Raw gas shift process applied to synthesis ammonia production

Abstract

The invention belongs to the technical field of raw gas conversion processes, and particularly relates to a raw gas conversion process applied to synthesis ammonia production. The raw gas conversion process has outstanding advantages, dust, tar and H2S in the raw gas are deeply removed through the synergistic effect of high-temperature electrostatic dust collection, ceramic membrane filtration and the pre-desulfurization tower, catalyst poisoning and carbon deposition are avoided from the source, and the service life of the raw gas conversion process is remarkably prolonged. An adiabatic and two-stage isothermal shift reactor is adopted, a waste heat boiler byproduct medium-low pressure steam is embedded between bed layers, high-temperature and low-temperature catalysts are matched, a reaction temperature interval is accurately matched, adiabatic temperature rise is avoided, steam consumption is reduced, efficient and deep conversion of CO is achieved, and effective gas loss is reduced. Meanwhile, steam stripping deamination and pervaporation membrane purification of condensate are carried out, near-zero discharge of wastewater is achieved, and ammonia and sulfur resources are recycled respectively; catalyst oxygen-enriched regeneration is combined with waste heat recovery to preheat desalted water, so that the energy consumption of the system is further reduced, and high efficiency, energy conservation and environmental protection are comprehensively considered.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of crude coal gas shift process, and particularly relates to a crude coal gas shift process applied to synthetic ammonia production. BACKGROUND

[0002] In synthetic ammonia production, crude coal gas shift is one of the key processes, and the core is to convert CO in the crude coal gas into H2 and CO2 under the action of a catalyst, while adjusting the hydrogen-carbon ratio to meet the needs of subsequent ammonia synthesis. The traditional shift process has the following outstanding problems: (1) the impurities (dust, tar, sulfides) in the inlet crude coal gas are not thoroughly treated, which easily leads to poisoning and deactivation of the subsequent catalyst; (2) the shift reaction is a strong exothermic reaction, and the temperature of the traditional adiabatic shift furnace rises greatly, which requires a large amount of steam to be injected for temperature control, resulting in large steam consumption and low energy efficiency of the system; (3) the condensate produced in the process contains high concentrations of ammonia, sulfides and other pollutants, which is difficult to treat and easily causes secondary environmental pollution; (4) the energy consumption of the catalyst regeneration and adsorbent regeneration processes is high, and the regeneration tail gas treatment is not perfect; (5) the system has a large amount of methane side reactions, and the methane content in the shift gas is high, which has a great impact on the subsequent system.

[0003] Although the prior art has some improvements, it mainly focuses on the optimization of a single link, lacks overall and integrated innovative design of the entire shift system in terms of energy efficiency coupling, pollution control and resource recovery, and it is difficult to simultaneously achieve efficient, energy-saving and environmentally-friendly long-period stable operation.

[0004] In view of the above problems, it is urgent to develop a green crude coal gas shift process that takes into account efficient shift, cascade utilization of waste heat, long service life of catalyst and water resource recycling. SUMMARY

[0005] The present application aims to solve the existing problems, and provides a crude coal gas shift process applied to synthetic ammonia production.

[0006] The present application is implemented by the following technical solutions:

[0007] A crude coal gas shift process applied to synthetic ammonia production, comprising the following steps:

[0008] S1, gasification crude coal gas is sequentially subjected to high-temperature electrostatic precipitation, ceramic membrane filtration and dust removal and oil removal, and then selectively removes H2S through a pre-desulfurization tower, and finally utilizes adiabatic plus two-stage isothermal reaction and shift gas waste heat to separate condensate;

[0009] S2, the detoxification and preheating of the crude coal gas is performed, the crude coal gas is introduced into an adiabatic furnace, high-temperature shift catalyst is used for high-temperature shift and by-product medium-pressure steam is produced; the first-stage shift gas is cooled to 230-260 DEG C and then introduced into a first-stage isothermal and second-stage isothermal shift furnace, low-temperature shift catalyst is used for low-temperature deep shift and by-product high-pressure and low-pressure steam is produced;

[0010] S3, cooling and separating the secondary conversion gas to condensate liquid, collecting all the condensate liquid, first stripping ammonia by steam, then removing H2S and organic matter by permeation vaporization membrane, and recycling the treated condensate water;

[0011] S4, finally, regenerating the adsorbent and the catalyst.

[0012] Further, the electric field strength in the high-temperature electrostatic precipitation in step S1 is controlled to be 3-5 kV / cm.

[0013] The ceramic membrane filtration has a membrane pore size of 0.1-0.2 μm and an operating pressure difference of 0.1-0.15 MPa.

[0014] The adsorbent used in the pre-desulfurization tower is mesoporous modified activated carbon loaded with ZnO-CuO, the operating temperature is 120-150 ℃, the operating pressure is 0.8-1.2 MPa, and the outlet H2S concentration is controlled to be lower than 0.3%.

[0015] The separation of the condensate liquid by using adiabatic plus secondary isothermal reaction and conversion gas waste heat is specifically as follows: the crude coal gas after pre-desulfurization is introduced into a gas-gas heat exchanger, and is preheated to 220-240 ℃ by using the conversion gas waste heat at the outlet of the secondary conversion furnace at 195-200 ℃, and at the same time, 30-40% of the condensate water in the crude coal gas is separated by a gas-liquid separator.

[0016] Further, the preparation of the adsorbent includes the following steps:

[0017] S101, mesoporous activated carbon is prepared by using KOH activation method with coconut shell activated carbon as raw material, the activation temperature is 800-850 ℃, the mass ratio of KOH to activated carbon is (3-4):1, the holding time is 2-3 h, and the mesoporous pore size is controlled to be 2-5 nm, and the specific surface area is controlled to be 800-1000 m 2 / g;

[0018] S102, an equal-volume impregnation method is used to load a mixed solution of Zn(NO3)2 and Cu(NO3)2, the molar ratio of Zn 2+ to Cu 2+ is 2:1, and the total metal ion concentration is 0.5-0.8 mol / L;

[0019] S103, drying at 120-150 ℃ for 4-6 h, and calcining at 350-400 ℃ for 3-4 h to obtain a ZnO-CuO / mesoporous activated carbon adsorbent with a loading amount of 8-12 wt%.

[0020] Further, the packing height of the high-temperature sulfur-tolerant conversion catalyst in step S2 is 3-4 m, and the space velocity is 800-1000 h -1, the reaction temperature is 280~350℃, the pressure is 5.8~6.2MPa, the CO content in the crude coal gas is reduced to 5~8%, the high-temperature shifted gas after reaction is sprayed with water to reduce the temperature, 15 tons of saturated steam per hour and 6.5MPa are produced as by-products, the production of by-product methane is reduced, and the methane concentration at the outlet of the control system is controlled to be below 2000ppm.

