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Deregulation and growth in the power industry are causing dramatic changes in power production and distribution. The demand for peak power and potentially high revenues due to premium electricity rates has attracted independent developers to the concept of Merchant Power Plants (MPPs). Over 100,000 MW of greenfield capacity is currently being developed through approximately 200 merchant plants in North America. These MPPs will have no captive customers or long-term power purchase agreements, but will rely on selling electricity into a volatile electricity spot market. Because of this, MPPs need the capability to export as much power as possible on demand. MPPs must also have the capability to produce significant assets in order to compete in the marketplace, based on both technical and commercial operation factors such as value engineering, life-cycle cost management, and information technology. It is no surprise then, that almost all merchant project developers have specified combined cycle (CC) technology. The CC power plant offers the highest thermal efficiency of all electric generating systems commercially available today. It also exhibits low capital costs, low emissions, fuel and operating flexibility, low operation and maintenance costs, short installation schedule, and high reliability/availability. However, since gas turbines (GTs) are the basis for CC power plants, these plants experience power output reductions in the range of 10 to 15 percent during summer months, the period most associated with peak power demand. In order to regain this loss of output as well as to provide additional power to meet peak demands, the most common options are GT inlet fogging, GT steam injection, and heat recovery steam generator (HRSG) supplemental firing. This paper focuses on plant design, cycle performance, and the economics of plant configuration associated with these options. Guidelines are presented in this paper to assist the owner in selecting power enhancement options for the MPP that will maximize their Return on Equity (ROE).

The paper describes GE’s Remote Monitoring and Diagnostic (RM&D) system, its operation, its unique features and our experiences in applying it to improve performance and availability of heavy-duty gas turbine fleet worldwide. A key success factor of the system is that it relies upon an effective combination of advanced computer automation complemented by technical experts who have an in-depth understanding of the power generation equipment to achieve its objectives. The RM&D system enables GE experts to remotely access operational data of power plants operating world wide, and exercise sophisticated algorithms, which can detect abnormal operating conditions. The experts, with ready access to the design information, operation and maintenance information and in-depth knowledge about the turbines, identify and track operational signatures, which may indicate potential problems. The real key is to be able to distinguish false indications from the ones that are true early indicators of potential problems. In this paper we describe a design approach for developing a successful RM&D system. We illustrate our approach through various examples of performance, vibration and combustion diagnostics scenarios.

The U.S. Department of Energy is in its 7th year of a 9-year program to develop the next generation of advanced turbine systems (ATS). Under this program, partnerships between industry, universities, national laboratories, government agencies and institutions, and the U.S. Department of Energy (DOE) are performing research and development required to commercialize the ATS. The ATS Program is jointly sponsored by the U.S. DOE Offices of Fossil Energy and Energy Efficiency and Renewable Energy. Supporting R&D, recent ATS accomplishments and future advanced concepts for next generation gas turbine systems are described and discussed in this paper. As the ATS program winds down, DOE’s National Energy Technology Center (NETL) is evaluating the technology and market needs for continuing DOE support to develop advanced turbine systems. As part of this effort, NETL is sponsoring market and technology assessments, regional focus group discussions, and public workshops. The purpose of this paper is to provide the status of the ATS Program and the NETL perspective on potential options for future research and development needs, and public-private development programs addressing turbine based power generation for systems 30MW or greater in output.

There is a significant emphasis on peaking power, particularly recognized in the US power generation market. Orders for gas turbines are at their peaks, with OEMs taking orders for delivery in the year 2002, or later. Though a simple cycle GT is the recognized power plant of choice for daily cycle and peak power supply, it still has the highest fuel consumption rate per kWh produced (heat rate, Btu/kWh or Btu/kWh) with associated high emissions. The massive additions of GT power plants for primarily peak/cycling applications should generate needs for better utilization of installed capacities. The Compressed Air Energy Storage (CAES) plant is demonstrated as the best and cost-effective plant for storing significant amounts of the off-peak energy and releasing the peak energy as needed. This paper presents an innovative power plant concept, which is based on the integration of a conventional GT with the unfired CAES, air-bottoming cycle — denoted as GT-CAES. This concept is analyzed and compared to a conventional CAES cycle. Also, the paper presents characteristics of this concept based on ABB’s GT24/26 combustion turbine, the characteristics produced for a number of GT-CAES projects which are in various stages of development.

