Abstract:
The cement production process is energy intensive both in terms of the thermal
energy (firing the kiln, drying and De carbonation) and electrical energy for
driving the numerous drives within the process line. The average specific power
consumption of the case study plant was 111 kWh/ton of cement with an average
peak demand of 9.7 MW. The high cost of electric power at 0.14 USD/kWh
results in very high cost of production that significantly lowers the company’s
profit margin and limits its competitive advantage. The generation of electrical
power from waste heat recovery would reduce the electricity power bill through
partially substituting the power procured from the national grid. This research
evaluated the potential that the plant has for generating electrical power from
the hot waste gases vented into the atmosphere and it was found that the plant
has the potential to generate 3.4 MWh of electrical power. This results to a
net potential to generate 2.89 MWh of electrical power after factoring in the
auxiliary power consumption by Waste heat recovery plant system at 15%. This
ultimately gave a reduction of 33% in the electricity power bill of the case
study plant. The paper recommends the installation of a steam rankine cycle
for the power generating plant. In this work the authors designed the steam
boilers for the waste heat recovery plant for conversion of thermal energy to
electrical energy, selected a commercial steam turbine and evaluated its economic
feasibility and established that the designed plant would have a simple payback
period of 2.7 years.
