bluuebunny/crossref_metadata_2025 huggingface dataset:
PBMR Update and Status on Process Heat Applications
Authors: Kuhr Reiner , Wallace Ed , Kriel Willem , Greyvenstein Rene´e
Published: May 2009

PBMR (Pty) Ltd. is undertaking the implementation of its demonstration project in Koeberg, South Africa with construction planned to start in 2008. Key test facilities have been completed and full-scale tests of first-of-a-kind components are underway. PBMR (Pty) Ltd., as part of a Westinghouse-led consortium, has been awarded the lead contract for the pre-conceptual design of the NGNP project; which could lead to a major demonstration project in the US some time next decade. Also, PBMR is working with Shaw and Westinghouse to develop several important non-power applications, using the high temperatures available from a 500MWt version of the reactor to produce high pressure steam for oil sands in-situ recovery operations, high temperature energy for steam methane reforming, and for thermal water splitting to produce hydrogen and oxygen. Water splitting offers dramatic improvements in coal-to-methane and coal-to-liquids applications by avoiding the inefficiencies of converting coal to hydrogen, with its associated CO2 emissions. This paper presents an update of the status of this work and the projected uses of this breakthrough nuclear technology.
Reliability Improvement and Failure Avoidance for Gear Speed Reducers
Authors: Bloch Heinz P. , Rehmann Chris A.
Published: May 2009

Many gear speed reducers in the Power Generating Industry suffer from premature failure of gears and / or shaft support bearings. This paper and presentation describes proven strategies for failure avoidance. It gives cost justification calculations and shows case histories dealing with gearboxes in the Southern United States and other parts of the world. Implementation of these strategies has rapidly demonstrated its cost-effectiveness. Actual installation details are highlighted.
Design, Manufacturing and Testing of a New Family of Steam Turbine Low Pressure Stages
Authors: Cosi Lorenzo , Slepski Jonathon , DeLessio Steven , Taviani Michele , Mujezinovic´ Amir
Published: May 2009

New low pressure (LP), stages for variable speed, mechanical drive and geared power generation steam turbines have been developed. The new blade and nozzle designs can be applied to a wide range of turbine rotational speeds and last stage blade annulus areas, thus forming a family of low pressure stages—High Speed (HS) blades and nozzles. Different family members are exact scales of each other and the tip speeds of the corresponding blades within the family are identical. Thus the aeromechanical and aerodynamic characteristics of the individual stages within the family are identical as well. Last stage blades and nozzles have been developed concurrently with the three upstream stages, creating optimised, reusable low pressure turbine sections. These blades represent a step forward in improving speed, mass flow capability, reliability and aerodynamic efficiency of the low pressure stages for the industrial steam turbines. These four stages are designed as a system using the most modern design tools applied on Power Generation and Aircraft Engines turbo-machineries. The aerodynamic performance of the last three stage of the newly designed group will be verified in a full-scale test facility. The last stage blade construction incorporates a three hooks, axial entry dovetail with improved load carrying capability over other blade attachment methods. The next to the last stage blade also uses a three hooks axial entry dovetail, while the two front stage blades employ internal tangential entry dovetails. The last and next to the last stage blades utilize continuous tip coupling via implementation of integral snubber cover while a Z-lock integral cover is employed for the two upstream stages. Low dynamic strains at all operating conditions (off and on resonance speeds) will be validated via steam turbine testing at realistic steam conditions (steam flows, temperatures and pressures). Low load, high condenser pressure operation will also be verified using a three stage test turbine operated in the actual steam conditions as well. In addition, resonance speed margins of the four stages have been verified through full-scale wheel box tests in the vacuum spin cell, thus allowing the application of these stages to Power Generation applications. Stator blades are produced with a manufacturing technology, which combines full milling and electro-discharge machining. This process allows machining of the blades from an integral disc, and thus improving uniformity of the throat distribution. Accuracy of the throat distribution is also improved when compared to the assembled or welded stator blade technology. This paper will discuss the aerodynamic and aeromechanical design, development and testing program completed for this new low pressure stages family.
New Dry Low NOx Combustor for Mitsubishi M501/701G
Authors: Tanimura Satoshi , Akamatsu Shinji , Sato Kenji , Koeneke Carlos
Published: May 2009

MHI G class gas turbine was designed to operate with a Turbine Inlet Temperature (TIT) of 1500 °C. This elevated temperature results in high thermal efficiency but also can induce relatively high emissions. MHI has developed a new Dry Low NOx (DLN) combustor that improves this class turbine compliance with stringent environmental regulations imposed around world. In addition to targeting an environmentally friendly combustor with lower emissions, the redesigned DLN combustor also improves the stability margin. Verification tests of the new DLN combustor were conducted in a M501G1 gas turbine at MHI’s T-Point Combined Cycle Power Plant from May, 2005 to March, 2007. In addition to verifying lower emission levels, these tests confirmed a wide stable operation margin as well as the reliability and durability of the components. The new design is optimized to be retrofitted into existing G class engines. The combustor is now in mass production as a MHI’s standard combustor. This paper describes the design process applied for the new combustor, including the Computational fluid Dynamics’ (CFD) and other analytical tools used.
Testing of Inter-Laminar Insulation of Stator Cores Using ELCID
Authors: Sasic Mladen
Published: May 2009

