Detailed description of the low-temperature shift process in coal-to-methanol production; it would be better to have a process flow diagram

I don’t know what the difference is between saturated towers; does the original poster know anything about it? I’d like to take a look :)

The last edit to this post was made by 654262293 on 2016-6-10 at 13:14. In the production of methanol using a fixed-bed batch gas generation process, usually just one stage of shift reaction is sufficient to meet the process requirements; therefore, a single low-temperature shift stage is adequate, and there is no need for a medium-temperature shift stage. Specific process description: The water-gas from the third stage of the compressor passes through a vapor-water separator and an oil remover to remove the oil and water contained in the water-gas. Then, indirect heat exchange occurs through the tube side of the preheating exchanger and the tube side of the main heat exchanger with the shifted gas, raising the temperature of the water gas to over 210°C before it enters the first catalyst layer of the shift reactor to remove the small amount of O2 contained in the water gas. The water gas produced in the first catalyst stage is mixed with steam and then fed into a humidifier, where it is humidified by water spray and cooled to 220–230°C. It subsequently enters the second catalyst layer for the shift reaction. The gas exiting this stage undergoes indirect heat exchange with the water gas in the shell side of the main heat exchanger, thereby being cooled to 170±5°C before entering a medium-temperature hydrolysis furnace, where a small amount of organic sulfur is converted into H2S. The shift gas produced by the medium-temperature hydrolysis furnace enters the shell side of the preheating exchanger, where it exchanges heat indirectly with water gas. It then goes to the tube side of the desalinated water heater, where it exchanges heat indirectly with the desalinated water coming from the reverse osmosis process. After that, it enters the tube side of the shift gas cooler, where it exchanges heat indirectly with the circulating water from the synthesis cycle water system, thereby being cooled to 30±5°C before being sent to the shift gas desulfurization process.

Description of the sulfur-resistant shift process for gas production using water-coal slurry: The water gas generated by gasification [at 6.15 MPa, 239°C, with a vapor-to-gas (dry) ratio of approximately 1.40 and a CO content of about 50.65% (on a dry basis)] enters the first medium-pressure waste heat boiler (E2001). There, it exchanges heat with the boiler feedwater and is cooled; after that, the condensed liquid is removed via the first water separator (V2001), and the resulting stream is divided into three branches. One branch is heated to 265°C using a medium-temperature heat exchanger before entering the methanol shift reactor (R2001), where the catalyst is installed in the first section. The second branch serves as quenching gas and enters the space between the two sections of the reactor. The shift gas, with a CO content of 5.4% (on a dry basis) and a temperature of around 450°C, enters the steam superheater (E2003), where it exchanges heat with the mixed steam generated by the first medium-pressure waste heat boiler and that coming from the methanol synthesis unit. After that, it enters the medium-temperature heat exchanger (E2002), where it exchanges heat with water-gas to cool down; subsequently, it mixes with the third stream of water-gas and enters the first low-pressure waste heat boiler (E2004), where it further exchanges heat with the boiler feedwater. The temperature of the shift gas drops to 201°C. By adjusting the flow rate of the third stream of water-gas, the CO content in the shift gas exiting the washing tower (T2001) is brought to 20% (on a dry basis). The shift gas exiting the first low-pressure waste heat boiler exchanges heat with the boiler feedwater in E2005A and E2005B, before entering the second low-pressure waste heat boiler (E2006) to exchange heat with the boiler feedwater and thereby cool down. After the condensate is separated in the second water separator (V2002), it proceeds to the desalinated water heater (E2007) and the shift gas water cooler (E2008), where it exchanges heat with the desalinated water and circulating water from the pipeline systems respectively. Once its temperature drops to 40°C, it enters the wash tower (T2001), where ammonia in the shift gas is removed using sealed water, after which it is sent to the low-temperature methanol washing section.

Process description of sulfur-resistant shift using the powder coal gasification process: The raw gas coming from the gasification unit (168°C, 3.8 MPa(a), 183.904 kNm3/h) first enters the feed gas separator S-15101 to remove any water contained in it, and then goes into the feed gas filter S-15102 to eliminate solid mechanical impurities. The raw gas coming out of the raw gas filter S-15102 is divided into three streams: one stream (about 35%, 64.552 kNm3/h) enters the tube side and shell side of the gas preheater E-15101, where it exchanges heat with the reformate gas from the third reformer to reach a temperature of 210°C. It then goes into the steam mixer S-15103, where it mixes with steam at 263°C; the resulting gas (at a temperature of about 230°C) subsequently enters the tube side and shell side of the gas exchanger E-15102, where it exchanges heat with the reformate gas from the first reformer to reach a temperature of 260°C, after which it enters the first reformer R-15101 for further reforming. The shift gas coming out of the first shift reactor (at a temperature of about 459°C) enters the shell side of the gas heat exchanger E-15102. After exchanging heat with the gas on the tube side (at a temperature of about 432°C), it mixes with another stream of raw gas coming from S-15102 – a stream containing 30% of the total gas flow, at a rate of 55.171 kNm3/h, and serving as a cooling agent for the high-temperature shift gas. This mixture then enters the No. 1 quench filter S-15104, where the gas is cooled to around 235°C by the shift condensate at 101.8°C, which comes from the condensate pump P15101. Finally, the gas proceeds to the second shift reactor R-15102 for the shift reaction. The gas exiting the second shift converter (at a temperature of about 345°C) is mixed with the remaining 35% of the gas in the raw gas (the third stream of raw gas from S-15102, at around 64.552 kNm3/h), and then enters the No. 2 quenching filter S-15105. There, the gas is cooled and humidified to 220°C by the shift condensate at 101.8°C coming from P15101, after which it enters the third shift converter R-15103 to undergo the shift reaction. The shift gas coming out of the third shift reactor R-15103 (at a temperature of about 304.9°C) enters the tube side of the gas preheater E-15101, where it is cooled by the gas flowing in the shell side to 293.7°C. It then enters the tube and shell sides of the boiler feedwater preheaters E-15103A/B, where it exchanges heat with the boiler feedwater; after its temperature drops to 180°C, it enters the demineralized water preheaters E-15104A/B, where it exchanges heat with the demineralized water flowing in the shell side until its temperature reaches 85°C. After that, it goes into the No. 1 shift gas separator S-15106 to have any condensed water separated from it, and then enters the shift gas water cooler E-15105, where it is cooled by the circulating water in the shell side to 40°C. Finally, it enters the No. 2 shift gas separator S-15108 to have any remaining condensed water removed, before being sent to the low-temperature methanol washing unit.