Effect of Natural Gas Composition on Low NOx Burners Operation in Heavy Duty Gas Turbine

Author(s):  
Serena Romano ◽  
Matteo Cerutti ◽  
Giovanni Riccio ◽  
Antonio Andreini ◽  
Christian Romano

Abstract Development of lean-premixed combustion technology with low emissions and stable operation in an increasingly wide range of operating conditions requires a deep understanding of the mechanisms that affect the combustion performance or even the operability of the entire gas turbine. Due to the relative wide range of natural gas composition supplies and the increased demand from Oil&Gas customers to burn unprocessed gas as well as LNG with notable higher hydrocarbons (C2+) content; the impact on gas turbine operability and combustion related aspects has been matter of several studies. In this paper, results of experimental test campaign of an annular combustor for heavy-duty gas turbine are presented with focus on the effect of fuel composition on both emissions and flame stability. Test campaign involved two different facilities, a full annular combustor rig and a full-scale prototype engine fed with different fuel mixtures of natural gas with small to moderate C2H6 content. Emissions trends and blowout for several operating conditions and burner configurations have been analyzed. Modifications to the burner geometry and fuel injection optimization have shown to be able to reach a good trade-off while keeping low NOx emissions in stable operating conditions for varying fuel composition.

2019 ◽  
Vol 141 (11) ◽  
Author(s):  
Serena Romano ◽  
Matteo Cerutti ◽  
Giovanni Riccio ◽  
Antonio Andreini ◽  
Christian Romano

Abstract Development of lean-premixed combustion technology with low emissions and stable operation in an increasingly wide range of operating conditions requires a deep understanding of the mechanisms that affect the combustion performance or even the operability of the entire gas turbine. Due to the relative wide range of natural gas composition supplies and the increased demand from Oil&Gas customers to burn unprocessed gas as well as liquified natural gas (LNG) with notable higher hydrocarbons (C2+) content, the impact on gas turbine operability and combustion related aspects has been matter of several studies. In this paper, results of experimental test campaign of an annular combustor for heavy-duty gas turbine are presented with focus on the effect of fuel composition on both emissions and flame stability. Test campaign involved two different facilities, a full annular combustor rig and a full-scale prototype engine fed with different fuel mixtures of natural gas with small to moderate C2H6 content. Emission trends and blowout for several operating conditions and burner configurations have been analyzed. Modifications to the burner geometry and fuel injection optimization have shown to be able to reach a good tradeoff while keeping low NOx emissions in stable operating conditions for varying fuel composition.


2021 ◽  
Vol 143 (3) ◽  
Author(s):  
Serena Romano ◽  
Roberto Meloni ◽  
Giovanni Riccio ◽  
Pier Carlo Nassini ◽  
Antonio Andreini

Abstract This paper addresses the impact of natural gas composition on both the operability and emissions of lean premixed gas turbine combustion system. This is an issue of growing interest due to the challenge for gas turbine manufacturers in developing fuel-flexible combustors capable of operating with variable fuel gases while producing very low emissions at the same time. Natural gas contains primarily methane (CH4) but also notable quantities of higher order hydrocarbons such as ethane (C2H6) can also be present. A deep understanding of natural gas combustion is important to obtain the highest combustion efficiency with minimal environmental impact. For this purpose, Large Eddy Simulations of an annular combustor sector equipped with a partially premixed burner are carried out for two different natural gas compositions with and without including the effect of flame strain rate and heat loss resulting in a more adequate description of flame shape, thermal field, and extinction phenomena. Promising results, in terms of NOx, compared against available experimental data, are obtained including these effects on the flame brush modeling, enhancing the fuel-dependency under nonadiabatic condition.


Author(s):  
S. Romano ◽  
R. Meloni ◽  
G. Riccio ◽  
P. C. Nassini ◽  
A. Andreini

Abstract This paper addresses the impact of natural gas composition on both the operability and emissions of lean premixed gas turbine combustion system. This is an issue of growing interest due to the challenge for gas turbine manufacturers in developing fuel-flexible combustors capable of operating with variable fuel gases while producing very low emissions at the same time. Natural gas contains primarily methane (CH4) but also notable quantities of higher order hydrocarbons such as ethane (C2H6) can also be present. A deep understanding of natural gas combustion is important to obtain the highest combustion efficiency with minimal environmental impact. For this purpose, Large Eddy Simulations of an annular combustor sector equipped with a partially-premixed burner are carried out for two different natural gas compositions with and without including the effect of flame strain rate and heat loss resulting in a more adequate description of flame shape, thermal field and extinction phenomena. Promising results, in terms of NOx, compared against available experimental data, are obtained including these effects on the flame brush modelling, enhancing the fuel-dependency under non adiabatic condition.


Author(s):  
Matteo Cerutti ◽  
Roberto Modi ◽  
Danielle Kalitan ◽  
Kapil K. Singh

As government regulations become increasingly strict with regards to combustion pollutant emissions, new gas turbine combustor designs must produce lower NOx while also maintaining acceptable combustor operability. The design and implementation of an efficient fuel/air premixer is paramount to achieving low emissions. Options for improving the design of a natural gas fired heavy-duty gas turbine partially premixed fuel nozzle have been considered in the current study. In particular, the study focused on fuel injection and pilot/main interaction at high pressure and high inlet temperature. NOx emissions results have been reported and analyzed for a baseline nozzle first. Available experience is shared in this paper in the form of a NOx correlative model, giving evidence of the consistency of current results with past campaigns. Subsequently, new fuel nozzle premixer designs have been investigated and compared, mainly in terms of NOx emissions performance. The operating range of investigation has been preliminarily checked by means of a flame stability assessment. Adequate margin to lean blow out and thermo-acoustic instabilities onset has been found while also maintaining acceptable CO emissions. NOx emission data were collected over a variety of fuel/air ratios and pilot/main splits for all the fuel nozzle configurations. Results clearly indicated the most effective design option in reducing NOx. In addition, the impact of each design modification has been quantified and the baseline correlative NOx emissions model calibrated to describe the new fuel nozzles behavior. Effect of inlet air pressure has been evaluated and included in the models, allowing the extensive use of less costly reduced pressure test campaigns hereafter. Although the observed effect of combustor pressure drop on NOx is not dominant for this particular fuel nozzle, sensitivity has been performed to consolidate gathered experience and to make the model able to evaluate even small design changes affecting pressure drop.


