3-1.5.5

between feedwater, blowdown, steam generation, and COC is represented as:

a) F = B x COC, from COC, Equation (2) above

b) F = E + B, from COC, Equation (1) above

c) B x COC = E + B, replacing F in Equation (2) with

Equation (1)

d) B x COC - B = E, rearranging Equation c) above

e) B x (COC-1) = E, rearranging Equation d) above

f) B = E (COC-1), rearranging Equation a) above

3-1.5.6

measured by a meter. As shown below, it can be calculated if any two of the following

parameters are known*: *1) feedwater; 2) COC; or 3) steam generation (E). Steam

volume is usually measured in units of meters on large boilers. The COC can be

calculated by measuring the conductivity or TDS in both the boiler water and the

feedwater. Note that the conductivity and quantity of TDS is the same for the boiler

water and the blowdown water.

COC = BTDS / FTDS

EQUATION

or

(4)

Bmhos / Fmhos3

where

COC= cycles of concentration, no units

BTDS= blowdown TDS, ppm

FTD= feedwater TDS, ppm

Bmhos= blowdown conductivity, micromhos

Fmhos= feedwater conductivity, micromhos

3-1.5.7

calculations in paragraph 3-1.5.6 can be used to determine the feedwater rate in units of

kilograms per hour (pounds per hour). Note that the term "feedwater" refers to water

that is fed to the boiler and includes the makeup water plus the condensate return and

steam from the deaerator.

EXAMPLE 3-1:

a) A 1720-kilopascal (250-pound-per-square-inch-gauge) boiler operates at a

conductivity level of 5000 mhos. The boiler feedwater has a conductivity

of 250 mhos. The COC calculation is:

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