che_november-2024 - 27

FIGURE 2. Changing to this rotary valve eliminated the
stem leakage that occurred with a globe valve
valves, have long been used where
high flowrates and minimal to moderate
pressure drops were the order
of the day. However, now there are
rotary valves that handle low-valveflow-coefficient
(Cv) requirements,
and noise and cavitation-resistant
trims are available on several types
of rotary stem valves. There are far
fewer processes now that must
use a globe valve.
Figures 1 and 2 depict one
example where a new type of
rotary valve provides improved
performance over a traditional
approach. These pictures show
a stark difference in the stem seal
performance of a globe (Figure
1) and a rotary (Figure 2) control
valve installed in the same process
for the same length of time.
The owner noticed his globe
valves developed " fuzz balls "
of process liquid that leaked
through the packing and then
crystallized. The process fluid in
this case is both toxic and flammable,
so he looked for another
solution. The rotary valve showed no
stem leakage over the time it took for
this fuzz ball to form.
By changing the type of control
WASH MORE. ENTRAIN LESS.
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and
42% larger maximum free passage††
Explosion
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30-60% larger droplet size† ††
valve specified, you may eliminate an
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for your plant. Remember to
consider valves with rotary stem sealing
for your problematic processes. ■
Edited by Dorothy Lozowski
Acknowledgement
All figures are reproduced courtesy
of Valin Corp.
Author
Peter Jessee is a process control
application engineer at Valin
Corporation (Email:
pjessee@
valin.com; Website: www.valin.
com), a subsidiary of Graybar. He
is a licensed professional engineer
with over 40 years of experience
in control valve technology.
Jessee has extensive experience
in the refining, chemical, pulpand-paper
and food-processing industries, bringing
expertise in optimizing process control and enhancing
operational efficiency. With a B.S.M.E., he possesses a
solid foundation in the principles of design and systems
integration. With a solid background in the design,
selection and application of control valves, Jessee
has played a critical role in improving system
performance and reliability for various chemical and
refining applications.
300% less entrainment† ††
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†when tested with water
††
when compared to traditional maximum free passage style nozzles
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CHEMICAL ENGINEERING WWW.CHEMENGONLINE.COM
NOVEMBER 2024
For details visit adlinks.chemengonline.com/86469-10
27
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