Analysis of Severe Erosion in Industrial Centrifugal Slurry Pumps

2013 ◽  
Author(s):  
Jafar Madadnia ◽  
Mostafa Amjad ◽  
Jeffry Kusnan
Keyword(s):  
Leading Edge ◽  
Centrifugal Pumps ◽  
Wear Model ◽  
Experimental Modelling ◽  
Flow Acceleration ◽  
Field Samples ◽  
Severe Erosion ◽  
Slurry Flows ◽  
In Series ◽  
Numerical Research

Centrifugal pumps designed for homogenous slurries experience inefficiency, off-design operations, shorter service-life expectancy, and rapid geometry change due to localized and uneven erosion. Experimental and numerical research to design erosion-free pumps has been inconclusive due to complexity of heterogeneous, multiphase slurry flows and mechanism of the localized material losses. This paper reports on erosion-effects of slurry flows on a number of industrial centrifugal pumps selected from an active copper mine field. The field samples include three metallic pumps operating in a serial-arrangement, and a number of worn pump-components with fully rubber-lined or metallic wetted-surfaces. Physical samples were also collected and photographed under an electronic microscope. The analysis of the photographs shows directional groves, ripples-formations, pitting, cavities, spots, and abrasive-embedding on the pump surfaces. The effected regions included a) hub or tip of the vane leading edge of impellers, b) internal and external surfaces of shroud and downstream of expellers, c) front-liners/throat bush all at the proximity of the inlet throat/tube, and d) Volute surface close to the discharge throat/tube on the spiral tail. Analysis of eroded regions suggests a combination of mechanisms some similar with those found with a sustained flow acceleration and momentum change towards a surface. A wear model is therefore recommended for the severe erosion in pumps which resembles erosion by cavitation. To further understand and verify the finding and to be able to predict and to avoid accelerated-erosion, an experimental modelling and a numerical modelling of slurry flows in two identical-centrifugal-pumps are conducted in series and preliminary results are presented. The project is in progress.

Role of Dissipation Characteristics in Predicting Flow from Dissimilar Centrifugal Pumps

1994 ◽  
Vol 208 (4) ◽  
pp. 285-294 ◽  
Author(s):  
E A Bunt ◽  
B Parsons ◽  
F Holtzhausen
Keyword(s):  
Flow Characteristics ◽  
Maximum Flow ◽  
Centrifugal Pumps ◽  
Graphical Solution ◽  
Dissipative Flow ◽  
In Series ◽  
Lower Maximum ◽  
Output Field ◽  
High Series

Examination of flows in a particular case of dissimilar pumps coupled in series or in parallel (without check valves) showed that the ‘classical’ graphical solution of combined characteristics in the [+H, +Q] quadrant did not accord with the output field in certain regions. To predict the full flow fields, it was necessary to take into account dissipative flow characteristics in two other quadrants: for low-output parallel flow (when there is still flow available from the pump of higher head when the ‘weaker’ pump's flow has been reduced to zero), that in the [+H, –Q] quadrant; and for high series flow (after the output head of the pump of lower maximum flow has been reduced to zero), that in the [–H, +Q] quadrant. This problem does not arise when the pumps have identical characteristics.

scholarly journals Break-before-Make CMOS Inverter for Power-Efficient Delay Implementation

2014 ◽  
Vol 2014 ◽  
pp. 1-11 ◽  
Author(s):  
Janez Puhan ◽  
Dušan Raič ◽  
Tadej Tuma ◽  
Árpád Bűrmen
Keyword(s):  
Short Circuit ◽  
Energy Charge ◽  
Leading Edge ◽  
Optimization Procedure ◽  
Short Circuit Current ◽  
Delay Element ◽  
Cmos Inverter ◽  
Power Efficient ◽  
In Series ◽  
Detector Cell

A modified static CMOS inverter with two inputs and two outputs is proposed to reduce short-circuit current in order to increment delay and reduce power overhead where slow operation is required. The circuit is based on bidirectional delay element connected in series with the PMOS and NMOS switching transistors. It provides differences in the dynamic response so that the direct-path current in the next stage is reduced. The switching transistors are never ON at the same time. Characteristics of various delay element implementations are presented and verified by circuit simulations. Global optimization procedure is used to obtain the most power-efficient transistor sizing. The performance of the modified CMOS inverter chain is compared to standard implementation for various delays. The energy (charge) per delay is reduced up to 40%. The use of the proposed delay element is demonstrated by implementing a low-power delay line and a leading-edge detector cell.

