bluuebunny/crossref_metadata_2025 huggingface dataset:
Design Considerations and Operation of Condenser Bypass Systems in Combined Cycle Power Plants: Part 2
Authors: Eaton Richard H. , Blessman Edward R. , Schoonover Kevin G.
Published: November 2008

Premature condenser tube failures in combined cycle power plants have been experienced at several installations related to fatigue and erosion of the condenser tubes. The admission of high energy steam into the condenser poses design challenges with respect to the compact design of the condenser in the combined cycle power plant. Dissipation of energy within the condenser is a specialty design usually performed by the condenser manufacturer. Part 1 of this paper reviews condenser design and plant operation that impacts, or may contribute to, condenser tube failures. Part 2 of this paper reviews the condenser bypass system, identifies related opportunities, and provides design considerations to optimize condenser reliability through the controlled admission of high energy steam into the condenser. A number of factors go into properly designing sub-systems, as required by the functional operation of the combined cycle plant. The bypass system is one sub-system, considered integral with the condenser.
Risk Assessment of an L-0 Stage Blade Retrofit
Authors: Lam Tony C.-T. , Shuster Lewis H. , Dewey Robert P.
Published: November 2008

The tie-lugs on a 46” last stage blade (LSB) operated in a power plant first commissioned in the early 1960s experienced a long service history of cracking problems. A root cause investigation was performed, which identified the third mode of the bladed disc as operating near resonance. The original configuration is a 4-blade group structure with two tie-lugs. The third mode is a group torsional mode in which maximum stress occurs in the outer lugs. Dynamic stress throughout the rotating stage was calculated using a FE model. Based on the results of the investigation features of a retrofit were identified to detune the resonant mode and change the brazed lug to a more reliable forged design. A probabilistic analysis was used to demonstrate how the risk of cracking problem would be dramatically reduced.
The Planning and Execution of Taiwan’s Largest Combined Cycle Plant
Authors: Huang S. J. , Kuo C. C. , Kwan H. W.
Published: November 2008

Taiwan’s continuous economic growth in the past 50 years has spurred a similar growth in electricity demand. Historically the reserve margin has been less than 20 percent, although new generation is introduced every year. In the planning for new plants, consideration must be given to the location, choice of fuel, environmental impact and in a democratic society, their public acceptance. Based on projected growth demand, a decision was made in 1996 to build a 4,000 MW gas fired combined cycle power plant at the Dah Tarn location. The project has offered many opportunities to international equipment suppliers and local contractors. As a government entity, Taiwan Power Company follows the Government Procurement Law in procurement of equipment and services which is designed for open and fair competition and protection of the interests of the Owner. The uniqueness of the site and its surroundings, and the division of work between participants has presented some design and engineering problems that need to be overcome in the execution of this plant.
Finally: A Reliable, On-Line Carbon-in-Ash Analyzer
Authors: Letcavits J. J. , Conrads Hans , Shelton Ed , Sommer Todd
Published: November 2008

The paper describes the principle features necessary for reliable and representative on-line unburned carbon-in-ash (UBC) measurement. The paper shows how modern on-line technology has been applied to obtain truly representative and reliable data for the evaluation of fly ash quality and boiler performance. To assure accurate UBC data from which to make operating decisions, one must achieve representative sampling in the ash stream, comparability of unburned carbon to loss-on-ignition (LOI) with various fuel types, a quality control regime to ensure the accuracy of the on-line measurement system in comparison with laboratory standards and auditing of the QC process.
Steam Generator Replacement Project at TVA’s Sequoyah Unit 1 Nuclear Power Plant
Authors: Anderson Myron R.
Published: November 2008

Pressurized Water Reactor Power Plants have at times required that large components be replaced (steam generators weighing 750,000 lbs) which have necessitated performing first time modifications to the plant that were unintended during the original design. The steam generator replacement project at Tennessee Valley Authority (TVA’s) Sequoyah Nuclear Power Station necessitated (1) two large temporary openings (21’×45’) in the plant’s Shield Building roof (2’ thick concrete) by hydro-blasting to allow the removal of the old generators and installation of the new, (2) removal and repair of the concrete steam generator enclosure roofs (20’ diameter, 3’ thick) which were removed by wire saw cutting and (3) the seismic qualification of; the design and construction of an extensive ring foundation for; the use of one of the world largest cranes to remove these components through the roof. This removal and replacement process had to be performed in an expeditious manner to minimize the amount of time the plant is shutdown so the plant could return to providing power to the grid. This paper will address some of the many technical and construction considerations required to perform this demolition and repair work safely, efficiently and in a short as possible duration.
Combined Cycle Plant Performance Monitoring
Authors: McClintock Michael , Cramblitt Kenneth L.
Published: November 2008

