Natural gas low-NOx burners are combustion devices designed to significantly reduce nitrogen oxide (NOx) emissions. With increasingly stringent environmental protection requirements, they are widely used in a wide range of fields. The following is a detailed introduction:
Working Principle
Premixed combustion: Before combustion, natural gas is premixed with an appropriate amount of air, ensuring a relatively even distribution of the two gases before entering the combustion chamber. This allows fuel and oxygen to react more fully and efficiently during combustion, reducing the formation of localized high temperatures, which are a key factor in the formation of NOx. For example, a precisely designed premixing device can control the natural gas-air mixture ratio within an ideal range, typically achieving an air-fuel ratio control accuracy of ±3%, effectively suppressing the formation of thermal NOx.
Staged combustion: The combustion process is divided into multiple stages. First, in the first combustion zone, a small amount of air is supplied, resulting in incomplete combustion of the natural gas. Due to the lack of oxygen, the combustion temperature is relatively low, and the amount of NOx generated during this stage is relatively low. Then, in subsequent stages, the remaining air is added to allow the incomplete combustion products to continue to burn. This approach avoids prolonged high-temperature, oxygen-rich environments in a single zone, thereby reducing overall NOx generation. Staged combustion typically divides the combustion process into two or three stages, with the air distribution ratio between the different stages optimized based on the burner design and actual application scenario.
Flue gas recirculation (FGR): A portion of the flue gas after combustion is extracted and returned to the burner inlet through specialized piping and equipment, where it is mixed with fresh air and natural gas before being recombined for combustion. Because flue gas contains a large amount of inert gases (such as nitrogen and carbon dioxide), this incorporation reduces the oxygen concentration and flame temperature in the combustion zone, suppressing NOx generation. Generally, an FGR rate between 10% and 30% can effectively reduce NOx emissions by 30% to 60%.
Structural Components
Premixer: This unit is responsible for evenly mixing natural gas and air in a set ratio. It typically includes components such as a mixing chamber, a regulating valve, and a flow sensor. The mixing chamber is designed to ensure thorough mixing and smooth flow of gases. The regulating valve precisely controls the flow of natural gas and air according to combustion requirements. Flow sensors monitor gas flow in real time and provide feedback to the control system for precise regulation.
The combustion head is the core area where combustion occurs. Its unique structural design ensures stable ignition and efficient combustion of the premixed gas. The combustion head is typically constructed of high-temperature and corrosion-resistant materials, such as ceramics or special alloys. It is also equipped with a flame stabilizer to prevent flameout and flashback during combustion, ensuring stable and safe combustion.
The control system comprehensively monitors and precisely regulates burner operation. It automatically adjusts the natural gas and air supply based on actual operating conditions (such as load fluctuations and temperature requirements) to maintain optimal combustion conditions. The control system also features fault diagnosis capabilities, monitoring burner operating parameters in real time. If an anomaly is detected (such as flame failure, excessive temperature, or abnormal pressure), it immediately initiates appropriate protective measures, such as shutting off the fuel supply and activating alarms.
The flue gas recirculation system includes the flue gas extraction piping, cooling device, regulating valve, and mixer. The flue gas extraction duct draws high-temperature flue gas from the chimney or flue. A cooling device cools the extracted flue gas to prevent damage to other burner components. A regulating valve controls the flow of recirculated flue gas, while a mixer thoroughly mixes the cooled flue gas with fresh air and natural gas, allowing it to participate in the combustion process.
Advantages
Significantly Low NOx Emissions: Compared to traditional burners, natural gas low-NOx burners can reduce NOx emissions to 30mg/m³ or even lower, meeting increasingly stringent environmental regulations. This is crucial for improving air quality and reducing environmental issues such as acid rain and photochemical smog. In regions with extremely stringent environmental standards, such as Beijing and Shanghai, new gas-fired boilers must be equipped with low-NOx burners to ensure compliance with NOx emission standards.
High Combustion Efficiency: By optimizing the combustion process to ensure complete combustion of natural gas, thermal efficiency typically exceeds 90%. This not only improves energy utilization and reduces energy costs, but also reduces other pollutants caused by incomplete combustion. For example, using low-NOx burners in industrial heating furnaces can significantly reduce fuel costs while ensuring production process requirements.
High Adaptability: They can adapt to various types of gas-fired boilers, industrial furnaces, and other equipment, making them convenient for both new projects and retrofits of existing equipment. Furthermore, they can flexibly adjust combustion parameters based on varying operating conditions and load requirements, ensuring stable operation under a variety of conditions.
Application Scenarios
Heating Industry: Widely used in gas-fired boilers for urban centralized heating. With increasing winter heating demand, a large number of gas-fired boilers are now in operation. Using natural gas low-NOx burners can effectively meet heating needs while reducing environmental pollution. For example, the adoption of low-NOx burners in some large heating stations has significantly reduced NOx emissions and significantly improved surrounding air quality.
Industrial Production: They play a vital role in industrial furnaces in industries such as food processing, textile printing and dyeing, and the chemical industry. These industries require significant amounts of heat energy. Using low-NOx burners in gas-fired furnaces ensures stable operation while complying with environmental regulations, avoiding the risk of production suspensions and rectifications due to excessive emissions. For example, low-NOx burners in baking ovens at food processing plants precisely control oven temperatures while reducing nitrogen oxide emissions, ensuring food quality and safety and ensuring environmental compliance.
Commercial venues such as hotels and hospitals typically use gas-fired boilers for hot water and heating systems. Installing natural gas low-NOx burners can improve the environmental performance of these systems and reduce the impact on the surrounding environment and personnel. Hotels and hospitals, as crowded places, have high air quality requirements, and the use of low-NOx burners helps create a comfortable and healthy environment.
