Total sulfur content in the purified gas exceeds the limit (3 points for reward)
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Dear sea friends, after some of the process gases undergo purification through low-temperature methanol washing, the total sulfur content in the purified gas exceeds the specified limit； As far as I know, there are several companies in China whose operations exceed the specified limits, and these issues have yet to be resolved. People can share which low-temperature methanol washing process package their respective companies use, whether the shift reaction is partial, what the catalyst’s water-gas ratio is, and what the total sulfur content in the purified gas is.
Our company uses the low-temperature methanol washing process package from Dalian University of Technology, full low-temperature shift technology, and catalysts produced by Qingdao Lianxin; the total sulfur content in the purified gas does not exceed the specified limits.
There are many units that use low-temperature methanol washing; there are also quite a number of shift units. In downstream facilities where methanol and acetic acid are produced, both full-shift and partial-shift processes share the same set of low-temperature methanol washing systems
Which organization are you from? Could I have your contact information?
We provide low-temperature methanol washing as a complement to coal pulverization pressurized gasification; it involves partial conversion with a low water vapor ratio, and the total sulfur content in the purified gas is generally in the range of 10–40 ppb
Which company makes your low-temperature process package?
In the conversion section, incomplete hydrolysis of organic sulfur compounds such as certain carbonyl sulfides can easily lead to excessive total sulfur levels in the low-temperature washing process.
If it’s a design issue, it’s difficult to fix. If the total sulfur level becomes excessive after the system has been operating stably for some time, it is possible to check the sulfur content in the lean methanol; in many cases, a leak in the heat exchanger causes the lean methanol and sulfur-free methanol to become contaminated, resulting in an elevated total sulfur level in the purified gas.
Dalian University of Technology: In the ammonia/synthetic methanol co-production process, the levels of total sulfur in the purified gas and total sulfur in the CO2-containing product gas have been above the specified limits since June 2016; this was attributed to leaks in the methanol-lean/methanol-rich heat exchangers. Recent maintenance work has been completed, and operations are now normal!
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This situation does not occur in the early stages of operation; after running for some time, it gradually increases and even exceeds the limit. The reason is that large molecular organic sulfur compounds such as thiol, thioether, and thiophene are difficult to remove during the methanol regeneration process, and their cumulative presence leads to excessive total sulfur levels. The only solution is to replace it with fresh methanol.