Improvement of Premixed Gas Turbine Combustion System Fuel Flexibility With Increased Hydrogen Consumption in a Renewable Market Place

Gas turbine flexibility is key in markets with significant renewable energy resources. Operational load flexibility and fuel flexibility ensure the gas turbine remains competitive in supporting power generation in renewable markets. For applications where heat is required in support of a process industry the gas turbine offers an additional advantage. Alternate fuels such as hydrogen are generated as byproducts from chemical processing plants. Hydrogen also has the ability to be a ‘battery fuel’ as excess energy produced by wind and solar can be used to produce hydrogen through electrolysis. This work focuses on the retrofit and commercial introduction of significant quantities of hydrogen fuel into the gas supply of an existing commercial E-class gas turbine in Europe. The commercially operating plant provides combined heat (in the form of process steam) and power. The gas turbine operates with a lean premixed combustor without the need for diluent injection, and is able to operate flexibly with hydrogen mixed into the base natural gas fuel supply. The fuel mixing allows consumption of a chemical plant process gas resulting in positive economic and environmental benefit. This involves several considerations including combustor control/operation, safe flashback margin, emissions, stability and hardware durability. Enhancements to the control system through an automated combustor tuning package which is able to compensate real time for fluctuations in fuel gas constituents was implemented. Significant testing of the fuel flexible concept in a full scale high pressure combustor test facility was performed to ensure the desired increase in hydrogen consumption could be achieved. The experience, in addition to adaptations for field testing, was used to test and validate a new long term operational limit of 25% hydrogen content in the fuel. The success of the test campaign allows reduction in natural gas fuel consumption and cost, reduction in flaring of product waste gas, with a reduced power plant CO2 footprint. The development program and engine field testing substantiation are described in detail herein.