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Kimitoshi YONEDA, Ryo MORITA, Fumio INADA
Article type: Article
Session ID: 2304
Published: September 04, 2004
Released on J-STAGE: August 01, 2017
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Scale adhesion can often be seen at the contraction of hydraulic equipments in piping systems of power plants. Since the adhesion may affect the plant performance, the mechanism of this phenomenon is required to be clarified, and considerable prevention measures should take place for rational plant operation. In this study, scale adhesion experiments were conducted under high-temperature & high-pressure condition, to imitate the events at the actual contraction in power plants. Also the flow characteristics around the contraction were calculated numerically by adopting LES as a turbulence model. At points where pressure drop and wall shear showed maximum values, unique changes of adhered scale were observed. This may explain the relation of thermal-hydraulic and electro-chemical causes on contraction surface.
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Hajime OKANO, Takashi MATUOKA, Kazuhiko SAKAGUCHI
Article type: Article
Session ID: 2305
Published: September 04, 2004
Released on J-STAGE: August 01, 2017
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The glass fiber reinforced plastic (GFRP) with the corrosion resistance properties has been used in water environment as a structure material. Now, a non-destructive method is required in order to verify the decrease of mechanical properties during using GFRP. An ultrasonic detecting method was chosen from some non-destructive methods in the study. Eight kinds of UD-GFRP, which the immersing time was changed in 80±3℃ distilled water, were prepared. The tensile test was carried out to estimate the change of mechanical properties under water environmental degradation. As a result, it become clear that interfacial debonding causing the fall of tensile strength increased and the interfacial debonding became a factor of the source of reflection of an ultrasonic wave.
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Hideo CHO, Akio YONEZU, Miko TAKEMOTO
Article type: Article
Session ID: 2306
Published: September 04, 2004
Released on J-STAGE: August 01, 2017
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Acoustic emission (AE) monitoring during stress corrosion cracking (SCC) of AISI 304 steel in chloride solution revealed that the transgranular type SCC (TG-SCC) does not produce AEs while intergranular type SCC (IG-SCC) does produce AEs with weak amplitude. This research studied whether the AEs are produced by break of the rust produced in ESCC. We found that the rust fracture in ECSS of AISI304 shell produced strong AEs with S/N ratio of over 10 dB and lOOmV and can monitor the ESCC by AE technique.
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Tsuyohsi Mihara, Kazushi Yamanaka, Masashi Akino, Toshihiro Ogata, Ryo ...
Article type: Article
Session ID: 2307
Published: September 04, 2004
Released on J-STAGE: August 01, 2017
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Hiroyuki YOSHIDA, [in Japanese], Kazuyuki TAKASE, Hajime AKIMOTO, Hide ...
Article type: Article
Session ID: 2308
Published: September 04, 2004
Released on J-STAGE: August 01, 2017
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The Reduced-Moderation Water Reactor (RMWR) adopts a tight-lattice core with triangular fuel rod arrangement and remarkably narrow gap spacing between rods. The criteria of boiling transition (BT) is one of most important subjects for such reactor but there has been no sufficient information from previous experimental or analytical studies about the effects of the gap spacing, grid spacer shapes and so on for the BT characteristics. Thus, we start to devebp a detailed two-phase flow simulation code with interface tracking method to get information of two-phase flow in tightlattice bundles. In this paper, to verify the code performance, the simulation code was applied to bubbly flow in a circular tube. In the results, the bubble shapes almost agreed with empirical correlation. However, the terminal velocities of the bubbles were over predicted by the numerical simulation.
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Jie LIU, Seiichi KOSHIZUKA, Yoshiaki OKA
Article type: Article
Session ID: 2309
Published: September 04, 2004
Released on J-STAGE: August 01, 2017
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A hybrid method to simulate unsteady multiphase flows is described. One phase is represented by moving particles and the other phase is defined on stationary mesh. The flow field is discretized by a conservative finite volume approximation on the stationary mesh, and the interface is automatically captured by the distribution of particles moving through the stationary mesh. The effects of surface tension and wall adhesion are evaluated by the Continuum Surface Force (CSF) model. The method simplifies the calculation of interface interaction, enables accurate modeling of multiphase flows.
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Takaya TAGUCHI, Nobuatsu TANAKA, Yasunori MOTOYAMA, Masaru IWATA
Article type: Article
Session ID: 2310
Published: September 04, 2004
Released on J-STAGE: August 01, 2017
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In the fields of engineering and science, numerical analysis plays an important rule. It is very difficult to numerically analyze fluid behavior in the engineering apparatus because it contains various kinds of phenomena such as complicated geometries, multiphase flow, free surface, phase change and turbulence. For the future CFD simulation, We adopt the advanced CFD techniques such as CIVA and C-CUP methods. In this paper, we have applied these methods to three-dimensional multiphase flow and we verified to simulate cubic cavity flow, sloshing problem and dam breaking problem.
