bluuebunny/crossref_metadata_2025 huggingface dataset:
Improvements to Converting Moist Air Into Water and Power
Authors: Vidmar Robert J.
Published: September 2010

Moist air conversion to water and power by a system that uses atmospheric water vapor as its fuel is described. Water vapor is separated from moist air using a vapor separation barrier system. This system has atmospheric pressure on one side of the barrier and the opposite side has a low pressure maintained by the inlet of a vacuum pump/compressor system. The pressure difference across the barrier promotes water-vapor transport through the barrier into the vacuum-pump inlet. Additional compression is necessary to raise the water-vapor pressure and temperature to values appropriate for efficient energy transfer and condensation. The magnitude of compression depends on the ambient water-vapor concentration that varies with location and season. Intercooling between compressors and the magnitude of compression are issues. In this paper the use of a two-compressor system without intercooling is developed and applied to Miami, FL, during the summer. Output power calculations are modeled as an improved Rankine-cycle with reheaters, regenerators, and feedwater heating to improve overall cycle efficiency. The net power output for a water-vapor throughput of 1 kg/s (2.204 lbm/s) is +151.1 kW (+515.5 kBtu/hr) with the water discharged from the system as a liquid. A turbine-based power extraction system is described that uses the warmed cooling fluid flowing from the steam condenser following the main turbine for power production. This system converts approximately 1% of the heat from the condenser into power. System calculations are specific to humid coastal areas, such as Miami, FL.
An Alarming Increase in Catastrophic Thermal Fatigue Failures in Cold Reheat Lines: QAE NDI for On-Line, Post Thermal Shock/Water Hammer Assessment
Authors: Ezra Dan , Yagen James
Published: September 2010

Cold Reheat Piping has received little attention in power plants for many years. Carbon Steel piping that handles steam at 500 F to 600 F has only had problems when not properly supported or water hammered on start up. Most recorded failures have been mechanical fatigue at a girth weld. A number of catastrophic failures in Cold Reheat Piping have occurred in recent years. Most of these recent failures can be traced back to water hammer or a change in the operation of attemperator sprays. This paper shows how a Cold Reheat Piping system, that was included in a nondestructive test program, failed in a short period of time due to thermal fatigue, from a change in spray operation.
Simplified Morton Effect Analysis for Synchronous Spiral Instability
Authors: Murphy Brian T. , Lorenz Joshua A.
Published: September 2010

A simplified analytical approach for modeling the synchronous instability phenomenon known as Morton effect is presented. The analysis is straight forward and easily applied to any rotor supported on fluid film bearings. The analysis clarifies the interaction of three distinct machine characteristics which combine to create a case of Morton effect. Some example calculations are shown illustrating the possible types of spiral vibration. In addition, an analytical approach is described for estimating the magnitude of the shaft temperature difference in a journal bearing as a direct function of the shaft orbit. It is significant that this method can readily be applied to any type of journal bearing, from plain sleeve bearings to tilting pad bearings. Example calculations using the method are shown.
Prediction of Performance From PRB Coal Fired in Utility Boilers With Various Furnace and Firing System Arrangements
Authors: Chudnovsky B. , Talanker A. , Berman Y. , Saveliev R. , Perelman M. , Korytnyi E. , Davidson B. , Bar-Ziv E.
Published: September 2010

Present regulatory requirements enforces the modification of the firing modes of existing coal-fired utility boilers and the use of coals different from those originally designed for these boilers. The reduction of SO2 and NOx emissions were the primary motivation for these changes. However, economic considerations played a major role too. Using sub-bituminous coals has become an important solution for emissions compliance due to their unique constituents and combustion characteristics; these coals are often referred to as enviro coals. Powder River Basin (PRB) Coals are classified as sub-bituminous ranked coals. Unlike higher ranked bituminous coals, which have tight pore structures that limit the amount of moisture they could hold, low rank coals, such as PRB coals, have looser pore structure and additional moisture retention capacity. PRB coals differ in many properties from those of the commonly burned bituminous coals, including low heating value, low fusion temperature, and high moisture content. However, PRB coals have low sulfur content and are relatively low cost. They can also lower NOx emission from power plants due to higher volatile content. When power plants switch from the designed coal to a PRB coal, operational challenges, including transportation, handling, storage, and combustion, were encountered. A major problem faced when using PRB coals is severe slagging and excess fouling on the heating surface. Not only is there an insulating effect from deposit, but there is a change in reflectivity of the surface. Excess furnace fouling and high reflectivity ash may cause reduction of heat transfer in the furnace, which results in higher furnace exit gas temperatures (FEGT), especially with opposite wall burners and with single backpass. Higher FEGT usually result in higher stack gas temperature and increasing in the reheater spray flow and therefore decreasing the boiler efficiency with higher heat rate of the unit. The modification of an existing unit for firing of PRB coals is confined to — and constrained by — existing equipment. All successful conversions happen when in the design phase of a project the following parameters are evaluated: (1) capacities or limitations of furnace size, (2) firing system type and arrangement, (3) heat transfer surface, (4) pulverizers, (5) sootblowers, (6) fans, and (7) airheaters. In the present study we used a comprehensive methodology to predict the behavior of three PRB coals fired in a 575MW T-fired boiler.
Long Radius Flow Nozzle Study
Authors: Wakeland Richard
Published: September 2010

