bluuebunny/crossref_metadata_2025 huggingface dataset:
Consumers' Preferences for GM Food and Voluntary Information Access: A Simultaneous Choice Analysis
Authors: Hu Wuyang , Adamowicz Wiktor L. , Veeman Michele M.
Published: May 2009

Previous studies on information and consumer choices have typically assumed that information is exogenous in that information made available to consumers is generally treated as being both received and processed. Based on a choice experiment on consumers' stated preferences for genetically modified food that provides for voluntary information access, this study allows information access decisions to be endogenous to the product choice decision‐making process. Instead of assuming correlated error terms between these decisions, the approach used in this analysis builds upon structural correlations between two models that individually consider each of these two decisions. We find that the two types of decisions are related and that there is heterogeneity across individuals in the nature of this relationship.

Des études antérieures sur l'information et les choix des consommateurs ont typiquement supposé que l'information est exogène, en ce sens que l'information mise à la disposition des consommateurs est généralement considérée comme étant à la fois reçue et traitée. Selon une méthode de choix expérimentaux sur les préférences déclarées des consommateurs quant aux aliments génétiquement modifiés offrant l'accès volontaire à l'information, la présente étude permet aux décisions d'accès à l'information d'être endogènes au processus de décision lié au choix du produit. Au lieu de supposer des termes d'erreur corrélés entre ces décisions, la méthode utilisée dans la présente analyse mise sur la corrélation structurale entre les deux modèles qui examinent individuellement ces deux décisions. Nous trouvons que les deux types de décisions sont liés et qu'il existe une hétérogénéité entre les individus quant à la nature de ce lien.
Isolation and characterization of 13 microsatellite loci for Neochamaelea pulverulenta (Cneoraceae)
Authors: RIGUEIRO CRISTINA , ARROYO JUAN M. , VALIDO ALFREDO , JORDANO PEDRO
Published: May 2009

We report 13 polymorphic nuclear microsatellite loci for Neochamaelea pulverulenta (Cneoraceae) using an enriched‐library approach. Although this plant species is tetraploid, expected patterns for tetrasomic segregation were completely absent, and all loci analysed showed a diploid pattern of inheritance. We detected a total of 102 alleles in 57 individuals genotyped (mean number of alleles per locus was 7.85). The values of observed and expected heterozygosities ranged from 0.193 to 0.737 and 0.425 to 0.812 respectively. Disomic segregation, levels of polymorphism and the exclusionary power of the developed markers render them readily applicable for parentage assignment of dispersed seeds, and for analyses of spatial genetic structure and population connectivity.
The ownership of ratings
Authors: Faure‐Grimaud Antoine , Peyrache Eloïc , Quesada Lucía
Published: May 2009

We identify the optimal contract between a rating agency and a firm and the circumstances under which simple ownership contracts implement this optimal solution. We assume that the decision to obtain a rating is endogenous and the price of a rating is a strategic variable. Clients hiding their ratings can be an equilibrium only if they are ex ante uncertain of their quality and if the hiring decision is not observable. For some distribution functions, a competitive rating market is necessary for this result to obtain. In this context, competition between rating intermediaries will lead to less information in equilibrium.
Bargaining with imperfect enforcement
Authors: White Lucy , Williams Mark
Published: May 2009

The game‐theoretic bargaining literature insists on a noncooperative bargaining procedure but implicitly assumes “cooperative” implementation of agreements. In reality, courts cannot implement agreements costlessly, and parties often prefer to use “noncooperative” implementation. We present a bargaining model which incorporates the idea that agreements may be enforced noncooperatively. We show that this has a substantial impact in limiting the inequality of agreements, and results in a nonmonotonicity of the discount rate. The model also explains why some parties may have incentives to deliberately write incomplete contracts as a way to enhance their bargaining power.
Firm reputation and horizontal integration
Authors: Cai Hongbin , Obara Ichiro
Published: May 2009

We study effects of horizontal integration on firm reputation in an environment where customers observe only imperfect signals about firms' effort/quality choices. Horizontal integration leads to a larger market base for the merged firm, and thus helps reputation building with more effective punishments and better monitoring by eliminating idiosyncratic shocks of individual markets. But it allows the merged firm to deviate only in a subset of markets, which hinders reputation building by making it more difficult for consumers to monitor its quality. We show that these effects give rise to a reputation‐based theory of the optimal firm size and derive its comparative statics.
Task assignments and incentives: generalists versus specialists
Authors: Prasad Suraj
Published: May 2009

I develop an agency model of job assignments where jobs differ based on the breadth of tasks. A tradeoff between task complementarities and relative abilities of workers results in those with balanced skills being assigned to multitask jobs. The same tradeoff between complementarities and relative abilities also influences incentives to sort privately informed workers to jobs. I then draw on a variety of sources (survey data, case studies, and anecdotal evidence) to suggest that relative abilities and multitasking play an important role in managerial assignments of nonacademic research scientists.
Reliability-Based Design and Assessment Standards for Onshore Natural Gas Transmission Pipelines
Authors: Zhou Joe , Rothwell Brian , Nessim Maher , Zhou Wenxing
Published: May 2009

