CAUTION:
During times of shutdown, volumetric expansion
can occur. We recommend the installation of a properly sized relief
valve on both sides of the heat exchanger.
INSTALLATION
1. Before installing this equipment, environment and service
conditions should be checked for compatibility with materials of
construction. Contact your nearest Xylem Representative if you
are not sure what the actual materials of construction are.
2. Provide valves and by-passes in the piping system so that both
the shell and tube sides may be by-passed to permit inspection
or repair.
3. Provide thermometer well and pressure gauge connections in all
piping to and from the unit and locate as near the unit as
possible.
4. Provide convenient means for frequently cleaning the unit as
suggested under “Maintenance.”
5. Provide necessary air vent cocks for units so they can be
purged to prevent or relieve vapor or gas binding of either the
tube or the shell sides.
6. Foundations must be adequate so that exchangers will not settle
and cause piping strains. Foundation bolts should be set to
allow for setting inaccuracies. In concrete footings, pipe sleeves
at least one size larger than bolt diameter slipped over the bolt
and cast in place are best for this purpose, as they allow the bolt
center to be adjusted after the foundation has set.
7. Loosen foundation bolts at one end of unit to allow free
expansion of shells. Oval holes in foundation brackets are
provided for this purpose.
8. Set exchangers level and square so that pipe connections may
be made without forcing.
9. Inspect all openings in exchanger for foreign material. Remove
all thread protectors and shipping pads just before installing. Do
not expose units to the elements with pads or other covers
removed from openings since rain water may enter the unit and
cause severe damage due to freezing.
10.Be sure the entire system is clean before starting operation to
prevent plugging of tubes with sand or refuse. The use of
strainers in settling tanks in pipe lines leading to the unit is
recommended.
11.Drain connections should not be piped to a common closed
manifold.
12.Location of the operating fluids in the heat exchanger can be a
function of the application. A few tips for the location of the
operating fluids are:
a. As a cooler, the preferred arrangement is with the hot
medium through the shell and the cooling medium through
the tubes. When the hot fluid is dirty or fouling, it is better to
put it through the tubes because they are easier to clean.
With single pass units be sure the shell inlet is on the same
end as the tube side outlet. In two pass units, the shell inlet
should be at the inlet-outlet bonnet end. It is customary for
the cooling medium to enter the lower bonnet connection,
although this can be reversed if necessary.
b. As a heater, the hot medium, usually steam or hot water,
must be in the shell. If it is steam, either of the shell
connections, or both, can be used, dependent on the actual
entering velocities.
c. For the above applications and for temperatures above
150°F, the higher temperature fluid should be circulated
through the shell side of the exchanger and precaution
should be taken to avoid shock from abrupt changes in fluid
circulation temperatures.
13.Steam hammer can cause serious damage to the tubes of any
heat exchanger. A careful consideration of the following points
before an installation is made can prevent costly repairs which
may be caused by steam hammer.
a. A vacuum breaker and/or vent, should be used in accordance
with the type of steam system installed.
b. The proper trap for the steam system installed should be
used.
c. The trap and the condensate return line to the trap should be
properly sized for the total capacity of the convertor.
d. The trap should be sized for the pressure at the trap, not the
inlet pressure to the steam controller.
e. The trap must drain into an unpressurized condensate return
system. Condensate return lines must not be run at an
elevation above the bottom of the heat exchanger. To do so
may result in a buildup of the condensate level in the heat
exchanger, which could cause water hammer and damaged
tubes.
CAUTION:
Fluids must be gradually introduced to the unit.
Failure to do so can cause damage to the heat exchanger.
OPERATION
1. When placing a unit in operation, open the vent connections and
start to circulate the cold medium only. Be sure that the
passages in the exchanger are entirely filled with the cold fluid
before closing the vents. The hot medium should then be
introduced gradually until all passages are filled with liquid,
close vents and slowly bring the unit up to temperature.
2. Start operation gradually. Do not admit hot fluid to the unit
suddenly when empty or cold. Do not shock unit with cold fluid
when unit is hot.
BCF HCF & SSCF Heat Exchangers Installation, Operation, and Maintenance Manual
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