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Ebara Engineering Review No.183

Prediction of Diffuser Pump Performance Using 3-D Viscous Stage Calculation

by Akira GOTO, Kosuke ASHIHARA, & Tatsuyoshi KATSUMATA

The reliability of a Computational Fluid Dynamics (CFD) code for predicting overall pump performance is discussed for two model diffuser pumps, with a median specific speed of 400 (m3/min, m, min-1) or 0.155 (non-dimensional). The flow fields are numerically analyzed using a stage calculation version of Dawes three-dimensional Navier-Stokes code, and the overall pump characteristics are predicted based on CFD calculations. A comparison is made with experiments for head, power and efficiency-flow characteristic curves, flow patterns of wall surface streamlines obtained by multi-color oil-film flow visualization, and the development of impeller inlet recirculation. The effects of grid resolution when predicting pump performance are also discussed.

Keywords
CFD, Diffuser pump, Stage calculation, Performance prediction, Wall surface streamlines, Multi-color oil film method, Inlet recirculation, Grid dependency, Internal flow, Loss analysis

Passive Vibration Control by Piezoelectric Materials with Electrical Elements of Resistance

by Masato TANO, Shijie GUO, & Yoichi KANEMITSU

The damping effect of piezoelectric materials with electrical elements of resistance on the vibration of structures like beams and disks, was investigated experimentally and analytically. It was shown experimentally that the piezoelectric material with resistance had damping effect and that an optimum resistance value existed to each vibration mode to exhibit maximum modal damping ratio. The modal damping was also estimated analytically. Both results were compared and showed good agreement. The results indicated that piezoelectric materials can be used to increase damping of flexible structures like impellers of fluid machinery.

Keywords
Vibration, Damping, Piezoelectric, Electrical circuits, Cantilever beam, Disk, Passive vibration control

A Study on Wastewater Treatment by an Advanced Oxidation Process

by Sota NAKAGAWA, Takehiko YAMADA, Hiroshi SAKUMA, Koji MISHIMA, Toshihiro TANAKA Takahiko NISHIMURA, & Masaki GOI

A study was made on the treatment of refractory substance containing wastewater by an AOP (Advanced Oxidation Process). This included lab-scale tests in which biologically treated leachate from a disposal site was used as the raw water. Test results here indicated that the D-TOC treatment performance of the AOP was higher than that by either an O3 treatment or a UV treatment. Findings on the decomposition performance suggested that there was no dependence on the molecular weight of refractory substances. Tests were also conducted on the advanced treatment of secondary treated sewage. Two combinations of treatment, one constituting a BAF (Biological Aerated Filtration) process followed by an AOP, and the other an AOP followed by a BAF process, were used here. The CODMn treatment performance of the AOP was found to be higher than that of an O3 treatment. As for the treatment performances of color, odor, and coliforms, those of the BAF process followed by the AOP were found to be highest. Such results indicated the present AOP was applicable for the advanced treatment of sewage water.

Keywords
Refractory substance, Advanced oxidation process, Secondary treated sewage

Development of a Manganese Removal Method for a Fluidized-bed Reactor

by Junichi NOMURA, Noriko UEDA, Yoshiko SUGITA, Shinichiro EGAWA, & Taizo IWATANI

A manganese removal method, featuring a fluidized-bed reactor using manganese sand as the bed medium, was developed for removing soluble manganese contained in wastewater and filtrate in water purification plants. By this method, soluble manganese is crystallized on the bed medium surface as carbonic acid by adjusting the pH of the influent. No trihalomethanes become generated as no chlorine is used. A test apparatus was used to study operational factors. Test results indicated that pH adjustment, made according to the temperature of the influent, adequately removed soluble manganese (influent: 10-25 mg/l, effluent: below 1 mg/l).

Keywords
Manganese carbonate, Manganese removal, Waterworks, Sludge treatment, Manganese sand, Crystalization, Single type fluidized bed, Dual type fluidized bed

A Study on the Removal of Acetaldehyde in Flue Gas by a Biological Deodorizing Method

by Toshio TSUKAMOTO, Kenichi FUTAMI, Akihiro ARIKAWA, & Nobuhiro YADE

Experiments were conducted to study the removal of acetaldehyde in flue gas using a packed tower equipped with a biological scrubber for deodorization. The test conditions included using flue gas with an acetaldehyde concentration of 15 ppm, an acetaldehyde volumetric load of 0.4 kg/(m3·d), and an SV of 600 h-1. Experimental results indicated that stable removal was possible, with the acetaldehyde concentration decreased to below 0.2 ppm. However, continuous long-term operation resulted in an increase in residual sludge in the tower, and a significant rise in pressure loss in the same. It was found that using a hydrogen peroxide solution was effective for removing such residual sludge.

