Controlling boiler emissions is extremely important for protecting human health and the environment. It helps prevent air pollution, safeguards water and soil resources, and minimizes climate change. Additionally, emissions control provides economic benefits for businesses, saves energy, and enhances reputation. This is not only a legal requirement but also a social responsibility and a sustainable development strategy.

Methods for controlling the basic content and components of emissions can be referenced as follows:

I - For emission flow rate: To reduce the emissions of the Boiler, it is necessary to control the following factors when managing and operating the equipment.

• Improve the combustion process: Adjust the excess air ratio (indicated by the excess oxygen percentage in the boiler) by optimizing the air supply and flue gas extraction system to enhance combustion efficiency, reduce fuel consumption, and decrease the excess air factor, thereby reducing the emissions flow.

• Use fuel that meets the equipment's design standards: For each type of boiler, the designer calculates the highest efficiency when using the specific fuel type recommended in the design. This ensures the boiler operates at its peak performance, with the lowest fuel consumption and optimal emissions.

Example: When using the correct fuel type as per design, the fuel consumption is 200 kg per 1 ton of steam. The emissions generated by the boiler with this fuel are 5 m³/kg of fuel, resulting in an emissions flow rate of 1000 m³/ton of steam produced. When using fuel that does not meet the design specifications, with lower calorific value, the boiler efficiency decreases and fuel consumption increases to 270 kg per 1 ton of steam. In this case, the emissions flow rate rises to 1350 m³/ton of steam produced (a 35% increase).

Reference formula for calculating fuel consumption and boiler efficiency:: https://phuctruonghai.vn/tinh-suat-tieu-hao-nhien-lieu-cho-lo-hoi

• Using a high-efficiency boiler and equipping it with a complete heat recovery system: The emissions flow rate is also influenced by the flue gas temperature (as temperature changes the specific volume of the flue gas). Therefore, using a high-efficiency boiler will reduce fuel consumption, decrease emissions, and reduce the emissions flow rate by lowering the volume.

II - With Co : CO is an air pollutant formed by the incomplete combustion of fuel and organic compounds. To effectively control the CO content, it is essential to ensure complete combustion of the fuel in the boiler's combustion chamber by controlling the appropriate amount of air supply for full combustion, maintaining the proper combustion chamber temperature to ensure continuous and stable heat transfer during combustion. Controlling the fuel residence time and proper fuel mixing are key methods to ensure that fuel, air, and temperature are blended and combusted continuously. When fuel undergoes smoldering or is piled up without proper exposure to air and temperature sources, it leads to significant CO emissions.

III – With NOx: NOx includes NO and NO2. These gases can be emitted during the combustion of all types of fuels with oxygen sourced from the air. There are three mechanisms for NO (NO and a small portion of NO2) formation during combustion: thermal NO, prompt NO, and fuel NO. Among these, thermal NO increases and is directly correlated with combustion temperature when the temperature exceeds 1200°C. Therefore, controlling NO should focus on managing the combustion process, including the following key factors:

• Control the combustion temperature of the boiler. Using fluidized bed boiler technology is also a method to reduce NOx emissions, as the combustion temperature in a fluidized bed boiler typically does not exceed 1050°C.
• Control the excess air in the boiler (Nitrogen makes up 78% of the air).
• Use fuel with low nitrogen content.

• For boilers that require high combustion temperatures (such as waste incinerators, clinker kilns, etc.), a NOx emission control system is necessary.

IV – With SOx: SOx is primarily generated when using fuels with high sulfur content. To reduce SOx in the emissions from combustion boilers, it is essential to use low-sulfur fuel (biomass fuels have very low sulfur content). If the equipment is designed to only use high-sulfur fuel, an additional flue gas treatment system should be installed, utilizing absorbent chemicals to remove SOx from the emissions (such as using lime water Ca(OH)2, Mg(OH)2, etc.).

V – With dust: Use and install additional dust filtration systems to thoroughly remove dust from the emissions, such as combined Cyclone dust removal, fabric bag filters, wet dust removal, electrostatic dust filters, etc. It is also recommended to install at least two stages of dust removal to effectively eliminate dust and provide backup solutions for continuous dust removal efficiency.

The above are key considerations when controlling the basic components in boiler emissions. We hope this helps you address the issues with your company's equipment!