The Effects of LBG Composition and Combustor Characteristics on Fuel NOx Formation

1980 ◽  
Vol 102 (2) ◽  
pp. 459-467 ◽  
Author(s):  
B. A. Folsom ◽  
C. W. Courtney ◽  
M. P. Heap
Keyword(s):  
Diffusion Flame ◽  
Hydrocarbon Fuel ◽  
Attractive Alternative ◽  
Nox Emissions ◽  
Catalytic Reactor ◽  
Nox Formation ◽  
Fuel Gas ◽  
Flame Reactor ◽  
Reactor Operating ◽  
Low Sulfur

The low Btu gas (LBG) combined gas and steam turbine power cycle is a potentially attractive alternative to the direct coal fired steam cycle because of the potential for low sulfur emissions and high overall cycle efficiency. However, LBG may contain ammonia (NH3) which could be converted to nitrogen oxides (NOx) under typical combustion conditions. This paper examines the effects of LBG composition and combustor design on NOx emissions. Low Btu gases of varying compositions were synthesized from bottled gases and fired in three atmospheric pressure flame reactors: diffusion flame reactor, flat flame reactor and catalytic reactor. Nitrogen oxide emissions were found to be most sensitive to the concentrations of NH3 and hydrocarbon fuel gas in the synthetic LBG. Lowest NOx emissions were produced by the diffusion flame reactor operating at near stoichiometric conditions and the catalytic reactor operating fuel rich.

Bench Scale Testing of Low-NOx LBG Combustors

1982 ◽  
Vol 104 (1) ◽  
pp. 120-128 ◽  
Author(s):  
W. D. Clark ◽  
B. A. Folsom ◽  
W. R. Seeker ◽  
C. W. Courtney
Keyword(s):  
Gas Turbine ◽  
Residence Time ◽  
Attractive Alternative ◽  
Nox Emissions ◽  
Catalytic Reactor ◽  
Power Cycle ◽  
Bench Scale ◽  
Gasification Process ◽  
Stirred Reactor ◽  
Catalytic Reformer

The high efficiencies obtained in a combined gas-turbine/steam-turbine power cycle burning low Btu gas (LBG) make it a potentially attractive alternative to the high sulfur emitting direct coal-fired steam cycle. In the gasification process, much of the bound nitrogen in coal is converted to ammonia in the LBG. This ammonia is largely converted to nitrogen oxides (NOx) in conventional combustors. This paper examines the pressurized bench scale performance of reactors previously demonstrated to produce low NOx emissions in atmospheric laboratory scale experiments. LBG was synthesized in a catalytic reformer and fired in three reactors: a catalytic reactor, a diffusion flame, and a stirred reactor. Effects of scale, pressure, stoichiometry, residence time, and preheat were examined. Lowest NOx emissions were produced in a rich/lean series staged catalytic reactor.

Predictions of NOx Formation Under Combined Droplet and Partially Premixed Reaction of Diffusion Flame Combustors

1999 ◽  
Vol 124 (1) ◽  
pp. 31-38 ◽  
Author(s):  
N. K. Rizk ◽  
J. S. Chin ◽  
A. W. Marshall ◽  
M. K. Razdan
Keyword(s):  
Diffusion Flame ◽  
Liquid Droplet ◽  
Mixture Distribution ◽  
Fuel Vapor ◽  
Nox Emissions ◽  
Gas Temperature ◽  
Nox Formation ◽  
Primary Zone ◽  
Wide Range ◽  
Partially Premixed

A methodology is presented in this paper on the modeling of NOx formation in diffusion flame combustors where both droplet burning and partially premixed reaction proceed simultaneously. The model simulates various combustion zones with an arrangement of reactors that are coupled with a detailed chemical reaction scheme. In this model, the primary zone of the combustor comprises a reactor representing contribution from droplet burning under stoichiometric conditions and a mixing reactor that provides additional air or fuel to the primary zone. The additional flow allows forming a fuel vapor/air mixture distribution that reflects the unmixedness nature of the fuel injection process. Expressions to estimate the extent of deviation in fuel/air ratios from the mean value, and the duration of droplet burning under stoichiometric conditions were derived. The derivation of the expressions utilized a data base obtained in a parametric study performed using a conventional gas turbine combustor where the primary zone equivalence ratio varied over a wide range of operation. The application of the developed model to a production combustor indicated that most of the NOx produced under the engine takeoff mode occurred in the primary as well as the intermediate regions. The delay in NOx formation is attributed to the operation of the primary zone under fuel rich conditions resulting in a less favorable condition for NOx formation. The residence time for droplet burning increased with a decrease in engine power. The lower primary zone gas temperature that limits the spray evaporation process coupled with the leaner primary zone mixtures under idle and low power modes increases the NOx contribution from liquid droplet combustion in diffusion flames. Good agreement was achieved between the measured and calculated NOx emissions for the production combustor. This indicates that the simulation of the diffusion flame by a combined droplet burning and fuel vapor/air mixture distribution offers a promising approach for estimating NOx emissions in combustors, in particular for those with significant deviation from traditional stoichiometry in the primary combustion zone.

