bluuebunny/crossref_metadata_2025 huggingface dataset:
HRSGs for Combined Cycle Plants: Design Considerations and Life Consumption Estimation Using Dynamic Software
Authors: Sun Suichu , Pasha Akber
Published: March 2012

Today’s Heat Recovery Steam Generators are exposed to more severe operation than just running at a base load. The deregulation of the electric generation industry has resulted in an increase of merchant plants that are required to supply electrical power to the grid as needed and when needed. The plants will be coming on line with minimal notice. This puts a strain on the HRSG and unless properly designed and operated to withstand the quick start-ups and shut downs, the integrity will be compromised. Fast starts result in achieving full load revenues much sooner including the cost of high start-up emission reduction. Basic definition of a fast start is to have about 66% of the plant power available in 30–50 minutes and full plant power available in 60–75 minutes with a hot or warm steam turbine. This paper describes various mechanisms which affect the integrity of the boilers. These include the damage mechanisms, their effect on various parts and how to control them. The causes and the end results of these damage mechanisms are not the same for all components of the boiler. This analysis results in deciding which components need further review of the critical components. Detailed analysis of the critical components under the specified operating conditions can lead the nature and origin of the forces causing adverse impact on the life of the component. Once the failure mechanism is determined, means to eliminate or reduce the impact can be developed. This paper also describes the Life Consumption Estimation software which uses the data directly retrieved from the plant data acquisition system, thus eliminating the tedious task of manual data transmission. Based on the correlations developed by Vogt Power International Inc. (VPI) with the detailed dynamic simulation, Finite Element Analysis and various codes the component consumption is estimated and displayed with the calculated replacement and start-up costs on a continual basis. This gives the plant owners and operators an on line tool to gauge the economic benefits of the aggressive operations in real time.
Good News About Gas Turbine Standards
Authors: Putnam Robert , Osolsobe George
Published: March 2012

Performance Test Codes (PTC) for gas turbines are about to experience a happy convergence of revisions to three principal documents. Several aspects of gas turbines are under consideration in ASME PTC 22 Gas Turbines, ASME PTC 36 Gas Turbine Installations Sound Emissions and ASME PTC 51 Gas Turbine Inlet Air Conditioning Equipment, all of which are in various stages of final development. These PTCs can be used to specify equipment and to perform verification testing to ensure conformance to performance requirements. This overview of the three PTCs will address the key concerns driving the development of the standards, the general issues addressed and the application and significance of uncertainties relevant to each.
HDPE Cooling Water Pipe for Power Generation
Authors: Zhou Z. Jimmy
Published: March 2012

Cooling water pipe systems are a critical part of a power generation plant. If the cooling water pipe fails, the whole plant may shut down. Due to its high tensile strength steel pipe has been used for cooling water pipe since the beginning of power generation. High density polyethylene (HDPE) has emerged as a reliable and sustainable replacement for steel pipe primarily due to its corrosion resistance. The Hazen-Williams C-factor of steel pipe decreases during the service period because of corrosion and buildup while HDPE pipe has a stable C-factor. The build up inside steel pipe reduces not only the C-factor but also the inside diameter. Steel pipe may fail in the ductile mode as a result of corrosion-related pipe strength reduction combined with the pressure surge related to the reduction of inside diameter. Ductile failure is not observed in the field for HDPE pipe. HDPE pipe is virtually maintenance-free while corrosion protection measures are used for steel pipe. HDPE pipe has advantage over metal pipe in total life cycle costs including material, installation, maintenance, and replacement costs. With these outstanding performance attributes, HDPE pipe has been used in power plants over the last 15 years to transport cooling water pipe for non-safety related applications. In November 2008, Ameren’s Callaway Nuclear Power Plant successfully completed the installation of a 36″ HDPE cooling water pipe system; the first safety related HDPE water pipe in North America for the ASME category 3 cooling pipe application. This safety related PE 4710 cooling water pipe has delivered exceptional performance since its installation.
Optimization of Waste Heat Recovery Power Generation System Applied in Ferroalloy Industry
Authors: Wang Yufeng , Zhao Shuai , Hui Shien , Zhao Qinxin , Zhou Qulan
Published: March 2012

During ferroalloy production, a large quantity of waste gas can be utilized to generate steam and electric power. In this paper, 4 detailed thermodynamic models of single-pressure (SP) and dual-pressure (DP) waste heat recovery power generation systems are presented, to analyze the impact of the steam pressure, steam temperature and pinch temperature difference on power generating capacity. By comparing the performance of typical systems, more reasonable thermodynamic models and their parameters are proposed. It is found that the power generation capacity of dual-pressure system is higher than that of the single-pressure system, but SP system is much simpler. Using superheated steam in deaerator reduces the efficiency of heat recovery power generation systems by 1.8%. The fluctuation of waste gas source affects the power generation greatly. It should be considered when more reasonable ranges for the main parameters are required. With the improvement of thermodynamic system and parameter optimization, the gross power is increased by 15% for SP system and 17% for DP system, corresponding to the steam parameters of 3.0MPa/400°C and 6.0MPa/400°C.
Experimental Study and Numerical Simulation on a Novel Structure of Dual Register Whirl Burner
Authors: Luo Rui , Zhou Qulan , Wang Huiqing , Li Na , Hui Shi’en , Zhao Qinxin
Published: March 2012

