Firing Low Viscosity Liquid Fuels in Heavy Duty Gas Turbines

Author(s):  
Jean-Pierre Stalder ◽  
Phil Roberts

Sustained economic growth has created a strong demand for electrical energy worldwide. Security of fuel supply and cost are therefore very often critical issues for thermal capacity additions. Also the distance from fuel sources and available fuel transport infrastructure is an important factor in the cost of generation. Many plant locations have only limited supplies of conventional gas turbine fuels, namely natural gas and distillate fuels, thus a drive to diversify the fuels involved. For other electricity producers, the optimal use of existing or potential fuel resources is a must for economical reasons. Therefore, the possibility of using alternative gas turbine liquid fuels, such as volatile and/or low viscosity fuels like naphtha, gas condensates, kerosene, methanol, ethanol, or low lubricity distillate fuels; refinery by-products such as BTX fuels (benzene-toluene-xylene mixtures), LCO-light cycle oil, or in the future synthetic fuels (GTL) are particularly interesting for their ability to be fired in heavy duty gas turbines. However, the practical use of these fuels creates specific issues such as low lubricity properties which can affect sensitive key components like fuel pumps and flow dividers. This paper addresses the many practical aspects of using fuel lubricity additives for reduced component wear in gas turbine fuel systems, and for reliability and successful plant operation on these alternative gas turbine liquid fuels. Also an overview of acquired experience is given.

Author(s):  
M. Molière ◽  
F. Geiger ◽  
E. Deramond ◽  
T. Becker

While natural gas is achieving unrivalled penetration in the power generation sector, especially in gas-turbine combined cycles (CCGT), an increasing number of alternative fuels are in a position to take up the ground left vacant by this major primary energy. In particular, within the thriving family of liquid fuels, the class of volatile products opens interesting prospects for clean and efficient power generation in CCGT plants. Therefore, it has become a necessity for the gas turbine industry to extensively evaluate such new fuel candidates, among which: naphtha’s; kerosines; gas condensates; Natural Gas Liquids (NGL) and alcohols are the most prominent representatives. From a technical standpoint, the success of such projects requires both a careful approach to several specific issues (eg: fuel handling & storage, operation safety) and a clear identification of technological limits. For instance, while the purity of gas condensates meets the requirements of heavy-duty technologies, it generally appears unsuitable for aeroderivative machines. This paper offers a succinct but comprehensive technical approach and overviews some experience acquired in this area with heavy duty gas turbines. Its aim is to inform gas turbine users/engineers and project developers who envisage volatile fuels as alternative primary energies in gas turbine plants.


Author(s):  
Robert E. Dundas

This paper opens with a discussion of the various mechanisms of cracking and fracture encountered in gas turbine failures, and discusses the use of metallographic examination of crack and fracture surfaces. The various types of materials used in the major components of heavy-duty industrial and aeroderivative gas turbines are tabulated. A collection of macroscopic and microscopic fractographs of the various mechanisms of failure in gas turbine components is then presented for reference in failure investigation. A discussion of compressor damage due to surge, as well as some overall observations on component failures, follows. Finally, a listing of the most likely types of failure of the various major components is given.


Author(s):  
Bernhard Ćosić ◽  
Frank Reiss ◽  
Marc Blümer ◽  
Christian Frekers ◽  
Franklin Genin ◽  
...  

Abstract Industrial gas turbines like the MGT6000 are often operated as power supply or as mechanical drives. In these applications, liquid fuels like 'Diesel Fuel No.2' can be used either as main fuel or as backup fuel if natural gas is not reliably available. The MAN Gas Turbines (MGT) operate with the Advanced Can Combustion (ACC) system, which is capable of ultra-low NOx emissions for gaseous fuels. This system has been further developed to provide dry dual fuel capability. In the present paper, we describe the design and detailed experimental validation process of the liquid fuel injection, and its integration into the gas turbine package. A central lance with an integrated two-stage nozzle is employed as a liquid pilot stage, enabling ignition and start-up of the engine on liquid fuel only. The pilot stage is continuously operated, whereas the bulk of the liquid fuel is injected through the premixed combustor stage. The premixed stage comprises a set of four decentralized nozzles based on fluidic oscillator atomizers, wherein atomization of the liquid fuel is achieved through self-induced oscillations. We present results illustrating the spray, hydrodynamic, and emission performance of the injectors. Extensive testing of the burner at atmospheric and full load high-pressure conditions has been performed, before verification within full engine tests. We show the design of the fuel supply and distribution system. Finally, we discuss the integration of the dual fuel system into the standard gas turbine package of the MGT6000.


