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Supercritical fluid plant and equipment including extractor

By Thomas September 28th, 2023 136 views

How to define a supercritical fluid with one simple sentence?

The No.1 of Google entries on the definition of supercritical fluid gives a very concise and perfect answer.

I won't repeat it again here.

As a reactor manufacturer, we look at supercritical fluids more from an application point of view.

Supercritical fluids have high diffusivity and low viscosity of gases. They also have the high density and high solubility of liquids.
This makes the supercritical fluid material can easily enter into other material species, and other materials for complete mixing, so as to realize complete contact.

The physicochemical properties of the fluid near the critical point are susceptible to changes in temperature and pressure, and the properties of the fluid can be adjusted by pressure without changing the chemical composition.
supercritial liquid phases

These fantastic properties of supercritical liquid make the uses of supercritical fluids a hot point for chemistry research and application.

The more mature development is supercritical extraction and coal-fired power generation technology.

 
Equipment design principles

As a company that produces equipment, it is enough to know this application principle of supercritical fluid.

Since chemists and engineers are using the magical properties of materials near the supercritical point to realize the application of supercritical fluids. Then we only need to fabricate equipment that can meet the temperature and pressure requirements of the supercritical point and can realize the manipulation of temperature and pressure to meet the basic needs of chemists and engineers.

First of all, it is not difficult to make a pressure vessel for superfluids.

Summarizing the table below, it can be seen that the following eight commonly used substances can be turned into superfluids simply by keeping the equipment in a certain operating range.

 

Material boiling point Critical point data  
critical temperature
Tc °C
critical pressure
Pc Mpa
critical density
ρc  g/cm3

Carbon dioxide CO2

-78.50 31.06 7.39 0.448

Ethane

-88.00 32.40 4.89 0.203

Ethylene

-103.70 9.50 5.07 0.200

Propane

-44.60 97.00 4.26 0.220

Propylene

-47.70 92.00 4.67 0.230

Ethanol

78.20 243.40 6.38 0.276

Ammonia

-33.40 132.30 11.28 0.240

Water

100.00 374.20 22.00 0.344

That is temperatures from 31.06°C to 374.20°C and pressures from 7.39 MPa to 22.00 MPa.

 

This working condition is very easy for WHGCM. Especially for laboratory reactors, WHGCM can make test kettles with temperatures ranging from -196°C to 500°C, and at the same time with pressures ranging from negative to 52Mpa.

Actually, it is a type of high temperature and high pressure reactor. WHGCM is fully capable of preparing the conditions for superfluid materials.

 

The following figure shows the process diagram of the carbon dioxide supercritical fluid extraction device.

It is mainly divided into three stages

Extraction stage, Separation stage, and Carbon dioxide recovery cycle stage.

 

According to these three stages, the related equipment is described as follows:

First, for the extraction stage.

Transforms the material into a supercritical fluid by simply adding temperature and pressure.

Pressure vessel: Increase the temperature and pressure of the material to transform it into a supercritical fluid state.

1. Heating

In industrial production, cost and efficiency are the first factors to be considered.
Therefore WHGCM provides various thermodynamic devices corresponding to different temperature ranges, such as heat exchangers, electric heating devices, jacketed oil bath heating devices, oil bath water bath circulating tank heating devices, etc., to meet the different needs of customers.

2. Pressurization

Generally, pressurizing pumps are used to pressurize pressure vessels, WHGCM can provide various specifications and models of pressurizing pumps according to different pressure requirements of customers to meet their needs.

Pump:

Press the liquid material into the vessel to bring it to the necessary pressure.

Extractor:

Usually consists of a fixed bed, extraction column, or extraction plate. In this, the sample is in contact with the supercritical fluid material, and the extract to be extracted in the sample will be dissolved into the supercritical fluid fluid material.

Second: Separation stage

Temperature and pressure control devices.

Temperature and pressure control devices are critical to the use of supercritical fluid materials.

As the temperature and pressure conditions of the material are maintained near the supercritical point.
By fine-tuning these two devices to raise or lower the temperature and pressure, it is possible to switch the material back and forth between the gaseous, liquid, and supercritical fluid states.

1. temperature

General use of high and low-temperature circulation machines to control the temperature rise or fall.

a、 high and low-temperature circulation machine

In the material must be, and process flow to determine the situation, there may be only require temperature rise or only require cooling. Then you can choose a relatively low-cost heating device or condensing device.

b、Other Heating devices.
electric heating bar1 electric heating bar 2
Electric Heating Bars I Electric Heating Bars  II
Constant temperature oil tank 1 Constant temperature oil tank 2
Constant temperature oil tank I Constant temperature oil tank II


c、Condenser
Stainless stell condensor

2. Pressure

In general, pressure regulation can be satisfied by reducing the pressure with a pressure relief valve.
Pressure relief valve
                                                            Pressure Relief Valve

3. Splitter

This is where the supercritical fluid material is separated from the extract and is usually a collector.

      Figure Collector

Third: Supercritical Fluid Material Recovery Cycle

1. Material Liquefaction Unit

Generally, a condenser or other low-temperature equipment is mainly used to convert materials from gas to liquid.

2. Intermediate storage tank

Collects liquid materials into storage tanks.

3. High-pressure pump

Press the liquid material into the extractor and recycle it.

 

Supercritical extraction in the pharmaceutical and food industry is now more common, especially in traditional Chinese medicine, and plant extraction, such as flavonoids, terpenes, lipids, and other substances purification.
This is because it has many advantages over other separation processes, such as low operating temperatures, which is a great advantage for the separation of heat-sensitive substances (active ingredients or drugs, etc.); and secondly, the extractant (e.g., carbon dioxide) is non-toxic and harmless, which has no effect on the human body and the environment.

 

Case:

The picture below shows WHGCM's carbon dioxide supercritical extraction kettle and high and low-temperature circulation machine.
CO2 supercritical fluid extractor 1
CO2 supercritical fluid extractor 2

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