The objective of this study is to examine the American Society of Mechanical Engineers (ASME) Long Radius Flow Nozzle. This study was conducted with regard to published standards for design and installation, manufacturing, and the comparative analysis of laboratory flow calibrations to the theoretical predictions of the coefficient of discharge. Several sets of identically designed Long Radius Flow Nozzles were manufactured and laboratory flow calibrated. The results of the flow calibration data were used to evaluate the accuracy of the prediction equations for the Coefficient of Discharge and to determine the effects of materials and manufacturing processes such as post weld stress relieving. Preliminary results of continuing research indicate that the uncertainty of the coefficient of discharge may be 1% or less while the published uncertainty is 2%. These results indicate that well controlled design and manufacturing processes influence the flow nozzle performance. These results are based on flow calibration data from an independent laboratory. In conclusion, the long radius flow nozzle can be designed and manufactured so the uncertainty associated with the coefficient of discharge is less than published values. Further study is required of the published equations for predicting the coefficient of discharge.
Operation Strategies for Thermoelectric Power Plants With CO2 Emission Constraints in Italy
Authors: Gambini Marco , Vellini Michela
Published: September 2010

The effort of carbon dioxide emission reduction, required to the European countries, especially to Italy, is very remarkable, particularly in the thermoelectric sector. Because between the various policies and measures it is possible to adopt the mechanism of exchange (sale/purchase) of emission rights (Emission Trading), in this work the authors intend to focus on Italian thermoelectric sector and want to illustrate the energy and economic consequences of various operational scenarios that can be conceived for power plants, fuelled by natural gas. In fact, through the Kyoto protocol and its country-specific targets, power producers are strongly driven towards CO2-reducing solutions such as, for example, power modulation. Two examples of advanced thermoelectric power plants, operating in Italy, will be described: the first power plant produces only electric energy while the second one is a cogeneration power plant (it produces heat and electric energy). For both power plants, the best management criteria will be discussed in order to attain competitive performance of such facilities. The final goal is to minimize the cost of production (or to maximize profits), taking into account, however, the specific targets for CO2 emissions.
Generator Retaining Rings: In Situ Inspection and Life Assessment
Authors: Noteboom Jan Willem
Published: September 2010

Stress corrosion cracking (SCC) in retaining rings of generators has been a major issue since large generator manufactures started to advise generator owners to replace and inspect retaining rings made from certain materials in the mid 1990’s. KEMA has been inspecting generator retaining rings with automated systems from the seventies on. Since 1995 new developments led to the possibility of also testing rings in situ, eliminating the need of removing the rotor from the stator and thus saving considerable down-time. Over the years, step by step improvements to the system and its application to generator retaining ring inspections have been implemented, one of which is the use of smaller probes and manipulators. Another improvement is the implementation of eddy current testing (ECT) to increase the detection capability for cracking at the outside surface in parallel to the automated ultrasonic testing (AUT). Experience obtained with this method contradicts some of the common ideas about reliability of other Non-destructive testing (NDT) methods, in particular the application of Dye Penetrant inspection (DPI) which appears to be less reliable. By performing fracture mechanics calculations to evaluate detected and sized flaw indications, predictions of remaining life of the rings can be made (Fitness-for-Purpose analysis). This paper presents results of applying the in situ retaining ring inspection system in the last 14 years and gives an overview of cases — some of those from recent inspections — where defect indications were detected, sized and evaluated. In some cases this resulted in recommendations to replace the retaining rings.
Performance and Operational Issues at the Boardman Coal Plant
Authors: Rodgers David A. T.
Published: September 2010

The keys to reliable and efficient coal fired power plant operations are combustion and performance monitoring. For this to occur it is necessary for the plant staff to have adequate tools that will enable them to make intelligent decisions. Success in this endeavor is insured with proper instrumentation, vigilant operations and a real time performance monitor. This paper will cite efforts made toward combustion improvements through the use of pulverizer coal flow enhancements, coal flow monitoring instrumentation and simple coal analysis trending. This paper will also provide examples of the value of a real time performance monitor as a tool for monitoring, identifying and addressing plant efficiency. Examples of the unique capability of tube leak identification using the plant’s performance monitor will be presented.
Planning for Extensive Validation of the Siemens H-Class Gas Turbine SGT5-8000H at the Power Plant Irsching
Authors: Abens S. , Eulitz F. , Harzdorf I. , Jaenchen M. , Fischer W. , Rudolph R. , Garbett P. , Ratliff P.
Published: September 2010