The key technology of furnace for utility boiler is the combustion organizing of burner. The whirl burners are gradually adopted in large-scale utility boiler. A new structure based on dual register whirl burner was proposed and studied by experiment and numerical simulation. From experiment work carried out on cold modeling test, we obtained axial velocity distribution, refluxing extent and turbulence with different spouts, swirl intensity, and blast air distribution. The flow fields were also calculated by computational fluid dynamic (CFD) simulations which accorded with experimental results. By both studies it was found that the new structure whirl burner has high turbulence near the spout and favorable reflowing for ignition and steady combustion. Air distribution controlling could adjust flow field for variable coal. Total refluxing extent variable was proposed to predict the refluxing ratio. The multi-blocks concentrator of pulverized coal was also studied. And favorable dense-lean particle separation was observed which is helpful to dense-lean combustion for low NOx emission.
Smart System for Disaster-Proof Community With Distributed Energy and IT Network
Authors: Kawana Masataka , Osakabe Masahiro , Mouri Kunihiko
Published: March 2012

Variety researches and developments have been performed in order to decrease the emission of carbon dioxides as known of major cause on global warming. The SMART study group has proposed a concept of the solution for the low carbon dioxides emission and the disaster-proof community cooperating with industries, academics and municipal offices. This concept is based on the distributed energy network as known as SMART grid technology proposed in 2004. The system consists of the micro-grid system with distributed energy and IT network securing the power supply apart from the power utility in case of emergency and disasters. The proposed SMART system has major three functions. The first is to provide the ability to use the renewable energy generated in the local community. The renewable energy is most expected one but the output is too fluctuating to use usually. The second is to provide the tools to cooperate with citizens. The advanced demand-side control can contribute to save the energy. The third is to prepare for the disaster as mentioned above.
Combustion Characteristics of a Dual Fuel Diesel Engine With Natural Gas (Influence of Cetane Number of Ignition Fuel)
Authors: Yoshimoto Yasufumi , Kinoshita Eiji
Published: March 2012

This paper investigates the performance, exhaust emissions, and combustion characteristics of a dual fuel diesel engine fueled by CNG (compressed natural gas) as the main fuel. The experiments used standard ignition fuels prepared by n-hexadecane and heptamethylnonane which are used to define the ignitability of diesel combustion, and focused on the effects of fuels with better ignitability than ordinary gas oil such as fuels with higher cetane numbers, 70 and 100. Compared with gas oil ignition, a standard ignition fuel with C.N. 100 showed shorter ignition delays, and lower NOx exhaust concentrations, and engine noise. The results also showed that regardless of ignition fuel, misfiring occurred when the CNG supply was above 75%. While the CNG ratio where misfiring occurs lowered somewhat with increasing C.N., the combustion stability (defined as the standard deviation in the cycle to cycle variation of IMEP divided by the mean value of IMEP) was little influenced. In summary, the results show that the influence of the ignitability on the engine performance and emission characteristics of the dual fuel operation is relatively small when the ignition fuel has C.N., and similar to or higher than ordinary gas oil.
A Cogeneration System for an Apartment Building Using Distributed Heat Storage Technology
Authors: Yamaguchi Hideki , Morita Hikaru , Asano Hitoshi , Hisazumi Yoshinori
Published: March 2012

In order to spread economically viable distributed generation systems for apartment buildings, it is essential to develop an efficient and low-cost heat supply system. We are developing a new cogeneration system (Neighboring CoGeneration system: NCG). The key concept of this system is to install a heat storage unit with a hot water supply and a room heating function at each household and to connect heat storage units by a single-loop hot water pipe. In this study, a simulator was developed to reproduce the dynamic performance of the NCG system that combined cogeneration with solar heat for 50 households, and the environmental load reduction effects of the system were evaluated on the condition that heat supply to all households was ensured. It showed that the gas engine system reduced the primary energy use by 18% in a year. Meanwhile, the SOFC system reduced the primary energy use by 29%.
Computationally Predicted Performance of Pulverised Coal Fired Boilers and Study of Ash Deposition Phenomenon
Authors: Tamura Masato , Uchida Masahiro , Oono Emi , Matsuzawa Yoshiaki , Kozaki Takahiro , Li He
Published: March 2012

Understanding of pulverised coal combustion performance including ash behaviour is very important to design optimum boiler furnaces. In the last decades, remarkable advance of computers and computational fluid dynamics (CFD) codes have been realised and plenty of numerical modelling has been applied. However total performance of pulverised coal fired boilers including burner geometries and ash deposition behaviours is still difficult to predict. There are the limitation of computer performance and unknown phenomenon of ash deposition. Therefore, the new method of modelling to perform the full size furnace simulation has been developed to materialise both reduction of calculation load and improvement in prediction accuracy. It is confirmed that this new technique can express the difference between varied burner conditions. Detailed coal ash deposition behaviours and heat absorption rate are currently unknown and were measured and analysed experimentally by using the horizontal cylindrical furnace with water cooled probes. The experiments gave the better understandings of ash deposition and inhibition of heat absorption and heat absorption model is proposed. Boiler furnace heat absorption with ash deposition will be calculated and ash deposition behaviour will be modelled.
Genetic Algorithm-Based Searching Method for Piping Path Routing in Coal-Fired Boiler Buildings
Authors: Kusumi Naohiro , Goldberg David E. , Ichinose Noriyuki
Published: March 2012

