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

Abstract

In order to further extend the turbine fuel flex capability, a test under atmospheric conditions of a full-scale SGT-400 burner was performed to study the combustion behavior when operating on hydrogen enriched natural gas. A high speed camera was installed in the rig to investigate the flame dynamics on different operation conditions. NOx emissions were measured for all presented conditions. The combustion system was instrumented with thermocouples on all the key locations to allow flame position monitoring and to avoid flame attachment on the hardware. Further measurements included static pressure probes to monitor combustor pressure drop. The test was conducted in a systematic matrix format to include the most important combustion parameters in order to identify their individual effects on the combustion behaviors. The quantity of hydrogen in natural gas, fuel split, air preheat temperature, air reference velocity and flame temperature were the combustion related variables studied in the presented test campaign. The volumetric hydrogen quantity could be increased to 30% maintaining stable operation for all measured conditions. Higher hydrogen contents up to 80 vol-% were reached without flash back tendency. A glowing spark igniter prevented testing at even higher hydrogen contents. Hydrogen enriched gas showed higher NOx emissions and improved blowout limit. Hydrogen blending in the fuel also reduced the combustor pressure drop, lowered the prechamber temperature and raised the pilot tip temperature.

Emissions of a Wet Premixed Flame of Natural Gas and a Mixture With Hydrogen at High Pressure

“…They reported however that an increase of NO x emissions was observed and they attributed this effect to the chemical influence of hydrogen enrichment on the NO x formation processes. An increase of NO x emissions due to hydrogen enrichment of natural gas has also been reported in commercial swirlstabilized combustion systems and it was attributed to the same cause [5,11].…”

“…There is an extensive body of research on premixed flames of hydrogen-enriched fuels on both industrial [3][4][5] and generic combustion systems, mostly focusing on flame stability, emissions and flashback. Hydrogen addition evidently lowers the LBO limit of swirl-stabilized combustors irrespective of the combustion system details, even for relatively low hydrogen concentrations in the fuel.…”

Reviewing H2 Combustion: A Case Study for Non-Fuel-Cell Power Systems and Safety in Passive Autocatalytic Recombiners

“…The differences are largely attributed to H 2 having a lower mass density in comparison to other fuels. The lower volumetric LHV of H 2 leads to a lower mixture LHV when H 2 is mixed with conventional fuels . This also means that higher volumes of the mixture are required. , …”

“…This may be attributed to chemical kinetics and the enhanced diffusion coefficient which increases the strain resistance, resulting in a higher fuel concentration in the flame front . Therefore, adding H 2 to slower burning fuels rises the upper flammability limit and lowers the lower flammability limit, which widens the flammability range of the mixture, resulting in a more efficient combustion . Extension of the flammability limits in H 2 fuel mixtures makes leaner combustion possible due to more OH molecules, which can improve emissions and thermal efficiency …”

“…Due to the extremely high burning velocity of H 2 , flashback is more probable. It has been shown that adding H 2 definitely increases the risk for flashback. , One study showed that flashback is more pronounced for pure H 2 than for H 2 mixtures, and that even a small fraction of CH 4 will reduce the flashback risk considerably . One would argue that using H 2 as a fuel additive instead of a pure fuel is advantageous when the flashback risk is the major consideration.…”