A Numerical Investigation Into the Interaction Between Current Flow and Fuel Consumption in a Segmented-in-Series Tubular SOFC

2009 ◽  
Vol 6 (3) ◽  
Author(s):  
B. A. Haberman ◽  
A. J. Marquis
Keyword(s):  
Density Distribution ◽  
Fuel Consumption ◽  
Current Density ◽  
Current Flow ◽  
Flow Direction ◽  
Ionic Current ◽  
Leading Edge ◽  
Current Density Distribution ◽  
Fuel Flow ◽  
In Series

A typical segmented-in-series tubular solid oxide fuel cell (SOFC) consists of flattened ceramic support tubes with rows of electrochemical cells fabricated on their outer surfaces connected in series. It is desirable to design this type of SOFC to operate with a uniform electrolyte current density distribution to make the most efficient use of the available space and possibly to help minimize the onset of cell component degradation. Predicting the electrolyte current density distribution requires an understanding of the many physical and electrochemical processes occurring, and these are simulated using the newly developed SOHAB multiphysics computer code. Of particular interest is the interaction between the current flow within the cells and the consumption of fuel from an adjacent internal gas supply channel. Initial simulations showed that in the absence of fuel consumption, ionic current tends to concentrate near the leading edge of each electrolyte. Further simulations that included fuel consumption showed that the choice of fuel flow direction can have a strong effect on the current flow distribution. The electrolyte current density distribution is biased toward the upstream fuel flow direction because ionic current preferentially flows in regions rich in fuel. Thus the correct choice of fuel flow direction can lead to more uniform electrolyte current density distributions, and hence it is an important design consideration for tubular segmented-in-series SOFCs. Overall, it was found that the choice of fuel flow direction has a negligible effect on the output voltage of the fuel cells.

Endwall Heat Transfer Measurements in a Staggered Pin Fin Array With an Adiabatic Pin

2007 ◽  
Author(s):  
Forrest E. Ames ◽  
Chad A. Nordquist ◽  
Lindsay A. Klennert
Keyword(s):  
Heat Transfer ◽  
Turbulent Transport ◽  
Infrared Camera ◽  
Leading Edge ◽  
Reynolds Numbers ◽  
Skin Friction Coefficient ◽  
Vortex System ◽  
Flow Acceleration ◽  
Pin Fin ◽  
Pin Fin Array

Full surface endwall heat transfer distributions have been acquired in a staggered pin fin array with the use of an infrared camera. Values are presented at Reynolds numbers of 3000, 10,000 and 30,000 based on pin diameter and average velocity through adjacent pins. Average endwall Nusselt numbers agree closely with archival values at each Reynolds number. Locally averaged heat transfer levels show a substantial increase from the inlet through the first few rows and finally a nearly streamwise periodic condition in the second half of the eight row geometry. Increasing levels of heat transfer in the inlet region can be attributed to the leading edge vortex system, flow acceleration around pins, and the generation of turbulence. Distributions of turbulence intensity and turbulent scale are shown to help document the turbulent transport conditions through the array. Detailed endwall Nusselt number distributions are presented and compared at the three Reynolds numbers for the first four and last four rows. These detailed heat transfer distributions highlight the influence of the horseshoe vortex system in the entrance region and the wake generated turbulence throughout the pin fin array. Local velocity and turbulence distributions are presented together with local Stanton number and skin friction coefficient data to examine the aggressive nature of the turbulent mixing.

