Impeller Wear Research Articles

Incipient fault detection for the spindle bearing of a cement grinding machine based on vibrational resonance

Abstract The spindle bearing of a circulation fan is an important component of a cement grinding machine. In addition to the faults on the spindle bearing, impeller wear and ash accumulation may cause dynamic unbalance and complex vibration interference as noise, which decreases the accuracy of fault detection based on vibrational signals and traditional signal processing-based methods at the early stage of a bearing fault. To address this issue, this paper presents a new fault detection method for the spindle bearing by utilizing extra injected noise and vibrational resonance. To enhance the fault signature and resonance performance, the nonlinear system of the traditional vibrational resonance is replaced by a new hybrid steady-state system, and the underdamped term is considered in the new system. The proposed system provides more possibilities to achieve resonance by adjusting the system parameters and overcomes the limitations of output saturation caused by the classical bistable system. The proposed method is validated by analyzing the collected vibration signals from a spindle bearing of a circulation fan in practice and is compared with other noise-elimination fault detection methods. The results demonstrate the effectiveness and superior performance of the proposed method.

Study on the influence of sediment erosion of Francis turbine runner under different water heads

Abstract The average measured sediment concentration of the river section where Wanjiazhai Hydropower Station is located over the years is 5.7kg/m 3, The maximum measured sediment concentration reaches 37.6kg/m 3, The erosion of the flow components of hydraulic turbines caused by sand containing water flow is becoming increasingly severe, coupled with the frequent impact of load changes during peak shaving operation, the problems exposed during the operation of hydraulic turbines are becoming more prominent, which affects the stable operation of the units. This article uses numerical simulation and experimental testing to study the sediment wear characteristics and hydraulic performance of the water turbine at Wanjiazhai Hydropower Station. Research has revealed the effects of working head on impeller wear. The increase in working head will exacerbate the impact wear on the main channel wall of the unit. The surface of water turbine blades is the main wear area, and the high-speed impact of particles causes an increase in the wall wear rate. The probability of particles coming into contact with the wall at the outlet increases, resulting in rapid wear at this point. The increase in head will intensify the wear intensity of the unit surface, and the flow velocity in the gap indicates that the local high-speed jet in the gap is the main cause of gap wear. Therefore, in order to ensure the efficient anti-wear performance of the water turbine, multiple factors need to be comprehensively considered to cope with sediment wear of the water turbine, including regular cleaning, optimized structural design, use of wear-resistant materials, replacement of worn parts, and optimization of operating parameters. These measures help to reduce the damage of sediment wear to water turbines and extend their service life.

Study on the effect of impeller wear on dredging pump performance under medium-coarse sand conditions

Study on the effect of impeller wear on dredging pump performance under medium-coarse sand conditions

Correlation development of erosive wear and silt erosion failure mechanisms for pump as turbine

One of the factors contributing to the gradual decline in the performance as well as the failure of hydropower plants over the years is silt erosion. Several researchers have developed empirical correlations for the prediction of erosive wear of hydro turbines, but these correlations are not directly applicable in practice as the materials examined for the impeller blades were different from the actual impeller material. In this study, an effort has been made to experimentally evaluate the silt erosion of the Pump as Turbine (PAT). The novelty of the study is to use the same material (SS304) for the specimens used for the analysis as well as for the impeller. The experiments were performed with three silt sizes of 100–350 μm, 350–700 μm, and 700–1000 μm; with three different silt concentrations of 0.75 %, 1 %, and 1.25 % for the duration of 18 hrs, 36 hrs, and 54 hrs. An empirical correlation is established for the assessment of normalized wear of the PAT impeller in terms of silt size, concentration, and operating time based on the experimental data. This correlation can be utilized to estimate normalized erosive wear of PAT impeller made up of SS304 material with an inaccuracy of ±15 %. According to the analysis, silt concentration was found to be a more significant parameter in causing erosion than silt size. Additionally, scanning electron microscopy was used to conduct a thorough analysis of the erosive failure mechanism of SS304 specimens. According to the analysis, silt size was observed to be an important factor in producing various types of erosive failures. The material removal from the substrate’s surface was found to be caused by plastic deformation and surface ploughing.

