For the safety improvement of the nuclear power plant, the safety equipment is constructing additionally under the new regulatory requirements. With the increase of safety equipment, the amount of inspection during the outage may increase. Accordingly, increase of the outage lead to prolong maintenance schedule period. To perform the outage efficiently, we propose the diagnosis method of steam turbine for a power generation using data to control plant operation(plant operation data). With plant operation data, the diagnosis can be made without adding measurement equipment, and past plant operation data can be used for diagnosis. The diagnostic method of this research detects abnormality based on the rate of change of vibration amplitude with increase of rotational speed, noting that the rate of change differs between normal condition and abnormal condition. Detecting an abnormality based on the rate of change of vibration amplitude enables early diagnosis of abnormalities before vibration amplitude increase. With this diagnostic method, it is possible to perform the outage efficiently.

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In high temperature gas-cooled reactors (HTGRs), Tri-isotropic (TRISO)-coated fuel particles are employed as fuel. In the high burnup coated fuel particle, stress due to fission gas pressure and irradiation-induced pyrolytic carbon (PyC) shrinkage is introduced into the coating layers and consequently the stress could cause failure of coating layers under high burnup irradiation condition. A failure model has developed to predict failure fraction of TRISO-coated particle under high burnup irradiation. In the model, it is assumed that the failure fraction depends not only on failure of the SiC layer but also on that of the PyC layers. Therefore, failure probability is strongly dependent on the irradiation characteristics of PyC. However, it is difficult to obtain new irradiation data of PyC by experiments. This paper describes the outline of the failure model and the issues to determine PyC characteristics.

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Hydrogen for fuel-cell power plants is commonly manufactured from hydrogen-rich materials such as hydrocarbons and alcohols, using steam-reforming with catalysts. Recently, the authors have investigated the optimum conditions for efficient and endurable steam reforming. The authors have been investigating the optimum conditions, especially focusing on both the influences of liquid-hourly space velocity LHSV upon concentrations and the ethanol conversion efficiency. In the present study, as well as our previous study (Momosaki et al., 2018), we attempt to improve the theory proposed in our previous study, in order to extend its applicable range. More specifically, all the concentrations are close to the theory except for the case at low reaction temperature T_R and high LHSV. To settle the inconsistency of this exceptional case, the authors improve the theory using some chemical reactions related with acetaldehyde in a wide range of T_R and LHSV.

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Aluminum and water are highly reactive and produce hydrogen at high reaction rates. However, the aluminum surface in the atmosphere is covered with a strong oxide film, and its reactivity with water is not high. On the other hand, when aluminum is used as a powder and stirred in pure water, the hydrogen generation reaction proceeds. The authors note this mechanochemical reaction, and found that the use of alloy powder with tin or zinc etc. further increased the reaction rate. This paper describes the demonstration results of high-pressure hydrogen production by mechanochemical reaction using aluminum alloy powder and the results of hydrogen production cost estimation in hydrogen production plant using this mechanism.

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In order to construct a hydrogen energy system, water electrolysis technology for converting renewable energy into hydrogen has recently attracted attention. In particular, a proton exchange membrane (PEM) water electrolysis can be operated at high current density and can produce high purity hydrogen compared to other water electrolysis techniques. However, increasing th0e efficiency is indispensable for putting PEM water electrolysis into practical use in the future. One of the serious problems is that the staying of generated oxygen bubbles in the reaction site inhibits the water supply and significantly reduces the reaction efficiency. However, the mechanism of generation, growth and detachment of oxygen bubbles on the reaction site in the PEM electrolyzer has not been clarified. Therefore, in this research, in order to understand the two-phase flow phenomenon of this oxygen bubble, the behavior of the bubbles was observed using a visible light high-speed camera and a visualized electrolysis cell.

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A film-laminated microfluidic device was fabricated to analyze a catalytic slurry used to make a porous electrode of polymer electrolyte fuel cells and sorting of particles in the slurry was demonstrated. Agglomerated particles in the slurry can affect porous structure such as cracking, surface roughness and inhomogeneous pore size distribution. These structural properties can correspond with a cell performance. The agglomerated particles settle down faster than small particles based on Stokes’ law and are sorted in the microfluidic device which has a flow channel with upper and lower branches of inlet and outlet in the direction of gravitational force. The sorted particles in the flow channel were observed by optical microscopy. A large number of the agglomerated particles were successfully sorted to the lower branch of the outlet according to the flow rate. The catalytic slurries with/without ultrasonication were supplied to the microfluidic device. The slurry with ultrasonication showed a smaller number of agglomerated particles than the slurry without ultrasonication. This can be because the agglomerated particles have broken down into smaller particles by the ultrasonication process.

