evenly spraying carbon dioxide absorption liquid.In this absorption tower, under carbon dioxide absorption liquid drenches in the absorption tower from top to bottom, gas flows from bottom to top, and carbon dioxide absorption liquid contacts with carbon dioxide containing gas (as flue gas) in entering the absorption tower, and absorption carbon dioxide and acid gas components such as SOx, NOx wherein.
Described generator 21 is provided with first the heat exchanger 31 and the second generation heat exchanger 25 takes place in it, be filled with the absorbent solution of low concentration in this generator 21, and this absorbent solution is made up of working medium and absorbent.The effect of this generator is that the absorbent solution of the low concentration in this generator is heated, thereby produces working substance steam.
Described generator 21 also is provided with external heat source heater 32 in it, be used to add the absorbent solution in the heater, to compensate owing to the radiation loss of system and the shortage of heat that the crystallizer cooling loss causes.
Described absorber 22, be filled with the absorbent solution of high concentration in it, its working medium and absorbent are identical with absorbent solution in the generator 21, but its concentration of absorbing is higher than the concentration of absorbing of absorbent solution in the generator 21, preferable, absorbent solution in its absorber 22 is saturated solution (perhaps supersaturated solution, i.e. coexistence has the absorbent crystallization).In this absorber 22, be provided with absorption heat exchanger 26, be connected in the reboiler 46 of described carbon dioxide absorption liquid regenerator 40.Between described generator 21 and described absorber 22, be provided with working substance steam passage 23, be used to make the working substance steam that produces in the generator 21 to enter in the absorber 22.The concentration of absorbing of absorbent solution is lower than the concentration of absorbing of absorbent solution in the absorber in the described generator.
Described carbon dioxide absorption liquid regenerator 40 is connected with reboiler 46, and its top is provided with sprinkling equipment 43, is connected in the absorption liquid outlet of 10 bottoms, described absorption tower.Be provided with packing layer 42 at the middle part of regenerator 40, be used to make carbon dioxide absorption liquid fully to regenerate, the bottom of regenerator is 41 to be used to hold carbon dioxide absorption liquid at the bottom of the tower, and regenerator 40 tops are provided with exhaust outlet 45.By pipeline the carbon dioxide absorption liquid of absorption tower bottom is delivered to the regeneration that regenerator carries out absorption liquid, forms gas and liquid two-phase.The main component of this gas is carbon dioxide and steam, and the main component of described liquid is a carbon dioxide absorption liquid, still, owing to reduce greatly through the gas concentration lwevel that contains in this liquid of regeneration.Described first inlet that heat exchanger 31 takes place is connected in the absorption liquid outlet of above-mentioned regenerator 40 bottoms, described first outlet that heat exchanger 31 takes place connects the sprinkling equipment 13 of above-mentioned carbon dioxide absorption tower 10, makes first to take place to enter in the carbon dioxide absorption tower once more through the carbon dioxide absorption liquid after the heat exchange cooling in the heat exchanger 31.Described second inlet that heat exchanger 25 takes place is connected in the top vent 45 of above-mentioned regenerator 40.The exhaust of regenerator reduces through gas temperature after the heat exchange, and part steam generation condensation.Then, obtain the carbon dioxide of high concentration from second outlet that heat exchanger 25 takes place.Preferable, be connected with gas-liquid separator 30 to obtain the higher carbon dioxide of purity in the second above-mentioned outlet that heat exchanger 25 takes place.
Seeing also shown in Figure 2ly, is the schematic diagram of the carbon dioxide separating system of the embodiment of the invention 2.Compare with the piece-rate system of the above embodiments 1, present embodiment has increased liquid-feeding pump 24, absorbent solution from heat exchanger 27 and absorbent crystallizer 28, and effect is to make the concentration difference of the absorbent solution in generator 21 and the absorber 22 to maintain a relatively stable state.In addition, present embodiment has also increased carbon dioxide absorption liquid from heat exchanger 44, and effect is to make the regeneration efficiency of absorption liquid to be further improved.
