Frick RWB II 480, Установка, эксплуатация и обслуживание

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RWB II ROTARY SCREW COMPRESSOR UNITS
INSTALLATION
S70-200 IOM
Page 10
OIL FILTER(S)
Use of filter elements other than
Frick must be approved in writing
by Frick engineering or warranty
claim may be denied.
The oil filter(s) and coalescer filter element(s) shipped with
the unit are best suited to ensure proper filtration and opera-
tion of the system.
THERMOSYPHON OIL COOLING
Thermosyphon oil cooling is an economical, effective method
for cooling oil on screw compressor units. Thermosyphon
cooling utilizes liquid refrigerant at condenser pressure and
temperature that is partially vaporized at the condenser tem-
perature in a plate and shell vessel, cooling the oil to within
15°F of that temperature. The vapor, at condensing pres-
sure, is vented to the condenser inlet and reliquified. This
method is the most cost effective of all currently applied cool-
ing systems since no compressor capacity is lost or com-
pressor power penalties incurred. The vapor from the cooler
need only be condensed, not compressed. Refrigerant flow
to the cooler is automatic, driven by the thermosyphon prin-
ciple and cooling flow increases as the oil inlet temperature
rises.
EQUIPMENT - The basic equipment required for a ther-
mosyphon system consists of:
1. A source of liquid refrigerant at condensing pressure and
temperature, located in close proximity to the unit to mini-
mize piping pressure drop. The liquid level in the refrigerant
source must be 6 to 8 feet minimum above the center of the
oil cooler.
2. A plate and shell oil cooler with:
Plate Side: Oil 400 psi design
Shell Side: Refrigerant 400 psi design
Due to the many variations in refrigeration system design
and physical layout, several systems for assuring the above
criteria are possible.
SYSTEM OPERATION - Liquid refrigerant fills the cooler shell
side up to the Thermosyphon receiver liquid level. See Fig-
ure 7.
Hot oil (above the liquid temperature) flowing through the cooler
will cause some of the refrigerant to boil and vaporize. The
vapor rises in the return line. The density of the refrigerant
liquid/vapor mixture in the return line is considerably less than
the density of the liquid in the supply line. This imbalance pro-
vides a differential pressure that sustains a flow condition to
the oil cooler. This relationship involves:
1. Liquid height above the cooler.
2. Oil heat of rejection.
3. Cooler size and piping pressure drops.
Current thermosyphon systems are using two-pass oil cool-
ers and flow rates based on 3:1 overfeed.
The liquid/vapor returned from the cooler is separated in the
receiver. The vapor is vented to the condenser inlet and need
only be reliquified since it is still at condenser pressure.
OIL TEMPERATURE CONTROL - Oil temperature will gen-
erally run about 15 - 35°F above condensing temperature. In
many cases, an oil temperature control is not required if con-
densing temperature is above 65°F as oil temperature can
be allowed to float with condenser temperature.
Condensing Temperature: 65°F - 105°F
Oil Temperature: 80°F - 140°F
INSTALLATION - The plate and shell type thermosyphon oil
cooler with oil-side piping and a thermostatically controlled
mixing valve (if ordered) are factory mounted and piped. The
customer must supply and install all piping and equipment
located outside of the shaded area on the piping diagram
with consideration given to the following:
1. The refrigerant source, thermosyphon or system receiver,
should be in close proximity to the unit to minimize piping
pressure drop.
2. The liquid level in the refrigerant source must be 6 to 8
feet minimum above the center of the oil cooler.
3. A safety valve should be installed if refrigerant isolation
valves are used for the oil cooler.
The component and piping arrangement shown in Figure 8,
is intended only to illustrate the operating principles of ther-
mosyphon oil cooling. Other component layouts may be bet-
ter suited to a specific installation. Refer to publication E70-
900E for additional information on Thermosyphon Oil Cooling.
HOT OIL IN
FROM
SEPARATOR
120-140 F
OIL OUT
O
TO SYSTEM CONDENSER
95 F
2.5#/FT
O
3
95 F
36#/FT
O
3
TS RECEIVER
Figure 7