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Manufacturing Materials and Metallurgy

1984;():V005T11A001. doi:10.1115/84-GT-59.
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Many alloys are available to designers for seal ring applications in aircraft and industrial gas turbines. In this paper, the capabilities of a number of alloys are reviewed. Emphasis is placed on thermal expansion, density, environmental resistance, high-temperature strength, microstructural stability after exposure to elevated temperatures, weldability, and brazability. Among the alloys considered, the Ni-Cr-Mo HASTELLOY® alloy S offers a potentially useful combination of properties for seal ring applications.

Commentary by Dr. Valentin Fuster
1984;():V005T11A002. doi:10.1115/84-GT-67.
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Fiber metal abradable seals are used to control clearances in the compressor and turbine sections of gas turbine engines. Fiber metal seals are good abradables that rub by the low energy mechanism of brittle fiber fracture over a wide range of rub conditions. Rub mechanisms are significantly influenced by features in the seal microstructure.

High temperature fiber metal seals have been developed with temperature capability to 1650°F (1170 K). These seals have been characterized to determine abradability, mechanical properties, temperature resistance and permeability.

Topics: Metals , Fibers
Commentary by Dr. Valentin Fuster
1984;():V005T11A003. doi:10.1115/84-GT-70.
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A wrought, nickel-base superalloy based on the Ni-Cr-W system has been developed for applications in the hot section of gas turbine engines. The new alloy is solid solution strengthened and very thermally stable. It particularly resists the formation of detrimental intermetallic compounds and contains little or no cobalt. Various mechanical and oxidation properties of the new alloy were measured, and the microstructural features were characterized. These were compared with those for other solid solution strengthened, high-temperature alloys. A number of advantages of the new alloy are defined.

Commentary by Dr. Valentin Fuster
1984;():V005T11A004. doi:10.1115/84-GT-255.
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Corrosion processes in the compressor and turbine section of a gas turbine are basically different and are treated separately. The subject of this first paper is the compressor section.

Firstly, the conditions controlling the corrosion behaviour in the compressor are considered. Next the different forms of corrosion in compressors and the various methods to combat these corrosion processes are considered. Special attention is paid to:

•rinsing and washing

•the properties of protective coatings with regard to corrosion and erosion.

Corrosion processes in the turbine section are discussed in part II.

Commentary by Dr. Valentin Fuster
1984;():V005T11A005. doi:10.1115/84-GT-256.
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The phenomenology of the corrosion processes in the turbine section, including the conditions which govern corrosion behaviour, like temperature, pressure, fuel quality and presence of sulphur are discussed.

Various methods to combat the corrosion attack are described: limits to be imposed on fuel and intake air impurities, the use of fuel additives, and the application of corrosion resistant materials and coatings. The background to and the merits of these methods are discussed.

Furthermore service experience with current and advanced coating systems in marine, industrial and aircraft gas turbines is reported.

Corrosion processes in the compressor section are discussed in part I.

Commentary by Dr. Valentin Fuster
1984;():V005T11A006. doi:10.1115/84-GT-276.
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Machining of aero-gas turbine components made of titanium alloys, using different combination of tools, cutting fluids and machining parameters revealed two important characteristics namely, chemical reactivity and dimensional growth. The former is pronounced when machined with carbide tools using Sulphur based cutting oils. The reactivity was not noticeable when machined either with CBN or ceremet tools, contrary to the reports in the literature. This mechanism of chemical reaction has been studied including the development of microcracks at 400°F. The other phenomenon of dimensional growth is also anlysed in detail and machining parameters to reduce this growth are arrived at. The heat treatment is also envisaged to help in depriving of this detrimental dimensional growth by relieving the machining stresses. Also the scope for further research in this area is clearly defined.

