What are the desirable qualities of CO2 SCFE equipment?

Supercritical fluid extraction (SCFE) is gaining increasing acceptance in the food and beverage, pharmaceutical, nutraceutical, and chemical industries. This is largely due to the ability of the process to separate the required molecule (target molecule) in its relatively pure form. Not only does the selectivity reduce the costs involved in post processing, it also helps honor the increasingly stringent regulations on safety, quality, purity, and toxicity in the said industries. 

Many countries are legalizing cannabis for medicinal and recreational use as its tremendous health benefits become increasingly apparent. SCFE setups and particularly CO2 SCFE systems are being increasingly used as cannabis extraction equipment. They are also used for the extraction process of essential oils, spices, algae, hops, phytochemicals, caffeine, flavors and fragrances, and herbal medicines. 

Carbon dioxide and water are the two most used supercritical fluids (SCFs). The SCF extraction process first increases the pressure and temperature respectively above the critical pressure and temperature of the fluid to take it in the supercritical state. The solvent power of the SCF depends on its density. In turn, the density depends on pressure and temperature. 

By carefully controlling the pressure, the solvent power of the SCF is adjusted to a value where it can selectively dissolve the target molecule. Such separation occurs in the extractor at high pressures. Thereafter, the SCF pressure is reduced so that the target molecule separates from the solution with the SCF. 

Desirable features of CO2 SCFE equipment are:

• Precise pressure control
• Continuous flow control
• Automation with intelligent control
• CO2 co-solvent pump
• CO2 recirculation
• High-quality sealing technology
• Quick extractor closure design
• Simple separator design
• Rapid valve changeover

Precise pressure control is at the very heart of the CO2 SCFE process. Therefore, CO2 SCFE equipment must have devices that carefully regulate pressure. Related to accurate pressure monitoring is the systematic reduction of pressure between the extractor and the separator. As mentioned, extractor operates at higher pressure and separator operates at lower pressure. If the pressure is allowed to freely drop between the extractor and separator levels, carbon dioxide will freeze and block the process equipment. 

The said temperature fall occurs according to the Joules Thompson Principle, which states that if the pressure of a gas drops without the gas performing mechanical work or without heat transfer, then the gas temperature falls. Many equipment suppliers employ cutting edge back pressure regulation valves for SCF extraction in India and the rest of the world. 

Flow rate control is crucial because it influences the yield and efficiency of extraction. 

Automation with intelligent control systems streamlines the SCFE process, thereby optimizing operations. 

Co-solvent pumps add ethanol, water, and methanol to supercritical CO2 (sCO2) to boost its capacity to extract polar compounds. sCO2 is naturally good with isolating non-polar compounds. 

Recirculation disallows CO2 from escaping to the atmosphere where it can produce the greenhouse effect. 

High-quality sealing technology avoids pressure loss and CO2 leakages. 

Rapid valve changeovers and quick extractor closure design maximize uptime and productivity. 

Simple separator design enables quick and easy collection of the product.