For SCR (selective catalytic reduction) applications both aqueous ammonia and urea reagents are used for NOx reducing agents in exhaust systems. For both diesel engines and small boilers, the reagent injection systems often consist of a few, and in some cases, a single injector, located on the wall of the exhaust pipe or duct. Often numerical modeling is performed to determine the location and orientation of the injectors and to predict the NRMS (normalized root mean square) of the gas phase reducing specie distribution prior to the catalyst. Aqueous ammonia and aqueous urea have significantly different processes from the point of injection to the formation of the gas phase reducing species. Evaporation characteristics are important, but for urea, the molecule must also decompose into ammonia and isocyanic acid. For modeling purposes, a simplifying assumption is frequently made to treat the liquid reagent as liquid water and assume that the evaporation of liquid water satisfactorily emulates the processes of forming the gas phase reducing species for both aqueous ammonia and aqueous urea reagents. In reality, the reagent droplets are binary component mixtures and treating the droplets as a single component, namely water, may significantly depart from reality. Additionally, the evaporation processes for aqueous ammonia and aqueous urea have significantly different behaviors. This paper addresses the potential errors associated with using a single component water drop for emulating the evaporation of aqueous ammonia and aqueous urea. This is accomplished by analyzing binary component evaporation for both aqueous ammonia and aqueous urea. Additionally, the time for the gas phase chemical decomposition of urea into ammonia and isocyanic acid is evaluated for various conditions. Typical decomposition times are compared to droplet evaporation times. Finally, the paper attempts to provide guidelines for determining when treating the drops as a single component may be sufficiently accurate, and when the complexity of modeling binary component evaporation is necessary.

Totally enclosed air to air cooled (TEAAC) generator with IC6A1A6 (as per IEC 60034-6) cooling is a widely accepted generator cooling solution for squirrel cage induction generators (SCIG) used in wind power generation, where the generator has two cooling systems, internal and external. The internal cooling is a closed loop system, where a shaft mounted mechanical fan helps in recirculating air inside the generator, and transfers the heat from the generator into an air-to-air heat exchanger. The external cooling system is a separate ventilation system creating airflow from the nacelle through the heat exchanger and removing the heat outside the nacelle with the help of an electrical fan mounted near the non-drive end of the generator. Cooling improvement of generator and bearing windings for performance enhancement is a well known research topic in turbo-generation as well as wind energy. Various winding design effort has been made in past for efficient generator cooling for turbogenerator as well as for wind turbine generator. With the increasing demand of power output, winding and bearing temperature class reaching its limit. Challenge is to come up with a solution for improving the performance of generator in terms of reducing temperature experienced by windings and at the same time reducing the cost. Detailed testing has been done on a test turbine to compare results obtained from open ventilated solution IC3A1 (as per IEC60034-6) and IC6A1A6 cooling for the squirrel cage induction generator. Paper presents advantages in case of using IC3A1 cooling where temperature of windings reduced substantially in comparison with IC6A1A6 cooling. To avoid contamination led windings and bearings hotspots, presented IC3A1 cooling configuration uses a unique design with inlet duct, filters, outlet duct and wire mesh.

Population explosion and rapid industrialization demands increased power production, whereas, environmental concerns are also an issue. The need of time is to develop eco-friendly technology which exploits renewable energy resources. Water is one of the most promising and cheap renewable energy resource. The gross approximate potential of hydro is 128 PW h per year while technically exploitable potential is only 26 PW h per year. Darrieus water turbine (DWT) is like Darrieus wind turbine but it operates in water instead of air. It is an emerging technology for the low head regions. This article focuses on the performance of DWT under different designing parameters i.e. different blade profiles, pitch angle, azimuth angles, tip speed ratio and effect of ducts. It will also focus on the different numerical models used for its simulation. Finally, based on the study an optimum model is selected for practical operations.

