bluuebunny/crossref_metadata_2025 huggingface dataset:
TN X SN Fatigue Curves for KS Hook and Chain Using Finite Element Modelling
Authors: Lima de Almeida Jose´ Carlos , Rossi Ronaldo Rosa , Sobral Ricardo
Published: October 2008

For mooring chains of offshore floating production units, API (American Petroleum Institute) recommends the use of its TxN fatigue curve considering the MBL (Minimum Breaking Load) of an ORQ (Oil Rig Quality) chain even if the chain has a higher grade. DNV (Det Norske Veritas) recommends the use of SxN fatigue curve where the stress is taken using the tension over the nominal area of the chain or wire rope. So it is easy to convert this SxN curve to a TxN curve or vice-versa. The geometry of the chain or wire rope and the material are implicit considered. To develop SxN curve for new accessories design it is necessary the using of FEM (Finite Elements Method) to obtain the distribution of stresses and strains and the stress concentration factor and the SxN curves of the material. The analysis of the tension and the stress concentration factor will be used to obtain the slope and intercept parameters of the fatigue curve. This paper will present the study developed for KS hook and how to obtain the fatigue curve for this accessory based on published papers, rules and recent tests.
Nonlinear Elastoplastic Behaviour of Intermittently Welded Stiffened Plates Under Inplane Compression
Authors: Khedmati Mohammad Reza , Rastani Mehran
Published: October 2008

The objective of this study is to investigate the sensitivity of the ultimate strength and failure mechanism of stiffened plates constructed by different welding methods in common. A series of detailed numerical analyses of longitudinally stiffened steel plates subjected to inplane compressive load are performed using ADINA commercial finite element code. Complete equilibrium paths are traced up to collapse for nonlinear elastoplastic response of stiffened plates. Stiffened plates analysed are imperfect and their aspect ratio, plate slenderness and column slenderness are changed in a systematic manner. Different types of stiffener are chosen for stiffened plate models. Three different stiffener-to-plate welding procedures are considered: continuous, chain intermittent and staggered intermittent fillet welding.
Experimental and Numerical Comparative Investigation of Pressure Fields Under Steep 2D Waves
Authors: Ducrozet Guillaume , Bonnefoy Fe´licien , Le Touze´ David , Roux de Reilhac Pierre , Retzler Chris , Rousset Jean-Marc , Ferrant Pierre
Published: October 2008

In the present work is presented a recently developed fully-nonlinear spectral Numerical Wave Tank (NWT) model, named HOST-wm2, and its capabilities for reproducing highly-nonlinear evolutions in a wavetank are evidenced on experimental comparisons. This fully-spectral model is based on a Higher-Order Spectral (HOS) method, which ensures high levels of accuracy and efficiency, thanks to the fast resolution made by FFTs only. This numerical method is dedicated to model wave basins and a specific care is paid to fit the experimental wavetank characteristics (are included, the physical geometry of the wavetank, the snake-type wavemaker, an absorbing beach, ...). The numerical simulations are successfully compared to experiments conducted in cooperation with Ocean Power Delivery (OPD) in the wavetank of the Ecole Centrale de Nantes (ECN). Comparisons for wave elevation and pressure fields under highly-nonlinear steep 2D waves are reported. The usefulness of the presented NWT to assist experiments is also illustrated on the assessment of the procedure used to extract the pressure gradient from the experimental pressure signals.
On the Reverse Flow Beneath a Submerged Plate Due to Wave Action
Authors: Carter Richard W. , Ertekin R. Cengiz , Lin Pengzhi
Published: October 2008

A water wave, passing over a horizontal plate submerged beneath the free surface, would experience above the plate both a change in wave height and wavelength. On leaving the plate, the wave, in general, encounters a reduction in wave height as compared to the incident wave. The reduction in the wave height depends upon the wavelength, the plate length and its position below the free surface, i.e., the submergence depth, as well as the water depth. Depending on the particular flow configuration, a pulsating reverse flow can occur beneath the plate, in a direction opposite to that of wave propagation. This pulsating two-dimensional flow field has been proposed by others as a method to convert wave energy into electrical energy. The main objective of this paper is to study the reverse flow beneath a submerged plate by surface wave action in finite water depth. A 2-D numerical model that uses the boundary-element method is developed to simulate this physical event by solving the linear equations of motion for waves in an ideal fluid. In addition, the Reynolds-Averaged Navier-Stokes equations are used to solve the nonlinear equations of motion for waves in a viscous fluid by use of the Fractional-Step Method. The numerically obtained linear and nonlinear results are compared with the available experimental data.
Three Dimensional Imaging System for Subsea Inspection
Authors: Messina L. C. P. , Simo˜es A. P. , Botto A. , Petra´glia A.
Published: October 2008

