Assessment of energy and exergy efficiencies of a grate clinker cooling system through the optimization of its operational parameters

Department of Mechanical Engineering, Faculty of Engineering, University of Malaya, 50603 Kuala Lumpur, Malaysia
Energy (Impact Factor: 4.16). 10/2012; 46(1):664-674. DOI: 10.1016/

ABSTRACT Grate coolers are widely used in cement industries to recover heat from hot clinker, coming out from the rotary kiln. This study focuses on improving the energy, exergy and recovery efficiencies of a grate cooling system through the optimization of its operational parameters such as masses of cooling air and clinker, cooling air temperature, and grate speed. It has been found that the energy and recovery energy efficiencies of a cooling system can be increased by 1.1% and 1.9%, respectively, with every 5% mass increases of cooling air. Similarly, it has been estimated that energy and recovery energy efficiencies can be increased by 2.0% and 0.4% with every 5% increase of cooling temperature. The exergy and its recovery efficiencies found to be increased by 3.6% and 2.2%, respectively, for the same condition. Energy efficiency and energy recovery efficiencies are increased by 3.5% and 1.4% with every 9.1% increase of grate speed. Using heat recovery from the exhaust air, energy and exergy recovery efficiencies of the cooling system found to be increased by 21.5% and 9.4%, respectively. It has been found that about 38.10% and 30.86% energy cost can be saved by changing mass flow rate of clinker and mass flow rate of cooling air, respectively.

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    ABSTRACT: In the present paper, a numerical study is presented to investigate the cascade utilization of waste heat in sinter cooling bed. With the aid of CFD (computational fluid dynamics), a two-dimensional unsteady mathematical model, which would significantly reduce the computational time, is established to describe three-dimensional steady flow and heat transfer in sinter cooling bed. The Brinkman–Forchheimer extended Darcy model and the LTNE (local thermal non-equilibrium) model are employed to describe flow and heat transfer in sinter cooling bed. And the reliability of this mathematical model is validated with both related simulation and experimental work. And then, numerical simulations are conducted to examine the effects of different operating parameters on the cooling air temperature and waste heat utilization quantity. Furthermore, the waste heat grade and quantity are taken into comprehensive consideration in energy and exergy analysis. The results indicate that, both the quantity and quality of waste heat utilization would be improved by increasing sinter cooling bed height, trolly's moving speed and sinter heat flux. Meanwhile, it is also found that, with different assignments of cooling air flow rate, the quantity and quality of waste heat in sinter cooling bed would not be improved at the same time.
    Energy 04/2014; · 4.16 Impact Factor
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    International Journal of Engineering and Technology. 01/2012; 4(5):665-667.
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    ABSTRACT: Based on numerical simulation work in sinter cooling bed of our previous work, AEG (annual energy gain) is obtained on energy and exergy analysis under WHCU (waste heat cascade utilization). In the present paper, a method that integrates economics and energy analysis of a sinter cooling bed is proposed. Firstly, the symbolic regression is employed to find an accurate correlation between operational parameters and AEG. In order to improve the performance of GPLAB (genetic programming toolbox) of MATLAB environment, the symbolic regression is modified by adding new function modules into GPLAB. Then, the cost model is established to evaluate effects of operational parameters on EAOC (equivalent annual operational cost). Finally, the CBR (cost benefits ratio) is calculated to assess the comprehensive performance of the sinter cooling bed. Furthermore, for the purpose of optimising CBR, the method of Genetic Algorithm (GA) is adopted. The studied cases show that, it is an effective way to obtain optimal sets of operational parameters in a sinter cooling bed within the range of operating conditions. The optimisation results show that, the CBR based on the first law and second law of thermodynamics could be reduced by 18.4 % and 29.8 % when the optimal sets of parameters are employed.
    Chemical Engineering Transactions 01/2014; 39. · 1.03 Impact Factor


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May 27, 2014