In this paper, in order to study the effect of excess attenuation of railway noise due to detached houses, the two methods to evaluate single event sound exposure level (SEL) are examined. One is SEL estimated by using the maximum sound pressure level from Shinkansen trains, the other is SEL obtained by integrating the sound pressure level during a train pass-by. It is found that there is difference between two SELs and that linear relationship between the difference and the grazing angle φ or building area ratio γ can be seen in some cases.

The environmental conservation at the waysides of railway lines is one of the important issues. Noise barriers are widely used to reduce the wayside noise along railway lines. Studies on the effect of the barriers have been conducted extensively. In the studies, noise reduction due to the noise barrier with the shape of which is uniform in the longitudinal direction has been investigated. In order to further reduce the wayside noise, the noise barrier made to be partially higher. In this paper, an attempt is made to examine the effect of partial change in height of noise barrier on the wayside noise using scale model experiments. It was found that (1) the effect of partially-higher barrier on the wayside noise is more apparent at positions higher than the sound barrier and (2) the effect within the distance from the railway up to 50m is almost equal to that of a barrier with an infinite length when the total length of the partially-higher barrier is longer than 50m.

The noise measured close to a tunnel portal of Shinkansen consists of the noise from the tunnel portal and the noise in open section. The noise from the tunnel portal and the noise in open section make the noise level much higher than the noise level at the points away from the tunnel portal. A model to predict the noise from a tunnel portal has been proposed, which was arranged in combination with road traffic noise prediction model and Shinkansen noise prediction model. However, the model has not been well-validated in Shinkansen noise around tunnel portals. In addition, recently, the propagation of the noise from tunnel portals tends to be more complicated because there is a tunnel entrance hood to reduce micro pressure wave, and the noise is also radiated from the openings on the tunnel entrance hood. In this paper, the results of the sound pressure levels measured around the tunnel portal will be discussed, and the comparison of the measurements with the results obtained with this prediction model will be carried out.

We have studied the analysis method of interior noise in railway cars by means of ray tracing method. By using a point source as an input which simulates the speaker test, the analysis result of sound decay along the longitudinal direction of the car didn't always match the measurement result. It is possibly because the wave character of the sound cannot be strictly simulated by the ray tracing method. On the other hand, in simulation for the running condition by applying multiple sources of which amplitude were estimated from the measured vibration of the interior panels, the tendency of the sound change by the difference of interior condition matched well between the analysis and the measurement.

Aerodynamic bogie noise of Shinkansen train is generated from the bogie section enclosed by side covers and ground. In this study, we studied the acoustic characteristics of the bogie noise, i.e. gain characteristics and the acoustic path, by using 1/7 scale train model in an-echoic room. Based on the reciprocal theorem, several microphones were installed inside the bogie cavity and a loudspeaker was installed besides the train model. It was found that noise generated from the bogie cavity is amplified especially in low frequency regions in spite of the side covers. Results of the impulse response obtained by TSP signal show these amplification is mainly due to the ground reflection.

When roughness on rail heads or wheel treads is larger, force on both a wheel and a rail becomes greater. There is some possibility of nonlinear vibration transmission from a rail to a concrete structure when the rail is excited by the greater force. To verify the characteristics of nonlinear vibration transmission, excitation tests using by an impulse hammer and an excitation apparatus were carried out in a mock-up viaduct and a test track. The excitation apparatus can excite a rail with larger force. The results of the tests show that the frequency responses on rail vibration are divided into two categories; the force less than 10 kN and that more than 30 kN. The vibration transmission between the rail and the mock-up viaduct and the noise under the viaduct in the force less than 10 kN also differ from those in the force more than 30 kN. The resonance frequency due to the rail mass and the rail pad stiffness in the rail vibration is changed as the excitation force changed. This fact indicates that these phenomena might be due to nonlinearity of the rail pad stiffness.

Reduction in aerodynamic noise emitted from a pantograph is an important subject for environmental preservation and speed-up of Shinkansen trains. In this study, an effect of pantograph horns to the aerodynamic noise characteristics was investigated. As a result, it is clarified that the pantograph horns affect aerodynamic noise properties significantly and shape improvement around the joint area of the pantograph head and the horns is an important factor for the reduction of aerodynamic noise.