Onshore pipelines have traditionally been designed with a deterministic stress-based methodology. The changing operating environment has, however, imposed many challenges to the pipeline industry, including heightened public awareness of risk, more challenging natural hazards, and increased economic competitiveness. To meet the societal expectation of pipeline safety and enhance the competitiveness of the pipeline industry, significant efforts have been spent for the development of reliability-based design and assessment (RBDA) methodology. This paper will briefly review the technology development in the RBDA area and the focus will be on the progresses in the past years in standard development within the American Society of Mechanical Engineers (ASME) and the Canadian Standard Association (CSA) organizations.
Four-Point Fatigue Testing of Pressurized Composite Pipe
Authors: Gerrard D. P. , Scavuzzo R. J. , Srivatsan T. S. , Miner T. S. , Olabisi Olagoke
Published: May 2009

This technical paper presents a comparative study of the fatigue strength of high-pressure composite pipes and high-pressure composite pipes containing joints. The test specimens used in this experimental investigation were exposed to cyclic bending stresses and to cyclic bending stresses in combination with constant or cyclic internal pressures generated by water, brine, and crude oil. The extrinsic influence of elevated temperature on fatigue performance was also examined. A new four-point bending fatigue machine was developed at the University of Akron to accomplish the testing. For each test specimen, two types of failure were distinctly observed. After a number of repeated cycles, the fluid under internal pressure began to gradually leak through the fine microscopic cracks in the matrix. The fine microscopic cracks were oriented in the circumferential direction of the pipe. However, despite the occurrence of “weeping failure” of the pipe, internal pressure could be easily maintained. After about 10–100 times the number of cycles required for “weeping,” the fiber reinforcements of the pipe gradually fractured and the internal pressure could no longer be maintained. The loss of pressure is referred to as “pipe failure.” In these tests, the primary parameter controlling failure was orientation of the fiber reinforcements in the body of the pipe. Those fibers aligned along the pipe axis revealed a substantial improvement in cyclic fatigue resistance. The existence of a joint in the test specimen showed secondary importance while contributing to degradation of the fatigue resistance of the specimen. Both types of failure were found to be dependent on temperature, over the range tested (22–66°C, and also dependent on the type of internal liquid used. The specimens tested using crude oil at 66°C as the internal fluid revealed the lowest fatigue resistance.
Two-Phase Flow-Induced Vibration of Parallel Triangular Tube Arrays With Asymmetric Support Stiffness
Authors: Feenstra Paul , Weaver David S. , Nakamura Tomomichi
Published: May 2009

Laboratory experiments were conducted to determine the flow-induced vibration response and fluidelastic instability threshold of model heat exchanger tube bundles subjected to a cross-flow of refrigerant 11. Tube bundles were specially built with tubes cantilever-mounted on rectangular brass support bars so that the stiffness in the streamwise direction was about double that in the transverse direction. This was designed to simulate the tube dynamics in the U-bend region of a recirculating-type nuclear steam generator. Three model tube bundles were studied, one with a pitch ratio of 1.49 and two with a smaller pitch ratio of 1.33. The primary intent of the research was to improve our understanding of the flow-induced vibrations of heat exchanger tube arrays subjected to two-phase cross-flow. Of particular concern was to compare the effect of the asymmetric stiffness on the fluidelastic stability threshold with that of axisymmetric stiffness arrays tested most prominently in literature. The experimental results are analyzed and compared with existing data from literature using various definitions of two-phase fluid parameters. The fluidelastic stability thresholds of the present study agree well with results from previous studies for single-phase flow. In two-phase flow, the comparison of the stability data depends on the definition of two-phase flow velocity.
The Fabulous Nuclear Odyssey of Belgium
Authors: Geraets Luc H.
Published: May 2009

This paper reviews the Belgian history of nuclear technology and its use for power generation, from the beginning in 1942 until now. It identifies the main players in the field, and the major milestones of this history, both from the power generation side and the nuclear fuel side. It demonstrates the genuine contribution of Belgium to this technology (typical examples are shown), and the significant role of its engineers and scientists.1
Estimation of Point Vibration Loads From Field Measurements for Industrial Piping
Authors: Saha S.
Published: May 2009

Estimation of point loads on a span for a vibrating pipe has been done with the help of boundary measurement of slope data. The approach is based on the theory of inverse force identification for hyperbolic systems. Depending on the form of the forcing function, which also satisfies some continuity conditions, an exact determination is possible. Though restrictive in its formulation some applications are still possible. A typical case for harmonic excitation of a pulsating reciprocating compressor has been shown as an illustration.
Study on Dynamic Strength Evaluation Method of Mechanical Members Based on Energy Balance
Authors: Minagawa Keisuke , Fujita Satoshi , Kitamura Seiji , Okamura Shigeki
Published: May 2009

