What we can express about the overall combustion phenomena is summerized by means of numerical simulation. Recent methods on numerical analysis of combustion characteristics are studied for gas, liquid spray, and pulverized coal fuel. Lagrangian and Eulerian approaches for the understanding of two phase flow such as spray and pulverized coal combustion are then compared.
Coal pyrolysis is also described by models based on the molecular structure. Not only a wall function model, but also low Re number model are applied for wall boundary treatment. The following submodels are furthermore shown; LES (Large Eddy Simulation) and k-ε two equation model, reduced combustion scheme for detailed reaction model, radiative heat transfer, soot formation, NO production and drop breakup mechanism of liquid spray.

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Energy is the basis of industrial civilization. Without it, modern life would cease to exist. The important point is that limited fossil fuels are converted into energy in a more efficient way. One of the most effective conversion systems is a gas turbine, which is a major power source used in the generation of electricity. A gas turbine is comprised of three main sections a compressor, a combustor, and a power turbine. Compressed air and fuel are burned in a combustor, and the resulting hot gas is allowed to expand through a turbine to perform work.
Thermal efficiency of the gas turbine increases with the rise of Turbine Inlet Temperature (TIT). TIT is, however, limited with the heat-resisting temperature of the first stage nozzle and turbine blades. This physical limit is always climbing with the advances in materials technology.
System design including gas turbine has also been developed vigorously. Cogeneration is the system that supplies not only electric power but also steam or hot water. The application of this system has been popularized for both society and industry.
As a present trend, a new concept system that was named “Chemical gas turbine system” and the latest actual machine “501 G” are introduced.

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The influence of CO₂ and H₂O gases on high temperature oxidation of CVD-SiC films on C/C composite are investigated in order to apply for the high temperature materials to a methane-fuel gas turbine. An oxidation test at 1, 700°Cin an atmosphere containing large volumes of CO₂ and H₂O gases is successfully attained by using the Xe-lamp heating method, and it is possible to measure the mass change of the specimen preventing the reaction at the contact spot with a sample holder. This paper describes that H₂O gas hastens theβ-cristobalite transformation of the amorphous SiO₂ formed on the SiC film by high temperature oxidation, and this crystallization causes cracking of the SiO₂ films during cooling after heating. The oxidation rate of SiC is also accelerated by the existence of CO₂ and H₂O in the atmosphere at 1, 700°C.

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We developed a two-dimensional combustion model to predict the transport phenomena in semicoke burning at the surface in a CDQ (Coke Dry Quencher) pre-chamber and blast furnace. Experiments and numerical simulation were carried out to analyze the transport phenomena in a spherical semicoke particle burning in a laminar gas stream. The model assumes that the semicoke particle is a packed bed of micro semicoke particles, and the combustion of fixed carbon is calculated as the char. Coke pyrolysis is also estimated involving the deposition and decomposition of tar and the combustion of VM (volatile matter). Gas flow in the packed bed and gas phase around the particle are calculated by Darcy's equation and Navier-Stokes equation, respectively.
The effect of heterogeneous and homogeneous reactions of the single semicoke particle on its property is calculated by the control volume method (CVM). The analysis shows that the combustion of the semicoke particle is governed by boundary layer diffusion and the homogenous reactions prevent the semicoke particle from consumption by heterogeneous reactions.

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We have proposed a novel high temperature gas cleanup system in which sulfides contained in the syngas are removed and transferred into the carrier gas through a molten carbonate membrane. On the syngas side of the membrane, gaseous sulfide is absorbed into molten carbonate to produce sulfide ion, and the reverse reaction proceeds on alternate side, i. e. carrier gas side, of the membrane with CO₂ and H₂O contained in the carrier gas. With this system, sulfides thus removed from the syngas can be concentrated into the carrier gas employing higher CO₂ and H₂O concentration in the carrier gas. In this article, we present the results of preliminary experiments to demonstrate the feasibility of this concept. Experimental results show that over 50% of inlet 0.7% H₂S is removed from simulated syngas in a flow channel whose length is only 4cm. The maximum sulfide concentration at the exit of the simulated carrier gas is about double of that at the simulated syng as inlet, and degree of concentration are expected to become higher by reducing simulated carrier gas flow rate. The reaction of gaseous sulfide with molten carbonate membrane is shown to be prompt, and the apparent diffusion coefficient of sulfide ion migrating through the membrane is estimated to be c. a. 3×10^-11 [mm²/s].