[0021] Further, the high-temperature sulfur-tolerant shift catalyst comprises: CoO 3~5wt%, MoO3 10~15wt%, CeO22~4wt%, La2O3 1~2wt%, ZrO2 1~3wt%, and the balance is mesoporous γ-Al2O3 carrier, the mesoporous pore size is 5~10nm, and the specific surface area is 200~300m 2 / g, and the preparation method comprises:

[0022] S301, using aluminum isopropoxide as an aluminum source and P123 as a template agent, hydrothermal reaction is carried out at 120~150℃ for 12~16h, and calcination is carried out at 550~600℃ for 6~8h to obtain mesoporous γ-Al2O3;

[0023] S302, Co(NO3)2, (NH4)6Mo7O 24 , Ce(NO3)3, La(NO3)3 and Zr(NO3)4 are dissolved in deionized water in proportion, ammonia water is used as a precipitant, the precipitation pH is controlled to be 8.5~9.5, and aging is carried out at 60~70℃ for 2~3h;

[0024] S303, the precursor is mixed with the mesoporous γ-Al2O3 carrier, washing, drying at 120~150℃ for 4~6h, calcination at 500~550℃ for 4~6h, tabletting (particle size 3~5mm) to obtain the high-temperature sulfur-tolerant shift catalyst.

[0025] Further, the packing height of the low-temperature sulfur-tolerant shift catalyst in step S2 is 2.5~3m, the space velocity is 1200~1500h -1 , the reaction temperature is 180~250℃, the pressure is 5.5~5.8MPa, and the low-pressure waste heat boiler is embedded between the catalyst beds to produce 0.8~1.2MPa saturated steam as by-products.

[0026] Further, the low-temperature sulfur-tolerant shift catalyst comprises: CoO 2~4wt%, MoO3 8~12wt%, Y2O3 1~3wt%, Nd2O3 0.5~1.5wt%, and the balance is a TiO2-γ-Al2O3@ZIF-67 composite carrier (ZIF-67 loading amount 10~15wt%, specific surface area 350~450m 2 / g), and the preparation method comprises:

[0027] (1) using tetrabutyl titanate and aluminum isopropoxide as raw materials, citric acid as a chelating agent, stirring at 80-90℃ for 4-6h to form a sol, drying at 120℃ for 6-8h, and calcining at 500℃ for 4-5h to obtain TiO2-γ-Al2O3 (mass ratio of TiO2 to γ-Al2O3 1:3);

[0028] (2) dispersing TiO2-γ-Al2O3 in a methanol solution, adding Co(NO3)2·6H2O and 2-methylimidazole (molar ratio 1:2), and reacting at room temperature for 24-36h, centrifuging, washing, and drying at 80℃ for 12h to obtain a composite carrier;

[0029] (3) using an equal volume impregnation method to load Co(NO3)2, (NH4)6Mo7O 24 , Y(NO3)3, and Nd(NO3)3 mixed solutions, drying at 120-150℃ for 4-6h, calcining at 450-500℃ for 3-5h, and tabletting (particle size 2-3mm) to obtain a low-temperature sulfur-tolerant shift catalyst.

[0030] Further, the steam stripping ammonia in step S3 is specifically: passing the collected condensate into a stripping tower, using 0.5MPa saturated steam for stripping, the operating temperature of the stripping tower is 120-130℃, the pressure is 0.55-0.6MPa, the volume ratio of steam to condensate is (3-5):1, and the NH3 content in the condensate after stripping is controlled to be ≤5ppm;

[0031] The H2S and organic matter are removed by a modified PDMS membrane, the operating temperature is 40-50℃, the operating pressure is 0.3-0.5MPa, and the H2S content in the treated condensate water is ≤0.1ppm;

[0032] The preparation method of the modified PDMS membrane is: dispersing graphene oxide (GO) in chloroform (concentration 0.5-1mg / mL) under ultrasonic, adding a vinyl-terminated polydimethylsiloxane (PDMS) prepolymer with a viscosity range of 5000-10000cP, a crosslinking agent (mass ratio 10:1), the crosslinking agent is methyltriacetoxysilane, and ZIF-8 nanoparticles (particle size 50-100nm, addition amount 5-10% of the mass of PDMS), stirring for 2-3h to form a uniform casting solution; coating the casting solution on a porous alumina support (coating thickness 50-80μm), and curing at 80-100℃ for 4-6h to obtain a PDMS-GO-ZIF-8 composite membrane, the H2S permeability coefficient of which is ≥1.5×10 -10 cm 3 ·cm / (cm 2 ·s·Pa), and the H2O / H2S separation factor is ≥200.

[0033] Further, the adsorbent in step S4 is regenerated by the low-pressure steam by-produced in step S2, the regeneration temperature is 160-180 DEG C, the regeneration time is 4-6h, and the regeneration tail gas (containing 5-8% H2S) is sent to a sulfur recovery device to produce sulfuric acid.

[0034] Further, in the catalyst regeneration in step S4, the mixed gas of oxygen-rich air and nitrogen (O2 content 25-30%) is used for oxidation regeneration, the regeneration temperature is 380-420 DEG C, the regeneration time is 8-12h, and the waste heat generated in the regeneration process is used to preheat the desalted water through a heat exchanger (preheated to 60-70 DEG C).

[0035] Compared with the prior art, the present application has the following advantages:

[0036] 1. In the present application, the gasification crude coal gas is sequentially subjected to high-temperature electrostatic dust removal, ceramic membrane filtration and oil removal, then selectively removes H2S through a pre-desulfurization tower, and finally uses the waste heat of the secondary shift gas to preheat and separate the condensate, through the combination of high-temperature electrostatic dust removal, ceramic membrane filtration and specific desulfurization process, the dust, tar and other impurities in the crude coal gas are removed, the toxic substances of the subsequent catalyst are eliminated from the source, the catalyst poisoning, carbon deposition and deactivation rate are significantly reduced, and the service life of the catalyst is prolonged.

[0037] 2. In the present application, an adiabatic plus two-stage isothermal shift reactor is used, and a waste heat boiler is directly embedded between the catalyst beds, the heat released by the strong exothermic reaction is removed in time and is used to produce medium-pressure steam and low-pressure steam respectively, high-temperature catalyst and low-temperature catalyst are used according to the different requirements of high-temperature shift and low-temperature shift, the high-temperature catalyst uses a mesoporous γ-Al2O3 carrier modified by multiple additives, the thermal stability and poison resistance are enhanced, the low-temperature catalyst uses a TiO2-γ-Al2O3 composite carrier modified by ZIF-67, the specific surface area and activity site dispersion are greatly enhanced, and rare earth additives are introduced, which exhibits extremely high activity and selectivity at low temperature, the bed temperature of the isothermal shift furnace is stable, the huge temperature rise of the adiabatic reactor is avoided, the steam consumption is reduced, the reaction is always carried out in the best activity temperature range of the catalyst, the CO conversion rate is higher, the reaction is more complete, and the loss of effective gas components is less.

