If feedwater carries 100 ppm TDS and the boiler water is held at 3,000 ppm, the boiler runs at 30 cycles. Blowdown as a fraction of feedwater equals one over cycles, so 30 cycles means about 3.3 percent of the feedwater is blown down. Raising cycles saves water, fuel and chemicals, but only as far as scale, foaming and carryover limits allow.
We're at 12 cycles, the water's good enough for 25, cut the blowdown back and save some gas.
Comparing conductivity of boiler water to feedwater is the quickest way to check cycles on a shift.
Also heard as
- cycles
- COC
- concentration ratio
Related terms
TDS
Total dissolved solids: the concentration of dissolved minerals and salts in boiler water, held in range by blowdown.
Blowdown
Draining some boiler water on purpose to remove concentrated dissolved solids and settled sludge.
Makeup water
Fresh water added to a boiler system to replace water lost to leaks, blowdown, venting and unreturned condensate.