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Tomomasa Ohkubo, Yoichi Ogata, Takashi Yabe
Article type: Article
Session ID: 2311
Published: September 04, 2004
Released on J-STAGE: August 01, 2017
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Generally, we use either curvilinear coordinate or Cartesian coordinate in computational simulation of fluid dynamics. Former is suitable for describing complex structure, and latter can get high accuracy easily. However, in this paper, we suggest new grid system, which is called "Soroban Grid". Coupling this grid system and CIP method [1], we can get flexibility to describe complex structure without loosing accuracy. Therefore in this paper, we try to apply these methods to simulate steam injector.
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Heng XIE, Seiichi KOSHIZUKA, Yoshiaki OKA, Jie LIU
Article type: Article
Session ID: 2312
Published: September 04, 2004
Released on J-STAGE: August 01, 2017
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The deposition process of a single droplet on the film is numerically simulated by the three-dimensional Moving Particle Semi-implicit (MRS) method to analyze the possibility and effect of splash occurring in the deposition process in the Boiling Water Reactor (BWR) condition. From the simulation results, it is found that the splash plays an important role in the deposition and re-entrainment process in high quality conditions in BWR.
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Keizo MATSUURA, Isao KATAOKA, Kaichiro Mishima
Article type: Article
Session ID: 2313
Published: September 04, 2004
Released on J-STAGE: August 01, 2017
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Post-dryout heat transfer analysis model by Lagrangian simulation was developed. In the model, wall-vapor forced convective heat transfer, wall-droplet direct contact heat transfer and vapor-droplet forced convective heat transfer model were introduced. Furthermore by using Lagrangian simulation, the interaction between steam and droplet can be considered. For the validation of the model, post-dryout experiment was analyzed. The comparison between calculated and measured value showed the validity of this model.
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Yasushi Yamamoto, Akio Kotani, Tomio Okawa
Article type: Article
Session ID: 2314
Published: September 04, 2004
Released on J-STAGE: August 01, 2017
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To predict thermal-hydraulic performance of BWR fuel bundle, such as the critical power, the subchannel analysis is usually performed. In the subchannel analysis code, many empirical correlations are included. The one of the important correlations is that for the rate of droplet deposition. However, most available correlations for deposition rate were deduced from experimental data for simple cross-sectional geometry such as round tube and rectangular duct. Thus, the cross-sectional geometry effect on the droplet deposition rate was studied numerically using the Eulerian-Lagrangian analysis method. As the first step, the droplet deposition rate onto the inner and outer walls in annulus channel were estimated. It was shown numerically that the droplet deposition rate onto the outer surface is larger than that onto the inner surface.
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Yuichi YAMAMOTO, Hideki HORIE, Noriyuki SHIRAKAWA, Yasushi YAMAMOTO, T ...
Article type: Article
Session ID: 2315
Published: September 04, 2004
Released on J-STAGE: August 01, 2017
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Subchannel analysis method has been used to predict the critical power of a BWR fuel-rod bundle, introducing empirical spacer effects models. To construct more mechanistic models for spacer effects such as promotion of deposition, the Euler-Lagrange (E-L) method has been developed. However, this method is incapable of considering break-up process of droplets impingement on the spacer surface. In this study, we simulated the droplets behavior around BWR spacer with TF-MPS method to make a sub-model for E-L method to take the interaction between droplets and spacer into account.
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Akimaro KAWAHARA, Michio SADATOMI, Keiko KANO, Hiroyuki KIMURA
Article type: Article
Session ID: 2316
Published: September 04, 2004
Released on J-STAGE: August 01, 2017
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A vertical test channel made up of two subchannels simplifying a triangle tight lattice rod bundle was newly constructed, and experimental data were obtained on turbulent mixing rate between the subchannels. Experiments were conducted in various single-phase and two-phase air-water flows under the hydrodynamic equilibrium flow conditions. The present mixing rate data were compared with those reported so far for triangle lattice rod bundle channels as well as square ones, having hydraulic diameters of about four times larger than the present tight lattice channel. It was found that the mixing rate was considerably smaller in the present channel than the previous triangle and square lattice channels, i.e., a channel size effect.
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Akitoshi Hotta, Hiroshi Shirai, Michio Sadatomi, Akimaro Kawahara, His ...
Article type: Article
Session ID: 2317
Published: September 04, 2004
Released on J-STAGE: August 01, 2017
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Strategies of improving the vapor-liquid cross flow models will be discussed. Mainly based on the high-resolution air-water database obtained by Sadatomi & Kawahara, general trends of vapor-liquid cross flow processes will be examined. It can be appropriately assumed that hydraulic-equilibrium void distributions will be dominated by the three major effects: i.e. the fluid dynamic, the geometry and the narrow gap. The equilibrium void distribution model was modified to include the above-mentioned three effects. Two types of improved equilibrium void distribution models were proposed. Three characteristic parameters were assigned for each of the three effects and they were identified experimentally as functions of the void ratio. Multi-dimensional lattice geometries were incorporated based on the two-dimensional flow network model. The network equation was constructed by mapping the equilibrium void balance problem into the force-deflection problem. The new models were implemented into The Lahey's void settling model and they were verified based on equilibrium void distribution data obtained by Sadatomi & Kawahara.