In response to the increasing world-wide need for reliable, lowest-cost and environmentally compatible generation of energy, Siemens Energy has developed a new generation of H-class gas turbines with a power of 530+ MW and an efficiency of more than 60% in combined-cycle. The SGT5-8000H has been developed based on an evolutionary innovation concept which can be characterized by a technology platform strategy and prior component pre-validation. To ensure that the new product line can be brought to market with extensive testing and operation experience under real power plant conditions, a comprehensive validation program was launched in December 2007 at the prototypical power plant in Irsching. The 18 month validation program consists of multiple measurement campaigns, covering the full operation range starting from the hot commissioning to a final endurance test in single-cycle configuration. To gain the required data for the validation, the SGT5-8000H prototype has been equipped with close to 3000 measuring sensors and an extensive data acquisition system. For the realization of the largest gas turbine validation program ever conducted by Siemens, innovation in various aspects of test execution and evaluation had to be realized. Dedicated teams are operating and monitoring the engine operation from on-site and from the world-wide engineering locations utilizing real-time data acquisition, monitoring and evaluation methods. This paper describes the infrastructure and settings of the validation program in terms of the testing scope, facilities, methods and tools.
A Green Combined Cycle Plant: From Landfill to Power
Authors: Serbetci Walter I. , Kindt Greg S.
Published: September 2010

WorleyParsons has been contracted by the Klickitat Public Utilities District to design a nominal 26 MWe, 2×2×1 Combined Cycle Plant in order to expand the District’s existing landfill gas (LFG) power generation facility. The combined cycle plant is unique in that it will run only on LFG and will employ a state-of-the-art on-site regenerable LFG treatment and compression system. For the design of the LFG treatment system all current technologies were screened and the most economical ones chosen for implementation. The heat rate of the plant is calculated to be 8,245 Btu/kW-hr (LHV) gross and 9,260 Btu/kW-hr (LHV) net, at 90 °F ambient temperature and 1500 ft elevation.
Development of High Performance Moisture Separator Reheater
Authors: Fujita Issaku , Machii Kotaro , Sakata Teruaki
Published: September 2010

Moisture Separator Reheaters (MSRs) of Nuclear power plants, especially 1st generation type (commercial operation started from between 1970 and 1982), has been suffered from various problems like severe erosion, moisture separation performance deterioration, drain sub cooling. To solve these problems and performance improvement, improved MSR was developed. At the new MSR, high performance SS439 stainless steel round type tube bundle was applied, where heating steam distribution is optimized by orifice plate in order to minimize the drain sub cooling. Based on the CFD approach, cycle steam distribution was optimized and FAC resistant material application for the internal parts of MSRs was determined. As a result, pressure drop was reduced by 0.6% against the HP turbine exhaust pressure. Performance of moisture separation was improved by the latest chevron type separator. Where, the reverse pressure is locally caused at the drainage area of the separator because remarkable longitudinal pressure distribution is formed by the high-speed steam flow in the manifold. Then, a new moisture separation structure was developed in consideration of the influence that this reverse pressure gave to the separator performance.
Energy Efficiency by Optimizing Annual Testing Schedules: Coordinating RATA Testing With Other Annual Test Requirements
Authors: Toburen Tina , Kephart Allen , Walker Rhonda
Published: September 2010

Nearly every power plant in the US must undergo annual Relative Accuracy Test Audits (RATA testing) to confirm the values reported by their continuous emission monitoring systems (CEMS). In order to perform a RATA test, the plant must operate at one or more stable loads for a number of hours. Depending on the type of unit and fuel, the required load levels for RATA testing can range from low, mid and high loads for coal-fired units to a single (normal) load for oil and gas fired units or four loads (from partial load to maximum load) for units utilizing 40 CFR Part 75 Appendix E alternative monitoring systems. Many plants operate in a dispatch environment where the plant is not in control of their load from hour to hour, and some even from minute to minute, such as those operating under Automatic Generation Control (AGC). Scheduling plant loads for the RATA testing must often be done far in advance and can come at a high price when factoring in fuel costs. Because it can be a significant undertaking to schedule the loads for a series of RATA tests, it makes economic sense to schedule other testing also requiring unit stability concurrently with the RATA tests. One of the most important tests that fits this category is performance testing for plant capacity and/or heat rate. Many plants are now required to perform capacity and/or heat rate demonstrations on a periodic basis to support their power purchase agreements or transmission reliability requirements. But even plants without performance test requirements can benefit from gathering performance related data during RATA testing. For plants dispatched based on demonstrated heat rates, understanding the heat rate impact of operating in AGC or at partial loads is essential. Awareness of expected heat rate is also vital for plants that must nominate their fuel consumption requirements in advance. If the RATA test loads are planned correctly, performance data collected during the RATA test periods can be used not only to fulfill required demonstrations for capacity and heat rate, but also to determine the actual annual degradation (recoverable and non-recoverable) observed for the plant equipment. Test data can also be used to build or update performance forecasting tools for dispatch purposes. Depending on the complexity of the RATA testing, multiple load points may be available (from minimum to maximum load) which can provide data on fuel consumption at various loads, supporting fuel purchasing and planning requirements for the plant. This paper intends to outline the value of coordinating annual performance tests with RATA tests in terms of manpower, load scheduling and fuel consumption. This paper will also discuss a number of issues that may arise when coordinating multiple tests — which could be performed by numerous independent parties, as well as the additional benefits which can be gained by collecting adequate performance data during RATA test periods.
Pyrolysis and Steam Gasification of Paper and Evaluation of Paper Char Kinetics
Authors: Ahmed Islam , Gupta Ashwani K.
Published: September 2010