Commentary by Dr. Valentin Fuster
1984;():V005T11A007. doi:10.1115/84-GT-277.
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Severe hot corrosion of gas turbine blades and vanes can result from the use of fuels contaminated with sodium and sulfur. A program has been initiated to survey currently available commercial as well as advanced developmental hot corrosion resistant coatings and select a list of coatings for application to Solar Centaur first-stage blades and vanes. A subsequent engine test program will be run on high-sulfur marine diesel fuel doped with sodium to produce severe hot corrosion conditions. The coatings will be tested in a rainbow fashion for a period up to 15,000 hours.

Commentary by Dr. Valentin Fuster
1984;():V005T11A009. doi:10.1115/84-GT-289.
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Alumina containing 3% TiO2, Y2O2 (13%)-stabilized zirconia and zirconia (13% Y2O3)-molybdenum powder mixtures (70:30 and 30:70) were sprayed by plasma unter standard conditions on several steel substrates. Intermediate nickelchromium metal layers were used. The adhesive strength of the coatings under static and dynamic stress, the thermal shock resistance were tested as well as wear and corrosion resistance, porosity and other properties of these oxide and oxide metal compound layers. Resistance against friction-abrasion, sometimes in combination with corrosion, can be controlled by pure oxide layers or, dependent on the kind of chemical reactions and mechanical behaviour by oxide molybdenum compounds. Some theoretical aspects of the behaviour of the tested coatings will be discussed.

Commentary by Dr. Valentin Fuster
1984;():V005T11A011. doi:10.1115/84-GT-297.
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For stationary gas turbine vanes IN 939 was evaluated very thoroughly in Europe as a promising hot corrosion resistant nickel base alloy.

This paper shows examples of properties and behavior of IN 939 from literature and from actual application in stationary gas turbines.

After long-term operation in stationary gas turbines vanes are analysed to show the type of oxide scale formation, the hot corrosion attack and phase stability. The alloy IN 939 exhibited excellent hot corrosion resistance under severe environmental conditions comparable to that of commercial hot corrosion protective coatings.

Phases are described developed after casting and during heat treatment and sensitivity towards M-phase formation is briefly discussed. Creep and fatique data of IN 939 are compared with IN 738 LC as well as the hot corrosion behavior.

Topics: Corrosion , Turbines
Commentary by Dr. Valentin Fuster

Ceramics

1984;():V005T12A001. doi:10.1115/84-GT-50.
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Metallic plate-and-fin recuperators for heat engine applications are one of the most expensive components of the engine because of the high temperature alloys required and the inherent expense of brazing or welding the individual plates. A highly compact, all-prime surface, internally manifolded, plate-and-fin ceramic recuperator has been developed to deliver equivalent high performance at reduced cost. Performance and economics of this unique recuperator are presented.

Topics: Ceramics , Engines
Commentary by Dr. Valentin Fuster
1984;():V005T12A002. doi:10.1115/84-GT-92.
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The properties, availability, and component experience of the Norton Company with high performance ceramics for heat engine applications will be reviewed. The monolithic systems SiC and Si3N4, as well as ZrO2 based coating systems will be described.

Commentary by Dr. Valentin Fuster
1984;():V005T12A003. doi:10.1115/84-GT-127.
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The Carborundum Company has been involved in the manufacture of alpha SiC for close to 100 years. The historical usage of this material has been as a coarse grain for the abrasive industry. Several Carborundum manufacturing plants are in existence worldwide and each has a capacity of approximately 40,000 tons/year of SiC powder produced by the Acheson process in which a graphite electrode is encased in a mixture of sand (SiO2) and coke. After the mass is heated to 4000°C and allowed to cool, the crystalline SiC grain is obtained directly (Figure 1). A milling and classification procedure is then employed to produce the desired grain sizes.

In 1975, researchers at Carborundum discovered a process for making high density, high strength monolithic shapes of alpha SiC(1). This involved using a submicron sized powder blended with sintering aids (boron and carbon). The mixture is green compacted and heated to above 2000°C under inert gas at atmospheric pressure. A solid state grain boundary diffusion process results in a densification process with an accompanying linear shrinkage of approximately 18%, to produce a body with 95–99% of theoretical density (3.21 gm/cc), and properties which are of interest for engineering applications. The pressureless sintering allows the formation of complex geometries by a net shape process without grinding, thus, creating the potential for the economical production of precision components in high volume.

