Ebara Engineering Review

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

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

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

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

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

by Takaki SAKURAI, Atsushi KANEKO, Mitsutoshi HAGINO, & Takashi ENOMOTO
An impeller of a large-sized, adjustable vane volute pump was designed using the 3D inverse method and CFD (Computational Fluid Dynamics). CFD was applied for the entire calculation, from suction to volute casing, for optimizing the pitchwise location between guide and stay vanes. Experiments using a model pump were carried out under different guide vane adjustments to study factors such as pump performance, axial and radial thrusts, and the unbalanced torque of the adjustable guide vanes.

Keywords
Volute pump, Adjustable guide vane, Computational Fluid Dynamics (CFD), Inverse design, Unbalanced torque, Axial thrust, Radial thrust

by Michiko SUGIYAMA, & Shuji YAMASHITA
The Finite Element Method (FEM) was used to predict vibration of large-sized vertical pumps, as well as that of the pump station where they were to be installed. When such pumping stations have a structural foundation with low rigidity, vibratory problems such as vibratory reaction between pumps, and increases in vibration, due to resonance caused by pump excitation frequencies and natural frequencies of the foundation, tend to occur. The following discusses an actual case of coupled vibration analysis and the effective application of resulting data in reinforcing the pumping station and installing additional pumps. The vibration levels of the pumps were found to be well below the allowable limit and the resonance phenomena was prevented.

Keywords
Coupled vibration analysis, Evaluation of pump vibration, Finite Element Method (FEM), Foundation structure, Natural frequency, Resonance phenomena, Vertical pump, Pump station

by Kiyomi ARAKAWA, & Toshihiro TANAKA
Ozonation was added to an activated sludge process to study the possibility of reducing phosphorus in the effluent. Test results, comparing supernatants from an anaerobic tank and those from an ozone reactor, suggested that it was possible to achieve both biological nutrient removal, by the anaerobic-anoxic-oxic process, and phosphorus removal, by ozonation. The propagation of phosphorus accumulating organisms was also confirmed. It was determined that using the supernatant from the anaerobic tank as raw water for chemical phosphorus removal was reasonable, as there was sufficient discharge of phosphorus in the tank, also because the phosphorus concentration therein was high. An intermediate settling tank and a chemical phosphorus removal system were set downstream the anaerobic tank, resulting in reduced excess sludge and a lower phosphorus concentration in the effluent.

Keywords
Sludge reduction, Anaerobic-anoxic-oxic process, Ozonation, Phosphorus removal, Activated sludge teatment

by Katsuko KUSUMOTO, & Masahiro WAKANA
A sludge dehydration system, namely the Ebara Value Sludge System, capable of outputting sludge with a moisture content of lower than 70% max., has been developed for recycling excess sludge, following the approval of combustion improver usage at sludge recycling plants. The system constitutes 3 main components: a shaft-sliding type screw-press dehydrator, a concentrator, and a flocculation reactor. The shaft-sliding mechanism of the dehydrator prevents excess sludge clogging in the dehydrator, a typical phenomenon which occurs during sudden drops in sludge moisture content in conventional screw-press dehydrators. This system is currently being used at 5 plants and excellent feedback is being reported.

Keywords
Combustion improver, Shaft sliding type screw-press dehydrator, Low sludge moisture, The resource recycling center of excess sludge, Human-waste treatment plant, Concentrator, Flocculation reactor

by Matsuho MIYASAKA
This is the first of 5 parts of a lecture on corrosion and corrosion protection of seawater pumps. Seawater corrosion characteristics, the mechanism of various types of seawater pump corrosion will be discussed, including an introduction of Ebara's R&D on corrosion resistant materials and corrosion engineering. Part 1 will feature basics of corrosion and seawater corrosion characteristics, Part 2 fluid dynamic effects on seawater corrosion, Part 3 galvanic corrosion and cathodic protection, Part 4 a numerical corrosion analysis technology, and Part 5 corrosion and corrosion protection of stainless steel and Ni-Resist cast iron. In the following Part 1, corrosion mechanism, seawater properties, and seawater corrosion characteristics are discussed. The relationship between seawater property characteristics and seawater corrosion will be explained, in which it is pointed out that seawater is a neutral aqueous solution which saturates dissolved oxygen, also that it includes a considerable amount of inorganic salt, mainly chlorides, and is therefore highly conductive.

