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CO2 Extraction Pumps: Basics, Top 3 Requirements, 6 Applications, 8 Features

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The supercritical CO2 extraction pump is one of the important equipments in the supercritical CO2 fluid extraction process. It undertakes the task of boosting and conveying CO2. The CO2 extraction pump currently used is mainly a plunger pump. As the "heart" part of the whole extraction system, its normal operation has a great influence on the normal operation of the whole set of equipment.The supercritical CO2 extraction pump is a low-speed reciprocating high-pressure pump. As the key equipment of the supercritical CO2 extraction machine, it can be widely used in biological, pharmaceutical, food, and other fields.

What are CO2 extraction pumps

Pumps are commonly used equipment for conveying liquid media.
In the supercritical CO2 fluid extraction process, it needs to be used to transport fluids, such as supercritical CO2 fluids, entrainers or liquid solutes. The high-pressure pump process shows the advantages of large CO2 flow, low noise, low energy consumption, and stable and reliable operation. Condensation and heat exchange equipment. At present, the supercritical CO2 extraction and booster devices above medium size generally use high-pressure pumps, which can operate at large flow rates and ensure long-term continuous use at higher pressures. Supercritical CO2 extraction pump has the advantages of simple structure, easy maintenance, easy troubleshooting, low cost, and mass production, so it is highly valued by people.

Technical introduction

The CO2 extraction process of CO2 essential oil under a supercritical fluid state places special demands on the supercritical co2 extraction pump technology. Wetted parts in the liquid end of the pump are optimized for this purpose. The arising compression heat is dissipated by cooling channels in the stuffing box barrel as well as in the valve block. The CO2 extraction pumps use horizontal three plungers and five plungers forms. The plunger material stainless steel spray colmonoyalloy, and pure ceramic plunger, wear durable, reliable healthy; the supercritical CO2 fluid extraction pump fluid end comes with a cooling system.

  • The CO2 extraction pumps are usually horizontal, three-plunger, single-acting reciprocating pumps. The CO2 extraction pump is specially developed for the supercritical CO2 extraction process. It is used to transport liquid CO2, and can also transport liquid oxygen, liquid nitrogen, liquid butene, and other media.
  • The supercritical CO2 pump is composed of a power end, a hydraulic end, a transmission part, and a motor. The whole pump is installed on a base, which has the advantages of a compact structure and high efficiency.
  • The supercritical co2 extraction pump is equipped with a variable frequency speed regulating motor, and the displacement of the pump can be adjusted within a certain range with the change of load. It can also be customized with an explosion-proof motor, the CO2 extraction pump can be used in places where explosion-proof is required. It can also be equipped with an electric control box according to user needs.
CO2 extraction pumps
CO2 extraction pumps

Top 3 technical requirements

A supercritical CO2 extraction pump is one of the important pieces of equipment in the process of supercritical CO2 fluid extraction. It undertakes the task of boosting and conveying CO2. The high-pressure pump currently used is mainly a plunger pump. As the “heart” part of the whole extraction system, its normal operation has a great influence on the normal operation of the whole set of equipment.

Sealed and high-pressure resistant

However, the supercritical CO2 extraction pump is the most prone to failure in the entire system, mainly because the density of supercritical CO2 fluid is similar to that of liquid, and the viscosity is 1/10 of that of liquid, which has good fluidity and permeability. , In the process of supercritical CO2 transportation, there are many unfavorable factors, which make the sealing problem more prominent. Therefore, in supercritical CO2 fluid extraction, the pump should also have good sealing performance and high-pressure resistance.

No vibration in working condition

Moreover, supercritical fluid has a certain compressibility, when it works under high-pressure differences (inlet and outlet pressure difference), it will affect the delivery volume of the CO2 extraction pump, and the pump head is also susceptible to shock and vibration. Therefore, it is required that the selected CO2 extraction pump should be equipped with a voltage regulator to absorb the pulsation of the pump, which can reduce the pulsation value of the pump flow and discharge pressure, and make the valve work smoothly.

Wear resistance

In addition, because the supercritical CO2 extraction pump relies on the reciprocating motion of the plunger rod to transport liquid CO2 when the plunger rod is exposed to the air, the CO2 on its surface will volatilize rapidly and the plunger will become dry and lose lubrication, making the column The wear between the plug rod and the plunger sleeve increases, resulting in loss of sealing performance.
To ensure the normal operation of the supercritical CO2 extraction pump, the following three problems should be solved:

  • Maintain the correct method of operation;
  • The plunger rod has good wear resistance;
  • Good wettability is maintained between the plunger rod and the plunger sleeve so that the sealing performance is stable.

