Nitrogen oxides (NOₓ) are major air pollutants that contribute to smog, acid rain, and respiratory illnesses—posing serious risks to both the environment and public health. As global emissions regulations tighten—from China’s GB standards to the EU’s Industrial Emissions Directive and U.S. EPA requirements—industries face growing pressure to implement effective NOₓ control.
Ever-power’s NOx Gas Treatment Solution delivers unmatched value by combining high destruction efficiency (99%) with economic viability, priced at 35% of Western competitors like Dürr or Eisenmann, while offering superior performance in NOx reduction through advanced rotary RTO design. This system not only meets stringent regulations (e.g., US EPA 40 CFR Part 60, China GB 16297-1996) but also reduces operating costs by 70% via 95% heat recovery, making it ideal for high-VOC industries. Clients benefit from custom engineering, ensuring seamless integration with existing exhaust systems, and long-term reliability with minimal downtime (less than 1% annually).
NOₓ (nitrogen oxides) is a collective term primarily referring to **nitric oxide **(NO) and **nitrogen dioxide **(NO₂)—two harmful gases formed during high-temperature combustion. Trace amounts of other nitrogen oxides (e.g., N₂O, N₂O₃) may also be present.
Sources
NOₓ is a key precursor to **ground-level ozone **(smog) and **fine particulate matter **(PM2.5), both major contributors to urban air pollution. It also reacts with moisture in the atmosphere to form nitric acid, a primary component of acid rain that damages forests, soils, and aquatic ecosystems.
Exposure to NOₓ can cause immediate irritation of the eyes, nose, and throat. Long-term exposure is linked to reduced lung function, aggravated asthma, bronchitis, and other chronic respiratory diseases—especially in children and the elderly.
Governments worldwide enforce strict NOₓ limits:
Non-compliance risks fines, operational restrictions, or shutdowns
| Source Category | Specific Examples | Key Characteristics |
|---|---|---|
| Combustion Processes | – Coal/oil/gas-fired power plants – Industrial boilers & furnaces – Cement kilns – Metal smelting | High-temperature combustion (>1,300°C) causes thermal NOₓ formation from atmospheric N₂ and O₂ |
| Transportation | – Gasoline & diesel vehicles – Ships & aircraft engines | Mobile source; major contributor in urban areas; emits both NO and NO₂ |
| Chemical Industry | – Nitric acid production – Explosives manufacturing – Adipic acid plants | Fuel-bound nitrogen in feedstocks leads to “fuel NOₓ”; often high-concentration streams |
| Waste Incineration | – Municipal solid waste incinerators – Hazardous waste combustors | Combustion of nitrogen-containing waste (e.g., proteins, plastics) generates significant NOₓ |
| Other Industrial | – Glass manufacturing – Refineries – Pulp & paper mills | Process-specific high-temp operations with air-fuel mixing |
Note: Over 90% of anthropogenic NOₓ emissions come from high-temperature combustion, where nitrogen and oxygen in the air react to form thermal NOₓ. In processes involving nitrogen-rich fuels or feedstocks, fuel NOₓ also contributes significantly.
Ozone (O₃) is used to rapidly oxidize water-insoluble NO into easily soluble NO₂, N₂O₅, etc., which are then completely removed by wet scrubbing (such as with alkaline solutions).
Advantages: Fast reaction speed, no secondary pollution, seamless integration with existing wet desulfurization systems, especially suitable for low-concentration, high-volume flue gas.
| Parameter | SNCR (Selective Non-Catalytic Reduction) | SCR (Selective Catalytic Reduction) | Sodium Hypochlorite DeNOx | Ozone DeNOx (O₃) |
|---|---|---|---|---|
| Working Principle | Inject ammonia/urea into flue gas at 850–1100°C to reduce NOₓ without a catalyst | Reduce NOₓ to N₂ and H₂O over a catalyst at 300–400°C | Oxidize NO to NO₂ using sodium hypochlorite (NaClO), then absorb with alkaline solution | Oxidize NO to NO₂/N₂O₅ using ozone (O₃), followed by wet scrubbing |
| NOₓ Removal Efficiency | 30% – 70% | 80% – 95%+ | 50% – 80% | 60% – 90% |
| Optimal Temperature Range | 850 – 1100°C | 300 – 400°C | Ambient – 80°C | Ambient – 150°C |
| Catalyst Required? | ❌ No | ✅ Yes | ❌ No | ❌ No |
| By-products / Secondary Waste | Minor ammonia slip | Very low ammonia slip (controllable) | Saline wastewater (requires treatment) | No harmful by-products |
| Space Requirement | Low (only injection system needed) | Medium–High (reactor + catalyst modules) | Low–Medium (scrubber + chemical tanks) | Medium (O₃ generator + scrubber) |
| Operating Cost | Low (no catalyst replacement) | Medium (catalyst life: 2–5 years) | Medium (continuous NaClO consumption) | High (significant electricity for O₃ generation) |
| Capital Cost | Lowest | Highest | Low–Medium | Medium |
| Best For | Small/medium boilers, limited budget, moderate emission limits | Power plants, chemical facilities, waste incinerators with strict compliance needs | Low-temperature, small-to-medium flow, high-humidity streams | Low-concentration NOₓ, retrofit projects, integration with existing wet FGD |
| Key Advantages | Low CAPEX, simple installation, ideal for retrofits | High efficiency, stable performance, predictable long-term OPEX | No high temperature required, easy operation | Fast reaction, no catalyst, tolerant to complex gas compositions |
| Limitations | Narrow temperature window, variable efficiency | Catalyst susceptible to poisoning (e.g., As, P, Ca); larger footprint | Corrosive chemicals; generates wastewater | High energy cost; requires strict O₃ safety management |
All technologies can be combined (e.g., SNCR + O₃ as a cost-effective alternative to SCR). we engineers will design the optimal, customized solution for your specific application.
