100

10

1

5

10

9

8

7

6

pH

3-2.7.2

to know the amount of carbon dioxide (CO2) in steam when assessing the return on

investment (i.e., cost savings from removing the CO2 versus the cost for use of internal

chemical treatment to remove the CO2). Engineers and water treatment service

companies need to estimate the amount of CO2 to properly estimate the amount of

neutralizing amine water treatment chemical that must be used. Example 3-5 illustrates

this estimation:

CO2 levels in the steam can be estimated from the amount of bicarbonate and

the carbonate alkalinity present in the feedwater as follows, where the "P" and "M"

alkalinity measure these compounds. (See paragraph 6-6.1 for test methods.)

EQUATION

CO2 = [bicarbonate x 0.79] + [carbonate x 0.35]

(18)

CO2 = [(M - 2P) x 0.79] + [2P x 0.35]

where:

CO2 = carbon dioxide estimate, ppm as CO2

M = total (methyl orange) alkalinity, ppm as CaCO3

P = phenolphthalein alkalinity, ppm as CaCO3

EXAMPLE 3-5:

a) Measured P = 2 ppm, M = 60 ppm

b) Bicarbonate CO2 contribution [60 - (2 x 2)] x 0.79 = 44.2

60

Integrated Publishing, Inc. |