This work presents the Stereo Vision and 3D Submarine Dimension System design and its experimental test to validate the system, which is the result of cooperation between PETROBRAS and COPPE/UFRJ, with the purpose of developing a system that allows, in real time, the three-dimensional visualization (stereo) and dimension of submarine structures (pipes, umbilical, connectors and valves) and anomalies. Basically, the system is characterized by an optimized hardware-and-software co-design procedure. The software includes a stereophotogrametry algorithm for precise, real-time, inspection and dimensioning operations. From a pair of cameras positioned on a ROV - Remotely Operated Vehicle, the system allows the telepresence sensation by three-dimensional vision of remote sites considerably reducing the time and, consequently, the costs of operation. The work also presents test results: laboratory small scale tests, test at PETROBRAS tank and a full-scale test on an inspection boat, with dimension of real pipe damages at Campos Basin. The system will provide three-dimensional images of submarine structures allowing the acquisition of consistent and accurate data to assist the decision for the need of repairing operations.
Study on Ship Form Technical and Economic Evaluation DS Based on Interactive MCDM
Authors: Song Sang , Jun Li-Hua
Published: October 2008

A new method of interactive Multiple Criteria Decision Making (MCDM) is presented. In order to settle the problem that in the cases for the ship designers sometimes it is difficult to make a decision when facing so complex ship form schemes. The conventional AHP (Analytical Hierarchy Process) is adopted, but it mostly depends on the designer’s subjective and leads to the systematic error. The new method can obtain the accurate result with the rigid least square method as a tool, making full use of the AHP and the objective information entropy, which reflects the inherent attribute. When applied in the practice, it is proved to be effective, practical and dependable for future ships’ complex Decision Systems (DS).
VIVACE (Vortex Induced Vibration Aquatic Clean Energy): A New Concept in Generation of Clean and Renewable Energy From Fluid Flow
Authors: Bernitsas Michael M. , Raghavan Kamaldev , Ben-Simon Y. , Garcia E. M. H.
Published: October 2008

Any device aiming to harness the abundant clean and renewable energy from ocean and other water resources in the USA must have high energy density, be unobtrusive, have low maintenance, be robust, meet life cycle cost targets, and have a 10–20 year life. The VIVACE (Vortex Induced Vibration Aquatic Clean Energy) Converter — invented by Bernitsas & Raghavan and patented through the University of Michigan — satisfies those criteria. It converts ocean/river current kinetic energy to electricity using VIV successfully and efficiently for the first time. VIVACE is based on the simple idea of maximizing rather than spoiling vortex shedding and exploiting rather than suppressing VIV. It introduces optimal damping for energy conversion while maintaining VIV over a broad range of vortex shedding synchronization. VIV occurs over very broad ranges of Reynolds (Re) number. Only two transition regions suppress VIV. Thus, even from currents as slow as 0.25m/sec, VIVACE can extract energy with high efficiency making ocean/river current energy a more accessible and economically viable resource. In this paper, the underlying concepts of the VIVACE Converter are discussed. The designs of the physical model and lab prototype are presented. A mathematical model is developed and design particulars for a wide range of application scales are calculated. Experimental measurements on the lab prototype are reported in the sequel paper and used here for preliminary benchmarking.
The Latest Innovation in Pressure Compensated Deep-Sea Wet Mateable High Voltage Connectors
Authors: Frerck Tobias
Published: October 2008

GISMA GmbH was founded in 1983 and is today a medium-sized company with 42 employees. With a real net output of 90%, GISMA in Neumu¨nster develops, designs and produces 3,500 different connectors. The high-quality electrical and fibre-optical connectors are used world-wide in the offshore industry, marine technologies and in submarine technologies. With a market share of approx. 30% GISMA is nowadays one of the leading connector manufacturers in European marine technology. 350,000 Euro is invested annually in research and development.
The VIVACE Converter: Model Tests at High Damping and Reynolds Number Around 105
Authors: Bernitsas Michael M. , Ben-Simon Y. , Raghavan Kamaldev , Garcia E. M. H.
Published: October 2008

The VIVACE Converter is a new concept to generate clean and renewable energy from fluid flows such as those abundant in oceans, rivers or other water resources. The underlying concepts for design, scaling, and operation of VIVACE (Vortex Induced Vibrations Aquatic Clean Energy) were introduced in our previous paper. In its simplest form, a VIVACE modulo consists of a single rigid cylinder mounted on elastic supports and connected to a Power Take Off (PTO) system. The cylinder is placed in a steady unidirectional current and excited in VIV. In this paper, the VIVACE modulo was tested in the Low Turbulence Free Surface Water Channel of the University of Michigan to demonstrate the concept, generate electricity, measure its efficiency, and calculate basic benchmarking measures such as energy density. Tests performed were tailored to the particulars of the VIVACE modulo which dictate that the cylinder operate in VIV under high damping and as high a Reynolds number as possible. At the same time, a broad range of synchronization is required to make VIVACE effective in energy generation in a realistic environment. Due to these requirements, VIV tests have not been performed before in the subspace applicable to the operation of the VIVACE modulo. In the process of extracting fluid kinetic energy and converting it to electricity in the lab, for a given set of cylinder-springs-transmission-generator, only the damping used for harnessing electricity was optimized. Even at this early stage of development, for the tested VIVACE modulo, the maximum peak efficiency achieved was ηPeak = 0.308; the corresponding integrated power efficiency in that particular test was ηVIVACE = 0.22 with theoretical upper limit based on measurements of ηUL-VIVACE = 0.3663. Such a high efficiency was achieved even at the low velocity U = 0.840m/sec = 1.63knots.
Analysis of Turbulent Flows and VIV of Truss Spar Risers
Authors: Constantinides Yiannis , Oakley Owen H. , Holmes Samuel
Published: October 2008

