Hydrocarbon Processing - May 2022 - 89

Water Management
pressures up to and beyond 4,000 psi (276
bar), automatic control with an electronic
stroke control or variable-speed motor,
and manual control through an adjustable
micrometer dial.
Hydraulic metering pumps vary by
model, with some having variable oilbypass
adjustment to provide improved
valve performance. This oil-bypass adjustment
enhances performance by allowing
the pump's valve extra time to seat. These
pumps can be constructed from several
different materials, such as 316 stainless
steel, C-20, polyvinyl chloride (PVC)
and Kynar, all of which can handle a variety
of chemicals. To meet certain service
requirements, hydraulic metering pumps
can also handle being outfitted with several
motor configurations.
Solenoid-actuated or electronic metering
pumps work well as an economical
option for boiler water treatment. They
provide chemical injection for low-capacity
and low-pressure [less than 2 gph and
under 250 psi (17.2 bar)] applications.
These pumps have a repeatable accuracy
of +/- 3%, with some having stroke rates
of 300 strokes/min or higher, allowing
for improved chemical injection at low
flowrates. Many of these pumps can also
operate at any single-phase voltage from
94 VAC-264 VAC and are unaffected by
voltage fluctuations.
The pump's composition tends to be
316 stainless steel, PVC or Kynar pump
heads; Viton or polytetrafluoroethylene
(PTFE) seals; PTFE diaphragms; and 316
stainless steel and ceramic or PTFE check
valves. These materials give these pumps
versatility for several chemical injection
applications during boiler water treatment.
Solenoid-actuated pumps also have
several models with a manual frequency
adjustment or speed control for stroking
speed. Some models even have frequency
adjustment and stroke-length adjustment,
allowing for large turndown capabilities.
The case for filter
feeders. Filter
feeders are an option that continues to
gain consideration for boiler water treatment
because of their dual functionality
(FIG. 3). They operate as a single piece of
equipment that can inject water treatment
chemicals, while also acting as a filtration
device by capturing the coagulated solids
and impurities that cause rust, corrosion
and scale.
Filter feeders use a filtration bag that
captures nearly all contaminants, even
those that are as small as 1 micron, which
is five times smaller than the width of
a human hair. These bags can also be
disposed of after they are full, instead
of being cleaned and used again, which
can reintroduce captured particles back
into the system.
Takeaway. While there are multiple ways
to help ensure the integrity of feedwater
for boilers, the most reliable method involves
chemical treatments using metering
pumps or filter feeders. These options
provide tangible results that help maintain
the boiler's optimal functionality and
health throughout its lifespan.
TIM FAGAN is a Product Specialist for Neptune.
DUSTIN WONG is a Product Specialist for Neptune.
EULIS ESTER is a Product Specialist for Neptune.
EWA provides decision-makers the data necessary to:
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Hydrocarbon Processing | MAY 2022 89
Hydrocarbon Processing - May 2022

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