Keywords
Corrosion, Seawater, Pump, Chloride ion, Dissolved oxygen, Potential, Crevice corrosion, Pitting corrosion, Galvanic corrosion, Cathodic protection

by Kenichi SUGIYAMA, & Shuji HATTORI
A novel method of predicting erosion volume loss of SCS6 and thermal sprayed cermet layers by slurry jet tests has been developed, offering a solution for a serious slurry erosion problem caused by sand particles in China's Yellow River Pumping Station. This method allows selection of erosion resistant materials and determination of maintenance sequences. An equation has been compiled which uses analytical results of sand particle behavior and measurement results on surface profiles of 60 μm (mean diameter) silica sand specimens. Prediction by this equation showed an almost perfect match with test results. This equation makes it possible to predict wear patterns of 30 μm (mean diameter) sand. It was also revealed that a threshold value exists as for kinetic energy of colliding particles which contribute to erosion. This threshold value was found to increase in proportion to Vickers hardness.

Keywords
Slurry erosion, Thermal spraying, Pump, Impeller, Prediction of slurry wear, Yellow River, Numerical analysis, Cermet, Slurry jet test, Erosion resistant materials

by Tadashi KATAOKA, Tadahiko KISHIKAWA, Shigeru SAKATA, Takahiro NAKAGAWA, & Jun ISHIGURO
A remote monitoring and failure detection-diagnosis system, capable of high capacity and high speed data acquisition and storage, as well as data sharing via the Internet, has been developed for use in microturbine cogeneration systems. This system enables optimal trouble-shooting and maintenance. Accumulated long-range trend data can also be used to predict the possibility of failure and such, thus enabling preventive measures and maintenance to be carried out accordingly. The operability of a microturbine cogeneration system, which uses this monitoring and diagnosis system, has been reported to exceed 99.5%, indicating that this system is significantly upgrading reliability.

Keywords
Microturbine, Remote monitoring, Failure detection, Failure diagnosis, Predictive maintenance

by Yoshihiro MOCHIZUKI, Hideki SHIBATA, Manabu TSUJIMURA, & Hirokuni HIYAMA
An estimation was done on the probability of delamination at low-k interfaces during CMP (Chemical Mechanical Planarization) processes. This was done by carrying out 4-point bending and delamination tests during CMP, mapping the relationship between the two test results in terms of stress distribution in an interconnect structure, and estimating the mechanical property of the device. It was revealed that if the value of Young's modulus of low-k material at the trench part of the interconnect structure is above a certain value, an extremely low CMP downforce becomes unnecessary. It was also revealed that the combination of material is an important factor for reducing delamination.

Keywords
Chemical Mechanical Planarization, Low-k material, Delamination, Finite element method, Fracture mechanics

by Yoichi MORI, Takashi KYOTANI, & Yasuhiko SUZUKI
Characteristics of PFC-containing waste gas treatment systems and evaluation on abatement efficiency are discussed. The discussed systems and evaluation methods are significantly contributing in reducting PFC gas emission, especially in the microchip manufacturing industry. Such reduction is crucial in creating a hazardous-gas-free work environment and more important, in minimizing the global warming effect.

Keywords
Perfluoro Compounds, Fired thermal type, Electrical thermal type with catalyst, Chemical reaction type for PFCs, Fourier transform infrared spectroscopy, Gas chromatography mass spectrometry, Quadrupole mass spectrometry, Abatement efficency, Waste gas treatment system, Analysis method

by Ryoji OTAKE, & Yoshikatsu YAMAMOTO
Manufacturing and installation of pump equipment, including electrical equipment, had been completed for modifying Shirone Pumping Station. This modification was done as a measure against land subsidence and for improving the reliability of pumping operations. As for the measure against land subsidence, a flexible base was constructed for the main pumps. Reliability was improved by the use of non-water-injected pumps, air cooled reduction gears, and gas turbines as prime movers for flood control. The cooling system was simplified and the air-cooling of the reduction gears was enabled by installing a radiator cooling system inside the ventilation duct. A touch panel was implemented for remotely switching over the operation of pumps in the old pump house to those in the new pump house.

