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A thorough understanding of the auto-ignition process is critical to the success of lean premixed prevapourised (LPP) combustors for future ultra-low NOx emissions gas turbines. A considerable amount of work has been done in the past on auto-ignition delay time (ADT) measurements for various aviation fuels and hydrocarbons. However, little was known about the influence of various possible fuel additives on ADT. A test rig was designed and built by DERA specifically for ADT measurements. It consisted of an injector housing and an instrumented duct where the ignition location could be monitored by fibre optic sensors. It was intended to acquire ADT measurements at 875K, 16bar and 40m/s of mean flow. The test rig and instrumentation were commissioned in January and February 2000. However, instrumentation inside the injector housing was damaged soon after the initial hot run as a result of overheating. Attempts were made to repair the damaged components and to identify the cause of overheating. Unfortunately, the damage to the components was extensive and the cause of overheating could not be diagnosed. In view of the technical risks involved, it was decided to stop further testing with this rig. Although ADT measurements could not be undertaken as planned, useful operating experience was gained from the tests conducted.Copyright © 2001 by ASME

The performance assessment of power plants is a complex task, which involves many calculations. Increasing the number of plant components with the introduction of new technologies available in the international market, it increases the complexity of performance analysis of power cycles. The present paper describes a process for optimising a conventional gas turbine combined cycle power plant. In this paper the method of assessing thermal power plants takes into account the exergy method and carries out along with optimisation of the whole plant based on maximising overall plant exergetic efficiency and minimising energy loss rejected to the atmosphere. The performance assessment of power plants using the exergy method considers the overall plant exergetic efficiency and the exergy destruction in the various components of the plant. The exergy method highlights irreversibility within the plant components, and it is of particular interest in this investigation. Due to the large number of equations with many variables taking part in the whole calculation and also considering constraints imposed to some variables, a genetic algorithm is recommended as the optimisation tool for the assessment method. Genetic Algorithms are adaptive methods which may be used to solve search and optimisation problems. They are based on the genetic processes of biological organisms. Over many generations, natural populations evolve according to the principles of natural selection and “survival of the fittest”, first clearly stated by Charles Darwin in his book “The Origin of Species”. Genetic algorithms do not require complicate mathematical calculations like the evaluation of derivatives necessary to be considered in conventional optimisation techniques.

This paper presents the progress made on the development of a dual spray, direct injection airblast fuel nozzle capable of variable fuel placement. It is anticipated that by varying the fuel placement within the confines of a combustion chamber it will be possible to control localised flame ‘Fuel Air Ratio’ and thus extend both stability and emissions performance in respect of engine power range. The extension of combustion stability is particularly desirable to high pressure, temperature and turndown ratio aero engines where the ratio between maximum and flight idle fuel flows is extreme. Atomiser aerodynamics have been developed that produce two different airflow re-circulating regions within the combustor. A concentric fuel filmer feeds each of these regions. By staging the fuel into each flame re-circulation zone the variation of local ‘Fuel Air Ratio’ can be more accurately controlled. A combination of bench testing and CFD has been used to analyse and manipulate airflow distribution between swirlers to form the two distinct flame regions. The work is ultimately concerned with the rationalisation of airflow distribution and fuel placement to best fit the operational envelope of the engine. The variable placement fuel injector features three or more air swirlers (inner swirler, middle swirler and dome swirler) and two ‘airblast’ fuel filmers (pilot and main). The paper describes the progress made with a number of fuel injector configurations.

Combustion oscillations are a serious technical challenge for stationary gas turbine manufacturers. In order to address this issue, the development cycle for a gas turbine combustor typically involves an extensive test program. In many cases, the dynamic stability observed in sub-scale test rigs differs from the commercial engines. If encountered late in the development cycle, these rig-to-engine variations can impact an entire engine program. This paper discusses an experimental approach to measure time-scales (i.e., fuel-transport time and flame response time) that play a critical role in combustion oscillations. If these time-scales can be measured throughout the development cycle, the rig-to-engine variations in combustor performance may be improved. The results described in this paper are collected from a nominal 1MWth single-can combustor rig operating on natural gas. The inlet-air temperature and pressure are 589K (600°F) and 760 kPa (7.5 atm), respectively. The measured time-scales are significantly larger than the bulk fuel-transport time calculated from simple estimates. In order to explain these discrepancies, a simple flame model is presented to show how the flame structure can influence these time-scales. This model is also used to illustrate how these critical time-scales can change as a function of operating condition.Copyright © 2001 by ASME

Combustion oscillations (dynamics) have become a major challenge in the development of low-emission premix combustors. Numerous recent papers have considered the various mechanisms that drive oscillations, as well as acoustic features of the combustor and fuel system that participate in sustaining unwanted oscillations. The acoustic transfer matrix technique has been used in a number of recent analyses of both the combustion and fuel injection process. In this paper, the transfer matrix analysis is combined with a reduced order model of the fuel supply to calculate the magnitude and phase of the fuel system response to imposed pressure perturbations. The analysis is used to determine if a variable geometry resonator in the fuel system can be used to adjust the phase and gain of the fuel response to enhance stability. Experimental data recorded in a research premix fuel injector show that the reduced order model accurately describes the dynamic response of the fuel entering the premix passage. Using measured acoustic properties it is also shown that the variable geometry resonator studied here can produce a phase response for fuel delivery over a range of 70 degrees, with appreciable modulation of the main fuel flow. It is suggested that this variable phase response could be used to adjust the stability properties of a given combustor.Copyright © 2001 by ASME

This paper is the first of two parts that describes an advanced CFD-based analysis system, developed at Pratt & Whitney, which has been used to optimize the PW6000 combustor exit temperature distribution. It utilizes a CFD calculation through the entire combustor domain to predict temperature distribution at the combustor exit. In this part, all components of the analysis system are presented, including the CAD and grid generation approach used to represent the complex combustor geometry, the core CFD solver, the Lagrangian fuel spray model, and the combustion model. In addition, the predictive capability of the system is established by comparing calculated exit temperature profiles to full annular rig test data for three aircraft gas turbine engine combustors: PW4090, PW4098, and a low-emissions technology development combustor. Comparisons of combustor airflow distribution and pressure drop are also presented to verify the accuracy of the tool. The paper demonstrates that the CFD-based analysis system is capable of calculating exit temperature distribution for a range of combustor configurations, and thus can be utilized as a predictive design tool. Part II demonstrates this predictive capability by applying the analysis tool to optimize the PW6000 combustor exit temperature distribution for turbine durability and life. Copyright © 2001 by ASME.

