CrystaSulf{sup SM} liquid redox and TDA gas phase H{sub 2}S conversion technologies for sour gas treating

Sour natural gas that contains hydrogen sulfide (H{sub 2}S) accounts for 15 to 25% of the gas processed in the US. Worldwide, as much as 30% of the gas reserves are sour. The need for more cost-effective approaches to process subquality gas is becoming more evident as new drilling occurs deeper within existing fields and in new fields. These types of producing zones tend to be sour. Gas containing very small amounts of sulfur (e.g., less than 0.2 long tons per day (LTPD)) can be cost-effectively treated with nonregenerable scavengers. This can be performed by injecting a liquid scavenger directly into a pipe containing the sour gas (direct injection) or by passing the sour gas through a tower containing a liquid or solid scavenger. Gas containing more than 25 to 30 LTPD of sulfur is generally processed by first separating the acid gases with an amine unit and then processing the amine offgas in a Claus plant to produce molten elemental sulfur. However, gas streams with sulfur amounts between 0.2 and 25 LTPD have generally posed treatment challenges to industry. This paper describes two emerging technologies for treating gases containing H{sub 2}S--the CrystaSulf{sup SM} liquid redox process and the TDAmore » gas phase direct oxidation process. Both convert the H{sub 2}S to elemental sulfur and both are being pilot tested during 1999. Radian International is commercializing both processes. CrystaSulf appears to be well suited to treat sour streams containing between 0.2 and 25 LTPD of sulfur. CrystaSulf can achieve sulfur control efficiencies of 99.8% or greater and can be applied directly to sour streams or to tailgases from amine units or Clause plants. The TDA direct oxidation process provides a cost effective way to treat amine unit tailgas and in a single stage can achieve 85 to 97% sulfur control efficiencies for that stream. Following successful pilot plant testing, both processes will be available commercially.« less