Operation Of Centrifugal Pumps Research Articles

Experimental study of a pump in turbine mode, energy characteristics, selection methods and operation in a system

This paper reveals the issues related to the operation of a standard centrifugal pump in turbine mode. The features related to predicting the parameters of the pump, when operating both as a turbine and operating in a system, are considered. An experimental study of a centrifugal pump with a specific frequency NSp=34 is made. The characteristics of the machine in pump and turbine mode are determined. A comparison is made with related models for pump selection for operation in turbine mode. The deviations in the obtained results were evaluated theoretically and experimentally. The obtained results are compared with models for predicting machine parameters in turbine mode, and there are considered different cases of operation of the particular machine in a system.

Investigation on stall characteristics of marine centrifugal pump considering transition effect

Marine centrifugal pumps are used as boiler feed pumps and condensate pumps in ocean engineering. Centrifugal pump stall is a transient flow structure, which may disrupt the uniformity of the flow field and have destructive effects on the pump. Centrifugal pump simulations are usually limited to the application of turbulence, ignoring the transition characteristics of the blade boundary layer. Aiming at the transient characteristics of centrifugal pump stall vortex, the calculation strategy considering the transition effect is established. This strategy determines the near-wall mesh based on the transition flow parameters and is applied to calculate the centrifugal pump stall for the first time. It is found that at deep stall conditions, the number of stall cells calculated by the transition model increases, while the stall frequency decreases. The microscopic flow structure calculated by the transition model and its relationship with the hump of the centrifugal pump head is obtained. The laminar separation bubbles near the blade leading edge will increase as the flow rate decreases, causing an increase in the friction loss on the blade surface, which lead to a hump in the pump head characteristics. The dynamic mode decomposition (DMD) method is used to extract the characteristic frequencies and corresponding modes of the 0.2Qd condition. In the high-order mode of the stall flow field with transition, a low-pressure zone formed at the head of the blade has a tendency to fall off from the wall, which shows the high-order motion characteristics of the stall vortex. The results could guide centrifugal pump design and operation.

A Review of Pressure Fluctuations in Centrifugal Pumps without or with Clearance Flow

As crucial equipment in the industrial field, the stable operation of centrifugal pumps has drawn noteworthy attention. Relevant studies in the open literature have shown that intense pressure fluctuations have a major effect on the reliability and lifetime of centrifugal pumps. In the present paper, the pressure fluctuations in the centrifugal pumps are discussed in detail from different perspectives. The details of the studies are as follows. Firstly, the pressure fluctuation characteristics in centrifugal pumps are studied without considering clearance flow. Secondly, the pressure fluctuation property is investigated in detail for the pumps, with consideration for clearance flow. The pressure fluctuation characteristics in the wear ring, the pump-chamber clearance region, and the main stream region are studied, and the effect of clearance flow on the external performance of the pumps is analyzed. Thirdly, measures to reduce the pressure fluctuations and forces are summarized to improve the operational reliability of centrifugal pumps. Finally, conclusions and future research perspectives in the field of centrifugal pumps are presented. This review presents the research highlights and progress in the field of pressure fluctuations, which is beneficial to the stable operation of centrifugal pumps in engineering.

Study of the influence of foaming surfactants on the operation of a multistage centrifugal pump when pumping water-gas mixtures created by an ejector

When implementing the SWAG technology, the degree of stability of the water-gas mixture plays a key role. A many factors of various nature is known to the suppression of the coalescence of gas bubbles is facilitated. This article presents the results of studies of the effect of surfactants of various compositions and concentrations on the operation of a multistage centrifugal pump when pumping water-gas mixtures. The foaming agent disolvan 4411 is determined to the degree of negative influence of free gas on the characteristics of the pump is significantly reduced. The reagent Neftenol VVD provides operating parameters very close to the characteristics of the pump when using disolvan 4411. The concentration of Neftenol VVD, recommended for addition to the water-gas mixture, has been determined. The expediency of choosing this surfactant is also due to the fact that the use of this reagent improves the injection capacity of wells. Keywords: multistage centrifugal pump; ejector; water-gas mixture; foaming surfactants.

