Liquid Ring Vacuum Pump Research Articles

A Comprehensive Review of Liquid Ring Vacuum Pumps and Compressors for Improving Global Efficiency and Energy Saving

Liquid ring vacuum pumps and compressors are mechanical positive displacement turbomachines that can operate in the mode of both vacuum compressor and vacuum pump. They are widely used in the fields of filtration, cryogenic, reaction, gas injection, condensation, evaporation, and convective drying. Despite their low performance, they have many advantages such as low costs, simplicity, reliability, improve suction characteristics, and in many cases, can provide a more efficient option. Improving efficiency is the key to decrease energy consumption and costs. The article analyzed and evaluated the previous investigations regarding these machines with a focus on challenges of improving efficiency, advances in numerical simulation, and experiments to afford beneficial insight on future research and next steps. The study revealed that the thermal interaction and the cavitation phenomenon are among the most important problems that require further research.

АДДИТИВНЫЕ ТЕХНОЛОГИИ ПРОИЗВОДСТВА ДЕТАЛЕЙ ЖИДКОСТНОКОЛЬЦЕВОГО ВАКУУМНОГО НАСОСА ДЛЯ ПРОЦЕССОВ АПК

. The tasks of prototyping using 3D printing are relevant for the needs of the agro-industrial complex, where constant modernization of existing equipment and the development of new designs that increase productivity are required. The printing of structural elements of a liquid ring vacuum pump, which is used in the processing of agricultural raw materials, is considered. Prototypes of structural elements of a single-stage liquid ring vacuum pump were manufactured on a Flying bear ghost 5 3D printer (Fig. 1) using FDM technology.The most optimal set of printing parameters was determined by the method of layer-by-layer deposition modeling. The selected modes provide the required quality indicators of the liquid ring vacuum pump prototype. The following parameters are considered: layer height, extruder nozzle and desktop temperatures, airflow during printing, speed, infill percentage and the need for supports. The analysis of the influence of each of the parameters on the characteristics of the finished product was carried out. It has been established that in order to obtain these structural elements without serious defects with a minimum consumption of material and the shortest printing time, it is necessary: the height of each layer is 0.2 mm; extruder nozzle temperature 230 ºС; desktop temperature 100ºС; print speed 60 mm/s; the percentage of filling the model is 25%. Also, for the best quality of the prototypes, constant airflow was used and supports were used in places where the model has significant protrusions. The manufactured prototypes allow evaluating the design features of the developed liquid ring vacuum pump and conducting simple tests for its performance in order to further eliminate the identified shortcomings of the prefabricated structure.

АНАЛИЗ РАСЧЁТА ПРИВОДА КОМБИНИРОВАННОЙ КОНСТРУКЦИИ ОДНОСТУПЕНЧАТОГО ЖИДКОСТНОКОЛЬЦЕВОГО ВАКУУМНОГО НАСОСА

The use of vacuum technologies and equipment in the processing of agricultural products can significantly reduce the loss of biologically active substances and functional components in the final product. Liquid ring vacuum pumps (LHVN) are considered in the work. A significant disadvantage of the LHVN is its low efficiency (about 50%), which is due to hydraulic losses due to friction of the liquid against the stationary pump casing and excessive power consumption for compressing the gas phase. A new design of a combined LHVN with a kinematic lock and an adjustable discharge window (LHVN KM) is proposed. The design allows to reduce the power consumption for the friction of the working fluid against the body; in the initial modes of operation - to minimize over compression and overflow of the gas phase from the injection area to the suction area; at limiting operating modes - to ensure the displacement of the gas phase from the working cavity and eliminate the effect of "locking", accompanied by destabilization of the working process. A standard size range of LHVN KM for various technological processes is presented. For LHVN KM of especially high speed of action, it is proposed to carry out the working process by rotating the body with blades through the designed drive. The scheme and methodology for calculating the drive on the basis of GOSTs and known methods for calculating gearing are described. In order to reduce the weight and size parameters of the LHVN KM, it is proposed to manufacture drive and pump parts from polymeric materials with subsequent hardening by a magnetothermal method.