In Japan, mechanical structures installed in nuclear power plants, such as piping and equipment, are usually designed statically in an elastic region. Although these mechanical structures have sufficient seismic safety margin, understanding the ultimate fatigue endurance is very important in order to improve the seismic safety reliability for unexpected severe earthquakes. Moreover, clarifying a margin of seismic resistance of mechanical structures that suffered a severe earthquake is being required. In this study, the energy balance equation that is one of valid methods for structural calculation is applied to the above-mentioned issues. The main feature of the energy balance equation is that it explains accumulated information of motion. Therefore the energy balance is adequate for the investigation of the influence of cumulative load such as seismic response. The investigation is implemented by forced vibration experiments. The experiment models are simple single–degree-of-freedom models that are made of stainless steel and carbon steel. In the experiment, random waves having predominant frequency similar to natural frequency of the experimental model are input in order to obtain adequate response not only in the elastic region but also in the plastic region. As a result, experimental models vibrate under resonance condition, so response acceleration is approximately seven times as big as the input. The excitation is continued until the experimental models fracture, and is carried out with various input levels. In the experiment, models suffered cracks at the bottom end, and fractured finally. As a result, input energy for failure increases as time for failure. In other words, more input energy for failure is needed in case of small input. Moreover the correlation between increment in input energy and input energy for failure is investigated. It was confirmed that input energy for failure is inversely proportional to increment in input energy per unit time. Additionally energy for failure of stainless steel is about twice as big as carbon steel. The correlation between fatigue failure and energy is confirmed from the vibration experiment. Therefore it is expected that time for fatigue failure can be evaluated by the energy balance equation.
Structural Response Optimization of a Light-Weight Composite Blast Containment Vessel
Authors: Thota Jagadeep , Trabia Mohamed B. , O’Toole Brendan J. , Ayyaswamy Ashok K.
Published: May 2009

This paper proposes an optimization technique for increasing the structural integrity of a light-weight composite blast containment vessel. The vessel is cylindrical with two hemispherical ends. It has a steel liner that is internally reinforced with throttles and gusset plates and wrapped with a basalt-plastic composite. A computationally-efficient finite element model of the blast containment vessel was proposed and verified in an earlier work. The parameters of the vessel are incorporated within an iterative optimization procedure to decrease the peak strains within the vessel, which are caused by internal blast loading due to an explosive charge placed at the center of the vessel. The results of the proposed procedure are validated for different initial guesses of the design variables.
Experimental and FEA Investigations on the Fracture Properties of Pipe Structures Under Internal Pressure in DBTT Region
Authors: Wang Zhao-Xi , Xue Fei , Shi Hui-Ji , Lu Jian
Published: May 2009

The fracture behavior of pipes with penetrating cracks was experimentally investigated with the results of the load-deflection curves and crack length. J-R curves were obtained from the testing results for different temperatures. With the decrement in temperature, the critical J integral decreases and the tearing modulus increases. An updated continuum damage model was proposed, in which the fracture energy density as a function of the stress triaxiality, temperature and strain rate in the transition region was taken as the critical damage factor. The uni-axial tension experiments at different temperatures were carried out to obtain the basic material properties and the critical fracture energy density, to verify the validity of the damage model. Based on detailed finite element analyses with the proposed updated continuum damage model, the loading level of pipes with penetrating cracks was estimated and compared with the experimental results, meanwhile the fracture processes of the pipeline structure in the ductile-brittle-transition-temperature region were reproduced. It has been shown that the fracture process in the transition region strongly depends on both the stress and strain state, and can be effectively predicted using the continuum damage models incorporating with the stress state effect.
Assessment and Test of the Creep-Fatigue Crack Behavior for a High Temperature Component
Authors: Lee Hyeong-Yeon , Lee Jae-Han , Nikbin Kamran
Published: May 2009

Creep-fatigue crack behavior has been investigated for a welded component with 316L stainless steel and Mod. 9Cr–1Mo steel through assessment and test. The evaluation of creep-fatigue crack initiation and propagation was carried out for 316L stainless steel according to the French RCC-MR A16 guide, and the evaluation of creep-fatigue crack initiation for a Mod.9Cr–1Mo steel specimen was carried out with an extended A16 method. A test for a structural specimen with a diameter of 500 mm, height of 440 mm, and thickness of 6.3 mm was performed to compare its results with that by an assessment according to the A16 guide. The specimen was subjected to creep-fatigue loads with 2 h of dwell time at 600°C and various primary loads. The creep-fatigue crack behaviors for the two materials were assessed, observed, and compared. The results showed that the A16 guide for the austenitic stainless steel was fairly conservative for the assessment of creep-fatigue crack initiation while it was reasonably conservative for creep-fatigue crack growth for the present specimen.
Circulation in Blowdown Flows
Authors: Katz Jonathan I.
Published: May 2009