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It is an important issue to measure the exact surface temperature of a wall subjecting to hot impinging gas flow in combustion. In this study, the surface temperature was computed by an inverse method. Airbag inflators were deployed in the closed tank and the hot impinging gas flow to the tank wall was simulated in the experiment. Since the direct measurement is largely affected by the hot impinging gas flow, the temperature inside the tank wall surface was measured by an thermocouple. By utilizing these in-wall temperature data as the boundary conditions, the surface temperature was inversely computed.
The transient surface temperature was computed by the inverse method. Then the heat flux to the wall and heat transfer coefficient was estimated. These results are reasonable compared with the actual experimental phenomena. Therefore, the surface temperature might be measured by the inverse method without the effect of the impinging hot gas flow.

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In order to investigate heat transfer in a carbon dioxide recovery furnace, radiative heat transfer was studied in a boiler furnace including water vapor, carbon soot and high concentration carbon dioxide. Numerical analysis was carried out using the Radiation Element Method by Ray Emission Model, REM², which can treat an arbitrary three-dimensional configuration, temperature distribution and participating media including anisotropic scattering particles. Heat flux on the boiler walls increases with increasing concentration of carbon dioxide, however, the concentration of more than 50% volume fraction reduces the flux slightly due to the greenhouse effect of participating gases. The heat generation rate or divergence of radiative flux decreases with increasing the concentration of carbon dioxide, which means an increase in flame temperature for a practical furnace. The soot in a flame increases the heat flux on the wall, however, relative effects of the carbon dioxide on the heat flux and heat gen eration rate decrease.

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In this study, the authors attempted a simulation technique of radiation-convection heat transfer in the high temperature fields of industrial furnaces, boilers and gas turbine combustors. The convection effect is analyzed by differential equations, but the radiation effect is analyzed by an integral equation. So, both effects are difficult to arrange using the same type of equations. Then, the authors introduced the Zone Method and Monte Carlo Method for integral equation of radiation effect and the Finite Difference Method for differential equations of convection effect. A three-dimensional analysis of a high temperature furnace was performed by this simulation technique to obtain its temperature distribution. Furthermore, another radiation-convection heat transfer analysis in a low temperature living room was performed by the same technique. Finally, the authors tried to develop computer software for radiation-convection heat transfer, and described their idea of software construction for the above.

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We applied a three-step reduced mechanism that is introduced from a detailed mechanism to calculate fuel-rich methane-air turbulent diffusion flame characteristics for the purpose of saving calculation time. We obtain good agreement between calculated and measured values on temperature, carbon monoxide, and carbon dioxide distributions in the combustor except for the near flame front. It is hard to calculate very perturbed areas like a flame front because the κ-ε2-equation model, used in this calculation, is modeled based on isotropic turbulence and isothermal fields. We also obtain good agreement carbon monoxide distribution, which was formed well in fuel-rich conditions by using three-step reduced mechanism. It is impossible to calculate carbon monoxide distribution by using one-step reduced mechanism, which is mainly used on combustion simulation. For the above reason, numerical simulation using three-step reduced mechanism is a more effective method to calculate the characteristics of turbulent diffusion flame because it is able to calculate a local fuel-rich condition.

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Ignition properties of pulverized coal clouds are examined under similar conditions to those of an industrial burner by using newly developed experimental equipment. Pulverized coals were injected into a preheated gas flow formed by catalytic combustion. The coal was ignited in an open area. Observation with a high speed camera showed that coal flames were formed and propagated from ignited particles heated by the gas flow. The flames were distributed at first, then the fiame grew and combined with other flames to form a continuous flame. The continuous flame was formed rapidly from the ignited particle, when the coal concentration increased. The devolatilization rate was accelerated when coal concentration increased, because of increasing of radiation heat transfer from the propagating flames.

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Coal is one of the important energy source because of its large reserves. However, emission of carbon dioxide from coal combustion is larger than other fossil fuels, and so development of clean and high efficiency coal combustion systes with carbon dioxide recovery is needed. Pulverized coal combustion with oxygen and the recycled flue gas is one of promising system to recover carbon dioxide from the exhaust gas of boilers for reducing the emission of carbon dioxide to the atmosphere. In order to develop this type of new coal combustion system, it is important to study the fundamental phenomena of coal combustion. Our group is making experiments not only using bench-scale pulverized coal burners, but also using microgravity condition in order to elucidate the fundamental mechanism of coal combustion. In this paper, studies on the flame propagation mechanism of pulverized coal clouds and on the ignition mechanism of single coal particle are introduced.

