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Hiroshima-shi, Japan

Yoshii Y.,Hitachi Ltd. | Hokari N.,Hitachi Ltd. | Iwase T.,Bab Hitachi Industrial Co. | Korai Y.,Kyushu University
Kagaku Kogaku Ronbunshu | Year: 2010

The gas-phase reaction NO-NH3-O2 was investigated in a tubular flow reactor at a pressure of 788 kPa and temperatures from 650 to 850°C. Injection of ammonia into a 2MWthPFBC combustor was also attempted, and it was found that 55% of NO was converted to N2 at 855°C with an NH3/NO molar ratio of 2 and residence time of 1.4 s. In the combustor, the nitric oxide concentration could be reduced to less than 70 ppm, and leakage of ammonia was kept below 5 ppm at the full load. During the load change operation in the combustor, nitric oxide was decreased as the load became higher when the ammonia injection was controlled by the prediction method. Copyright © 2010 The Society of Chemical Engineers, Japan.


Yoshii Y.,Hitachi Ltd. | Iwase T.,Bab Hitachi Industrial Co. | Korai Y.,Kyushu University
Nihon Enerugi Gakkaishi/Journal of the Japan Institute of Energy | Year: 2010

Emissions of SOx from a 4MWth twin-bed pressurized fluidized bed combustor (PFBC) system were measured during long-term (1187 hours) operation. The PFBC consisted of two bubbling beds, A-bed and Bbed. Though both reactors were operated at the same pressure and temperature, emissions of SO2 differed between two reactors. The limestone particles sampled from B-bed, which showed lower emission level, had more internal cracks and their particle size was smaller than those from A-bed. Basic studies of SO2 capture and calcination were also conducted using a pressurized fixed bed reactor for eight kinds of limestone. Calcination of limestone was found to increase reactivity with SO2 under elevated CO2 partial pressure conditions higher than equilibrium partial pressure. Limestones with more internal cracks were found to have higher reactivity towards SO2 absorption. The degree of crystallization measured by X-ray diffraction gave valuable information to predict reactivity and fragmentation. The difference in emission behavior between two fluidized beds is discussed in terms of crack formation and fragmentation.


Patent
Hitachi - GE Nuclear Energy and Bab Hitachi Industrial Co. | Date: 2014-08-04

The laser welding apparatus includes a welding head and a welding head scanning apparatus. A collimate lens installed on a head body of the welding head is arranged opposite to an end face of optical fibers. The welding head includes only the collimate lens as a lens and the length is shortened. A laser generated by a laser oscillator is introduced into the optical fiber, enters the collimate lens, and then is converted to a parallel beam by the collimate lens. The laser of a parallel beam is irradiated on a surface a welding portion of the welding object through a laser path and the surface of the welding portion is melted. Metallic powder is jetted from powder feed paths formed in a head body to the melted portion and build-up welding is performed on the surface of the welding portion.


Shinozaki K.,Hiroshima University | Yamamoto M.,Hiroshima University | Mitsuhata K.,Babcock Hitachi K. K. | Nagashima T.,Bab Hitachi Industrial Co. | And 2 more authors.
Welding in the World | Year: 2011

The melting of filler wire is investigated in detail to obtain the precise temperature distribution of the filler wire during ultra-high-speed gas tungsten arc (GTA) welding and develop ultra-high-speed GTA welding with a pulse-heated hot-wire system for three kinds of materials. The melting phenomena of the filler wire were observed using a high-speed camera, and temperature distributions of the filler wire were measured using a radiation thermometer. The results show that ultra-high-speed GTA welding can be achieved with suitable welding conditions for each material. Ultra-high-speed GTA welding requires suitable wire current to obtain a suitable temperature distribution and melting position of the filler wire. Moreover, the temperature distributions of three kinds of filler wire could be estimated using a proposed simple estimation method.

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