LNG接收站高压泵平衡机构优化及计算流程研究

Study on optimization and calculation process of high pressure pump balancing mechanism in LNG receiving station

国内某LNG接收站共设置4台高压泵,出厂设计级数18级,该高压泵自投入运行以来,一直采用13级方案,后5级用过流件替代,运行期间一切性能指标正常。增加至18级方案后,运行约3000 h时(正常运行周期25000 h),4台泵先后均出现振动、噪声值增加,振速由1.6 mm/s增大至4 mm/s;该故障属共性问题,对泵解体检查后发现轴承压盖端面、轴承外圈内侧有磨损。经分析导致振速增大的根本原因是由于轴承的损坏所致,即增加5级叶轮后,平衡机构前后压差增大,平衡力增大,导致残余轴向力偏大,致使轴承运行寿命缩短。该文研究了优化高压泵平衡机构和降低残余轴向力的方案,并归纳出了平衡装置优化计算流程,可推广应用于平衡机构采用双平衡鼓结构的多级泵中。

LNG receiving station set up 4 high pressure pumps,The pump design grade of 18.This high pressure pump has always adopted a 13 grade since it was put into operation,and the last 5 grades have been replaced by flow components.All performance indexes are normal during operation.After increasing to the 18-stage,the vibration and noise value of the 4 pumps successively increased when operating for about 3000 h(25000h normal operating cycle),and the vibration speed increased from 1.6 mm/s to 4 mm/s.The fault is a common problem.After disassembly inspection of the pump,bearing cover end face and inside the bearing outer ring was found wear.The fundamental reason for the increase of vibration velocity is the damage of bearing,that is,after adding 5-stage impeller,the pressure difference between the front and back of the balancing mechanism increases,and the balance force increases,leading to the larger residual axial force and the shorter running life of the bearing.In this paper,how to optimize the balancing mechanism of high pressure pump and reduce the residual axial force is described in detail,and the optimized calculation process of balancing device is summarized,which can be widely used in multi-stage pumps with double balancing drum structure.