Modelling for integrated energy optimisation in cement production

Energy costs play a major role in the cement production process. As much as 60% of total cost is allocated to energy and 18% to the consumption of electrical energy. Historically, energy cost savings were achieved by large infrastructure upgrades. These upgrades are often costly and lead to interruptions in production. In this paper the operation of all the energy intensive components of the cement production process are identified, modelled, integrated and optimised for minimum operational costs while meeting production targets. This integrated approach allows for simulation of the collective effect of individual system components. The model incorporates constraints such as maintenance, production and dynamic energy costs. No published research could be found where these constraints are incorporated into a single operational modelling system. The system was implemented on three different cement plants and a total electricity cost saving of R 8.5 million was achieved. This highlights the practical significance of an integrated systems approach to energy cost savings.