The reliability of large generators is of major importance to maintain the integrity of power plant. Continuous monitoring or frequent inspection is therefore desirable to be able to remedy growing defects before a catastrophic failure or more major work becomes necessary. Recent test information may also permit more effective use of routine or unscheduled outages by means of additional preparation and provisioning. The stator core is a major electro-mechanical component of a generator to which this applies in particular, as failure and associated repair or replacement necessitates major disassembly of other parts of the machine. Information on condition of the core structure is therefore significant, but is increasingly difficult to obtain at frequent intervals. Low power core testing can be performed more quickly and easily than using traditional full flux methods and may need to be considered an indispensable tool to increase or maintain essential monitoring levels. Low power core testing presents opportunities to maintain the level of stator core lamination monitoring in a more time and resource efficient manner using comparatively short windows in available outage time, often partly overlapping with other concurrent maintenance activities. These opportunities are enhanced with wider use of low power EL CID testing without removal of the rotor, not feasible with thermal loop tests.
Steam Turbine Condition Monitoring (TCM)
Authors: Nagel Christof
Published: May 2009

Interest in online turbine condition monitoring has increased among utilities in order to minimize unforeseen standstills and for better planning of overhauls or repair work. The AMODIS® (ALSTOM Monitoring and Diagnostic System) Steam Turbine Condition Monitoring system monitors steam turbines locally or remotely via long distances [1]. The system also collects all data to compare current events with past events. This monitoring system is not an expert system recommending how to solve malfunctions. It is more a system which helps operators to take measures before the standard alarm or turbine trip is activated. An interlock of the process parameters generates early warning alarms which are based on the OEM experience and help operators to get a clear picture of an arising problem and to react early enough to avoid forced outages. Additional sensors for additional process parameters have to be installed. The system is part of the AMODIS plant monitoring system and consists of six separately available modules: • Steam inlet valves: To detect increased friction in the actuator and the steam valve guide. • Jacking oil and turning gear: To detect malfunction in the jacking oil and turning gear systems. • Bearing supervision: To detect possible tilting of the bearing pedestal or abnormal oil consumption. • Thermal expansion: To detect extreme or abnormal differential expansion and to detect expansion hindrance. • Thermal efficiency: To detect loss of internal efficiency at an early stage. • Lube oil condition monitoring: To monitor the oil with an online particle counter and a sensor for content of water. All modules can be supplied separately. Modules to check vibration and performance are also available in an AMODIS system but are not covered in this paper.
Importance of Physics-Based Prognosis for Improving Turbine Reliability: RRA 501KB Gas Turbine Blade Case Study
Authors: Koul Ashok K. , Bhanot Saurabh , Tiku Ajay , Junkin Brent
Published: May 2009

Prognosis and health monitoring (PHM) technology needs to be developed to meet the challenges posed by aging gas and steam turbines in power plants, transportation systems, gas pipelines, and other industries. It is necessary to use physics based residual life prediction and life extension techniques to take into account the state of damage due to prior service. This paper focuses on the requirements of the technology and the state of the development to date. In this study, Life Prediction Technologies Inc.’s (LPTi’s) prognosis tool known as XactLIFE™ was successfully used to establish the fracture critical location of RRA 501KB first stage gas turbine blades under steady state loads and to compute the average life to creep crack initiation in the blade airfoils. The analysis used typical engine operating data from the field in terms of engine speed and average turbine inlet temperature (TIT). The blade is known to suffer airfoil untwist and lengthening during service and this is obviously followed by stress rupture failure. The primary objectives of the case study are to show how prognosis can allow a user to predict fracture critical locations to avoid failures.
Prediction of Performance and Pollutant Emission From Bituminous and Sub-Bituminous Coals in Utility Boilers
Authors: Saveliev Roman , Chudnovsky Boris , Kogan Ben-Zion , Korytnyi Efim , Perelman Miron , Sella Yoram , Spitz Nadine D. , Bar-Ziv Ezra
Published: May 2009

