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Ⅰ. Scheme Background and Waste Gas Characteristics
Waste gas generated from rubber production processes (mixing, vulcanization, shaping, etc.) has complex components, mainly including non-methane total hydrocarbons (NMHC), benzene series, sulfides (H₂S, mercaptan), and dust. It is characterized by low concentration, large air volume, strong peculiar smell and drastic component fluctuation. The typical NMHC emission concentration ranges from 50-500mg/m³. Some working conditions contain a small amount of viscous organic compounds. Direct discharge will cause atmospheric pollution and adversely affect the surrounding environment. Aiming at such waste gas, this scheme adopts Catalytic Oxidation (CO) and Regenerative Catalytic Oxidation (RCO) technology to realize dual objectives of waste gas purification and waste heat recovery.
Ⅱ. Core Technical Principle
1. Principle of Catalytic Oxidation (CO)
With the catalytic effect of precious metal catalysts (Pt, Pd) or non-precious metal catalysts (MnO₂, CeO₂), organic pollutants in waste gas are oxidized and decomposed into harmless CO₂ and H₂O at a low temperature of 250-350℃, accompanied by heat release. The chemical reaction formula is shown as follows:
VOCs + O₂ → CO₂ + H₂O + Heat
The catalyst reduces the activation energy of chemical reaction and avoids secondary pollutants such as NOₓ generated by high-temperature combustion.
2. Principle of Regenerative Catalytic Oxidation (RCO)
Based on CO technology, regenerators (ceramic honeycomb, ceramic balls) are added to recycle combustion heat through heat storage and heat release circulation. The raw waste gas is preheated to the reaction temperature by regenerators and then decomposed in the catalytic bed. The high-temperature flue gas after reaction heats another group of regenerators and is discharged below 100℃. The heat storage efficiency is over 90%, which greatly reduces energy consumption and is highly suitable for low-concentration and large-air-volume waste gas.
Ⅲ. Process Selection and Applicable Scenarios
Technology Type | Core Advantages | Applicable Scenarios | Treatment Efficiency | Energy Consumption Level |
|---|---|---|---|---|
Catalytic Oxidation (CO) | Simple equipment, low investment and fast startup | Medium-concentration waste gas (100-500mg/m³), small air volume (≤10000m³/h) and stable components | NMHC removal rate ≥95% | Medium (auxiliary heating required) |
Regenerative Catalytic Oxidation (RCO) | High waste heat recovery efficiency, low operating cost and wide concentration adaptability | Low-concentration waste gas (50-300mg/m³), large air volume (≥10000m³/h) and fluctuating components | NMHC removal rate ≥98% | Low (auxiliary heating only for startup) |
Ⅳ. Complete Treatment Process Flow
1. Pretreatment System (Key Unit)
Rubber waste gas contains dust and viscous organic matter. Strict pretreatment is required to prevent catalyst poisoning and blockage.
(1) Filtration Unit
High-temperature resistant glass fiber filter bags or metal filter screens are adopted to remove dust and colloidal particles larger than 1μm with a filtration efficiency ≥99%.
(2) Adsorption Pretreatment (Optional)
For waste gas with low concentration and high humidity, activated carbon or molecular sieve adsorption layers are equipped to concentrate organic matter and control gas humidity ≤60% to meet the optimal working conditions of catalysts.
(3) Fire Resistance Device
Corrugated flame arrester is installed to prevent backfire. The fire resistance grade meets GB 50058 safety standards.
2. Core Reaction System
(1) Configuration of CO System
Preheating Chamber: Electric or gas heating is adopted to heat pretreated waste gas to 280-320℃ (catalyst activation temperature).
Catalytic Bed: Modular structure with honeycomb ceramic carrier. The specific surface area ≥300m²/g. The catalyst loading capacity is designed according to air volume and concentration with space velocity controlled at 10000-20000h⁻¹.
Thermal Insulation Layer: The equipment shell is insulated with rock wool with a thickness ≥50mm, and the surface temperature is controlled ≤60℃.