Power plant design using digital engineering based on 3-D computer-aided design has become a mainstream technology because of possessing higher speed and improvement in design accuracy. To take a coal-fired boiler building as an example, it has many complex structures with several million parts including the boiler itself, large fans, steel structures, and piping in varying sizes. Therefore, it is not easy to maintain integrity of the whole design throughout all the many engineering processes. We have developed a smart design system for coal-fired boiler buildings to solve the integrity problem. This system is capable of creating and allocating 3-D models automatically in accordance with various technical specifications and engineering rules. Lately, however, there has been a growing demand for more effectiveness of the developed system. We have begun to look into the feasibility of further improvements of the system function. The first point to note, when considering effectiveness, is the piping path routing process in the coal-fired boiler building. The quantity of piping is large, and it has a considerable impact on performance of the whole plant because hot steam is fed into the steam turbine and cold steam is taken from it through the piping. A considerable number of studies have been made on automatic searching methods of piping path routing. Although, the decision of piping path routing by using the Dynamic Programming method is most commonly, a previously decided routing becomes an interference object because of the single searching method. Therefore, basically, the later the order of the routing becomes, the longer the length of the routing becomes. To overcome this problem, in this paper we have proposed a new searching method based on the Genetic Algorithm (GA). The GA is a multipoint searching algorithm based on the mechanics of natural selection and natural genetics. Virtual prohibited cells are introduced into the proposed search method as a new idea. The virtual prohibited cells are located in a search space. The different paths are generated by avoiding the virtual prohibited cells while searching for the piping path routing. The optimum locations of the prohibited cells which are expressed in a genotype are obtained by using the GA in order to get a lot of paths independent of the order of the routing. The proposed method was evaluated using a simple searching problem. The results showed that many effective paths are generated by making the virtual prohibited cells.
A Numerical Simulation of Fuel Premixing for PCCI Combustion by Direct Injection
Authors: Kondo Tsuyoshi , Nakagawa Tsuguhiko
Published: March 2012

Diesel engine has some advantages that thermal efficiency is high and control response is fast. On the other hand, more particulate matter (PM) and nitrogen oxide (NOx) are contained in the exhaust gas of diesel engine. Premixed charge compression ignition (PCCI) combustion is proposed to reduce the PM and NOx. In the lean range of equivalent ratio, unburned fuel is left and in the rich range, PM and soot are generated. For the practical use of PCCI combustion, mixing fuel and air well is important under the low equivalent ratio of injection. In this study, the mixing characteristics of fuel and air in a cylinder were numerically evaluated. A numerical simulation was performed with general-purpose simulator. The fuel has been injected into the vertical direction of cylinder and injection angle has been defined as 0 degree. In order to express the collusion, impingement on the wall model, that defines behavior of a droplet impinged on the wall with the Weber number of a droplet, was applied. By the injection timing, standard deviation of local equivalent ratio at Top Dead Center (TDC) was plotted. In this study, Frequency of mixing in each cell statistically was observed to evaluate the fuel-air mixing degree. The authors have taken notice of the condition which can be reduced the amount of scatter in the distribution of local equivalent ratio.
Hydrogen Production by Bio-Fuel Steam Reforming at Low Reaction Temperature
Authors: Maeda Tsuyoshi , Shinoki Toshio , Funaki Jiro , Hirata Katsuya
Published: March 2012

The authors reveal the dominant chemical reactions and the optimum conditions, supposing the design of ethanol steam-reforming reactors. Specifically speaking, experiments are conducted for Cu/ZnO/Al2O3 catalyst, together with those for Ru/Al2O3 catalyst for reference. Using a household-use-scale reactor with well-controlled temperature distributions, the authors compare experimental results with chemical-equilibrium theories. It has revealed by Shinoki et al. (2011) that the Cu/ZnO/Al2O3 catalyst shows rather high performance with high hydrogen concentration CH2 at low values of reaction temperature TR. Because, the Cu/ZnO/Al2O3 catalyst promotes the ethanol-steam-reforming and water-gas-shift reactions, but does not promote the methanation reaction. So, in the present study, the authors reveal that the Ru/Al2O3 catalyst needs high TR > 770 K for better performance than the Cu/ZnO/Al2O3 catalyst, and that the Ru/Al2O3 catalyst shows lower performance at TR < 770 K. Then, the Ru/Al2O3 catalyst is considered to activate all the three reactions even at low TR. Furthermore, concerning the Cu/ZnO/Al2O3 catalyst, the authors reveal the influences of liquid-hourly space velocity LHSV upon concentrations such as CH2, CCO2, CCO and CCH4 and the influence of LHSV upon the ethanol conversion XC2H5OH, in a range of LHSV from 0.05 h−1 to 0.8 h−1, at S/C = 3.0 and TR = 520 K. And, the authors reveal the influences of the thermal profile upon CH2, CCO2, CCO, CCH4 and XC2H5OH, for several LHSV’s. To conclude, with well-controlled temperatures, the reformed gas can be close to the theory. In addition, the authors investigate the influences of S/C.
Development of Air Cooled Combustor for Mitsubishi G Class Gas Turbine
Authors: Tsukagoshi Keizo , Akamatsu Shinji , Sato Kenji , Tanaka Katsunori , Kishida Hiroaki , Nishida Koichi , Saitoh Keijiro
Published: March 2012