In this paper, a Fiat Avio 701F gas turbine re-design process is presented. This already tested gas turbine has been modified, for a particular re-powering application: a reduction in the net power production is required, whereas efficiency and exhaust temperature have been improved by mean of increased hot gas temperature at the first nozzle inlet section. Consequently this re-powering solution clearly requires consistent re-design efforts to satisfy specific plant operating conditions. The gas turbine power output has been tuned to the required value by reducing the air inlet mass flowrate; the combustion chamber setting has been modified with particular attention to the control of pollutant emission level. The increase of inlet stator turbine temperature necessitated a complete review of the three cooled turbine stages. The aim of greater overall efficiency with inlet and exit turbine temperature increase also involved the introduction of a new blade material. For design tool flexibility the blade cooling design procedure has been improved making better optimization of the cooling system possible. In this paper a detailed description of the several gas turbine modifications with particular attention to the blade cooling design procedure and to the corresponding simulation results is reported. The modifications developed could also be introduced on the new version of the 701F, at full power capability, in order to get better efficiency and power.

The share of the gas turbine combined cycle plants tends to increase rapidly in the world of power generation. Under the circumstances, MHI is developing the several kinds of gas turbine to meet each customer’s needs. The ‘F’ series’ engine, which has a firing temperature of 1350–1400 degree C, is predominant in the current market, and the reliability improvement is constantly performed. As a result, the operational hours of 50,000, and the combined cycle efficiency of 55–57% (LHV) is achieved for F-series combined cycle. During the operating experience, any events occurred in field operation is solved. Also, countermeasure was implemented on every machine. Furthermore, robust design improvement is introduced, and commercial operation of the design achieved higher reliability and availability. In this paper, the operating experiences, design improvements and the F series gas turbine uprating program are introduced.

The contribution of the gas turbine in simple and combined cycle systems to power production in the United States has been steadily rising over the past 25 years. In 1998 their contribution to power production was approximately 15% and it increased over the past 5 years by 1.5 to 2%, annually. In parallel, the United States Department of Energy (DOE) has financially supported Advanced Technology development with good formulated goals for overall performance of plants including reliability, availability and maintainability (RAM). In this paper the authors evaluate RAM performance data from power plants over the past five years. This evaluation can be used as baseline or benchmark for further improvements. It takes into account the mode of operation being base load, cycling or peaking application and analyses the power plant on a year-by-year evaluation. All RAM-data came from the same source and are collected and analyzed according to standardized procedures. Availability will be reviewed for machines of different sizes and technologies. Maintainability will be analyzed as function of the size of units, energy production, and the mode of operation. Gas turbine simple and combined cycle power plants have been operated in peaking, cycling, base and continuous load operation. The flexibility is shown in different “Service Hours per Successful Start” and a correlation with the RAM parameters. To analyze and explain these differences will be the main result of this evaluation. The contribution shall help to evaluate the best solution for individual sites because efficiency and availability cannot always be increased in parallel.

Explosive growth in power plants in the US and elsewhere is occurring through combined cycle advanced gas turbine technology. Significant fuel expenditure savings are possible through such technology. Much of the recent advances have been possible through the transfer of aero engine design tools, elevated temperature materials, coatings, and sealing technologies. A balanced approach that melds the aero engine technologies and longstanding field experience from large industrial frame gas turbines is key to ensuring Reliability, Availability, Maintainability and Durability (RAM-D) design objectives are met. Future costs associated with power generation and distribution with these advanced gas turbine combined cycle power plants will undoubtedly be driven by major decisions of OEMs pertaining to design and validation approach, material selection, reparability, design criteria, and design features for quicker maintainability. In this paper, MHI’s approach for enhancing RAM-D performance and reducing O&M expenditures of advanced combined cycle gas turbines are described.