Described liquid-feeding pump 24 is connected in described generator 21 and absorber 22 by pipeline, is used for the solution that partially absorbs in generator 21 and the absorber 22 is transported to absorbent crystallizer 28.This absorbent crystallizer 28 comprises: the crystallizer absorbent solution inlet is connected in the absorbent solution outlet of liquid-feeding pump 24 by pipeline; The crystallizer weak solution exports, and is connected in the absorbent solution inlet of generator 21 by pipeline; And contain the crystallization solution delivery outlet, be connected in the absorbent solution inlet of absorber 22 by pipeline.This absorbent crystallizer 28 also has the refrigerant recycle unit, and the absorbent solution that is used in absorbent crystallizer 28 provides cold, and the absorbent solution temperature in the absorbent crystallizer 28 is reduced, and when the crystallization temperature that reaches absorbent is following, separates out the absorbent crystallization.After Separation of Solid and Liquid, the absorbent crystallization outputs to the absorber 22 from containing the crystallization solution delivery outlet, and the weak solution that concentration of absorbing has reduced is transported in the generator 21 from the outlet of crystallizer weak solution.
Absorbent solution is used for the absorbent solution that enters absorbent crystallizer 28, carries out heat exchange from the weak solution of absorbent crystallizer output with from the crystallization solution that contains of absorbent crystallizer output on heat exchanger 27 is arranged at described absorbent crystallizer 28 and pipeline that liquid-feeding pump 24 is connected.Absorbent solution is that from the beneficial effect of heat exchanger 27 through after the heat exchange, the absorbent solution temperature that enters absorbent crystallizer 28 reduces, and helps the formation of crystallization, thereby has saved the required cold of crystallization; The temperature that outputs to the weak solution of generator 21 is improved, and helps absorbing the evaporation of cycle fluid; The temperature that contains the absorbent crystallization solution of output also is improved, thereby helps keeping absorber 22 to be worked under higher temperature.
Described carbon dioxide absorption liquid is from heat exchanger 44, be arranged on the pipeline that the absorption liquid that connects 10 bottoms, absorption tower exports and the absorption liquid on regenerator 40 tops enters the mouth, be used at the bottom of the tower of regenerator 40,41 being delivered to the first carbon dioxide absorption liquid that heat exchanger 31 takes place and between the carbon dioxide absorption liquid of regenerator conveying, carrying out heat exchange from absorbing at the bottom of the Tata 11, enter the temperature of the carbon dioxide absorption liquid of regenerator 40 with raising, thereby further improve the carbon dioxide absorption liquid regeneration efficiency of regenerator 40.
In above-mentioned each embodiment, the basic procedure of finishing technical solution of the present invention has only been described, omit for other parts or the equipment of realizing this flow process, for example, guarantee pump or valve that each flow of matter direction is required.For realizing needed other equipment of the described power circulation system of above-mentioned each embodiment or part, those skilled in the art all can find corresponding technological means in the prior art, and the inventor does not repeat them here.
The embodiment of the invention 3 has also proposed a kind of carbon dioxide separation method, and it adopts embodiment 1 described carbon dioxide separating system.This carbon dioxide separation method comprises: contact with flue gas with carbon dioxide absorption liquid in carbon dioxide absorption tower, make the carbon dioxide in the carbon dioxide absorption liquid absorption flue gas, and drop at the bottom of the tower of carbon dioxide absorption tower; Output to the carbon dioxide absorption liquid behind the absorbing carbon dioxide at the bottom of the tower in the carbon dioxide absorption liquid regenerator and be heated intensification, the absorption liquid of absorbing carbon dioxide is decomposed, form gas and liquid two-phase, this gas is mainly carbon dioxide, and because a large amount of carbon dioxide has formed gaseous state, the carbon dioxide content in the liquid that regeneration forms reduces; The gas that forms after the above-mentioned regeneration is fed second of generator heat exchanger takes place, and the liquid that forms of the back of will regenerate feeds first of generator heat exchanger takes place, the absorbent solution that is used for adding heater makes its formation working substance steam; Above-mentioned working substance steam enters into absorber by steam channel, is absorbed absorbent solution in the device and absorbs to discharge and absorb heat, is used to heat carbon dioxide absorption liquid in the reboiler by heat exchange mode with this absorptions is hot.The difference of the absorbent molar fraction of the absorbent solution in absorbent solution in the wherein said absorber and the described generator is greater than 0.1, the big more temperature that helps more improving in the absorber of concentration difference, thus help the regeneration of carbon dioxide absorption liquid; Turn back to the carbon dioxide that the carbon dioxide absorption tower top is used for absorbing flue gas once more from first liquid that heat exchanger output takes place; The second above-mentioned gas that heat exchanger output takes place is carried out gas-liquid separation can obtain highly purified carbon dioxide.
