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Key Measurement Points in a Sulfur Recovery Unit Tail Gas Treatment Unit

Sulfur recovery units (SRUs) have been utilized to remove elemental sulfur from hydrogen sulfide (H2S) rich acid gas streams in hydrocarbon processing, refining, and steel production plants for over 70 years. Modern SRUs have been designed to use the Claus process and have historically achieved 90+% recovery of elemental sulfur, significantly reducing the amount of H2S and SO2 released to the environment. However, <99% recovery is no longer acceptable to many global regulatory agencies, so various plant designs and additions have been developed to achieve sulfur recovery rates of 99.8% or even 99.9%.

Continuous, analytical gas measurements can be performed in tail gas treatment units (TGTUs) or tail gas cleaning units (TGCU) to ensure reliable, efficient, and safe operations in the effort to reduce sulfur emissions from the sulfur recovery unit (SRU).

A TGTU is designed to receive the gas output from the Claus unit, referred to as the tail gas, and further capture, and therefore reduce, sulfur compounds that will be released from the plant. Compared to the feed gas at the start of the Claus unit, a typical tail gas stream will contain much lower levels (<5%) of sulfur compounds – such as H2S and SO2 – at the TGTU inlet, and these will ultimately be lowered to ppm levels at the emissions stack outlet.

Click here to read more about the removal of elemental sulfur in a TGTU in Michael Gaura’s article, “The Key Points,” published in the October 2021 edition of Hydrocarbon Engineering magazine.

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