REDUCING GAS-TURBINE EMISSIONS THROUGH HYDROGEN-ENHANCED, STEAM-INJECTED COMBUSTION

The potential for reducing emissions from gas turbines by injecting st eam for NOx control and hydrogen for CO control is evaluated through l aboratory-scale combustion experiments. Results showed that hydrogen a ddition into a steam-injected diffusion combustor at hydrogen/fuel mol ar ratios of approximately 20 percent was associated with somewhat inc reased NOx production and reduced CO emissions. Both effects are attri buted 20 an increase in the local stoichiometric flame temperature. Ho wever, the decrease in CO was greater than the increase in NOx, result ing in a net emissions benefit, or a shifting of the NOx-CO curve towa rd the origin. Consequently, a greater range of NOx/CO emissions targe ts could be achieved when hydrogen was available. Additional experimen ts on premixed systems with hydrogen injection showed a significant in crease in operability. Cost estimates for producing hydrogen with a co nventional fired steam reformer suggested high capital costs unless am ple steam is already available. Hence, the technology is particularly well suited for turbines that use steam for power augmentation. Altern ate reforming technology, such as catalytic pal tial oxidation, offers the potential for reduced capital costs.