Novel green synthesis gas purification treatment device

Abstract

The utility model discloses a novel green synthesis gas purification treatment device, which purifies synthesis gas in sections and recycles the synthesis gas step by step, and comprises a combined compressor, an inlet heat exchanger, an absorption system, a flash evaporation system, a desorption system, a regeneration system and a light oil recovery system. According to the utility model, a multi-stage absorption system design is adopted, and various impurities in the synthesis gas prepared from biomass are subjected to stage purification treatment. According to the utility model, CO, H2, CO2, sulfur-containing acid gas and light oil in the synthesis gas are respectively recycled step by step in the flash evaporation system, the desorption system, the regeneration system and the light oil recovery system, so that the maximum utilization of resources is realized. The combined compressor is arranged, the recycle gas compression of the flash evaporation system and the green synthesis gas compression of biomass gasification are subjected to coupling design, the technological process is simplified, and the device investment is reduced. According to the utility model, the inlet separator adopts shunting type heat exchange, so that the temperature difference is reduced, and the cooling capacity utilization is maximized.

Description

Technical Field

[0001] The utility model relates to the technical field of green synthesis gas purification, specifically a new type of green synthesis gas purification and treatment device which removes carbon dioxide, organic sulfur, inorganic sulfur and light oil components such as benzene and naphthalene in synthesis gas produced by biomass gasification in stages to obtain qualified purified gas and recover carbon dioxide, acid gas and light oil step by step. Background Art

[0002] Traditional chemical products like synthetic ammonia and methanol can be produced from a variety of raw materials. In the 1950s, the primary raw materials for methanol production were coal, coke, and coke oven gas. By the 1960s, natural gas gradually became the primary feedstock for methanol production. While methanol itself is a clean energy source, its production process was not always truly clean.

[0003] With the advancement of science and technology, production technology has developed rapidly in recent years, resulting in the emergence of green chemical products such as green methanol and green synthetic ammonia. Green methanol and green aviation fuel can be produced by biomass hydrogen production or water electrolysis hydrogen production combined with carbon dioxide; green synthetic ammonia can be obtained by biomass hydrogen production or water electrolysis hydrogen production combined with air separation nitrogen. The cost of producing hydrogen by water electrolysis is high, while biomass, as a readily available and inexpensive material, can significantly reduce the production cost of green chemical products. However, green syngas produced from biomass contains a large number of components that are detrimental to the synthesis reaction. Therefore, a technology is needed to purify green syngas and remove these harmful components.

[0004] Biomass is the main raw material for the preparation of green chemical products such as green methanol and green aviation fuel. After pyrolysis under certain conditions, the carbon after pyrolysis undergoes redox reaction with the gasification medium (air, water vapor) supplied, producing a certain amount of CO, H2, CO2, N2, CH4, C n H m , sulfides, and other mixed gases. CO2 is detrimental to methanol synthesis; sulfides emit toxic gases after reacting with the catalyst; and naphthalene precipitates upon cooling, clogging pipes and heat exchangers. To eliminate the negative impacts of carbon dioxide, sulfides, and naphthalene on the process, the synthesis feed gas must be purified to ensure the safe and efficient operation of the green methanol plant.

[0005] The mainstream methods for syngas purification and decarbonization include pressure swing adsorption, MDEA solution absorption, and low-temperature methanol washing. These methods address the problems of large green syngas volume, high sulfur content, high moisture content, and impurities. Pressure swing adsorption is difficult to operate and has high process costs. In addition, pretreatment and fine desulfurization are required before treatment. The pores of the adsorbent are easily clogged by impurities, and H2S and water will be adsorbed on the adsorption material or damage the structure of the adsorption material, affecting the purification effect. As for the MEDA decarbonization system, the green syngas from biomass gasification will carry light oil components, which are insoluble in the MDEA solution. Oil droplets easily float on the oil-water interface and stratify. In addition, the MDEA decarbonization system will generate a large number of bubbles during the gas-liquid mass transfer process. When the oil phase content increases, the surface tension of the bubbles increases, making it difficult for the bubbles to burst in a short period of time. The pressure difference in the absorption tower will increase accordingly. In severe cases, the tower plates will be flooded, and the outlet gas phase components cannot be controlled.

[0006] Low-temperature methanol scrubbing, a syngas purification process and apparatus that simultaneously desulfurizes, decarbonizes, and removes oils, can address the shortcomings of the aforementioned methods. This technology offers a high degree of gas purification. The total sulfur content in the purified gas can be reduced to below 0.1 ppm; methanol exhibits high selectivity for acid gases. H2S and CO2 can be absorbed separately in different equipment or at different locations within the same equipment and recovered separately under different equipment and conditions. Furthermore, the solubility of H2 and CO in methanol is low at low temperatures, significantly reducing effective gas loss. Methanol has high thermal and chemical stability and is not degraded by components such as organic sulfur and cyanide. It does not foam during operation and does not corrode equipment or pipelines. Furthermore, the CO2 and H2S components in the crude syngas can be recycled, enhancing economic efficiency.