Monitoring thermal performance in the current generation of combined cycle power plants is frequently a challenge. The “lean” plant staff and organizational structure of the companies that own and operate these plants frequently does not allow the engineering resources to develop and maintain an effective program to monitor thermal performance. Additionally, in many combined cycle plants the highest priority is responding to market demands rather than maintaining peak efficiency. Finally, in many cases the plants are not designed with performance monitoring in mind, thus making it difficult to accurately measure commonly used indices of performance. This paper describes the performance monitoring program being established at a new combined cycle plant that is typical of many combined cycle plants built in the last five years. The plant is equipped with GE 7FA gas turbines and a GE reheat steam turbine. The program was implemented using a set of easy-to-use spreadsheets for the major plant components. The data for the calculation of indices of performance for the various components comes from the plant DCS system and the PI system (supplied by OSIsoft). In addition to the development of spreadsheets, testing procedures were developed to ensure consistent test results and plant personnel were trained to understand, use and maintain the spreadsheets and the information they produce.
Spectroscopic Analysis of Fuel Lean Flames for Propulsion Applications
Authors: Gautam Vivek , Gupta A. K.
Published: November 2008

Chemiluminescence and thermal imaging techniques have been used to examine the chemical and thermal behavior of turbulent flames with practical application to TBCC propulsion systems. The present study examines single swirler using an experimental double concentric swirl burner that simulates one swirler in a practical gas turbine combustor. The optical emission spectroscopy (OES) technique have been used to provide information on selected species in flames that mark the flame reaction zone and heat release rate. The instantaneous images are then integrated to obtain time-averaged information. Spatial distribution of OH, CH, C2 species from within the flames have been obtained at selected wavelengths using an ICCD camera and narrow band interference filters. The vibrational temperature distributions are obtained from the ratio of intensities of two discrete C2 bands of 470nm and 515nm. The time-averaged spatial distribution of flame generated radicals is processed using the Abel Inversion technique to project the initial 2-D image to represent the 3-D distribution of species and temperature in the flame. The results show that swirl distribution affects the shape of the spatial distribution by spreading the high intensity regions radially outwards with increase in swirl strength at inner regions of the fuel injector. Co-swirl distribution in the burner provided decrease in temperature and species intensity due to greater entrainment of the surrounding fluid. Calculated flame thermal strain rates were found to be significantly different for the co- and counter-swirl flames.
Flow Dynamics of Unconfined and Confined Swirl Stabilized Gaseous Flames
Authors: Archer S. , Gupta A. K.
Published: November 2008

Three-dimensional (3-D) flowfield data has been obtained using Particle Image Velocimetry (PIV) for varying swirl distributions in the burner. The 3-D data also allows one determine the local swirl number of the resulting flow. Flow characteristics of the resulting flowfield, both without and with combustion, have been examined for the effect of co- and counter-swirl under lean direct injection conditions using unconfined and confined combustor geometry. Experimental results of the effect of swirl and combustion are presented to simulate the flow dynamics of Lean Direct Injection (LDI) configuration gas turbine combustion. The selected configuration is typical because it does not make use a premixing zone and relies totally on the swirl and the injector to accomplish rapid mixing. Specifically, the effect of radial distribution of combustion air and swirl in a burner are examined under non-burning and burning conditions using propane as the fuel. The present study explores single swirler interaction with the use of an experimental double concentric swirl burner that simulates one swirler of a practical gas turbine combustor. Results showed that both swirl and combustion has significant effect on the characteristics of the internal and external recirculation zones. The calculated local swirl number differs significantly form that estimated using geometrical relationship derived from the vane angle only. The effect of combustion for the confined and unconfined geometries was also been found to be different. In the confined geometry combustion decreases the size of the recirculation zone. This is in contrast to that found for the unconfined conditions. Combustion enhances the recirculation zone in the unconfined geometry. Combustion provides greater velocity magnitudes than their counter non-combustion conditions. The counter-swirl combination resulted in smaller and more well defined internal recirculation regions. The results provide the role of swirl and combustion on the mean and turbulence characteristics of flows over a range of swirl and shear conditions between the inner and outer flow of the burner. This data provides important insights on the flow dynamics in addition to providing data for model validation and model development.
Are Your Pumps Operating at Optimum Efficiency?
Authors: Gairola Vidhu S.
Published: November 2008

Pumps are the lifelines of any process industry. When pumps fail, processes stop. A power plant runs smoothly when pumps such as boiler feed, condensate, cooling water are healthy. Power plants must operate at optimum levels to be profitable. Operating costs for pumps fall in two categories that are related — operational and maintenance. Bad operation leads to high maintenance, and inadequate maintenance leads to inappropriate operation! In spite of having the same objective of keeping the plant operating at optimum levels, the approach of the two groups towards this objective may differ significantly leading to inefficiencies. What can be done to alleviate this problem and achieve the goal of the plant? This paper provides a simple yet lucid explanation of the pump operation and issues that must be addressed to achieve optimum operation and realize savings.
Multi-Pollution Removal System Using Oxides of Manganese
Authors: Boren Richard M. , Hammel Charles F. , Bleckinger Mark R.
Published: November 2008

