Carrier 16JB - Manual (Page 5)

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into the vacuum pump condensate return system.
If this method is used, it is desirable to use either
cold boiler feed water or any other cold water
source which will benefit by heat rejected from hot
condensate.
CLOSED CONDENSATE RETURN
(PRESSURIZED) SYSTEM
16JB010-068 — Many manufacturers have high-
temperature condensate units, generally suited for
use with most of the Carrier absorption machine
Une. Because the condensate units are usually quite
high, some of the smaller machines may not be
high enough to provide liquid head for gravity
flow. In these cases, the closed system should not
be used. A typical unit consists of a closed ASME
Code receiver and centrifugal pump for returning
hot condensate to the boiler. This system has the
advantage of complete condensate recovery with­
out flash losses often experienced in atmospheric
return systems.
These systems require very careful application
to the absorption machine. There are two common
types of closed condensate systems :
The first type will operate under pressurized
conditions. The pressure between the generator
and receiver is equalized and condensate flows by
gravity to the closed receiver located below the
generator outlet. It is essential that under these
conditions the vacuum breaker on the 16JB
generator should be blocked. This is to prevent air
from building up in the closed receiver. Also, the
closed receiver should be equipped with a device
that is capable of releasing the air that is in the
system after a shutdown period. A thermostatic
vent is usually suppUed for this purpose. In this
type of system, the pumps on the receiver can
pump under vacuum.
The second type of closed system consists of a
closed receiver with atmospheric condensate
pumps. Therefore, the receiver is usually equalized
with the steam chest. In this type of system, the
vacuum breaker and the generator must be left open
so that the receiver cannot go into the vacuum range.
A steam trap is usually recommended.
16JB077-124 — Because the 16JB077-124 units
have two steam inlets, these machines must be
considered as having two generators when applying
a closed condensate system. Each end of the
machine operates at a different steam pressure.
This could cause the condensate to back up into
the generator and cause dangerous water hammer if
the condensate system were not properly designed.
Each end of the machine should be considered
similar to the system on 16JB010-068 units (see
Fig. 4).
CLOSED CLOSED
CONDENSATE CONDENSATE
RECEIVER
П r~
RECEIVER 1
TO lA S 1------------------------------------- 1 1 til TO
L-b^-eoa^
NOTE' Each J5IKÌ 5s similar t o O f ) l&lóOliKSeS machìnes.
Fig. 4 — Closed Condensate Return System
(16JB077-124)
HOT WATER MACHINES
The 16JB hot water absorption machines are
furnished with pneumatic controls only. Fig. 5
schematically
illustrates the capacity control
valves, controls and control panel. There are two
commonly used piping systems, depending on the
temperature of the supply hot water.
077 THRU 124 SIZES ONLY
EPS — Electric-Pneumatic Switch
PE — Pressure-Electric Switch
Fig. 5 — Pneumatic Control Schematic
Piping For Water Temperature of 300 F Or Below
— Fig. 6 gives suggested hot water piping when
supply hot water is 300 F or below. The capacity
of the machine is controlled by regulating the flow
of hot water through the generator. Either a
two-way or three-way capacity control valve (CV)
can be used. Machine sizes 16JB077-124 require
two capacity control valves if partial load effi­
ciency of double generators is to be utilized.