In this study, an estimation method of the main factor of large vibration of the construction machine was considered by using modified operational transfer path analysis (OTPA) with principal compnent (PC) model. In the method, we attempted to determine which input force to the frame or the resonance of the rear frame made the high contributing PC to the response point vibration. Simple construction model was employed for the analysis and the vibration of cab and multiple points of the rear frame were measured simultaneously for applying OTPA. Through the mode shape correlation between the calculated high contributing PC mode at the operational condition and the vibration modes, main factor increasing the cab vibration could be estimated well.

This paper presents a structural model construction for statistical energy analysis (SEA) using FEM. Identigying SEA parameter regardless of the excitation method is demanded effectively. The proposed method is based on a combination of SEA and vibration response by random vibration analysis or large mass method. These method are effective on an analytical cost performance for base excitation compared with the conventional force excitation method that is called rain-on-the-roof-exctation. In this study, the proposal method is validated through the two types of model, (i) simple flat plate consisting of one subsystem, and (ii) an L plate consisting of two subsystems. As a result, the method is shown to work quantitatively well to the internal loss factors and qualitatively well to the coupling loss factors.

In this study, we considered a method for selecting high contributing body panel vibration mode to the interior noise utilizing operational TPA (OTPA) . Simple vehicle body model was employed and operational test was carried out by using two exciters. Acceleration vibration at multiple points on the each body panel and the interior noise were measured simultaneously as the reference and response signals for OTPA. Subsequently, high contributing principal component mode of each body panel to the interior noise was obtained in the OTPA using principal component model. Finally, high contributing body vibration modes were extracted in many body modes by associating the high contributing PC mode of each panel with them.

Natural acoustic frequency of one dimensional duct partitioned by a perforated plate was clarified to come down with decreasing an aperture ratio experimentally and analytically. In order to clarify the reason, the sound propagation experiment was conducted. As a result, it was clarified that the smaller the aperture ratio was the longer the sound arrival time became. This is equivalent to the getting long of the duct and the natural acoustic frequency can be considered to become low.

Acoustic characteristics of centrifugal impeller was investigated in experiments by using the transparent wall. It is cleared that the transmittance of the transparent wall is gradually decreased with the pressure increment. And the variation of the transmittance is different with the sound frequency. By using the transparent wall, the sound source characteristics of the fan is cleared in upstream and downstream radiation. The large sound distribution at the inlet section is moved with the impeller rotation. The large sound distribution at the outlet of the impeller is moved with the impeller rotation, but the speed of it very larger than the rotating speed of impeller.

This paper describes analysis of acoustic characteristics of an expansion type silencer with inserted tube based on the equivalent circuit. The purpose of this study is to clarify the acoustic noise suppression mechanism of the combining an expansion type silencer and inserted tube. It is possible to model the acoustic characteristics of the expansion type silencer by parallel network system. We investigate the transmission loss and the insertion loss of the silencer numerically and experimentally. The results show that the calculated results based on the equivalent circuit and the experimental results have the same tendency. The results also show that the position of the hole in the inserted tube is important factor for transmission loss of the silencer.

In this study, we made the acoustic meta-materials for changing sound transmission property in semi-finite field. When sound passes through a material having high density, the sound velocity becomes fast. By arranging apparent density of the materials distributed over the aperture through which the wave penetrated perpendicularly, the sound transmission path could be inclined from the nominal axis of the wavefront. At first, we devised three patterns of the acoustic meta-materials. The first pattern is formed as a series of slits. The second pattern is a two-dimensional array of square props. The third pattern is an array of cross props. The wave propagation analysis in two-dimensional free field incorporating the material was performed using the finite element method. Among three patterns, we found from the simulation that the square prop affected the sound deflection most. We then conducted sound field measurements for an acoustic meta-material composed of square prop. From the measurements, it was found that the higher the frequency, the more the sound waves are deflected, and the directivity also increased. From these investigations mentioned above, the acoustic meta-materials is thought to be effective for sound deflection control.

This study proposes a new method for identifying the arrival direction of infrasound. A board in air vibrates due to infrasound. The magnitude of vibration increases when the intersecting direction of the board and the source direction of the sound are the same. Therefore, we are able to identify source direction of infrasound by measuring the vibration of boards which are placed in different directions. In this study, we attached vibration pickups to each board and measured the vibration of the different boards. The experimental results found that the source direction of infrasound can be identified in the range of ±10degrees.