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The degradation mechanisms of the conventional nickel-based solid oxide fuel cell (SOFC) anode are related to the poisoning, coarsening and redox instability of the Ni phase. In the present study, the fabrication process of Ni-free anode composed of LSCM (La_0.9Sr_0.1Cr_0.5Mn_0.5O₃) and GDC (Gd_0.1Ce_0.9O₂) was optimized. The feasibility of new electrode design was evaluated by the comparison with the conventional Ni-based anodes with particles of submicron size.

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To improve the performance of solid oxide fuel cell (SOFC) electrodes, nanoparticles are introduced to the porous electrodes by infiltration technique and its effect is investigated by electrochemical measurements and microstructural analysis. A solution containing active metals is introduced into the porous electrodes, followed by heat treatment yielding precipitation of nanoparticles. GDC (gadolinia-doped ceria) infiltration into LSCF (lanthanum strontium cobalt ferrite) cathode and Ni infiltration to YSZ (yttria-stabilized zirconia) scaffold are performed. In the GDC-infiltrated cathode, it is confirmed that the GDC nanoparticles of several tens of nm are introduced, which increases the density of the electrochemical reaction sites, and thereby improves the electrochemical activity. In the Ni-infiltrated anode, the performance at low temperature is improved. These suggest the effectiveness of the infiltration technique to enhance electrode performance.

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We present a modeling framework which jointly uses discrete element method, kinetic Monte Carlo method, lattice Boltzmann method and artificial neural network to predict the electrochemical performance and degradation rate of solid oxide fuel cell cathode from raw powder. A multi-objective genetic algorithm is used to minimize both the overpotential and degradation rate of the cathode. The Pareto front is obtained for the optimal design of cathode microstructures.

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This study conducted model analysis and experimental investigations in polymer electrolyte fuel cell (PEFC) startup below freezing point to confirm the cold start characteristics with temperature rise. In the experimental investigations, a single cell with an active area of 25cm² (5cm×5cm) was used. Heaters and heat insulating plates were inserted between the current collectors and the end plates to simulate the adiabatic condition by controlling the cell temperature. In the model analysis, we considered water generation, electro-osmosis and back diffusion to estimate water content in membrane. Here, the model was developed based on cold startup at −30°C. The results of model analysis showed that 2 step current loading is more appropriate than ramp loading to avoid shutdown due to dry-out in early startup. In the experimental investigations simulating adiabatic temperature rise at −30°C, the 2 step loading improved the performance of PEFC cold startup, and made it possible for the cell temperature to rise from −30°C up to 0°C without any shutdown due to both dry-out and ice formation.

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In order to improve the power generation performance and extend the life of PEFC, it is important to clarify the temperature distribution of interface between PEM and catalyst layer at the cathode, i.e. reaction surface, in single cell. In this study, a heat transfer model is constructed to evaluate the heat transfer phenomena in single PEFC cell operated at high temperature such as 90℃ which is the target temperature for stationary applications during the period from 2020 to 2025 in Japan according to NEDO road map 2017. The impact of MPL on the temperature distribution under the high temperature operation condition was investigated. As a result, it is revealed that the temperature on reaction surface rises from the inlet to the outlet of the cell by approximately 1 – 2℃ at T_ini = 80, 90℃ with MPL, while it becomes relatively flat at T_ini = 100℃. In addition, the temperature on reaction surface rises from the inlet to the outlet of the cell by approximately 1 – 2℃ at T_ini = 90℃ with MPL irrespective of relative humidity conditions.

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Redox flow battery is expected as a large capacity battery for leveling power variation of renewable energy. To improve redox flow battery’s performance, detailed knowledge about the effects of structure and operation conditions on the performance is needed. In the previous study, the authors investigated the performance and current density distribution in various conditions experimentally, and developed analysis models which can evaluate the effects of structure and operation conditions, based on the experimental results. Simple evaluation equations which can calculate performance in low current density region was also developed with some assumptions to summarize the major parameters dominating performance. This study extends the major parameters summarizing the effects of structure and operation conditions on performance to high current density region, and proposes evaluation methods of the performance using two figures with major parameters. These presents efficient design guidelines of the optimal structure and operation conditions for high performance redox flow battery. In order to verify the effectiveness of this evaluation method, we evaluated the performance in various conditions.

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Topology optimization of electrolyte-electrode interfaces of solid oxide fuel cells is presented. The total amount of reaction current is chosen as an objective function to be maximized. A cylindrical pillar is userd as an initial condition, and is iteratively modified using the optimization procedure based on the adjoint-method. The results show that the present method is capable of finding structures that can increase the total amount of reaction in the anode. It is also shown that the obtained structures have characteristic sub-structures like ’wrinkles’ at the bottom side, which effectively work as a conduction pathway for oxide ions.

