On CO2 emissions from vented gas
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During the methanol synthesis process, off-gases are generated; the H2 in these off-gases can be recovered, and the CO can be burned. But what about CO2?
CO2 can be purified and supplied to Coca-Cola Company or used to produce ethylene oxide and other products
The vent gas contains only a small amount of gas; if some hydrogen is recovered using membrane separation, the remaining gases are vented or burned. If methanol is produced from natural gas, after purifying hydrogen using pressure swing adsorption, carbon-rich gas (mainly CO, CO2, CH4, and some hydrogen) can also be recovered and fed into the conversion process to increase alcohol production.
The CO2 content in the synthetic off-gas is already very low (except in abnormal cases); after the off-gas has had its hydrogen-rich fraction recovered through membrane separation or pressure swing adsorption, it can be directly sent to the combustion air for use
In fact, it ends up in the atmosphere, where it needs to be converted into organic matter through photosynthesis
How can it go back and react again? Isn’t venting gas meant to release inert gases? If it goes back, there’s no need for venting gas anymore
During re-synthesis, it can be added to the coke oven gas compressor as a carbon source, thus making full use of energy
If pressure swing adsorption is used to recover hydrogen, the carbon-rich gas generated can be used as a carbon source to increase methanol production; we plan to install such a pressure swing adsorption hydrogen recovery unit
If hydrogen is produced by pressure swing adsorption, it is advisable to install a small storage tank after the exhaust gas; otherwise, the pressure fluctuations will be too large. This is true in the case of membrane separation as well. The pressure remains stable; this material is usually sent to the purge gas system or burned in the waste treatment furnace.