Boiler Combustion Theory

The stage from the fuel into the furnace to the ignition temperature is called the preparation stage. In this stage, the evaporation of water should be completed, the volatile matter should be separated out, and the mixture of fuel and air should reach the ignition temperature. Obviously, this stage is the endothermic process, and the source of heat is flame radiation and high-temperature flue gas backflow. In addition to the burner itself, the factors that affect the length of the preparation stage are the strength of the heat provided by the hot flue gas in the furnace for the pulverized coal flow, the amount, temperature, concentration, volatile content and fineness of the pulverized coal flow.HORIZONTAL MITRE BAND SAW MACHINE BS-170G When the ignition temperature is reached, the volatile matter is first ignited and burned, releasing heat to increase the temperature, and the coke is heated to a higher temperature and begins to burn. The combustion stage is a strong exothermic process, the temperature rises rapidly, and the chemical reaction is strong. At this time, the surface of the carbon particles often appears in an oxygen-deficient state. The key to the enhanced combustion stage is to strengthen the mixing, so that the air flow is strongly disturbed, so as to provide oxygen to the surface of the carbon particles, and diffuse the carbon dioxide on the surface of the carbon particles.HORIZONTAL MITRE BAND SAW MACHINE BS-180G The burnout stage is mainly to burn off the unburned carbon in the combustion stage. Although there is not much carbon left in the burnout stage, it is very difficult to completely burn it out. The main reason is that there are many factors that are not conducive to complete combustion, such as a small amount of carbon. The fixed carbon is surrounded by ash; the oxygen concentration is already low; the disturbance of the air flow is gradually attenuating; the temperature in the furnace is gradually decreasing.Vacuum brazing of the rear passage assembly of the flame tube If the fuel has low volatile content, high ash content, coarse pulverized coal, and small furnace volume, it will be more difficult to completely burn out. According to the test, for coal powder with a fineness of R90=5%, 97% of the combustibles can be burned in 25% of the time, while the remaining 3% of the combustibles can be burned in 75% of the time. This is the basic reason why it is impossible to completely burn the combustibles in the actual boiler.Sintered NdFeB Vacuum Heat Treatment Process