Large Electric Utility Company – Slurry Valves

Business Objective

To alleviate cavitation in various Vee-balls in slurry lines throughout the FGD unit.

Plan

The FGD unit included as part of its original design several Vee-ball valves that are mainly installed in recirculation lines that are cavitating. The valves were lasting less than one year. Due to potential erosion (from the slurry) an attenuator was not an optimal solution and due to capacity issues, erosion, and costs a globe style valve was not a viable alternative. It was decided (after a year of selling this solution) to aspirate air into the valves to cushion the bubble collapse. A spool piece was sold through our Corrosion Division that included taps to aspirate +5PSIG of air immediately after the valve.

Outcome

After providing this solution on the first Vee-ball valve vibration was eliminated (as was cavitation) on the valve during normal flow. During maximum flow, vibration was reduced by 75%.

Results

The entire solution less plus the spool piece was less than two hundred dollars. It is estimated the customer will now get close to five years out of these valves rather than one. A 6” ET with Cav Trim would have been well over $25K. Also, the local engineer looked at re-piping the recirculation line (to allow the cavitation to “blow” into the vessel) but determined engineering and construction costs would have exceeded $250K.