In the modern industrial equipment system, multistage centrifugal pumps, as core fluid transfer devices, are widely used in fields such as petrochemicals, power, municipal engineering, and energy development. Sudden rotor seizure of the equipment not only may cause downtime losses but also may trigger chain safety accidents. In this article, technicians from Changsha Zoomlian Pump Industry, a professional manufacturer of multistage centrifugal pumps, will deeply analyze the systematic causes and solutions of rotor seizure in multistage centrifugal pumps from an engineering practice perspective, hoping to provide you with reference.
I. Common Causes in Operation Management
Improper start-stop operations
Not following the operation norm of "filling liquid first and then starting" may lead to dry running of the impeller, causing thermal deformation. When some enterprises use frequency converters for control, they fail to set soft start parameters, and the instantaneous current impact may cause bearing displacement. A power enterprise once started the equipment without closing the outlet valve, resulting in damage and seizure of the motor bearings.
Deviation of operating conditions from design values
Long-term operation beyond the rated flow rate will increase the radial force on the bearings. Data from a certain chemical project shows that when the flow rate exceeds the rated value by 15%, the bearing life is shortened by 40%. In addition, sudden changes in medium density or abnormal pipeline resistance may trigger the overload protection of the motor torque.
II. Key Vulnerabilities in Maintenance Systems
Lubrication System Failure Modes
Excessive lubrication intervals for bearings or incorrect grease selection can lead to metal fatigue wear. A case study from a steel mill revealed that when ordinary lithium-based grease was used instead of specialized high-temperature grease, the equipment seized up after only 300 hours of operation. It is recommended to adopt an intelligent lubrication system for dynamic monitoring.
Seal Failure Chain Reaction
If mechanical seal leakage is not promptly addressed, the medium can invade the bearing housing, causing the lubricating medium to emulsify. For equipment transporting corrosive media, seal failure is more likely to trigger electrochemical corrosion of the bearings.
III. Aging Mechanisms of Key Components
Evolution Process of Bearing Failure
Excessive bearing clearance will lead to an increase in vibration values. When the vibration intensity exceeds the G2.8 level of the ISO10816-3 standard, the machine should be immediately shut down for maintenance. It is recommended to use vibration sensors for early warning.
Wear Law of Flow-Through Components
For every 0.1mm increase in the clearance between the impeller and the guide vanes, the equipment efficiency drops by 1.2%. A certain thermal power plant discovered through 3D scanning technology that when the wear of the impeller mouth ring caused the clearance to expand to 0.8mm, the operating noise of the equipment increased by 15 decibels.
IV. Influencing Factors of Medium Characteristics
Hazard Level of Solid Particles
When the solid content in the medium exceeds 0.5%, it is recommended to install a multi-stage filtration system. A certain mining project failed to install a cyclone separator, resulting in clogging of the impeller channel and periodic seizing faults.
Scale Risk Control Strategy
For media with high calcium and magnesium ion content, it is recommended to use an online acid washing system. Dynamically adjusting the dosage of scale inhibitor based on water quality analysis data can effectively control the scaling rate.
The rotor seizing problem of multi-stage centrifugal pumps is essentially an external manifestation of systematic management issues. Zoomlian Pump Industry suggests that enterprises establish a "prevention-oriented, data-driven" operation and maintenance system, combining intelligent monitoring technology with professional services to achieve reliability management throughout the equipment's life cycle.