| 摘要 |
A method of controlling a centrifugal compressor to maximize its efficacy. The compressor has an impeller mounted on a shaft supported by an active magnetic bearing unit and is driven by a variable speed motor under normal on-load conditions at a calculated pre-surge speed for the required delivery pressure. The actual rotational speed and delivery pressure of the compressor is repeatedly measured and recorded at high frequency. The compressor is allowed to surge periodically after a preset re-calibration time and the compressor is put into a surge recovery cycle when surge is detected, during which the compressor is off-loaded and the rotational speed reduced. A compressor pre-surge speed line is recalibrated during the surge recovery cycle for the current operating conditions and the compressor reloads when the shaft speed reaches the greater of the recalibrated pre-surge speed line or the load speed. Preferably the said active bearing is capable of measuring the speed of the shaft and activates an alarm signal which starts the surge recovery cycle. The alarm also activates a by-pass valve which causes the compressor to off-load and signal the motor to reduce its rotational speed. |
