The results of the operation practice of rotary kiln show that mechanical stress, thermal stress and chemical erosion are the three basic ways to cause damage to the refractory materials of kiln head. Mechanical stress is caused by the deformation of the cylinder and the thermal expansion of bricks; thermal stress is caused by overheating and thermal shock; chemical erosion is caused by the erosion of clinker silicates and alkali salts. Among them, mechanical stress is the most important damage factor.
In order to effectively reduce mechanical stress, kiln head cylinders and cylinder guards made of low carbon steel, stainless steel and nickel-berkelium steel have been tried successively, with no less than ten combinations, but the actual use effect has always been poor. The main reason for this phenomenon is that the kiln head cylinder is affected by long-term high-temperature roasting, and the various welded parts are unevenly deformed by heat during use. Eventually, the kiln head refractory material cracks with the deformation of the kiln head ring iron, and the kiln head refractory material is very easy to fall off after a long time. In response to the above problems, the following improvement measures have been taken.
01 Improve the structure of the cylinder kiln head
To ensure the reliability of the structure, the cylinder kiln head originally assembled by 153 parts was changed to a cylinder composed of 12 guard plates with a radius of 2045mm, and the sealing cylinder was changed to a spray water cooling cylinder to cool the cylinder; the length of the cylinder originally extending into the hot smoke chamber was shortened from 1100mm to 550mm to reduce heat conduction.
02 Strengthen the structural strength of the cylinder kiln head guard plate
The general kiln head structure consists of a cylinder, a guard plate and a castable, and the cylinder and the guard plate are connected and fixed together by 4 bolts to form a whole. Practice has proved that the large deformation of the cylinder kiln head and the loosening of the guard plate bolts are important reasons for the fall of the castable. In order to strengthen the structural strength of the cylinder kiln head guard plate, 108 stainless steel reinforced anchor hooks were designed and manufactured, welded on the kiln head guard plate, and the connection area and strength of the refractory and the kiln head steel components were increased.
03 Improve the sealing effect of the kiln head
During the sintering process, the kiln head is located in a very special position, and it rotates rapidly with the kiln body, and is affected by the rapid change of temperature. The sealing of this part is the part that needs to be paid special attention and maintained in production. The original fish scales were installed by bolts and tightened with wire ropes. After long-term operation, the wire ropes loosened and failed due to high temperature, causing the fish scales to loosen and fail to seal the kiln head. In order to ensure the sealing effect of the kiln head, the fish scales of the kiln head were improved: the fish scales were added with an annular iron ring. And a tension spring device was installed. If it loosened, the tension spring could be adjusted to tighten the wire rope to ensure the sealing effect of the kiln head.
04 Improve the cooling effect of the kiln head
After long-term use of the equipment, its cooling efficiency has been reduced. For this reason, without affecting the rotation of the rotary kiln, the existing cooling air branch pipe was lengthened so that the wind produced by the cooling fan could enter the cold air hood in time to cool the kiln head evenly and ensure the cooling effect of the kiln head.
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