Commentary by Dr. Valentin Fuster
1984;():V005T12A004. doi:10.1115/84-GT-165.
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In the field of diesel engine components, ceramic glow plugs assisting quick start up of chamber diesel engines had been developed in September, 1981 and ceramic swirl chambers followed in commercialization in April, 1983. These ceramic components are currently under commercial production and are installed on passenger cars on the merket.

Silicon nitride (Si3N4) is the material of these components, and a lot of mass-production technique has firmly established in order to achieve competitive price and high durability in comparison with the conventional metal components.

Because of its excellent heating characteristics, ceramic glow plugs have eliminated the “waiting time” before the start-up of diesel engines. As the result, drivers can enjoy quick starting of engines as they can do with gasoline fueled vehicles. Ceramic swirl chambers could drastically reduce idling noise of diesel engines and remarkably improved starting performance in the cold climate operation.

Topics: Ceramics , Engines
Commentary by Dr. Valentin Fuster
1984;():V005T12A005. doi:10.1115/84-GT-228.
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A status of GTE sintered silicon nitride for advanced heat engines will be presented. This will include an update of: sintering and final properties for a number of GTE silicon nitride compositions, microstructure, density, surface finish, strength, Weibull modulus, oxidation resistance, fracture toughness etc. The status of heat engine components fabricated by injection molding or isopressed/green machining and their performance will be reviewed along with correlations between the shape fabrication technique, strength, and Weibull modulus. Costs and availability will be included where possible. Future directions for increased reliability in silicon nitride structural ceramics will be summarized.

Commentary by Dr. Valentin Fuster
1984;():V005T12A006. doi:10.1115/84-GT-260.
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Material type, process technology and major properties for four ceramic components mass produced during the last three years are described. Table A-1 defines the components, material type and fabrication method. Table A-2 summarizes the density, bend strength, Weibull modulus and as fired dimensional tolerances. Production parts with flaws detectable by lox visual examination are not included in the tabulated data.

Commentary by Dr. Valentin Fuster

Structures and Dynamics

1984;():V005T13A003. doi:10.1115/84-GT-11.
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Squeeze film dampers are commonly applied to high speed rotating machinery, such as aircraft engines, to reduce vibration problems. The theory of hydrodynamic lubrication has been used for the design and modeling of dampers in rotor dynamic systems despite typical modified Reynolds numbers in applications between ten and fifty. Lubrication theory is strictly valid for Reynolds numbers much less than one, which means that fluid viscous forces are much greater than inertia forces. Theoretical papers which account for fluid inertia in squeeze films have predicted large discrepancies from lubrication theory, but these results have not found wide acceptance by workers in the gas turbine industry. Recently, experimental results on the behavior of rotor dynamic systems have been reported which strongly support the existence of large fluid inertia forces. In the present paper direct measurements of damper forces are presented for the first time. Reynolds numbers up to ten are obtained at eccentricity ratios 0.2 and 0.5. Lubrication theory underpredicts the measured forces by up to a factor of two (100% error). Qualitative agreement is found with predictions of earlier improved theories which include fluid inertia forces.

Commentary by Dr. Valentin Fuster
1984;():V005T13A008. doi:10.1115/84-GT-71.
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The torsional and lateral rotor dynamic analyses of most turbomachinery designs are usually conducted independently, however, for a certain class of turbomachinery, e.g., geared compressors, the torsional and lateral vibrations are coupled due to the offset centerlines of the geared rotors. This paper develops and verifies the appropriate coupling matrix. An analysis is then presented of a multistage, geared compressor showing the effects of coupling. Test data is also presented.