This report presents three cases that ” Flow induced Vibration Problems” including ①. vibration outbreak situation, ②. Causes, ③. Remedies, ④. Effects of remedies.
This problem suddenly occurs at the new plant under trail operation, and perplexes the managers engineer on site. Moreover, this problem is not only a technical trouble of equipment, but also an environmental problem that causes troublesome Ultra Low Frequency Sound in the surrounding residential area.The cases shown here are the case where physiological obstacle and psychological disorder on human mind and body occurred by "Ultra Low Frequency Sound" that derived from "flow induced vibration" in the aviation test facility, and the ventilation system of the power station.
And it was confirmed that the influence on mind and body at residential area was recovered completely by the remedies. And last one is the case that the destruction of the flashing tank facility of power station occurred by the flow induced vibration.

This paper describes the theoretical optimal time-gap of delay blasting in tunnel blasting method. for tunnel blasting. Recently the shorter time-gap of the delay blasting in micro seconds can be carried out by the development of high precious electric detonator. At many excavation sites the time-gaps were empirically determined and there is no report about theoretical determination for the time-gap. At first we introduce a condition for optimal time-gap to reduce synthesized signal in maximum under the assumption that the signal can be expressed by sinusoidal signal without decay. Next the condition is also useful to determine the time-gap for decayed sinusoidal signals. Moreover, we apply the condition for the optimal time-gap to reduce the synthesized signal based on the first blasting signal which is excluded from the actual blasting sound. It is concluded that the time-gap determined by the introduced condition is useful to reduce the synthesized signal.

Perforated plates with backing cavity are effective for sound absorption and often used for noise control. In this study, we measured the sound absorption coefficient of perforated plates with inclined holes. Since the inclination of holes is not considered in the prediction by Guess, we compared the measured impedance with the prediction and then tried to correct the prediction to fit the measurement. The obtained profile of sound absorption coefficient of the plate with inclined holes has lower frequency of the peak and higher peak than that without inclination. We can revise the prediction considering the effective thickness of the plate when backing cavity is thick. (Backing cavity depth is up to 3.5mm) When the backing cavity depth is under 2.2mm, it is necessary to consider both the effective thickness and depth of backing cavity. We can revise using consider thickness of the plate and backing cavity depth frequency of peak of sound absorption coefficient.

A perforated plate with a backing cavity is often used as an acoustic liner. In this study, we measured sound absorption coefficients, α, of the acoustic liners with grazing flow by use of a flow duct. The flow speed, U, in the duct was set around 0-44m/s, and the SPL was set up to 140dB. We proposed a propagation constant method (PCM) to calculate α. We employed another method, back microphone method (BMM), in which a microphone on the end of the backing cavity was installed. These obtained α values were compared with the α obtained by use of the standard impedance tube method (ITM). When U = 0, the α values by PCM agree with the values by ITM around the peak frequency, and the values by BMM agree well with the values by ITM in wide frequency range. When U ≠ 0 (ITM is inapplicable), the α values by PCM and the values by BMM agree around the peak frequency although the values by PCM are fragmentary.

The fundamental sound absorbing characteristics of the Micro-perforated panel(MPP) liner is given by some useful prediction formulas or by normal impedance tube measurements, however these approaches are not sufficient for its application to the aero-engine inlets because of the presence of both grazing flow and oblique incidence waves. To evaluate the performance of MPP liner in the presence of flow, flow duct facility is designed and built. This paper presents the evaluation of MPP liners in this facility and acoustic impedance derivation from these results.

In the present paper the attention is focused on the effect of plasma actuator on aerodynamic sound radiated from two-dimensional airfoil. We measured the aerodynamic sound radiated from the airfoil with plasma actuator near the trailing edge of the airfoil. At the normal airfoil, discrete frequency noise clearly observed at small attack angle. The peak level of spectra for plasma actuator decreased compared with the normal airfoil. The plasma actuator was effective to reduce the discrete frequency noise radiated from airfoil. This noise depended on the actuator location, geometry of electrode and applied frequency of plasma actuator. We have discussed the effective geometry and conditions of plasma actuator to reduce the discrete frequency noise.