Main characteristics of gaseous yield from steam gasification have been investigated experimentally. Results of steam gasification have been compared to that of pyrolysis. The temperature range investigated were 600 to 1000°C in steps of 100°C. Results have also been obtained under pyrolysis conditions at same temperatures. For steam gasification runs, steam flow rate was kept constant at 8.0 gr./Min.. Investigated characteristics were evolution of syngas flow rate with time, hydrogen flow rate, chemical composition of syngas, energy yield and apparent thermal efficiency. Residuals from both processes were quantified and compared as well. Material destruction, hydrogen yield and energy yield is better with gasification as compared to pyrolysis. This advantage of the gasification process is attributed mainly to char gasification process. Char gasification is found to be more sensitive to the reactor temperature than pyrolysis. Pyrolysis can start at low temperatures of 400 °C; however char gasification starts at 700 °C. A partial overlap between gasification and pyrolysis exists and is presented here. This partial overlap increases with increase in temperature. As an example, at reactor temperature 800 °C this overlap represents around 27% of the char gasification process and almost 95% at reactor temperature 1000°C.
A Case Study of Optimizing Combined Cycle Performance at Kalaeloa
Authors: Andersen Helmer
Published: September 2010

Fuel is by far the largest expenditure for energy production for most power plants. New tools for on-line performance monitoring have been developed for reducing fuel consumption while at the same time optimizing operational performance. This paper highlights a case study where an online performance-monitoring tool was employed to continually evaluate plant performance at the Kalaeloa Combined Cycle Power Plant. Justification for investment in performance monitoring tools is presented. Additionally the influence of various loss parameters on the cycle performance is analyzed with examples. Thus, demonstrating the potential savings achieved by identifying and correcting the losses typically occurring from deficiencies in high impact component performance.
Design Methodology and Valve Sizing for Heater Drain Systems
Authors: Loughrin Casey
Published: September 2010

Heater drain systems in fossil and nuclear power plants have proven to be among the most complex systems to design due to the occurrence of two–phase flow phenomena. The overall performance of heater drain systems directly relates to proper sizing and design of the piping and control valves. Proper sizing is highly dependent upon accurate and conservative calculation of two-phase flow pressure losses. This paper outlines the various options of solution methods available to the engineer and details one possible method which is simple, yet adequate, and based on the homogeneous equilibrium model (HEM) for two phase flow for calculation of heater drain system performance. General comparisons are made to the more complex multi-fluid models, flow regime considerations, and non-equilibrium models.
Ultrasonic Condition Monitoring in Power Plants
Authors: Bandes Alan
Published: September 2010

Instruments based on airborne/structure borne ultrasound technology offer many opportunities for reducing energy waste and improving asset availability in power plants. They expand the concept of “Condition Monitoring” to include much more than basic mechanical fault inspections. Since these instruments detect friction, ionization and turbulence, their inspection capabilities range from trending bearing condition to determining lack of lubrication, locating compressed air leaks and detecting arcing, tracking and corona emissions in both open and enclosed electric equipment. Portable, instruments based on this technology are used to trend and analyze bearing condition, detect leaks (pressure and vacuum), test valves and steam traps, identify electrical problems and identify potential problems in gears, motors and pumps. This presentation will provide a brief overview of the technology, its applications, energy savings cost analysis and suggested inspection techniques.
Improvement of the Performance of a Utility Oil Fired Boiler by Modifying the Design of Burners and Atomizers
Authors: Diego-Marin Antonio , Melendez-Cervantes Carlos , Mendez Aranda Angel Alberto , Giles-Alarcon Armando
Published: September 2010

