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Ebara Engineering Review No.223

Prediction of Wear Depth Distribution by Slurry on a Pump Impeller

by Kenichi SUGIYAMA, Takashi ENOMOTO, & Shuji HATTORI

A technique has been developed for predicting wear volume loss for impellers of pumps susceptible to slurry wear by sand particles in river water. Predictions can be used to determine applicable wear resistant materials and maintenance factors for pump impellers. The wear depth distribution of impeller blades of an aluminum pump was studied, the results of which were found to correspond well with slurry wear test results of the same. Industrial application of this technique is highly recommendable.

Slurry wear, Wear depth distribution, Prediction, Pump impeller, Maintenance, Slurry jet test

Water Polishing by Diamonds - Performance of Diamond Electrodes for Wastewater Treatment -

by Masahiro SERIKAWA, Kenichi SASAKI, & Yuji SENDA

CVD-made conductive diamond electrode exhibit outstanding stability compared to the noble metal electrodes in wastewater treatment as well as high COD removal efficiency. Stable diamond electrode with size enough for industrial use has been developed. Results of a field test carried out using a pilot plant equipped with a diamond electrode stack indicated stable operation. Current trends in diamond electrode technology for wastewater treatment is discussed in this paper.

Diamond electrode, Wastewater treatment, Electrode stability

Behavior of Anaerobic Microbial Consortia in Thermophilic Methanogenic Sludge - Treating Cellulose-containing Wastes -

by Tomoko TATSUZAWA, Ling-yun HAO, Shohei AYAME, Naoaki KATAOKA, & Akiko MIYA

The behavior of acidogenic and methanogenic microbial consortia in cellulose-containing wastes was studied to collect physiological and ecological data for enhancing the degradation and methane gas yield of anaerobic digestion processes. In particular, the effect of HRT (Hydraulic Retention Time) on the profile of four acidogenic and three methanogenic anaerobic microorganisms in a thermophilic anaerobic digester, for treating toilet paper and organic wastes, was investigated by a quantitative PCR method. The methanogenic activity and population of microbial consortia was found to be stable under a run under an HRT of 35 days and an OLR (Organic Loading Rate) of 2.3 g-CODCr/(L·d), The JC3 strain was found to be the predominant cellulose degrader while the reactor was undergoing stable operation. In the case of a run under an HRT of 23 days, the loss of methanogenic activity could not be recovered by stopping the feeding. However, VFA (Volatile Fatty Acids) accumulation, especially acetate and propionate, continued and the population of genus Methanoculleus could not be recovered.

naerobic digestion, Cellulose-degrading bacteria, Methanogenesis, Thermophilic, Polymerase chain reaction (PCR), Quantitative PCR

Ice Thermal Storage Systems with High-efficiency Heat-pumps for Tokyo Subcenter Metro Subway Line

by Yasunari KURIHARA, & Takehiro KOYAMA

Ice thermal storage systems equipped with high-efficiency heat-pumps have been installed in air-conditioning facilities of Tokyo Subcenter Metro Subway line stations. The main features of these systems are: 1) Use of compact, high-efficiency heat-pumps, 2) Use of compact, high IPF (Ice Packing Factor) container type ice storage tanks, and 3) Use of an optimal air-conditioning control system which can match particular subway power consumption and air conditioning load factors. Compared to using conventional such air conditioning systems, the implementation of these ice thermal storage systems are expected to achieve a 40% reduction in annual running cost and a 24% reduction (670 tons) in CO2 emission.

Heat-pump, Ice making mode, Cooling ice melting mode, Chilling mode, Ice thermal storage system, Ice packing factor, Ice storage tank, Power consumption, Load prediction, Peak adjustment

Environmental Wind Tunnel System for an Overseas Japanese Company

by Sadayoshi TAKAHASHI, Fuminori ETO, Hideaki FUEKI, Wutichai PITUKLERDKUL, & Piya JARASMATUSORN

This wind tunnel system, initially developed for domestic use, had been equipped at an overseas Japanese company facility under a "full turnkey" contract. After reviewing simulation test results according to precision requirements (airflow distribution at the main outlet in particular), decision was made to manufacture and construct the system locally. Favorable airflow performance test results, upon completion of the system, indicated that the wind speed distribution at the 3.0 m section of the main nozzle outlet was below 3%, while the same at the 1 m section of the secondary nozzle outlet was below 1%. These test results confirmed that the precision in airflow distribution was fully adequate. It is expected that this system, an outcome of Ebara's wind tunnel expertise and airflow simulation technology accumulated over many years, will be further developed and see more use in the international market.

Wind tunnel, Environmental, Main fan, Settling chamber, Contraction nozzle, Airflow simulation, Airflow performance, Airflow distribution precision, Sun-light system, Overseas operation

Lecture on Corrosion and Corrosion Protection of Seawater Pumps - Part 4: Numerical Corrosion Analysis -

by Matsuho MIYASAKA

The authors have developed a 2D, 3D and axisymmetric boundary-element-method (BEM) system. This system makes it possible to quantitatively estimate cathodic protection and macro-cell corrosion, such as galvanic corrosion and differential-aeration-cell-corrosion. Understanding the physical quantities (potential and current densities) on the surface of corroding materials is of primary importance in solving corrosion problems, The developed BEM system does not require internal elements discretization which constitutes difficulties when analyzing complicated 3D regions. Internal element discretization is used in conventional analysis techniques, e.g. finite-difference-method (FDM) and finite-element-method (FEM). In this paper, some history on the development of corrosion analysis is introduced, followed by an outline on the BEM and BEM system. Also included are verification experiment results and examples of application for cathodic protection and galvanic corrosion, to demonstrate the analytical accuracy and effectiveness of the BEM system.

Boundary element method (BEM), Corrosion analysis, Cathodic protection, Galvanic corrosion, Seawater, Pump, Potential, Current density, Polarization curve