Supercritical CO₂ for fragrant & oil extraction

The French company SFE Process develops and manufactures equipment for automated extraction of natural compounds from raw materials such as plants for end customers typically within food, perfumery, cosmetics and pharmaceutical industries. The use of supercritical CO₂ allows low temperature extraction of essential oils, aromas or perfumes from a natural product without denaturing it. 
To improve the accuracy and hence the quality of the extraction equipment, SFE Process contacted Bronkhorst France for their flow meters.

What is supercriticial CO₂?

As an effective alternative for volatile organic solvents, supercritical CO₂ - carbon dioxide - has proven its worth. We talk about supercritical fluids when there is no distinct between the gaseous and liquid phase of the fluid. In this case, for CO₂ , this is at temperatures higher than 31° C and pressures > 73 bars. This is called the 'supercritical' state. This state combines useful liquid properties - being a solvent - and gaseous properties - high diffusivity-, making it a good extracting agent. 
 

Process solution

The Bronkhorst solution consists of a Coriolis-based mass flow meter - mini CORI-FLOW M15 series - for the SFE Process' industrial equipment, and a mini CORI-FLOW M14 mass flow meter for laboratory equipment. The flow meters are equipped with the Modbus protocol for communication between the flow instruments and the rest of the SFE Process equipment.

The standard industrial equipment developed by SFE Process is used for pressures up to 400 bars and 100°C. In laboratory applications, the pressure can go up to 1000 bars. The mass flow meters are placed in front of the pump that applies the high pressure to the extractor.

SFE Process’ extraction equipment allows automatic extraction due to a set of pre-recorded recipes that can be fully parameterised according to the raw materials and the to-be-extracted compounds. By integrating a flow meter, it is possible to accurately measure the CO₂ flow and to control this flow continuously to ensure an optimal extraction. The mass of the CO₂ flow is measured as important information to analyse the extraction efficiency.

In addition, the flow meter accurately measures the temperature and density of the carbon dioxide. The temperature is measured to make sure that the CO₂ is supplied in a liquid state before pumping. If necessary, adjustments can be made by e.g. changing the heat exchanger or pump settings. 

Extraction control and monitoring is extremely accurate and is conducted in real-time. Thus, it is a real quality assurance of production, which saves time and money and which improves the process.