bluuebunny/crossref_metadata_2025 huggingface dataset:
Experimental Investigation on the Control of Particulate Emissions Using Cera Fiber Filter in a DI Diesel Engine
Authors: Annamalai K. , Jeyachadran K.
Published: December 2008

Diesel engines are gaining importance in recent years because of its efficiency. But diesel particulates which are extremely small in size (0.1–1.0 micron) have raised lot of health and environmental problems. These particulates enter the human respiratory system during inhalation, which may cause lung cancer. Diesel particulates consist of two major components namely Insoluble Organic Fraction (IOF) comprised primarily of carbonaceous materials and a Soluble Organic Fraction (SOF) made up of hydrocarbon materials. An experimental investigation was conducted to study the performance of catalyst coated ceramic fiber filter (mullite) wound cartridge mounted in a canister on emission as well as performance. The canister was fabricated to accommodate one to three cartridges. It is seen that the catalyst coated ceramic fiber filter gives better reduction of particulate when compared to uncoated ceramic fiber filter and also gives lower smoke, higher bed temperature, lower pressure drop, lower specific fuel consumption and higher brake thermal efficiency.
A Phenomenological Combustion Model for Common Rail Multi-Jet Diesel Engine
Authors: Ponti Fabrizio , Serra Gabriele , Siviero Carlo
Published: December 2008

The simplest way to describe the combustion process into the cylinder of an internal combustion engine and the associated heat release is to estimate at each crankshaft angular position the mass fraction of fuel burned using a proper function. There is a number of functions recorded in the literature that have been used for this purpose, the most relevant being likely the so-called Wiebe function. These functions have been developed both for spark ignition and diesel engines. The development of modern Common Rail injection systems makes the application of this kind of methodology particularly challenging. The trend seems to indicate, in fact, that in the near future Diesel engine injection systems will perform up to five injections per engine cycle. Therefore the way energy is released into the cylinder could become very complex to be described and the simple approaches developed up to now could be not sufficient anymore. This paper deals with the development of a single zone combustion model able to correctly describe the heat release rate for a common rail multi-jet diesel engine employing up to 4 injections per engine cycle. The model has been developed step-by-step from the simplest case of a single injection to the more complex one with 4 injections. It has been identified and validated using experimental data obtained employing from 1 to 4 different injections. Premixed and diffusive combustions have been taken into account, both modelled as “Wiebe functions”. Particular identification problems (such as modelling error with multiple injection or identification robustness procedure) are approached on the basis of real data. The main result is that increasing the number of injections actuated (and then the combustion phases) predictive properties of the model are still acceptable, and identification procedure is robust if initial values of unknown parameters are properly set. The obtained results allowed observing for example the way the combustion delays (i.e the time delays between each Start of Injection and the corresponding Start of Combustion) are modified as the number of injections increases, as well as other important combustion characteristics.
Nonlinear Versus Linear Stress-Strain Relations in Engine Turbulence Modeling Under Swirl and Squish Flow Conditions
Authors: Baratta Mirko , Catania Andrea E. , d’Ambrosio Stefano
Published: December 2008

A general form of the stress-strain constitutive relation was introduced for the application of two nonlinear k-ε turbulence models, namely, the ARS model of Gatski and Speziale ([1]) and the Cubic model of Lien et al. ([2]), to the numerical analysis of flow fields in a test engine with flat-piston and bowl-in-piston arrangements, under swirling or no-swirling flow motored conditions. The model capabilities in capturing turbulent flow features were compared to those of the upgraded linear RNG k-ε model which was previously indicated as a good compromise between accuracy and computational cost ([3]). Evaluations were made on the basis of the predicted flow evolution throughout the whole engine cycle, as well as of the comparison between numerical and experimental results. Furthermore, the effect of the stress-strain relationship on the predicted averaged turbulence quantities and anisotropy invariant values were examined, in addition to the sensitivity of the nonlinear models to the mesh quality. Finally, prospects concerning possible improvements of turbulence Eddy Viscosity Models (EVM) were presented. The predictions were made by a newly developed CFD code embedding various accuracy-order finite-volume discretization schemes. Modified wall boundary conditions with respect to the conventional logarithmic-function approach were used, so as to give negligible importance to the local equilibrium hypothesis.
Development of a New Mechanism for a Rotary Internal Combustion Engine
Authors: Athiayyappasamy M. , Udaya Kumar R.
Published: December 2008

A new mechanism for working of a rotary engine is suggested based on Brayton / Atkinson cycle. This mechanism is designed in such a way that the expansion volume in three times greater than the suction volume and in this engines the exhaust gases can expand inside the engine down to atmospheric pressure. This is expected to increase the work output, reduce the exhaust heat losses and exhaust noise. Also in this engine compression ratio of 20 can be attained with out using any auxiliary compressing unit where as which is not possible in a conventional Wankel diesel engine. This mechanism was developed and animated using “C” programming language and pressure, torque values are estimated with respect to the crank angle.
Performance Evaluation of Feedwater Heaters for Nuclear Plants Under Normal and Abnormal Conditions
Authors: Sunder Raj Komandur S.
Published: December 2008