Pending legislation suggests there will be a need for increased removal of NOx, SO2, Hg (Mercury) and PM 2.5 from coal-fired power plants. Current commercial technologies only handle one of these pollutants so several different technologies must be combined to remove all of these pollutants. The Pahlman™ Process developed by Enviroscrub Technologies removes NOx, SO2 and Hg in one step. The Pahlman™ Process is a sorbent-based technology, which utilizes a proprietary Oxides of Manganese compound to remove SO2, NOx and Hg. The sorbent is spray-dried into the exhaust duct downstream of the current particulate control device. Spray drying is used to control the particle size (40 micron mean) and increases the surface area of the particle (∼300 m2 /gram). The sorbent is collected in a fabric filter baghouse, which serves two purposes: (1) it captures the entrained sorbent and (2) provides additional residence time for gas-solid contact between the sorbent and the target pollutants. The loaded sorbent is removed from the baghouse and routed to regeneration. Sorbent regeneration occurs in an aqueous solution under temperature and pressure while the solution is maintained in the proper pH and Eh ranges. The reacted manganese is oxidized back to its starting state and sulfate and nitrate byproduct compounds are produced. The insoluble oxides of manganese are then filtered out of the solution and returned to the spray-dryer for re-use. The soluble sulfate and nitrate compounds are separated and the nitrate by-products are sold as fertilizer. The sulfates are further processed and re-used in the regeneration process with excess sulfate by-products sold as fertilizer or used to produce sulfuric acid. Testing over the last three years has resulted in consistent SO2 removal of over 99% and NOx removal of greater than 95%. Testing performed in June 2003 at DTE Energy’s River Rouge Power Station Unit#3 in Detroit, Michigan showed removal rates of >99% for SO2, >98% for NOx and 97% for oxidized Mercury (Hg2+). Mercury testing was performed by the Energy and Environmental Research Center (EERC) and paid for by DTE Energy and the DOE. Testing performed in December 2003 through January 2004 at Minnesota Power’s Boswell Energy Center Unit#4 in Cohasset, Minnesota showed removal rates of >98% for SO2, >94% for NOx and 99.2% for elemental (Hg0) and 94% for total Mercury (HgT).
Multi-Pressure Surface Condenser Performance Evaluation: A Case Study
Authors: Sunder Raj Komandur S.
Published: November 2008

Surface condensers for power plant applications are generally specified and designed following turbine-condenser optimization studies. The turbine manufacturer provides turbine-generator performance data (thermal kit) at the very outset of plant design when the condenser is usually a black box and not much is known about its design. The turbine-generator guarantee would then be based on a specified condenser pressure that may or may not be attainable once the condenser is actually specified and designed. The condenser pressure used for the turbine performance guarantee might assume a single-pressure condenser while the actual design might be a multi-pressure condenser. In order to properly predict and monitor the performance and conduct diagnostics on a multi-pressure condenser, it is important to understand the design basis and develop an accurate model using performance modeling tools. The paper presents a multi-pressure condenser case study for a 600 Mwe nuclear power plant. The paper discusses the design basis used, interface between the turbine and condenser, use of a performance modeling tool for predicting performance, determining capacity losses attributable to the condenser and conducting diagnostics.
Optimizing Compliance Cost for Coal-Fired Electric Generating Facilities in a Multipollutant Control Environment
Authors: Staudt James E.
Published: November 2008

Higher natural gas prices have increased the importance of coal-fired generation at a time when environmental uncertainty is raising the risks of operating coal-fired units. The likely need for increased investment in environmental control technologies comes at a time when many electricity generators are under great financial stress. This combination of forces makes a structured and comprehensive approach to assessing compliance strategies essential to managing generating assets. The approach needs to incorporate the high degree of uncertainty that can be otherwise buried in key assumptions, such as regulatory requirements, market pricing of allowances, plant capacity factor, wholesale electric prices, etc. The approach should also facilitate testing of assumptions under a range of scenarios to allow for flexibility in possible compliance strategies. In this paper an approach for evaluating compliance risks and quantifying the potential costs under various scenarios will be described. The approach integrates market-based compliance mechanisms with capital improvements in control technology while providing methods to address the uncertainty of key assumptions. The approach facilitates optimizing the balance between market-based and technology-based compliance approaches so that the environmental compliance risk profile can be tailored to the specific situation. A unique feature of this approach is that it incorporates the effects of the market risk associated with emissions markets along with market derivative instruments designed to manage risk, while also incorporating comprehensive technology analysis so that costs and risks can be well quantified under any regulatory scenario. The approach lends itself to active scenario review to facilitate flexibility in decision making while avoiding premature commitments.
Minimizing the Impact of SCR Catalyst on Total Generating Cost Through Effective Catalyst Management
Authors: Staudt James E.
Published: November 2008

