Here’s a detailed overview of High-Pressure Pumps & CO₂ Delivery Systems in Supercritical Fluid Extraction (SFE), focusing on their function, design, and operational considerations:
1. Role in SFE
High-pressure pumps and CO₂ delivery systems are critical components that ensure the supercritical fluid reaches the extraction vessel at the required pressure, flow rate, and consistency.
- Maintain constant supercritical conditions (above Tc and Pc)
- Deliver CO₂ at controlled flow rates for reproducible extraction
- Support process scalability (lab → pilot → industrial)
2. High-Pressure Pump Types
a. Piston/Plunger Pumps
- Most common for SFE
- Positive displacement → precise flow control
- Can reach pressures up to 600 bar or more
- Good for CO₂ and co-solvents
b. Diaphragm Pumps
- Use a flexible diaphragm to push fluid
- Less common for supercritical CO₂ due to pressure limitations
- Useful for solvent modifiers or low-flow applications
c. Syringe Pumps (Lab Scale)
- Used in lab-scale SFE
- Very precise, but limited capacity and scalability
3. CO₂ Delivery System Components
- CO₂ Storage Cylinder
- High-pressure gas or liquid CO₂ source
- Equipped with pressure regulators and valves
- Chiller / Cooling System
- CO₂ is cooled below Tc before pressurization to maintain density
- Prevents cavitation in pumps
- High-Pressure Pump
- Delivers CO₂ to extraction vessel at constant, programmable flow and pressure
- Check Valves & Safety Reliefs
- Prevent backflow and protect system from overpressure
- Flow Meters & Pressure Sensors
- Real-time monitoring of flow rate, pressure, and system stability
- Heating System (Optional)
- Raises CO₂ to supercritical temperature before entering extraction vessel
4. Operational Considerations
- Pressure Control: Maintain steady pressure above critical point for consistent extraction
- Flow Rate: Determines extraction kinetics and yield
- Pump Maintenance: Regular inspection for wear, seals, and leaks due to high pressure
- Safety: High-pressure systems require relief valves, burst disks, and proper venting
5. Scalability
- Lab-scale: Syringe or small plunger pumps (up to 100 bar)
- Pilot-scale: Plunger/piston pumps (100–300 bar, 1–20 L/min)
- Industrial-scale: Multi-stage pumps (300–600 bar, 50+ L/min), often with CO₂ recycling
6. Summary Table
| Component | Function / Benefit |
|---|---|
| CO₂ Cylinder | Supply supercritical CO₂ |
| Chiller / Cooler | Maintain CO₂ density, prevent cavitation |
| High-Pressure Pump | Deliver CO₂ at precise flow and pressure |
| Valves & Safety Relief | Protect system from overpressure |
| Sensors & Flow Meters | Monitor process for reproducibility |
| Heater (if needed) | Bring CO₂ to supercritical temperature |
✅ Bottom Line:
High-pressure pumps and CO₂ delivery systems ensure precise, controlled, and safe operation of SFE, directly impacting yield, selectivity, and product quality. Proper design, maintenance, and monitoring are essential for reproducible extraction and scale-up.
I can also create a visual diagram showing a CO₂ delivery system: cylinder → cooler → high-pressure pump → extraction vessel → separator, with sensors and safety valves highlighted.
Do you want me to create that diagram?