УПРОЧНЕНИЕ МЕТАЛИЗАЦИЕЙ ПОЛИМЕРНЫХ ДЕТАЛЕЙ МАШИН И МЕХАНИЗМОВ АПК, ПОЛУЧЕННЫХ ПОСРЕДСТВОМ АДДИТИВНЫХ ТЕХНОЛОГИХ

The active introduction of additive technologies in many industries, including agriculture, determines the relevance of studying the properties of materials used in printing and the characteristics of the resulting products. Polymeric materials are widely used in 3D printing, which can be used to create new composites with the required parameters. One of the approaches to significantly improve the properties of parts made of polymers obtained using 3D printing is their metallization. The article proposes a technology for surface hardening of parts made of thermoplastic polymer materials. This technology is based on combining the action of an external heat flux, which is directed to the hardened surface, and a magnetic field, acting from the opposite surface of the part. Under the influence of magnetic and thermal fields, diffusion of metal powder particles into the polymer surface occurs. In particular, the hardening of the impeller blade of a liquid ring vacuum pump made of ABS plastic by means of three-dimensional printing using FDM technology is considered. The characteristics of the used thermoplastic polymer, which affect the regime parameters of the printing process and subsequent hardening, are considered. The developed installation is described, by means of which magnetothermal reinforcement is carried out. The following surface hardening parameters are possible: molding pressure 2 MPa; preheating the mold to 160-180℃ (approximately 20℃ lower than the melting point of ABS plastic); exposure at the specified temperature and pressure for no more than 2 minutes, followed by cooling in air. Nickel powder with a particle size of 40 μm was chosen as a ferromagnet for hardening. In the future, it is possible to conduct research on the introduction of metal powder into the product during the printing process.

ОБОСНОВАНИЕ ПАРАМЕТРОВ ВАКУУМ-ОТКАЧНЫХ СРЕДСТВ С ПУЛЬСИРУЮЩИМ АКТИВНЫМ ПОТОКОМ

Vacuum pumping devices designed for dosing, mixing, transporting and distributing feed; milking cows; milk processing and other technological processes in agriculture are among the main components of the technological processes of animal husbandry. In order to improve the technical characteristics of vacuum pumping devices, widely used in all industries, it is proposed to use a pulsating jet apparatus installed on the suction port of a liquid ring vacuum pump. To characterize a stationary flow, the reduced velocity and the Reynolds number are usually used, and in the case of a pulsating flow, the relative frequency and relative amplitude of the pulsations are added to them, which are necessary to determine the design and technological parameters. One of the main design parameters of the operation of a jet vacuum pumping device is the ejection coefficient, the increase of which is achieved by deliberately violating the stationary mode of material flow by adding a pulsating device. The object of experimental research was a jet apparatus with a pulsating active flow. As an interrupting mechanism for an ejector with a pulsating active flow, it is advisable to use a ball-shaped valve made of various materials, which, due to the pressure drop and a return spring, can pulsate at a frequency of 
 90 ... 100 beats/min. During the experiments, the change in the supply of a water-ring vacuum pump with a pulsating jet apparatus was determined depending on the materials of the ball-type valve (steel, rubber and textolite), the suction pressure (1; 5; 10; 20; 30; 40; 50; 60 kPa), valve pulsation frequency (85; 100; 115; 130 beats/min) and ejector inlet pressure (20; 30; 50; 60 kPa). The best result is noted when using a valve in the form of a ball made of steel. In this variant, the supply of a water ring vacuum pump with a pulsating jet apparatus is increased to 14.5 m3/min, and the maximum supply is provided at a pulsation frequency of 90...100 beats/min

The axial tip clearance leakage analysis of the winglet and composite blade tip for the liquid-ring vacuum pump

Axial tip clearance leakage of liquid-ring vacuum pump has an important impact on it's hydraulic performance. In order to suppress the axial tip clearance leakage flow and improve the hydraulic performance, the winglet and composite blade tip were introduced to the axial tip clearance of the 2BEA-203 liquid-ring vacuum pump blade. The mechanisms of the winglet and composite blade tip on the clearance leakage flow field were analyzed by numerical simulation method. The analysis results show that the winglet extends the flow channel of axial clearance, and reduces the pressure difference between the two sides of the clearance, thus suppressing the leakage flow. Therefore, the winglet impeller can improve the pump vacuum and efficiency to a certain extent. However, the suction surface winglet will generate the wing corner vortex under the winglet, resulting in additional losses and making the improvement of its hydraulic performance lower than that of the pressure surface winglet. For the composite blade tip, the jet hole directly leads the high-pressure fluid from the pressure surface to the clearance, which weakens the effect of the winglet. So, the suppression effect of the composite blade tip is lower than that of the winglet. Although the winglet reduces the mixing loss of the jet, the suppression effect of the winglet is better than that of the jet. Therefore, as the mechanism of the winglet is different from that of the tip jet, the suppression effect of the composite blade tip is lower than that of the winglet, and greater than that of the tip jet.

