Fluidization and mixing characteristics of biomass particles in a bubbling fluidized bed

Download
index.pdf
2008
İnanlı, Sinan
Show full item record
235
views
96
downloads
Fluidized bed is a suitable technology for combustion and gasification of biomass materials. Hydrodynamics occurring in the bed is crucial for the design and operation of the combustion or gasification unit. In the present study, hydrodynamic behavior of binary mixtures of biomass-silica sand in a bubbling fluidized bed was experimentally investigated. Five different biomass materials and silica sand with three different particle sizes were employed to form binary mixtures. Biomass materials were rice husk, sawdust, wheat straw, hazelnut shell and olive cake which are all potential energy sources for Turkey. Effects of mass percentage of biomass and particle size of silica sand on minimum fluidization velocity of the mixtures were determined. Comparisons between results of the present study and predictions of available correlations proposed for minimum fluidization velocity of binary mixtures were carried out. Mixing and segregation characteristics of biomass-silica sand binary mixtures were investigated for mixtures having different mass fraction of biomass and different silica sand particle sizes. Fluidization and bubbling behaviors of mentioned mixtures were observed in a 2-D fluidized bed and images taken during steady-state operation of bed were presented as visual tools to guide fluidization characteristics of the bed. Mass percentage increase of rice husk, wheat straw and sawdust resulted in increase in minimum fluidization velocity of the mixture whereas change in mass fraction of olive cake and hazelnut shell had no effect on minimum fluidization velocity. Minimum fluidization velocity increased with increase of silica sand particle size for all biomass-silica sand mixtures having same mass percentage of biomass. Vertical mixing pattern in the bed at steady state conditions were found almost same for all biomass-silica sand mixtures. Biomass acted as flotsam and accumulated mostly at the top of the bed and silica sand acted as jetsam and accumulated mostly at the bottom of the bed. 2-D bed experiments showed that mixing biomass materials with silica sand provides desired bubbling behavior in the bed.
Mechanical engineering.
http://etd.lib.metu.edu.tr/upload/3/12610014/index.pdf
https://hdl.handle.net/11511/17814
Graduate School of Natural and Applied Sciences, Thesis

Suggestions

First and second law analyses of a biomass fulled solid oxide fuel ceel-micro turbine hybrid system
Arabacı, Selin; Yüncü, Hafit; Department of Mechanical Engineering (2008)
Fuel cells are direct energy conversion devices to generate electricity. They have the lowest emission level of all forms of electricity generation. Fuel cells require no combustion of the fuel. The thermal energy gained from fuel cells may be utilized in micro turbines (gas turbines). In this work, first and second law analyses are performed on a hybrid system consisting of a solid oxide fuel cell (SOFC) combined with a micro turbine to be able to find an optimum point of pressure and corresponding mass ra...
An electronic control unit design for a miniature jet engine
Polat, Cuma; Dölen, Melik; Department of Mechanical Engineering (2010)
Gas turbines are widely used as power sources in many industrial and transportation applications. This kind of engine is the most preferred prime movers in aircrafts, power plants and some marine vehicles. They have different configurations according to their mechanical constructions such as turbo-prop, turbo-shaft, turbojet, etc. These engines have different efficiencies and specifications and some advantages and disadvantages compared to Otto-Cycle engines. In this thesis, a small turbojet engine is inves...
Conduction based compact thermal modeling for thermal analysis of electronic components
Ocak, Mustafa; Sert, Cüneyt; Department of Mechanical Engineering (2010)
Conduction based compact thermal modeling of DC/DC converters, which are electronic components commonly used in military applications, are investigated. Three carefully designed numerical case studies are carried out at component, board and system levels using ICEPAK software. Experiments are conducted to gather temperature data that can be used to study compact thermal models (CTMs) with different levels of simplification. In the first (component level) problem a series of conduction based CTMs are generat...
Performance anallysis of an intermediate temperature solid oxide fuel cell
Timurkutluk, Bora; Tarı, İlker; Department of Mechanical Engineering (2007)
An intermediate temperature solid oxide fuel cell (SOFC) is developed and its performance is investigated experimentally and theoretically. In the experimental program, a gadolinium doped ceria based membrane electrode group is developed with the tape casting and screen printing methodology and characterized. An experimental setup is devised for the performance measurement of SOFCs and the performance of produced cells is investigated over a range of parameters including the electrolyte thickness, the sinte...
Comparison of engine performance and emissions for conventional petroleum diesel fuel and diesel-ethanol blends
Erkal, Gül; Yozgatlıgil, Ahmet; Department of Mechanical Engineering (2010)
Ethanol is an environmental friendly alternative diesel fuel that has received significant attention both as a possible renewable alternative fuel and as an additive to existing petroleum-based fuels. Beyond simply representing an additional fuel supply, ethanol exhibits several advantages when compared to existing petroleum fuel. The objective of this work is to investigate experimentally the effects of using different blends of specified percentages of ethanol on the engine performance and emissions and t...
Citation Formats
S. İnanlı, “Fluidization and mixing characteristics of biomass particles in a bubbling fluidized bed,” M.S. - Master of Science, Middle East Technical University, 2008.
METU IIS - Integrated Information Service open@metu.edu.tr