The composition of exhaust gases varies significantly across different industries, directly impacting technology selection:
✅ Our Approach: We provide free flue gas composition testing advice to accurately identify NOₓ types (thermal/fuel/rapid).
Temperature, airflow, and fluctuations determine system stability:
| Industry | Typical Operating Conditions | Recommended Technology |
|---|---|---|
| Power Plant Boilers | High temperature (300–400°C), stable | Conventional SCR |
| RTO Outlet | High temperature but intermittent operation | RTO + Heat Recovery + SCR (with electric backup heater) |
| Biomass Boilers | Low temperature (<250°C), high dust | SNCR or Low-Temperature SCR (with specialized catalyst) |
This format is clear, professional, and suitable for technical documentation, websites, or client proposals. Let me know if you’d like to add more industries or include efficiency/compliance notes!
Avoid starting from scratch and reduce customer investment costs:
Add a compact SCR module to the back end of the existing RTO system;
Install an SNCR injection grille in the space behind the boiler economizer;
Integrate the O₃ DeNOx system with the existing wet desulfurization tower to save space.
✅ Our approach: Provide 3D plant layout scanning to achieve a “zero-conflict” installation design.
Significant regional regulatory differences exist:
✅ Our approach: Built-in global emissions standards database, automatically matching compliance pathways.
✅ Our approach: Provide a 5-year life cycle cost analysis report (LCC) to help clients calculate their “total costs”.
PT Jaya Energi operates a 300 MW coal-fired power plant that supplies electricity to over 500,000 households. In 2023, Indonesia’s Ministry of Environment and Forestry (KLHK) tightened air emission standards under Regulation No. PM-14/2023, requiring all coal plants to reduce NOₓ emissions to ≤100 mg/Nm³ (from the previous 400 mg/Nm³). The plant’s existing combustion controls could only achieve ~250 mg/Nm³—far from compliance.
Facing potential fines and operational restrictions, the plant began searching for a reliable DeNOx solution. After reviewing international suppliers, they discovered Ever-power through an industry webinar on “High-Efficiency SCR Systems for Southeast Asian Coal Plants” and were impressed by Ever-power’s reference projects in Vietnam and the Philippines.
To meet these challenges while ensuring long-term compliance, Ever-power designed a high-efficiency, compact SCR system based on the fundamental principles of Selective Catalytic Reduction (SCR)—a technology proven effective in thousands of global installations.
The core of the SCR process lies in the selective oxidation of nitrogen oxides (NOₓ) using ammonia (NH₃) as a reducing agent. Under controlled conditions, NH₃ reacts preferentially with NOₓ rather than oxygen in the flue gas, producing harmless nitrogen (N₂) and water (H₂O)—with no secondary pollutants or harmful by-products.
The key chemical reactions are:
(1) 4NO + 4NH₃ + O₂ → 4N₂ + 6H₂O
(2) 2NO₂ + 4NH₃ + O₂ → 3N₂ + 6H₂O
These reactions occur efficiently only within a narrow temperature window—approximately 980°C without a catalyst. However, when a catalyst is introduced, the reaction becomes viable at much lower temperatures: 300–400°C, which aligns perfectly with the flue gas temperature between the economizer and air preheater in coal-fired boilers. This makes SCR ideal for retrofitting into existing plants without major thermal modifications.
Moreover, since NOₓ concentrations in flue gas are relatively low, the heat released during the reaction is negligible—meaning no additional heating is required, and the system remains thermally stable under normal operation.
This scientific foundation enabled Ever-power to design a solution that not only meets performance targets but also integrates seamlessly into the plant’s operating environment.
Based on this chemistry-driven approach, Ever-power implemented the following tailored solutions:
✅ 1. High-Resistance Catalyst Design
✅ 2. Compact Vertical Reactor Layout
✅ 3. Temperature & Ammonia Control Strategy
✅ 4. Localized Operation & Support
The entire system was delivered in prefabricated modules, installed within 8 weeks, and commissioned successfully during a scheduled maintenance shutdown.
“Ever-power didn’t just sell us a reactor—they delivered a compliance guarantee. Their understanding of Southeast Asian coal made all the difference.”
— Mr. Budi Santoso, Plant Manager, PT Jaya Energi
Editor: Miya