[0038] 3. In the present application, the high-pollution condensate is subjected to combined purification by steam stripping and high-performance pervaporation membrane, the NH3 concentration is reduced, H2S and organic matter are efficiently removed, and the treated condensate water can be recycled to the system to realize near-zero wastewater discharge. The stripped ammonia can be recycled, the adsorbent regeneration tail gas is sent to a sulfur recovery device to produce sulfuric acid, waste is turned into treasure, the sulfur resource is recycled and utilized, the catalyst regeneration uses oxygen-rich regeneration technology, the energy consumption of inert gas heating is reduced, the regeneration time is short, and the waste heat generated in the regeneration process is effectively recycled to preheat the desalted water, and the overall energy consumption of the system is further reduced. DETAILED DESCRIPTION

[0039] In order to make further explanation of the present application, the following specific examples are described.

[0040] Example 1

[0041] A crude gas shift process applied to synthetic ammonia production, comprising the following steps:

[0042] S1, the gasification of crude gas is sequentially subjected to high-temperature electrostatic precipitation, ceramic membrane filtration, oil removal, and then selectively removes H2S through a pre-desulfurization tower, and finally uses adiabatic plus two-stage isothermal reaction and shift gas preheating and separates the condensate;

[0043] The electric field strength of the high-temperature electrostatic precipitation is controlled to be 3 kV / cm;

[0044] The membrane pore size of the ceramic membrane filtration is 0.1 μm, and the operating pressure difference is 0.1 MPa;

[0045] The adsorbent used in the pre-desulfurization tower is a mesoporous modified activated carbon loaded with ZnO-CuO, the operating temperature is 120℃, the operating pressure is 0.8 MPa, and the outlet H2S concentration is controlled to be less than 0.3%;

[0046] The preparation of the adsorbent comprises the following steps:

[0047] S101, mesoporous activated carbon is prepared by using coconut shell activated carbon as raw material and adopting KOH activation method, the activation temperature is 800℃, the mass ratio of KOH to activated carbon is 3:1, the holding time is 2h, and the mesoporous pore size is controlled to be 2nm, the specific surface area is 800m 2 / g;

[0048] S102, an equal volume impregnation method is used to load Zn(NO3)2 and Cu(NO3)2 mixed solution, the molar ratio of Zn 2+ to Cu 2+ is 2:1, and the total metal ion concentration is 0.5 mol / L;

[0049] S103, drying at 120℃ for 4h and calcining at 350℃ for 3h to obtain a ZnO-CuO / mesoporous activated carbon adsorbent with a loading amount of 8wt%;

[0050] The adiabatic plus two-stage isothermal reaction and shift gas waste heat and condensate separation are specifically as follows: the crude gas after pre-desulfurization is passed into a gas-gas heat exchanger, and the shift gas waste heat at the outlet of the two-stage shift furnace is used to preheat to 220℃, and at the same time, 30% of the condensate water in the crude gas is separated through a gas-liquid separator;

[0051] S2, the detoxification preheated raw coal gas is introduced into the adiabatic furnace, and high-temperature shift is carried out under the action of high-temperature sulfur-tolerant shift catalyst, the packing height of the high-temperature sulfur-tolerant shift catalyst is 3 m, the space velocity is 800 h -1 , the reaction temperature is 280 DEG C, the pressure is 5.8 MPa, the CO content in the raw coal gas is reduced to 5-8%, the high-temperature shift gas after reaction is sprayed with water to reduce the temperature, 15 tons of saturated steam with a pressure of 6.5 MPa are by-produced per hour, the production of by-reaction methane is reduced, and the methane concentration at the outlet of the control system is controlled to be below 2000 ppm;

[0052] The high-temperature sulfur-tolerant shift catalyst comprises the following components: CoO 3wt%, MoO3 10wt%, CeO2 2wt%, La2O31wt%, ZrO2 1wt%, and the balance is mesoporous γ-Al2O3 carrier, the mesoporous pore size is 5 nm, and the specific surface area is 200 m 2 / g, and the preparation method comprises the following steps:

[0053] S301, mesoporous γ-Al2O3 is obtained by using aluminum isopropoxide as an aluminum source, using P123 as a template agent, carrying out hydrothermal reaction at 120 DEG C for 12 h, and carrying out calcination at 550 DEG C for 6 h;

[0054] S302, Co(NO3)2, (NH4)6Mo7O 24 , Ce(NO3)3, La(NO3)3 and Zr(NO3)4 are dissolved in deionized water in proportion, ammonia water is used as a precipitant, the precipitation pH is controlled to be 8.5, and aging is carried out at 60 DEG C for 2 h;

[0055] S303, the precursor is mixed with the mesoporous γ-Al2O3 carrier, washing, drying at 120 DEG C for 4 h, calcination at 500 DEG C for 4 h, tabletting (particle size 3-5 mm) are carried out, and a high-temperature sulfur-tolerant shift catalyst is obtained;

[0056] After the primary shift gas is cooled to 230 DEG C, the primary shift gas enters a primary isothermal and secondary isothermal shift furnace, and low-temperature deep shift is carried out under the action of low-temperature sulfur-tolerant shift catalyst, and high-pressure and low-pressure steam is by-produced;

[0057] The packing height of the low-temperature sulfur-tolerant shift catalyst is 2.5 m, the space velocity is 1200 h -1 , the reaction temperature is 180 DEG C, the pressure is 5.5 MPa, and the low-pressure waste heat boiler is embedded between the catalyst bed layers to by-produce 0.8 MPa saturated steam;

[0058] The low-temperature sulfur-tolerant shift catalyst comprises the following components: CoO 2wt%, MoO3 8wt%, Y2O3 1wt%, Nd2O30.5wt%, and the balance is TiO2-γ-Al2O3@ZIF-67 composite carrier (ZIF-67 loading amount 10wt%, specific surface area 350 m2 / g), a preparation method comprising:

[0059] (1) using tetrabutyl titanate and aluminum isopropoxide as raw materials, citric acid as a chelating agent, stirring at 80°C for 4h to form a sol, drying at 120°C for 6h, and calcining at 500°C for 4h to obtain TiO2-γ-Al2O3 (mass ratio of TiO2 to γ-Al2O3 1:3);

[0060] (2) dispersing the TiO2-γ-Al2O3 in a methanol solution, adding Co(NO3)2·6H2O and 2-methylimidazole (molar ratio 1:2), and reacting at room temperature for 24h, centrifuging, washing, and drying at 80°C for 12h to obtain a composite carrier;