Complex flows through riser arrays, such as the case of risers located in the truss section of a truss spar, are very difficult to describe and analyze. It is especially difficult predict and correct Vortex Induced Vibration (VIV) response using traditional tools that were meant to analyze single risers rather than arrays of risers. Computational Fluid Dynamics (CFD) offers the designer the capability to properly analyze these complex problems, increasing the reliability of the design. In this study, a full scale truss spar with vertical risers is modeled using CFD. The VIV response of the risers is predicted and the effect of risers is correctly captured and compared with experiments.
Diagnostic Techniques for Improving Power Plant Performance, Reliability and Availability: A Case Study
Authors: Sunder Raj Komandur S.
Published: October 2008

The objectives of an effective power plant performance monitoring program are several-fold. They include: (a) assessing the overall condition of the plant through use of parameters such as output and heat rate (b) monitoring the health of individual components such as the steam generator, turbine-generator, feedwater heaters, moisture separators/reheaters (nuclear), condenser, cooling towers, pumps, etc. (c) using the results of the program to diagnose the causes for deviations in performance (d) quantifying the performance losses (e) taking timely and cost-effective corrective actions (f) using feedback techniques and incorporating lessons learned to institute preventive actions and, (g) optimizing performance. For the plant owner, the ultimate goals are improved plant availability and reliability and reduced cost of generation. The ability to succeed depends upon a number of factors such as cost, commitment, resources, performance monitoring tools, instrumentation, training, etc. Using a case study, this paper discusses diagnostic techniques that might aid power plants in improving their performance, reliability and availability. These techniques include performance parameters, supporting/refuting matrices, logic trees and decision trees for the overall plant as well as for individual components.
Capacity Mapping for Optimum Utilization of Pulverizers for Coal Fired Boilers
Authors: Bhattacharya Chittatosh
Published: October 2008

The pulverizer plays a pivotal role in coal based thermal power generation. The improper coal fineness or drying reflects a quality-wise deterioration. This results in flame instability, unburnt combustible loss, and a propensity to slagging or clinker formation. Simultaneously, an improper air-coal ratio may result in either the coal pipe choke or the flame impingement, an unbalanced heat release, an excessive FEGT, overheating of the tube metal, etc, resulting on the reduced output and excessive pulverizer rejects. In general, the base capacity of the pulverizer is a function of coal and air quality, conditions of grinding elements, classifier and other internals. The capacity mapping is a process of comparison of standard inputs with actual fired inputs to assess the available standard output capacity of the pulverizer. In fact, this will provide a standard guideline over operational adjustment and maintenance requirement of the pulverizer. The base capacity is a function of grindability; fineness requirement may vary depending upon the volatile matter content of the coal and the input coal size. The quantity and inlet temperature of primary air limits the drying capacity. The base airflow requirement will change depending upon the quality of raw coal and output requirement. It should be sufficient to dry pulverized coal. Drying capacity is also limited by utmost P.A. fan power to supply air. The P.A. temperature is limited by APH inlet flue gas temperature — an increase of this will result in efficiency loss of the boiler. Besides, the higher P.A. inlet temperature can be attained through economizer gas by-pass, the SCAPH, partial flue gas recirculation. The primary air/coal ratio, a variable quantity within the pulverizer operating range, increases with decrease in grindability or pulverizer output and decreases with decrease in volatile matter. Again, the flammability of mixture has to be monitored on explosion limit. Through calibration, the P.A. flow and efficiency of conveyance can be verified. The velocities of coal/air mixture to prevent fallout or to avoid erosion in the coal carrier pipe are dependent on the pulverized coal particle size distribution. Metal loss of grinding elements inversely depends on the YGP index of coal. Besides, variations of dynamic load on grinding elements, wearing of pulverizer internal components affect the available pulverizing capacity and percentage rejects. Therefore, the capacity mapping is necessary to ensure the available pulverizer capacity to avoid overcapacity or under capacity running of pulverizing system, optimizing auxiliary power consumption, This will provide a guideline on the distribution of raw coal feeding in different pulverizers of a boiler to maximize operating system efficiency and control resulting a more cost effective heat rate.
Evaluation of the Effect of Firing Temperature, Cycle, Engine Configuration, Components, and Bottoming Cycle on the Overall Thermal Efficiency of an Indirectly Coal-Fired Gas Turbine Based Power Plant
Authors: Johnston Richard P.
Published: October 2008