[0007] Green methanol synthesis gas purification technology is a safe, reliable, simple and direct synthesis gas purification technology. It uses the extremely high solubility of methanol in acidic gases at low temperatures to remove H2S, COS, RSH, CO2, HCN, NO, as well as paraffins, aromatic hydrocarbons, crude benzene and other components from the raw gas. It can also dehydrate the gas to make it completely dry. The absorbed useful components can be recovered during the methanol regeneration process. Utility Model Content

[0008] The technical problem to be solved by the present invention is that, in view of the characteristics that the impurity components in the synthesis gas from biomass gasification are complex and difficult to recycle, a new green synthesis gas purification and treatment device is proposed for segmented purification and step-by-step recycling of synthesis gas. The new green synthesis gas purification device can purify carbon dioxide, organic sulfur, inorganic sulfur and light oil components such as benzene and naphthalene in the synthesis gas produced by biomass gasification, and at the same time, it can be flexibly adjusted according to the different requirements of the downstream green chemical product synthesis section for the purified gas composition, with a high degree of impurity purification and maximum resource utilization.

[0009] The technical problems to be solved by the present invention can be achieved through the following technical solutions:

[0010] A new type of green synthesis gas purification and treatment device, comprising:

[0011] a combined compressor having a raw synthesis gas inlet, a recycle gas inlet, and a compressed synthesis gas outlet, wherein the raw synthesis gas enters the combined compressor through the raw synthesis gas inlet, is compressed in the combined compressor to form compressed synthesis gas, and is delivered through the compressed synthesis gas outlet;

[0012] an inlet heat exchanger having a compressed syngas inlet and a pre-cooled syngas outlet, wherein the compressed syngas delivered from the compressed syngas outlet of the combined compressor enters the inlet heat exchanger through the compressed syngas inlet for pre-cooling, and forms pre-cooled syngas which is delivered from the pre-cooled syngas outlet;

[0013] An absorption system, the absorption system having a precooling synthesis gas inlet, a prewashing methanol outlet, a purified gas outlet, a sulfur-containing methanol outlet, a sulfur-free methanol outlet, and a lean methanol inlet; the precooling synthesis gas inlet is connected to the precooling synthesis gas outlet, and the precooling synthesis gas discharged from the precooling synthesis gas outlet of the inlet heat exchanger enters the absorption system through the precooling synthesis gas inlet of the absorption system for absorption; the prewashing methanol formed by the absorption system is delivered through the prewashing methanol outlet, the purified gas formed by the absorption system is delivered through the purified gas outlet, the sulfur-containing methanol formed by the absorption system is delivered through the sulfur-containing methanol outlet, and the sulfur-free methanol formed by the absorption system is delivered through the sulfur-free methanol outlet;

[0014] a flash evaporation system; the flash evaporation system has a sulfur-containing methanol inlet, a sulfur-free methanol inlet, a recycle gas outlet, and a methanol outlet; the sulfur-containing methanol inlet is connected to the sulfur-containing methanol outlet, receives the sulfur-containing methanol from the absorption system for flash evaporation to form recycle gas; the recycle gas outlet is connected to the recycle gas inlet; the recycle gas after flash evaporation is sent from the recycle gas outlet and the recycle gas inlet to a combined compressor for compression, cooling, and then returning to the feed gas;

[0015] a desorption system having a methanol inlet, a sulfur-rich methanol outlet, a tail gas outlet, a stripping gas inlet, and an H2S reflux inlet, wherein the methanol inlet is connected to the methanol outlet, the methanol from the flash evaporation system enters the desorption system and is stripped by the stripping gas entering the stripping gas inlet, and the stripped tail gas is sent out through the tail gas outlet; and the stripped sulfur-rich methanol is sent out through the sulfur-rich methanol outlet;

[0016] a regeneration system comprising a sulfur-rich methanol inlet, a lean methanol outlet, an acid gas outlet, a methanol replenishment inlet, a wastewater discharge outlet, a methanol aqueous solution inlet, and an H2S reflux outlet, wherein the sulfur-rich methanol inlet is connected to the sulfur-rich methanol outlet, the sulfur-rich methanol desorbed by the desorption system is fed into the regeneration system for regeneration, the lean methanol outlet is connected to the lean methanol inlet, and the regenerated lean methanol is fed into the absorption system; a portion of the regenerated acid gas enters the desorption system through the H2S reflux outlet and the H2S reflux inlet to increase the H2S concentration, and a portion is discharged through the acid gas outlet; wastewater is discharged through the wastewater discharge outlet, and methanol required to be replenished during the regeneration process is replenished through the methanol replenishment inlet;

[0017] A light oil recovery system, the light oil recovery system has a light oil outlet, a pre-wash methanol inlet and a methanol-water solution outlet, the pre-wash methanol inlet is connected to the pre-wash methanol outlet, the methanol-water solution outlet is connected to the methanol-water solution inlet, the pre-wash methanol enters the light oil recovery system for oil removal to form the methanol-water solution, which is then sent to the regeneration system, and the oil is sent out from the light oil outlet.