This paper discusses the performance of feedwater heaters for nuclear plants under normal and abnormal conditions. Normal conditions are defined as all heaters operating in their design configuration with no plugged or leaking tubes. Abnormal conditions refer to plugged tubes, leaking tubes, heaters out of service, extraneous flows, etc. In recent years, with several nuclear plants uprating or planning to uprate, heaters are operating or will be operating at or very close to their thermal design levels. Also, many heaters are being subject to abnormal conditions. All these result in both thermal and hydraulic overload and premature as well as accelerated failure of several heaters. The paper examines the performance parameters for heaters under normal and abnormal conditions and the use of performance modeling tools in evaluating performance. Recommendations are provided for monitoring the performance of heaters under normal and abnormal conditions.
Heat Balance Techniques for Diagnosing and Evaluating Feedwater Flow Nozzle Fouling in Nuclear Plants
Authors: Sunder Raj Komandur S.
Published: December 2008

In nuclear plants, feedwater flow is utilized to calculate the heat input to the Nuclear Steam Supply System (NSSS). The heat input, in conjunction with a heat balance around the reactor, is used to calculate the reactor core thermal power. Since a calibrated flow nozzle is used to measure feedwater flow and, the calibration assumes a clean flow section with no fouling, any deposits or fouling of the flow nozzle will result in errors in flow measurement, causing the flow to read high. This would result in a calculated reactor power higher than the true value and an attendant loss in plant capacity. The paper presents the methodology and heat balance techniques used in diagnosing the existence of feedwater flow nozzle fouling and in quantifying the capacity loss. The paper provides recommendations on how to monitor performance for tell-tale signs of feedwater flow nozzle fouling and steps to take for corrective action.
Gland Seal Erosion in a Geothermal Turbine
Authors: Mazur Zdzislaw , Palacios Luis M. , Urquiza Gustavo
Published: December 2008

Excessive erosion of the low-pressure shaft end gland seal of a 25 MW geothermal turbine has been investigated. Due to excessive erosion of the gland seal rotor surface the turbine vacuum was partially destroyed and the efficiency of the cycle degraded. This study uses computational fluid dynamics (CFD) to identify the causes of erosion and the optimal steam seal system flow conditions for reducing the erosion problem. The predictions were based upon a numerical calculation using a CFD model of the rotor end gland seal with a steam flow containing hard solid particles and solved with the commercial CFD code: Adapco STAR-CD. The results confirmed the existence of flow conditions that play a major role in the rotor gland seal erosion. Afterwards, the flow was simulated changing seal steam flow conditions (flow pressure). It was confirmed that there exists threshold seal flow conditions below which erosion does not occur. The recommendations for adjusting shaft end gland seal system are provided to avoid erosion problem.
Experience in Application of Thermal Diagnostics in the Turow Power Station
Authors: Gardzilewicz Andrzej , Gluch Jerzy , Bogulicz Malgorzata , Walkowiak Roman , Najwer Malgorzata , Kiebdoj Jozef
Published: December 2008

The thermal diagnostics of a steam power unit in the TUROW Power Station is based on the DIAGAR system and thermal and flow measurements, recorded on-line by the DCS system. Along with direct evaluation of the operating parameters of the thermal cycle, the diagnostic system evaluates degradation of the system components and prognoses economically justified repair actions.
A Technoeconomic Comparison of IGCC Power Plants With Cold Gas Cleanup and Hot Gas Cleanup Units Using Indian Coals
Authors: Rao J. S. , Neelima J. , Srikanth G.
Published: December 2008

Bulk of CO2 emission comes from thermal power generation, which constitutes about 63% of total installed capacity of around 101.6 GWe. The policy makers and power utilities are increasingly favoring the introduction of clean coal technologies, which release less pollutants viz. CO2, NOx and SOx than the conventional thermal plants and have potential to operate at higher efficiencies above 42–44%. Among the clean coal technologies, Integrated Gasification Combined Cycle (IGCC) is being considered the most promising because of higher thermal efficiencies and improved environmental performance. IGCC has the added advantage of removing sulphur pollutants in bed using sorbent as against expensive external post combustion flue gas desulphurisation systems. It is proposed to set up 100MWe-demonstration plant for proving the emission standards and performance prior to commercialization. This plant is based on Frame 6 FA gas turbine designed for low Btu gas firing. The Paper presents the technical parameters and compares the overall project cost of 100MWe IGCC plant for both Cold gas cleanup unit (CGCU) and Hot gas cleanup unit (HGCU), which comprises of Gasification Island, power block, and balance of plant. Being first of kind the project cost is higher and the project cost is likely to get reduced for utility scale of 425 MW IGCC plants in future.
Optimum Condenser Cooling Water Temperature Rise in Power Plants
Authors: Srinivasan Ram
Published: December 2008