Potential LHV performance of an indirect coal-fired gas turbine-based combined cycle plant is explored and compared to the typical LHV 35–38 % thermal efficiencies achievable with current coal-fired Rankine Cycle power plants. Plant performance with a baseline synchronous speed, single spool 25:1 pressure ratio gas turbine with a Rankine bottoming cycle was developed. A coal-fired High Temperature Advanced Furnace (HITAF) supplying 2000° F. (1093° C.) hot pressurized air for the gas turbine was modeled for the heat source. The HITAF concept along with coal gas for supplemental heating, are two important parts of the clean coal technology program for power plants. [1,2] From this baseline power plant arrangement, different gas turbine engine configurations with two pressure ratios are evaluated. These variations include a dual spool concentric shaft gas turbine, dual spool non-concentric shaft arrangement, intercooler, liquid metal loop re-heater, free power turbine (FPT) and post HITAF duct burner (DB). A dual pressure Heat Recovery Steam Generator (HRSG) with varying steam pressures to fit conditions is used for each engine. A novel steam generating method employing flash tank technology is applied when a water-cooled intercooler is incorporated. A halogenated hydrocarbon working fluid is also evaluated for lower temperature sub-bottoming Rankine cycle equipment. Current technology industrial gas turbine component performance levels are applied to these various engines to produce a range of LHV gross gas turbine thermal efficiency estimates. These estimates range from the lower thirties to over forty percent. Overall LHV combined cycle plant gross thermal efficiencies range from nearly forty to over fifty percent. All arrangements studied would produce significant improvements in thermal efficiency compared to current coal-fired Rankine cycle power plants. Regenerative inter-cooling, free power turbines, and dual-spool non-concentric shaft gas turbine arrangements coupled with post-HITAF duct burners produced the highest gas turbine engine and plant efficiency results. These advanced engine configurations should also produce operational benefits such as easier starting and much improved part power efficiency over the baseline engine arrangement. An inter-turbine liquid metal re-heat loop reduced engine thermal efficiency but did increase plant power output and efficiency for the example studied. Use of halogenated hydrocarbons as a working fluid would add to plant power output, but at the cost of significant additional plant equipment.
A Parametric Simulation of the Evaporation in Liquid-Fueled Porous Burners
Authors: Periasamy Chendhil , Gollahalli S. R.
Published: October 2008

This paper presents a computational parametric study of evaporation processes in liquid-fueled, simulated porous media burners using a two-energy equation model. The effects of porous medium heat source, porous medium structure, fuel flow rate, and air inlet temperature on evaporation characteristics were determined. Predicted steady-state axial temperature profiles within the porous media and radial vapor concentration profiles at 5 cm downstream of the porous medium are presented. Vapor concentration results showed a strong dependence on porous medium temperature, which, in turn, depended on the strength of the heat source and the effectiveness of heat transfer between porous medium and coflow air. Simulations with different porosities demonstrated that the peak vapor concentration decreased as porosity increased. The peak vapor concentration dropped by 42 % when porosity was increased from 0.5 to 0.87. Under higher fuel flowrate conditions, the extent of completeness of evaporation decreased, showing that much stronger heat source was needed to maintain the complete evaporation. When the coflow air temperature was increased, the peak vapor concentration was found to increase and the vapor concentration spread more radially.
Multi-Pollutant Removal System Performance: Based on Testing and Plant Operation Experience
Authors: Hamel H.-J. , Jaeger Walter , Fattinger Volker , Termuehlen Heinz
Published: October 2008

Since roughly 95 % of the fossil fuel reserves in the US are coal and only 5 % natural gas and crude oil, we need clean coal-fired power plants. Today, about 1400 pulverized-coal-fired power plant units are generating roughly 50 % of the US electric power.
Flow in Duct Downstream of a Steam Turbine Bypass Valve
Authors: Amano R. S.
Published: October 2008

The main goal of this study is to investigate the evaporation process of a coolant (water droplets) which is injected through spray nozzles mounted on a steam turbine bypass pipeline in a co-generator system. The study includes several important factors: (1) the effects of four elbows on the flow pattern and evaporation process of the water particles, (2) heat transfer that affects the steam temperature and also the evaporation rates, and (3) the effects of a perforated plate on the flow pattern and evaporation process. The investigation of the structure of liquid spray jets during the transition into the gaseous phase was accomplished by developing a physical model of a particle tracking technique to investigate evaporation processes of the liquid droplets in a highly turbulent flow. Through this research, numerous data have been acquired and analyzed for heat transfer mechanisms of the evaporation of the water droplets in the pipeline system along with the cooling of the steam flow. The results of the computations were verified by comparing them with theoretical models, and were shown to be quite reliable.
The Exergy Underground Coal Gasification Technology as a Source of Superior Fuel for Power Generation
Authors: Blinderman Michael S.
Published: October 2008

