| Along with the increasingly regard on energy saving, the technology of SeawaterReverse Osmosis System(SWRO) has been rapidly developed recently, as a result ofwhich the energy consumption has been reduced sharply. The reduction of energyconsumption can be attributed to full utilization of Energy Recovery Device(ERD) toa great extent. ERD can be divided into two types: turbine ERD and rotary ERD. Asone of the ratary ERD, Hydro-Drive Rotary Energy Recovery Device(HRERD) ischaracterized by its compact size, easy manipulation, good fluid continuity, becauseof which it has become a hotspot of the research of ERD in recent years.Six kinds of diversion blocks whose impacting angles are67.8°、68.5°、69.9°、72.5°、75.1°and77.9°were designed and processed, then fixed in turn on two endplates made of stainless steel. Then a rotor core were assembled with the end platesand rotor, after which an HRERD was assembled with the rotor core, an outer cylindermade of organic glass and other necessary parts. Then rotating speeds of the HRERDwere measured when the system pressure was at0.6MPa and the flow was at5.1m3·h-1、5.8m3·h-1、6.5m3·h-1、7.1m3·h-1respectively, after which the relationshipbetween rotating speed and system flow, impacting angle could be concluded. A novelpressure resistant cylinder made of stainless steel with a window for rotating speedmeasurement was designed and processed to replace the cylinder made of organicglass. Use it as the outer cylinder of HRERD and then its rotating speeds weremeasured when the system flow was at8m3·h-1、9m3·h-1、10m3·h-1、10.7m3·h-1respectively, after which the relationship between rotating speed and system flow,pressure and impacting angle could be concluded. The results were as follows:(1) therotating speed increases with the increase of system flow;(2) the rotating speedincreases and then decreases with the increase of system impacting angle;(3) With theincrease of pressure, the rotating speed firstly increases into a maximum value, then itdecreases slightly into a non-stable region, lastly it will decrease to zero. The reasonwhy HRERD could not run steadily at high pressures was that the resistance of therotor was too large when it was rotating. The resistance sources may be as follows:⑴the decrease of coaxiality of the rotor;⑵vortex caused by the tapping hole on diversion block;⑶cavition. Several experiments were arranged to explore the reasons,whose results shows that the resistance may be caused by the decrease of coaxiality ofthe rotor and cavitation.This article improved the theoretical formula of the rotating speed of a HRERDwith specific geometric dimensions by amending the computing of kinetic moment ofthe rotor, the resisting moment between the surfaces of the rotor and the rotor sleevein axial and taking resisting moment between the end faces of the rotor and the endplates into consideration. Based on the theorectical formula, the theorectical rotatingspeed was calculated when system flow was4.4m3·h-1、5.0m3·h-1、6.0m3·h-1、7.1m3·h-1respectively. Then the four theorectical rotating speeds were compared with therelevant experimental rotating speeds. The results show that the theoretical rotatingspeeds are slightly larger than the experimental rotating speeds, and the relative errorsbetween them are no more than12%. The errors come from two assumptions duringdeducing, the assumptions are as follows:⑴impacting angles of fluid passagewayswhich are numbered as3#,4#and5#are the same;⑵the side clearance leakagebetween diversion block and rotor was ignored. |
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