[0018] In a preferred embodiment of the present invention, the inlet heat exchanger adopts split-flow heat exchange, that is, a part of the hot raw synthesis gas is heat exchanged with the cold tail gas, and the remaining part of the hot raw synthesis gas is heat exchanged with the cold purified gas, and temperature difference control is adopted.

[0019] In a preferred embodiment of the present invention, the temperature difference is controlled within a range of 1°C to 4°C.

[0020] In a preferred embodiment of the present invention, the combined compressor couples the cycle gas compression and the green synthesis gas compression produced by biomass gasification.

[0021] In a preferred embodiment of the present invention, CO and H2, CO2, sulfuric acid gas and light oil in the synthesis gas are recovered and utilized in sequence, wherein effective gases such as CO and H2 are recovered in a flash evaporation system, CO2 products are recovered in a desorption system, sulfuric acid gas is recovered in a regeneration system, and light oil is recovered in a light oil recovery system, thereby maximizing the utilization of resources.

[0022] In a preferred embodiment of the present invention, the absorption system adopts a multi-stage design, including a desulfurization section and a deoiling section. In the desulfurization section, lean methanol from the regeneration system washes H2S and COS in the pre-cooled synthesis gas to form sulfur-containing methanol, which is sent to the flash evaporation system after cooling and decompression; the desulfurized gas leaves the desulfurization section and is reheated as purified gas and then sent out of the boundary; a part of the sulfur-containing methanol from the desulfurization section washes the light oil component to form pre-wash methanol, which enters the light oil recovery system.

[0023] In a preferred embodiment of the present invention, the absorption system further comprises a decarbonization stage. This stage uses lean methanol from the regeneration system as an absorbent to absorb CO2 from the desulfurized gas. The desulfurized gas is then withdrawn and cooled between stages to produce sulfur-free methanol. The sulfur-free methanol is cooled and depressurized before being transferred to a flash evaporation system. The decarbonized gas is then reheated as purified gas and discharged.

[0024] In a preferred embodiment of the present invention, a bypass adjustment is set in the decarbonization section in the absorption system, and the content of CO2 in the purified gas is adjusted by controlling the amount of methanol, temperature and other process parameters, so as to maximize the adaptation to the decarbonization needs of subsequent sections and meet the carbon emission requirements of the entire plant under different working conditions.

[0025] In a preferred embodiment of the present invention, the stripping gas is nitrogen.

[0026] The working principle of this utility model is as follows: The green syngas purification process is a typical physical absorption method, utilizing methanol's high solubility for acidic gases at low temperatures to remove acidic gases from the feed gas. Due to the high vapor pressure of methanol, the green syngas purification process is often operated at low temperatures (-35°C to -60°C). At low temperatures, the solubility of CO2, H2S, and light oil increases significantly with decreasing temperature, thus requiring less solvent and requiring smaller equipment. Furthermore, the solubility of CO2, H2S, and light oil in methanol varies significantly at different temperatures, enabling the selective removal of related impurities.

[0027] The technical advantages of this utility model are as follows:

[0028] 1. This utility model adopts an integrated purification treatment and recovery solution for the synthesis gas produced by biomass gasification, which mainly includes an absorption system, a flash evaporation system, a desorption system, a regeneration system and a light oil recovery system.

[0029] 2. The utility model adopts a multi-stage absorption system design, including a deoiling section, a desulfurization section and a decarbonization section, to purify various impurities in the synthesis gas produced from biomass in stages.

[0030] 3. The decarbonization section in the absorption system involved in the present invention is provided with a bypass adjustment, and at the same time, the process parameters such as the amount of methanol and temperature are controlled to adjust the content of CO2 in the purified gas, thereby maximizing the adaptation to the decarbonization needs of subsequent sections and meeting the carbon emission requirements of the entire plant under different working conditions.

[0031] 4. The utility model is equipped with a flash evaporation system, a desorption system, a regeneration system and a light oil recovery system to sequentially recover and utilize CO and H2, CO2, sulfuric acid gas and light oil, wherein effective gases such as CO and H2 are recovered in the flash evaporation system, CO2 products are recovered in the desorption system, sulfuric acid gas is recovered in the regeneration system, and light oil is recovered in the light oil recovery system, thereby maximizing the utilization of resources.

[0032] 5. In view of the low pressure of the green synthesis gas at the current biomass gasification outlet, biomass gasification often needs to be equipped with a compressor before it can be sent to the purification device. The utility model optimizes the design of the flash evaporation system, couples the circulating gas compression of the flash evaporation system with the green synthesis gas compression of the biomass gasification, simplifies the process flow, and reduces the investment in the device.