The concept of optimum cooling water temperature rise in a power plant has been introduced in this study as that which corresponds to the highest possible net plant output. Every power plant having a steam turbine exhausting to a water-cooled condenser has a unique optimum cooling water temperature rise. This optimum temperature rise may not be the minimum possible as often inadvertently assumed by power plant designers. This optimum temperature rise is a strong function of the steam turbine exhaust parameters. The author has developed correlations, which will help determine the optimum temperature rise using easily available power plant design parameters. This paper will discuss the details behind this method and show the thermal and financial advantages of designing a plant with this concept. A proper understanding of this concept will enable power plant designers to economically and efficiently size the condenser cooling water system.
Pickering B Nuclear Power Generating Station Condenser Performance Improvement
Authors: Allen Wayne , Anderson David , Mayer Bert
Published: December 2008

The Ontario Power Generation (OPG) Pickering B Facility consists of four 540 MW nuclear generating units. Each unit is furnished with a once-through Condenser Cooling Water (CCW) System that uses Lake Ontario water. Zebra mussels (Dreissena polymorpha) are infesting the condenser cooling water intakes at Pickering. The mature mussels and their shells become entrained in the CCW, are deposited in the condenser inlet water boxes, and become lodged in the condenser tube sheets and within the tubes. As a result, the flow through the condenser is reduced, and the existing Condenser Tube Cleaning System (CTCS) performance is degraded. This reduces the Turbine-Generator generating capability that results in a loss of electric generation revenues for OPG, and increased maintenance costs to manually remove the zebra mussels from the condenser. OPG decided to install Debris Filters in the six 72-inch diameter inlets of each of the four Pickering B units to automatically remove the zebra mussels before they enter the condensers and discharge them back into the lake. The Debris Filters for Unit 8 were installed during a scheduled outage in the winter of 2001/2002. The Unit 5 installation was completed at the end of 2002 and the Unit 6 & 7 installations are scheduled for 2003. The installed equipment is performing as expected. The zebra mussels are intercepted by the Debris Filter, and are automatically discharged into the condenser bypass and returned to the lake. The CTCS system can again perform its intended function to prevent bio-fouling buildup inside the condenser tubes. As a result, generation capacity increased and maintenance expenditures decreased with a net result of increased revenues for OPG.
Modelling and Advanced Control of Industrial Wood Waste Boilers
Authors: Meeker Richard H. , Selekwa Majura F.
Published: December 2008

This paper describes recent work to develop an improved approach to control of wood-waste fired boilers, and, in particular, bark-fired boilers commonly in operation in the pulp and paper industry. A brief review of the process and control requirements and common control methods currently employed is followed by a discussion of development of a first-principles boiler model suitable for use in development of a robust controller. A simple nonlinear model for the boiler is developed and used for designing a robust controller that offers better performance in terms of tracking the desired reference point in the face of uncertain variations in the system parameters. The objective of the proposed controller is to increase the responsiveness to load changes, reduce the variability of controlled parameters, and improve efficiency of the boiler (reducing fuel consumption). With hundreds of these boilers in operation at large pulp, paper, and paperboard mills in the U.S., potential net energy savings through efficiency improvement and reduced fuel consumption are substantial, with likely side benefits of reduced emissions and possible reapplication of developments to fossil-fired electric utility boilers, waste incinerators, hog fuel, and biomass boilers.
Theoretical and Experimental Analysis of Heavy Duty Gas Turbine Performance Depending on Ambient Conditions
Authors: Brusca S. , Lanzafame R.
Published: December 2008

A mathematical model of a heavy duty gas turbine has been implemented using GateCycle™ code. This model is able to simulate the engine behavior running on syngas and fuel oil. Also engine control logic is implemented using Microsoft Excel™ VBA language. The model implemented has been finely tuned and tested with measured data. Test results show that it is able to simulate engine running in on-design and off-design conditions. Using this model, an extensive thermodynamic analysis of light fuel oil and syngas fed engine performance has been carried out in respect of ambient conditions. As it is possible to see in the results of the thermodynamic analysis, at high air temperatures performance reduction occur. Relative humidity have a slightly effect on engine performance when the latter is running on syngas. Instead it doesn’t have a relevant effect on the performance of the engine running on light liquid fuel oil in all the range of ambient temperature investigated. Results of this analysis also show the correct replication of the engine control system. In conclusion, the developed mathematical model is able to simulate gas turbine operations with low errors. So that, it could be used in order to optimise engine performance at the ambient conditions that occur for the site of the IGCC Complex in which gas turbine has integrated as topper.
Theoretical and Experimental Analysis of Carbon Coke Fed Steam Power Plant Performance
Authors: Brusca S. , Lanzafame R.
Published: December 2008

