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Ebara Engineering Review No.193

Development of Water Hydraulic Proportional Control Valve

by Tamami TAKAHASHI, & Chishiro YAMASHINA

The authors have developed a novel proportional control valve that exclusively uses water as its working fluid. This valve is equipped with a spool, directly driven by a solenoid that had been modified for water usage. The characteristics of this solenoid, including data that verifies its performance is equal to that of oil hydraulic types, is first presented in the following. Next, some structural characteristics of the water hydraulic proportional control valve is discussed. Some features of the valve are, hydrostatic bearings (embedded in the valve for supporting the spool) and damping orifices (for stabilizing the spool), the former for compensating the low lubricity of water and the latter for the low viscosity of the same. In particular, the hydrostatic bearing section had been designed to enable a minimization of total leakage, including the bearing flow, while obtaining a load capacity. The constant flow from the hydrostatic bearing prevents the water in the valve from decaying. Finally, experimental results of cylinder positioning, controlled by the developed water hydraulic proportional control valve, are introduced to verify the valve's satisfactory performance as a control valve.

Ozonation, Water hydraulics, Control valve, Proportional solenoid, Hydrostatic bearing, Damping orifice

Electromagnetic Acoustic Resonance

by Toshihiro OHTANI, Hirotsugu OGI, & Masahiko HIRAO

This report discusses the Electromagnetic Acoustic Resonance (EMAR) method, an emerging ultrasonic spectroscopy technique which enables nondestructive, non-contact evaluation of material characteristics. By this method electromagnetic acoustic transducers (EMATs) and superheterodyne circuitry process received reverberation signals excited by long radio frequency (RF) bursts. The transduction occurs through the Lorentz force mechanism. For ferrous metals, the transducion occurs by the magnetostriction and the magnetic force. A weak coupling of EMATs is essential for achieving high accuracy in measuring ultrasonic velocities and attenuation in conducting materials. A high signal to noise ratio is achieved by the reception of overlapping coherent echoes at resonant frequencies. Thus, small changes in related material properties become sufficiently detectable. The spectral response can be interrupted for sample geometries, such as those of plates, cylinders and spheres. The EMAR method has been proven to be extremely suitable for industrial use because of its sturdy mechanism and performance, the non-necessity of surface preparations, and the capability of easy measurement within a short time. Precise measurements on attenuation can be done at resonant frequencies.

Electromagnetic Acoustic Resonance (EMAR), Noncontact material characterization, Resonance method

The Influence on Settled Thickening of Sewage Sludge by Vacuum Deaeration Treatment

by Ryosuke HATA, Takao HAGINO, Yoshiharu IRIUCHIJIMA, & Hideki YOSHIDA

Pilot plant experiments were conducted to study the effects of vacuum deaeration on the settled thickening of sewage sludge in a gravity thickener. The influent sludge had undergone putrefaction while being transported during centralized sewage sludge treatment. Deodorizing effects by the same was also studied. The recovery of suspended solids following deaeartion was 20 points higher than that by agitation deaeration during summer and fall, a period during which sludge putrefaction is intense. The concentration of thickened sludge was higher by 5 g/L comparing the same. It was also found that there was no generation of scum throughout the year for treatment by vacuum deaeration. Gas in the sludge was found to become enriched-exhausted, thus significantly reducing the generation of malodor due to hydrogen sulfide. Centralized sludge treatment, a treatment which is becoming more widespread, is expected to complicate sludge treatment by conventional methods and vacuum desecration has potential as a solution to such complication.

Vacuum deaeration treatment, Centralized sludge treatment, Gravity thickener, Scum, Suspended solids recovery, Settled thickenability, Hydrogen sulfide, Sludge odor, EBARA Deaer-Mild

A Rapid Method of Quantifying PCBs in Transformer Oil

by Makoto TAKADA, & Hisayuki TODA

A rapid method of analyzing and quantifying trace quantities of PCBs in transformer oil has been developed. This method combines liquid-liquid extraction and solid phase extraction for speeding up pretreatment, enabling low resolution, quadrupole GC/MS (Gas Chromatograph/Mass Spectrometer) analyses. Analyses are facilitated and neither high technology nor high-cost devices are necessary. Analytical results by this method were compared to those by the conventional, official method of analysis and it was confirmed that this method was capable of precise quantification. The reproductibility of this method was also found to be extremely favorable. Comparing this method to conventional analysis methods, it was found that this method used up merely one thirtieth of the time. The cost was only one fifth of that by conventional methods. The use of this method at a PCB treatment facility, including operation and PCB assessment, is introduced and discussed in the following.

Polychlorinated biphenyl (PCB), Soild phase extraction (SPE), Gas chromatograph/Mass spectrometer (GC/MS), Analysis, Transformer oil

A Speed-up of Dioxin Analysis using the Ion Trap MS/MS Technique


A rapid analytical method for dioxin had been under development since 1997 and an outline of this method had been given in a previous report3). The modifications made heretofore have enabled higher precision and sensitivity, and consequently, an analysis method featuring a high degree of versatility has been established. The main modifications comprise a) Comprehensive application for water samples by using a disc filter method, b) Establishment of a high efficiency extraction method for activated-carbon containing samples, c) Enhanced sensitivity by optimizing analysis conditions, and d) Establishment of concentration method utilizing decompression and centrifugal devices. Results of a cross-check on 10 low-concentration, soil samples suggested that there was great correlation between the said method and the corresponding JIS method, an assurance of improved sensitivity.

