Modelagem numérica do perfil térmico na parede de um forno de cimento na operação normal e no processo de resfriamento

Abstract

With cement production on the rise, challenges such as high energy consumption and environmental impacts of the cement production process show the need to control, optimize and better know the production stages. In the cement manufacturing process, one of the most important steps is clinkerization, performed in a device called cement kiln or clinker kiln. The present work aimed to model the temperature profile along the wall of a clinker kiln of a cement industry in Brazil, considering both the normal operating condition (steady state) and the kiln cooling condition during shutdown (transient state). To this end, a MATLAB language algorithm was implemented for numerical resolution of the transient state heat equation in cylindrical coordinates using the Method of Lines. The equipment wall was discretized in space by the Finite Difference Method and the boundary conditions were determined by energy balance of the mesh nodes. The transient temperature field was integrated in time by the Predictor-Corrector Method, starting from a fictitious initial state until reaching the steady state corresponding to the kiln normal operating situation. Then, the boundary conditions were changed to simulate the cooling process and the temperature field was again integrated in time, using the steady state condition as the initial condition. The temperature profile obtained for the normal operating condition (steady state) is compatible with heat transfer fundamentals and presented a fit to industrial temperature data of the kiln shell with quality similar to that of other works in scientific literature. The curves obtained for the cooling process were compatible with other published studies. It was found that, under the conditions studied, it takes about three days for the kiln to reach an internal temperature compatible with the entry of the maintenance technician.