The Influence of Fuel Hydrogen Content Upon Soot Formation in a Model Gas Turbine Combustor

1984 ◽  
Vol 106 (4) ◽  
pp. 789-794 ◽  
Author(s):  
T. T. Bowden ◽  
J. H. Pearson ◽  
R. J. Wetton

The sooting tendencies of various fuel blends containing either single-ring or polycyclic aromatics have been studied in a model gas turbine combustor at a pressure of 1.0 MPa and varying values of air/fuel ratio. Sooting tendencies were determined by flame radiation, exhaust soot, and infra-red absorption measurements. The results of this study have indicated that, even for fuels containing high concentrations of naphthalenes or tetralins (> 10 percent v), fuel total hydrogen content correlates well with fuel sooting tendency. The present results are explained by a hypothesis that assumes that the majority of soot is formed in regions of high temperature, low oxygen content, and low fuel concentration, e.g., the recirculation zone.

1984 ◽  
Vol 106 (1) ◽  
pp. 109-114 ◽  
Author(s):  
T. T. Bowden ◽  
J. H. Pearson

The sooting tendencies of various hydrocarbon structures have been studied in a model gas turbine combustor at a pressure of 0.35 MPa and a preheated air temperature of 530 K. The results of this study have indicated that the sooting tendencies of fuels containing only single ring aromatics, fused bicyclic saturates, and unsaturated nonaromatics will be related to the overall hydrogen content of the fuel. However, experimental fuel blends with high concentrations (> 20 percent wt) of naphthalenes or tetralins exhibit sooting properties that are dependent upon the presence of such components. It is suggested that a kinetic scheme utilizing aromatic rings as nuclei upon which reactive fragments may stabilize can explain the present results.


2017 ◽  
Vol 140 (3) ◽  
Author(s):  
Anandkumar Makwana ◽  
Suresh Iyer ◽  
Milton Linevsky ◽  
Robert Santoro ◽  
Thomas Litzinger ◽  
...  

The objective of this study is to understand the effects of fuel volatility on soot emissions. This effect is investigated in two experimental configurations: a jet flame and a model gas turbine combustor. The jet flame provides information about the effects of fuel on the spatial development of aromatics and soot in an axisymmetric, co-flow, laminar flame. The data from the model gas turbine combustor illustrate the effect of fuel volatility on net soot production under conditions similar to an actual engine at cruise. Two fuels with different boiling points are investigated: n-heptane/n-dodecane mixture and n-hexadecane/n-dodecane mixture. The jet flames are nonpremixed and rich premixed flames in order to have fuel conditions similar to those in the primary zone of an aircraft engine combustor. The results from the jet flames indicate that the peak soot volume fraction produced in the n-hexadecane fuel is slightly higher as compared to the n-heptane fuel for both nonpremixed and premixed flames. Comparison of aromatics and soot volume fraction in nonpremixed and premixed flames shows significant differences in the spatial development of aromatics and soot along the downstream direction. The results from the model combustor indicate that, within experiment uncertainty, the net soot production is similar in both n-heptane and n-hexadecane fuel mixtures. Finally, we draw conclusions about important processes for soot formation in gas turbine combustor and what can be learned from laboratory-scale flames.


Author(s):  
W. S. Blazowski

Liquid synthetic fuels derived from non-petroleum resources will play a major role in meeting future national energy demands. In the case of gas turbine applications, it is known that the different properties of these fuels can rusult in substantially altered combustion performance. Most importantly, decreased fuel hydrogen content resulting from an increased aromatic content has been observed to result in increased exhaust smoke and particulates as well as greater flame luminosity. This paper contributes empirical information and insight which allows the greater soot formation tendencies of low hydrogen content fuels to be better understood. A small scale laboratory device which simulates the strongly backmixed conditions present in the primary zone of a gas turbine combustor is utilized. The Jet Stirred Combustor provides for very rapid mixing between a premixture of vaporized fuel and air and the combustion products within a 5.08-cm-dia hemispherical reactor. Results to be presented are gaseous combustion product distributions, incipient soot limits, and soot production (mg) for a variety of fuels. The influences of combustor inlet temperature and reactor mass loading have been evaluated and the sooting characteristics of fuel blends have been studied. These results have been analyzed to develop useful correlation which are in general agreement with existing mechanistic concepts of the soot formation process.