Reduction of both atomizing steam and particulate emissions were investigated in a 350 MWe utility boiler. A residual fuel oil was dispersed as a fine mist into the furnace with sixteen atomizers of internal turbulent chamber type. The existing atomizers were replaced by Y-jet type atomizers. To do this, full scale prototypes were designed and tested in a cold model rig using mineral oil as the fuel and compressed air as the atomizing medium. The oil droplet size distribution was measured from a single port of each prototype by using a Malvern particle sizer. The prototype to be tested in the power station was selected based on the smallest oil droplets produced along with lower compressed air consumption. In the power station, the burners were modified to install the new design of Y-jet atomizers. Field tests were conducted at 50, 75 and 100% load. Atomizing steam was measured, as well as particulate emissions and the furnace exist flue gas temperature. With the Y-jet atomizers, the atomizing steam was reduced 55% with respect to the original atomizers; the unburned carbon particles were reduced by a maximum of 50%, the furnace exit gas temperature was similar between the two type of atomizers and no side effects were observed in the boiler.
The Steam Turbine Retrofitting of Six Boiling Water Reactor Units Using Innovative Engineering and Laser Scanning Techniques
Authors: Jones Mike , Nelmes David J.
Published: September 2010

Alstom Power is executing the steam turbine retrofit of six nuclear units for Exelon Generation in the USA. The existing turbine-generators are an 1800 RPM General Electric design originally rated at 912 MWe and 1098 MWe and powered by Boiling Water Reactors. 18 Low Pressure inner modules will be replaced, with the first due to be installed in March 2010. This project is particularly challenging — the aggressive retrofit installation schedule is compounded by the requirement to handle radioactively contaminated equipment and also comply with demanding regulations applicable to BWR plant. The author’s company has extensive experience in the steam turbine retrofit business, having supplied around 800 retrofit cylinders globally since the 1970’s. However, this LP upgrade challenges the established techniques used in the business and requires extraordinary effort. Traditional retrofit engineering and installation principles have been interrogated and developed to meet the specific requirements of this project. Innovative techniques are introduced, including the extensive use of the Leica HDS 6000 laser scanner to model the existing plant. The approach has advanced the field of steam turbine retrofit design and installation significantly. The first section of this paper focuses on the extraordinary considerations of the project and the challenges surrounding BWR plant. The second part describes the laser scanning technique and the application of scan data. It outlines the innovative solutions which have been developed.
Determination of Fuel Input for a Coal Fired Plant Performance Test
Authors: Jin H.
Published: September 2010

In applying ASME PTC 46 “Overall Plant Performance” to a coal-fired steam plant, it is mandated that the heat input to the plant is determined by the product of heat input to the steam and the inverse of the steam generator fuel efficiency. Steam generator fuel efficiency is to be determined, per PTC 46, by the energy balance method as detailed in ASME PTC 4 “Fired Steam Generators”. ASME PTC 4 (1998) superseded an earlier Code, ASME PTC 4.1, which is no longer an ANSI standard or an ASME Code (as this paper was being written, PTC 4- 2008 has been published as a revision of PTC 4-1998). PTC 4.1 made use of a simplified “short form” to determine efficiency by what was known as the heat loss method, used by the industry for many years due to its ease of use. The energy balance method is fundamentally different from the heat loss method even in terms of the definition of efficiency and heat input. This paper explores the major differences between the two PTC’s (the defunct PTC 4.1 and PTC 4). Without knowing these differences, a direct comparison of PTC 4 and PTC 4.1 results is meaningless and could lead to false conclusions.
Micro-Hydro Power Systems: Current Status and Future Research in Pakistan
Authors: Chattha Javed A. , Khan Mohammad S. , ul-Haque Anwar
Published: September 2010

The total installed electric power capacity of Pakistan is about 20,000 MW. Pakistan is currently facing a power deficit of about 4,000 MW. This deficit is creating huge difficulties for the consumers as electrical power load shedding has become a norm in all over the country. Currently only about 33% of the total power is being produced by hydro sources and major electric power is still produced by burning oil and gas. The hydro potential of Pakistan is estimated to be about 41 GW, out of which 1,290 MW can be generated by micro-hydro systems. These potential off grid micro-hydro systems are very essential for the consumers living in the remote areas of Pakistan and may be installed on canals and water falls which are abundant in the remote areas. This paper discusses the potential and the status of installed of hydro power systems in Pakistan. Cross flow turbines are being manufactured in Pakistan and are usually quite successful for micro-hydro systems. However, cross flow turbines are not suitable for majority of the prospective site conditions. Furthermore, custom made conventional turbines are not mass produced and for the micro-hydro systems, standard centrifugal pumps may be used as turbines. These centrifugal pumps are easily available in the market at comparatively much lower cost and shorter delivery periods. A pump was installed at a suitable site for generation of electricity, while running in turbine mode. It was initially estimated that the Pump as Turbine, PaT would be able to generate about 70 kW of power based on the available flow rate and head parameters at the site. Currently only half of that power is being generated by the PaT, under study. Efforts are underway to rectify the problems being faced and improve the power generation capacity of the installed unit. This paper discusses the problems associated with the use of PaT and measures being undertaken to make it feasible for the use of micro-hydro systems. Two major issues; draft tube design and presence of trash in the canal water, responsible for performance deterioration have been discussed in this paper.
Design of a Free Turbine for Simulation of Flow in a Turbine-Annular-Diffuser-With-Struts Delivery System
Authors: Dakuri Srinuvasu , Roy Bhaskar
Published: September 2010