The blowdown (rapid release) of high pressure gas from a pressure vessel adiabatically cools the gas remaining in the vessel. The gas near the wall is warmed by conduction from the wall, producing radial temperature and density gradients that affect the flow, the mass efflux rate, and the thermodynamic states of both the outflowing and the contained gas. The resulting buoyancy-driven flow circulates the gas through the vessel and reduces, but does not eliminate, these gradients. The purpose of this technical brief is to estimate when blowdown cooling is rapid enough that the gas in the pressure vessel is neither isothermal nor isopycnic, though it remains isobaric. I define a dimensionless number, the buoyancy circulation number, that parametrizes these effects.1
Performance of a Drum Type Packaging With Urethane Foam Overpack Subjected to Crush and Other Regulatory Tests
Authors: Smith Allen C. , Blanton Paul S. , Gelder Lawrence F. , Lutz Rex N.
Published: May 2009

General purpose fissile package prototypes of two configurations, 16 in. and 18.5 in. diameter drum overpacks, were subjected to the free-drop, crush, puncture, and thermal hypothetical accident condition sequential tests for 10 CFR 71, Type B packagings. The tests demonstrated that the prototypes are very robust, easily withstanding the structural tests. The tests also confirmed that the urethane foam-filled overpack was able to withstand the thermal test.
Evaluation of Two-Parameter Approaches to Describe Crack-Tip Fields in Engineering Structures
Authors: Kamel Simon , O’Dowd Noel P. , Nikbin Kamran M.
Published: May 2009

The application of two-parameter approaches to describe crack-tip stress fields has generally focused on Ramberg–Osgood (RO) power law material behavior, which limits the range of applicability of such approaches. In this work we consider the applicability of a J-Q or J-A2 approach (the latter is designated here as the J-A approach) to describe the stress fields for RO power law materials and for a material whose tensile behavior is not described by a RO model. The predictions of the two-parameter approaches are compared with full field finite-element predictions. Results are presented for shallow and deep-cracked tension and bend geometries, as these are expected to provide the expected range of constraint conditions in practice. A new approach for evaluating Q is proposed for a RO material, which, for a given geometry, makes Q dependent only on the strain hardening exponent.
Experimental Evaluation of the Bending Load Effect on the Failure Pressure of Wall-Thinned Elbows
Authors: Kim Jin-Weon , Na Yeon-Soo , Lee Sung-Ho
Published: May 2009

During normal operating conditions, piping systems in nuclear power plants are subject to internal pressure and bending loads induced by deadweight, thermal expansion, and internal pressure. Thus, understanding the effect of bending load on the failure of wall-thinned elbows is important to understand failure behavior and to evaluate the failure pressure reliably. This study includes a series of burst tests using full-scale 4-in. schedule 80 elbow specimens with local wall-thinning under combined internal pressure and in-plane bending load. The results are compared with those tested under simple internal pressure only. In the tests, various circumferential thinning angles (θ/π=0.125, 0.25, 0.5, 1.0) and thinning locations (intrados, extrados, and full-circumference) were considered. Each specimen was initially subjected to a displacement controlled in-plane bending load, closing mode for extrados wall-thinned elbows, and opening mode for intrados wall-thinned elbows, and then internal pressure was applied up to the point of final failure. The results showed that the effect of in-plane bending on the failure pressure and failure mode was minor under all wall-thinning conditions. In addition, the dependence of failure pressure on the circumferential thinning angle and thinning locations was identical to that observed under simple internal pressure.
Troubleshooting Condenser Vacuum Issues at North Omaha Station Unit 1
Authors: Sunder Raj Komandur S.
Published: May 2009

In 2004, North Omaha Station Unit 1 (NOS 1) experienced multiple condenser vacuum upsets. At least one of them resulted in a unit trip. The upset conditions occurred over relatively short periods of time with no clear indication of the initiating mechanism. Overall, condenser vacuum was low. Various methods were employed to combat the vacuum issues and upset conditions. These included operating both sets of holding steam jet air ejectors (SJAEs) above 600 psig (50% above design), using the hogging SJAE during unit operation and, operating the condensate pumps in a recirculating mode. Air inleakage was a known problem on NOS 1. The air inleakage was no longer measurable since it exceeded the scale of the installed instrumentation (20 scfm). Besides air inleakage, tube fouling of the condenser tubes was also contributing to degraded condenser vacuum. NOS 1 had a history of fouling due to calcium carbonate plateout on the condenser tubes. During the January 2005 outage, major sources of air inleakage were identified and fixed. Leaking tubes in the SJAE intercondenser/aftercondenser were plugged. The condenser tubes were scraped to reduce fouling. Although condenser vacuum improved, problems persisted at low loads. Following a vacuum upset in June 2005, the hogging SJAE was placed into service. Helium testing in July 2005 indicated high air inleakage. The problems continued to persist and, in February 2006, the unit tripped on low condenser vacuum. At that time, the unit had been operating at about 58 Mwe. In order to maintain the unit on line at a reduced load of 40 Mwe, both the hogging SJAE and one set of first stage and second stage holding SJAEs had to be deployed. An attempt to remove the hogging SJAE from service was unsuccessful since it resulted in rapid decrease in air-removal capability of the holding SJAEs. This paper describes the methodology used to troubleshoot the condenser vacuum issues for NOS 1 and remedies proposed for proper performance and reliable operation.
Performance Optimization of Advanced Power Plants Based on Fossil Fuel Decarbonization Technologies
Authors: Gambini Marco , Vellini Michela
Published: May 2009

