CO2 system for retrofitting in food processing company

CO2 was chosen over an ammonia cascade plant
The food processing company Exquisite recently replaced 22 independent systems at its plant in Melbourne, which manufactures high-quality ice-cream, by a single, centralized two-stage transcritical CO2 system. The retrofitting was supported by a 50% grant from Ausindustry under the ReTooling for Climate Change program. CO2 was chosen over an ammonia cascade plant, because of the presence of residential properties nearby and a potential plant noise problem. The new system is used to carry out all the required blast freezing, cold and chilled-process water cooling, the heating of the tap water for sanitary and factory cleaning purposes. Process hot water is also generated to provide air-conditioning reheat and space heating for the premises. The plant includes nine Bitzer CO2 compressors, comprising two air-conditioning and three high-stage transcritical compressors, plus one common standby system and three boosters including one standby system. All the compressors are equipped with variable speed drives. One of the most critical aspects of the system is oil management, for which purpose each transcritical compressor is equipped with an oil separator, while the three boosters share one unit. Problems were also experienced with the control of flash gas between the +10 and the +5°C and the +5 and -10°C vessels. Power consumption is expected to drop 33% and and natural gas consumption is expected to decrease 60%.

Climate Control News, June 2012