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Journal Articles

Flow behavior in annular centrifugal extractors with different vessel sizes

Misumi, Ryuta*; Todoroki, Kei*; Kunii, Kanako*; Nishi, Kazuhiko*; Kaminoyama, Meguru*; Sano, Yuichi; Sakamoto, Atsushi; Takeuchi, Masayuki

Kagaku Kogaku Rombunshu, 44(5), p.285 - 291, 2018/09

https://doi.org/10.1252/kakoronbunshu.44.285

Annular centrifugal extractors have been anticipated for use as extractors in spent nuclear fuel recycling. The extraction rate and the liquid-liquid dispersion are related to the flow pattern in the vessel. However, no study has clarified flow patterns in vessels of various scales. For this study, flow pattern characteristics are quantified for extractors of two scales. An extractor has a mixing zone around the vessel bottom and a separation zone in the cylindrical rotor. For this experiment, distilled water was fed into the vessel. Flow behavior in the mixing zone was observed from a side view using a digital video camera at various rotor speeds and supply flow rates for extractors of two scales. In some cases, the liquid horizontal velocity vectors in the mixing zone were measured using particle image velocimetry. Results demonstrate that flow behaviors in the mixing zone in both scales of extractors are classifiable as three types, changing with operational conditions: Type A, Type B, and a Transition regime. For the Type A state, the mixing zone is fully filled with liquid from the vessel bottom up to the lower edge of the rotor. In the Type B state, the zone with existing liquid is vertically divisible into two regions. Lower rotor speeds and higher flow rates tend to produce Type A state flow behavior. The boundary operational condition between Type A and the Transition regime are correlated with the normalized supply flow rate and pumping capacity of the rotor, which is evaluated from liquid surface level in a rotor formed by centrifugal force. Furthermore, the fluid velocity in the mixing zone is roughly proportional to the rotor surface circumferential speed irrespective of the vessel scale.

Journal Articles

Development of decomposition/detoxicifying technology of dioxins in waste incineration flue gases using electron beams

Kojima, Takuji

Hoshasen To Sangyo, (95), p.64 - 68, 2002/09

http://ci.nii.ac.jp/naid/40005508828

JAERI has developed decomposition/detoxicization technology of diozins in waste incineration flue gas using electron beams and actual 200 $^{circ}C$ flue gas at Takahama clean center. The obtained results are as follows:(1) Ratio of concentrations before and after irradiation were about 50%, 80% and higher than 90%(goal) for absorbed doses of 3, 10, and higher than 14kGy. (2)Applicability of the obtained data with the scale-up ratio of about 6 was demonstrated for actual 4,000 m $^{3}$ /h flue gases. (3)Toxicity as endocline-desruptor was checked using ELISA method and higher than 50% of such a toxicity was reduced from initial one by irradiation.(4) Diphenylether(DPE) or chloro-DPE having benzen-rings and ether bonds, were used as model compounds to clarify electron-beam decomposition mechanism detecting decomposition products at 200 $^{circ}$ C. Break of ether bonds and cleavage of benzen-rings can be occured mainly at the initial decoposition process of dioxins rather than dissociation of Cl base without destruction of dioxin structure.