In this paper two options for H2 production, by means of fossil fuels, are presented and their performances are evaluated when they are integrated with advanced H2/air cycles. In this investigation two different schemes have been analyzed: an advanced combined cycle power plant (CC) and a new advanced mixed cycle power plant (AMC). The two methods for producing H2 are as follows: • partial oxidation of methane; • gasification of coal. These hydrogen production plants require material and energetic integrations with the power section and the best interconnections must be investigated in order to obtain good overall performance. With reference to thermodynamic and economic performance, significant comparisons have been made between the above mentioned reference plants. An efficiency decrease and an increase in the cost of electricity have been obtained when power plants are equipped with a fossil fuel decarbonization section. The main results of the performed investigation are quite variable among the different H2 production technologies here considered: the efficiency decreases in a range of 5.5 percentage points to nearly 10 for the partial oxidation of the natural gas and in a range of 6.2–6.4 percentage points for the coal gasification. The electricity production cost increases in a range of about 33–37% for the first option and in a range of about 24–32% for the second one. The clean use of coal seems to have very good potentiality because, in comparison with natural gas decarbonisation, it allows lower energy penalizations (about 6 percentage points) and lower economic increases (about 24% for the CC).
Diagnosis of the Operation of Power Plants
Authors: Gonza´lez-Santalo´ Jose´ Miguel , Gonza´lez-Di´az Abigail , Marin˜o-Lo´pez Carlos Alberto
Published: May 2009

A system was developed to diagnose the operation of combined cycle power plants and to determine, when deviations are found, which components are causing the deviations and the impact of each component deviation. The system works by comparing the values of the actual operating variables with some reference values that are calculated by a model that was adjusted to the design heat balances. The model can use the actual values of the environmental parameters as well as the design values, so the effect of environmental changes can be quantified and separated. The determination of the individual equipment impacts is done by adjusting the equipment parameters in order to reproduce the values of the measured variables. The adjustment is done by varying the values of the characteristic parameters of the equipment in order to minimize the sum of the squares of the differences between the values of the measured variables and the calculated values from the model.
Resurrecting a Major Coke Calcining Energy Recovery Plant
Authors: John Tommy , Deyoe Ray , Gray John , Gross Paul
Published: May 2009

Refurbishment of the Port Arthur Steam Energy facility began in early 2005 after key commercial agreements were concluded. The plant, which had been idle since October 2000, was originally constructed in 1983 and 1984 to recover energy from three petroleum coke calcining kilns at the Great Lakes Carbon LLC facility. Major repairs were needed because of extensive damage from sulfuric acid corrosion of the HRSG system and deterioration of water treatment facilities. In addition, major improvements were made including an acoustic cleaning system, multiclones for particulate emission reduction, magnesium oxide injection for corrosion control, a complete new control system with all new field instrumentation, stack improvements to increase dispersion, and improvements to the HRSG system and water treatment system to improve reliability and reduce maintenance. Rising energy prices dictated a fast-paced schedule. Following a major reconstruction effort with a peak force of 435 people, the facility was in full operation by August 2005, less than nine months from commencement. The facility is producing approximately 450,000 lb/hr of high pressure steam, the majority of which is sold to the neighboring Valero Port Arthur refinery, and producing 4 to 5 MW of power. By capturing 1800–2000°F heat that would other wise be wasted, the project recovers nearly 5 trillion Bru/year, off setting over 200 tons/yr of NOx and over 280,000 tons/yr of carbon dioxide that would otherwise be emitted by natural gas combustion. The success of the project can be attributed to management of the project which included innovative inspection techniques, development of the scope of work, design of improvements, and extensive construction and repairs.
Model to Estimate Mass Emissions of Atmospheric Pollutants in Thermal Power Plants
Authors: Huertas Jose´ I. , Carmona Mauricio Y. , Moreno Diego
Published: May 2009