Conventional maintenance schedules and scheduling techniques are typically based on the manufacturer’s guidelines and applied to all engines of a certain make and model. This approach does not always address the specific operating environment and requirements for each operator. An alternative to this conventional “one schedule suits all” approach is the Component Management Program described in the paper. This type of program is designed to tailor maintenance requirements to suit the specific operating environment of the operator’s engine or fleet of engines. The program is intended to extend and optimize maintenance intervals and at the same time ensure reliability of the components. The paper outlines the metallurgical analysis and other techniques that are incorporated into a Component Management Program, the tracking systems used to schedule maintenance, and some case studies where these programs have been used to extend component life and reliability.

The nutating engine is a new type of internal combustion engine with distinct advantages over conventional piston engines and gas turbines in small power ranges. The engine’s unique arrangement flexibility allows several alternative disk and shaft configurations, each selected for a different application. Variations in cycle temperature ratio and compression ratio during normal operation enable the engine to effectively become a variable-cycle engine, allowing significant flexibility for maximum efficiency or power or other optimizing function for on-ground stationary or for airborne applications. In its basic configuration the core of the engine is a nutating non-rotating disk, with the center of its hub mounted in the middle of a Z-shaped shaft. The two ends of the shaft rotate, while the disk “nutates”, performs a wobbling motion without rotating around its axis. The motion of the disk circumference prescribes a portion of a sphere. A portion of the area of the disk is used for intake and compression, a portion is used to seal against a center casing, and the remaining portion is used for expansion and exhaust. The compressed air is admitted to an external accumulator, and then into an external combustion chamber before it is admitted to the power side of the disk. A companion paper examines the performance potential of the one-disk engine. This paper examines alternative engine configurations. The external combustion chamber enables the engine to operate on a variable compression ratio cycle. In addition, separate disks of unequal size are used for intake and expansion, resulting in distinct and significant power, efficiency, fuel flexibility, and arrangement advantages over conventional piston engines, over gas turbines, and over the basic nutating-engine configuration. The performance of these arrangements is examined for: on-ground power, on ground efficiency, (auxiliary power, automotive); and for small and light airframe applications for flight Mach numbers from 0 to 1 and altitudes from 0 to 20 km. This publication is the original presentation of the performance potential of several alternative configurations of the basic engine, such as multi-disk arrangements, combustion and exhaust disks of different size, and variable-compression ratio (variable cycle) configurations.Copyright © 2001 by ASME

Pratt & Whitney is developing a 107 kN (24,000 pound) thrust PW6000 engine for the 100-seat aircraft market. The combustor for this engine has been designed by combining the TALON emissions concept demonstrated on the PW4000 engine family with an advanced CFD-based analysis system to optimize the combustor exit temperature distribution. The design objective is to provide a low cost highly reliable engine, which produces low emissions. This paper is the second of two parts, which describe an advanced CFD-based analysis system used to optimize the combustor exit temperature distribution for turbine life. The analysis system applied the identical Allstar solver, which is described and validated in part I, to the PW6000 combustor. All calculations in this paper were completely predictive in nature. The effect of dilution hole pattern changes on the exit temperature profile was determined by solving the flowfield from the prediffuser inlet to the combustor exit. Results from the study were used to understand the physical processes taking place inside the prediffuser and combustor that impact the exit temperature profile and from this understanding a hole pattern configuration was identified. Full annular rig measurements of the pressure drop and airflow distribution throughout the model along with exit temperature profile measurements agreed very well with CFD predictions. A second target exit temperature profile was defined based upon engine testing and the analysis tool demonstrated the ability to define a second dilution hole pattern that met the target profile to optimize turbine life. An annular rig test again confirmed the CFD predictions. Parametric studies were also performed on the prediffuser inlet pressure profile to predict how the turbine inlet temperature profile would change. These studies were used to desensitize the combustor temperature profile to prediffuser inlet profile changes that may occur over the life of the engine. The predictive capability of this CFD-based analysis tool has significantly reduced experimental development costs and has optimized the combustor exit temperature profile to meet PW6000 design objectives.

This paper describes a computer program simulation of the impact of noise emissions of Austrian’s largest gas compressor plant. The case history covers a multi-source compressor plant containing LM 2500 and frame 3 gas turbines as well as the noise emissions of gas-air coolers and dehydration equipment. The paper outlines further how potentials of noise reduction can be identified and how the noise impact of future projects can be simulated with the help of a computerized model.Copyright © 2001 by ASME

In this paper a high efficiency and flexible hybrid system representing a new total energy concept for the distributed power market is presented. The hybrid system is composed of a very small size (5 kW) micro gas turbine (named personal turbine – PT) presented in a companion paper by the authors (McDonald and Rodgers, 2001) coupled to a small size Solid Oxide Fuel Cell (SOFC) stack. The power of the whole system is 36 kW depending on the design parameters assumed for the stack. The design and off design performance of the hybrid system have been obtained through the use of an appropriate modular code named “HS-SOFC” developed at the University of Genoa (Magistri, 1999) and described in detail in this paper. The results of the simulation are presented and discussed with particular regards to: choice of the Hybrid System (HS) design point data, HS design point performance, off design performance of PT and SOFC stack, off design performance of the whole HS. Some preliminary economic results are also included based on different fuel and capital cost scenarios and using the cost of electricity as the parameter for comparison between PT and HS.

