Have you ever taught of applying Flow-Delta protection strategy in pump minimum flow protection?

All centrifugal compressor potentially surge when the flow rate crosses the surge point and potentially leads to catastrophic failure. Hence, anti-surge control is always implemented to safeguard a centrifugal compressor. Flow-Delta anti-surge protection strategy (Fig. 1) is on of the anti-surge control widely applied in centrifugal compressor as anti-surge protection strategy.

Fig. 1 Typical Flow-Delta anti-surge protection strategy

Centrifugal pump may subject to cavitation when the flow rate reach it minimum allowable flow where severe internal recirculation occurred and potentially damage the pump impeller. A process engineer shall always implements minimum flow protection strategy for centrifugal pump to avoid the potential damage. Typical centrifugal pump minimum flow control strategies are:

(i) A restriction orifice on pump discharge recycle line
(ii) A flow meter on pump discharge with control valve on recycle line
(iii) Use Automatic Recirculation Valves (ARC) valve

Is it feasible applying Flow-Delta protection strategy in pump minimum flow protection?

Yes. Above strategy is feasible A paper written by S. Mirsky (from CCC) described in brief the implementation of the above strategy.

Fig. 2 : Minimum flow protection strategy for centrifugal pump

Source : Pump Control Strategies Benefits from Compressor Know-How (HP,Feb 2005)

Figure above shows application of Flow-Delta anti-surge protection strategy for centrifugal pump minimum flow protection in Offshore Seawater injection system.

Reference :
S, Mirsky, << Pump Control Strategies Benefits from Compressor Know-How >>, Hydrocarbon Processing, Feb 2005

JoeWong