Natural gas low-NOx burners are combustion devices designed to significantly reduce nitrogen oxide (NOx) emissions. With increasingly stringent environmental protection requirements, they are widely used in a wide range of fields. The following is a detailed introduction:
Working Principle
Premixed combustion: Before combustion, natural gas is premixed with an appropriate amount of air, ensuring a relatively even distribution of the two gases before entering the combustion chamber. This allows fuel and oxygen to react more fully and efficiently during combustion, reducing the formation of localized high temperatures, which are a key factor in the formation of NOx. For example, a precisely designed premixing device can control the natural gas-air mixture ratio within an ideal range, typically achieving an air-fuel ratio control accuracy of ±3%, effectively suppressing the formation of thermal NOx.
Staged combustion: The combustion process is divided into multiple stages. First, in the first combustion zone, a small amount of air is supplied, resulting in incomplete combustion of the natural gas. Due to the lack of oxygen, the combustion temperature is relatively low, and the amount of NOx generated during this stage is relatively low. Then, in subsequent stages, the remaining air is added to allow the incomplete combustion products to continue to burn. This approach avoids prolonged high-temperature, oxygen-rich environments in a single zone, thereby reducing overall NOx generation. Staged combustion typically divides the combustion process into two or three stages, with the air distribution ratio between the different stages optimized based on the burner design and actual application scenario.
Flue gas recirculation (FGR): A portion of the flue gas after combustion is extracted and returned to the burner inlet through specialized piping and equipment, where it is mixed with fresh air and natural gas before being recombined for combustion. Because flue gas contains a large amount of inert gases (such as nitrogen and carbon dioxide), this incorporation reduces the oxygen concentration and flame temperature in the combustion zone, suppressing NOx generation. Generally, an FGR rate between 10% and 30% can effectively reduce NOx emissions by 30% to 60%.
Structural Components
Premixer: This unit is responsible for evenly mixing natural gas and air in a set ratio. It typically includes components such as a mixing chamber, a regulating valve, and a flow sensor. The mixing chamber is designed to ensure thorough mixing and smooth flow of gases. The regulating valve precisely controls the flow of natural gas and air according to combustion requirements. Flow sensors monitor gas flow in real time and provide feedback to the control system for precise regulation.
The combustion head is the core area where combustion occurs. Its unique structural design ensures stable ignition and efficient combustion of the premixed gas. The combustion head is typically constructed of high-temperature and corrosion-resistant materials, such as ceramics or special alloys. It is also equipped with a flame stabilizer to prevent flameout and flashback during combustion, ensuring stable and safe combustion.
The control system comprehensively monitors and precisely regulates burner operation. It automatically adjusts the natural gas and air supply based on actual operating conditions (such as load fluctuations and temperature requirements) to maintain optimal combustion conditions. The control system also features fault diagnosis capabilities, monitoring burner operating parameters in real time. If an anomaly is detected (such as flame failure, excessive temperature, or abnormal pressure), it immediately initiates appropriate protective measures, such as shutting off the fuel supply and activating alarms.
The flue gas recirculation system includes the flue gas extraction piping, cooling device, regulating valve, and mixer. The flue gas extraction duct draws high-temperature flue gas from the chimney or flue. A cooling device cools the extracted flue gas to prevent damage to other burner components. A regulating valve controls the flow of recirculated flue gas, while a mixer thoroughly mixes the cooled flue gas with fresh air and natural gas, allowing it to participate in the combustion process.
Advantages
Significantly Low NOx Emissions: Compared to traditional burners, natural gas low-NOx burners can reduce NOx emissions to 30mg/m³ or even lower, meeting increasingly stringent environmental regulations. This is crucial for improving air quality and reducing environmental issues such as acid rain and photochemical smog. In regions with extremely stringent environmental standards, such as Beijing and Shanghai, new gas-fired boilers must be equipped with low-NOx burners to ensure compliance with NOx emission standards.
High Combustion Efficiency: By optimizing the combustion process to ensure complete combustion of natural gas, thermal efficiency typically exceeds 90%. This not only improves energy utilization and reduces energy costs, but also reduces other pollutants caused by incomplete combustion. For example, using low-NOx burners in industrial heating furnaces can significantly reduce fuel costs while ensuring production process requirements.
High Adaptability: They can adapt to various types of gas-fired boilers, industrial furnaces, and other equipment, making them convenient for both new projects and retrofits of existing equipment. Furthermore, they can flexibly adjust combustion parameters based on varying operating conditions and load requirements, ensuring stable operation under a variety of conditions.
Application Scenarios
Heating Industry: Widely used in gas-fired boilers for urban centralized heating. With increasing winter heating demand, a large number of gas-fired boilers are now in operation. Using natural gas low-NOx burners can effectively meet heating needs while reducing environmental pollution. For example, the adoption of low-NOx burners in some large heating stations has significantly reduced NOx emissions and significantly improved surrounding air quality.
Industrial Production: They play a vital role in industrial furnaces in industries such as food processing, textile printing and dyeing, and the chemical industry. These industries require significant amounts of heat energy. Using low-NOx burners in gas-fired furnaces ensures stable operation while complying with environmental regulations, avoiding the risk of production suspensions and rectifications due to excessive emissions. For example, low-NOx burners in baking ovens at food processing plants precisely control oven temperatures while reducing nitrogen oxide emissions, ensuring food quality and safety and ensuring environmental compliance.
Commercial venues such as hotels and hospitals typically use gas-fired boilers for hot water and heating systems. Installing natural gas low-NOx burners can improve the environmental performance of these systems and reduce the impact on the surrounding environment and personnel. Hotels and hospitals, as crowded places, have high air quality requirements, and the use of low-NOx burners helps create a comfortable and healthy environment.