Investigation on Stall Characteristics of Centrifugal Pump with Guide Vanes

Stall usually occurs in the hump area of the head curve, which will block the channel and aggravate the pump vibration. For centrifugal pumps with guide vanes usually have a clocking effect, the stall characteristic at different clocking positions should be focused. In this paper, the flow field of the centrifugal pump under stall conditions is numerically simulated, and the rotor–stator interaction effects of the centrifugal pump under stall conditions are studied. The double-hump characteristic is found in the head curve by using SAS (Scale Adaptive Simulation) model. The hump area close to the optimal working condition is caused by hydraulic loss, while the hump area far away from the optimal working condition point is caused by the combined action of Euler’s head and hydraulic loss. The SAS model can accurately calculate the wall friction loss, thus predicting the double-hump phenomenon. The pressure fluctuation and head characteristics at different clocking positions under stall conditions are obtained. It is found that when the guide vanes outlet in line with the volute tongue, the corresponding head is the highest, and the pressure fluctuation is the lowest. The mechanism of the clocking effect in the centrifugal pump with guide vanes is obtained by simplifying the hydrofoil. It is found that when the downstream hydrofoil leading edge is always interfered with by the upstream hydrofoil wake, the wake with low energy mixes the boundary layer with low energy, which causes small-pressure pulsation. The results could be used for the operation of centrifugal pumps with guide vanes.

Numerical Analysis and Experimental Study of Unsteady Flow Characteristics in an Ultra-Low Specific Speed Centrifugal Pump

Low specific speed centrifugal pumps are widely used in urban water supply, agricultural irrigation, petrochemical and other fields due to their small flow rate and high head. Therefore, the study of unsteady flow characteristics plays a vital role in its safe and stable operation. In this paper, numerical simulation and experimental methods are used to explore the unsteady performance of the pump. The results show that the fluctuations of the external characteristic such as head, shaft power and energy loss are due to the periodic disturbance of the flow field of pump. But the transient performance of shaft power and head shows different changing trends due to different influencing factors. In this paper, the transient process of hydraulic performance is divided into three stages according to the causes and characteristics of hydraulic fluctuations. Most of the hydraulic losses occur inside the impeller, so the impeller flow field determines the level of time average hydraulic performance. Although the hydraulic loss of the spiral case is small, it is greatly affected by the rotor-stator interaction, which affects the strength of the hydraulic fluctuation. This study is of great significance to the mechanism of rotor-stator interaction and the stable operation of low specific speed centrifugal pumps.

Research of the effect of the properties of water-oil emulsions on the work of centrifugal electric pumps

In this article, the formation of highly mineralized water-oil emulsions in Uzbekistan, the complexity of their composition, and the effect of their physical and chemical properties on the operation of centrifugal electric pumps used for the extraction and transfer of this type of oil are described. As the period of use of wells increases, the degree of hydration of the well product also increases, which, in turn, complicates the work of centrifugal electric pumps.

Investigation on performance of a marine centrifugal pump with broken impeller

As an important auxiliary equipment for ships, the stable operation of centrifugal pumps has a significant impact on the safe operation of ships, so monitoring the operation of marine centrifugal pumps is particularly urgent. In this paper, a marine centrifugal pump is studied for four cases: the normal state, the initial stages of broken state, the intermediate stages of broken state, and the late stages of broken state. The Delayed Detached Eddy Simulation (DDES) with a nonlinear eddy viscosity model is used for the nonstationary calculation of the whole channel, aiming to study the performance of the centrifugal pump in the broken state. A comprehensive analysis of the hydrodynamic characteristics of the centrifugal pump, such as external characteristics, flow situation, pressure pulsation, and flow analysis based on the proper orthogonal decomposition (POD) method, was carried out. Taken together, these results suggest that as the number of broken blades increases, the corresponding head and efficiency gradually decrease. Blade loss mainly affects the uniformity and stability of the flow field, so that the centrifugal pump performance loss increases, which in turn causes the centrifugal pump head and efficiency to decline. It also leads to an increase in radial force during operation, which in turn causes an increase in the amplitude of pump vibration. The results of the study provide some references for the fault diagnosis of centrifugal pumps.