Experimental study on the flow and heat transfer behavior of polymer solutions in the closed liquid ring vacuum pump system

The closed liquid ring vacuum pump system, which mainly includes the liquid ring vacuum pump and the heat exchanger, is widely used for gas pumping in various industries. In this paper, the energy saving effect in the liquid ring vacuum pump and the flow and heat transfer behavior in the shell-and-tube heat exchanger are investigated for aqueous solutions of rigid xanthan gum (XG) and flexible Polyacrylamide (PAM), and the effects of the concentration, Reynolds number, polymer conformation and flow geometry on the flow behavior of polymer solutions are studied. Results show that, despite the significant differences in molecular conformation and rheological properties between XG and PAM, the similar energy saving rate, about 1.5 ∼ 17.5%, is obtained in the liquid ring vacuum pump. However, in the shell-and-tube heat exchanger, XG solutions exhibit the more obvious pressure drop enhancement and heat transfer reduction than that of PAM solutions for the same concentration. Furthermore, due to the polymer shear degradation, the shaft power in the liquid ring vacuum pump decreases first and then stabilizes, conversely, the flow resistance decreases and the flow rate increases in the heat exchanger. The great difference in the flow condition between the intense rotating gas–liquid two-phase flow field and the gentle liquid pipe flow causes the different flow behavior for XG and PAM solutions.

Mini-Refinery Vacuum Unit: Functional Analysis and Improvement of Vacuum Overhead System

The purpose of this study was to analyze the functioning of the vacuum distillation unit of a mini-refinery and to develop recommendations for improving the vacuum overhead system with the aim to reduce the cost of creating and maintaining a vacuum in the fuel oil separation column. A calculation model of the vacuum unit was developed in the Unisim Design R451 software package, which was identified by comparing the calculated data with the data from an industrial study for two operating modes of the installation. Replacing the existing steam-ejector pump with a liquid-ring vacuum pump was proposed. A numerical experiment was carried out on the developed model, the purpose of which was to determine the “bottlenecks” of the scheme. The peculiarity of the experiment was that the vacuum column and the vacuum overhead system were considered as a single whole. As a result, it was determined that the “bottleneck” is the condenser, which was proposed to be replaced. During the technical and economic analysis, two possible vacuum overhead system schemes were considered; according to the results, it was determined that the vacuum overhead system scheme based on a liquid-ring vacuum pump will help reduce operating costs by 78%.

Design of Liquid-Ring Vacuum Pump with Adjustable Degree of Internal Compression

Design of Liquid-Ring Vacuum Pump with Adjustable Degree of Internal Compression

Возможности применения жидкостно-кольцевого вакуумного насоса с автоматическим регулируемым нагнетательным окном при измельчении виноградных семян и выжимок