Mitsubishi Heavy Industries (MHI) pioneered the introduction of steam cooling technology for gas turbines with the introduction of the M501G in 1997. To date, 71 Mitsubishi G units have been sold making this series the largest steam cooled fleet in the market. The turbine inlet temperature (TIT) for this gas turbine is 1500 deg. C. The original M501G has been upgraded for air cooling applications. This upgraded version is called as M501GAC (G Air Cooled). The latest Dry Low NOx (DLN) and cooling technologies from existing F and G series were applied to the upgraded M501GAC. The new GAC combustor was installed in the in-house verification Combined Cycle Power Plant, called T-Point, and verification tests of the combustor were conducted from November 2008. The air cooled M501GAC combustor demonstrated less than 15ppm NOx operation, stable combustor dynamics at all load levels, and high combustor ignition reliability making it suitable for daily start and stop operation at T-Point. Also, oil firing capabilities was tested in May, 2010. Long term verification test is completed in fall 2010.
Effect of Surface Roughness and Micro-Grooves on Condensed Water Removal in Latent Heat Recovery Heat Exchanger
Authors: Kimoto Kenta , Asano Hitoshi , Sakurai Masafumi , Hamada Tetsuro , Hirotsu Makoto , Kimura Sakiko
Published: March 2012

Hot-water supply has high percentage of energy consumption in Japanese civilian sector. Gas water heaters are used in most cases. Therefore, improvement in thermal efficiency of a gas water heater is an important issue for energy saving. In order to improve thermal efficiency of a gas water heater, an additional heat exchanger is required for latent heat recovery from exhaust humid combustion. The purpose of this study is to develop a compact latent heat recovery heat exchanger with a simple configuration. It is necessary for compactness to reduce the gap between the heat transfer tubes. However, the narrow gap will cause stagnation of condensed water. In order to remove the condensed water from horizontal tube bank, three kinds of tubes with different surface treatments, polished tubes, unpolished tube, and smooth tube with circular micro-grooves, were examined. As the result, condensed water was easily removed by the groove with the 0.7mm depth, to avoid the formation of water bridges between tubes. The effect could lead to no deterioration in the heat transfer performance by decreasing the tube clearance to 1.0mm.
Low NOX Combustion of DME by Exhaust Gas Recirculation Under the High Pressure
Authors: Takeuchi Hiroaki , Tanikawa Tatsuro , Matsumoto Ryosuke , Ozawa Mamoru
Published: March 2012

This study focuses on the fundamental characteristics of DME (Dimethyl ether) combustion with exhaust gas recirculation EGR, aiming at development of the low NOx combustion technology of DME under the high pressure. EGR reduces the NOx emission by recirculating the exhaust gas into the combustion chamber to control the oxygen concentration and the combustion gas temperature. EGR at the high mixing ratio, however, may lead to unstable combustion of conventional fuels, methane or city gas. On the other hand, DME has high potential of applicability of EGR even at the high mixing ratio because of its high burning velocity and low ignition temperature. In this experiment, the oxygen concentration and the combustion air temperature were systematically regulated, so that the exhaust gas recirculation was simulated. The combustion test was conducted with laboratory-scale 8kW combustor. Initial air ratio λ was 1.5. At the atmospheric pressure, the exhaust gas recirculation can be applied to 54% of the EGR ratio. The NOx concentration reduces to 10ppm at 0%-O2, which corresponds to about 22% of NOx emission without EGR. However, the flame became unstable at 54% of the EGR ratio. By increasing the pressure in the combustion chamber, the NOx concentration increased the 84ppm at 0.3MPa-without EGR. The maximum EGR ratio can be applied to 59% under the pressure of 0.3MPa, wihch is almost the same with that at atmospheric pressure. The NOx emission in the exhaust gas decreases to 17ppm. The exhaust gas recirculation is effective to the low NOx combustion of DME at the high pressure.
Study of Multi-Stage Test Turbine and Numerical Calculation
Authors: Sun Qi , Kong Xianglin , Jiang Shengke , Zhong Gangyun , Shang Yu
Published: March 2012

