Aspen Plus based simulation for energy recovery from waste to utilize in cement plant preheater tower

Cement manufacturing is an energy intensive and heavy pollutant emissions process. It is accountable for CO2, NOX, SO2 emissions and some heavy metal discharge from the manufacturing process which causes severe greenhouse effects. Waste derived alternative fuels are widely used for substituting the thermal energy requirement from fossil fuels and reducing the pollutant emission. In the current study, a process model of the preheater tower is developed using Aspen Plus simulation software based on the combustion mechanism. Preheater tower is part of the modern energy efficient cement plant which is responsible for most of the CO2 release as the calcination of the raw material occurs at high temperature in this section. The model is verified against measured data from industry and data available in the literature. This paper presents the effects of the flow rate of waste derived fuels on the energy efficiency and emission from the preheater tower. Three different waste derived fuels, namely tyre derived fuel, meat and bone meal and refuse derived fuel are considered for this study. Fixed substitution rate of conventional fuel by the alternative one has been considered to identify the differences among the selected alternative fuels. Results show that maximum 3% increase of energy efficiency and 2.5% reduction of CO2 can be achieved by using tyre for about 25% of thermal energy requirement. Simulation results presented in this paper offer a guideline for implementing selected waste derived fuels in cement industry. (C) 2014 The Authors. Published by Elsevier Ltd.