Water Wells’ Rehabilitation: A Case Study of Northern Part of Ekiti East Local Government Area, Southwestern Nigeria

Potable water is scarce during dry season (October to March) each year in the northern part of Ekiti East Local Government Area, southwestern Nigeria. Rain harvested water serves as alternative source of water during the rainy season. Other forms of surface water are often contaminated by open defecation apart from being expensive to treat and circulate to points of needs. The area of study lacks pipe borne water and a good number of boreholes in the area had lost their original yield while some had completely broken down due to mineral sediments, screen incrustation, silt fill-up bottom sump, submersible pump coil damage, impeller wear, faulty grouting and cementation. In order to have access to potable groundwater, rehabilitation was carried out on abandoned water wells which were earlier drilled through government intervention being fairly cheaper than constructing new boreholes. Rehabilitation of these wells was done by removing the submersible pump, flushing and back washing with pressured water, air lifting, grout reconstruction and cementation, which restored the yield of these water wells to their original yield. The results had shown that the borehole rehabilitation in northern part of Ekiti East Local Government Area will provide sustainable water borehole yield but to avoid well yield shortage, borehole in this area must be flushed with compressed air or high pressure water at the end of raining season every year because of thick overburden peculiarity of boreholes in the study area which comprise of Ilasa, Ikun/Araromi, Ishaya, Kota, part of Omuo-Oke and Omuo-Ekiti.

Experimental Study on the Influence of Particle Diameter, Mass Concentration, and Impeller Material on the Wear Performance of Solid–Liquid Two-Phase Centrifugal Pump Blade

A centrifugal pump is an important solid–liquid mixture conveying machinery, which is widely used in mineral mining, water conservancy engineering, and other fields. Solid particles will wear the impeller of the centrifugal pump in the process of transportation, resulting in lower service life of the impeller, especially in the transportation of a high concentration of solid particles. Many scholars use numerical simulation to study the wear of centrifugal pumps, but few efforts have been made in the wear experiment. In this study, the effect of three factors, namely, diameter of solid particles, mass concentration of particles, and material of impellers on the wear of a solid–liquid two-phase centrifugal pump was studied by the wear experiment. The solid particles are SiO2 with irregular shapes, and the diameter ranges are 0.125–0.212 mm, 0.212–0.425 mm, and 0.425–0.710 mm. The mass concentration of solid particles is 15%, 20%, and 30%. The material of impellers is carbon structural steel (Q235), gray cast iron (HT200), and low-alloy high-strength steel (16 Mn). The amount of wear is determined by measuring the thickness of the impeller material before and after wear experiments. The wear morphology of the impeller was observed by using a digital microscope. The results showed that the wear mainly concentrated on the middle and trailing edges of the blade. Impellers of different materials suffer different wear forms, among which the impeller made of HT200 has the best erosion resistance. The increase of solid mass concentration will aggravate the wear of the impeller. The change of particle diameters also has a great influence on impeller wear.

An experimental insight into dynamic characteristics and wear of centrifugal pump handling multi-size particulate slurry

The river water has a high sand content and the characteristics of mixed distribution of sand particles with different diameters. The effect of sand particles on the dynamic characteristics and wear of centrifugal pumps is an important issue when handling particulate slurry. The objective of this work is to establish the effect of flow rate and sand volume concentration variation on pump energy performance, outlet pressure pulsation, pump body vibration, and pump impeller wear. Experiments were conducted in a pilot plant test rig with five flow rates and three particle concentrations based on multi-size particulate slurry. It was observed that the head and efficiency of the centrifugal pump decrease with the increase of sand concentration, whereas the effect of small sand concentration on the energy performance of the pump is weak. The larger the flow rate of centrifugal pump, the lower the pressure pulsation and vibration intensity of pump body, but the more serious the impeller wear. When the sediment concentration increases, the pressure pulsation at the pump outlet and the vibration intensity of the pump body increase, and the impeller wear is more serious. In addition, with the increase of pump operation time, the outlet of blade pressure surface, the middle area of blade suction surface and the outlet area of impeller back shroud passage are seriously worn, and the outlet of blade pressure surface is the most serious.

Mechanized complex of mine water purification from large mechanical impurities

It is well known that the main reason for the failure of sectional pumps in underground mines is the extensive hydroabrasive wear of their impellers. The rate of hydroabrasive wear of the impellers of sectional pumps largely depends on the size of solid particles contained in mine waters. Within the framework of this research work, in order to reduce the rate of hydroabrasive wear of parts of the flow path of sectional pumps of mine drainage installations, in particular impellers, a mechanized complex was developed and sufficiently substantiated for cleaning mine water from large solid particles. It is based on the use of a hydrocyclone and a high-frequency screen. Introduction of the developed technical solution in mine drainage systems will reduce the intensity of hydroabrasive wear of sectional pump impellers.

