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Five Calculation Requirements for Supercritical CO2 Extraction Machine Design

After the structural type of the process equipment is determined, it is necessary to calculate the main components.

The supercritical CO2 fluid extraction vessel generally works at a high pressure of 32Mpa (sometimes possibly higher), and is often disassembled. It is a high-pressure pressure vessel, and its strength design is the difficulty and key to the strength design of the entire supercritical CO2 extraction equipment. When the shell of the CO2 extraction vessel is opened, if the hole diameter exceeds the maximum hole diameter allowed without additional reinforcement, the reinforcement area must be calculated according to the requirements.

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Calculation Requirement 1# – Wall Thickness of CO2 Extraction Vessel

In small and medium-sized supercritical CO2 fluid extraction equipment, fatigue analysis is usually not performed, because the volume of small and medium-sized equipment is small, and the wall thickness of the supercritical CO2 extraction container is also small, so the safety factor can be increased when calculating the strength. Ways to deal with it, so that only the strength problem can be considered.
Before calculating the wall thickness of the CO2 extraction vessel, it is necessary to determine the relevant design parameters of the supercritical CO2 fluid extraction vessel according to the operating conditions.

Calculation Requirement 2# – CO2 Extraction Vessel Head

Most of the heads of high-pressure vessels are flat covers, especially small-diameter high-pressure vessels. Because flat caps are easy to manufacture and are suitable for a variety of seals, flat-end caps can be selected.

Calculation Requirement 3# – CO2 Extraction Vessel Cap Thread

Considering that the cap thread of the supercritical CO2 extraction vessel mainly bears single-phase axial force, a zigzag thread can be selected.

Calculation Requirement 4# – CO2 Extraction Vessel Support

Supercritical CO2 extraction equipment generally adopts skirt support, which needs to be checked for strength.

Calculation Requirement 5# – Shell and tube heat exchanger

The calculation of a heat exchanger as a pressure vessel is the same as that of a general vessel, but there are also specific strength calculations for heat exchangers, including the calculation of the temperature difference stress caused by the temperature difference between the tube wall and the shell, the calculation of the thickness of the tube sheet, and the calculation of the tube tension. The calculation of the pull-off force; when the pull-off force is too large, the calculation of the expansion joint must be selected. Since the calculation process is relatively complicated, and the Standardization Committee has recommended calculation software, you can use the software calculation directly when necessary, please check the relevant information.

Read more: Supercritical carbon dioxide