- Time:Mar 06, 2023
In order to reduce the content of tricalcium iron aluminate and tetracalcium iron aluminate (C3AF, C4AF) to promote the crystalline phase transformation of cement clinker, improve the strength of cement and ensure the quality of cement, cement clinker must quickly enter the grate cooler for rapid cooling after high temperature calcination, therefore, cement clinker should be rapidly cooled after the completion of sintering in the firing zone and discharged through the cooling zone and the kiln mouth area. According to the variation of coal injection tube and flame length of each enterprise, some enterprises call both cooling belt and kiln mouth as kiln mouth area.
In the production of large dry kilns, the cooling zone kiln lining is one of the weakest kiln linings in large rotary kilns. In the cooling zone, although the ambient temperature is not as high as the high temperature zone, and there is no flue gas corrosion, but restricted by the production process, the cement rotary kiln cooling zone are very short, the temperature of the clinker away from the kiln at the rotary kiln mouth is as high as 1400°C, and the temperature of the secondary wind into the kiln reaches 1200°C. The kiln mouth is almost completely exposed to the radiation of the high temperature flame at 1700°C.
As the kiln becomes larger and the output increases, the amount of clinker passed per unit time increases, the kiln mouth area is not protected by the kiln skin, the temperature of the clinker and large kiln skin that has left the firing zone decreases, and the cement clinker cools and crystallizes to form molten particles, the kiln mouth material tends to wear under the abrasion and scouring of the clinker with large particles and high strength at a high temperature of about 1400°C during the operation of the rotary kiln.
Since the first gear wheel belt area of rotary kiln is also in this position, mechanical stress and axial stress will also produce extrusion of refractory materials, so the front end of the kiln mouth must be poured with pouring material as a whole to fix the refractory bricks.
The substantial increase of secondary air temperature, the acceleration of kiln slope and rotational speed, and the absence of stable kiln skin at the kiln mouth require that the lining bricks must have good high-temperature volume stability to eliminate damage due to thermal stress, as well as high hot-state and cold-state strength and wear resistance to meet the requirements for cooling belt use.
At present, the substantial increase of wind temperature, the slope and speed of kiln, and the absence of stable kiln skin at the kiln mouth require that the lining bricks must have good high temperature volume stability to eliminate damage due to thermal stress, as well as high hot and cold state strength and wear resistance to meet the requirements of cooling belt use.
ZHENJIN REFRACTORIES developed steel fiber reinforced kiln opening special brick in 2009, which has high bulk density, high compressive strength, wear resistance, scouring resistance, overall masonry specification, can hang kiln skin in a lower temperature range, and can play the effect of using kiln skin to protect the lining brick, which better meets the requirements of large The kiln skin can be used to protect the lining bricks, which can better meet the requirements of large cement kilns for the kiln mouth area, and has been used well in Guotou Xindeng Cement, Mengdian Cement and other units. The use of kiln skin to protect the kiln mouth lining brick is a new technical means.
