Effect of fuel flexibility on combustion performance of a micro-mixing gas turbine combustor at different fuel temperatures

An H-class gas turbine combustor prototype that employs the micro-mixing combustion technology is first proposed in the current research. It consists of 60 interior jet-in-crossflow micro-mixing nozzles with a distributed arrangement. To analyze the fuel flexibility, a blend of 50% H₂ and 50% CO by volume and the pure H₂ are considered for the micro-mixing combustor prototype in terms of the design and alternative fuels, respectively. Secondly, this research discusses the fuel temperature effects on the rated and off-design combustion performance for both fuels, because the fuel temperature is an important factor for the power generation efficiency in the gas turbine combined cycles. The results indicate that at the rated fuel temperature of 473 K and off-design ones of 423, 523 and 573 K, the micro-mixing combustor prototype has a great fuel flexibility, in which NO emission is lower than 15 μL/L at 15% O₂, outlet temperature distribution factor is lower than 15%, combustion efficiency is higher than 99%, and total pressure recovery factor is higher than 95% for both fuels. Through the trends of combustion performance in different radial planes, it can be found that the high temperature zone of flue gas produced by H₂ is longer than H₂/CO (50%/50%), and far away the nozzles. Thus, the H₂-fired micro-mixing combustor prototype needs a longer axial liner length than H₂/CO (50%/50%), in order to realize the enhanced temperature distribution uniformity and combustion efficiency. Eventually, an optimal relationship between the axial liner length and fuel hole diameter is proposed for both fuels based on the trade-offs around the whole combustion performance from the perspective of engineering applications.