Chapter 7—AUXILIARY MACHINERY
feed to the first effect will raise the liquid level
in the first effect. More heat will be required to
raise the feed to the boiling point, so that less heat
will be available for evaporation in the first-effect
shell and a smaller amount of heat will flow to
the second-effect tube nest. These changes would
work out to a new balanced condition, but other
adjustments would be required to make the new
balance satisfactory. Under such circumstances,
overcontrolling can cause many readjustments.
The operator will always find it is better to make
adjustments singly and in small increments, allow-
ing enough time between each adjustment for the
conditions to become steady.
gland properly vented, gland properly packed and
sealed, no air leaks in piping).
f. Tube nests properly drained.
(1) Proper operation of all drain
regulators.
(2) Proper operation of the tube nest
drain pump.
3. Highest possible vacuum in the last-effect
shell.
a. No air leaks.
Causes of Low Plant Output
b. Proper air ejector operation.
Failure to obtain full rated capacity is one of
the most frequent troubles encountered during
operation of a distilling plant. The trouble may
be very difficult to remedy since it may result from
a combination of things. Following are the various
factors which promote full output of the distill-
ing plant. Any variations of these may cause a
decrease in the plant’s efficiency.
(1) Clean nozzle and strainer.
(2) Steam at the required quality and
quantity.
c. Ample flow of circulating water.
1. Proper steam pressure above the orifice.
2. Highest possible vacuum in the first-effect
tube nest.
(1) Clean strainer, pipeline, and tubes.
(2) Proper valve settings.
(3) Proper operation of the circulating
pump.
a.
b.
shells.
c.
vented.
d.
No air leaks
Proper water levels in the evaporator
Evaporator tube nests continuously
Evaporator tube nests reasonably clean.
(1) Continuous feed treatment.
(2) Tubes mechanically cleaned when
necessary.
e. Density of brine overboard not over
1.5/32.
(1) Overboard piping reasonably clean.
(2) Proper valve settings.
(3) Proper operation of brine pump
(clean piping and strainers, proper speed and
direction of rotation, pump properly vented,
d. Effective surface in the distilling
condenser.
tubes.
(1) No undue deposits inside the tubes.
(2) Proper venting of the condenser
(3) Proper operation of the condensate
pump.
Steam Pressure
A distilling plant cannot maintain its full out-
put unless it is supplied with dry steam at the
designed pressure. The orifices supplied are
designed to pass the proper amount of steam to
ensure designed plant output with a pressure of
about 5 psig above the orifice. Orifices should be
inspected annually. An orifice should be measured
and the reading compared with the figure stamped
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