How does the experimental multi zone rotary furnace work?

The experimental multi zone rotary furnace achieves efficient processing of materials under complex process conditions through precise temperature control, dynamic heating mechanism, and atmosphere regulation system. Its working principle can be decomposed into the following core steps:

1. Structural composition and basic functions
Furnace structure
Multi temperature zone design: The furnace body is divided into multiple independent temperature zones along the axial direction (such as preheating zone, reaction zone, cooling zone), and each temperature zone is equipped with independent heating elements (resistance wires, silicon carbon rods, etc.) and temperature sensors (thermocouples) to achieve temperature gradient control.
Rotary system: The furnace tube is driven by a motor to rotate or tilt 360 °, causing the material to continuously roll during the heating process, avoiding local overheating or underheating.
Sealing and Atmosphere System: Flanged seals are used at both ends of the furnace tube, which can be filled with inert or reducing gases such as nitrogen, argon, and hydrogen to prevent material oxidation or reduction.
control system
PID temperature control module: Each temperature zone is equipped with a PID controller, which adjusts the heating power in real-time based on temperature sensor feedback to ensure temperature fluctuations of ≤± 1 ℃.
PLC/DCS integration: Supports multi-stage program temperature control (such as 30 programmable segments), with preset heating rate, constant temperature time, and cooling curve to meet complex process requirements.
Human computer interaction interface: Set parameters, monitor real-time data, and support data export and fault diagnosis through touch screen or upper computer software.

2. Workflow analysis
Material loading and furnace preparation
Material loading: evenly load the materials to be processed (such as powders, particles, and blocks) into the furnace tube to avoid accumulation and uneven heating.
Atmosphere replacement: After closing the furnace door, use a vacuum pump to evacuate to below 10 ⁻ Pa, and then introduce high-purity inert gas (such as argon) for replacement 3-5 times to ensure that the oxygen content in the furnace is ≤ 1 ppm.
Sealing inspection: Confirm that the flange sealing ring has no leakage, to avoid atmosphere leakage or external air infiltration.
Multi temperature gradient heating
Segmented heating:
Preheating zone: Heat up to 200-500 ℃ at a rate of 5-10 ℃/min to remove adsorbed water and volatile impurities on the surface of the material.
Reaction zone: Set the target temperature (such as 800-1500 ℃) based on the material characteristics, and achieve precise temperature control through an independent temperature control module. For example, lithium iron phosphate cathode material needs to be kept at 750 ℃ for 12 hours to complete crystal transformation.
Cooling zone: using air or water cooling system, controlling the cooling rate (such as 5 ℃/min) to avoid material cracking due to thermal stress.
Dynamic heating: The rotation speed of the furnace tube (0.5-5 rpm) works in conjunction with the temperature gradient to ensure uniform heating of the material. For example, in the synthesis of nanoparticles, rotational motion can prevent particle aggregation and improve the uniformity of particle size distribution.
Atmosphere control and reaction regulation
Atmosphere type selection:
Inert atmosphere: Nitrogen/argon is used to prevent oxidation (such as metal powder sintering).
Reductive atmosphere: Hydrogen/carbon monoxide is used for reducing metal oxides (such as catalyst preparation).
Oxidative atmosphere: Oxygen is used to promote oxidation reactions (such as densification of ceramic materials).
Flow control: Accurately adjust the gas flow rate (such as 100-500 sccm) through a mass flow meter to ensure atmosphere stability.
Pressure regulation: Some furnace types support positive pressure (0.1-0.5 MPa) or negative pressure (vacuum) operation to meet special process requirements.
Cooling and unloading
Natural cooling: After turning off the heating power, the furnace body naturally cools down with the ambient temperature, suitable for materials sensitive to thermal stress.
Forced cooling: Accelerated cooling through air or water cooling systems to shorten the experimental period. For example, lithium battery materials require rapid cooling after sintering to fix the crystal structure.
Atmosphere protection unloading: After cooling to room temperature, maintain an inert atmosphere to prevent oxidation or hydrolysis of the material in contact with air.

3. Key technological advantages
Temperature uniformity: The combination of rotary motion and multi zone temperature control results in a temperature difference of ≤ ± 5 ℃ inside the furnace, which is much better than traditional static furnace types.
Process flexibility: Supports simultaneous processing of multiple materials or stepwise reactions, for example, in the preparation of lithium battery materials, preheating, sintering, and cooling can be completed in the same furnace.
Atmosphere controllability: The sealing system and gas supply module achieve ultra-high purity atmosphere with oxygen content ≤ 1 ppm and dew point ≤ -60 ℃, meeting the requirements of semiconductor material preparation.
Data traceability: The PLC system records temperature, atmosphere, and speed data throughout the entire process, supporting process optimization and quality traceability.

4. Typical application scenarios
Lithium battery materials:
Positive electrode material: Under an oxygen atmosphere, the ordered growth of ternary material layered structure is achieved through a temperature range of 1200 ℃, and the initial charge and discharge efficiency is increased to 92%.
Negative electrode material: Graphitization treatment is completed at 800 ℃ in an argon atmosphere to enhance the conductivity of the material.
Ceramic materials:
Alumina ceramics: achieved densification and sintering through rotational motion at a temperature range of 1600 ℃, with a bending strength of over 400 MPa.
nanometer material:
Nano zinc oxide: Prepare uniformly distributed nanoparticles (D50=30 nm) by controlling the rotation speed in the temperature range of 500 ℃.