Test of TDA's Direct Oxidation Process for Sulfur Recovery

Abstract

This project was a Phase III pilot plant test of TDA's gas sweetening process done under realistic conditions. TDA Research Inc successfully completed the test at Whiting Petroleum's Sable San Andreas Gas Plant. The feed was approximately 228,000 standard cubic feet per day (SCFD) of gas that contained approximately 60 vol% CO{sub 2}, 20 vol% CH{sub 4} and 10 vol% C{sub 3}+ and higher hydrocarbons. The feed was associated gas from CO{sub 2} flooding operations carried out on Whiting's oil wells. The gas is collected and piped to the Sable gas plant where it is normally flared. We sited our pilot plant in line with the flare so that we could remove the hydrogen sulfide (H{sub 2}S) prior to flaring. The average H{sub 2}S concentration in the gas during the field test was 7341 ppm. The selectivity of our process for converting H{sub 2}S into elemental sulfur was essentially 100% and the catalyst converted 90% of the H{sub 2}S into sulfur and water (the remaining 10% of the H{sub 2}S passed through unconverted). Importantly, no catalyst deactivation was observed for over the course of the 1000+ hour test. Minimal (ca. 10-15 ppm) of SO{sub 2} was formed during the test. Approximately 3.6 tons of elemental sulfur was recovered from a total inlet of 3.9 tons of sulfur (as H{sub 2}S). The total amount of SO{sub 2} released from the plant (taking into account flaring of the unconverted 10% H2S) was 0.86 tons. This amount of SO{sub 2} is much lower than the normal 8 tons that would have been emitted if all of the H{sub 2}S were flared over the time of the pilot plant test. The pilot plant was simple to operate and required much less operator intervention than is typical for a new unit being commissioned. Our operator (Mr. Eugene Peeples) has more than 30 years of experience operating commercial scale liquid redox sulfur recovery processes and in his opinion, TDA's Direct Oxidation pilot plant is easier to operate than liquid systems. The ease of use and low capital and operating costs of TDA's Direct Oxidation process makes it an attractive technology to be used where traditional sulfur recovery technologies are too expensive (e.g. small to medium sized plants). Currently, TDA's direct oxidation process has been exclusively licensed to SulfaTreat, and is being offered commercially under the trade name SulfaTreat-DO{reg_sign}. We anticipate that the first plant will be installed in 2005.