Page 160 - Boiler plant and distribution system optimization manual

Over 100 Ways to Improve Efficiency 145

12. KEEP INSTRUMENTATION AND gallons of water in 24 hours producing over 30
CHART RECORDERS IN GOOD REPAIR. pounds of minerals behind every day. This adds
up and causes problems by forming foam on the
A lot of things happen in the typical thermal steam-water interface a cause of carry over, scale
plant that can’t be seen, in boilers covered with on tube surfaces and suspended sludge which
ibricks and insulation, in piping systems and at usually sinks to the bottom of the lower drum.
remote locations served by the piping systems. These dissolved solids are kept at a manageable
Plants don’t necessarily run on observable data level by draining a portion of the contaminated
the instruments tell the story about efficiency. water from the boiler, called blow-down. This
People need correct data to make safe decisions water contains a lot of heat, not to be wasted.
too; there are a lot of dangers connected to ther- The scale when formed retards heat transfer also
mal plant operations. wasting energy and causing possible boiler dam-
age, so this area is a good target for energy sav-
ings activity. See Chapter 15 for more details.

Section 10-5 2. USE WATER SOFTENER
Boiler Water Management Hardness in water is caused by dissolved
calcium and magnesium which precipitates out
of the feedwater. As the temperature of the water
CHECkLIST 5 is raised calcium and magnesium precipitate out
Boiler Water Management of the water and adhere to surfaces such as boiler
tubes. The softener is used to remove calcium and
1. Improve water treatment magnesium from the make up water. This reduc-
2. Water pretreatment softener es the potential for scale deposit formation in the
3. Boiler water chemistry improvements in- boiler allowing the boiler to carry higher cycles of
crease cycles of concentration concentration producing both water and energy
4. Install automated blow down control system savings. Another important benefit of this water
5. Mechanical scale removal softening process is the prevention of boiler tube
6. Chemical scale removal failure caused by overheating of the tube metal
7. Boiler blow down heat recovery caused by these scale deposits
8. Use hot blow down water to keep idle boil-
ers warm
3. INCREASING CYCLES OF
CONCENTRATION
1. BOILER WATER MANAGEMENT
TO CONSERVE ENERGY Cost
Low
When boiler feedwater is heated, it evapo-
rates and goes off as distilled steam leaving im- Potential Savings
purities behind. As more and more water is dis- Moderate
tilled in the boiler, more feedwater containing
dissolved solids is added to replace it. As a result Description
the amount of these solids dissolved in the boil- Cycles of concentration is the ratio of impuri-
er water gradually increases. A boiler as small as ties being maintained in the boiler water divided
100 horsepower, can evaporate more than 10,000 by the impurity level of the boiler feedwater. This