Equipment for extraction with liquid CO2 on a commercial scale

2 Equipment for extraction with liquid CO2 on a commercial scale 

It is constructed of stainless steel and the welded connections are X-ray tested at every joint to ensure safety. It has been in operation for ten years and has a replacement value in excess of 3 million. 

The extract solution enters the condenser-evaporator through the shell side of a shell and tube evaporator. The energy required for the evaporation of CO2 from liquid to gas (latent heat only 42 cal/g) is provided by the re-liquified CO2 from the re-compressor passing through the tube side of the evaporator. Thus the heat from the reclaimed CO2 on its passage back to the CO2 tank is used to provide heat for the evaporation of liquid CO2 to gas in the condenser-evaporator a very energy-efficient process. This is a patented system (chapter 4). The circuit is then complete and the CO2 circulates to the columns again [10]. 

The optimum extraction conditions for any given material are established by evaluation of a series of experiments in which the following variables are adjusted (i) pressure, (ii) temperature, (iii) particle size profile of the. botanical material, (iv) throughput ratio of CO2 to botanical. 

The best conditions are those which give the extract with the best odour and taste. Often these do not give the maximum yield (some botanical materials contain lipids which are of little or no flavour value, but will extract under severe conditions of processing). 

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