The paper deals with the set-up and preliminary test-planning of an innovative mini cogeneration plant, in which exhaust gases coming from a 45 kWe rated turbogenerator directly feed an absorption chiller / heater with a 170 kWth chilling and a 160 kWth heating capability. Electric power is partly used on site to satisfy the plant auxiliary systems power demands and partly vectorised to the main building of the Engineering Faculty (15 km from the plant site) through the main electric grid. Thermal power is exploited locally for any season air conditioning of laboratory rooms. The paper describes the plant layout and the technical solutions adopted for installation and diagnostic purposes. This plant has been conceived even as a test-bed for Remote Monitoring (RM) and Plant Condition Monitoring (PCM) techniques development and testing. To this purpose dedicated diagnostics have been set up and mathematical models of all the main components are being developed to perform the identification of their operational parameters (e.g. efficiencies) on the basis of the acquired parameters. These are aimed at obtaining both a correct management of the plant and an early diagnosis of malfunctions to achieve the ability of following an on-condition maintenance philosophy to reduce maintenance costs and outage periods.

The intention of this paper is to offer a general description of the Molten Carbonate Fuel Cell (MCFC), its performance parameters, and the work done on the integration of MCFCs and gas turbines into an hybrid cycle to achieve high efficiencies. The paper describes results obtained for several hybrid configurations, some of them using pressurised MCFCs, others using atmospheric pressure MCFCs. Each configuration is analysed for different values of the cycle parameters, as part of the optimization process done to find an optimum solution. Finally, some conclusions are presented. An important part of the work corresponds to the development of the code MC-GreenCell that simulates the performance of MCFC. This code, developed by the authors, estimates power, voltage, electrical current densities, heat losses, temperatures, gases flow rates and compositions, resulting from the steam reformer and from the MCFC stack. The code was utilized together with a commercial code on the assessment of the design point performance of the hybrid system. In the future the code will be used to evaluate the off-design performance of the cycle. The code has been validated using MCFC field data available from current projects. The study focuses on hybrid cycles of 1÷25 megawatt size that may be used in commercial or industrial cogeneration, distributed power generation for hospitals, public buildings, etc.

In this paper an existing cogeneration plant (134 MWel and 225 MWth) based on gas turbine and steam cycle technology, has been investigated. The main goal of the work is to analyse different repowering options for the plant taking into account the capital cost of the new devices, the cost of the fuel and the cost related to the CO2 emissions. For the analysis of the repowering alternatives the Thermoeconomic Analysis has been utilised. Two different approaches have been used for the CO2 emissions cost evaluation: the classical Carbon Tax approach using political charges on the unit ton of emitted CO2, and one proposed by the Authors linked to the efficient utilization of energy resources in the plants, and based on the exergy analysis. In the paper the two procedures for the evaluation of the charges on the CO2 emissions and their influence on the choice of the repowering option, and how they promote the adoption of a high efficiency repowering solutions have been discussed.

Amongst the available alternatives of regenerative energy sources, biomass may play an important role in the future. Biomass represents stored solar energy, accessible whenever there is demand. But so far, its large potential has only been used to a small extent. This is partly due to the fact that solid biomass is a common fuel for the production of heat, but is hardly used in combined heat and power (CHP) plants. For the conversion of solid fuels, combustion in combination with a Rankine cycle is the only well established technology available today, thus acceptable net efficiencies (> 25% LHV) are only possible in complex, rather large scale plants. However, since the occurrence of biomass differs depending on region and season, and because of its low energy density and thus reduced transportability, biomass is particularly suited for decentralized applications, i.e. for the generation of heat and power (1) in the small power range. This paper discusses strategies for the integration of biomass gasification / pyrolysis and gas cleaning processes into different gas turbine schemes. Rather than reviewing all possible aspects of and concepts for the usage of biomass in gas turbine applications, this paper evaluates some key aspects (pressurization, tar removal, gas cleaning, choice of gas turbine cycle) of directly fired gas turbine concepts with regard to small scale applications. The paper shows that tar is a key problem. Especially for small scale applications solutions based on the combustion of tars, like pressurized biomass conversion in combination with hot gas cleaning, prove to be simple and efficient. This paper also compares the characteristics of integrated gasification cycles, e.g. by demonstrating difficulties connected with the integration of steam blown allothermal gasification (reforming). Furthermore, it is shown that recuperated gas turbines are well suited for highly efficient, yet simple small scale applications. Test results indicate that “mild” pyrolysis is an alternative technology for the production of comparatively clean medium heating value gases. Integrating the use of pyrolysis gas and charcoal into a simple gas turbine plant, however, can not easily be achieved.

This paper examines a Biomass Integrated Gasification Combined Cycle (BIGCC) CHP plant using atmospheric air-blown gasification with wet cold gas clean-up and flue gas drying of the biomass feed stream. The plant provides heat and power to a medium sized municipality. The paper presents simulated performance results obtained using GateCycle software, and also presents results for the associated economy and CO2 emissions of the district heating system. The computed production costs of the cogenerated electricity are uncompetitively high, given current conditions in Sweden. In order to become competitive, international consensus must be reached on the level of economic advantage to be attributed to the “green” electric power produced by such a plant. However, likely price incentives for “green” power will probably be insufficient for BIGCC-CHP plants to become economically attractive. Therefore further effort is needed to improve the technology, reduce the investment costs, and identify options for longer annual operating times than those usually adopted for CHP plants coupled to district heating plants.Copyright © 2000 by ASME