Для повышения сохранения биологически активных веществ, уменьшения энергопотребления в процессе измельчения и получения порошка заданной степени помола из виноградных выжимок и семян предлагается использование установки двухступенчатой дисково-шаровой вакуумной мельницы. Предложенная конструкция двухступенчатой мельницы оказывает влияние на безопасность работы (исключаются взрывы) и экологичность (не создает запыленности окружающей среды). В конструкции разработанной установки важным объектом является вакуумный насос. Приведены устройство и основные принципы работы классического одноступенчатого водокольцевого вакуумного насоса производства ОАО «БЕСКОМ» и жидкостно-кольцевого вакуумного насоса с возможностью автоматического регулирования размеров нагнетательного окна, разработанного в ФГБОУ ВО «ТГТУ» на кафедре «МИГ». Показаны основные преимущества предлагаемого насоса по сравнению с классическим вариантом. На основе испытаний был проведен сравнительный анализ разработанного жидкостно-кольцевого вакуумного насоса с автоматическим регулируемым размером нагнетательного окна и классического вакуумного насоса равной быстроты действия, результаты которого продемонстрировали существенную эффективность использования первой машины. Установлено, что затраты удельной мощности в процессе транспортирования растительных порошков на 20-25% ниже при равной быстроте действия. Экономический расчет демонстрирует эффективность применения новой конструкции разработанного вакуумного насоса в технологическом процессе тонкого измельчения сухих растительных продуктов за счет вакуумного отвода заданной фракции помола. Поэтому разработанный насос рекомендуется использовать для измельчения сухих сыпучих растительных продуктов на крупных перерабатывающих предприятиях агропромышленного комплекса, пищевой, фармацевтической и парфюмерной отраслях промышленности. To increase the preservation of biologically active substances, reduce energy consumption in the grinding process and obtain a powder of a given degree of grinding from grape pomace and seeds, it is proposed to use a two-stage disk-ball vacuum mill. The proposed design of a two-stage mill affects the safety of work (excluding explosions) and environmental friendliness (does not create a dusty environment). An important object in the design of the developed installation is the vacuum pump. The device and basic principles of operation of a classic single-stage liquid ring vacuum pump manufactured by JSC "BESCOM" and a liquid ring vacuum pump with the ability to automatically adjust the size of the discharge window, developed at the TSTU Department of MIG are presented. The main advantages of the proposed pump in comparison with the classic version are shown.Based on the tests, a comparative analysis of the developed liquid ring vacuum pump with an automatically adjustable discharge window size and a classical vacuum pump of equal action speed was carried out, the results of which demonstrated the significant efficiency of using the first machine. It has been established that the specific power consumption in the process of transporting plant powders is 20-25% lower with the same speed of action. An economic calculation demonstrates the effectiveness of using a new design of the developed vacuum pump in the technological process of fine grinding of dry plant products due to the vacuum removal of a given grinding fraction. Therefore, the developed pump is recommended to be used for grinding dry bulk plant products at large processing enterprises of the agro-industrial complex, food, pharmaceutical and perfumery industries.

Liquid Ring Vacuum Pumps for Heat and Mass Transfer Processes

The paper examines the calculation of a liquid ring vacuum pump, using the example of the drying process of various materials. It was found that for two-stage convective vacuum-impulse drying it is economically efficient to use a two-stage liquid ring vacuum pump with the ability to turn off the second stage. A method for calculating the specific power of one-stage and two-stage liquid ring vacuum pumps, taking into account heat and mass transfer and thermal processes that occur during operation is proposed.

Experimental study of the characteristics of a liquid ring vacuum pump

Experimental study of the characteristics of a liquid ring vacuum pump

Modeling and energy analysis of a solar thermal vacuum membrane distillation coupled with a liquid ring vacuum pump

In this paper, a study of the energy performance of a solar powered vacuum membrane distillation coupled with liquid ring vacuum pump was investigated through various energy evaluation criteria. This analysis was investigated for the twelve months of the year. The results showed that the average daily production varied over the months from 598 to 217 kg/day. The average specific energy consumption, the average gained output ratio and the average energy efficiency were between 671 and 699 kWh/m3, 0.93–1.01 and 56.2–59.3% respectively. The maximum productivity and the best energy performance were that of June which is the month corresponding to the most important solar radiation. In addition, it was observed that vacuum liquid ring pump is characterized by a lower electrical energy consumption, which varies during the year between 4.2 and 7.47 kWh/m3. Besides, the effect of the vacuum level applied and liquid ring temperature on the energy performance was examined. Obviously, the results reveal that while increasing the vacuum, the specific energy consumption decreases. Moreover, it has been demonstrated that using an operating liquid at reduced temperatures reduces the flow rate required to ensure total condensation and decreases energy loss and specific energy consumption.

Coupled Simulation of a Vacuum Creation System and a Rectification Column Block

The purpose of this study was the coupling simulation of the vacuum block of the ethanolamine mixture separation unit to determine the optimal layout of the vacuum creation system. For this, a computational model of the vacuum unit, which was identified by comparing the computational data with the data of an industrial study of vacuum rectification columns, was synthesized in the Unisim Design R461 software package. To determine the required load on the vacuum system, a numerical experiment was carried out, during which it was discovered that the load on the system would be 9600 m3/h. It was proposed to replace individual column vacuum pumps with a single vacuum-generating system (VGS) based on a liquid ring vacuum pump (LRVP). When defining the layout, two possible schemes were considered, the models of which were created in Unisim Design R461. The system layout was determined by matching the characteristics of the system elements with the characteristics of the vacuum columns. A technical and economic comparison of the proposed solutions was carried out and the payback period for capital costs was calculated, which for Scheme 1 was 4.14 years, and for Scheme 2–3.59 years.

