The cement kiln head burner is a key equipment in the clinker calcination process, and has a key relationship with the clinker production and quality, the service life of the kiln system refractory materials, the clinker coal consumption, and environmental emissions. The service life of the burner is closely related to the quality of the burner refractory castables.
In order to avoid the burner outer sleeve from being burned, the burner end castable must be removed and recast when this happens.
2 Cause Analysis
By analyzing the damage of the burner end castable, the main reasons for the damage of the burner end castable are as follows:
(1) Cleaning the end coking damage castable. Since this type of burner is a large thrust, medium wind pressure burner, the nozzle wind speed reaches 330-410m/s, resulting in very serious coking at the burner end. In order to reduce the impact of coking on the flame shape, coking needs to be cleaned twice per shift. The coke cleaning method is to use a Φ108mm heat-resistant steel pipe to hit the end of the burner through the manhole door on the side of the kiln head cover. Due to the long distance, heavy steel pipe, and high wind speed of the burner, the strength and direction of the steel pipe are difficult to control when hitting, and it is easy to hit the castable directly, causing damage to the castable. On the other hand, when the coke falls off, the stress will also peel off part of the castable.
(2) The castable is too thin. Since the diameter of the ThyssenKrupp burner head is 100mm larger than the old burner, the old burner mold is still used when casting the new burner head, resulting in the thickness of refractory castables at the end of the new burner being only 85mm, which is easy to burn.
(3) Sulfur, alkali and flying sand erosion. Due to the disposal of hazardous waste, the harmful components of the material are relatively high. The residual head castable is yellow, and the sample is taken for chemical analysis. The sulfur and alkali content is obviously high. Usually, the flying sand material at the kiln head is large, which has a certain abrasion on the end of the burner.
Measures
(1) Increase the thickness of the castable and chamfer the head. Increase the thickness of the castable within the 500mm length of the head to 120mm, replace the Φ60mm×6mm (V-shaped nail, 6mm thick, 6mm high) nail with Φ80mm×8mm, use floating nails, and the nail head has a 3mm plastic cap. Paint the coal pipe and nail with asphalt paint, strictly control the amount of water added ≤7%, and extend the mixing time by 3%. Set the end castable with a 45° chamfer.
(2) Improve the strength grade of the castable. The refractory castables model is changed from HN-20G to HN-20GP. (3) Optimize the burner construction method. Usually, it is poured horizontally, leaving two expansion joints axially symmetrically and one expansion joint every 1m in the annular direction. Due to the horizontal pouring, it is difficult to accumulate larger particles of castables in the head, which affects the strength of the castable to a certain extent. Therefore, the coal pipe is erected for construction with the head facing down, so that larger particles of castables can be concentrated in the head to increase the strength. Leave three expansion joints axially symmetrically and one expansion joint every 0.8m in the annular direction.
(4) Change the position of the burner. Previously, the position of the burner was flush with the hot kiln mouth. Due to the large amount of flying sand in front of the kiln, the secondary air entering the kiln caused wear and thermal erosion on the end of the burner, reducing the service life of the castable. Retracting the burner 300mm can not only relatively extend the length of the burning zone, but also reduce the wear and thermal erosion of the fine clinker particles on the castable at the end of the burner. By repairing the castable at the end of the burner and strictly controlling the construction process to ensure the construction quality, the service life of the burner castable still did not meet expectations.
