Application of Industrial Kilns In Cement Industry

 

Industrial kilns are rotary kilns often used in the industrial field. Industrial size kiln is an important equipment in the process of new dry cement production, and its design is directly related to the output and quality of cement. Industrial size kiln has become necessary equipment for calcination of cement clinker due to its advantages of large production capacity, a high degree of automation, high product quality, and low energy consumption.

Function of Industrial Kilns in Clinker Calcination

The production of new dry process cement mainly includes raw meal preparation, clinker burning and cement preparation. The burning of clinker needs to be carried out in an industrial size kiln.

1. Preheating of raw meal

 

The raw meal needs to be preheated before entering the industrial size kiln for calcination. To heat the raw meal to the expected 800°C, the equipment needed in this link is a multi-stage cyclone preheater. The raw meal is fed from the link duct of the first-stage cyclone, driven by the high-speed ascending airflow, turns and moves upward, and is finally sent into the cyclone. Under the action of airflow and gravity, the material falls along the wall of the cylinder and enters the feeding pipe of the next cyclone cylinder. The material repeats the above movement and exchanges heat with the hot exhaust gas in the preheater. After the preheating is completed, the temperature of the raw meal can reach the target preheating temperature of 800°C, and the hot exhaust gas is reduced from 1100°C to about 300°C. Because the hot gas in the preheater is the reuse of waste gas generated by industrial kilns, unnecessary waste of fuel can be avoided, and the heat consumption of cement clinker firing can be reduced.

2. Material is decomposed in the precalciner

The preheated materials need to be sent to the precalciner for decomposition. The first-stage cyclone at the bottom of the preheater is connected to the entrance of the precalciner, and the material is sent into the furnace through a pipe. According to the different fuel used, the precalciner heating method will be different. Take the precalciner of a coal-heated rotary kiln as an example. Pulverized coal is injected into the precalciner and mixed with raw meal. The temperature of the pulverized coal increases rapidly with the furnace temperature, reaches the ignition point and burns rapidly, and at the same time transfers energy to the material. Under the action of high temperature, the carbonate in the raw meal quickly absorbs heat, decomposes, and releases carbon dioxide.

3. Material is sintered in the industrial kilns

Through the pre-decomposition of the precalciner, the decomposition rate of the material can reach more than 90%, thereby reducing the heat load of cement calcination in the industrial kilns and improving the utilization rate of fuel such as coal powder. The materials enter the industrial rotary kiln and undergo further sintering and decomposition under the action of high temperature. With the continuous rotation of the industrial kiln body, the material also moves forward. The heat generated by fuel combustion causes a series of chemical reactions in the material, and the final product is tricalcium silicate, the main component of cement clinker.

4. Material cooling

After calcined in the industrial kiln, cement clinker needs to be sent to grate cooler for cooling. The cooling machine adopts the cooling mode of direct air blowing, and the cooling air is blown vertically into the bottom of the machine to cool the cement clinker directly. The grate cooler has good cooling effect and can cool the clinker in a short time. It also has the advantages of low discharge temperature and excellent cooling capacity.