Computational Fluid Dynamic (CFD) models give good predictions of coal combustion in utility boilers if the coal combustion kinetic parameters are known. We developed a three-step methodology to provide reliable prediction of the behavior of a coal in a utility boiler: (1) Obtaining the combustion kinetic model parameters from a series of experiments in a test facility, CFD codes and optimization algorithm. (2) Validation of the combustion kinetic parameters by comparison of different experimental data with simulation results obtained by the set of combustion kinetic parameters. (3) The extracted kinetic parameters are then used for simulations of full-scale boilers using the same CFD code. Three to four bituminous and sub-bituminous coals with known behavior in Israel Electric Corporation (IEC) 550MW opposite-wall (3 coals) and 575MW tangential-fired (4 coals) boilers were used to show the capability of the method. An unfamiliar bituminous coal was then examined prior of its firing in the utility boilers and prediction of its combustion behavior in the two boilers was carried out. This methodology was used to examine a Venezuelan coal that was found to yield high LOI.
Alternatives to Meet Short-Term Electrical Capacity and Demand Requirements for Fort Wainwright, Alaska
Authors: Brown William T. , Vavrin John L. , Lorand Robert T.
Published: May 2009

A study team was commissioned by Headquarters, United States Army Installation Management Command (HQ IMCOM), under the leadership of the U.S. Army Engineer Research and Development Center-Construction Engineering Research Laboratory (ERDC-CERL), to determine the electric power requirements of Fort Wainwright, Alaska (FWA) through the year 2020, and energy supply alternatives to meet these requirements. Of particular importance was the impending winter and the fact that the installation thought it would not have the ability to meet all electrical demand, in approximately six months. Although several studies of the FWA electric power situation were performed over the past few years, the major concern was that recent increases in demand due to new construction brought about by newly added troop deployment units to the installation, a reduction in the number of facilities scheduled for demolition, coupled with the temporary loss of some generating capacity from the FWA Central Heating and Power Plant (CHPP), could result in a power shortfall during the upcoming 2006/2007 winter season. The study involved the following six primary tasks: (1) Establishing the generating capabilities of the FWA CHPP as well as FWA’s electric power import capacity, based on existing interties to the local utility; (2) Determining the annual electric power requirements through the year 2020; (3) Performing a limited condition assessment of the CHPP-related electrical system to identify critical items in need of repair/replacement; (4) Determining the ability of the local electric utility and other electric power suppliers to meet FWA electric demands through the year 2020; (5) Identifying options for meeting any electric power shortfalls likely to occur through the year 2020; and (6) Identifying methods and costs to improve electrical reliability focusing on redundart equipment and systems. The study determined that the potential power shortfall ranged from 2.3 megawatts (MW) to 3.8 MW for the winter of 2006/2007; 3.6 MW to 5.1 MW for the winter of 2007/2008; 6.3 MW to 7.8 MW in 2011; and 9.7 MW to 11.2 MW by the year 2020, Furthermore, the study corroborated earlier reviews that the switchgear was in immediate need of attention to ensure safe and reliable operation. The subsequent recommendations, which were implemented, included the installation of a nominal 7.5 megavolt-ampere (MVA) transformer to increase import capacity to meet potential shortfalls between 2006 and 2007 and a detailed review of the switchgear condition. Recommendations for upgrade of the switchgear are being pursued, along with further increase in transformer capacity (2 × 20 MVA substation) to ensure no electric power shortfalls through the year 2020.
Probabilistic Model-Based Fault Diagnosis of the Rotor System
Authors: Shao Jiye , Wang Rixin , Gao Jingbo , Xu Minqiang
Published: May 2009

The rotor is one of the most core components of the rotating machinery and its working states directly influence the working states of the whole rotating machinery. There exists much uncertainty in the field of fault diagnosis in the rotor system. This paper analyses the familiar faults of the rotor system and the corresponding faulty symptoms, then establishes the rotor’s Bayesian network model based on above information. A fault diagnosis system based on the Bayesian network model is developed. Using this model, the conditional probability of the fault happening is computed when the observation of the rotor is presented. Thus, the fault reason can be determined by these probabilities. The diagnosis system developed is used to diagnose the actual three faults of the rotor of the rotating machinery and the results prove the efficiency of the method proposed.
Enhancing Life and Reliability of Existing Superheaters and Reheaters: Seventeen Years of Performance
Authors: Hara Kevin G. , Burnett Thomas D.
Published: May 2009

A review is presented of 17 years experience in the application of a technology to increase the reliability of superheaters and reheaters without replacement. More than 20 superheaters and reheaters have been modified and have accumulated more than one million hours since they were modified. The technology, called TubeMod, optimizes the temperature profiles by redistributing steam flow from cold tubes to hot tubes to reduce peak temperatures to enhance life and avoid future failures. Removal of high temperature restrictions and application on a T91 superheater are also discussed.
POS Definition and Transition Risk Modeling Guidance
Authors: Rochon Chris , Finnicum David
Published: May 2009