The carbon dioxide separation method of present embodiment 3 can remove the carbon dioxide more than 80% in the flue gas, and the purity (being dry gas content) under the condition of disregarding the steam composition of the carbon dioxide that separation obtains can reach more than 99%.
The embodiment of the invention 4 has also proposed a kind of carbon dioxide separation method, is that with the separation method difference of embodiment 3 it adopts embodiment 2 described piece-rate systems.Present embodiment has increased the circulation step of absorbent solution in generator and the absorber than embodiment 3, it comprises: feed the solution that partially absorbs that partially absorbs in solution and the generator in the absorber in the absorbent crystallizer jointly, and the absorbent solution in the crystallizer cooled off, thereby can form the absorbent crystallization, carry out Separation of Solid and Liquid then; The rare absorbent solution that obtains after the Separation of Solid and Liquid imports in the generator, and the absorbent crystallization after the Separation of Solid and Liquid imports in the absorber in the mode that contains crystallization solution, thereby the solution concentration difference in absorber and the generator is kept within the specific limits.The present invention can realize the continuity of carbon dioxide separation process.In above-mentioned absorbent crystallizer, can feed external source to the absorbent solution in the crystallizer is cooled off.
Preferable, before entering absorbent crystallizer, partially absorb solution, partially absorbing the weak solution after solution, the Separation of Solid and Liquid and containing and carry out heat exchange between the crystallization solution from generator output from absorber output.Through this heat exchange steps, thereby can improve the operating temperature that the temperature that imports the absorbent solution in absorber and the generator can keep absorbent solution in absorber and the generator, simultaneously the temperature of the absorbent solution in the absorbent crystallizer can be lowered into, thereby the consumption of low-temperature receiver can be saved.Preferable, at the bottom of the tower of regenerator, be delivered to the carbon dioxide absorption liquid of the first generation heat exchanger and at the bottom of the absorption Tata, between the absorption liquid that regenerator is carried, carry out heat exchange, enter the temperature of the carbon dioxide absorption liquid of regenerator with raising, thereby further improve the regeneration efficiency of the carbon dioxide absorption liquid of regenerator.
In the above embodiment of the present invention, described carbon dioxide absorption liquid is solution of potassium carbonate or aminated compounds solution.Preferable, described aminated compounds is monoethanolamine, diethanol amine, triethanolamine, diisopropanolamine (DIPA), methyl diethanolamine or diglycolamine; Described absorbent solution is made up of working medium and absorbent, and described working medium is water, ammonia, methyl alcohol, ethanol or its mixture etc., and described absorbent is LiBr, LiCl, LiNO 3, Li 2SO 4, ZnCl 2, ZnBr 2, NaCl, KCl, Na 2SO 4, K 2SO 4, NaBr, KBr, CaCl 2Or MgBr 2The perhaps mixture of above-mentioned each material.
Below by embodiment the exploitativeness of the foregoing description is described with concrete parameter.
