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Ebara Engineering Review No.210

Assessment of Creep Damage in a Nickel-based Super-alloy by Electromagnetic Acoustic Resonance

by Electromagnetic Acoustic Resonance
by Toshihiro OHTANI, Hirotsugu OGI, & Masahiko HIRAO

The microstructural evolution of Waspaloy, a nickel-based super-alloy, was studied using EMAR (Electromagnetic Acoustic Resonance). The Waspaloy was subjected to tensile creep at 1073 K and shear-wave attenuation and velocity was monitored by EMAR. Taken into account was the observation that contact-less transduction based on the Lorenz force mechanism was the key to establishing the monitoring of microstructural changes in the bulk of highly sensitive metals. A clear relationship was found between attenuation and life fraction. In the interval, 35% to 40% of the creep life, attenuation reached a peak, independent of applying stress. This novel phenomenon was interpreted as being a drastic change in dislocation mobility and the coarsening of γ'- precipitates. This was supported by SEM and TEM observations. During the occurrence of this phenomenon, dense dislocations started to tangle to γ'- precipitates, with the coarsening and condensation of γ'- precipitates becoming saturated. It was thus established that it was possible to use this EMAR assessment method to assess the progress of damage in metals and predict their remaining creep life.

Keywords
Creep damage, Ni-base superalloy, EMAT, Ultrasonic attenuation, Non-contact evaluation, Dislocation

Analysis on Characteristics of a Boosted Temperature type Absorption Heat Pump

by Naoyuki INOUE, Kiichi IRIE, & Yukihiro FUKUSUMI

Theoretical analysis was conducted on various absorption cycles, assuming reversible cycles, in an effort to improve the performance of a boosted temperature type absorption heat pump. Comparison was made using the Carnot cycle to estimate the COP, temperature boost and maximum performance. A simulation model assuming the usage of H2O-LiBr as the working fluid was developed to study the performance. It was found that a direct flow of heat source hot water from a generator to an evaporator was favorable for high performance.

Keywords
Absorption, Heat pump, Absorption cycle, Temperature boost, Steam generation

Development of Fuel-cell Type, Backup Power Generation System for Traffic Signals

by Yutaka MORI, Kazufumi TATEISHI, Kazunori YOSHIDA, & Koichi WADA

A novel backup power generation system for traffic signals, featuring the use of a hydrogen-based polymer electrolyte fuel cell, has been developed. A performance test is now underway using a prototype for traffic signals at an actual intersection. This highly reliable, safe and compact system's operational features are quick startup, favorable performance under load, no performance drop due to vehicular exhaust gas constituents, operability under high and low temperature (including that under direct sunlight exposure). The following discusses this systemOs development factors and performance test results.

Keywords
Fuel cell, Polymer electrolyte fuel cell, Backup power generation, Traffic signal, Light emitting diode tight lamp, Power failure, Hydrogen cylinder

High Discharge Pressure (50 MPa Class) De-scaling Pump

by Kikuo NISHIYAMA

A high discharge pressure de-scaling pump, capable of being operated at a discharge pressure of 50 MPa and coupled with a rapid variable-speed coupling, has been developed. Fatigue-causing high amplitude and high cycle stress applying on the pump has been coped with by an elliptically shaped nozzle opening section which reduces stress concentration in this section.

Keywords
De-scaling pump, Barrel casing, Thick-wall vessel, Nozzle, Fatigue, Meridional stress, Hoop stress, Stress concentration, Throttle bush, Hard chromium plating

Circulating Water Pumps for Jiaxing Power Plant, Zhejiang Province, China

by Toshiaki KIKUIRI

A total of 8 EBARA circulating water pumps have been installed at Jiaxing Power Plant, Zhejiang Province, China. These pumps feature an elongated total length to cope with high differential tides. Adjustable vane angle pumps are also used to optimize plant operation. Special foreign-made actuators are used for the vane angle control units, Cathodic protection is applied for corrosion resistance. The following outlines these pumps.

Keywords
Circulating water pump, Adjustable vane angle, Vane angle control, Anti-corrosion device, Cathodic protection, High differential tide, Actuator, Distributing valve, Self-potential, Condenser

Large Diameter Conical Plug Valves for Chicago's Tunnels and Reservoirs

by Naobumi IKEDA, Mitsutoshi HAGINO, Takao MIYAMOTO, & Daisuke MIKAMI

A total of six large-diameter, conical plug valves have been shipped to Chicago, U.S.A. to be used for flood control in Chicago's Tunnel and Reservoir Plan. Two of these valves were designed for use under high flow rates (45 m/sec.), at 30 minute opening and closing time, and to withstand occurrences of erosion, noise and vibration due to cavitations following opening/closing. As a measure against erosion, the plug body and plug were made from stainless steel plates and overlays. Compressed air injection ports have been installed to lessen cavitation and a large-capacity/high-lift-capable operator has been applied for coping with high torques. Lubricant-injection type bearings have been installed to enable lubrication. A water resistant, proximity switch system is also implemented for cylinder location detection.

Keywords
Conical plug valve, Mechanism for open and close, High velocity, Cavitation, Stainless steal overlay, Proximity switch, Dynamic torque, Lubrication system, Shut-off torque, Stress analysis by computer