Thermal Analysis for Rotary Kiln in Cement Industry

Cement kiln

Production Capacity: 180-10,000t/d

Rotate speed (r/min): 0.26-3.9

Rotary kiln in cement industry is the key equipment for dry and wet cement production. Through the measurement and analysis of the heat in the rotary kiln, it can help cement manufacturers to adjust equipment parameters in time, thereby improving the quality of cement clinker. Therefore, it will also play a key role in cement production.

However, the measurement and control of thermal power in cement kiln is more complicated. Its complexity is mainly reflected in the occurrence of high error rates in the measurement process. Through the research of the existing equipment, it can be found that in the calculation process, the use of the cement kiln heat transfer model in cement industry will produce more complicated data, and the more accurate data cannot be obtained in the calculation, and the operability is poor. Therefore, the thermal measurement of cement kiln should comprehensively analyze the chemical reaction and the dominant factors of pulverized coal, so as to establish an accurate model. In this way, the solution can be more accurate, so that the temperature distribution of the rotary kiln in cement industry can be analyzed, which can provide more technical support for cement production.

Measurement and analysis of heat in rotary kiln
Measurement and control of thermal power in cement kiln

For types of kiln in cement industry, the internal heat is mainly formed during the combustion of fuel. Taking the coal-fired rotary kiln as an example, the heat transfer effect will be formed in the process of pulverized coal combustion. At the same time, in different positions of the rotary kiln, the material will also undergo chemical generation, accompanied by the generation and absorption of heat.

Combustion Analysis of Pulverized Coal

Generally, the combustion of pulverized coal is carried out on the top of the cement rotary kiln. The combustion of pulverized coal produces a large amount of smoke and dust, which is combined with the water vapor in the cement rotary kiln shell and forms a large amount of smoke on the top of the kiln. The temperature of these flue gases is relatively high. Technicians can analyze the temperature of flue gas in a cement kiln according to the length of the flame.

Heat Transfer Analysis of Cement Rotary Kiln

In the process of cement rotary kiln heat transfer analysis, the main heat transfer mode and heat transfer coefficient can be analyzed. Because the heat transfer area in the rotary kiln is fixed, when analyzing the heat transfer problem of the rotary kiln in cement industry, the focus is on the calculation of the heat transfer coefficient.

Heat transfer form of cement rotary kiln

As the main source of heat in the rotary kiln, the heat generated by the flue gas is transferred in the wall of the rotary kiln through radiation, and at the same time it can transfer the heat to the material. The heat can be transferred inside and outside the wall of the rotary kiln, and different heat transfer methods are adopted. The inner wall of the rotary kiln mainly transfers heat to the outside of the cylinder by means of heat conduction. And the outside of the cylinder body dissipates heat by convection, that is, to the surrounding environment.

Heat transfer coefficient of cement rotary kiln

Heat transfer of cement kiln
Heat transfer of cement kiln

The heat transfer coefficient of the material on the inner wall of the cement rotary kiln is mainly divided into the heat transfer coefficient of the material in an unstable state and the heat transfer coefficient of the material covering the wall of the cement kiln. Add these two coefficients together to get the heat transfer coefficient.

In the process of analyzing the calorific value of the open cement rotary kiln wall, the heat transfer coefficient of the material and the flue gas is analyzed, and the convective heat transfer coefficient of the flue gas is analyzed, and the convective heat transfer coefficient of the flue gas and the material can be obtained. When the wall of the rotary kiln is open, a strong heat transfer effect can be formed, and the heat transfer coefficient detected at this time will be relatively large.

A large amount of radiation is generated in the cement rotary kiln during the production process. By analyzing the radiation coefficient, the radiation heat transfer coefficient in rotary kiln can be simplified, thus the absorption flue gas in the closed cavity and the radiation heat transfer coefficient formed on the surface of ash body can be obtained. Then, the radiative heat transfer coefficient is obtained by using the network simulation method combined with the heat balance equation.

To analyze the heat transfer coefficient of the outer surface of the rotary kiln, the heat dissipation value of the surrounding environment can be analyzed, and then the coefficient of convective heat transfer can be analyzed, and the two can be added. In the process of analyzing the convective heat transfer coefficient, the flue gas that cannot be rotated in the rotary kiln can be analyzed first, and then the heat transfer coefficient can be analyzed according to the forced convection method.