WO2023138706A1 - 一种含有可燃烧气体的混合气的脱碳脱硫方法 - Google Patents

一种含有可燃烧气体的混合气的脱碳脱硫方法 Download PDF

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WO2023138706A1
WO2023138706A1 PCT/CN2023/081522 CN2023081522W WO2023138706A1 WO 2023138706 A1 WO2023138706 A1 WO 2023138706A1 CN 2023081522 W CN2023081522 W CN 2023081522W WO 2023138706 A1 WO2023138706 A1 WO 2023138706A1
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gas
solution
decarbonization
sodium
hydrogen sulfide
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PCT/CN2023/081522
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English (en)
French (fr)
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刘志盛
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中国中煤能源集团有限公司
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    • C—CHEMISTRY; METALLURGY
    • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
    • C10K—PURIFYING OR MODIFYING THE CHEMICAL COMPOSITION OF COMBUSTIBLE GASES CONTAINING CARBON MONOXIDE
    • C10K1/00—Purifying combustible gases containing carbon monoxide
    • C10K1/002—Removal of contaminants
    • C10K1/003—Removal of contaminants of acid contaminants, e.g. acid gas removal
    • C10K1/005—Carbon dioxide
    • C—CHEMISTRY; METALLURGY
    • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
    • C10K—PURIFYING OR MODIFYING THE CHEMICAL COMPOSITION OF COMBUSTIBLE GASES CONTAINING CARBON MONOXIDE
    • C10K1/00—Purifying combustible gases containing carbon monoxide
    • C10K1/002—Removal of contaminants
    • C10K1/003—Removal of contaminants of acid contaminants, e.g. acid gas removal
    • C10K1/004—Sulfur containing contaminants, e.g. hydrogen sulfide
    • C—CHEMISTRY; METALLURGY
    • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
    • C10K—PURIFYING OR MODIFYING THE CHEMICAL COMPOSITION OF COMBUSTIBLE GASES CONTAINING CARBON MONOXIDE
    • C10K1/00—Purifying combustible gases containing carbon monoxide
    • C10K1/08—Purifying combustible gases containing carbon monoxide by washing with liquids; Reviving the used wash liquors
    • C10K1/10—Purifying combustible gases containing carbon monoxide by washing with liquids; Reviving the used wash liquors with aqueous liquids
    • C10K1/103—Purifying combustible gases containing carbon monoxide by washing with liquids; Reviving the used wash liquors with aqueous liquids alkali- or earth-alkali- or NH4 salts or inorganic acids derived from sulfur
    • C—CHEMISTRY; METALLURGY
    • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
    • C10K—PURIFYING OR MODIFYING THE CHEMICAL COMPOSITION OF COMBUSTIBLE GASES CONTAINING CARBON MONOXIDE
    • C10K1/00—Purifying combustible gases containing carbon monoxide
    • C10K1/08—Purifying combustible gases containing carbon monoxide by washing with liquids; Reviving the used wash liquors
    • C10K1/10—Purifying combustible gases containing carbon monoxide by washing with liquids; Reviving the used wash liquors with aqueous liquids
    • C10K1/12—Purifying combustible gases containing carbon monoxide by washing with liquids; Reviving the used wash liquors with aqueous liquids alkaline-reacting including the revival of the used wash liquors
    • C10K1/122—Purifying combustible gases containing carbon monoxide by washing with liquids; Reviving the used wash liquors with aqueous liquids alkaline-reacting including the revival of the used wash liquors containing only carbonates, bicarbonates, hydroxides or oxides of alkali-metals (including Mg)
    • C—CHEMISTRY; METALLURGY
    • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
    • C10K—PURIFYING OR MODIFYING THE CHEMICAL COMPOSITION OF COMBUSTIBLE GASES CONTAINING CARBON MONOXIDE
    • C10K1/00—Purifying combustible gases containing carbon monoxide
    • C10K1/20—Purifying combustible gases containing carbon monoxide by treating with solids; Regenerating spent purifying masses
    • C10K1/22—Apparatus, e.g. dry box purifiers
    • C—CHEMISTRY; METALLURGY
    • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
    • C10K—PURIFYING OR MODIFYING THE CHEMICAL COMPOSITION OF COMBUSTIBLE GASES CONTAINING CARBON MONOXIDE
    • C10K1/00—Purifying combustible gases containing carbon monoxide
    • C10K1/32—Purifying combustible gases containing carbon monoxide with selectively adsorptive solids, e.g. active carbon
    • Y—GENERAL 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
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
    • Y02P20/00—Technologies relating to chemical industry
    • Y02P20/151—Reduction of greenhouse gas [GHG] emissions, e.g. CO2

Definitions

  • the present invention relates to the field of decarbonization, desulfurization and purification of combustible mixed gas, in particular to a method for removing carbon dioxide and hydrogen sulfide from oilfield associated gas, shale gas, gas produced from natural gas fields, coal bed methane, and synthesis gas produced from coal and biomass energy.
  • the existing natural gas and synthesis gas purification technologies mainly include low-temperature methanol washing method and organic amine solvent absorption method.
  • Methanol and organic alcohol amine solvents have high solubility for CO 2 and H 2 S and low solubility for CO, hydrogen and nitrogen under low temperature and high pressure. Selective absorption performance. When the solution absorbing carbon dioxide and hydrogen sulfide is decompressed or heated, the gas solutes of carbon dioxide and hydrogen sulfide will be released from the solution into the gas phase, and the solution will be regenerated at the same time.
  • the solvent can continuously absorb carbon dioxide and hydrogen sulfide gas at high pressure and low temperature, and release gas at low pressure and high temperature, so as to realize the removal and purification of CO 2 and H 2 S in natural gas and syngas raw materials.
  • the solubility of hydrogen sulfide in the solvent is several times that of carbon dioxide and the absorption is fast, carbon dioxide and hydrogen sulfide can be released successively under different operating conditions, achieving the purpose of enriching hydrogen sulfide and carbon dioxide respectively.
  • low-temperature methanol washing can purify carbon dioxide and hydrogen sulfide in natural gas and syngas with high quality
  • process analysis that low-temperature methanol washing has the following inherent disadvantages: large temperature differences in different operating links require the construction of large-scale refrigeration equipment, which consumes steam heat and cooling water, and consumes a lot of electricity for methanol circulation; multi-stage decompression flashing is required to release carbon dioxide and hydrogen sulfide, and a large amount of pressure energy is lost; more equipment is invested in the process, and the pressure level and anti-corrosion level of equipment and pipelines are high, and the investment cost is high; there are carbon dioxide and hydrogen sulfide removal efficiency and hydrogen dissolution Loss, excessive energy consumption, and methanol loss; during flash evaporation, it is easy to cause hydrogen and hydrocarbon gas in the effective synthesis gas to flash into carbon dioxide, and the combustible gas in the mixed gas is reduced; methanol and organic alcohol amine solvents are hazardous chemicals, equipment pipeline leaks can easily lead
  • the domestic production technology of sodium sulfide is a batch method, and the production technology is relatively backward; second, the output of sodium sulfide is not enough to support the removal of carbon dioxide in coal chemical and petrochemical industries; third, the toxic substance hydrogen sulfide will be produced after the sodium sulfide solution absorbs carbon dioxide.
  • Sodium sulfide has a high solubility in water, and 1 molecule of sodium sulfide can absorb 2 molecules of carbon dioxide.
  • the generated hydrogen sulfide has a high calorific value and can be processed into sulfur and sulfuric acid.
  • sodium sulfide can be produced continuously and in large quantities, its production cost will be greatly reduced. It will become feasible to use sodium sulfide to absorb carbon dioxide to purify syngas and natural gas, and realize the integrated technology route of energy gas carbon dioxide capture, storage and desulfurization.
  • the low temperature methanol washing process has a large temperature difference with the upstream gasification and transformation section, resulting in a large amount of energy consumption and waste.
  • the meaning of this method homologous three alkalis is that three kinds of alkalis are all derived from the production of sodium sulfide,
  • Carbon dioxide is absorbed by sodium sulfide, hydrogen sulfide is absorbed by sodium hydroxide, caustic soda is produced by sodium carbonate, and the three alkalis realize the linkage cycle.
  • a method for decarburization and desulfurization of a mixed gas containing a combustible gas comprising the steps of:
  • Preparation of decarbonization tower absorption liquid add Na 2 S and deionized water to the buffer tank at the top of the decarbonization tower to form a decarbonization tower absorption liquid;
  • Decarbonization tower absorption liquid washes raw material mixture: inject the absorption liquid in the decarbonization tower top buffer tank in step (1) into the top of the decarbonization tower, feed the raw material mixture gas containing carbon dioxide from the bottom of the decarbonization tower, supplement low-temperature deionized water in the middle of the decarbonization tower, the exhaust gas from the top of the decarbonization tower enters the hydrogen sulfide separation unit, the bottom product of the decarbonization tower enters the decarbonization tower bottom buffer tank, and the thick solid phase slurry of the decarbonization tower bottom buffer tank is discharged to NaHCO 3
  • the solution is placed in the crystallization and liquid-solid separation unit, and the weak liquid is discharged from the buffer tank at the bottom of the decarbonization tower into the buffer tank at the top of the decarbonization tower in step (1) to supplement the absorption liquid of the decarbonization tower; the sulfur ions in the absorption liquid are replaced by carbon dioxide into hydrogen sulfide or hydrogen sulfide, and carbonate or hydrogen carbonate
  • Step (2) The hydrogen sulfide-containing gas discharged from the top of the decarbonization tower enters the hydrogen sulfide separation unit, and the hydrogen sulfide separation unit uses membrane separation or pressure swing adsorption separation method to separate most of the hydrogen sulfide in the exhaust gas of the decarbonization tower to form decarbonized sulfur-rich gas and/or decarbonized sulfur-poor gas;
  • Decarbonization and sulfur-rich gas treatment send decarbonization and sulfur-rich gas with high concentration of H 2 S to the hydrogen sulfide treatment unit to prepare sulfur or sulfuric acid;
  • Decarburization and sulfur-poor gas scrubbing send the decarbonized and sulfur-depleted gas with low concentration of H 2 S to the sulfur-depleted gas sodium hydroxide scrubber, and the exhaust gas at the top of the tower is decarbonized, desulfurized and purified gas; part of the tower bottom solution is circulated into the tower top buffer tank, and the other part is sent to the decarbonization tower top buffer tank in step (1) to supplement the decarbonization tower absorption liquid;
  • the thick solid phase slurry discharged from the buffer tank at the bottom of the decarbonization tower in step (2) enters the NaHCO 3 solution for static crystallization and liquid-solid separation unit, and the separated solid material is sent to the NaHCO 3 drying equipment; the separated mother liquor is sent to the buffer tank at the top of the decarbonization tower in step (1) to supplement the absorption liquid of the decarbonization tower;
  • step (6) Thermal decomposition of NaHCO 3 : the NaHCO 3 solid material produced in step (6) can be used for product output after drying, part of the sodium bicarbonate is heated and decomposed to produce sodium carbonate products, and the mixed gas produced by the decomposition is condensed and cooled, and the gas phase is sent to step (2) together with the raw material mixed gas for decarburization;
  • caustic soda production add deionized water and calcium oxide in the causticizing reactor, and Na CO produced in step (7) is put into the solution of the causticizing reactor as raw material for caustic soda production; the precipitated calcium carbonate is separated to obtain calcium carbonate solid, which is sent to step (9) as raw material for calcined calcium carbonate, and the NaOH solution generated is sent to step (5) sulfur-deficient sodium hydroxide washing tower top buffer tank;
  • step (8) Calcination of calcium carbonate: calcining the calcium carbonate produced in step (8), the calcined gas phase product is sent to step (2) for decarburization together with the raw material mixed gas after recovering heat; the calcined solid phase product calcium oxide is sent as raw material to step (8) caustic soda production process.
