This paper describes present status of nuclear power and current technical issues based on the activities of the Japan Nuclear Energy Safety Organization (JNES) which was established on October 1 of 2003. Currently one of the major issues in Japanese nuclear power plants is seismic issue covering Niigata-Chuetsu-oki earthquake two years' ago and re-evaluation of the operating plants in compliance with the new guideline established by Nuclear Safety Commission in 2006. New inspection system has been introduced from this year. Many issues regarding safety regulation have been addressed or under investigation such as ageing, risk application, safety culture, plant uprating, sump clogging, severe accident. Present status of nuclear fuel cycle facilities such as MONJU and the reprocessing plant at Rokkasho is also explained. International activities have been promoted by the globalization and the Multinational Design Evaluation Program (MDEP) is one of them. Role of the technical support organizations (TSO) for regulatory body is attracting more importance.

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Recently, new wind turbine generator optimized for the wind turbine output is proposed. This wind turbine generator is made of PM generator and is using neither control circuit nor PWM converter. From the experiment result and review, it has been confirmed that the matching of the wind turbine and new generator is high. And, action and operating method of this wind turbine generator at fluctuating wind speed is described.

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Aerodynamic efficiency of the wind turbine depends on operating conditions such as tip speed ratio and pitch settings. Generally, the wind turbine blades are designed based on the blade element momentum theory. In this process, the aerodynamic performance of airfoil sections by two dimensional wind tunnel test with some fixed angle of attack are used. However, during wind turbine operation at the field, wind direction and wind velocity always changes. They bring about fluctuation of angle of attack of the rotor blade. Therefore clarification of airfoil characteristics in dynamic conditions is important for accurate estimation of power output and loads of wind turbine. In this study, wind tunnel experiments in static and dynamic condition are conducted.

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In this study, two types of experimental wind turbines were tested to compare the performance at low tip speed ratio. One has a rotor with tapered blades designed by the combined blade element and momentum theory less than tip speed ratio 2. The other rotor has inversely tapered blades in which the calculated chord length are applied in an opposite way. Moreover, the authors tested experimental blades with winglet. In addition, to analyze the behavior of the air flow around these rotors, the visualization test by PIV has also conducted.

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In recent years, the importance of renewable energy has been increasing because of the need to prevent global warming. In order to decrease the impact on the environment, a lot of wind turbine generation systems have been actively introduced all over the world. The importance of the Yaw control system of large wind turbines rises in this situation. The investigation and analysis for the large wind power system with trail torque mechanism, THK-R Guide and Gearless structure, the application and possible result for the Trail Control Installation and R-Guide in the large wind power system.

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This paper reports the considering of the behavior and power performance for the Straight Wing Vertical Axis Wind Turbine (SW-VAWT). Features of SW-VAWT are non-directivity and low noise. Therefore, SW-VAWT is suitable for an urban site because wind characteristics of that are generally the low wind speed and the extreme change of the wind direction. Then, we carried out the simulation of the behavior for this turbine in the urban wind condition, and this simulation uses the turbine motion equation which depends on the relation of the inertia, load, and initial mechanical loss. From this work, we clear that the most important element to efficient driving of this turbine in the urban site is the decrease of the initial mechanical loss.

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Wind turbines generate sustainable energy, however CO_2 is emitted during the various processes in the life cycle of a wind turbine. Therefore, it is important to take into account the latest data of the environmental impact in addition to applying megawatt scale wind turbines by the method of LCA. In this study, recent CO_2 basic unit (g-CO_2/kWh) was calculated under the conditions of that the life time of turbines is set to be 20 years and the life cycle includes manufacturing, construction, transportation and operation processes. The recalculation result of the domestic 2MW wind turbine constructed in Choshi area shows 10.8g-CO_2/kWh and 13.5g-CO_2/kWh under the conditions of average wind speed = 6m/s, CO_2 emission rate of operation and maintenance =1.0%/year, the loss of transmission grid = 5% in its life cycle. The important points of electricity produced by wind turbines are finding locations with good wind supply and application of large scale wind turbines. And the "product category rule" should be established for the standardized calculation of the Japanese CO_2 basic unit (g-CO_2/kWh) of the wind generator.

