NOx Formation in High-Pressure Jet-Stirred Reactors With Significance to Lean-Premixed Combustion Turbines

Abstract

Measurements of NOx and CO in methane-fired, lean-premixed, high-pressure jet-stirred reactors (HP-JSRs) independently obtained by Rutar [1] and Rutar et al. [2] and by Bengtsson [3] and Bengtsson et al. [4] are well predicted assuming simple chemical reactor models and the GRI 3.0 chemical kinetic mechanism. The single-jet HP-JSR of Rutar [1] and Rutar et al. [2] is well modeled for NOx and CO assuming a single PSR for Damköhler number below 0.15. Under these conditions, the estimates of flame thickness indicate the flame zone, that is, the region of rapid oxidation and large concentrations of free radicals, fully fills the HP-JSR. For Damköhler number above 0.15, that is, for longer residence times, the NOx and CO are well modeled assuming two PSRs in series, representing a small flame zone followed by a large post-flame zone. The multi-jet reactor of Bengtsson [3] and Bengtsson et al. [4] is well modeled assuming a large PSR (over 88% of the reactor volume) followed by a short PFR, which accounts for the exit region of the HP-JSR and the short section of exhaust prior to the sampling point. The Damköhler number is estimated between 0.01 and 0.03. Our modeling shows the NOx formation pathway contributions. Although all pathways, including Zeldovich (under the influence of super-equilibrium O-atom), nitrous oxide, Fenimore prompt, and NNH, contribute to the total NOx predicted, of special note are the following findings: 1) NOx formed by the nitrous oxide pathway is significant throughout the conditions studied; and 2) NOx formed by the Fenimore prompt pathway is significant when the fuel-air equivalence ratio is greater than about 0.7 (as might occur in a piloted lean-premixed combustor) or when the residence time of the flame zone is very short. The latter effect is a consequence of the short lifetime of the CH radical in flames.

Fuel quality impact analysis for practical implementation of corn COB gasification gas in conventional gas turbine power plants

“…For all conditions, a hybrid Perfectly Stirred Reactor-Plug Flow Reactor (PSR-PFR) network was employed, which is commonly used to simulate mixing and flow characteristics in gas turbine combustor networks [31]. The reactor configuration consists of two clusters; the first cluster is a Perfectly Stirred Reactor (PSR), in which three distinct zones are applied; a mixing zone where fuel is partly premixed, a flame region directly connected to the former and the central recirculation zone (CRZ) where the products are recirculated [15,16].…”

Real-time prediction of lean blowout using chemical reactor network

“…[25][26][27][28][29][30] employed a two element reactor to study the influence of lean blowout limit of an industrial gas turbine. Lefebvre [31] established a quantitative relationship between aspects of combustion and physical properties of the combustor based on the well-stirred reactor concept.…”

Model-Based Approach for Combustion Monitoring Using Real-Time Chemical Reactor Network

“…In zonal modeling, the combustor volume is divided into idealized PSR and PFR elements, where the flow conditions for the elements can be calculated based on the dissipation gradient method. Simple chemical reactor models have been used for evaluating pollutant emission trends in laboratory combustors, e.g., [32][33][34][35][36]. While these approaches provide quick and useful insight into emission trends, more advanced CRNs containing ten or more reactor elements can address the complex flow field inside the combustor.…”