Topics: Rotors
Commentary by Dr. Valentin Fuster
1984;():V005T13A011. doi:10.1115/84-GT-99.
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Vibratory stress characteristics of the low pressure compressor in the Pratt & Whitney Aircraft PW1120 turbojet engine recently have been evaluated during full-scale engine testing at the United States Air Force’s Arnold Engineering Development Center. A description is presented of the approach used to evaluate the vibratory characteristics of the new three stage low pressure compressor. Results are presented showing the effects of simulated altitude conditions, inlet pressure distortion, and off-schedule variable vane operation. Strain gage data is compared to case-mounted light probe data, and the levels of system damping and mistuning are discussed. Predicted vibratory response is compared to test results showing the new compressor to be free of destructive vibration.

Commentary by Dr. Valentin Fuster
1984;():V005T13A012. doi:10.1115/84-GT-109.
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A parametric study of turbine blade platform friction damping has been performed using the lumped parameter analysis. The hardware configuration used in the analysis is the first stage turbine of the High Pressure Fuel Turbopump of the Space Shuttle Main Engine. The analysis procedure, developed over the last few years by A. Muszynska, now of Bently Nevada Corporation, and D.I.G. Jones, of AFWAL/MLLN, solves the nonlinear equations of motion of a turbine blade acted on by a platform friction damper by an iterative matrix method. The parametric study considers the effects on the blade deflection response of variations in: the coefficient of friction; the normal force on the friction surface interface; the blade hysteretic damping; the blade to blade phase angle of the harmonic forcing function; and the amplitude of the forcing function. The results of the study are applicable to any blade-damper system similar to the one used in the study. [Work sponsored by Marshall Space Flight Center of NASA.]

Commentary by Dr. Valentin Fuster
1984;():V005T13A013. doi:10.1115/84-GT-110.
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Since the Kongsberg KG5 gas turbine was introduced into service in 1977 these engines have accumulated more than 100 000 hours of field operation. Apart from an exducer blade vibration problem which was revealed and fixed prior to field introduction, no major operational problems have been encountered.

During test and commissioning of two larger orders, three separate incidents of turbine blade failure occurred, one in March 1982 and two in February 1983. The first incident triggered a number of investigative actions and the resulting conclusion was confirmed by the last two incidents.

The present paper describes the analytical and test methods employed in order to investigate this problem. The blade natural frequencies were determined analytically through a NASTRAN analysis and experimentally with a TV-Speckle Interferometer technique.

It is shown how the influence of an interference fit or dampening joint between the two rotor wheels was actually hiding the possible resonance condition during the initial qualification tests, and how the transient movements of this joint would allow resonance to occur under certain operational conditions.

The possible corrective modifications are discussed and the selected solution is shown. The test set up and the results from the verifying strain gauge test is presented.

Commentary by Dr. Valentin Fuster
1984;():V005T13A014. doi:10.1115/84-GT-136.
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The laser-Doppler, fibre-optic probe which has been developed at Cranfield and which can be used for the non-intrusive detection and measurement of mechanical vibration, has been improved optically and by the inclusion of a microprocessor system to replace the previously employed frequency tracker and Bragg cells. These improvements facilitate the manufacture of a laser-Doppler probe which is more compact and considerably cheaper than the previous version, and which has potential for the application of a wide range of signal processing techniques.

Topics: Lasers , Vibration , Probes
Commentary by Dr. Valentin Fuster
1984;():V005T13A021. doi:10.1115/84-GT-169.
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An analysis is developed that can be used to calculate the aeroelastic instabilities of labyrinth air seal systems. The formulation considers both the stator and rotor as flexible components and the fluid within the cavity has both axial and swirl components of velocity. The interaction of the leakage flow (through the clearance between lips of the seal and the stator) with the vibratory modes of the rotor and stator provides the mechanism for possible aeroelastic instability.

A limited parametric study shows that increasing the stiffness of either the rotor or the stator has the same stabilizing influence as including, in the analysis, swirl flow component of the leakage flow. Further, at frequencies where coincidence between stator and rotor modes occurs, there could be a sharp drop in available aerodynamic damping. These results, which need experimental confirmation, can influence the design of these important components of jet engines.

