The trace sulfur levels in the low-temperature methanol wash transformed gas and untransformed gas are above the specified limits
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In our plant, the low-temperature methanol wash unit consists of two washing systems that share one regeneration system; during this period, the levels of trace sulfur in both the transformed gas and the untransformed gas have been above the specified limits, and we have tried hard to identify the cause without success. In daily operations, the water content in the methanol regenerated by the system remains around 0.12%, the temperature of the methanol used for washing is also within normal ranges, and the amount of washing liquid is sufficient. At present, the amount of nitrogen gas used for stripping is relatively low (in previous operations, the gas quality was satisfactory at this level of stripping gas); moreover, the filters need to be cleaned frequently during production. What exactly is the reason for this?
Measure the acid value of the regenerated methanol to assess the issues with the regenerated methanol
The acidity of the regenerated methanol was 0.037 (on a HCOOH basis), which is slightly high.
It is recommended to rule out a leak in the raw gas cooler
@Koyo, what’s your opinion on this situation?
I need to think about it. I’ve only been involved in low-temperature methanol washing for a short time, so I don’t have much experience and I’m not sure I can speak rashly on this topic
Oh, okay, if you have any good ideas, get in touch with the original poster
By transformed gas, do you mean your exhaust gas or the product gas?
This post was last edited by Small and on 2017-9-13 22:38. If it’s a product-related issue, then there’s a problem with the quality of the methanol during regeneration; the only requirement is regarding moisture levels. Has the sulfur content in the methanol after regeneration exceeded the allowed limits?
Less nitrogen is used for stripping, which results in a high sulfur content remaining in the methanol rich in hydrogen sulfide; moreover, the temperatures at the bottom and top of the regeneration tower must be maintained properly
It seems that the steam volume to the regeneration tower is a bit low; isn’t the reflux flow rate to the regeneration tower insufficient?