Examensarbeten för masterexamen // Master Theses
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Browsar Examensarbeten för masterexamen // Master Theses efter Program "Innovative sustainable energy engineering, MSc"
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- PostModelling of the gas flow in fluidized beds(2017) Gioia, Federica; Chalmers tekniska högskola / Institutionen för energi och miljö; Chalmers University of Technology / Department of Energy and EnvironmentFluidized bed technology plays an important role in the transition of the current energy system to full sustainability, both as main first choice for thermochemical biomass conversion (which is considered CO2 neutral) and as basis for chemical looping combustion (CLC), which is considered to be the second generation of carbon capture applications, since it allows CO2 capture with no inherent energy penalty. The aim of the work is to formulate and implement a proper description of the gas flow inside a fluidized bed, covering a variety of scales and applications. This will be done by the development of an own code, since this provides enhanced flexibility with respect to already developed modelling tools available on the market. The influence of four parameters (inlet velocity, exchange coefficient between phases in the dense bed, dense bed height and lateral diffusion coefficient) in regular fluidized bed combustion is studied, in particular considering a lateral injection of volatiles resembling biomass combustion. The results have been mostly in line with the expectations, showing a high dependence of the system from the gas mixing more than kinetics, and, on the other hand, that the exchange between phases in the dense bed and the dense bed height are not influential parameters.
- PostPET recycling via gasification - Influence of operating conditions on product distribution(2019) Li, Shouzhuang; Chalmers tekniska högskola / Institutionen för rymd-, geo- och miljövetenskap; Chalmers University of Technology / Department of Space, Earth and EnvironmentEU plans to achieve 100% plastic packaging reuse in 2040, and some new technologies have been proposed. Gasification is one of the promising technologies to convert plastic into syngas for heat production or chemicals synthesis process. This project focused on the thermoplastic that is widely used in textile fibre, film, and bottles – PET. Although PET bottle recycling is reliable, gasification could be an option for recycling contaminated and other PET products. Proximate analysis was carried out by Thermogravimetric Analysis (TGA) to comprehend its thermal decomposition, obtaining volatiles and char. Gasification experiments were conducted in a lab scale bubbling fluidized bed with batch and continuous feeding operation. The batch experiments compared different plastics and gasifying agents. It was found that CO2 dominated the gas production at all agents, and steam can motivate H2 production. However, air cannot reduce tar formation significantly as literature stated. After that, continuous feeding experiments for steam gasification were designedtoinvestigatehowtemperature, residence time and steam/fuel ratio affect the distribution of gas and tar products in PET steam gasification. The results show the temperature is an essential condition parameter for gas and tar yield. The increasing temperature improved the gas yield and tar cracking. The application of syngas produced by PET steam gasification was evaluated based on the experimental results. The highest energy conversion efficiency from PET and reacted steam to cold syngas was 29% at 800 ◦C, meaning that most of heat energy was lost. Fuel synthesis was analyzed by H2/CO ratio, and syngas products are more likely to be produced fuels by FT synthesis. Besides, the tar limitation of both power generation and fuel synthesis are very strict, but the tar concentrations in all cases are extremely high. Mixing with other plastics or biomass and better bed material could be solutions to promote syngas quality. Moreover, the mass balance analysis suggests 35% - 40% carbon was not detected, so sampling and measurement methods should be improved in the future research.