Story of a SFE system
A Supercritical Fluid Extraction (SFE) system consists of several components that work together to achieve stable extraction conditions. It starts with the CO2 source.
1. The scale usually dictates the storage method, but in almost all cases we deliver CO2 as a high-pressure liquid.
2. To ensure the CO2 remains a liquid it passes through a heat exchanger, which we call a Condenser. This is usually chilled below 4 °C before entering the high-pressure pump.
3. CO2 pump – We then compress the CO2 to the desired pressure for the extraction.
4. It then travels into a second heat exchanger that is called the Pre-heater. At this stage the CO2 reaches its supercritical state.
6. Extraction vessel – Now we are at the desired temperature and pressure, we flow the CO2over a packed bed of biomass. We begin to extract the desired components in our CO2 stream.
8. Now we need a way of collecting this material while maintaining the flow. To do this we use a pneumatically control back pressure regulator (ABPR) which acts to hold the pressure in our extractor while allowing a flow of CO2 and our material into our first collector.
9. Anyone that has watched a CO2 system in action may have observed Joule-Thomson effect. This is when we go from a high pressure to a low pressure which results in a drop in temperature.
This can cause issues in processing especially with a high content of water in your material. The water freezes and then blocks the pipework.
To overcome this, we use a Vaporiser (another heat exchanger) to heat the CO2 exiting the ABPR. This helps overcome the freezing and expand the CO2 into the gas phase releasing the components of interest into our first separator.
10. The product then enters high-pressure collection assembly and serve as fraction collectors.
11. By adjusting the Manual Back Pressure Regulators (MBPR), we can alter the pressure in the collector.
The CO2 loses its solvating power as the density is decreased, precipitating products from the CO2 feed. The flow path from the final cyclone exits to vent or to an optional CO2 recycler.
Depending whether you are fractionating your products or recycling the CO2 the story of a SFE system remains the same.
And this completes our story, we apply engineering principles to all our designs to create a highly adaptable and efficient extraction system.