[0033] 6. The inlet heat exchanger adopts split-flow heat exchange and temperature difference control, which makes the temperature of the crude synthesis gas entering the absorption system more stable. Compared with a single heat exchanger, it adds a means of adjusting the inlet temperature and makes the utilization of cold energy more reasonable.

[0034] 7. The utility model can optimize the design of the multi-stage absorption system, delete the decarbonization stage, and maximize the recovery of CO2 in the synthesis gas while meeting the purification indicators such as deoiling and desulfurization. It is particularly suitable for the subsequent synthesis unit to produce green methanol by hydrogenation of high CO2. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 This is a structural schematic diagram of the green synthesis gas purification and treatment device of Example 1 of the present utility model.

[0036] Figure 2 This is a structural schematic diagram of the green synthesis gas purification and treatment device of Example 2 of the present utility model. DETAILED DESCRIPTION

[0037] The present invention is further described below with reference to the accompanying drawings and specific embodiments.

[0038] Example 1

[0039] See also Figure 1 The green methanol synthesis gas purification and processing device shown in the figure includes a combined compressor 100, an inlet heat exchanger 200, an absorption system 300, a flash evaporation system 400, a desorption system 500, a regeneration system 600, and a light oil recovery system 700.

[0040] The combined compressor 100 couples the cycle gas compression and the green synthesis gas compression produced by biomass gasification, and has a raw synthesis gas inlet 110, a cycle gas inlet 120 and a compressed synthesis gas outlet 130. The raw synthesis gas enters the combined compressor 100 through the raw synthesis gas inlet 110 and is compressed in the combined compressor 100 to form compressed synthesis gas, which is then sent out from the compressed synthesis gas outlet 130.

[0041] The inlet heat exchanger 200 adopts split-flow heat exchange, that is, a portion of the hot raw synthesis gas is exchanged with the cold tail gas, and the remaining portion of the hot raw synthesis gas is exchanged with the cold purified gas, and temperature difference control is adopted. The temperature difference is controlled within 1°C to 4°C.

[0042] The inlet heat exchanger 200 has a compressed synthesis gas inlet 210 and a pre-cooling synthesis gas outlet 220. The compressed synthesis gas sent from the compressed synthesis gas outlet 130 of the combined compressor 100 enters the inlet heat exchanger 200 through the compressed synthesis gas inlet 210 for pre-cooling, forming pre-cooled synthesis gas and sent out from the pre-cooling synthesis gas outlet 220.

[0043] The absorption system 300 adopts a two-stage design, including a desulfurization section 370 and a deoiling section 380. In the desulfurization section 370, the lean methanol from the regeneration system 600 washes the H2S and COS in the pre-cooled synthesis gas to form sulfur-containing methanol, which is sent to the flash evaporation system 400 after cooling and decompression; the desulfurized gas leaves the desulfurization section 380 and is reheated as purified gas and then sent out of the boundary; a part of the sulfur-containing methanol from the desulfurization section 370 washes the light oil component to form pre-wash methanol, which enters the light oil recovery system 700.

[0044] The absorption system 300 has a pre-cooling synthesis gas inlet 310, a pre-washing methanol outlet 320, a purified gas outlet 330, a sulfur-containing methanol outlet 340, a sulfur-free methanol outlet 350 and a lean methanol inlet 360; the pre-cooling synthesis gas inlet 310 is connected to the pre-cooling synthesis gas outlet 220, and the pre-cooling synthesis gas coming out of the pre-cooling synthesis gas outlet 220 of the inlet heat exchanger 200 enters the absorption system 300 through the pre-cooling synthesis gas inlet 310 of the absorption system 300 for absorption; the pre-washing methanol formed in the absorption system 300 is sent out from the pre-washing methanol outlet 320, the purified gas formed is sent out from the purified gas outlet 330, the sulfur-containing methanol formed is sent out from the sulfur-containing methanol outlet 340, and the sulfur-free methanol formed is sent out from the sulfur-free methanol outlet 350.

[0045] The flash evaporation system 400 has a sulfur-containing methanol inlet 410, a sulfur-free methanol inlet 420, a circulating gas outlet 430 and a methanol outlet 440. The sulfur-containing methanol inlet 420 is connected to the sulfur-containing methanol outlet 350, and receives the sulfur-containing methanol from the absorption system 300 for flash evaporation to form circulating gas. The circulating gas outlet 330 is connected to the circulating gas inlet 120. The circulating gas after flash evaporation is sent to the combined compressor 100 from the circulating gas outlet 330 and the circulating gas inlet 120 to be compressed, cooled and then returned to the raw gas.

