Visualisation and performance evaluation of biodiesel/methane co-combustion in a swirl-stabilised gas turbine combustor. (1st October 2020)

• Record Type: Journal Article
• Authors: Agwu, Ogbonnaya; Runyon, Jon; Goktepe, Burak; Chong, Cheng Tung; Ng, Jo-Han; Giles, Anthony; Valera-Medina, Agustin
• Is Part Of: Fuel. Volume 277(2020)
• Publication Date: 2020-10-01
• Subjects: Alternative fuel -- Combustion -- Emissions -- Multiphase burn -- Stability; Fuel -- Periodicals; Coal -- Periodicals; Coal; Fuel; Periodicals; 662.6
• DOI: 10.1016/j.fuel.2020.118172
• Languages: English
• ISSNs: 0016-2361

Abstract

Abstract: While dual fuel firing of power generation combustion systems can improve the fuel flexibility of such systems, several studies on compression ignition engines have also shown a positive impact on NOX and PM emissions. Previous multiphase fuel combustion studies for combustion turbines are limited, thus the present study addresses that gap by fuelling a model swirl stabilised gas turbine combustor with a blend of waste cooking oil-derived biodiesel and methane. Methane was increasingly injected into swirling combustion air flow while simultaneously reducing the biodiesel spray flowrate across a pressure atomiser, thus maintaining an overall equivalence ratio of 0.7 while delivering a thermal power output of 15 kW in all cases, except for flame stability range trials. Direct flame imaging, CH* and C2 * chemiluminescence imaging, post combustion emissions as well as stability performance of the flames were evaluated. NOX emissions were found to decrease by 29% and unburnt hydrocarbons increased by 10% as the fraction of methane in fuel mix increased to 30%. Further, flame images suggest increased wrinkling and perturbing of the flame front as gas fraction of the biodiesel/methane flame increases. However, the temporal variation of integral intensity of CH* and C2 * species chemiluminescence point to at least an 8% improvement in flame stability when 30% of flame heat output is supplied by methane compared to neat biodiesel burn. Also, it was found that flame stability limits reduce as methane partly replaces biodiesel in the flame.