For coal-fired boilers equipped with Selective Catalytic Reduction (SCR) NOx reduction technology, direct catalyst cost contributes to a major operating expense. Decisions regarding catalyst management have other significant impacts to generating cost, including outage time and frequency and parasitic load. Strategies for minimizing the impact to total generating cost while preserving system performance — generally referred to as catalyst management — are receiving greater attention. Approaches to managing catalyst can vary widely. Therefore, analysis of catalyst management strategies requires accurate predictive tools for assessing SCR system performance that have the flexibility to address a wide range of scenarios. These predictive tools may also be used to investigate performance issues that facility operators may encounter. However, until recently, operators have not had access to these tools, except through catalyst suppliers or consultants. In this presentation, various catalyst management strategies will be examined. Using an analysis tool recently adopted by several power plant operators and SCR technology suppliers, we will illustrate how such a tool can be used to optimize a catalyst management strategy to minimize the total cost of generation. Comparisons of model results to measured SCR performance at operating facilities will be presented. The model will be used to show operating trade offs for SCR operating parameters, such as NOx reduction, ammonia slip, catalyst outage frequency, catalyst usage, and parasitic load under a variety of scenarios. We will also discuss how the tool can be used to diagnose operating problems.
Power Augmentation of Heavy Duty and Two-Shaft Small and Medium Capacity Combustion Turbines With Application of Humid Air Injection and Dry Air Injection Technologies
Authors: Nakhamkin Michael , Pelini Robert , Patel Manu I. , Wolk Ron
Published: November 2008

This paper presents the latest information on Humid/Dry Air Injection (HAI/DAI) power augmentation technology for Combustion Turbine (CT) and Combined Cycle (CC) power plants. It describes: • The summary of the latest activities on the implementation of HAI and DAI technologies including results of the validations tests conducted on the PG7241 (FA) combustion turbine, and findings of various CT-HAI implementation projects. • The technical background including the latest CT-HAI and CT-DAI concepts resulting in the performance improvements and reduced emissions. • A novel concept for humidification of the injected air that further reduces overall capital costs by 15%. • The novel approach for the power augmentation of two-shaft small and medium capacity CTs with application of HAI and DAI technologies. Two-shaft CTs are widely used for electric power generation, including distributed generation, as well as a variable-speed mechanical driving engine including driving natural gas (NG) pipeline compressors (PC).
Capacity Losses in Nuclear Plants: A Case Study
Authors: Sunder Raj Komandur S.
Published: November 2008

Nuclear power plants are licensed to operate at a fixed rating of reactor core thermal power. Capacity losses that occur may be attributable to one or more sources such as feedwater flow nozzle fouling, cycle isolation problems, malfunctioning equipment, etc. Depending upon the severity and extent of the problems, the losses could be substantial. Using a case study for an 800-Mwe nuclear power plant, the paper examines some of the sources of capacity losses that could occur and quantification of the losses. The use of a performance modeling tool in analyzing the losses is presented. Since various plant parameters are impacted when these losses occur, their importance in monitoring performance and serving as diagnostic tools is discussed.
Economical and Environmental Aspects of Heat Pump System Utilizing Unused Energy in Aquarium
Authors: Okamoto Satoru
Published: November 2008

This paper introduces a heat pump system with a latent heat storage utilizing seawater installed in an aquarium. Heat from the seawater is collected and used as the heat source for the heat pump system. This maintains the indoor conditions at constant temperature and relative humidity. With regard to the heat pump system using low-temperature unutilized heat source, development is introduced on a heat source load responsive heat pump system, with combines a load variation responsive heat pump utilizing seawater with a latent heat (ice plus water slurry) storage system using nighttime electric power serving for electric power load leveling. The desired outcome would be to show that the costs of generating heat energy with the seawater-source heat pump are significantly less than those with the air-source heat pump and the oil-fired system. Additionally, the CO2 emissions for the seawater-source heat pump compare favourably as they maybe less than those for the other conventional assumed systems described.
Common Design Deficiencies in Counterflow Cooling Towers
Authors: Cruz Hector L.
Published: November 2008

