Example analysis of methanol consumption, please explain the reasons
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In the low-temperature methanol washing device of a certain factory, after the absorption tower has been running for a period of time, the pressure difference has increased from 45KPa to 54KPa, and the gas-entrained methanol has also increased from the design value of 50ppm to more than 10,000ppm. After stopping for inspection, it was found that there was no problem with the tray, and the sulfur content of the circulating methanol was also low. The requirements are met. The only thing that does not meet the requirements is the content of NH3 in the circulating methanol. The design value is 20mg/l, and the maximum value can be 200mg/l during operation. After increasing the discharge of dirty methanol (methanol in the acid gas reflux tank), the tower pressure difference is restored, and the gas entrained methanol is also significantly reduced. Please explain why the NH3 content is related to the amount of methanol entrained in the gas?
I think the ammonia content in the lean methanol will not affect the methanol content in the purified gas. If the ammonia content in the lean methanol is too high, it will affect the hydrogen sulfide content in the purified gas. The possible reason for the high methanol content in the purified gas is that the tower pressure difference is too large, causing liquid blocking or liquid carrying accidents. Otherwise, the methanol content in the purified gas will not change so much.
This post was last edited by poatmc at 2010-5-25 09:22 with reply 2# 654262293 I have the same idea as you. But the result is that after reducing the ammonia content, the amount of methanol in the purified gas is greatly reduced. Is it possible that NH3 reacted with other substances and blocked the tray, causing the tower pressure difference to be too high and liquid flooding to occur? However, I checked the tower top mist eliminator and its downcomer, and there were no abnormalities. Open each manhole in the tower and check that the visible trays are relatively clean, without any scaling or dirt, and the float valve moves flexibly, without sticking or astringency. For further confirmation, we dismantled six more main wash trays and found no abnormalities after inspection.
I think it may be because there is too much dirt brought in by the previous process, or it may be that the system was not blown clean during purging. At this time, filtration should be strengthened.