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In order to develop a highly efficient gas turbine system using a Rich-Lean two stage combustion, it is essential to elucidate the combustion characteristics and NO_x formation in this system. In the present study, this two stage combustion system was simplified by two basic flame configurations; the first stage was the one dimensional premixed flame of fuel-rich mixture of methane and air, and the second stage was the counterflow flame of burnt gas from the first combustion and preheated air. Numerical calculation using detailed chemical kinetics GRI-Mech shows that the NO formation at first combustion is very small under fuel-rich combustion conditions, and the final NO emission of Rich-Lean two stage combustion is controlled by the second combustion. In addition, the flame temperature of the second combustion is considerably low compared with single-stage combustion, and NO formation is reduced effectively.

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It is known that EGR (Exhaust Gas Recirculation) is effective to reduce NO_x emission from a combustion system. In this study, an EGR system is applied to a kerosene spray combustion in a swirl type combustor. In paticulay, this paper focuseS the effects of the EGR ratio and the introduction method of EGR gas on combustion characteristics such as NO concentration and gas temperature. With a high EGR ratio, a blue flame is formed since the evaporation of kerosene spray is promoted by hot EGR gas. Also, the use of secondary air is effective for NO reduction. NO concentration decreases with increasing EGR ratio, while combustion gas temperature is dependent on the introduction position of secondary gas. In the experiment, when the EGR gas is introduced into primary air, and secondary air is introduced at 95mm from combustor inlet, low NO emission is achieved without temperature reduction of combustion gas.

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An advanced low NO_x combustion technology, FDI (Fuel Direct Injection), has been developed. FDI combustion technology reduces thermal NO_x substantially for combustion of high preheated air over 1, 000°C. The principal of its ultra-low NO_x combustion is the separate and direct injection at high momentum of combustion air and fuel gas into the furnace. By directly injecting air and fuel, selfinduced flue gas re-circulation is substantially enhanced, reducing the formation of thermal NO_x to a substantially low level. Applied to a regenerative burner system that utilize high air preheat for fuel saving, the FDI combustion has demonstrated more than 90% NO_x reduction.
As compared to conventional ones, simple and compact regenerative burners have been developed. These new regenerative burners have been designed solely for the use of FDI low NO_x combustion technology. Field tests of various furnaces such as forging, re-heating and aluminum melting have successfully demonstrated substantial low NO_x level below 100 ppm (at 11% O₂) by the FDI technology with fuel saving of 20-60%.

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We propose unit furnace to construct general data base for practical industrial furnace design. According to this philosophy we built test furnace and evaluated comparatively the experimental results and calculation results in high-temperature air combustion. The absolute value of NO gained by using a general CFD code has many uncertain points, but the tendency of the NO value agrees with measured value. Therefore, we can use the calculation results to understand tendency and predict NO_x value.
We constructed many data bases for high-temperature air combustion including techniques for making the uniform furnace temperature, raising the furnace temperature and low NO_x formation.
We designed a practical high performance industrial furnace using the above mentioned data, then we achieved 30% of saving energy, over 20% of downsizing and clearing the environmental regulation of NO_x value.

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The authors have studied regenerative heat exchanging systems in order to increase the thermal efficiency of combustion heating systems. In a study of regenerative burner systems, the authors have developed two types of low NO_x burners. One is a radiant tube burner, the other is a direct firing burner. As a result, the NO_x emission of both burners has been reduced to less than one-fourth provious levels. In a study of rotary regenerator systems, the rotary regenerator is sometimes more effective than regenerative radiant tube burner. In a study of non- oxidizing heater systems, the authors have developed a regenerative N₂ jet heater. This system, an N₂ jet heater with regenerative burner, can heat N₂ gas up to 1, 773K, and can recycle the almost 100% of the high temperature N₂ gas using a trio of heaters installed with two regenerative heat exchangers inside the combustion chamber. This system reduces the furnace length to less than one-fourth previous levels, and increases the thermal efficiency of furnaces to the same level as regenerative radiant tube burners. This paper presents an outline of these systems, and describes the effect of theirs use on the steel products furnaces.

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CO₂ management technology is one of the most important issues for the global environment. This paper describes the feasibility experiment that CO₂ can be reformed by direct conversion into fuel-like species with the aid of plasma reactions. Here, CO₂ pure gas and (CO₂+H₂) are discharged into an expansion chamber raising a plasma reaction furnace and the chemical species produced by plasma direct mass conversion are detected by a combined time-of-flight and mass spectrometer technique. As a result, fuel-like species such as CO, CH₄, CH₃OH are abtained with fairly good COR (Coefficient of Reforming), which is getting better by adding Ar molecules as activating reagents.