Predictions of NOx Formation Under Combined Droplet and Partially Premixed Reaction of Diffusion Flame Combustors

1999 ◽  
Author(s):  
Nader K. Rizk ◽  
Ju S. Chin ◽  
Andre W. Marshall ◽  
Mohan K. Razdan
Keyword(s):  
Diffusion Flame ◽  
Liquid Droplet ◽  
Mixture Distribution ◽  
Fuel Vapor ◽  
Nox Emissions ◽  
Gas Temperature ◽  
Nox Formation ◽  
Primary Zone ◽  
Wide Range ◽  
Partially Premixed

A methodology is presented in this paper on the modeling of NOx formation in diffusion flame combustors where both droplet burning and partially premixed reaction proceed simultaneously. The model simulates various combustion zones with an arrangement of reactors that are coupled with a detailed chemical reaction scheme. In this model, the primary zone of the combustor comprises a reactor representing contribution from droplet burning under stoichiometric conditions and a mixing reactor that provides additional air or fuel to the primary zone. The additional flow allows forming a fuel vapor/air mixture distribution that reflects the unmixedness nature of the fuel injection process. Expressions to estimate the extent of deviation in fuel/air ratios from the mean value, and the duration of droplet burning under stoichiometric conditions were derived. The derivation of the expressions utilized a data base obtained in a parametric study performed using a conventional gas turbine combustor where the primary zone equivalence ratio varied over a wide range of operation. The application of the developed model to a production combustor indicated that most of the NOx produced under the engine takeoff mode occurred in the primary as well as the intermediate regions. The delay in NOx formation is attributed to the operation of the primary zone under fuel rich conditions resulting in a less favorable condition for NOx formation. The residence time for droplet burning increased with a decrease in engine power. The lower primary zone gas temperature that limits the spray evaporation process coupled with the leaner primary zone mixtures under idle and low power modes increases the NOx contribution from liquid droplet combustion in diffusion flames. Good agreement was achieved between the measured and calculated NOx emissions for the production combustor. This indicates that the simulation of the diffusion flame by a combined droplet burning and fuel vapor/air mixture distribution offers a promising approach for estimating NOx emissions in combustors, in particular for those with significant deviation from traditional stoichiometry in the primary combustion zone.

scholarly journals Design and Operation of Low-NOx Combustors With Medium Heating Value, Coal-Derived Gas

1980 ◽  
Author(s):  
J. R. Grant ◽  
T. E. Holladay ◽  
F. H. Boenig ◽  
R. L. Duncan
Keyword(s):  
Gas Turbine ◽  
Diffusion Flame ◽  
Electrical Power ◽  
Water Injection ◽  
Attractive Alternative ◽  
Nox Emissions ◽  
Gas Turbine Combustor ◽  
Heating Value ◽  
Alternative Means ◽  
High Concentrations

Industrial turbines fired on medium heating value (MHV) gas (nominally 300 Btu/scf) synthesized from coal offer an attractive alternative means of producing electrical power in the future. Peak flame temperatures resulting from combustion of this MHV gas in conventional diffusion flame combustors may be comparable to those of natural gas, yielding undesirably high concentrations of NOx. This paper describes an EPRI-sponsored program conducted to demonstrate a MHV gas turbine combustor capable of meeting EPA NOx requirements without water injection. Program objectives were to design, fabricate, and test three MHV combustor configurations and to demonstrate NOx emissions concentrations of 15 ppmv (dry basis) or less at a burner inlet pressure of 1.27 atm: Design of the combustors was based on a lean-premix fuel metering concept. Tests were conducted in a single-can combustor rig at simulated engine conditions ranging from 40 to 125 percent of engine baseload (74 MW).

