Damage analysis of inner lining of alumina clinker rotary kiln

 

1.The slurry in the alkali-eroded alumina clinker kiln is mixed with a considerable amount of alkaline substances such as CaCO? and Na?CO?, which are soaked or adhered to the lining surface at high temperature and penetrate into it, in addition to their own chemical changes , and may also react with the lining to form a two-component tissue along the cross-sectional direction, destroying the tissue structure of the original lining, thereby reducing the strength of the lining. When the temperature or composition of the material changes greatly, the two phases separate and the lining peels off. It is easy to prove this point by analyzing and comparing the petrographic structure of the peeled block, the residual brick and the original brick. It can be seen from the alkali existence state of the preheating zone and the decomposition zone that these two working zones are most severely affected by alkali erosion, but the strength of the material itself at this stage is low, and the lining is damaged by impact and friction and wear is small, so these two The damage of the working belt is mainly caused by alkali erosion.


2.Process damage.

(1)?The kiln skin is the protective layer of the lining of the firing zone. It is a prerequisite to ensure the stable and high output of the clinker kiln to maintain the thermal system of the kiln stably and maintain the kiln skin well. When hanging the kiln skin, the kiln skin must be melted and adhered to the surface of the lining, otherwise the working surface of the lining will be burned, but after the kiln skin is hung, as long as the ratio of aluminum to silicon in the slurry is stable and the fluctuation is small, the firing temperature Constant, strong kiln skin, which greatly reduces lining wear. When the content of aluminum and silicon in the material is relatively large, the sintering temperature of the material is required to be increased, so that when the clinker is sintered, the kiln skin is also sintered, and the material enters the process with the material. The scouring, friction and wear of the dough are large. In order to protect the lining, the operation of hanging the kiln skin has to be repeated. Therefore, when the aluminum-silicon ratio fluctuates many times, the kiln skin is damaged and the lining is damaged.

(2) When there is a deviation between the flame length and the position of the coal injection nozzle, the sintering efficiency of the material will be reduced, and the kiln skin and the lining will be strengthened by the high temperature scouring effect, which will also shorten the life of the lining.

(3) When the kiln skin is hung on the firing zone, a layer of kiln skin thinner than the firing zone will also be attached to the lining of the adjacent pre-decomposition zone, which is called the auxiliary kiln skin. Generally speaking, the auxiliary kiln skin also has a protective effect on the lining, but this layer of kiln skin is mostly a low-temperature eutectic melt of an intermediate compound, which is easy to adhere. When the reducing atmosphere and the temperature in the kiln fluctuate, this layer of kiln skin is also easy to fall off. When the reducing atmosphere and the temperature in the kiln fluctuate, this layer of kiln skin is also easy to fall off, and adheres to the inner lining surface, so that the inner lining is affected by Therefore, this lining should have sufficient strength and corrosion resistance.


3. The maintenance of various parts of the mechanically damaged kiln system is not synchronized, causing the kiln to be shut down for many times, so that the lining is often in a state of rapid cooling and rapid heating, resulting in cracks, until the seepage material enters the alkali intake, thereby peeling off. The kiln was stopped for inspection, and it was found that the linings of individual sections were squeezed, stretched, and broken or dropped, which was caused by the distortion of the kiln body, indicating that the kiln rotation was not concentric, and the kiln line was not correct. In addition, the mechanical failure of the large ring gear position causes vibration, which makes the lining at this position unstable, resulting in looseness and bricks. The main reason for the damage to the material of the cooling belt is that the material in this section has high strength and large block size, and the lining is directly worn or smashed. The ordinary clay brick has low strength, is not wear-resistant, and evenly thins in a short time. , short lifespan.


4.The quality of the kiln lining is damaged due to the poor quality of the lining, which also affects the life of the lining. Moreover, when the quality of the lining is defective and the kiln skin cannot be successfully hung again, it will directly cause the kiln shell to be damaged. Red and discontinued. There are mainly two direct situations in which the production was stopped due to the quality of the lining construction, one is the brick drop; the other is the damage to the ring seam.

(1) Drop bricks. During the operation of the rotary kiln, the red kiln caused by the pull-out or falling off of the whole brick in the inner lining is called falling brick, which usually occurs soon after the construction of the inner lining is completed. The reasons are all related to the poor quality of the inner lining. have a direct relationship. First, the use of bricks is not suitable and the mud is not full. The size of the dropped bricks is too small or does not match the size of the surrounding bricks, and the mud is not full, causing the bricks to loosen and fall off; the second is the phenomenon of misplacement during masonry, the placement of the bricks is not perpendicular to the kiln skin, and the working surface is not vertical. The ash seam at the bottom of the ash joint is small, and the pressure loses the axial force and falls off; the third is that the masonry of the lock brick is not strict, mostly because the lock brick processing is rough and cannot meet the requirements and the ash seam is too large.?

(2) The annular seam is damaged. After the kiln was running for a period of time, the ring seam between the adjacent two ring bricks became wider or the masonry at the ring seam was damaged, and there was no lining protection outside the ring seam, which led to the shutdown of the red kiln. This is mainly due to the unevenness of the ring seam. When the surface of the ring seam is an inclined ellipse and is not perpendicular to the axis of the kiln, the ring seam will become wider after operation; when the ring seam is uneven and has steps , during operation, uneven force at the step will occur and damage will occur.

Wanhao is a manufacturer who is specialized in designing various kinds of furnace and making refractory products for electric furnace, ladle, tundish, blast furnace, AOD furnace, IF furnace, etc.

Article Source:Damage analysis of inner lining of alumina clinker rotary kiln

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