Fuel blending Options in cement pyro processing of Messebo Cement factory by Co firing of Sawdust and Coal

Abstract

This research assesses the technical, economic, and environmental viability of co-firing biomass fuels (eucalyptus sawdust, olea sawdust, and pine sawdust) alongside coal in cement manufacturing at Messebo Cement Factory. The evaluation emphasizes fuel blend composition, calorific values, combustion properties, and the potential for emissions reduction. Employing a mass-based fuel blend composition model, the study determines the molar composition of the blended fuels while examining their performance across 10%, 15%, and 20% co-firing ratios. Key results indicate that co-firing biomass significantly lowers CO₂ emissions compared to coal. At a co-firing rate of 10%, eucalyptus sawdust emits 0. 46426 kg of CO₂ per kg of cement, in contrast to 0. 760 kg for coal by itself. This results in a CO₂ emissions reduction of 0. 304875%, which escalates to 1. 009417% at a co-firing rate of 20% for olea and pine sawdust. The flame temperature of 1770 K (1497°C) for 10% eucalyptus co-firing satisfies kiln operational specifications, confirming its technical feasibility. From an economic standpoint, substituting 10% of coal with eucalyptus yields approximately 75,297,000 birr in annual savings, with savings rising to 150,600,000 birr at a 20% co-firing rate. The cost of eucalyptus (0. 38205 birr/kg of cement) is considerably lower than that of coal (1. 637 birr/kg of cement), leading to a 7. 67% decrease in fuel expenses at a 10% co-firing rate. Moreover, 10% eucalyptus co-firing decreases coal consumption by 5. 6%, which further boosts economic and environmental advantages. Environmental benefits encompass significant reductions in SO₂ and NOₓ emissions. For instance, 20% eucalyptus co-firing decreases SO₂ emissions by 19. 15264 units and NOₓ emissions by 12. 49865 units. Pine sawdust exhibits the greatest reduction in SO₂ (19. 77646 units at 20% co-firing), while olea sawdust achieves the most substantial reduction in NOₓ (13. 02422 units at 20% cofiring). A lower ash content (18. 67% at 20% co-firing) and minimal sulfur content in biomass further enhance combustion efficiency and lessen environmental impacts. The study also underscores the practical use of pine sawdust as an alternative fuel, which lowers the air-to-fuel ratio, excess air ratio, oxygen demands, flame temperature, as well as SO₂ and NOₓ emissions. Locally sourced pine sawdust offers benefits such as decreased transportation expenses, reduced moisture content, and less biological degradation. It can be processed and burned in a manner similar to coal or pet coke, needing only slight modifications. The thesis concludes that co-firing biomass fuels, especially pine sawdust, represents a feasible and sustainable approach to cement production, delivering considerable environmental and economic advantages. It suggests additional actions like waste heat recovery, alternative raw material usage, carbon capture, and the integration of renewable energy to further enhance system efficiency. Co-firing coal with biomass provides significant benefits for cement kiln pyro processing but necessitates precise optimization and execution suited to specific operational circumstances