bluuebunny/crossref_metadata_2025 huggingface dataset:
Investigation Into Optimal Operation of BCHP Systems in the Air-Conditioning Season
Authors: Cao Jiacong , Fang Hong
Published: October 2008

Building cooling, heating and power generation (BCHP) is important for the sustainable energy strategy in China because of its contribution to energy conservation and the reduction of CO2 emissions. The number of BCHP or small-scaled combined cooling, heating and power generation systems that have been put to use or are in the course of construction is steadily increasing in China. However, in many cases the performance of BCHP systems is not good enough, i.e., the average real exergetic efficiency of whole system is much lower than expected and the economic effect is not satisfactory. This is a problem that perplexes designers and plant owners and need be investigated so as to increase the knowledge of optimizing the operation of BCHP systems. In this paper the performance of a typical BCHP system is investigated using thermodynamic and thermoeconomic analyses based on the simulating results of off-design operation and the solution of performance optimization of the system. With the help of a great number of real running data of the system and the master data supplied by manufacturers, a model of the system operation is developed to simulate the whole domain of operation on off-design conditions. In order to shorten computer time the operation domain is described by a set of functions obtained by curve fitting using the numerical data from the simulation. Two models of optimization, of which the objective functions are the exergetic efficiency and gross benefit of the whole BCHP system separately, are established in virtue of these fitted functions. The simulation of off-design operation and the solution of the optimization problems supply a great number of useful data that form various graphs, which are to be the references to energy conservation and economic operation of the systems. The investigation indicates that there are some differences between the optimum working conditions obtained by the two optimization models, whereas it is inevitable that the system runs with some lower efficiency and less gross benefit when working at high cooling or heating load factors. By analyzing the data some significant conclusions are obtained, which will be helpful for the BCHP industry in China.
Renewable Energy Powered Rural Community Development Centres in the Developing Countries
Authors: Islam Mazharul , Amin M. Ruhul , Islam A. K. M. Sadrul
Published: October 2008

People in the developing countries who lack basic services and economic opportunities are primarily concerned with improving their living conditions. At present, unemployment problem in the rural areas of the developing countries are diversifying the moral values and social responsibilities of unemployed youth. To solve the problem, rural development centres (involving vocational training, IT services and other productive activities) can contribute significantly for the upliftment of these rural youths and can transform them into grass-root entrepreneurs. One critical factor hindering the establishment of such rural development centers is access to affordable and reliable energy services. Under this backdrop, environmentally benign renewable energy systems can contribute significantly in providing much needed energy in the unserved or underserved rural development centers in the developing countries to achieve both local and global environmental benefits. The paper demonstrates that energy deficient, economically backward communities in the off-grid areas of the developing countries, can be given an array of opportunities for income generation and social progress through rural development centers with the aid of renewable energy sources (such as wind, solar photovoltaics, solar thermal, biomass and micro-hydro), thereby improving their standard of living. Poverty alleviation in rural areas can be accomplished and the critical role of access to adequate level of energy services, Information Technology (IT) and modern communication facilities in it demonstrated. Furthermore, the production, implementation, operation and maintenance of renewable energy applications being labor-intensive, will also result in job growth in the village context, preventing migration of labor force, especially of young men, from rural areas to overcrowded industrial areas. An appropriately designed renewable energy systems can also have a significant role in reducing the impact of climate change through non production of green house gases.
Village of Freeport Generation Project Implementation
Authors: Bianco Hubert M. , Bender Peter A.
Published: October 2008

Freeport Electric is one of only three Long Island-based, New York State municipal electric utilities that self-generate its electrical needs. A member of the New York Association for Public Power, the utility serves a community of over 45,000 people with a diverse customer base of approximately 15,000 residential, commercial and municipal customers. Freeport Electric’s energy costs are among the lowest on Long Island.
Lessons Learned for Combustion Turbine Power Projects
Authors: Lyda Charles D.
Published: October 2008

Lessons Learned have long been used to refine designs and work practices. In recent years, litigation has caused this effort to be reviewed in terms of worth versus liability. Even the best-managed Lessons Learned program can have a negative impact to a company’s bottom line. This paper is intended to promote the beneficial rewards of, without regard for liabilities associated with, “Lessons Learned”.
Feasibility of Site Balancing Rewinded 2-Pole Turbo Generators
Authors: Angantyr Anders
Published: October 2008