Significant change is taking place in the power generation market. We are witnessing structural change as we move to a deregulated and competitive global market. And we can also see significant technological change, as new products are driven towards improved efficiencies, greater output and environmental friendliness. Measuring the impact of these changes in terms of efficiency, output and reduced emissions is a straightforward exercise, and the ability to judge if the change has been positive is relatively objective. However, these structural and technological changes have created challenges in terms of reliability and availability measurements. • First, our measurement approach is obsolete and has no consideration for duty cycle… The demand, the mission profile, which must be achieved for the unit to meet its economic contribution value, is the single most important issue for power producers today. • Second, if the measurements have no consideration for the demand that the unit must meet, then the measure is not tied to the profitability of the plant, and therefore the operators are forced to use non-standard measures to accommodate management reporting. • And third, the strong relationship between effective plant operations and profitability demands “real time” data gathering from the unit control or plant DCS, and transformation of the data points into meaningful information for effective decision support, specifically related to the availability and reliability of systems, components, and the full plant, with a specific focus on measuring “demand” based availability and reliability. This paper addresses the issue and the opportunities associated with developing both new standard for measuring demand related reliability and availability, as well as the focus on “real time” data capture.

During more than 100 years engineers of the Swiss development center of A.-G. BBC Brown, Boveri & Cie., from 1988 onwards ABB Asea Brown Boveri Ltd, in 1999 ABB ALSTOM POWER Ltd and now ALSTOM Power Ltd in Baden, Switzerland have significantly contributed to the achievement of todays advanced gas turbine concept. Numerous “Firsts” are highlighted in this paper — ranging from the first realization of the industrial, heavy-duty gas turbine in the 1930s to todays high-technology Gas Turbine (GT) products, combining excellent performance, extraordinary low environmental impact with commercial attractiveness for global power generation. Interesting connections could be unveiled for the early parallel development of industrial and areo gas turbines.Copyright © 2001 by ASME

The Pebble Bed Modular Reactor (PBMR) Demonstration Plant is a 100 MW(e) gas cooled nuclear reactor being developed by Eskom, the South African state electricity utility. The PBMR uses helium in a closed cycle and operates at pressures up to 7.0 MPa and temperatures up to 900°C. Three heat exchangers are used in the PBMR power generation cycle, a Recuperator, a Pre-cooler and an Intercooler. All three exchangers play an important role in the power generation cycle but the Recuperator represents the most challenging application for heat exchanger technology requiring high performance under demanding operating conditions. Printed Circuit Heat Exchanger (PCHE) technology is being considered for Recuperator for several reasons including its ability to handle high pressures and high temperatures and its compactness. PCHEs are high integrity plate type heat exchangers made by chemically etching fluid flow channels into flat metal plates which are then diffusion bonded. This paper will discuss aspects of the design and construction of PCHEs and look at how this technology is being applied to the PBMR.Copyright © 2001 by ASME

Natural-gas-fired combined cycle plants have become the preferred technology for new power generation because of their high thermal efficiency and superior environmental characteristics. An outcome of the recent resurgence in the U.S. power market is that the average size of the new power plant has increased, leading to the use of two or three advanced gas turbines (GTs) per plant. In lieu of the traditional multishaft arrangement, some GT suppliers are advocating the use of multiple trains of their single-shaft reference plants. This paper covers salient differences between the two approaches and discusses at length the major variables and their impact on balance-of-plant cost that must be carefully examined for a cost-effective solution.Copyright © 2000 by ASME

