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Design of continuous CO2 extractor with piston silo chain

Piston silo CO2 extraction kettle and seal structure design

In order to extract the mixture of different components in the piston silo, different piston silos can be designed for staged pressure extraction. The staged pressure is set to 10MPa. According to the design requirements, the maximum pressure is 50MPa, that is, the extraction pressure of each stage is set to 10, 20, 30, 40, 50, 40, 30, 20, and 10MPa, and a total of 9 piston bins are required. During the continuous extraction process, the pressure in the piston bins of each extraction kettle is gradually increased from 10 to 50MPa, and then from 50 ~10MPa step-by-step decompression.

Design Of Continuous CO2 Extractor With Piston Silo Chain
 Piston bunker extraction kettle and
seal structure: Front gland 2. Front cover 3. V-shaped dust-blocking ring 4. End face seal O-ring 5. Piston chamber body 6. Metal mesh 7. Radial seal O-ring 8. rear gland

According to the test and simulation results, the polyurethane material is used as the dynamic sealing form of the O-ring. Since the V-shaped dust-blocking ring can effectively improve the life of the O-ring, a V-shaped dust-blocking ring is installed on the extraction kettle. During continuous extraction, The extraction kettle moves in one direction in the cylinder, so a V-shaped dust-blocking ring is installed, and an O-ring is installed on the left and right sides for sealing. Considering the leakage of the end face, the end face sealing ring is designed. Since the polyurethane material is relatively hard, it is easy to seal. circle installation.

Structure design

Wherein the front gland and the front end cover are threaded and pressed, the rear gland is threaded and compressed with the piston chamber body, and the piston chamber and the front end cover are threaded.
The front and rear glands are set in a cross-shaped concave-convex structure, which is convenient for multiple piston silos to be connected into a silo chain through this structure to achieve continuous extraction.
The piston chamber has a built-in metal mesh, and the solid mixture to be separated is placed in it. live
The plug bin body has a through the hole with a diameter of 1.5mm, and there is a 1.5mm annular gap between its outer wall and the inner wall of the extraction cylinder.
The supercritical fluid passes through the metal mesh through the upper inlet hole, contacts with the mixture in the metal mesh, and then flows out through the lower outlet hole to realize the extraction process in the piston chamber.

Structural design of piston silo chain continuous CO2 extractor

According to the process of supercritical fluid extraction, the structure of the designed piston silo chain continuous extractor is shown in the figure below.

Design Of Continuous CO2 Extractor With Piston Silo Chain
The structure of a continuous extractor with
piston bin chain: Hydraulic device 2. Place table 3. Hydraulic cylinder 4. Clamping device 5. Cylinder 6. Change
Heater 7. Piston silo extraction kettle 8. Inlet tube 9. Pressure regulating valve 10. A drain pipe 11. gold
Belonging to the net 12. through hole

After the gas from the carbon dioxide storage tank is preheated and pressurized, it becomes a supercritical CO2 fluid and passes through the pressure regulating valve to adjust the pressure to the extraction pressure required by each level. The through hole enters the inside of the metal mesh and extracts the mixture to be separated, and is discharged through the discharge pipe, and then becomes carbon dioxide gas after decompression, and the extract is precipitated. The carbon dioxide gas is pre-cooled and then enters the storage tank for repeated use.

Structural design

Before supercritical CO2 extraction, the process of the mixture entering the piston silo is carried out outside the extraction process. When the piston silo to be extracted is to be incorporated into the silo chain, it is put into a hydraulic device and connected to the front piston silo through the cross joint plugged in and clamped by hydraulic cylinders at both ends when a piston silo supercritical CO2 extraction is completed, the extraction residue needs to be taken out and the solid phase extract is loaded again, the clamping devices at both ends are controlled by electrical and hydraulic pressure to release At this time, the hydraulic cylinders at both ends are still clamped, the hydraulic cylinder on the discharge side on the left shrinks, and the hydraulic cylinder on the inlet side on the right advances, and the piston silo that needs to be extracted is pushed into the cylinder while the piston silo that has been extracted is discharged, and the extraction is completed. After this action, the clamping devices at both ends are clamped again.


For the convenience of operation, the two ends are provided with placing platforms, which are not in contact with the silo chain, and are only used as a temporary place for the piston silo when the silo chain is put in and removed from the silo chain.

Since the loading and unloading are all carried out outside the extraction cylinder, the extraction process has realized continuous operation. Compared with the intermittent operation using the quick-opening sealing structure, the energy loss during each loading and unloading is reduced, and it is also The explosion accident caused by the failure of the quick-opening sealing structure after repeated operations are avoided, and the extraction efficiency is improved.

In conclusion

To improve extraction efficiency and realize graded continuous extraction under different pressures, a chain-type continuous extractor with a piston silo is designed, which provides a continuous extraction process realization method, which is reliable in the co2 extraction equipment process and easy to manufacture.

Compared with the double-screw feeding method, this piston silo chain-type continuous feeding and unloading device can effectively solve the problem that the solid extract is damaged and easily blocked during the feeding and unloading process. At the same time, the pressure in different silos can be adjusted. Realize the process of step-by-step pressure increase and step-down during the extraction process, and realize the continuous extraction of different components of the extract. Compared with single-pressure continuous extraction equipment, the extraction range is wider.

More experiments are needed for piston seal research and extractor design with a higher pressure range (50~100MPa) and larger diameter. The influence on the dynamic seal is also a key research point when the extract is solid powder. Consider designing a new type of sealing structure to resist the influence of solid powder to achieve effective sealing and continuous and efficient extraction of supercritical fluid.

Read More: Piston Chamber Continuous CO2 Extraction Vessel