| 摘要 |
The stroking speed of an antisurge control valve is impeded by the combined damping effects of signal dead time and the inherent lag of ancillary pneumatic components within a primary control loop. Furthermore, as control valve actuator size increases, the negative influence of these two impediments (dead time and lag) is amplified. As a result, control valve response times are adversely affected; and the possibilities of surge-induced compressor damage and process upsets are heightened. For these reasons, this disclosure relates to a method for protecting turbocompressors from impending surge, and for preventing subsequent process upsets, by improving antisurge control. But more specifically, it describes a technique for decreasing damping effects by evacuating control valve actuators (diaphragm or piston) through restrictions having a lower resistance to compressible-fluid flow rather than through volume boosters-consequently, increasing a control valve's opening speed to that of an emergency shutdown. The proposed method (1) allows continuous control of antisurge control valves and (2) incorporates both solenoid valves and quick exhaust valves (located adjacent to the actuators) which are manipulated by predefined discrete signals from antisurge controllers.
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