  • the temperature of the absorption solution prepared in step (1) is 30-90°C, the sodium sulfide content per 100g of water is 0-0.735mol, and the temperature of the deionized water is lower than the temperature of the absorption solution;
  • step (2) Na 2
  • the amount of S solution added and the feed amount of raw material mixed gas are adjusted according to the pH value of the solution.
  • the pH value of the absorbing liquid after absorbing carbon dioxide gradually decreases: sodium sulfide absorbs a small amount of carbon dioxide to form sodium bisulfide and sodium carbonate, and less hydrogen sulfide is precipitated; the solution continues to absorb carbon dioxide, and when the sulfur ions in the solution are nearly consumed, a large amount of hydrogen sulfide begins to precipitate.
  • the solution no longer has the ability to absorb carbon dioxide; the hydrogen sulfide-rich gas is sent to step (4) for decarbonization and sulfur-rich gas treatment through the pipeline, and the hydrogen sulfide-depleted gas is sent to step (5) for decarbonization and sulfur-poor gas treatment through the pipeline.
  • step (2) according to the carbon dioxide concentration and feed amount of the raw material gas, in order to timely discharge the sodium carbonate or sodium bicarbonate solids in the solution, a multi-tower series connection method is set up for multi-stage decarburization washing; the sodium sulfide content, sodium bisulfide content, and sodium carbonate content in the absorption liquid components of decarbonization washing towers at each level are different.
  • the decarburization tower has strong acid and alkali resistance, and is a tower container with a mixing and stirring device or a liquid-solid mixed discharge
  • the absorption tower can carry out gas-liquid-solid three-phase reaction, and has the adjustment means to avoid the growth of sodium bicarbonate crystal nuclei and avoid the static precipitation of solid phase materials.
  • the hydrogen sulfide treatment unit in step (4) is equipped with a sulfur recovery unit and/or a sulfuric acid unit and/or a hydrogen sulfide electrolysis unit.
  • the materials produced in each step of the production process are coupled with the materials that need to be input, and the heat of reaction in the production process is coupled with the heat of the reaction process that requires heating.
  • the present invention uses sodium sulfide to absorb carbon dioxide with high solubility and high efficiency, separates hydrogen sulfide through coupled membrane separation and pressure swing adsorption technology, superimposes sodium hydroxide washing to absorb refined purification gas, combines calcined calcium carbonate and causticization to prepare caustic soda, and uses sodium sulfide to absorb carbon dioxide
  • the sodium bicarbonate obtained from the carbon is decomposed to obtain the soda ash raw material for the causticization process of caustic soda, which realizes the complete cycle of materials in the process.
  • the chemical principle utilized in the present invention is that, according to different ionization constants, the acidic relationship between carbon dioxide, hydrogen sulfide and hydrogen radical ions thereof is as follows:
  • the solubility of saturated sodium carbonate corresponding to 100 grams of water is 0.43-0.46 moles, and the solubility of sodium bicarbonate is below 0.2 moles. Since 1 mole of sodium carbonate can produce 2 moles of sodium bicarbonate and consume 1 mole of solvent water, about 70% of sodium bicarbonate crystalline solids will be precipitated when saturated sodium carbonate absorbs carbon dioxide. The sodium hydrogen slurry is discharged in time.
  • the solubility of sodium sulfide in water increases with the increase of temperature. At 60°C, the solubility of saturated sodium sulfide corresponding to 100 grams of water is 0.398 moles, and the solubility of sodium carbonate is 0.438 moles. Since 1 mole of sodium carbonate can produce 1 mole of sodium bicarbonate and consume 1 mole of solvent water, a small amount of sodium carbonate crystalline solid will be precipitated when saturated sodium carbonate absorbs carbon dioxide.
  • the initial operating temperature is above 60°C.
  • a multi-stage sodium sulfide washing process for absorbing carbon dioxide at different temperatures can be set up
  • the reaction process can be monitored according to the pH.
  • the sodium sulfide content, sodium hydrosulfide content, and sodium carbonate content in the absorption liquid components of decarbonization scrubbers at different levels are different, and the pH value of the absorption liquid is different, and the hydrogen sulfide increment in the exhaust gas is also different.
  • the present invention has high operating temperature and no requirement for operating pressure, and can use the heat and pressure energy of the transformed gas produced by the upstream transforming device for turbine work, reducing the pressure level of the equipment and materials of the method.
  • the liquid phase operation temperature can be maintained at 0-100°C.
  • the sodium sulfate reduction, sodium bicarbonate decomposition, and calcined limestone processes can be coupled with the high-temperature heat source of the conversion device and the sulfuric acid and sulfur devices, and no refrigeration process and equipment are required.
  • the present invention does not need a solvent regeneration process, and the sodium bicarbonate thermally decomposes to produce sodium carbonate.
  • the unit decomposes according to the demand for sodium hydroxide to wash hydrogen sulfide, and the amount depends on the hydrogen sulfide removal efficiency of the hydrogen sulfide separation unit.
  • the present invention does not require a large amount of circulation of the solution, and the mother liquor separated from sodium bicarbonate can be evaporated or reused depending on the fluidity and discharge of the product mixture; the operating pressure of the present invention has little influence on the process of chemically absorbing carbon dioxide.
  • the operating pressure of sodium sulfide absorbing carbon dioxide should be set with reference to the pressure requirements of the hydrogen sulfide separation unit, or an additional blower is added to transport the decarburized gas to the hydrogen sulfide treatment unit.
  • the method does not involve the operation of flashing and desorbing carbon dioxide in the low-temperature methanol eluting carbon process, and the loss of pressure energy is small.
  • the present invention does not need to set up flash decarburization, hydrogen sulfide concentration, solvent regeneration, solvent rectification and other processes, and the corresponding towers, heat exchangers, tanks, pumps and other pipelines and equipment reduce investment costs and low.
  • the invention is a chemical absorption process, the process and operation are simple, and the removal efficiency of carbon dioxide and hydrogen sulfide is high; in the reaction process of the invention, the solubility of hydrogen and hydrocarbons in the aqueous solution is extremely small, and the hydrogen and hydrocarbons in the effective synthesis gas will not be reduced.
  • the solvent of the present invention is an aqueous solution such as sodium sulfide, sodium carbonate, sodium hydroxide, etc., which are not flammable or explosive chemicals. The leakage of liquid from equipment pipelines will not cause fire and explosion accidents, and the toxicity of the above three substances is lower than that of methanol and organic amines.
  • Carbon dioxide is removed with carbonate ions to realize the integration of one-step carbon dioxide capture and storage and device integration; the source of sodium sulfide in the present invention can be obtained by reducing sodium sulfate with hydrogen. Hydrogen can be provided by electrolytic hydrogen production. At the same time as carbon dioxide in the mixed gas, sodium bicarbonate, sodium carbonate, sulfur and sulfuric acid products can be produced by-products, and then the sodium sulfide raw material can also be expanded from sodium sulfate to sodium chloride to obtain hydrochloric acid.
  • the present invention can provide an application outlet for the by-product sodium sulfate and sodium chloride in the industrial field.
  • Figure 1 is a schematic diagram of material input and output in Example 1 of the present invention.
  • Figure 2 is a schematic diagram of material input and output in Example 2 of the present invention.
  • Figure 3 is a schematic diagram of the process flow of Example 1 of the present invention.
  • Figure 4 is a schematic diagram of the process flow of Example 2 of the present invention.
  • the embodiments of the present invention are a further elaboration of a mixed gas decarburization and desulfurization process that utilizes a sodium sulfide solution to absorb carbon dioxide described in the invention, and is not a limitation.
  • the described embodiments are some of the embodiments of the present invention, rather than all of them. Based on the embodiments of the present invention, all other embodiments obtained by persons of ordinary skill in the art without making creative work all belong to the scope of protection of the present invention.
  • sodium sulfide is supplied as the solute raw material, and all hydrogen sulfide produced is output as a product.
  • the raw material mixture gas is the converted synthesis gas from the crude synthesis gas produced by the gasifier, and its volume composition is 47.4% hydrogen, 20.8% carbon monoxide, 31% carbon dioxide, 0.3% hydrogen sulfide, 0.2% nitrogen, 0.1% methane, and 0.2% other.
  • the Na 2 S solution preparation temperature is close to the temperature of the raw material mixed gas, and through coupling with other exothermic process unit processes, the raw material mixed gas and Na 2 S solution are controlled at a higher temperature, controlled at 80-90°C; the Na 2 S solution preparation concentration is based on the mass of Na 2 S in 100 grams of solvent water is not greater than 0.77 times the solubility of the saturated solution at this temperature. With the introduction of carbon dioxide, the solvent water will be continuously consumed.
  • the concentration of the solution can be adjusted according to the water content in the raw material mixture and the water replenishment in the process of sodium sulfide absorbing carbon dioxide.
  • the impurities of the Na2S raw material we use cannot affect the absorption and precipitation of CO2 by Na2S, nor can it affect the desorption of H2S.
  • Sodium sulfide impurities do not contain organic hydrocarbons.
  • the decarbonization tower is like a container with a stirring device or an absorption tower with a liquid-solid phase mixed discharge, and has strong acid and alkali resistance.
