CO2 separation vessel
The supercritical CO2 fluid containing solvent and solute from the CO2 extraction vessel of the CO2 extraction machine needs to be separated under reduced pressure. The device that separates the two is called a CO2 extraction separator, also known as a CO2 separation vessel.
Read More: Supercritical CO2 Fluid
Principle of separation of the supercritical CO2 extraction process
Generally, after the mixed CO2 fluid from the CO2 extraction vessel is decompressed by the pressure-reducing valve, the fluid in the valve outlet pipe is in a two-phase state, that is, there is a gas phase and a liquid phase (or solid phase). If it is a liquid phase, it contains The CO2 extract and solvent are dispersed in the gas phase in the form of small droplets, and the gas-liquid separation is realized by solvent evaporation in the second step.
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Three types of CO2 extraction and separation vessels
Commonly used CO2 extraction and separation vessels, regardless of solid raw materials and liquid raw materials, mainly have the following forms:
Types 1#: Axial inlet CO2 extraction and separation vessel
Axial inlet CO2 extraction separation vessel is the most commonly used form of separation, which uses jacket heating.
The axial intake CO2 extraction and separation container has a simple structure and is convenient to use and sterilize.
However, sometimes when the flow rate of the axial intake air is large, the CO2 extract that is not released in time will be blown up, and the liquid will be entrained out of the separator by CO2, resulting in a decrease in the CO2 extraction efficiency, and in severe cases, the pipeline will be blocked.
Types 2#: Cyclone CO2 Extraction Separation Vessel
The cyclone CO2 extraction and separation vessel is composed of a cyclone chamber and a collection chamber. When the extract is liquid, a receiving chamber at the bottom of the cyclone chamber can be used to collect the extract with low solvent content; when the extract is relatively viscous or paste-like When it is not easy to flow, it can be designed as a movable bottom to receive the extract.
Types 3#: Cyclone CO2 Extraction Separation Vessel with Heat Exchanger
Read More: CO2 Extraction Machine
The cyclone CO2 extraction and separation vessel is characterized by a vertical or inclined shell-and-tube heat exchanger inside the separator, which uses natural convection and forced convection to exchange heat with supercritical CO2 fluid.
When designing or selecting such a CO2 extraction separation vessel, it is necessary to consider whether the extract will be deposited on the surface of the heat exchanger.
For example, in the process of CO2 extraction and separation of hops, a large amount of CO2 extract may adhere to the surface of the heat exchanger, which reduces the heat transfer efficiency and even causes the heat-sensitive deterioration of the CO2 extract.