Analysis of NOx Formation in a Hydrogen-Fueled Gas Turbine Engine

Abstract

A commercially available natural gas fueled gas turbine engine was operated on hydrogen. Three sets of fuel injectors were developed to facilitate stable operation while generating differing levels of fuel∕air premixing. One set was designed to produce near uniform mixing while the others have differing degrees of nonuniformity. The emission performance of the engine over its full range of loads is characterized for each of the injector sets. In addition, the performance is also assessed for the set with near uniform mixing as operated on natural gas. The results show that improved mixing and lower equivalence ratio decrease NO emission levels as expected. However, even with nearly perfect premixing, it is found that the engine, when operated on hydrogen, produces a higher amount of NO than when operated with natural gas. Much of this attributed to the higher equivalence ratios that the engine operates on when firing hydrogen. However, even the lowest equivalence ratios run at low power conditions, higher NO was observed. Analysis of the potential NO formation effects of residence time, kinetic pathways of NO production via NNH, and the kinetics of the dilute combustion strategy used are evaluated. While no one mechanism appears to explain the reasons for the higher NO, it is concluded that each may be contributing to the higher NO emissions observed with hydrogen. In the present configuration with the commercial control system operating normally, it is evident that system level effects are also contributing to the observed NO emission differences between hydrogen and natural gas.

Hydrogen Enriched Combustion Testing of Siemens Industrial SGT-400 at Atmospheric Conditions

“…This behavior is similar to the experimental result reported in Ref. [11] and the kinetic modeling result presented in Ref. [12], It is also demonstrated in the Fig.…”

Fuel Flexible Turbine System (FFTS) Program

“…This configuration differs from most of the previous cases investigated previously in the literature with the exception of (Therkelsen, Werts et al 2009). These researchers investigated hydrogen fueling of the same engine to be investigated in this work, a Capstone C65 engine.…”

“…Most of these previous works have focused on non-premixed combustion systems (Conrad and Corrington 1957;Nomura, Tamaki et al 1981;Sampath and Shum 1985;Tomczak, Benelli et al 2002;Juste 2006;Cocchi, Provenzale et al 2008;Cocchi and Sigali 2010). Some work with regard to the operation of premixed systems on high hydrogen content fuels has also been carried out (Minakawa, Miyajima et al 1997;Farina, Perry et al 2009;Perry, Farina et al 2009;Therkelsen, Werts et al 2009). General Electric and Siemens researchers have also investigated premixed combustion systems for operation of gas turbines on high hydrogen content fuels (Lacy, Ziminsky et al 2008;Bradley and Fadok 2009).…”

“…However, the fact that the NOx emissions do not increase as hydrogen is added does not agree with those trends from the PSR simulations. It should also be noted here that several publications contain experimental data showing an increase in NOx as hydrogen is added to natural gas (or another baseline fuel) (Tomczak, Benelli et al 2002;Juste 2006;Cocchi, Provenzale et al 2008) or substituted for the original fuel (Nomura, Tamaki et al 1981;Sampath and Shum 1985;Therkelsen, Werts et al 2009). However, other publications show experimental data with sub 1 ppm NOx measurements after several design modifications (Minakawa, Miyajima et al 1997;Farina, Perry et al 2009).…”

Conceptual Studies of a Fuel-Flexible Low-Swirl Combustion System for the Gas Turbine in Clean Coal Power Plants

“…The interchangeability of natural gas and hydrogen has been demonstrated in a small-scale gas turbine [7]. In that study, the injector hardware had been modified only to mitigate the effects associated with the highly reactive combustion properties of hydrogen that include high turbulent flame speed and short auto-ignition times.…”