Anywhere compressed air can be eliminated represents an opportunity to reduce system operating expenses. Often, this reduction means fewer compressors must operate to meet the plant's air requirements.
Author: Christopher Schmidt, Mark D'Antonio and Alan MacDougall
Install a flow meter in the recycle, cascade the flow set point with a pressure control loop. With proper tuning, the valve characteristics are lost in the flow control loop, which should be tuned fast with PI.
Electric variable-speed drives on lubricant-cooled and lubricant-free rotary air compressors are not a cure-all for system woes -- chemical plants must implement them correctly and at the right time to achieve maximum energy savings