To improve the aerodynamic performance of flow path for steam turbines, three-stage air turbine experimental test rig is designed and established at Dongfang Steam Turbine Co. Ltd. The experimental test rig is described at first including the wind regime system, controlling system, measurement system and experimental body. The hydraulic dynamometer and torquemeter are used to measure the output power of the experimental turbine stages. Advanced and accurate pressure and temperature measurement equipments and corresponding displacement device are utilized to obtain the aerodynamic parameters of interstage passage flow. The modeling three-stage turbines according to steam turbines are experimentally measured to obtain the aerodynamic performance and flow fields, as well as demonstrate the accurate and reliability of the air turbine experimental test rig. In addition, three-dimensional Reynolds-Averaged Navier-Stokes (RANS) and S-A one equation turbulent model is also used to obtain the flow characteristics of the experimental turbine stage at the measurement flow conditions. The repeatability of the establishment of air turbine experimental test rig is demonstrated according to two times measurements results. The developed three-stage air turbine experimental test rig can be able to support high reliability of the measurement and verification tool to obtain the aerodynamic performance and flow fields for steam turbines manufactured by Dongfang Steam Turbine Co. Ltd..
Numerical Investigations on Aerodynamic Performance of Nozzle Control Stage of a 600MW Steam Turbine Under Different Backing Pressure Conditions
Authors: Zhong Gangyun , Li Jun , Li Zhigang , Yan Xin , Wu Qilin
Published: March 2012

Partial admission aerodynamic performance of a nozzle control stage for a 600MW steam turbine was numerically investigated using the Reynolds-Averaged Navier-Stokes (RANS) solutions. Two inlet main steam pipe, four control valves, four nozzle groups including strengthening ribs and full stator blades, and full rotor blades were considered in the present computational domain. The partial admission with three control vales opening and the fourth control valve closed under five different backing pressures were calculated to analyze the aerodynamic efficiency and total pressure losses distributions. The maximum aerodynamic efficiency of the nozzle control stage was obtained at five different backing pressure operating conditions. The flow fields in the nozzle control stage at specified backing pressure with consideration of the partial admissions effects were also illustrated.
The Development and Prospects of Coal-Fired Power Conservation Technologies in China
Authors: Zhou Yigong
Published: March 2012

This paper analyzes the applications and prospects of supercritical/ultra-supercritical power generation technology, integrated coal gasification cycle combination (IGCC) power generation technology, double reheat supercritical power generation technology, large-scale air-cooled power generation technology and modern thermal power system integration and optimization technology in China’s coal-fired power conservation.
Reliability Prediction Methods and Application of Large Capacity Generating Units
Authors: Shi Jinyuan , Huang Gongwen , Wang Yong , Yang Yu
Published: March 2012

The mathematical model and the methodology of the reliability prediction of generating units are presented. Based on statistical analysis of operation reliability past data for generating units, statistical values of the repair factor and the mathematical model’s parameters of the repair factor are determined. According to plan repair outage days and the mathematical model for the repair factor of some generating unit, equivalent availability factor (EAF) of the generating unit can be predicted in future three years. The reliability prediction examples for sub-critical 300MW, supercritical 600MW and sub-critical 600MW fossil units are given together with reliability prediction results of 550MW hydro units and 984MW, 990MW nuclear units. The relative error’s range for equivalent availability factor prediction values of the generating units is between −1.48% and 2.69% which indicates that reliability prediction precision is higher. By using reliability prediction method, prediction values for the reliability indexes of generating units can be quantitatively calculated, which provides a basis for reliability objective management and optimization repair of generating units.
Study and Application of Two-Level Optimization of Coal Blending for Power Plant Based on On-Line Coal Identification
Authors: Xia Ji , Peng Peng , Zhang Cheng , Yang Tao , Chen Gang
Published: March 2012

In china, many thermal power plants have to burn blended coals forced by the complexity of coal type and market tension and transportation pressure of coal purchasing. As a engineering implementation method of coal blending, “different coals grinding in different mills and then mixed burning in the furnace” has many advantages such as low investment, easy to control milling system parameters and can be optimized online, etc, compared with traditional coal blending methods. But it is limited by the number of mills and cannot achieve high-precision ratio of blending. To remedy this shortcoming, a model of two-level optimization of coal blending for the thermal power plant with direct blowing pulverizing system was established in this paper. The tradional coal blending was regarded as first step of optimization. The secondary optimization was implemented by adjusting the outputs of different mills, then the blend was changed to accurate ratio. Furthermore, since the existence of coal bunker, it made a time lag from coal discharge to combustion, meanwhile, the real-time load was unpredictable and the coal utilization rate was inconsistent of each bunker. The three reasons make it uncertain of the current coal of bunker. To identify each coal in the mill(equivalent to bunker) correctly was the basis of achieving the second blending optimization. Therefore, a soft-sensing model of coal moisture based on the heat balance equation was used to take this work. At last, a intelligent coal blending system by the two-level optimization model was developed for a power plant and achieved good results.
Research on Combustion Characteristics of a Jet Flame With Penetration of Side Micro-Jets
Authors: Cao Yu-chun , Wang Zheng-wei
Published: March 2012