Under the auspices of the Standards Developing Organizations (SDOs), the nuclear industry is currently in the process of developing standards for Probabilistic Risk Assessments (PRAs) to support risk-informed applications of nuclear power plants, including PRA standards for Low Power and Shutdown (LP/SD) operations. A particularly challenging part of building a LP/SD PRA model is the definition of quasi-steady Plant Operating States (POSs). This document provides guidance for developing the POSs needed for the creation and use of a LP/SD risk model based on a standard set of 15 generally applicable POSs. NUREG/CR-6144, prepared by the Brookhaven National Laboratory for the Nuclear Regulatory Commission (NRC) (for the Surry plant), was used as a foundation to build the set of standard set of 15 POSs presented here. Within these standard POSs, there is room for modification for plant- and application-specific purposes such as the specific LP/SD risk application of transition risk analysis. Specifically, modifications are accomplished by subdividing POSs. Another particularly challenging part of building a LP/SD PRA model is defining and modeling periods of transition which for the suggested guidance, are defined as risk-significant activities between quasi-steady POSs which involve significant configuration changes. This guidance provides support for developing the models needed for the evaluation of the risk associated with plant transitions occurring in the process of the plant shutdown and startup. Specifically, guidance is provided to lead a PRA modeler through the identification and characterization of the transitions and the selection and generation of appropriate transition PRA modeling elements and data. The transition modeling guidelines are applicable for procedure-based transitions (as opposed to physical-phenomenon-type transitions such as the drop in decay heat level) occurring during LP/SD operations. The guidance presented is intended to be applicable for all Light-Water Reactors (LWRs). The detailed guidance processes described are currently focused on Pressurized-Water Reactors (PWRs).
Experience of the On-Line Turbine Cycle Efficiency Monitoring System Operation
Authors: Berkovich Y. , Eitan U. , Levin L. , Gordinsky A. , Berman M.
Published: May 2009

The most commonly used method for control over the turbine island efficiency variation is turbine balance test. However, this test requires many various resources and is therefore rarely performed. Besides, such tests are performed for a simplified variant of the cycle that’s why the test results are not suitable for the real operational conditions. For these reasons the balance test can not solve a variety of important problems: - to keep track of heat losses caused by the deviation of the operational parameters from their optimal values and, overall, by an unsuccessful operation of the equipment; - to evaluate the heat losses caused by the equipment degradation which is necessary in order to optimize the start and duration of repair works; - to compare an operation quality of different units with different operational conditions. All the above mentioned problems can only be solved by using the efficiency monitoring systems. But for these monitoring systems to have practical significance the following principal requirements must be fulfilled: - the integral diagnostic factor has to be found; this factor must have a high sensitivity to the turbine cycle efficiency variation as well as to the variation of turbine cycle equipment conditions; - the low uncertainty of the diagnostic factor calculation results has to be provided, the uncertainty value must be sufficiently close to the one of the traditional test results. In the presented paper our experience of operating the online turbine cycle Efficiency Monitoring System is described.
LNG Interchangeability in Land Based Gas Turbines: The Siemens Approach
Authors: Nag Pratyush , Abou-Jaoude Khalil , Mumford Steve , Wu Jianfan , LaGrow Matthew , Engel Jacqueline , Rising Bruce
Published: May 2009

Liquefied Natural Gas (LNG) from offshore reserves is expected to expand its role in supplementing US natural gas supplies. The quality and hydrocarbon contents of the natural gas imported from these international sources, frequently differs from the compositions of domestic natural gas. With the range of variations in fuel characteristics known to exist with offshore LNG, use of this LNG in gas turbine engines could violate applicable fuel specifications, and lead to operational issues such as, but not limited to, combustion dynamics, flashback, increased emissions, or decreased component life. Another potential issue for gas turbines generating power is that rapid changes in the fuel characteristics that may occur when blending imported and domestic gas, may lead to substantial fluctuations in power output. Fuel flexibility is dominantly tied to the combustion system design. Conventional diffusion flame combustion systems are more tolerant of wide variations in fuel compositions but they are limited by their emission levels. The more advanced premixed flame combustors, the Dry Low NOxs (DLN) and Ultra Low NOx (ULN) combustion systems have significantly better performances in terms of emissions but they are also more sensitive to changes in the fuel composition and characteristics. Siemens has performed test campaigns with commercially operating engines and high pressure combustion test rigs to evaluate their commercially available combustion system configurations for LNG applicability. From these test campaigns, Siemens has defined the set of combustion hardware modifications which is robust to changes in fuel composition within the tested limits. Along with the said combustion hardware upgrade, Siemens has also designed an Integrated Fuel Gas Characterization (IFGC) system (Patent Pending). This IFGC system acts like an early warning system and feeds forward signals into the plant control system. Depending on the changes in the properties of the incoming fuel, the IFGC system is designed to adjust the engine tuning settings to compensate for these dynamic changes in the fuel. Customer implementation of the required hardware as well as associated site-specific engineering will mitigate the operational and emissions risk associated with the fuel changes. Overall, it is Siemens recommendation that LNG type fuels will be acceptable to be used in Siemens Gas Turbines with the preferred combustion hardware in place along with the Integrated Fuel Gas Characterization System. A site specific evaluation would be required to determine the optimal system depending on the expected fuels that the unit would be operating with, along with the emissions permit levels associated with the site.
Consideration of Co-Variance in Power Plant Test Uncertainty Calculations
Authors: Sullivan Terrence B. , Kirkpatrick Keith
Published: May 2009

