Blowdown Fuel Penalty
Definition
The fuel cost of the sensible heat carried out of the boiler with blowdown water, calculated from blowdown rate, specific heat, temperature difference, and boiler efficiency.
For a boiler blowing down 1,000 lb/hr at 212 degrees F against 60 degree F makeup, heat loss is 152,000 BTU/hr, which divided by 80 percent efficiency gives 190,000 BTU/hr of required fuel and about 1.90 dollars per hour at 10 dollars per MMBTU, or roughly 16,644 dollars per year. This excludes the water, sewer, and chemical cost of the blowdown. It shows why unnecessarily low cycles are expensive, because every extra pound of blowdown discards already-heated water.
Related concepts
Boiler Efficiency · Sensible Heat · Cycles of Concentration
Part of The Blueprint of Water · 📏 measurement