Case Study 4 – Vibration
This steel company had been experiencing severe vibration and cracking of the casing on their coke oven battery scrubber booster fans supplied by a competitor when operated at reduced flow conditions. Robinson field service technicians were called in to investigate. Measurements of vibration and pressure pulsation versus frequency revealed a rotating stall condition. This is an aerodynamic instability that can occur with certain fan/damper combinations at reduced flow.
A variable speed controller was installed which allowed regulation of the flow rate by fan speed, so the damper could remain fully open.
The fan now operates smoothly at all process flow rates, plus the energy savings of this method of control is estimated to be $200,000 annually.