Underground Coal Gasification (UCG) is a gasification process carried on in non-mined coal seams using injection and production wells drilled from the surface, converting coal in situ into a product gas usable for chemical processes and power generation. The UCG process developed, refined and practiced by Ergo Exergy Technologies is called the Exergy UCG Technology or εUCG® Technology. The εUCG technology is being applied in numerous power generation and chemical projects worldwide. These include power projects in South Africa (1,200 MWe), India (750 MWe), Pakistan, and Canada, as well as chemical projects in Australia and Canada. A number of εUCG based industrial projects are now at a feasibility stage in New Zealand, USA, and Europe. An example of εUCG application is the Chinchilla Project in Australia where the technology demonstrated continuous, consistent production of commercial quantities of quality fuel gas for over 30 months. The project is currently targeting a 24,000 barrel per day synthetic diesel plant based on εUCG syngas supply. The εUCG technology has demonstrated exceptional environmental performance. The εUCG methods and techniques of environmental management are an effective tool to ensure environmental protection during an industrial application. A εUCG-IGCC power plant will generate electricity at a much lower cost than existing or proposed fossil fuel power plants. CO2 emissions of the plant can be reduced to a level 55% less than those of a supercritical coal-fired plant and 25% less than the emissions of NG CC.
Testing and Prediction of Performance and Emissions From Bituminous (Drummond Colombia) and Sub-Bituminous (Adaro Indonesia) Coals and Their Blends
Authors: Spitz Nadine D. , Bar-Ziv Ezra , Saveliev Roman , Perelman Miron , Korytni Efim , Dyganov Georgiy , Chudnovsky Boris
Published: October 2008

We predict the combustion behavior and pollutant emissions of blends of a Colombian bituminous coal, Drummond, and an Indonesian sub-bituminous coal, Adaro, in pulverized-coal utility boilers. This work is based on full-scale numerical simulations with GLACIER, a powerful computational-fluid-dynamic (CFD) code that uses the two-mixture fraction approach which models two separate coal streams in the combustion chamber. By burning the coals and their blends in a pilot-scale test furnace, previously unknown information on the coal combustion, such as devolatilization and char oxidation kinetic parameters, was determined and the CFD model validated for the test furnace. The same set of parameters was used for the CFD model configured for an opposed-wall and a tangential fired utility boiler. Our results show good fits between numerical results and experimental data for gas temperature, CO2, O2, and NOx, both in the test furnace and in the utility boilers, for single coals and their blends. We believe that the tool we developed can help utility companies make rational decisions on the use of new coals or coal blends so as to lower pollutant emissions while maintaining the same combustion efficiency.
Optimization of Steam Extractions Mass Flowrate in Advanced Steam Power Plant With Using Combined Pinch and Exergy Analysis (CPEA)
Authors: Sefidi Adel , Arash Ardeshir
Published: October 2008

Pinch technology has developed for thermodynamic analysis of chemical processes. This technology targets the most possible modification prior to detailed design. Pinch technology it is not sufficient in analyzing systems involving beat and power such as power plants. Exergy analysis, on the other hand, provides a powerful tool for heat and power analysis, although at times it does not provide clear practical design guideline. To prevailing over the weaknesses of both analysis, in obtaining a practical design guideline for the analysis of heat and power systems, combined pinch and exergy analysis (CPEA) is developed. This paper introduces the application of CPEA to advanced steam power plant. The paper presents a new methodology in optimization of steam extractions mass flowrate from multiple pressure levels of steam turbine with using CPEA. Efficiency improvement about 0.34% can be obtained by application of new approach and likewise, hot and cold utilities of cycle can be decreased.
Targeted Boiler Cleaning Using Smart Sootblower
Authors: Zhuang Huiying , Parikh Sandip , Shah Sandeep
Published: October 2008

A Smart Sootblower has been developed to meet the increasing demand for advanced boiler cleaning equipment. Utility plants are challenged to burn coals with severe slagging tendency. Slagging condition may be significantly different from pendant to pendant across the boiler. Conventional retractable sootblowers cleans superheat and reheat pendants with even intensity, resulting in over cleaning of some pendants and “clinker” buildup in others. Modern instrumentation such as SuperHeat Fouling Monitoring (SHFM) systems and Video Cameras is able to locate the exact spot where the slag is accumulated. With the help of these detention systems, the Smart Sootblower, a multi-mode soot blower, is able to target and adjust clean intensity based on slagging condition, thus minimizing tube leakage and clinker formation. The Smart Sootblower has two motors that independently control translation and rotation motion. This allows the sootblower to change helix for different cleaning in different sections of the boiler. Operators can select zones require aggressive cleaning and zones need less or no cleaning. Integration of SuperHeat Fouling Monitoring (SHFM) system would provide operators the knowledge of fouling condition and enable automatic control of sootblowers for optimal performance. Actual installations and data are presented.
On-LineTurbine Internal Efficiency Monitoring for Steam Turbine Condition Diagnostics
Authors: Berkovich Y. , Glickman S. , Levin L. , Eitan U. , Gordinsky A.
Published: October 2008