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Takayuki SUEMURA, Yoshiei AKIYAMA
Article type: Article
Session ID: 2318
Published: September 04, 2004
Released on J-STAGE: August 01, 2017
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Mixing vanes located on the top of the grid spacers have very important roles in the thermal hydraulics performance of the PWR fuels. They had been treated simply as the resistances in the axial direction and/or isotropic diffusion promoters in the conventional subchannel analyses models, while they might cause the large scale forced cross flows in the rod bundle. In this paper, we describe the improved treatment of the mixing vanes in the subchannel analysis. It makes the prediction of the crossflow effect in the bundle more physical and points out the potential margins of conventional design methods.
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Takahiro ARAI, Yutaka ABE, Kenichiro SATOH, Yuji NAKAGAWA
Article type: Article
Session ID: 2319
Published: September 04, 2004
Released on J-STAGE: August 01, 2017
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Spontaneous vapor explosion can occur when a layer of the high temperature molten material lies on the water pool or on the moisture floor. This is so-called base-triggered vapor explosion. The base-triggered vapor explosion is supposed to occur in the case of a severe accident in a nuclear reactor and in other industrial facilities. It is very important to clarify the base-triggered vapor explosion from the viewpoints of the prediction and the prevention of the vapor explosion. In order to evaluate the heat transfer and fluid dynamic behavior of the base-triggered vapor explosion, the experimental apparatus is designed and constructed. The experiments using U-Alloy95 as a stimulant material are conducted. Consequently, the behavior of the molten material can be observed in detail with this experimental apparatus. The digital auto-correlation method and PIV are also applied to the visual observation data obtained on the experiments in order to evaluate the velocity distribution of the molten material. Based on the velocity, the conversion ratio of kinetic energy in initial thermal energy at the vapor explosion is also evaluated. In addition, the experimental results are compared with the thermal interaction zone (TIZ) theory in order to evaluate the occurrence condition of base-triggered vapor explosion.
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Hideo NAKAMURA, Masaya KONDO, Hiroshi KAWAI, Ichio TOMIAI, Toshihiko O ...
Article type: Article
Session ID: 2320
Published: September 04, 2004
Released on J-STAGE: August 01, 2017
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RELAP5 one-dimensional two-phase flow code is thermally coupled with ACE-3D multi-dimensional two-phase flow code for analyses of thermal-hydraulic behavior of a heat exchanger. RELAP5 code is suitable for analysis of one-dimensional flow in heat exchanger condenser tubes of interest, but is inappropriate for multi-dimensional flow analysis required to simulate flows in a large volume secondary water pool. Therefore, ACE-3D code is coupled with RELAP5 code as if it works as a subroutine of RELAP5 code. RELAP5 code gives the thermal boundary condition to ACE-3D code and takes the ACE-3D calculation results as the boundary conditions. This paper introduces the coupled code with some calculation results. Key Words: PCCS, RELAP5, ACE-3D, thermal-coupling, ROSA-V, LSTF
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Tatsuya MATSUMOTO, Koji MORITA, Shinichi TANOUE, Kenji FUKUDA, Yoshiha ...
Article type: Article
Session ID: 2321
Published: September 04, 2004
Released on J-STAGE: August 01, 2017
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Transient behavior of the single and huge bubble discharged from the lower side into the water pool with about 0.3MPa was analyzed by using reactor safety analysis code (SIMMER-III). In this analysis, it was verified that the condensation behavior of the bubble of nitrogen, steam and the mixture steam when there was non-condensable gas in the bubble enough and the bubble was grown up by the strong effect of condensation inhibition were reproduced comparatively well. Moreover, it was examined that the improvement of a physical model for the condensation behavior of the mixture steam was more necessary when the effect of the condensation inhibition of non-condensable gas was small and the gas phase was condensed rapidly.
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Nariaki Sakaba, Keisuke Sonoda, Yoritaka Mizokami, Shigeaki Nakagawa, ...
Article type: Article
Session ID: 2322
Published: September 04, 2004
Released on J-STAGE: August 01, 2017
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Safety demonstration tests using the HTTR are now underway in order to verify the inherent safety features and to improve the safety design and evaluation technologies for HTGRs, as well as to contribute to research and development for VHTR which is one of the Generation IV Reactor candidates. In the safety demonstration tests, a coolant flow reduction test by tripping of all the three gas circulators is planned. A three-dimensional transient numerical-model was produced in order to simulate the thermal-hydraulics between the structure and helium gas in the primary concentric hot gas duct during the coolant flow reduction test. The validity of this model was confirmed by the comparison of the analytical result and the actual transient data from the test of a reactor-scram due to loss of electric-power.
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Hidesada Tamai, Masatoshi Kureta, Akira Ohnuki, Hajime Akimoto
Article type: Article
Session ID: 2323
Published: September 04, 2004
Released on J-STAGE: August 01, 2017
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In order to design Reduced-Moderation Water Reactor core from a thermal-hydraulic point of view, an evaluation method on a pressure drop in a tight-lattice rod bundle is required. In this study, the evaluation method by Martinelli-Nelson was investigated from a comparison with experimental data in a tight-lattice 37-rod bundle. The method tends to overestimate the pressure drop under low pressure condition (P_<2MPa), whereas the method can predict the pressure drop with high accuracy near the nominal operating condition (P=7.2MPa).
