Calculation And Software Implementation Of Heat Loss Through A Cement Rotary Kiln Based On Infrared Image

Under current circumstances of resource shortage and energy crisis, energy conservation and emission reduction, strongly advocated by the government, have become the only way out for the survival and development of cement industry, which is one of the most energy intensive industries. As the main equipment of cement production, the rotary kiln is the most energy consuming part, where the heat loss is also significant. However, much less attention has been paid to the research about the heat loss of the kiln shell, directly resulting in simple and rough calculation method as well as relatively-weak waste heat recovery technology. Since the improving space of energy-saving technology of the kiln is reduced gradually, some new ideas about how to achieve energy saving lie on management and operation. The energy lost from the surface of the kiln reflects the performance of the rotary kiln and the influence of operating parameters to some extent. So there is a certain guiding meaning for optimization and energy management of the cement kiln on the study of heat dissipation model and calculation in it.The present work was devoted to the discussion about the energy lost from the surface of the kiln. Actual data and infrared images, which were collected from a cement plant located in Jiangxi, were used in the study about heat loss through the kiln shell.The model of calculation was constructed as follows. Firstly, based on the mapping relational model of gray value and temperature value, temperature field of the surface of the kiln, which was running for nearly a month, was obtained from the acquired infrared images using the infrared image acquisition system of cement kiln. Then, the defining scope of burning zone was got by comparing the cylinder axial temperature, the infrared heat maps and physical diagram of the kiln. Next, the calculating model of the heat dissipation was built from two aspects of convection and radiation, furthermore the establishment was based on actual conditions and thermodynamic analysis of the cement kiln. Combined with field data, the appropriate model parameters were chosen to calculate the heat loss of the kiln shell. And the numerical results can show the changes of heat loss at different moments every day.A set of calculation software of heat loss based on the above calculating model was developed by LabVIEW programming. Without any additional hardware investment, the software can use the infrared images collected by the thermal imager to realize the visual monitoring and analysis of the heat loss of the cement kiln under different periods and different working conditions. Theoretical analysis of the heat loss calculated by the software was presented in this paper as well. At first, the economic analysis showed that the daily direct economic loss resulted from the heat loss of the cement kiln is about ￥ 3700 per day. Secondly, the statistical k-means clustering method was used to analyze the relation between several parameters of the cement kiln (coal feed rate for kiln head, material feed rate and kiln speed) and the heat loss of the kiln shell. This work can allow cement plant managers to assess the performance of the rotary kiln and the operation level of workers more effectively and efficiently. Besides, it can also provide data support for the economic operation and energy standards of the cement kiln. Ultimately the purpose of energy-saving management can be achieved.