Design of reliable carbon dioxide industrial refrigeration plant.

Distinct challenges exist in the design of large carbon dioxide refrigeration plant to assure reliability. The relatively high refrigerant pressures mean that many component design pressures have had to be increased from refrigeration norms and even then components often operate close to their design pressure limits, thus increasing stress and wear and leakage rates. In many cases components have been sourced from outside the refrigeration industry or adapted. Multi megawatt cascade carbon dioxide refrigeration systems often have special defrost arrangements. Many industrial carbon dioxide refrigeration systems use non miscible oil which must be carefully managed within the refrigerant circuit. These factors all bring new design and maintenance
challenges. This paper reviews the unique elements of carbon dioxide systems and presents lessons for design and maintenance engineers based on operational experience with five large systems which have all operated for more than 9 years.