Conceptual Evaluation of a Membrane Unit for Flare Gas Recovery:Possibility, Efficiency and Advantages

In this research, a simple hybrid process encounters a cryogenic and membrane separation units was considered to separation of heavy hydrocarbons from a flare gas stream and also producing an off-gas stream with the highest amount of light components (C1+C2). The cryogenic section cooled the compressed gas to the temperature lower than the hydrocarbon dew point. The membrane system was a single-stage separation unit containing 12 or 18 spiral wound membrane elements from MRT Company (PDMS composite membranes) at six parallel lines. The differential pressure of 415 psig was considered for permeation phenomenon that expanded the permeated gas streams and cooled it. The permeated gas was recycled to the compressor discharge stream to enhancing the C3 + recovery. The recovery percentage of 50 and 70% (mass) were achieved by the membrane system containing 12 and 18 spiral modules respectively. Increasing the permeation surface increased the recovery value of heavy components but decreased its quality to some extent

Keywords:

PDMS , Composite Membrane , Flare , C3 recovery , Hybrid , Vapour