除铁器在立式泵磁悬浮轴承中的应用

Applications of Separator in Vertical Pump Magnetic Bearings

磁悬浮轴承立式斜流泵在工作时,输送的流体中往往含有铁磁性颗粒与非磁性颗粒。在磁力的吸引下,铁磁性颗粒易被吸附到磁轴承的工作间隙中并与非磁性颗粒凝聚成团,造成磁轴承磨损。为了解决这个问题,根据磁轴承工作间隙附近流场特性,在现有的立式斜流泵结构上增设一个永磁除铁器装置。考虑多场耦合方式,建立除铁器数学模型。利用数值模拟方法研究除铁器及磁轴承工作间隙周围颗粒相的分布以及其运动情况。结果表明:远离磁轴承工作间隙处的铁磁性颗粒和非磁性颗粒随流场流动方向流动,随之被输运至泵出口;磁轴承工作间隙周围的铁磁性颗粒能够较好地被除铁器吸附,并与非磁性颗粒凝聚成团;随着吸附粒团的增大,由于外围粒团受磁力变小,部分粒团逐渐脱落并被流体带走,这种情况周期性地发生;此外,磁轴承工作间隙周围的被吸附粒团也起到阻止后续颗粒进入磁轴承工作间隙的作用。

Frequently,ferromagnetic and non-magnetic particles are included in the delivery fluid when the vertical mixed flow pump with magnetic bearings works. As the magnetic attraction,the magnetic particles are easily adsorbed to the magnetic bearing gap and united with the non-magnetic particles into a group,causing the magnetic bearing wear. To tackle this issue,magnetic separator device was installed in the existing bearing structure according to the flow field near the magnetic bearing work space. The mathematical model of the separator was created by multi-field coupling way. The distribution and movement of particle phase around the separator and magnetic bearings work space were studied by numerical simulation. The results show that：the ferromagnetic and non-magnetic particles which are away from the magnetic bearing clearance are flowed and transported to the pump outlet;the ferromagnetic particles are attracted around magnetic bearing operating clearance and coagulated into a group with non-magnetic particles;with increase of ad-sorption grain groups,part of the grain groups gradually fall off and are taken away by fluid as the magnetic force of external grain groups is small;the situation occurs periodically. In addition,the group of adsorbed particles around the magnetic bearing gap plays a role to prevent follow-up particles into the magnetic bearing work clearance.