Commentary by Dr. Valentin Fuster

Controls, Diagnostics and Instrumentation

1984;():V005T14A002. doi:10.1115/84-GT-33.
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This paper presents a computer model called ‘TURBOTEST’ which is applicable both to analysis of gas turbine engine rig tests and to simulation of engine steady-state performance. As with the earlier ‘TURBOFLEXI’ model a wide range of gas turbine engines can be simulated, using any kind of hydrocarbon fuel, and allowing for chemical dissociation of the gas, and for the effect of air humidity.

In addition, however, for the particular requirements of rig test analysis, the following new features have been developed and incorporate:-

(a) It can carry out rig test analysis for a wide range of gas turbine engines if all the necessary test data are presented.

(b) If the test data is incomplete, a computer simulation of the engine can be used to complete the analysis.

(c) Performance deterioration of engine components can be detected by comparing the results of a test analysis and of a parallel simulation using stored characteristics of engine components in the “as new” condition.

The program has been tested on simulated test data generated by engine models such as a turbojet and a turbofan. The results show it has close and repeatable agreement with design values. Further tests of the model have been carried out by applying it to the actual engine rig test data.

Commentary by Dr. Valentin Fuster
1984;():V005T14A005. doi:10.1115/84-GT-220.
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For plants with multiple gas turbines, a second generation integrated plant condition monitoring and control system combines prime mover and driven load controls with process controls for the balance of plant. Projected applications include electric power generation, cogeneration, combined cycle plants, and gas compression plants. The system offers redundant distributed control, with diagnostics, repair, and return to original fault tolerance levels. This forms the basis for projections of high control availability. Two data highways drastically reduce plant wiring while improving availability of communications. Color graphic plots of any parameter can be displayed, along with analysis of the condition of the plant components. The system can interface with dispatching telemetery systems.

Commentary by Dr. Valentin Fuster

Education

1984;():V005T15A002. doi:10.1115/84-GT-226.
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A tandem ejector pumping system has been applied to an intermittent blowdown tunnel for cascade testing to achieve sub-atmospheric exit pressures and extend the operating range substantially. The ejectors are run from the same supply as the tunnel itself, but because they are only used at low Reynolds numbers when the cascade mass flow is small the overall running costs are kept low. A conventional one-dimensional ejector theory is developed in a new way for such an application as this, where the driving mass flow needs to be known for constant Mach number of the driven stream (the cascade exit Mach number). Several ejector geometries were tested in various configurations in a one-tenth scale model before the prototype ejectors were developed. It is demonstrated that by suitable grouping of terms it is possible to correlate both model and prototype ejector performance, and that this performance can be predicted sufficiently accurately by the theoretical model to justify its use as a design tool.

The method of operating two ejectors in tandem depends on the interaction of the exit stream of the first (forming the driven stream of the second) and the driver stream of the second. This is not immediately obvious, and is discussed fully in the light of the achieved performance.

Topics: Ejectors , Pumps , Tunnels
Commentary by Dr. Valentin Fuster
1984;():V005T15A003. doi:10.1115/84-GT-288.
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The advancement of aeropropulsion systems continues to provide technology to various portions of the gas turbine field. It is recognized that this area is undergoing considerable change, which will result in substantially improved gas turbine components and systems. These changes are occurring in a number of technical areas including advanced analytical and physical measurement methods, the application of large scientific computers, the dynamic modeling of components and systems, the application of integrated control systems that optimize and improve performance and system condition monitoring, and the development of new and unique materials and structures. As these areas evolve, the ways in which technology will advance, and factors affecting the design and development of new systems, will probably be considerably different than those of today. It is also anticipated that the necessary skilled work force will be different. Certainly there will be changes, but the nature, extent, and rate of those changes can only be surmised at this time.