Nowadays as clean energy gas is being got more widely utilization in the industrial fields, such as the industrial boilers and kilns. How to improve the combustion performance, including the high efficiency and low pollution emission of the gas flame, is becoming the hot topic for the combustion researchers. In this paper, an innovative jet flame with side micro-jets has been proposed and its effects on the flame structure and its performance have also been investigated. Due to the changes of the initial combustion conditions, mixing and aerodynamics which results from the perturbation of the side micro-jets, such a lifted jet flame have different flame structure compared with the common premixed flame. Results show that use of the micro-jets can control, to a certain extent, the flame structure, including the flame length, lift-off distance and blow-off limit. With the same fuel and air flow rate, the flame length with the side micro-jets will decrease about 5%–40% as the air volume ratio a increases from 58%–76%. Compared with the common diffusion flame, such a jet flame demonstrates to be easier to be momentum-dominated flame. The flame length with 2 micro-jets is about 5% less than with 6 micro-jets under the same fuel and air flow rate. With the same α, the fewer number of the controlled jets lead to the flame with relatively shorter length, not easier to be blown off and higher NOx emission. With certain fuel flow rate, the critical air volume ratio is largest for the flame with 3 micro-jets, which is more difficult to be blown off than the cases with 2, 4 or 6 micro-jets.
Performance Deterioration Mechanism Analysis of Natural Draft Cooling Towers Under Crosswind Conditions
Authors: Sun Feng-zhong , Zhao Yuan-bin , Gao Ming , Chen You-liang , Shi Yue-tao
Published: March 2012

Based on the developed three-dimensional computation model of natural draft wet cooling towers, the effect of crosswind on circumferential distribution of air radial pressure gradient and velocity at tower air inlet was studied, and the effect of crosswind on total air inflow rate, transverse mass flow rate, vertical mass flow rate and water temperature drops of the three zones (i.e. spray zone, filling zone and rain zone) were also analyzed. Analysis of crosswind effect on air flow field in heat and mass transfer zone indicates that the induced longitudinal eddy causes reduction of effective ventilation area in filling zone. Results showed that crosswind destroys the uniform air inflow, reducing the total air inflow mass rate and the effective ventilation area of filling zone, resulting in cooling performance deterioration of natural draft wet cooling towers.
Application Analysis on the Bias and Air Staged Combustion Technology in the Opposed Firing Boiler
Authors: Liu Tai-sheng
Published: March 2012

The bias combustion technology has been widely used in the swirling burner. Take the distribution of the pulverized-coal concentration at the primary air outlet as the division principle, there are three kinds of bias combustion models: radial model with inside dense and outside lean, radial model with outside dense and inside lean, and circumferential model. Considering stable ignition and low NOx emission, at the phase of the pulverized-coal ignition, the dense pulverized-coal flow should be heated by the high temperature flue gas intensively and quickly to ensure the coal’s timely ignition and form an In-flame NOx reduction zone for low NOx emission. Hence the bias combustion technology should be in accordance with the recirculation zone. So the radial bias model with inside dense and outside lean suits to central recirculation zone while radial bias model with outside dense and inside lean suits to annular recirculation zone. The circumferential bias model suits to both recirculation zones. Furthermore, appropriate measures should be taken on the burner’s arrangement and furnace’s design to prevent the obvious increase of slagging problem and unburned carbon in fly ash when using bias and air staged combustion technology.
Development of Oxy-Fuel IGCC System With CO2 Recirculation for CO2 Capture: Experimental Examination on Effect of Gasification Reaction Promotion by CO2 Enriched Using Bench Scale Gasifier Facility
Authors: Kidoguchi Kazuhiro , Hara Saburo , Oki Yuso , Kajitani Shiro , Umemoto Satoshi , Inumaru Jun
Published: March 2012

To cope with global warming problem, utility companies are required to reduce CO2 emission from pulverized coal fired power plants. Japanese utility companies are advancing various measures to improve plant thermal efficiency and to promote utilization of biomass as a fuel. In Europe and America, CO2 capture and storage (CCS) technology is regarded as one effective approach, and various demonstration projects are planned all over the world. However, the introduction of conventional CO2 capture system to power station causes a decrease in the plant thermal efficiency and an increase in the power generating cost. In this reason, it is necessary to develop a new power generating system with high thermal efficiency. Therefore, Central Research Institute of Electric Power Industry (CRIEPI) proposed an innovative integrated coal gasification combined cycle power generating system (IGCC) with CO2 capture whose plant thermal efficiency is very high, and is working on the research and development of the new system. This is a system to combine a new oxygen-CO2 blown coal gasifier in that captured CO2 is used with the closed gas turbine in which coal gas from the gasifier is burned with the gas mixed oxygen and recycled exhaust CO2. The system has the following features. The gasification performances improve greatly. The processes of concentrating and separating CO2 are unnecessary. It is estimated that the carbon conversion efficiency (CCE) and the cold gas efficiency (CGE) in oxygen-CO2 blown gasifier improve more than conventional oxygen blown gasifiers by the effect of the gasification reaction promotion of CO2 by gasifying coal with oxygen and CO2. As a result, the gasifier and the char recycling system can make to compact, and the equipment cost can be reduced. This paper reports on examination of CO2 promotion effect on the gasification performances by gasification test using a bench scale gasifier facility.
Development of 60Hz Titanium 48-Inch Last Stage Blade for Steam Turbine
Authors: Murata Yoriharu , Shibukawa Naoki , Murakami Itaru , Kaneko Joji , Okuno Kenichi
Published: March 2012

