Carrier AquaForce 30XB series - Major System Components; Twin-Screw Compressor Details; Pressure Vessels and Safety

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11.1 - Direct-drive twin-screw compressor with
variable capacity slide valve
- 30XB units use 06T geared twin-screw compressors
equipped with a variable capacity slide valve for
continuous control between 30% and 100% of full load.
- Nominal capacities range from 120 to 750 kW. The ten
models used in the 30XB & XBP range are economised.
11.1.1-Oillter
The 06T screw compressor has an independent oil lter attached
to the oil separator. This lter is eld replaceable.
11.1.2 - Refrigerant
The 30XB & XBP range units can operate with R-134a & R1234Ze
refrigerants.
11.1.3 - Lubricant
The 06T screw compressor is approved for use with the following
lubricants:
- Castrol Icematic SW220 (Carrier specication PP47-32)
- Lubrizol Emkarate RL220H (Carrier specication PP47-13).
11.1.4 - Oil supply solenoid valve
An oil supply solenoid valve is installed on the oil return line as
standard to isolate the compressor from oil flow when the
compressor is not operating. The oil solenoid valve is field
replaceable.
11.1.5 - Suction and economizer screens
To increase the reliability of the compressor, a screen has been
incorporated as a standard feature into suction and economizer
inlets of the compressor.
11.1.6 - Capacity control system
The 06T screw compressor has an unloading system that is
standard on all compressors. This unloading system consists of
slide valve that permits changing the length of the screw used for
the refrigerant compression. This valve is controlled by the action
of a piston controlled by two solenoid valves on the oil return line.
11.2 - Pressure vessels
General
Monitoring during operation, re-qualication, re-testing and re-
testing dispensation:
- Follow the regulations on monitoring pressurised
equipment.
- It is normally required that the user or operator sets up
and maintains a monitoring and maintenance le.
- If there are no regulations or to complement them follow
the control programmes of EN 378.
- If they exist follow local professional recommendations.
- Regularly inspect the condition of the coating (paint) to
detect blistering resulting from corrosion. To do this, check
a non-insulated section of the container or the rust
formation at the insulation joints.
- Regularly check for possible presence of impurities (e.g.
silicon grains) in the heat exchange fluids. These
impurities maybe the cause of the wear or corrosion by
puncture.
- Filter the heat exchange uid check and carry out internal
inspections as described in EN 378.
- In case of re-testing please refer to the maximum
operating pressure given on the unit nameplate.
- The reports of periodical checks by the user or operator
must be included in the supervision and maintenance le.
Repair
Any repair or modication, including the replacement of moving
parts:
- Must follow local regulations and be made by qualied
operators and in accordance with qualied procedures,
including changing the heat exchanger tubes.
- Must be made in accordance with the instructions of the
original manufacturer. Repair and modification that
necessitate permanent assembly (soldering, welding,
expanding etc.) must be made using the correct proce-
dures and by qualied operators.
- An indication of any modication or repair must be shown
in the monitoring and maintenance le.
Recycling
The unit is wholly or partly recyclable. After use it contains
refrigerant vapours and oil residue. It is coated by paint.
Operating life
This unit is designed for:
- Prolonged storage of 15 years under nitrogen charge with
a temperature difference of 20 K per day.
- 452000 cycles (start-ups) with a maximum difference of 6
K between two neighbouring points in the vessel, based on
6 start-ups per hour over 15 years at a usage rate of 57%.
Corrosion allowances:
Gas side: 0 mm
Heat exchange uid side: 1 mm for tubular plates in lightly alloyed
steels, 0 mm for stainless steel plates or plates with copper-nickel
or stainless steel protection.
11.2.1 - Evaporator
30XB chillers use a flooded multi-tube evaporator. The water
circulates in the tubes and the refrigerant is on the outside in the
shell. One vessel is used to serve both refrigerant circuits. There
is a centre tube sheet which separates the two refrigerant circuits.
The tubes are 3/4” diameter copper with an enhanced surface
inside and out. There is just one water circuit, and depending on
the size of the chiller, there may be one, two or three water passes.
The units have three refrigerant circuits with two evaporators
connected in series on the heat transfer uid.
The evaporator has a thermal insulation of 19 mm thick
polyurethane foam, an aluminium sheet (option) and is equipped
with a water drain and purge.
The water connection of the heat exchanger is a Victaulic
connection. As an option the evaporator is available with frost
protection (evaporator frost protection option).
The products that may be added for thermal insulation of the
containers during the water piping connection procedure must be
chemically neutral in relation to the materials and coatings to which
they are applied. This is also the case for the products originally
supplied by Carrier.
11 - MAJOR SYSTEM COMPONENTS AND OPERATION DATA