Dependence of Soot Production on Fuel Blend Characteristics and Combustion Conditions

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):  
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.


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.


1981 ◽  
Vol 103 (1) ◽  
pp. 43-48 ◽  
Author(s):  
W. S. Blazowski ◽  
A. F. Sarofim ◽  
J. C. Keck

The decreased hydrogen content of future fuels will lead to increased formation of soot, while increased organically bound nitrogen in the fuel can result in excessive NOx emission. Control concepts for these two problems are in conflict: prevention of soot requires leaner operation while control of emissions from fuel nitrogen requires fuel-rich operation. However, recent results of two DOE research programs point to both processes having a major dependence on “hydrocarbon breakthrough.” Control of both fuel nitrogen conversion and soot formation can be achieved by primary zone operation at equivalence ratios just below that for hydrocarbon breakthrough. This paper reviews the evidence for the importance of hydrocarbon breakthrough, explains our current understanding of why hydrocarbon breakthrough is important, and offers suggestions of how these results might be applied.


Author(s):  
Matti Malkamäki ◽  
Ahti Jaatinen-Värri ◽  
Antti Uusitalo ◽  
Aki Grönman ◽  
Juha Honkatukia ◽  
...  

Decentralized electricity and heat production is a rising trend in small-scale industry. There is a tendency towards more distributed power generation. The decentralized power generation is also pushed forward by the policymakers. Reciprocating engines and gas turbines have an essential role in the global decentralized energy markets and improvements in their electrical efficiency have a substantial impact from the environmental and economic viewpoints. This paper introduces an intercooled and recuperated three stage, three-shaft gas turbine concept in 850 kW electric output range. The gas turbine is optimized for a realistic combination of the turbomachinery efficiencies, the turbine inlet temperature, the compressor specific speeds, the recuperation rate and the pressure ratio. The new gas turbine design is a natural development of the earlier two-spool gas turbine construction and it competes with the efficiencies achieved both with similar size reciprocating engines and large industrial gas turbines used in heat and power generation all over the world and manufactured in large production series. This paper presents a small-scale gas turbine process, which has a simulated electrical efficiency of 48% as well as thermal efficiency of 51% and can compete with reciprocating engines in terms of electrical efficiency at nominal and partial load conditions.


Author(s):  
C. P. Lea˜o ◽  
S. F. C. F. Teixeira ◽  
A. M. Silva ◽  
M. L. Nunes ◽  
L. A. S. B. Martins

In recent years, gas-turbine engines have undergone major improvements both in efficiency and cost reductions. Several inexpensive models are available in the range of 30 to 250 kWe, with electrical efficiencies already approaching 30%, due to the use of a basic air-compressor associated to an internal air pre-heater. Gas-turbine engines offer significant advantages over Diesel or IC engines, particularly when Natural Gas (NG) is used as fuel. With the current market trends toward Distributed Generation (DG) and the increased substitution of boilers by NG-fuelled cogeneration installations for CO2 emissions reduction, small-scale gas turbine units can be the ideal solution for energy systems located in urban areas. A numerical optimization method was applied to a small-scale unit delivering 100 kW of power and 0.86 kg/s of water, heated from 318 to 353K. In this academic study, the unit is based on a micro gas-turbine and includes an internal pre-heater, typical of these low pressure-ratio turbines, and an external heat recovery system. The problem was formulated as a non-linear optimisation model with the minimisation of costs subject to the physical and thermodynamic constraints. Despite difficulties in obtaining data for some of the components cost-equations, the preliminary results indicate that the optimal compressor pressure ratio is about half of the usual values found in large installations, but higher than those of the currently available micro-turbine models, while the turbine inlet temperature remains virtually unchanged.