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W. Liu, M. Kureta, H. Tamai, T. Mitsutake, A. Ohnuki, H. Akimoto
Article type: Article
Session ID: 2324
Published: September 04, 2004
Released on J-STAGE: August 01, 2017
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A major concern in the design of RMWR is that sufficient cooling capability be provided to keep fuel cladding temperature below specified values, even for a postulated abnormal transient process. In this research, power increase and flow decrease transient tests are performed in 7-rod and 37-rod double-humped tight lattice bundles, under RMWR nominal operating condition (P_<ex> = 7.2 MPa, T_<in> =283℃) for mass velocity G = 300, 450, 600 kg/m^2s. Experiments are analyzed with TRAC code, in which new JAERI critical power correlation is implemented for BT judgment. For the postulated nominal power increase and flow decrease transients, when CPR is 1.3, no Boiling Transitions (BTs) are observed in experiments and TRAC code predicts the same trends. For severer conditions that BT occurs, wall temperature jumping points (BT points) can be predicted quite well within the accuracy of the implemented critical power correlation. The traditional quasi-steady-state prediction of BT in transient process is confirmed being applicable for axially double-humped-heated tight lattice bundles.
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Yasuo Koizumi, Hiroyasu Ohtake, Takuro Ogawa, Hiroshi Hasegawa, Michit ...
Article type: Article
Session ID: 2325
Published: September 04, 2004
Released on J-STAGE: August 01, 2017
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The application of a steam injector to nuclear rectors as a water supply pump and a low pressure injection pump has been investigated. The heat transfer coefficient of the direct condensation of steam on the sub-cooled water surface which is indispensably required in designing and analytically examining the steam injector was studied in this research. A steam bubble was formed by ejecting steam from a 1mm diameter nozzle into sub-cooled stagnant water at atmospheric pressure. The measured heat transfer coefficient defined by temperature difference between the saturation temperature and liquid temperature and a time-averaged bubble surface area was much lower; approximately 1/100, than the realistic condensation heat transfer coefficient of steam. The measured value increased as the water sub-cooling increased on the contrary to that the realistic condensation heat transfer coefficient showed decreasing tendency with the sub-cooling increase. It was considered that when the steam bubble condensed in stagnant water, heat conduction in water provided large thermal resistance for the condensation.
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Yasuo KOIZUMI, Hiroyasu OHTAKE, Naoki YAMASHITA, Tohru MIYASHITA, Mich ...
Article type: Article
Session ID: 2326
Published: September 04, 2004
Released on J-STAGE: August 01, 2017
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The application of a steam injector to nuclear rectors as a water supply pump and a low pressure injection pump has been investigated. The characteristics of the steam injector over wide range and its performance limit are examined in this studied. In the present paper, the disruption of a water jet of 5 mm diameter injected coaxially into a 20 mm diameter pipe of 100 mm long was studied. The sub-cooling and the velocity of the water jet tested were varied from 20 to 80℃ and from 4.2 to 17 m/s, respectively. The vapor flow rate was also varied from 8 to 50 kg/s. When the vapor flow rate was low or the water sub-cooling was low, the water jet maintained a round shape. However, the vapor flow rate became large and the water sub-cooling became high, the water jet became unstable and disrupted.
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Shintaro ISHIYAMA
Article type: Article
Session ID: 2327
Published: September 04, 2004
Released on J-STAGE: August 01, 2017
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Conceptual design study and R&D on H2SO4 vaporizer has been developed. Ceramic material is to be applicable for structural materials of the vaporizer and corrosion test and bonding test between ceramics were conducted. Si3N4/Si3N4 bonding specimen exhibits high strength and excellent thermal heat shock characteristic
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Masanobu TAKEI, Shinichi KOSUGIYAMA, Kazuhiko KUNTTOMI
Article type: Article
Session ID: 2328
Published: September 04, 2004
Released on J-STAGE: August 01, 2017
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Japan Atomic Energy Research Institute has been developing the Gas Turbine High Temperature Reactor (GTHTR300) based on design, construction and operational experiences obtained from the High Temperature Engineering Test Reactor (HTTR) in JAERI. The GTHTR300 is a greatly simplified HTGR-GT plant that leads to substantially reduced technical and cost requirements for earlier technology deployment. Also, it is expected to be an efficient and economically competitive reactor in 2010s due to newly proposed design features such as core design with two-year refueling interval, conventional steel material usage for a reactor pressure vessel, innovative plant flow scheme and horizontally installed gas turbine unit. This paper describes the results of the economical evaluation on the GTHTR300. The capital cost is estimated to be less than a target cost of 200 thousands Yen/kWe. In addition, the power generation cost is estimated to be less than a target cost of 4 Yen/kWh. The present study is entrusted from Ministry of Education, Culture, Sports, Science and Technology of Japan.
