High temperature and high pressure reactorIt is the core equipment for high-pressure and high-temperature reactions in the fields of chemical engineering, materials, biomedicine, etc. The accuracy of its pressure and temperature parameters and the sealing of the equipment are directly related to experimental safety and data reliability. The following are specific calibration and leak detection methods:
1、 Calibration method for high temperature and high pressure reaction kettle
Calibration should be conducted regularly (recommended every 6 months), with priority given to using standard instrument comparison methods. The core calibration parameters are temperature and pressure.
1. Temperature calibration
preparation
Prepare standard thermocouple thermometers (with an accuracy of not less than 0.1 ℃) and temperature inspection instruments that have passed metrological verification, ensuring that there are no significant temperature fluctuations in the calibration environment.
Open the lid of the reaction vessel, fix the standard thermocouple probe and the built-in temperature measuring element inside the vessel at the same temperature measuring point (such as in the middle of the vessel cavity, avoiding contact with the vessel wall), and seal the lid.
Calibration steps
Set the target temperature for the temperature control system of the reaction kettle (it is recommended to select 3 calibration points, such as 100 ℃, 200 ℃, 300 ℃, covering the common temperature range), and start the heating program.
After the temperature stabilizes, record the displayed values of the built-in temperature measuring element in the reaction kettle and the measured values of the standard thermocouple, and calculate the difference between the two.
If the temperature difference exceeds ± 2 ℃, it is necessary to enter the temperature control system calibration interface and correct the equipment reading according to the standard value; If you are unable to make corrections on your own, contact the manufacturer's professional personnel for debugging.
Verification after calibration
After calibration is completed, set the temperature at any calibration point again, confirm that the displayed value deviates from the standard value within the allowable range (≤± 1 ℃), record the calibration data and archive it.
2. Pressure calibration
preparation
Prepare standard pressure gauges/pressure sensors (with an accuracy of not less than 0.05 level) and pressure connection adapters that have been verified and qualified, ensuring that the pipeline is leak free.
Close the inlet/outlet valves of the reactor and connect the standard pressure gauge to the backup pressure interface of the reactor body through an adapter (if there is no backup interface, the original pressure gauge on the reactor can be temporarily replaced).
Calibration steps
Slowly introduce inert gas (such as nitrogen) into the reaction vessel, and gradually increase the pressure to three calibration points (such as 1MPa, 5MPa, 10MPa, matching the commonly used pressure range of the equipment). Wait for the pressure to stabilize and hold for 5 minutes.
Record the displayed value of the built-in pressure gauge of the reaction kettle and the measured value of the standard pressure gauge separately, and calculate the deviation value.
If the pressure deviation exceeds ± 0.05MPa, the built-in pressure gauge needs to be zeroed or range corrected; For intelligent reaction vessels, parameter correction can be achieved through the pressure calibration module of the control system.
Post calibration processing
After calibration is qualified, remove the standard pressure gauge, restore the original pipeline, release pressure to atmospheric pressure, and record the calibration ledger (including calibration time, instrument model, deviation value, etc.).
IIHigh temperature and high pressure reactorThe leak detection method
Leak detection requires preliminary testing under no-load and normal temperature conditions, and then combined with temperature and pressure rise conditions for review. The commonly used methods are as follows:
1. Static pressure holding leak detection method (basic leak detection, suitable for routine sealing inspection)
operating steps
Close all valves of the reaction kettle, introduce inert gas into the kettle to 80% of the rated working pressure, close the inlet valve, and start timing.
Record the pressure value inside the kettle every 10 minutes and observe continuously for 30 minutes.
Judgment criteria: If the pressure drop within 30 minutes is ≤ 1% of the rated pressure, it indicates good sealing performance; If the pressure drop exceeds the standard, the leakage point needs to be investigated.
Leakage point location
Prepare soapy water and evenly apply it to the sealing surface of the kettle cover, valve joints, pipeline welds, and other areas that are prone to leakage.
If there are continuous bubbles in a certain area, it is a leakage point, which should be marked and treated with pressure relief.
2. Vacuum leak detection method (applicable to reaction vessels with high sealing requirements)
operating steps
Close all pathways of the kettle body, connect the vacuum pump to evacuate the kettle to a vacuum degree of ≤ 10Pa, and close the connection valve between the vacuum pump and the kettle body.
Let it stand for 1 hour and observe the changes in the vacuum gauge reading.
Judgment criteria: If the vacuum degree rebound value is ≤ 5Pa/h, it indicates no obvious leakage; If the rebound is too fast, further investigation is needed.
auxiliary positioning
If an abnormal increase in vacuum degree is found, acetone/ethanol can be sprayed onto the suspicious area outside the kettle. If the vacuum gauge reading suddenly fluctuates, it indicates that there is a leak in that area (organic solvent vapor entering the kettle causing a change in vacuum degree).
3. Leak detection method for heating conditions (rechecking sealing performance at high temperatures)
operating steps
After completing the room temperature pressure leak detection, fill the kettle with inert gas to the working pressure, start the heating system to raise the temperature to the common reaction temperature, and keep it warm for 30 minutes.
Observe pressure changes and apply soap water to areas prone to leakage to confirm sealing performance under high temperature and pressure conditions.
Attention: During the heating process, it is necessary to slowly increase the pressure to avoid damage to the sealing components caused by sudden changes in temperature and pressure.
3、 General precautions for calibration and leak detection
Before calibration and leak detection, it is necessary to ensure that the reaction vessel is in an unloaded, cooled, and depressurized state, and it is strictly prohibited to operate with materials or under high temperature and high pressure.
The standard instruments used for calibration must be within the valid period of calibration, and the range must match the calibrated parameters (to avoid using beyond the range).
The soap water used for leak detection should be free of impurities to avoid residual blockages in the pipeline; During vacuum leak detection, it is necessary to prevent the vacuum pump oil from being sucked back into the kettle.
If leakage is caused by aging of the sealing components (such as cracking or deformation of the O-ring on the kettle cover), it is necessary to replace the original sealing components of the same model in a timely manner, and it is strictly prohibited to mix non-standard components.
After each calibration and leak detection, equipment maintenance records need to be filled out as the basis for equipment measurement and safety assessment.