Comparative example
This comparative example carries out the situation that carbon dioxide separation reclaims for adopting existing carbon dioxide separation technology shown in Figure 3 to coal-fired flue-gas.The carbon dioxide volume content of this coal-fired flue-gas is 15%, and temperature is 150 ℃, and pressure is 150kPa.Carbon dioxide absorption liquid is the mixed solution of the diethanol amine of the potash of mass content 25% and mass content 3%, the absorption temperature is that the temperature of carbon dioxide absorption tower inlet absorption liquid is 70 ℃, regeneration temperature is that the temperature of carbon dioxide regenerator bottom absorption liquid is 112 ℃, and the external heat source of regenerative heater adopts 120 ℃ saturated vapor.The carbon dioxide volume content of the absorption tower exit gas of this comparative example is 1%, and the carbon dioxide separation rate of recovery is 90%, and the regeneration energy consumption that per kilogram reclaims carbon dioxide is about 3200kJ.
Example
This example adopts embodiment 4 described methods, and the coal-fired flue-gas that institute separates recovery is all identical with above-mentioned comparative example with conditions such as the absorption liquid that is adopted, absorption temperature and regeneration temperatures.The thermal source of external heater adopts 80 ℃ hot water.The working medium of absorbent solution is water, and absorbent is LiNO 3With the mixture of LiBr, LiNO 3With the mol ratio of LiBr be 0.25, the absorbent solution of absorber is the saturated solution under the absorber operating temperature, and the absorbent solution of generator is the unsaturated solution under the generator operating temperature.Absorbent crystallizer adopts-18 ℃ external source.The carbon dioxide volume content of the absorption tower exit gas of this example is 1%, the carbon dioxide separation rate of recovery is 90%, the energy consumption that per kilogram by the external heater input reclaims carbon dioxide is about 400kJ, and the regeneration energy consumption that per kilogram reclaims carbon dioxide is about 750kJ.
The regeneration energy consumption of above-mentioned comparative example and example is defined as follows:
The quality that heat/institute separates the carbon dioxide of recovery of the regeneration energy consumption of comparative example=drop into by regenerative heater
The regeneration energy consumption of example=(heat by the external heater input+be used for the cold of absorbent crystallizer)/separate the quality of the carbon dioxide that reclaims
Following table 1 is the running parameter of above-mentioned example and comparative example.
Table 1
Figure S2008101155589D00101
For realizing that the necessary other technologies means of technique scheme all can adopt technology of the prior art to realize.
The above, it only is preferred embodiment of the present invention, be not that the present invention is done any pro forma restriction, though the present invention discloses as above with preferred embodiment, yet be not in order to limit the present invention, any those skilled in the art, in not breaking away from the technical solution of the present invention scope, when the technology contents that can utilize above-mentioned announcement is made a little change or is modified to the equivalent embodiment of equivalent variations, in every case be the content that does not break away from technical solution of the present invention, according to technical spirit of the present invention to any simple modification that above embodiment did, equivalent variations and modification all still belong in the scope of technical solution of the present invention.

Claims (11)

1. carbon dioxide separating system is characterized in that it comprises:
Carbon dioxide absorption tower is used for absorbing the carbon dioxide of carbon dioxide containing gas;
Carbon dioxide absorption liquid regenerator is connected with reboiler, is used for the regenerating carbon dioxide absorption liquid;
Generator is provided with first the heat exchanger and the second generation heat exchanger takes place in it, be filled with absorbent solution in this generator;
Absorber is filled with absorbent solution in it, be provided with the absorption heat exchanger in this absorber, is connected in described reboiler;
Steam channel is communicated with described generator and described absorber;
The concentration of absorbing of absorbent solution is lower than the concentration of absorbing of absorbent solution in the absorber in the described generator;
Described first inlet that heat exchanger takes place is connected in the absorption liquid outlet of above-mentioned carbon dioxide absorption liquid regenerator bottom, and first outlet that heat exchanger takes place connects the absorption liquid inlet on above-mentioned carbon dioxide absorption tower top; Described second inlet that heat exchanger takes place is connected in the gas vent at above-mentioned carbon dioxide absorption liquid regenerator top.
