The burner is an important equipment for kilns and furnaces in cement production. It is an important guarantee for the stable ignition and combustion of fuel and the complete combustion of fuel. Therefore, it is necessary to start with the burner in order to suppress the production of NO. , Low NOx burners are roughly divided into the following categories:
1. Stage burner
The stage burner designed according to the principle of staged combustion allows the fuel and air to be mixed and burned in stages. Since the combustion deviates from the theoretical equivalent ratio, a local anoxic environment is formed, so the generation of NO2 can be reduced.
2. Self-recirculating burner
One is to use the pressure head of the combustion-supporting air to suck back part of the combustion flue gas, enter the burner, and mix it with air for combustion. Due to the flue gas recirculation, the heat capacity of the combustion flue gas is large, the combustion temperature is lowered, and the NO is reduced. Another kind of self-recirculation burner is to directly enter part of the flue gas into the recirculation in the burner and add it to the combustion process. This kind of combustion The device has dual effects of suppressing nitrogen oxide and saving energy.
3. Rich and thin type burner
The principle is to make a part of the fuel burn too rich, and another part of the fuel burn too lightly, but the overall air volume remains unchanged. Since the two parts are burned under the deviation from the stoichiometric ratio, the NO is very low. This kind of combustion is also called deviation from the combustion or non-stoichiometric combustion.
4. Split flame burner
The principle is to divide a flame into several small flames, because the heat dissipation area of the small flames is large, and the flame temperature is low, so that the thermal reaction NO is reduced. In addition, the flame is small, which shortens the residence time of oxygen, nitrogen and other gases in the flame, and has obvious inhibitory effect on thermal reaction NO and fuel NO.
5. Mixing promotion burner
The residence time of flue gas in the high temperature area is one of the main factors affecting the amount of NOx produced. Improving the mixing of combustion and air can reduce the thickness of the flame surface. Under the condition of constant combustion load, the flue gas will be more stable on the flame surface, that is, in the high temperature area. The internal residence time is shortened, thereby reducing the production of NO. The mixing-promoting burner is designed according to this principle.
6. Low NO pre-chamber burner
The pre-combustion chamber is a high-efficiency, low-NO2 staged combustion technology developed in my country in the past 10 years. The pre-combustion chamber is generally composed of primary air (or secondary air) and a fuel injection system. The fuel and primary air are quickly mixed. The fuel-rich mixture is formed in the primary combustion zone of the combustion chamber. Due to the lack of oxygen, only part of the fuel is burned, and the fuel precipitates volatiles in the primary flame zone with poor oxygen and low flame temperature, thus reducing the formation of NO2.
The burner is an important equipment for kilns and furnaces in cement production. It is an important guarantee for the stable ignition and combustion of fuel and the complete combustion of fuel. Therefore, it is necessary to start with the burner in order to suppress the production of NO. , Low NOx burners are roughly divided into the following categories:
1. Stage burner
The stage burner designed according to the principle of staged combustion allows the fuel and air to be mixed and burned in stages. Since the combustion deviates from the theoretical equivalent ratio, a local anoxic environment is formed, so the generation of NO2 can be reduced.
2. Self-recirculating burner
One is to use the pressure head of the combustion-supporting air to suck back part of the combustion flue gas, enter the burner, and mix it with air for combustion. Due to the flue gas recirculation, the heat capacity of the combustion flue gas is large, the combustion temperature is lowered, and the NO is reduced. Another kind of self-recirculation burner is to directly enter part of the flue gas into the recirculation in the burner and add it to the combustion process. This kind of combustion The device has dual effects of suppressing nitrogen oxide and saving energy.
3. Rich and thin type burner
The principle is to make a part of the fuel burn too rich, and another part of the fuel burn too lightly, but the overall air volume remains unchanged. Since the two parts are burned under the deviation from the stoichiometric ratio, the NO is very low. This kind of combustion is also called deviation from the combustion or non-stoichiometric combustion.
4. Split flame burner
The principle is to divide a flame into several small flames, because the heat dissipation area of the small flames is large, and the flame temperature is low, so that the thermal reaction NO is reduced. In addition, the flame is small, which shortens the residence time of oxygen, nitrogen and other gases in the flame, and has obvious inhibitory effect on thermal reaction NO and fuel NO.
5. Mixing promotion burner
The residence time of flue gas in the high temperature area is one of the main factors affecting the amount of NOx produced. Improving the mixing of combustion and air can reduce the thickness of the flame surface. Under the condition of constant combustion load, the flue gas will be more stable on the flame surface, that is, in the high temperature area. The internal residence time is shortened, thereby reducing the production of NO. The mixing-promoting burner is designed according to this principle.
6. Low NO pre-chamber burner
The pre-combustion chamber is a high-efficiency, low-NO2 staged combustion technology developed in my country in the past 10 years. The pre-combustion chamber is generally composed of primary air (or secondary air) and a fuel injection system. The fuel and primary air are quickly mixed. The fuel-rich mixture is formed in the primary combustion zone of the combustion chamber. Due to the lack of oxygen, only part of the fuel is burned, and the fuel precipitates volatiles in the primary flame zone with poor oxygen and low flame temperature, thus reducing the formation of NO2.