The customer operated a gas-powered Wartsila generating set on a North Sea floating production, storage, and off-loading (FPSO) unit. Because the associated gas used to power the engines was extremely rich, the engines had to be de-rated to achieve reliable, trouble-free operation. The customer wanted to remove at least half of the C3+ components from the gas to allow the engines to be used at their rated capacity. The available footprint for the fuel conditioning unit was small.
MTR installed a simple one-stage membrane system in which the membrane tubes were arranged vertically to save space. A coalescing filter upstream from the membrane modules removed entrained liquids and particulate matter. The feed gas then passed to the modules, which divided the gas into a
2,400 m3/h conditioned gas stream to power the engines and a 4,300 m3/h permeate stream to be recycled to the suction side of an existing vapor compressor. The membrane modules lowered the C3+ content of the gas from 15.7% to 5.0%. Fuel quality problems with the compressors were eliminated.