[0046] The desorption system 500 has a methanol inlet 510, a sulfur-rich methanol outlet 520, an exhaust gas outlet 530, a stripping gas inlet 540, and an H2S reflux inlet 550. The methanol inlet 510 is connected to the methanol outlet 440. The methanol from the flash evaporation system 400 enters the desorption system 500 and is stripped by the stripping gas (the stripping gas is nitrogen) entering from the stripping gas inlet 540. The exhaust gas after stripping is sent out from the exhaust gas outlet 530; the sulfur-rich methanol after stripping is sent out from the sulfur-rich methanol outlet 520.

[0047] The regeneration system 600 has a sulfur-rich methanol inlet 610, a lean methanol outlet 620, an acid gas outlet 630, a methanol replenishment inlet 640, a wastewater discharge port 650, a methanol aqueous solution inlet 660, and an H2S reflux outlet 670. The sulfur-rich methanol inlet 610 is connected to the sulfur-rich methanol outlet 520. The sulfur-rich methanol desorbed by the desorption system 500 is sent to the regeneration system for regeneration. The lean methanol outlet 620 is connected to the lean methanol inlet 360. The regenerated lean methanol is sent to the absorption system 300. A portion of the regenerated acid gas enters the desorption system 500 through the H2S reflux outlet 670 and the H2S reflux inlet 550 to increase the H2S concentration, and a portion is discharged through the acid gas outlet 630. Wastewater is discharged through the wastewater discharge port 650, and methanol required for replenishment during the regeneration process is replenished through the methanol replenishment inlet 640.

[0048] The light oil recovery system 700 has a light oil outlet 710, a pre-wash methanol inlet 720 and a methanol aqueous solution outlet 720. The pre-wash methanol inlet 720 is connected to the pre-wash methanol outlet 320, and the methanol aqueous solution outlet 720 is connected to the methanol aqueous solution inlet 660. The pre-wash methanol enters the light oil recovery system 700 for oil removal to form a methanol aqueous solution and is sent to the regeneration system 600, and the oil is sent out from the light oil outlet 710.

[0049] For the synthesis of green methanol, purified gas with high CO2 concentration (2% to 40%) can be used as synthesis gas, so the absorption system 300 is simplified to a two-stage design, namely the deoiling section 360 and the desulfurization section 370.

[0050] The raw syngas at the outlet of biomass gasification is compressed into compressed syngas by the combined compressor 100 and then enters the inlet heat exchanger 200 for precooling. After precooling, it enters the absorption system 300 (-12°C to -26°C). The inlet heat exchanger 200 uses split-flow heat exchange, that is, a part of the hot raw syngas at the outlet of biomass gasification exchanges heat with the cold tail gas, and the remaining part of the hot raw syngas at the outlet of biomass gasification exchanges heat with the cold purified gas, and uses temperature difference control. The temperature difference can be controlled within (|ΔT| = 1°C to 4°C), making the temperature of the compressed syngas entering the absorption system 300 more stable and making the utilization of cold energy more sufficient.

[0051] In the absorption system 300, a part of the sulfur-containing methanol from the desulfurization section 370 (that is, the H2S absorption section) is washed with light oil components in the deoiling section 360 to form prewashed methanol. The prewashed methanol enters the light oil recovery system 700 through the prewashed methanol outlet 320.

[0052] In the desulfurization section 370 (that is, the H2S absorption section), the methanol received from the regeneration system 600 through the lean methanol inlet 360 is used to wash H2S and COS in the compressed syngas to form sulfur-containing methanol. The sulfur-containing methanol is sent to the flash system 400 through the sulfur-containing methanol outlet 340 after being cooled and depressurized; the desulfurized gas leaves the desulfurization section 370 (that is, the H2S absorption section) and is sent out of the boundary as purified gas after reheating (2.5 - 6.0 MpaG, 30°C) through the purified gas outlet 330.

[0053] In the flash system 400, the sulfur-containing methanol is flashed, and the dissolved H2, CO and part of CO2 are flashed out together. This flash gas is compressed and cooled in the combined compressor 200 and then returned to the compressed syngas to realize the recovery of effective gas and reduce the loss of effective gas. This combined compressor 200 couples the compression of recycle gas and the compression of green syngas produced by biomass gasification. The recycle gas (0.8 - 1.0 MpaG) at the recycle gas outlet 420 of the flash system 400 enters the combined compressor 200 from the interstage of the combined compressor 200.

[0054] The methanol after flashing enters the desorption system 500 through the methanol outlet 430 of the flash system 400 after being depressurized. The H2S concentrator in the desorption system 500 flashes out CO2 gas, and N2 is used to strip CO2 to make CO2 enter the tail gas and is sent out of the boundary area through the tail gas outlet 530 after reheating (0.025 - 0.03 MpaG, 30°C). The sulfur-rich methanol after H2S enrichment enters the regeneration system 600 through the sulfur-rich methanol outlet 520 to regenerate the methanol.

