Increasing efficiency and reducing pollutants in cement industry by thermodynamic and exergoeconomic methods

Cement industry consumes large amounts of energy since 1850's. The current processes which have been used for decades are really need to be revised, and very important precautions and innovations are needed to decrease the energy consumption. There are no considerable improvements in processing techniques and that makes the cement industry one of the top two manufacturing industry sources of greenhouse gases. Thus, this research focuses on the methods and applications to improve the cement production process by reducing specific energy consumption and emissions. A modern cement production factory has four main energy consuming processes which are milling, precalcination, complete calcination and cooling. A program in EES (Engineerin Equation Solver) was prepared to calculate all performance parameters for the processes such as specific energy consumption (SEC), emissions, heat transfer rate, first law and second law efficiency values of each unit. The program was based on thermodynamic and exergoeconomic methods. During this research, the performance parameters of each main energy consuming unit for a cement factory are calculated. The performance parameters of a conventional cement production plant are investigated. Comparing the results obtained from theoretical analysis with the experimental data taken from Gaziantep Cement Factory, the most suitable performance parameters for cement production are determined. It is found that, among of the plant components, the maximum energy consumption rate occurs in the rotary kiln as 54.85 MW that is 59.82 % of total exergy consumption in the plant. The specific exergetic cost of the farine, clinker and cement produced by the cement plant are calculated to be 50.52 USD/GJ, 126.41 USD/GJ and 170.55 USD/GJ respectively. The total manufacturing costs for farine, clinker and cement are calculated to be 3.8 USD/ton, 33.11 USD/ton and 41.84 USD/ton, respectively. The exergetic performance results indicate that the rotary kiln is by far the most destructive unit in the plant. As a result of the implementation of this study, the SEC values and emission rates should be reduced by the application of different methods.