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Operating in natural wind field, a horizontal axis wind turbine suffers fluctuating aerodynamic loads, which result in oscillations of the rotor blades. Since the blade oscillation has considerable effects on the blade fatigue life, the influence on the fatigue loads from the interaction between the aerodynamic loads and the structural oscillations should be considered in the design process. The objective of this work is to analyze the fatigue loads on rotor blade due to inflow conditions and structural oscillation. The turbulent wind field is simulated with the Veers' model. For the calculation of aerodynamic loads on the rotor blades, vortex lattice method based on panel method was adopted. In order to consider the blade oscillation, a structural model with multiple degrees of freedom based on multi-body dynamics was used. For fatigue load analysis, each of the simulated time series of the loads was processed with the rain-flow counting algorithm.

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The total introduction capacity of wind power generation facility in Japan is staying in 1,745MW and total quantity is staying in 1,449 units (the source : JWPA). This is equal to or less than 10 percents compared with world No. 1 market / United States (approximately 25,000 MW) or world No. 2 market / Germany (approximately 24,000 MW). It seems some particular environmental or local conditions cause this difference. We must seek for the possibility to promote the introduction by consideration of the technical problems and countermeasures. In this thesis we summarize the electric types and control system functions in the recent large-scale wind power generation facilities and we investigated the possibility to control power fluctuation by the battery system application.

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We have started the research of application for comprehensive wind energy since 1976. The research has continued for more than thirty years. The topics of the research include the design of best suitable turbines, wind characteristics, wind energy density and reserve, the efficiency of the wind power system, etc. Both the Straight Win Fixed Pitch Vertical Axis and the Horizontal Axis wind power systems have done the wind tunnel experiments and field tests. The research results also cover the relevant running tests, determination of the boundaries, stress tests in limits, etc. This report is the summarized statement for the most up-to-date experimental results of the Straight Wing Vertical Axis Wind Turbine power system.

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This paper proposes the wind collector with the vertical axis wind power generation. This proposes system is composed of the vertical axis windmill, the wind collector, and the generator. This experiment was examined the effect of wind collect in the wind tunnel. Moreover, this experiment compared about wind velocity characteristics, the output of power characteristics by setting angle of the wind collection board and the position. As a result, it confirmed wind collect effectiveness by introducing the wind collector.

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This paper proposes wind collector with the vertical axis wind power generation. This proposes system is composed of the vertical axis windmill, the wind collector, and the generator. This experiment was examined effect of wind collect in the wind tunnel. Moreover, this study compared about the voltage characteristics, the rotational speed characteristics , the output of power characteristics by setting angle of the wind collection board and the position. As a result, it confirmed wind collect device effectiveness by introducing the wind collector.

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This Paper presents a study of small scale wind powered generation systems (SW-VAWT) combined with solar cell generation unit as a reliable electric power source from Taiwan in Mingdao University. This system is environmental friendly and designed to proactively utilize the abundant natural resource. The experiments of the system done by the Mingdao University at Taiwan have completed the great results. It further enlightens the resident's concept for the application of new energy and enhances the better understanding of energy efficiency.. In these regions, wind is strong through a year and is constantly available and, if the wind turbine generation system is combined with solar cell unit, it will be an ideal independent electric source. The ultimate design concept was required for development and reliable operation for independent electric source powered. Therefore, the system was simplified. The research application has accomplished great experimental results not only in Japan, but also in many different locations in Taiwan. The experimental results are efficient and matched with the projection, and those results also prove the effectiveness of the lab theory.

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The subject of this study is a reliable and independent electric source powered by a small wind turbine which is intended to introduce by education. In these regions, wind is strong through a year and is constantly available and, if the wind turbine generation system is combined with solar cell unit, it will be an ideal independent electric source.The ultimate design concept was required for development and reliable operation for independent electric source powered. Therefore, the system was simplified. The system of straight wing non-articulated vertical axis wind turbine (SW-VAWT) has been shown good wind energy transform efficiency, by fixing a number of straight wings around vertical axis. Our experimental VAWT was designed based on the study and preliminary structural boundary to confirm them and collect operating experience under real, fluctuating wind with a number of loading devices.

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This research is focused on the characteristics of the "non-periodically controlled Dalieus Vertical Axis Wind Turbine system". The system has the fixed pitch and high ratio of cycling speed, and it generates the bigger torque. Therefore, the system has the better efficiency while remains the simple and smart mechanical structure. This Hercules Type Wind Turbine system is a newly developed system which can utilize the low speed wind, and it is evolved and refined from the past R&D results. The new equipment has done the Field Test and completed the experimental application with analysis partially finished. This paper is the general summary for the accomplishments and results.