1980 ◽  
Vol 102 (2) ◽  
pp. 403-408 ◽  
Author(s):  
W. S. Blazowski

Liquid synthetic fuels derived from nonpetroleum resources will play a major role in meeting future national energy demands. In the case of gas turbine applications, it is known that the different properties of these fuels can result in substantially altered combustion performance. Most importantly, decreased fuel hydrogen content resulting from an increased aromatic content has been observed to result in increased exhaust smoke and particulates as well as greater flame luminosity. This paper contributes empirical information and insight which allows the greater soot formation tendencies of low hydrogen content fuels to be better understood. A small scale laboratory device which simulates the strongly backmixed conditions present in the primary zone of a gas turbine combustor is utilized. The Jet Stirred Combustor provides for very rapid mixing between a premixture of vaporized fuel and air and the combustion products within a 5.08 cm dia hemispherical reactor. Results to be presented are gaseous combustion product distributions, incipient soot limits, and soot production (mg/l) for a variety of fuels. The influences of combustor inlet temperature and reactor mass loading have been evaluated and the sooting characteristics of fuel blends have been studied. These results have been analyzed to develop useful correlations which are in general agreement with existing mechanistic concepts of the soot formation process.


Author(s):  
Jochen Stro¨hle ◽  
Tore Myhrvold ◽  
Nils A. Ro̸kke

In the present study, a numerical evaluation of different oxy-fuel concepts for a typical gas turbine combustor is performed to investigate how the inlet conditions affect fuel and CO burnout, NOx and soot emissions, and wall heat fluxes. Three oxy-fuel cases with different distribution of oxygen to the inlets are compared with a reference case using air as an oxidiser. Three-dimensional numerical simulations are performed using the in-house CFD code SPIDER. Turbulent combustion is modelled by the Eddy Dissipation Concept (EDC) with detailed chemistry and soot formation reactions. Whereas low oxygen concentrations at the fuel inlet lead to extinction of the flame, the temperature in the primary combustion zone becomes very high leading to unacceptable wall heat fluxes at high oxygen concentrations. NOx, hydrocarbons and soot emissions are very low while CO emissions are relatively high for the oxy-fuel cases.


Author(s):  
Terrence R. Meyer ◽  
Sukesh Roy ◽  
Sivaram P. Gogineni ◽  
Vincent M. Belovich ◽  
Edwin Corporan ◽  
...  

Simultaneous measurements of OH planar laser-induced fluorescence (PLIF) and laser-induced incandescence (LII) are used to characterize the flame structure and soot formation process in the reaction zone of a swirl-stabilized, JP-8-fueled model gas-turbine combustor. Studies are performed at atmospheric pressure with heated inlet air and primary-zone equivalence ratios from 0.55 to 1.3. At low equivalence ratios (φ < 0.9), large-scale structures entrain rich pockets of fuel and air deep into the flame layer; at higher equivalence ratios, these pockets grow in size and prominence, escape the OH-oxidation zone, and serve as sites for soot inception. Data are used to visualize soot development as well as to qualitatively track changes in overall soot volume fraction as a function of fuel-air ratio and fuel composition. The utility of the OH-PLIF and LII measurement system for test rig diagnostics is further demonstrated for the study of soot-mitigating additives.


Author(s):  
J. Brouwer ◽  
B. A. Ault ◽  
J. E. Bobrow ◽  
G. S. Samuelsen

Closed-loop feedback control, developed in a axisymmetric can combustor, is demonstrated in a model can combustor with discrete wall jets. The study represents the initial steps toward the application of feedback control technology to practical gas turbine combustion systems. For the present application, the radiative flux from soot particulate is used as an indication of combustor performance, and nozzle atomizing air is selected as the input parameter. A measurement of radiative flux at the exit plane of the combustor is conveyed to a control computer which invokes an optimization algorithm to determine changes in the dome region necessary to minimize the radiative flux from soot. The results demonstrate the utility and potential of active control for maintaining optimal performance in real-time.


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