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Oxide ion diffusion around a Double Phase Boundary (DPB) on the surface of LSM-grains cathode in SOFC was visualized using an oxygen-isotope quenching method. Corresponding to an instantly-stepwise increase in a current density, the terminal voltage decreased instantly. After that, the terminal voltage recovered gradually up to 60 % during more than 100 seconds because the surface of LSM-grains in cathode played an important role on production of oxide ions as the DPB in addition to the Triple Phase Boundary (TPB) at the interface between the LSM-grains and a dense YSZ electrolyte. The diffusion of oxide ion around the DPB and TPB was clearly observed.

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The purpose of this study is to measure the permeability of a porous Ni–YSZ (yttria-stabilized zirconia) cermet used for SOFC anodes and to reveal the relationships between its microstructure and the permeability. Anode disks with different microstructure are prepared by changing the particle size and weight ratio of pore formers. The pressure difference formed between both sides of the anode disks is measured at various permeation flow rate of the air. Then, the permeability of each disk is calculated from Darcy’s law. It is found that the permeability increases as the average pore size increases. For instance, the permeability of the disk with the average pore size of 2.1 µm is 3.4 × 10^-14-14 m² , whereas that with the average pore size of 0.69 µm is 4.4 × 10^-16 m² .

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Hydrogen energy system, which is composed of PEFC/EC and hydrogen storage, has an advantage in energy density at larger scale of electricity storage, and it will be applied in space field, such as a power source for lunar exploration sites. In this scenario, gas leakage from cell becomes large problem, because it is difficult to re-fuel. This study measures the hydrogen gas leakage rate from a unit PEFC under vacuum condition, and also challenges to theoretically predict the leakage rate. Comparison between the measurement and theoretical analysis clarified the influence of cell component properties (Young’s modulus and surface roughness) on the leakage rate.

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Polymer electrolyte fuel cells (PEFCs) are highly expected as a technology for stationary power generation, hybrid engines in automobile and various applications. To improve the performance of PEFCs, analysis of mass transport is very important. On the other hand, durability is one of the critical problems for practical use. Chemical decomposition of PEM by hydroxyl radicals has been reported as one of causes of PEFCs degradation, and as a countermeasure, a method of adding cerium ions into the PEM has been studied. Using molecular dynamics simulations, we constructed a system of the polymer electrolyte membrane (PEM) that contains cerium ions to investigate the effect of cerium ions on the proton transport property. We have obtained proton diffusion coefficient, radial distribution function, coordinate number, number of cluster and cluster size. As a result, we found that at low water content, diffusion coefficient of protons increases by adding cerium ions because cerium ions attract the surrounding water molecules and clusters are connected to make better diffusion path of protons. At high water content, clusters are grown to a sufficient size with or without cerium ions. Moreover, due to the presence of highly charged cerium ions in the cluster, it repulses with protons having the same positive charge, thereby reducing the diffusion of protons.

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Two-phase flow and ion transportation three dimensional numerical simulations of alkaline water electrolysis are conducted to clarify the influence of mixing effect with an oxygen bubble on overpotential. The numerical results are shown that not only the concentration distribution, but also electrical potential distribution is transformed with the bubble and the total overpotential is suppressed by mixing the electrolyte with floating force. The suppression of the overpotential is mainly achieved with the suppression of the anode concentration overpotential and solution overpotential.

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Influence of high-intensity turbulence to the performance of a Savonious wind turbine has been investigated experimentally. The turbulent intensity and its isotropic quality are managed in a large wake region of an open-jet type wind tunnel. We have found that the rotational speed of the turbine rather increases with hep of turbulence as a constant load was subject to the turbine. This robustness to the inflow quality is attributed to the drag acting on the blade being intensified by the turbulence. Hot-wire anemometer measurement of the flow behind the turbine revealed that periodic vortex-shedding due to the blade-passing frequency was suppressed with strong turbulence in the inflow.

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In the present study, the authors conduct subsonic wind-tunnel experiments, in order to investigate the basic aerodynamic characteristics of an autorotating finite flat plate in uniform mainstream, which has a potential for new windmills and waterwheels with very simple structures in addition to new mixers/diffusers. The present study focuses on both the effects of an aspect ratio AR and a tip-speed ratio Ω^∗ upon the tumbling of the flat plate with a low thickness-tobreadth ratio λ = 1.3×10-2 − 2.0×10-2 . The authors carry out the measurements using a torquemeter together with the synchronised measurements of the plate’s attack angle α for the analyses with phase-averaging technique. As a result, the torque coefficient C_T tends to decreases with increasing Ω^∗ , and C_T tends to become large with increasing AR. Power coefficient C_P shows that the present phenomenon is suitable for low-speed windmills and waterwheels.

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In this paper, velocity distributions in the far wake to X/C=13.5 from the trailing edge of an NACA0012 airfoil flows are measured by using the hot-wire anemometer in wind tunnnel test. The Reynolds number based on the chord length of the airfoil and flow velocity is 4.0×10⁵ and the airfoil is under the high lift condition.Then, turbulence length scale as maximum scale of wake vorttex are calculated from the results by cross-correlation measurement of 2 points local flow velocities at X/C=13.0. Then, the characteristics of expansion of half width, velocity profiles in the far wake and turbulence length scales in X-direction and in Y-direction at X/C=13.0 are clarified.

