6-30
October 2012
6.5
Boiler and Steam Systems
36
EBMUD,
op. cit
.
••
Work with the water treatment vendor to prevent scaling and corrosion and opti-
mize cycles of concentration.
Improving Make-upWater Quality
To improve make-up water quality, consider the following:
••
Consider pre-treating boiler make-up water to remove impurities, which can in-
crease the cycles of concentration the boiler can achieve. Water softeners, reverse
osmosis systems, or demineralization are potential pre-treatment technology
options. Refer to
Section 7.2: Water Purification
for more information.
••
When increasing cycles of concentration, ensure that discharged water meets
allowable water quality standards.
Retrofit Options
To improve the efficiency of an existing boiler and steam system, consider retrofit-
ting the system by recovering steam condensate and installing meters and control
systems to monitor water use.
Recovering Steam Condensate
When recovering steam condensate, consider the following:
••
Install and maintain a condensate recovery system to return condensate to the
boiler for reuse.
••
Where condensate cannot be returned to the boiler and must be discharged to
the sanitary sewer, employ an expansion tank to temper hot condensate rather
than adding water to cool it.
Installing Meters and Control Systems
When installing meters and control systems, consider the following:
••
Install an automatic blowdown control system, particularly on boilers that are
more than 200 horsepower, to control the amount and frequency of blowdown
rather than relying on continuous blowdown.
36
Control systems with a conduc-
tivity controller will initiate blowdown only when the TDS concentrations in the
boiler have built up to a certain concentration.
••
If not already present, install flow meters on the make-up water line and the con-
densate return line to monitor the amount of make-up water added to the boiler.
Refer to the previous “Operation, Maintenance, and User Education” section for
recommendations on how to use the meter once it is installed.
