OPTIMIZATION OF HYBRID CYCLONE IN REDUCTION OF PARTICULATE FLY ASH IN SUGAR INDUSTRIES IN KENYA

Abstract

The sugar industry in Kenya faces growing environmental and regulatory pressure due to fly ash emissions from bagasse-fired boilers. Traditional single-stage cyclone separators currently employed in these facilities offer limited particulate collection efficiency—ranging between 50% and 60%—and often fail to capture fine ash particles, resulting in persistent air pollution and adverse health impacts on surrounding communities and industrial workers. This research investigates the design and performance of a hybrid cyclone separator, aiming to enhance particulate capture rates and reduce environmental degradation in Kenya’s sugar belt regions. The study employed a factorial design approach, combining Computational Fluid Dynamics (CFD) simulations and experimental modeling to assess key design parameters, including inlet diameter (150 mm, 200 mm, 250 mm) and cyclone orientation (series vs. parallel). Temperature, pressure, velocity, and density profiles were analyzed across configurations to evaluate their influence on particle separation and gas dynamics. Results revealed a pronounced improvement in efficiency when using the hybrid cyclone in a series configuration, achieving rates between 81.26% and 81.95%—a substantial increase compared to conventional cyclones, which recorded a maximum of 63.69%. Notably, the hybrid design maintained stable gas velocities and operated with slightly lower fluid densities, reinforcing its capability to trap finer particles effectively. Among tested inlet diameters, the 200 mm configuration demonstrated optimal baseline efficiency and fluid dynamic stability. Orientation analysis showed that series connection outperformed parallel setups, with the latter achieving only 30.6% efficiency due to thermal instability and less synchronized vortex formation. The series arrangement enhanced flow regulation, leading to improved pressure gradients and particle capture. A regression-based mathematical model was derived to estimate efficiency using pressure, density, and relative pressure variables, yielding consistent predictive accuracy across all configurations. The model equation: Efficiency (%)} = -3303 + 0.05075P - 1441\rho - 0.05564P_r offers engineers a useful tool for real-time estimation and design optimization. The research concludes that hybrid cyclones configured in series offer a viable and energy-efficient alternative for particulate control in Kenyan sugar mills. Their implementation not only aligns with environmental standards but also enhances occupational safety, reduces equipment corrosion, and supports the industry's move toward sustainable practices. This thesis contributes a scalable and technically grounded solution to air quality challenges in agro-industrial settings, with implications for broader applications in biomass combustion and particulate-laden exhaust management.