The integral diagnostics factor used for the evaluation of turbine island condition is the turbine heat rate corrected to constant steam parameters and condenser pressure which is called “corrected turbine heat rate”. In case of excessive deviation of corrected heat rate from its normal value, it is necessary to implement a diagnostic subsystem for determining the source of the deviation. The following subsystems of the turbine island have to be taken into consideration: turbine steam path, turbine end seals, control valves, etc. For each subsystem it is necessary to select the calculated or measured parameter(s), which will be used as diagnostic factors for turbine condition evaluation purposes. For the turbine steam path subsystemthe internal efficiency of the high pressure turbine (HP) and intermediate turbine (IP) can be used. Selection of the internal efficiency as diagnostics factor is based on its high sensitivity to variations in steam path conditions (erosion, steam path fouling and so on), as well as to steam path diaphragm and radial sealing conditions. However, the basic internal efficiency calculation results of HP and IP turbines at different loads, using measured parameters, show very high sensitivity of the calculation results to random measurement errors, random components of the regulation process and variations in spatial and time distribution of the temperature and pressure fields. This high sensitivity causes the uncertainty of the calculation results to approach ± 1.5 % and means that the results can not be used for diagnostic purposes. To achieve acceptable results for uncertainty (± 0.3 %) special methods of mathematical analysis need to be applied, including robust estimation, precise multivariate approximation, filtration and others. Furthermore, the HP turbine internal efficiency depends on control valve position and thus can not be directly used as a diagnostic factor in an on-line turbine diagnostic system. To solve this problem, special methods were developed for correcting the real efficiency value to the valve wide open position. The developed method was verified by a set of specially designed tests and results have shown that this technique can be applied for on-line calculations. The described system for on-line turbine internal efficiency monitoring was developed in cooperation between IEC and Berman Engineering Ltd. The system was implemented on a 550 MW unit and has been in operation for two years. The results of operation show that the system yields the required expanded uncertainty in the range of ± 0.3 %. The system is characterized by high reliability and a friendly interface.
Global Potential of Biomass: Heat, Electricity and Liquid and Gaseous Fuels Markets
Authors: Iyinbor Jude , Abayomi Ogunrinde
Published: October 2008

Negative environmental effects, diminishing fossil fuel sources and soaring oil prices are some of the pertinent factors militating against the long term usage of fossil fuels. These make the introduction of alternative energy sources an integral part of our global energy plan. On the contrary, established fossil fuel infrastructures, flexibility of fossil fuels and economic gains from the oil sector are a few reasons why there is a global attitude of ‘drill the last drop before developing sustainable alternatives’. There are various energy sources that have little environmental effects and are sustainable (e.g. wind, geothermal, solar, hydro, biomass, e.t.c.), but the potentials they do have when it comes to the major energy utilization forms (heat, electricity and liquid and gaseous fuels) will be a key determinant of how alternative energy sources will be able to match the seemingly invincible presence of fossil fuels. The biomass option is examined in this report considering its potential with respect to heat, electricity and liquid and gaseous fuels market. Factors that may favour or hinder its potential and suitable solutions on how the potential can be increased are also discussed.
Industrial Demonstration on NOx Removal by Gas Reburning in a 50MWE Tangential Pulverizing Coal-Fired Boiler
Authors: Lu Xiaofeng , Liu Hanzhou , Amano R. S.
Published: October 2008

More than 70% of NOx in air comes from various coal burning processes. Among NOx removal technologies, gas-reburning technology have been proven to be an available technology by all industrial demonstrations in USA and Europe. To identify the feasibility of NOx removal with gas reburning technology for low rank coal in China, an industrial demonstration test of NOx removal with the gas reburning technology was carried in a 220t/h tangential pulverizing coal-fired boiler in JiangYou power plant from 2002 to 2004. In the test, reburning gas and burn out air were arranged at the front and rear walls of the furnace in a creative way. It was the first time in the world for such an arrangement method of reburning gas and burn out air were applied. The relationship of NOx removal efficiency with the nature gas flow rate, the Oxygen content in the furnace and operating methods of ball mills (or the Third Air) were tested. During the test, the change of the temperature of superheat steam and the furnace temperature were measured. The industrial demonstration test results showed: the NOx removal efficiency may reach at 50% and NOx discharge content may be as lower as 200 mg/nm3 when the heat value of burning coal was about 18MJ/kg (LHV). Some factors, which affected the efficiency of NOx removal, were discussed in this paper.
Gray and Impaired Water Cooling in Surface Condensers and Heat Exchangers
Authors: Schumerth Dennis J.
Published: October 2008