A 600MW tangentially fired sub-critical boiler with the volume heat load of 87.6kW/m 3 at the case of BMCR was not originally equipped with the separated over fire air (SOFA) system. Shenhua bituminous coal with low ash fusion point and strong slagging characteristics is employed as its design coal. To prevent serious slagging on its platen heaters, it is necessary to employ 80% Shenhua bituminous coal with low ash fusion temperature blending 20% Shenhua bituminous coal with high ash fusion temperature. However, NOx emission value at the furnace exit reaches more than 370mg/m 3 (O 2 = 6%). In order to achieve a NOx emission limitation level below 100mg/m 3 (O 2 = 6%) for pulverized coal power boilers which meets the requirement from latest Chinese environmental protection regulation, while considering a low cost of retrofit, a comprehensive low NOx emission boiler retrofit scheme combining air-staged low NOx combustion technology and selective catalytic reduction of flue gas in the low temperature flue duct of boiler was selected preferentially. Two-level air staging technology has some obvious advantages including a little negative effect on the boiler’s combustion efficiency, and easily achieving deep air-staged combustion mode. Therefore, a study of numerical simulation concerning original combustion mode and optimized two-level air staging combustion mode was conducted. Due to excellent ignition and burnout characteristics of Shenhua bituminous coal with high volatile matter, low ash fusion temperature and reasonable configuration of upper and lower burnout air ports, the NOx emission level at the exit of furnace would be greatly reduced, and the fouling layer temperature of water wall obviously decreases, which means a definite improvement of clean degree of furnace. And the gas temperature at the bottom of platen heaters decreases about 20 °C while burning 100% Shenhua bituminous coal with low ash fusion temperature. However, its combustion efficiency would decline weakly. The performance of boiler was optimized by combustion tests after the retrofit. This boiler can fully burn Shenhua bituminous coal with low ash fusion temperature by use of two-level air staging system, and furnace soot blowing frequency also lowered. Consequently, exhaust gas temperature decreased, which achieved an increase of boiler efficiency by about 0.3%. In addition, NOx emission level decreased more than 60%, and was about 15 mg/m 3 (O 2 = 6%) lower than coal blending cases. To meet a full burning of Shenhua bituminous coal with low ash fusion temperature, it is suggested that two-level air staging technology should be applied to the retrofit of boiler. And then goals of low NOx emission and anti-slagging on the platen heaters can be achieved.

Effects of the tube array, such as in-line and staggered, on void-fraction distribution and heat transfer coefficient around a tube were experimentally investigated. The test section was vertical duct with inner size of 90 × 90 mm 2 . Diameter of the tubes was 15 mm, and the pitch-to-diameter ratio was 1.5 for both tube bundles. Working fluids were air and water. Experiments were carried out at superficial gas velocity defined at minimum area section, J g , of 0.10 to 0.89 m/s, superficial liquid velocity, J l , of 0.1 to 0.3 m/s, under the atmospheric condition. Measurements of void-fraction distribution were carried out using X-ray radiography. In addition, heat transfer coefficient around a tube was measured and the heat transfer coefficients in association with the flow regime and the void-fraction distribution were evaluated. Time-average void-fraction was higher around upstream of a tube than that of downstream at bubbly flow condition for both bundles. Under intermittent flow condition, time-average void fraction at the maximum gap were higher than that around the other points in both tube bundles. For in-line tube bundle, enhancement of the heat transfer clearly appeared between ±90 to 180°. For staggered tube bundle, the heat transfer increased all over the pipe.

Restriction on water consumption is becoming an increasing problem for the power generation industry. As an alternative both to once-through cooling and to surface condenser/wet-cooling tower combination, utility companies and equipment manufacturers are considering, and even implementing, air-cooled condenser (ACC). However, the industry is quite reluctant to switch over to ACC for three important reasons: (a) lower power output, (b) higher capital cost, and (c) larger physical foot-print, all because of the same reason — it is not as efficient to transfer heat from condensing steam to air as it is to transfer to water. In other words, overall thermal resistance from condensing steam to the ambient air is significantly higher than to cooling water. To get a clear and full understanding of the heat transfer process occur in air-cooling condenser, Detailed mathematical equations were derived to model the heat transfer process through the fined-tubes of the ACC. The total thermal resistance model was analyzed and investigated to identify the design components with highest affect in the process. The paper proposes a viable cooling system based on novel heat pipe technology which addresses these problems. This technology employs boiling as the means to store and transfer heat energy. A detailed mathematical set of equations was derived to model the heat pipe thermal resistance. A comparison of the heat transfer performances of the ACC technology and the proposed method is presented. The proposed cooling system suggests a solution for each of the three components of the thermal resistance, the super-hydrophobic coating of the steam ducts internal surfaces increased the condensing heat transfer rate by an order of magnitude, the proposed design of the heat pipes improved the external heat transfer, and the installation mechanism improves the fin efficiency by eliminating the contact resistance between steam duct and the heat pipe.