Wear mechanism investigation in a centrifugal slurry pump impeller by numerical simulation and experiments

Centrifugal slurry pumps are widely used in ore mining, metal smelting, petrochemical and other industries. They are mainly used to transport muddy fluids containing a large number of solid particles. The impellers in slurry pumps always experience serious wear with damages the equipment. This study analyzed the flow in a slurry pump to identify the key sources of the wear. A centrifugal slurry pump was analyzed using the particle Eulerian-Eulerian multiphase flow model to study the impeller wear. The results show that increasing the flow rate causes the high solid volume fraction area to gradually move along the suction surface from the inlet to the outlet. At over-load flow rate, the high volume fraction area moves to the junction of the blade and the rear shroud. For the same conditions, increasing the concentration reduces the pump lift and efficiency, gradually increases the solid slip velocity at the blade outlet, and creates higher solid volume fractions on the suction surface of the blade than that on the pressure surface. The wear location predicted by the simulations agreed well with experimental observations. This study provides guidance on how to optimize slurry pump impeller designs to reduce the wear.

Influence of Blade Thickness on Solid–Liquid Two-Phase Flow and Impeller Wear in a Ceramic Centrifugal Slurry Pump

The impeller blades of ceramic slurry pumps are usually very thick for the purpose of prolonging the service life. In this paper, numerical simulations and wear test were conducted to investigate the influence of blade thickness on the solid–liquid two-phase flow and impeller wear in a ceramic centrifugal slurry pump. The wear test was conducted for CFD validation. The numerical results show that the incident angles of solid particles increase with increasing blade thickness, which results in larger wrap angles of the solid particle trajectories. The increasing wrap angles of the solid particle trajectories offset the region that the collisions between the blade pressure side and the solid particles side take place towards the impeller exit and lead to more impacts between the solid particles and the blade suction side. The numerical results are in good accordance with the wear pattern of the tested impellers, which demonstrates that the numerical method adopted in this paper is predictable in the abrasion of the impeller of a ceramic centrifugal slurry pump. The experimental results show that an increase in the blade thickness alleviates the abrasion of the leading edges and the pressure side of the impeller blades; however, it also aggravates the abrasion of the blade suction side and decreases the pump performance.

The Influence of Different Blade Outlet Angle and Wedge Groove on the Performance of the Double Suction Pump

This study aims to significantly improve the performance of the centrifugal pump by designing a wedge grooves on the outside of the impeller cover, and investigating the method for determining the blade outlet angle that plays important roles in the energy conversion. The solidliquid two-phase flow fields with the designed pump and an original pump were numerically simulated in the ANSYS-FLUENT. Compared with the original pump, reducing the blade outlet angle can effectively improve the sand-water wear on the blade surface and opening wedge grooves can slow down impeller ring wear. The head of the improved model pump decreases by about 1.5% and the efficiency increases by about 1.5%.

Wear Characteristics of Dense Fine Particles Solid‐Liquid Two‐Phase Fluid Centrifugal Pump with Open Impellers

The demand for a centrifugal pump with open impellers for conveying dense fine particles in solid‐liquid two‐phase flow has increased significantly in actual engineering. The wear of dense fine particles on the centrifugal pump is also exceedingly prominent, which affects the engineering efficiency and economic benefits. The two‐phase flow in the open centrifugal pump is three‐dimensional and unsteady; the movement of high‐volume concentration particles in the centrifugal pump and its mutual influence on the two‐phase flow, which results in the calculation of wear, are very intricate. To study the wear characteristics of the centrifugal pump with open impeller with high‐volume concentration particles more accurately, numerical simulation and experimental comparison are carried out for the impeller wear of dense fine particles transported by the centrifugal pump with open impellers. Considering the relationship between particles and walls, we used the Fluent 18.0 built‐in rebound function and wear model. The RNG k‐ε model and the DDPM model were adopted in the numerical simulation, and the numerical solution for centrifugal pump wear was performed under flow rate (9.6 m3·h−1, 12.8 m3·h−1, 16 m3·h−1, and 19.2 m3·h−1), different particle sizes (0.048 mm, 0.106 mm, 0.15 mm, 0.27 mm, and 0.425 mm), and different particle volume concentrations (10%, 15%, 20%, 25%, and 30%), respectively. By comparing the serious wear positions of the impeller, the experimental results correspond well with the numerical simulation, which can be used to predict and study the wear characteristics of the impeller. The results show that the most serious area of blade wear is the middle part of the pressure surface, followed by the middle part of the upper part of the blade. The wear of the impeller is greatly affected by relevant parameters, such as pump flow rate, particle diameter, and particle volume concentration. These results can provide some basis for the wear‐resistant design of dense fine particle impeller.

