Browsing by Author "John, Geoffrey"

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Energy Recovery from Municipal Solid Waste
(Regional Collaboration Conference, july 2014) Omari, Arthur; Njau, Karoli; Mtui, Peter; John, Geoffrey
Energy flow analysis and thermal degradation of municipal solid waste was carried out using differential scanning calorimetry and thermo-gravimetric analyzer at heating rates of 10 K/min, 20 K/min, 30 K/min and 40 K/min in a nitrogen atmosphere and temperatures between 308 K and 1273 K. The activation energy (E a ) is the energy barrier which must be overcome for reaction to occur. Thermal degradation behavior experiments show that the municipal solid waste is less reactive than biomass or coal with activation energy ranging between 205.9 to 260.6kJ/mol. These value are higher than typical wood activation energy which ranges between 50 and 180kJ/mol and coal with a range between 30 and 90 kJ/mol. These value of activation energy can be improved by pretreatment of municipal solid waste.
Energy Recovery routes from Municipal Solid Waste : A case study of Arusha-Tanzania
(Journal of Energy Technologies and Policy, 2014) Omari, Arthur; Said, Mahir; Njau, Karoli; John, Geoffrey; Mtui, Peter
A study of energy recovery from municipal solid waste was undertaken. The energy content of the solid waste is 12MJ/kg. The elemental composition shows that the municipal solid waste contains 50% and 5% of carbon and hydrogen respectively. The energy flow (exothermic and endothermic) and thermal degradation analysis were carried out using differential scanning calorimetry and thermo-gravimetric analyser respectively. Experiments were performed at heating rate of 10 K/min, 20 K/min, 30 K/min and 40 K/min in the nitrogen atmosphere at temperature between room temperature and 1273 K. The thermal degradation kinetic parameters values of activation energy (E ) ranged from 205.9 to 260.6kJ/mol. It has been observed that municipal solid waste is less reactive to combustion as compared to coal and biomass, but its reactivity can be improved through pre-treating process so as to reduce noncombustible materials such as oxygen and ash content. Also pyrolysis and gasification can be used to convert MSW to liquid or gaseous fuel. a
Mass And Energy Balance For Fixed Bed Incinerators
(Journal of Multidisciplinary Engineering Science and Technology (JMEST), 2015-09) Omari, Arthur; Njau, Karoli; John, Geoffrey; Kihedu, Joseph; Mtui, Peter
An estimation of mass and energy balance of an incinerator is an important consideration toward the design and operation of the incineration process. This paper is aimed to study the mass and energy balance of a locally made fixed bed incinerator. The results shows that the total mass rate of 49 kg/h of municipal solid waste and 9.75 kg/h of diesel consumed 458.9 kg/h of air. The incineration process generates 379,287.14 kJ/h with ash and flue gases emissions at a total mass rate of 528.51 kg/h.
Potential of municipal solid waste, as renewable energy source : a case study of Arusha, Tanzania.
(International Journal of Renewable Energy Technology Research, 2014-06) Omari, Arthur; Kichonge, Baraka; John, Geoffrey; Njau, Karoli; Mtui, Peter
This paper presents the study of municipal solid waste (MSW) as a potential source of renewable energy in Arusha city. The city of Arusha annual average MSW generated was estimated at 43,772 tonnes. Characterization revealed the main components of MSW to compose of biomass materials such as food, paper and wood waste. Based on the characteristics of the MSW, evaluation was conducted to determine energy potential that would be recovered. Results from proximate analysis of MSW samples showed average calorific value of about 12MJ/kg which indicate annual energy potential of 128.9 GWh. Results indicate there is a substantial energy potential to recover from MSW the largest share being renewable energy. The composition of waste from developing and developed countries was further compared with that of Arusha city. Results indicated that in developing countries characteristics of MSW is mainly composed of food waste as was the case of Arusha city.