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Binary power generation system using water as a working fluid has been proposed. This system is aimed to recover the low-grade waste heat such as the hot spring water; therefore, the assumed temperature of heat source is about 85 °C. The effects of turbine efficiency on the cycle performance were discussed with the theoretical calculations based on steam table. The calculations showed that the cycle efficiency and the electric power generation per 1kg hot water became almost double if the turbine efficiency increases by 0.2. Furthermore, the 10kW pilot plant with radial twin turbine and platetype heat exchangers for the evaporator and condenser was constructed. The power increase due to the increase of turbine inlet pressure was expected but the experimental result did not show the clear increase. The higher turbine inlet pressure resulted not only as the critical flow increase but also the decrease of the turbine efficiency. It was considered that the decrease of efficiency was due to the decrease of steam superheat. The more water droplet could be generated in the nozzle and turbine at the lower superheat and decrease the turbine efficiency.

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Wave energy can be converted into the electrical energy by using a wave energy converter. Impulse turbine for bi-directional airflow is a kind of air turbines for wave power generation. This turbine has a high efficiency in a wide range of flow rate thus, it can be converted the wave energy even with a large change in wave height. In addition, this turbine has a good starting characteristic because it can be obtained a high torque in low speed rotation. However, it has problems in maintenance and high production cost because of it complicated cascade. In this study, aiming to resolve this problem, an impulse turbine with a simple cascade was employed, and the turbine performance was investigate using by the computational fluid dynamics (CFD) analysis. As a result, it was found that the efficiency of impulse turbine with simple cascade is very close to the conventional impulse turbine, and the favorable turbine geometry has been clarified. The impulse turbine with a combination of setting angles of guide vane of θ=22.5˚, and setting angle of the rotor of γ=70˚, which obtained a peak efficiency η_P=45.6%, seems to be a suitable simple turbine shape.

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A twin-impulse turbine system has been developed for wave energy converter. However, an impulse turbine, which is used for a unidirectional flow, cannot obtain a high efficiency in reverse flow. A fluidic diode can be used to alleviate this problem. In this study, in order to improve the rectification performance, the performance characteristics of fluidic diode has been investigated by computational fluid dynamic (CFD) analysis. The commercial CFD tool, SCRYU/Tetra of Cradle Co. Ltd, is used to perform the CFD analysis. RANS equations are used as governing equations, and the standard k-ε model is used as the turbulence model. The computational domain is composed of a circular tube and fluidic diode and meshed with an approximately 1.5 million mesh elements. The pressure and velocity fields inside the fluidic diode are visualized and analyzed to obtain a deep insight about the flow rectification effect. As a result, it is clarified that the rectification characteristics of the fluidic diode do not depend on the length of the blunt body. The flow passage area through which the air flows inside the fluidic diode greatly affects the rectification characteristics.

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Hot spring thermal energy is a low enthalpy energy source, which is able to apply to extract the electrical energy converting by a heat engine. The power generation systems utilized the heat source of finite temperature and finite flow rate have unique characteristics that the maximal condition of thermal efficiency does not correspond to the condition of maximum power generation point. However, such thermodynamic theory has not introduced for the estimation and evaluation of the power generation in hot spring thermal energy. Therefore, for the evaluation and the development of the system, this paper shows the theoretical maximum available energy based on finite-time thermodynamics and proposes the generalized evaluation methods on the power generation system. Moreover, the parametric analysis is conducted using HFC245fa and HCFO1224yd(Z) to consider the adaption of low global warming potential working fluid on ORC system. The results clarified the effectiveness of the evaluation method and the possibility of equivalent power generation using HCFO1224yd(Z) as the alternate material as the working fluid.

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Hybrid Ocean Thermal Energy Conversion (OTEC) system is one of the OTEC system, composed of electric generating plant and desalination plant. The submarine topography of east side of Kumejima region is suitable for arranging pipelines to take in deep ocean water. Therefore, Kumejima region is one of the place that is expected to construct an OTEC plant, and already OTEC experimental plant is under running. This report is written about the performance analysis of Hybrid OTEC system that using oceanographic investigation results conducted by the fisheries training ship. The working fluid was using NH₃. A procedure is developed to maximize a net power of power system consisting of shell and plate type heat exchanger under the condition of designate power system. The maximum net power is given by minimizing the heat exchangers which consume most of a power system. The minimum value of objective function is about 19.9 m² / kW, when the temperature difference of warm seawater and cold seawater is 20.8 ℃（Jun. 2018）.