A free turbine is intended to produce the effect of a rotating flow field to be fed into a strutted annular diffuser for simulating a 3D fluid mechanic interaction and effect. This turbine is driven by the flow from a flow driver fan, upstream of the turbine. As sufficient pressure is required for the diffuser air flow, the concept of maximum work generation by a turbine is bypassed in the design intent. An inlet guide vane is designed for the turbine such that the rotational speed of the turbine matches the design intended speed and also produces an axial exit flow (no swirl) at design condition, and a rotating wake for off design conditions. The consideration of using of the inlet guide vanes (rather than usual stator-nozzles) is to avoid a mismatch between the absolute angle of the flow coming from the flow driver fan and the absolute design intent flow angle requirement, to run the turbine. Also, due to the 3D flow effects, some uncertainty exists in determining the exact entry air flow angle to the guide vane; this uncertainty is provided for with a rounded leading edge to the inlet guide vanes. The above design considerations when embedded in the conventional turbine design procedure resulted in an unusual turbine design with very low blade cambers.
Integrated Solar Cycles for Natural Gas and Coal Power Plants
Authors: Golden Gary , Libby Cara , Bell Robin
Published: September 2010

As fossil fuel prices rise and emission allowances are implemented, solar augmented steam cycles might be an attractive option for energy companies. The system utilizes steam generated by a solar field in a conventional natural gas or coal-powered steam cycle, offsetting some of the fuel required to generate power. Many energy companies are interested in adding solar power to their generating mix, but today most solar applications are not cost-competitive with other power generating options. Solar augmentation potentially is the lowest cost option for adding solar power to the generation fleet. The highest intensity solar energy typically is within a few hours of peak summer loads, making it a particularly attractive renewable option.
Application of CFD Modeling in HRSG Evase Design
Authors: Shi Xuefeng , Chriswindarto Wulang , Boyce David
Published: September 2010

Computational simulation of flow, heat transfer and combustion in a vertical tube heat recovery system generator (HRSG) with a single angel roof, a dual angle roof and an air flow optimized evase are studied. Existing theoretical models for flow and gas combustion [1] are used to predict how the three kinds of roof shapes influence the flue gas and temperature distribution in the whole HRSG System, and particularly the flue gas distribution upstream of first heat exchanger bundles (superheater 3 and reheater 2) and duct burner as well as the temperature distribution downstream of the duct burner. The gas phase conservation equations of momentum, enthalpy and mixture fraction are solved utilizing the k-(epsilon) turbulence model. A Finite Rate/Eddy Dissipation model and the P-1 radiation mode are used to predict gas combustion and radiative heat transfer, respectively. The simulation results show the air flow optimized evase not only provides a more uniform velocity profile upstream of the first heat exchanger bundle, but is also able to reduce the pressure drop through the whole HRSG system.
Earthquake Protection Strategies for Power Plant Equipment
Authors: Nawrotzki Peter
Published: September 2010

Power plant machinery can be dynamically decoupled from the substructure by the effective use of helical steel springs and viscous dampers. Turbine foundations, coal mills, boiler feed pumps and other machine foundations benefit from this type of elastic support systems to mitigate the transmission of operational vibration. The application of these devices may also be used to protect against earthquakes and other catastrophic events, i.e. airplane crash, of particular importance in nuclear facilities. This article illustrates basic principles of elastic support systems and applications on power plant equipment and buildings in medium and high seismic areas. Spring-damper combinations with special stiffness properties are used to reduce seismic acceleration levels of turbine components and other safety or non-safety related structures. For turbine buildings, the integration of the turbine substructure into the machine building can further reduce stress levels in all structural members. The application of this seismic protection strategy for a spent fuel storage tank in a high seismic area is also discussed. Safety in nuclear facilities is of particular importance and recent seismic events and the resulting damage in these facilities again brings up the discussion. One of the latest events is the 2007 Chuetsu earthquake in Japan. The resulting damage in the Kashiwazaki Kariwa Nuclear Power Plant can be found in several reports. Among other vital components, turbine equipment was damaged and overflow of fuel storage pools was observed (Fukushima, 2007 and Yamashita, 2008).
Characterization of Combustion Dynamics in Swirl Stabilized Flames
Authors: Idahosa Uyi , Saha Abhishek , Xu Chengying , Basu Saptarshi
Published: September 2010