scholarly journals Experimental Investigation and Passive Flow Control of a Cavitating Centrifugal Pump

2012 ◽  
Vol 2012 ◽  
pp. 1-8 ◽  
Author(s):  
Spyridon D. Kyparissis ◽  
Dionissios P. Margaris
Keyword(s):  
Flow Control ◽  
Centrifugal Pump ◽  
Leading Edge ◽  
Total Efficiency ◽  
Centrifugal Pumps ◽  
Pump Performance ◽  
Passive Flow Control ◽  
Passive Flow ◽  
Pump Test ◽  
Blade Leading Edge

Passive flow control techniques are used to improve the flow field and efficiency of centrifugal pumps and turbomachines, in general. An important phenomenon that mechanical engineers have to take into account is cavitation. It leads to the decrease of the pump performance and total head. In the present experimental study, a centrifugal pump is investigated in cavitating conditions. A passive flow control is realized using three different blade leading edge angles in order to reduce the cavitation development and enhance the pump performance. The experiments are carried out in a pump test rig specially designed and constructed, along with the impellers. The head drop and total efficiency curves are presented in order to examine the effect of the blade leading edge angle on the cavitation and pump performance. Finally, the vapour distribution along with the blades is illustrated for the tested blade leading edge angles.

Dynamics of a Large Scale Hydraulic Capsule Pipeline System

1999 ◽  
Vol 124 (1) ◽  
pp. 191-195 ◽  
Author(s):  
Hongliu Du ◽  
Satish S. Nair
Keyword(s):  
Large Scale ◽  
Control Method ◽  
Experimental Studies ◽  
Small Scale ◽  
Pipeline System ◽  
Centrifugal Pumps ◽  
Long Distance ◽  
Column Separation ◽  
In Series ◽  
Hydraulic Capsule Pipeline

The dynamics of a booster station, which is critical for the control of a novel, long distance, hydraulic capsule pipeline, is simulated mathematically for design studies and control of the hydraulic transients caused by the valve actuators in the system. Several modifications to the pump bypass station configuration of the booster station have been studied. With the objective of eliminating column separation and reducing flow reversals, a configuration with several centrifugal pumps connected in series, and a carefully sized air chamber is found to be a viable design. A valve control method is designed to eliminate column separation and the design results in acceptable flow reversal levels in the main pipe. The simulation results match with trends in limited experimental studies performed on a small scale experimental capsule pipeline system.

Delay of Rotating Stall in Compressors Using Plasma Actuators

2016 ◽  
Vol 138 (9) ◽  
Author(s):  
Farzad Ashrafi ◽  
Mathias Michaud ◽  
Huu Duc Vo
Keyword(s):  
Centrifugal Compressor ◽  
Leading Edge ◽  
Plasma Actuator ◽  
Rotating Stall ◽  
Tip Clearance ◽  
Compressor Stage ◽  
Dbd Plasma ◽  
Two Stage ◽  
Stall Inception ◽  
Flow Acceleration

Rotating stall is a well-known aerodynamic instability in compressors that limits the operating envelope of aircraft gas turbine engines. An innovative method for delaying the most common form of rotating stall inception using an annular dielectric barrier discharge (DBD) plasma actuator had been proposed. A DBD plasma actuator is a simple solid-state device that converts electricity directly into flow acceleration through partial air ionization. However, the proposed concept had only been preliminarily evaluated with numerical simulations on an isolated axial rotor using a relatively basic CFD code. This paper provides both an experimental and a numerical assessment of this concept for an axial compressor stage as well as a centrifugal compressor stage, with both stages being part of a low-speed two-stage axial-centrifugal compressor test rig. The two configurations studied are the two-stage configuration with a 100 mN/m annular casing plasma actuator placed just upstream of the axial rotor leading edge (LE) and the single-stage centrifugal compressor with the same actuator placed upstream of the impeller LE. The tested configurations were simulated with a commercial RANS CFD code (ansys cfx) in which was implemented the latest engineering DBD plasma model and dynamic throttle boundary condition, using single-passage multiple blade row computational domains. The computational fluid dynamics (CFD) simulations indicate that in both types of compressors, the actuator delays the stall inception by pushing the incoming/tip clearance flow interface downstream into the blade passage. In each case, the predicted reduction in stalling mass flow matches the experimental value reasonably well.