At power plants with large distances to workshops and balancing facilities the outage time for rewinding of a generator rotor may be considerably reduced if the work can be carried out on site. However a problem arises when balancing is concerned. If the rotor is balanced on site, i.e. in the stator and driven by the turbine, the balancing weights at the rotor body are not accessible. This constraint and the critical speeds of the rotor determine the feasibility to achieve an acceptable balancing state. This paper first presents estimates of the expected unbalance introduced by rewinding based on the balancing weight distribution for a set of rewinded rotors. These estimates are then applied to a rotordynamical model and a search algorithm is used to see what can be achieved by balancing in the accessible balancing planes. Several numerical examples are studied. Finally, some guidelines for feasibility of site balancing rewinded turbo generator rotors are defined based on the numerical results.
Automatic Fire Protection of Turbine-Generator Bearings at Joppa Generating Station
Authors: Bafford R. Dean
Published: October 2008

Electric Energy Inc.’s Joppa generating station has six 181 MW coal-fired units located on the bank of the Ohio river in Massac county, Illinois. The original GE turbine-generators were installed in the early 1950’s without any fire protection for the bearings. In 1998, Securiplex watermist systems were installed on units 5 & 6 to protect the bearing areas of those turbine-generators from fires. The fire detection was done using VESDA air sampling technology. In subsequent years, Securiplex watermist – VESDA systems were installed on the remaining four units to protect the bearing areas of those turbine-generators. This paper explains the factors that went into the decision to install this type of fire suppression technology as opposed to conventional sprinkler or deluge systems. Operating and maintenance experience with the Securiplex watermist systems and the VESDA fire detection systems will be discussed with reference made to real life events.
Using Integral Power Plant Diagnosis to Boost Maintenance Efficiency
Authors: Figueroa Ibarra Luis R. , Rodri´guez Marti´nez J. Hugo , Romo Millares Ce´sar A. , Sa´nchez Herna´ndez Laura E.
Published: October 2008

Significant decrements in generated power at fossil fuel power plants occur in the few months following annual maintenance which, besides causing economic losses for the power plants, reduce their availability. In order to determine the causes of these decrements, it is a common practice to carry out tests to evaluate the performance of the equipment in which the problem supposedly originates. Because these tests are made individually in the equipment, it is not possible to have an integral vision of the plant operation as a whole and, therefore, the problem related to energy efficiency is not attacked from the root [1]. This paper shows a practical method using in-situ measurements and a commercial simulation computer tool that allows the power plant operators to make an integral thermodynamic assessment. It makes possible to identify the causes of efficiency decrease (for the whole plant and its components) and to quantify the contribution of each equipment to the total power loss. As a result, priorities on the maintenance of the equipment can be determined to tackle the most important energy losses, and obtaining a total solution to the problem of energy decrement. The paper includes the results obtained from the application of this methodology to assess a 158 MW fossil fuel power plant unit in Mexico.
Cooling Water Chemistry: Friend or Foe
Authors: Janikowski Daniel S. , Kubik William J.
Published: October 2008

With today’s growing restrictions in sources and chemical treatment, cooling water that has low corrosive potential is difficult to find. Today’s sources are more aggressive (corrosive) creating a greater challenge to the survival of tubing materials. Pitting and crevice corrosion have become much more common. This paper identifies and summarizes those changes, concerns, and provides suggestions on how a utility can prevent long-term problems. It will cover the water factors to consider and monitor, proper lay-up practices, and material selections based on cooling water chemistry and practices.
Generator Upgrades: The Rest of the Story
Authors: Kilmartin Steve , Clark James W. , Lake Les
Published: October 2008

It is not unusual for well maintained and operated generators to be in use long after the OEM’s designed life expectancy. In fact, most large utilities in the United States have generators in their fleets that have been in operation for well over 30 years. With a growing dependence on electric power and the prohibitive cost of outage extensions, there have been increased efforts to obtain higher operating voltages while increasing reliability. To accomplish this, it may require the replacement of major components such as armature windings, field windings or a complete rotor. Upgrading generator components can be a complicated process that requires a considerable amount of preplanning, extended outage time and a significant financial investment. Not all generator service issues are solved with a rewind. Often ignored during generator upgrades are the auxiliary systems; seal & lube oil, hydrogen cooling, gas supply & controls, stator cooling water and monitoring systems. The auxiliary system equipment is critical to ensure efficient, reliable and safe operation of the generator. Time and wear of auxiliary system components have a direct impact on the generator availability and could potentially lead to a generator problem that could lead to a catastrophic failure. A proactive approach to upgrading these critical auxiliary systems will help secure your return on investment involved in rewinding a generator. This paper identifies the benefits for evaluating and upgrading generator auxiliary systems.
Flow Dynamics of Unconfined Swirling Flames Under Fuel-Lean Conditions
Authors: Archer S. S. , Gupta A. K. , Kitagawa K.
Published: October 2008