Martensitic wear resistant steels alloyed with titanium

The traditional approach to improving the abrasion wear resistance of martensitic steels is to increase their hardness via high carbon levels. However: (i) a higher hardness is usually accompanied by a lower toughness, negatively affecting the impact wear resistance, and (ii) increased carbon concentrations reduce weldability and complicate thermal cutting. This work explored microalloying with Ti as a method to simultaneously increase hardness and toughness via a concurrent precipitation of coarse TiMoVCN, fine TiC and fine Fe3C particles. Five plate steels containing <0.4C, <0.8Ti, Mn, Si, Cr, Mo and V (wt. %) were melted, cast, hot forged and heat treated to replicate an industrial processing technology. Dependences of mechanical properties on steel composition were studied using hardness, tensile, Charpy impact, pin-on-drum wear (two-body abrasion wear conditions) and impeller wear (two-body impact wear conditions) testing. Microstructure characterisation was carried out using optical and scanning electron microscopy. With an increase in Ti/C ratio: hardness and strength showed a dependence with a maximum; toughness a dependence with a minimum; and wear resistance (both abrasion and impact) a dependence with a maximum. The maximum wear resistance (at Ti/C = 0.314) did not correspond to either hardness (at Ti/C = 0.905) or toughness (at Ti/C = 0.018) maximum, but matched the highest tensile strength. The fracture development at the particle-matrix interface was found to govern the wear mechanism in the studied steels.

Leakage and Force Coefficients of a Grooved Wet (Bubbly Liquid) Seal for Multiphase Pumps and Comparisons With Prior Test Results for a Three Wave Seal

Abstract In the subsea oil and gas industry, multiphase pumps and wet gas compressors are engineered choices saving transportation and separation facility costs. In these machines, seals handling multiple phase components must be able to operate without affecting the system efficiency and its dynamic stability. This paper, extending prior work conducted with uniform clearance and wavy surface annular seals, presents measurements of leakage and dynamic force coefficients in a grooved seal whose dimensions are scaled from an impeller wear ring seal in a boiler feed pump. The 14-grooves seal has diameter D = 127 mm, length L = 0.34 D, and clearance c = 0.211 mm; each groove has shallow depth dg ∼2.6 c and length Lg ∼ 3.4% L. At a shaft speed of 3.5 krpm (surface speed = 23.3 m/s), a mixture of air in ISO VG 10 oil with inlet gas volume fraction (GVF) ranging from 0 (just oil) to 0.7 (mostly air) lubricates the seal. The pressure ratio (inlet/exit) is 2.9. The flow is laminar since the liquid is viscous and the pressure drop is low. The measured mixture mass flow decreases continuously with an increase in inlet GVF. The seal stiffnesses (direct K and cross coupled k), added mass (M), and direct damping (C) coefficients are constant when the supplied mixture is low in gas content, GVF ≤ 0.1. As the gas content increases, 0.2 ≤ GVF ≤ 0.5, the seal direct dynamic stiffness becomes nil with an increase in excitation frequency, whereas k and C reduce steadily with GVF. In general, for GVF ≤ 0.5, the direct damping is invariant with frequency; variations appearing for GVF = 0.7. Compared against a three wave annular seal, the grooved seal offers much lower force coefficients, in particular the viscous damping. Thus, for laminar flow operation (heavy oil) with a low pressure drop as in a wear ring seal, a three wave seal is recommended as it also offers a significant centering stiffness.

Chaotic vibration reduction of vertically suspended centrifugal pumps by the effect of the mechanical design parameter on hydraulic forces

The chaotic vibration generated by slender rotor–stator contact in vertically suspended centrifugal pumps shows itself in wear and fatigue failure of shafts, bearings, wear rings, seals and impellers. In common design methods of rotary equipment, for validating designed products, virtual representations in Computer Aided Design tools are imported to simulation tools (e.g. ANSYS software) on the last step of the design process. In this research, the ability of a non-linear finite element model is examined to support decision-making, synthesis and interaction of design choices during earlier stages of design process. So, the back wear ring diameter as the adjustable mechanical design parameter is used to reduce chaotic behavior of the pump rotor without any difficulty in manufacturing or problematic effect on the major hydraulic properties. The non-linear finite element model of the rotor is discretized into an appropriate number of Timoshenko beam elements. The major non-linear terms, the geometric stiffening effect, and the gyroscopic effect are considered. Rotor–stator contact, considering the rotor–stator clearance and the rotor–stator friction coefficient are taken into account. The full-order equations of motion are obtained using Lagrangian approach and the finite element method, and then are integrated into a computational plan. This study presents an allowable domain of the mechanical design parameter in which chaotic vibrations of the slender rotor can be reduced effectively. Furthermore, this research shows a basic method in which some design stages can be run in parallel rather than in series can be used to reduce redesigning and optimization times.

