Case Study 4 – Vibration

Problem:

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.

Solution:

A variable speed controller was installed which allowed regulation of the flow rate by fan speed, so the damper could remain fully open.

Result:

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.