One of the best methods for insuring a power plant will produce its guaranteed base load is to have an excess of circulating cold water or at least the expected guaranteed cold water temperature throughout the year. Yet, within industry today, numerous mistakes continue to be made when purchasing a cooling tower, by both the Subcontractor, and the Contractor. Only following only normal design criteria established by cooling tower Subcontractors, or an industry association, is not sufficient. Guidelines in the cooling tower industry have been established to set forth minimum standards that have helped to eliminate obvious past deficiencies. They were not established to protect the Subcontractor. Nor were they established to guarantee the Contractor receives what is thermally and mechanically necessary for a given project. Design of a cogeneration or industrial plant does not always consider the necessary requirements on a cooling tower over the range of expected operation. This type of design for a cooling tower is more complicated than the single guarantee point operational design of a power plant that is the current norm. Just as the Contractor needs to consider how to meet the thermal energy requirements over the range of expected operation of the plant, the Subcontractor of the cooling tower must do the same. Contractors must be aware that the cooling tower designer does not consider aspects that are often applicable to cogeneration plants and therefore they must include exceptions to the Subcontractors’ optimized offering in their standard cooling tower specifications. These exceptions in no way disagree with the Codes and Standards adopted by the cooling tower industry or any governing agency. This paper will address exceptions that the power plant and cooling tower designer needs to take into consideration to ensure that a reliable supply of cold water relates to the thermal duty requirements from the plant throughout the year.
The First Commercial Ocean Thermal Energy Conversion Power Plant: Taking a Renewable Energy Technology Project From Concept to Commercial Operation
Authors: Loria Dennis , Nicholson Robert , Sullivan Edward
Published: November 2008

Ocean Thermal Energy Conversion (OTEC) is one of the few renewable energy technologies that can provide an unlimited source of continuous, electric power. Sea Solar Power (SSP) is currently involved in a coordinated design and commercial development effort that will bring their patented SSP OTEC cycle to commercial operation in 2007. The SSP OTEC cycle not only provides continuous electric power, but also provides large quantities of desalinated water, which is even more valuable than electricity in many countries and islands. The first 10 MW land-based SSP plant is now being developed for application on an island in the Caribbean. (Negotiations are ongoing, so the location cannot be disclosed at this time, but will be disclosed when the paper is delivered at the conference.) This paper will review the on-going efforts that will bring this technology to commercial operation and the potential benefits of this technology. The technology is based on a proprietary binary Rakine thermodynamic cycle that utilizes the temperature difference between warm surface water and cold deep sea water. These temperature differentials are unique to the Tropics. The 10 MW landbased SSP plant will also provide 11,355 cubic meters-per-day (3 million gallons-per-day) of desalinated water. Another beneficial byproduct of this technology is the ability to support mariculture, or fish-farming, using the nutrient-rich deep seawater. Mariculture can provide food for thousands of people and enhance the economy of the host country, as an export commodity. R. W. Beck is supporting the design of the standard, 10 MW land-based plant for this application and is also supporting the commercial development activities of SSP.
On the Modeling of Transient Combustion and Heat Transfer Characteristics in Furnaces
Authors: Kameel Ramiz , Khalil Essam E.
Published: November 2008

This paper describes a numerical method that was designed to calculate and predict the flow characteristics in three-dimensional furnace configurations at high Reynolds numbers under steady and unsteady conditions. The paper introduces a new (non-commercial) Computational Fluid Dynamics (CFD) program (3DTCOMB) that is capable of adequately predicting the furnaces. The time dependent nature of the flame propagation in furnaces is described and explained in the present work through a “squashing and stretching” process. The agreements between the obtained numerical predictions, based on the Arrhenius reaction model and the corresponding experimental results are shown to be qualitative in nature. The computed flame characteristics at various time intervals are to be used for future development of the combustion models on a large-scale furnace.
What Powers the Chevrolet in 2030?
Authors: Hill Richard C.
Published: November 2008

“The Annual Energy Outlook 2003” from the Energy Information Administration indicates an annual petroleum consumption of 38.5 quads with 25.7 quads imported. The transportation sector uses 26 quads, or 67% of the total. No other sector (residential, commercial or industrial) of our society has this level of dependence on petroleum. Electric power generation, for example, has less than 5% of its output dependent on petroleum. Recent energy policy has focused hydrogen as the next generation transportation fuel. Will this alternative stand technical scrutiny? What are the options? Do those of us laboring in the technology vineyard have a responsibility to speak out publicly on these options?
Improving Coal-Fired Power Plant Performance and Operating Flexibility Today
Authors: Termuehlen Heinz
Published: November 2008

Since 50% of the electric power in the US is generated by pulverized-coal-fired power plants and 95% of the US fossil fuel reserves are coal, immediate action should be taken to improve coal-fired power plant performance. The DOE has started a program to develop most efficient coal-fired power plants with the goal to reach 60% net power plant efficiency. Present coal-fired power plants are mainly designed and built more than 30 years ago with a net power plant efficiency of about 32%. We should not wait for a general application of a future technology with the potential of reaching the 60% net efficiency level of coal-fired power plants. We must take action today and build more advanced pulverized-coal-fired power plants based on a technology, which has already gained operating experience and is commercially available. This paper shows how such power plants can be built as new units or as units replacing outdated units. A power plant net efficiency of 45% can be achieved even with highly effective emission reduction systems already included. The 40% lower specific coal consumption of these plants over present units reduces also the CO2 discharge by the same magnitude. Coal-fired power plants can also be designed for proving high operating flexibility. They can support the grid system in case of grid disturbances and can also stay at idle operation after full-load rejections for immediate reloading. Therefore, blackouts can be avoided. This paper provides detailed information on how to build such advanced pulverized-coal-fired power plants.
Turbine Blade Fatigue Crack Growth
Authors: Salzman Ronald N. , Rieger Neville F. , Wang Letian
Published: November 2008

