Profroid MiniCO2OLcompact Notice D'instructions page 51

2.2.8 Injection valve AKV
If the discharge temperature of the MT rack reaches a maximum value on the order of 115°C defined in the controller, the AKV
expansion device controlled by the discharge temperature sensor will inject liquid at the inlet of the subcooler into the degasing
line, in order to reduce MT compressor suction superheat. In parallel, an additional minimum suction superheat control is done to
avoid superheat to become too low.
2.2.9 Miscellaneous
Filter drier on the liquid line (must be replaced after 48hrs of operation).
Safety valves on liquid receiver.
Vertical liquid receiver(s).
Option: heat recovery module.
Filter upstream HP valve on the gas cooler return line (to be cleaned after the first 200hrs of operation).
2.2.10 Standstill pressure
Standard service pressures (PS) of the racks are 30 bar at LT booster suction and 45 bar at MT suction rack suction, and also for the
MP liquid receiver and liquid line.
In those conditions an emergency condensing unit is recommended to maintain the receiver pressure below the service pressure
during scheduled stops. This unit must be installed above the receiver if remotely connected (thermo-siphon).
This unit must use a separate uninterrupted power supply in order to avoid any risk of safety valve activation in case of power shut
down of the main power supply.
Additional service pressure levels are available under request (52/60/80 bar). Please refer to the machine name plate.
2.2.11 Intercooler
Depending on the operating conditions, especially in case of high ambient temperature and/or high LT/MT load ratio (higher than
50%), it is recommended to install an external de-superheater (intercooler) on the LT discharge line.
2.2.12 Parallel compression
Parallel compression (also called ECO compressor) can be offered as an option. In that specific case, one or two compressors (out of the 6
compressors in total at the MT stage) have their suction line directly connected to the receiver and take over the role of the MP valves
beyond a certain opening degree. The main benefit of that solution is the energy efficiency in transcritical mode with a dedicated
compression stage to compress the vapor created at the outlet of the HP expansion valve. The first parallel compressor is equipped with an
inverter and the oil management is adapted to ensure proper oil feeding to the parallel compressor(s) which run at higher suction pressure
than the remaining MT compressors (see chapter 2.2.6).
The below schematics shows the example of a compression parallel solution.