To reduce the emission of carbon dioxide, an increase of the role nuclear power plants and renewable energy power plants bear is predictable. Fossil fuelled power plants will have to correspond to fluctuation of electric demands with fewer composition ratios. To meet conditions that future fossil fuelled power plants will be expected to have, we have focused on oxygen blown semi-closed MCFC-GT hybrid system and attempted to construct a system that can maintain high efficiency on wide load rates. Two bypass lines that bypass MCFC anode and turbine were set. Net efficiency on rated output marked 65.4%. By dividing operation method into four depending on the load rate, the system was able to maintain an efficiency of over 58% (net thermal, HHV) on load rate 100-25% and the system was operable up to load rate of 3.2%. The carbon dioxides that are discharged from the plant will be easy to collect, for it was of high purity.

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This paper describes the relationship between fan performance and configuration factors such as flow inlet porosity of an electronic enclosure, or flow obstacles which imitate high-density packages and restricted flow area configurations for a development of a fan performance prediction model. We focus on an electronic enclosure or an obstacle in front of the fan individually as factors which have dominant effects to the fan. First, we installed an enclosure model in front of the test fan and measured its P-Q curves while operating it in an enclosure. Secondly, we installed a perforated plate in front of the fan as an obstacle and investigated the P-Q curve changes as affected by the position and distance between the adjacent area and the fan. When the perforated plate was located in front of the fan, the P-Q curves were adversely affected, and the flow rate was determined by the open area ratio in front of the fan.

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The unusual properties of supercritical water including density, ion dissociation product, dielectric constant and hydrogen bond were introduced. Furthermore, the basic law of corrosion and deposition on supercritical and ultra-supercritical units was revealed. With regard to supercritical and ultra-supercritical units, the deposition inside boiler tubes especially consists of magnetite which accumulated principally on inner surface in the front of economizer. Furthermore, with respect to vertical type water wall, magnetite deposition can also foul control orifices. It is predicted that adequate control of corrosion product transport to supercritical boilers is not achievable with AVT. Both AVT (R) and AVT (O) inevitably result in a significant increase in pressure drop through the furnace walls due to internal deposition, and hence increase in metal temperature and necessity for frequent chemical cleaning. To restrain flow-accelerated corrosion and magnetite deposition in supercritical and/or ultra-supercritical units, OT is doubtless the excellent feedwater treatment regime, and it should be adopted as soon as possible if the feedwater conditions once become acceptable.

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The films formed on boiler tube steels are investigated and the corrosion resistances of the films formed are evaluated in this work. Corrosion potential measurements are conducted in simulated AVT (All Volatile Treatment) waters at 308K for 100h on STB410 carbon steel, STBA24 low-alloy steel and SUS304 stainless steel, which are used as the boiler tube steels in thermal power plants. Four kinds of the simulated AVT waters, i.e., the base water and the waters added with chloride and sulfate ions, are used in the tests. After corrosion potential measurements the films formed on the steels are observed with SEM (Scanning Electronic Microscope) and are analyzed with XPS (X-ray Photoelectron Spectroscopy). Anodic polarization behaviors of the materials with the films formed are also investigated in the same test waters. In all of the test waters, STB410 steel exhibits base corrosion potentials, while STBA24 and SUS304 steels show nobler. It is found that the films formed on STB410 steel consist of Fe-oxides and the films formed on STBA24 and SUS304 steels contain stable Cr-oxides. In this work, it is confirmed that the STBA24 and SUS304 steels show better corrosion resistances to the anions such as chloride and sulfate ions in the simulated AVT waters at 308K by virtue of the passive films.

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In the current paper, the temperature conditions and furnace atmosphere of the boiler water-wall were simulated in the tube furnace where the pulverized coal (PC) is burned. The SA213-T22 steel widely used for the water-wall tube material of ultra-supercritical boiler was taken as the sample to conduct the corrosion experiment, and the electron scanning microscope SEM and X-ray energy spectrometer (EDS) were used to make the analysis of the corroded sample and to investigate the impact of the factors like temperature, corrosion atmosphere etc. on high-temperature corrosion. The results show that in the corroded sample, the sulfur content increases remarkably with the drop of the oxygen concentration in the flue gas, but it is not related greatly to the temperature. However, the impact of temperature on the structure of the corroded material is conspicuous. The oxides on the surface of the corroded sample are mainly Fe_3O_4 and Fe_2O_3. The higher the temperature and the ambient oxygen concentration, the thicker the oxide layer.

