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FM-148 COLUMBIA BOILER COMPANY, REV 6-06
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for the precipitation of scale forming salts before scale is deposited.
Below a pH of 5.0 the water is acidic enough to dissolve the steel boiler plates. Under
these conditions the steel gradually becomes thinner and thinner until its destruction. At a
pH between 5 and 9.4 pitting of shell plates will occur at a rate depending on the amount
of dissolved oxygen in the boiler.
Dissolved Oxygen
Dissolved oxygen is caused by the solubility of atmospheric oxygen into the supply water.
Aeration of the city water supply is frequently used to remove other noxious gasses.
Efficient aeration results in saturation of the water with oxygen.
The majority of corrosion problems are directly related to the quantity of dissolved oxygen
in the boiler water. Elimination of the corrosive effect of dissolved oxygen can be accom-
plished both directly or chemically.
Direct or mechanical removal of dissolved oxygen is done through the use of a deaerator
or by heating the water to a temperature above 180°F. Heating the water can be done
with a preheater or a sparge tube installed in the return system.
Chemical deaerator is done through the introduction of specific chemicals in the boiler to
react with the oxygen. The dissolved oxygen content should be maintained at a minimum
but at no time should it exceed 0.007 mg/l.
Sulfites
Sodium sulfite is generally used for the chemical removal of dissolved oxygen within the
boiler water. To assure the rapid and complete removal of the oxygen entering the boiler
feedwater system the concentration of sulfite in the boiler must be maintained at a mini-
mum of 20 PPM. (parts per million)
Solids
Solids can be broken up into two categories: suspended solids, and dissolved solids.
Suspended solids are those which can be removed by filtration, while dissolved solids are
in solution with the water. The best test for the determination of solids content of the boiler
water is through a conductance test.
The conductance value of boiler water varies by the various ionized salts present. The con-
ductance can be used to measure the total dissolved solids in the boiler water and to serve
as an accurate means for the control of solids through the use of blowdown.
Another test which is sometimes used as a gauge of solids is to measure the chloride pres-
ent in the boiler water. The ratio of chlorides in the boiler water to that of the feed water
can be used as a means to determine the amount of blowdown required. The chloride test
is unsuitable for feedwater with low incoming concentrations and the concentrations in the
feedwater must be averaged over time for accuracy.
Содержание CT Series
Страница 2: ...CT BOILER WITH PARTIAL SECTION Figure 1 ...
Страница 13: ...FM 148 COLUMBIA BOILER COMPANY REV 6 06 10 Figure 4 BLOWDOWN PIPING ...
Страница 34: ...FM 148 COLUMBIA BOILER COMPANY REV 6 06 31 MAINTENANCE LOG ...
Страница 35: ...FM 148 COLUMBIA BOILER COMPANY REV 6 06 32 MAINTENANCE LOG ...
Страница 48: ...APPENDICES ...
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Страница 60: ...OPERATION OF WARRICK DUAL FUNCTION CONTROLS 5 95 PRINTED IN U S A ...
Страница 61: ...INSTALLATION OF WARRICK SERIES 3C 3K ELECTRODE FITTINGS ...
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Страница 63: ...OPERATION OF WARRICK SERIES 26 CONTROLS 5 93 ...
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