Boiler Blowdown Recovery

The rate stays where the water chemistry puts it. Recovery takes the cost out of each gallon discharged, which removes the temptation to cut blowdown and let dissolved solids climb. Once the heat is no longer wasted, operators tend to hold the correct rate instead of the cheapest one, and the boiler is better for it.

It can leave close to the temperature of the incoming make-up water, if the exchanger has enough surface and the flows are reasonably balanced. That matters twice: it maximizes the heat returned, and many sewer authorities limit discharge temperature, so cooler drain water can remove the need for tempering with cold water. Send us the make-up temperature and any discharge limit you work to.

Flow on the blowdown side simply stops, and the make-up side usually does the same, so the exchanger idles with both sides full. The concern is corrosion or deposit while it sits still, which a drain-down or a short flush on restart handles. On a plant with frequent boiler cycling, tell us the pattern so materials and drains are chosen with idle time in mind.

Bottom blowdown comes in short, violent bursts that carry sludge, and it is rarely worth chasing. The continuous surface blowdown is steady, relatively clean and running all day, which is where the recoverable heat sits. Most schemes recover the continuous stream and leave intermittent bottom blowdown going to its own blowdown tank as before.

Send the boiler operating pressure, the treatment program and the cycles of concentration you run. Those set the temperture at the exchanger inlet and the pH and solids the plates and gaskets will face. With that in hand we choose the alloy and compound against the concentrated water rather than guessing from feedwater figures.