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1000MWe capacity supercritical utility units employ 2950 t/h tangential-fired boiler, which uses the low NOx concentric firing system (LNCFS) and the deep air staged technology for reduce the NOx emission. The large capacity boiler uses eight burners at the same level, located at corner and the middle of the wall, which form the double fire balls in the furnace. In this work, the flow fields in the furnace were obtained by measuring the air velocity in the model furnace with over fire air and concentric firing system, the diameter of the air circle is also measured.

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2950 t/h tangential-fired boiler is manufactured for the 1000MWe capacity super critical utility units, which employs the low NOx concentric firing system (LNCFS) and the deep air staged technology for reduce the NOx emission. In this work, the comparison of two schemes of separated over-fire-air employment was conducted using the numerical simulation method, the flow field, temperature distribution, oxygen concentration in the furnace and NOx emission were obtained. The numerical results showed that the combustion system employed in the 2950 t/h tangential-fired boiler had good performance on the NOx reduction, carbon burnout. The NOx emission can be reduced to less than 300 mg/Nm^3 when the Shenhua coal was burned.

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Ultra Super Critical (USC) technology, whose steam temperature is over 593℃, has been developed under government subsidization and applied to many power plants in Japan since early 1990. IHI delivered first USC boiler in Japan in 1993 and completed nine units in total by now, including one with steam temperature 620℃. Furthermore two units are under construction. Coal fired boilers built in the 1960's and 1970's are overdue for replacement due to aging and to meet latest environmental requirement. Customers of those boilers have strong intention to upgrade unit capacity and plant efficiency, when replacing old ones within the existing limited area. To meet such demand, IHI developed new type of tower boiler with USC technology. This paper introduces design concept and latest experience of IHI tower type USC boilers in Japan and Germany.

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The experimental study was carried out on the air-staged combustion of different coal in a 1 MW W-shaped furnace. The combustion process occurred in two zones: the pre-stage combustion zone and the primary combustion zone. A variable SR was introduced to represent the air stoichiometric ratio in the pre-stage combustion zone. It is found that as SR decreases in the test range, the flame penetration depth is lengthened, and the temperature at the exit of the furnace decreases. Meanwhile, the maximum temperature in the central of the furnace first increases and then decreases, whereas the combustible loss and nitrogen oxides (NO_x) emissions first decrease and then increase. The value of SR corresponding to the optimal combustion performance is 0.67 for lean coal and 0.65 for anthracite. Besides, it is also indicated that the effects of air-staging method are more significant on the lean coal than that on the anthracite.

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The first largest scale CFB boiler (300MWe subcritical unit), which is independently developed in china, has been put into commercial operation in Baolihua, Guangdong province with good performance as a whole. But there are still some problems such as uneven wall temperature distribution and overheating in some area of PSH. Detailed analysis and calculation in this paper based on the actual measured data from site have discovered that the un-even heat distribution over enlarged furnace sectional area caused by CFB boiler enlargement should be the main reason. This situation can be well controlled by using various sizes of throttles at the inlet of PSH pipes to redistribute the steam flow.

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Since it is much more than size expansion for the capacity of supercritical CFB boiler rising from 300MW to 600MW and requires a lot of efforts to conquer some of specific technical problems during the research. Without addressing the problems, we can not fulfill the goal of development. So this article is subject to the vital technical problems in the development of supercritical CFB boiler.

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The particle convection can be considered as one of dominant factors of the heat transfer mechanism in fluidized-bed. But the estimation of the effect of particle convection in the actual fluidized-bed is very difficult owing to the complicated particle movement. In this investigation, thus, heat transfer experiment under controlled particle convection was conducted by using the cylinder-shaped fluidized-bed equipped with a stirrer. The cylinder diameter was 115 mm, and the stainless foil heater was attached on the inner surface of the cylinder. The bed material was the silica sand, and average particle diameter was 0.175 mm. The static bed height was 200 mm. As the results, the heat transfer characteristics were measured under arbitrary particle velocities, and showed a strong relationship with the residence time among the heating surface. The experimental result has been well explained by using the numerical calculation with the Molerus's effective thermal conductivity with the considering of the gas convection.