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The large-scale wind turbines with the grid connection system operated in wind farms are being used for the power generation in many nations. On the other hand, the small-scale wind turbines have been used as the independent source of power regardless of the places. In resent years, these small wind turbines are employed for street lights, park lights, environmental monuments and power sources for emergencies. Among such trends, sail-wing windmills are revaluated in the modern society because of their safety, reduced noise and attractive appearance. Therefore, in the present study, the authors made the vertical axis sail-wing type variable paddle windmill with link mechanism and evaluated their aerodynamic performance to find the optimal shape and configuration experimentally in a wind tunnel. The results show that the windmill with -20 deg angle of adjustment has the maximum power coefficient of Cp=0.325.

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Experiments were conducted to explore the effects of the mutual interaction between two widely spaced Savonius rotors within a wind tunnel. The number of revolution was investigated for two different velocity and conditions, being under small friction and high friction with revolution control. The optimum set of the parameter was found to be u= 4.0 m/s, (x, y) = (2.0D, 0.5D) with two rotors rotating in the same direction under small friction, and the number of revolution of them became 9.1% larger than that of the single rotor. In contrast, increase of revolution was not observed with u= 5.0 m/s under the condition of revolution control and high friction. This result shows that the mutual interference of two Savonius rotors depends on the relation between wake structure and tip speed ratio.

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Cavitation induced vibration and the consequent erosion of pipes are the potential damaging factors in the piping system. In order to prevent such trouble, it is preferable to develop a detection method of cavitation occurrence. Therefore, we investigated detection of cavitation using accelerometers mounted on the outer surface, of apiping. However, in this method, it is difficult to detect incient cavitation, and it is required to comfirm effectiveness of the detection method cavitation. In this study, in order to evaluate incipience of cavitation erosion, we carried out cavitation erosion experiments with alminium specimens and impact force detectors. As the resuts: (1) In the cavitation erosion experiments, the incipient cavitation number, where cavitation erosion pits occured, was 0.8 at 50mm and 75mm downstream of the orifice and 0.7 at 100mm. At those cavitation numbers, the states of cavitation was a developed stage or near the developed stage. (2) In the measurements of impulsive force, the cavitation number, where impulsive force began to increase, almost agreed with the cavitation number at occurrence of erosion pits.

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Liquid droplet impingement erosion (LDI) is defined as an erosion phenomenon caused by high-speed droplet attack in a steam flow. In a power plant, pipe wall thinning by LDI is observed steam piping system. Because LDI usually occur very locally and is difficult to detect, a prediction of LDI location is required for the safety of the plant system. Therefore, as ultimate objectives, we set the development of the prediction tool of LDI location that can use in power plants easily (LDI Prediction Code). In previous researches, we developed LDI evaluation system, core part of LDI Prediction Code, to organize past achievements and knowledge systematically. However, this system needs 3-dimensional simulations to evaluate the mass flow rate and the droplet behavior which are important parts of the system. As 3-dimensional simulations have heavy loads, it is difficult to use as is in power plants. In this study, we tried to develop new methods to evaluate the mass flow rate and the droplet behavior easily instead of 3-dimensional simulations and to modify the 1-dimensional flow evaluation code "MATIS-SP" to apply high-wetness and water region. For the mass flow rate evaluation, we assumed the flow choked at the orifice, and suggested an analytical method with experimental and computational results. This approach agrees well with experiments and computations within acceptable range. For the flow evaluation, we developed a new code "MATIS-SP2" by adopting a simplified model that only considered pressure loss evaluation and applicable to all region of the steam/water. And for the droplet behavior evaluation, we conducted much simulations of the droplet behavior and suggested the correlation between droplet collision rate and flow state quantities from simulation results. Finally, we suggested new evaluation system with no 3-dimensional simulations and wide applicable region, and compared them with previous system by LDI evaluation in model system.

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Liquid droplet impediment erosion (LDI) is a pipe wall thinning phenomena that a droplet accelerated by steam flow attacks pipe surface. It is difficult to evaluate LDI behavior in the system of NPP. Therefore, in current pipe wall thinning management, the pipe element is replaced conservatively when it is recognized to become thinner by pipe wall thinning measurement result. If LDI behavior at each point of the system can be estimated, it is possible to measure the pipe wall thickness and replace the pipe element at an appropriate time. CRIEPI has constructed the evaluation system for LDI by using flow dynamics. In this paper, following items are described; /the applicability of the LDI evaluation system by a comparative verification between pipe wall thinning rate calculated by LDI system and that by actual measurement result / establishment of remaining life assessment method of pipe in LDI environment by using LDI model.

