초록 ▼

Compressors for processes, as used for refrigeration systems applied to ethylene production, are multiple stage machines; furthermore, sidestreams enter/exit between the stages. Since a flow measurement device is not available between stages, and the gas temperature entering most stages is unknown,

Compressors for processes, as used for refrigeration systems applied to ethylene production, are multiple stage machines; furthermore, sidestreams enter/exit between the stages. Since a flow measurement device is not available between stages, and the gas temperature entering most stages is unknown, it is difficult to calculate an accurate value for reduced flow for antisurge control purposes. A new method is described, whereby reduced flow alone is replaced by the product of the reduced flow and the equivalent speed. This allows accurate calculation of the distance of the operating point to the surge line since the inlet temperatures into the separate compression units (except the first) are not necessary. The invention described herein can be applied to multistage compression systems for a variety of processes.

대표청구항 ▼

A method for antisurge control of a compression unit of one or more combined stages of a multistage compressor comprising the acquisition of a mass flow rate (m) through, a compression ratio (Rc) across, a rotational speed (N) of, and a pressure (p) in suction or discharge of the compression unit, t

A method for antisurge control of a compression unit of one or more combined stages of a multistage compressor comprising the acquisition of a mass flow rate (m) through, a compression ratio (Rc) across, a rotational speed (N) of, and a pressure (p) in suction or discharge of the compression unit, the method comprising the steps of: (a) computing a value for qNe=(mN)/p for the compression unit; (b) computing a surge parameter, Ss=f(Rc, qNe), for the compression unit; and (c) using the value of Ss for antisurge control. An apparatus for antisurge control of a compression unit of one or more combined stages of a multistage compressor comprising the acquisition of a mass flow rate (m) through, a compression ratio (Rc) across, a rotational speed (N) of, and a pressure (p) in suction or discharge of the compression unit, the apparatus comprising: (a) means for computing a value for qNe=(mN)/p for the compression unit; (b) means for computing a surge parameter, Ss=f(Rc, qNe), for the compression unit; and (c) means for using the value of Ss for antisurge control.