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Shoji KATANISHI, Kazuhiko KUNITOMI
Article type: Article
Session ID: 2329
Published: September 04, 2004
Released on J-STAGE: August 01, 2017
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JAERI has undertaken the design study of gas turbine high temperature reactor, the GTHTR300. Design of fundamental safety functions, such as shutdown of rector, maintaining the coolability of reactor core and prevention of FP release has progressed in this design study program. Design of control rod arrangement and its insertion scheme was conducted in order to meet the safety requirement, such as a sufficient shutdown margin of reactivity and a low control rod ejection worth. A passive cooling system by using a natural convection of air was designed for maintaining the coolability during accident. Cooling panels consisting of rectangular ducts were adopted for sufficient capability of heat removal and structural integrity during depressurization accident. Double confinement was designed for mitigation of FP release and for maintaining the integrity of coated fuel particles and graphite material of fuel support structures. This article describes results of these design studies.
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Masahiko HISHIDA, Yosindo SOMAN, Mamoru KONOMURA, Toshiie SAIGUSA, Mik ...
Article type: Article
Session ID: 2330
Published: September 04, 2004
Released on J-STAGE: August 01, 2017
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In the "Feasibility Study on Commercialized Fast Reactor Cycle Systems", an innovative concept of a sodium-cooled loop-type reactor to pursue high economic competitiveness has been developed by adopting several innovative concepts. For one of the concepts, 12Cr-steel with high strength and low thermal expansion rate has been employed as a structural material of the primary piping. As a result, the diameter is enlarged and length is shortening and the cooling system has been remarkably simplified. For the design concept of the hot leg piping, it is designed as a simple L-shaped top-entry type piping selected on the view point of economical and technical issues. And the structural integrity against a thermal stress and the instability of the vibrations of primary piping are evaluated.
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Yoshihisa NISHI, Izumi KINOSHITA, Tomohiro FURUKAWA, Kazumi AOTO
Article type: Article
Session ID: 2331
Published: September 04, 2004
Released on J-STAGE: August 01, 2017
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Lead-bismuth eutectic (LBE) is one of the candidate of the coolants of fast breeder reactor (FBR). It is important to develop the proper protection of both structural and core materials from LBE corrosion. In this study, a high chromium martensitic stainless steel (ASME P122) as a promising candidate of structural materials of the FBR was investigated to clarify the corrosion behavior in stagnant LBE at 650℃ under controlled oxygen concentration. Structure of the oxygen layer surrounding the specimens and the behavior of the main alloy elements were investigated by optical and chemical analyzing. It is estimated that LBE penetration can be protected by retaining high chromium content layer at the border between the oxide and the steel.
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Tadashi FUJII, Youhei NISHIGUCHI, Mamoru KONOMURA, Hiromi SAGO, Tadash ...
Article type: Article
Session ID: 2332
Published: September 04, 2004
Released on J-STAGE: August 01, 2017
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A conceptual design study of the sodium-cooled fast reactor (JSFR) is in progress in "Feasibility Study on Commercialized Fast Reactor Cycle Systems". The cooling system of the reactor is composed of two loops in order to reduce plant construction cost. According to reduction of loop number, large diameter pipings are adopted in the primary cooling system, and the average sodium velocity in the piping increases to 9 m/s level. One of issues for piping design is to confirm hydraulic and flow-induced vibration behaviors of the piping under high Reynolds number (10^7 order level) conditions. Then, a flow-induced vibration test facility which simulates a hot leg piping with 1/3 scale has been fabricated. As a first step of the test series, this report describes outline of flow visualization test results.
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Satoshi NISHIMURA, Izumi KINOSHITA, Ken-ichiro SUGIYAMA, Wataru ITAGAK ...
Article type: Article
Session ID: 2333
Published: September 04, 2004
Released on J-STAGE: August 01, 2017
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In order to clarify the effect of hydrodynamic fragmentation on molten fuel-coolant interactions, which is important in evaluating the sequence of core disruptive accidents in metallic fuel fast reactors, a series of basic experiments with a molten metallic fuel simulant (molten copper) and a sodium pool was carried out under an ambient Weber number condition (We) roughly equivalent to that in practical metallic fuel cores with high burnup. The value of the mass median diameter (D_m) of copper fragments normalized by the initial jet diameter (D_m/d_0) decreased with increasing the superheating of the molten copper jet, independently of the ambient Weber number under the condition of We<200. Under the condition of We>200, the effect of initial superheating temperature becomes negligible and the value of D_m/d_0 comes to depend on the ambient Weber number. This finding indicates that the transition of fragmentation mode from thermal to hydrodynamic occurs at the ambient Weber number of approximately 200.
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Kazuma OTOGURO, Shunsuke YAO, TOMOAKI Namioka, Kunio YOSHIKAWA, Yousuk ...
Article type: Article
Session ID: 2401
Published: September 04, 2004
Released on J-STAGE: August 01, 2017
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The aim of HyPR-MEET system is to produce hydrogen from biomass resources by means of gasification with high-temperature steam of 1000-1300℃. In this paper, basic gasification characteristics of wood chips and meat-and-bone meals with high-temperature steam were investigated. In addition, we measured the reaction rate of gasification of char produced from both samples under high-temperature with and without steam supply. The experimental results show that H_2 and total gas production substantially increased under 900℃ steam gasification. The char gasification reaction was significantly promoted by increasing the reaction temperature and supplying steam.