Research on the Relationship between Sediment Concentration and Centrifugal Pump Performance Parameters Based on CFD Mixture Model

To study the relationship between sediment concentration and the performance parameters of centrifugal pumps, Jiamakou water supply pumping station with total installed capacity of 30,880 kW was selected to analyze characteristics of the centrifugal pump in this paper. Based on a CFD mixture model, the effects of different sediment concentrations on the movement of solid–liquid two-phase flow and the performance parameters of the centrifugal pump were obtained. Then, fitting equations were established between performance parameters (head, flow rate, shaft power, and efficiency) of the centrifugal pump and sediment concentration at three working conditions (0.8 Q = 2 m3/s, Q = 2.5 m3/s, 1.2 Q = 3 m3/s) by the polynomial least-square method. Calculated values of fitting equations were compared with the measured values in centrifugal pump operation. The results show that, as the sediment concentration increases from 0.1% to 1%, the maximum volume fraction of sediment at blade outlet increased from 0.14% to 1.14%, and the maximum volume fraction of sediment at blade outlet increased from 0.7% to 2.29%. The turbulent kinetic energy inside the centrifugal pump increased from 8.74 m2/s2 to 10.78 m2/s2. The calculated values of fitting equation are in good agreement with the measured values in centrifugal pump operation, and the maximum errors of head, flow rate, and efficiency are 6.48%, 3.54%, and 2.87%, respectively. Therefore, the reliability of the fitting equations is verified. The research method can provide a reference for the calculation of performance parameters for centrifugal pumps in other water supply pumping stations with sediment-laden flow.

Numerical modeling and analysis of particle-fluid flow and wall erosion in centrifugal slurry pumps under different solid concentrations

Wall erosion is a critical problem encountered in operation and maintenance of centrifugal slurry pumps. This paper presents a numerical study of the particle-fluid flow and wall erosion of industrial pumps. This is done by the dense discrete phase model. The model is validated by comparing the simulated results with the experimental measurements of pump hydraulic performance and jet erosion. Then, the effects of feed solid concentration are quantified under fixed motor power. The numerical results show that with increasing solid concentration, the pump efficiency increases first to a maximum and then decreases. The volute casing suffers the most erosion, which is generally not much sensitive to solid concentration. This is not the case for pre swirl vane and frame plate, whose erosion rate increases rapidly at relatively high solid concentrations. The results suggest that the model can be used as a cost-effective tool for pump design and control. • The dense discrete phase model is applied to study centrifugal slurry pumps. • It focuses on the effects of solid concentration on flow and wall erosion. • Volute casing suffers most erosion but is much insensitive to solid concentration. • The erosion of pre swirl vane and frame plate is sensitive to solid concentration.

METHODOLOGICAL BASES FOR ASSESSING THE ENVIRONMENTAL IMPACT FROM THE INTRODUCTION OF A FREQUENCY-CONTROLLED ELECTRIC DRIVE AT PUMPING STATIONS OF WATER SUPPLY AND SEWERAGE SYSTEMS

A methodology for determining the environmental impact indicators from the operation of centrifugal pumps of water supply and distribution systems (WSDS) and wastewater pumping systems (WPS) is presented. The main dependences are given that allow calculating the cost of standard fuel for the process of pumping water and wastewater and the level of greenhouse gas emissions in CO2 equivalent. The dependences of determining the level of leaks due to the excess of the calculated pressure in the water distribution system are also given. Recommendations are given for the practical application of the methodology in the implementation of energy-saving and environmental measures at the pumping stations of the WSDS and WPS.