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The hybrid OTEC (H-OTEC) cycle is a combined system of a desalination and an OTEC which generates power using the temperature difference between the surface and depth in the ocean. The system is able to produce the electric power and the distilled water from seawater, simultaneously. The cycle uses low pressure steam as warm heat source generated by the flush evaporation in vacuumed condition instead of flowing the surface seawater that acquires: to prevent the performance degradation of the evaporator caused by the fouling due to marine organisms, to improve the heat transfer and to cost reduction by using the stainless steel instead of the titanium for an evaporator. In this study, the effects of each heat exchanger on the performance in the hybrid cycle were clarified by parameter analysis. It conducts to examine the effect of the working fluid flow rate and the evaporator heat transfer performance on the net power generation, exergy efficiency, and water production ratio. As the results, it is confirmed that the net power generation increases with working fluid flow rate. In addition, as the evaporator heat transfer performance increases, the power output and the exergy efficiency is increased, and the maximum performances confirmed in each condition is increased, respectively. Furthermore, the water production ratio increased with the increase in working fluid rate, and the specific power consumption decreased significantly.

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Ocean thermal energy conversion (OTEC) is a system to convert the ocean thermal energy stored as the vertical temperature gradient in the ocean into the electricity. In OTEC system, each component has the irreversible loss such as heat exchanger, turbine and pumps, and they are not negligible for the net power production. This research describes about the theoretical net power on OTEC considering irreversibilities in the heat engine, heat exchange process and fluid flow of heat source using the coefficient of irreversibility and effectiveness of heat transfer, and compared with the 30 kW OTEC experimental results using difference type of heat exchangers. As the result, theoretical results shows the equivalent irreversibility of the heat engine of the experimental apparatus in the case of the two heat exchanger, which shows the effectiveness of the theoretical study using finite-time thermodynamics.

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In Japan, depopulation is likely to have a negative influence on power infrastructure. As population decreases, electricity demand decreases and it becomes difficult to invest in renewal of power source. Furthermore, from the viewpoint of global warming countermeasures, investment in low-carbon energy technologies is required. In rural areas, these effects are noticeable because population decline rate is high. Therefore, using Hokkaido as a target area, this study aims to clarify how decarbonation of power supply system under demand decrease affect power source mix in the future. Power generation mix in time series and in each area and power generation cost was analyzed quantitatively by using dynamic optimization model for Hokkaido with scenarios of different type of electricity demand. As a result, in the high-demand scenario, the larger amount of wind power is introduced and power generation cost increases. In time series analysis, the reduction target of 2030 is achieved by fuel conversion. To achieve the reduction target of 2050, coal power is reduced according to demand decrease in the low-scenario, and wind power is introduced in the high-demand scenario. Further, power sources are distributed to various areas in the high-demand scenario and concentrates on Sapporo area in the low-demand scenario.

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In recent years in Japan, the energy self-sufficiency rate clearly has been low level (7.4% in 2015), the management of various companies including farmers is pressured as the price of crude oil rises due to the change in international situation and it leads to great negative effects on the Japanese economy. Also, Currently in Japan, agriculture tends to decline, there is concern that the food self-sufficiency rate will decline. The cause is that Japanese farmers are heavily influenced by soaring crude oil prices because it is mainstream to use heavy oil boilers when using hot water. Therefore, a plant factory has attracted attention. The plant factory controls the temperature inside the factory, so it needs a lot of energy. By supplying this energy with renewable energy, it is possible to construct an agricultural system that can secure a stable harvest amount without relying on heavy oil boilers. In this paper, we assumed the solar heat collecting system which supplies heat demand, which is the main energy demand in the plant factory by the solar collector, and its economic and environmental performance was evaluated.

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Ground source heat exchangers are used for utilization of ground source heat. This ground source heat exchanger is usually installed in the ground at a depth of about 100 m vertically. However, installation costs are expensive in Japan. It is preventing popularization of ground source heat utilization. The Horizontal Directional Drilling (HDD) method costs only a third of the vertical drilling in Japan. We set the ground source heat exchanger horizontally inside the permeable layer by HDD method at Saga. High heat exchange rate at heat exchanger can be expected by the groundwater flow. Experiment was carried out with constant inlet temperature and constant flow rate. Small Effect of groundwater flow Was confirmed by the experiment.

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Since the Great East Japan Earthquake occurred, it has attracted attention that power generation systems using waste biomass could be a feasible option to replace fossil fuels. The system can convert waste biomass such as garbage, paper, wood and so on into energy. Hence, it increases energy independence ratio in residential area. Since biomass has the characteristic of carbon neutral, the system can reduce CO2 emissions. However, conditions of waste biomass are different for their properties, so it is difficult to use as a fuel for power generation. Here, superheated steam gasification system is an effective energy conversion system, because it can handle wide range of waste biomass. When the syngas generated by gasification is applied to a gas engine CHP, high combined efficiency can be obtained. However, when analyzing superheated gasification power generation system using waste biomass, it was unclear how to operate the system due to the fact that the demand was not taken into consideration. Therefore, we constructed a platform for Superheated Gasification Power Generation System using Waste Biomass independent on the region and achieved user application.

