A Comparative Study of Methanol and Methane Combustion in a Gas Turbine Combustor

To investigate the combustion and emission characteristics of a 20 MW gas turbine combustor following fuel replacement, this study employs numerical simulations to systematically compare the combustion performance of methanol and methane. The focus is on the influence mechanism of the fuel distribution ratio on NOx emissions. As a preliminary numerical investigation, this study aims to provide theoretical guidance for subsequent experimental research, with the results serving to define measurement points in experimental design. It is found that the value of NOx emission from methanol combustion is 40–78% of that of methane under all operating conditions, which is significantly lower than that of methane. And its low NOx emission range is significantly wider than that of methane (methanol: a pilot fuel ratio range of 1–12%; methane: a pilot fuel ratio range from 2 to 4%). Methanol reaches the lowest NOx emission (51.53 ppm) near the pilot fuel ratio of 2%, while methane reaches the lowest NOx emission (93 ppm) near the pilot fuel ratio of 4%. This difference is due to the oxygen content and low calorific value of methanol, which makes it easier to reduce the flame in the main combustion zone to the temperature that inhibits the generation of thermal NOx, so there is no need to allocate more fuel to the pilot to reduce the cooling pressure in the main combustion zone. In addition, the combustor efficiency of methanol is higher and less volatile (99.52–99.89%), which is slightly higher than that of methane (99.33–99.61%). The results show that methanol is suitable as a gas turbine fuel. Its performance in the gas turbine combustor is slightly better than that of methane, and NOx emission is significantly better than that of methane. The better performance of methanol provides greater flexibility for the design of gas turbine combustors and has great feasibility in engineering.