Dynamic evolution process of rotating stall vortex based on high-frequency PIV system in centrifugal impeller

Rotating stall is a kind of strong unstable flow phenomenon, which plays a decisive role in stable operation of centrifugal pumps. Limited by the performance of the experimental system, so far there are rare experimental studies on the rotating stall phenomenon in impeller, especially the initial generation and the evolution process of the rotating stall vortex. Based on the experimental bench with refractive index matching and the high-frequency PIV system, the continuous instantaneous velocity fields were visualized in a five-blade impeller. Two kinds of experimental measurement methods were utilized to observe the formation process and study the transmission mechanism of rotating stall vortex between impeller passages. Meanwhile, the Proper Orthogonal Decomposition method is used to smooth the instantaneous velocity field. The results show that the generation of the rotating stall in impeller is a transient process. The flow rate in each passage adjusted quickly when the impeller enters the stall stage, and then the stall vortex moved periodically along the impeller at a certain frequency. Two kinds of frequency characteristics of the stall vortex were clearly observed at stall conditions. The relationship between the evolution frequency of the stall vortex under different impeller speeds and flow rate is reasonably explained.

CALCULATION AND ANALYSIS OF OPERATING MODES AND ENERGY CONSUMPTION OF CENTRIFUGAL PUMPS WITH FREQUENCY-CONTROLLED ELECTRIC DRIVE IN WATER SUPPLY SYSTEMS

The article discusses examples of calculating the operating modes of a centrifugal pump of a water supply and distribution system using a newly developed methodology by the authors. The main points of calculation and analysis of technological, energy and environmental parameters characterizing the operation of centrifugal pumps of water supply and distribution systems are given.

Modeling of the Blade Leading-Edge Pressure Drop of Centrifugal Impeller Based on Machine-Learning

Blade leading-edge pressure drop is an important parameter that strongly influences the safe and stable operation of centrifugal pump. It is sensitive to blade leading-edge geometry. To understand the inlet flow state of centrifugal pump, it is necessary to evaluate the location and the minimum value of blade leading-edge pressure drop. However, the operation condition is complex. A large amount of experiments and numerical simulations should be conducted for a fully understanding of the local pressure field. With the development of artificial intelligence, machine learning can be used for accelerating the evaluations with potential laws of fluid mechanism. Therefore, neural network is used in this case to fit the solution space of condition, leading-edge geometry and local pressure drop. The influence of different factors can be well analyzed. The conditions which is not directly tested will be predicted by well-trained neural network. With the increasing of the leading-edge elliptic ratio of the blade inlet, the minimum pressure position of the blade moves from the impeller hub to the impeller shroud. This study provides a preliminary study and a good reference of the evaluation of blade inlet leading edge flow state in the future researches.

INFLUENCE OF GAS BUBBLES ON THE OPERATION OF A CENTRIFUGAL PUMP

Analysis shows that many liquids contain soluble gas in them. Such fluids have low viscosity and density. However, when pumping liquids, a number of problems arise, one of which is the appearance of bubbles in the mixture. Such liquids with gas do not obey the law of homogeneous liquid and gas. Therefore, in recent years, special attention has been paid to the hydromechanics of two-phase systems, such as oil-gas, water-steam, etc. the appearance of gas bubbles also affects the operation of centrifugal pumps, which manifests itself during pumping. Keywords: centrifugal pump, gas-liquid system, gas bubbles, torque on the shaft, power, mass of liquid.

Research on stator current characteristics of centrifugal pumps under different mechanical seal failures

Mechanical seal failure has a great negative impact on the operation of a centrifugal pump system. A method to analyze the stator current characteristics of the motor in a centrifugal pump system is proposed to monitor the internal flow of the centrifugal pump and to identify the failure status of the mechanical seal. Experiments were conducted under different mechanical seal states. Based on sensorless technology, the stator current signal of the motor is collected, processed by windowing function, anti-aliasing filter, singular value decomposition, Hilbert–Huang transform, and the marginal spectrum of correlation quantity is drawn. The results show that according to the external characteristic curve of the centrifugal pump, after the failure of the mechanical seal, the head and efficiency of the centrifugal pump decrease, and the head is greatly affected by the degree of failure, while the degree of mechanical seal failure has little effect on the shaft power of the centrifugal pump; the centrifugal pump has good operation stability under design conditions or near slightly large flow; the stability of centrifugal pump operation decreases with the aggravation of mechanical seal failure; the corresponding maximum amplitude in the marginal spectrum can be used as an index to diagnose the damage degree of the mechanical seal.