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Yukihiko MATSUMURA, Masanori SHIMAMURA, Yoshihiro KIKUCHI
Article type: Article
Session ID: 2402
Published: September 04, 2004
Released on J-STAGE: August 01, 2017
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In supercritical water gasification, hydrogenation is expected to prevent char formation and to improve gasification efficiency, but hydrogenation reagent has not been specified. Some researchers suspect formic acid, intermediate of water gas shift reaction, is working as a strong hydrogenation reagent. In this study, experimental work was conducted to find the characteristics of formic acid and 2-propanol production in supercritical water gasification of glucose, where the former should be produced by partial oxidation, and the latter is produced from acetone, intentionally added to detect hydrogenation.
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Takanari OKAMURA, Chyoju FUKUHARA, Susumu TAKAHASHI, Toshiya TAMURA
Article type: Article
Session ID: 2403
Published: September 04, 2004
Released on J-STAGE: August 01, 2017
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This paper presents the experimental results of gasification of wood biomass using a fluidized bed test furnace. The feedstock for the test furnace is cedar chips. A1_2O_3 particle was prepared in fluidized bed and air was used for reaction gas. The furnace temperature was selected the range of 600 to 750℃. The production gas composition is CO,CO_2,H_2 and CH_4. The inflammable gas CO, H_2 and CH_4 increased with a rising of furnace temperature. And carbon conversion showed higher level than 80% over 650℃.
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Ryo ATSUMI, Yasuhiro OKI, Yutaka MITANI, Masachika TAKASHIO
Article type: Article
Session ID: 2404
Published: September 04, 2004
Released on J-STAGE: August 01, 2017
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Methane fermentation by the Upflow Anaerobic Sludge Blanket (UASB) system is extensively applied to treatment of brewery effluents. However, the UASB system is not suited to process solid sludge. Therefore, the feed solution requires a pretreatment to remove any suspended solid matter. This report introduces the hydrogen and methane two-stage anaerobic fermentation system, which produces hydrogen in the former stage and methane in the latter stage, for the purpose of effective treatment by energy conversion from food processing-wastes including solid waste. The hydrogen gas produced from this process will be able to use for a fuel cell, without any chemical converting. By the usual manner, the produced methane can be used as a boiler combustion gas. Therefore, this process will enable the simultaneous supply of electricity and heat. We conducted fermentation and power generation experiments using a bench pilot fermentor and a small-scale fuel cell, respectively. A comparison was made between the two-stage fermentation and the conventional methane single fermentation. The two-stage hydrogen and methane fermentation excelled the methane single fermentation in terms of energy balance.
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[in Japanese], [in Japanese], [in Japanese], [in Japanese], [in Japane ...
Article type: Article
Session ID: 2405
Published: September 04, 2004
Released on J-STAGE: August 01, 2017
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Experiments of the "semi-carbonization" pyrolysis were conducted for cellulose mixed with phosphoric acid in order to clarify the effect of acid additives on the transportation of semi-carbonized fuel. The acid additive promoted dehydration of cellulose, and induced the reduction in the weight yield of char under low temperature conditions. The analytical model to investigate the energy value of the semi-carbonized fuel was presented by taking account of the reduction in the fuel value due to the transportation. The addition of small amount of phosphoric acid to cellulose was effective for manufacturing the semi-carbonized fuel with the highest energy value at low pyrolysis temperature. The fuel energy value decrease with increasing the concentration of acid addition for a given transportation distance. It was found that the optimal concentration was 1 wt.% in the ranee of the present study.
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Nobuhiko HAMANO, Kenichi SEMITANI
Article type: Article
Session ID: 2406
Published: September 04, 2004
Released on J-STAGE: August 01, 2017
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The Internally Circulating Fluidized-bed Gasifier (ICFG) comprising two chambers (gasification and combustion chambers) in a single furnace is now under development. The fluidizing medium in this gasifier, mainly silica-sand, circulates between these chambers. The gasifier has been tested, using mainly wood-biomass as the feedstock, for more than 2000 hours since 2003. Test results indicated a successful production of intermediate-calorific gas by pyrolysis gasification. The product gas was supplied into a gas engine and micro gas turbine, and it was demonstrated that stable operation with product gas was possible. The principles of the ICFG, the outline of the test plant, and some operational data are presented in the following. By using the ICFG, efficient power generation and the synthesis of chemical products from various solid raw materials will come to realize
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Yuji MORI, Shigehiko KANEKO, Tatuo WATANABE, Yudai YAMASAKI, Takayuki ...
Article type: Article
Session ID: 2407
Published: September 04, 2004
Released on J-STAGE: August 01, 2017
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For the purpose of the effective utilization of the biomass, a low calorific value gas fueled micro gas turbine generating system is being developed. The micro gas turbine is a twin shaft gas turbine with regenerative cycle, and its output is about 10 kW. City gas and low calorific value gas are used as fuel. The low calorific value gas simulated the gas composition of the biogas, and its calorific value is about 4,000 kcal/m^3. In order to operate and evaluate the generating system, the development of the control system is also being carried out. In this paper, the outline of the generating system and its start-up control method are introduced.
