| 摘要 |
A screw expander comprising two or more rotors having meshed helical formations and being supported for rotation in respective bores inside a casing, wherein the casing comprises 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. Preferably the bleed port has a smaller cross-sectional area than the outlet and presents an elongate helical slot to a bore. The working fluid may be steam. A method of reducing pressure of a working fluid is also claimed. |