One of the most important aspects of American Society of Mechanical Engineers (ASME) Performance Test Code (PTC) thermal performance testing is the proper determination of test uncertainty since the Uncertainty Analysis (UA) validates the quality of a test as well as demonstrates that the test meets code requirements. It can also carry a commercial relevance when test tolerances are linked to uncertainty figures. This paper introduces an approach to the calculation of the random component of uncertainty when covariance exists between certain primary measurements in thermal performance testing. It demonstrates how to identify parameters that are co-variant, provides a methodology for properly calculating the aggregated random uncertainty of co-variant measurements, and discusses the effect of co-variance on UA results.
A Real Time Dynamic Model of a Micro-Gas Turbine CHP System With Regeneration
Authors: Gambarotta Agostino , Vaja Iacopo
Published: May 2009

A model of a Micro Gas Turbine system for cogeneration is presented. The analyzed plant is based on an aero derivative Gas Turbine with a single staged centrifugal Compressor and an axial Turbine with two stages. The net power output is 260 kWe in simple cycle mode. Exhaust gases can be sent to a counter flow surface compact heat exchanger for thermal regeneration, which turns to be thermodynamically favourable in this range of power output. If a thermal load is required the system operates in CHP configuration and part, or the whole, of turbine exhaust gases are sent to a Heat Recovery Boiler for water heating. The HRB is, in analogy to the Regenerator, a counter flow surface heat exchanger. The mass of hot gases directed to each heat exchanger can be controlled by a regulation valve that allows, for a given fuel mass flow rate, to enhance the net power output or to privilege the thermal generation at the HRB. This degree of freedom allows the system to operate at different cogeneration degrees, thus covering many power-to-heat demand ratios. The whole system is modeled in the Simulink® environment, a powerful tool for dynamic system analysis. All components are studied and a mathematical representation for each of them is described. Equations are then implemented in Simulink® allowing to create customized blocks of different components which are then properly coupled, respecting the physical causality of the real system, by connections that may represent either mechanical or fluid dynamic links. Models are classified depending on whether state variables for the considered component can be defined or not. Compressor and turbine are represented as “Black Box” components without state, while the combustion chamber is modelled as a “white box” applying energy and mass conservation equations with three state variables. Heat exchangers are considered as “White Box” without state, and the physics of the heat exchange process is studied according to the Effectiveness-NTU method. A further dynamic equation is the shaft dynamic balance equation. Model results are reported in the paper in several transient conditions: in all cases the computational time proved to be lower than real time.
Challenges, Considerations and Options to Effectively Refurbish Lube Oil and Hydrogen Coolers
Authors: Smith James W.
Published: May 2009

Power plants today are plagued with aging balance-of-plant heat exchangers, particularly lube oil coolers and hydrogen coolers that have reached the end of their useful lives. Refurbishment of these coolers requires that Plant Engineers and Maintenance Personnel carefully evaluate the extent of the damage, research available solutions and develop a plan of action. A better understanding of what must be considered and what options are available will allow them to perform these tasks more effectively. This paper illustrates the challenges, considerations and options to effectively refurbish lube oil and hydrogen coolers as well as refurbishment activities, specialized tools, techniques and procedures. Also discussed are examples of common problems encountered and their solutions.
Comparison of ASME PTC-46 Performance Test Correction Factors as Estimated in a Project Proposal Phase to Those Determined During Project Implementation
Authors: Deen Philip G. , Gutierrez Juan , Sullivan Terry B. , Friedman Jeffrey R.
Published: May 2009

Accurate performance correction equations are essential to the successful implementation of an initial performance test of a new unit, and to continually monitor performance in a meaningful way. Developers of these formulations must consider the latest design information of all major equipment in the cycle. Per Section 5.3.5 of ASME PTC 46–1996 [Ref. 1], these corrections are to be developed from a heat balance computer model after it is “finalized following purchase of all major equipment and receipt of performance information from all vendors.” This paper reviews the requirements for the development of accurate correction curve/factor formulations for a typical combined cycle power plant, and demonstrates how significantly skewed the results of a test can be if assumptions on equipment design performance are made prior to manufacturers’ final submittals.
Moving to Market-Based Photovoltaics: The Impact of PV Costs and Performance on PV Incentives
Authors: Simons George , Scheuermann Kurt , O’Kelly Myles , Landry Pierre
Published: May 2009