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Miki TANIGUCHI, Hidenao TANAKA, Kenichi SASAUCHI
Article type: Article
Session ID: 2408
Published: September 04, 2004
Released on J-STAGE: August 01, 2017
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The forest biomass energy is recently paid attention from the both sides activation of the forestry or local industry and global warming prevention. From 2002, we installed the demonstration plant of gasification and power generation of the forest biomass in Yamaguchi as joint research with NEDO, and started the demonstration examination. This Plant performs power generation with the gas engine dynamo that uses a woody tip as materials and uses the gasification and generation gas by the multi-cylindrical rotary kiln of an indirect heating formula as fuel. This time, we report the outline of the Demonstration Plant and the data of result.
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Jian ZHANG, Keitaro SATO, Tomoaki NAMIOKA, Kunio YOSHIKAWA, Hironao MA ...
Article type: Article
Session ID: 2409
Published: September 04, 2004
Released on J-STAGE: August 01, 2017
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In this research, middle heating value gas is made using chicken droppings as a fuel using pyrolysis and gasification, and reports the power generation system. Chicken droppings are supplied to a pyrolysis gasifier, reaction is performed in 600-700℃ temperature and non-oxygen, pyrolysis gas containing tar is led to a reformer, is reformed into Ft and CO as main reforming gas with 800-1000 ℃ high temperature air. At the last, engine is driven, and electricity and thermal energy are extracted. Results show the gasification and power generation system flow chicken droppings is quite possible.
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Yoshitaka Chikazawa, Toru Hori, Mamoru Konomura, Shouji Uchida, Yoshih ...
Article type: Article
Session ID: 2410
Published: September 04, 2004
Released on J-STAGE: August 01, 2017
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A feasibility study on hydrogen production systems using sodium cooled fast breeder reactors has been carried out in Japan Nuclear Cycle Development (JNC). Thermochemical and electrolysis hybrid cycle developed in JNC is one of sulfuric acid cycle without carbon dioxide emission. The process temperature is lowered up to 500deg-C to add SO_3 gas electrolysis to Westinghouse sulfuric acid cycle. In this study, hydrogen production system is designed. Major components of the plant are sketched and designed to be made of steels such as high Si cast iron which has good toughness against sulfuric acid. High hydrogen production efficiency of 42% is achieved with the thermochemical electrolysis hybrid cycle, assuming development of high efficiency electrolysis.
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Shinji ISHIMATSU, Takashi SAIKA
Article type: Article
Session ID: 2411
Published: September 04, 2004
Released on J-STAGE: August 01, 2017
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In this paper, the experiments were conducted for application of ammonia to fuel cell system. If ammonia is dissociated by heating on the suitable catalyst, it becomes 75% of hydrogen and 25% of nitrogen. The authors have proposed the new hydrogen generation system using ammonia for fuel cells and designed an ammonia dissociator and an ammonia distiller. The separator and the distiller for residual ammonia are necessary even in the optimal conditions obtained in the experiment. It could be demonstrated that the fuel cell system with the ammonia separator and the distiller. Then it can be possible to continuously operate fuel cells.
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Keisuke KAWANISHI, Keisuke TAKESHITA, Yoshiharu AMANO, Takumi HASHIZUM ...
Article type: Article
Session ID: 2412
Published: September 04, 2004
Released on J-STAGE: August 01, 2017
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In this paper, authors propose and investigate an Ammonia-Water Mixture (AWM) turbine system with ejector. The AWM turbine system is a power cycle which is similar to a Kalina cycle. The AWM turbine system without ejector has high pressure solution which is led to the condenser through the reducing valve without using potential of the pressure. For using the pressure difference effectively, a new cycle configuration which installs ejector is proposed. The results of simulations show that the turbine system with ejector generates larger output power than that without ejector under the same condition. And the simple configuration cycle can be expected to generate almost as much output as more complicated cycle by installation of ejector.
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Keisuke TAKESHITA, Taiji SATO, Yoshiharu AMANO, Takumi HASHIZUME
Article type: Article
Session ID: 2413
Published: September 04, 2004
Released on J-STAGE: August 01, 2017
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This paper describes performance comparison of two types of hybrid configuration of power generation and refrigeration cycles using ammonia-water mixture by simulation calculation. Difference between two configurations is the ammonia mass fraction of solution from the turbine system (power generation cycle) to the ammonia absorption refrigerator (refrigeration cycle). The newer configuration (configuration 2) supplies higher mass fraction solution to the refrigerator. As a result, both configurations show larger system net power than separated operations when the basic composition (the ammonia mass fraction of the evaporator in the turbine system) is 0.45 kg/kg. The performance gains of configuration 1 and 2 are 13.6% and 13.8%, respectively.
