The temperature of rich methanol at the outlet of the H2S absorption tower in the LINDE process is too high!
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Recently, the temperature of the rich methanol at the outlet of the H2S absorption tower in the LINDE process has been on the high side, exceeding the normal level by about 10°; currently it is around 1°. The liquid level in the H2S absorption tower fluctuates significantly, and the temperature of the rich methanol at the outlet of the CO2 absorption tower is also above normal. The load has been relatively low lately. Could everyone help me analyze what might be causing this? How to adjust? Thank you!
The amount of cooling capacity available for analysis is lower~~ The process gas load is low, and there isn’t much excess capacity for CO2 to be dissolved in methanol~ This is probably why the system doesn’t have enough cooling capacity
This is a fairly normal phenomenon: when the flow rate of the process gas drops to a certain level, the temperature in the desulfurization section of the scrubber tower increases significantly. As mentioned earlier, methanol only gets absorbed and does not get desorbed; the reason for the relatively low temperatures usually is that as methanol is absorbed, the saturated carbon dioxide is desorbed at the same time. I’m not sure what product you are producing If it’s methanol, carbon dioxide coming out of the scrubber tower won’t be detectable, right? Level fluctuations are inevitable. Think about it: if methanol is not separated, its volume changes depending on the amount of gas absorbed, so the liquid level also experiences certain fluctuations. During full-load operation, the liquid level in the upper section of the scrubber experiences significant fluctuations; therefore, in some processes, automatic control of the liquid level in that upper section is omitted.
We have strict controls on CO2, and the gas is mainly hydrogen, which is used for hydrogen production. I always thought that the fluctuations in liquid level were caused by an imbalance in gas-liquid entrainment.
It might be due to too low system load and excessive methanol absorption; could the fluctuations in the liquid level of the hydrogen sulfide absorption tower be caused by an imbalance in the gas-liquid ratio? Without a flowchart, it’s difficult to make too many assumptions
As the original poster said, the load is low – has your circulation rate of lean methanol decreased? If the circulation rate of lean methanol remains unchanged, it will inevitably prevent saturated absorption, which in turn means saturated desorption cannot occur; as a result, most of the cooling capacity cannot be utilized effectively (it is not carried to the regeneration tower), and therefore the temperature of the rich methanol will rise!
Is the fluctuation in liquid level caused by air blockage in the heat exchanger with an inverted U shape? When the pressure of the liquid is greater than the air resistance, the liquid flows downward; when the liquid pressure is less than the air resistance, the liquid can no longer flow!