What causes the excessive H2 level in CO2 during purification?
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What causes the excessive H2 level in CO2 during purification?
This is likely due to a high pressure in the medium-pressure flash, resulting in incomplete vaporization of the effective gas. However, the medium-pressure flash pressure is too low, which results in more carbon dioxide being flashed out, and the energy consumption required to pressurize the recycle gas also increases.
Try to reduce the temperature of the methanol-rich stream before it reaches the flash tank; at the same pressure, the lower the temperature, the less CO2 will flash off. Therefore, it is possible to appropriately reduce the flash pressure at low temperatures.
My suggestions: 1) The pressure set for the medium-pressure flash tower is too high; 2) There is a leak in the heat exchanger that handles the CO2 stream and the syngas stream – please check this. But overall, it still seems that the former option is a bit more likely.
You can also check whether the circulation volume is too high
The pressure in the medium-pressure flashing section is too high. Additionally, the temperature in the CO2 separation section also has some impact