A main noise source of the high powered suction truck is a pressure fluctuation of a blower and the noise is radiated from the final component named “4^th catcher”. Two holes are provided at the upper and the lower parts of the blower as a means to get cool the blower and two SHACs (Self Help Air Conditioner) are connected by two hoses. The present study aims to clarify the achievement of the noise reduction to use the phase difference which can be made by two different lengths of hoses. As a result, the use of fluctuating pressure data before connection of two ports doesn’t go well in the noise reduction but go well by use of the data after the connection and the phase difference is the most important factor in the prediction of the noise reduction of use the idea of the interference type silencer

In an open section without tunnels, pressure fluctuations are emitted from high-speed trains and railway structures. This pressure fluctuation is consisted of two components, i.e. the aerodynamic component which is generated from train vehicles and structure borne sound from railway structures. For the aerodynamic component, although vehicles except the leading and trailing cars could play a major role, their characteristics have not been clarified. In the present study, a field test was conducted in which low-frequency aerodynamic sound sources were identified. In addition, using a launching facility for train model, an experiment was carried out in order to simulate the field test and explore low-noise shapes. The field test using a linear microphone array clearly showed that more than 16 to 32 measurements of trains are required to identify the source precisely and that bogies and current collecting devices are major sources. The results obtained by launching experiment were consistent with those in the field test. Rounding cavity corner is supposed to be one of the reduction countermeasures for the low-frequency aerodynamic sound.

In this study, we considered a contribution separation technique that separates road and wind noise contributions to vehicle interior noise without using any sound source signals in case each noise was generated by multiple sound sources. In the experiment, road, wind or mixed noise sources were reproduced from four speakers positioned at different points. The mixed interior noises were recorded at two separate positions surrounded by the speakers. A contribution separation technique using independent component analysis (ICA) was then applied for obtaining the contribution at a position (driver seat position). Firstly, ICA was applied to the recorded interior noise at the driver seat (target noise) and the noise at the assistant seat position (reference noise). The result showed that each contribution could not be correctly obtained due to the low accuracy at the low frequency and the permutation problem, in which the relationship between the calculated and actual contributions was not retained with changes in frequency. Next, we changed the reference signal to the other noise having low correlation with the target noise to improve the accuracy and formulated the permutation solution using the correlation of calculated contributions of dominant independent component. By applying this technique, the ICA method with the permutation solution procedure correctly calculated the road and wind noise contributions.

Adaptive feedforward control method is achieved by adding in a reverse-phase control sound of the same amplitude to noise near an error microphone. Because this method is aimed at controlling only noise near the error microphone, the control area is inherently narrow. Here, we propose an alternative method of noise control for an entire closed space. The proposed method is based on state feedback control and modeling of the acoustic space and loudspeaker by the concentrated-mass model. The coupled system is modeled as masses, connecting springs, connecting dampers, and base support dampers. We previously reported a method for simple one-dimensional acoustic space control. In this paper, we show the design of a control system for twodimensional acoustic spaces. By the proposed method, noise in the acoustic space was experimentally controlled, with the finding that noise in the entire acoustic space was reduced around the resonance frequencies. Furthermore, the limit of the control effect are considered within the proposed system.

This paper proposes a feedforward (FF) control based sound insulation system that reduces the two-way diffraction of an indoor noise barrier to actively create independent acoustic domains in open offices. An efficiently coupled FF control system structure, which can reduce the two-way propagation of noise, is proposed. This system applies a two-source loudspeaker array as the control source, and two microphones as the reference and error sensors. The directivity of the loudspeaker array is controlled to project the control sound only into the corresponding control area. First, the structure of the proposed system is presented in the paper. Then, simulation is conducted to verify the system performance. The results demonstrate that the proposed system can reduce the two-way diffraction of a noise barrier.

Evacuees of a great disaster of an earthquake as the Great East Japan Earthquake or Kumamoto Earthquake made partitions by cardboards to keep their personal space at a shelter. Although a cardboard is able to get easily at a shelter, is able to make various form as demand and have moderate strength, the cardboard was inept in acoustic material as an absorbent or an insulator to keep their privacy. Therefor we have be trying to improve acoustic characteristics of a cardboard. At the start of the study, we studied out an evaluation method for cardboard with two microphone method using only two microphones that could evaluate not only an acoustic absorption but also an acoustic transmission coefficient. This paper introduces the point of the evaluate method and a measurement result of sample cardboard.