This paper presents experimental investigations of the effect of scheme exit height and double jet injection on the film cooling performance of a Micro-Tangential-Jet (MTJ) scheme on the suction side of a gas turbine vane using the transient Thermochromic Liquid Crystal (TLC) technique. In part I of the present paper the investigations over the pressure side are presented. The MTJ scheme is a micro-shaped scheme designed so that the micro-sized secondary jet is supplied tangentially to the vane surface. In order to investigate the effect of scheme exit height, one row of the MTJ scheme with exit height of 1.5 hole diameters was investigated and compared with the case of 1.0 hole diameter scheme exit height. Meanwhile, to investigate the effect of double injection, one row of the MTJ scheme in staggered arrangement with one row of fan-shaped scheme was investigated. The investigations were conducted at a blowing ratio, calculated based on the scheme exit area, ranging from 0.25 to 0.625. The average density ratio during the investigations was 0.93, and the Reynolds Number was 1.4E+5, based on the free stream velocity and the main duct hydraulic diameter. The pitch to diameter ratio of the cooling holes is 6.5, and the turbulence intensity during all investigations was 8.5%. The increase in the MTJ scheme exit height did not result in significant change in the Mach number distribution. Moreover, increasing the scheme exit height resulted in enhanced effectiveness performance. The enhanced effectiveness was accompanied with Heat Transfer Coefficient (HTC) ratio augmentation as well. As a result, a reduction in the Net Heat Flux Reduction (NHFR) accompanied increasing the scheme exit height from 1.0 to 1.5 hole diameters. Besides, adding a row of shaped schemes in front of the MTJ scheme result in significant effectiveness reduction, compared to the case of single row injection. The latter was attributed to the presence of the shaped scheme inclination angle that result in enhanced secondary stream loss due to the perpendicular momentum component to the vane surface accompanying the shaped scheme secondary jet.

In power plant locations with adequate supply of cooling water the steam from the steam turbine is condensed in a water cooled condenser. In most instances circulating water from the cooling tower is used to condense the turbine exhaust steam. In other instances once through cooling is deployed wherein water from a lake, river or sea is used to condense the turbine exhaust steam. In water challenged locations or locations where wet cooling cannot be deployed due to permitting or regulatory issues, the steam from the steam turbine is condensed in an air cooled condenser (ACC) wherein ambient air is used to cool and condense the turbine exhaust steam. In a combined cycle plant, during normal operation, the water or air cooled condenser condenses the turbine exhaust steam. During bypass operation, when the steam turbine is out of service, the high-pressure steam from the HRSG is attemperated in a pressure reducing/desuperheating (PRD) valve and then admitted into the water cooled or air cooled condenser. The bypass steam flow is substantially higher than the design turbine exhaust steam flow and the duration of bypass operation can vary from a few hours to several weeks. The requirements for admission of bypass steam into a water cooled condenser are substantially different from that for an air cooled condenser. In a water cooled condenser the bypass steam is admitted in the steam dome. The bypass steam as well as the turbine exhaust steam is condensed outside the tubes. In an air cooled condenser the bypass steam is admitted in the large diameter steam duct. The bypass, as well as the turbine exhaust steam (normal operation), is condensed inside the tubes. There are similarities and differences in the requirements for admission of bypass steam into a water cooled and air cooled condenser. The differences must be identified and addressed to ensure safe and reliable performance of the condenser.

This study examines the upgrade of two forward-curved centrifugal induced draft fans, to support fuel blends with greater fractions of PRB coal for a 160 MWe generating unit. After a post installation event, an audible periodic low frequency vibration in the breeching was noticed at loads ranging from 75–95 MWe. A detailed investigation was conducted which included fluid dynamic and vibration analyses of the fan and system, as well as an assessment of the fan and motor performance characteristics. Results of the analyses revealed system resistances which generated operating points in the stall region on the fan performance curve. Non-uniform fan inlet flow distributions were characterized by axial and transverse distortion parameters. Data showed relatively high transverse distortion parameters over the affected load range with the maximum of 20.5% distortion occurring at 95 MWe; with a corresponding breeching vibration frequency approximately four-thirds shaft speed. Based on the data obtained and observed system behavior, it was determined the phenomenon responsible for the flow-induced vibration was the onset of rotating stall. The magnitude of the pressure pulses associated with this low frequency vibration is capable of causing fatigue damage to large ductwork and producing unwanted acoustic emissions. In light of the large number of similar conversions performed throughout industry and increases in partial-load operation, the accurate diagnosis of such phenomenon is vital for reliable plant operations. This work summarizes an effective and practical methodology for making such evaluations, while addressing issues of fan performance and system effects.

