Rotary kiln lining brick is an important equipment to ensure the continuity of cement clinker production. Therefore, if the rotary kiln is an important machine, then the refractory brick lining is the motor. However, there are many cement plants that will have refractory bricks falling off in the kiln when they build a new rotary kiln, and they don't know what to do. What is the reason? The main reason is that the refractory bricks are not locked during the masonry process.
1: Analysis of the causes of brick drop during the drying process of refractory bricks
(1) Improper use of cement. In the masonry process, it is necessary to bond the refractory bricks of the rotary kiln masonry with mortar, and it is also necessary to level the refractory bricks with mortar. When the mortar is applied unevenly, it is easy to cause the proportion of refractory bricks to be unbalanced, resulting in the tilt of the brick surface and the inconsistency of the size and head of the brick. The use of mortar has a particularly prominent impact on winter construction. Due to the decrease in ambient temperature, the fluidity of the refractory mortar deteriorates and the phenomenon of freezing appears. When the whole ring is locked with a channel steel plate, the mortar has frozen, but in the process of heating up the kiln body, the mortar begins to melt, and the mortar in the brick joint is lost under the gravity extrusion of the refractory bricks, resulting in the increase of the refractory bricks in the ring joint, loosening and falling off, resulting in the brick falling accident.
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(2) The locking degree of each circle of refractory bricks is insufficient. When laying bricks with a brick laying machine, it is often used to lock each circle of bricks in place at one time. Only when it is properly locked does the next ring begin to be built. After all the bricklaying is completed, a joint steel plate is added to the top of the refractory bricks in the kiln from the end of the kiln to the kiln head with a sledgehammer. This masonry method has a disadvantage: because it is not locked at the beginning, the refractory bricks will inevitably slide downward under the action of their own gravity, resulting in the refractory brick floor and the inner wall of the kiln are not tight, and there is a void phenomenon. When the void phenomenon is formed, the locking joint steel plate will only increase the tightness between the circular refractory bricks and the bricks, and the void problem will not be changed when the temperature rises to a certain extent, and the void phenomenon will be aggravated when the rotary kiln needs to be turned intermittently.
(3) The pressure of the brick laying machine is insufficient. The working pressure of the brick laying machine is not enough to support the refractory bricks, and it cannot be brought close to the kiln barrel, resulting in a slight void phenomenon. During the construction process, it is necessary to ensure that the air supply pressure of the air compressor is between 0.55mpa~0.65Mpa, which is our weakness. During winter construction, due to the long compressed air pipeline connected to the masonry machine and the different thickness of the connecting pipe, the air compressor has the problem of oil-water separator, the gas storage tank does not release water frequently, and the connecting pipeline leaks. , the air supply pressure of the brick laying machine is insufficient, and the insufficient air supply pressure will lead to insufficient pressure on the top brick of the brick laying machine, forming a void at the bottom of the refractory brick.
2: Solutions and precautions
(1) When locking bricks, the bottom surface of the refractory bricks of the rotary kiln must be as close to the inner wall of the kiln as possible. After you lock one ring, you can place the next ring. After the masonry is completed, the lock iron plate should be added in the rotary kiln. When tightening the iron plate, the position below the centerline of the rotary kiln should be tightened as far as possible to ensure that there are locking iron plates at 90°, 180°, 270° and 360° around the circumference of the rotary kiln, and two slotted plates are allowed.
(2) Before masonry, the supporting mortar of the refractory bricks of the rotary kiln should be selected, and its materials, including various physical and chemical indicators, should be matched with the refractory bricks. Mortar that is not allowed to be used does not match the refractory brick material.
(3) Before masonry, a circumferential line should be set up every 2m in the kiln shell, and the circumferential line should be parallel to the girth weld of each section of the cylinder. When laying refractory brick floors, it must be constructed according to the axis and ring line. Check every 5 revolutions to measure whether the distance between the ring peak and the circumferential line is consistent. Adjust the refractory brick back ring according to the distance deviation. It is not allowed to be done in one step and should be adjusted gradually. At the same time, it should be controlled within 2 mm.
(4) Try to avoid cutting and processing bricks. If the length of the processed brick is less than the length of the original brick, the adjacent standard brick should be removed. Standard bricks and small processing bricks should be used for staggered masonry to eliminate ring peaks. Staggered masonry must be wet masonry, and the effect of high-temperature mortar is good.
Conclusion: The masonry of refractory bricks in rotary kiln is best selected by experienced construction team. Before the material enters the factory, some acceptance tests should be carried out to prevent the use of substandard products. The rotary kiln masonry refractory bricks need to be subject to static acceptance and dynamic acceptance before being delivered to the owner.