  • the decarburization tower should be equipped with adjustment means to avoid the growth of sodium bicarbonate crystal nuclei and avoid the static precipitation of solid phase materials, so as to prevent the accumulation of sodium carbonate and sodium bicarbonate in the equipment due to low solubility, making it difficult for the liquid-solid mixture to be discharged to downstream equipment.
  • the amount of Na 2 S solution added and the amount of raw material mixed gas are adjusted according to the pH of the solution: along with the reaction of the raw material mixed gas and the sodium sulfide solution, the pH of the solution gradually decreases.
  • the pH starts to be less than 9.4 the sodium sulfide in the solution is basically consumed and hydrogen sulfide is no longer desorbed, and the solution begins to produce bicarbonate ions;
  • the pH starts to be less than 8.3 the carbonate ions are basically used up and the solution no longer has the ability to absorb carbon dioxide;
  • the optimal control value is 8.4 to prevent the carbon dioxide content in the decarburized gas from being too high, and increase the load of subsequent sodium hydroxide washing to absorb hydrogen sulfide.
  • Step (2) The hydrogen sulfide-containing gas discharged from the top of the decarbonization tower enters the hydrogen sulfide separation unit, and the hydrogen sulfide separation unit uses membrane separation or pressure swing adsorption separation method to separate most of the hydrogen sulfide in the exhaust gas of the decarbonization tower to form decarbonized sulfur-rich gas and decarbonized sulfur-poor gas; after absorbing carbon dioxide by sodium sulfide, the decarbonized gas is rich in hydrogen sulfide gas and enters the hydrogen sulfide separation device for treatment.
  • the hydrogen sulfide gas is sent to the sodium hydroxide absorbing hydrogen sulfide unit through the pipeline for treatment.
  • the hydrogen sulfide separation device is configured as a membrane separation or pressure swing adsorption separation process to make full use of the pressure energy of the raw material mixture.
  • the decarbonized hydrogen sulfide-poor gas enters the sodium hydroxide solution to wash and absorb the carbon dioxide device, and discharges the decarbonized and desulfurized purified gas.
  • the sodium hydroxide solution is provided by the sodium hydroxide produced in the caustic soda process.
  • Decarbonization and sulfur-rich gas treatment Send the decarbonization and sulfur-rich gas with high concentration of H 2 S to the hydrogen sulfide treatment device to prepare sulfur or sulfuric acid.
  • the hydrogen sulfide treatment unit is equipped with sulfur recovery unit and/or sulfuric acid unit and/or hydrogen sulfide electrolysis unit.
  • Decarbonization and sulfur-poor gas scrubbing send the decarbonized and sulfur-poor gas with low H 2 S concentration to the sulfur-poor gas scrubber, and the exhaust gas at the top of the tower is decarbonized and desulfurized purified gas; the NaOH solution prepared in steps (7) and (8) is sent to the top buffer tank of the sulfur-poor gas scrubber; part of the bottom solution of the sulfur-poor gas scrubber is circulated into the top buffer tank of the sulfur-poor gas scrubber, and the other part is sent to the top buffer tank of the decarbonization tower in step (1) to supplement the decarbonization tower absorption liquid.
  • step (2) Disposal of the solid-liquid mixture after absorbing carbon dioxide: the thick solid phase slurry discharged from the buffer tank at the bottom of the decarbonization tower in step (2) enters the NaHCO 3 solution for static crystallization and liquid-solid separation device, and the separated solid material is sent to the NaHCO 3 drying equipment; after separation
  • the mother liquor is sent to the buffer tank at the top of the decarburization tower in step (1), and the decarburization tower absorbing liquid is supplemented.
  • the NaHCO 3 solid material produced in step (6) can be used as a product output after drying, part of the sodium bicarbonate is heated and decomposed to produce sodium carbonate products, and the mixed gas produced by the decomposition is condensed and cooled, and the gas phase is sent to step (2) together with the raw material mixed gas for decarburization.
  • caustic soda production deionized water and calcium oxide are added to the causticizing reactor, and the Na2CO3 produced in step (7) is put into the solution of the causticizing reactor as a raw material for causticizing caustic soda; the precipitated calcium carbonate is separated to obtain calcium carbonate solid, and the calcium carbonate is sent to step (9) as a raw material for calcined calcium carbonate, and the generated NaOH solution is sent to step (5) sulfur-deficient sodium hydroxide washing tower top buffer tank.
  • step (8) The calcium carbonate produced in step (8) is calcined, and the calcined gas-phase product is sent to step (2) for decarburization together with the raw material gas mixture after recovering heat; the calcined solid-phase product calcium oxide is sent as a raw material to step (8) caustic soda production process.
  • self-produced sodium sulfide is used as the solute raw material for absorbing carbon dioxide, and the hydrogen sulfide produced is processed into sulfuric acid through the hydrogen sulfide treatment unit.
  • the sulfuric acid and sodium chloride can be prepared to obtain sodium sulfate and hydrochloric acid, and the prepared sodium sulfate is used for the production of sodium sulfide.
  • the raw material mixed gas is the converted synthesis gas from the crude synthesis gas produced by the gasifier, and its volume composition is 47.4% hydrogen, 20.8% carbon monoxide, 31% carbon dioxide, 0.3% hydrogen sulfide, 0.2% nitrogen, 0.1% methane, and 0.2% other.
  • the reducing gas for the production of sodium sulfide is provided by clean energy power generation and hydrogen production. The purpose of this embodiment is to reduce carbon emissions through green hydrogen supplementation and achieve zero carbon emissions in coal chemical industry.
  • the Na 2 S solution preparation temperature is close to the temperature of the raw material mixed gas, and through coupling with other exothermic process unit processes, the raw material mixed gas and Na 2 S solution are controlled at a higher temperature, controlled at 80-90°C; the Na 2 S solution preparation concentration is based on the mass of Na 2 S in 100 grams of solvent water is not greater than 0.77 times the solubility of the saturated solution at this temperature. With the introduction of carbon dioxide, the solvent water will be continuously consumed.
  • the concentration of the solution can be adjusted according to the water content in the raw material mixture and the water replenishment in the process of sodium sulfide absorbing carbon dioxide.
  • the impurities of the Na2S raw material we use cannot affect the absorption and precipitation of CO2 by Na2S, nor can it affect the desorption of H2S.
  • Sodium sulfide impurities do not contain organic hydrocarbons.
  • the decarbonization tower is like a container with a stirring device or an absorption tower with a liquid-solid phase mixed discharge, and has strong acid and alkali resistance.
  • the decarburization tower should be equipped with adjustment means to avoid the growth of sodium bicarbonate crystal nuclei and avoid the static precipitation of solid phase materials, so as to prevent the accumulation of sodium carbonate and sodium bicarbonate in the equipment due to low solubility, making it difficult for the liquid-solid mixture to be discharged to downstream equipment.
  • the amount of Na 2 S solution added and the feed amount of the raw material mixed gas are adjusted according to the pH of the solution: along with the reaction of the raw material mixed gas and the sodium sulfide solution, the pH of the solution gradually decreases.
  • the pH starts to be less than 9.4 the sodium sulfide in the solution is basically consumed and
  • Hydrogen sulfide is no longer desorbed, and the solution begins to produce bicarbonate ions; when the pH begins to be less than 8.3, the carbonate ions are
  • the pH value of the solution is greater than 8.3, and the preferred control value is 8.4, so as to prevent the carbon dioxide content in the decarburization gas from being too high, and increase the load of subsequent sodium hydroxide washing to absorb hydrogen sulfide.
  • Step (2) The hydrogen sulfide-containing gas discharged from the top of the decarbonization tower enters the hydrogen sulfide separation unit, and the hydrogen sulfide separation unit uses membrane separation or pressure swing adsorption separation method to separate most of the hydrogen sulfide in the exhaust gas of the decarbonization tower to form decarbonized sulfur-rich gas and decarbonized sulfur-poor gas; after absorbing carbon dioxide by sodium sulfide, the decarbonized gas is rich in hydrogen sulfide gas and enters the hydrogen sulfide separation device for treatment.
  • the hydrogen sulfide gas is sent to the sodium hydroxide absorbing hydrogen sulfide unit through the pipeline for treatment.
  • the hydrogen sulfide separation device is configured as a membrane separation or pressure swing adsorption separation process to make full use of the pressure energy of the raw material mixture.
  • the decarbonized hydrogen sulfide-poor gas enters the sodium hydroxide solution to wash and absorb the carbon dioxide device, and discharges the decarbonized and desulfurized purified gas.
  • the sodium hydroxide solution is provided by the sodium hydroxide produced in the caustic soda process.
  • Decarbonization and sulfur-rich gas treatment Send the decarbonization and sulfur-rich gas with high concentration of H 2 S to the hydrogen sulfide treatment device to prepare sulfur or sulfuric acid.
  • the hydrogen sulfide treatment unit is equipped with a sulfur recovery unit and/or a sulfuric acid unit and/or a hydrogen sulfide electrolysis unit.
  • Decarbonization and sulfur-poor gas scrubbing send the decarbonized and sulfur-poor gas with low H 2 S concentration to the sulfur-poor gas scrubber, and the exhaust gas at the top of the tower is decarbonized and desulfurized purified gas; the NaOH solution prepared in steps (7) and (8) is sent to the top buffer tank of the sulfur-poor gas scrubber; part of the bottom solution of the sulfur-poor gas scrubber is circulated into the top buffer tank of the sulfur-poor gas scrubber, and the other part is sent to the top buffer tank of the decarbonization tower in step (1) to supplement the decarbonization tower absorption liquid.
  • this embodiment sets multiple towers connected in series to perform multi-stage desulfurization washing, and the concentration and circulation volume of sodium hydroxide solution at each stage are different.
  • concentration of sodium hydroxide is 30%, 20%, and 10% to set up a three-stage alkaline cleaning process.
  • the thick solid phase slurry discharged from the buffer tank at the bottom of the decarbonization tower in step (2) enters the NaHCO 3 solution for static crystallization and liquid-solid separation device, and the separated solid material is sent to the NaHCO 3 drying equipment; the separated mother liquor is sent to the buffer tank at the top of the decarbonization tower in step (1) to supplement the absorption liquid of the decarbonization tower.
  • the NaHCO 3 solid material produced in step (6) can be used as a product output after drying, part of the sodium bicarbonate is heated and decomposed to produce sodium carbonate products, and the mixed gas produced by the decomposition is condensed and cooled, and the gas phase is sent to step (2) together with the raw material mixed gas for decarburization.
