Semi-hermetic 4-cylinder compressors for transcritical CO2 applications

Since the beginning of the 90's Bock and leading institutes and manufacturers are concerned with the development of compressors for the transcritical CO2 process. In the last few years, Bock CO2 compressors were established in various applications. The current program of transcritical CO2 compressors with the models RKX26 and HG2 CO2 T is now extended by the 4-cylinder model HG34 CO2 T with capacity stages from 9,8 to 20,1 m³/h.

Important Information

Transcritical CO2 applications are still in the development phase
They require a completely new kind of system and control
They are not a general solution for the substitution of F-gases
We specifically point out that all information in this chapter has been made based on our current level of knowledge and may change at any time due to further development
Compressors can only be made available for selected projects

CO2 as a refrigerant

Within refrigeration technology, carbon dioxide (CO2) is known by the name R744 and has a long history. It is a colourless gas which liquefies under pressure and has a slightly acidic smell. Carbon dioxide has no ozone depletion potential (ODP=0) and a negligible direct effect on global warming (GWP=1) when used as a refrigerant in closed systems. It is not combustible, is chemically inactive and heavier than air. Carbon dioxide has a narcotic and asphyxiating effect on humans only at higher concentrations.

Available models

Designed for CO2 - built for the future

Bock HG34 CO2 T - A compressor packed with more than 15 years of CO2 compressor experience.

Oil supply of bearings through forced lubrication and optimal oil circulation
Low oil throw through a calmed lubrication circuit, minimum oil foaming and oil mist
Calmed oil level for precise and safe indication of oil level in the sightglas
Prevention against oil overfilling
High-strength spheroidal cast iron housing for maximum operating pressures on the low pressure,- and high pressure side
Tempered crankshaft with massive main bearing and optimised mass balance for highest running comfort
Drop-forged, split steel connecting rod with bearing shell and bearing bush for highest dynamic loads and best emergency running properties
Weight-optimised connecting rod for highest running comfort
Smallest possible piston diameter for maximum efficiency with CO2
Highest efficiency through hard chromium plated piston rings in triple assembly
Hardened pistons with anti-friction coating at the piston skirt for minimum wear and high emergency running properties
Piston heads with grooving of the suction reed valves outline for minimum clearance volume
Thermal separations on the cylinder cover and in the compressor housing improve the temperature on the suction side
Valve system with optimised flow and channels in the housing ensure lowest pressure drops and highest efficiency
Thermal protection thermostat installed ex works as standard
Oil sump heater installed ex works as standard

HA design in development In addition, the Bock characteristic features also apply to compressors of the type HG34 CO2 T:

- Easy maintenance, e.g. replaceable motors

- Frequency converter

- Bock MP10 electronic motor protection, especially easy to operate because of status indicators