IMPROVEMENTS IN OR RELATING TO SCREW EXPANDERS

摘要

A method of reducing the pressure of a working fluid comprises expanding the working fluid in a screw expander from an initial pressure and bleeding a portion of the working fluid from the screw expander at an intermediate pressure lower than the initial pressure. The remaining working fluid is expanded in the same screw expander and discharged at a discharge pressure lower than the intermediate pressure. A screw expander for performing this method comprises: a casing having an inlet for admitting working fluid to the casing at a relatively high initial pressure; an outlet for discharging working fluid from the casing at a relatively low discharge pressure; and at least one bleed port located downstream of the inlet and upstream of the outlet for extracting working fluid from the casing at an intermediate pressure between the initial pressure and the discharge pressure.