This study provides the role of co- and counter swirl distribution in a experimental double concentric swirl burner that simulates the that simulates one swirl cup of a practical gas turbine combustor. Results of the effect of radial distribution of swirl in a burner under unconfined non-burning and combustion conditions are presented on the flow dynamics of a fuel-lean direct injection (LDI) configuration using propane as the fuel. Three-dimensional (3-D) flowfield data has been obtained immediately downstream of the burner exit to determine the detailed flow dynamics associated with the flow. The fuel was injected radially into the surrounding swirl flow. Flow characteristics, both without and with combustion, have been obtained for the co- and counter-swirl distributions to the combustion air flow under unconfined conditions. Flat vane swirlers have been used to induce swirl to the air flow. Both combustion and swirl distribution significantly influences the resulting flowfield. The resulting swirl number of the flow was calculated using the 3-D velocity data. Results show that swirl distribution in the burner and combustion provides significant effect on the characteristics of the internal and external recirculation zones. The heat release from combustion enhances the inner recirculation zone by increasing its width and length. Combustion causes significant increase to the velocity and vorticity magnitudes in the flow, and promotes flowfield symmetry. Combustion also affects the swirl number of the flow. The swirl number calculated from the geometrical relationships, derived from the swirl vane angle and swirler dimensions, is much different than that determined from the 3-D velocity field data. The entrained mass flow rate is larger for the co-swirl distribution case and this entrainment is further enhanced with combustion. The results provide the role of radial swirl distribution on the mean and turbulence characteristics of flows for the two different shear flow conditions between the inner and outer annulus of the burner.
An Effective Way for Maintenance Reduction and Vibration Elimination of Peaking Gas Turbines
Authors: Anderson James H. , Hildebrand Chuck , Anderson James H.
Published: October 2008

A US power generation company had 36 similar high heat rate gas turbines in two of their plants. These units were used for peaking power in a large metropolitan area. On two of these units in the early 1990’s they tried switching from lubricated, gear-type couplings to single, machined diaphragm-type couplings for reduction of maintenance and improved flexibility. The gear couplings also caused a great deal of vibrations during startup, and many times units were shut down because of excessive vibrations. Due to the extreme thermal growth of these applications, along with the stop-start nature of the application, the couplings were required to handle enormous amounts of misalignment. While the standard diaphragm couplings seemed like a good choice for the application because of their large misalignment capability, they proved to be unable to handle the excessive offset movements caused by thermal growth. The problem with the standard diaphragm was that it was too stiff or in other words, the spring rate was too high. In one case the coupling failed catastrophically very quickly under normal running conditions. In the mid 1990’s the power company tried a different, unique style of diaphragm couplings that used multiple diaphragms with holes in them. The diaphragms were made of thin, uniform thickness steel instead of the more common machined ‘profile’ diaphragms. Because of the holes, these new diaphragms provided much more misalignment capability, and they also had far lower spring rates than the previous diaphragm couplings. The lower spring rates caused an enormous reduction in reactionary forces from the coupling, and they also eliminated many vibration problems caused by the original gear couplings. The overall effect of this discovery was for the company to begin changing all similar units to this type of coupling. Now these 36 units which previously had severe vibration problems during startup, run very reliably. They have also eliminated the need for maintenance, which was an issue with the original gear couplings.
Combining CFD and Mathematical Optimization to Optimize Combustor Exit Temperature Profile
Authors: Motsamai Oboetswe , Visser Jan A. , Morris Reuben M.
Published: October 2008

A technique for design optimization of a combustor is presented in this study. The technique entails the use of Computational Fluid Dynamics (CFD) and mathematical optimization to minimize the combustor exit temperature profile. The empirical and semi-empirical correlations commonly used for optimizing Combustor Exit Temperature profile do not guarantee optimum. As experimental approach is time consuming and costly, use is made of numerical techniques. Using CFD without mathematical optimization on a trial-and-error basis, however, does not guarantee optimal solutions. A better approach that is viewed as too expensive is a combination of the two approaches, thereby, incorporating the influence of the variables automatically. In this study the combustor exit temperature profile is optimized. The optimum (uniform) combustor exit temperature profile depends on mainly the geometric parameters. The combustor exit temperature profile is affected as soon as flow enters the combustor. However, in gas turbine applications where care has been taken on the influence of upstream flow related conditions, the combustor exit temperature profile is optimized by dilution hole pattern and size. In this study combustor parameters have been used as optimization variables. The combustor in the study is an experimental liquid fuelled atmospheric combustor with turbulent diffusion flame. The CFD simulations uses the Fluent code with Standard k-ε model. The optimization is carried out with the Dynamic-Q algorithm, which is specifically designed to handle constrained problems where the objective or constraint functions are expensive to evaluate. The optimization leads to a more uniform combustor exit temperature profile as compared to the original.
Energy and Economic Evaluation of a Hybrid Power Plant With Wind Turbines and Compressed Air Energy Storage
Authors: Arsie I. , Marano V. , Rizzo G. , Moran M.
Published: October 2008