Primary air flow is supplied to the wind box of a 300 MW CFB boiler by means of three primary air ducts connected to a common plenum. A flow rate measurement is performed in each duct using an Annubar flow meter. Due to the tight configuration of the piping and the associated turbulence, the measured flows in the three ducts were not consistent, resulting in improper air flow distribution in the boiler. A primary air duct flow study was performed in an effort to improve measurement accuracy, which will lead to improved combustion efficiency and low load cycling by allowing precision air flow control in the furnace. The objective of this project was to employ a 1/10 th scale model test to determine the best method to improve the flow upstream of each Annubar flow meter. Tests were conducted with room temperature air at several flow rates generated by a centrifugal fan. Reynolds number independence was achieved in the tests. Appropriate dimensionless Grashof and Prandtl number scaling was used to extrapolate the scale model tests to the high temperature conditions prevalent in the unit. Flow visualization and measurements using a five-hole directional velocity probe were performed. It was determined that mounting 50% open area screens in the primary air duct of the scale model had the effect of significantly reducing both yaw and pitch angles across the Annubar measurement plane. A complimentary benefit was that the velocity profiles in the flow direction were notably flattened by the addition of the screens. Furthermore the performance of the Annubar flow meters could be improved if the measurement plane was moved further upstream of the opposed blade flow control damper.

Large hydro generators convert the mechanical energy of water turbines into electrical energy. This process is not free of heat losses which have to be dissipated from the machine. For this, different ventilation methods can be applied for an air cooled hydro generator. These methods have not changed very much in the last decades, but there has been a strong enhancement of the calculation and design approaches. State of the art computation methods are thermal and flow networks in combination with 3-dimensional computational fluid dynamics (CFD). The focus of this paper is a CFD analysis of the end winding region as basis for development of correlations between the convective wall heat transfer coefficient (WHTC) and speed and flow rate parameters. These correlations are used as boundary conditions for thermal networks. Furthermore there is also a focus on the influence and sensitivity of the numerical settings on the correlations. This work deals with a reduced numerical model which is designed to calculate a hydro generator fast and accurately by using a steady-state simulation with the mixing plane method. The mixing plane approach is predestined for this kind of design. Considering only one slot section of the end winding bars and stator ducts, the advantages of the stage model can take its full effect. The main advantages are the use of large pitch ratios, periodicities in circumferential direction and the averaging of the fluxes on bands.

The elimination of severe power excursion with significant mechanical-energy release during Core Disruptive Accidents (CDAs) is a key issue for the enhanced safety of Sodium-cooled Fast Reactors (SFRs). In order to prevent the formation of a large-scale molten fuel pool within a reactor core, which is one of factors leading to the severe power excursion during CDAs, Japan Atomic Energy Agency (JAEA) is studying the introduction of Fuel Assembly with Inner Duct Structure (FAIDUS). In the current reference design for FAIDUS, the top end of the inner duct is open whereas the bottom end of the inner duct is closed, and therefore it is expected that the molten fuel will be discharged from a reactor core towards an upper sodium plenum through the inner duct. The objective of the present study is to clarify the fundamental mechanism for upward fuel discharge through the inner duct structure in FAIDUS, and thereby to confirm the effectiveness of FAIDUS. In the previous paper, the possibility of upward discharge of a high-density melt driven by coolant vapor was confirmed by visual observation in the JAEA’s out-of-pile experiment, in which molten Wood’s metal (density at the room temperature: 8700 kg/m3, melting point: 352 K) simulating the molten fuel was injected into a coolant channel (equivalent inner diameter: 30 mm, total height: 2 m, fluid content: water) simulating the inner duct structure. In this paper, the mechanism of upward discharge of a high-density melt driven by coolant vapor pressure and/or flow in this experiment is discussed in terms of the application to reactor conditions. Through this discussion, the following mechanisms were clarified. 1) Coolant vapor pressure is built up within the coolant channel after the melt injection. The magnitude of the pressure buildup becomes larger with increase of melt-enthalpy-injection rate which is defined by the product of melt-mass-injection rate into the coolant channel and melt specific enthalpy. 2) Following the pressure buildup, the melt is discharged upward being driven by the coolant vapor flow directing towards the top opening end of the coolant channel. The upward discharge mass rate becomes higher with the increase of the magnitude of the pressure buildup and therefore melt-enthalpy-injection rate. From these experimental knowledge, it was suggested that the coolant pressure buildup could act as one of the driving force for the upward discharge of a high-density melt through the inner duct structure in FAIDUS under reactor conditions with higher melt-enthalpy-injection rate than the current experimental condition.

