I134 Variations of the Flame Structures and the Fuel-NOx Formation Characteristics with High CO_2 Dilution

Ammonia contained in coal-gasified fuel is converted to nitrogen oxides (NOx) in the combustion process of a gas turbine in integrated coal gasification combined cycle (IGCC) system. Research data on fuel-NOx formation are insufficient, and there still remains a wide explored domain. The present research aims at obtaining fundamental knowledge of fuel-NOx formation characteristics by applying reaction kinetics to gas turbine conditions. An instantaneous mixing condition was assumed in the cross section of a gas turbine combustor and both gradual mixing condition and instantaneous mixing condition were assumed at secondary air inlet section. The results may be summarized as follows: (1) in the primary combustion zone under fuel rich condition, HCN and other intermediate products are formed as ammonia contained in the fuel decomposes; (2) formation characteristics of fuel-NOx are affected by the condition of secondary air mixing; and (3) the conversion ratio from ammonia to NOx declines as the pressure inside the combustor rises under the condition of gradual mixing at the secondary air inlet. These results obtained agreed approximately with the experimentation.

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Emissions Performance of the Parker Macrolaminate Premixer Tested Under Simulated Engine Conditions

Journal of Engineering for Gas Turbines and Power ◽

10.1115/1.1762907 ◽

2004 ◽

Vol 126 (3) ◽

pp. 465-471

Author(s):

Adel Mansour ◽

Michael A. Benjamin

Keyword(s):

Pressure Drop ◽

Liquid Fuel ◽

Flame Temperature ◽

Operating Conditions ◽

Inlet Temperature ◽

Nox Formation ◽

Pressure Drops ◽

Lean Blowout ◽

Stirred Reactor ◽

Fuel Nox

Single-injector high-pressure rig evaluation of the prototype Parker macrolaminate dual fuel premixer (previously tested at NETL, Mansour et al., 2001) with pressure swirl macrolaminate atomizers was conducted under simulated engine operating conditions running on No. 2 diesel fuel (DF2). Emissions, oscillations and lean blowout (LBO) performance on liquid fuel at high, part and no load operating points (pressures of 160, 100, 120 psig, and inlet temperatures of 690, 570, 590°F, respectively) and various pressure drops (ΔP/P) and air fuel ratio conditions were investigated. The results indicate that the Parker premixer design has the potential to reduce the DF2 NOX emission to below 15 ppmv, 15% O2. At simulated high load conditions with a nominal flame temperature TPZ of 2700°F, the NOX and CO emissions are approximately 10 and 2.5 ppmv at 15% O2, respectively. These NOX results have not been corrected for fuel bound nitrogen (FBN). From the studies of Lee (2000), small amounts of FBN in the liquid fuel generally are completely converted over to fuel NOX under lean premixed conditions. The fuel tested has a nominal 60 ppmw of FBN which converts to an estimated fuel NOX of 4 ppmv at 15% O2. These results compare extremely favorable to existing commercially available premixer technologies tested under similar rig operating conditions. More importantly, the NOX yield for the Parker Macrolaminate premixer appears to be independent of operating conditions (from high to no load and various pressure drop conditions). Variations in combustor pressure, inlet temperature T2 and residence time (τ) or pressure drop (ΔP/P) does not seem to have an effect on the formation of NOX. According to Leonard and Stegmaier (1993), insensitivity of NOX formation to operating conditions is a good indication of high degree of premixing. Additionally, the premixer NOX data is only 1 to 2 ppmv higher than the jet stirred reactor (JSR) results (ran at T2=661°F,PCD=1 atm and TPZ=2762°F with similar DF2) of Lee et al. (2001) further confirming the quality of premixing achieved. Combustion driven oscillations was not investigated by tuning the rig so that oscillations would not be a factor.

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