2. carbon dioxide separating system according to claim 1 is characterized in that it also comprises absorbent crystallizer, and this absorbent crystallizer comprises:
The crystallizer absorbent solution inlet is connected in absorber absorbent solution outlet and generator taphole by pipeline;
The crystallizer weak solution exports, and is connected in the absorbent solution inlet of generator by pipeline; And
Contain the crystallization solution delivery outlet, be connected in the absorbent solution inlet of absorber by pipeline.
3. carbon dioxide separating system according to claim 2, it is characterized in that it comprises that also absorbent solution is from heat exchanger, be arranged on described absorbent crystallizer and generator and the pipeline that absorber is connected, be used to enter the absorbent solution of absorbent crystallizer, from the weak solution of absorbent crystallizer output with from the heat exchange between the crystallization solution of containing of absorbent crystallizer output.
4. carbon dioxide separating system according to claim 1 is characterized in that it also comprises gas-liquid separator, is connected in the outlet of the above-mentioned second generation heat exchanger.
5. carbon dioxide separating system according to claim 1 is characterized in that also being provided with the external heat source heater in the described generator, is used to add the absorbent solution in the heater.
6. carbon dioxide separation method is used for separating the carbon dioxide of carbon dioxide containing gas, it is characterized in that this method may further comprise the steps:
Contact with carbon dioxide containing gas with carbon dioxide absorption liquid, absorb the carbon dioxide in the described gas;
Carbon dioxide absorption liquid behind the absorbing carbon dioxide is heated, regenerates then, and the absorbent solution that gas that regeneration forms and liquid divide two-way to be used to heat a low concentration, and produce working substance steam;
The laggard promoting the circulation of qi liquid of absorbent solution that the gas that regeneration forms has heated above-mentioned low concentration separates, and obtains carbon dioxide;
The liquid that regeneration forms has heated the carbon dioxide that is used for absorbing carbon dioxide containing gas after the absorbent solution of above-mentioned low concentration as carbon dioxide absorption liquid once more;
Above-mentioned working substance steam is absorbed by the absorbent solution of another high concentration and discharges and absorbs heat, the described carbon dioxide absorption liquid that absorbs after heat is used to heat above-mentioned absorbing carbon dioxide.
7. carbon dioxide separation method according to claim 6, the difference of absorbent molar fraction of absorbent solution that it is characterized in that the absorbent solution of wherein said low concentration and high concentration is greater than 0.1.
8. carbon dioxide separation method according to claim 7 is characterized in that the absorbent solution of part low concentration wherein and the absorbent solution of part high concentration are cooled, and forms crystallization, carries out Separation of Solid and Liquid then;
Weak solution after the Separation of Solid and Liquid is mixed with described lower concentration absorbing solution, contains crystallization solution and mixes with described high concentration absorbent solution.
9. carbon dioxide separation method according to claim 8 is characterized in that it also comprises: the absorbent solution of the part low concentration before above-mentioned being cooled and absorbent solution, the weak solution after the Separation of Solid and Liquid of part high concentration and contain and carry out heat exchange between the crystallization solution.
10. carbon dioxide separation method according to claim 9 is characterized in that adopting external source that the absorbent solution of part low concentration and the absorbent solution of part high concentration are cooled off.
11., it is characterized in that described carbon dioxide absorption liquid is the mixture of solution of potassium carbonate and aminated compounds solution one of them or above-mentioned each material according to each described carbon dioxide separation method of claim 6-10;
Described absorbent solution is made up of working medium and absorbent, and described working medium is the mixture of water, ammonia, methyl alcohol and ethanol one of them or several materials; Described absorbent is LiBr, LiCl, LiNO 3, Li 2SO 4, ZnCl 2, ZnBr 2, NaCl, KCl, Na 2SO 4, K 2SO 4, NaBr, KBr, CaCl 2And MgBr 2The mixture of one of them or several materials.
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