As for the turbulent two-phase flow in the non-circular duct, the flow could show an anisotropic turbulence feature in liquid phase. In this study, the air-water bubbly turbulent upward flow experiment in the large square duct with the inside cross-section of 136mm×136mm has been conducted. Since the bubble size is very important for air-water bubbly flows, the bubble generating method was improved to get more uniform bubble size. After confirming the flow symmetry in the measuring cross-section, the distributions of local void fraction, bubble frequency and primary liquid velocity were measured by a hot-film anemometry, and the bubble behaviors were also investigated by using the high-speed video camera. The results show that the bubbles tend to accumulate to the wall region, where the liquid primary velocity shows the maximum especially at the corner.

In the present paper, the inflow phenomenon in the near-field of a buoyant jet issuing from a square duct is studied by using scanning LIF and scanning PIV measurements. The scanning LIF visualization allows an insight into the critical condition of the inflow phenomenon in a wide range of Froude number and Reynolds number. While, the scanning PIV allows the quantitative information on the inflow rate through the duct exit. The experimental result shows that the critical Froude number increases with an increase in Reynolds number in the duct exit up to Reynolds number 2,000, though it is weakened at higher Reynolds number. The examination of the inflow rate indicates that the large magnitude of the inflow rate occurs in the lower Froude number and Reynolds number.

For nuclear power plant life extension projects, it may be convenient and in some instances necessary to locate safety-related steel ducts and pipes outside of the main structures, exposing them to extreme environmental loads such as tornado missile impact. Examples of such applications include emergency firewater lines and Control Room vent ducts. The design of a tornado-impacted duct or pipe system requires an estimate of its dynamic response and an establishment of damage limits. These considerations are complicated by the system geometric and material nonlinearities and the local triaxiality effects on the response ductility limit. Simple, but acceptable accurate techniques for comprehensive evaluation of steel ducts under impact loads have not been established. This study presents simplified evaluation techniques for a steel duct/pipe under a heavy impact load, using fundamental concepts. The approach presented could be utilized to evaluate steel ducts/pipes against not only tornado missile impact loadings, but other types of transient loads as well. Both local and global responses of duct/pipe lines under missile impacts are evaluated. Applied impulse loadings for various types of tornado missiles are first established. A non-linear pseudo-static finite element analysis is performed in lieu of a more complicated dynamic analysis. The result is adopted for evaluation of the local ductility of ducts and pipes by using triaxial strain criteria. Global ductility and global shear checks are performed based on inelastic single-degree-of-freedom analysis methods. Pipe line design diameters and thicknesses are then determined based on the local ductility, global ductility and global shear evaluations. Accuracy of the non-linear pseudostatic analysis is discussed and a practical example using the proposed methodology is presented.

During the startup of a new fossil power plant, a high level of fly ash accumulation (higher than predicted) was encountered in the flue gas ducting upstream of a fluidized bed scrubber. The level of fly ash accumulation made it necessary to manually withdraw fly ash using a vacuum truck after short periods of operation, at less than 80% maximum continuous rating (MCR). This paper presents a simple method for rapid assessment of fly ash accumulation in flue gas ducts using steady state single phase Computational Fluid Dynamics (CFD) simulation of flue gas flow. The propensity for fly ash accumulation in a duct is predicted using calculated wall shear stresses from CFD coupled with estimates for the critical shear stresses required for mobilization of settled solids. Critical values for the mobilization stresses are determined from the Shields relations for incipient motion of particles in a packed bed with given fly ash particle size and density as inputs. Solids accumulation is possible where the wall shear stress magnitude is less than the critical shear stress for mobilization calculated from the Shields relations. Predictions of incipient fly ash accumulation based on the coupled CFD/Shields relations model correlate well with plant startup field observations. Fly ash accumulation was not observed in a related physical scale model test. A separate CFD/Shields relation analysis of the scale model physical tests show that the wall shear stresses in the scale model are several times larger than the critical value required for the mobilization of the fly ash simulant. This study demonstrates that a simple steady state, single phase CFD analysis of flue gas flow can be used to rapidly identify and address fly ash accumulation concerns in flue gas duct designs. This approach is much simpler and computationally inexpensive compared to a transient Eulerian multiphase simulation of particle laden flow involving handling the dense phase in regions of ash accumulation. Further, this study shows that physical model tests will be accurate for predicting fly ash accumulation, only if, the scaling maintains the proper ratio of wall shear stress to critical remobilization stress.

