The Gavin plant has seven stages of closed feedwater heaters, three high pressure stages, and four low pressure stages. The photo shows one of the three #7 heaters. Notice the feedwater inlet and outlet pipes in front. On the side we see the heater drain pipes and throttling valves.
The photo shows one of the two closed feedwater heaters #1 - the first of the four stages of low pressure (800 kPa) heater stages.