This paper deals with the theoretical and experimental analysis of carbon coke fed steam power plant performance. Thus, A mathematical model of the generator and of all power plant has been developed and implemented within GateCycle workspace. Using experimental data the mathematical model has been finely tuned and tested in several running conditions in respect of refinery requests. Results analysis has shown that it is able to simulate power plant running in on-design and off-design conditions with low relative errors. Using mathematical model, the effects of steam extraction by the refinery from the “high, medium and low pressure level manifolds” on the turbine efficiency and heat consumption as well as on steam generators performance have been studied. Results analysis has been shown that steam extraction involves a turbine performance reduction. The developed mathematical model could be used to optimize steam turbine efficiency as well as generators performance in order to study the better control strategy.
Failure Analysis of the L-0 Steam Turbine Blade
Authors: Kubiak S. J. , Gonzalez R. G. , Jua´rez R. D. , Nebradt G. J. , Sierra E. F.
Published: December 2008

The main objective of the paper is to present an analysis that leads to detect the most possible cause of the L-0 blade fracture. Recently, several L-0 blades 28.5 inches long of a steam turbine have fractured. The fracture appeared 5 inches from the blade root platform, Fig. 1-“C”, causing the forced outage of the turbine. Previously, in the beginning of the last decade a finite element analysis of the blade was carried out calculating the natural frequencies and the vibratory stresses, and also, a telemetry test was carried out on these blades. These were published several years ago [1]. The analysis results gathered then were very precious to find a root cause of the present failure. To find out the causes of the blade fracture the following activities were carried out: analysis of the operational data during the last two years, analysis of the previous investigations, metallurgical investigations, identification of the mechanical and metallurgical modes of the failure. Apart from that, the turbine was overloaded by certain period of time. In this paper the results of the investigations indicated a miswelding process of the stubs as a principal cause of the blade fracture.
Prospects of Fluidized Bed Combustion in Power Generation
Authors: Poduri Sridhar
Published: December 2008

Power plays a great role in our daily life aiding in diverse activities such as industry, agriculture, transport etc. Power provides our homes with light and heat. The living standard and prosperity of a nation vary directly with increase in use of power. In short, “Power is the power of a nation”. As Technology advances, the consumption of power is steadily increasing. This necessitates two main options for the scientific community. They are: 1. Search for new sources of energy. 2. Devise new and effective ways of producing energy. A new and efficient method of utilization of energy should satisfy the following conditions: 1. It should be technologically feasible for usage in varying conditions. 2. It should be economically viable. 3. It should show a marked increase in performance over the systems currently under use. 4. It should be reliable and flexible. Since the advent of industrialization coal has been the most predominant form of fuel under use and will probably remain so for a few more decades to come. The whole world depends heavily on the energy obtained from coal. The known reserves of coal, a fossil fuel may not last forever. Hence the imperative to develop efficient methods of burning coal, thus decreasing fuel wastage and various losses associated with the other systems of burning coal. Fluidized Bed Combustion (FBC) has attracted international attention as an alternative coal fired technology for the future. In addition to its potential advantages in the area of boiler performance and pollution control, it also provides considerable fuel flexibility. This has opened doors to the use of unconventional fuels which otherwise would not have been possible to be utilized for steam generation. Amongst these are high ash and high sulfur coals that are abundantly available throughout the world. This report covers the operating experience at the Power Block of Coastal Papers Ltd., a member company of the AP Paper Mills Ltd., India during the period Jan 2001 and June 2001 on the 36 t/h atmospheric fluidized bed boiler supplied by M/S Cethar Vessels Ltd., India. This report covers the details the boiler setup, water treatment, boiler operation, turbo generator, and the various plant characteristics. India has an estimated 112 billion tones of coal reserves and 40% of it contains more than 32% ash. The state of Bihar has around 1185 million tones of low volatile coal and the state of Assam has about 2500 million tones of high sulphur coal.
Four Years of Successful Operation at Mercer Generating Station Following Feedwater Heater Tube Repair: An Alternative to Replacement
Authors: Schafer Bruce W. , Patten Daniel B. , McCall Charles R.
Published: December 2008

