Natural-gas processing is a complex industrial process designed to clean raw natural gas by separating impurities and various non-methane hydrocarbons and fluids to produce what is known as pipeline-quality dry natural gas.

Natural-gas treatment begins at the wellhead. The composition of the raw natural gas extracted from producing wells depends on the type, depth, and location of the underground deposit and the geology of the area. Oil and natural gas are often found together in the same reservoir. The natural gas produced from oil wells is generally classified as associated-dissolved, meaning that the natural gas is associated with or dissolved in crude oil. Natural gas production that is naturally occurring and not associated with crude oil production is classified as “non-associated” or “free gas”.

Process Diagram for Natural Gas Purification

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PSA Principle for Natural Gas Purification

Pressure swing adsorption (PSA) is a cyclic adsorption process for gas separation and purification. PSA offers a broad range of design possibilities influencing the device behaviour. In the last decade much attention has been devoted towards simulation and optimisation of various PSA cycles. The PSA beds are modelled with hyperbolic/parabolic partial differential algebraic equations and the separation performance should be assessed at cyclic steady state (CSS). Detailed mathematical models together with the CSS constraint makes design difficult. We propose a surrogate based optimisation procedure based on kriging for the design of PSA systems. The numerical implementation is tested with a genetic algorithm, with a multi-start sequential quadratic programming method and with an efficient global optimisation algorithm. The case study is the design of a dual piston PSA system for the separation of a binary gas mixture