(2) Configuration of RCO System
Regenerative Chamber: Double-bed or triple-bed structure with ceramic honeycomb regenerators (specific surface area ≥400m²/m³). The switching cycle is 30-90 seconds, and the preheating efficiency ≥92%.
Catalytic Bed: Consistent catalyst selection with CO system. The catalytic bed is arranged behind the regenerative chamber to trigger oxidation reaction by high-temperature preheated flue gas.
Switching Valve: High-temperature resistant pneumatic switching valve with excellent tightness and switching response time ≤1 second to ensure continuous system operation.
3. Post-treatment and Waste Heat Utilization
(1) Tail Gas Discharge
Purified tail gas is discharged through a high-altitude chimney (height ≥15m). All indicators comply with the Emission Standard of Pollutants for Rubber Products Industry (GB 27632-2011): NMHC ≤120mg/m³, Benzene ≤4mg/m³, H₂S ≤10mg/m³.
(2) Waste Heat Recovery (Optional)
The high-temperature waste heat generated by the RCO system can be used for production water heating and workshop heating through heat exchangers. The heat recovery efficiency ≥85% to reduce enterprise energy consumption.
Ⅴ. Key Technical Parameters and Equipment Selection
Parameter Name | CO System | RCO System |
|---|---|---|
Treatment Air Volume | 1000-10000m³/h | 5000-50000m³/h |
Reaction Temperature | 280-350℃ | 300-380℃ |
Catalyst Service Life | 2-3 years (normal working condition) | 3-5 years (normal working condition) |
System Resistance | ≤2000Pa | ≤3000Pa |
Startup Time | ≤30 minutes | ≤60 minutes |
Energy Consumption (10000m³/h) | Power consumption: 30-50kW・h | Power consumption: 10-20kW・h (no auxiliary heating after startup) |
Ⅵ. Safety and Operation Guarantee Measures
1. Safety Protection Measures
Temperature, pressure and concentration sensors are installed to monitor operating status in real time. The bypass valve will be automatically opened with an alarm when gas concentration ≥1000mg/m³ or temperature ≥400℃.
A nitrogen purging device is configured to replace residual organic matter in catalytic beds and pipelines during shutdown or failure, preventing carbon deposition and spontaneous combustion.
2. Catalyst Maintenance
Catalyst activity is inspected every 6 months. Regeneration or replacement is required when the NMHC removal rate is lower than 90%.
Toxic substances such as sulfur, chlorine and heavy metals are strictly prohibited. Desulfurization and dechlorination pretreatment units shall be added if toxic components cannot be avoided.
3. Operation Control
PLC automatic control system is adopted for linkage control of fans, heaters and switching valves, supporting remote monitoring and fault alarm.
The minimum concentration threshold is set. When the concentration is lower than 50mg/m³, the system automatically switches to heat preservation mode to reduce energy consumption.
Ⅶ. Scheme Advantages and Economic Analysis
1. Core Advantages
High Purification Efficiency: NMHC removal rate ≥95% (CO) / ≥98% (RCO) with excellent deodorization performance.
Environmental Compliance: All emission indicators meet national standards without secondary pollution.
Strong Adaptability: Suitable for waste gas from all rubber production processes, tolerating concentration fluctuation and a small amount of impurities.
Safe and Reliable: Equipped with complete fire resistance, explosion-proof and alarm systems in line with industrial safety specifications.
2. Economic Analysis (Air Volume: 20000m³/h, NMHC Concentration: 200mg/m³)
Items | Catalytic Oxidation (CO) | Regenerative Catalytic Oxidation (RCO) |
|---|---|---|
Initial Investment | 800,000-1,200,000 RMB | 1,500,000-2,200,000 RMB |
Annual Operating Cost | Electricity + catalyst replacement: 300,000-450,000 RMB | Electricity + catalyst replacement: 150,000-250,000 RMB |
Investment Payback Period | 2-3 years | 3-4 years |
Remarks | Suitable for short-term investment and small-air-volume scenarios | Suitable for long-term operation and large-air-volume scenarios; waste heat recovery further reduces costs |
