Feed Water Heater
The feed water heater is not required but can significantly increase the efficiency of the system.
The exhaust from the turbine is on the low pressure side and must be cooled and condensed. The boiler feed water is on the pressurized size and must be heated and turned into steam. The feed water heater allows a heat transfer between the high and low pressure sides while keeping the pressure difference.
The feed water heater is a small heat exchanger that forced the hot exhaust steam passed the feed water as it is slowly being pumped into the boiler. The energy is recovered from the exhaust and reduces the need for a condenser.