Having a background of utilising ammonia as an alternative fuel for power generation, exploring the feasibility of co-firing ammonia with methane is proposed to use ammonia to substitute conventional natural gas. Howe...Having a background of utilising ammonia as an alternative fuel for power generation, exploring the feasibility of co-firing ammonia with methane is proposed to use ammonia to substitute conventional natural gas. However, improvement of the combustion of such fuels can be achieved using conditions that enable an increase of oxygenation, thus fomenting the combustion process of a slower reactive molecule as ammonia. Therefore, the present study looks at oxygen enriched combustion technologies, a proposed concept to improve the performance of ammonia/methane combustion. To investigate the characteristics of ammonia/methane combustion under oxygen enriched conditions, adiabatic burning velocity and burner stabilized laminar flame emissions were studied. Simulation results show that the oxygen enriched method can help to significantly enhance the propagation of ammonia/methane combustion without changing the emission level, which would be quite promising for the design of systems using this fuel for practical applications. Furthermore, to produce low computational-cost flame chemistry for detailed numerical analyses for future combustion studies, three reduced combustion mechanisms of the well-known Konnov's mechanism were compared in ammonia/methane flame simulations under practical gas turbine combustor conditions. Results show that the reduced reaction mechanisms can provide good results for further analyses of oxygen enriched combustion of ammonia/methane. The results obtained in this study also allow gas turbine designers and modellers to choose the most suitable mechanism for further combustion studies and development.展开更多
Exhaust gas recirculation(EGR)is one of the main techniques to enable the use of oxyfuel combustion for carbon capture and storage(CCS).However,the use of recirculated streams with elevated carbon dioxide poses differ...Exhaust gas recirculation(EGR)is one of the main techniques to enable the use of oxyfuel combustion for carbon capture and storage(CCS).However,the use of recirculated streams with elevated carbon dioxide poses different challenges.Thus,more research is required about the cumulative effects on the desirable outcomes of the combustion processes such as thermal efficiency,reduced emissions and system operability,when fuels with high CO_(2) concentration for CCS exhaust gas recirculation or biogas are used.Therefore,this study evaluates the use of various CO_(2) enriched methane blends and their response towards the formation of a great variety of structures that appear in swirling flows,which are the main mechanism for combustion control in current gas turbines systems.The study uses 100 kW acoustically excited swirl-stabilised burner to investigate the flow field response to the resultant effects of the variation in the swirl strength,excitation under isothermal condition and the corresponding effects during combustion with different fuels at various CO_(2) concentrations.Results show changes in size and location of flow structures as a result of the changes in the mean and turbulent velocities of the flow field,consequence of the imposition of different swirl and forcing conditions.Improved thermal efficiency is also observed in the system when using high swirl and forcing while the blend of CO_(2) with methane balanced the heat release fluctuation with a corresponding reduction in the acoustic amplitudes of the combustion response,suggesting that certain CO_(2) concentrations in the fuel can provide more stable flames.Concentrations between 10%to 15%CO_(2) volume show great promise for stability improvement,with the potential of using these findings in larger units that employ CCS technologies.展开更多
Expanding the fuel flexibility of continuous combustion systems to include multiphase fuel combustion offers additional support to combat the problem of energy security and,potentially,environmental pollution.In this ...Expanding the fuel flexibility of continuous combustion systems to include multiphase fuel combustion offers additional support to combat the problem of energy security and,potentially,environmental pollution.In this study,apart from establishing stability limits and measuring post-combustion emissions,flames generated from simultaneous combustion of biodiesel and syngas were examined using C_(2)*and CH*chemiluminescence imaging to capture changes in the reaction zone.The proportion of syngas in the fuel mix was varied from 0 to 30%content(by energy contribution)while maintaining a total power output of 15 kW.The overall equivalence ratio was held at 0.7 in cases other than for determining the flammability range.The results indicate a reduction of stability limits as gas proportion in fuel blend increases.Also,chemiluminescence imaging of the two targeted species suggest a general reduction in reaction rate as well as reaction zone area and length with increase in gas ratio in the dual phase tests.Furthermore,emissions performance in the context of NOxand CO was investigated as liquid-to-gas ratios were altered.Conclusively,the study demonstrates the feasibility,limitations and potential benefits of multiphase renewable fuel combustion in a swirl-stabilised burner.展开更多
