Patent ID: 6332336
Filing Date: 2001-12-25
Classification: F01D,F02C,F25J

Abstract:
A method for maximizing the production of natural gas liquids (liquid high-molecular weight fractions) from natural gas using equipment comprising a turboexpander with adjustable nozzles, a recompressor, a turboexpander speed controller, a flow-rate control, a compressor antisurge controller, and a compressor antisurge valve, the method comprising:(a) measuring a rotational speed, N, of the turboexpander;(b) calculating a deviation, N-N.sub.sp, of the turboexpander rotational speed, N, from a limiting set point, N.sub.sp ;(c) controlling the rotational speed of the turboexpander when the deviation is positive by modulating the compressor antisurge valve to return and maintain the deviation to a value less than or equal to zero; and(d) limiting the opening of the compressor antisurge valve when further opening results in a decrease in compressor power.