This paper investigates flame frequency response relative to changes in swirl intensity and equivalence ratio in a non-premixed swirl stabilized burner. The degree of swirl in the burner is characterized by the swirl number (S) provided by circumferentially distributed air supply ports directed tangentially to the main axial air flow. Equivalence ratio variations are induced using varying constant, linear ramp and exponentially decaying fuel (propane) flow rates towards blowoff. The variations in the air speed at the exit of the burner (U) are measured with an anemometer located at the base of the flame. The emission of CH* radicals (I) is used as a marker of flame heat release and is measured using a photomultiplier (PMT). The frequency response of the PMT heat release and burner velocity signals are analyzed in the frequency domain using the Fast Fourier Transform (FFT) and Continuous Wavelet Transform (CWT) methods. Amplification in the power of heat release fluctuation is observed in low swirl flames close to blowoff. This effect is found to be reversed in higher swirl number flames even close to blowoff. In dynamic approaches to blowoff (using ramp and decaying fuel flow rates), the dominant heat release fluctuation frequencies are observed to be similar to perturbation frequencies in lean flames hovering at constant fuel flow rates close to blowoff.
Interpreting Constant Support Hanger Readings
Authors: Kimball Lange , Myers Carl , Johnson Michael
Published: September 2010

As the “baby-boomer” generation of power plant operators and maintenance personnel retire, enormous amounts of knowledge are lost. A part of this knowledge regards engineered products that support critical piping as well as boiler and turbine components. One such engineered product is the “constant support hanger”. The constant support hanger is a complex mechanical machine that is intended to provide a constant supporting load to the equipment regardless of the vertical movement experienced. This paper provides insights into how the constant support hanger can be visually inspected to: a.) Help assure that the support is operating properly, b.) How to interpret hanger settings to provide a means to gauge its operation, (c.) Recognize the constant support hanger from its numerous designs, vintages and manufacturers and (d) Provide insights into what can be done if problems are found.
Landfill Gas to Generate Power in Monterrey Mexico for Public Usage
Authors: Vega-Galaz Jose Ramon , Godoy Barahona Norma Gabriela , Saldan˜a Mendez Jaime , Gonza´lez Adriana
Published: September 2010

The power plant for public usage installed in Monterrey City using landfill gas is a case of success for Mexico and Latin America. This power plant supplies energy for lighting of seven municipalities around Monterrey including itself. It is also used to supply energy to the electric train for public transportation and other governmental buildings. To reach the final users it is utilized the electric grid owned by the state Company of Electricity CFE (Comisio´n Federal de Electricidad). This paper describes the technology chosen to generate the power and the operational strategies to maximize economical efficiency of this renewable energy system. Some points related with legal conditions to operate the power plant are also described.
Mobile Cogeneration Unit (MCU) Computational Model Adjusted With Test Cell Conditions to be Used to Predict Future Performance in Different Sites
Authors: Vega-Galaz Jose Ramon , Garci´a-Bulle´ Oscar , Cassel Ken
Published: September 2010

The mobile cogeneration unit (MCU) consists of two gas turbines and one heat recovery steam generator mounted in a trailer with standard dimensions to supply 3 MW of electricity at ISO conditions and 14,000 to 28,000 pounds per hour of superheated steam depending on duct burner duty and steam conditions. A computational model using Thermoflex software was developed to adjust Test Cell measurements with it. The purpose of this model is to predict MCU performance in different sites of implementation. Some field measurements in Test Cell and other sites are compared with model results showing very good approach.
The Radovich Cycle: A Novel MSW-Fired Heat Cycle
Authors: Radovich Michael
Published: September 2010

A conceptual study was performed for a novel heat cycle designed to utilize fuel gases produced by a Taylor Biomass Energy (TBE) Gasification System. The system is sized to consume 500 dry tons per day Municipal Solid Waste (MSW). The heat cycle utilizes a Solid Oxide Fuel Cell (SOFC) feeding directly to a Twin-Fluidized Bed Steam Gasification Unit (TFBSGU). MSW fed into the TFBSGU is partially gasified by exhaust from the anode space of the fuel cell. The resulting gas is cooled, sour-shifted, dehydrated and compressed. The compressed gas passes through an acid-gas removal (AGR) system and then is returned to the anode space of the fuel cell. Combustion air is compressed and passes through the cathode space of the fuel cell before entering the TFBSGU in a separate stream from the fuel gas. The resulting flue gas leaves the TFBSGU and is cooled and expanded before exhausting to atmosphere. The design also features sour shift and acid gas removal from the fuel stream. The plant produces 44 net MW, converting approximately 43% of the energy in the MSW into electricity and 23% of the energy into usable thermal energy. Overnight 2009 EPC costs are estimated at $6000/net kw. Electrical production costs are estimated at 126$/MWhr. Because the plant burns MSW, it provides carbon offsets. In addition, approximately 60% of the carbon dioxide produced by the plant can be readily sequestered. The conceptual design included a heat balance, water balance, auxiliary load list, capital cost estimate, and cost of electricity estimate.
Avoiding Common Pitfalls in Cooling Tower Pump Intake Design Related to Hydraulic Performance
Authors: Sassaman Timothy C. , Johansson Andrew E. , Padmanabhan Mahadevan
Published: September 2010