This paper presents an approach that has not previously been applied to predict power plant component fatigue failure. While many computer tools and procedures do exist for life prediction, recent experience shows that those methods often lack needed precision. In addition detailed knowledge of the material fracture mechanics properties and of the component load history, including the sequence of events. For complex load applications the sequence of events has been shown to be significant. For these applications Linear Damage Models (Minors Rule) are inadequate. A case where the accuracy of existing methods was found to be insufficient involved a steam power plant. Fatigue cracks were observed in the blade root area of 10% of the L-0 row turbine blades. The cracked blades were removed and replaced with new blades. The question to be answered was how safe are the reinstalled blades that had no visible damage. A successful solution was obtained by integrating NASA technology with STI experience in the analysis of steam and gas turbine blades. This led to the development of a proprietary, advanced life prediction computer code that: • incorporates contributions from both HCF and LCF to calculate crack growth, • treats the actual sequence in which all HCF and LCF loading has been applied, and • initiates the crack growth process from the microscopic inclusions and flaws. Complete analysis included comprehensive material tests, performed at a qualified material-testing laboratory. Test specimens were created from actual components, which had been subjected to over 30 years of service. Realizing that fatigue testing data variations can be relatively large, results from Life Cycle showed solid agreement with both short-term (105 to 106 cycles) material tests and with long-term (∼160×109 cycles) operation under high strain steady load and low strain cyclic load conditions.
Rewind and Core Restack of AEP Conesville #5 Generator
Authors: Timperley J. , Michalec J. , Moore W. , Moudy H. , Hutt J.
Published: November 2008

This paper presents an overview of the design and field installation events involved in rewinding and restacking AEP’s Conesville #5 generator. This style of generator, commonly known as a “double tube stack” machine, has been susceptible in the past to stator end winding vibration, stator coil and core deterioration, and phase lead problems. Following tests and inspections, AEP decided to rewind this generator in anticipation of the consequences of these problems. Successful pro-active maintenance, which included a complete stator rewind and stator core restack, prevented a costly forced outage. Root cause analysis of the coil failures are described, as well as details of the core laminations problems. Specific design enhancements over and above the original design will be discussed. In addition, details of the existing core damage will be discussed, as well as procedures used for core restacking. Fiber optic monitoring instruments were installed on the coil ends and the phase leads after the new coil installation was complete. Results of these initial readings will be shared. Successful startup and continued operation of this unit demonstrates that refurbishment of these large generators with inner gas cooled technology is reliable and cost-effective over other alternatives, such as conversion to water cooled technology.
Effect of Inlet Air Refrigeration on the Performance of Combined Cycle Power Plants
Authors: Srivastava G. , Yadav R.
Published: November 2008

In the present work an attempt has been made to study the effect of inlet air refrigeration on the performance of combined cycle power plants. The inlet air cooling for the chosen combined cycle configuration may be done by means of employing a refrigeration system such as vapor compression and vapor absorption system, which derive the energy input from the system itself. In the vapor absorption system, the input energy to generator is given by three possible heat source from the system namely from the gas turbine exhaust, steam bled from steam turbine and exhaust gas from the exit of heat recovery steam generator (HRSG). It has been observed that the vapor absorption system with HRSG exhaust as heat source to the generator is the better option followed by the vapor compression refrigeration system for compressor inlet air cooling. The cooled compressed inlet air up to 280K from 300K improves the plant specific work around 4% and plant efficiency around 0.39 percentage point for the combined cycle using vapor compression system.
Generator Performance Plus™ Hydrogen Seal System
Authors: Rice P. C. , McNickle A.
Published: November 2008

The authors’ companies have collaborated to develop an advanced oil seal assembly for hydrogen-cooled generators. This new technology addresses our industry’s needs to reduce oil and hydrogen consumption, improve seal life, and upgrade existing seal technology.
Comparative Analysis of Advanced H2/Air Cycle Power Plants Based on Different Hydrogen Production Systems From Fossil Fuels
Authors: Gambini M. , Vellini M.
Published: November 2008