[0061] (3) loading Co(NO3)2, (NH4)6Mo7O 24 24·3H2O, Y(NO3)3, and Nd(NO3)3 mixed solutions by using an equal volume impregnation method, drying at 120°C for 4h, calcining at 450°C for 3h, and tabletting to form a shape (particle size 2-3mm) to obtain a low-temperature sulfur-tolerant shift catalyst;

[0062] S3, cooling and separating the condensate of the secondary shift gas, collecting all the condensate, passing the collected condensate into a stripping tower, and stripping using 0.5MPa saturated steam, the operating temperature of the stripping tower being 120°C, the pressure being 0.55MPa, the volume ratio of steam to condensate being 3:1, and the NH3 content in the condensate after stripping being controlled to be ≤5ppm, followed by removing H2S and organic matter by using a pervaporation membrane, and recycling the treated condensate;

[0063] The removal of H2S and organic matter by using the pervaporation membrane uses a modified PDMS membrane, the operating temperature being 40°C and the operating pressure being 0.3MPa, and the H2S content in the treated condensate being ≤0.1ppm;

[0064] The preparation method of the modified PDMS membrane is as follows: dispersing graphene oxide (GO) in chloroform (concentration 0.5mg / mL) by ultrasonic dispersion, adding A component (vinyl-terminated PDMS) of Dow Corning 184 and a crosslinking agent (mass ratio 10:1), the crosslinking agent being methyltriacetoxysilane, and then adding ZIF-8 nanoparticles (particle size 50nm, addition amount 5% of the mass of the PDMS), stirring for 2h to form a uniform casting solution, coating the casting solution on a porous alumina support (coating thickness 50μm), and curing at 80°C for 4h to obtain a PDMS-GO-ZIF-8 composite membrane, the H2S permeability coefficient of which being ≥1.5×10 -10 cm 3 ·cm / (cm 2 ·s·Pa) and the H2O / H2S separation factor being ≥200;

[0065] S4, the adsorbent and catalyst regeneration is finally carried out, namely;

[0066] The adsorbent is regenerated by using the low-pressure steam by-produced in step S2, the regeneration temperature is 160 DEG C, the regeneration time is 4h, and the regeneration tail gas is sent to a sulfur recovery device to prepare sulfuric acid;

[0067] When the catalyst is regenerated, the mixed gas of oxygen-rich air and nitrogen (O2 content 25%) is used for oxidation regeneration, the regeneration temperature is 380 DEG C, the regeneration time is 8h, and the waste heat generated in the regeneration process is used to preheat desalted water through a heat exchanger (preheated to 60 DEG C).

[0068] Example 2

[0069] A crude coal gas shift process applied to ammonia production, comprising the following steps:

[0070] S1, the gasification crude coal gas is sequentially subjected to high-temperature electrostatic precipitation, ceramic membrane filtration, dust removal and oil removal, then selectively removes H2S through a pre-desulfurization tower, and finally uses adiabatic plus two-stage isothermal reaction and shift gas preheating to separate and condense liquid;

[0071] The electric field strength is controlled to be 4kV / cm during the high-temperature electrostatic precipitation;

[0072] The membrane pore size of the ceramic membrane filtration is 0.15μm, and the operating pressure difference is 0.12MPa;

[0073] The adsorbent used in the pre-desulfurization tower is mesoporous modified activated carbon loaded with ZnO-CuO, the operating temperature is 135 DEG C, the operating pressure is 1MPa, and the outlet H2S concentration is controlled to be lower than 0.3%;

[0074] The preparation of the adsorbent comprises the following steps:

[0075] S101, mesoporous activated carbon is prepared by using KOH activation method with coconut shell activated carbon as raw material, the activation temperature is 820 DEG C, the mass ratio of KOH to activated carbon is 3.5:1, the holding time is 2.5h, and the mesoporous pore size is controlled to be 3nm, and the specific surface area is 900m 2 / g;

[0076] S102, an equal-volume impregnation method is used to load Zn(NO3)2 and Cu(NO3)2 mixed solution, the molar ratio of Zn 2+ to Cu 2+ is 2:1, and the total metal ion concentration is 0.7mol / L;

[0077] S103, drying at 135 DEG C for 5h and calcining at 380 DEG C for 3.5h, to obtain ZnO-CuO / mesoporous activated carbon adsorbent with a loading amount of 10wt%;

[0078] The specific process of using adiabatic addition and secondary isothermal reaction and waste heat of shift gas and separating condensate is as follows: the pre-desulfurized crude coal gas is introduced into a gas-gas heat exchanger, and the crude coal gas is preheated to 230 DEG C by using the waste heat of the shift gas at the outlet of the secondary shift converter at 198 DEG C, and 35% of the condensate water in the crude coal gas is separated by a gas-liquid separator at the same time;

[0079] S2, the detoxification preheated crude coal gas is introduced into an adiabatic furnace, and high-temperature shift is carried out under the action of high-temperature sulfur-tolerant shift catalyst, and medium-pressure steam is by-produced; the loading height of the high-temperature sulfur-tolerant shift catalyst is 3.5 m, the space velocity is 900 h -1 -1, the reaction temperature is 310 DEG C, and the pressure is 6 MPa, so that the CO content in the crude coal gas is reduced to 5-8%, the high-temperature shift gas after reaction is sprayed to reduce the temperature, 15 tons of saturated steam at a pressure of 6.5 MPa is by-produced per hour, the production of by-product methane is reduced at the same time, and the methane concentration at the outlet of the control system is controlled to be below 2000 ppm;

[0080] The high-temperature sulfur-tolerant shift catalyst comprises CoO 4 wt%, MoO3 12 wt%, CeO2 3 wt%, La2O31.5 wt%, ZrO2 2 wt%, and the balance is mesoporous γ-Al2O3 carrier, the mesoporous pore size is 7 nm, and the specific surface area is 250 m 2 / g, and the preparation method comprises the following steps:

[0081] S301, mesoporous γ-Al2O3 is obtained by using aluminum isopropoxide as an aluminum source, P123 as a template, hydrothermal reaction at 135 DEG C for 14 h, and calcination at 570 DEG C for 7 h;

[0082] S302, Co(NO3)2, (NH4)6Mo7O 24 , Ce(NO3)3, La(NO3)3 and Zr(NO3)4 are dissolved in deionized water in proportion, ammonia water is used as a precipitant, the precipitation pH is controlled to be 9, and aging is carried out at 65 DEG C for 2.5 h;

[0083] S303, the precursor is mixed with the mesoporous γ-Al2O3 carrier, washed, dried at 135 DEG C for 5 h, calcined at 520 DEG C for 5 h, pressed into a tablet (particle size 3-5 mm), and a high-temperature sulfur-tolerant shift catalyst is obtained;