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In recent years, the power uprate of Boiling Water Reactors have been conducted at several existing power plants as a way to improve plant economy. In one of the power uprated plants (117.8% uprates) in the United States, the steam dryer breakages due to fatigue fracture occurred. It is conceivable that the increased steam flow passing through the branches caused a self-induced vibration with the propagation of sound wave into the steam-dome. The resonance among the structure, flow and the pressure fluctuation resulted in the breakages. To understand the basic mechanism of the resonance, previous researches were done by a point measurement of the pressure and by a phase averaged measurement of the flow, while it was difficult to detect the interaction among them by the conventional method. In this study, Dynamic Particle Image Velocimetory (PIV) System was applied to investigate the effect of sound on natural convection and forced convection. Especially, when the phases of acoustic sources were different, various acoustic wave effects were checked.

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Effects of Cr content and environmental factors, pH and dissolved oxygen concentration, on removal rate of carbon steels due to flow accelerated corrosion have been examined by experiments. Cr content holds a strong impact on the FAC rate regardless of pH values from 6.84 to 10.4. Addition of 1% Cr to carbon steel reduces the FAC rate by one order of magnitude under the environmental conditions, where magnetite forms. Detailed characterizations of oxide film formed on the specimen have been carried out by using SEM and TEM. Preferential corrosion of pearlite phase has been observed at specimen surface of low Cr content steel in early stage of FAC. It has been suggested that oxide structure and porosity were obviously different between low and high Cr content steels.

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The prediction model of flow accelerated corrosion (FAC) rate based on the FAC mechanism is required in the wall thinning management of the power plant. The dominant factors of FAC are water chemistry, material, and fluid dynamics. It is expected that the solubility of iron can express the effect of water chemistry on FAC. The correlation between solubility and FAC rate has not been adequately discussed. In this study, a novel model of chemical effect on FAC that was developed by taking into account the diffusion of iron, chromium, dissolved hydrogen and dissolved oxygen and under steady-state condition is proposed. The FAC model reproduces qualitatively effect of major water chemistry parameters on FAC rate. The equation to evaluate a critical dissolved oxygen concentration for FAC suppression is also proposed.

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Flow Accelerated Corrosion (FAC) requires considerable attention in plant piping management, for its potential of catastrophic pipe rupture of main piping systems. In view of fluid dynamics, the most essential factor to be considered is mass transfer at the inner surface of the pipe. In the previous report, the authors have proposed a new mass transfer coefficient model, which is adaptable to various types of piping elements with strong turbulence, by introducing the idea of "Effective Friction Velocity" from the hydraulics in the viscous sub-layer along the wall. And in the present report, the model has been revised with rational logic, and verified with additional data obtained in FAC experiments with AVT water condition and CFD for the flow in the experiments. Furthermore, some discussion was made by considering the correlation of the thinning rate and the product of mass transfer and iron solubility, for the prospect of thinning rate prediction.

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In this study, in order to understand flow fields downstream of a valve, an acrylic test section of a globe valve was made and velocity profiles were measured by laser Doppler velocimetry (LDV). Flow visualization by ink was also conducted. The diameter D of a downstream pipe is 50 mm, and mean cross-sectional velocity was set to 3.54 m/s in LDV measurement, 0.453 m/s in flow visualization, respectively. Horizontal or vertical velocity profiles were found asymmetric. Flow velocity around the lower wall near the outlet of the valve was accelerated. Velocity near the center axis of the pipe was lower than that near the pipe wall, which is a characteristic of swirl flow. Existence of swirl flow was also confirmed by flow visualization. Velocity profiles approached fully developed turbulent profile at downstream after 7D.

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Pipe wall thinning is sporadically detected in ferritic steel piping in Japanese BWR plants. The suitability for continued service of wall thinning pipe is basically evaluated by using the "Rules on pipe wall thinning management for BWR power plants." The probabilistic fracture mechanics (PFM) analysis was performed in order to confirm the failure probability applied the rule. Based on the result, the issues of the rule which should be solved ware clarified.