In the late 1990’s, two of the high-pressure feedwater heaters at PSEG Power LLC’s Mercer Generating Station began to experience tube leaks after almost 40 years of operation. Prior to the repair, these leaks were occurring at least once per month. Based on eddy current and video probe inspections, the area of tube degradation appeared to be isolated to the desuperheater region of the bundle. PSEG Power LLC performed a life assessment of the feedwater heaters and, based on the good condition of the remainder of the heaters, determined that repair of the desuperheater region could improve the reliability and significantly extend the operating life of the heat exchangers. The heater condition, coupled with a repair vs. replace economic model, led to the decision to sleeve the feedwater heaters. During the April 1999 maintenance outage, Framatome ANP performed repair work on the two high pressure feedwater heaters. This repair consisted of installing an 11 foot-2 inch (3404 mm) sleeve in all outlet tube ends, spanning the desuperheating region. The sleeving method used consisted of a three step process. After the sleeve was installed, its lower end was roll expanded within the tubesheet. Next, the entire length of the sleeve in the desuperheater section was expanded into close contact with the parent tube. The final installation step was upper hydraulic expansions, above the desuperheating zone end plate, in nondefective portions of the tube. This installed sleeve became the pressure boundary in the desuperheater section of the feedwater heater. After more than 4 years of operation, no tube leaks have been noted and the need to replace the components has been eliminated for the foreseeable future.
High Tech Tool for Combustion Optimization and Economic Emissions Reductions
Authors: Elsen Guido , Jensen Alan D. , Boehme Axel , Happel Jens
Published: December 2008

The power generation industry is currently in a very difficult period of business restructuring. All the while, the demands to reduce emissions of NOx, SOx and particulates in accordance with the Clean Air Act continue. The high capital and operating cost of post-combustion NOx controls like Selective Catalytic Reduction (SCR) is leading to greater interest in finding methods to reduce NOx formation during combustion. The most cost effective means of reducing any pollutant is to never form it in the first place. The science behind combustion NOx control uses techniques which limit the amount of air available in the high temperature combustion zones where thermal NOx forms. Minimum NOx formation occurs when fuel and air mixing are carefully controlled to maintain required stoichiometric ratios. Additionally, controlling coal and air flow minimizes excess air requirements, can reduce unburned carbon resulting in better electrostatic precipitator performance and improved overall boiler efficiency. Thus maintaining fuel and air flow at optimal levels becomes a major concern if one wishes to achieve minimum NOx formation during combustion and maintain optimum boiler performance throughout the units load range. Since pulverized coal is transported by primary air in a two phase flow it has been difficult, if not impossible, in the past to measure coal mass flow on a continuous basis. Typically, coal flow and fineness have been measured on an intermittent basis using extractive techniques. This paper serves to introduce a real-time “flow measuring system” for pulverized coal, based on the use of microwave technology. It will describe how microwaves are used to obtain very accurate coal flow measurements. Comparisons of data obtained using the microwave system will be made with measurements obtained using extractive isokinetic methods. Some relevant operational effects from both US and German installations will be discussed and projections of operational savings will be made especially when using the system on an SCR equipped installation.
A New Concept for a Thermal Air Power Tube Used With Concentrated Solar Energy Power Generation in Open-Pit Mines and Large Natural Geo-Physical Phenomenon
Authors: Di Bella Francis A. , Gwiazda Jonathan
Published: December 2008

This paper reviews a novel power generation system that improves the overall efficiency of concentrated solar energy systems while also providing for the cost effective reclamation and utilization of a man-made geo-physical phenomenon: decommissioned, open pit mines. A preliminary feasibility will be presented of an integrated system consisting of a concentrated solar energy powered Rankine Cycle system and the authors’ novel (patent pending) energy recovery system that consists of a thermally induced, pneumatic (wind turbine) power tube system (Pneumatic Power Tube) that is designed with reflective surfaces for concentrating solar energy. The proposed system is unique in the field of power generation using renewable/natural resources while also providing a solution to the reclamation and utilization of depleted open pit mines. The paper presents a parametric feasibility study of the proposed system installed for a range of “small” and “large” open-pit mines, such as the Palabora copper open pit mine located in South Africa. Using state-of-the-art specifications for power generation from concentrated solar energy systems based on D.O.E. supported research, a average size integrated installations could generate approx. 700–750 Mwe with 12–18 Mwe contributed by the new Pneumatic Power Pit Tubes. The enhancements include a unique design for a pneumatic power tube that combines the functions of solar collector/reflector with a hot air “chimney” air diffuser and wind power generation. A schematic of the proposed integrated system is also provided. The paper also presents a summary of the major technical benefits of the proposed system including the synergisms between the proposed renewable energy system and the application of DOE’s microwave power generation and transmission as well as the societal benefits of reclaiming land areas that are otherwise not suitable for habitation. Suggestions will also be made as to the application of authors’ pneumatic wind turbine power tubes to other large, naturally occurring geo-physical phenomenon.
High Steam Turbine Operating Flexibility Coupled With Service Interval Optimization
Authors: Ulbrich Artur , Gobrecht Edwin , Siegel Michael R. , Schmid Erich , Armitage Pamela K.
Published: December 2008