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Carbon emissions intensities from power plants depend on fuel properties and plant efficiencies. Here, an attempt is taken for clarifying the effect of fuel chemical composition for the estimation of variations in CO₂ emissions. The unified assessment methodology is especially important for the comparison between various fuels, like coal and natural gas.

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IHI Corporation has developed an advanced PCC system with a novel amine-based solvent and IHI proprietary efficient packing, and CO₂ utilization technologies. At first half of this report IHI advanced PCC technologies is introduced and at latter half the IHI unique catalyst technologies for CO₂ utilization. In Australia, we launched an internationally collaborative PCC (Post Combustion Capture) demonstration project, we call PICA being an acronym formed PCC, and IHI, CSIRO (Australian research institute), AGL (Australian power company).Through the long term operation at this demonstration project under the practical conditions, i.e., using the flue gas of an operating brown coal-fired power plant, we have evaluated our integrated PCC technologies. During the operation, 90 % CO₂ capture ratio was achieved stably and other measured values were also kept stable. The results indicate that the PICA plant and the ISOL-162 solvent have sufficient stability and robustness to enable long term operation. Over the long term operation, practical studies of the emission evaluation were carried out. The emissions of amine and its derivatives from the outlet of the washing tower were measured on various wash-type conditions. The result clearly demonstrated that the amine emission from the system was considerably reduced and minimized by the application of the washing technologies. The demonstration results are explained in detail in the presentation. Further to CO₂ capture technologies, we are developing the CO₂ utilization technologies in considering that the geosequestration is not yet an option. With IHI unique catalyst, we confirmed that CO₂ was converted efficiently to methane as synthetic natural gas during 3,000hour operation.

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O₂/CO₂-blown gasification test were carried out with the 50 ton per day bench-scale test facility to verify syngas composition and slag discharge for the Oxy-fuel IGCC system which will be utilized for IGCC power generation with CO₂ capture. The main component, hydrocarbon and trace elements of the syngas were analyzed during the stable gasifier operation. The performance of the gasifier such as cold gas efficiency, were almost same as oxygen-blown gasification. Although the temperature of the gasifier fell with higher the partial pressure of CO₂ compared with the oxygen-blown, it was verified that stable discarge of the slag and reduction of the hydrocaron in syngas during coal property changing by optimizeing reductor/total coal ratio.

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A numerical simulation of coal gasification on an O₂-CO₂ blown coal gasifier was performed to demonstrate the numerical model implemented in the simulation code. Especially the extended Chemical Percolation Devolatilization model (ECPD) in which the chemical structure of coal was considered in the sense of the network-type model to capture the tar release, decomposition and polymerization was developed and implemented. ECPD was coupled with a gaseous phase elementary reaction model. The cases performed in this study were the conditions examined in the experiment with the laboratory-scale coal gasifier. Results showed that the simulated results such as temperature distribution and product gas composition showed good agreement with the experimental data. Moreover, the characteristics of the formation of chemical species including polycyclic aromatic hydrocarbons and soot was discussed in detail.

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As a gas turbine for high-efficiency oxy-fuel IGCC system corresponds to a semi-closed type gas turbine (GT), it is necessary to burn coal gasified fuel and oxygen near stoichiometric condition in CO₂-rich diluent recirculated as GT exhaust gas. Furthermore, there is concern that a very small amount of ingredient contained in fuel affects the purity of captured CO₂. In this study, to grasp the impurity (NOx) concentration in exhaust gas of exhaust gas recirculation, the atmospheric pressure combustion tests recirculating exhaust gas with a small diffusion burner are carried out and the effects of fuel composition (NH₃ and CH₄ concentration, H₂/CO ratio,) on the NOx concentration are examined. As the results, NOx concentration is concentrated to approximately 5 times by exhaust gas circulation. NOx concentration is affected by fuel composition and showed 1000ppm-dry or more each.

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MHPS has successfully developed the highly-efficient M501J, which achieved the world's first turbine inlet temperature of 1600°C, and started verifying operations using the verification facility in the MHPS Takasago Works in 2011. Thereafter, the M501J has been delivered all over the world, and have accumulated more than 750,000 Actual Operating Hours. In addition, to further improve the efficiency of the gas turbine combined cycle power generation (GTCC) and enhance the operability, we replaced the steam-cooled system for the cooling of the combustor and developed a new enhanced air-cooled system. This paper presents the development and operational situation of the state-of-the-art, high-efficiency gas turbine of MHPS and the development of the next-generation 1650°C class JAC (J Air Cooled) gas turbine using an enhanced air-cooled system as the core technology based on the technology adopted for the M501J.

