Effect of Hydrogen Content on the Gas Turbine Combustion Performance of Synthetic Natural Gas

This paper investigates the effect of hydrogen content on the gas turbine combustion performance of synthetic natural gases to determine whether they are adaptable to industrial gas turbines. Synthetic natural gases which are composed of methane, propane and varying amounts of hydrogen (0%, 1%, 3% and 5%), are tested in ambient pressure and high temperature conditions at the combustion test facility of a 60kW_th industrial gas turbine. Combustion instabilities, flame structures, temperatures at nozzle, dump plane and turbine inlet, and emissions of NOx and CO are investigated for the power outputs from 35 to 60kW_th. With increasing hydrogen content, combustion instabilities are slightly alleviated and the frequency of pressure fluctuation and heat release oscillation is increased. NOx and CO emissions are almost similar in trends and amounts for all tested fuels, and the undesirable phenomena from addition of hydrogen such as flashback, auto-ignition and overheating of fuel nozzle were not observed. Synthetic natural gas with less than 1% hydrogen showed no difference in gas turbine combustion characteristics, while synthetic natural gases containing hydrogen of over 3% showed a slight difference in combustion instability such as amplitude and frequency of pressure fluctuations and heat release oscillations. From these results, we conclude that the synthetic natural gas containing less than 1% hydrogen is adaptable without retrofitting any part of the combustor, and Korea coal-SNG Quality Standard Bureau is planning to establish the SNG quality standards, guaranteeing hydrogen content of up to 1%.