Desulfurization issues for natural gas to methanol production
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Our plant uses natural gas as raw material to produce methanol. In the desulfurization process, we have a nickel-molybdenum hydrogenation reactor, two zinc oxide desulfurization tanks, and an external ultra-clean desulfurization tank. Is this necessary? This post was last edited by Ma Hai on 2009-2-24 18:28 ]
It's necessary! Because H2S not only corrodes equipment and pipelines, but also poisons subsequent catalysts, such as expensive synthetic catalysts! If S exceeds the standard, not only will the catalyst have to be replaced, but production will also be affected! Adding more removal equipment will help stabilize production!
Natural gas contains a small amount of sulfides (mainly H2S). Through hydrogenation, other sulfides can be converted into H2S, H2S+ZnO-----ZnS+H2O (of course carbonyl sulfide will react with water to generate carbon dioxide and hydrogen sulfide). The purer the sulfur is removed, the longer the life of the catalyst! This post was last edited by 3218zhu on 2009-2-23 11:35 ]
superficial view: Desulfurization is necessary and necessary. Using natural gas as raw material to produce methanol requires that the S content in the desulfurized raw gas be below 0.1ppm. A nickel-molybdenum hydrogenation reactor and two zinc oxide desulfurization tanks should be able to meet production needs. The ultra-clean desulfurization tank can be ignored.
From the perspective of subsequent work sections, desulfurization is essential
I’m not sure what the sulfur requirements of methanol synthesis catalysts are, but for FT synthesis catalysts, such as Co-based catalysts, the general requirement is less than 40 ppb. After low-temperature methanol washing and zinc oxide desulfurization, the sulfur content of the synthesis gas can be reduced to 20 ppb, so I think the subsequent ultra-clean desulfurization is unnecessary.
After the first few stages of desulfurization, the sulfur content in natural gas may drop below the ppm level. In order to ensure that the sulfur content in the feed gas for subsequent methanol production is lower than the value allowed by the methanol catalyst. Perhaps without adding an ultra-clean desulfurization tank, the raw gas may meet the requirements. Personally, I feel that adding an ultra-clean desulfurization tank is mainly to ensure that the raw gas meets the requirements, even if the sulfur content in the outlets of the first few reactors increases slightly.
The main function of ultra-clean desulfurization tank is safety guarantee. personal opinion
The pre-conversion catalyst has high requirements for sulfur content, generally less than 0.1ppm. Generally, zinc oxide is sufficient, and foreigners have added ultra-clean desulfurization tanks, just in case.