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Application Considerations |
Figure A-1 — Typical
Steam Supply Piping
1. Steam Supply Valve (Detail "B")
2. Strainer
3. Union or Flanged Connection
4. Gate Valve
5. Drip Leg
6. Float & Thermostatic Trap
7. Pressure Gauge, Vent and Shut-off Valves (Detail
"A")
8. Pressure Reducing Valve
9. Pressure Gauge
10. Relief Valve
Note: Nominal steam valve is selected for a pressure drop
of 5 psig. If steam supply pressure exceeds the selected valve pressure drop, a pressure
reducing valve (Item 8) may be needed.
Detail "B"
General
Trane Horizon™ two-stage absorption chillers are designed for use in air
conditioning and process applications requiring a continuous and reliable supply of
chilled water in the range of 40 F to 60 F. The Horizon two-stage model range is 380 tons
through 1150 tons. Two-stage machines are most often used where an economic evaluation of
refrigeration equipment justifies a higher first cost to obtain a lower operating cost.
Catalog application data is based on ARI 560-92. All
selections are based on a fouling factor of .00025 on the interior of all tube surfaces.
Selections based on the use of fluids other than water, or with other fouling factors, can
be obtained by contacting a local Trane sales engineer.
In planning an absorption refrigeration installation,
consideration must be given to providing the following:
• structural support
• service access
• tube pull space
• piping access for tube maintenance
• condensate handling
• steam supply control
• condenser water temperature control
• chilled water flow control
• chilled and condenser water flow limit
• generator hot water application
In a properly installed and maintained installation, the
Trane two-stage absorption chiller offers a high degree of reliability.
Operating Limits
Trane two-stage absorption chillers operate with steam
pressure up to 115 psig. In all applications, superheat should be limited so steam
temperature does not exceed 400 F. Hot water machines can use up to 370 F hot water.
Water flows within the limits indicated on the appropriate
selection charts will insure tube water velocities not exceeding 10 feet per second in
copper tubes and 11 feet per second in cupronickel tubes. Changes in chilled water flow or
condenser water temperature should not exceed 3 percent of chilled water flow per minute
or a 1 degree condenser water temperature change per minute.
Steam Supply
The steam supply piping should be designed in accordance
with good design practice, providing strainers, unions and gate valves for ease of
operation and maintenance. A properly sized steam modulating valve, based on design flow
and pressure drop requirements, is provided factory mounted by the Trane Company.
A hand valve in the steam supply piping is recommended when
the machine will be out of operation for an extended period. The modulating steam valve
may experience a small amount of leakage during shutdown. This leakage may result in
heating of the equipment room unless the machine is properly valved off with a hand valve.
In all applications, it is recommended that the steam
supply pressure to the control valve inlet not exceed design to assure proper valve close
off. If steam supply pressures exceed design, a pressure reducing station should be used
to control the steam pressure to the valve.
Figure A-1 illustrates a typical steam supply piping
illustration that includes the appropriate hardware. Steam Supply |
