I am having issues with getting enough flow from a feedwater heater drain to the DA. The primary drain can not accommodate the entire flow. The drain water has to travel 70 vertical feet to the DA. The secondary drain feeds back to a lower pressure feedwater heater and when it opens the pressure drop reduces or stops the flow to the DA. I have increased the control valve trim on the primary, but I still have the same issue. I am familiar with using a pump to push feedwater heater drain water back into the condensate line, but has anyone ever seen a pump used to move water from a feedwater heater drain to a DA?

Hi,
Yes, I work at an older plant (53) and we have the same setup as you are mentioning. We have heater drain pumps, and they operate at lower loads when the differential between the lowest pressure feedwater heater and the deaerator pressure is such that it will not flow. Heater vents to deaerator also have a similar scheme with an automatic vent to condenser that is open until there is more than a 10 #diff between the 4rd ext. to dea. and the 3rd ext. to #4 heater.
At lower loads, the heater drain pump runs to boost the cascading FWH drains to the Dea, but once past mid load, they can be shut down, and the flow will begin to go on its own.