Boiler Blowdown Recovery

Boiler Blowdown Recovery

Recovering Heat You Are Throwing Away

Boilers blow down continuously to control dissolved solids. That water leaves at boiler pressure and temperature and it is discarded. Putting a small exchanger between the blowdown and the incoming make-up water recovers most of the heat for essentially no operating cost.

Flash comes first. Hot blowdown released to lower pressure flashes into steam. A flash vessel recovers that low-pressure steam before the liquid reaches the exchanger, and sizing the exchanger for the liquid that actually arrives is what makes the numbers work.

Small unit, continuous duty. The flow is modest but it runs whenever the boiler runs, which is what produces the payback. Projects that look marginal on flow rate frequently look excellent on annual hours.

Materials. Blowdown is concentrated boiler water and it is chemically aggressive. Plate material and gasket compound are chosen against that concentration rather than against feedwater.