Since its publication in 1996, ASME PTC 46 Performance Test Code on Overall Plant Performance has established itself as the premier test code for conducting overall plant performance within the power industry, especially for combined cycle power plants. The current text within ASME PTC 46, which is currently under revision by the ASME PTC 46 Committee, describes in Section 5.3.4 Specified Measured Net Power that “This test is conducted for a combined cycle power plant with duct firing or other form of power augmentation, such as steam or water injection when used for that purpose.” Further, the only example problem for a combined cycle with duct firing is provided in Appendix B of the code utilizing the Specified Measured Net Power Test Method. Though the text and example are correctly presented within the code, it resulted in misinterpretation within the industry that the only correct way to test a combined cycle plant with duct firing was to conduct a Specified Measured Net Power Test. Though the Specified Measured Net Power Test Method is an acceptable and accurate method in determining the performance of a combined cycle plant with duct firing in operation, it lends to being inflexible to the weather conditions for the plant operation. When the weather is too cold, the exhaust energy from the combustion turbines may be at such a magnitude as to not allow the duct burners to be fired due to limitations within the heat recovery steam generator and steam turbine systems to take the load, thus limiting the plant testing to take place when the weather is warm enough to allow the plant to be operated with duct firing. The opposite condition can also exist where the ambient conditions are too hot so that the duct burner capacity is unable to achieve the specified measured net power allowing the test to be conducted. The limitations stated herein are the reasons that an alternative approach with more flexibility is necessary. This paper will present an alternative approach referred to as the Fixed Duct Burner Heat Input Test Method to testing combined cycle plants where the duct burner heat input (Fuel Flow) is held fixed while the plant net power and heat rate are left to float with ambient conditions. Corrections for both power and heat rate will be developed for ambient conditions per ASME PTC 46 guidelines. This paper will further present a comparison between the Specified Measured Net Power Test Method and the Fixed Duct Burner Heat Input Test Method in the areas of the flexibility of the methods for various ambient conditions, and the method uncertainty associated with each method’s ability to correct to reference conditions.

Simple cycle power plants are frequently utilized as peaking power plants which generate electricity typically during a high demand. To comply with environmental standards simple cycle power plants are equipped with emission control catalysts reducing emissions of nitrogen oxides, carbon monoxide and other pollutants. In some applications ambient air (so called tempering air) is injected into the exhaust duct to control temperature of the flue gas prior to entering environmental catalysts. Such catalytic treatment of pollutants present in the flue gas requires exhaust systems with substantial footprints to accommodate the emission control catalysts and tempering air injection systems. This paper discusses a new compact exhaust system and efficient arrangement of the tempering air system for simple cycle power plants. The proposed system includes transitioning hot exhaust flue gas into pre-oxidation section of the exhaust system, passing hot exhaust gas through the oxidation catalyst for the CO emissions control, injecting tempering air stream into the post-oxidation section of the exhaust system, and passing cooled flue gas through the reduction catalyst for the NO x emissions control. The resultant benefit of this newly designed process is a more effective use of catalysts, a smaller exhaust footprint of equipment and a lower capital cost to the end user.

As demands for increased operational flexibility are placed on heavy-duty gas turbines, the usage of inlet air compressor bleed heating devices has been expanded to increase the emissions-compliant operating envelope. To ensure that these devices maintain acceptable flow-field characteristics at the compressor face, a method to accurately determine the flow field characteristics at the compressor face is required. In the past, Computational Fluid Dynamics (CFD) analysis has been used to predict flow field characteristics at the compressor face. As a means by which to make a comparison between analytical predictions and empirically determined characteristics, a scale model direct measurement arrangement was devised and tested. Given the high flow speed and complex geometry in the vicinity of the compressor face, accurate in-situ measurement of the flow profile presents many challenges. The measurement arrangement must provide sufficient data density such that flow-field gradients are fully captured, while simultaneously maintaining a minimum level of obstruction attributable to the sensors. One of the end goals is to ensure that the measured flow is representative of the system in its final configuration. Measurement systems of sufficiently small size to minimally influence the flow, but of sufficiently high accuracy must be employed. Advances in the design and usage of a measurement system to empirically determine the flow field characteristics in the inlet air system of a heavy-duty industrial gas turbine are presented. This system was used to characterize a number of competing inlet air compressor bleed heating systems. The results of this characterization are compared qualitatively and quantitatively, with a specific focus on the technology of the measurement system and measurement techniques.

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