A model of a Hybrid Power Plant (HPP) consisting of Compressed Air Energy Storage (CAES) coupled with a wind farm is presented. This kind of plant aims at overcoming some of the major limitations of wind-generated power plants, including low power density and an intermittent nature owing to variable weather conditions. In CAES, energy is stored in the form of compressed air in a reservoir during off-peak periods and used on demand during peak periods to generate power with a turbo-generator system. Such plants can offer significant benefits in terms of flexibility in matching a fluctuating power demand, particularly when coupled with wind turbines. For the hybrid power plant considered in this study, results show that advantages in terms of economics, energy savings and CO2 mitigation can be achieved.
Cooling of Gas Turbines Inlet Air Through Aquifer Thermal Energy Storage
Authors: Bahadori Mehdi N. , Behafarid Farhad
Published: October 2008

The power output of gas turbines reduces greatly with the increase of inlet air temperature. Aquifer thermal energy storage (ATES) is employed for cooling of the inlet air of a gas turbine. Water from a confined aquifer is cooled in winter, and is injected back into the aquifer. The stored chilled water is withdrawn in summer to cool the gas turbine inlet air. The heated water is then injected back into the aquifer. A 20 MW Hitachi gas turbine, along with a two-well aquifer were considered for analysis. It was shown that the minimum power output of the gas turbine on the warmest day of the year could be raised from 16.30 to 20.05 MW, and the mean annual power output could be increased from 19.1 to 20.1 MW, and the efficiency from 32.52% to 34.54% on the warmest day of the year and the mean annual efficiency from 33.88% to 34.52%. The use of ATES is a viable option for the increase of gas turbines power output, provided that suitable confined aquifers are available at their sites.
Estimating Long Term Major Maintenance and Capital Spending Requirements of Trinidad’s Aging Power Plants
Authors: Richwine Robert R. , Joseph Michael , Huguenard Charles , Baksh Hafeez , Elenbass Mike
Published: October 2008

This paper describes the process used by the Power Generation Company of Trinidad and Tobago (PowerGen) to estimate the range of major (expenditures greater than US$50,000) recurring and non-recurring costs that can be expected to be incurred from 2006–2025 by PowerGen’s three existing generating facilities: Port of Spain, Point Lisas and Penal. Since many of these Capital and O&M costs are not 100% certain, a probabilistic approach was used that incorporates a Monte Carlo methodology. The results of this approach allowed PowerGen to better understand the range of possible major capital and O&M expenditures that would likely be required over the next 20 years along with a quantification of the risk profile of those ranges. By adding these costs to the routine O&M costs, a total cost cash flow timeline was able to be developed that more realistically forecast the actual financial requirements of PowerGen’s power plants. Periodic review and updates of the data will also provide PowerGen with a continuing sound basis for long term technical and financial decisions. Additionally, a benchmarking analysis was performed that compared the reliability trends of similar but older technologies to those plants in PowerGen’s fleet in order to gain an insight into the reliability expectations for PowerGen plants over the next twenty years.
Models for Simulation and Diagnosis of Energy Plant Components
Authors: Cerri Giovanni , Borghetti Sandra , Salvini Coriolano
Published: October 2008

This paper describes a methodology to set up models for simulation and diagnosis of energy plant components. The adopted approach consists in a simultaneous solution of modules representing plant components taking their actual behavior into account. Models are characterized by Reality Functions to adapt them to the reality of machines and apparatuses so that the New&Clean map of the real component can be established. Furthermore, to account for deterioration phenomena occurring during plant operations, Actuality Functions affecting component performance in terms of work and heat transfer, losses and effective flow functions have been introduced. Models have been validated and tested against real CHP plant data. Two applications to different kinds of power plants are presented and discussed. Results show a good capability to estimate component deterioration statuses and reproduce component actual behavior maps.
Some Fundamentals of Explosions Related to the Power Industry
Authors: Lilley David G.
Published: October 2008

Fundamentals of pertinent information on fire dynamics of explosions are reviewed, with emphasis on technical aspects related to the power industry. Topics include: fundamentals, characterization, vapor cloud explosions, blast damage due to over-pressurization, procedure for estimating the overpressure, blast fragment missile damage, and energy of mechanical explosions. The text is imbued with examples to assist in understanding and applying the ideas in real-world situations. This material is designed especially for persons in fire-related occupations: fire service, insurance adjusters, fire investigators, forensic engineers and attorneys desiring further knowledge about technical aspects of explosions.
The Advantages of Using Multiple Frequencies for Eddy Current Examination of Condenser Tubing
Authors: Droesch Dale , Maestas Ronnie , Saxon George
Published: October 2008