It is often desirable to measure the sound power radiated by the inlet or exhaust of a gas turbine in an installation that includes filters and silencers. A direct measurement can only be accomplished within the empty duct between the inlet or exhaust flange and the silencer. For a number of reasons ISO 5136 [1] cannot be used directly to perform these measurements. Consequently, some other means must be found. The primary requirement for an in-duct sound power measurement is a valid in-duct sound pressure measurement. In order to accomplish this, the effect of the turbulent pressure fluctuations inherent in the flow, or induced by the microphone probes, must be removed from the dynamic pressure signals sensed by the microphone. This paper describes the use of a two-microphone cross amplitude spectrum (CAS) technique to perform accurate measurements of the autospectra of sound fields embedded in turbulent duct flows. This technique is based on the assumption that the acoustic and turbulence signals detected by any microphone are uncorrelated with each other and also with the turbulence signals detected by another microphone. The paper gives the measurement parameters required for various degrees of turbulence rejection as well as the accuracy and convergence of the estimate of the embedded acoustic spectrum. The paper also provides a means to determine the microphone separation distance required to ensure that the turbulence signals at the two microphones are uncorrelated. These results are based on both the simulation of acoustic fields embedded in turbulence and on laboratory experiments using both loudspeakers and an aeroacoustic wind tunnel. Typical results show that for practical measurement durations the proposed method will provide a turbulence rejection in octave bands of approximately 15 dB at 31.5 Hz rising smoothly to 25 dB at 8 kHz. The method thus appears to have some distinct advantages over ISO 5136 methodology.

In developed countries, coal power plants are often used to work in part load and possibly to follow the demand. Consequently, the transient behaviour of these power plants is a very important issue. In integrated coal gasification combined cycles (IGCCs), the complex interactions between the different parts of the plant make the process behaviour difficult to predict. This paper describes a non-linear simulation model of the gasification island. It comprises mainly a module for the gasifier reactor with water walls, two different ones for the convective and radiant syngas coolers, a raw gas / clean gas heat exchanger and a simple module for the gas treatment. This latter is simplified because it has only a small influence on the transients of the plant given its low inertia. All these modules have been introduced into a dynamic computational tool previously designed to simulate the transients of gas combined cycles (Dechamps, 1995). The computational code, called CCDYN (Combined Cycle DYNamics), is a modular and flexible code, each module being a main component (like a gasifier, a gas turbine, a heat exchanger, …) solving a set of transient equations. This paper also presents some results and demonstrates the interest of such a modelling. As an example, the gasification island of a coal-based IGCC is modelled in the case of different coal feed properties and the influence on the syngas composition is illustrated. Another example is the evolution with time of the various temperatures in the system during a start-up procedure and a load variation. The thermochemical and physical properties used in the models are extracted from Barin (1989), from Perry and Green (1984) and from Dechamps (1995).

In this paper, the mentioned cycle has been transformed in a CO2 regenerative Ericsson-like cycle and therefore is named E-MATIANT. The removed CO2 can still be available at a pressure higher than the critical one (73 bar). When optimising the cycle, the calculated optimum pressure will be around 60 bar; this makes the technical issues easier to deal with than when using a supercritical fluid, namely the material strains and corrosion behavior. A sensitivity analysis is performed with respect to the CO2 delivery pressure in order to evaluate the performance changes. The fuel flexibility is an important asset of the newly designed cycle: mixtures of CO and H2 produced either in gasification or steam reforming processes can indeed be burnt in the combustion chamber. In a future work, the combination of a solid oxide fuel cell (SOFC) and this cycle both fed by a CO and H2 mixture will be considered as an option for the improvement of the global efficiency. If not fixed in a chemical or biological system, the delivered CO2 can be used in industry or in the enhancement of fossil fuels recovery from their deposits, with a marginal compression consumption work. In this paper, CO2 injection is used to enhance methane recovery from coal seams by some 20 to 30%, in comparison with water pumping. The depleted seam can afterwards be used as the host site for long run CO2 sequestration. As a conclusion, the combination of quasi-zero emission power plants with CO2 geological storage and enhanced fuel recovery provides a CO2 flow, otherwise considered as a waste or a byproduct, with an exergetic and a commercial added value. This makes this option a serious alternative to other CO2 control technologies.

A new probe has been developed for Bruel & Kjaer 6.35 mm (1/4″) microphones in order to allow in-duct measurements in high temperature gas turbine exhaust ducts without exposing the microphone to excessive temperatures. The motivation for this design was the need for a probe system that is easily transported and installed on site. The new probe is made from readily available 6.35 mm (1/4″) o.d. tubing and compression fittings. It consists of a stem to sample the in-duct acoustic field, a shut off valve, a “T” connector to provide a microphone port remote from the hot gas and an anechoic termination. The termination provides a true anechoic response down to 20 Hz. The probe provides a smooth, resonant free response between 20 Hz and 20 kHz allowing for accurate calibration and measurement. This paper describes the probe design and installation details, probe frequency response calibration, probe flanking limit and performance of the anechoic termination. The paper also compares the probe response to theoretical predictions. Relative to other potential in-duct measurement probe systems the new design is seen to be lightweight, compact and inexpensive.

Currently there is a lot of interest in microturbines, with projections that these small turbogenerators will be produced in large quantities in response to the needs of the deregulated power generation market. First generation, low pressure ratio microturbines, based on state-of-the-art technology, require a recuperator to achieve an efficiency of 30 percent. With the recuperator representing 25–30 percent of the turbogenerator cost, major efforts are underway to establish new heat exchanger concepts, with low cost being paramount. In this paper a simple primary-surface recuperator concept is suggested that meets the major requirements, which include compact size and light weight, minimum number of parts, amenable to high volume automated fabrication, and packaging flexibility in either a wrap-around annular geometry or rear mounted cube form. This paper includes recuperator background information, technology bases, details of the proposed surface geometry, fabrication considerations, specific size and weight, cost target goals, and heat exchanger configurations for integration with microturbines in the power range of 5 to 75 kW.Copyright © 2000 by ASME

In this paper experience with some of the first gas turbines equipped with dry low NOx combustors installed in the North Sea is presented. The case history covers LM2500 and LM6000 gas turbines. The paper outlines further some of the technical challenges for future applications in conformance with recent revisions of power plant air emission guidelines.