Author(s):  
Thomas Palmé ◽  
Francois Liard ◽  
Dan Cameron

Due to their complex physics, accurate modeling of modern heavy duty gas turbines can be both challenging and time consuming. For online performance monitoring, the purpose of modeling is to predict operational parameters to assess the current performance and identify any possible deviation between the model’s expected performance parameters and the actual performance. In this paper, a method is presented to tune a physical model to a specific gas turbine by applying a data-driven approach to correct for the differences between the real gas turbine operation and the performance model prediction of the same. The first step in this process is to generate a surrogate model of the 1st principle performance model through the use of a neural network. A second “correction model” is then developed from selected operational data to correct the differences between the surrogate model and the real gas turbine. This corrects for the inaccuracies between the performance model and the real operation. The methodology is described and the results from its application to a heavy duty gas turbine are presented in this paper.


Author(s):  
Wolfgang Kappis ◽  
Stefan Florjancic ◽  
Uwe Ruedel

Market requirements for the heavy duty gas turbine power generation business have significantly changed over the last few years. With high gas prices in former times, all users have been mainly focusing on efficiency in addition to overall life cycle costs. Today individual countries see different requirements, which is easily explainable picking three typical trends. In the United States, with the exploitation of shale gas, gas prices are at a very low level. Hence, many gas turbines are used as base load engines, i.e. nearly constant loads for extended times. For these engines reliability is of main importance and efficiency somewhat less. In Japan gas prices are extremely high, and therefore the need for efficiency is significantly higher. Due to the challenge to partly replace nuclear plants, these engines as well are mainly intended for base load operation. In Europe, with the mid and long term carbon reduction strategy, heavy duty gas turbines is mainly used to compensate for intermittent renewable power generation. As a consequence, very high cyclic operation including fast and reliable start-up, very high loading gradients, including frequency response, and extended minimum and maximum operating ranges are required. Additionally, there are other features that are frequently requested. Fuel flexibility is a major demand, reaching from fuels of lower purity, i.e. with higher carbon (C2+), content up to possible combustion of gases generated by electrolysis (H2). Lifecycle optimization, as another important request, relies on new technologies for reconditioning, lifetime monitoring, and improved lifetime prediction methods. Out of Alstom’s recent research and development activities the following items are specifically addressed in this paper. Thermodynamic engine modelling and associated tasks are discussed, as well as the improvement and introduction of new operating concepts. Furthermore extended applications of design methodologies are shown. An additional focus is set ono improve emission behaviour understanding and increased fuel flexibility. Finally, some applications of the new technologies in Alstom products are given, indicating the focus on market requirements and customer care.


1974 ◽  
Author(s):  
Marv Weiss

A unique method for silencing heavy-duty gas turbines is described. The Switchback exhaust silencer which utilizes no conventional parallel baffles has at operating conditions measured attenuation values from 20 dB at 63 Hz to 45 dB at higher frequencies. Acoustic testing and analyses at both ambient and operating conditions are discussed.


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.


Author(s):  
A. O. White

This paper covers the early experience of the author’s company in burning residual oils in their gas turbines and the problems that occurred. The laboratory invesgations and field tests that resulted in a fuel processing system that permitted satisfactory operation on a wide range of liquid fuels are described. The operating experiences, where residual fuels were successfully burned in a large number of units, are described. The most recent operating experience with residual and crude oils and heavy distillates is also covered. A list of the various installations with dates and hours of operation is included and it is concluded that heavy duty gas turbines burning heavy fuels will be established as the up-to-date source of economical power in many applications.


Author(s):  
Vasco Mezzedimi ◽  
Pierluigi Nava ◽  
Dave Hamilla

The full mapping of a new gas turbine axial compressor at different speeds, IGV settings and pressure ratios (from choking to surge) has been performed utilizing a complete gas turbine with a suitable set of modifications. The main additions and modifications, necessary to transform the turbine into the Compressor Test Vehicle (CTV), are: - Compressor inlet throttling valve addition - Compressor discharge bleed valve addition - Turbine 1st stage nozzle area reduction - Starting engine change (increase in output and speed range). This method has been successfully employed on two different single shaft heavy-duty gas turbines (with a power rating of 11MW and 170 MW respectively). The paper describes the theoretical basis of this testing method and a specific application with the above mentioned 170 MW machine.


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