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This paper shows the test items and equipments introduced by Japan Nuclear Energy Safety Organization to establish the monitoring technique for machinery conditions. From the result of vertical pump simulation tests, it was confirmed that fault analysis was impossible by measuring the accelerations on both motor and pump column pipes, however, was possible by measuring of pump shaft vibrations. Because hydraulic whirls by bearing wear had significant influences over bearing misalignments and flow rates, the monitoring trends must be done under the same condition (on bearing alignments and flow rates). We have confirmed that malfunctions of vertical pumps can be diagnosed using measured shaft vibration by ultrasonic sensors from outer surface of pump casing on the floor.

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Recently, stress corrosion cracking (SCC) has been observed in aged components of nuclear power plants located in primary water environments and subjected to high radiation exposure levels. Toshiba has developed an Underwater Laser Beam Welding (ULBW) process that applies SCC-resistant weld metal directly onto surface of the aged components, serving as a method of maintenance and repair. This paper provides an update on ULBW using filler material Alloy 52 and development of welding machine for Reactor Coolant System (RCS) nozzle of PWR.

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Some damages were found at the forks of low pressure turbine blades caused by random vibration and steam-flashback vibration. In this study, for the aim of fatigue property improvement, laser peening technology for 12Cr stainless steel was developed and material properties were examined. Laser peening is a process to induce compressive residual stress to the material surface. Fatigue specimens which simulate the stress concentration zone of forks were fabricated and laser peening was applied to the surface of specimens. Residual stress was measured by X-ray diffraction and compressive residual stress was formed on the peened surface. As the results of fatigue test, fatigue strength of the laser peened specimens was improved about 40 percent compared to the unpeened specimens.

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Creep tests on 9Cr and 12Cr steels welded joints were conducted under internal pressure conditions as well as uniaxial stress conditions. For both materials, failure occurs at fine grain HAZ region under long time region, which means type IV damage. SEM observation was carried out on internal pressure test specimens of the welded joints. It was found that density of creep voids is higher in mid-thickness of the HAZ portion than that in outer and inner surfaces. Furthermore, a recently developed demonstration test facility, which can load bending forces and internal pressure on actual boiler pipes at high temperatures, is briefly introduced in this presentation.

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In the rules on fitness-for-service for nuclear power plants of the Japan society of mechanical engineers (JSME). failure assessment procedures are prescribed only for austenitic stainless steel and ferric steel. In this study, the failure assessment procedure for nickel alloy and its welding metal was investigated. Failure loads were evaluated for welding part of a pipe of 36B using the two-parameter failure assessment procedure. Axial and circumferential surface cracks were assumed and cHntegral values were evaluated by finite element analysis. Based on the failure assessment using material data, it was revealed the failure assessment procedure for plastic collapse (limit load analysis) can be applied for welding metal as well as base metal of the nickel alloy.

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Thermal fatigue is one of critical problems in nuclear power plants. To prevent crack initiation, JSME has issued a guideline for design. In this study, the feasibility of incorporating crack growth analysis into the design and integrity evaluation was investigated. It was shown that the steep stress gradient near the surface significantly reduced the stress intensity factor of deep cracks. It is concluded that, under thermal fatigue loading, the cracks that are detected in the in-service inspection have already been arrested if they do not penetrate the wall thickness. The crack arrest scenario is a reasonable method of assessing the integrity of cracked components.

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In case the electromagnetic pump in the primary sodium purification system of Monju trips up, the sodium flow in the system stops. If we restart the system without stopping the main primary sodium circuit system, the mixing piping structure which connects the branch flow from the purification system to the main flow is subjected to thermal transient load because the cold stagnant sodium is pushed out and the hot sodium from main flow follows. The aim of this study is to assess the fatigue damage of the mixing piping structure in the primary sodium purification system of Monju in case its electromagnetic pump trips up and then it is restarted with keeping plant operation. From the analysis results, we found that [1] the fatigue damages were mainly dependent on the temperature difference between the cold sodium at the initial stage and the hot sodium after restart, [2] the fatigue damages were considerably mitigated by preheating and [3] even the severest case allows more than 400 cycles of this events.

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Installation of hydrofoils to ship wetted surface enables bubble generation to be realized with power consumption much lower than conventional bubble generators. With help of this principle, net effect of frictional drag reduction for ships can be improved. We have already obtained around 10% net power-saving efficiency for a cargo ferry throughout about a half year. The power-saving has a large potential to be improved more by considering multiphase fluid dynamics in terms of the hydrofoil-water-air triple interaction. In this paper, the basic principle of the bubble generation and the trial parametric studies implemented by numerical and experimental visualizations are reported.