scholarly journals Numerical Research on Hydraulically Generated Vibration and Noise of a Centrifugal Pump Volute with Impeller Outlet Width Variation

2014 ◽  
Vol 2014 ◽  
pp. 1-13 ◽  
Author(s):  
Houlin Liu ◽  
Jian Ding ◽  
Hanwei Dai ◽  
Minggao Tan ◽  
Xiaochen Tang
Keyword(s):  
Noise Level ◽  
Sound Radiation ◽  
Fem Analysis ◽  
Centrifugal Pumps ◽  
Pressure Pulsations ◽  
Performance Pressure ◽  
Impeller Outlet ◽  
Numerical Research ◽  
Structure Vibration ◽  
Vibration And Sound Radiation

The impeller outlet width of centrifugal pumps is of significant importance for numbers of effects. In the paper, these effects including the performance, pressure pulsations, hydraulically generated vibration, and noise level are investigated. For the purpose, two approaches were used to predict the vibration and sound radiation of the volute under fluid excitation force. One approach is the combined CFD/FEM analysis for structure vibration, and then the structure response obtained from the FEM analysis is treated as the boundary condition for BEM analysis for sound radiation. The other is the combined CFD/FEM/BEM coupling method. Before the numerical methods were used, the simulation results were validated by the vibration acceleration of the monitoring points on the volute. The vibration and noise were analyzed and compared at three flow conditions. The analysis of the results shows that the influences of the sound pressure of centrifugal pumps on the structure appear insignificant. The relative outlet widthb2*atnq(SI) = 26.7 in this paper should be less than 0.06, based on an overall consideration of the pump characteristics, pressure pulsations, vibration and noise level.

An Experimental Investigation on the Erosion of a Helico-Axial Pump With Gas Presence

2020 ◽  
Author(s):  
Yi Chen ◽  
Abhay Patil ◽  
Yiming Chen ◽  
Gerald Morrison ◽  
Marisela Rojas
Keyword(s):  
Volume Fraction ◽  
Pressure Rise ◽  
Leading Edge ◽  
Oil And Gas Industry ◽  
Performance Degradation ◽  
Oil Field ◽  
Tip Clearance ◽  
Centrifugal Pumps ◽  
Impeller Blade ◽  
Axial Pump

Abstract Electrical submersible pump (ESP) technology has been widely applied in the oil and gas industry due to its high productivity. However, erosion always causes the reduction of productivity and sometimes even the failure of an ESP system. This study explores the effect of gas presence on erosion mechanism on an ESP which is composed of 4 stages of Helico-Axial Pump (HAP). A 200-hour erosion test has been performed on this ESP. During the test, the ESP was running at 3600 RPM with a liquid flow rate of 880 GPM, 20% inlet Gas Volume Fraction (GVF), and 0.24% sand concentration by weight. Performance tests were conducted every 50 hours to acquire the performance maps and monitor the performance degradation. Analysis of volume/weight loss and performance degradation is conducted to investigate pump wear. Two types of erosion are found at the impeller: the volume loss found notably at the leading edge is mainly caused by two-body impact erosion, while the tip clearance increment between the impeller housing and impeller blade tip is mainly caused by the three-body abrasive erosion. Unlike most conventional centrifugal pumps, there is no observable wear found at the trailing edge of the impeller. The presence of the gas shows a negative effect on both types of erosion. The consequence of the erosion is the performance degradation, especially at the condition with higher pressure rise. It is suggested to apply this HAP in the oil field with more gas and higher bottom hole pressure.

Sign in / Sign up

Export Citation Format

Share Document