An essential element in the eddy current testing methodology is the use of multiple testing frequencies. A true volumetric inspection requires complete penetration of the tube wall from various perspectives. Since prime frequency is set to approximately thirty seven percent standard depth of penetration of the tube wall, additional frequencies are required to gain an accurate and detailed perspective of the defect. In fact, the need for additional frequencies is absolutely necessary to characterize particular defects such as under-deposit corrosion and microbiologically influenced corrosion. In such cases a minimum of three frequencies are required to perform optimum testing. The frequencies will vary from low, midrange to high depending on the material under test. A fourth frequency can also be used to identify tube supports and tubesheets. This paper demonstrates the effects and advantages of utilizing multiple frequencies in the testing process. The result of which is to provide the analyst with sufficient information to call the defects with greater accuracy and reliability. Utilizing a multi-frequency test instrument and standard probes commonly used for testing condenser tubes, tube samples with various defects will be examined utilizing one, two, three and four frequencies. Defect acquisition rates will also be varied and the results reported. The information is useful for determining the number of frequencies required for an effective eddy current test.
Design, Fabrication and Testing of a Novel Energy-Harvesting Thermoelectric Power Supply for Wireless Sensors
Authors: Jovanovic Velimir , Ghamaty Saeid , Bass John C.
Published: October 2008

A prototype energy-harvesting thermoelectric generator (TEG) was designed and fabricated and it is being tested to provide power for wireless sensors used in the health monitoring (monitoring of temperatures, vibrations, strains, etc) of Navy shipboard machinery. TEGs are rugged, reliable, solid-state devices that convert heat directly into electricity without any moving parts. The TEGs designed in this project utilize the heat transfer between shipboard waste heat sources and ambient air to generate electricity. To satisfy the required small design volume of less than one cubic inch, Hi-Z Technology, Inc. (Hi-Z) is using its innovative Quantum Well (QW) thermoelectric technology that provides a factor of four increase in the conversion efficiency, and a large reduction in the design volume over the currently used bulk bismuth-telluride thermoelectics. QWs are nanostructured multi-layer thin films. These wireless sensors can be used to detect cracks, corrosion, impact damage, and temperature and vibration excursions as part of the Condition Based Maintenance (CBM) of the Navy ship machinery. The CBM of ship machinery can be significantly improved by automating the process with the use of self-powered wireless sensors. These power-harvesting TEGs can be used to replace batteries as electrical power sources and to eliminate tethered wires and cables, thus significantly reducing the installation and maintenance costs. The very first QW TEG module anywhere was just successfully tested (it produced electricity from heat). It remains to package this module with thermal insulation in the housing and heat sink, and to test this entire TEG device in a simulated thermal environment of a Navy gas turbine. Following this test, it is planned to attach this device to the surface of a gas turbine on a Navy ship and to test it in its actual environment, in conjunction with a wireless sensor. This power supply for wireless sensors can also be used in health monitoring of equipment in the nuclear and conventional power plants, process plants, and the monitoring of temperatures, vibrations and pressures of steam lines, etc. Hi-Z has chosen this small power supply as the first practical application of its emerging QW TEG technology. However, this technology can also be used on a much larger scale in, for example, recovering the waste heat from the exhaust of the truck and automobile engines, where the generated electricity can be used to eliminate the alternator and thus reduce the load on the engine, improve overall efficiency and reduce fuel consumption.
Installation of a New Deaerator for Boiler Feedwater Supply Achieves Better Efficiency and Operating Stability
Authors: Signo Barbara , Alvarez Jose F. , Marin Blas , Sellers Dennis
Published: October 2008

Sugar Cane Growers Cooperative of Florida, (SCGC), a sugar processing mill with six power boilers, achieved higher reliability, higher overall efficiency, and better operating stability by replacing the 29 year old parallel flow horizontal Deaerator and installing a new Feed Water Storage Tank. This paper presents the selection process for the new Counter Flow Two Stage Spray-Tray Deaerator, instrumentation, automation, and system modifications which led to saving 8,000,000 Btu/hr (2,340 kW/hr), and reducing the use of sulfite for boiler oxygen scavenging purposes while reducing system pressure and temperature fluctuations.
A Case Study of How Vertical Spindle Pulverizer Performance is Related to Overall Plant Performance
Authors: Storm Stephen K. , Storm Richard F. , Storm Daniel S. , Tuzenew Sammy , McClellan Adam
Published: October 2008

