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Rubber waste gas has complex components, mainly including organic sulfides (hydrogen sulfide, methyl mercaptan), aromatic hydrocarbons (benzene, toluene), non-methane total hydrocarbons, dust and other pollutants. Combined with waste gas concentration, air volume and component characteristics, combined treatment processes are selected. The mainstream rubber waste gas treatment schemes and applicable scenarios are listed as follows:
Ⅰ. Pretreatment Process (Dust Removal & Organic Condensation Recovery)
The core function of pretreatment is to remove particulate matter and viscous substances in waste gas to protect subsequent core treatment equipment, while recovering part of condensable organic compounds.
1. Bag Dust Removal / Electrostatic Dust Removal
(1) Treatment Principle
Bag dust removal adopts filter bags to intercept dust particles. Electrostatic dust removal charges dust particles through a high-voltage electric field and adsorbs particles on electrode plates.
(2) Applicable Scenarios
Suitable for dusty waste gas generated during rubber mixing and vulcanization processes. It can remove dust with particle size >1μm, and the dust removal efficiency is over 99%.
(3) Process Characteristics
Advantages: Stable operation and low maintenance cost.
Notes: Filter bags and electrode plates shall be cleaned regularly to prevent blockage.
2. Condensation Recovery Method
(1) Treatment Principle
High-boiling organic matter (such as heavy oil and rubber oil) is condensed into liquid by cooling treatment to realize organic recovery.
(2) Applicable Scenarios
Suitable for high-concentration and high-boiling organic waste gas, commonly used as pretreatment or auxiliary recovery process.
(3) Process Characteristics
Advantages: Recover valuable organic substances and reduce the load of subsequent treatment units.
Limitations: Poor treatment effect on low-boiling organic compounds.
Ⅱ. Core Treatment Process (Organic Pollutant Degradation & Odor Removal)
1. Activated Carbon Adsorption Method
(1) Treatment Principle
The porous structure of activated carbon is utilized to adsorb organic molecules and sulfides in waste gas.
(2) Applicable Scenarios
Suitable for rubber waste gas with low concentration and large air volume, especially for intermittent exhaust gas.
(3) Process Characteristics
Advantages: Simple equipment, low investment cost and convenient operation.
Notes: Saturated activated carbon shall be regenerated or replaced to avoid secondary pollution. It has limited adsorption capacity for inorganic sulfides such as hydrogen sulfide.
2. Catalytic Oxidation (CO) / Regenerative Catalytic Oxidation (RCO)
(1) Treatment Principle
Catalytic Oxidation (CO): Under the action of catalysts (such as platinum and palladium), organic waste gas is oxidized and decomposed into CO₂ and H₂O at a low temperature of 200–400℃.
Regenerative Catalytic Oxidation (RCO): Heat regenerators are added to recover combustion heat for air preheating, reducing energy consumption with thermal efficiency higher than 95%.
(2) Applicable Scenarios
Suitable for organic waste gas with medium and high concentration (1000–5000mg/m³), applicable to continuous exhaust gas from rubber vulcanization and regeneration processes.
(3) Process Characteristics
Advantages: High treatment efficiency (>95%), no secondary pollution and low energy consumption (RCO is more energy-saving).
Limitations: High equipment investment. Catalysts are vulnerable to dust and sulfur poisoning, hence strict pretreatment is required.
3. Regenerative Thermal Oxidation (RTO)
(1) Treatment Principle
Waste gas is directly burned and decomposed at a high temperature of 750–850℃. Heat regenerators recover waste heat to preheat inlet gas.
(2) Applicable Scenarios
Suitable for high-concentration rubber waste gas with complex components, especially waste gas containing refractory organic matter and high sulfur content.
(3) Process Characteristics
Advantages: High treatment efficiency (>99%), strong adaptability and no catalyst dependence.
Limitations: High operating temperature and high energy consumption; explosion-proof measures are mandatory.
4. Biological Treatment Method (Biotrickling Filter / Biofilter)
(1) Treatment Principle
Microbial metabolism is applied to decompose organic pollutants and sulfides into harmless substances such as CO₂, H₂O and sulfate.
(2) Applicable Scenarios
Suitable for low-concentration (<1000mg/m³) and biodegradable rubber waste gas, especially for odor-oriented flue gas.
(3) Process Characteristics
Advantages: Low operating cost, no secondary pollution and simple operation.
Limitations: Treatment efficiency is greatly affected by temperature and humidity; long startup cycle; not applicable for high-concentration waste gas.
5. Photocatalytic Oxidation / Low-temperature Plasma Method
(1) Treatment Principle
Photocatalytic Oxidation: Ultraviolet rays excite catalysts such as TiO₂ to generate hydroxyl radicals for organic oxidation and decomposition.
Low-temperature Plasma: High-voltage discharge generates high-energy particles to crack organic molecules and sulfides.
(2) Applicable Scenarios
Suitable for rubber waste gas with low concentration and low air volume, usually used as auxiliary treatment combined with activated carbon or biological method.
(3) Process Characteristics
Advantages: Small equipment footprint and simple operation.
Limitations: Limited independent treatment efficiency; by-products such as ozone may be generated.
Ⅲ. Combined Treatment Process (Mainstream Recommended Schemes)
Due to the complex components of rubber waste gas, a single process hardly meets emission standards. In practical engineering, the combined scheme of pretreatment + core treatment is widely adopted:
1. Low-concentration, Large-air-volume and Dusty Waste Gas
Bag Dust Removal → Activated Carbon Adsorption → Standard Discharge
2. Medium-concentration Continuous Organic Waste Gas
Bag Dust Removal → Regenerative Catalytic Oxidation (RCO) → Standard Discharge
3. High-concentration Complex Waste Gas
Electrostatic Dust Removal → Regenerative Thermal Oxidation (RTO) → Standard Discharge
4. Low-concentration Odor-oriented Waste Gas
Water Washing Pretreatment → Biotrickling Filter → Standard Discharge
Ⅳ. Key Factors for Scheme Selection
1. Waste Gas Parameters
Including concentration, air volume, composition, temperature and humidity.
2. Emission Standard Requirements
Comply with local environmental protection regulations (limit values of non-methane hydrocarbons and sulfides).
3. Investment and Operating Cost
RTO and RCO have high investment but thorough purification effect; biological method and activated carbon method feature low investment but frequent maintenance.
4. Safety Factors
Explosion-proof and leakage prevention measures shall be equipped for high-concentration organic waste gas treatment.
