Apart from pressure, temperature, and flow control, which features improve the utility of a SCFE system
Following features improve the utility of a supercritical fluid extraction system- in addition to pressure, temperature, and flow control - that is in addition to pressure, temperature, and flow rate:
● Co-solvent Pump
● Automation
● Intuitive User Interface
● Ergonomics
SCFE, also called supercritical extraction, uses a supercritical fluid (SCF) for the purpose of separating the required compound (called target molecule). An SCF is one that is at a :
● Pressure above its critical pressure; and
● Temperature above its critical temperature.
In the supercritical state, the solvent power of the fluid depends on its pressure. Solvent power is the capacity to dissolve the required target molecule. Solvent power of the supercritical fluid rises with pressure and vice versa. The same is true of the relationship between its solvent power and temperature.
More importantly, at a set pressure (and / or temperature), the SCF will dissolve only one particular target molecule while leaving other compounds in the raw material relatively untouched. This has a direct bearing on the accuracy of the process, and this is the reason why pressure and temperature control are so crucial to the success of supercritical extraction.
Flow control is important because it controls the amount of time the supercritical fluid will be in touch with the raw material. It has a direct impact on the yield, efficiency, and mass transfer rate.
Let us now consider the other factors:
● Co-solvent Pump: Is a useful addition to the SCFE setup for diversifying the compounds that can be extracted. It adds a co-solvent to the supercritical fluid in the required proportion.
Take the case of SCFE using carbon dioxide (CO2) i.e. CO2 SCFE. Supercritical carbon dioxide (sCO2) is good at isolating non-polar compounds from raw materials. Addition of co-solvents such as ethanol, water, and methanol in minor quantities makes it capable of extracting polar compounds as well.
● Automation: Ensures the error free operation of supercritical extraction, or any other engineering system for that matter. During the addition of co-solvent via the co-solvent pump for example, automation mixes it in the required proportion.
Top SCFE equipment manufacturers use rapid extractor changeover valves to minimize downtime, something that automation makes possible.
These are just a couple of examples. The benefits of automation extend across the entire installation in the form of greater productivity, efficiency, and safety. Extractors in the SCFE set up operate at higher pressure and separators at lower pressure. Pressure control and change is absolutely necessary for the success of extraction - something which automation deals with effortlessly.
● Intuitive User Interface: Helps the operator better understand the process flow. This way, the operator is at ease when in front of the interface. Please note, setups have their own design and workflow. Grasping their nitty gritty is essential to monitor and control them in an improved manner.
● Ergonomics: Relates to operator comfort. A simple consideration will be the location of extractors and separators. If they are so positioned that it is easy to load and unload them, we have an ergonomic design. At least, in part.