The sound masking method is able to cover contents of conversation by using a masking sound. However, there is a problem that the sound level is increased because of a masking sound. Therefore, we suggested Low-noise sound masking method. In this method, spectrum of phonemes are made flat by using active noise control(ANC). It is difficult to recognize phonemes that are processed by this method because the major factor determining the phonemes in speech recognition is the relative relationship of the peaks of its spectrum. In this paper, we verify the control effect of the method by simulation.

This study was carried out with the purpose of grasping the influence of change of sound quality on the clarity of the Japanese monosyllabic for the sensorineural hearing loss person. Using the 67-S word table, heard the sound by the difference of the sound level of the consonant part and the vowel part, the sound subjected to the multi band compressor and the sound caused by the difference between speaker for hearing loss person and speaker for home-use. As a result, the smaller the sound pressure level difference between the consonant part and the following vowel part is, the more the clarity increases, the possibility that the word tone occurs due to the change in the characteristics of the following vowel, and the less the energy for each frequency of the following vowel is, the more the clarity is improved It showed the possibility.

A human-machine interface is important for monitoring a machine condition to prevent a grave accident. When a human drives an automobile, the visual, hearing and smells senses are used. However, there is no allowance on the visual sense because it is used in a grasp of map information displayed on a car navigation system, in addition to a grasp of the road condition. There is also no allowances on the hearing sense because it is used in listening to the music, etc. In this study, seat vibration is focused on in order to convey further information for the safe driving, for example, alarms for drowsy driving and for lane deviation. First, the response time was examined using a chair with a built-in vibrator, and it was confirmed that the response time was almost equal to one using sound. Then, the factor analysis was conducted to collect basic data for designing the wave form.

A Topology optimization attracts attention as a useful technique because of its flexibility in the design and applied to the various fields. To solve the wave problem with the impedance boundary condition, the utilization of the BEM and the level set method is proposed. The conventional method, however, cannot be applied to the acoustic problem dealing with plurality of fixed frequencies. In this paper, the topology optimization using the BEM and the level set method is applied to the design problem of an acoustic enclosure to improve the acoustic performance. The method for the acoustic problem dealing with plurality of fixed frequencies is proposed and some results are shown in this paper.

Sound insulation plate made of transparent polycarbonate are installed on existing concrete noise barriers to achieve higher noise reduction. However, it is almost impossible to install higher noise barrier without reinforcing the viaduct sufficiently because of wind load increase. Therefore, the authors have proposed a novel noise barrier, sound insulation plate of which can reduce wind load with hinge mechanism. In this paper, noise insulation performance of the novel noise barrier as insertion loss was evaluated in rail line. And acoustic analysis by finite element method in frequency domains was conducted to inspect the applicability for noise reduction estimation. Then the measured insertion loss shows no sound leakage from the clearance of sound insulation plate and the numerical results shows that it is applicable to visualize the distribution of sound transmission and estimate the sound reduction effect according to the noise barrier height.

The MBT (Mechanical Biological Treatment) systems that separate raw kitchen waste from other forms of municipal waste provide smaller local governments in Japan with a viable means of converting waste into energy. In order to promote MBT systems, it is important to quantify the benefits that they can provide. To quantify the benefits of MBT systems, we need to test, measure and analyze a range of operating criteria in the context of a small-scale local government setting. The results will then inform future planning of waste treatment facilities.

The recycling plants such as combustible waste incineration facility, excreta treatment facility and so on are built at the same location in AIZUWAKAMATSU city. But biomass wastes such as food waste, raw sludge, are still unused resources. In this research, we did a simulation from both environmental load evaluation and economic evaluation perspectives in case of methane fermentation facility is built. We surveyed bout the collection of biomass waste material. We set 5 model cases based the feasibilities. Moreover, this study investigates the case of using the waste heat from neighborhood incineration facility.