  • caustic soda production deionized water and calcium oxide are added to the causticizing reactor, and the Na2CO3 produced in step (7) is put into the solution of the causticizing reactor as a raw material for causticizing caustic soda; the precipitated calcium carbonate is separated to obtain calcium carbonate solid, and the calcium carbonate is sent to step (9) as a raw material for calcined calcium carbonate, and the generated NaOH solution is sent to the top buffer tank of step (5) sulfur-deficient sodium hydroxide washing tower.
  • step (8) The calcium carbonate produced in step (8) is calcined, and the calcined gas-phase product is sent to step (2) for decarburization together with the raw material gas mixture after recovering heat; the calcined solid-phase product calcium oxide is sent as a raw material to step (8) caustic soda production process.
  • the present invention uses sodium sulfide solution to chemically absorb carbon dioxide to generate sodium carbonate, which can continue to absorb carbon dioxide and generate sodium bicarbonate ions and precipitates; the mixed gas is absorbed to form decarbonized gas containing hydrogen sulfide, and the decarburized gas is separated into decarburized sulfur-rich gas and decarbonized sulfur-poor gas through membrane separation or pressure swing adsorption process; Caustic soda is produced by alkali and calcium oxide through causticization, which can meet the demand for caustic soda for washing hydrogen sulfide with sodium hydroxide.
  • the sulfuric acid produced by the sulfuric acid plant can react with sodium chloride to obtain sodium sulfate and hydrochloric acid, and the sodium sulfate can react with purified gas to obtain sodium sulfide, so as to realize the circular replenishment of sodium sulfide.
  • the raw material mixed gas that can be purified in the present invention has no upper and lower limit requirements for the concentration of carbon dioxide and hydrogen sulfide.
  • the process steps include: preparation of Na 2 S solution, absorption of CO 2 by Na 2 S solution, separation of H 2 S, treatment of H 2 S, liquid-solid separation of NaHCO 3 ,
  • NaHCO 3 drying and thermal decomposition, caustic caustic soda production, calcined calcium carbonate, sodium hydroxide absorption of H 2 S consists of 9 process steps; it is characterized in that the raw material gas to be processed contains H 2 , CO, CH 4 , N 2 , H 2 S, SO 2 , H 2 O, rare gases, hydrocarbons
  • the raw mixed gas can be made of coal, residual oil or biomass
  • the sodium sulfide in the solution is basically consumed and hydrogen sulfide is no longer desorbed, and the solution starts to produce bicarbonate ions; when the pH starts to be less than 8.3, the carbonate ions are basically consumed and the solution no longer has the ability to absorb carbon dioxide.
  • the liquid-solid mixture discharged from the Na 2 S solution absorbing CO 2 equipment enters the NaHCO 3 solution static separation equipment. After the solid-liquid mixture is statically separated, the mother liquor is discharged to the sodium sulfide solution preparation equipment as part of the solution, and the solid phase is discharged to the sodium bicarbonate solid drying equipment.
  • the heat source of the dry sodium bicarbonate equipment can use the high-temperature gas produced by calcium carbonate calcination and sodium bicarbonate thermal decomposition. After the dried gas is condensed, it can be added to the Na 2 S solution preparation process to supplement solvent water.
  • the high-temperature carbon dioxide gas heat source can be sent to the sodium sulfide solution to absorb carbon dioxide after the heat energy is used by the dried sodium bicarbonate solid.
  • the Na 2 S solution absorbs the decarbonized gas discharged from the CO 2 equipment and enters the hydrogen sulfide separation unit.
  • the hydrogen sulfide separation unit produces at least two kinds of hydrogen sulfide-rich gas and hydrogen sulfide-poor gas.
  • the hydrogen sulfide-rich gas is sent to the hydrogen sulfide treatment unit through the pipeline, and the hydrogen sulfide-poor gas is sent to the sodium hydroxide absorption hydrogen sulfide unit through the pipeline.
  • the decarbonized hydrogen sulfide-poor gas enters the sodium hydroxide solution to wash and absorb the carbon dioxide unit, and discharges the decarbonized and desulfurized purified gas.
  • the sodium hydroxide solution is supplied by the sodium hydroxide produced in the caustic soda process.
  • the sodium carbonate in the caustic soda production process is provided by the sodium carbonate produced by the decomposition of sodium bicarbonate.
