Gas composition at the bottom of the thermal regeneration tower
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In the Ruchi process, the reboiler at the bottom of the thermal regeneration tower heats a mixture of water and methanol; the gas produced is referred to as methnol vapor by foreigners. Should it be called methanol vapor instead? Is it still called methanol vapor? I think the gas must contain water; it should be called methanol vapor. Do anyone have any opinions? 【Just enlarging the font helps protect your eyes!】 】 This post was last edited by z880347730 on 2009-3-25 21:40 ]
It should be called methanol vapor. If it is called methanol vapor, then the water content in the lean methanol pump will definitely exceed the limit.
It should be called methanol vapor, because it is a mixture of methanol and water!
Either one will work, but under normal conditions it is basically pure methanol gas; since water is a heavier phase compared to methanol, it comes out from the bottom of the tower, with only a very small amount of water vapor at the top.
I think it’s called methanol vapor; the methanol concentration at the bottom of the thermal regeneration tower in our plant is 99.46%, with a relatively low water content.
Let’s first take a look at our material data: in the gas phase at the outlet of the reboiler, methanol constitutes 99.87% (w), while water accounts for 0.12% (w). At this point, the pressure of the liquid at the bottom of the tower is 0.335 MPa (a), corresponding to a boiling point of 98.513°C. The saturated vapor pressure of pure methanol at the same temperature (98.5°C) is 0.236 MPa (g). It can be seen that the saturated vapor pressure of the mixture at the bottom of the tower differs from that of pure methanol at the same temperature by only about 3 KPa. So based on this data, it should be called vapor. But there is one more thing that people overlook: the so-called gas phase is not actually a true gas phase; it should be called a vapor phase. In this case, it is a two-phase flow, with the gas phase accounting for about 1/10 of the total mass. In this sense, it can also be called steam. Hehe^^