Dioxin, Analysis, Ion trap, MS/MS, Fly ash, Soil, Wastewater, Throughput

Circulation Fan for Wide Space Air Conditioning

by Toru SAITO

A low-noise, mixed-flow circulation fan has been manufactured for air conditioning wide space, in particular for use in domed stadiums. Compact and equipped with a silencer, this fan can be installed near spectator seats in a closed space. Moreover, it is exceptionally energy-efficient and satisfies air-flow velocity and noise emission (NC45) standards.

Circulation fan, Large space, Swirl flow, Dome, Low noise, Silencer, Mixed flow fan

Pressurized Two-stage Gasification System for Plastics The EBARA Ube Process (EUP)

by Hideko SUGIYAMA, Takashi IMAIZUMI, Daisaku HUKUHARA, Shinichiro CHIBA, Syuichi OKU,Takao SATO, Shigeya HAYASHI, Makoto TERAUCHI, & Osamu KAMEDA

EBARA CORPORATION and UBE INDUSTRIES, LTD. have jointly developed a pressurized two-stage gasification system, named EUP, for the chemical recycling of plastic wastes. This system, whose main components are a low-temperature fluidized-bed gasifier and a high-temperature, swirling-type slagging gasifier, degrades plastic wastes into hydrogen and CO, which are in turn recovered and used to make ammonia at an adjacent chemical plant. The treatment capacity of this system, currently 30t/day, is expected to be increased to 65t/day by the year 2002, thus enabling an annual treatment of 20-thousand tons. The following outlines this system and its operation.

Plastic wastes, Laws on recycling containers and packages, Chemical recycling, Hydrogen, Carbon monoxide, Pressurized two-stage gasification, Fluidized-bed gasifier, Swirling-type slagging gasifier, Ammonia synthesis, Slag

New Construction-cost Saving Technology Adopted by Large-scale Drainage Pump Station Ushizue Drainage Pump Station


A new construction-cost saving technology has been adopted at the Ushizue Drainage Pump Station, Saga Prefecture. This technology features the use of compact pumps and peripherals, including their facilitated operation. This technology was developed in an effort to downsize a new pump house, added to an existing one, to save on construction cost, and to upgrade operability and reliability. The new pump house was completed in March 2001 and commercial operation is underway. The following introduces the pumping facility, the high-speed and compact main pump, the high-speed canal, and other technology being newly adopted at Ushizue Drainage Pump Station.

Drainage pump station, Saving construction cost, High speed & Compact pump, High velocity canal, Axial flow pump, Adjustable vane pump, Concrete casing pump, Gas turbine, Air cooled reduction gear, Crane truck

Singapore Kranji Sewage Treatment Plant Construction Project

by Shigemi OKADA

The Phase 3 extension works of Kranji Sewage Treatment Plant in Singapore started in March 1995 and finished in August 1999. EBARA was involved in this project as an NSC (Nominated Sub-Contractor) together with Mitsubishi Corporation who was a consortium partner. The main contractor was Hyundai Engineering and Construction Co. Ltd and the consultant, which supervised the works, was Binnie, Black, and Veatch. The client was the Ministry of Environment of Singapore. The capacity of the extended plant was approximately 75000m3/d, which doubled the treatment capacity of the existing plant. The multi-national project team consisted of more than 30 members at the peak of the commissioning. Thanks to the cooperation of our relevant division and efforts of the project team the plant is being operated smoothly.

Kranji Sewage Treatment Plant, Construction Works, Consortium, Engineering, Hyundai Engineering & Construction Co, Ltd., Binnie Black and Veatch, Jurong Engineering Ltd. (JEL), Ministry of Environment, Mitsubishi Corporation, Egg shaped digester

PCB Degradation by the BCD Process

by Maina YOSHIDA, Yoshihiko INOUE, Mitsuhiro KINUGAWA, & Hiroshi WADA

A permit for the installation of Japan's first Industrial Waste (PCBs and PCB contaminated oil) Dechlorination-Decomposition Plant was obtained in October 1999. Treatment of highly concentrated PCBs was carried out at this plant, which features the BCD (Base Caltalyzed Decomposition) process, for one year from January 2000. The plant was proven to be safe and target treatment was accomplished. An attempt for risk communication was made with the residents in the vicinity of the plant, as well as with the local authorities, with whom an understanding and cooperation was established. Treatment of PCB containing oil yielded treated oil in which PCB concentrations were degraded to below allowable standards, with no indication of dioxins. Emissions from the treatment processes contained very low concentrations of PCBs and dioxins, well below the allowable standards and causing no impact on the environment. This experience is expected to contribute substantially to the abatement of PCB emissions in Japan.

PCB, BCD process, (Base Catalyzed Decomposition process), Risk communication, Dechlorination, Decomposition treatment, PA (Public acceptance)