  • the calcium carbonate precipitate produced in the caustic soda production process is sent to the calcium carbonate calcination process.
  • the calcium oxide produced by the calcined calcium carbonate is sent to the caustic soda production process to produce sodium hydroxide.
  • the carbon dioxide produced by the calcined calcium carbonate is sent to the sodium sulfide absorption carbon dioxide process after recovering heat.
  • Sodium sulfide can be provided by the upstream workshop or purchased.
  • a sodium sulfide reduction unit can be configured upstream to produce sodium sulfide, and it can also be obtained by absorbing hydrogen sulfide from sodium hydroxide. While reducing sodium sulfate to produce sodium sulfide unit to produce sodium sulfide, it can also produce process water and tail gas washing sodium carbonate and sodium bicarbonate materials. These materials and waste heat can be coupled with the material and heat of this method.
  • This method retains the power of any material and heat coupling between sodium sulfide production and sodium sulfide absorption carbon dioxide and sodium hydroxide absorption carbon dioxide and hydrogen sulfide units to produce process changes, and any simple changes will not lead to fundamental changes in the innovation and novelty of this method.
  • the purification gas after desulfurization and decarburization can also be used to restore sodium sulfate to produce sodium sulfide, thereby achieving self -sufficiency of sodium sulfide soluble by circulating. It can prepare a combination of hydrogen sulfide treatment unit as a combination of sulfur recovery device, sulfuric acid device or hydrogen sulfide electrolytic device and above. For raw materials, sodium sulfide is converted into sodium sulfate. At the same time, it is produced by producing products. Sodium sulfate products can be used to produce sodium sulfide raw materials, and decarburized desulfurization gas is used for the reduction of sodium sulfate.
  • the materials produced in each step are coupled with the materials that need to be input, and the heat of reaction in the production process is coupled with the heat of the reaction process that needs to be heated.
  • the pipeline of S solution preparation equipment includes supplementary Na 2 S pipeline, make up deionized water pipeline, absorb H by sodium hydroxide 2 Na returned by the S device 2 S solution pipeline, NaHCO 3 Clear liquid discharge material pipeline and its auxiliary pipeline of solution liquid-solid separation equipment; Na 2 The liquid discharge line of the S solution preparation equipment and Na 2 S solution absorbs CO 2 Device connection; Na 2 S solution absorbs CO 2 The liquid-solid mixture of the equipment is discharged from the material pipeline with NaHCO 3 Solution static and liquid-solid separation equipment connection; NaHCO 3 The solid discharge material pipeline of the solution liquid-solid separation equipment and NaHCO 3 Drying equipment connection; NaHCO 3 The solid discharge material pipeline of the drying equipment and NaHCO 3 Decomposition device connection; NaHCO 3 The gas phase discharge pipe of the decomposition equipment and Na 2 S solution absorbs CO 2 Device connection; NaHCO 3 The mother liquor discharge pipe of the solution static separation equipment

Abstract

一种含有可燃烧气体的混合气的脱碳脱硫方法，涉及混合气中二氧化碳和硫化氢的净化技术领域，该方法用硫化钠溶液化学吸收二氧化碳；脱碳后的混合气富含硫化氢；脱碳富硫气经硫磺装置或者硫酸装置生成硫磺或硫酸，脱碳贫硫气经氢氧化钠吸收硫化氢后产出脱碳脱硫净化气；中间产物碳酸氢钠经热分解生成纯碱，经苛化法制得烧碱，用于氢氧化钠洗涤硫化氢。生产过程中的每一个步骤产出的物料与需要投入的物料实现物料耦合，生产过程中的反应热与需要加热的反应过程实现热量耦合。将能源气体二氧化碳捕集和封存及脱硫的一体化，能够连续化大量生产硫化钠，大幅降低生产成本，利用硫化钠吸收二氧化碳来净化合成气和天然气。

Description

一种含有可燃烧气体的混合气的脱碳脱硫方法 技术领域
 本发明涉及可燃混合气的脱碳脱硫净化领域，具体涉及一种脱除油田伴生气、页岩气、天然气田采出气、煤层气和煤炭及生物质能源制造的合成气中的二氧化碳及硫化氢的脱除方法。
 背景技术
 现有天然气和合成气的净化技术主要有低温甲醇洗法和有机胺溶剂吸收法，甲醇和有机醇胺溶剂在低温高压下具有对CO 2及H 2S溶解度大，且对CO、氢气和氮气溶解度小的选择性吸收性能。而这种吸收二氧化碳和硫化氢的溶液在减压或者加热升温时，二氧化碳和硫化氢气体溶质会从溶液中释放到气相中，同时溶液得到再生。利用上述特点，溶剂可以不断进行高压和低温时吸收二氧化碳和硫化氢气体，在低压和高温时释放气体的溶剂循环操作，从而实现天然气和合成气原料中CO 2和H 2S的脱除净化。根据硫化氢在溶剂中溶解度是二氧化碳的数倍且吸收快的特点，又能够将二氧化碳和硫化氢在不同的操作条件下先后进行释放，达到了分别富集硫化氢和二氧化碳的目的。目前涉及合成气净化的大型煤化工项目均配套低温甲醇洗工艺，涉及天然气气田和炼厂的烃类气脱硫均配套有机醇胺溶剂吸收硫化氢的工艺，也有很小一部分项目选择变压吸附或者膜回收法脱除硫化氢和二氧化碳。对这几种工艺的优缺点，国内生产企业、设计公司和科研院校均有详细的分析比较和实践总结。虽然低温甲醇洗能够高质量地净化天然气和合成气中的二氧化碳及硫化氢，但通过流程分析可知，低温甲醇洗存在以下固有缺点：不同操作环节温差大，需同时配备建设大型制冷设备，需要消耗蒸汽热量和冷却水，消耗大量电能进行甲醇循环；需要进行多级的减压闪蒸释放二氧化碳和硫化氢，损失了大量的压力能；投入工艺的设备较多，且设备及管线的压力等级和防腐等级高，投资成本高；存在二氧化碳和硫化氢脱除效率低、氢气溶解损失、能耗偏大及甲醇损耗的现象；在闪蒸时易造成有效合成气中氢气和烃类气闪蒸进入二氧化碳中，混合气中可燃气体的减损；甲醇和有机醇胺溶剂均为危化品，设备管线泄露易导致火灾爆炸事故，且甲醇有毒；吸收和解吸二氧化碳过程与二氧化碳和硫化氢解吸过程之间没有清晰的界限，在吸收硫化氢的同时，伴随着吸收二氧化碳。