Pulverizer performance optimization is the first step to a successful combustion optimization program and the inter-relationships of the pulverizers must be considered when attempting to optimize combustion, overall unit performance, operability, reliability, and capacity. Pulverizer capacity seems to be an industry challenge while many units today are undergoing drastic fuel changes. Considering there seems to be a huge disconnect when correlating mill performance with such issues as fuel line distribution, heat rate, NOx and environmental control equipment performance, it is the intent of this technical paper to provide better understanding of how mechanical optimization & tuning of the pulverizers can yield overall improved plant performance. Low NOx firing and/or optimization of the burner belt combustion with a limited amount of furnace residence time is absolutely essential to optimizing plant performance. For example, when pulverizer performance is poor, it is also often related to not only high furnace exit gas temperatures, increased slagging and/or high LOI, but also degrading electrostatic precipitator (ESP) performance from the coarse particle ash. Furthermore, reliability of the boiler (ie. tube leaks, fouling, and slagging) can also be impacted negatively by secondary combustion and consequent super heater and re-heater tube metals overheating and/or wall wastage often occurs from non-optimized fuel distribution being delivered from the pulverizers. Whether the reason for improving mill performance is for the aforementioned items and/or perhaps simply to reduce power generation costs with improved fuels flexibility, the purpose of this case study is to review the basics of vertical spindle mill performance improvements. The data used to support this paper is from a compilation of actual field testing & tuning results. Furthermore, Storm Technologies, Inc. (STI) suggests the aforementioned steps as an effective approach to optimization.
Comparison Between American and European Methods For Admitting Bypass Steam Into a Steam Surface Condenser: Advantages and Disadvantages of Each Practice
Authors: Nadig Ranga , Phipps Michael
Published: October 2008

Combined cycle plants are in operation in every part of the globe. The majority of the combined cycle plants have been designed by architect engineering companies in the USA or in Europe. The US standards for plant design are different from those in Europe. In spite of the differences, both design practices achieve the common goal of efficient and reliable electrical power generation. The method for admission of bypass steam into a condenser in the U.S. is substantially different from that in Europe. In the US practice, bypass steam entering the condenser is at relatively high pressures and is superheated. In the European practice, the bypass steam entering the condenser is at relatively low pressures and is wet. Each practice serves the common purpose of condensing bypass steam in the condenser and each practice has its own disadvantages and disadvantages. Tube failures are encountered in each practice. These tube failures are caused by droplets in the (moist) high velocity bypass steam. Low condenser pressures, improper design / control / operation of pressure reducing desuperheating valve (PRD valve), and improper drainage of bypass header lines are some of the major reasons that cause an environment favorable for tube failures. This paper examines the US and European methods for admitting bypass steam into a condenser. The advantages and disadvantages of each practice are discussed. For each practice, the performance in bypass mode for varying condenser pressures, bypass steam flow rates, support plate spacing, and moisture pockets quality are evaluated. Both actual and critical steam velocities are calculated. Condenser operating points prone to flow-induced vibration and associated tube failures are predicted.
Integrating Performance and Maintenance Programs to Meet AES Cartagena Business Goals
Authors: Freitas Italo , Toomey Greg
Published: October 2008

It is always a major endeavor and challenge to build a new combined-cycle power plant. This fact combined with having stringent reliability, availability and efficiency contractual terms necessitates a well planned, highly effective maintenance strategy. To further complicate the matter, the company was rolling out a new EAM; SAP. AES Corporation was facing exactly these issues for their new plant in Cartagena, Spain. This paper will describe the approach used by AES to develop a proactive maintenance program that integrates condition and performance information to achieve their goals. The process begins with creating a maintenance strategy using the SRCM® process. From the results of the strategy development SAP-PLM module was configured to support agreed to business process models, asset hierarchy schemes, task list, value lists and spare parts determination. The strategy developed also identified the PdM and ODR technologies to use and lead to the development of the PdM program. It also created the operator driven (ODR) tasks by specifying what equipment is to be watched by operators as part of an equipment health program. Finally, PdM, ODR and appropriate process data were linked together into a decision support system. This information combined with the plant performance information will provide AES an effective, integrated program to manage their plant and equipment. Due to the limited staff to manage the station a software tool was used to lessen the effort to understand the condition of critical equipment based on the data. A discussion of why it is necessary for new and existing plants to create a proactive maintenance program that starts with business processes followed by software and hardware including CMMS, PdM, online monitoring, electronic operator rounds and ends with the right data in these tools is presented. Without the proper data including asset register, criticality, reliability information and condition data the program will not support plant objectives and could potentially cost the company large penalties for non-performance. Examples of work products developed with work flowcharts will be provided. By actively pursing an integrated, proactive solution for the maintenance and performance programs AES will achieve their business objectives from the very beginning of plant commercialization. It will also ultimately lead to savings in not only implementing a complete maintenance program but will provide a solid foundation for managing and improving the program operation of the plant to meet and exceed contractual performance requirements.
Power Plant Centralized Monitoring Using SBM
Authors: Flesch Philip J. , Stoecker Chad
Published: October 2008

