The supercritical CO2 extraction process requires high operating pressure, so safety factors such as production, maintenance, explosion protection, and fire protection must be fully considered in the overall layout to strictly prevent accidents and avoid component explosions. According to the operation experience of petrochemical equipment, two corresponding technical safety measures must be adopted.
Safety Measure 1#: Safety Valve
What is a safety valve?
The function of the safety valve is to reduce the excessive pressure in the container through the automatic opening of the valve to discharge the gas. Its advantage is that when the pressure in the container drops slightly lower than the normal operating pressure, it can be automatically closed, avoiding the waste and interruption of production caused by discharging all the gas once the container is overpressured; it can be reused many times, and the installation and adjustment are relatively easy. But the sealing performance is poor, the opening of the valve has a hysteresis phenomenon, and the pressure relief response is slow.
CO2 extraction pumps safety valve requirements
For high-pressure CO2 extraction pumps, it is necessary to use a pressure gauge with good performance and a matching safety valve to realize overpressure protection. When the pressure in the extraction process exceeds the process requirements due to the blockage of viscous components, the high-pressure pump must be able to stop automatically.
Requirements for safety valves of CO2 extraction vessels
For high-pressure equipment such as CO2 extraction vessels and CO2 separation vessels, matching safety valves should be selected according to their working pressure. In addition, to match the quick-opening structure of the CO2 extraction vessel, a safety protection device such as a manual vent valve must be installed on the top cover of the CO2 extraction vessel. Only when the pressure in the CO2 extraction vessel is confirmed to be zero can the lid be opened to ensure safe production.
Safety Measure 2#: Blast-proof membrane
What is an explosion-proof film?
An explosion-proof membrane is a rupture-type safety relief device. It uses the explosion-proof membrane to break under the calibration pressure to achieve the purpose of pressure relief. After the pressure is released, the explosion-proof membrane cannot continue to be used effectively, and the container is forced to stop running.
Two characteristics of explosion-proof membrane
Although the explosion-proof membrane is a relief device that does not reclose after bursting, it has two characteristics compared with the safety valve:
- First, the airtight performance is good, and it can be completely sealed;
- Second, the rupture speed is fast, and the pressure relief response is rapid.
Therefore, when the safety valve cannot play an effective protective role, an explosion-proof membrane or a combination device of an explosion-proof membrane and a safety valve must be used.
For the CO2 condenser, an explosion-proof membrane must be installed to ensure the safe operation of the equipment. In addition, the management and operators of supercritical CO2 extraction equipment should have the necessary basic knowledge of pressure vessels, understand the difference between working pressure and hydraulic test pressure, and overpressure operation is strictly prohibited.
Read more: Supercritical carbon dioxide