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This paper presented a method for optimization of boiler start-up process based on fuzzy reasoning and process simulation. The boiler parameters are calculated by the simulation program of boiler start-up process, and the drum stress and fatigue life are analysed according to the ASME Boiler and Pressure Vessel Code. The fuzzy relationship between the firing rate and the drum stress is established, and the fuzzy reasoning rules are instituted. The firing rate curve and the pressure-raising curve of the start-up process are optimized by fuzzy reasoning. Using this method, the start-up process of a 600MW boiler from the time of boiler light-off to the time of turbine rolling is optimized. The results show that using the optimized starting curves the start-up time can be reduced greatly without increasing the loss of drum life. Simultaneity, the optimum firing rate and pressure-raising curve provided by the method can help the operators of power plant regulate the start-up process conveniently and intuitively.

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Numerical simulation software is developed and carried out on the furnace of a 1100t/h boiler. Heat load distribution and heat deviations on water-walls were obtained. The numerical results are basically consistent with that from experiments. Two operating conditions were adopted with different swirl velocity arrangements. In condition I, tangential velocities from two burners sharing the same height and same wall, turn upward at the side close to the central line of the furnace, which turn downward in condition II. Results show that, heat load distribution varies a lot, among water-walls and among different locations in the same water-wall, especially at the corners, where bad stress concentration may form; in condition II, the flame center appears at lower position, temperature distribution is more uniform, and the difference of heat load distribution between water-walls is less evident. These results provide important reference value for water-wall safety of large capacity utility boilers.

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It is very difficult to simultaneously reconstruct the temperature distribution and radiative properties of media and walls in an industrial furnace. Because they were intercoupling, especially, the difference of heat transfer character between wall and gas should also be considered. In this paper, four colored images were captured by four flame image detectors which were mounted in the four corners of an industrial furnace. The radiative intensity and temperature information can be obtained from four colored images based on radiation image processing technology. Then a revised Tikhonov regularization method was used to reconstruct the temperature distribution from radiative temperature information, and an optimization method was also ultilized to simultaneously reconstruct the radiative properties of media and walls from radiative intensity information. The simulation results in the different two-dimensional sections show that the temperature distribution and radiative properties involved the absorption and scattering coefficients of media and emissivity of walls can be simultaneously reconstructed at different radiative intensity measurement errors and wall temperature. And the reconstruction error can be maintained at same level with measurement error. The reconstruction results by this algorithm can illuminate the integrated, transient information of radiative heat transfer process in an industrial furnace, and it is especially suitable for online monitoring the surface temperature, such as walls, billets or tubes.

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A semi-industrial experiment on fouling factor of helical finned tube bundle is done in a 75t/h boiler unit. Profiles of the fouling factor with different flue gas velocity are observed. It is found that the fouling factor of the experiment is much smaller than the recommended value by the former Soviet Union standard, which is widely used in China. And it is as the same order as the result of other researchers in China, which is resulted from lab. Discussions are made between the differences. Compared with the work of other researchers in China, the result of this article is more suitable.

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Using a dielectric barrier discharge plasma actuator (DBD-PA), an active control system for flow separation around the MEL001 airfoil was attempted successfully at Re = 3.2×10^4. DBD-PA consists of top and bottom electrodes and a dielectric layer placed between the electrodes. Tangential jet velocities reach their maximum (V_<j-max>) in the range of 0.12 &le; V_<j-max> &le; 1.05 m/s, when bipolar sinusoidal wave voltages are applied, ±2.0, ±2.25, ±2.5, ±2.75, ±3.0 kV at 50 kHz. A series of experiments was carried out in the open-circuit blower type wind tunnel with 200mm×200mm×500mm test section under free stream velocity of U_∞ = 3.2 m/s. A DBD plasma actuator was installed on the MEL001 airfoil (chord length: L = 50 mm, wingspan: W = 200 mm). The wing was set in the test section with angles of attack (a) at a = 8.2 and 12.0 degrees. The effective jet velocities and power consumptions required to suppress flow separation were estimated by the velocity distributions around the airfoil and the current and voltage data so far accumulated on DBD-PA.

