Sulphur recovery optimization of Claus/Sulfreen Units

Stringent environmental standards and greater public awareness require an increased emphasis on the operation of sulphur plants to maximize sulphur recovery and minimize emission levels. In an effort to reduce sulphur emissions, extensive work at the Ram River Gas Plant was conducted to optimize the plant operation between 1980 and 1984. The topics to be discussed in this paper include process analyzers and controllers, COS and CS/sub 2/ conversion, oxygen control, COS and CS/sub 2/ generation, and Sulfreen optimization. As a result of the work conducted, the overall yearly recovery average has increased from 98.1% in 1980 to 98.7% in 1983. The contribution by sulphur compounds to plant emissions were, 22.3 tonnes equilibrium limits, 8.3 tonnes ratio upsets, 13.7 tonnes COS/CS/sub 2/, and 4.7 tonnes Sulfreen losses. The Ram River Plant processes sour natural gas from 12 different pools with a maximum H/sub 2/S content of 39%. The inlet capacity is 17.7 x 10/sup 6/m/sup 3//day raw gas and 300 m/sup 3//day pentanes plus, producing 12.0 x 10/sup 6/m/sup 3//day sales gas, and 4,600 tonnes/day sulphur as the by product of the DEA sweetening process. The sulphur recovery facility consists of four, 1150 tonnes/day modified-Claus plants and two Sulfreen units.more » Acid gas feed to the sulphur recovery units varies between 70% and 83% H/sub 2/S with CO/sub 2/ making up the bulk of the remaining composition. Each sulphur plant is a straight through process with two, 91 tonne converters with interstage condensers/coaleser units. Each Sulfreen tail gas unit is fed by two sulphur trains. Stage I Sulfreen has six, 89 tonne reactors while the Stage II unit has three, 204 tonne reactors. The waste gas from each Sulfreen is passed through separate incinerators where the remaining sulphur components are oxidized to SO/sub 2/ before being released through a common stack.« less