[0084] The primary shift gas is cooled to 240 DEG C and then introduced into a primary isothermal and secondary isothermal shift converter, and low-temperature deep shift is carried out under the action of a low-temperature sulfur-tolerant shift catalyst, and high-pressure and low-pressure steam is by-produced;

[0085] The loading height of the low-temperature sulfur-tolerant shift catalyst is 2.7 m, the space velocity is 1300 h -1 -1, the reaction temperature is 210 DEG C, the pressure is 5.6 MPa, and a low-pressure waste heat boiler is embedded between catalyst bed layers to by-produce 1 MPa saturated steam;

[0086] The low-temperature sulfur-tolerant shift catalyst is composed of CoO 3wt%, MoO3 10wt%, Y2O3 2wt%, Nd2O31wt%, and the balance of TiO2-γ-Al2O3@ZIF-67 composite carrier (ZIF-67 loading amount 12wt%, specific surface area 400m 2 / g), and the preparation method comprises:

[0087] (1) using tetrabutyl titanate and aluminum isopropoxide as raw materials, citric acid as a chelating agent, stirring at 85°C for 5h to form a sol, drying at 120°C for 7h, and calcining at 500°C for 4.5h to obtain TiO2-γ-Al2O3 (mass ratio of TiO2 to γ-Al2O3 1:3);

[0088] (2) dispersing TiO2-γ-Al2O3 in a methanol solution, adding Co(NO3)2·6H2O and 2-methylimidazole (molar ratio 1:2), and reacting at room temperature for 30h, centrifuging, washing, and drying at 80°C for 12h to obtain a composite carrier;

[0089] (3) loading Co(NO3)2, (NH4)6Mo7O 24 , Y(NO3)3, and Nd(NO3)3 mixed solution by equal volume impregnation method, drying at 1350°C for 5h, calcining at 470°C for 4h, and tabletting (particle size 2-3mm) to obtain a low-temperature sulfur-tolerant shift catalyst;

[0090] S3, cooling and separating the condensate of the secondary shift gas, collecting all the condensate, passing the collected condensate into a stripping tower, stripping with 0.5MPa saturated steam, the operating temperature of the stripping tower being 125°C, the pressure being 0.57MPa, the volume ratio of steam to condensate being 4:1, and controlling NH3 in the condensate after stripping to be ≤5ppm, and then removing H2S and organic matter by a pervaporation membrane, and recycling the treated condensate;

[0091] The pervaporation membrane for removing H2S and organic matter is a modified PDMS membrane, the operating temperature is 45°C, and the operating pressure is 0.4MPa, and the H2S content in the treated condensate is ≤0.1ppm;

[0092] The preparation method of the modified PDMS membrane is: ultrasonic dispersion of graphene oxide (GO) in chloroform (concentration 0.75 mg / mL), adding the A component of Dow Corning SYLGARD 184 (vinyl-terminated PDMS), and a crosslinking agent (mass ratio 10:1), the crosslinking agent is methyltriacetoxysilane, and then adding ZIF-8 nanoparticles (particle size 70 nm, the addition amount is 8% of the mass of PDMS), stirring for 2.5 h to form a uniform casting solution; the casting solution is coated on a porous alumina support (coating thickness 50-80 μm), and cured at 90℃ for 5 h to obtain a PDMS-GO-ZIF-8 composite membrane, the H2S permeation coefficient of which is ≥1.5×10 -10 cm 3 ·cm / (cm 2 ·s·Pa), and the H2O / H2S separation factor is ≥200.

[0093] S4, regeneration of the adsorbent and the catalyst is finally carried out;

[0094] The adsorbent is regenerated by using low-pressure steam by-produced in step S2, the regeneration temperature is 170℃, the regeneration time is 5 h, and the tail gas of regeneration is sent to a sulfur recovery device to prepare sulfuric acid;

[0095] When the catalyst is regenerated, a mixed gas of oxygen-rich air and nitrogen (O2 content 27%) is used for oxidation regeneration, the regeneration temperature is 400℃, the regeneration time is 10 h, and the waste heat generated in the regeneration process is used to preheat desalted water through a heat exchanger (preheated to 65℃).

[0096] Example 3

[0097] A crude coal gas shift process applied to synthetic ammonia production, comprising the following steps:

[0098] S1, the gasification crude coal gas is sequentially subjected to high-temperature electrostatic precipitation, ceramic membrane filtration and oil removal, and then selectively removes H2S through a pre-desulfurization tower, and finally uses adiabatic plus two-stage isothermal reaction and shift gas preheating to separate and condense liquid;

[0099] The electric field strength is controlled to be 5 kV / cm during the high-temperature electrostatic precipitation;

[0100] The membrane pore size of the ceramic membrane filtration is 0.2 μm, and the operating pressure difference is 0.15 MPa;

[0101] The adsorbent used in the pre-desulfurization tower is mesoporous modified activated carbon loaded with ZnO-CuO, the operating temperature is 150℃, the operating pressure is 1.2 MPa, and the outlet H2S concentration is controlled to be lower than 0.3%;

[0102] The preparation of the adsorbent comprises the following steps:

[0103] S101, mesoporous activated carbon is prepared by using coconut shell activated carbon as raw material and adopting KOH activation method, the activation temperature is 850 DEG C, the mass ratio of KOH to activated carbon is 4:1, the holding time is 3h, the mesopore size is controlled to be 5nm, and the specific surface area is 1000m 2 / g;

[0104] S102, Zn(NO3)2 and Cu(NO3)2 mixed solution is loaded by adopting equal volume impregnation method, the molar ratio of Zn 2+ to Cu 2+ is 2:1, and the total metal ion concentration is 0.8mol / L;

[0105] S103, drying is carried out at 150 DEG C for 6h, roasting is carried out at 400 DEG C for 4h, and the ZnO-CuO / mesoporous activated carbon adsorbent with a loading of 12wt% is obtained;

[0106] The utilization of adiabatic plus secondary isothermal reaction and waste heat of shift gas and separation of condensate is specifically as follows: the pre-desulfurized raw gas is introduced into a gas-gas heat exchanger, and is preheated to 240 DEG C by using the waste heat of 200 DEG C of the shift gas at the outlet of a secondary shift furnace, and at the same time, 40% of the condensate water in the raw gas is separated out through a gas-liquid separator;