 目前，利用氢氧化钠溶液化学吸收二氧化碳和硫化氢的项目，一般用于含量很少的硫化氢和二氧化碳混合气气体的脱除精制，其根本原因在于氢氧化钠成本高昂。例如在甲醇制烯烃工艺中的烯烃分离装置中，需用氢氧化钠洗涤吸收其中的二氧化碳；在炼油厂催化裂化产出的气分装置前，需用氢氧化钠溶液洗涤其中携带的微量硫化氢和硫醇。
 目前，利用硫化钠溶液洗涤吸收二氧化碳的工艺国内鲜有研究和应用，其原因可能在于：一是国内硫化钠为间歇法生产技术，生产技术相对落后；二是硫化钠产量不足以支撑煤化工和石油化工中二氧化碳的脱除，三是硫化钠溶液吸收二氧化碳后会产出硫化氢这一有毒物质。硫化钠在水中的溶解度很高，并且1分子硫化钠能吸收2分子二氧化碳，生成的硫化氢热值高，可加工成硫磺和硫酸，如果硫化钠能够连续化大量生产，其生产成本大幅下降，利用硫化钠吸收二氧化碳来净化合成气和天然气将变得可行，实现能源气体二氧化碳捕集和封存及脱硫的一体化技术路线。
 发明内容
 针对现有二氧化碳和硫化氢的物理吸收法的不足，如低温甲醇洗工艺工作温度低、操作压力高、再生热量消耗大、冷量消耗大、溶液循环量大的高耗能缺点，低温甲醇洗工艺同上游气化和变换工段存在较大温度差，造成大量的能源消耗和浪费，本发明目的在于提供一种全程无需低温制冷的同源三碱，即硫化碱、纯碱和烧碱洗涤吸收二氧化碳、硫化氢和二氧化硫等酸性气及金属离子的工艺方法。本方法同源三碱的意思是三种碱均来源于硫化钠的生产，
通过硫化钠吸收二氧化碳，氢氧化钠吸收硫化氢，碳酸钠苛化法制烧碱，三碱实现联动循环。设计一种能源气体二氧化碳捕集和封存及脱硫的一体化技术路线，能够连续化大量生产硫化钠，大幅降低生产成本，利用硫化钠吸收二氧化碳来净化合成气和天然气。
 本发明是这样实现的：
一种含有可燃烧气体的混合气的脱碳脱硫方法，包括如下步骤：
（1）配制脱碳塔吸收液：在脱碳塔顶缓冲罐中补入Na 2S、去离子水，形成脱碳塔吸收液；
（2）脱碳塔吸收液洗涤原料混合气：将步骤（1）脱碳塔顶缓冲罐中的吸收液注入脱碳塔顶部,从脱碳塔底部通入含二氧化碳的原料混合气，在脱碳塔中部补充低温去离子水,脱碳塔顶部排出气进入硫化氢分离单元，脱碳塔底部产物进入脱碳塔底缓冲罐，脱碳塔底缓冲罐浓固相浆液排出至NaHCO 3溶液静置结晶及液固分离单元，脱碳塔底缓冲罐排出稀液进入步骤（1）的脱碳塔顶缓冲罐，补充脱碳塔吸收液；吸收液中硫离子被二氧化碳置换成硫氢根或硫氢酸，同时生成碳酸根或碳酸氢根离子，硫氢酸经加热从溶液中析出成为硫化氢进入排出气；
（3）脱碳气初脱硫：步骤（2）脱碳塔顶部排出含硫化氢气体进入硫化氢分离单元，硫化氢分离单元使用膜分离或变压吸附分离方法将脱碳塔排出气中大部分硫化氢分离，形成脱碳富硫气和/或脱碳贫硫气； 
（4）脱碳富硫气处理：将含H 2S浓度高的脱碳富硫气送入硫化氢处理单元制备硫磺或硫酸；
（5）脱碳贫硫气洗涤：将含H 2S浓度低的脱碳贫硫气送入贫硫气氢氧化钠洗涤塔，塔顶排出气为脱碳脱硫净化气；塔底溶液一部分循环进入塔顶缓冲罐，另一部分送入步骤（1）的脱碳塔顶缓冲罐，补充脱碳塔吸收液；
（6）吸收二氧化碳后的固液混合物处置：步骤（2）中脱碳塔底缓冲罐排出的浓固相浆液进入NaHCO 3溶液静置结晶及液固分离单元，分离出的固体物料送入NaHCO 3干燥设备；分离后的母液送入步骤（1）的脱碳塔顶缓冲罐，补充脱碳塔吸收液；
（7）NaHCO 3热分解：步骤（6）产出的NaHCO 3固体物料干燥后可做产品输出，部分碳酸氢钠经加热分解后产出碳酸钠产品，分解产出的混合气经冷凝冷却后，将气相送入步骤（2）中与原料混合气一同进行脱碳；
（8）苛法制烧碱；苛化反应器中补入去离子水和氧化钙，步骤（7）产出的Na 2CO 3作为苛法制烧碱的原料投入苛化反应器的溶液中；沉淀出的碳酸钙经分离得到碳酸钙固体，碳酸钙固体送入步骤（9）作为煅烧碳酸钙原料，生成的NaOH溶液送入步骤（5）贫硫气氢氧化钠洗涤塔顶缓冲罐；
（9）煅烧碳酸钙：将步骤（8）产生的碳酸钙进行煅烧，煅烧后的气相产物经回收热量后送入步骤（2）中与原料混合气一同进行脱碳；煅烧后的固相产物氧化钙作为原料送入步骤（8）苛法制烧碱流程。
 优选地，步骤（1）配制的吸收液温度为30-90℃，每100g水中硫化钠含量为0-0.735mol，去离子水温度低于吸收液温度；
优选地，步骤（2）Na 2S溶液的加入量和原料混合气的通入量根据溶液PH值调整，随着混合气和硫化钠溶液的反应，吸收液吸收二氧化碳后的PH值逐渐降低：硫化钠吸收微量二氧化碳后生成硫氢化钠和碳酸钠，析出硫化氢较少；溶液继续吸收二氧化碳，当溶液中硫离子接近消耗完时开始大量析出硫化氢，当PH开始小于9.4时，该溶液不再解析出硫化氢，同时开始产出碳酸氢根离子；溶液继续吸收二氧化碳，当PH开始小于8.3时，该溶液不再具有吸收二氧化碳的能力；富硫化氢气体经管道送往步骤（4）进行脱碳富硫气的处理，贫硫化氢气体经管道送往步骤（5）进行脱碳贫硫气的处理。
 优选地，步骤（2）根据原料气二氧化碳浓度和进料量，为及时排出溶液中的碳酸钠或碳酸氢钠固体，设置多塔串联连接方式进行多级脱碳洗涤；各级脱碳洗涤塔吸收液组分中的硫化钠含量、硫氢化钠含量、碳酸钠含量侧重不同，吸收液的PH值不同，排出气中硫化氢增量也不同；步骤（5）根据硫化氢脱除效果不同，设置多塔串联连接方式进行多级脱硫洗涤，各
级氢氧化钠溶液浓度和循环量不同。
 优选地，脱碳塔具备强耐酸碱能力，是带混合搅拌装置的塔式容器或带液固相混合出料
的吸收塔器，可以进行气液固三相反应，具备避免碳酸氢钠晶核增长和避免固相物料静置沉淀的调节手段。
 优选地，步骤（4）硫化氢处理单元设置硫磺回收装置和/或硫酸装置和/或硫化氢电解装置。
 优选地，生产过程中的每一个步骤产出的物料与需要投入的物料实现物料耦合，生产过程中的反应热与需要加热的反应过程实现热量耦合。
 本发明在硫化钠生产效率大幅提高、成本大幅下降，原料来源广泛的前提下，利用硫化钠溶解度大且能高效化学吸收二氧化碳，通过耦合膜分离和变压吸附技术分离硫化氢，叠加氢氧化钠洗涤吸收精制净化气、结合煅烧碳酸钙和苛化法制烧碱、并利用硫化钠吸收二氧化
碳得到的碳酸氢钠分解获得苛化法制烧碱的纯碱原料，实现了工艺的物料完整循环。本发明利用的化学原理是，根据电离常数不同，二氧化碳和硫化氢及其氢根离子的酸性关系如下：    
H 2CO 3>H 2S>HCO 3 ->HS -
因此过量硫化钠与少量二氧化碳反应为：
2Na 2S+CO 2+H 2O=2NaHS+Na 2CO 3
继续通入二氧化碳，硫氢化钠和二氧化碳反应如下：
2NaHS+CO 2+H 2O=2H 2S+Na 2CO 3
生成的碳酸钠也会与二氧化碳继续发生反应：
Na 2CO 3+CO 2+H 2O=2NaHCO 3
氢氧化钠和硫化氢的吸收反应如下：
NaOH+H 2S=NaHS+H 2O
NaHS+H 2S=Na 2S+H 2O
100克水中硫化钠，碳酸钠和碳酸氢钠的摩尔溶解度见下表：
因碳酸氢钠热稳定性差，在60℃以上时，碳酸氢钠分解为碳酸钠和二氧化碳的速度，大于碳酸钠吸收二氧化碳和水生成碳酸氢钠的速度，因此碳酸钠洗涤二氧化碳的操作温度应低于60℃。
 100克水对应的饱和碳酸钠溶解度在0.43-0.46摩尔，碳酸氢钠溶解度在0.2摩尔以下，由于1摩尔碳酸钠可产出2摩尔碳酸氢钠，同时消耗1摩尔溶剂水，因此饱和碳酸钠吸收二氧化碳会析出约70%的碳酸氢钠结晶固体，为防止碳酸氢钠析出后在设备及管线中沉积堵塞，可根据固含量和析出量设置多级碳酸钠洗涤吸收二氧化碳的流程，中间增设沉淀罐将碳酸氢钠浆液及时排出。
 硫化钠在水中溶解度随温度升高而增大，在60℃时，100克水对应的饱和硫化钠溶解度为0.398摩尔，碳酸钠溶解度为0.438摩尔，由于1摩尔碳酸钠可产出1摩尔碳酸氢钠，同时消耗1摩尔溶剂水，因此饱和碳酸钠吸收二氧化碳会析出少量碳酸钠结晶固体，为防止碳酸钠析出后在设备及管线中沉积堵塞，可补入低温溶剂水降低溶液温度，同时也可提高硫化钠
的初始操作温度在60℃以上进行。为此可设置多级硫化钠不同温度洗涤吸收二氧化碳的流程
设置，分别形成不同温度下不同硫化钠浓度吸收二氧化碳的流程，可通过控制反应进行程度减少碳酸钠析出。其反应过程可根据PH进行监测，各级脱碳洗涤塔吸收液组分中的硫化钠含量、硫氢化钠含量、碳酸钠含量不同，吸收液的PH值不同，其排出气中硫化氢增量也不同。
 本发明操作温度高，对操作压力无要求，可将上游变换装置所产的变换气的热量和压力能进行透平做功利用，降低本方法设备的设备材料压力等级。液相操作温度可保持在0-100℃进行，硫酸钠还原、碳酸氢钠分解、煅烧石灰石艺可以耦合变换装置和硫酸及硫磺装置的高温热源，不需配备制冷工艺及设备。本发明不需溶剂再生流程，碳酸氢钠热分解生产碳酸钠单元根据氢氧化钠洗涤硫化氢的需求量进行分解，其用量取决于硫化氢分离单元硫化氢的脱除效率。本发明不需要溶液的大量循环，碳酸氢钠分离出的母液，可视产物混合物的流动性和排出情况选择蒸发或者母液再利用；本发明操作压力对化学吸收二氧化碳过程的影响不大，为保持气相压力能的利用，应参考硫化氢分离单元的压力需求设置硫化钠吸收二氧化碳的操作压力，或者增设鼓风机将脱碳气输送至硫化氢处理单元。本方法不涉及低温甲醇洗脱碳工艺中的闪蒸解吸二氧化碳的操作，压力能损耗少。本发明相对溶剂物理吸收法，无需设置闪蒸脱碳、硫化氢浓缩、溶剂再生、溶剂精馏等过程，相应的塔、换热器、罐、机泵等管线和设备减少投资成本低。本发明为化学吸收过程，过程和操作简单，二氧化碳和硫化氢脱除效率高；本发明的反应过程在水溶液中，氢气和烃类的溶解度极小，不会造成有效合成气中氢气和烃类的减损。本发明的溶剂为硫化钠、碳酸钠、氢氧化钠等水溶液，均不是易燃易爆化学品，设备管线泄漏液体不会导致火灾爆炸事故，且以上三种物质的毒性较甲醇和有机胺小，将二氧化碳以碳酸根离子除去，实现了二氧化碳捕集和封存一步化和装置的一体化；本发明硫化钠的来源可由氢气还原硫酸钠获得，氢气可由电解制氢提供，电能可来源于风力和太阳能发电，本方法可实现零碳零污染的净化混合气，在净化混合气中二氧化碳的同时，能够副产碳酸氢钠、碳酸钠、硫磺和硫酸产品，进而也可以将硫化钠原料由硫酸钠扩展到氯化钠，并获得盐酸，本发明可为工业领域副产硫酸钠和氯化钠提供应用出路。
 附图说明
 下面结合附图和具体实施方式对本发明做进一步的阐述。
 图 1 本发明实施例1的物料投入产出示意图。
 图 2 本发明实施例2的物料投入产出示意图。
 图 3 本发明实施例1的工艺流程示意图。
 图 4 本发明实施例2的工艺流程示意图。
 实施方式
 为了使本发明的内容更加便于理解，下面将结合本发明实施例，将具体实施步骤和工艺流程叙述进行清楚完整地描述，本发明实施例是对发明中所述的一种利用硫化钠溶液吸收二氧化碳的混合气脱碳脱硫工艺的进一步阐述，而并非限制。显然，所述的实施例是本发明一部分实施例，而不是全部的实施例，基于本发明中的实施例，本领域普通技术人员，在没有做出创造性劳动的前提下所获得的所有其它实施例，都属于本发明保护的范围，例如使用本发明用于各类合成气下游甲醇、氨、乙二醇、烯烃及其他各类化工品的生产。