In this paper two options for H2 production by means of fossil fuels are presented, evaluating their performance when integrated with advanced H2/air cycles. The investigation has been developed with reference to two different schemes, representative both of consolidated technology (combined cycle power plants) and of innovative technology (a new advance mixed cycle, named AMC). The two methods, here considered, to produce H2 are: • coal gasification: it permits transformation of a solid fuel into a gaseous one, by means of partial combustion reactions; • steam-methane reforming: it is the simplest and potentially the most economic method for producing hydrogen in the foreseeable future. These hydrogen production plants require material and energy integrations with the power section, and the best connections must be investigated in order to obtain good overall performance. The main results of the performed investigation are quite variable among the different H2 production options here considered: for example the efficiency value is over 34% for power plants coupled with coal decarbonization system, while it is in a range of 45–48% for power plants coupled with natural gas decarbonization. These differences are similar to those attainable by advanced combined cycle power plants fuelled by natural gas (traditional CC) and coal (IGCC). In other words, the decarbonization of different fossil fuels involves the same efficiency penalty related to the use of different fossil fuel in advanced cycle power plants (from CC to IGCC for example). The CO2 specific emissions depend on the fossil fuel type and the overall efficiency: adopting a removal efficiency of 90% in the CO2 absorption systems, the CO2 emission reduction is 87% and 82% in the coal gasification and in the steam-methane reforming respectively.
The Effect and Remedy of Nozzle Loads on Boiler Feed Pumps
Authors: Flory Alan P. , Livoti William C.
Published: November 2008

Many frequently encountered start-up and operational problems in current design combined cycle power plants can be traced to pipe strain and nozzle loads placed upon pumps. This is most dramatic when the boiler feed pump is affected. Many of the symptoms are significant and can include misalignment, dynamic (changing) alignment, pump or motor vibration, bearing problems, mechanical seal failures and seizure of equipment on start-up and shutdown. While these are all nuisance items that can plague plant shake-down and commissioning, some can generate huge costs and plant unscheduled outages. More profoundly, these symptoms are often all present, making accurate diagnosis of the true cause very difficult. The real cost of these problems can be seen in plants missing commercial operation dates. Some of the piping issues that can cause these symptoms will be discussed, items including hydraulic aspects of the piping design, straight runs, horizontal runs, venting, location of minimum flow valve, and pipe hanger location. Also, the use of pre-fabricated pipe and spool pieces will be discussed. A short discussion will also be presented on how these piping issues impact various designs of pumps, such as barrel pumps, horizontal split case and ring section type pumps. This will also include some comments on pump mounting issues such as base-plate installation, the use of pin & key blocks and pedestal design. All of the discussions will be summarized and then presented with several recommendations for piping repair, operational changes, and material reinforcement. Optional pump features will be presented, indicating what items can be used to improve operation and reliability when abnormal nozzle loads are expected, including comments on internal clearances, wear part metallurgy and bearing upgrades. These recommendations will be compared against several field experiences for confirmation, with some focus on nozzle load data vs. design, and operation prior to and after strain removal. This combination of field results and engineering analysis of this topic should prove quite useful to the engineer attempting to diagnose any symptoms found in the field. Often times several symptoms may be present, making diagnosis difficult and it is only the methodical steps of symptom elimination that will get the new power plant on the way to commercial operation.
Performance Improvement of a Simple Gas Turbine Power Station Using Pulse Combustion Technology
Authors: Gadalla Mohamed A.
Published: November 2008

The retrofitting projects have been considered in many countries to convert simple gas turbine units into more advanced cycle units with higher efficiency and higher output. Among many proven technologies, such as inlet air cooling, intercooling, regeneration, reheat and steam injection gas turbine etc., pulse combustion is one of the promising technologies in boosting both the output capacity and thermal efficiency, and reducing carbon and nitrogen oxides emissions without additional pollution control equipment. This paper presents the analysis of potential and real benefits of pulse combistion technology applied in the combustion process of a simple gas turbine cycle under different operating conditions. In addition, this study investigates the utilization of converting part of chemical energy of fuel into pressure energy in the gas turbine pulse combustion chamber. The influence of the maximum pressure rise due to pulse combustion (pre-compression parameter), the ratio of combustion heat released in the isochoric process, maximum cycle temperature, and compressor pressure ratio on the performance paramenters such as net work output, cycle thermal efficiency, and fuel consumption were also investigated. Finally, the results of comparative analyses between a simple gas turbine cycle utilizing a pulse combustor and a conventional cycle show the thermodynamic advantages of applying this technology in simple gas turbine power cycles.
Mobile Nitrogen Pumper: A Valuable Tool
Authors: Daily Joseph V.
Published: November 2008