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When a heat exchanger in a Fast Breeder Reactor cracks, a sodium-water reaction occurs. Highly pressurized water or steam escapes into the surrounding liquid sodium from the crack. The release of steam into the liquid sodium media is a two-phase flow with an underexpansion. Several studies have examined only the underexpansion of the gas-gas phase. However, there are few reports on the underexpansion of the gas-liquid phase. In this study quantitative measurement was carried out for the purpose of revealing the flow with the underexpanded gas jet injected into water. The gas jet distance L and the expansion angle θ were then obtained from averaged images of a high-speed camera. L and θ increased approximately linearly with increasing pressure. The entrainment velocity and the velocity of entrained water droplets into the gas jet were obtained by PIV.

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In order to design the riskless and high efficient slurry transport system, determination of mechanism in iquid-Solid Flow is important. The aim of this study is to reveal the behavior of a rotating solid cylinder with solid wall. The rotation of the cylinder was generated by slope. The trajectory of the cylinder and it's ambient fluid were examined experimentally. The trajectory of cylinder was measured by image processing. The flow around cylinder was measured by PIV. By experiment, two kinds of collision mechanism were found. This phenomenon is affected by ratio of horizontal velocity and vertical velocity of the cylinder.

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Free surface fluctuations at the neighboring two locations on a water jet have been measured using the non-intrusive optical technique. The instantaneous free-surface slope angle is evaluated by detecting the two dimensional trajectories of laser beams refracted at the jet free surface. The obtained time series data of slope angle is divided into each wave period according to zero-up-crossing method. The individual wave speed is evaluated from the dominant time lag of cross-correlation coefficient. Moreover, the spatial shape of each wave is reconstructed by integrating slope angle data. By comparing the statistical property of spatial wave shapes and the observation of jet free surface, it is found that the wave steepness reaches a maximum in the free surface region where a periodic wave pattern breaks down into less regular three dimensional pattern. And the probability density function of non-dimensional wave height also approximates to the Rayleigh distribution downstream this region.

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Gas-liquid two-phase flow is encountered in many industries, including flow near nuclear fuel rods in boiling water reactor (BWR). Especially dryout of water film occurs at the thin base film between two successive disturbance waves. Therefore, it is important to clarify the detailed behavior of the disturbance wave. In previous studies, many experiments were performed under atmospheric condition. However the properties of liquid and gas under atmospheric condition are quite different from those of a BWR operating condition (7MPa, 285℃). Therefore, in the present study, HFC 134a gas and ethanol liquid, whose properties are similar to those of the BWR operating conditions are used as the test fluids at comparatively low pressure and low temperature (0.7MPa, 40℃). In this paper, the effect of gas-liquid properties on the liquid film thickness is discussed.

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If severe accident is occurred in the fast breeder reactor, the molten metal fuel may leak into a sodium pool. Then the solidification and breakup of the dissolution metal will occur by fuel-core interaction. For the preliminary clarification of the mechanism, we have researched the behavior of metal spheres with bubble cavity when entering into free surface. In this study, we focused on the experimental results of the relation between bubble cavity volume and drag coefficient.

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This study is concerned with extension of numerical code called CRIMSON (Civa Refined Multiphase SimulatiON), which has been developed to evaluate multi-phase flow behaviors based on the recent CFD (computational fluid dynamics) techniques. The CRIMSON employs a finite-volume method combined with the high order interpolation scheme, CIVA (cubic-interpolation with area/volume coordinates). The CRIMSON solves gas-liquid two phases by a unified scheme of CUP (combined unified procedure). The conventional CIVA method has a problem of loosing interface sharpness in long-term calculation. In this study, the problem was solved by introducing the idea of the phase field method. For numerical analyzing splashing fluid, we also introduced the SPH particle method to the CRIMSON.

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The behavior of the particle in down-flow circulating fluidized bed (downer) was simulated by DEM (Discrete Element Method) and the animation and graph of the particle behaviors were obtained. This DEM is the method that can consider influence of a turn / a collision / the current of air of the particle about each particle. And the particle diameter was set as 7mm in this gas-solid two-phase down flow simulation. Then, the simulation result was compared with the experimental data obtained by the electrical capacitance tomography (ECT). As a result, the simulation result shows a good agreement with those of the experiment.

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