[0055] In regeneration system 600, sulfur-rich methanol first desorbs H2S in the thermal regeneration tower of regeneration system 600. The overhead gas phase is cooled, then flows through an H2S concentration line and refluxes to desorption system 500 via H2S reflux outlet 670, thereby increasing the concentration of acid gas at outlet 630 (H2S concentration > 25%). The lean methanol from the regenerated bottom of the tower is cooled and then enters absorption system 300 via lean methanol outlet 620 as an absorption medium. To ensure the quality of the lean methanol, a portion of the methanol in the bottom of the tower enters a methanol water tower for methanol and water separation. Wastewater (methanol concentration < 0.01 wt%) is discharged from the bottom of the methanol water tower, and the purified lean methanol gas is refluxed to the thermal regeneration tower, increasing the methanol concentration in the lean methanol in the bottom of the tower.

[0056] In the light oil recovery system 700, pre-wash methanol (i.e., oil-containing methanol) from the de-oiling section 360 and entering through the pre-wash methanol outlet 320 flashes in the extraction tank of the light oil recovery system 700 to remove the effective gas. Desalted water is then used to extract methanol from the pre-wash methanol (i.e., oil-containing methanol) into an aqueous phase. This aqueous methanol phase then enters an azeotropic column to completely separate the methanol-water solution from the light oil. The methanol-water solution then enters the methanol-water column of the regeneration system 600 through the methanol-water outlet 730 for methanol separation. The oil phase in the extraction tank is discharged out of the delimited area through the light oil outlet 710.

[0057] Example 2

[0058] See also Figure 2 The green aviation fuel synthesis gas purification and treatment device shown in the figure has a structure basically the same as that of Example 1, and also includes a combined compressor 100, an inlet heat exchanger 200, an absorption system 300, a flash evaporation system 400, a desorption system 500, a regeneration system 600, and a light oil recovery system 700.

[0059] However, for the synthesis of green aviation fuel, the carbon dioxide in the synthesis gas needs to be completely removed. Therefore, the absorption system 300 of this embodiment is different from the absorption system 300 of Example 1 and is configured as a three-stage design, namely a deoiling section 370, a desulfurization section 380, and a decarbonization section 390.

[0060] Decarbonization stage 390 uses lean methanol from regeneration system 600 as an absorbent to absorb CO2 from the desulfurized gas. The desulfurized gas is then withdrawn and cooled between stages to produce sulfur-free methanol. After cooling and decompression, the sulfur-free methanol is sent to flash evaporation system 400. The decarbonized gas is reheated as purified gas and then discharged.

[0061] The decarbonization section 390 in the absorption system 300 features a bypass regulator. By controlling process parameters such as the methanol dosage and temperature, the CO2 content in the purified gas is adjusted to maximize the decarbonization needs of subsequent stages and meet overall plant carbon emission requirements under varying operating conditions. The purified gas CO2 concentration can be adjusted from 20 ppm to 0.1%, meeting the needs of various green aviation fuel synthesis gas production processes.

[0062] The raw syngas at the outlet of biomass gasification is compressed into compressed syngas by the combined compressor 100 and enters the inlet heat exchanger 200 for precooling. After precooling, it enters the absorption system 300 (-12°C to -26°C). The inlet heat exchanger 200 uses split-flow heat exchange, that is, a part of the hot raw syngas at the outlet of biomass gasification exchanges heat with the cold tail gas, and the remaining part of the hot raw syngas at the outlet of biomass gasification exchanges heat with the cold purified gas, and uses temperature difference control, and the temperature difference can be controlled within (|ΔT| = 1°C to 4°C), making the temperature of the compressed syngas entering the absorption system 300 more stable and making the utilization of cold energy more sufficient.

[0063] In the absorption system 300, a part of the sulfur-containing methanol from the desulfurization section 380 (that is, the H2S absorption section) is washed with light oil components in the deoiling section 370 to form prewashed methanol, and the prewashed methanol enters the light oil recovery system 700 through the prewashed methanol outlet 320.

[0064] In the desulfurization section 380 (that is, the H2S absorption section), the methanol received from the regeneration system 600 through the lean methanol inlet 360 is used to wash H2S and COS in the compressed syngas to form sulfur-containing methanol. The sulfur-containing methanol is sent to the flash system 400 through the methanol outlet 340 after cooling and pressure reduction.

[0065] The desulfurized gas leaves the desulfurization section 370 (that is, the H2S absorption section) and enters the decarbonization section 390. The decarbonization section 390 uses the lean methanol from the regeneration system 600 as the absorbent to absorb CO2 in the desulfurized gas, and is cooled by inter-stage extraction to form sulfur-free methanol. The sulfur-free methanol is sent to the flash system 400 through the methanol outlet 340 after cooling and pressure reduction. The decarbonized gas is reheated as purified gas (2.5 to 6.0 MpaG, 30°C) and sent out of the boundary through the purified gas outlet 330.

