Applications SEVEN

Variable speed lowering and lifting required

Water treatment works using SBRs (Sequencing Batch Reactors) draw off treated water from above the settled solids using a decant arm. This structure must be lowered into the water slowly (typically over around one hour at a constant speed) without disturbing the settled solids at the bottom of the tank.

However, to ensure fast refilling, the arm needs to be raised rapidly to a preset parked position above the water prior to the next decant cycle.

Brine pumping control valves
INEOS Enterprises in Mid Cheshire UK have several hundred brine wells, each using pumps to transfer brine from the well to saturator unit. The flow is controlled using Pump Delivery Recycle Butterfly Valves driven by actuators.

Under normal operation when a reduced flow is detected, the actuator which controls the valve is opened over a period of 80 seconds, however, if a reverse flow is detected then the valve needs to be closed in 10 seconds to protect the pump.

Different speeds are therefore required for opening, closing and emergency closure to protect the pump.