Historically steam turbine operations were designed for a market that was typically either base load or intermediate duty load operation. The optimal steam turbine start-up profile was established using the maximum allowable component stress and therefore optimizing service time consumption. Over the last few years, the market requirements have changed significantly. The market requires plant start-up flexibility with the ability to accurately predict start-up time, and reliably meet the start-up time. Applying the historical steam turbine start-up philosophy either limits the operating flexibility of the plant or exceeds steam turbine allowable stresses increasing service time consumption. Innovative concepts are being presented on how steam turbines can achieve reduced start-up times while minimizing service time consumption thereby improving availability. These concepts allow the customer to be able to accurately predict start-up times and reliably meet the dispatch bid. Therefore, an economic calculation may be performed to determine the most effective start-up mode. This economic calculation will evaluate the impact to service life (inspection and test intervals) versus the benefits of power generation. The new concepts provide one solution for base load, intermediate duty load operation, and plants requiring fast start up capability. The new market needs for flexible operation including fast start-up times require plant operability enhancements [1]. Some of the operability enhancements that can be implemented include: • steam turbine stress controller and stress monitoring systems which allow a selection of the start-up mode determining the start-up time, thermal stress and service time consumption; • high level of plant automation; • plant systems designed to provide steam conditions necessary for selected start-up mode. The benefit of these solutions will be presented by means of examples from recently modified power plants. It is possible to achieve a significant improvement in the plant operation and start-up with low costs.
On the Inability of Multiple Exhausters to Eliminate Condenser Excess Back Pressure at High Air In-Leakage
Authors: Harpster Joseph W.
Published: December 2008

A comprehensive theoretical development, confirmed by inplant measurements, will be summarized showing the dependence of condenser air in-leakage and exhauster capacity on build up of excess back pressure caused by the establishment of a zone of stagnation near the condenser’s air removal section. It has been generally believed that there will not be a zone of stagnation and an associated excess back pressure, above the design pressure, provided the exhauster capacity for air removal remains higher than the air in-leakage regardless of the leakage size. This paper will show, however, that excess back pressure can occur at high air in-leakage, even though exhauster capacity is adequate. A gradual increase in the concentration of non-condensables as steam scavenges these gases toward the air removal section is presented. This results in a reduction of individual tube heat transfer coefficient in the high air concentration region which is accompanied by an increase in condenser pressure. It will be shown that this may be the condition of heat transfer reduction that many authors have used throughout the 20th century to describe the effect of air on all tubes in the condenser. An associated condition will also be discussed related to subcooling of the gas and vapor space between tubes within the region of reduced heat transfer. With high air in-leakage and high exhauster capacity, it will be shown that near the air removal section the large amount of air flow will scavenge steam through the subcooled region, directed toward the vent line, causing generation of a condensate mist that becomes suspended in the moving air. The reported theoretical explanation is derived using a condenser model developed earlier by the author. The results are confirmed from measurement data taken on an operating plant using a RheoVac® condenser performance and diagnostic instrument, the description of which may be found in the open literature.
Analytical Model of Copper Deposition Patterns on Large Fossil Steam Turbines for Use in Steam Path Design
Authors: Brisson Bruce W. , Alaksiewicz John D.
Published: December 2008

Numerous fossil steam turbine utilities are experiencing performance degradation due to copper deposition. Current restoration techniques involve periodic foam cleaning or blast cleaning of the steam path (depending on degradation rate), both of which can be costly in terms of unit down time. Using data from units experiencing similar problems, the deposition distribution pattern in the steam path can be determined. Steam turbine design analysis tools are applied to create an analytical model. Changes in bucket/nozzle surface finish, profile losses and reductions in flow area are included inputs. A direct comparison of output loss between older impulse-type and advanced, modern steam paths can then be made from the analytical model developed. Some conclusions as to the deposition conditions can be inferred from comparing the thermodynamic conditions to the deposition pattern.
Upgrade of Thermal Stress Supervision and Lifetime Assessment
Authors: Weiss Gerhard J. , Kopczynski Jerry A.
Published: December 2008

Steam power plants have an average service life of 40 years. There are many power plants still operating with the original supervision systems. These plants were equipped with control, protection, and supervision systems, which were available at the time. Over the last 20 years, steam turbine control/protection systems’ capabilities have been greatly improved. New hardware and improved software are available today to extend the life of existing turbines. For example, older turbines were originally equipped with casing metal temperature measurements or with so-called mechanical temperature probes for stress supervision. These measurements assist operators during manual run-up and loading of the turbine. Today’s upgraded supervision systems use the original sensors to measure the turbine metal temperature. Existing temperature signals are used as inputs to the electronic modules. These modules calculate the actual stresses in rotors and/or casings and acceptable margins. In cases where the calculated stress exceeds the pre-set limits, the run-up or loading gradient is automatically reduced, thus optimizing startup time of the steam turbine and resulting in optimal usage of the turbine’s life. Based on many years of experience in steam turbine design and service, standard proven algorithms are used to determine stress calculations. Automatic stress limiters can be installed. Acceptable stresses as well as actual stresses and margins can be displayed on the Operator Station (HMI) and recorded. Based on these records the lifetime assessment can be performed. The operator can select either slow, normal or fast startup, which will influence the lifetime consumption.
Ultrasonic Testing in 25 Minutes
Authors: Blum William E. , Gryba¨ck Thomas
Published: December 2008

