Browsing by Author "Moshi, Robert"

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The Exergy Analysis for the Air Gasification in a Hybrid Fixed Bed Gasifier
(Current Journal of Applied Science and Technology, 2021-07-31) Moshi, Robert
Municipal solid waste (MSW) is becoming a concern as population in urban area is increasing. Several disposal methods (landfill and biochemical) have been used. However, waste to energy (WTE) particularly gasification technology is a potential technology for energy recovery. The system is used to convert biodegradable material into syngas under limited gasifying media. This study presents numerical analysis of producer gas for the two air paths in the hybrid fixed bed gasifier (HFBG). It was revealed that the optimum operating condition was achieved when the air ratio at the first air flow path (AIR1) was 0.3. Furthermore, the exergy efficiency of about 81.51% was achieved.
Experimental Study of a Lab Scale Hybrid Fixed Bed Gasifier
(Science Publishing Group, 2020-02-04) Moshi, Robert; Kivevele, Thomas; Jande, Yusufu
Thermo-chemical conversion technologies (incineration, gasification and pyrolysis) have emerged as potential technologies for municipal solid waste management (MSWM). This is happening due to the increase of the need for clean and sustainable energy as a result of fossil fuel depletion. The increase in municipal solid waste (MSW) generation as well as land scarcity for MSW disposal is another reason in raising the potential for thermal technology. Incineration has been the most common thermo-chemical technology for solid waste disposal. However, due to environmental concern, gasification technology is currently becoming more preferable since it is environmental friendly for MSW disposal as well as energy recovery. The aim of this study is to analyze the flue gases obtained from the hybrid fixed bed gasifier during gasification of MSW. The fire was initiated by wood charcoal and six kilograms of MSW was fed in the gasifier. The combustion was supported by the air supplied by electric blower. The flue gas analyzer, TESTO 327-1 was used to analyze the concentration of CO, CO2 and O2. Results show that after 150 minutes of the gasification process, O2 concentration increased by 17.2% while CO and CO2 decreased by 0.0% and 3.77% respectively. The experimental results show that, during gasification process the O2 concentration was increasing with time while CO and CO2 concentration decreased.
Simulation and performance analysis of municipal solid waste gasification in a novel hybrid fixed bed gasifier
(NM-AIST, 2022-06) Moshi, Robert
Municipal Solid Waste (MSW) is a main challenge to municipalities in developing countries due to the increase in its production caused by technology development, community culture, population growth, and urbanization. The challenge is heightened by the scarcity of dumping sites within municipalities and the environmental impact associated with improper disposal management. Thermo-chemical conversion technologies (gasification, pyrolysis and incineration) have become to be known as practicable technologies for municipal solid waste management (MSWM). In this study, the Hybrid Fixed Bed Gasifier (HFBG) model was developed using Aspen Plus in order to merge the advantages of both downdraft and cross draft gasifiers and suppress their disadvantages. Furthermore, experimental analysis of the flue gas was carried out on the HFBG. The TESTO 327- 1 flue gas analyzer was used to analyze the concentration of CO, CO2 and O2. The simulated results showed that the feedstock MC of about 59.8 wt% was lowered to 6.8 wt%. The developed hybrid fixed bed gasifier demonstrated an increase in 2 H and CO of about 29.29 % and 37.05 % mole fraction in the producer gas respectively. The syngas output was highly affected by the changes in the ER as well as change in temperature. The composition for 2 H and CO increases with increase in temperature while the composition decreases with ER between 0.1 to 0.4. However, at this ER CO2 and H O2 tend to increases but above 0.4 CO2 and H O2 decrease gradually. Experimental results show that after the elapse of 30 minutes CO and CO2 concentration was 9.69% and 5.85% respectively. Furthermore, after 150 minutes of the gasification process, the output concentration for O2 was 17.2 % while the concentration for CO and CO2 was 0.0 % and 3.77 % respectively. The experimental results revealed that, during the entire gasification process the concentration for CO and CO2 were decreasing with time while O2 concentration was increasing. This result shows diversion from the simulated results due to gasifier leakages. With high MC of MSW, the study has shown that, HFBG can handle up 60 wt% as compared to downdraft which is limited to 20 wt%.
Simulation and performance analysis of municipal solid waste gasification in a novel hybrid fixed bed gasifier using Aspen plus
(Taylor & Francis Online, 2020-08-27) Moshi, Robert; Jande, Yusufu; Kivevele, Thomas; Kim, W. S.
Thermochemical conversion technologies (incineration, gasification, and pyrolysis) have emerged as potential technologies for municipal solid waste management. Incineration is the most common thermo-chemical technology widely used in developing countries; however, the process pollutes the environment. Therefore, this study suggests a novel hybrid fixed bed gasifier for gasification of municipal solid waste (MSW). The gasifier model was developed using the Advanced System for Process Engineering Plus (ASPEN Plus) software to accommodate the four gasification stage (drying, pyrolysis, combustion, and gasification). The aim of developing a novel hybrid fixed bed gasifier is to combine the advantages of downdraft and cross-flow gasifiers in one system and minimize its disadvantages. This combination has revealed the way to a gasifier design that accommodates feedstock with high moisture content (≈ 60%) while maintaining or improving syngas output composition. The analysis of operating parameters such as temperature and equivalence ratio (ER) was also investigated. The results showed that the moisture content (MC) was reduced from 59.8 wt% to 6.8 wt%. The syngas output was highly affected by the changes in temperature as well as ER. High temperature increases H2and CO output composition. The behavior was different for the case of ER where it was observed that H2 and CO decreases while CO2 andH2Oincreases between ER = 0.1 to 0.4 and then starts decreasing gradually. In general, the developed hybrid fixed bed gasifier exhibited an increase inH2 and CO in the producer gas. At this situation, the carbon conversion efficiency of 62.35% and a gasifier conversion efficiency of 54.5% were realized. This suggests the suitability of hybrid