Energy, Vol.135, 128-137, 2017
Thermoeconomic and environmental analyses of a dry process cement manufacturing in Nigeria
In this study, the thermoeconomic and environmental assessment was performed to identify key energy efficient opportunities and technical improvement potentials of the production of dry cement in Nigeria. The process was divided into ten basic unit operations, which are: drilling, explosive charging, mucking and hauling, crushing, raw material preparation, pre-heating, pyro-processing, additive preparation, finish grinding and packaging. The analyses revealed that to produce a tonne of cement requires 3.12 GJ of energy at a cost of (sic)4875.41 ($25.66), and about 0.59 tonnes of CO2 is released to the environment. The most energy intensive unit operation is the pyro-processing operation, followed by the pre-heating operation with energy intensities of 2.22 and 0.60 GJ/tonne, respectively. However, the economic impact of the explosive charging unit, which seems to be less significant from the energy view point, is relatively high. To make the overall plant more energy and economic efficient, it was suggested that plant modification should consider the pyro-processing and pre-heating units together with the optimization of explosive charging unit, and the use of efficient prime movers for pumps and cooling fans. Furthermore, for maximum energy utilisation, uniform material flow in the pyro-processing and pre-heating unit is essential. (C) 2017 Elsevier Ltd. All rights reserved.