Nondestructive Testing (AKA NDT, NDI, NDE) is an integral part of any power generation program. Ultrasonic Testing (UT) is one NDT method used to determine the integrity of materials and components. Managers, engineers, quality control personnel and others often require a fundamental understanding of the nondestructive testing methods used in their operations. This paper introduces basic theory, advantages and disadvantages, typical equipment and applications of ultrasonic testing. It is designed to give the reader a basic understanding of ultrasonic testing.
Energy Production and Performance of a Large Photovoltaic Roof
Authors: Ubertini Stefano , Desideri Umberto
Published: December 2008

The market for photovoltaic is rapidly expanding and there are some large utility PV power plants, thousands of residential systems, and tens of thousands of remote power systems in use. Even if photovoltaic is a technology that has already demonstrated its effectiveness and holds great promise in electrical generation, the costs are still too high to guarantee a commercial competitivity. This paper presents the performance results of a 15 kWp photovoltaic power plant installed on the roof of a high school in central Italy. The system consists of 220 modules for a total of 22 arrays, which are connected to inverters to allow conventional appliances to be powered by photovoltaic electricity. The PV plant is remotely controlled and data on sun radiation, ambient temperature, modules temperature and power production are continuously acquired by a PC. The measured power plant performances during the year are presented in this paper.
Experimental Investigation and Numerical Simulation of Gas Ejector in a Combustor With Combustion Gases Recirculation
Authors: Zhang Kumpeng , Xue Fei , Pan Weiming , Fan Zhihua
Published: December 2008

Sets of high-pressure ejection experiment were conducted to investigate the implementing of gases ejector with high-pressure condition. Numerical simulation was used to extend the study and overcome the limit of experiment facilities. Experiment shows that ejection coefficient of gases ejector was not sensitive to supply gas pressure changes. But which was affected greatly by backpressure in mixing cavity of ejector, as shown by simulation. The simulation result also implies that there are inherent relation between ejection coefficient, area ratio at inlet of mixing cavity and pressure different between supply gas pressure and the backpressure. And the relationship determines that in some range, the implementing of gas ejector was unstable.
Apparatus and Method for Emission Control Through Continuous Dry Filtration System
Authors: Avin˜a David
Published: December 2008

A method of improving the removal of particulate matter, heavy metals, and acidic gases in waste gas emission streams through continuous filter control through the utilization of independent chambers to divert the flow of waste gas during the cleaning and precoating cycles of the chamber to optimize emission collection efficiency and prevent fugitive emissions.
Innovative 3-D Numerical Simulation of Thermal Discharge From Browns Ferry Multiport Diffusers
Authors: Lin Fangbiao , Hecker George E. , Smith Brennan T. , Hopping Paul N.
Published: December 2008

The TVA Browns Ferry Nuclear Power Plant (BFNPP) withdraws its condenser cooling water from Wheeler Reservoir via an intake pumping station. Waste heat from the plant increases the condenser cooling water temperature. The heated water returns to the reservoir through three multiport diffusers containing a total of about 22,500 downstream facing ports. The ports are 2 inch diameter holes situated 6 inches apart both vertically and horizontally. The numerous small diffuser ports, the buoyancy of the heated effluent, and the large scale of the discharge area to be simulated present major challenges to developing a reliable three-dimensional computational fluid dynamics (CFD) method for predicting temperature distributions and flow patterns in Wheeler Reservoir. This paper presents an innovative CFD method and the results for numerically simulating under steady conditions the thermal discharge from the BFNPP. A finite-volume CFD package, FLUENT, was used to develop the required numerical models. The realizable k-ε turbulence model was selected for closure of the Reynolds-Averaged Navier-Stokes Equations. Second-order accurate schemes were used to discretize the governing equations. To simulate the discharge from thousands of diffuser ports, the CFD method features an innovative two-zone modeling approach, consisting of a multiple jet sectional model and an overall river model. The latter contains about 2 million computational cells for simulating the cooling water discharged from the thousands of multiport diffuser ports. The multiple jet sectional model, which simulates the flow from the individual discharge ports over a one foot slice of the diffuser pipe in great detail, provides the information for developing sectional boundary conditions for the diffuser effluent. These boundary conditions are then used in the overall river model for the whole study area. Validation and verification of the CFD models were performed using data from field measurements, hydraulic model tests, and other experiments. Comparisons between the CFD results and these data showed that the overall river model, based on the two-zone approach, can reproduce the major features of temperature and flow in the diffuser mixing zone. Model limitations exist, however, for low river flows, where requirements for steady behavior impede solution convergence.
Application of the New ASME Performance Test Code on Steam Surface Condensers PTC 12.2-1998
Authors: Karg Dale C. , Burns John M. , Catapano Michael C.
Published: December 2008