This paper presents the results of a study conducted by Itron for the California Public Utilities Commission (CPUC) to examine the relationships between solar photovoltaic (PV) performance, costs, and PV incentive structures. The intent is twofold. The first intent is to create a baseline of PV performance and costs using actual performance data and reported costs from a large number of PV systems installed and operating in California. The second intent is to examine how PV performance and projected PV cost reductions can influence PV incentive payments. This study should help provide policy makers responsible for developing PV incentive programs with information that will result in incentive structures that fairly and transparently reward improved PV cost and performance while simultaneously providing a reasonable pathway to move PV towards an incentive-free market environment. PV performance monitoring data for over one hundred operating commercial, industrial, and institutional solar PV systems are combined with projected electricity retail rates and future PV costs within a breakeven levelized cost model to produce associated PV incentive levels. Preliminary results for 39 prototype PV market scenarios provide insights into how PV incentive levels can be set to take advantage of utility-specific electricity retail rates, PV configuration and location, and projected PV cost reductions while facilitating the development of PV systems that can compete without incentives. Potential implications of these performance and cost-effectiveness results are discussed with respect to PV incentive programs and PV markets.
Quantification of Greenhouse Gas Emission Reductions From California Self-Generation Incentive Program Projects
Authors: Khursheed Aaiysha , Simons George , Souza Brad , Barnes Jennifer
Published: May 2009

Over the past few decades, interest in the effects of greenhouse gas (GHG) emissions on global climate change has peaked. Increasing temperatures worldwide have been blamed for numerous negative impacts on agriculture, weather, forestry, marine ecosystems, and human health. The U.S. Environmental Protection Agency reports that the primary GHG emitted in the U.S. is carbon dioxide (CO2), most of which stems from fossil fuel combustion [1]. In fact, CO2 represents approximately 85% of all GHG emissions nationwide. The other primary GHGs include nitrous oxide (N2O), methane (CH4), ozone (O3), and fluorinated gases. Since the energy sector is responsible for a majority of the GHGs released into the atmosphere, policies that address their mitigation through the production of electricity using renewable fuels and distributed generation are of significant interest. Use of renewable fuels and clean technologies to meet energy demand instead of relying on traditional electrical grid systems is expected to result in fewer CO2 and CH4 emissions, hence reducing global climate change impacts. Technologies considered cleaner include photovoltaics, wind turbines, and combined heat and power (CHP) devices using microturbines or internal combustion engines. The Self-Generation Incentive Program (SGIP) in California [2] provides incentives for the installation of these technologies under certain circumstances. This paper assesses the GHG emission impacts from California’s SGIP during the 2005 program year by estimating the reductions in CO2 and CH4 released when SGIP projects are in operation. Our analysis focuses on these emissions since these are the two GHGs characteristic of SGIP projects. Results of this analysis show that emissions of GHGs are reduced due to the SGIP. This is because projects operating under this program reduce reliance on electricity generated by conventional power plants and encourage the use of renewable fuels, such as captured waste heat and methane.
Best Practices for Cogeneration System Design
Authors: Souza Brad , Ishii Ron , Simons George , Landry Pierre
Published: May 2009

Successful cogeneration system design requires a combination of engineering, investigation, and forecasting skills. Operating schedules for the facility must be considered in the design of the cogeneration system to optimize overall plant utilization and economics. This results in tradeoffs between electrical power production and thermal heat recovery for many applications of the technology. Optimizing these two parameters requires a thorough understanding of how and when the facility uses power and heat and the owner’s objectives of the investment in the cogeneration system. Customer-sited cogeneration systems have been accepted as one option to mitigate electrical supply shortages. On the utility side, this requires that cogeneration systems operate at a relatively high capacity factor, especially during peak periods. On the customer side, the cogeneration system must be capable of meeting onsite energy needs to reduce energy costs. In California, the Self-Generation Incentive Program (SGIP) provides incentives for the installation of distributed generation systems. Incentives are paid on an installed capacity basis ($/kW) that varies by installed technology. Eligible technologies include photovoltaic, wind, fuel cells, internal combustion engines, and microturbines. Alternative Energy Systems Consulting, Inc. (AESC) provides technical support services to the SGIP, the sponsoring utilities and SGIP’s Working Group. The services that AESC provides varies with utility, but primarily includes program design support, regulatory review, technology evaluation, application review, generator performance metering, participant training and equipment field verification. Itron evaluates the SGIP to quantify performance of the systems and estimate overall impacts of the program. This paper will present best practice recommendations for cogeneration system design to meet the efficiency criteria of the SGIP. Recommendations are based on findings from numerous AESC performance reviews and on-site inspections, as well as results of Itron’s in-depth performance evaluation of the effectiveness of useful thermal energy recovery of on-site cogeneration systems receiving incentives from the SGIP. Information is presented through Program Year 2005. Results of several past studies have suggested that cogeneration systems were not operating as they were designed and, more importantly, were not achieving the efficiencies claimed at the design stage. This paper will also explore some of the key drivers behind the unexpectedly low thermal energy recovery and overall plant performance sampled from the fleet of SGIP cogenerators. Results from recent Itron studies will be combined with AESC’s expertise in actual operations to develop a list of best practices to be followed when designing and commissioning a cogeneration system.
Air Quality and Climate Change: Hard Choices
Authors: Ochsner Heidi , MacDougall Ruth , Bowen La Ronda , Dusault Allen , Simons George
Published: May 2009

