Session: 04-43 Hydrogen Emissions III

Submission Number: 175949

Evaluation of Multipoint Lean Direct Injection Nozzle Arrays at Atmospheric Condition 

Previous studies conducted by Escudero et al., Tran et al., and Overbaugh et al. demonstrated the potential of the Lean Direct Injection (LDI) concept for hydrogen gas turbine combustors. Such work outlined specific nozzle geometries that enabled LDI nozzles to operate on various natural gas-hydrogen blends, from 100% natural gas to 100% hydrogen, while maintaining low NOx emissions. To evolve the LDI concept from applied research towards a full-scale combustor, two multipoint-LDI (MLDI) combustors, each with a unique nozzle-nozzle spacing are characterized. Nozzle Configuration 7 (C7) from the previous studies was selected as the basis for the MLDI arrays, which consists of one ‘pilot’ nozzle encircled by six ‘main’ nozzles, each grouping having distinct fuel passages and controls. A Box-Behnken experimental design was used to characterize the NOx emissions performance of each array. Tests were devised to study the effect of adiabatic flame temperature (AFT), pressure drop (PD), and pilot-main-ratio (PMR), which defines the fuel split between the pilot and main nozzles. The preheat temperature was maintained at 600K throughout this phase of testing whereas the pressure drop and flame temperature varied systematically from 3-5% and 1600-1900K, respectively. To study the fuel and hardware effects on the emissions, this test plan was repeated multiple times in a series of blocks, one for each spacing-fuel combination. A modified Box Behnken experimental design was used to characterize array stability, which is defined by the lean blowoff point. Results from the current testing were compared to previous single nozzle testing, including flame observations, emissions measurements, and operational challenges. Flame temperature, PMR, and nozzle spacing were found to have a significant effect on NOx emissions, whereas fuel type and pressure drop were found to be insignificant. PMR, preheat temperature, and nozzle spacing were found to correlate well to the lean blowoff flame temperature. NOx emissions are reported on a volume basis in ppmvd corrected to 15% O₂ and corrected for fuel. 

Presenting Author: Malcolm Overbaugh University of California, Irvine

Presenting Author Biography: PhD student

Authors:

Malcolm Overbaugh University of California, Irvine
Brandon Esquivias University of California, Irvine
Vincent Mc Donell University of California - Irvine