This paper discusses some of the advanced concepts and research and development associated with implementing catalytic combustion to achieve ultra-low-NOx emissions in the next generation of land-based gas turbine engines. In particular, the paper presents current development status and design challenges being addressed by Siemens Westinghouse Power Corp. for large industrial engines (>200 MW) and by Solar Turbines for smaller engines (

Gas turbine based power and cogeneration schemes are likely to become more favored as turbine efficiencies improve, but the economics of local power generation may depend on the use of low cost fuels other than natural gas. Opportunities may arise in the application of gas turbines in the pulp and paper industry and the wider use of biomass derived fuels in general. These fuels, as produced, typically contain inorganic impurities originating from ash forming substances and other minor constituents of the feedstock. Also, depending on the biomass treatment process, they contain varying amounts of complex organic derivatives, commonly referred to as tars, and some simpler condensable vapors. The Department of Energy is sponsoring work aimed at providing realistic data on low level constituents and impurities in gas derived by indirect gasification of wood, some of which may have disproportionately severe effects on turbine operation, durability, and emissions performance. It is planned to sample gas from both laboratory scale (up to 20 tons/day) and pilot scale (200 tons/day) installations and to assess the effectiveness of wet scrubbing procedures and catalytic reforming of condensables in cleaning up the gases. This paper discusses the rationale for this work, experimental approach, and analytic procedures that will be used. The work will include the operation of a small (220-kWe) gas turbine to provide direct information on the impact of using the final biomass derived gas delivered by the system. The laboratory scale work is currently under way, with a planned completion date in mid 2000. The second phase is dependent on arrangements for integration of the R&D effort with the operation of the pilot plant.

An ASME performance test code. PTC 47, for integrated gasification combined cycle, IGCC. plants is currently being written. This code will include definitions of the significant overall plant and plant component performance results — input, output, and effectiveness. It will indicate the measurements and measurement techniques required to calculate these results, and estimate systematic uncertainties associated with each measurement, as well as random uncertainties due to the measuring device or variations in plant conditions during the test. The code writing committee is making use of mathematical models of the performance of various IGCC power plant configurations to aid in the work of code preparation and testing. The objective of this paper is to describe how computerized system performance models are now being used in the preparation of PTC 47, and to indicate how such models might be used in the conduct of performance tests in the future. The general form of a system performance model is discussed to clarify how it relates to correction factors for system performance parameters — input, output, and effectiveness: but the paper does not include defining or solving the actual equations of a system performance model.

Fuel cells are emerging as a major new power generation technology that is particularly suitable for distributed power generation, high-efficiency, and low pollutant emission. An interesting combined cycle, the “HYBRID,” has recently been scoped “on paper” that portends the potential of ultra-high efficiency (approaching 80%) in which a gas turbine is synergistically combined with a fuel cell into a unique combined cycle. This paper introduces hybrid technology to the gas turbine community as a whole, and summarizes the current and projected activities associated with this emerging concept.

This paper outlines the handling of a semi closed cycle gas turbine, its working fluid is carbon dioxide and the fuel is low heating value gas from coal. At startup however, air and natural gas are used. The objective of the machine is to produce clean electricity with the smallest efficiency penalty. Many aspects of the operation of the engine are examined here; these include starting requirements, stator vane and bleed valve scheduling and the working fluid transition from air to carbon dioxide. Other features highlighted are the compressor operating lines and surge margins. The present paper describes the salient features of the three main stages into which the engine operation has been divided. These stages are: startup to synchronous idle, change of working fluid (from air to Carbon Dioxide-Argon) and fuel (from natural gas to coal synthetic gas) at synchronous idle and part load operation. Preliminary findings show that engine handling can be carried out effectively with variable stators. This is possible because of the two shaft gas generator. Another point of interest is the large increase of corrected speed relative to rotational speed experienced when the working fluid changes from air to carbon dioxide. In general the control of the engine does not seem to present any insurmountable problems despite the complexities arising from the need to change working fluid and fuel.

This paper describes a design point study of different power generation systems using the gasification of sugar cane bagasse, which produces a low calorific value fuel. The biomass gasification is viewed as a process of drying the solid fuel and heating it up before the gasification reactions take place. The process is represented by equilibrium conditions. Varying pressure, temperature and feed composition in the gasifier controls the fuel gas composition. Five alternative arrangements of an integrated gasification combined cycle (IGCC) power plant have been analysed using the exergy method. These alternatives comprise a combined gas / steam cycle using a simple gas turbine and also a reheat gas turbine, a combined gas / air cycle using a simple gas turbine and also a reheat gas turbine, and a combined gas / air / freon cycle using a reheat gas turbine. The combined gas / steam cycles are more efficient rather than the combined gas / air cycles. Using a reheat gas turbine at the topping cycle of the combined cycles analysed contribute to increase the overall plant exergetic efficiency. The exergy analysis has been carried out along with the performance assessment of power plants and takes into account the irreversibility of their components and the exhaust losses. The gasifier is the component of the power plant that destroys maximum exergy. Three computer codes have been developed. One of them has the ability of simulating the thermodynamic properties of the low calorific value fuel in the gasification process and the other two are related to the performance analysis of the different power cycles using the exergy method. The production of energy from the gasification of sugar cane bagasse has been of increasing importance to the Brazilian energetic matrix. This paper has been focused on the GEOPHILES - αlfa Programme, a project to train Latin America engineers on biomass gasification for power generation. The Commission of Energy of the European Community has supported this project.