This paper presents the results of a study conducted by Itron, Sustainable Conservation and Bowen & Associates for the Sacramento Municipal Utility District (SMUD) to investigate the status and costs of controls for reducing emissions of oxides of nitrogen (NOx) from small (100 to 300 kW) reciprocating engines operating on biogas from dairy digesters. During the course of the study, it became apparent that simultaneous environmental policies have created a fundamental “catch 22” situation for California’s biogas industry. On one hand, California air quality regulations require distributed generation (DG) technologies to achieve aggressive emission limits for control of oxides of nitrogen (NOx). At the same time, California’s Governor and Legislature have passed landmark legislation calling for GHG emissions to be reduced by twenty-five percent to 1990 levels by no later than 2020. A “catch 22” occurs because while DG technologies, particularly biogas fueled technologies, can play a key role in reducing GHG emissions, NOx control technologies needed to meet the required NOx levels have not matured to commercial readiness. This requires project developers to take substantial risks on both the financial and technical front without the likelihood of recouping their investments. The result creates an impasse that potentially deprives California not only of forward progress in reducing GHG emissions but forestalls significant interim NOx reductions that could otherwise be achieved. However, the situation highlights a problem that extends beyond California’s borders and the biogas industry: how to simultaneously achieve aggressive air quality targets while making significant reductions in greenhouse gas (GHG) emissions. This paper presents the findings of an investigation into proposed NOx emissions limits for biogas to energy applications and how those requirements interact with policies to reduce GHG emissions.
Benefits of Reliability Assessment in Operating Power Plants
Authors: Raza Mohammad , Steele Robert F.
Published: May 2009

The global energy market continues to face significant change, evolving over time in several dimensions. One of them is a structural change, where it went into de-regulation and that has become a viable opportunity and reality; another is clean technology as new generating alternatives with greater efficiency and “environmental friendliness” has become available. Today, there is a keen interest in power plants using the latest gas turbine technology, which has higher firing temperatures, greater output, and improved efficiencies and remains environmental friendly. With evolving markets and variations in prices, the importance of reliability has increased greatly. As these technologies evolve and improve, it is important to recognize that the operational performance and profitability is expected to be consistently on the rise. Consequently, market conditions and expectations continue to place a significant emphasis on the achievable level of reliability and availability, which in turn provides the importance on having feedback from the plants within the framework of quality data resulting in building up benchmarking statistics. ORAP® (Operational Reliability Analysis Program) which is owned by Strategic Power System Inc.® (SPS) tracks reliability and availability performance on gas turbines from various MW size ranges, manufacturers, applications, and duty cycles. NERC is another data source with several years of data from varied fuels and power plant types. This paper presents the importance of having benchmarking data from an independent third party and the results of quality analysis by OEM experts. This focused approach develops the methodology of setting targets for MTBF, MTTR, FOR and failure rate not only at system level but also even down to component level for any operating power plant. The reliability growth potential is identified and reliability techniques are applied.
Challenges Facing Performance Evaluations of IGCC Power Plants
Authors: Zachary Justin , Khochafian Alex
Published: May 2009