Keywords
Drainage pump station, Subsidence, Simplification, Flexible base, Gas turbine

by Manabu NOGUCHI, Hiroshi YAKUWA, & Matsuho MIYASAKA
Causes of and measures against high temperature corrosion in energy conversion systems of waste treatment facilities, including incinerators, stokers, boilers and gasification systems, are revealed and discussed. Actual examples and corrosion-resistant materials and methods are introduced. Such knowledge on high temperature corrosion is an important factor in evaluating the durability of materials used in energy conversion systems and leads to an upgrade in cost-and energy-efficiencies.

Keywords
High temperature corrosion, Incinerator, Gasifier, Fluidized bed, Super heater, Stoker, Erosion-corrosion

by Hidenobu OKAMOTO, & Masashi KITAMURA
A 3D inverse design method and a CFD (Computational Fluid Dynamics) method were applied in the development of an axial-flow fan for cooling towers. These methods were put to use in an attempt to improve the aerodynamic performance of cooling towers. Studies were carried out systematically on blade loading parameters, stacking conditions and rotational speed effects, afterwhich values were optimized according to study results. A fan with a blade featuring the finalized design was installed in an actual cooling tower and tested to verify its aerodynamic performance. Test results revealed that this fan, which featured the inverse design, was able to maintain the amount of rise in static pressure according to specifications, also that its efficiency was more than 20% higher than that of a conventional such fan. All in all, it was proven that the inverse design method could be an advantageous method for the design of axial-flow fans.

Keywords
Inverse design method, Axial flow fan, Cooling tower, Computational fluid dynamics, Blade loading parameter, Verification experiment, Efficiency, Rotational speed

by Tadashi KATAOKA, Teruyuki NAKAJIMA, Takahiro NAKAGAWA, & Saburo YUASA
An attempt has been made to utilize biogas (sewage digester gas) as a fuel for gas turbines. The sewage digester gas utilized had low Btu, constituting 60% methane and 40% carbon dioxide. Conventional attempts necessitate the optimization of combustion systems to improve flame-holding and other characteristics to enable the use of biogas as gas turbine fuel. The novel approach taken here by the authors was to use mass-produced microturbines and peripherals, with minimal modification and without using specially-designed combustors. The regeneration cycle is started up using a high calorific fuel for the microturbine's RQL (Rich-burn, Quick-mix, and Lean-burn) combustor. The fuel is switched to digester gas once the inlet air gets preheated to 600 K or higher. This method has proven itself to enable reliable startup, stable operation (from idling to the rated power output), and to be equivalent in efficiency to that by an operation wherein high calorific fuel is used. This system is looked forward as an energy-efficient, energy-saving cogeneration system with minimal impact on the environment.

Keywords
Microturbine, Biogas, Combustor, Sewage digester gas, Cogeneration

by Shohei SHIMA, Akira FUKUNAGA, & Manabu TSUJIMURA
An electrochemical polishing experimental apparatus was used to evaluate surface reaction during an actual CMP process. In-situ experiments were conducted to study the electrochemical reaction between interconnecting metals and the CMP slurry. A finding was made that the electrochemical reaction characteristic during polishing and non-polishing differed, also that the characteristic greatly differed depending on the chemical components of the slurry. This evaluation also revealed that it was possible to experimentally determine the effectiveness of a particular slurry and post-treatment agents prior to a particular polishing process, thus realizing a time-saving in the development. Moreover, mechanical properties of metal surface-layers were able to be evaluated from the AFM force curve, revealing a correlation with electrochemical reaction characteristics. This evaluation method suggests a possibility of nano-scale evaluation on the mechanical properties of ultra-thin reaction layers.