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It is important to increase combustion efficiency of ammonia gas-turbine combustor. Concentration of unburnt ammonia depends strongly on combustor inlet temperature in the case of the previous combustor. Emissions of unburnt ammonia is high under 500℃ of combustor inlet temperature. In the case of rich-lean low-NOx combustor, concentration of unburnt ammonia does not depend on combustor inlet temperature. Low emission of unburnt ammonia of 15ppm (16%O₂) is recorded at 313℃ of combustor inlet temperature. In the case of rich-lean low-NOx combustor, it is thought that the gas-turbine without regenerative heat exchanger can apply high combustion efficiency to ammonia combustor. It means that it can be used for the larger gas-turbine systems.

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In order to reduce CO₂ emission from coal-fired boiler, it is expected that ammonia is used as a fuel which has no carbon content. In that case, it is concerned that NOx concentration in flue gas increases because ammonia has more nitrogen content than coal. With 10 MWth test furnace, 20 % ammonia co-firing test in lower heating value base was conducted. In previous study, ammonia co-firing was succeeded with NOx concentration as same as that of single coal combustion. In this study, co-firing test for analyzing effect of nitrogen content in coal and heat input on NOx was conducted. The results show that condition for reducing NOx concentration in NH3 co-firing is clarified.

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In this study, the flame propagation limit of premixed gas of ammonia, which is promising as a carbon-neutral energy carrier gas, and methane in turbulent fields was clarified experimentally in order to establish the technology for the mixing combustion of ammonia and methane, which is the main component of natural gas. The experiments were carried out with various range of the ratio of methane in fuel, equivalence ratio, and turbulence intensity using a constant volume vessel. From the experimental results, a map of the flame propagation limit was made. It has been found that the flame propagation limit expands with the increase of the methane ratio. In addition, we can see the tendency of flame propagation with the highest turbulence intensity was obtained at the equivalence ratio of 0.9, regardless of the methane ratio. This tendency is considered to be due to the diffusional-thermal instability of the flame surface for the pre-mixed gas with a low equivalence ratio.

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Due to a demand of the strict regulation of greenhouse gas emission by Paris Agreement, CO₂ emission from thermal power generation has to be reduced dramatically. Hydrogen has an important role to realize the low carbon society. It is important to establish large scale power generation systems which can utilize a large amount of hydrogen efficiently. As a future hydrogen combustion turbine power generation system, an Oxy-fuel cycle, proposed by Jericha at Graz University of Technology, and conventional combined cycle were analyzed by using EnergyWin, the thermal efficiency analysis software. The results show that thermal efficiency (LHV) of the Oxy-fuel cycle with H₂/O₂ stoichiometric complete combustion is 10 point higher than combined cycle with H₂. Even considering O₂ production energy, thermal efficiency for Oxy-fuel cycle is higher. It indicates that Oxy-fuel cycle has a potential to achieve high efficiency. Furthermore, the effects of gas turbine inlet temperature, pressure, compressor adiabatic efficiency and gas turbine polytropic efficiency were clarified. The result shows that the factor of gas turbine inlet temperature or pressure has greater effect on thermal efficiency than compressor adiabatic efficiency or gas turbine polytropic efficiency.

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As a method of stably discharging molten slag from slag holes, an Integrated coal Gasification Combined Cycle, IGCC process using slag taps has been studied. The flow state of the slag varies depending on the shape of the slag tap and the viscosity of the molten slag. In this study, flow simulations were conducted using the lattice Boltzmann method considering the temperature dependency of viscosity. As a result, it was revealed that stable slag discharging conditions and the difference in flow due to the influence of viscosity were observed.

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The combustion of the diesel engines occurs during the dilution process when burning spray mixes with the air. Some of the issues to be solved are, residue of the air which cannot be utilized for combustion and the necessity of exhaust gas aftertreatment, because the gas burns before they are mixed sufficiently. These issues exist mainly because the existing fuel injection devices do not change the direction of injection, or the pattern of the fuel spray. Up to now, fuel injection technologies such as a pressurization of injection, or using multiple small diameter holes have been playing a big role for diesel combustion. However, to achieve the further improvement of the thermal efficiency and to cut down on the amount of exhaust, a breakthrough approach is necessary. The breakthrough can be realized, in addition to the methods mentioned above, by varying the pattern or the penetration of the spray during the injection in seamless manner. This will bring us a shorter burning time thanks to a rapid mixture, and utilization rate of the air will also be improved. Accordingly, this new method will boost the output power, reduce or suppress the combustion in high concentration zone, and reduce the exhaust gas. In gasoline direct injection engine also, with the rapid mixture knocking can be avoided by closing the timing of injection and of firing, which allows us to have the high-compression and the improvement of thermal efficiency. Based on the idea above, an architecture for dynamic scattering spray generation of fuel injection device have been considered, which will be explained in this paper.

