All issues
Volume 50, Issue 3
Special Issue of 48th Summer Symposium
Displaying 1-7 of 7 articles from this issue
- |<
- <
- 1
- >
- >|
Review
-
Hisao Makino, Naoki Noda2013 Volume 50 Issue 3 Pages 166-172
Published: March 10, 2013
Released on J-STAGE: September 30, 2014
JOURNAL RESTRICTED ACCESSSolid carbon fuel resources like coal and solid biomass are very important energy resources now and for the future. Coal reserves are more abundant than other fossil fuels, so coal will be important energy resource in the future. Biomass is regarded as renewable energy. For a stable supply of energy and protection against the global warming problem, advanced technologies for the utilization of coal and biomass are needed.
Powder technology is important for effective utilization of solid carbon fuels. Powder handling technologies, from the mining of coal and the collection of biomass to the utilization of these fuels, is being utilized. In this paper, the role of powder technology in conventional thermal power plants and future high performance power plants is discussed along with the possibility of more effective contribution of powder technology including fuel upgrading technologies.View full abstractDownload PDF (880K)
Original Paper
-
Yong Huang, Koyo Norinaga, Shinji Kudo, Jun-ichiro Hayashi, Keiji Tomu ...2013 Volume 50 Issue 3 Pages 173-181
Published: March 10, 2013
Released on J-STAGE: April 04, 2013
JOURNAL FREE ACCESSThis research is aiming at developing a pyrolysis technology of biomass producing charcoal with a high yield. Our strategy in increasing a charcoal yield is to facilitate co-carbonization of biomass and tar by intensifying char / biomass and tar interactions inside the reactor. A laboratory scale simulated moving bed reactor was originally developed. Using this reactor, it was possible to evaluate several processes included in the biomass pyrolysis at up-draft moving bed reactor such as volatile release, tar sorption in / on biomass, tar reforming at charcoal surface, and co-carbonization of biomass / char and tar. The fundamental knowledge accumulated with these experiments towards maximizing charcoal yields as well as minimizing heavy tar yields provided guidelines useful for designing and operating the bench-scale up-draft moving bed pyrolyzer which can process 1 ton of biomass feedstock per day. The test operations revealed that charcoal yields from several biomass with more than 40 mass% were successfully achieved.View full abstractDownload PDF (980K) -
Masahiro Narukawa, Yosuke Tsuboi, Yasuzo Kumagai, Makoto Takafuji, Tos ...2013 Volume 50 Issue 3 Pages 182-189
Published: March 10, 2013
Released on J-STAGE: April 04, 2013
JOURNAL FREE ACCESSWood pellets were steam-gasified by using the bench-scale dual fluidized bed gasifier (DFBG). The composition of volatile compounds in the effluent gas from the gasifier is compared with that for lignite. The major components for wood were CO, H2 and hydrocarbons which result mainly from pyrolysis, whereas H2 and CO2, which are produced by steam gasification and water-shift reaction, were major components for lignite. For wood, 57% of carbon in volatile compounds originates from pyrolysis, to be compared with 27% for lignite.The results of experiment and numerical calculation suggest that secondary pyrolysis of tar components proceeds in the free-board and that tar components are steam-reformed.View full abstractDownload PDF (825K) -
Hiroyuki Hatano, Junichiro Otomo2013 Volume 50 Issue 3 Pages 190-196
Published: March 10, 2013
Released on J-STAGE: April 04, 2013
JOURNAL FREE ACCESSThe chemical looping reaction is applied to the combustion and gasification of coal for effective energy conversion. The reduction of metal oxide is examined in the fixed / fluidized bed of 20 mm I.D. and 1120 mm in height. As a lattice oxygen carrier, iron oxide is used and coated on the porous alumina of 0.2 mm mean diameter. Taiheiyo coal of 0.5 g is dropped into the test section and gas production profiles were measured with the temperature range 793 K through 983 K. Initial stage of the reaction, only carbon dioxide is observed, while the hydrogen is produced simultaneously for the insufficient amount of lattice oxygen. Hydrogen yield is about 2.5 times of the carbon content and this exceeds 2.0 which is obtained from the complete reactions of the Water gas and Shift reactions. The extra hydrogen is produced from the hydrogen contained in coal and it may give higher cold gas efficiency.View full abstractDownload PDF (687K) -