Keywords
Chemical Mechanical Planarization, Electrochemistry, Potentiodynamic polarization, Open circuit potential, Slurry, Oxidizer, Chelate agent, Interconnection metal, Atomic Force Microscopy, Spectroscopic ellipsometer

by Kouichi FUKAYA, Shinji KAJITA, Yukiko NISHIOKA, Fumitoshi OIKAWA, Katsuhiko TOKUSHIGE, & Manabu TSUJIMURA
Research had been conducted on precision drying technology for CMP (Chemical Mechanical Polishing) processes, in an effort to minimize damage on the surface of Low-k (low dielectric constant) films. Comparative studies were made on defect (watermark) suppression effects on hydrophilic and hydrophobic films by both the conventional SRD (Spin-Rinse-Dry) and the IPA drying methods. Study results revealed that IPA was optimal for drying hydrophobic film due to its watermark suppressing effect. As for hydrophilic film, although there was no significant difference in the drying performance by both methods, SRD was determined to be more favorable due to faster tact time.

Keywords
Chemical Mechanical Polishing (CMP), IPA drying, Rotagoni drying, Spin rinse drying, Watermark, Hydrophobic film, Hydrophilic film, Low dielectric constant materials, Contact angle

by Takeshi IZUMI, Masahiro HAGIWARA, Takashi OHTSU, Hirofumi INAGAWA, & Masayuki ARAI
A new ion exchange resin solidification system, featuring the combining of resins with paraffin wax, has been developed. The resulting solid matter, constituting resins and paraffin wax, were able to be easily incinerated at existing incineration plants, Therefore, there is no longer a need to store spent ion exchange resins, as low-level radioactive waste, that had been output from water purification systems at nuclear power plants.

Keywords
Nuclear power plants, Ion exchange resins, Radioactive wastes, Incineration treatment, Solidification, Paraffin wax

by Hideji ISOBE, Hiroshi YAMASHITA, & Toshihiro SASAGAWA
The Snow Lasta SP is a snow thawing system developed to cope with land subsidence and groundwater level sinkage in districts of heavy snow. The system's features include automatic shift of operation modes to optimally match particular snowfall conditions and ambient temperature. Pump operation (time and frequency) are constantly monitored by computer, thus enabling an elongation of pump life in the long run. Lowering cost for market competitiveness had been the top priority in the development of previous Snow Lasta models. In comparison, the development of Snow Lasta SP was centered on improvement with considerations made on water and energy saving.

Keywords
Snow thawing system, Snow thawing control, Snow sensor, Snowflake detection, Snowfall pulse, Snowfall intensity, Water saving control, Residual snow prevention, Intermittent operation, Water spray

by Hideki TATEISHI, Akira SUSAKI, & Tsutomu NAKADA
A system for removing Cu oxide film grown on the surface of copper semiconductor interconnects has been developed for reducing the resistance of such multi-layered interconnects. This system features a dry process in the atmosphere, and is developed applicable for wet processes such as CMP and plating systems. Formic acid gas, vaporized from liquid form, is efficiently applied on wafer surfaces, resulting in the removal of naturally-oxidized Cu film depositing on 200 mm wafers, in 1 minute under a temperature of 175 ℃. The basic characteristics of a practical system have been proven and a compact system has been realized.

Keywords
Semiconductor, Copper interconnects, Oxide removal, Atmospheric process, Organic acid, Multi-layered interconnects, Low oxygen concentration space, Ellipsometry, Vacuum exhaust means, Plated copper

by Takuro WATANABE, Koichi NAOI, Toshiaki MAEZAWA, & Toshimichi MIYASAKA
A SCADA (Supervisory Control And Data Acquisition) system has been developed for totalized monitoring and controlling of wind farms, thus enabling integrated management of both wind turbine and power generator systems. The following discusses the basic geometry, specifications and features of this cost-saving SCADA system.

Keywords
Wind turbine generator, Wind farm, SCADA system, Web server, Database

by Kenichi UMEMURA
The manufacturing of pump equipment for and construction work at Owada Pump Station, Chiba Prefecture had been undertaken by Ebara between March 2004 and June 2007. This was done as a part of a reconstruction project of this pump station which was getting obsolete after 37 years of service. Ebara's commitment included the modification of pump machinery and control systems, as well as reconstruction of structures by civil engineering. Various technological solutions, beyond the scope of conventional pump facility construction, were put to use, such as designing instrumentations.

Keywords
Drainage pump station, Reconstruction, Vertical axial flow pump, Siphon, Concrete casing, No water system, Silencer, Short schedule, Temporary still water system, Static concrete cutting