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Ⅰ. Scheme Background and Pollution Source Analysis
The core pollutants of black smoke waste gas include particulate matter (PM), sulfur oxides (SOx), nitrogen oxides (NOx), and volatile organic compounds (VOCs). The pollution sources are mainly divided into three categories:
1. Industrial Emission Sources: Black smoke is generated by insufficient combustion or high sulfur content of raw materials in coal-fired boilers, iron and steel smelting, chemical production, waste incineration and other industrial processes.
2. Mobile Emission Sources: Black smoke exhaust is caused by aging engines or poor fuel quality of diesel trucks, ships, construction machinery and other mobile equipment.
3. Scattered Small Sources: Unorganized emissions from catering oil fume, small coal-fired furnaces, and agricultural straw burning cause local black smoke pollution.
Black smoke reduces atmospheric visibility. Harmful substances such as heavy metals and polycyclic aromatic hydrocarbons contained in black smoke will damage human health. Therefore, a targeted treatment scheme is formulated for pollution control.
Ⅱ. Core Treatment Technology System (Classified by Scenarios)
(Ⅰ) Treatment Scheme for Industrial Stationary Source Black Smoke
According to the characteristics of high concentration and continuous emission, a three-stage process of pretreatment + core purification + advanced treatment is adopted.
1. Pretreatment Stage
A gravity settling chamber or cyclone dust collector is installed to remove large particles larger than 10μm and reduce the load of subsequent equipment. A gas-liquid separator is equipped for black smoke containing oil mist and water vapor to prevent equipment corrosion and blockage.
2. Core Purification Stage (Optional or Combined)
Scheme A: Electrostatic Precipitator (ESP): Suitable for large-air-volume waste gas from coal-fired boilers and steel plants. The dust removal efficiency is over 99.5%, which can remove fine particles such as PM2.5. It is matched with a desulfurization tower (limestone-gypsum method) to remove SOx synchronously.
Scheme B: Bag Dust Collector: Suitable for viscous dust-containing waste gas from chemical industry and waste incineration. With high filtration precision, it can intercept fine particles and part of VOCs. Filter bags (PTFE, glass fiber and other materials) need regular replacement.
3. Advanced Treatment Stage
Low-temperature plasma reactor or photocatalytic oxidation equipment is installed to decompose residual VOCs and partial NOx. For excessive nitrogen oxide working conditions, a supporting SCR (Selective Catalytic Reduction) denitrification system is equipped. At 300-400℃, ammonia water converts NOx into nitrogen and water.
(Ⅱ) Treatment Scheme for Mobile Source Black Smoke
1. Motor Vehicles (Mainly Diesel Trucks)
Vehicles are mandatorily equipped with China VI standard exhaust treatment device adopting the combined process of DPF (Diesel Particulate Filter) + SCR. DPF captures particulate matter and realizes high-temperature regeneration combustion, while SCR is used for denitrification. Low-sulfur diesel (sulfur content ≤10ppm) is mandatory. Old vehicles are restricted and eliminated, while new energy trucks and LNG (Liquefied Natural Gas) clean energy vehicles are vigorously promoted.
2. Ships & Construction Machinery
Ships are equipped with exhaust gas scrubbers (seawater or fresh water washing type) to remove more than 80% of SOx and partial particulate matter. Ocean-going ships can switch to low-sulfur fuel (sulfur content ≤0.5%). Construction machinery is equipped with portable exhaust purification devices adopting honeycomb ceramic catalysts to oxidize and decompose particulate matter and CO, which is applicable for non-road mobile machinery.
(Ⅲ) Treatment Scheme for Scattered Small Source Black Smoke
1. Catering Oil Fume
High-efficiency oil fume purifiers (electrostatic type or composite type) with purification efficiency ≥95% are installed, matched with special smoke exhaust pipelines to avoid low-altitude emission.
2. Small Coal-fired Furnaces & Straw Burning
Open straw burning is prohibited, and straw returning and biomass power generation are promoted. Small coal-fired furnaces are replaced with clean energy equipment such as electric and natural gas equipment. Alternatively, small cyclone dust collectors and activated carbon adsorption devices shall be installed to realize compliant discharge after simple treatment.
Ⅲ. Auxiliary Guarantee Measures
1. Monitoring and Supervision System
Industrial emission sources are equipped with online monitoring devices to real-timely monitor the concentration of PM, SOx and NOx, with data connected to environmental protection departments. Mobile sources adopt remote sensing monitoring and road inspection to strictly investigate vehicles with excessive exhaust emission. The OBD (On-Board Diagnostics) system is promoted to monitor real-time emission status.
2. Operation and Maintenance Requirements
Industrial treatment equipment shall be cleaned regularly (such as electrostatic precipitator plates and bag filter bags), and catalysts shall be replaced to ensure stable treatment efficiency. The DPF of mobile equipment requires regular regeneration to prevent dust accumulation and blockage, with complete maintenance records.
3. Policy and Economic Support
Tax reductions and financial subsidies are provided for enterprises purchasing environmental protection equipment. Penalties for inferior fuel and excessive emission are increased to force pollution source rectification.
Ⅳ. Scheme Advantages and Expected Effects
1. Mature Technology: Core technologies (electrostatic dust removal, SCR, DPF, etc.) are mainstream industrial technologies with stable operation, which are suitable for different emission scenarios.
2. High Compliance Rate: Industrial sources comply with Integrated Emission Standard of Air Pollutants (GB 16297). Mobile sources meet China VI and IMO (International Maritime Organization) standards.
3. Excellent Environmental Benefits: After implementation, the regional PM2.5 concentration can be reduced by 30%-50%, and the emission of SOx and NOx can be decreased by more than 40%. The black smoke phenomenon is basically eliminated, and atmospheric visibility is significantly improved.
