Supercritical CO2 fluid extraction equipment

Supercritical extraction technology is the latest subject in modern chemical separation, which is an advanced green separation technology rising in the world. Therefore, supercritical fluid refers to the fluid whose thermodynamic state is above the critical point (PC, TC). The critical point is the state point where the gas-liquid interface just disappears. Supercritical fluid has very unique physical and chemical properties. Its density is close to that of liquid, and its viscosity is close to that of gas, while its diffusion coefficient is large, its viscosity is small, and its dielectric constant is big. It is a good solvent. Supercritical extraction means that the solvent in the extraction cylinder contacts with the extract under high pressure and proper temperature, the solute diffuses into the solvent, and then changes the operating conditions in the separator to separate the solute. This equipment is widely used in biological, pharmaceutical, food, health care products, flavors and fragrances.

Therefore, supercritical fluid is an ideal extractant. Supercritical fluid is a kind of non gaseous and non liquid state between gas and liquid, which can only exist when its temperature and pressure exceed the critical point. The density of supercritical fluid is large, similar to that of liquid, and its viscosity is close to that of gas. Therefore, supercritical fluid is an ideal extractant.

The solvent strength of supercritical fluid depends on the temperature and pressure of extraction. By using this property, only changing the pressure and temperature of the extractant fluid, different components in the sample can be extracted successively according to the solubility in the fluid. The substances with weak polarity can be extracted first under low pressure. With the increase of pressure, the substances with large polarity and large molecular weight and basic properties can be extracted first. Therefore, different extraction can be obtained by supercritical extraction under program pressure Components, but also can play a role in separation.

The change of temperature is reflected in two factors: the density of the extractant and the vapor pressure of the solute. In the low temperature zone (still above the critical temperature), the increase of temperature reduces the density of the fluid, while the increase of the vapor pressure of the solute is not much. Therefore, the increase of temperature when the solvent dissolves can make the solute separate out from the fluid extractant. When the temperature further increases to the high temperature zone, although the density of the extractant However, with the increase of vapor pressure and volatility, the extraction rate will not decrease but increase.

In addition to pressure and temperature, adding a small amount of other solvents in supercritical fluid can also change its solute solubility. Its mechanism has not been fully understood. In general, the addition amount is less than 10%, and most of them are polar solvents such as methanol and isopropanol. By adding a small amount of polar solvent, the scope of application of supercritical extraction technology can be further extended to more polar compounds.

Characteristic:

1. Supercritical extraction can be carried out near room temperature (35-40 ℃) and under the cover of CO2 gas, effectively preventing the oxidation and dissipation of heat sensitive substances. Therefore, the active components of medicinal plants are kept in the extract, and the substances with high boiling point, low volatility and easy pyrolysis can be extracted at a temperature far lower than its boiling point;

2. Supercritical extraction is the cleanest extraction method. Because organic solvent is not used in the whole process, there is no residual solvent in the extract, thus preventing the existence of harmful substances to human body and environmental pollution in the extraction process, and ensuring 100% pure nature;

3. The combination of extraction and separation. When the saturated dissolved CO2 fluid enters the separator, due to the drop of pressure or the change of temperature, the CO2 and the extract quickly become two-phase (gas-liquid separation) and are separated immediately. The extraction efficiency is high and the energy consumption is less, the production efficiency is improved and the cost is reduced;

4. CO2 is a kind of inert gas, which does not occur chemical reaction in the extraction process, and belongs to non combustible gas, tasteless, odorless, non-toxic and very safe;

5. CO2 gas is cheap, high purity, easy to produce, and can be recycled in production, thus effectively reducing the cost;

6. Pressure and temperature can be the parameters for adjusting the extraction process. The purpose of extraction can be achieved by changing the temperature and pressure. The pressure fixing can also separate the substances by changing the temperature. On the contrary, the temperature fixing can separate the extractions by reducing the pressure, because this process is simple and easy to master, and the extraction speed is fast.

II. Main technical parameters:

1. Maximum extraction pressure: 50MPa

2. Extraction volume: 1l-300l

3. Volume of separation kettle: 1-2

4. Extraction temperature: normal temperature ~ 150 ℃, adjustable

5. Maximum flow: 0 ~ 1600L / h adjustable pump head with cooling

6. Double plunger pump: 0-1600l / h adjustable

About extraction technology:

The principle of supercritical CO2 fluid extraction (SFE) separation process is based on the relationship between the solubility of supercritical fluid and its density, that is, the influence of pressure and temperature on the solubility of supercritical fluid. In the supercritical state, the supercritical fluid is contacted with the substance to be separated, so that it can selectively extract the components of polarity, boiling point and molecular weight successively. Of course, it is impossible to obtain a single extract corresponding to each pressure range, but the conditions can be controlled to obtain the proportion of the mixed components, and then by means of decompression and temperature rise, the supercritical fluid will become a common gas, and the extracted material will be completely or basically separated, so as to achieve the purpose of separation and purification. Therefore, the supercritical CO2 fluid extraction process is a combination of extraction and separation processes And become.

Supercritical fluid extraction technology is a modern chemical component