 以下为本发明的具体实施例：
实施例
如图1和图3所示，以外供硫化钠为溶质原料，所产硫化氢全部作为产品输出，原料混合气是自气化炉所产粗合成气经变换后的合成气，其体积组成为氢气47.4%，一氧化碳20.8%，二氧化碳31%，硫化氢0.3%，氮气0.2%，甲烷0.1%，其他0.2%。
 具体操作时，步骤如下：
（1）配制脱碳塔吸收液：脱碳塔又称二氧化碳吸收塔/反应器，是强化了的传质设备，我们首先在脱碳塔顶缓冲罐中补入Na 2S固体溶质、去离子水；当工艺系统进入正常循环后，富Na 2S溶液可以从NaOH吸收H 2S的产物中获得，即步骤（2）脱碳塔底缓冲罐排出的稀液和步骤（5）贫硫气洗涤塔送入的含硫化钠溶液，形成脱碳塔吸收液；当工艺系统进入正常循环后，还可以补入NaHCO 3溶液静置及液固分离设备排出的母液上清液。Na 2S溶液配制温度接近原料混合气的温度，通过与其它放热工艺单元流程进行耦合，使得原料混合气和Na 2S溶液控制在较高温度，控制在80-90℃；Na 2S溶液配制浓度按照100克溶剂水中Na 2S的质量不大于该温度下饱和溶液溶解度的0.77倍。随着二氧化碳的通入，溶剂水会不断消耗，为避免硫化钠的析出，不宜制备成饱和或者过饱和溶液，溶液浓度可根据原料混合气中水的含量，以及硫化钠吸收二氧化碳流程中的补水情况调整。
 我们采用的Na2S原料的杂质不能影响Na2S对CO2的吸收和沉淀，也不能影响H2S的解吸。原料Na2S除Na2S和水外，其余组成含量小于1%。硫化钠杂质不含有机烃类物质。
 (2)脱碳塔吸收液洗涤原料混合气 ：将步骤（1）脱碳塔顶缓冲罐中的吸收液注入脱碳塔顶部,从脱碳塔底部通入含二氧化碳原料混合气，在脱碳塔中部补充低温去离子水,脱碳塔顶部排出气进入步骤（3）硫化氢分离单元，脱碳塔底部产物进入脱碳塔底缓冲罐，脱碳塔底缓冲罐浓固相浆液排出至NaHCO 3溶液静置结晶及液固分离单元，脱碳塔底缓冲罐排出稀液进入步骤（1）的脱碳塔顶缓冲罐，补充脱碳塔吸收液；吸收液中硫离子被二氧化碳置换成硫氢根或硫氢酸，同时生成碳酸根或碳酸氢根离子，硫氢酸经加热从溶液中析出成为硫化氢进入排出气。
 脱碳塔如带搅拌装置的容器或者带液固相混合出料的吸收塔器，且耐酸碱能力强。进行气液固三相反应，脱碳塔应具备避免碳酸氢钠晶核增长和避免固相物料静置沉淀的调节手段，防止碳酸钠和碳酸氢钠因溶解度较低在设备内集聚导致液固混合物不易排出到下游设备。   
Na 2S溶液的加入量和原料混合气的通入量根据溶液PH来调整：随着原料混合气和硫化钠溶液的反应，溶液的PH逐渐降低，当PH开始小于9.4时，该溶液硫化钠基本被耗完并且不再解吸出硫化氢，同时溶液开始产出碳酸氢根离子；当PH开始小于8.3时，碳酸根离子基本被耗完并且溶液不再具有吸收二氧化碳的能力；进入到碳酸氢钠溶液静置及液固分离设备的溶液PH值大于8.3，优选控制值为8.4，防止脱碳气中二氧化碳含量过高，加重后续氢氧化钠洗涤吸收硫化氢的负荷。
 （3）脱碳气初脱硫：步骤（2）脱碳塔顶部排出含硫化氢气体进入硫化氢分离单元，硫化氢分离单元使用膜分离或变压吸附分离方法将脱碳塔排出气中大部分硫化氢分离，形成脱碳富硫气和脱碳贫硫气；经硫化钠吸收二氧化碳后的脱碳气富含硫化氢气体，进入硫化氢分离装置处理，硫化氢分离装置至少产出富硫化氢和贫硫化氢两种气体，富硫化氢气体经管道送往硫化氢处理装置，贫硫化氢气体经管道送往氢氧化钠吸收硫化氢装置处理。将硫化氢分离装置配置为膜分离或变压吸附分离工艺，充分利用原料混合气的压力能。脱碳贫硫化氢气体进入氢氧化钠溶液洗涤吸收二氧化碳装置，并排出脱碳脱硫净化气，氢氧化钠溶液由苛法制烧碱流程产出的氢氧化钠提供。
 (4)脱碳富硫气处理：将含H 2S浓度高的脱碳富硫气送入硫化氢处理装置制备硫磺或硫酸。
 硫化氢处理单元设置硫磺回收装置和/或硫酸装置和/或硫化氢电解装置。
 (5)脱碳贫硫气洗涤：将含H 2S浓度低的脱碳贫硫气送入贫硫气洗涤塔，塔顶排出气为脱碳脱硫净化气；将步骤（7）和（8）制备的NaOH溶液送入贫硫气洗涤塔顶缓冲罐；贫硫气洗涤塔塔底溶液一部分循环进入贫硫气洗涤塔顶缓冲罐，另一部分送入步骤（1）的脱碳塔顶缓冲罐补充脱碳塔吸收液。
 (6)吸收二氧化碳后的固液混合物处置：步骤（2）中脱碳塔底缓冲罐排出的浓固相浆液进入NaHCO 3溶液静置结晶及液固分离装置，分离出的固体物料送入NaHCO 3干燥设备；分离后
的母液送入步骤（1）的脱碳塔顶缓冲罐，补充脱碳塔吸收液。
 （7）NaHCO 3热分解：步骤（6）产出的NaHCO 3固体物料干燥后可做产品输出，部分碳酸氢钠经加热分解后产出碳酸钠产品，分解产出的混合气经冷凝冷却后，将气相送入步骤（2）中与原料混合气一同进行脱碳。
 （8）苛法制烧碱；苛化反应器中补入去离子水和氧化钙，步骤（7）产出的Na 2CO 3作为苛法制烧碱的原料投入苛化反应器的溶液中；沉淀出的碳酸钙经分离得到碳酸钙固体，碳酸钙送入步骤（9）作为煅烧碳酸钙原料，生成的NaOH溶液送入步骤（5）贫硫气氢氧化钠洗涤塔顶缓冲罐。
 （9）将步骤（8）产生的碳酸钙进行煅烧，煅烧后的气相产物经回收热量后送入步骤（2）中与原料混合气一同进行脱碳；煅烧后的固相产物氧化钙作为原料送入步骤（8）苛法制烧碱流程。
 实施例2
如图2和图4所示，以自产硫化钠作为吸收二氧化碳溶质原料，所产硫化氢经硫化氢处理单元加工成硫酸，硫酸和氯化钠制备可得到硫酸钠和盐酸，制得的硫酸钠被用于硫化钠的生产。原料混合气是自气化炉所产粗合成气经变换后的合成气，其体积组成为氢气47.4%，一氧化碳20.8%，二氧化碳31%，硫化氢0.3%，氮气0.2%，甲烷0.1%，其他0.2%。生产硫化钠的还原性气体由清洁能源发电制氢提供，本实施例的目的是通过绿色补氢降碳，实现煤化工零碳排放。
 具体操作时，步骤如下：
（1）配制脱碳塔吸收液：脱碳塔又称二氧化碳吸收塔/反应器，是强化了的传质设备，我们首先在脱碳塔顶缓冲罐中补入Na 2S固体溶质、去离子水；当工艺系统进入正常循环后，富Na 2S溶液可以从NaOH吸收H 2S的产物中获得，即步骤（2）脱碳塔底缓冲罐排出的稀液和步骤（5）贫硫气洗涤塔送入的含硫化钠溶液，形成脱碳塔吸收液；当工艺系统进入正常循环后，还可以补入NaHCO 3溶液静置及液固分离设备排出的母液上清液。Na 2S溶液配制温度接近原料混合气的温度，通过与其它放热工艺单元流程进行耦合，使得原料混合气和Na 2S溶液控制在较高温度，控制在80-90℃；Na 2S溶液配制浓度按照100克溶剂水中Na 2S的质量不大于该温度下饱和溶液溶解度的0.77倍。随着二氧化碳的通入，溶剂水会不断消耗，为避免硫化钠的析出，不宜制备成饱和或者过饱和溶液，溶液浓度可根据原料混合气中水的含量，以及硫化钠吸收二氧化碳流程中的补水情况调整。
 我们采用的Na2S原料的杂质不能影响Na2S对CO2的吸收和沉淀，也不能影响H2S的解吸。原料Na2S除Na2S和水外，其余组成含量小于1%。硫化钠杂质不含有机烃类物质。
 (2)脱碳塔吸收液洗涤原料混合气 ：将步骤（1）脱碳塔顶缓冲罐中的吸收液注入脱碳塔顶部,从脱碳塔底部通入含二氧化碳原料混合气，在脱碳塔中部补充低温去离子水,脱碳塔顶部排出气进入步骤（3）硫化氢分离单元，脱碳塔底部产物进入脱碳塔底缓冲罐，脱碳塔底缓冲罐浓固相浆液排出至NaHCO 3溶液静置结晶及液固分离单元，脱碳塔底缓冲罐排出稀液进入步骤（1）的脱碳塔顶缓冲罐，补充脱碳塔吸收液；吸收液中硫离子被二氧化碳置换成硫氢根或硫氢酸，同时生成碳酸根或碳酸氢根离子，硫氢酸经加热从溶液中析出成为硫化氢进入排出气。
 脱碳塔如带搅拌装置的容器或者带液固相混合出料的吸收塔器，且耐酸碱能力强。进行气液固三相反应，脱碳塔应具备避免碳酸氢钠晶核增长和避免固相物料静置沉淀的调节手段，防止碳酸钠和碳酸氢钠因溶解度较低在设备内集聚导致液固混合物不易排出到下游设备。
  
Na 2S溶液的加入量和原料混合气的通入量根据溶液PH来调整：随着原料混合气和硫化钠溶液的反应，溶液的PH逐渐降低，当PH开始小于9.4时，该溶液硫化钠基本被耗完并且
不再解吸出硫化氢，同时溶液开始产出碳酸氢根离子；当PH开始小于8.3时，碳酸根离子基
本被耗完并且溶液不再具有吸收二氧化碳的能力；进入到碳酸氢钠溶液静置及液固分离设备
的溶液PH值大于8.3，优选控制值为8.4，防止脱碳气中二氧化碳含量过高，加重后续氢氧化钠洗涤吸收硫化氢的负荷。
 （3）脱碳气初脱硫：步骤（2）脱碳塔顶部排出含硫化氢气体进入硫化氢分离单元，硫化氢分离单元使用膜分离或变压吸附分离方法将脱碳塔排出气中大部分硫化氢分离，形成脱碳富硫气和脱碳贫硫气；经硫化钠吸收二氧化碳后的脱碳气富含硫化氢气体，进入硫化氢分离装置处理，硫化氢分离装置至少产出富硫化氢和贫硫化氢两种气体，富硫化氢气体经管道送往硫化氢处理装置，贫硫化氢气体经管道送往氢氧化钠吸收硫化氢装置处理。将硫化氢分离装置配置为膜分离或变压吸附分离工艺，充分利用原料混合气的压力能。脱碳贫硫化氢气体进入氢氧化钠溶液洗涤吸收二氧化碳装置，并排出脱碳脱硫净化气，氢氧化钠溶液由苛法制烧碱流程产出的氢氧化钠提供。
 (4)脱碳富硫气处理：将含H 2S浓度高的脱碳富硫气送入硫化氢处理装置制备硫磺或硫酸。硫化氢处理单元设置硫磺回收装置和/或硫酸装置和/或硫化氢电解装置。
 (5)脱碳贫硫气洗涤：将含H 2S浓度低的脱碳贫硫气送入贫硫气洗涤塔，塔顶排出气为脱碳脱硫净化气；将步骤（7）和（8）制备的NaOH溶液送入贫硫气洗涤塔顶缓冲罐；贫硫气洗涤塔塔底溶液一部分循环进入贫硫气洗涤塔顶缓冲罐，另一部分送入步骤（1）的脱碳塔顶缓冲罐补充脱碳塔吸收液。根据硫化氢脱除效果不同，本实施例设置多塔串联连接方式进行多级脱硫洗涤，各级氢氧化钠溶液浓度和循环量不同。如氢氧化钠浓度按30%，20%，10%设置三级碱洗流程。
 (6)吸收二氧化碳后的固液混合物处置：步骤（2）中脱碳塔底缓冲罐排出的浓固相浆液进入NaHCO 3溶液静置结晶及液固分离装置，分离出的固体物料送入NaHCO 3干燥设备；分离后的母液送入步骤（1）的脱碳塔顶缓冲罐，补充脱碳塔吸收液。
 （7）NaHCO 3热分解：步骤（6）产出的NaHCO 3固体物料干燥后可做产品输出，部分碳酸氢钠经加热分解后产出碳酸钠产品，分解产出的混合气经冷凝冷却后，将气相送入步骤（2）中与原料混合气一同进行脱碳。
 （8）苛法制烧碱；苛化反应器中补入去离子水和氧化钙，步骤（7）产出的Na 2CO 3作为苛法制烧碱的原料投入苛化反应器的溶液中；沉淀出的碳酸钙经分离得到碳酸钙固体，碳酸钙送入步骤（9）作为煅烧碳酸钙原料，生成的NaOH溶液送入步骤（5）贫硫气氢氧化钠洗涤塔顶缓冲罐。