基金financially supported by the Welsh European Funding Office(WEFO)through its program "Flexible Integrated Energy Systems(FLEXIS)"(Grant No.80835)
文摘Having a background of utilising ammonia as an alternative fuel for power generation, exploring the feasibility of co-firing ammonia with methane is proposed to use ammonia to substitute conventional natural gas. However, improvement of the combustion of such fuels can be achieved using conditions that enable an increase of oxygenation, thus fomenting the combustion process of a slower reactive molecule as ammonia. Therefore, the present study looks at oxygen enriched combustion technologies, a proposed concept to improve the performance of ammonia/methane combustion. To investigate the characteristics of ammonia/methane combustion under oxygen enriched conditions, adiabatic burning velocity and burner stabilized laminar flame emissions were studied. Simulation results show that the oxygen enriched method can help to significantly enhance the propagation of ammonia/methane combustion without changing the emission level, which would be quite promising for the design of systems using this fuel for practical applications. Furthermore, to produce low computational-cost flame chemistry for detailed numerical analyses for future combustion studies, three reduced combustion mechanisms of the well-known Konnov's mechanism were compared in ammonia/methane flame simulations under practical gas turbine combustor conditions. Results show that the reduced reaction mechanisms can provide good results for further analyses of oxygen enriched combustion of ammonia/methane. The results obtained in this study also allow gas turbine designers and modellers to choose the most suitable mechanism for further combustion studies and development.
基金the support from the Welsh European Funding Office(WEFO)through its program“Flexible Integrated Energy Systems(FLEXIS)”,project No.80835.
文摘Exhaust gas recirculation(EGR)is one of the main techniques to enable the use of oxyfuel combustion for carbon capture and storage(CCS).However,the use of recirculated streams with elevated carbon dioxide poses different challenges.Thus,more research is required about the cumulative effects on the desirable outcomes of the combustion processes such as thermal efficiency,reduced emissions and system operability,when fuels with high CO_(2) concentration for CCS exhaust gas recirculation or biogas are used.Therefore,this study evaluates the use of various CO_(2) enriched methane blends and their response towards the formation of a great variety of structures that appear in swirling flows,which are the main mechanism for combustion control in current gas turbines systems.The study uses 100 kW acoustically excited swirl-stabilised burner to investigate the flow field response to the resultant effects of the variation in the swirl strength,excitation under isothermal condition and the corresponding effects during combustion with different fuels at various CO_(2) concentrations.Results show changes in size and location of flow structures as a result of the changes in the mean and turbulent velocities of the flow field,consequence of the imposition of different swirl and forcing conditions.Improved thermal efficiency is also observed in the system when using high swirl and forcing while the blend of CO_(2) with methane balanced the heat release fluctuation with a corresponding reduction in the acoustic amplitudes of the combustion response,suggesting that certain CO_(2) concentrations in the fuel can provide more stable flames.Concentrations between 10%to 15%CO_(2) volume show great promise for stability improvement,with the potential of using these findings in larger units that employ CCS technologies.
文摘Expanding the fuel flexibility of continuous combustion systems to include multiphase fuel combustion offers additional support to combat the problem of energy security and,potentially,environmental pollution.In this study,apart from establishing stability limits and measuring post-combustion emissions,flames generated from simultaneous combustion of biodiesel and syngas were examined using C_(2)*and CH*chemiluminescence imaging to capture changes in the reaction zone.The proportion of syngas in the fuel mix was varied from 0 to 30%content(by energy contribution)while maintaining a total power output of 15 kW.The overall equivalence ratio was held at 0.7 in cases other than for determining the flammability range.The results indicate a reduction of stability limits as gas proportion in fuel blend increases.Also,chemiluminescence imaging of the two targeted species suggest a general reduction in reaction rate as well as reaction zone area and length with increase in gas ratio in the dual phase tests.Furthermore,emissions performance in the context of NOxand CO was investigated as liquid-to-gas ratios were altered.Conclusively,the study demonstrates the feasibility,limitations and potential benefits of multiphase renewable fuel combustion in a swirl-stabilised burner.
