Precautions for using experimental multi zone rotary furnace

The experimental multi zone rotary furnace is a precision heat treatment equipment widely used in experimental scenarios such as material synthesis, sintering, catalytic reactions, etc. Although its multi temperature zone design and rotation function have improved process flexibility, they also put forward higher requirements for operational safety and experimental accuracy. The following are key precautions during use, covering preparation before operation, monitoring during operation, and maintenance:

1. Preparation before operation: Ensure that the equipment is compatible with the experimental conditions
Equipment inspection and calibration
Electrical system: Check if the power and grounding wires are intact to avoid the risk of leakage; Confirm that the wiring inside the control cabinet is not loose to prevent short circuits.
Mechanical structure: Check whether the furnace tube rotating mechanism (such as motor, drive belt) is flexible, whether the tilt angle adjustment device is stuck, and ensure that the rotation function is normal.
Temperature zone calibration: Use standard thermometers or thermocouples to verify the temperature control accuracy of each temperature zone. If the deviation exceeds ± 1 ℃, recalibration is required.
Sealing test: For vacuum rotary furnaces, negative pressure testing (such as vacuuming to -0.1MPa) is required to check for air leaks in flanges, observation windows, and other areas.
Sample matching with furnace tube
Sample size: Ensure that the particle size or block size of the sample is less than one-third of the inner diameter of the furnace tube to avoid jamming or blockage. For example, when processing powders, it is recommended to have a particle size of ≤ 5mm.
Furnace tube material selection: Select materials based on experimental temperature and atmosphere. For example, when dealing with highly corrosive gases, priority should be given to using alumina tubes (Al ₂ O3) or metal tubes (such as Hastelloy); High temperature experiments (>1400 ℃) require silicon carbon tubes heated with silicon molybdenum rods.
Material loading control: The sample filling rate inside the furnace tube should not exceed 60% to prevent material accumulation during rotation, which may cause uneven temperature or mechanical jamming.
Atmosphere and environment configuration
Gas purity: When introducing inert gases (such as Ar, N ₂) or reactive gases (such as H ₂, CO), high-purity gases (≥ 99.99%) should be used to avoid impurity contamination of the sample or corrosion of the furnace tube.
Flow control: Set the gas flow rate according to process requirements (such as 100-500mL/min), and accurately adjust it through a mass flow meter to ensure atmosphere stability.
Exhaust treatment: For toxic or flammable gases (such as H ₂ S, CH ₄), it is necessary to connect exhaust treatment devices (such as scrubbers, incinerators) to prevent environmental pollution or explosion risks.

2. Monitoring during operation: ensuring experimental safety and accuracy
Key points of temperature control
Heating rate: Strictly follow the process curve to set the heating rate (such as 5 ℃/min), to avoid rapid heating that may cause thermal stress cracking of the furnace tube or sample cracking.
Synchronization of temperature zones: When operating in multiple temperature zones, it is necessary to monitor the deviation between the actual temperature in each zone and the set value. If the deviation exceeds ± 2 ℃, the experiment should be paused and the heating element or thermocouple should be checked.
Insulation stage: During the constant temperature period, regularly record temperature fluctuations (such as every 10 minutes) to ensure a fluctuation range of ≤± 1.5 ℃.
Rotation parameter adjustment
Speed control: Adjust the speed according to the material characteristics (such as 1-10 rpm). Powder mixing requires a high rotational speed (≥ 5rpm), while block material processing requires a low rotational speed (≤ 3rpm) to prevent collision damage.
Tilt angle: When inclined discharge is required, first reduce the speed to ≤ 2rpm, and then slowly adjust the angle (such as -5 ° -20 °) to avoid sudden material pouring and damage to the furnace tube.
Safety protection measures
Personal protection: Wear insulated gloves and protective face shields when operating high-temperature equipment to prevent burns or splashes.
Emergency stop: Familiarize yourself with the location of the emergency stop button, and immediately cut off the power and exhaust in case of furnace tube jamming, temperature loss, or gas leakage.
Fire and explosion prevention: Flammable materials are prohibited from being stored within 3 meters around the furnace body. Fire extinguishers (such as CO ₂ fire extinguishers) and sandboxes are equipped in the laboratory.

3. Post experimental processing: extending equipment lifespan
Cooling and discharge
Natural cooling: After the experiment, turn off the heating power but keep the rotation and atmosphere flowing. Wait until the furnace temperature drops below 200 ℃ before stopping the rotation and ventilation to prevent deformation of the furnace tube due to thermal expansion and contraction.
Forced discharge: For materials with strong adhesion (such as molten salt), reverse airflow (such as N ₂) should be introduced at high temperatures to assist in discharge and avoid residue on the inner wall of the furnace tube.
Cleaning and maintenance
Furnace tube cleaning: Use a soft bristled brush or vacuum cleaner to remove residual materials from the furnace tube, and prohibit scratching with hard objects to prevent scratching.
Heating element inspection: Regularly check whether the heating wire, silicon carbon rod or silicon molybdenum rod is oxidized or broken, and replace aging elements in a timely manner.
Lubrication and maintenance: Apply high-temperature lubricating grease (such as molybdenum disulfide) to mechanical components such as rotating bearings and transmission chains every 3 months to reduce wear.
Data recording and archiving
Record the process parameters (temperature, time, speed, atmosphere, etc.), equipment operating status, and abnormal conditions for each experiment, providing a basis for subsequent process optimization.
Save equipment maintenance records (such as component replacement time, calibration date) for easy tracking of equipment lifespan and failure patterns.

4. Common faults and emergency response
Temperature out of control
Reason: thermocouple open circuit, solid-state relay damage, PID parameter imbalance.
Solution: Immediately stop the machine and check the thermocouple connection, replace the faulty relay, and recalibrate the PID parameters.
Furnace tube stuck
Reason: Sample accumulation, broken drive belt, motor malfunction.
Solution: Turn off the heating power and manually rotate the furnace tube to try to remove the jamming; If it is ineffective, the furnace tube needs to be disassembled for cleaning or the transmission components need to be replaced.
Atmosphere leakage
Reason: Aging of flange sealing ring and rupture of observation window.
Solution: Pause the experiment and replace the sealing ring or observation window, and re vacuum test the sealing performance.