Cooling towers are an attractive method to provide cooling water to power plants and other process cooling applications. The use of cooling towers versus once-through cooling significantly reduces the amount of water drawn from rivers and lakes, which is particularly important in many regions in the Western United States where water availability is a problem. Cooling towers also eliminate thermal pollution due to cooling water discharges into and greatly reduce the amount of water withdrawn from natural bodies of water. Despite these advantages, cooling towers provide special challenges with regard to the design of cooling water pump intake structures. These challenges must be addressed to ensure a reliable flow of cooling water with a minimum expenditure of power in order to maximize the plant capacity and efficiency. Design factors such as footprint, civil constraints, increases in plant capacity requiring increased cooling flow, and off-design operation can all affect the flow hydraulics and therefore negatively affect the performance of the pumps. In this paper, general hydraulic design guidelines and performance acceptance criteria for pump intakes based on Hydraulic Institute Standards are outlined. Case studies from physical model studies of cooling water pump intakes are presented which may provide insight into likely problems and design flaws that engineers should be aware of while designing cooling tower pump intake structures. Examples of measures to avoid or remedy the commonly-encountered hydraulic problems derived from hydraulic model studies are discussed.
Set Point Calculation Model for a Paper Mill Power House to Minimize Fuel Consumption
Authors: Vega-Galaz Jose Ramo´n , Da´vila Ramo´n , Argu¨elles Jorge , Compea´n R. Federico I.
Published: September 2010

A Microsoft Excel model is presented to calculate set points of the elements involved in one paper mill power house to generate steam and power. The power house supply 100% of steam to the user and power is covered partially, the rest of the power comes from the public utility. This scheme generates some savings to the user, but this may be maximized calculating appropriate set points for steam and power production. The power house consists of two mobile cogeneration units or MCU’s and three package boilers that burn natural gas. Partial load characteristics of the power house elements are included in the model in order of having realistic results.
Preventing Condenser Tube Failures Through Effective Cleaning and Nondestructive Testing
Authors: Fayard Eric H. , Fischer Gary
Published: September 2010

Generating companies lose hundreds of millions of dollars annually to problems related to condenser and heat exchanger fouling, corrosion and tube leaks. In fact, the Condenser Tube Failure Control Program of Electric Power Research Institute (EPRI, Matthews, J.) disclosed that condenser tube failures contributed to almost 25,000 outages nationwide during a recent four year period and continue to be one of the most pressing issues related to plant output and availability. To adequately prevent condenser tube failures, effective condenser tube cleaning and nondestructive testing must be performed. Effective tube cleaning should ideally remove all deposits, leaving only the cleanest metal surface. Once tubes are free of fouling deposits, multi-frequency eddy current testing should be used to establish the overall integrity of condenser tubes. Plugging is recommended for the tubes with poor integrity that put condenser reliability at risk. If tube failures do occur, advances in tracer gas leak detection, specifically those using sulfur hexafluoride and helium, can be used to quickly locate sources of circulating water tube leakage and return the unit to reliable operation. This paper will examine implications of condenser tube fouling and failure, and the available nondestructive technologies for their prevention and correction.
Fast Degas Carbon Dioxide Evaporator
Authors: Howard Kyle T. , Ramirez Blanca A.
Published: September 2010

Two reasons exist for the rapid degassing of Hydrogen cooled generators. The first is an upset condition which could cause an unsafe condition or generator failure if the Hydrogen is not removed. The second is the time savings that can be recognized by reducing the time required to fully purge the generator and refill during an unplanned or planned outage. A generator bearing fire is an example of the first condition where the ability to remove the Hydrogen and purge with Carbon Dioxide rapidly would result in a significant reduction in the risk of a catastrophic situation. Current purge operations typically require many hours for the gas change from Hydrogen to Carbon Dioxide during maintenance outages. This new system reduces the time required for this step to less than 20 minutes. Times for refilling can also be reduced by similar amounts. This time can be extremely valuable during peak generation periods. The Carbon Dioxide vaporizer systems that have been installed previously have been limited by the rate they can vaporize the Carbon Dioxide and feed the gas to the generator without freezing. The system described uses flow controls, a large heater and backup Carbon Dioxide storage to perform the necessary operations quickly. The system can be operated manually or fully automatic. Automatic operation is preferred for the safety concerns since any fire or other upset would likely occur in the area of the equipment and time would be of the essence. The system described has been installed and tested in a number of operating plants and is performing satisfactorily.