In recent years, concern over the continued use of limited fresh water supplies or similarly, cooling towers and their essential makeup, high maintenance and associated chemical treatment requirements has spawned a clever, yet dramatic change in powerplant surface condenser and heat exchanger cooling. The paradigm shift away from the established and typical toward the unconventional has produced an innovative and non-traditional cooling water source for surface condensers and heat exchangers. Pundits suggest water shortages will increase the amount of water reuse (Chart 1) in the US from a current estimated 1.7 billion gallons to an estimated 12 billion gallons by the year 20152. Given this dramatic prediction, water reuse, or the reclamation and treatment of impaired or gray water will be driven by and emerge as market incentives joined at the hip by emerging or mandated effluent discharge standards. Without a clear understanding of the legislative and political landscape, regulative complexities that deal with this type of cooling water could conceivably lead to an unattractive environmental legacy. Having duly noted the “trend or aberration” dilemma, this paper will further identify efforts by the municipal wastewater treatment plants to economically process a usable product. We will investigate the impact of ancillary add-on costs absorbed by the electric utility such as secondary filtration and examine an actual case study involving the extensive use of gray water. Finally, the paper will evaluate new operational conditions, emerging new corrosion issues with suggested abatement, metallurgical changes, pollution considerations, maintenance issues and other mechanisms which have forced utilities to develop innovative solutions when employing impaired cooling water sources for the main surface condenser and other heat exchangers.
First Cost-Savings Step: Critical Equipment Selection
Authors: August J. K. , Dundon Ed , Vasudevan Krishna , Magninie Wayne H.
Published: October 2008

The typical plant Computerized Maintenance Management System (CMMS) holds several thousand components tags, although nuclear units may exceed 100,000. “Critical equipment” simplifies equipment selection for PM assessment and prioritizes corrective maintenance. However, critical equipment holds subtle meaning. Complex equipment, multiple failure modes, and multiple systems functional failure effects, can diminish critical equipment value. Applied to failure-preventing tasks, critical terminology should support performance-based preventive maintenance plans. Identifying critical equipment is only the start.
Response Calculation and Analysis of Torsional Vibration of Turbine-Generator Shafts
Authors: Zhang Zhi , Du Dongmei , He Qing
Published: October 2008

Due to the disturbance of electric power system or other shock load, the torsional vibration of turbine-generator shafts occurs. It is significant to calculate the response of torsional vibration excited by the disturbance of electric power system in order to analyze and prevent catastrophic accident. The multi-mass lumped model of turbine-generator shafts is used. A new method of response calculation of torsional vibration of turbine-generator shafts, the Increment Transfer Matrix method (ITM), which combines the Riccati transfer matrix method with the Newmark-β step-by-step integral method, is presented. By the ITM method, the transient response of torsional vibration of turbine-generator shafts, especially at the dangerous cross-sections, can be calculated. The responses of torsional vibration of 200MW turbine-generator shafts due to the generator at non-all-phase operation are calculated and analyzed. The cause of bolt broken of the coupling of intermediate-pressure rotor and low-pressure rotor and the coupling of generator and exciter are discussed. The results are identical with the data recorded in field.
Swirl and Lateral Injection for Improved Mixing and Combustion
Authors: Lilley David G.
Published: October 2008

The aerodynamics benefits of lateral jet injection into swirling crossflow have long been recognized and used by combustion engineers. Studies are reported here on research related to the correlation of data, for swirling flowfields with lateral jet injection and combustion. Combustion efficiency and the θ-parameter are found to correlate well aerodynamic influences for combustor design.
Achieving Simultaneous NOx and Combustion Improvements on a 90MW T-Fired Unit by Applying the Fundamentals
Authors: Storm Stephen K. , Storm Danny , McClellan Adam C. , Storm R. F. , Mulligan Jim
Published: October 2008

Storm Technologies in cooperation with AES Westover Station implemented a total combustion optimization system approach, including a fan boosted over-fire air system on Unit 13 to reduce the emissions of NOx while also improving and/or maintaining acceptable Carbon in Ash content levels on a daily basis. Implementation of this total airflow & pulverizer performance utilized a fundamental and proven approach to performance optimization and the system has been installed now for over two years and continues to be successful. The results of this systems modifications was up to 60% NOx reduction and payback in months by reducing the need for NOx credits and simultaneously improving unit performance, reliability and fuels flexibility. All of the goals of this program were accomplished and the technical success of this project is once again the results of applying a systematic and comprehensive approach addressing fundamental opportunities for improvement. The benefit of this total combustion optimization project was not only NOx reductions, but also reliability and “fuels flexibility”. Furthermore, foresight in this system was the ability to improve boiler efficiency, heat rate and reduce rates of ammonia when and/or if SCR or SNCR is installed. Since the installation of the FBOFA System it should be noted that AES Westover has been able to consistently attain between .25–.30 lbs/mmBtu NOx and single digit carbon in ash levels with no negative effects of the system installed. The goals of this project were as follows: 1. NOx Reduction from >.54lb/mmBtu (full load) – to ≤ 0.32 lb/mmBtu; 2. Flyash Carbon Content less than 10%; 3. Minimal slagging; 4. Operations with a minimum of 2% Oxygen to maintain a “slag friendly” furnace without exceeding the NOx limits; 5. Maximum Load Capability; 6. Maximum Fuel Flexibility; 7. Total Combustion Optimization & Performance Preservation.
Online Computing Model of Temperature Field of Turbine Rotor
Authors: He Qing , Du Dongmei , Chen Yuesheng
Published: October 2008