[0066] In the flash system 400, the sulfur-containing methanol is flashed, and the dissolved H2, CO and part of CO2 are flashed out together. This flash gas is compressed and cooled in the combined compressor 100 and then returned to the compressed syngas to realize the recovery of effective gas and reduce the loss of effective gas. This combined compressor 100 couples the compression of recycle gas and the compression of green syngas produced by biomass gasification. The recycle gas (0.8 to 1.0 MpaG) at the recycle gas outlet 420 of the flash system 400 enters the combined compressor 200 from the inter-stage of the combined compressor 100.

[0067] After flashing, the sulfur-free methanol is depressurized and enters the desorption system 500 through the methanol outlet 430 of the flash evaporation system 400. A relatively pure CO2 product gas with a CO2 concentration of 96% to 99.5% is flashed out at the top of the CO2 product column of the desorption system 500. The flashed methanol then flashes out CO2 gas (0.17-0.2 MPaG, 30°C) in the H2S concentration column. This CO2 is then stripped with N2, entering the tail gas. After reheating, the CO2 is delivered to the decompression zone (0.025-0.03 MPaG, 30°C) through the tail gas outlet 530 or directly discharged through the CO2 outlet 540 of the desorption system 500. The sulfur-rich methanol, enriched with H2S, enters the regeneration system 600 through the sulfur-rich methanol outlet 520 for methanol regeneration.

[0068] In regeneration system 600, sulfur-rich methanol first desorbs H2S in the thermal regeneration tower of regeneration system 600. The overhead gas phase is cooled, then flows through an H2S concentration line and refluxes to desorption system 500 via H2S reflux outlet 670, thereby increasing the concentration of acid gas at outlet 630 (H2S concentration > 25%). The lean methanol from the regenerated bottom of the tower is cooled and then enters absorption system 300 via lean methanol outlet 620 as an absorption medium. To ensure the quality of the lean methanol, a portion of the methanol in the bottom of the tower enters a methanol water tower for methanol and water separation. Wastewater (methanol concentration < 0.01 wt%) is discharged from the bottom of the methanol water tower, and the purified lean methanol gas is refluxed to the thermal regeneration tower, increasing the methanol concentration in the lean methanol in the bottom of the tower.

[0069] In the light oil recovery system 700, pre-wash methanol (i.e., oil-containing methanol) from the de-oiling section 360 and entering through the pre-wash methanol outlet 320 flashes in the extraction tank of the light oil recovery system 700 to remove the effective gas. Desalted water is then used to extract methanol from the pre-wash methanol (i.e., oil-containing methanol) into an aqueous phase. This aqueous methanol phase then enters an azeotropic column to completely separate the methanol-water solution from the light oil. The methanol-water solution then enters the methanol-water column of the regeneration system 600 through the methanol-water outlet 730 for methanol separation. The oil phase in the extraction tank is discharged out of the delimited area through the light oil outlet 710.

[0070] The raw synthesis gas containing CO2, acid gas and light oil components is treated by the green synthesis gas purification method and device, and the components that are not conducive to synthesis are removed, and the CO2 gas, acid gas and light oil are effectively recovered, making the recycling of resources more reasonable.

