Can gas be supplied to industrial multi temperature zone rotary furnaces?

The industrial multi temperature zone rotary furnace can pass gas, and gas injection is one of its core functions, which can meet the strict requirements of atmosphere control for powder drying, sintering, calcination and other processes. The following analysis will be conducted from four aspects: technical principles, gas types, application scenarios, and typical cases:

1. Technical principle: Implementation method of gas introduction
The industrial multi temperature zone rotary furnace achieves gas inlet through the following design:
Partition gas pipeline system
The furnace body is divided into multiple temperature zones along the axial direction (such as preheating zone, reaction zone, cooling zone), and each temperature zone is independently equipped with gas inlet and outlet, supporting the introduction of different gases into different temperature zones (such as H ₂ reduction in the front section, N ₂ protection in the middle section, and air cooling in the rear section).
Gas distribution device
Gas nozzles or distribution plates are installed inside the furnace to ensure uniform gas penetration into the material layer, avoiding local concentrations that are too high or too low. For example, in metal powder sintering, H ₂ gas is uniformly sprayed through a nozzle at a flow rate of 0.5-2m/s to ensure sufficient reduction of iron oxide.
Sealing and pressure control
The furnace body adopts a dynamic sealing structure (such as labyrinth seal, gas seal), combined with pressure sensors and regulating valves, to maintain a slight positive pressure inside the furnace and prevent external air from infiltrating. For example, in the drying of lithium battery materials, the furnace pressure is controlled at+100Pa, and the O ₂ concentration remains stable at<1%.
Exhaust gas treatment system
The gas outlet is connected to an incinerator, washing tower, or catalytic oxidation device to treat exhaust gases containing volatile organic compounds (VOCs), dust, or harmful gases, ensuring compliance with emission standards.

2. Types and functions of gases that can be introduced
Inert gases (N ₂, Ar): Metal powder sintering, lithium battery material drying, oxygen isolation, to prevent material oxidation (such as in stainless steel powder sintering, N ₂ protection reduces decarburization rate).
Reductive gases (H ₂, CO): sintering of hard alloys, reduction of iron oxide, reduction of metal oxides (such as in WC Co sintering, H ₂ reduces Fe ₂ O3 to Fe, improving material density).
Oxidative gases (O ₂, air): ceramic materials are calcined and organic matter is burned to provide an oxidizing environment (such as in the calcination of Al ₂ O3 ceramics, air completely decomposes organic additives).
Vacuum environment: drying of thermosensitive materials, preparation of high-purity materials, reducing boiling point and minimizing thermal damage.
Mixed gas (N ₂+H ₂): Special alloy sintering, balancing protection and reduction (such as in titanium aluminum alloy sintering, 5% H ₂+95% N ₂ mixed gas prevents Ti oxidation while reducing surface oxides).

3. Core application scenarios for gas injection
Metal powder sintering
Case: Sintering of Hard Alloy (WC Co)
Gas requirements: The front section is filled with H ₂ (800-1000 ℃) to reduce Fe ₂ O Ⅲ impurities, the middle section is filled with N ₂ (1000-1400 ℃) to prevent Co volatilization, and the rear section is filled with Ar for rapid cooling to suppress grain growth.
Effect: The uniformity of cobalt phase distribution is improved, the bending strength of the product is greater, and the pass rate is increased.
Drying of lithium battery materials
Case: Drying of ternary positive electrode material (NCM811)
Gas requirement: The entire process is filled with O ₂ (5% -10%) to prevent Ni ² ⁺ from being reduced to Ni ⁰ (causing material capacity decay); The rear section is cooled with N ₂ to prevent the decomposition of Li ₂ CO ∝.
Effect: After drying, the O ₂ content of the powder is less than 0.1%, the moisture content is reduced, and the dispersibility of the slurry is improved.
Pharmaceutical micro powder drying
Case: Drying of antibiotic raw material (amoxicillin)
Gas requirement: N ₂ (O ₂ concentration<0.5%) to prevent drug oxidation and degradation; Dry air is used to balance moisture in the rear section.
Effect: After drying, the retention rate of active ingredients is better, the moisture content is lower, and it meets the standards.
Ceramic material calcination
Case: Calcination of alumina ceramics
Gas requirement: Air (with an O ₂ concentration of 21%) is supplied to completely decompose organic additives (such as polyvinyl alcohol) at 600-800 ℃, avoiding residual carbon from affecting dielectric properties.
Effect: After calcination, the ceramic body has a higher density and lower dielectric loss.