Why is it necessary to install a recirculation pipe for the water supply pump? - Heavy Oil burner

Why is it necessary to install a recirculation pipe for the water supply pump?

Why is it necessary to install a recirculation pipe for the water supply pump?

When the feedwater flow rate is very small or zero, the frictional heat generated by the impeller inside the pump cannot be carried away by the feedwater, causing the temperature inside the pump to rise. When the temperature inside the pump exceeds the saturation temperature at the pressure, the feedwater will vaporize, forming cavitation.

In order to prevent this phenomenon from occurring, it is necessary to ensure the minimum flow rate of the feedwater pump and set up a recirculation pipe. This can ensure the required minimum flow rate during unit start-up, shutdown, low load or accident conditions, and prevent the feedwater from vaporizing inside the pump.