Commentary by Dr. Valentin Fuster

Process Industries

1984;():V005T16A001. doi:10.1115/84-GT-111.
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Modern high capacity blast furnaces are generally operated at high values of back pressure at the top of the furnace (250÷400 kPa abs.). In order to recover this large quantity of pressure energy some turbine equipments have been recently developed. The possible solutions of these systems must take into account the clean up outcoming blast furnace gas conditions (cold and water saturated gas).

Up-to-date solution analysis has carried to three different main process types: wet expansion; dry expansion by partial burning of gas; dry expansion by gas heating in a heat exchanger.

This paper develops an energy based analysis for these equipments taking into account not only the recovery in the turbine unit, but also the effect of this equipment on the whole integrated system “blower - cowpers - blast furnace - gas turbine unit - power conversion station”.

A parametric analysis is performed and the obtained results are presented and discussed.

Commentary by Dr. Valentin Fuster
1984;():V005T16A002. doi:10.1115/84-GT-125.
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This paper describes the process of the integration of a cogeneration plant in a plastics manufacturing complex, which is being expanded.

It presents the background against which the decision to proceed was made, the alternatives considered, and some of the techniques utilized to obtain management approval.

It also describes the specific aspects of the cogeneration facility, fuels, heat recovery systems for thermal oil and medium pressure steam, the balancing between energy production and utilization in the complex and the control system for the optimization of the facility.

Also some energy typical aspects of connecting the generator to the public grid will be addressed.

Commentary by Dr. Valentin Fuster
1984;():V005T16A003. doi:10.1115/84-GT-126.
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Heat recovery boilers utilizing the exhaust from gas turbines continue to be viable as industrial cogeneration systems. This paper outlines the types of heat recovery boilers available for use with gas turbines (1–100 MW). It discusses the design and performance criteria for both unfired and supplementary fired gas turbine exhaust heat recovery boilers of single and multiple pressure levels. Equations to assist in energy balances are included along with design features of heat recovery system components. The economic incentive to achieve the maximum practical heat recovery versus the impact on boiler design and capital cost are examined and discussed. It is intended that the information presented in this paper will be of use to individuals who are not intimately familiar with gas turbine heat recovery systems so that they can better specify and evaluate potential systems.

Commentary by Dr. Valentin Fuster
1984;():V005T16A004. doi:10.1115/84-GT-131.
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In 1972 El Paso Products investigated the possibility of replacing their existing industrial gas generators with an alternative. These gas turbines provided a constant hot gas flow to the catalysts of their butadiene plant in Odessa Texas. This project demanded the highest reliability and offered some unique engineering challenges.

Topics: Design , Generators
Commentary by Dr. Valentin Fuster
1984;():V005T16A008. doi:10.1115/84-GT-161.
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This paper will describe a co-generation system using a conventional boiler or process heater and applying a gas turbine to provide preheated combustion air to the boiler or furnace.

A number of design considerations such as applicable type and size of the gas turbine, expected energy savings and control and safety aspects are discussed. These design considerations should be taken into account when retrofitting a conventional plant into a co-generation system.

The paper will also describe such a type of co-generation system with a process heater which is in operation at the Chevron/Texaco Refinery in The Netherlands.

Commentary by Dr. Valentin Fuster
1984;():V005T16A009. doi:10.1115/84-GT-206.
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An internal inspection of the expander after 16,000 hours of operation confirmed the successful operation of Ingersoll-Rand’s first two stage, high temperature, FCC expander. This paper discusses the construction and operation of the unit, designed for 1300°F (704°C) dirty gas environment and presents the inspection results of critical components.

Commentary by Dr. Valentin Fuster
1984;():V005T16A010. doi:10.1115/84-GT-223.
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This paper pertains specifically to refinery fluid catalytic cracking and associated power-recovery concepts. The several systems described go beyond basic onsite FCC practices previously used. However, no special technical development or prototypes would be required to engineer practical and successful installations. All component equipment and apparatus reflect current state-of-the-art, requiring only explicit economic justification.

The individual systems, as presented, are solely conceptual, but sufficient detail is provided to confirm their technical feasibility. Application economics will depend on geographic location, site conditions and the specific process installation.