Computation of temperature field of turbine rotor is a two-dimension axisymmetric problem. A two-dimension computing model of rotor temperature field is obtained by the analysis and simplification of rotor geometry structure and boundary conditions. The finite difference method is used to compute two-dimension temperature field of turbine rotor in this paper, which has enough precision and low amount of computation for online monitoring. By simplifying the structure and boundary conditions of turbine rotor, the fifteen node types of rotor are obtained. The difference calculating formulas for all node types are given. According to the model and difference formulas, an online computing program of temperature field of turbine rotor has been developed and applied to a 200MW turbine. Color cloud picture of temperature field of turbine rotor is released online via Internet.
Advanced Nuclear Process Heat Concepts and Applications
Authors: Kuhr Reiner W. , Bolthrunis Charles , Corbett Michael , Lahoda Ed
Published: October 2008

This paper presents a summary of a screening study to select the most advantageous applications for nuclear process heat. The review is focused on the application of the Pebble Bed Modular Reactor (PBMR) technology adapted for process heat applications. This technology is unique in its smaller modular size and ability to deliver high temperature process heat at conditions that allow higher value applications. The implementation of projects for nuclear process heat and hydrogen production will require collaboration between nuclear power plant operators and process plant owners who will benefit from lower costs of heat delivery. Heat and hydrogen from nuclear water splitting can be used to displace expensive fuels, extend carbon utilization for products and reduce CO2 emissions and other environmental impacts.
Replacement Feedwater Heater Performance Modeling and Rating Calculations
Authors: Weber Gerald , Catapano Michael C.
Published: October 2008

It is not uncommon to expect that feedwater heaters will require replacement over their Unit’s service life. In some cases, Unit upgrades, changes in the full range of operation, and the absence of root cause failure analysis can lead to unsuitable replacements. Neglecting these considerations can result in the continuance of similar failures as heaters are either replaced in-kind or not to the extent necessary as dictated by the changes in load and/or how they are operated. The heater technical specification must not only address the obvious issues related to changes in tube material, quality control, and references to the current state-of-the-art heater standards, but also the full range of current and projected modes of operation. An important factor in obtaining a heater that will last reliably for many years is to specify one that will be versatile enough to handle not only the normal base load operation, but will also safely withstand higher loads, higher heat inputs, and other modes of operation reasonably expected. The replacement heater specification must define the full range of projected load impositions to allow the Vendor to consider and adapt his internal layouts and physical geometries to accommodate them safely and conservatively. This paper shall illustrate how performance modeling and predictive rating calculations can be valuable tools in helping to identify the full range of conditions to be considered by the Vendor so as to optimize the specification of the new heater. A variety of hypothetical cases can be examined in order to help determine the optimal design and its effects on the entire heater system as well as projected resultant differences in Unit load and heat rate or efficiency. Constructing a performance mode model, such as the PEPSE example utilized herein, for single heater analysis is quick and relatively easy. The feedwater and drain inlet conditions (temperature, pressure and flow), the heater shell pressure, and the required Terminal Temperature Difference (TTD) and Drains Cooler Approach (DCA) are inputs to the model which then calculates the required steam flow demand and the heater outlet conditions. Using this tool, the initial design, current minimum and full load (from plant historical data or PI data), future full load, abnormal/overload conditions and any other pertinent analysis may be accomplished. The key output data delivered by the model is the required steam and drain flows obtained by the energy balance. This information is then specified to the heater Vendors as it applies to the rating and physical sizing of the replacement. This information can be crucial to ensure that the replacement heater(s) will be capable of providing long, reliable life for even the worst load potentials.
Numerical Model and Optimization for Dynamic Characteristic of Damping Blade
Authors: Xie Yonghui , Zhang Di
Published: October 2008

The reliability of blade is very important for steam turbine. Adding damping structure can decrease dynamic stress of blade. Firstly, the numerical model for dynamic analysis of damping blade has been developed. The following matrices which are necessary for Finite Element analysis have been obtained: the stiffness matrix, mass matrix and damping matrix of Finite Element for blade and damper, then the gross Finite Element motion equation of the blade can be obtained. Secondly, the response energy formula of blade has been obtained by analyzing the relation between exciting force and response of blade, the response energy can be taken as optimization goal, POWELL Penalty Function Method is adopted as optimization algorithm. At last, the dynamic characteristic of a real blade is analyzed, some numerical results such as response energy varied with normal press force have been obtained, the normal press force of rubbing surface has an apparent effect on the damp and response energy of blade, it can change the dynamic characteristic of blade, and there is an optimal normal press force, which can lead to the minimum response energy of blade, i.e. the optimal damper for blade.
Accuracy Analysis of Code-Test Flow Measurements
Authors: Keyser David R.
Published: October 2008

Analysis and estimation of uncertainty is presented for several typical Code-test situations for PTC-approved, differential pressure, flow-measurement systems. These analyses trace the calibration pedigree from the fundamental standards at NIST to the implementation of the instrumentation at the test site.