转盘式能量回收装置中滑阀的间隙液膜力学特性及结构优化

Mechanical Characteristics of Clearance Liquid Films and Structural Optimization of Slide Valves of Rotary Energy Recovery Device

转盘式能量回收装置(RERD)采用转盘旋转与滑阀协调响应的工作模式实现反渗透海水淡化中浓盐水压力能的连续回收.其中滑阀控制流体流动的方向和流量,它主要的性能要求是切换过程的可靠性.但滑阀中阀杆在偏心和倾斜时与阀套形成的配合间隙不均匀变化会产生不平衡液压力,进而产生液压卡紧并影响滑阀切换的响应性能.针对这一问题,构建了阀杆与阀套的间隙液膜仿真模型,采用CFD方法模拟探究了间隙液膜的力学特性,并引入均压槽和通腔浅槽改善液压卡紧现象.结果表明:阀杆偏心时,间隙液膜形成的每个压力差区段的最大压力差位于高压液体侧,其形成的液压力使阀杆有自动对中的倾向;阀杆倾斜时,间隙液膜中压力差区段的最大压力差在各区段的中间位置,其液压力产生的倾覆力矩会加剧阀杆的倾斜.滑阀间隙液膜的液压力和倾覆力矩随高压流体压力、偏斜率的增大而增大.在阀杆上引入均压槽和通腔浅槽能减小间隙不均匀引起的压力差和液压力的范围,在操作压力6.0 MPa、配合间隙0.015 mm和倾斜率1/3的条件下,滑阀所受液压力和倾覆力矩分别较原结构降低73.4%和70.8%以上.上述结果对装置中滑阀结构优化和提高滑阀响应可靠性具有指导作用.

The rotary energy recovery device(RERD)is an energy-saving equipment which promotes the development and application of reverse osmosis seawater desalination technology.RERD realizes the continuous pressure energy recovery of concentrated brine in reverse osmosis seawater desalination system by adopting a working model of the rotor rotation and through the synchronous response of the slide valves.Slide valves control the direction and flow of fluid and its performance is mainly affected by its switching reliability.However,hydraulic clamping due to unbalanced hydraulic forces highly affects the response performance of slide valves causing a change of the clearances of the slide valve stem with eccentricity and inclination.As a response,simulation models of the liquid films are employed and the hydromechanical characteristics are investigated via CFD method.Equal pressure grooves and a through-cavity shallow groove are introduced to improve hydraulic clamping.Results reveal that when the valve stem is eccentric,the maximum pressure difference for each pressure difference section is achieved on the high-pressure side and the hydraulic force in the liquid film makes the valve stem self-centering.On the other hand,when the valve stem is inclined,the maximum pressure difference in each pressure difference section is located in the middle of each section.The overturning moment generated by the hydraulic force in the liquid film aggravates inclination level,which is prone to hydraulic clamping and blocking.The hydraulic force and its overturning moment in the liquid films increase with higher pressure and greater eccentricity/inclination rate.Reduced pressure difference and decreased gen-eration range of the hydraulic force when inclined were achieved through the introduction of equal pressure grooves and a through-cavity shallow groove.Compared with the original structure,the hydraulic force and overturning mo-ment are reduced by more than 73.4%and 70.8%,respectively upon applying 6.0MPa pressure,and setting the fit clearance and inclination rate to 0.015 mm and 1/3,respectively.The results acquired from this paper hope to provide guidance in the optimization of the structures of slide valves and in the improvement of the reliability of their re-sponse.