Working principle and adjustment method of kiln burner

Working principle and adjustment method of kiln burner
The kiln head burner is an important part of the mature materials in the kiln. Whether its performance is adjusted properly or not is directly related to the service life of the kiln calcination and kiln lining. Properly adjust the butterfly valve opening of the external air, internal air and central air of the burner, improve the local pulverized coal concentration before the ignition of pulverized coal, strengthen the internal, external and return flow of the high-temperature gas of the burner, and strengthen the full mixing of the primary air to achieve complete combustion.
However, it should be noted that the internal air should not be adjusted too high, otherwise the pulverized coal may have been diluted before the fire, which is adverse, or it may produce high temperature flame, wash the kiln skin, cause the kiln skin to fall off, which is not conducive to the protection of refractory bricks. The internal air should not be adjusted too low, otherwise the pulverized coal can not be mixed with the air quickly after ignition, which will lead to the reduction of the reaction speed of pulverized coal, resulting in a large amount of carbon monoxide can not be oxidized into carbon dioxide in time, resulting in the reduction atmosphere in the kiln.
In addition, the external air should not be adjusted too high, otherwise it will cause the burning belt flame to move backward, there is thick kiln skin at the end of the kiln or there is ring formation and egg formation near the transition belt, and the external air should not be too small, otherwise it will not produce a strong flame, which is not conducive to the calcination of high-quality clinker. Therefore, according to the coal quality, fineness, water content, secondary air temperature and other factors, the reasonable operating parameters, the kiln environment and the burnability of St. Louis should be selected, and the appropriate calcination system should be determined by adjusting the proportion of the optimal external air, internal air and central air, and the reasonable position of the burner near the kiln mouth.
1. Burner positioning. Many companies use the "light column method" to locate the burners, which is accurate in control, but inconvenient in operation. It is better to use a position ruler to position the kiln head section. Generally, it is better to control the position of the kiln head section with the X axis slightly to the right or slightly to the fourth quadrant. If there are special process conditions, fine adjustment can be made.
2. Design of the influence of flame shape on calcination. The optimal flame shape is at the position of axial flow wind and swirl wind (0.0) (at this time, the ventilation of each air duct is maximum), and the flame shape is complete and powerful. The adjustment of flame shape is realized by adjusting the ventilation sectional area of each air duct. At point (0.0), the ventilation sectional area of axial flow air and swirl air is the largest. Due to the mutual influence and restriction of swirling air and axial flow air, the flame shape is realized by the central air, and the central air volume cannot be too large or too small. Generally, the central wind pressure should be controlled between 6 and 8 KPa, the rotational wind speed is 24-26 KPa, the axial flow wind is 23-25 KPa, and the parameters should be adjusted when the ventilation sectional area of each air duct is not less than 90%. In order to change the flame shape, a stable primary outlet pressure must be maintained. The purpose of changing the flame shape can be achieved by changing the pressure on the burner and the ventilation sectional area of each branch pipe.
3. Specific flame shape changes. When adjusting the flame shape, extreme phenomena should be avoided. When the flame is too thick, it will be very long and soft. When the flame is too thin, the flame will be too short. The burning zone requires the flame to be complete, lively and powerful, which requires our long-term observation and experience.
4. Influence of coal quality change on flame shape:
(1) The higher the ash content is, the slower the combustion speed of pulverized coal is, the longer the flame is, the longer the flame combustion zone is. It should: ① increase the temperature of secondary air or make full use of secondary air to improve the mixing degree of primary air, secondary air and pulverized coal; ② Reduce the fineness and water content of pulverized coal; ③ Change the air consumption rate of axial flow air and swirl air ④ Increase the primary air volume and reduce the concentration of pulverized coal in the primary and secondary air.
(2) The higher the volatile content of coal, the faster the combustion speed, and the lower the oxygen concentration around the coke particles. It is easy to form a flame close to the kiln head, with low stability and long high temperature part. At this time, it should: ① increase the oxygen content around the flame; ② Increase the air volume and wind speed of axial flow air (under the original flame state); ③ Increase the primary air volume.
(3) When the water content in coal increases, increasing the temperature of the outlet gas can reduce its external humidity, while the internal water needs to be evaporated at about 110 ℃. It is difficult to reduce the internal water content of the pulverized coal mill. After the pulverized coal with high internal water rate enters the kiln, the flame will become longer, the combustion speed will become slower, the flame temperature will decrease, and the black flame head will become longer. When properly increasing the combustion support effect of secondary air on the flame, increase the mixing of secondary air and primary air, increase the temperature of secondary air, properly release a part of the burner, and use the secondary air to increase the flame combustion speed to achieve the purpose of improving the flame temperature.