Effect of Fuel Composition on NOx Formation in Lean Premixed Prevaporized Combustion

1997 ◽  
Author(s):  
Scott A. Capehart ◽  
John C. Y. Lee ◽  
Joseph T. Williams ◽  
Philip C. Malte
Keyword(s):  
High Intensity ◽  
Carbon Number ◽  
Fuel Oil ◽  
Liquid Fuels ◽  
Fuel Composition ◽  
Nox Formation ◽  
Stirred Reactor ◽  
Lean Premixed ◽  
Reactor Operating ◽  
Low Sulfur

The effect of fuel composition on NOx formation in lean premixed prevaporized (LPP) combustion is examined using an atmospheric pressure jet-stirred reactor fitted with a prevaporizing-premixing chamber and liquid fuel atomizing nozzle. Four liquid fuels are studied, including the pure hydrocarbons n-heptane (C7H16) and n-dodecane (C12H26), No. 2 low sulfur diesel fuel oil (LSDFO#2) with 0.0195% sulfur and 0.0124% nitrogen by weight, and n-dodecane doped with n-ethylethylenediamine (C2H5NHCH2CH2NH2 or C4H12N2) to give 0.0096% nitrogen by weight in the doped fuel. For comparison, propane (C3H6) is burned. The combustion temperature range of the experiments is 1625 to 1925K, and the nominal residence time of the reactor is 3.5ms. The first objective of the work is to determine the effect which increasing fuel carbon number has on the NOx yield of high-intensity LPP combustion. For combustion at 1800K, an increase of 15 to 20% is measured in the NOx yield when the fuel is changed from C3H6 to C12H26. Comparison to earlier work on CH4 and C3H6 combustion in the jet-stirred reactor operating at 1800K shows essentially an identical increase in NOx yield between CH4 and C3H6 as between C3H6 and C12H26. The second objective of the work is to determine the conversion of fuel-nitrogen to NOx for the combustion of low nitrogen content fuels in high-intensity LPP combustion. The measurements indicate a fuel-nitrogen to NOx conversion of 70 to 100%. These conversion values should be regarded as preliminary since only two nitrogen-containing fuels have been examined and only one prevaporizer-premixer system has been used.

Staged Premix EV Combustion in Alstom’s GT24 Gas Turbine Engine

2012 ◽  
Author(s):  
Daniel Guyot ◽  
Thiemo Meeuwissen ◽  
Dieter Rebhan
Keyword(s):  
Gas Turbine ◽  
Distribution System ◽  
Fuel Oil ◽  
Operational Flexibility ◽  
Nox Formation ◽  
Diffusion Type ◽  
Fuel Gas ◽  
Start Up ◽  
Reduce Emissions ◽  
Ev Burner

Reducing gas turbine emissions and increasing their operational flexibility are key targets in today’s gas turbine market. In order to further reduce emissions and increase the operational flexibility of its GT24, Alstom has introduced an internally staged premix system into the GT24’s EV combustor. This system features a rich premix mode for GT start-up and a lean premix mode for GT loading and baseload operation. The fuel gas is injected through two premix stages, one injecting fuel into the burner air slots and one injecting fuel into the centre of the burner cone. Both premix stages are in continuous operation throughout the entire operating range, i.e. from ignition to baseload, thus eliminating the previously used pilot operation during start-up with its diffusion-type flame and high levels of NOx formation. The staged EV combustion concept is today a standard on the current GT26 and GT24. The EV burners of the GT26 are identical to the GT24 and fully retrofittable into existing GT24 engines. Furthermore, engines operating only on fuel gas (i.e. no fuel oil operation) no longer require a nitrogen purge and blocking air system so that this system can be disconnected from the GT. Only minor changes to the existing GT24 EV combustor and fuel distribution system are required. This paper presents validation results for the staged EV burner obtained in a single burner test rig at full engine pressure, and in a GT24 field engine, which had been upgraded with the staged EV burner technology in order to reduce emissions and extend the combustor’s operational behavior.