[0107] S2, the detoxification preheated raw gas is introduced into an adiabatic furnace, and high-temperature shift is carried out under the action of a high-temperature sulfur-tolerant shift catalyst, and medium-pressure steam is by-produced; the packing height of the high-temperature sulfur-tolerant shift catalyst is 4m, the space velocity is 1000h -1 -1, the reaction temperature is 350 DEG C, and the pressure is 6.2MPa, so that the CO content in the raw gas is reduced to 5-8%, the high-temperature shift gas after reaction is sprayed to reduce temperature, 15 tons of saturated steam are by-produced per hour, the pressure is 6.5MPa, the generation of by-product methane is reduced, and the methane concentration at the outlet of the system is controlled to be below 2000ppm;

[0108] The high-temperature sulfur-tolerant shift catalyst comprises CoO 5wt%, MoO315wt%, CeO24wt%, La2O32wt%, ZrO23wt%, and the balance is mesoporous γ-Al2O3 carrier, the mesopore size is 10nm, and the specific surface area is 300m 2 / g, and the preparation method comprises the following steps:

[0109] S301, mesoporous γ-Al2O3 is obtained by using aluminum isopropoxide as an aluminum source and P123 as a template agent, hydrothermal reaction is carried out at 150 DEG C for 16h, and roasting is carried out at 600 DEG C for 8h;

[0110] S302, Co(NO3)2, (NH4)6Mo7O 24Ce(NO3)3, La(NO3)3, and Zr(NO3)4 were dissolved in deionized water in a certain proportion, and ammonia water was used as a precipitant. The pH of the precipitate was controlled at 9.5, and the precipitate was aged at 70°C for 3 hours.

[0111] S303. The precursor is mixed with a mesoporous γ-Al2O3 support, washed, dried at 150℃ for 6 hours, calcined at 550℃ for 6 hours, and pressed into tablets (particle size 3~5 mm) to obtain a high-temperature sulfur-resistant conversion catalyst.

[0112] After being cooled to 260°C, the first-stage shift gas enters the first-stage and second-stage isothermal shift furnaces, where it undergoes low-temperature deep shifting under the action of a low-temperature sulfur-resistant shift catalyst, producing high-pressure and low-pressure steam as byproducts.

[0113] The low-temperature sulfur-resistant shift catalyst has a loading height of 3m and a space velocity of 1500h. -1 The reaction temperature is 250℃, the pressure is 5.8MPa, and 1.2MPa saturated steam is embedded in the catalyst bed between the layers of the low-pressure waste heat boiler.

[0114] The composition of the low-temperature sulfur-resistant shift catalyst is: CoO 4wt%, MoO3 12wt%, Y2O3 3wt%, Nd2O3 1.5wt%, with the balance being TiO2-γ-Al2O3@ZIF-67 composite support (ZIF-67 loading 15wt%, specific surface area 450m²). 2 / g), and its preparation method includes:

[0115] (1) Using tetrabutyl titanate and aluminum isopropoxide as raw materials, and citric acid as chelating agent, the mixture was stirred at 90°C for 6 hours to form a sol, dried at 120°C for 8 hours, and calcined at 500°C for 5 hours to obtain TiO2-γ-Al2O3 (the mass ratio of TiO2 to γ-Al2O3 is 1:3).

[0116] (2) TiO2-γ-Al2O3 was dispersed in methanol solution, and Co(NO3)2·6H2O and 2-methylimidazole (molar ratio 1:2) were added. The mixture was reacted at room temperature for 36 h, centrifuged, washed, and dried at 80 °C for 12 h to obtain the composite support.

[0117] (3) Co(NO3)2 and (NH4)6Mo7O were loaded using the equal volume impregnation method. 24 A mixed solution of Y(NO3)3 and Nd(NO3)3 was dried at 150℃ for 6 hours, calcined at 500℃ for 5 hours, and then pressed into tablets (particle size 2~3 mm) to obtain a low-temperature sulfur-resistant conversion catalyst.

[0118] S3, cooling and separating the secondary shift gas to condensate liquid, collecting all the condensate liquid, and feeding the collected condensate liquid into a stripping tower, and stripping the condensate liquid by using 0.5 MPa saturated steam, the operating temperature of the stripping tower is 130℃, the pressure is 0.6 MPa, the volume ratio of steam to condensate liquid is 5:1, and the NH3 content in the condensate liquid after stripping is controlled to be less than or equal to 5 ppm, and then removing H2S and organic matter in the condensate liquid by using a pervaporation membrane, and recycling the treated condensate water;

[0119] The modified PDMS membrane is used to remove H2S and organic matter in the condensate liquid, the operating temperature is 50℃, the operating pressure is 0.5 MPa, and the H2S content in the treated condensate water is less than or equal to 0.1 ppm;

[0120] The preparation method of the modified PDMS membrane is as follows: dispersing graphene oxide (GO) in chloroform (concentration 1 mg / mL), adding A component (vinyl-terminated PDMS) of Dow Corning 184, and crosslinking agent (mass ratio 10:1), the crosslinking agent is methyltriacetoxysilane, and then adding ZIF-8 nanoparticles (particle size 100 nm, and the addition amount is 10% of the mass of PDMS), stirring for 3 h to form a uniform casting solution; coating the casting solution on a porous alumina support (coating thickness 80 μm), and curing at 100℃ for 6 h to obtain a PDMS-GO-ZIF-8 composite membrane, the H2S permeability coefficient of which is greater than or equal to 1.5*10 -10 cm 3 ·cm / (cm 2 ·s·Pa), and the H2O / H2S separation factor is greater than or equal to 200;

[0121] S4, finally, the adsorbent and the catalyst are regenerated;

[0122] The adsorbent is regenerated by using low-pressure steam by-produced in step S2, the regeneration temperature is 180℃, the regeneration time is 6 h, and the regeneration tail gas is sent to a sulfur recovery device to prepare sulfuric acid;

[0123] When the catalyst is regenerated, the mixed gas of oxygen-rich air and nitrogen (O2 content 30%) is used for oxidation regeneration, the regeneration temperature is 420℃, the regeneration time is 12 h, and the waste heat generated in the regeneration process is used to preheat desalted water through a heat exchanger (preheated to 70℃).

[0124] Comparative Example 1

[0125] In this comparative example 1, the adsorbent is replaced by adsorbent I, and the other steps are the same as those in Example 2.

[0126] The preparation of the adsorbent I includes the following steps:

[0127] (1) taking granular activated carbon of coconut shell (specific surface area about 500~600 m 2 / g, pore size 1~2nm), soak in deionized water for 2h to remove surface impurities, dry at 120℃ for 4h, and cool down for standby;

[0128] (2) Prepare Zn(NO3)2 aqueous solution (concentration 0.6mol / L), and immerse the pretreated activated carbon in the Zn(NO3)2 solution at a ratio of activated carbon mass: solution volume = 1g: 1.2mL, stir at room temperature for 1h, and stand for 6h to ensure that the solution is completely absorbed by the carrier;

[0129] (3) Place the impregnated activated carbon in an oven, dry at 130℃ for 6h (to remove water); then transfer to a muffle furnace, calcine at 360℃ for 4h, and cool down naturally to obtain the adsorbent I with a loading of 8wt%.

