Condensate & Feedwater
U-Tube Heat Exchangers

Condensate & Feedwater U-Tube Heat Exchangers

Boiler House Heat Recovery

Condensate returning from process users carries substantial heat and is already treated, which makes recovering both the water and its energy the single best economic move available in most steam plants. You avoid the make-up water cost, the treatment chemical cost and the fuel to reheat it, all at once.

Feedwater preheating raises boiler efficiency directly. Every degree added before the boiler is a degree the boiler does not have to add. High-pressure feedwater heaters in power generation are among the most demanding U-tube applications built, and they are classic DEU territory: a D-type front head closure for tube-side pressure beyond what a bolted bonnet holds economically, behind a bundle with no rear pressure joint at all.

Blowdown recovery is the item most often omitted. Continuous blowdown carries heat away by design, and it does so continuously. A small exchanger recovering that heat into make-up water typically pays back in months. The reason it gets left out is not economics; it is that nobody put it on the drawing.

Flash steam is part of the design, not an afterthought. Hot condensate and blowdown released to a lower pressure flash into steam. Ignoring that produces an exchanger sized for a liquid stream that is partly vapor in practice. The usual arrangement is a flash vessel recovering low-pressure steam first, with the remaining liquid passing through the heat exchanger, and sizing the exchanger for the liquid that actually reaches it is what makes the numbers work.

Oxygen control matters as much as heat recovery. Recovered condensate that picks up air on its way back becomes a corrosion problem in the boiler rather than an asset. Closed recovery systems, properly vented deaeration and attention to where the return line can draw air are all part of doing this properly.

Thermal cycling is constant. Boiler house exchangers follow plant steam demand, which means they cycle for their whole service life. A U-tube bundle absorbs that without an expansion joint, which is a large part of why the geometry dominates the application.

Related pages: steam-to-water heating, DEU high-pressure exchangers, high-pressure U-tube construction and clean steam generation.