Supercritical Fluid Technology (SF) is a technology that utilizes the special properties of supercritical fluids for physical or chemical processes. A supercritical fluid (SF) is a fluid at or above a critical temperature and pressure, which combines the properties of a gas and a liquid, such as high diffusivity and good solubility. Carbon dioxide is a commonly used supercritical fluid due to its low critical temperature, chemical stability, ease of access and safety.
Guidelines for Supercritical Fluid Operations:
1. **Understanding the Basics**:
- Supercritical Fluid Extraction (SFE) utilizes the property that the solvency of supercritical fluids varies with density to extract and separate substances by varying the pressure and temperature .
2. **Equipment Components**:
- Supercritical fluid extraction equipment usually includes extraction kettle, separation kettle, distillation column, high pressure pump, heat exchange system, flow meter, temperature and pressure control system.
3. **Operating Procedure**:
- Preparation stage: check the integrity of the equipment, ensure that all connected parts are free of leaks, preheat the system.
- Sample loading: put the substance to be extracted into the extraction kettle.
- Parameter setting: Adjust pressure, temperature and fluid flow according to the target substance.
- Start extraction: Start the high-pressure pump to input supercritical fluid, which passes through the extraction kettle and comes into contact with the sample to dissolve the target substance.
- Separation and purification: Separate the supercritical fluid from the target substance by lowering the pressure or changing the temperature.
- Collection of product: The separated target substance is collected.
4. **Safety Precautions**:
- Strictly follow the operating procedures to avoid the risk of operation under ultra-high pressure and ultra-high temperature conditions.
- Regularly check the integrity of equipment, especially pressure vessels and piping.
- Use safety devices such as safety valves and pressure relief devices to prevent overpressurization.
- Operators need to be professionally trained in the characteristics of the equipment and the measures to be taken in case of emergency.
5. **Maintenance**:
- Regularly clean and inspect the equipment, especially the high pressure pump and heat exchange system.
- Inspect and replace worn seals and gaskets.
- Keep software up to date to ensure the accuracy and reliability of the control system.
6. **Application areas**:
- Supercritical fluid technology is widely used in food, chemical, pharmaceutical, environmental protection, material science and other fields .
7. **Environmental protection and economy**:
- SFE technology usually uses CO2 as a solvent, which is environmentally friendly and has no solvent residue, in line with the requirements of modern green chemistry .
8. **Technology Development Trend**:
- With the development of technology, supercritical fluid technology has gentler operating conditions, higher extraction efficiency and wider application.
With the above guidelines, the safe, effective and economic operation of supercritical fluid technology can be ensured.