Convolution Diagnosis Model of Centrifugal Pump Based on Fractal Dimension

Nowadays, more and more centrifugal pumps are used in the industrial domain. Normal operation of centrifugal pumps is also the key to maintain stable operation of production and process. So it is very important to monitor the operation status of centrifugal pumps real time on-line. In order to diagnose the fault of centrifugal pumps, we proposed a Convolutional Neural Network (CNN) fault diagnosis model, based on Fractal Dimension (FD) features. Firstly, we collected the vibration signal of centrifugal pumps and preprocessed them. Then we used the Empirical Mode Decomposition (EMD) to calculate the fractal dimension and the fractal matrix of the signal. Finally, we constructed the CNN model to diagnose and classify the fault of centrifugal pumps. The experiment shows that the accuracy of the proposed model can reach over 90%.

DEVELOPMENT OF OİL PRODUCTİON IMPROVEMENT TECHNOLOGY

It is important to conduct research without storing wells. Prior to this study, the wells will be shut down to explore the wells and additional work will be done for the survey. The research work itself took 15-20 days, using this research to determine the necessary parameters for the joint operation of the reservoir in a short time. In solving engineering problems, the force often applied to the system is to determine its reaction. In such cases, the correct answer to the question can be obtained on the basis of theoretical calculations. However, this is not always possible, and in some cases, instead of a mathematical model of the object under study, research is conducted to find a similar one. An electrical circuit can be thought of as a similar model of the mechanical oscillations of a solid. Therefore, by studying the motion of an electric charge in an electric circuit, it is possible to apply the oscillations of a mechanical system and the distribution of pressure in a porous medium by studying the distribution of heat in an object. If the final results of the two events are similar, then the modeling can be performed. The formation is considered as a working machine to determine the similarity of the drainage zone of the oil and gas well. In this case, the fluid system is lifted by lifting pipes to a certain height with formation pressure and the production of the well is ensured. As a result of the research, it was found that the mode of operation of the drainage zones of the strata in the wells is close to the mode of operation of centrifugal electric pumps. Keywords: debit, formation pressure, gas flow rate, drainage zone of the well, hydraulic characteristics of discharge line, bottomhole pressure, stress on discharge line of the pump.

Analysis of causes of failure of the electric centrifugal pump elements by the methods of automated diagnostics

The article discusses the issues of assessing the technical condition of electric centrifugal pumps (ECP) by the methods of automated diagnostics. The factors influencing the ECP and causes of failures of the electric centrifugal pump (ECP) and the submersible electric motor (SEM) are analyzed. The results of ECP failure identifiaton using the measuring systems are presented. Recommendations on the operation of electric centrifugal pumps are provided.

Numerical Simulation and Computational Flow Characterization Analyses of Centrifugal Pump Operating as Turbine

Using a pump in reverse mode as a hydraulic turbine remains an alternative for hydropower generation in meeting energy needs, especially for the provision of electricity to remote and rural settlements. The primary challenge with small hydroelectric systems is attributed to the high price of smaller size hydraulic turbines. A specific commercial pump model, with a flow rate of 12.5 m3/h, head 32 m, pressure side diameter of 50 mm, impeller out, and inlet diameters of 160 mm and 6 mm, respectively, was chosen for this research. This research aimed to investigate a pump’s flow characteristics as a turbine to help select a suitable pump to be used as a turbine for micro- or small hydropower construction. Numerical methodologies have been adopted to contribute to the thoughtful knowledge of pressure and velocity distribution in the pump turbine performance. In this study, the unsteady flow relations amongst the rotating impeller and stationary volute of the centrifugal pump made up four blades and four splitters. Intermittent simulation results of pressure and velocity flow characteristics were studied considering diverse impeller suction angles. The study was conducted by considering a wide range of rotational speeds starting from 750 rpm to 3250 rpm. From the results, it was found that PAT operation was improved when operated at low speeds compared to high-speed operation. Thus, speeds between 1500 rpm and 2000 rpm were suitable for PAT performance. This research helps to realize the unsteady flow physiognomies, which provide information for future research on PAT. This study makes useful facts available which could be helpful for the pump turbine development. Future studies should focus on cost analysis and emission generation in energy generation.