A factory has two pre decomposition clinker production lines, including No. 1 kiln Φ three point two × The 48m rotary kiln was put into operation in 2008. Since the operation, with the technical support of Kerui refractories, through the continuous summary of the use of kiln refractories, the use situation has been better and better year by year. In 2011 and 2012, the annual operation rate was above 91%, and the clinker output reached 430000 tons. From October, 2011 to December, 2012, the whole kiln has not been replaced with refractory bricks for 404 consecutive days, and no red kiln accident occurred after 840 days of use of refractory bricks at 16.2~21.4m vulnerable parts of the transition zone.
- Determination of batching scheme
The raw meal adopts 4-component proportioning, the coal adopts Shanxi good low volatile coal, the burner adopts advanced 4-channel pulverized coal burner, and the clinker three rate values are determined as: kh:0.90-0.94, sm:2.9-3.1, im:1.5-1.7.
- Refractory brick masonry
First, a specially assigned person shall be responsible for supervising the entry of magnesia bricks into the factory, and the type, specification, quantity and manufacturer of bricks shall be strictly inspected and accepted; Secondly, in the process of bricklaying (such as residual corner damage), it should not be used when it is squeezed and cracked due to moisture, otherwise the hidden danger will be aggravated; Third, pay attention to masonry quality. Professionals often say: three materials, seven masonry. During bricklaying, magnesia bricks directly bonded shall maintain a certain expansion joint due to their high expansion coefficient, while silica mullite bricks shall be used sparingly due to their small expansion coefficient. The refractory mud shall not be too thick as long as it is leveled. The smaller the brick joint, the better. Finally, it should be strictly checked. After the bricklaying is completed, special personnel shall carefully inspect it. Each brick in each ring shall not be missed. As long as it can be inserted into the iron, it shall be pulled tightly.
- Hang the first kiln skin
Pay attention to maintaining the stable thickness and length of kiln skin. The newly built bricks are fired and fed for the first time, there is no kiln skin protection in the kiln, and the refractory bricks are completely exposed to high-temperature flame for calcination. It is very important to hang the first kiln skin and inject the first raw material. During this process, it is not allowed to stop the kiln or the fire bricks will burst or be crushed due to rapid cooling and heating. The ignition and temperature rise process shall adhere to the principle of "slow temperature rise, no tempering", and generally can be completed from the initial ignition to feeding for about 8 hours.
The kiln skin hanging stage should be unremitting. Generally, it is enough to keep about 90% of the normal feeding amount. The kiln speed should be stable rather than fast. Otherwise, the heat in the kiln is unstable. The three shifts shall keep the same calcination. No fire or top fire is allowed. The position of the coal pipe shall be moved back and forth in a small range to make the kiln skin flat and uniform in thickness.
- Keep good flame shape
Maintaining good flame shape is the responsibility and obligation of every fire watcher. A good flame should be lively, smooth and powerful, with a certain fire intensity, and its thickness and length should be appropriate. It is very important for prolonging the service life of refractory bricks that there is no bifurcation and no scouring of kiln skin. The main causes of abnormal flame are: the head of the coal injection pipe is damaged, which generally refers to the burning or abrasion of the head of the coal injection pipe; The air duct and coal air duct are worn through, and air channeling causes serious flame deformation. In case of flame bifurcation or deformation, the coal pipe shall be replaced in time or the coking on the head shall be cleaned to find out the cause. Secondly, the poor ventilation in the kiln results in the unsmooth flame. There are rings or large balls in the kiln. The flame is not smooth, and the fire is held in front. The main reasons are the accumulation of materials in the smoke chamber, the upper necking and scaling, or the large balls or long thick kiln skins in the kiln. In case of fire suppression during calcination, first reduce the number of units and clean the smoke chamber and necking crusts in time. If there is a large ball, immediately burn the ball and ring to ensure good ventilation and smooth flame in the kiln.
- Optimized configuration of refractory bricks
After continuous exploration and in combination with the process characteristics, the following optimized configurations of refractory materials have been carried out:
Front kiln mouth: as the kiln speed is fast, the temperature of clinker out of the kiln is high and the abrasion is serious, so the front kiln mouth is made of special castables with good wear resistance, high temperature resistance and thermal shock stability.
Front end of the firing zone: considering the large ball or the high length of the kiln mouth ring, 1.2m silicon molybdenum brick is configured in front, which has good thermal shock stability, wear resistance and scouring resistance.
Firing zone: directly bonded magnesia chrome brick is selected from 2m to 15m. This brick has high fire resistance, can withstand high temperature of about 2000 ℃, high load softening temperature, and can withstand high temperature. In addition, it is easy to stick to the kiln skin. The brick is closely combined with the kiln skin and is not easy to fall off the kiln skin. Therefore, this brick is suitable.
Transition zone: this part is the most vulnerable part of the new dry process kiln. The main kiln skin here is unstable, and the attached kiln skin changes frequently. If there is a big ball, it will linger here and smash the bricks, resulting in an accident. Therefore, silicon molybdenum bricks with good wear resistance, erosion resistance, chemical corrosion resistance and high thermal shock stability shall be selected for this part. The silica mullite bricks selected at the position of 16.2~21.4m have been used for more than two years, but there is still no brick falling out of the red kiln.
Front transition zone: common phosphorous brick can be selected. As the working conditions here are relatively good, common phosphorous bricks have been used for nearly 5 years since january2011.
Rear kiln mouth: select alkali resistant and scouring resistant castables. The optimized allocation of refractory materials can greatly improve the operation rate of rotary kiln, save maintenance funds and improve clinker quality. It has been proved by practice that the refractory material configuration scheme for the precalcining kiln is ideal.