CO2 extraction pump structure

The CO2 extraction pumps consist of a power end, a liquid end, a transmission part, and an electric motor.

Driver end

  • The base is a box-type structure, and the lower part of the crank end of the base is designed as an oil pool for storing lubricating oil. The friction pair at the power end is lubricated by the splashed lubricating oil and scraped lubricating oil when the crankshaft and connecting rod move. The amount of lubricating oil in the lubricating oil pool is displayed on the oil mark on the side of the CO2 extraction pump.
  • A small oil pool is designed in the machine base on the upper part of the crosshead slide hole, and a small hole is drilled in the upper center of each crosshead slideway hole. The lubricating oil carried by the crankshaft when the circular crank rotates is guided into the oil pool by the oil scraper, which lubricates the crosshead through the hole.
  • The big end of the connecting rod is made of 08 high tin alloy thin-walled bearing bush, and the small end of the connecting rod is made of a bronze bushing.
  • The cross-head pin is in dynamic fit with the cross-head pinhole, and the cross-head pin is inserted into the pinhole and supported with a jacking wire.
  • When the middle intermediate rod reciprocates, the lubricating oil at the power end is sealed by the anti-vibration sealing ring installed on it.

Liquid end

  • The liquid cylinder is a rectangular integral type, according to the different transport mediums, choose a different material. The CO2 extraction pump cylinder of the CO2 extraction machine is 3O4SS stainless steel generally.
  • Suction and discharge valves are ball valves.
  • The surface of the piston is ceramic, and (the hardness is HRC>58.
  • Piston seal using the best wear resistance carbon fiber ring.
  • The packing box is (the interlayer cooling structure and the liquid cylinder has a cooling hole, and the cooling water flows into the cooling layer of the stuffing box through the cooling hole of the liquid cylinder, thus achieving the overall cooling effect of the liquid cylinder and the stuffing box.
  • The exposed surface of the piston is lubricated by the CO2 extraction pump of the supercritical co2 extraction machine lubricating system itself.
  • The safety valve is installed on the cylinder in order to protect the CO2 extraction pump of the supercritical co2 extractor. The pressure of operating the valve is 1.05-1.1 times the rated pressure in general.
  • The assembly of the driver is the makeup of the big and small belt wheels, a set of narrow bells, and a protective cover.

Work Principle

The motor drives the crankshaft of the CO2 extraction pump to rotate through the large and small pulleys and the narrow belt, and the crankshaft drives the connecting rod and the plunger to reciprocate. When the plunger moves backward, the suction valve opens, and the liquid enters the CO2 extraction pump body until the plunger moves to the rearmost position (the crankshaft rotates 180 degrees) and the suction process ends. The plunger starts to move forward. At this time, the liquid in the inner cavity of the CO2 extraction pump body is squeezed and the pressure rises, so the suction valve is closed, the discharge valve is opened, and the liquid is pushed by the plunger to be discharged through the discharge valve.

8 Features

  1. Lubrication method: oil bath splash lubrication;
  2. Deceleration mode: belt deceleration and gear deceleration;
  3. Flow regulation: adopt speed regulating motor or frequency conversion speed regulation;
  4. The suction and discharge valve of the liquid end: poppet valve or ball valve;
  5. Plunger seal: it is a single-stage seal, and its stuffing box is jacket-cooled;
  6. Plunger: metal spray-welded plunger, integral ceramic plunger, surface sprayed ceramic plunger; liquid end: 304SS high-quality stainless steel, the liquid cylinder body has a cooling process hole, which forms a circuit with the jacket stuffing box, which can be connected to an external coolant ;
  7. The overload protection method of the pump: there are safety valves, electric contact pressure gauges, and pressure sensors to choose from;
  8. CO2 cooling method: The plunger cooling lubrication system is provided in the pump.

6 Applications

  1. Extraction processes with supercritical CO2 (Supercritical Fluid Extraction SFE), such as decaffeination, degreasing, and phytoextraction, as well as the extraction of oil seed, omega fish oil, flavors, and spices
  2. Supercritical preparative liquid chromatography (Supercritical Fluid Chromatography SFC), as well as the separation of optically active substances
  3. Supercritical Fluid Reactions SFR
  4. Particle formation (e. g., Particles from Gas Saturated Solutions PGSS), such as high-pressure spraying process for pulverizing greases, baked goods, etc.
  5. Cleaning processes, e.g., process integrated separation of substances, such as pesticide removal (wool grease, lanolin)
  6. Cell breakdown, inactivation (gentle sterilization)
The complete process of extracting rose essential oil with a CO2 extraction machine
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