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A new concept of a gas turbine/steam turbine combined cycle system, referred to as the “Chemical Gas Turbine” system, is proposed in order to raise the total thermal efficiency of existing systems. The characteristics of this system are a combustor operating under fuel-rich conditions, and C/C composites material adopted for fabrication of the turbine blade. This system consists mainly of two gas turbines and a steam turbine, and has advantages that exergy loss and total NO_x products are decreased by means of fuel-rich combustion.
The purpose of this work is to demonstrate the advantage of the chemical gas turbine system, and the thermal efficiency of this system and total NO_x products are simulated. Besides, we convert a commercial small-scale gas turbine into the micro chemical gas turbine, and develop combustor for fuelrich combustion of methane-air and related equipment. After that, we examine the fundamental working characteristics of the assembled system. The results show th feasibility of such a chemical gas turbine system.

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Thormochemical recuperative combined cycles with methane-steam reforming are proposed for improving their thermal efficiency and for peak-load leveling. For targeting higher thermal efficiency, a cycle with methane-steam reforming reaction heated by gas turbine exhaust was analyzed. The inlet temperature of gas turbine was set at 1, 350°C. Low-pressure steam extracted from a steam turbine is mixed with methane, and then this mixture is heated by part of the gas turbine exhaust to promote a reforming reaction. The rest of the exhaust heat is used to produce steam, which drives steam turbines to generate electricity. The effect of steam-to-methane ratio (S/C) on thermal efficiency of the cycle, as well as on methane conversion, is investigated by using the ASPEN Plus process simulator. The methane feed rate was fixed at constant and S/C ratio was varied from 2.25 to 4.75. Methane conversion shows an increasing trend toward the ratio and has a maximum value of 17.9% at S/C=4.0. Thermal efficiency for the system isabout 51%, which is 1% higher than that calculated for a conventional 1, 300°C class combined cycle under similar conditions.
A thermochemical recuperative combined cycle is designed for peak-load leveling. In night-time operation from 20: 00 to 8: 00 it stores hydrogen produced by methane steam reforming at S/C=3.9 to save power generation. The gas turbine inlet temperature is 1, 330°C. In daytime operation from 8: 00 to 20: 00 the chemically recuperated combined cycle operated at S/C=2.0 is driven by the mixture of methane and the stored hydrogen. The output at night-time operation decreases down to 0.70 of that for a combined cycle operated at constant load with the same methane feed rate, whereas daytime operation generated power 1.26 times larger than that of the combined cycle.

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Sealant is designed so that in the range of low-shear rate, the viscosity is very large, and in the range of high-shear rate, the viscosity is very small. The Ellis model is applied to Polysulfide sealant. Parameters in this model are determined with a rheometor. In the high shear rate region, the viscosity depends much on the temperature. But in the low-shear rate region, the viscosity does not depend on the temperature. The pressure drop of the pumping sealant through the pipe and the minimum pipe diameter required to discharge from tank under absolute zero pressure are calculated and their results are found to be reasonable compared with actual plant data. The compounds of precoated fillers are much more thixotropic than those of uncoated fillers.

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In order to obtain an insight into the mechanical composing process of particulate materials in a high-speed elliptical rotor type mixer (θ-composer), a 3-dimensional numerical simulation (PEM) was carried out to predict the dynamic behavior of the core particles in the device. Mono-disperse spherical particles with a diameter of 200 μm were charged into the mixer as cores. The variation of the contact forces acting on the particles and the number of contacts in time were analyzed.
The motion of the particle bed in the mixer without rotor predicted by the PEM simulation is in good agreement with that actually observed one. Thus, this particular simulation seems to be reasonable. The compressive force exerted on the particle bed has a maximum at an angle of around 45°in terms of the horizontal inclination of the long axis of the elliptical vessel. The highest deformation forces are found for the particle-rotor contacts as compared to the forces arising from the particle-particle and particle-vessel wall contacts. It is clarified that the force acting on particles due to interaction with the rotor strongly depends on the rpm of the rotor. Therefore, control of the rotational speed of the rotor is important for controlling the deposit layer formation in the θ-composer.

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A prediction method is presented for salt effect on vapor-liquid equilibria by a solvation model. The solvation model assumes that the activity coefficient for vapor pressure depression has additivity with each activity coefficient of each solvent in pure solvent + salt system. In this work, to describe more accurately the behavior of the activity coefficient which contributes to the vapor pressure depression, the solvation model introduces a correction factor for estimation of the activity coefficient for vapor pressure depression. The introduced function with correction factor has the following characteristics; (1) peak activity coefficients can be expressed, (2) no correction is done for pure components, and (3) extension to a multi-component system is possible. As a result, the presented method improves the prediction accuracy of vapor pressure depression or boiling point raising of binary solvent mixture + salt systems and boiling point of ternary solvents + salt systems by using the correction factor d etermined from a binary solvents + salt system.