The Performance Test Code on Steam Surface Condensers underwent a major revision in 1998 with the release of ASME PTC 12.2 - 1998, “Performance Test Code on Steam Surface Condensers”. One of the improvements over the previous code revisions was the development of a new method for determining or estimating tube bundle fouling. Instrumentation has been developed to apply the new methods and was used in a test program on a recently retubed condenser. This paper describes the testing program initiated by Santee Cooper at the Winyah Generating Station where a successful attempt to utilize the guidelines established by the new Code were carried out. The objectives of our testing program were to: • Evaluate the data collected from the instrumentation developed to determine tube bundle fouling. • Propose methods for utilizing the new instrumentation to evaluate tube bundle fouling over time. • Compare the results of the test to design based on the Heat Exchange Institute Standards for Steam Surface Condensers (HEI) [2]. The initial results of the program demonstrate a good correlation between the actual versus projected condenser performance and tube bundle fouling by employing the methodology outlined in ASME PTC 12.2 - 1998. Santee Copper’s retubed condenser provided an excellent opportunity for the application of the new test code since the condition of the replacement heat transfer surface was known as “virtually clean”. The purpose of the testing was solely for investigative and information purposes as there was no performance “acceptance” criteria placed on the retubing project.
Dynamic Model Construction of an Industrial Flue Gas Recirculation (FGR) Furnace for Real-Time NOx Emission Control
Authors: Jiang Q. , Zhang C. , Jiang J.
Published: December 2008

Flue gas recirculation is one of the most effective ways to reduce nitric oxides (NOx) emission in conventional industrial furnaces. To design an effective control scheme, one has to understand the dynamic relationships among different furnace inputs and outputs. This paper concentrates on the construction of such dynamic models for an industrial furnace using numerical simulations and frequency domain system identification techniques. The numerical simulations are based on the conservation equations of mass, momentum, and energy. The inputs to the furnace consist of the pressure head of the flue gas recirculation fan, the temperature of the combustion air, and the flow rate of the combustion air. The outputs considered herein are NOx and oxygen (O2) concentrations. To obtain a dynamic model for this multi-input and multi-output system, low amplitude sinusoidal signals of different frequencies are administrated at the furnace input. The dynamic relationships among the inputs and outputs at these frequencies are established in terms of frequency responses (magnitude and phase) around a particular furnace operating point. These frequency responses are further processed by a least squares based system identification technique to convert them to a set of parametric models. The result of the system identification is a set of the transfer functions with the order ranging from 3rd to 6th. Studies have been carried out to verify the validity of these dynamic models by comparing the responses generated from these models with those obtained from the full-scale numerical solution. These dynamic models provide a starting point for the design of realtime optimal feedback control systems for minimizing NOx emission.
Real-Time, On-Line Balancing and Vibration Control for Power Plant Rotating Machinery
Authors: Winzenz Andrew , Altieri Russell
Published: December 2008

Vibration related outages due to an unbalance in rotating equipment have been a historic problem in the power generation industry and have resulted in increased plant operating costs. Until recently, the only means for solving these vibration problems was to perform manual balancing on the rotating equipment. Active balancing systems have been used in other industrial processing applications, on ID/FD fans, compressors, and turbines, for many years. Further developments in active balancing capabilities have positioned these systems to cover the broad range of applications in the power generation industry today.
Performance Enhancement of Advanced Combined Cycles
Authors: Sanjay  , Singh Onkar , Prasad B. N.
Published: December 2008

This paper reports on the development requirements of gas/steam combined cycle with an aim to achieve plant efficiency greater than 62% through various development possibilities in gas turbine and steam turbine cycle by taking a reference combined cycle configuration (MS9001H gas turbine and three pressure heat recovery steam generator with reheat). The innovative development possibilities include the advanced inlet design to reduce pressure loss, the increase in turbine inlet temperature, use of advanced turbine blade material, increased component efficiency, improved turbine cooling technologies along with better cooling medium, incorporating intercooling, reheat and regeneration either separately or in combination with simple gas turbine cycle using higher compressor pressure ratio, better utilization of heat recovery steam generator, minimum stack temperature, single shaft system configuration, etc. Based on the quantification of each development item, if incorporated in reference cycle, it has been estimated that the combined cycle as the potential to achieve the plant efficiency in excess of 63%.
Thermo-Economic Analysis of Combined Cycles
Authors: Yadav R. , Srivastava Priyesh , Saraswati Samir
Published: December 2008

The paper presents a thermo-economic analysis of gas/steam combined cycle. The stated objective is achieved by optimizing thermo-economic parameters for simple combined cycle (large and medium range) and to apply this to economic model of these cycles. The economic parameters evaluated in the present study include discount cash flow rate of return (DCRR) and gross payout period (GPO), two terms commonly employed in engineering economic analysis. DCRR and GPO are calculated for various electric sale and fuel prices. It has been found that maximum value of DCRR and minimum value of GPO are found with large size plant.