Core Pain Points Before Renovation:
- High-concentration asphalt fume, visible white/yellow smoke during heating process
- Strong pungent odor, frequent resident environmental complaints
- NMHC & benzo[a]pyrene marginally exceeding local ultra-emission standards
- Original activated carbon system: High hazardous waste output & frequent replacement
- RTO renovation rejected due to high natural gas cost and site limitation
Case Details
1. Project Overview
Project Name: Asphalt Mixing Plant Flue Gas & Odor Renovation Project
Location: Jiangsu Province, China (Urban perimeter asphalt production base)
Commissioned Date: June 2024
Design Flue Gas Flow: 35,000 Nm³/h
Production Profile: Intermittent operation, 16 hours/day, asphalt mixture & modified asphalt production
Core Pain Points Before Renovation:
-
High-concentration asphalt fume, visible white/yellow smoke during heating process
-
Strong pungent odor, frequent resident environmental complaints
-
NMHC & benzo[a]pyrene marginally exceeding local ultra-emission standards
-
Original activated carbon system: High hazardous waste output & frequent replacement
-
RTO renovation rejected due to high natural gas cost and site limitation
2. Raw Flue Gas & Emission Standard
2.1 Inlet Flue Gas Parameters (Average)
|
Parameter
|
Value
|
|
Flue Gas Temperature
|
155–170 ℃
|
|
NMHC
|
285 mg/Nm³
|
|
Benzo[a]pyrene
|
0.0045 mg/Nm³
|
|
H₂S
|
12.8 mg/Nm³
|
|
Odor Concentration
|
2,800 OU
|
|
Tar Mist
|
22 mg/Nm³
|
2.2 Target Emission Standard
Comply with GB 16297-1996 and local asphalt industry ultra-low emission requirements, consistent with EU VOC control guidelines:
-
NMHC ≤ 60 mg/Nm³
-
Benzo[a]pyrene ≤ 0.001 mg/Nm³
-
Odor Concentration ≤ 300 OU
-
Invisible flue gas & zero resident complaint
3. Final Process Solution
Based on high tar content, high temperature and intermittent operating characteristics, the client adopted a 3-stage combined ozone catalytic oxidation process (no direct ozone injection):
Flue Gas Collection → Quenching Scrubber → Electrostatic Tar Remover → Mist Eliminator → Ozone Catalytic Oxidation (OCO) → Residual Ozone Thermal Destructor → Stack Discharge
3.1 Key System Configuration
-
Ozone Generator: Oxygen-fed, water-cooled, maximum output 1,200 g/h
-
Ozone Concentration: 120 g/m³ (high-purity industrial grade, NOx-free)
-
Design Ozone Dosage: 115 mg/Nm³ (medium VOC working condition)
-
Catalyst: Mn-based rare earth composite catalyst, anti-pollution & anti-blocking, service life 2.5 years
-
Reactor HRT: 35 s
-
Automatic Control: VOC online sensor linked with ozone output (0–100% stepless adjustment)
-
Safety Device: Thermal ozone destructor + workshop ozone leakage interlock system
3.2 Core Pre-treatment Design
Flue gas is cooled from 160℃ to below 40℃ via spray quenching; tar mist is reduced from 22 mg/Nm³ to ≤8 mg/Nm³ by electrostatic demisting, effectively preventing catalyst deactivation and ozone thermal decomposition.
4. Operational Performance & Test Data
4.1 Stable Effluent Quality (6-month Average Monitoring)
|
Parameter
|
Inlet
|
Treated Effluent
|
Removal Rate
|
|
NMHC
|
285 mg/Nm³
|
41 mg/Nm³
|
85.6%
|
|
Benzo[a]pyrene
|
0.0045 mg/Nm³
|
0.0004 mg/Nm³
|
91.1%
|
|
H₂S
|
12.8 mg/Nm³
|
0.5 mg/Nm³
|
96.1%
|
|
Odor Concentration
|
2,800 OU
|
220 OU
|
92.1%
|
|
Flue Gas Visual
|
Visible yellow smoke
|
Completely invisible
|
—
|
4.2 On-site Operation Effect
-
Eliminated pungent asphalt odor, zero resident complaints after renovation
-
No stack smoke visible during full-load production
-
24-hour unattended automatic operation, simple daily maintenance
-
No secondary pollution such as dioxin and NOx
5. Economic Benefit Analysis
5.1 Operating Cost Comparison
|
Technology
|
O&M Cost (USD/1000Nm³)
|
Hazardous Waste
|
Fuel Cost
|
|
Ozone Catalytic Oxidation
|
1.85
|
Very Low
|
None
|
|
RTO Thermal Oxidation
|
3.72
|
Medium
|
High (Natural Gas)
|
|
Original Activated Carbon
|
1.68
|
Extremely High
|
None
|
5.2 Annual Cost Saving
-
Hazardous Waste Saving: Cancel monthly activated carbon replacement, save USD 21,800/year
-
Fuel Cost Saving: No natural gas consumption compared with RTO, save USD 38,500/year
-
Environmental Risk Saving: Zero complaint penalty risk, reduce compliance management cost
-
Payback Period: 1.8 years
6. Conclusion & Project Value
This project verifies that Ozone Catalytic Oxidation with professional pretreatment is the optimal solution for urban peripheral asphalt plants. The system achieves stable ultra-low emission of VOCs, PAHs and odor without fuel consumption, drastically cuts hazardous waste output, and completely solves odor complaint issues. With low investment, simple skid-mounted renovation and low long-term O&M cost, it is highly replicable for global asphalt mixing plants, modified asphalt factories and waterproof membrane production lines.