Currently there is a need for a model to estimate mass emissions of atmospheric pollutants at the exit of the stacks of thermal power plants that operate under a variable regime of electric power generation based on the variables that typically are monitored during the operation of the plants. The recommended alternative to calculate the mass emissions of pollutants is based on the experimental measurements of pollutant concentration, velocity and temperature at the exit of the stack. This alternative is expensive and cumbersome to implement. Alternatively the US EPA emission factors can be used. However, the emission factors require modifications to account for the type of fuel, the technology used to control emissions, maintenance of the equipment, and the local environmental conditions. As a solution, this paper presents a model to estimate emissions of atmospheric pollutants in thermal power plants based on the variables that are continuously monitored during the operation of most of the thermal power plants in Mexico such as fuel chemical composition, fuel consumption, air to fuel ratio of the combustion process, and mean boiler temperature. The proposed model was calibrated by continuously measuring all the variables included in the three models during one week of operation of a 2.2 GW thermal power plant located in the continental area of the Gulf of Mexico. This plant has six units of generation that operate with fuel oil and one with natural gas. Results obtained from the three methodologies described before were compared. It was concluded that the NOx, SOx and CO results of the proposed model follow closely the results obtained using the measurements of concentration, velocity and temperature at the exit of the stack method. It was also found that the results of the emission factors methodology require to be adjusted to include the particular operating conditions of each unit of electricity generation.
Leading Edge Conveyor Technologies to Improve Coal Handling
Authors: Bierie Greg
Published: May 2009

This paper looks at a two new conveyor technologies that offer the opportunities for significant improvement in the handling of coal in power plants, and in bulk transportation facilities, and other coal-handling operations. This first technology is “flow-engineered” chutes. Based on material testing and flow studies, these chutes allow the development of transfer chute systems that provide better control, continuous coal flow at higher capacities, and dramatic reductions in material spillage and the release of airborne dust. By regulating the coal flow path of movement, these engineered chutes improve the load placement on the belt, eliminate chute blockages, reduce safety hazards, and minimize maintenance costs. The second leading edge system is air-supported conveyors. Air supported conveyors are now seeing increasing acceptance in coal handling applications in power plants. This is due to the advantages they offer to coal-handling, including high efficiency and low maintenance. This technology also provides a reduction in the release of coal dust, as the carrying side of the conveyor is completely enclosed. This paper will discuss recent installations of these systems in coal handling facilities. In particular, it will feature the engineering and installation of flow-engineered chute systems at AmerenUE’s Meramec and Rush Island Electric Generating Stations, to improve conveyor system performance, while reducing dust as much as 98%. He will also discuss recent application of air-supported conveyor systems in coal handling systems, and discuss the benefits of the application of conveyors combining both “leading edge” systems.
The Effect of Non-Uniform Aerodynamic Loading on the Blade Responses
Authors: Mahmoud Abdelgadir M. , Leong Mohd S.
Published: May 2009

Turbine blades are always subjected to severe aerodynamic loading. The aerodynamic loading is uniform and Of harmonic nature. The harmonic nature depends on the rotor speed and number of nozzles (vanes counts). This harmonic loading is the main sources responsible for blade excitation. In some circumstances, the aerodynamic loading is not uniform and varies circumferentially. This paper discussed the effect of the non-uniform aerodynamic loading on the blade vibrational responses. The work involved the experimental study of forced response amplitude of model blades due to inlet flow distortion in the presence of airflow. This controlled inlet flow distortion therefore represents a nearly realistic environment involving rotating blades in the presence of airflow. A test rig was fabricated consisting of a rotating bladed disk assembly, an inlet flow section (where flow could be controlled or distorted in an incremental manner), flow conditioning module and an aerodynamic flow generator (air suction module with an intake fan) for investigations under laboratory conditions. Tests were undertaken for a combination of different air-flow velocities and blade rotational speeds. The experimental results showed that when the blades were subjected to unsteady aerodynamic loading, the responses of the blades increased and new frequencies were excited. The magnitude of the responses and the responses that corresponding to these new excited frequencies increased with the increase in the airflow velocity. Moreover, as the flow velocity increased the number of the newly excited frequency increased.
Experimental Evaluation and Comparison of the Performance and Emissions of a Regenerative Gas Microturbine Using Biodiesel From Various Sources as Fuel
Authors: Nascimento Marco A. R. , Lora Electo S. , Sierra R. Guido A. , Rendon Manuel A.
Published: May 2009

Biodiesel is an alternative fuel that has become more attractive recently because of its environmental benefits and the fact that it is made from renewable resources. As it can be blended in any proportion with mineral Diesel, and there are several reports which presented substantial reductions in emissions of unburned hydrocarbons, carbon monoxide and particulate in IC engines without reducing the output power significantly. The aim of this work was to perform an emissions and performance experimental analysis to evaluate and compare the use of Biodiesel obtained from different sources, Castor, Soy and Palm Oil, on a 30 kW regenerative gas micro turbine engine installed in the laboratories of the Federal University of Itajuba´ – Unifei, Brazil, at different power levels at steady state condition. All the fuels were characterized in terms of its viscosity and heat value, and the thermal performance and the emissions were measured. In all cases, it was performed a comparison between the obtained results with Biodiesel and Diesel. None of the fuels presented any problem related to atomization process in the related tests, and have shown no significant changes in performance of the microturbine reaching levels of around 26% of thermal efficiency. The minimum Heat Rate obtained at full load, was for the Biodiesel from Palm oil case, and the maximum was for Castor oil with a value 8.38% higher than when operated with Diesel. In Addition, when measuring pollutants emissions in the exhaust gases, it was observed a slightly increment in CO and a reduction in NOx concentration.
The Quest for More Efficient Industrial Engines: A Review of Current Industrial Engine Development and Applications
Authors: Cullen Barry , McGovern Jim
Published: May 2009