Keywords
Biological scrubber, biological deodorizing method by packed tower, Acetaldehyde, Wet scrubber , Adsorption by activated carbon, H2O2, hydrogen peroxide, SV, space velocity, LV, linear velocity, Pressure loss, Activated sludge

Studies on Hydrogen Production System using Microorganism

by Naoaki KATAOKA, Akiko MIYA, & Koichi KIRIYAMA

Hydrogen production by a two-stage reactor system combining culturing of anaerobic bacteria and photosynthetic bacteria was investigated. Continuous hydrogen productivity from soluble starch by anaerobic bacteria, Clostridium sp. KT-7B, was 1.4 to 2.3 mol-H2/mol-glucose [1.8 to 2.8 mmol-H2/(g-cell·h)]. The hydrogen production yield from acetate and butyrate (VFA) by photosynthetic bacteria, Rhodobacter sphaeroides ATCC17023, was 0.24 and 0.29 mol-H2/mol-VFA, respectively [0.15 and 0.13 mmol-H2/(g-cell·h)]. Based on both fermentative hydrogen production data and photosynthetic production data from the present experiment and several references, it was estimated that the total hydrogen production yield by a two-stage reactor utilizing the combined culturing system was 1.6 to 5.9 mol-H2/mol-glucose, which was 13 to 49%of theoretical. Investigation of the bio-conversion ratio of acetate and butyrate to hydrogen by photosynthetic bacteria is believed to be important for putting the biological hydrogen production system to practicable use.

Keywords
Hydrogen production, Anaerobic bacteria, Photosynthetic bacteria, Starch, Organic acid, Hydrogen partial pressure, Vacuum culture, Organic waste, Fermentation, Reactor

RCD Series Absorption Chiller-Heater Unit Utilizing Waste Heat

by Tomoyoshi IRIE

EBARA has developed a RCD series absorption heater-chiller unit, named Genelink, which utilizes waste heat in wastewater as a heat source. This unit is designed under a co-generation concept, principally using gas as fuel and also making use of waste heat from a gas engine generator. The utilization of waste heat by this unit enables a 10% saving on fuel consumption under a normal heater-chiller operation for air conditioning. The water heated by waste heat is drawn into Genelink via a heat exchanger and no absorption chiller (necessary in conventional system) is needed. This system, under a partial air-conditioning load, is also capable of being operated using only waste heat in water as the power source, thus realizing significant energy-saving.

Keywords
Absorption Chiller-heater, Waste heat, Co-generation System, Gas consumption reduction rate, Microcomputer control panel

Comparison between an Hzfree Pump and an MS Pump by LCA

by Kazuhiko KANEKO, & Haruo OKAZAKI

LCA (Life Cycle Assessment) was carried out on two types of pumps, namely the MS type and the Hzfree type, and the results compared. It was found that the greatest impact on the environment by these pumps were during their use, related to the consumption of electric power for driving them. As for the impact on the environment during the manufacturing of these pumps, that during the manufacturing of the Hzfree pump was smaller. This was attributed to compactness and the fact that no cast iron was used for this pump. Results of evaluation on the life cycle also indicated that the Hzfree pump had less impact on the environment. This was attributed to an energy saving effect by the use of inverters. The following introduces data acquired during the comparison, including matters involving the inventory as well as impact assessment results.

Keywords
Life cycle assessment, LCA, Pump, Inventory, Impact, Energy consumption, GWP, LCE, Distance-To-Target

Tungsten CMP Process

by Keisuke NAMIKI, & Norio KIMURA

Tungsten CMP (Chemical Mechanical Polisher) processes are now replacing RIE (Reactive Ion Etching) processes in semiconductor manufacturing. These next-generation processes are already used for mass production of semiconductors by some manufacturers. The following introduces configuration data and application examples of CMP processes. Vital factors in a tungsten CMP process are discussed, such as dishing, oxide erosion, surface roughness, and post-polishing cleaning. As these factors are effected by the slurry used, comparison is made among different types of slurries. Another type of metal CMP process is discussed as well.

Keywords
Oxide erosion, Dishing, Polishing rate, Uniformity, Endpoint detection, Cleaning , Scratch, Selectivity, Slurry, Pad

The Gaikaku Housuiro Drainage Pump Station - First Report on General Outline of Pumping System -

by Tetsuo TAKABE, Shinjiro MAE, Takashi ENOMOTO, & Takafumi MAEHARA

The planning and construction of drainage systems, equipped with deep underground conduits as primary reservoirs for storing run-off via inter-river linkage, are recently underway as a countermeasure against floods which threaten low and flat urban areas. The JShutoken Gaikaku Housuiro"construction project features the building of Japan's largest-scale underground conduits. The main pumps used in the JGaikaku Housuiro"drainage pump station are the largest such pumps in Japan as well. The following gives a general outline of this drainage pump station and introduces new technologies applied.