Commentary by Dr. Valentin Fuster
1984;():V005T16A011. doi:10.1115/84-GT-224.
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This paper describes the importance of accurate calculation of thermal and electrical energy production by cogeneration plants on the overall validity of cogeneration projects. A new simple graphical method which improves the accuracy of calculation of annual thermal and electrical energy consumption and production by various energy sources is proposed. A practical example of developing annual load duration characteristic using the proposed method is provided. Several illustrative graphs are included.

Evaluating the feasibility of an energy conservation project normally involves comparing of the saved operating cost with the additional capital costs required to implement the project. Operating costs, which can also be called running costs, include energy costs and equipment operating and maintenance costs. Normally, energy costs represent a major part of the running costs and, therefore, are the major factors affecting the overall profitability of the project. It almost goes without saying that an economic analysis of an energy conservation project is much more sensitive to the variations in the cost of energy than to changes in the capital costs. It is quite common that a 10 percent change in the energy cost can produce dramatic economic changes, while the same or a much larger change in the capital cost often has only a marginal effect on the economics.

Commentary by Dr. Valentin Fuster
1984;():V005T16A012. doi:10.1115/84-GT-258.
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The Britalus Engine concept under development by Combustion Research & Technology, Inc. (CR&Ti) is a gas turbine-like Brayton cycle engine whose physical characteristic is that a unique design is used for the compressor and the expander. These components achieve their function by positive displacement wherein pistons located within a rotor are forced to execute simple harmonic motion through bearing contact with an outer three-lobed cam. It is shown that this arrangement has the advantage that practical designs for engine sizes ranging from as small as 10 kw to 1000 kw with steady combustion are possible. The high compression and expansion efficiencies of these components incorporated in a simple high pressure ratio cycle allow contemplation of the design of light, rugged and efficient engines for a wide variety of applications. A realistic evaluation of a new engine requires identification and magnitude determination of the performance limiting loss mechanisms and an understanding of the means for power control. This paper is a description of the compressor and expander components, and the means used for cycle pressure variation by modification of the compressor geometry. The part-load characteristics of the engine and the impact of the requirement for part-load operation on the engine design are described.

Commentary by Dr. Valentin Fuster
1984;():V005T16A013. doi:10.1115/84-GT-275.
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On basis of ISO-Standard 2314, the German Standard Organisation (DIN) has prepared the German Standard DIN 4341, which deals with acceptance tests for gas turbines. Sample calculations have been included.

In connection with the development of the sample calculations a new diagram for thermodynamic properties of air and products of combustion was developed on basis of

-humid air as per ISO standard 2314

-standard gaseous fuel

-standard liquid fuel

This diagram allows exact calculation of performance data.

Further, a simplified but relatively acurate formula is presented for calculating the turbine inlet temperature on basis of

-compressor pressure ratio

-exhaust gas temperature

-thermal efficiency

Development and limitation of this formula is presented.

Topics: Gas turbines
Commentary by Dr. Valentin Fuster

Technology Resources

1984;():V005T17A001. doi:10.1115/84-GT-123.
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Mass steam injection into the combustor of a Cheng Cycle turbine can influence combustion characteristics and pollutant formation.

When using a Cheng Cycle system based on a Garrett 831 gas turbine liquid fuel, these influences were studied experimentally. Data obtained to date indicate that significant NOx reduction can be achieved without suffering combustion inefficiency or instability.

Commentary by Dr. Valentin Fuster
1984;():V005T17A003. doi:10.1115/84-GT-214.
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Oil provides several functions in the circulating system of a gas turbine-centrifugal compressor. It cools, dampens, flushes, lubricates, resists corrosion, seals, and transmits power. Uncontrolled accumulation of contaminants in the oil can impair these functions, can cause excessive wear, deterioration, malfunction, and failure of system components, and can create safety hazards for the equipment and its environment.

Commentary by Dr. Valentin Fuster

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