Numerical analysis of the exhaust gases recovery from a turbine CHP unit to improve the energy efficiency of a ceramic kiln

The paper focuses on the analysis of an industrial ceramic kiln in order to improve the energy efficiency and thus the fuel consumption as well as the pollutant emissions. A lumped and distributed parameter model of the entire system is constructed to simulate the performance of the kiln under actual operating conditions. The model is able to predict accurately the temperature distribution along the different modules of the kiln and the operation of the many natural gas burners employed to provide the required thermal power. Furthermore, the temperature of the tiles is also simulated so that the quality of the final product can be addressed by the modelling. CFD simulation is also employed to determine the heat transfer coefficients between the tiles and the different components of the system. The numerical approach is used for analysing the effects of the exhaust gases recovery from a CHP turbine unit on the overall efficiency of the kiln. In particular, the CFD approach is adopted for investigating the best location for the hot gases injection within the pre-heating zone of the kiln. The influence of the exhaust gases on the heat exchange between the tiles and the air flow is addressed and the improvement on the convection heat transfer is determined. By means of the 0D/1D the behaviour of the entire kiln is evaluated with particular attention to the fuel consumption. The employment of the CHP exhausts recovery demonstrates to be beneficial both in terms of a reduction of the electric energy requirement of the system for powering the many blowers adopted and in terms of increased efficiency of the kiln.