Precautions for operating a multi zone rotary furnace for experiments

The operation of a multi zone rotary furnace for experiments involves complex conditions such as high temperature, high pressure, and special atmosphere. Improper operation may cause safety accidents or lead to experimental failure. The following are key precautions during the operation process, covering safety regulations, process control, equipment maintenance, and other aspects:

1. Preparation before operation
Equipment inspection
Sealing test: Check if the sealing ring of the furnace door flange is intact. Use a vacuum pump to evacuate to below 10 ⁻ Pa and maintain pressure for 10 minutes to observe pressure changes and ensure no leakage.
Electrical system inspection: Confirm that the wiring of heating elements, temperature sensors, motors, etc. is secure and there are no short circuits or aging phenomena.
Mechanical component inspection: Check whether the rotating bearings and transmission chains of the furnace tube are lubricated to avoid jamming during operation.
Material Preparation
Loading control: The material filling amount should not exceed 60% of the furnace tube volume to avoid uneven heating or deformation of the furnace tube caused by material accumulation during rotation.
Material uniformity: Powder materials need to be pre mixed evenly, and block materials need to avoid sharp edges scratching the inner wall of the furnace tube.
Compatibility confirmation: Ensure that there is no chemical reaction between the material and the furnace tube material (such as quartz, ceramic, stainless steel), and metal furnace tubes cannot be used for strong acid materials.
Atmosphere system preparation
Gas purity verification: Use high-purity gas (≥ 99.999%) and detect oxygen content ≤ 1 ppm through a gas purity analyzer.
Pipeline blowing: Before introducing gas, blow the pipeline with the target gas for 3-5 minutes to eliminate residual air or impurities.
Pressure test: Hold the pressure at 0.1-0.5 MPa for 5 minutes and check if there is any air leakage at the gas pipeline connection.

2. Standardized operation
Heating and temperature control
Segmented heating: Strictly set the heating rate according to the process curve (such as 5-10 ℃/min) to avoid rapid heating causing thermal stress cracking of the furnace tube.
Temperature calibration: Regularly calibrate the temperature of each temperature zone using standard thermocouples to ensure that the displayed value deviates from the actual value by ≤± 1 ℃.
Overtemperature protection: Set an overtemperature alarm threshold (such as target temperature+10 ℃), and automatically cut off the heating power after triggering.
atmosphere control
Atmosphere switching: When switching gas types, first close the original gas valve, blow with nitrogen for 10 minutes, and then introduce new gas to prevent mixing and explosion.
Stable flow rate: The fluctuation range of gas flow rate is ≤± 5 sccm to avoid sudden changes in flow rate that may affect reaction stability.
Oxygen content monitoring: Real time monitoring of oxygen content in oxidizing or reducing atmospheres to ensure it is within the required range of the process (such as ≤ 5 ppm).
Rotation and speed control
Start sequence: Start the rotating motor first, then start heating up to avoid local overheating when the material is stationary.
Speed adjustment: Adjust the speed according to the characteristics of the material (0.5-5 rpm). For powder materials, the speed should be low (1-2 rpm), and for block materials, it can be appropriately increased.
Abnormal shutdown: If the rotation is stuck or makes abnormal noises, immediately shut down for inspection to avoid motor burnout or furnace tube damage.
Real time monitoring and recording
Data recording: Record temperature, atmosphere flow rate, speed and other parameters every 10 minutes to ensure process traceability.
Video surveillance: Monitor the status of materials through furnace observation windows or cameras to promptly detect abnormalities such as clumping and splashing.
Alarm response: For alarm signals such as overheating, overpressure, gas leakage, etc., it is necessary to respond and handle them within 30 seconds.

3. Post operation processing
Cooling and unloading
Natural cooling: High temperature furnace bodies (>500 ℃) need to be naturally cooled to below 200 ℃ before forced cooling to avoid thermal stress causing furnace tube rupture.
Atmosphere protection: Maintain an inert atmosphere during the cooling process to prevent oxidation or hydrolysis of materials in contact with air.
Unloading sequence: Stop rotating first, then open the furnace door and use high-temperature resistant tools (such as ceramic shovels) to remove the material to avoid burns.
Equipment cleaning and maintenance
Furnace tube cleaning: Wipe the inner wall of the furnace tube with a dust-free cloth to remove material residue and avoid cross contamination.
Sealing ring replacement: Replace the fluororubber or silicone rubber sealing ring every 50 uses or when poor sealing is found.
Heating element inspection: Regularly check whether heating elements such as resistance wires and silicon carbide rods are broken or oxidized, and replace them in a timely manner.
waste gas treatment
Exhaust gas collection: Exhaust gas containing VOCs, acidic gases, or dust is purified through devices such as activated carbon adsorption and alkali spray.
Emission monitoring: Regularly monitor the concentration of exhaust emissions to ensure compliance with environmental standards (such as NOx ≤ 200 mg/m ³).

4. Safety protection and emergency response
Personal Protection
Protective equipment: Wear high-temperature gloves, protective face shields, gas masks, and anti-static work clothes during operation.
Safe distance: Maintain a safe distance of at least 1 meter from the furnace body to avoid high-temperature radiation or splashing injuries.
Emergency plan
Fire treatment: If the materials in the furnace catch fire, immediately cut off the power and gas supply, use dry powder fire extinguishers to extinguish the fire, and strictly prohibit using water to extinguish the fire.
Gas leakage: When a gas leakage is detected, quickly close the gas source valve, open the ventilation system, and evacuate personnel to a safe area.
Equipment malfunction: If the motor is stuck or the temperature is out of control, press the emergency stop button and contact professional maintenance personnel.
Training and Qualification
Operation training: Operators need to undergo professional training to become familiar with equipment principles, process flow, and safety regulations.
Certified for employment: Operators involved in hazardous processes such as high-pressure gas and high-temperature operations must obtain relevant qualification certificates.

5、 Special process precautions
Vacuum process
Vacuum degree control: When vacuuming to below 10 ⁻ Pa, the valve should be slowly opened to avoid sudden pressure changes that may cause deformation of the furnace body.
Vacuum maintenance: In high-temperature vacuum processes, regularly check the oil level and sealing of the vacuum pump to prevent a decrease in vacuum degree.
Reducing atmosphere process
Hydrogen safety: When using hydrogen, a hydrogen concentration detector should be equipped, which will automatically alarm and cut off the gas source when the concentration is ≥ 4%.
Explosion proof measures: The grounding resistance of the furnace body should be ≤ 4 Ω to avoid static electricity causing hydrogen explosions.
Corrosive material process
Material selection: When dealing with strong acid and alkali materials, choose polytetrafluoroethylene (PTFE) lining or Hastelloy furnace tubes.
Waste liquid treatment: The waste liquid after cleaning the furnace tube should be collected according to the hazardous waste treatment process, and direct discharge is strictly prohibited.