A detailed study is presented in this paper concerning the changes required to transform a GE/Nuovo Pignone PGT2 gas turbine into a humid air turbine (HAT). The PGT2 is a 2 MW single-shaft gas turbine with a two stage centrifugal compressor and single can combustor. These features of the compressor and the combustion chamber are very important, because they reduce to a minimum the modifications necessary to add all the components required for operation in HAT cycle mode. This paper shows the performance of the PGT2 gas turbine in three different modified configurations: 1) regenerated cycle, 2) intercooled-regenerated cycle and 3) HAT cycle with flue gas condensation. A detailed economic study is presented of the regenerated and the HAT cycles. The intercooled-regenerated cycle was not considered in the economic analysis, because it does not reach the performance of the HAT cycle but it has not the advantage of being a dry cycle. All the components being added to the PGT2 are sized to determine with a sufficient accuracy their cost. The economic analysis presents a detailed cost analysis of the optimal configurations for maximum efficiency, and allows the calculation of the capital cost of the modified gas turbine. Return of investment is also presented in different economic situations with varying electricity and fuel prices.

This paper presents the Kvaerner design concept for an LM2500 Gas Turbine Package, with combined engine interfaces for both the LM2500 PE and the LM2500 Plus. The paper also presents the Kvaerner Modularized Auxiliary System concept, where the lube oil module and the fuel modules are located in separate compartments integrated in the turbine skid, protected from soak-back heat and blade-out conditions.Copyright © 1997 by ASME

Indirect fired multistage combined/cogeneration turbine system, fed with pulverized coal, has been considered. Net electric power of the system amounts to about 46 MW. Such a system has already been considered in former paper of the author, No 95-CTP-60, except that water/steam tube radiation screens were discussed. In this paper, on the other hand, a course of calculation as well as an example of air tube radiation screen is presented. The radiation screen supplys heat to the working air for the high-pressure turbine. The middle- and low-pressure turbines are fed with air heated in two convective hot-heat-exchangers placed just behind the combustion chamber.Copyright © 1997 by ASME

The provision of an ignition source in the central region of a liquid-fired combustor reduces the requirement for wide spray angles, rich primary zones, and their associated performance drawbacks such as high levels of soot and NOx formation and high liner wall temperatures. Various ignition devices have been considered for providing centrally located ignition sources. The current paper presents a study of one alternative concept — the integral catalytic torch ignitor/injector — as a means for providing both combustor light-off and enhanced flame stability in the combustor primary zone. An integral catalytic torch in a fuel injector offers the potential to significantly improve ignition arid flame stability and thus the opportunity to operate combustor primary zones at leaner conditions, which may improve emissions, pattern factor, and combustor liner durability. This paper presents computational and experimental results for a conventional liquid-fired combustor with the addition of a catalytic torch (replacing the pilot pressure atomizer) down the centerline of an air-blast fuel injector. The benefits of a lean primary zone with an integral catalytic torch/injector were investigated both computationally and experimentally by comparing combustor performance with standard and successively leaner primary zones. Pattern factor and emissions are compared with different primary zone jet configurations to observe if the central torch can enhance the operability of leaner primary zones in conventional combustor geometries. The experimental and computational results suggest that the integral catalytic torch can provide more than adequate ignition capabilities with improved combustor emissions when it is combined with a relatively lean operating primary zone.

Recent market place activity over the past years has shown a renewed trend in using steel mill waste gas for combustion in gas turbines. To effectively use steel mill gas, as well as other industrial off gases and syngas from gasification, more than just the combustion process has to be considered. With steel mill gases some of the more critical areas involve gas clean up and compression, as well as integration with the steam system of the host industrial plant. This paper will summarize some of the special considerations for applying a gas turbine/combined cycle power plant to a steel mill. Due to the similarities of the fuels, this paper will also discuss how this is common to other industrial gases applications. GE has substantial experience in combustion of low calorific fuels as well as industrial process gases and more recently steel mill gases.

The combustion gas turbine, operating in both simple and combined cycle modes, is rapidly becoming the preferred prime-mover for electrical power generation for both new plants, and in the repowering of old power stations. In replacing Rankine cycle plants the combustion gas turbine could become dominant in the power generation field early in the next century. Fired currently with natural gas, and later with gasified coal these gas turbines will operate for many decades with no concern about resource depletion. This paper addresses an extension of high efficiency gas turbine technology but uses a combustion and emission-free heat source, namely a high temperature gas cooled nuclear reactor. The motivation for this evolution is essentially twofold, 1) to introduce an environmentally benign plant that does not emit greenhouse gases, and 2) provide electrical power to nations that have no indigenous natural gas or coal supplies. This paper presents a confidence-building approach that eliminates risk towards the goal of making the nuclear gas turbine a reality in the 21st century.Copyright © 1997 by ASME

This paper describes major results of combustor envelopment activities conducted under 1 MW industrial engine (Turbo Green 1200) program at Samsung Aerospace. The program was initiated in 1992 partially supported by Korean government. The main application of the industrial engine is a standby duty unit with a future derivative engine considered for a cogeneration unit. During the engine development, various tests of the engine and its components were carried out to confirm the performance target or the engine. This paper concentrates on the component test activities of the combustion section.Copyright © 1997 by ASME

To evaluate the potential of the compressor of Sulzer’s Typ 3 gas turbine, a series of engine tests was analyzed with two computer codes. The comparison between measured and calculated performance map are given in the paper. The design goal was to find modifications, which can be applied easily to already operating engines. The simplest option-increase of shaft speed with the existing blades-would have caused high loss due to increased tip Mach number. The calculation revealed, that a newly designed first rotor blade is an appropriate modification to increase massflow and efficiency. No further change is required, because the calculations indicate, that all subsequent stages operate at near optimum incidence. The calculations were confirmed experimentally. The paper presents the new rotor blade and its influence on the compressor calculated and measured performance.Copyright © 1981 by ASME

This paper describes the development history of the CW352 engine combustor from the time when the persistent problem of a hot primary zone wall when operating in the regenerative mode while burning diesel oil was solved by the incorporation of an airblast atomizer. The problems of stability and poor atomization at low engine cranking speeds which accompany the use of airblast atomizers were addressed in the combustion laboratory but evaluation tests on an engine showed that further improvement in these areas would be beneficial. Concurrently, the preliminary design strategy of the CW182 combustor was predicted on the use of an airblast atomizer and its development program emphasized a phase of testing which examined the effects on nozzle performance of variations in local flowfield and of the use of atomizing air. The paper documents the particular problems met and solved in the areas of burning oil fuel in a regenerative machine, of maintaining low emissions of smoke while designing for single inventory of parts and providing stable combustion by the use of auxiliary atomizing air.Copyright © 1981 by ASME