Superheated steam is used to process gas for degreasing oily waste because it prevents oxidation of waste metal and ignition of oil. The degreasing systems play an important role in improving the quality of oily metal as recycled materials. For safe operation in melting furnaces of waste metal and improving the quality of recycled materials, it is important to reduce the adhesion rate of oil for waste metal to 1.0% or less. In the experiment, a practical circulation-type superheated steam degreasing system is proposed, and an oily metal cutting chip disposed from a metalworking factory is processed. However, a superheated steam degreasing system consumes higher specific energy than conventional centrifugal oil separation or compression systems. Therefore, it is expected to find an optimum operation condition for the superheated steam degreasing to process the waste material. In this paper, an experiment is conducted to process gas temperatures of 400 °C or more, and the influence of the process temperature on the degreasing performance is evaluated. As a result, a superheated steam waste degreasing system for oily waste metal cutting chips can reduce the adhesion rate of oil less than 1.0%, which is difficult to attain by other degreasing methods.

The woody biomass, which is so-called carbon neutral fuel, is expected to become more important fuel in the boilers. In general, it is difficult for the clean and stable combustion to occur in woody biomass flames. In the present study, the combustion flames of pulverized woody biomass in a high-temperature air stream were investigated on the physical properties such as pulverized size and air flow rate, comparing those of fuel gas jet flames. Wood -pellet and pulp and were used for pulverized biomass fuels, and propane was used for gas fuel. The effects of the fuel on the ignition temperature and ignition delay time were examined. It was shown that the decrease of the diameter of pulverized woody biomass reduces the ignition delay time. The results suggest that the ignition characteristics of the pulverized biomass flames are almost the same as those of the gas flames.

JFE Engineering has developed the advanced stoker-type incineration system “JFE Hyper 21 Stoker System”, which adopts high temperature air combustion technology. With this technology, the incinerator realizes stable combustion in the condition of low excess air ratio, which results in reduction of NOx formation. In this paper, we describe a newly developed stoker-type incinerator which utilizes counter flow combustion in addition to high temperature air combustion technology. Verification experiment was conducted and further reduction of NOx formation was achieved. Experiment and numerical simulation were carried out to consider the reduction mechanism of NOx. Flat combustion region which contributes to stable combustion was observed in both experiment and simulation. Oxygen concentration distribution in the furnace implies that effective two-staged combustion is formed. From the view of fluid analysis, strong turbulence region is formed in the downstream of the furnace. These factors are considered to interact with each other and contribute to suppress the NOx formation.

Gasification is one of promising technologies for energy recovery from biomass including municipal solid waste. However, it has also problems such as reduction of tar and is required to increase the syngas yield. Then, we conducted experimental study on gasification and catalytic reforming of woody biomass using an electric tubular furnace to evaluate the performance of mesoporous silica catalyst supporting NiO. The results showed that the gaseous composition of H₂ significantly increased with catalytic reforming regardless of gasification agent. When only steam was used as gasification agent, H₂ generated was the highest and the concentration was 55 vol% in N₂ free condition, and the cold gas efficiency reached 77%. However, a clear result was not obtained about tar formation and decomposition by catalyst, and more research is needed.

The torrefaction process, which means low temperature heat treatment of woody biomass before severe thermal degradation without oxygen atmosphere, has recently emerged as a promising technology to upgrade solid fuel characteristics. Torrefied woody biomass fuel have higher energy density as well as better hydrophobicity and requires lower grinding energy. Our group produced the torrefaction demonstration plant, which consists of rotary-kiln type oven and ring-die type pelletizer, and succeeded to produce torrefied chip from continuously from wet wood chip of Japanese cedar. The torrefied fuel prepared in the demonstration plant showed better combustion performance in the stove and burner than conventional wood pellet. We propose a small scale utilization model of torrefied wood fuel as a heat resources for small heating appliance in rural area.

Biocoke (BIC) produced from biomass is a solid fuel which has high density and hardness. The solidification of BIC occurs by adhesive property of biomass. The adhesive mechanism seemed to be based on thermo-fluid phenomena under high temperature and pressure of hemicellulose and lignin which are main components of biomass. In this study, we investigated the thermo-fluid phenomena of the woody and herbaceous biomass. We focused on the correlation between moisture content of biomass and composition ratio of hemicellulose and lignin. Also, we intended to experimentally clarify the temperature which heat fluidity starts for each biomass. The experimental results show that the moisture content increases with decreasing starting temperature of heat fluidity for all biomass. Particularly, considering that rice straw and green tea belongs to herbaceous biomass, the heat fluidization occurs at low moisture content (5%). The actual value is highly correlated to the estimation value about heat fluidization temperature of biomass. However, the estimation value is underestimated by approximately 16°C for an actual value. The variation is approximately ±30%.