Analysis of preparation of TiO2 particles by diffusion flame reactor for photodegradation of phenol and toluene

2008 ◽  
Vol 34 (4) ◽  
pp. 319-329 ◽  
Author(s):  
Piyabutr Sunsap ◽  
Dong-Joo Kim ◽  
Tawatchai Charinpanitkul ◽  
Kyo-Seon Kim
Keyword(s):  
Diffusion Flame ◽  
Tio2 Particles ◽  
Flame Reactor

Effect of Biodiesel, JP-8 and Ultra Low Sulfur Diesel Fuel on Autoignition, Combustion, Performance and Emissions in a Single Cylinder Diesel Engine

2010 ◽  
Author(s):  
Chandrasekharan Jayakumar ◽  
Jagdish Nargunde ◽  
Anubhav Sinha ◽  
Walter Bryzik ◽  
Naeim A. Henein ◽  
...  
Keyword(s):  
Diesel Engine ◽  
Fuel Properties ◽  
Nox Emissions ◽  
Single Cylinder ◽  
Combustion Performance ◽  
Ultra Low Sulfur Diesel ◽  
Diffusion Controlled ◽  
Performance And Emissions ◽  
Combustion Fraction ◽  
Low Sulfur

Concern about the depletion of petroleum reserves, rising prices of conventional fuels, security of supply and global warming have driven research toward the development of renewable fuels for use in diesel engines. These fuels have different physical and chemical properties that affect the diesel combustion process. This paper compares between the autoignition, combustion, performance and emissions of soybean derived biodiesel, JP-8 and ultra low sulfur diesel (ULSD) in a high speed single-cylinder research diesel engine equipped with a common rail injection system. Tests were conducted at steady state conditions at different injection pressures ranging from 600 bar to 1200 bar. The ‘rate of heat release’ traces are analyzed to determine the effect of fuel properties on the ignition delay, premixed combustion fraction and mixing and diffusion controlled combustion fractions. Biodiesel produced the largest diffusion controlled combustion fraction at all injection pressures compared to ULSD and JP-8. At 600 bar injection pressure, the diffusion controlled combustion fraction for biodiesel was 53% whereas both JP-8 and ULSD produced 39%. In addition, the effect of fuel properties on engine performance, fuel economy, and engine-out emissions is determined. On an average JP-8 produced 3% higher thermal efficiency than ULSD. Special attention is given to the NOx emissions and particulate matter characteristics. On an average biodiesel produced 37% less NOx emissions compared to ULSD and JP-8.

NOx Emissions in a Steel Reheat Furnace Firing By-Product Fuels

2001 ◽  
Author(s):  
Bradley R. Adams ◽  
Dave H. Wang
Keyword(s):  
Low Cost ◽  
Nox Reduction ◽  
Coke Oven ◽  
Cfd Modeling ◽  
Stoichiometric Ratio ◽  
Nox Emissions ◽  
Confined Space ◽  
Nox Formation ◽  
Reheat Furnace ◽  
Bottom Zone

Abstract A DOE-funded program was used to understand the mechanisms that control the formation of NOx during the combustion of steelmaking by-product fuels and to investigate possible low-cost control options to minimize the NOx emissions. This paper discusses the CFD modeling results of NOx emissions in a reheat furnace. The reheat furnace has a total of 20 burners distributed over three firing zones. The furnace is fired at a rate of 250 × 106 Btu/hr and an overall stoichiometric ratio of 1.06 (fuel lean). Fuels with heating values of approximate 500 Btu/SCF were examined, including coke oven gas (COG), blast furnace gas (BFG) and a blend of COG, BFG, natural gas (NG) and nitrogen. A good range of process variables was modeled to examine effects of fuel type, air preheat, stoichiometric ratio, firing rate and burner stoichiometry distribution on NOx emissions. Modeling results indicated that NOx formation in the reheat furnace is dominated by thermal NO, with some variation depending on the fuel fired. Temperature profiles showed an effective separation of the furnace interior into top and bottom zones as a result of the steel slab barrier. Higher temperatures characterized the bottom zone and elevated NOx levels as a result of the confined space and enhanced fuel air mixing provided by the slab supports. Results also showed that reburning of NOx plays a significant role in final NOx emissions with 30–40% of NOx formed being reduced by reburning in most cases. Modeling identified that operating the side burners in each burner zone slightly substoichiometric (while maintaining the overall furnace stoichiometry at 1.06) provided significant NOx reduction via reburning. NOx reductions of 23% and 30% were predicted when firing with COG and COG-NG-Air fuels, respectively. Overall furnace exit temperatures and heat flux profiles were not significantly affected by the biased firing.

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