This paper discusses a current research and development program whose object is to advance the technical readiness of large, coal-fired heaters to supply the input to closed-cycle gas turbine cogeneration systems. Such closed-cycle systems become increasingly attractive as energy cost increase. The gas turbine working fluid is completely isolated from the products of coal combustion, thus avoiding corrosion and erosion of the gas turbine system. Additionally, the nature of the thermodynamic cycles is frequently such as to afford substantial savings in coal input requirements as compared to steam turbine based systems producing equivalent process heat and power. This paper describes three fired heater concepts that are under development for CCGT service. The organization of the research and development program, and the development needs of the fired heaters that are to be satisfied by the R&D program, are discussed.Copyright © 1981 by ASME

The work described in this paper is a part of the Department of Energy/Lewis Research Center Advanced Conversion Technology (ACT) Project. The program is a multiple contract effort with funding provided by the DOE and technical management provided by the NASA-Lewis Research Center. Continued development of combustion technology is needed to provide utility and industrial gas turbine engines capable of sustained, environmentally acceptable operation when using minimally processed and synthetic fuels. This paper describes an exploratory development effort to identify, evaluate and demonstrate techniques for controlling emissions of Nox and smoke from combustors of stationary gas turbine engines. Preliminary results indicate rich primary zone staged combustion provides environmentally acceptable operation with residual and/or synthetic coal derived liquid fuels.

During the initial years of Gasunie’s existence, the early 60’s, a projection was made for the power required in various compressorstations in the grid. This projection was updated periodically and this paper reviews the 1977 update, focussing on the Ravenstein compressorstation. The main subject of the paper is the development of the design criteria for this update and the comparison with the reality of the 1979/1980 pumping season. It may be stated that the actual conditions of the pumping season have justified the selection of the criteria.Copyright © 1981 by ASME

This paper presents techniques in which greater productivity and fuel savings can be achieved by the use of online monitoring and diagnostic systems and compressor management systems applied to turbo-compressors. With maintenance life cycle costs for gas turbines being about one-fifth of fuel life cycle costs, the incentives for maintaining good operating efficiency is high. An online monitoring and diagnostic system can go a long way in pin-pointing areas in which performance decrements occur. There is also large monetary savings by operating load compressors with minimum recirculation. Secondary benefits of such systems include automated vibration analysis and automated diagnostic of common faults. This paper also covers some case histories that illustrate benefits and generic system diagrams that illustrate such systems.

There has been an increasing demand for onshore testing of equipment destined for offshore operation. The justification for this requirement can be summarized as follows: 1. High cost of offshore commissioning where even minor faults detected, constitutes potentially serious problems. 2. Consequenses of delay of platform start-up are enormous. 3. Skilled experienced personel and diagnostic equipment is available onshore, and rectification of new units will benefit from the existence of previous experience. 4. Spare and renewal parts availability. This paper describes the method for string testing of a 3 unit 60 mw utility gasturbine-generator power module built for the gullfaks A platform in the Norwegian sector of the north sea. It describes the test facility and test equipment set up and also the test program which was followed. At the time of writing the paper the test program was barely initiated, and for that reason the test results will be presented in the form of an addendum to this paper during the meeting.

The efficient end environmentally friendly production of electricity is undoubtedly one of the 21st century priorities. Since renewable sources will be able to guarantee only a share of the future demand, the present research activity must focus on innovative energy devices and improved conversion systems and cycles. Great expectations are reserved to fuel cell systems. The direct conversion from chemical to electrical energy eliminates environmental problems connected with combustion and bypass the stringent efficiency limit due to Carnot’s principle. Still in infancy high temperature Fuel cells present the further advantage of feasible cycle integration with steam or gas turbines. In this paper, a Molten Carbonate Fuel Cell plant is simulated in a cycle for power generation. The introduction of an external combustion Gas Turbine is evaluated with the aim of efficiency and net power output increase. The results show that the proposed cycle can be conveniently used as a source of power generation. As compared to internal combustion Gas Turbine hybrid cycles found in literature the plant is characterized by fuel cell greater simplicity, due to the absence of pressurization, and gas turbine increased complexity, due to the presence of the heat exchange system.

The nutating engine is a new type of internal combustion engine. The engine has unique advantages over conventional piston engines and gas turbines in small power ranges suitable for unmanned aerial vehicles (UAV), and other applications. This publication is the original presentation of the performance potential of the simplest version of the engine, a one-disk engine operating at constant compression ratio, for light airframe propulsion. In its basic configuration the core of the engine is a nutating non-rotating disk, with the center of its hub mounted in the middle of a Z-shaped shaft. The two ends of the shaft rotate, while the disk “nutates”, performs a wobbling motion without rotating around its axis. The motion of the disk circumference prescribes a portion of a sphere. A portion of the area of the disk is used for intake and compression, a portion is used to seal against a center casing, and the remaining portion is used for expansion and exhaust. The compressed air is admitted to an external accumulator, and then into an external combustion chamber before it is admitted to the power side of the disk. The external combustion chamber enables the engine to use diesel fuel in small engine sizes, giving it unique capabilities for UAV propulsion. The performance of the one-disk engine configuration for flight Mach numbers from 0 to 1 and altitudes from 0 to 20 km is presented and discussed. The performance with equal compression and expansion volume is compared with the higher-efficiency version with expansion volume higher than compression volume. A companion paper examines multi-disk alternative engine configurations and load control schemes.