 （9）将步骤（8）产生的碳酸钙进行煅烧，煅烧后的气相产物经回收热量后送入步骤（2）中与原料混合气一同进行脱碳；煅烧后的固相产物氧化钙作为原料送入步骤（8）苛法制烧碱流程。
 本发明用硫化钠溶液化学吸收二氧化碳，生成碳酸钠可继续吸收二氧化碳，生成碳酸氢钠离子及沉淀；混合气经吸收后形成含硫化氢脱碳气体，经膜分离或者变压吸附工艺将脱碳气分离成脱碳富硫气和脱碳贫硫气；富硫气经硫磺装置或者硫酸装置生成硫磺或硫酸，贫硫脱碳气经氢氧化钠吸收硫化氢后产出脱碳脱硫净化气；硫化钠吸收二氧化碳所产碳酸氢钠经热分解生成纯碱，纯碱与氧化钙经苛化法制得烧碱，可满足氢氧化钠洗涤硫化氢用烧碱需求，苛化法所产碳酸钙经煅烧重新得到氧化钙用于循环制烧碱。进一步，硫酸装置所产硫酸可与氯化钠反应得到硫酸钠和盐酸，硫酸钠可与净化气反应得到硫化钠，实现硫化钠的循环补充。 
 本发明可净化处理的原料混合气，对其二氧化碳和硫化氢浓度无上下限要求，所述工艺步骤包括：Na 2S溶液配制、Na 2S溶液吸收CO 2、H 2S分离、H 2S处理、NaHCO 3液固分离、
NaHCO 3干燥及热分解、苛法制烧碱、煅烧碳酸钙、氢氧化钠吸收H 2S共9个工艺步骤组成；其特征在于：被处理的原料气中含有H 2、CO、CH 4、N 2、H 2S、SO 2、H 2O、稀有气体、烃类
及衍生物气体或其它有机可燃气中的至少一种；例如原料混合气可以是由煤、渣油或生物质
气化经变换后的合成气、甲烷重整气、煤层气、页岩气、气田采出天然气等气体。
 Na 2S溶液吸收二氧化碳设备内主要发生如下化学反应：二氧化碳与Na 2S溶液反应生成碳酸根离子，碳酸根离子可进一步与二氧化碳反应生成碳酸氢根离子，二氧化碳与Na 2S溶液反应生成硫氢根，并能以硫化氢气体形式离开溶液，其特征在于净化后的脱碳气富含硫化氢需进入硫化氢分离单元处理；Na 2S溶液的加入量和原料混合气的通入量根据溶液PH来调整：随着原料混合气和硫化钠溶液的反应，溶液的PH逐渐降低，当PH开始小于9.4时，该溶液硫化钠基本被耗完并且不再解吸出硫化氢，同时溶液开始产出碳酸氢根离子；当PH开始小于8.3时，碳酸根离子基本被耗完并且溶液不再具有吸收二氧化碳的能力。
 Na 2S溶液吸收CO 2设备排出的液固混合物进入到NaHCO 3溶液静置分离设备，固液混合物静置分离后，母液排出至硫化钠溶液配制设备作为部分溶液，固相排出至碳酸氢钠固体干燥设备。干燥碳酸氢钠设备的热源可以利用碳酸钙煅烧和碳酸氢钠热分解产生的高温气体，干燥出的气体冷凝后可补入Na 2S溶液配制流程补充溶剂水，高温二氧化碳气体热源经干燥碳酸氢钠固体利用热能后可送入硫化钠溶液吸收二氧化碳单元。
 Na 2S溶液吸收CO 2设备排出的脱碳气进入到硫化氢分离单元，硫化氢分离单元至少产出富硫化氢和贫硫化氢两种气体，富硫化氢气体经管道送往硫化氢处理单元，贫硫化氢气体经管道送往氢氧化钠吸收硫化氢单元处理；其优选特征在于：可充分利用原料混合气的压力能，将硫化氢分离单元配制为膜分离或变压吸附分离工艺。脱碳贫硫化氢气体进入氢氧化钠溶液洗涤吸收二氧化碳单元，并排出脱碳脱硫净化气，氢氧化钠溶液由苛法制烧碱流程产出的氢氧化钠供入。
 苛法制烧碱流程的碳酸钠由碳酸氢钠分解产出的碳酸钠提供，苛法制烧碱流程所产碳酸钙沉淀送入碳酸钙煅烧流程，煅烧碳酸钙所产氧化钙送入苛法制烧碱流程生产氢氧化钠，煅烧碳酸钙所产二氧化碳回收热量后送入硫化钠吸收二氧化碳流程。
 硫化钠可由上游工段提供，也可外购。如上游可配制还原硫酸钠生产硫化钠装置，也可由氢氧化钠吸收硫化氢获得。还原硫酸钠生产硫化钠单元生产硫化钠的同时，还可产出工艺水和尾气洗涤碳酸钠及碳酸氢钠物料，这些物料以及废热可与本方法进行物料和热量的耦合，本方法保留硫化钠生产和硫化钠吸收二氧化碳及氢氧化钠吸收二氧化碳及硫化氢单元之间的任何物料与热量耦合而产生工艺变化的权力，而且任何简单的变化都不会导致本方法创新性和新颖性的根本变化。
 脱硫脱碳后的净化气也可用于还原硫酸钠生产硫化钠，从而实现由硫元素的循环完成硫化钠溶质的自给自足，可将硫化氢处理单元配制为硫磺回收装置、硫酸装置或者硫化氢电解装置及以上装置的组合；进一步的，硫化氢处理单元可使用氯化钠和浓硫酸为原料，将硫化钠转化为硫酸钠，同时生产出盐酸产品，硫酸钠产品可用于生产硫化钠的原料，脱碳脱硫净化气用于硫酸钠的还原气。
 在本发明的生产过程中的每一个步骤产出的物料与需要投入的物料实现物料耦合，生产过程中的反应热与需要加热的反应过程实现热量耦合。
 本发明在主体工艺流程搭配上，按下面设备顺序连接构建工艺流程：工艺中进入Na 2S溶液配制设备的管线包括补充Na 2S管道、补充去离子水管道、由氢氧化钠吸收H 2S设备返入的Na 2S溶液管道、NaHCO 3溶液液固分离设备的清液排出物料管道及其辅助管线；Na 2S溶液配制设备的液体排出管线与Na 2S溶液吸收CO 2设备连接；Na 2S溶液吸收CO 2设备的液固混合物排出物料管道与NaHCO 3溶液静置及液固分离设备连接；NaHCO 3溶液液固分离设备的固体排出物料管道与NaHCO 3干燥设备连接；NaHCO 3干燥设备的固体排出物料管道与NaHCO 3分解设备连接；NaHCO 3分解设备的气相排出管道与Na 2S溶液吸收CO 2设备连接；NaHCO 3溶液静置分离设备的母液排出管道与Na 2S溶液配制设备连接；Na 2S吸收原料混合气设备的原料混合气进气管道的物料是原料混合气；Na 2S吸收原料混合气设备的排气管道的物料是脱碳净化气；Na 2S溶液吸收CO 2设备的排气管道与H 2S分离单元连接；H 2S分离单元分离出的H 2S浓度高的脱碳富硫气经管道与H 2S处理单元H 2S原料入口管线连接；H 2S分离单元分离出的H 2S浓度低的脱碳贫硫气物料管道与氢氧化钠吸收H 2S的气相入口管道连接；NaHCO 3热分解设备的排出的固相是Na 2CO 3纯碱产品，Na 2CO 3纯碱产品可送入苛法制烧碱设备；苛法制烧碱流程产出的氢氧化钠溶液经管道与氢氧化钠洗涤脱碳贫硫气的液相入口连接；苛法制烧碱流程产出的碳酸钙固体送入碳酸钙煅烧设备；碳酸钙煅烧后得到的氧化钙可加入到苛法制烧碱设备；碳酸钙煅烧产出二氧化碳可送入Na 2S溶液吸收CO 2设备。

Claims (6)

  1. 一种含有可燃烧气体的混合气的脱碳脱硫方法，其特征在于，包括如下步骤：
    配制脱碳塔吸收液：在脱碳塔顶缓冲罐中补入Na 2S、去离子水，形成脱碳塔吸收液；吸收液温度为30-90℃，Na 2S溶液配制浓度按照100克溶剂水中Na 2S的质量不大于该温度下饱和溶液溶解度的0.77倍，去离子水温度低于吸收液温度；
    脱碳塔吸收液洗涤原料混合气：将步骤（1）脱碳塔顶缓冲罐中的吸收液注入脱碳塔顶部,从脱碳塔底部通入含二氧化碳的原料混合气，在脱碳塔中部补充低温去离子水,脱碳塔顶部排出气进入硫化氢分离单元，脱碳塔底部产物进入脱碳塔底缓冲罐，脱碳塔底缓冲罐浓固相浆液排出至NaHCO 3溶液静置结晶及液固分离单元，脱碳塔底缓冲罐排出稀液进入步骤（1）的脱碳塔顶缓冲罐，补充脱碳塔吸收液；吸收液中硫离子被二氧化碳置换成硫氢根或硫氢酸，同时生成碳酸根或碳酸氢根离子，硫氢酸经加热从溶液中析出成为硫化氢进入排出气；
    脱碳气初脱硫：步骤（2）脱碳塔顶部排出含硫化氢气体进入硫化氢分离单元，硫化氢分离单元使用膜分离或变压吸附分离方法将脱碳塔排出气中大部分硫化氢分离，形成脱碳富硫气和/或脱碳贫硫气；
    脱碳富硫气处理：将含H 2S浓度高的脱碳富硫气送入硫化氢处理单元制备硫磺或硫酸；
    脱碳贫硫气洗涤：将含H 2S浓度低的脱碳贫硫气送入贫硫气氢氧化钠洗涤塔，塔顶排出气为脱碳脱硫净化气；塔底溶液一部分循环进入塔顶缓冲罐，另一部分送入步骤（1）的脱碳塔顶缓冲罐，补充脱碳塔吸收液；
    吸收二氧化碳后的固液混合物处置：步骤（2）中脱碳塔底缓冲罐排出的浓固相浆液进入NaHCO 3溶液静置结晶及液固分离单元，分离出的固体物料送入NaHCO 3干燥设备；分离后的母液送入步骤（1）的脱碳塔顶缓冲罐，补充脱碳塔吸收液；
    NaHCO 3热分解：步骤（6）产出的NaHCO 3固体物料干燥后可做产品输出，部分碳酸氢钠经加热分解后产出碳酸钠产品，分解产出的混合气经冷凝冷却后，将气相送入步骤（2）中与原料混合气一同进行脱碳；
    苛法制烧碱；苛化反应器中补入去离子水和氧化钙，步骤（7）产出的Na 2CO 3作为苛法制烧碱的原料投入苛化反应器的溶液中；沉淀出的碳酸钙经分离得到碳酸钙固体，碳酸钙送入步骤（9）作为煅烧碳酸钙原料，生成的NaOH溶液送入步骤（5）贫硫气氢氧化钠洗涤塔顶缓冲罐；
    煅烧碳酸钙：将步骤（8）产生的碳酸钙进行煅烧，煅烧后的气相产物经回收热量后送入步骤（2）中与原料混合气一同进行脱碳；煅烧后的固相产物氧化钙作为原料送入步骤（8）苛法制烧碱流程。
  2. 根据权利要求1所述的含有可燃烧气体的混合气的脱碳脱硫方法，其特征在于：所述的步骤（2）Na 2S溶液的加入量和原料混合气的通入量根据溶液PH值调整，随着混合气和硫化钠溶液的反应，吸收液吸收二氧化碳后的PH值逐渐降低：硫化钠吸收微量二氧化碳后生成硫氢化钠和碳酸钠，同时也不析出硫化氢；溶液继续吸收二氧化碳，当溶液中硫离子接近消耗完时开始析出硫化氢，当PH开始小于9.4时，该溶液不再解析出硫化氢，同时开始产出碳酸氢根离子；溶液继续吸收二氧化碳，当PH开始小于8.3时，该溶液不再具有吸收二氧化碳的能力；富硫化氢气体经管道送往步骤（4）进行脱碳富硫气处理，贫硫化氢气体经管道送往步骤（5）进行脱碳贫硫气洗涤。
  3. 根据权利要求1或2所述的含有可燃烧气体的混合气的脱碳脱硫方法，其特征在于：所述的步骤（2）根据原料气二氧化碳浓度和进料量，为及时排出溶液中的碳酸钠或碳酸氢钠固体，设置多塔串联连接方式进行多级脱碳洗涤；各级脱碳洗涤塔吸收液组分中的硫化钠含量、硫氢化钠含量、碳酸钠含量侧重不同，吸收液的PH值不同，排出气中硫化氢增量也不同；步骤（5）根据硫化氢脱除效果不同，设置多塔串联连接方式进行多级脱
    硫洗涤，各级氢氧化钠溶液浓度和循环量不同。
  4. 根据权利要求1或2所述的含有可燃烧气体的混合气的脱碳脱硫方法，其特征在于：所述脱碳塔具备强耐酸碱能力，是带混合搅拌装置的塔式容器或带液固相混合出料的吸收塔器，可以进行气液固三相反应，具备避免碳酸氢钠晶核增长和避免固相物料静置沉淀的调节手段。
  5. 根据权利要求1或2所述的含有可燃烧气体的混合气的脱碳脱硫方法，其特征在于：所述的步骤（4）硫化氢处理单元设置硫磺回收装置和/或硫酸装置和/或硫化氢电解装置。
  6. 根据权利要求1或2所述的含有可燃烧气体的混合气的脱碳脱硫方法，其特征在于：所述的生产过程中的每一个步骤产出的物料与需要投入的物料实现物料耦合，生产过程中的反应热与需要加热的反应过程实现热量耦合。
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