I heard that CO2 in syngas can also be used to control the pressure of the synthesis system?
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When there is more CO2, the pressure decreases； If there is less CO2, will the pressure increase? I’ve heard this claim for the first time; I hope experts in synthesis can explain it. That textbook never mentioned such a thing during the theoretical training. I just can’t figure it out!
In the case of methanol production from natural gas with externally supplied CO2, this is a possibility; an increase in the amount of externally supplied CO2 means that the hydrogen-to-carbon ratio may become more suitable. At the same synthetic purge gas flow rate, the synthesized pressure decreases.
We produce methanol through gasification here! Purified using low-temperature methanol washing!
CO reacts with 2 H2 to produce one CH3OH; the volume after the reaction is equivalent to 1/3 of the volume before the reaction； CO2 reacts with 3 molecules of H2 to produce one molecule of CH3OH and one molecule of H2O. The water vapor is condensed into water in the methanol cooler. Therefore, the volume after the reaction is equivalent to 1/4 of the volume before the reaction; hence, the volume decreases. This is how I understand it. For reference only!
The principle is as mentioned above; the operating temperature can also be controlled by the hydrogen-to-carbon ratio, that is, the bed temperature is controlled by regulating the flow rates of the purge gas and the recycle gas.
Let’s discuss how the pressure in the entire system is controlled Is it by using CO2 to control it?
I agree with what the two people above said. However, the amount of CO2 generally doesn’t fluctuate much. Besides, having too much CO2 is a waste when it comes to H2! !
There should be a relationship. Observations show that when the hydrogen level is high, the compressor inlet pressure increases. The synthesis process can only raise the pressure by reducing the amount of purge gas released. Perhaps there’s also some relation to the compression ratio of the converted gas!
The gas composition has a certain effect on the synthesis pressure; however, the main factor determining the amount of purge gas is the accumulation of inert gases in the gas mixture that do not participate in the reaction. The effect of CO2 on the pressure is not significant. . .