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Reduction in CO2 emission is strongly requested in power generation today. Efficiency increase in power plants is the most direct and effective measure to reduce CO2 emission. Only those new units which can satisfy high efficiency level are allowed to be constructed. Existing plants are also requested to comply with similar high efficiency level within a certain period of time. Modification of old plants to higher efficiency plants is urgently needed, and the application of solid oxide fuel cell (SOFC) is one of the promising approaches to achieve this purpose. By combining SOFC, and by minimum modification of the existing conventional power plant (Boiler-steam turbine combination), the plant efficiency can be greatly improved. In the present study, repowering of existing plants is considered by means of integrating with a non-pressurized SOFC, and thermodynamic feasibility of the repowering method was numerically studied. The high temperature exhaust gas from the SOFC is used separately for steam generation and for superheating to assist the boiler. A convective evaporator and fuel burner are additionally equipped to handle the SOFC exhaust gas adequately for the boiler operation. This configuration enables to install the SOFC to fully or partly support the heat load of the boiler. The numerical results indicate that the net efficiency of the combined system reaches 72.8% (LHV) by fully utilizing the exhaust heat of SOFC. At this point, the installed capacity of the SOFC is 4 times as large as the capacity of the existing steam turbine.

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This report sorts out the indices of performances and additional expenditures of power balancing operation of thermal power plant during the massive introduction of intermittent renewable energies. The efficiency of the 700MW class coal fired power plant during the partial load operation and throttle valve control operation is calculated by the material and heat balance analysis; the calculated efficiency is applied to the basic performance of the coal fired power plant in the demand – supply balance analysis. By applying the indices of the low load LFC, Load Frequency Control, performance the demand- supply balance of the supposed balancing group (IEEJ standard model, AGC30 model) is analyzed. In the case that the coal power plant is operated within the low load condition, LFC ability is performed by the throttle control operation; the throttle control is responsible for the possible failure of the plant. The expenditure of substituting the failure of LFC of coal plant is calculated. The substitution by the LNG steam cycle plant consumes much amount of fuel gas compared to the case that the GTCC is selected as the substitution.

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A high-efficiency coal-fired power plant, calld an Advanced Ultra Supercritical (A-USC) is being developed. A-USC improves the efficiency to 46 to 48% and reduces CO₂ emissions by 10% or more by improving main steam conditions by 100 °C or more compared to conventional USC. Ni-base superalloys is one of the possible candidates to replace the ferritic steels. In addition, lately, with the introduction of a large amount of renewable energy, it is suggested that coal-fired power plant requires the output adjustment operation to adjust supply and demand in the future. However, it is expected that the output adjustment would induce fatigue damage in which the oxidation of material interacts. So far, it has been clarified that the fatigue crack growth rate of alloy 617 in the 750 °C steam environment depends on the cyclic loading frequency, and it was found that crack propagated along grain boundary under lower cyclic loading frequency. Since selective oxidation of grain boundaries was observed on the fractured surface, it is thought that such oxides contributed to the reduction of grain boundary strength and cracks progressed selectively at grain boundaries under slower cyclic loading frequency.

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It was reported that the fatigue crack growth rate of alloy 617 and 625 showed cyclic loading frequency dependence in a high temperature steam environment at 750ºC. In particular, in the alloy 617, the crack path becomes intergranular in the lower loading frequency range, and the growth rate is accelerated. In this study, elemental and crystallographic analysis of the tips of the intergranular cracks propagated under two different loading frequency conditions were conducted by transmission electron microscopy. It was found that Al-enriched and Cr-enriched oxides were formed in the crack tip under both conditions. In addition, Kernel Average Misorientation (KAM) distributions evaluated using transmission electron backscatter diffraction technique indicated that the width of the high KAM value region near the crack was narrow. Therefore, local oxidation morphology and deformation behavior under both conditions showed similar tendency, and it corresponded with the crack growth rate.

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The rifled tubes which have high-cooling capability are adopted for vertical furnace water wall tubes of USC sliding pressure operation once-through boiler. To improve the boiler performance and reliability, it is effective for lowering mass velocity of furnace tube inside. In such case, rifled tubes are required to suppress the heat transfer deterioration phenomenon at supercritical pressure and also DNB (Departure from Nucleate Boiling) at subcritical pressure. In this research, we first screen and developed the rifled tube geometry by re-examining the past experimental results and performing CFD analysis. Finally, we determine new rifled tube geometry by experimental verification of its performance.

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For long term reliability of pulverized coal-fired boiler, it is important to predict boiler tube temperature under operation. In this development, test tubes are installed in a large scale coal combustion test facility, and detailed data such as tube temperature, cooling water temperature, etc. is acquired. Also, tube temperature prediction method using a numerical simulation is verified.

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