The advent of certain technologies have opened the door to higher plant performance through highly accurate, centralized monitoring. These technologies include data historians, better network/internet connection speeds, faster processor speeds and Similarity Based Modeling (SBM). By combining these technologies the modern utility can monitor a broad base of sites, components and plants from a central location.
The Application of Systems CFD to the Design and Optimization of High-Temperature Gas-Cooled Nuclear Power Plants
Authors: Greyvenstein Gideon P.
Published: October 2008

The basic approach with the design of power plants is to first carry out a thermodynamic cycle analysis and then to vary certain cycle parameters such as the overall pressure ratio in order to determine the optimum or design point condition. One would then proceed to design the different components to match the process conditions. However, since component design has an impact on overall system performance, one cannot optimize the design of the components in isolation from the rest of the system. This calls for an iterative procedure where one has to move several times between the process and component levels to obtain an optimized integrated solution. Another problem faced by plant designers is that Computational Fluid Dynamics (CFD) codes that are increasingly used for detailed component design are slow and not well suited for optimization studies. They are not suited at all for the analysis of complete power plants. Furthermore, the main task of plant designers is not to do design point analyses but to analyze off-design performance, to do uncertainty analyses, to optimize the design and to characterize the dynamic behavior of the system for the purpose of controller design. An approach that has been used with great success for the design of the power conversion system of the Pebble Bed Modular Reactor (PBMR) is the systems CFD approach. The PBMR is a new High Temperature Gas-cooled Reactor (HTR) that is being developed in South Africa. The PBMR utilizes a direct closed recuperated Brayton cycle. Other cycles are also being investigated including various combined cycles. Systems CFD codes are based on the network approach and allow one to model the performance of large complex systems in an integrated fashion. Different levels of component models are provided for ranging from lumped models for components such as pumps to 1D, 2D or even 3D CFD models for components such as complex diffusers, heat exchangers and the pebble bed reactor. In this paper the systems CFD approach will be discussed including the most important component models. Various examples of the application of the systems CFD approach in the design of the PBMR plant will be given.
Clearance and Seals Design for New Heat™ Steam Turbine
Authors: Couture Bernard A. , Keeling Leslie B. , Kowalczyk Mark W.
Published: October 2008

The HEAT™ (High Efficiency Advanced Technology) steam turbine utilizes high reaction technology [1], which is significantly influenced by the effectiveness of sealing between the stages. The thermal-mechanical analysis based clearance design and the combination of labyrinth sealing with abradable coatings offer an effective solution to minimize bucket and nozzle tip leakage through transient and steady state operation of the turbine. The aim of this paper is to describe the clearance design process and the development of abradable-labyrinth seal configurations. The paper describes extensive testing and detailed analysis conducted to evaluate seal properties and behaviors. Properties investigated included corrosion, erosion and in particular, rub characteristics. Rub behavior is investigated in a high temperature, high speed test apparatus designed to simulate clearance changes during transient periods of start-up, shutdown and hot re-start which often result in interference between the sealing components. This paper will discuss the method to predict differential rotor to stator movements and the resulting abradable incursion during the various operating transients. The seal tooth to coating contact is then simulated with component testing for multiple incursion modes (i.e. radial, axial and a combination of the two) and rates. The discussion will also include the application of the clearance design and sealing technology to a reaction type steam turbine.
Field Validation Testing of New HEAT™ Steam Turbine
Authors: Miller Richard J. , Conner Reginald D.
Published: October 2008

The field validation and launch unit performance testing of a new high efficiency steam turbine design is described. The HEAT™ (High Efficiency Advanced Technology) steam turbine utilizes a new line of high efficiency steam path components developed by the author’s company [1], [2]. The extensive field test program, executed at the customer’s plant, included all major aspects of steam turbine operation and performance. Data was gathered continuously using multiple automated systems. Careful indexing of this data provided a multi-faceted view of operating phenomena during the test period. Overall machine performance was tested using ASME PTC 6.2 protocol. HP and IP individual section thermodynamic performance was quantified with a series of enthalpy drop tests. In addition, all leakage flows were measured to confirm end seal performance. HP section pressure ratio tests and internal leakage blowdown tests were done to determine the HP steam path aerodynamic characteristics. Various pressure measurements were used to quantify LP bucket aerodynamics and overall LP hood/diffuser performance. Validation testing of thermal-mechanical transient behavior of major components during all normal operating modes was achieved using lasers, thermocouples and strain gauges. In addition, thermal imaging was used to increase understanding of these transients. The validation instrumentation had an additional benefit to this customer, as it assisted the site team to successfully commission this A14 code type turbine, which achieved world-class efficiency.
Nanoscale Energy Conversion by Using Nano-Catalytic Particles
Authors: Hu Zhiyu , Thundat Thomas
Published: October 2008