Yuki Kamikawa, Masayuki Taniguchi2013 Volume 50 Issue 3 Pages 197-203
Published: March 10, 2013
Released on J-STAGE: April 04, 2013
JOURNAL FREE ACCESSCoal fly ash components, morphologies, and the crystal structure produced under high combustion temperatures were observed with an electron microscope. Coal was burnt using the high-temperature tandem-type staged drop-tube furnace. Reaction temperature, reaction time, and particle concentrations were adjusted to those used in actual boilers and sub-bituminous coal and bituminous coal were investigated. When coal was burnt under high temperature fuel-rich conditions in the first furnace, solid carbon compounds which differ from char were observed. Elemental analysis revealed that the solid carbon compounds were soot. To evaluate the effect of coal properties on soot formation, emission properties of unburned carbon in fly ash （UBC） were examined for sub-bituminous coal and bituminous coal. In the case of sub-bituminous coal, UBC decreased once then increased again with increasing combustion temperature. By contrast in the case of bituminous coal, UBC steadily decreased with increasing combustion temperature. Electron microscope images showed that high crystallized carbon compounds were present in the soot of sub-bituminous coal.View full abstractDownload PDF (846K) -
Kenji Tanno, Ryoichi Kurose, Takenobu Michioka , Hisao Makino, Satoru ...2013 Volume 50 Issue 3 Pages 204-211
Published: March 10, 2013
Released on J-STAGE: April 04, 2013
JOURNAL FREE ACCESSIn coal-fired thermal power plants, selective catalytic de-NOx system is widely used and very efficient method to reduce NOx emission from the plant. However, ash particles laden in flue gas adhere on a de-NOx catalyst surface, and ash coverage causes the severe degradation of de-NOx catalyst. Authors numerically investigated the effect of flow behavior in a honeycomb channel on the adhesion characteristics of particles to the wall in the previous study. However, previous study was performed under the assumption that all particles, which reach the wall, adhere. Therefore, in this study, the effect of particle collision and rebound behavior on the adhesion characteristics on the wall of honeycomb shaped catalyst was investigated by applying a direct numerical simulation (DNS). In order to take account of particle collision and rebound behavior, the probability coefficient of adhesion was introduced. The results show that although particle adheres on the wall only in the upstream region, in which flow condition is turbulent, irrespective of adhesion probability coefficient, the amount of adhered particles decreases with decreasing probability coefficient. The results also indicate that particle re-adhesion also occurs only in the upstream region even though some particle rebound and return to the flow from the wall.View full abstractDownload PDF (988K) -
Hiroyuki Hatano, Satoru Matsuda, Yasuhiro Uenohara, Yasuo Kawaguchi, K ...2013 Volume 50 Issue 3 Pages 212-218
Published: March 10, 2013
Released on J-STAGE: April 04, 2013
JOURNAL FREE ACCESSA new desiccant air conditioning system, MCMB : Mesh partitioned Countercurrent Moving Bed, is proposed to achieve an efficient dehumidification at low pressure drop. The dehumidifying section is divided into two flow channels by a wire mesh. Air is introduced from the bottom of one of the channels, while desiccant particles are flowed down in the other channel at a slow speed to achieve updraft type moving bed. Length of the acrylic dehumidifying section is 600 mm with a rectangular cross-section of 50 mm by 5 mm for air flow channel and 50 mm by 10 mm for particle flow channel. Axial distribution of air temperature, Tg, relative humidity, φ, and particle temperature, Tp, are measured and dehumidification rate is obtained. Based on these results, it is found that the MCMB actualizes the efficient isothermal dehumidification at low pressure drop. Furthermore, the wire mesh governs the mass transfer step when the particles have higher adsorption rates such as Zeolite.View full abstractDownload PDF (881K)
- |<
- <
- 1
- >
- >|