Development and Characterization of a Non-Intrusive Sensor to Measure Wear in Centrifugal Pumps

A magnetic sensor is designed and fabricated that allows for impeller blade wear measurement while a centrifugal pump is in operation. The sensor can be installed on existing pumps and does not require structural modification. Over time, as the pump impeller erodes, the gap between the impeller and the pump side plate increases from an unworn width of 0.65 to 2.50 mm, the maximum allowable wear on the testbed pump used for experimental validation. The extent of the impeller wear is determined by measuring over time the change in the reluctance of a magnetic circuit passing through the eroding area. The sensor flux guide mechanism has a relative magnetic permeability of 10000. Flux through the circuit is driven by an inductive coil excited with a 1.0 V AC voltage signal at 70 Hz. As wear occurs, the impeller gap grows and the total reluctance of the magnetic circuit increases, which causes the peak inductance of the coil to drop. Trial data is collected at sampling frequencies up to 500 kHz and then assessed in the frequency domain using fast Fourier transform (FFT). The amplitude of the FFT signal at the pump’s rotational frequency is then considered to estimate wear. Sampling data for 1 s at 500 kHz, the sensor demonstrates a maximum signal-to-noise ratio of 17.8 dB with an average sensitivity of 0.022 mV/mm and a resolution of 0.38 mm.

Development and Evaluation of a Method of Reducing Erosion Wear of Impellers

Results of numerical simulation of the process of heating of the nozzle blade of a steam turbine in order to reduce the concentration and sizes of droplets that can induce erosion are presented. Results of numerical simulation of the motion of polydisperse flow of moisture accompanied by the formation of a film on the surface of the blade are compared with experimental data. A technique of calculating heating of nozzle blades as an effective method of combatting erosion is developed. Results that show that the efficiency of heating is significantly higher than intrachannel separation are obtained.

Dynamic analysis of slender rotor of vertically suspended centrifugal pumps due to various hydraulic design factors

If a rotor is excited at one of its natural frequencies, a resonance occurs. The resonance can lead to large amplitude oscillations and subsequently failures. Field experience proves that the excessive vibration of the rotor of centrifugal pumps shows itself in wear and fatigue failure of shafts, bearings, wear rings, seals and impellers. So, modal analysis of a pump rotor is of great concern to researchers, international standard organizations and industries. In this research, dynamic behavior of a nonlinear finite element model of slender rotor of vertically suspended centrifugal pumps is studied. The dynamic model of the rotor is discretized into an appropriate number of three-dimensional Timoshenko beam elements. In addition to the main nonlinear terms and particularly the geometric stiffening effect, the gyroscopic effect has been also taken into account. The full-order equations of the motion, which are obtained by the Lagrangian approach and the finite element method, are integrated into a computational plan. The ability of the recent nonlinear dynamic model, which is intended to furnish a basic model for further development of a more comprehensive model, is examined to track the coupling between different types of vibrations. The comprehensive modal analysis of the rotor due to various hydraulic design factors is presented.

Pilot study for the reliability evaluation of double suction volute pump

In this paper, the study of test methods for the reliable assessment of the amount of suction pumps which bees root fluid is sucked into both around the impeller. Bee root amount suction pump is usually used for the purpose ofdischarging a large flow rate, such as water supply plant equipment and buildings. Centrifugal pumps are currently in production in the country is the trend in the exchange according to Chapter mode changes to improve the level of technology leaks due to wear of the mechanical seal from the existing impeller wear. When the mode is changed to give chapter and developed appropriate test method for evaluating the reliability of centrifugal pumps life testing time because the calculation method differs with these failure modes.

Internal Flow Analysis of Seawater Cooling Pump using CFD

This research focuses on simulation and visualization of flow field characteristics inside a centrifugal pump. The 3D numerical analysis was carried out by using a numerical CFD tool, addressing a Reynolds Average Navier-Stock code with a standard k-Ɛ two-equation turbulence model. The simulation accounts for friction head loss due to rough walls at suction, impeller, discharge areas and volumetric head loss at impeller wear ring. A comparison of performance curves between simulation and experimentation is included, and it reveals a same trend of those results with a small difference of maximum 5 %. At best efficiency point, velocity vectors are smooth but it changes significantly under off-design point, a strong recirculation appears at the outlet of impeller passages near tongue area. A relatively uniform preassure distribution was observed around the impeller in despite of the tongue. Within the volute, because of its geometry, spiral vortexes formed, proving that the flow field in this region was relatively turbulent and unsteady.