(Do not use wire brushes or metal pads,
which will score the plates.)
; Take care when pressure washing not to
hose the gaskets directly, since that may
loosen or dislodge them, creating more
problems once the unit is reassembled.
It sounds time consuming, but per
my friend Susan Hammock at Alfa Laval,
a typical 1,000-ton plate heat exchanger
can be opened, cleaned and reassembled
in the matter of 16 to 24 hours by maintenance personnel, assuming no major
hiccups. Opening the plate pack allows
one to inspect the condition of the plates
and gaskets. If there is severe fouling of
the plates or suspected plate damage (fig.
3), the plates can be shipped off site to
authorized cleaning facilities that will
clean and inspect each plate for corrosion
and leaks and replace gaskets.
Susan recommends selecting a plate
heat exchanger with enough pressure
drop (~ 10 psid) at design flow to allow for
sufficient turbulence inside the unit at part
load. High turbulence gives you two benefits:
( 1) It provides a higher U-value (makes the
heat exchanger more efficient and involves
less first cost), and ( 2) it also gives a higher
shear stress on the plate walls, which creates
a scrubbing effect inside the heat exchanger
and reduces fouling.
For me, it is relying on my wife for a
jumpstart and transportation to where I
have to be until my car is fixed. For the
plate heat exchanger, it is an altogether
different issue. What is your current backup plan? (And no, my wife can’t pick you
up the next time your car breaks down!)
Based in Madison, Wis.,
Steve Tredinnick, PE, is
vice president of energy
services for Syska Hennessy
Group, which has more than
16 locations across the U.S.
He has more than 26 years’
experience related to building heating, ventilation and air-conditioning
systems. The past 15 years of his work have
been focused on district energy systems.
Tredinnick is a graduate of Pennsylvania State
University with a degree in architectural engineering. He is a member of IDEA and
ASHRAE and is currently immediate past chair
of ASHRAE TC 6. 2 District Energy. Tredinnick
currently serves on IDEA’s board of directors.
He may be reached at stredinnick@syska.com.
