Advances in natural gas liquids(NGL)recovery technologies,coupled with enhanced compact brazed aluminum heat exchanger design,higher expander and compressor efficiencies,and improved fractionation schemes have made significant contributions to today's NGL plant designs.The newer processes are generally less complex and more energy efficient than earlier designs and can also be designed to operate in either an ethane rejection or an ethane recovery mode.The flexibility of switching between ethane rejection and ethane recovery is important for most gas processing processes as this capability allows a quick response to the cyclic nature of the ethane market.Retrofitting an existing process to obtain this flexibility requires detailed evaluation.The extent of process reconfiguration must be economically justified by either higher product revenues or lower energy consumption.This paper describes a new Fluor~R Cryo-GasSM process for NGL recovery that can be used to retrofit NGL plants for increased liquids recovery without increasing energy consumption.The case study reported in this paper outlines a retrofit of a 1970s expander plant operating with a relatively low pressure feed gas.The low pressure feed gas presents a technical challenge for high liquids recovery,as the refrigeration produced by turbo-expansion is limited and the use of pre-compression is cost prohibitive.The Cryo-Gas process described in this paper is capable of more than 99 percent propane recovery,up to 90 percent ethane recovery,and can be easily switched between ethane recovery and rejection.Patents are pending on the technology discussed in this paper.
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