Parameter optimization of gas–solid heat transfer process in sinter packed bed based on further exergy analysis

Abstract

Based on the porous media and local non-equilibrium thermodynamics theory, a two-dimensional steady numerical model of the annular cooler was established, in the condition that the moving speed of the bed was defined in the model. The modified Ergun formula and experimental Nusselt number were used to accurately describe the gas flow and gas–solid heat transfer process in the sinter bed. The reliability of the calculation model was verified by comparing with the experimental data. The parameters such as the cooling air volume distributed per kg of sinter, sinter bed height, waste heat recovery sector length and inlet air temperature were discussed. The further exergy which considers the pressure resistance was put forward as an optimization criterion, and the optimal parameter combination was obtained by the orthogonal experiments. The results show that the exergy increased with sinter bed height and inlet air temperature. Meanwhile, there are optimal parameter values for cooling air volume and length of waste heat recovery sector, which are 2.05 m3/kg and 56 m respectively. Finally, according to orthogonal experiment, when the annular cooler is in the optimal working condition, the exergy of the system reaches to 217.57 MJ/h, which is 32.04% higher than the standard condition. The results would provide some guidelines for the designs and optimization of operation parameters for the sinter cooling process.