The development of cryogenic turboexpander plants for the recovery of liquids from naturalgas has evolved significantly over the years. The primary focus of developers has been on thereduction of operating and capital costs while maintaining high recoveries through lowering thehorsepower demand for recompression of the residue gas. Other major developments over the yearsinclude improved heat integration through the addition of multiple side reboilers and theimplementation of reflux streams to improve recovery. We have seen other innovations developed toimprove the processes tolerance to carbon dioxide.One element common to most turboexpander processes is that both the recovery of product andthe stabilization of product are carried out at essentially the same pressure, whether it is with a singletower scheme or with a dual tower scheme. Although this is suitable for many conditions of inletpressure and composition, there are instances when another approach is more efficient.A process scheme for the recovery of liquids from natural gas has been developed which is inthe patenting process that allows for the independent, optimum selection of the operating pressure forboth the recovery process and the stabilization process. This scheme is applicable to both ethane andpropane recovery. This paper describes this process, which is in the patenting process, and its benefits.
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