Major System Components And Operation Data; Direct-Drive Twin-Screw Compressor With Variable Capacity Slide Valve; Pressure Vessels - Carrier AquaForce 30XBE 250 Installation, Operation And Maintenance Instructions

12 - MAJOR SYSTEM COMPONENTS AND OPERATION DATA

12.1 - 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(E/P) range are economised.
12.1.1 - Oil filter
The 06T screw compressor has an independent oil filter attached
to the oil separator. This filter is field replaceable.
12.1.2 - Refrigerant
The 30XB(E/P) range units must operate with R-134a.
12.1.3 - Lubricant
The 06T screw compressor is approved for use with the following
lubricants: Carrier specification PP47-32 & Carrier specification
PP47-13
CAUTION : Too much oil in the circuit can cause the unit to
malfunction.
NOTE : Never use oils which have been exposed to air.
12.1.4 - 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.
12.1.5 - 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.
12.1.6 - 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.

12.2 - Pressure vessels

General
Monitoring during operation, re-qualification, 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 file.
- 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 fluid 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 file.
70
Unit PED classifications
The unit PED classification depending are presented in the
following tables. The unit classification is driven by the the highest
PED class equipment.
30XB(E/P) 250 300 350 400 450 500 600 700 750 800
Standard unit
PED Category III III III
30XB(E/P)
850 900 1000 1100 1200 1300 1400 1500 1550 1700
Standard unit
PED Category IV IV IV
Repair
Any repair or modification, including the replacement of moving parts:
- Must follow local regulations and be made by qualified
operators and in accordance with qualified 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 qualified operators.
- An indication of any modification or repair must be shown in
the monitoring and maintenance file.
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.
- 10 000 cycles (start-ups) during the whole lifetime.
Corrosion allowances:
Gas side: 0 mm
Painted parts : 0 mm
Heat exchange fluid side: 1 mm for tubular plates in lightly alloyed
steels,1 mm for water box 0 mm for stainless steel plates or plates
with copper-nickel or stainless steel protection.
If any part of the piece (with 0mm of acceptable corrosion) shows
corrosion, change the piece
12.2.1 - 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 fluid.
The maximum standard operating pressures are 2100 kPa relative
for the refrigerant side and 1000 kPa relative for the water-side.
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.
III III III III III IV
IV /
IV IV IV IV IV
III
IV
IV /
IV