Dear friends, please let me know in most of the power plants recirculation line and balance leak off lines are provided for boiler feed water pumps and those lines are connected to Deaerator. Why?
The feed pumps for most power plants are multistage centrifugal pumps. They have a minimum flow requirement or the balancing forces of the various impellers are lost and the pump is damaged. A recirculation line permits a minimum flow to be maintained at all times. It goes back to the deaerator so the boiler feedwater is not lost. Note: many of these pumps have the recycle automated so it is only in operation at very low flow rates. The leak off from the balancing line is recycled for the same reason.