The titanium 48-inch last stage blade that has world’s largest class exhaust annulus area and tip speed for 60Hz steam turbines has been developed. Concept of this blade is to achieve high performance and compact design of steam turbine for 1000MW thermal power plant and 300MW combined cycle plant. In the design of this blade, the optimization design has been done by using the recent analysis technologies, three dimensional CFD in aerodynamic design and FEA in mechanical design. The blade has curved axial fir-tree dovetail, snubber cover both at the tip and at the mid-span. To achieve superior vibration characteristics, continuously coupled structure was adopted for blade connection. To confirm the validity of design, first, sub-scale model blades were provided and tested in model steam turbine test facilities. Second, one row of actual size blades were assembled on the wheel of test rotor and were exposed rotating vibration test in a wheel box. Finally, these blades were tested at actual steam conditions in a full scale steam turbine test facility. In this paper, aerodynamic and mechanical design features will be introduced, and the test results of both sub-scale and actual size blades under real steam turbine operating conditions will be presented.
Use of On-Board Hand Brake Monitoring to Prevent Freight Car Wheel Damage and Improve Maintenance and Safety
Authors: Lonsdale Cameron , Wilson Brent
Published: March 2012

This paper discusses the benefits of using on-board hand brake sensors to determine whether a freight car hand brake is applied or released in service. Unreleased hand brakes are a significant source of wheel tread damage, which can lead to wheel removals, and in extreme cases can cause damage and derailments. Also, hand brake-related accidents are a significant cause of North American railroad accidents. Wheel tread damage and wayside wheel impact load detectors (WILD) are reviewed, along with AAR why made codes for wheel removals. Wheel failures and other wheel impact associated damage are discussed, along with operational considerations for hand brakes. Further, on-board sensors in general, and hand brake sensors in particular, are described in detail and service data from monitored cars is presented. Additionally, possible safety and operational improvements related to use of hand brake sensors are discussed, along with comments on the use of sensors to assist with proactive maintenance of freight cars.
A Dynamic Wheel/Rail Interaction Model Based on an Euler-Bernoulli Beam Rail Model
Authors: Hopkins Brad M. , Taheri Saied
Published: March 2012

Early detection of rail defects is necessary for preventing derailments and costly damage to the train and railway infrastructure. A rail surface flaw can quickly go from a small fracture to a broken rail after only a few train cars have passed over it. Rail defect detection is typically performed by using an instrumented car or a separate railway monitoring vehicle. Such systems can either be costly or time consuming to implement. This paper presents a dynamic wheel/rail interaction model for generating training data for a defect detection algorithm. The defect detection algorithm works with an onboard data acquisition system and sensor set consisting of accelerometers mounted to the bogie side frame. Side frame vertical acceleration signatures are analyzed by the algorithm to detect defects ranging from small surface fractures to rail breaks with complete rail separation. Proper training of the defect detection algorithm requires a large data set. This data set should consist of a wide range of train operating conditions and defect characteristics. Operating conditions of interest include various forward speeds and payloads, and defect characteristics of interest include rail fracture and break geometric parameters. To generate this training data, a dynamic wheel/rail interaction model was developed that relates crack/break geometry to the side frame vertical acceleration signature. The model was generated by treating the rail as an Euler-Bernoulli beam with appropriate boundary conditions and the pad-tie-ballast systems as discrete, evenly spaced lumped parameter forcing inputs into the rail system. The pad and ballast were each separately modeled as a non-linear spring and damper in parallel, and the sleeper was treated as a mass fixed between the spring and damper of the pad and ballast. The model was validated by comparing the simulated vertical acceleration response to actual bogie side frame vertical acceleration data.
Fretting Fatigue of Axles
Authors: Stone Daniel H.
Published: March 2012

The effect of surface damage by fretting corrosion pits under the backing ring or wheel seat will provide stress risers that will serve as crack initiation sites for fatigue crack initiation. Approximately one-half of North American axle failures are initiated by fretting. Both fretting under the backing ring and fretting in the wheel seat are reviewed.
Train Braking Distance Estimation Under Different Operating Conditions
Authors: Ahmad Husain , Ahmadian Mehdi
Published: March 2012

