Water Treatment Boilers Requirements are :
Water treatment is required to provide the physical plant with properly
treated water in sufficient quantities to meet plant needs. All
system require water treatment by using speciality chemicals such
as corrosion and scale inhibitors , however open systems require
constant water treatment to deal with the constant need for treated
water to make-up for system losses of often up to 100%. Closed systems
also require water treatment, but due to minimal system losses,
that treatment commonly occurs only at the system fill source.
Industrial water treatment for cooling water systems , water treatment
boiler requires advanced water technologies ,keeping in mind chemistry
of water and use of advanced formulations of corrosion and scale
Three tools can be used to improve water quality:
- Internal Treatment – conditioning the
boiler water to pre-determined levels by using a variety of chemicals.
- Demineralization/ Reverse Osmosis / Electrodialysis
- the replacement of specific inorganic salts by ion exchange.
- Deaeration – the removal of dissolved
oxygen and carbon dioxide by heating and atomizing the water with
While demineralization and deaeration can be accomplished easily
by investment in the appropriate support equipment, internal treatment
calls for a more concerted effort. However, most organizations large
enough to have in-house maintenance will find that the combination
of these three tools will more than pay for themselves in defrayed
operating costs. A well-implemented program will ensure -
- Increased heat transfer
- Lower fuel expenditures
- Lower chemical consumption
Except for steam trap maintenance, water treatment has the most
potential for reducing annual operating costs in a power plant.
Boiler Losses due to scale
|Thickness of Scale
||Increase in fuel consumption due to scale
|4 mm ( 0.125” )
|8 mm ( 0.25” )
|16 mm ( 0.5” )
|30 mm (1” )
Objectives of Water Treatment boiler
Prevention of scaling in boiler.( use speciality chemicals such
as scale inhibitors to counter it )
Prevention of corrosion in boiler. (use speciality chemicals such
as corrosion inhibitors to counter it )
Prevention of stress corrosion cracking.
Prevention of steam contamination.
What is an External Treatment?
Treatment of water that are done outside of the boiler is called
pre-boiler or external treatment. The main physical methods for
improving quality of water for boiler include flocculation, clarification,
deaeration, oil removal, colour removal, suspended solids removal
and blow down. When preparing water for boilers operated at less
than 150 psi, all necessary chemical treatments can be accomplished
in a clarifier, but as pressure increases; the quality of feed water
must improve. The purpose of external treatment is to reduce suspended
solids, demineralize the feed water and remove silica. This purpose
can be achieved by
- Coagulation with chemicals
- Demineralization/ Reverse osmosis/ Electrodialysis (cold lime,
soda process, hotlime-soda process, mixed bed exchange)
- Silica removal (coagulation with chemical, Demineralization,
Reverse Osmosis, Electrodialysis)
What is an Internal Treatment?
There are number of treatments that are made within the boiler
to minimize the adverse effects of small concentration of components
that remain in the feed water after the external treatment. In
spite of various external treatments, it is not possible to attain
an absolute perfect quality of boiler feed water. Chemical treatment
or internal treatment of water inside the boiler is essential
to take care of various impurities entering into the boiler such
as hardness, dissolved solids, oxygen, and silica.
In many cases, external treatment of water supply is not necessary
specifically in low or moderate pressure boilers or where large
amount of condensed streams are used or when raw water available
is of very good quality.
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