Large Vertical Pumps Research Articles

EFFECT OF SUMP GEOMETRY AND SUBMERGENCE DEPTH ON FREE SURFACE VORTEX FORMATION OF PUMP INFLOW

This paper examines and discusses pump sump design as it affects unsteady pump inflow. It is shown that an improvement of the unsteady inflow characteristics can be accomplished by introducing some modifications to the pump sump design. The paper introduces a 3D numerical computation of unsteady flow through a water sump into the intake of a large vertical pump. The numerical simulation is performed using ANSYS CFX. Numerical simulations performed use the shear stress transport model to account for the effect of turbulence. The results obtained were verified by comparison with published experimental data. The effect of the sump geometry and water level on the internal flow in pump sump is presented. Four sump geometries were studied: a rectangular sump, a sump with inclined edge at 30°, a sump with inclined edge at 45°, and a half-circle-ended sump. Also, three submergence levels were studied: S/D = 1.015, 0.771, and 0.54. It is concluded that sumps of rectangular geometry are the best to avoid surface and floor vortex formation.

원통형 수직 펌프의 공진회피를 위한 접수진동해석

Resonance phenomena occurs at large vertical pump which is operating to cool down the hot steam using sea water in the power plant. To avoid the resonance, the natural frequency needs to be isolated about 20% from motor operating speed. Yet, excessive vibration occurs especially at low tide. At first, natural frequency of the whole pump system and each part is calculated using ANSYS. As it is revealed in the previous journal papers that only circular pipe part is related to resonance, the FSI technique is applied for free vibration analysis. The natural frequency is reduced to 60% (compared to that) of the frequency measured in air as it is similar to other published results. And the frequency obtained by finite element analysis is almost same to that obtained from modal test. Based on the accurate finite element model and analysis, design change is tried to avoid the resonance by changing the thickness of pipe and base supporting plate. In stead of doing optimization process, design sensitivity is computed and used to find such designs to avoid resonance.

대형 입형펌프 운전 중 공진현상의 진동 저감을 위한 스티프너 설계 및 성능 검증

This case study presents a practical method to reduce resonant vibration of large vertical pumps. The pumps are driven at 400 rpm rated speed by induction motor. The vibration was not significantly large when operated at this rated speed. Large vibration was occurred when the pump was operated below the rated speed for flow control. Due to the large vibration resonance, variable speed operation of the pump was not possible for several months at worst cases. To find an efficient vibration control method, the flexural responses of pumps for both normal and transient operations were measured. The measured modal characteristics were compared with those of finite element analysis. When the pump was operated at a specific rpm, the natural mode whose resonance frequency is twice the rotating angular speed induced the large vibration. The retrofit utilizing stiffeners to reduce this resonant vibration were performed. Effects of designed stiffeners on reducing vibration were validated through tests after actual installation.

Guide bearing probability load theory of large vertical pump

The factors are analyzed in this paper that influence the guide bearing load of a large vertical pump from structures; errors of design, manufacture, construction and installation of pump unit and assembly. The error randomicity results in the bearing load randomicity. The probability load theory of the guide bearing is established for the first time. Solving methods of the model and characteristics of the bearing probability load are studied. The guiding bearing design load is recommended. The results mean much to rational design, load decrease and increase of service life of the guide bearing.

발전소 대형 입형펌프 전동기의 전류/진동신호 특성 분석

Induction motors are the workhorse of our industry because of their versatility and robustness. The diagnosis of mechanical load and power transmission system failures is usually carried out through mechanical signals such as vibration signatures, acoustic emissions, motor speed envelope. The motor faults including mechanical rotor imbalances, broken rotor bar, bearing failure and eccentricities problems are reflected in electric, electromagnetic and mechanical quantities. The recent research has been directed toward electrical monitoring of the motor with emphasis on inspecting the stator current of the motor, The stator current spectrum has been widely used for fault detection in induction motor systems. The motor current signature analysis is the useful technique to assess machine electrical condition. This paper describes the motor condition detected by the current signatures Paralleled with vibration signatures analysis of induction motors with the roller bearing and the journal bearing type for large vertical pumps in power plant as examples to discuss for motor fault detection and diagnosis.

Optimization of a test platform for large vertical pumps

CETIM recently decided to modify its hydraulic test platform to accommodate very large vertical pumps. To ensure the final set-up would provide the correct conditions, it was first modelled using both a physical scale model and numerical simulation. Robert Pozzoli discusses the project and compares the findings of the two modelling methods.

Hydraulic Design of the Sandow Pumping Plant

Vertical turbine pump installation provides make-up water for cooling pond serving circulating water system of 300 mw steam power plant of Aluminum Co of America near Rockdale, Tex; pumping facility is unusual in its combination of large vertical pumps, long and irregular pipe line profile and surge and flow control problems; hydraulic features of plant described; solutions to some unusual design problems.