Thursday, December 9, 2010

ECONOMICAL OPTIONS FOR RECOVERING NGL / LPG AT LNG RECEIVING TERMINALS

ABSTRACT

A number of LNG receiving terminals are now in the planning or construction phases around the world. Many of these new terminals will be sited in highly industrialized nations where a significant infrastructure already exists for utilizing lighter liquid hydrocarbons (ethane and propane)as feedstock for chemicals production and fuel usage. This provides a strong economic incentive for recovering these components from the LNG prior to vaporization, with the added benefit of making the resulting gas more compatible with existing gas transmission pipelines by reducing its heating value.

Fractionation to separate the heavier hydrocarbons from the methane in LNG has not yet been practiced on an industrial scale. Nevertheless, the concepts involved are much the same as those that have been employed in cryogenic NGL and LPG recovery plants for decades. As such, extension of this more familiar "gas plant" technology to LNG fractionation provides significant economic benefit for the receiving terminal while adding very little project risk.

Ortloff has developed a number of processing schemes for efficient fractionation of LNG to produce NGL and/or LPG. The optimum processing scheme generally depends on several factors, including the desired product slate, the value of the products compared to the value of natural gas and the cost of energy, and the receiving and delivery conditions. In many LNG terminals, design parameters for existing pumping and vaporization equipment are also important constraints on the process design. This paper presents examples and discusses the relative merits of these new processing schemes.

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