Government mandates that have reduced the maximum allowable sulfur content of motor fuels have necessitated the costly installation of additional hydrodesulfurization (HDS) capacity at many refinery locations.
The capital investment for these additional HDS facilities was only the first hurdle for most refiners. HDS processing results in the production of incremental amounts of hydrogen sulfide (H2S),which must then be removed from the recycle hydrogen stream and reduced to elemental sulfur. Such H2S processing can often be accomplished by removing the H2S with a new amine acid gas removal unit and then sending it to the plant’s existing sulfur recovery unit (SRU) facilities, which are traditionally based on the Claus process followed by tail gas treating (TGT). Although the increase in sulfur production is often just a few tons per day, the existing SRU facilities at many refinery locations cannot handle the additional load. In such problem situations, the construction of new SRU facilities has seemed to be the only available solution. Refiners now have another choice when addressing this problem — CrystaSulf.
CrystaSulf is a nonaqueous sulfur recovery process that removes both H2S and light hydrocarbons from the hydrogen recycle stream of hydrotreaters. Using CrystaSulf, refineries can recognize a significant cost savings due to reduced hydrogen losses and an increase in hydrogen partial pressure in the hydrogen recycle stream. The H2S that is removed in the process is converted directly to elemental sulfur with no need for a conventional Claus SRU. The benefits are substantial, especially for refineries that don’t currently have an SRU, that have limited SRU capacity, that want to avoid changes to an existing SRU, or that have large seasonal turndown ratios.
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