In the activated carbon production line, the main differences between the internal heat activation furnace and the external heat activation furnace are reflected in the heating method, thermal efficiency, temperature control, application scenarios, etc. The following is a specific comparison:
Internal Heating Activation Furnace
Direct Heating: The heat source (e.g., gas, steam, or flue gas) directly contacts the material. Combustion-generated heat and activation gases (e.g., steam, CO₂) act simultaneously on the carbonized feedstock.
Heat Source Location: Heat is released inside the furnace via combustion chambers or high-temperature steam injection.
External Heating Activation Furnace
Indirect Heating: The heat source (e.g., gas, electric heating elements) burns outside the furnace wall or in a jacket, transferring heat through the wall to the material.
Heat Source Location: Combustion chambers or heating devices are located outside the furnace, physically isolating the material from the heat source.
Internal Heating
High Thermal Efficiency: Direct heat transfer enables rapid heating and lower energy consumption (typically 20%~30% more efficient than external heating).
Drawback: Some heat may escape with exhaust gases, requiring optimized gas circulation.
External Heating
Lower Thermal Efficiency: Heat loss occurs through furnace walls, resulting in higher energy consumption.
Advantage: Exhaust gases are separated from the material, allowing partial heat recovery.
Internal Heating
Temperature Fluctuations: Direct contact with heat sources may cause localized overheating or uneven temperatures.
Applications: Suitable for standard activated carbon with less stringent temperature uniformity requirements (e.g., industrial wastewater treatment carbon).
External Heating
Stable and Uniform Temperature: Heat is evenly conducted through furnace walls, enabling precise temperature control.
Applications: High-value products (e.g., pharmaceutical-grade or food-grade activated carbon) requiring strict pore structure control.
Internal Heating
Simpler Structure: No complex jackets or external combustion chambers, reducing manufacturing costs.
Maintenance Challenges: High-temperature gases inside the furnace may corrode the chamber, requiring regular carbon deposit removal or refractory material replacement.
External Heating
Complex Structure: Requires high-temperature-resistant walls (e.g., silicon carbide) and insulation layers, leading to higher costs.
Maintenance Advantage: Isolation of material from combustion gases reduces coking and extends furnace lifespan.
Internal Heating
Mixed Activation and Combustion Gases: May introduce impurities (e.g., sulfides), necessitating gas purification.
Rapid Pore Development: High-temperature direct activation suits large-pore activated carbon production.
External Heating
Pure Activation Gases: Steam or CO₂ is injected separately, ensuring high product purity.
Enhanced Microporosity: Gentle heating promotes fine pore structures, improving adsorption performance.
Internal Heating
Large-scale production of standard activated carbon (e.g., for air purification or water treatment).
Feedstock: Coconut shells, fruit shells, coal-based materials.
External Heating
High-purity, high-value activated carbon (e.g., for pharmaceuticals, supercapacitors).
Feedstock: Wood, resin-based materials requiring precise activation.
|
Comparison |
Internal Heating Furnace |
External Heating Furnace |
|
Heating Method |
Direct contact, internal gas flow |
Indirect conduction, external heat |
|
Energy Consumption |
Lower |
Higher |
|
Temperature Uniformity |
Less uniform |
More uniform |
|
Product Purity |
Potential impurities |
High purity |
|
Equipment Cost |
Lower |
Higher |
|
Applications |
Industrial-grade activated carbon |
Food/pharmaceutical-grade, specialty carbon |
Selection Guidelines:
Choose internal heating for low-cost, large-scale production;
Opt for external heating for high-purity products requiring precise temperature control.
