- Time:Mar 24, 2023
The firing of refractory materials enters the kiln with the kiln car as the carrier, and the way of loading the kiln car has a huge impact on the firing process of refractory materials. The load softening temperature of magnesia refractories for cement kiln is relatively high, and the variety is simple. Most refractory manufacturers use the way of loading products vertically or sideways, and some manufacturers use the way of loading products flat. However, All kinds of loading methods have their own characteristics, and this article analyzes this content.
1. The method of loading the kiln car
（1）Vertical loading
The magnesia refractories used in cement kilns generally adopt conventional brick types, such as B320, B620, B322, B622 and their slotted bricks. The length and width of the above brick types are similar, tending to be square. Vertical loading is a common loading method adopted by most manufacturers.
The magnesia refractories used in cement kilns are loaded vertically, and there are appropriate gaps between the products on the kiln car, so that the products can be heated evenly during the firing process, and the output and quality are stable. The stack is stable, and it is not easy to have safety problems such as stacking.
（2） Side loading
Side loading is rarely used on magnesia refractories for cement kilns. Because it is loaded on the side, after the products are fired, there will be scales in the width direction, and the difference between the upper part and the lower part will be large, which will affect the use of kiln masonry. The upper layer adopts side laying.
（3）Flat loading
In the refractory industry, ordinary bricks are generally rarely loaded flat, because flat loading can easily lead to product distortion, under-burning, and unstable brick stacks. Usually, only the top of the brick stack is laid flat, and the lower part is loaded vertically to ensure the height of the brick stack. However, with the optimization and adjustment of the loading method and the redesign of the plain packaging method, after the corresponding products are fired, not only can the product defects caused by the traditional loading method be reduced, but also the appearance quality of the product can be effectively improved.
When packing flat, care should be taken to avoid seamless stacking and loading of multi-layer products, which will cause insufficient heat conduction and radiation, and the firing temperature in the middle of the product will not reach the firing temperature, which will eventually cause under-burning in the center of the product. When loading flat, two bricks can be used as a unit, and the odd and even layers are reversed to form an approximate horizontal plane. The misplaced placement between each two layers not only ensures the stability of the brick stack, but also increases the size of the finished product. The contact area with the air flow can make the product evenly heated to reach the firing temperature of the product, and there will be no quality problems such as under-burning.
2. The influence of different loading methods
Vertical loading is the most commonly used loading method for magnesia refractories used in cement kilns. It has many advantages, but it also has certain disadvantages. Vertical loading will cause different parts of the products on the same kiln car to shrink differently after being fired at high temperature, because the height of the brick stack is 700~900mm, the lower product bears the weight of the upper product and is in a state of compression, and the upper product is only affected by its own weight , so when firing at high temperature, a series of physical and chemical reactions occur in the product, and the size will also shrink under the influence of external gravity. The length deviation of the upper and lower parts of the product on the same kiln car is about 1%. This size change will cause unevenness inside the kiln body when the refractory material is built on the cement kiln, which will affect the service life. However, some manufacturers will consider this factor when forming blanks, and increase the scale of the lower product, thereby reducing the overall size deviation range of the product.
When loading on the side, after the products are fired, the same reason as loading on the vertical, there will be scale reduction in the width direction, and the shrinkage difference between the upper and lower parts is relatively large, while the products are ring-built on the cement kiln, and the dimension requirements in the width direction Strict, otherwise there will be large brick cracks on the inner wall of the cement kiln after masonry, which will cause difficulty in masonry and affect the service life.
Adopting the adjusted flat loading method, after the product is fired, the thickness dimension changes slightly, the deviation of the upper and lower parts is within 0.5%, and the length and width dimensions basically remain unchanged. In this way, when the fired finished bricks are built on the cement kiln, the inner surface of the cylinder is even and smooth, which can increase the service life.
In addition, with the development of industrial information technology, the level of equipment automation in the refractory industry is gradually improving. The use of flat loading is also conducive to the automation of loading and unloading kiln cars and improving work efficiency. When laying flat for loading, since the same layer of products is placed in the same direction, the robotic arm can grab one or more products at the same time and place them, which greatly improves work efficiency and reduces waste caused by human factors. However, if it is placed vertically or sideways, the mechanical arm loading and unloading kiln car has certain limitations, and the difficulty of automatic design will increase accordingly.
3. Summary
By comparing the three loading methods of magnesia refractories used in cement kilns, when the designed flat loading method is adopted, it can not only effectively improve the pass rate of the products in the firing process, but also reduce the error range of the appearance size of the products. Thereby improving the service life of the product in the cement kiln. In addition, laying flat is also convenient for loading and unloading kiln cars to realize automation and improve work efficiency.
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