In several industrial processes, various hydrocarbons, such as low BTU blast furnace gas, syngas, Naphtha, heavy oil and condensate, are available as by-products or residues. Burning such unconventional fuels for combined cycle power generation can be attractive in certain countries due to their low prices or availability compared to natural gas or distillate. In this paper, design and operating experience of combined cycle power plants burning such unconventional fuels, e.g. Bao Shan in China burning LBTU gas, GVK in India burning Naphtha and Api in Italy burning medium Btu gas from heavy oil (refinery bottom) gasification etc. are discussed. The high degree of manufacturers’ ability to develop such projects and design the required equipment — burners/combustors, CC power train and control systems — is illustrated. In addition, the development of Naphtha and condensate burner for GT13E2 is described in short.

The combined adoption of solid oxide fuel cells and microturbines has been recently considered for the development of small advanced plants for high efficiency distributed electric power generation. This paper investigates the application of this technology to an independent, small-capacity power plant, which operates in conjunction with a compression heat-pump/chiller system and eventually with an absorption chiller, cogenerating heating, cooling and electric power for a single user like a medium-size commercial building. Detailed results are presented for both the application of a SOFC+microturbine system and a simple microturbine system, in terms of annual energy balances; they indicate, specially for the SOFC+microturbine systems, high primary energy savings and reduction in emissions of carbon dioxide. A preliminary economic analysis is presented, showing that, in absence of incentives, specific SOFC investment costs as low as 1200 $/kW are required to make economically attractive the adoption of this highly efficient and environmentally benign component.

Gas Turbines in power generation are frequently of the single rotor type. The rotor is directly connected to the electrical generator. The rotor may be supported by two journal bearings or in some cases there is an additional journal bearing situated between the axial compressor discharge and the gas turbine intake. This third bearing serves to provide the rotor with additional support required to reduce rotor dynamic instabilities. The third bearing is, therefore, inside the machine housing and a significant amount of maintenance work is necessary to inspect it. The third bearing is also exposed to elevated temperatures by, essentially, being surrounded by compressor discharge air. A certain amount of compressor discharge air leaks through the seals into the cylindrical space around the third bearing housing and from there, due to significant pressure gradients, into the third bearing. Labyrinth seals are provided to impede air leakage from the pressurized cylindrical space into the bearing cavity. The air that leaks into the bearing housing mixes with a buffer air stream. This buffer air stream serves to cool the bearing cavity and to prevent leakage of hot, high-pressure air into the bearing cavity. Two dry air streams are then routed into the atmosphere via the coaxial space formed by two cylindrical surfaces. The portion of the buffer air stream contacting the bearing lubricating oil is de-misted in a special de-mister vessel. The de-misted air is exhausted into the atmosphere and the separated oil is returned to the gas turbine lubricating oil reservoir. This Paper discusses the introduction of brush seals into the No. 3 bearing housing as an additional element in retarding the high pressure, high temperature air infiltration into the No. 3 bearing housing.

Ambient air temperature plays significant role in performance of a Gas Turbine. Frequently Gas Turbines in electrical power generation are single rotor and are directly coupled to the Electrical Generators. These machines normally operate 8,000 hours per calendar year under the 100% load. The control of the combustion air flow is achieved by modulating compressor Inlet Guide Vanes (IGV). The single shaft axial compressor consumes as a rule of thumb more than 50% of turbine useful expansion work. Axial compressor is high-volume, moderate discharge pressure machine. Its power demand to discharge ambient air to the turbine combustion system is very dependent on ambient conditions such as pressure, temperature and relative humidity. The optimization of the axial compressor aerodynamic loading under various ambient conditions is therefore mandatory. During the hot and humid summer days, especially from the noon time to 6:00 PM, the demand for the power is at its maximum. This Paper describes selection, design and installation of the Inlet Air Cooling System. (IACS). The selected IACS is fine water mist, FOG. FOG System (FS) was selected because of its efficiency and because the clean water was available. FS incorporates Fog Generating Skid (FGS) and Fog Curtain (FC). FC is comprised of lateral lines with equally spaced. FOG Nozzles (FN). The FN is specially designed to generate individual “Fog Cones” that efficiently dissipate the water particles in the space. Fine water particles are atomized by incoming air in the Inlet Air (IA) duct. The homogenous mixture of FOG and IA is required to enhance the water mist particles evaporation process. In cases when the FS works in tandem with Evaporative Cooler (EC) most of the FOG particles are “injected” into the compressor suction. The injected FOG particles start to evaporate during the IA compression process. The water evaporation process simultaneously causes cooling of the IA being compressed. The result is reduced compression work and improved performance of GT.