It is expected that the end face combustion of biomass columnar briquette in which pyrolysis and combustion region is limited to one end and propagates to another end with constant rate can obtain a constant heat release rate. In the previous study, it was found that a long char combustion region is formed because the char combustion rate is smaller than that of pyrolysis and flaming combustion, whereas steady end face combustion was obtained. To enhance the char combustion, the secondary air is supplied only to the char combustion region to avoid interference from the secondary air on the flame formed around the cylindrical briquette in this study. The influences of the secondary air flow rate on the length of the char combustion region, the mass loss rate and the combustion efficiency are investigated. By supplying the secondary air, the maximum temperature of the char combustion region increases and the length of the char combustion region decreases. The mass loss rate of the briquette increases with increasing the secondary air flow rate without significant influence on the combustion efficiency in relatively wide secondary air flow range.

The present study examined the mechanism underlying the enhancement of the gasification rate of biomass char when potassium (K) or iron (Fe) was supported on the char. The alkali metal catalysts were directly supported on the char with support ratios of 0, 2, 6, 10, and 20 wt%. When K was supported on the char, the gasification rate increased as the support ratio increased up to 10 wt%. Although the amount of the char-supported K catalyst slightly decreased due to heating during gasification (evaporation and scattering), the catalyst did not completely disappear, but remained on the surface and inside of the char and the remaining catalyst exerted its effect. When Fe was supported on the char, although the gasification rate increased as the support ratio increased, the gasification rate was markedly lower when Fe was supported than when K was supported. One reason for this low gasification reactivity was that the impregnation (infiltration) of the char with Fe was difficult when the catalyst supported by Fe solution and a large number of Fe crystals were laminated on the char surface only. Specifically, after heating under an Ar flow, the Fe content on the surface decreased because Fe oxide particles moved into mesopore, suggesting the decrease in the number of active sites and the restriction of the accessibility of CO₂ to active sites.

The fly ash which is combustion ash of the coal is used by already various uses. However, the use of the combustion ash of the woody biomass fuel does not advance. This study aims at the utilization by mixing combustion ash of the woody biomass to concrete. Composition of the combustion ash of the woody biomass was investigated so far. This is mixed by concrete, and the usage that is effective because various characteristics are investigated is going to be found in future.

One solution to reduce CO₂ emission from fossil fuels effectively is to replace coal or coal coke with solid biofuels. When sold biofuels are used as alternative fuels of coal or coal coke, several functions except heating have to be added to solid biofuels. The permeability is one of the most important functions, because the furnace would not work if the permeability was not added to solid biofuels. Thermal treatment can be an effective reforming, and two types of thermally treated sold biofuels have been investigated so far to replace coal coke. One is a carbonized densified biofuel and the other is non-carbonized one. The latter one devised by Ida is called BIC. The temperature range of thermal treatment of BIC is around between 160 and 300 degree, which is much lower than that of carbonized biofuels. Therefore, the mass and energy yields of BIC are higher than those of carbonized biofuels. In this study, current status of ISO17225 for “Solid biofuels” including thermally treated densified biofuel is summarized and the effect of carbonization on the net reduction of CO₂ emission is investigated.

In recent years, biodiesel fuel (Hereinafter, BDF fuel) that can be used as a diesel fuel substitute fuel has attracted attention from the viewpoint of prevention of global warming. As a commecial method of BDF fuel, by using vegetable fats and oils as a raw material, chemical treatment such as methyl esterification (alkali catalytic method) is carried out and impurities are removed in a subsequent refining step to produce Be done. However, if this chemical treatment is inadequate as incomplete combustion can occur that can not burn BDF fuel.
Therefore, in order to remedy this drawback, we used BDF fuel refined on the other hand, research process as a BDF fuel for a diesel engine and verified the exhaust gas concentration. We concluded that refine BDF, process as mixed BDF fuel can improve NO_x.CO value using small generator.