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Two dimensional numerical analysis based on current distribution has been calculated for electrolytic etching of lead frame from both sides.
With an increase in anode width, the side etching widths become smaller, both for the forced primary and the secondary current distributions. A residual hump forms for the forced primary current distribution of 200μm anode width. With an increase in current density, the side etching widths also become smaller. With an increase in foil thickness, the side etching widths become larger and etched shapes become round, both for the forced primary and the secondary current distributions.
A residue of 200μm anode width is eliminated completely with the aid of an isolated resist located from x=45μm to 95μm. This residue of a 200μm anode is also eliminated completely with photo resists of more than 30μm thickness.

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A mathematical model is developed for an industrial stirred-bed reactor for gas-phase propylene polymerization. The basic feature of this process is that latent heat for evaporation of liquid monomer is used for the removal of heat of reaction, and then the evaporation process of liquid monomer plays an important role. Dynamics of the recycle condenser and evaporation of liquid monomer in the reactor are taken into account in the model. The dynamic behavior of a pilot plant is described well by the developed model. From simulation studies by the model, it is shown that the conventional operations are carried out under thermally unstable steady states, and consequently feedback control is essential to stabilize the process operation.

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Activated carbons with high specific surface area were prepared from beer lees by chemical activation with KOH. We examined the influence of the preparation conditions, such as temperature and impregnation ratio, on the pore structure of the prepared activated carbon, and examined the adsorption ability of benzene and acetone on the prepared activated carbon.
The specific surface area increased with an increase in carbonization temperature up to 800°C and decreased at 900°C because of excess activation. Itreached a maximum value at the impregnation ratio of 2.0. The activated carbon, which was prepared at the carbonization temperature of 800°C and at the impregnation ratio of 2.0, had very high specific surface area of 2, 440mm²/g. It was found that KOH worked effectively as the activating reagent in two temperature ranges, below 500°C and above 600°C. The amount of benzene and acetone adsorbed on the prepared activated carbon were much larger than that on the commercial activated carbons.

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Flocculation and compaction of a highly concentrated suspension by using the thermosensitive polymers which show a hydrophilic/hydrophobic transition by heating their aqueous solutions is examined. Poly (N-isopropylacrylamide) (polyNIPAM) and the copolymers of N-isopropylacrylamide and acrylamide (polyNIPAM-co-AAM) were synthesized as thermosensitive polymers. Kaolin suspen- sions of 125kg/m³-375kg/m³ were used, and flocculation and compaction were performed by the plunger test. A polymer solution of the desired concentration was mixed with kaolin suspension at a temperature below the transition temperature of polymer to adsorb the polymer on the surface of kaolin particles. Then, the mixture was transferred to a cylinder immersed in a water bath heated above the transition temperature of the polymer. The plunger was thrust into the mixture at a constant speed. Even if the adsorbed polymer transformed into a hydrophobic polymer by heating above the transition temperature, the formation of flocs was observed, and the compaction was occurred by dosing the polymer exceeding 0.006kg/kg-kaolin. Sludge bulkiness, which describes the volumetric proportion of sludge and solid, reaches almost 3 at a polymer dosage of 0.03kg/kg-kaolin, and it was difficult to thrust the plunger into the sludge any more. Such phenomena of flocculation and/or compaction are explained by the hydrophobic interaction of thermosensitive polymer.

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In order to realize quantitative elucidation, as well as simulate complex formation at the liquidliquid interface, 8-Sulfonamidoquinolines (C_nphSAQ) were calculated by both a semi-empirical molecular orbital method considering solvent effect, and molecular dynamics at the water-toluene interface. The MD calculations support the fact that interfacial area occupied by a molecule (ca. 60AA²) obtained by the measurement of interfacial equilibrium of C_nphSAQ is consistent with projected area of sulfonamidoquinoline moiety. Furthermore, examination of the quantitative structure property relationship (QSPR) between energy difference in interfacial adsorption and interfacial adsorption equilibrium constant can obtain good linear correlation.

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Zinc oxide is a promising material for the transparent electrodes and color development lasers in the ultra violet region. This zinc oxide film is prepared from DEZ and N₂O with Plasma CVD. The safe dopant of TEB is used. The minimum resistance is found to be 4.55×10^-3Ω·cm at substrate temperature of 300°C. This minimum resistance corresponds to an increase in electron density and the film shows high c-axis orientation.

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