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By 'Radial Equilibrium' principle, an equation is derived to describe the radial distribution of the throughflow velocity, by which a design approach is proposed for the twisted blade of axial microfan. This approach can take into consideration the influence of the radial gradient for the throughflow velocity at the impeller's outlet, which is different from the traditional design approach for large fans assuming the throughflow velocity remains radially unchangeable. By this design approach, attempt is made on the design for an axial microfan by choosing different twisted powers so as to obtain different shapes of twisted blades and their respective aerodynamic performance is numerically investigated. Compared to the corresponding straight blade and the twisted blade designed by the traditional approach, this new twisted blade can not only enlarge the stable operating range but also improve the flow pressure, which contributes to the improvement of the blade's aerodynamic performance.

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An important issue for a fossil power plant is maintaining its reliability and safety against frequent start-ups and load changes. Unstable states arising during start-ups, shut-downs, and load changes give rise to unsteady temperature distribution with respect to time in steam turbine components. Thermal stresses caused by the rapid increase in temperature make the components susceptible to failure and reduce their remaining life. In particular, HP and IP casings undergo frequent cracking due to thermo-mechanical low-cycle fatigue at the nozzle fit corner radius or other stress concentration shapes. Thus, for effective maintenance, it is necessary to have accurate knowledge of transient thermal stresses at the critical position that is susceptible to failure. In this paper, thermal stress concentration factors for the inner surface of the casing and valve are defined to account for variations in the geometry using three-dimensional finite element analysis. In addition, the total strain-range is obtained to assess the fatigue life according to the life assessment procedure in Korea. Using this study, the life consumption of steam turbine inner-casing was obtained, and a guideline for effective maintenance is proposed.

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The purpose of the research & design of the BFPT, the definition of the parameter design, the shaft system & blades as well as the main configuration design is briefly described in this article. The structure of the steam turbine and its auxiliary system are also introduced.

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In the steam turbine for power generation, both higher performance and reliability are required. Although the steam turbine key technologies are recently developed by CFD analyses and the experiments, the final verification of them in an actual plant machine is still important. However, it takes much long time for this verification and feedback the results to design processes. Therefore, it is strongly desired to minimize this step. To solve the problem, Toshiba Corporation planned to construct the actual size steam turbine test facility, which was successfully completed and started the operation. The HP turbine has 16 stages, which are supposed to be applied for advanced turbine in the very near future. The LP turbine consists of 6 newly developed stages, including a series of 60Hz35inch last three stages. The first performance test was successfully conducted and both HP and LP turbines showed as good enough efficiency as their design requirement.

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This paper presents a probabilistic analysis method for the heat rate of steam turbines. The method makes use of probability statistics to analyze the influence of the operation parameter scatter on the heat rate of steam turbines by supposing operation parameter of steam turbines as random variables. A calculation formulate of heat rate mean value and standard deviation and a method to analyze the influence of operation parameters deviating from design values on the heat rate as well as a probabilistic analysis method for steam turbine's the heat rate to achieve target value are to be put forward together with a practical example. The main factors affecting heat rate of steam turbines can be diagnosed by use of the method which provided the basis for raising operation economy of steam turbines.

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The exhaust equipment of a 600MW supercritical, direct, air-cooling steam turbine is a very large and complex box shaped structure. The Y shaped connection nozzle between the exhaust box and steam ducts to ACC is a important part of the exhaust equipment. In order to obtain quantitative results in stress and flexibility for this type of equipment design, this paper sets up a calculation analysis model and studies the strength and rigid properties of a 600MW steam turbine's exhaust equipment using Three-Dimensional Finite Element Analysis method. The stress and displacement distribution of the exhaust equipment under different conditions are obtained. The weak positions in the structure are found and important parts are strengthened or modified. The paper also studies the force that is acting on the turbine LP casing by calculation analysis and the pressure loss when exhaust steam flows through the box, obtained from the blowing test by implementing a simplified test model. The research results of this paper can provide a reference for the design of an air cooling steam turbine's exhaust equipment with the same capabilities.

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