Page 134 - Boiler plant and distribution system optimization manual

Over 100 Ways to Improve Efficiency 119

Figure 10.14—Tracking exhaust temperature 1 Figure 10.15—Tracking exhaust temperature-2

(a) The condensate should return at
160°F-190°F. If it doesn’t return, this heat
is lost.
(b) Makeup feedwater must be chemically
treated and heated from 50°F to 160°F-190°F
to replace the lost condensate.
(c) Condensate is essentially pure water.
Having to replace it with “makeup” wa-
ter containing impurities increases the
amount of blowdown required.
(d) Chemical treatment of the makeup feed-
water and the cost of the water itself can Figure 10.16—Rule of thumb for boiler water tem-
be avoided. perature.

There is an additional factor here, and that is
if the condensate system has leaks or is not func-
tional and steam traps have failed and are blow-
ing steam, all of this high energy steam is also dis-
appearing.
Electric pumps have an uncertain lifetime in
environments which occasionally can flood, also
centrifugal pumps have difficulty handling con-
densate near the boiling point. These electrical
units can be replaced with pump sets which use
steam pressure to pump condensate back to the
boiler plant.

Advantages/Disadvantages
Repair and replacement of condensate return Figure 10.17—A steam powered pumping unit over-
systems can be quite expensive. The economic comes the reliability problems of electrical powered
gain or savings available from keeping conden- pumps with a longer life, less expensive installation
sate systems well maintained is also very high. and lower operating costs.