Burning or combustion is the most common energy conversion method of which the chemical energy stored is converted to the thermal energy during an oxidation process. Governed by the scaling and thermodynamic laws, there is a minimum size requirement (∼1 mm) for having a sustainable reaction. Conventional combustion or burning usually takes place when the reactants’ temperature is much higher than the body temperatures of biological beings. All heat engines including both external combustion engines and internal combustion engines were developed using this phenomenon; and reaction processes proceed in macroscale where big machines and large reaction chambers are often employed. As an attempt to mimic nature’s method of energy conversion, without external ignition, nano-catalytic particles could be self-heated very rapidly (in seconds) in the present of methanol or ethanol vapor/air mixture flow. Stable and reproducible spontaneous self-ignition and self-supporting combustion have been achieved at room temperature by exposing nanometersized catalytic particles to methanol-air or ethanol-air gas mixtures. Infrared thermography revealed that the thermal gradient near nanoparticles could be more than 100 times higher than what could be achieved in macroscale. The reaction releases heat and produces CO2 and water. Such reactions starting at ambient temperature have reached both high (> 600°C) and low (a few tenths of a degree above room temperature) reaction temperatures. The reaction intensity could be easily controlled by varying the fuel-air mixture. The application of this discovery might lead to the development of a new class of solid state electrical power generators which could convert fuel energy to electricity without any moving parts.
Flow Analysis Helps Correct Underperformance of Combined Cycle Emissions Equipment
Authors: Fisher Mark D. , Davies George A.
Published: October 2008

Computational fluid dynamics analysis of the exhaust gas flow distribution in the inlet ductwork of a combined cycle power plant has helped improve both emissions performance as well as lowering plant operating costs. The Turlock Irrigation District Almond Power plant had recently installed an upgraded gas turbine (GT), and replaced both CO oxidation and selective catalytic control (SCR) NOx control catalysts in order to withstand the higher exhaust temperatures of the new gas turbine. After the retrofits, both NOx and CO emissions were within Permitted limits, but were above expected values, and operators found that overspray of ammonia was required to meet required NOx values of 3.0 ppmv at 15% O2. The need to overspray also resulted in unacceptably high levels of ammonia slip at the stack. Following investigations which included physical flow modeling of the ductwork, TID opted to have the exhaust gas flow numerically modeled to confirm the origin of the emissions problem and identify and implement a long-term resolution. Computational fluid dynamics (CFD) analyses confirmed that the cause of the poor emissions performance was highly biased gas flow distributions at the entrance to the CO catalyst modules and the ammonia injection grid (AIG). Using multiple models to evaluate alternate configurations of flow control devices, a single distribution grid located upstream of the CO catalyst modules was designed to provide improved flow distributions at both the CO catalyst, AIG, and SCR catalysts. Field tests of the plant with the installed distribution grid confirmed that the retrofit significantly improved emissions performance while reducing both required ammonia injection flows and ammonia slip values eight-fold. This not only allowed the plant to meet and exceed required emissions levels, but also reduced ammonia injection flow rates by a minimum of 40%. Additionally, the facility has seen an improvement in the plant’s effective operating range. This is the range at which the plant can operate and still maintain emissions compliance. Prior to the installation of the distribution grid the plant had an effective operating range of 30–50 MW. The plant now has an effective operating range of 20–50 MW. This is beneficial at times when the plant is operated in “load following” mode.
Solar Photovoltaic Water Pumping to Alleviate Drought in Remote Locations
Authors: Meah Kala , Fletcher Steven , Wan Yu , Ula Sadrul
Published: October 2008

Many parts of the western US is rural in nature and consequently do not have electrical distribution lines in many parts of farms and ranches. Distribution line extension costs can run from $15,000 to $25,000 per mile, thereby making availability of electricity to small water pumping projects economically unattractive. Solar photo-voltaic (PV) powered water pumping is more cost effective in these small scale applications. Many western states including Wyoming are passing through fifth year of drought with the consequent shortages of water for many applications. Wyoming State Climatologist is predicting a possible 5–10 years of drought. Drought impacts the surface water right away, while it takes much longer to impact the underground aquifers. To mitigate the effect on the livestock and wildlife, Wyoming Governor Dave Freudenthal initiated a solar water pumping initiative in cooperation with the University of Wyoming, County Conservation Districts, Rural Electric Cooperatives, and ranching organizations. Solar water pumping has several advantages over traditional systems; for example, diesel or propane engines require not only expensive fuels, they also create noise and air pollution in many remote pristine areas. Solar systems are environment friendly, low maintenance and have no fuel cost. In this paper the design, installation and performance monitoring of the solar system for small scale remote water pumping will be presented.