Hydrocarbon Processing - May 2022 - 87

Water Management
T. FAGAN, D. WONG and E. ESTER,
Neptune, Grand Terrace, California
Bringing treatments to a boil
The function of a boiler is simple.
It boils water to produce steam, which,
in turn, provides energy. While this is a
straightforward process, there are complexities
within it that could affect the
boiler's integrity. The primary concern is
the quality of the water.
Even high-quality water contains impurities,
which has the potential to create
problems for the boiler's functionality.
Over time, chemical impurities in the
water could damage a boiler's internals,
leaving solid deposits, such as corrosion,
rust or scale as the steam evaporates.
These accumulated deposits could eventually
thermally insulate the boiler's heat
exchanger surfaces, reducing the boiler's
rate of steam generation and eventually
causing the equipment's metals to fail.
Without proper treatment, corrosion, rust
and scale may eventually lead to thermal
failure, reduced boiler efficiency and a potential
boiler failure.
The boiler is not the only thing that
may be affected by untreated feedwater.
Aside from the boiler's internals, the corresponding
safety equipment and auxiliary
piping may also suffer the effects of
water chemicals and impurities. Addressing
the quality of the feedwater becomes
imperative. Otherwise, the damage to
the boiler and associated equipment may
shorten their longevity and increase capital
expenditures.
That is why a boiler water treatment
plan is highly recommended to keep a
boiler operating at a high and efficient
level. Boiler water treatments neutralize or
remove impurities and chemicals in feedwater
to help ensure proper and effective
functionality, and boiler longevity.
Common challenges. Common water
contaminants are magnesium, calcium,
iron, aluminum and silica, all of which can
be found in hard water and result in hard
FIG. 1. Using chemicals to treat feedwater is only an effective method for handling impurities if
the amounts of chemicals are dispensed properly and accurately. This task can be achieved by
employing the proper metering pump or filter feeder.
Hydrocarbon Processing | MAY 2022 87
deposits when heated. Heated hard water
serves as the primary source of scale in
boilers. Scale buildup can reduce water
flow in pipes and can prevent the efficient
transfer of heat in boilers.
Corrosion stems from dissolved oxygen
and carbon dioxide (CO2
) in water.
These gases attach to the walls of the boiler,
piping and other equipment. Eventually,
these gases may eat away at the metals
within the equipment, causing corrosion,
weakening the system. The weakened
pieces are susceptible to cracks and other
damage that can severely impact the boiler.
Without chemicals. Tackling these common
challenges is best done through boiler
water treatment, of which there are several
options. One option does not require the
use of chemicals. The two approaches under
this method are using filters and softeners
to remove chemicals and preheating
the water ahead of its entry into the boiler.
Sediment filters are designed to remove
suspended solids in water, while water
softeners remove magnesium, calcium
and other impurities that cause hard water,
which can result in scale buildup.
The second approach is preheating the
feedwater before it enters the boiler. This
process helps remove dissolved oxygen
from the water, making it less harsh on
the internals of the boilers and associated
equipment. Preheating the water usually
occurs in a feedwater tank or a deaerator
using supplementary steam.
The chemical approach. Using chemicals
to treat feedwater is an effective
method for handling impurities, yet the
amounts must be dispensed properly and
accurately (FIG. 1). Too much of a chemical
treatment may adversely impact the
quality of the water, which could damage

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