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Keisuke TAKESHITA, Koji MORIMOTO, Yoshiharu AMANO, Takumi HASHIZUME
Article type: Article
Session ID: 2414
Published: September 04, 2004
Released on J-STAGE: August 01, 2017
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This paper presents an experimental investigation on effectiveness of the AWM (Ammonia-Water Mixture) turbine system to the lower temperature heat sources. The system features two subsystems: a distillation/condensation subsystem (DCSS) and a vapor generator subsystem (VGSS). The experimental result and calculation results show that DCSS functions when the heat source is higher than 100 [℃], and VGSS functions when the heat source is over than 180 [℃]. Since the main application of the AWM turbine system is the heat recovery and there are abundant 100-200 [℃] exhaust heats as unused heat sources, effectiveness of the system to the lower temperature heat source, especially from 100 to 200 [℃], is very important. The experiment was carried out with changing the back pressure of the steam turbine.
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Yoshitaka IWASA, Takemi CHIKAHISA
Article type: Article
Session ID: 2415
Published: September 04, 2004
Released on J-STAGE: August 01, 2017
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The paper analyzes CO_2 reduction effect and economic effect of cogeneration network system (CGNS) with considering grid limitation in electric quality. In CGNS, cogenerations are connected to the grid, being allowed to send excessive electricity to the grid. The system equips heat storage system and it is operated to contribute to reduce power-demand fluctuation; in this sense the system is cooperative to the grid. Analysis was made to compare the system with conventional cogeneration system without networking. A model area based on the actual service area in a city was selected and analyzed. The result indicates that the CO_2 reduction rate increases to 20% with the CGNS from 10% of the conventional cogeneration system. Additionally the power fluctuation in the grid can be also expected.
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Shin'ya OBARA, Kazuhiko KUDO
Article type: Article
Session ID: 2416
Published: September 04, 2004
Released on J-STAGE: August 01, 2017
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Improvement in efficiency of fuel-cell-powered vehicle is studied using water electrolysis as the energy storage. Three method are proposed; 1. Reformer and fuel cell are divided into two or more units, and the maximum output of each unit is set small, which reduces the partial load operation, 2. all the fuel cell units are operated above the low efficiency partial load condition and the excess electricity is supplied to another fuel cell unit to generate hydrogen and oxygen by water electrolysis, 3. regenerated energy during deceleration period is used to make by hydrogen and oxygen. Moreover, the LA4 cycle was introduced the energy saving effects of the above-mentioned methods are studied for the fuel-cell-powered electric vehicle, and are shown to increase the energy efficiency by 1.23-1.72 times the conventional method.
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Kinji TSUJIMURA, Katsuhiko YOKOTA, Hiroyuki YUZA, Keita HORANAI
Article type: Article
Session ID: 2417
Published: September 04, 2004
Released on J-STAGE: August 01, 2017
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In this study, a solar thermal energy car system is investigated for heat application. It would be driven by a power system with water vapor expansion that is generated by collected solar thermal energy through heat exchanger. Then, we made a Solar Collector with a condensing mirror and a lower thermal heat loss, and measured the operating oil temperature, etc, in this system. As results, we could get a high temperature of operating oil and good prospect for capability of a solar thermal energy car system.
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Takeshi SOMEYA, Yutaka ABE, Yutaka SUZUKI
Article type: Article
Session ID: 2418
Published: September 04, 2004
Released on J-STAGE: August 01, 2017
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It is expected that the micro channel device with many narrow passages is high performance heat exchanger device in various fields, hi the present study, the heat exchanger with the micro channel device is newly manufactured by diffusion bond. Experiment and numerical analysis are performed to investigate characteristics of the heat transfer and fluid flow through the micro channel heat exchanger. It turns out that the overall heat transfer coefficient becomes high with increasing the Reynolds number of heating gas and a coolant gas. The maximum value of the overall heat transfer coefficient for gases is about 50% higher than the traditional devices.
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Yohinori UEDA, Yukio SUGURO
Article type: Article
Session ID: 2419
Published: September 04, 2004
Released on J-STAGE: August 01, 2017
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The wind power generation capacity exceeds 40GW in the world. There are about 800 turbines of 730MW in Japan. Growing market requires newer and larger wind turbines. So, rated output of wind turbine has increased double every four years since last 10 years. It's a very hard target for turbine manufacturers. Mitsubishi Heavy Industries, Ltd. is the only one manufacturer of MW class large wind turbines in Japan. We have produced first 2MW wind turbine in Japan at Okinawa in march 2003. The technical problems about large wind turbines and tactics to solve them are described. First tactics is how to extend the relative strength of turbine equipmemts. Second tactics is how to reduce the load acting to turbines. Wind turbines at Miyako island have been severely damaged by typhoon No.14 in 2003. It revealed that wind turbines are not so strong enough when yaw control has been lost by power failure. The new technology to survive power failure, named "SmatYaw" is explained.
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Akira MAEKAWA, Shinji UEHARA, Masanori TAKAHARA
Article type: Article
Session ID: 2420
Published: September 04, 2004
Released on J-STAGE: August 01, 2017
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Wind energy converters which are connected to the grid of local island sometimes cause frequency or voltage fluctuation. This article presents the wind energy hybrid system which makes the local grid stable using batteries and inverters connected to wind energy converters in the arrangement in a row. If the wind velocity is high, the results which could supply 80% of the electrical demand by wind energy converters are introduced together.
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