Claims

1. A new type of green synthesis gas purification and treatment device, characterized in that: include: a combined compressor having a raw synthesis gas inlet, a recycle gas inlet, and a compressed synthesis gas outlet, wherein the raw synthesis gas enters the combined compressor through the raw synthesis gas inlet, is compressed in the combined compressor to form compressed synthesis gas, and is delivered through the compressed synthesis gas outlet; an inlet heat exchanger having a compressed syngas inlet and a pre-cooled syngas outlet, wherein the compressed syngas delivered from the compressed syngas outlet of the combined compressor enters the inlet heat exchanger through the compressed syngas inlet for pre-cooling, and forms pre-cooled syngas which is delivered from the pre-cooled syngas outlet; an absorption system, the absorption system comprising a precooling synthesis gas inlet, a prewashing methanol outlet, a purified gas outlet, a sulfur-containing methanol outlet, a sulfur-free methanol outlet, and a lean methanol inlet; the precooling synthesis gas inlet is connected to the precooling synthesis gas outlet, and the precooling synthesis gas discharged from the precooling synthesis gas outlet of the inlet heat exchanger enters the absorption system through the precooling synthesis gas inlet of the absorption system for absorption; the prewashing methanol formed by the absorption system is delivered through the prewashing methanol outlet, the purified gas formed by the absorption system is delivered through the purified gas outlet, the sulfur-containing methanol formed by the absorption system is delivered through the sulfur-containing methanol outlet, and the sulfur-free methanol formed by the absorption system is delivered through the sulfur-free methanol outlet; a flash evaporation system; the flash evaporation system has a sulfur-containing methanol inlet, a sulfur-free methanol inlet, a recycle gas outlet, and a methanol outlet; the sulfur-containing methanol inlet is connected to the sulfur-containing methanol outlet, receives the sulfur-containing methanol from the absorption system for flash evaporation to form recycle gas; the recycle gas outlet is connected to the recycle gas inlet; the recycle gas after flash evaporation is sent from the recycle gas outlet and the recycle gas inlet to a combined compressor for compression, cooling, and then returning to the feed gas; a desorption system having a methanol inlet, a sulfur-rich methanol outlet, a tail gas outlet, a stripping gas inlet, and an H2S reflux inlet, wherein the methanol inlet is connected to the methanol outlet, the methanol from the flash evaporation system enters the desorption system and is stripped by the stripping gas entering the stripping gas inlet, and the stripped tail gas is sent out through the tail gas outlet; and the stripped sulfur-rich methanol is sent out through the sulfur-rich methanol outlet; a regeneration system comprising a sulfur-rich methanol inlet, a lean methanol outlet, an acid gas outlet, a methanol replenishment inlet, a wastewater discharge outlet, a methanol aqueous solution inlet, and an H2S reflux outlet, wherein the sulfur-rich methanol inlet is connected to the sulfur-rich methanol outlet, the sulfur-rich methanol desorbed by the desorption system is fed into the regeneration system for regeneration, the lean methanol outlet is connected to the lean methanol inlet, and the regenerated lean methanol is fed into the absorption system; a portion of the regenerated acid gas enters the desorption system through the H2S reflux outlet and the H2S reflux inlet to increase the H2S concentration, and a portion is discharged through the acid gas outlet; wastewater is discharged through the wastewater discharge outlet, and methanol required to be replenished during the regeneration process is replenished through the methanol replenishment inlet; A light oil recovery system, the light oil recovery system has a light oil outlet, a pre-wash methanol inlet and a methanol-water solution outlet, the pre-wash methanol inlet is connected to the pre-wash methanol outlet, the methanol-water solution outlet is connected to the methanol-water solution inlet, the pre-wash methanol enters the light oil recovery system for oil removal to form the methanol-water solution, which is then sent to the regeneration system, and the oil is sent out from the light oil outlet.

2. A novel green synthesis gas purification and treatment device according to claim 1, characterized in that: The inlet heat exchanger adopts split-flow heat exchange, that is, a part of the hot raw synthesis gas is heat exchanged with the cold tail gas, and the remaining part of the hot raw synthesis gas is heat exchanged with the cold purified gas, and temperature difference control is adopted.

3. A novel green synthesis gas purification and treatment device according to claim 1, characterized in that: The temperature difference is controlled at 1°C to 4°C.

4. A novel green synthesis gas purification and treatment device according to claim 1, characterized in that: The combined compressor couples the compression of circulating gas and the compression of green synthesis gas produced by biomass gasification.

5. A novel green synthesis gas purification and treatment device according to any one of claims 1 to 4, characterized in that: The CO and H2, CO2, sulfuric acid gas and light oil in the synthesis gas are recovered and utilized in sequence, among which effective gases such as CO and H2 are recovered in the flash evaporation system, CO2 products are recovered in the desorption system, sulfuric acid gas is recovered in the regeneration system, and light oil is recovered in the light oil recovery system, thereby maximizing the utilization of resources.

6. A novel green synthesis gas purification and treatment device according to claim 5, characterized in that: The absorption system adopts a multi-stage design, including a desulfurization section and a deoiling section. In the desulfurization section, lean methanol from the regeneration system washes H2S and COS in the pre-cooled synthesis gas to form sulfur-containing methanol, which is sent to the flash evaporation system after cooling and decompression; the desulfurized gas leaves the desulfurization section, is reheated as purified gas, and is sent out of the boundary; a portion of the sulfur-containing methanol from the desulfurization section washes the light oil component to form pre-wash methanol, which enters the light oil recovery system.

7. A novel green synthesis gas purification and treatment device according to claim 6, characterized in that: The absorption system also includes a decarbonization stage, which uses lean methanol from the regeneration system as an absorbent to absorb CO2 from the desulfurized gas. The desulfurized methanol is then withdrawn and cooled between stages to produce sulfur-free methanol. After cooling and decompression, the sulfur-free methanol is fed to a flash evaporation system, where the decarbonized gas is reheated as purified gas and then discharged.

8. A novel green synthesis gas purification and treatment device according to claim 7, characterized in that: The decarbonization section in the absorption system is provided with a bypass adjustment. At the same time, the CO2 content in the purified gas is adjusted by controlling the amount of methanol, temperature and other process parameters, so as to maximize the adaptation to the decarbonization needs of subsequent sections and meet the carbon emission requirements of the entire plant under different working conditions.

9. A novel green synthesis gas purification and treatment device according to claim 8, characterized in that: The stripping gas is nitrogen.

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