This paper describes the steady state performance analysis of a 3-shaft closed cycle helium turbine using nuclear heat source. The analysis is carried out using a computer program, which is specifically made for this cycle. The computer model was tested for various Turbine Entry Temperatures (TET) and absolute pressures. The analysis of the change was focused on the compressors, as these are relatively more critical than the rest of the equipments. The change in TET triggered changes in shaft speed, mass flow rate, power output, absolute pressure etc. Adjustable guide vanes were used to study the operation with constant surge margin. The closed cycle was tested for various absolute pressures and it was established that the efficiency will not be affected in using the inventory control for the load variation.

This paper presents the results of an investigation of active control of combustion instabilities in a natural gas, high-pressure, full-scale gas turbine combustor that was retrofitted with an Active Control System (ACS). The combustor test rig simulates the geometry, inlet airflow distribution, and pressurization of a can-type combustor that exhibits dynamic flame instabilities at some off-design operating conditions. Two essential features of the investigated ACS are 1) a real-time mode observer that identified the frequencies, amplitudes and phases of the dominant modes in the pressure signal and 2) a fast response servo valve that can modulate a large portion of the gaseous fuel. Two active control configurations were studied. In the first configuration, the actuator was mounted on one of two premixed fuel stages, and in the second configuration it was mounted on the inlet to the stabilizing diffusion stage. In both configurations, the ACS damped combustion instabilities, attenuating the dominant mode by up to 15dB and reducing the overall broadband noise by 30-40%. NOx emissions were also reduced by approximately 10% when control was applied. Finally, this study demonstrated the importance of having a fast multiple-mode observer when dealing with complex combustion processes with inherently large time delays.Copyright © 2001 by ASME

The need to evolve next-generation ultra-lean premixed systems with advanced air management and improved liner cooling strategies have led Solar to develop a pre-production combustion system for its C50 class engine. The system uses an Augmented Backside Cooled/Thermal Barrier Coated (ABC/TBC) combustor and Variable Geometry injectors. The technology reduces both NOx and CO emissions, while improving part-load cycle efficiency. The ABC/TBC combustor technology eliminates quenching of the reaction at the walls typically found in combustors using film-cooling techniques. Eliminating this quenching effect is not only conducive to reducing CO emissions, but it also enables the operation of the combustor primary zone at low temperatures to produce minimum thermal NOx. Coupled with a set of variable geometry injectors, the system manages air more effectively to extend the combustor operating range under which emissions and stability limits are maintained. The injectors enable the control of air entering the combustor as a function of engine load and ambient temperature. Such ability reduces the need to bleed high-pressure compressor air at part-load, thus enhancing the engine cycle efficiency. The pre-production combustion system is currently undergoing field evaluation to assess long-term durability, characterize system performance, and develop optimum control algorithms. The development methodology and experience for this system is discussed in this paper.

This paper describes the effects of degradation of the main gas path components of the gas turbine topping cycle on the Combined Cycle Gas Turbine (CCGT) plant performance. Firstly the component degradation effects on the gas turbine performance as an independent unit are examined. It is then shown how this degradation is reflected on a steam turbine plant of the CCGT and on the complete Combined Cycle plant.TURBOMATCH, the gas turbine performance code of Cranfield University was used to predict the effects of degraded gas path components of the gas turbine have on its performance as a whole plant. To simulate the steam (Bottoming) cycle, another Fortran code was developed. Both codes were used together to form a complete software system that can predict the CCGT plant design point, off-design, and deteriorated (due to component degradation) performances.The results show that the overall output is very sensitive to many types of degradation, specially in the turbine of the gas turbine. Also shown is the effect on gas turbine exhaust conditions and how this affects the steam cycle.Copyright © 2001 by ASME

Gasified biomass has become an attractive fuel source for the production of electricity for various processes due to its potential to reduce the net CO2 emission. The overall aim is to combine biomass as a fuel source with high temperature catalytic combustion in order to lower emissions of nitrogen oxides, carbon monoxide and hydrocarbons. This paper presents the design of a pressurized test facility for testing various catalytic materials under varying operating conditions and arrangements in the combustor. Instrumentation of the rig is described. Catalyst development and preparations are being described as well as the first results from the pilot-scale test facility. Different catalyst configurations and compositions have been tested. It was shown that a Pd / LaAl11O18 catalyst is able to ignite the synthetic gasified biomass and that high conversion rates of H2 can be achieved with this type of catalyst. By applying a layer of barium stabilized alumina, thermal protection of the catalyst is achieved, hence limiting the maximum catalyst temperature.

The Vx4.3A gas turbine family has already been well received by the market. Nevertheless the market drives technology towards both increased turbine inlet temperatures and reduced emissions. The HR3 burner was originally developed for the V4.2 and Vx4.3 fleet featuring silo combustors in order to mitigate the risk of flashback and to improve the NOx- emissions (Prade, Streb, 1996). Due to its favourable performance characteristics in the Vx4.3 family the advanced HR3 burner was adapted to the Vx4.3A series with annular combustor. The paper reports upon the design, testing and field evaluation steps which were necessary to implement the burner for the 50 and 60 cycle gas turbines. With CFD calculations the flow field and the mixing of natural gas and combustion air have been optimised. A number of tests in the Siemens test facilities confirmed these predictions. The atmospheric 3 burner segment combustion test rig allows to test flame interaction, stability and exhaust gas emission simultaneously. In the Siemens Berlin Test Facility which provides a platform for full scale gas turbine testing 24 HR3-burners were implemented into a V84.3A gas turbine with a base load power output of 184 MW at ISO conditions for prototype testing before introducing this new burner generation into the bigger 50 cycle family V94.3A. Implementation of 24 scaled HR3 burners were installed in the V94.3A of Cottam Development Centre (Great Britain) and demonstrated an excellent performance. The gas turbine reached an ISO base load output of 265 MW with NOx emissions well below 25 ppmvd. Due to the very promising test results in Berlin and Cottam, this burner modification, which can be retrofitted to all VX4.3A gas turbines, was implemented nearly fleet wide.