The main components used in the supercritical CO2 extraction machine are Heat Exchangers, CO2 Extraction Vessels (CO2 extraction kettle), CO2 Separation Vessels (CO2 separation kettle), Storage Tanks, etc.
Read more: Supercritical carbon dioxide
Four major components 1#: heat exchanger
What is a heat exchanger?
Heat exchangers are widely used in chemical production. Different heat transfer methods can be divided into partition heat exchangers, direct heat exchangers, and regenerative heat exchangers.
- Direct contact heat exchanger: Direct contact heat exchanger is the direct contact between two (cold and hot) fluids after they enter the heat exchanger, transfer heat, and have high heat transfer efficiency, but the use is limited, only applicable to allow these two where fluids are mixed.
- Regenerative heat exchanger: A regenerative heat exchanger is a space (regenerator) filled with a regenerator, and two fluids with different temperatures pass through the regenerator alternately one after another to achieve indirect heat transfer. The method is inefficient and requires two fluids to be allowed to mix.
- Dividing wall heat exchanger: The most widely used in chemical production is the dividing wall heat exchanger, which means that two fluids with different temperatures transfer heat through the wall (tube wall) through which the fluid flows, and the two fluids do not contact each other. This heat transfer method is most suitable for chemical production.
According to the shape of the partition wall, the partition wall heat exchanger can be divided into shell and tube heat exchanger with tube wall heat transfer and plate heat exchanger with plate wall heat transfer.
The heat exchanger in the supercritical CO2 fluid extraction process is a wall heat exchanger, and its main function is to make the CO2 fluid and biomass (extraction material) reach the operating temperature before entering the CO2 extraction vessel, and rise to the temperature before entering the CO2 separator vessel. High temperature to facilitate separation, etc.
Four major components 2#: CO2 extraction vessels
The CO2 extraction vessel (also called the CO2 extraction kettle) is one of the key components in the supercritical CO2 extraction machine.
According to the different CO2 extraction processes and feeding methods, it can be divided into continuous countercurrent CO2 extraction vessel (CO2 fractionation technology, the equipment is also called CO2 fractionation column) and intermittent operation CO2 extraction vessel.
- At present, for liquid materials, a continuous countercurrent CO2 extraction vessel (supercritical CO2 fractionation technology, the equipment is also called CO2 fractionation column) is generally used, which has the advantages of simple operation, good material contact, and easy temperature control.
- For solid materials, batch CO2 extraction vessels are mostly used, because solid materials are not easy to achieve continuous operation.
At present, the design and manufacturing capacity of supercritical CO2 fluid extraction vessels in China has reached the world’s advanced level, from desktop CO2 extractors to small CO2 extraction machines to industrial CO2 extraction machines of more than 3000L.
New CO2 extraction vessels
Since the structural design of the CO2 extraction vessel (CO2 extraction kettle) directly affects the production cost and product quality, many manufacturers in the world are actively researching and adopting new CO2 extraction vessels with more reasonable structures.
- For example, the quick-opening device of the CO2 extraction container adopts an automatic quick-opening device for the top cover and bottom head, which is very convenient for material loading and unloading.
- The multi-layer cylinder extraction kettle adopts the inner wall heating and cooling type structure, that is, there are many longitudinal grooves in the inner wall of the cylinder, and circulating water is introduced into them, which can make the temperature control easier.
- BIT’s CO2 extraction vessel is a multi-layered cylinder structure, and adopts a clamp-type quick-opening structure, with a jacket outside the cylinder to ensure the stability of the extraction temperature during operation.
Read More: CO2 Extraction Vessels
Four Major Components 3#: CO2 separation vessels
The role of the CO2 separation vessel is to effectively separate the extract and the extractant.
The supercritical CO2 fluid carrying a large amount of solute from the top of the CO2 extraction container of the supercritical CO2 extraction machine first enters the heat exchanger, the temperature of the supercritical CO2 fluid rises, and the pressure also increases after reaching the CO2 separation container (CO2 separation kettle). Further reduction, the solubility of the supercritical CO2 fluid drops rapidly, and a large amount of solute is released from the supercritical CO2 fluid and flows out from the bottom of the CO2 separation vessel (CO2 separation kettle).
Four Major Components 4#: Storage Tank
Storage tanks are indispensable in the supercritical CO2 fluid extraction process. According to the use, there are mainly storage containers, metering containers, reflux containers, intermediate turnover containers, buffer containers, and mixing containers.
- Buffer container: The main purpose is to accumulate a certain amount of substances, so as to ensure the stability of the flow operation in the process flow. Therefore, after pretreatment, the extractant, entertainer, and liquid materials need to enter the buffer first.
- Mixing vessel: A mixing vessel is sometimes needed in supercritical fluid extraction, such as the mixing of extractant and entrainer before entering the extraction kettle.
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