Multiphase fuel combustion in a swirl diffusion burner: an operational and performance study
Year: 2020
Type: dissertation
Abstract: Meeting the ever-growing energy demands of the world while not sacrificing energy \nsecurity/environmental sustainability by relying on a single fuel source means that \ncombustion systems must demonstrate fuel flexibility. Currently, the gas turbine \nburns a wide range of fuels and fuel combinations. However, there seems to be a limit \nto an exploration of its fuel flexibility. Whereas there are numerous investigations \ninto multiphase fuel combustion in other internal combustion engines like the diesel \nengine, there is a dearth of such studies for the gas turbine. Consequently, this thesis \ninvestigates the simultaneous combustion of practical liquid and gaseous fuels in a 20 \nkW swirl-stabilised gas turbine relevant combustor. \nThe investigation involved developing a dual-phase fuel injection system capable of \nhandling diesel/methane, diesel/syngas, biodiesel/methane, biodiesel/syngas and \nblends of methanol/glycerol co-combusted with methane. The effect of partly \nreplacing the liquid fuel with a gaseous type fuel on combustion characteristics like \nflammability limits, flame stability, flame structure and exhaust emissions were \nstudied for the diesel and biodiesel blends. The gas substitution ratio was based on \nheat energy contribution in such a manner that a certain percentage of a desired heat \noutput is contributed by the gaseous fuel and the balance by the liquid fuel. The nature \nof non-reacting flows in the system, including air flow and liquid fuel spray was also \ninvestigated using CFD while experimental measurements were supported using \nnumerical chemical kinetics modelling. \nFlame extinction tests proved that as gas substitution ratio increases, flammability \nlimits decrease owing to changing non-reacting and reacting flow dynamics. \nIntermediate combustion species chemiluminescence imaging was key to the \ninvestigations and was used in evaluating reaction zone characteristics and flame \nstability. These parameters as well as exhaust emissions were assessed as test \nconditions were varied. It was important, for the methanol/glycerol blends, to \nestablish the feasibility of its combustion without retrofitting the burner used for the \nother blends in order to prove its practicality. Thereafter, the influence of methane \naddition on flame structure and stability was investigated.
Author: Ogbonnaya Agwu
Language: English
Subfield: Computational Mechanics
Field: Engineering
Domain: Physical Sciences
Open Access status: green
OpenAlex ID: W3155081860