Since the swirl burner ignites the coal powder by absorbing the surrounding hot flue gas and has little relationship with the surrounding burners, the swirl burner can be tested on a single burner and individually optimized and adjusted. During the operation of the cyclone burner, the central return flow, the range of the air flow and the diffusion Angle of the air flow are mainly regulated.
Volute swirl burners are generally regulated by adjusting the tongue baffle at the inlet of the burner. The length and width of the central backflow area of the rotary jet increase with the increase of cyclone intensity. The range of the rotary jet decreases with the increase of cyclone intensity. The diffusion Angle of the rotating jet increases with the increase of cyclone intensity. Therefore, in operation adjustment, the diffusion Angle, range and reflux zone should be considered comprehensively. According to the corresponding type of coal, the cyclone strength can be properly adjusted. When the load is low or the ash content of coal quality difference is large, the axial baffle can be properly turned off to obtain a larger cyclone strength and improve the fire condition of the burner. When the load is high or the coal quality reaches the design standard, the large axial baffle can be properly opened to avoid coking.
The double volute burner itself has some disadvantages: (1) the airflow rotation intensity attenuation is very fast, the later mixing of coal powder and air is poor; Large secondary wind resistance; (3) Poor adaptability of coal; At the outlet section of the burner, the distribution of coal powder in the primary air flow is not uniform; (5) Grinding through casing in the first wind and powder leakage cause the jet flow of the burner outlet to be destroyed, and the axial baffle of the secondary air to fall off or get stuck, resulting in the difficulty in adjusting the secondary air; Part of the secondary air outlet of the burner is deformed due to the fall off of the upper and lower edge castable, its vertical diameter is larger than the horizontal diameter, the shape of the nozzle is changed from circular to elliptic, the exit cross-sectional area is increased, the secondary air cyclone intensity is weakened, making the shape of the flame change, causing combustion instability.
Therefore, it is necessary for the burner to maintain an appropriate first, second, and third air outlet speed to establish a normal aerodynamic field and stable combustion in the furnace. In order to improve the fire condition of the burner reasonably, it is more important than the coordination of the primary and secondary winds. In the past, due to the static pressure monitoring of primary air pressure, the primary air baffle was in full open position most of the time to prevent pipe blocking. After the DCS system modification of the unit is completed, due to the installation of an online monitoring device for wind powder, the operator's monitoring of the primary air duct is completed by changing the original wind pressure to wind speed, wind powder concentration and wind powder temperature. In this way, the wind speed of primary air duct can be adjusted quantitatively. If the wind speed of primary air duct is too high, the fire will be delayed; if the wind speed is too low, the burner will be easily burned and pulverized coal will be deposited in the primary air duct.
In addition to adjusting the primary wind, the secondary wind must also be adjusted. Since there is a big difference in the measured secondary air velocity, the secondary air volume can only be changed by changing the secondary damper opening. When the load is low or the coal quality is poor, turn down the secondary damper, on the one hand, it can improve the cyclone strength, on the other hand, it can ensure that the oxygen meets the requirements; When the load is high or the coal quality is good, open the secondary air damper, which is consistent with improving the combustion, reducing the fly ash fuel, and ensuring the main steam parameters. In addition, in the field practice, the influence on combustion should be considered due to the large change of coal quality, the destruction of jet flow at the outlet of the burner due to the grinding and leaking of powder through casing in the primary air, and the falling off or jamming of axial baffle in the secondary air.
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