[0130] Comparative Example 2

[0131] Comparative Example 2 is the same as Example 2, except that the high-temperature sulfur-tolerant shift catalyst is replaced by high-temperature catalyst I.

[0132] Preparation of high-temperature catalyst I, including the following steps:

[0133] (1) Take aluminum nitrate as the aluminum source and ammonia as the precipitant, slowly drop ammonia into 1mol / L aluminum nitrate solution at room temperature, control pH=8.5, stir for 30min, and stand for 4h; filter to obtain aluminum hydroxide precipitate, wash with deionized water until the filtrate is neutral, dry at 120℃ for 5h, calcine at 550℃ for 6h, and crush to obtain ordinary γ-Al2O3 carrier (specific surface area about 180~220m 2 / g, no mesoporous structure);

[0134] (2) Dissolve Co(NO3)2·6H2O and (NH4)6Mo7O 24 ·4H2O in deionized water at a ratio of CoO: MoO3=3wt%: 10wt%, and stir until completely dissolved; immerse the ordinary γ-Al2O3 carrier in the mixed solution by equal volume impregnation method, stand at room temperature for 4h;

[0135] (3) Dry the impregnated carrier at 130℃ for 5h, and calcine at 500℃ for 5h; then press into tablets by tablet press, screen the particles with a particle size of 3~5mm, and obtain high-temperature catalyst I.

[0136] Comparative Example 3

[0137] Comparative Example 3 is the same as Example 2, except that the low-temperature sulfur-tolerant shift catalyst is replaced by low-temperature catalyst I.

[0138] Preparation of low-temperature catalyst I, including the following steps:

[0139] (1) Take tetrabutyl titanate as titanium source and aluminum isopropylate as aluminum source (mass ratio of TiO2 and γ-Al2O3 is 1:3), dissolve them in ethanol, add a small amount of nitric acid to adjust pH to 3, stir for 3 h at room temperature to form a uniform sol; dry the sol naturally in a fume hood, dry at 120℃ for 7 h, and calcine at 500℃ for 4 h to obtain a traditional TiO2-γ-Al2O3 mixed carrier (specific surface area is about 250~300 m 2 / g);

[0140] (2) Prepare a mixed aqueous solution of Co(NO3)2 and (NH4)6Mo7O 24 24·12H2O, dissolve them according to the ratio of CoO:MoO3=2.5wt%:9wt%, and immerse the traditional TiO2-γ-Al2O3 carrier in the mixed solution by equal volume impregnation method, and stand for 5 h at room temperature;

[0141] (3) Dry the impregnated carrier at 135℃ for 5 h, calcine at 450℃ for 4 h, press into a tablet, and screen the particles with a particle size of 2~3 mm to obtain a low-temperature catalyst I.

[0142] Comparative Example 4

[0143] Comparative Example 4 and Example 2 are compared, the modified PDMS membrane is replaced by an unmodified PDMS membrane, and the other steps are the same as those in Example 2.

[0144] The effect of the crude gas shift process of Examples 1~3 and Comparative Examples 1~4 above is tested, and the test results are shown in Table 1 below.

[0145] Table 1

[0146] Pre-desulphurization outlet H2S concentration (%) Primary shift CO conversion (%) Secondary shift CO conversion (%) Membrane outlet condensate H2S concentration (ppm) Condensate water recovery rate (%) Example 1 0.09 91.9 98.6 0.08 91 Example 2 0.08 92.2 99.3 0.07 92 Example 3 0.08 92.5 99.2 0.06 92 Comparative Example 1 0.85 - - - - Comparative Example 2 - 81.3 - - - Comparative Example 3 - - 90.1 - - Comparative Example 4 - - - 5.8 65

[0147] From the above table 1, compared with the examples, the comparative example 1 uses a traditional adsorbent, and the chemical adsorption of H2S is weak, which shows that the traditional adsorbent cannot meet the demand of the subsequent catalyst for low-sulfur raw gas due to the lack of mesoporous regulation and the single ZnO activity. The comparative example 2 uses a traditional catalyst, and the first-stage shift CO conversion rate is reduced to 81.3, which cannot maintain long-term stable operation, which shows that the CeO2 / La2O3 / ZrO2 additive of the high-temperature catalyst of the present application can inhibit the high-temperature sintering of the γ-Al2O3 carrier (the mesoporous structure is stable at 310℃), and at the same time, enhance the dispersity of the Co-Mo active component, so that the first-stage CO conversion rate reaches 92.5%, and the effect is remarkable. The second-stage shift CO conversion rate of the comparative example 3 is only 90.1, which is far lower than that of the examples, which shows that the improvement of the catalyst of the present application significantly improves the catalytic activity, and is helpful to realize deep shift. The comparative example 4 uses a traditional PDMS membrane, and the outlet H2S concentration reaches 5.8ppm, and the reuse rate is reduced to 65%, and the separation performance is significantly weaker than that of the examples, which shows that the modified PDMS membrane of the present application has good selectivity to H2S.

[0148] The above specific embodiments further explain the purpose, technical solutions and advantages of the present application. It should be understood that the above description is only a specific embodiment of the present application, and is not used to limit the protection scope of the present application. Any modification, equivalent replacement, improvement, etc. within the spirit and principle of the present application should be included in the protection scope of the present application.

Claims

1. A crude gas shift process applied to ammonia synthesis, characterized in that, Includes the following steps: S1. The gasified crude coal gas is sequentially passed through high-temperature electrostatic dust removal, ceramic membrane filtration for dust removal and oil removal, then through a pre-desulfurization tower for selective removal of H2S, and finally the waste heat from the adiabatic addition of a two-stage isothermal reaction and the shift gas is used to separate the condensate. S2. The detoxified and preheated crude coal gas is fed into an adiabatic furnace, where it undergoes high-temperature conversion under the action of a high-temperature sulfur-resistant conversion catalyst, producing medium-pressure steam as a byproduct. The first-stage conversion gas is cooled to 230~260℃ and then enters a first-stage isothermal and second-stage isothermal conversion furnace, where it undergoes low-temperature deep conversion under the action of a low-temperature sulfur-resistant conversion catalyst, producing high-pressure and low-pressure steam as byproducts. S3. Cool and separate the secondary conversion gas into condensate. Collect all the condensate and first strip it with steam to remove ammonia. Then, remove H2S and organic matter through a pervaporation membrane. The treated condensate is then reused. S4. Finally, regenerate the adsorbent and catalyst.

