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Ebara Engineering Review No.231

Cavitation CFD and the Prediction of Cavitation Erosion

by Motohiko NOHMI

Considerations on the erosive cavitation phenomenon, an overview on the recent progress in cavitation CFD, and trends in the development of erosion prediction methods are introduced in the following. Cavitation Erosion occurs due to impact loadings caused by the collapse of cavitation bubbles in the vicinity of an object. Although this phenomenon can be analyzed at a single bubble level, analysis is extremely difficult at a bubble cluster level. Cavitation CFD, which is using an approximating method called cavitation model, enables comprehensive analysis and is applied in estimating pump head breakdown. A number of proposals have been submitted for predicting probable erosion zones and obtaining quantitative erosion rate by estimating erosion intensity levels based on cavitation CFD results. Significant studies on a trial basis are underway but a decisive method has yet to be found, thus making further research necessary.

Cavitation, CFD, Erosion, Bubble, Bubble Collapse, Impact Loadings, Micro Jet, Energy Cascade, Cavitation Model, Pit

Steam Generation System Utilizing Low-temperature Waste Hot Water

by Yukihiro FUKUSUMI, Keisuke KAJIYAMA, & Motoki FUJIMURA

A new steam generation system, capable of generating 0.3 - 0.6 MPa(G) of steam from low-temperature waste hot water (80 - 90 degrees C) and other thermal sources, has been developed for providing as a heat source for various facilities in a factory. This enables good use of low-temperature hot wastewater which is normally discharged for being unsuitable as a heat source. By the new system an absorption heat pump, driven by low temperature hot water, generates low pressure steam of 0.1 - 0.2 MPa(G). A steam ejector is then used to pressurize the steam to 0.3 - 0.6 MPa(G). This system was co-developed with Tokyo Gas, Miura

Waste heat, Waste hot water, Steam generating, Absorption heat pump, Absorption cycle, Steam ejector, Temperature boosting, Pressure boosting, Cogeneration system

Combustion Type Gas Abatement System (G5 Series)

by Keiichi ISHIKAWA

Recent demand in combustion type gas abatement systems include not only stable and high performance but also low running cost (energy saving) and improved operability. Ebara's G5 series achieves energy saving by an on-demand operation featuring a quick startup burner. Its automatic scraper system removes by-products produced after the abatement, thus improving operability. The system also uses water falls and a port for visual inspection of the system interior. It is capable of high level gas abatement, is compact and its maintenance can be done easily.

Combustion type abatement system, Per fluoro compounds, Energy saving, On-demand operation, Low running cost, Quick startup, High operability, Transparent PVC material, Measure against by-products, Water wall

Reductions in CO2 Emission and Cost by Turbine Power Generation during Incineration

by Tsutomu MIENO

Ebara Environmental Plant Co., Ltd. has been contracted to manage a waste incineration facility which it had shipped to Saga Municipal Waste Incineration Plant. Under supervision by Saga City, an energy saving operation is underway making effective use of heat from waste incineration to generate electric power. A reduction in CO2 emission is also being achieved. In the 3 years between 2007 and 2009, the reduction of CO2 emission by the saving in power consumption reached about 1290 tons (equivalent value), thus contributing to not only to the reduction of global warming gas emission but also to cost saving.

Municipal solid waste incineration plant, Operation technology, Energy saving, Reduction of Carbon dioxide emission