This paper describes a unique piece of equipment for delivering nitrogen gas. This equipment is used for supplying nitrogen on a temporary basis and capable of delivering an extremely wide range of pressure, flow, and temperature requirements. In the electric utility industry, “temporary nitrogen supply” has been mostly associated with the use of banks of pressurized cylinders or tube trailers. Both have definite limitations with overall volume capacity and flow rates. These delivery systems tend to be time consuming, require multiple refill deliveries, and lack cost effectiveness. The general awareness of the existence of mobile nitrogen pumping equipment and the potential value it provides is relatively limited within the electric power industry. Recently, however, this equipment has been used successfully as a cost saving alternative for selected applications. One such example is to replace natural gas for fuel line blow cleaning and “target testing” during the construction phase of natural gas fired combustion turbines. The mobile nitrogen pumping equipment effectively duplicates the flow and sonic velocities achieved using natural gas while conforming to the established “target testing” specifications. The primary benefits of using nitrogen in lieu of natural gas or air are cited to be enhanced safety, environmental considerations, and overall time/cost savings. A description of this equipment is offered including the flow rate, pressure, and temperature specifications. Additionally, examples are given of a program that predicts nitrogen gas velocities throughout the natural gas delivery piping system under steady flow conditions. This includes velocity changes as the piping system diameter changes. Specific data is offered comparing the velocity differences between natural gas and nitrogen under the same steady state flow rate conditions. Case studies are offered that detail the successful use of this mobile nitrogen pumping equipment for line blowing and “target testing” during the pre startup phase of combined cycle plants.
Comparison of Products of Incomplete Combustion of Waste Polystyrene and Styrene in Diffusion Flames and Ethyl Benzene in Fuel-Rich Premixed Flames
Authors: Ergut Ali , Levendis Yiannis A. , Carlson Joel
Published: November 2008

This study examined the effects of the mode of combustion of waste polystyrene (PS) on the emissions of products of incomplete combustion (PIC). Typically, combustion of PS in furnaces takes place with diffusion flames forming around devolatilizing chunks (pieces, shreds, pellets, etc.) of the solid polymer. In such flames a broad range of local fuel/air equivalence ratios exist, at any given instant of time. The inner side of a diffusion flame is fuel-rich and the outer side is fuel-lean, making it impossible to assess local conditions. Results are typically reported on the basis of a global equivalence ratio, φglobal, which is calculated based on the total amounts of fuel and air consumed in combustion. To examine the effects of local equivalence ratios, φ, on pollutant emissions, premixed flame combustion is necessary. In this investigation emissions from batch combustion of solid PS pellets in fixed beds, placed inside a horizontal furnace, are compared with emissions from steady-state steady-flow combustion of PS particle clouds (aerosols), inside a vertical furnace. Sampling was conducted at the exits of the furnaces. In addition, effluents from both diffusion and premixed flames of PS precursors are also compared. Liquid styrene is the monomer precursor of polystyrene; it is also the most abundant pyrolyzate. It was burned in batches inside the horizontal furnace. However, because of its unstable, often explosive combustion ethyl-benzene was chosen for the premixed combustion experiments. This choice was based on work conducted elsewhere, which showed that in flames the conversion of ethyl-benzene to styrene is extensive and extremely fast. Ethyl-benzene was pre-vaporized in nitrogen, mixed with oxygen and nitrogen, and burned in a flat flame burner. Fuel-rich conditions (φ = 2.5) were implemented to enhance the product yield. Product sampling was conducted in the luminous region of the premixed flame.
Nonlinear Investigation of the Effect of Primary Suspension on the Hunting Stability of a Rail Wheelset
Authors: Mohan Anant , Ahmadian Medhi
Published: November 2008

The mathematical model of a single railway wheelset moving with constant speed on a smooth, level, and tangential track is used to numerically investigate the nonlinear dynamics of the wheelset. Nonlinearities in the wheelset model include the nonlinear wheel-rail profile and the friction-creep characteristics of the wheel-rail contact geometry. Wheelset numerical simulations consider single-point and two-point wheel-rail contact scenarios. Sensitivity of the critical hunting velocity to primary stiffness and damping parameters is examined. Results of the lateral stability study indicate that the critical hunting velocity of the wheelset is most sensitive to the primary longitudinal and lateral stiffness. Methods involving semi-active and active control of the primary longitudinal stiffness are developed to raise the critical velocity of hunting. These approaches are seen to considerably increase the wheelset critical hunting velocity.
Determination of Traction Power Distribution System Impedances and Susceptances for AC Railroad Electrification Systems
Authors: Kneschke Tristan , Mbika Phonigi
Published: November 2008

Electrical characteristics of the traction electrification system, together with the train power demand, headway, and operating scenario, are the key factors in determining the overall system performance. A mathematical procedure for calculation of traction power distribution system line impedances and capacitances is developed using the Alternative Transient Program (ATP). The technique is applied to Direct Feed and Autotransformer Feed traction electrification systems and typical results for one-, two-, three-, and four-track railroads are presented. All self-and mutual impedance and capacitance components are included in the calculations.