1975 ◽  
Vol 97 (4) ◽  
pp. 527-530 ◽  
Author(s):  
R. Kollrack ◽  
L. D. Aceto

An evaluation of the effects caused by recirculation of hot final combustion products into unburned or partially burned fuel/air mixtures indicates that the thermal effect predominates the combustion activity. Dilution and the introduction of active radicals produce lesser results. Internal recirculation, such as produced by swirl or bluff body stabilization, differs from external recirculation by the temperature levels of the recirculant and its composition. The net effect of recirculation is to simulate a longer residence time and/or an effective higher inlet temperature. As a general result, the end products are closer to equilibrium, specifically the CO levels are lower and the NO levels higher.


Biomass fuel as carbon neutral, abundant, domestic, cost effective is being reconsidered to fuel-up the power plant to produce electricity in clean way. But utilization of biomass fuel directly in existing conventional power plant causes problem in turbine such as erosion, hot corrosion, clogging and depositions [1]. As such combustion of biomass fuel outside the primary cycle eradicates potential hazards for turbine. In such a case indirectly fired micro gas turbine opens a door to biomass fuel as this technology is free from negative aspects of direct combustion as well as making micro gas turbine feasible to generate electricity in small scale at non-grid areas for individual consumer or group of consumers. In this research, the effect of different types of biomass fuel on operating parameters as well as on output electrical power of externally fired micro gas turbine (EFmGT)has been analyzed. The biomass fuels are categorized on the basis of air to fuel ratio (AFR) using stoichiometry combustion theory. It is found from results that parameters like air mass flow rate, compression ratio, heat exchanger effectiveness, turbine inlet temperature, combustion temperature, and temperature difference in heat exchanger affect the performance of EFmGT. Also types of biomass fuel have substantial impacts on these performance parameters as well as on electrical power output of EFmGT cycle.


2021 ◽  
Author(s):  
Mario Ditaranto ◽  
Inge Saanum ◽  
Jenny Larfeldt

Abstract Hydrogen, a carbon-free fuel, is a challenging gas to transport and store, but that can be solved by producing ammonia, a worldwide commonly distributed chemical. Ideally, ammonia should be used directly on site as a fuel, but it has many combustion shortcomings, with a very low reactivity and a high propensity to generate NOx. Alternatively, ammonia could be decomposed back to a mixture of hydrogen and nitrogen which has better combustion properties, but at the expense of an endothermal reaction. Between these two options, a trade off could be a partial decomposition where the end use fuel is a mixture of ammonia, hydrogen, and nitrogen. We present an experimental study aiming at finding optimal NH3-H2-N2 fuel blends to be used in gas turbines and provide manufacturers with guidelines for their use in retrofit and new combustion applications. The industrial burner considered in this study is a small-scale Siemens burner used in the SGT-750 gas turbine, tested in the SINTEF high pressure combustion facility. The overall behaviour of the burner in terms of stability and emissions is characterized as a function of fuel mixtures corresponding to partial and full decomposition of ammonia. It is found that when ammonia is present in the fuel, the NOx emissions although high can be limited if the primary flame zone is operated fuel rich. Increasing pressure has shown to have a strong and favourable effect on NOx formation. When ammonia is fully decomposed to 75% H2 and 25% N2, the opposite behaviour is observed. In conclusion, either low rate or full decomposition are found to be the better options.


Author(s):  
Cristian Aldana ◽  
Ramkumar N. Parthasarathy ◽  
Subramanyam R. Gollahalli

Canola methyl ester (CME) is a biofuel that is produced by the transesterification of canola oil; it is renewable, carbon-neutral and low in sulfur content. The objective of this study was to document the combustion characteristics of spray flames of CME and No 2 diesel (petroleum fuel) blends. Three blends with 25%, 50% and 75% volume concentration of CME were studied. The fuel was atomized and mixed with air in a heated environment at a supply equivalence ratio of 0.62. Measurements of global CO and NO emissions, inflame temperature and in-flame concentrations of combustion products were made. The near-injector homogeneous gas-phase reaction zone increased in size with the addition of CME. The global CO and NO emissions decreased with the increase in CME content in the fuel blend. The in-flame NO concentration profiles and flame temperature profiles followed similar trends, suggesting that the thermal mechanism of NO formation was dominant in these flames.


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