The paper addresses the need for efficiency gains in the modern industrial engine as utilized in Combined Heat and Power (CHP) generation and other Distributed Generation (DG) situations. Power generation is discussed in terms of reciprocating-engine-based plant operating on Otto type thermodynamic cycles. The current state of the technology and the research being conducted is examined. Internal combustion engine (ICE) performance improvement in the industrial engine sector focuses on improvements in the combustion characteristics of the plant, with emphasis on areas such as piston design, valve timing and supercharging. Maximum brake thermal efficiencies, in percentage terms, are currently in the forties. In CHP generation, most of the energy not utilised for mechanical power is recovered as heat from various engine systems such as jacket water and exhaust and utilised for space or process heating. In other Distributed Generation situations, this energy is not utilised in this manner and is lost to the surroundings. While second law analysis would provide a more meaningful interpretation of the efficiency defect, this approach is still not the norm. Distributed Generation benefits directly from efficiency improvements; the more efficient use of primary energy leads to reduced fuel costs. Combined Heat and Power generation is, however, more sensitive to the matching between the plant and its energy sinks, as its successful implementation is dictated by the ability of a site to fully utilise the heat and electrical power produced by the plant. At present, the energy balance of such engines typically dictates that heat is produced in greater quantity than electrical power, the ratio being of the order of 1.1 — 1.5: 1. Due to this production imbalance, it is accepted that in order to be economically feasible, thermal and electrical demand should be coincident and also all heat and power should be utilised. This has traditionally led to certain sectors being deemed unsuitable for CHP use. Some current research is aimed at tipping the production balance of these engines in favour of electrical power production; however, performance gains in this regard are slow. The paper concludes with some brief commentary on current industrial engine developments and applications and proposes some directions for progress.
Design and Validation of a Compressor for a New Generation of Heavy-Duty Gas Turbines
Authors: Eulitz F. , Kuesters B. , Mildner F. , Mittelbach M. , Peters A. , van den Toorn B. , Waltke U. , Rimmington P. , Wasdell D.
Published: May 2009

Siemens H-Class. Siemens has developed the world-largest H-class Gas Turbine (SGT™) that sets unparalleled standards for high efficiency, low life cycle costs and operating flexibility. With a power output of 340+ MW, the SGT5–8000H gas turbine will be the primary driver of the new Siemens Combined Cycle Power Plant (SCC™) for the 50 Hz market, the SCC5–8000H, with an output of 530+ MW at more than 60% efficiency. After extensive lab and component testing, the prototype has been shipped to the power plant for an 18-month validation phase. In this paper, the compressor technology, which was developed for the Siemens H-class, is presented through its development and validation phases. Reliability and Availability. The compressor has been extensively validated in the Siemens Berlin Test Facility during consecutive engine test programs. All key parameters, such as mass flow, operating range, efficiency and aero mechanical behavior meet or exceed expectations. Six-sigma methodology has been exploited throughout the development to implement the technologies into a robust design. Efficiency. The new compressor technology applies the Siemens advanced aerodynamics design methodology based on the high performance airfoil (HPA) systematic which leads to broader operation range and higher efficiency than a standard controlled diffusion airfoil (CDA) design. Operational Flexibility. The compressor features an IGV and three rows of variable guide vanes for improved turndown capability and improved part load efficiency. Serviceability. The design has been optimized for serviceability and less complexity. Following the Siemens tradition, all compressor rotating blades can be replaced without rotor lift or destacking. Evolutionary Design Innovation. The compressor design incorporates the best features and experience from the operating fleets and technology innovation prepared through detailed research, analysis and lab testing in the past decade. The design tools are based on best practices from former Siemens KWU and Westinghouse with enhancements allowing for routine front-to-back compressor 3D CFD multistage analysis, unsteady blade row interaction, forced response analyses and aero-elastic analysis.
Experimental Study in a 350 MWe Utility Boiler of Oil Droplet and Coke Size Analysis
Authors: Diego-Marin Antonio , Melendez-Cervantes Carlos , Giles-Alarcon Armando
Published: May 2009

