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Ebara Engineering Review No.221

Development of Cryogenic Pump Inducer using Inverse Design Method and CFD

by Hiroyoshi WATANABE, & Isamu ICHIKI

A cryogenic pump, comprising an inducer, impeller and diffuser, has been developed for LNG (Liquified Natural Gas) transfer and pressurization. The inducer, an important component which enables high suction performance, was exclusively designed using the 3D inverse design method, by which 3D data for blade geometry was numerically obtained for specified blade loading distribution. The flow fields and performances of the inducer and pump were evaluated by CFD (Computational Fluid Dynamics), while pump suction performance was evaluated using a Rayleigh-Plesset cavitation model. The pump was then tested in a water test tunnel, the result of which indicated favorable suction performance. Cavitation CFD was used for investigating inducer work distribution effects and hub meridional shapes. Suction performances predicted by cavitation CFD matched well with those of test results.

Keywords
Inducer, Suction performance, Three dimensional inverse design, Loading, Cavitation, CFD, LNG, Cryogenic pump

Pure Water Production System

by Hiroshi SHINMURA, & Shinji YOSHIDA

A novel pure water production system comprising 3 units, namely an upstream pre-system unit, a pure water production unit, and a downstream sub-system unit, has been developed. These units are used in accordance with raw water and pure water specifications. The pure water production unit's hub constitutes the GDI (Graft De-Ionization) component which is a demineralizer. This component uses ion exchange non-woven fabric by radiation graft polymerization for the ion exchanger. As GDI enables a significantly greater surface to be ion-exchanged than when this is done by applying ion exchange resin, it has become possible to make the unit compact and the operation more effective.

Keywords
Electric desalination unit, GDI, Pure water production system, UF membrane filtration, Ultra pure water production unit

Pump System in Effective Water Usage at Kinugawa Dam Network

by Hiroyuki OSAWA, & Takayuki SUZUKI

EBARA had undertaken the construction and installation of dam pumping facilities for transmitting water between 2 dams to enable effective use of water resources. The pumping facility for feeding water had been installed in headrace tunnels, 1 large-scale vertical-axis pump in each of 2 vertical shafts. The facility for return water features a hinge-float for enabling water intake from surface layers,in line with dam water level changes. A pump equipped in the bottom of this float makes it possible to transmit return water as well as enable a natural downward flow. Return water test operation was done in accordance with actual water levels to cope with water pressure fluctuations in tunnels and at gate, also with seasonal and time-wise fluctuations in water levels.

Keywords
Dam network, Effective use of water resource, Water feed pumping facilities, Water supply facilities, Ikari dam, Kawaji dam, Floating unit, Vertical volute type mixed flow pump, Submersible moter pump, Cone valve

Vibration of Centrifugal Pumps - Fluid Phenomena and Rotor-dynamics

by Masato EGUCHI

A study had been made on centrifugal pumps problems related to fluid-induced vibration. The majority of such problems are caused by fluid-induced unsteady excitation, which tend to occur during off-design pump operations (low flow rate operations, NPSH operations, etc.), or by the destabilized force of the flow in narrow clearances. There are also many cases where the deterioration of the damping property of the rotor-bearing system, related to the fluid operating condition, contributes in the occurrence of these problems. The following categorizes fluid-induced vibration of centrifugal pumps, introduces problems in actual cases, and gives examples of measures and research cases.

Keywords
Rotordynamics, Annular pressure seal, Interference between impeller and vane, Fluid induced vibration, Centrifugal impeller, Centrifugal pump, Self-excited vibration, Resonance

Lecture on Corrosion and Corrosion Protection of Seawater Pumps - Part 2 Fluid Dynamic Effects on Seawater Corrosion -

by Matsuho MIYASAKA

The fluid dynamics of seawater cause the progress of corrosion in seawater pumps by causing an effect on the electro-chemical reaction between the pump material and fluid. Moreover, pump damage by erosion-corrosion or erosion results in high flow rate regions, due to mechanical effects on material surface oxide film or on the materials themselves. The following discusses such corrosion and erosion-corrosion, including a brief discussion on erosion. Also discussed is differential-flow-rate-cell-corrosion, a phenomenon which may occur due to the formation of a macro cell caused by non-uniform flow rates inside seawater pumps.

Keywords
Corrosion, Seawater, Pump, Fluid dynamics, Erosion-corrosion, Differential-flow-rate-cell-corrosion, Galvanic corrosion, Polarization curve, Potential