2016 ◽  
Vol 139 (2) ◽  
Author(s):  
Shi Liu ◽  
Hong Yin ◽  
Yan Xiong ◽  
Xiaoqing Xiao

Heavy duty gas turbines are the core components in the integrated gasification combined cycle (IGCC) system. Different from the conventional fuel for gas turbine such as natural gas and light diesel, the combustible component acquired from the IGCC system is hydrogen-rich syngas fuel. It is important to modify the original gas turbine combustor or redesign a new combustor for syngas application since the fuel properties are featured with the wide range hydrogen and carbon monoxide mixture. First, one heavy duty gas turbine combustor which adopts natural gas and light diesel was selected as the original type. The redesign work mainly focused on the combustor head and nozzle arrangements. This paper investigated two feasible combustor arrangements for the syngas utilization including single nozzle and multiple nozzles. Numerical simulations are conducted to compare the flow field, temperature field, composition distributions, and overall performance of the two schemes. The obtained results show that the flow structure of the multiple nozzles scheme is better and the temperature distribution inside the combustor is more uniform, and the total pressure recovery is higher than the single nozzle scheme. Through the full scale test rig verification, the combustor redesign with multiple nozzles scheme is acceptable under middle and high pressure combustion test conditions. Besides, the numerical computations generally match with the experimental results.


2021 ◽  
Author(s):  
Serena Romano ◽  
Roberto Meloni ◽  
Pier Carlo Nassini ◽  
Antonio Andreini ◽  
Giovanni Riccio

Author(s):  
Matteo Cerutti ◽  
Nicola Giannini ◽  
Gianni Ceccherini ◽  
Roberto Meloni ◽  
Emanuele Matoni ◽  
...  

This paper describes the development phases of an annular type combustor for heavy-duty gas turbine applications. High cycle efficiency and low emissions are required over a wide range of load conditions, with the consequence of reducing margin to thermo-acoustic instability onset and lean blow-out. In addition, in lean premixed combustors, the increased fuel air mixing times required to keep emissions low, may lead to undesired ignition or flashback into the fuel burner ducts. All these aspects are matter of this work and focus is on fuel burner design modifications which allowed dry emissions reduction while maintaining a sufficiently wide safe operation window. A synergic effort has been put in place, involving experimental campaigns and CFD simulations, with the purpose of assessing design changes initially and doing screening. In the meanwhile, numerical practices have taken benefits form the experience growth. Results of past work on similar components has been leveraged too. Test campaign involved different scale facilities, from single burner through full annular combustor up to full scale prototype engine. The progressive reduction of viable option for combustor components design changes, due to high impact of such modifications during the gas turbine late development phases, forced designers to concentrate efforts onto fuel burner optimization, looking for efficient ways to implement modifications and assess their effectiveness of combustion system performances. Emissions trends, blow-out and flashback margin for several burner designs are reported. Numerical analysis results are also shown, which revealed to be well aligned with the experimental outcomes, allowing burner optimized solution to be identified. Finally, characterization with respect to fuel gas composition is shown as well as sensitivity to different operating conditions.


2011 ◽  
Vol 84-85 ◽  
pp. 259-263
Author(s):  
Xun Liu ◽  
Song Tao Wang ◽  
Xun Zhou ◽  
Guo Tai Feng

In this paper, the trailing edge film cooling flow field of a heavy duty gas turbine cascade has been studied by central difference scheme and multi-block grid technique. The research is based on the three-dimensional N-S equation solver. By way of analysis of the temperature field, the distribution of profile pressure, and the distribution of film-cooling adiabatic effectiveness in the region of trailing edge with different cool air injection mass and different angles, it is found that the impact on the film-cooling adiabatic effectiveness is slightly by changing the injection mass. The distribution of profile pressure dropped intensely at the pressure side near the injection holes line with the large mass cooling air. The cooling effect is good in the region of trailing edge while the injection air is along the direction of stream.


Author(s):  
Tim Lieuwen ◽  
Vince McDonell ◽  
Eric Petersen ◽  
Domenic Santavicca

This paper addresses the impact of fuel composition on the operability of lean premixed gas turbine combustors. This is an issue of current importance due to variability in the composition of natural gas fuel supplies and interest in the use of syngas fuels. Of particular concern is the effect of fuel composition on combustor blowout, flashback, dynamic stability, and autoignition. This paper reviews available results and current understanding of the effects of fuel composition on the operability of lean premixed combustors. It summarizes the underlying processes that must be considered when evaluating how a given combustor’s operability will be affected as fuel composition is varied.


Author(s):  
O. R. Schmoch ◽  
B. Deblon

The peripheral speeds of the rotors of large heavy-duty gas turbines have reached levels which place extremely high demands on material strength properties. The particular requirements of gas turbine rotors, as a result of the cycle, operating conditions and the ensuing overall concepts, have led different gas turbine manufacturers to produce special structural designs to resolve these problems. In this connection, a report is given here on a gas turbine rotor consisting of separate discs which are held together by a center bolt and mutually centered by radial serrations in a manner permitting expansion and contraction in response to temperature changges. In particular, the experience gained in the manufacture, operation and servicing are discussed.


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