Expected gas-switchable Chemical Looping Process (CLP) hydrogen production using a calcium ferrite. CLP uses inexpensive iron-based metal oxide and has high hydrogen production efficiency, so it can reduce the production cost of hydrogen. In this research, methane gas, which is attracting attention as a result of the discovery of methane hydrate, is used as reducing gas. Because there is little knowledge when reducing calcium ferrite with methane gas, the trend of the reaction was grasped and the amount of gas produced was measured.

The plasma membrane reactor (PMR) has been developed to produce hydrogen from ammonia, which are used in the hydrogen carrier energy systems. In commercial use, more hydrogen production efficiency is desired. An innovative plasma membrane reactor (flat plate type PMR) with the flow channel has been developed to solve the drawbacks of the cylindrical plasma membrane reactor. In this paper, NH₃ decomposition characteristics of the flat plate type PMR were investigated as first experiment. Though the residence time of ammonia gas is very short in the flat plate type PMR, the plasma firing state is stable than that of the cylindrical PMR, and the power consumption is also very low. The maximum NH₃ decomposition rate was attained 26.1 % at NH₃ gas flow rate of 0.3 L/min, NH₃ concentration of 0.498 %, and applied voltage of 15 kV. The energy efficiency of hydrogen production was improved.

An oxygen cutting nozzle with/without a small pilot flame has been proposed as a device for combustion incineration and manufacturing of fire-resistant CFRP (Carbon Fiber Reinforced Plastic). Carbon fiber is almost impossible to be burned out by even high temperature burnt gas because of extremely high melting point of carbon fiber and a low oxygen concentration in burnt gases. Our preliminary trial using a propane-oxygen premixed flame, however, has revealed that its unburnt premixed gas region of a high oxygen concentration successfully burns the carbon fiber, not in extremely high temperature burnt gas region. In this study, first, oxygen nozzle of 10 mm x 30 mm exit size, which equipped fuel (propane) pipe of inner diameter of 0.8 mm for a pilot ignition flame, has been constructed. Five kinds of test pieces are used for in-oxygen-combustion experiment to obtain its combustion properties; (i) CFRP slender plate (2 mm wide and 1 mm thickness), (ii)slender plate of CFRP-P (Plastic removed CFRP), "G"FCRs("Graphite" Fine Cylindrical Rods) of diameters of 0.38 mm, 0.55 mm and 0.72 mm. Based on video recording results, it is found that once the test pieces are ignited by the pilot flame, the combustions of all the pieces are maintained in a surrounding oxygen gas flow, resulting in reducing the length of the test pieces. The behaviors of the tip positions are measured as fundamental properties for further analytical investigations of CFRP incineration technologies.

The spread of hydrogen energy system has been desired to solve CO2 issues, however, there are problems that huge energy loss has got to face in storage and transport hydrogen. Hydrogen carrier such as ammonia is available for reducing the energy loss. In the hydrogen carrier system use ammonia, a hydrogen production device from ammonia is necessary. This research is focusing on ammonia decomposition using atmospheric pressure plasma. A plasma membrane reactor (PMR) has been developed for hydrogen production from ammonia. In this study, effect of gas residence time on hydrogen yield was investigated to design the efficient plasma membrane reactor. The hydrogen yield increased with an increase in the power consumption and gas residence time. hydrogen yield achieved 99.1 % at the power consumption of 400 W and the plasma firing time of 1800 sec. The same experiments were performed by a plasma reactor without the hydrogen separation membrane (PR), and the hydrogen yields were compared with the results of the PMR. The hydrogen yields of the PMR were higher than that of the PR; therefore, it found that hydrogen separation membrane play a role of acceleration of ammonia decomposition.

Nitrogen oxides (NO_x) and sulfur oxides (SO_x) are the major components of environmental pollution; therefore they should be removed. In this study, NO oxidation process by using ozone gas and NO_x removal process by using Na₂SO₃ solutions combined with semi-dry desulfurization equipment to glass melting furnace were investigated. Experiments were carried out with varying gas-liquid reaction time in the lab-scale experiment and Na₂SO₃ concentration in the pilot-scale experiment. In the lab-scale experiment, NO_x removal efficiency was reached 64.9 % in maximum. Furthermore, in the pilot-scale experiment, when the ratio of the amount of ozone gas to the amount of NO in the exhaust gas was 23 %, NO_x removal efficiency was reached up to 17.0 %. There was no effect on desulfurization by applying plasma-chemical hybrid process to semi-dry desulfurization equipment.