Precautions for using customized rotary tube furnaces with multiple temperature zones

As a high-precision and highly complex experimental and production equipment, the customized rotary tube furnace with multiple temperature zones must strictly follow the operating specifications to ensure equipment performance, reliability of experimental results, and personnel safety. The following are key precautions during use:

1. Equipment installation and debugging
Environmental requirements
Site selection: Installed indoors in a dry, ventilated, and non corrosive gas environment, away from vibration sources and strong electromagnetic interference (such as large motors and high-frequency equipment), to avoid temperature fluctuations affecting temperature control accuracy.
Horizontal calibration: Use a spirit level to adjust the equipment base, ensuring that the furnace body is level and preventing sample displacement or furnace tube wear caused by tilting during rotation.
Power matching: Configure a dedicated power supply line according to the equipment power (such as 10kW-50kW), ensure voltage stability (such as 380V ± 5%), and install overload protection devices.
Inspection of gas path and vacuum system
Airtightness test: Introduce inert gas (such as argon) to 0.1MPa, and use soapy water to check for air leaks at the furnace tube, flange, and valve connections to ensure the system’s sealing.
Vacuum pump maintenance: Regularly replace the vacuum pump oil, check the pump body temperature (normal ≤ 60 ℃), and avoid oil contamination affecting the vacuum degree (target ≤ 10 ⁻ Pa).
Gas flow calibration: Use a mass flow meter to calibrate the gas flow rate (such as H ₂ flow accuracy ± 0.1SLM) to ensure stable process atmosphere.
Rotating mechanism debugging
Speed setting: Set the rotation speed (usually 1-30rpm) based on the characteristics of the sample (such as powder, film) to avoid splashing or affecting uniformity if the speed is too fast.
Bearing lubrication: Regularly add high-temperature grease (such as molybdenum disulfide) to rotating bearings to reduce wear and extend service life.
Vibration monitoring: Observe the vibration of the furnace body during the initial operation. If the vibration is too large, check the balance of the rotating mechanism or whether the furnace tube is loose.

2. Operating standards
temperature control
Heating rate limit: Set the heating rate based on the thermal stability of the material (such as ≤ 10 ℃/min) to avoid rapid heating that may cause sample cracking or equipment thermal stress damage.
Coordinated control of temperature zones: When multiple temperature zones operate simultaneously, ensure that the temperature gradient in each zone is reasonable (such as a temperature difference between adjacent zones ≤ 200 ℃), and prevent the furnace tube from cracking due to uneven thermal expansion.
Overtemperature protection: Set an overtemperature alarm threshold (such as target temperature+50 ℃), and automatically cut off the heating power and sound an alarm when the temperature is abnormal.
Atmosphere and Vacuum Operation
Atmosphere switching sequence: First evacuate to the target value (such as 10 ⁻⁴ Pa), then introduce protective gas (such as N ₂) to atmospheric pressure, repeat 2-3 times to completely eliminate air and prevent sample oxidation.
Gas purity control: Use high-purity gas (such as 99.999% Ar) to avoid impurities affecting material properties (such as oxygen content in lithium-ion battery materials should be ≤ 500ppm).
Vacuum breaking standard: After the experiment is completed, inert gas should be introduced to atmospheric pressure first, and then the furnace door should be opened to prevent damage to the furnace tube due to internal and external pressure differences.
Sample placement and fixation
Sample size matching: Sample length ≤ effective length of furnace tube (e.g. effective length of Φ 100mm furnace tube ≤ 1200mm), diameter ≤ 70% of furnace tube inner diameter, to avoid collision with furnace wall during rotation.
Uniform distribution requirements: Powder samples should be evenly spread in a boat with a thickness of ≤ 10mm; film samples should be fixed on the substrate to prevent curling or detachment during rotation.
High temperature resistant material selection: Use high-temperature resistant vessels such as alumina and graphite to avoid direct contact between the sample and the furnace tube, which may cause contamination or damage to the furnace tube.

3. Security protection
Personal protective equipment
Operators are required to wear insulated gloves, protective goggles, and dust masks to prevent high-temperature burns, splash injuries, and inhalation of harmful gases (such as H ₂ S, Cl ₂).
When dealing with highly corrosive atmospheres such as Cl ₂, it is necessary to wear chemical protective clothing and a fully enclosed face mask.
Equipment safety device
Emergency stop button: Ensure that the button is prominently located and easily accessible, and can immediately cut off heating, rotation, and gas supply in case of emergency.
Interlock protection: Temperature rise is prohibited when the furnace door is not closed, and reaction gas is prohibited from entering when the vacuum degree does not meet the standard to prevent accidents caused by misoperation.
Fire prevention measures: Fire extinguishers (such as CO ₂ fire extinguishers) should be equipped around the furnace body, and flammable materials should not be stacked. Smoke alarms should be installed in the experimental area.
Emergency response process
Gas leakage: Immediately close the gas source valve, open the ventilation system, evacuate personnel to a safe area, and contact maintenance.
Overtemperature alarm: Press the emergency stop button, check the cause of the temperature control system malfunction (such as thermocouple damage, PID parameter imbalance), repair and recalibrate the temperature.
Vacuum pump failure: Switch to the backup pump, check the oil level, motor or seal of the faulty pump, and replace spare parts if necessary.

4. Maintenance and upkeep
Daily cleaning
After the experiment, clean the powder residue in the furnace with a vacuum cleaner to avoid affecting the purity of the next experiment.
Use a dust-free cloth dipped in alcohol to wipe the inner wall of the furnace tube to remove oil stains or carbon deposits (such as cleaning once a week when dealing with organic materials for a long time).
Regular maintenance
Monthly inspection: tighten the flange bolts of the furnace tube to prevent air leakage; Check whether the heating element (such as silicon molybdenum rod) is broken or oxidized, and replace aging parts in a timely manner.
Quarterly calibration: Use standard thermometers (such as platinum rhodium 10 platinum thermocouples) to calibrate the temperature control accuracy of each temperature zone, ensuring an error of ≤± 1 ℃.
Annual overhaul: Disassemble the furnace and inspect whether the insulation material (such as alumina fiber felt) has collapsed, and replace damaged rotating bearings or sealing rings.
Spare parts Management
Reserve commonly used spare parts (such as thermocouples, heating elements, O-rings) to ensure quick replacement in case of failure and shorten downtime.
Establish a spare parts inventory ledger to record the usage and replacement status, in order to avoid expired or missing spare parts.