During the night hours, to match the lowest load demand by a power generation system, many different strategies can be employed: unit load following, unit shutdown and hydro storage. Obviously, the utilized strategy influences the power production (gas turbines, hydro turbines, etc.) during the peak load demand. In this paper, the energy comparison among the above different strategies is carried out as a function of the load demand, the heat rate of the peaking units, the hydro storage total efficiency and the hydro stored energy. In particular, two sets of intermediate load fossil fuel power units (conventional and advanced) are considered. For the sets considered and relatively to the variable costs, the two-shift operation proved to be the most convenient strategy.

The GT24/26 Advance Cycle System ‘ACS’ was announced in 1993 as the first modern single shaft reheat combustion turbine to serve the power generation market. The ACS goal was to have higher efficiency and higher specific output than ‘F’ class machines already providing the first step to improved efficiency. The innovative sequential combustion system (reheat) technology raised overall plant efficiencies to 58% LHV, a substantial improvement over the state of the art plant performance of 55% LHV at that time, without pushing the turbine inlet temperature envelope. This paper will review progress of the power plant concepts that will serve the emerging Merchant Power market as a result of deregulation of the industry not only in the United States but in other countries as well. Operating experience as well as improvements will be reviewed of the current and future plants that will account for over 10 GW’s in the year 2000. Improvements to meet the challenges of the New Millenium continue through ABB R&D efforts as well as contributions to the DOE ATS program.

This paper describes progress on Westinghouse’s Advanced Turbine Systems (ATS) Program. The ATS Program objective is to develop new utility gas turbines with greater than 60% net plant thermal efficiency, NOx emissions limited to less than 10 parts per million, reduced cost of electricity generation by 10% over current systems, and reliability-availability-maintainability equivalent to modern power generation systems. The Westinghouse ATS plant is a highly efficient combined cycle, based on an advanced gas turbine incorporating novel design concepts and enhancements of existing technologies. The 501 ATS engine is a fuel-flexible design operating on natural gas with provisions for future conversion to coal or biomass fuels. It is based on proven concepts employed in Westinghouse 501F and 501G engines. To achieve the required performance and reliability, the engine utilizes closed-loop steam cooling, advanced materials and coatings, and enhanced component performance. To minimize NOx emissions, an ultra-low NOx combustion system was incorporated. To ensure success, the necessary technologies were developed and integrated into the ATS engine design.Copyright © 1997 by ASME

Based on the experience gained with more than 80 machines operating worldwide in 50 and 60 Hz electrical systems respectively, Siemens has developed a new generation of advanced gas turbines which yield substantially improved performance at a higher output level. This “3A-Series” comprises three gas turbine models ranging from 70 MW to 240 MW for 50 Hz and 60 Hz power generation applications. The first of the new advanced gas turbines with 170 MW and 3600 rpm was tested in the Berlin factory test facility under the full range of operation conditions. It was equipped with various measurement systems to monitor pressures, gas and metal temperatures, clearances, strains, vibrations and exhaust emissions. This paper presents the aero-thermal design procedure of the highly thermal loaded film cooled first stage blading. The predictions are compared with the extensive optical pyrometer measurements taken at the Siemens test facility on the V84.3A machine under full load conditions. The pyrometer was inserted at several locations in the turbine and radially moved giving a complete surface temperature information of the first stage vanes and blades.