Can industrial multi temperature zone rotary furnaces be evacuated?

Industrial multi temperature zone rotary furnaces can be evacuated, and vacuum function is one of their core advantages, especially suitable for thermosensitive materials, high-purity materials, and process scenarios that require strict control of oxidation reactions. The following analysis will be conducted from four aspects: technical implementation, application scenarios, advantages, and typical cases:

1. Technical Implementation: Core Design of Vacuum System
The industrial multi temperature zone rotary furnace achieves vacuum function through the following key designs:
Vacuum sealing structure
Dynamic sealing: using labyrinth sealing, gas sealing or magnetic fluid sealing technology to ensure that the furnace body can still maintain a high vacuum degree (usually ≤ 10Pa) during rotation. For example, a lithium battery material drying furnace adopts a two-stage labyrinth seal, which has a lower leakage rate.
Static sealing: Metal O-rings or fluororubber seals are used for the inlet, outlet, and observation window, combined with a quick opening and closing mechanism to reduce vacuum failure time (usually<5 minutes).
Vacuum pump group configuration
Pre stage pump: rotary vane pump or water ring pump, used for rough vacuum pumping (reducing pressure from atmospheric pressure to below 10 ³ Pa).
Main pump: Roots pump or molecular pump, used in high vacuum stage (pressure drops from 10 ³ Pa to below 10 ⁻ ² Pa). For example, a semiconductor material sintering furnace uses a three-stage pump set (rotary vane pump+Roots pump+molecular pump), with a maximum vacuum degree of 5 × 10 ⁻ Pa.
Vacuum monitoring and control
Sensor: Used in combination with Pirani vacuum gauge (measuring range 10 ³ -1Pa) and ionization vacuum gauge (measuring range 10 ⁻² -10 ⁻⁶ Pa) to provide real-time feedback on vacuum level.
Control system: PLC automatically adjusts the operating frequency of the pump group based on the vacuum degree to maintain the target pressure (such as during the drying of lithium battery materials, the vacuum degree remains stable at 50 ± 5Pa).
Leak-proof design
Furnace body material: Made of 316L stainless steel or Hastelloy alloy to reduce material release rate.
Welding process: The seam of the furnace body is welded using argon arc welding or electron beam welding to ensure no leakage points. For example, the weld seam of a certain pharmaceutical micro powder drying furnace was detected by helium mass spectrometry, resulting in a lower leakage rate.

2. Core application scenarios of vacuum function
Drying of thermosensitive materials
Case: Drying of whey protein powder
Requirement: Quickly remove moisture at low temperatures (60-80 ℃) to prevent protein denaturation.
Solution: Use a vacuum rotary furnace (pressure 50-100Pa) to evaporate water at low temperatures and reduce protein denaturation rate.
Effect: After drying, the protein content is higher, the solubility is higher, and it meets food grade standards.
Preparation of high-purity materials
Case: Drying of Semiconductor Silicon Powder
Requirement: Remove surface adsorbed water and organic impurities to prevent metal contamination.
Solution: Use a vacuum rotary furnace (pressure 10 ⁻ Pa), combined with high temperature (300-400 ℃) baking, to reduce impurity content.
Effect: After drying, the purity of silicon powder is higher, meeting the requirements of the semiconductor industry.
Oxidation sensitive material treatment
Case: Sintering of Titanium Alloy Powder
Requirement: To prevent Ti from reacting with O ₂/N ₂ at high temperatures to form TiO ₂/TiN.
Solution: Use a vacuum rotary furnace (pressure 10 ⁻ ³ Pa) to sinter at 1200-1400 ℃ with less oxygen content.
Effect: After sintering, the titanium alloy has a higher density and tensile strength.
Solvent Recycling and Environmental Protection Treatment
Case: Drying of pharmaceutical intermediates
Requirement: Recycling organic solvents (such as ethanol and acetone) to reduce VOCs emissions.
Solution: Adopt a vacuum rotary furnace (pressure 10 ³ Pa), combined with a condenser to recover solvents, resulting in a higher recovery rate.
Effect: After drying, there is less solvent residue and lower VOCs emission concentration, which meets environmental protection requirements.

3. Significant advantages of vacuum function
Reduce process temperature
In a vacuum environment, the boiling point of materials significantly decreases (such as the boiling point of water dropping to 7 ℃ at 100Pa), allowing for rapid drying/sintering at low temperatures and reducing thermal damage. For example, in the drying of bioactive substances, vacuum reduces the temperature from 120 ℃ to 60 ℃, resulting in an increase in activity retention rate.
Inhibit oxidation reaction
Vacuum environment isolates O ₂/N ₂ to prevent oxidation and degradation of metals (such as Ti, Al) or organic compounds (such as active pharmaceutical ingredients). For example, in titanium alloy sintering, vacuum reduces oxygen content and significantly improves material properties.
Improve product purity
Vacuum environment reduces the adsorption of gas impurities (such as H ₂ O, CO ₂), combined with high-temperature baking to remove surface adsorbed impurities and improve product purity. For example, in the drying of semiconductor silicon powder, vacuum reduces the impurity content from 1ppm to 0.1ppm.
Shorten process time
In a vacuum environment, the internal pressure of the material is lower than the external pressure, which promotes rapid diffusion of moisture/solvents and shortens drying/sintering time. For example, in the drying of lithium battery materials, vacuum reduces the drying time from 8 hours to 3 hours, increasing production capacity.