Design and Computational Fluid Dynamic Modeling of a Municipal Solid Waste Incinerator for Kampala City, Uganda

Abstract

In Uganda, the government targeted to produce at least 15 MW from Municipal Solid Wastes (MSW) by end of 2012, which was not achieved. It is against this background that this project’s twofold objective is to explore the energy potential of MSW in Kampala and design an environmentally friendly waste-to-energy incinerator for electricity generation. The obtained waste characterization results show that the average composition of MSW in Kampala city varied as follows: food and yard waste, 90.64 %; papers, 1.67 %; plastics, 1.77 %; polyethylene, 2.99 %; textiles, 0.59 %; glass, 1.16 %; metals, 0.15 % and others 1.03 %. The proximate analysis of the food and yard waste component indicated volatile matter of 73.29 %; fixed carbon of 4.36 %; moisture of 8.49 % and ash of 13.86 %. Furthermore, the ultimate analysis of the MSW on dry basis yielded Carbon 22.58 %; Hydrogen 3.22 %; Oxygen 14.06 %; Nitrogen 1.56 %; Sulphur 0.24 % and Ash 58.33 %. The Lower Heating Value (LHV) and Higher Heating value (HHV) of the MSW were 9.49 MJ/kg and 10.19 MJ/kg on dry basis respectively. The HHV and LHV of the food and yard waste determined from the bomb calorimeter was 15.11 MJ/kg and 14.68 MJ/kg, respectively. An incinerator was designed to suit the characteristics of the MSW and optimized using ANSYS Computational Fluid Dynamics (FLUENT Version 14, 2011). The total time needed to incinerate the waste was 31 minutes in comparison to 25 minutes for typical incinerators. The optimal capacity of the incinerator is also 460 kg/hr as opposed to the design capacity of 567 kg/hr.