One of the critical factors in Positive Train Control (PTC) is accurately estimating the train braking distance under different conditions. Accurate estimation of the braking distance will allow the trains to be spaced closer together, with reasonable confidence that they will stop without causing a collision. This study will develop a dynamic model of a train consist that includes three railcars for performing a parametric study to evaluate how various elements will affect the train stopping distance, from an initial speed. Parameters that can be varied in the model include, initial train speed, railcar weight, wheel-rail interface condition, and dynamic braking force. Other parameters are included in the model such as aerodynamic drag forces and air brake forces. The model is based on a multibody formulation of the railcars, trucks (bogies), and suspensions. The paper will include the derivation of the mathematical model and the results of a numerical study in Matlab. The results indicate that the railcars’ weight and initial speed play a significant role in the stopping distance and the time required to stop the train. Our future work will include using this model for closed-loop control of the dynamic braking forces, such that the train braking distance and time to stop can be minimized, under various wheel-rail dynamic conditions.
Assessment of Fire Hazards and Mitigation Methods in Locomotive Fuel Tanks
Authors: Parida Basant K. , Carter James , Zaouk Abdullatif K. , Punwani John
Published: March 2012

Diesel fuel carriage in locomotives, while safe in normal operational conditions, presents a potential hazard in the event of serious accident or derailment. Development of an effective mitigation method against this hazard requires an understanding of operational conditions that lead to fuel spill and fire. This paper describes a study of fire hazard stemming from rail accidents and potential approaches to mitigation. Data for the study was obtained from a large sample of National Transportation Safety Board (NTSB) investigation reports for accidents involving both freight and passenger locomotive accidents over a 10-year period. Approximately 25% of the events reviewed resulted in fuel release. In addition, of the events that resulted in fuel loss, a large majority (almost 70%) resulted in fire. Most cases with major fires led to loss of life and/or property, including destruction of multiple locomotives. Typical road locomotives carry 3,000–4,500 gallons of diesel fuel during normal operation. As the locomotive consumes fuel, large volumes are available for vapor generation within the tank. In a post-collision scenario, the vapor that vents to the atmosphere at temperatures close to flash point of the fuel presents a significant fire hazard. Further, flammable mists can be generated by the sprays that develop due to fuel leaks from the post-impact movement of a train. Previous laboratory tests on a scaled tank demonstrated that fire in a fuel-rich vapor can flash back inside the tank causing an explosion or a large fire. This paper also assesses potential technologies to prevent or mitigate fire hazards in locomotive fuel tanks. These include fuel tank leak prevention or reduction of outflow from breached fuel tanks, monitoring vapor concentration within fuel tanks, and limiting vapor concentrations inside tank to maintain levels below the Lower Explosive Limit (LEL). Potential benefits of the latter method include minimization of pollution from escaping vapor as well as partial recovery of reusable fuel from vapor.
Experimental Evaluation of Resistance to Motion of a Light Rail Vehicle
Authors: Otero Yugat Jesu´s , Alonso Portillo Igor
Published: March 2012

All railway vehicles running on a track have to overcome a resistance to motion. The resistance to motion is due to mechanical and electrical losses, as well as to aerodynamic drag. In order to evaluate this resistance, two different experimental methodologies can be used. The first one consists on a conventional method which takes into account the energy stored in rotating masses and the equivalent curving and grade resistance. The application of this method is based on a coasting test procedure done on a straight track without slope. The second methodology consists on the experimental acquisition of electrical signals in the traction power line and strain measurements at the traction links of the bogie-truck, with different speeds. The electrical signals allow obtaining the efficiencies of the equipments in the traction power line. Once the different efficiencies of the equipments in the traction power line are known, the power transmitted to each wheel can be determined and consequently the resistance to motion is calculated. This paper summarizes an experimental procedure based on both methodologies. The designed instrumentation uses voltage and current probes for the recording of electrical signals in the traction line, piezorresistive accelerometers in order to obtain the uncompensated and the longitudinal accelerations of the train, extensometric gauges in full bridge configuration for the acquisition of stresses at the traction links, and a gyroscope for the detection of curves along the track. Several tests have been done by means of the described methods in light rail vehicles. Also, the vehicles have been tested in order to evaluate the influence of the air conditioning and air intakes, the circulation in curves and the cooling of traction equipments in the resistance to motion. Through these experimental methods, a useful tool for the prediction and analysis of the resistance to motion is provided. Additionally, the results obtained by means of these methodologies permit to calculate the influence of different running conditions in the resistance to motion.
Wheel Rim Axial Residual Stress and a Proposed Mechanism for Vertical Split Rim Formation
Authors: Lonsdale Cameron , Oliver John
Published: March 2012

Railroad wheels are manufactured with beneficial residual compressive hoop stresses, which are imparted by rim quenching and tempering. Hoop and radial residual stresses for wheels have been studied in detail by various organizations over the years and are relatively well characterized. However axial residual stresses, in the orientation across the rim width from back rim face to front rim face, have not been extensively investigated. This paper describes a failure mode known as a vertical split rim (VSR) and describes efforts to measure the axial residual stresses in, 1) new wheels, 2) service worn wheels and 3) wheels that have failed from VSRs. Initial axial residual stress measurement efforts, using core drilling and x-ray diffraction from the tread surface, are briefly reviewed. Further more extensive work using x-ray diffraction to measure axial residual stress on radial wheel slices is described and data are presented, focusing on differences between the three wheel types. The concept of Axial Stress Amplification (ASA) is outlined, and the relationship of axial residual stress to VSRs is discussed. A proposed mechanism for VSR formation is described. Future work, with a goal of reducing or eliminating VSRs in service, is considered.