A study was carried out to find out the cause of premature plugging of air heaters of a 350 MWe oil fired boiler. The unit burnt a heavy fuel oil number 6, with both high levels of sulfur (3.75%) and asphaltenes (16.2%), as well as high viscosity (555 SSF at 50°C) and API gravity of 11.2. Particle concentration at the furnace exit and at the stack were measured, also flue gas analyses were performed at the same sites. In the furnace were employed water cooled probes of six meters in length which allowed traversing 70% of its width. In addition, the oil droplet size distribution from an atomizer was measured with a Malver Particle Sizer. Cold condition using simulating fluids were taken in this analysis. Also, the unburned carbon particles size distribution, both from the furnace exit and from the stack, was performed with a particle Malver Sizer. The atomizer produced large oil drops, 5.7% by volume larger than 300 micron size, which were considered as promoters of unburned carbon. The concentration of carbon particles in the stack was 60% of that of the furnace exit. Furthermore, the particles from the stack were of smaller size (95% <150 μm) than those of the furnace (89% <150 μm). Deposition of carbon particles in the internal component of the boiler, mainly in the air heaters, was the cause of this finding. To solve the premature plugging of the air heaters of this oil fired boiler, the atomizers should be modified to reduce at a minimum level the oil drops larger than 200 micron size.
Fan Performance Test and Evaluation Methodology: Addressing the Difficulties of Full and Partial Capacity Testing When the Specified and Site Conditions Don’t Match
Authors: Kaufman Steven G. , Falk Mats A.
Published: May 2009

For many years now, an increased emphasis has been placed on the energy requirements of electric motor driven equipment. For end-users footing monthly electrical bills, efficiency is important along with the assurance that the equipment delivers the specified output. With fans, it is now commonplace to put performance guarantees in place when purchasing new equipment which specify volume flow, pressure requirements and expectations for efficiency or power that have to be met. Test procedures suitable for conducting fan performance guarantee tests are available in many published AMCA, ASME, ANSI, BS and ISO performance test standards and codes. These procedures specify how to measure the fan performance at discrete operating points and provide uncertainty analysis methods to estimate the accuracy of the test. Some test standards are believed to provide more accurate field test results than others. It is generally recognized throughout industry that it is virtually impossible to have suitable correlation between the site and the specified design conditions for the purpose of a ‘guarantee test’. This is often due to differences in the actual system resistance compared to what was predicted by the original design calculations as well as difficulties of adjusting system resistance and maintaining system stability with a process operating on line. The method of fan volume flow control, whether variable speed or throttle control, influences the amount of time and effort required to get the test point as close as possible to the specified operating point. With possibly the exception of AMCA and BS, published test standards and codes generally do not provide methods for evaluating whether the performance guaranteed by the fan vendor has been verified by a performance test. This technical paper provides guidelines for how to approach the difficult problem of verifying guaranteed operating points on fans. It specifically deals with the following aspects: - Evaluation of both partial and full capacity operating points. - Data collection methodology for selecting the number and relative positions of performance test points that are required to verify a guaranteed operating point. - Evaluation methodology that will relate the test points obtained to the specified operating point; Single Point, Multiple Point Line and Multiple Point Box data collection and evaluation methods. - Potential acceptance tolerances for flow, pressure, power and/or efficiency of the guaranteed operating point. - Field test accuracy and the implications on acceptance tolerances.
Markov Modeling Application to a Redundant Safety System
Authors: Adams George , Ferrante Fernando
Published: May 2009

Redundancy of components and subsystems is part of the design of reliable complex engineering systems used in several industrial applications, including power generation facilities. Such engineering systems may be in one or more intermediate operating states at various times. For example, these systems could continue operating during the repair of failed components and during maintenance intervals. For this reason, they do not lend themselves well to traditional reliability modeling techniques that do not account for a system’s progression through various intermediate states. The use of traditional reliability modeling techniques may lead to significantly different estimates of the performance of a complex system required to exhibit high reliability. This paper discusses the application of a Markov modeling approach for the development of reliability estimates of complex engineering systems. This approach is expected to have advantages for modeling reliability for such systems, since they are commonly comprised of redundant sets of components and require a strict set of maintenance operations to ensure their reliability.
Using a Multiport Pitot Tube in Circulating Water Flow Measurements
Authors: Figueroa Ibarra Luis R. , Rodri´guez Marti´nez J. Hugo , Santaba´rbara Botello Marcelino
Published: May 2009

This paper details the design of a Pitot tube used for water flow rate measurements in large pipes. The paper describes first the nowadays commonly used device (simplex pitot), based on standard CTI Code ATC-105 from Cooling Tower Institute [1]. The disadvantages of the simplex pitot are pointed out, and the detailed description of the proposed device (multiport pitot) is explained. The Multiport Pitot, which design is also based on norm ATC-105, is able to perform real-time measurements. The paper also includes the results obtained from the water flow rate measurements made in the cooling system of a thermal power plant in Mexico. These measurement results were compared to simulation results obtained with a computational commercial simulation tool.