Keywords
Underground conduits, Primary reservoir for runoff, Inter-river linkage, Drainage pump station, Underground at great depth, Flood prevention, Drainage system

Peripheral Equipment for Karisaka Tunnel

by Koichi FURUYA, Masaki OHSUGA, Akira MOCHIZUKI, Hironobu HIRASHIMA, Hiroyuki MUSHA, & Tamotsu NAKANO

Peripheral equipment was installed for Karisaka Tunnel, one of the longest tunnels in Japan, including ventilation, warning and fire-fighting, power reception/distribution, and control equipment. An across-the-board coordination system for each management/control stage, such as for normal or emergency operations, is also included. The equipment enable stable control of ventilation during normal operation, speedy and precise linked control of ventilation and fire-fighting during emergency operation. A backup management system enables some functions to be intact in case of equipment failure. The peripheral equipment is helping achieve an improvement in reliability and all their functions are reported to be favorable

Keywords
Long distance tunnel, Ventilation equipment, Fire prevention equipment, Authenticity, Variable voltage variable Frequency, Higher harmonic wave, Fire, Across-the-board operation, Operation stage, New technology

A Chronology of EBARA's Fluidized-bed Technology

by Takahiro OSHITA

Drastic changes are expected in the waste treatment of the 21st Century. Gasification & melting techniques, by which excess combustion heat is used for the remediation of dioxins and the melting of incineration ash, will become the mainstay of treating general waste. Chemical recycling techniques will be used for converting plastics-based mixed waste into chemical resources. Demand will rise for high efficiency power generation (efficiency exceeding 30%) using excess heat from waste incineration. As for high efficiency power generation using coal, techniques for preventing CO2 emission at an early stage will be in demand. Fluidized-bed technology will surely play an important role in realizing a breakthrough in the 21st Century waste treatment and power generation using coal. Bubbling fluidized-bed and circulating fluidized-bed techniques will make way for newer techniques. The following introduces a chronology of EBARA's fluidized-bed technology as well as the future of the same.

Keywords
Fluidized-bed, Incinerator, Gasifier, Fluidized-bed boiler, Pressurized combustion, Pressurized gasification, Dioxin, Ash melting, Power generation, Chemical recycling

EBARA's Environmental Management System and ISO14001

by Motokazu UMEDA

Situations encompassing environmental problems are recently undergoing drastic changes on a worldwide scale. The number of business locations which have been certified as ISO14001 sites in Japan has exceeded 1,392 by the end of November 1998, a surge which is expected to outrun that experienced regarding ISO9000 sites. In December 1997, the United Nations Frame Work Convention on Climate Change (COP3) was held in Kyoto, Japan to discuss the prevention of the global warming effect. The following discusses how EBARA's environmental management system is related to problems and solutions discussed in this symposium. Discussion is also made on the impact of environmental management on enthusiastically carried out environment-related businesses. Finally, discussion is made on EBARA's future environmental management system, i.e. as an outcome of past and current efforts in EBARA's continuous improvement on environmental management, including EBARA's 5 areas which have attained the ISO14001 standard.

Keywords
Environmental Management System, Environment-related business and environmental management system, each constituting wheels on each side of a vehicle, Zero emission, Self-imposed action in environment-related plans of the Japan Society of Industrial Machinery Manufacturers, PRTR policy, Bottom-up by participation of all, Top-down put together by audial input involving entire corporate body, Home version ISO14001, Business management based on the environment

Engineering Seminar on Fluid Acoustics Lecture 3 ; Broad Band Noise Induced by Flow Turbulence

by Yoshiyuki MARUTA

This is the third of a series of lectures for an engineering seminar on fluid acoustics which focuses on control and utilization of sound generated from unsteady flows. This third lecture presents the generation mechanisms and the control techniques of broad band noise induced by flow turbulence. Boundary layer noise, separated flow noise, and jet noise are explained after explanations about frequency, wave-length, acoustic impedance, and the acoustic interference are presented. The phenomena of bursts in the viscous transition layer under the turbulent boundary layer are seeds of boundary layer noise. The scale of flow separation controls the amplitude and the dominant frequency component of separated flow noise. The structure of shear flow layer around the jet flow controls the jet noise and the span-wise non-uniformity of the shear flow decreases the jet noise.

Keywords
Fluid dynamic sound, Turbulent noise, Broad band noise, Turbulent boundary layer, Separated flow, Jet, Vortex, Acoustics, Lecture, Noise control