Based on the present revival of coal as the fossil fuel of choice for power generation, there is a high probability that several IGCC projects will materialize in the near future. One of the challenges facing the Owners, EPC Contractors and OEM’s will be to define the performance commercial guarantees and the practical means to determine them. In addition following the current huge upturn in conventional supercritical coal fired power plants, a large number of facilities will conduct thermal performance tests. The proper conductance of the test, data collection and correction to reference conditions, have many technical implications and could affect drastically the commercial outcome of a project both for the Contractor and the Owner. For IGCC plants, in anticipation of this probability, ASME Performance Test Committee had developed a Performance Test Code for such type of plant — PTC 47, which was published in January 2007. In the first part, the paper will provide details about the specific challenges facing the implementation of the Code, in particular the proposed use of the input/output method (mass and energy balance). The presentation will cover other highlights of the code recommendations. The methodology is fully applicable to conventional power plants, since they use same type of fuel. The determination of the heat input based on actual continuous measurement of the mass flow and composition of the coal will be discussed in details. The practicality and the measurement uncertainty associated with fuel composition will also be analyzed. A comparison with the indirect method for determination of the heat input will also be presented. The article will evaluate how the code requirements are reflected in the definition of the power plant design, configuration and instrumentation. The implications of test tolerance as a commercial issue and measurement uncertainty as a technical issue will also be presented and evaluated Other unique aspects of the entire IGCC plant performance testing will be discussed: (1) stability criteria related to the gasification and integration processes, (2) corrections from test to guarantees conditions due to complex chemical, mechanical processes. Finally, the article will indicate the progress on the development of performance evaluation methodologies for other main IGCC components: gasifier, air separation unit, gas cleaning systems and Power Island.
Performance Testing of Coal Fired Power Plants
Authors: Powers Shane E. , Wood William C.
Published: May 2009

With the renewed interest in the construction of coal-fired power plants in the United States, there has also been an increased interest in the methodology used to calculate/determine the overall performance of a coal fired power plant. This methodology is detailed in the ASME PTC 46 (1996) Code, which provides an excellent framework for determining the power output and heat rate of coal fired power plants. Unfortunately, the power industry has been slow to adopt this methodology, in part because of the lack of some details in the Code regarding the planning needed to design a performance test program for the determination of coal fired power plant performance. This paper will expand on the ASME PTC 46 (1996) Code by discussing key concepts that need to be addressed when planning an overall plant performance test of a coal fired power plant. The most difficult aspect of calculating coal fired power plant performance is integrating the calculation of boiler performance with the calculation of turbine cycle performance and other balance of plant aspects. If proper planning of the performance test is not performed, the integration of boiler and turbine data will result in a test result that does not accurately reflect the true performance of the overall plant. This planning must start very early in the development of the test program, and be implemented in all stages of the test program design. This paper will address the necessary planning of the test program, including: • Determination of Actual Plant Performance. • Selection of a Test Goal. • Development of the Basic Correction Algorithm. • Designing a Plant Model. • Development of Correction Curves. • Operation of the Power Plant during the Test. All nomenclature in this paper utilizes the ASME PTC 46 definitions for the calculation and correction of plant performance.
Nuclear Plant Feedwater Heater Life Cycle Optimization Through Comprehensive Condition Assessment Program
Authors: Thomas Daniel S. , Coakley Michael T. , Catapano Michael C. , Svensson Eric B.
Published: May 2009

Many papers published over the last 25 years have strongly emphasized the need for an ongoing program of condition assessment through inspection and testing with subsequent failure cause analysis of feedwater heaters. Plants must be run more competitively; therefore, Utilities must try to decrease operation and maintenance costs, while optimizing overall plant efficiency. One recognized area that needs to be addressed in accomplishing this goal is the heat cycle. This paper specifically deals with the feedwater heating system. Utility engineers must monitor feedwater heater performance in order to recognize degradation, identify and mitigate failure mechanisms, and prevent in-service failures while optimizing availability. Periodic tube plugging without complete analysis of the degraded/failed areas resolves the immediate need for return to service; however, heater life will not be optimized. This paper is a direct follow-up to a previously published ASME paper that detailed the establishment of a comprehensive life cycle management program for feedwater heaters implemented at Peach Bottom Atomic Power Station (PBAPS). This particular paper reports the eventual results and benefits achieved through the continuance and perseverance of this program. This successful condition assessment case history included the following inspection, testing, and maintenance activities to ascertain reliable data in support of root cause analysis: • Removal of previously installed plugs. • Videoprobe inspection of failed areas. • Videoprobe inspections of the steam space. • Extraction of tube samples for further analysis. • Eddy current testing of selected tubes. • Evaluation of the condition of “insurance” plugged tubes for return to service. • Hydrostatic testing of selected tubes. • Repair plans based on the results of the above program. • Reviewing operating data to assess case history. • Monitor and continue the program over future planned unit outages. This paper concludes that no single method of inspection or testing should solely be relied upon in assessing actual conditions. It is a combination of evaluating all gathered data that affords the best chance in arresting problems and optimizing feedwater heater life. Problem heaters should be continuously monitored over time until the facts ultimately help to justify replacement.
Overcoming Plant Cooling Issues Using Compact Heat Exchangers
Authors: Trom Lawrence W.
Published: May 2009

In the power generation industry today, a variety of factors can lead to the insufficiency of existing heat exchangers. These factors include loss of surface area from purposely plugged tubes, power uprates, warmer raw water temperatures and increased spent fuel loads. While plants were generally designed for a life of 40 years, many plants are near or exceed that. It is common that the heat exchangers can be at or near the end of their physical life.