2. The crude gas shift process for ammonia synthesis according to claim 1, characterized in that, In step S1, the electric field strength is controlled to be 3~5kV / cm during high-temperature electrostatic dust removal. The ceramic membrane filter has a pore size of 0.1~0.2μm and an operating pressure difference of 0.1~0.15MPa; The pre-desulfurization tower uses ZnO-CuO / mesoporous activated carbon adsorbent, operates at a temperature of 120~150℃ and a pressure of 0.8~1.2MPa, and controls the outlet H2S concentration to be below 0.3%. The specific steps of utilizing adiabatic and secondary isothermal reactions and waste heat from shift gas to separate condensate are as follows: the pre-desulfurized crude coal gas is passed into a gas-to-gas heat exchanger, and the waste heat from the shift gas at the outlet of the secondary shift furnace (195-200℃) is used to preheat it to 220-240℃. Simultaneously, 30-40% of the condensate in the crude coal gas is separated by a gas-liquid separator.

3. The crude gas shift process for ammonia synthesis according to claim 2, characterized in that, The preparation of the adsorbent includes the following steps: S101. Mesoporous activated carbon is prepared using coconut shell activated carbon as raw material and KOH activation method. The activation temperature is 800~850℃, the mass ratio of KOH to activated carbon is (3~4):1, the holding time is 2~3h, and the mesopore diameter is controlled to be 2~5nm and the specific surface area is 800~1000m². 2 / g; S102, A mixed solution of Zn(NO3)2 and Cu(NO3)2 is loaded using an equal-volume impregnation method. 2+ With Cu 2+ The molar ratio is 2:1, and the total metal ion concentration is 0.5~0.8 mol / L. S103 is dried at 120~150℃ for 4~6h and calcined at 350~400℃ for 3~4h to obtain a ZnO-CuO / mesoporous activated carbon adsorbent with a loading of 8~12wt%.

4. The crude gas shift process for ammonia synthesis according to claim 1, characterized in that, The high-temperature sulfur-resistant shift catalyst described in step S2 has a loading height of 3-4 m and a space velocity of 800-1000 h⁻¹. -1 The reaction temperature is 280~350℃ and the pressure is 5.8~6.2MPa, which reduces the CO content in the crude coal gas to 5~8%. The high-temperature shift gas after the reaction is cooled by spraying water. The by-product is 15 tons of saturated steam per hour at a pressure of 6.5MPa, which at the same time reduces the generation of methane by-reaction. The methane concentration at the control system outlet is kept below 2000ppm.

5. The crude gas shift process for ammonia synthesis according to claim 4, characterized in that, The high-temperature sulfur-resistant shift catalyst has the following composition: CoO 3~5wt%, MoO3 10~15wt%, CeO2 2~4wt%, La2O3 1~2wt%, ZrO2 1~3wt%, with the balance being a mesoporous γ-Al2O3 support. Its preparation method includes: S301. Using aluminum isopropoxide as the aluminum source and P123 as the template agent, the mixture is hydrothermally reacted at 120~150℃ for 12~16h and calcined at 550~600℃ for 6~8h to obtain mesoporous γ-Al2O3. S302. Co(NO3)2, (NH4)6Mo7O 24 Ce(NO3)3, La(NO3)3, and Zr(NO3)4 were dissolved in deionized water in a certain proportion, and ammonia was used as a precipitant. The pH of the precipitate was controlled at 8.5~9.5, and the precipitate was aged at 60~70℃ for 2~3 hours. S303: The precursor is mixed with a mesoporous γ-Al2O3 support, washed, dried at 120~150℃ for 4~6h, calcined at 500~550℃ for 4~6h, and pressed into tablets to obtain a high-temperature sulfur-resistant conversion catalyst.

6. The crude gas shift process for ammonia synthesis according to claim 1, characterized in that, The low-temperature sulfur-resistant shift catalyst described in step S2 has a loading height of 2.5~3m and a space velocity of 1200~1500h. -1 The reaction temperature is 180~250℃, the pressure is 5.5~5.8MPa, and a low-pressure waste heat boiler by-product of 0.8~1.2MPa saturated steam is embedded between the catalyst bed layers.

7. The crude gas shift process for ammonia synthesis according to claim 6, characterized in that, The composition of the low-temperature sulfur-resistant shift catalyst is: CoO 2~4wt%, MoO3 8~12wt%, Y2O3 1~3wt%, Nd2O3 0.5~1.5wt%, with the balance being TiO2-γ-Al2O3@ZIF-67 composite support. Its preparation method includes: (1) Using tetrabutyl titanate and aluminum isopropoxide as raw materials, and citric acid as chelating agent, the mixture is stirred at 80~90℃ for 4~6h to form a sol, dried at 120℃ for 6~8h, and calcined at 500℃ for 4~5h to obtain TiO2-γ-Al2O3 (TiO2 to γ-Al2O3 mass ratio 1:3). (2) Disperse TiO2-γ-Al2O3 in methanol solution, add Co(NO3)2·6H2O and 2-methylimidazole, react at room temperature for 24~36h, centrifuge, wash, and dry at 80℃ for 12h to obtain composite support; (3) Co(NO3)2 and (NH4)6Mo7O were loaded using the equal volume impregnation method. 24 A mixed solution of Y(NO3)3 and Nd(NO3)3 was dried at 120~150℃ for 4~6h, calcined at 450~500℃ for 3~5h, and then pressed into tablets to obtain a low-temperature sulfur-resistant conversion catalyst.

8. The crude gas shift process for ammonia synthesis according to claim 1, characterized in that, The steam stripping for ammonia removal in step S3 specifically involves: passing the collected condensate into a stripping tower and stripping it with 0.5 MPa saturated steam. The operating temperature of the stripping tower is 120~130℃, the pressure is 0.55~0.6 MPa, the volume ratio of steam to condensate is (3~5):1, and the NH3 content in the condensate after stripping is controlled to be ≤5 ppm. The pervaporation membrane removes H2S and organic matter using a modified PDMS membrane, with an operating temperature of 40~50℃ and an operating pressure of 0.3~0.5MPa. The H2S content in the condensate after treatment is ≤0.1ppm.

9. The crude gas shift process for ammonia synthesis according to claim 1, characterized in that, The adsorbent described in step S4 is regenerated using low-pressure steam produced as a byproduct of step S2. The regeneration temperature is 160~180℃ and the regeneration time is 4~6h. The regeneration tail gas is sent to a sulfur recovery unit to produce sulfuric acid.

10. The crude gas shift process for ammonia synthesis according to claim 1, characterized in that, In step S4, the catalyst is regenerated by using a mixture of oxygen-enriched air and nitrogen for oxidation regeneration. The regeneration temperature is 380~420℃ and the regeneration time is 8~12h. The waste heat generated during the regeneration process is used to preheat the demineralized water through a heat exchanger.