ADJUSTMENT OF REAL GAS EQUATIONS TO CALCULATION OF GAS JET PUMPS

When choosing the suitable type of gas equipment and further calculating its performance characteristics, equations based on the ideal gas law are used most widely. Equations for imperfect gas are less common in practice due to the fact that the calculations and the application in practice are more complex. This paper revisits some imperfect gas equations and gives recommendations on how to apply them based on an example of jet pump calculation. The paper illustrates how the calculation results for perfect and imperfect gas vary more as the pressure rises.One of the main outcomes of the study is the ability to take account of the extra losses in the jet pump caused by the nature of real gas. This will make it more simple to commence gas equipment and will lead to more accurately predicted performance characteristics for certain conditions of operation, which, in turn, allows for a higher efficiency of the commenced gas jet pumps. Keywords: imperfect gas, real gas, isentropic flow equations, jet pump

Перекачивание жидкости с использованием водокольцевого вакуумного насоса

The paper examines modelling of the pumping stages when using liquid-ring pumps, for example, in power plants and technological devices. It is important to determine the characteristics of various processes involved in liquid pumping using vacuum because the accuracy of predicting how objects move in such flows cannot be improved without solving the problems related to the calculation of hydraulic and power characteristics of the pumping unit in the network. Cubic spline functions were used as approximating functions when calculating the performance characteristics of a liquid-ring vacuum pump. The dynamics of changes in the pressure in the working vessel during operation of an ELRS-5 pump was considered for different values of the leakage coefficient. Solutions of the Cauchy problem were obtained using the numerical method. The paper presents the results of calculating the dynamics of the process of liquid pumping into the working vessel at different values of the vacuum creation time. As the time increases, the liquid flow rate quickly reaches its maximum value, and then falls with a decrease in the pressure drop. The higher the maximum flow rate, the longer the time.

Evaluation of different turbulence models on simulation of gas-liquid transient flow in a liquid-ring vacuum pump

To analyze the prediction ability and applicability of different turbulence models to the complicated gas-liquid flow in the liquid-ring vacuum pump, three different turbulence models, namely RNG k-ε, SST k-ω and LES were respectively used to simulate the gas-liquid flow, and the numerical results were compared with the experimental results. The study shows that the trend of pump hydraulic performance with the flow rate and the shape of gas-liquid interface in pump calculated by the three turbulence models have a good agreement with the experimental results. The three models are difficult to capture the small-scale bubbles in liquid-ring, but LES model can capture larger scale bubbles near the gas-liquid interface. The prediction ability of RNG k-ε and SST k-ω models to the complex vortex structures is limited for the influence of Reynolds-averaged treatment, but the LES model can predict the complex channel vortices in impeller passage and the wake vortices of different scales at the impeller outlet. The computation cost of LES model is about three times of the other two models. The RNG k-ε and SST k-ω models have better applicability than LES model if we mainly focus on the distribution of phase and pressure fields in pump.

Application and research of new energy-efficiency technology for liquid ring vacuum pump based on turbulent drag reduction theory

The liquid ring vacuum (LRV) pump is a gas-liquid rotodynamic machine which has been widely applied for over a century in areas of gas pumping. However, its high energy consumption and low efficiency has been a dramatic limitation not effectively solved by the structural optimization design. Based on an energy balance model, a novel energy-efficiency technology for the LRV pump is proposed, which uses a polymer drag-reducing xanthan gum (XG) solution as the working fluid to reduce wall friction and turbulent loss to improve the pump efficiency. The effect of XG concentration on the rheological properties of XG solution and the LRV pump performance was investigated experimentally. The results show the XG solution shows a shear thinning and viscoelastic behavior, and at an inlet pressure of 60 kPa, the LRV pump efficiency is 34.4% in pure water, but can be greatly improved to 43.2% at an optimum concentration of 4500 ppm, corresponding to a 21.4% energy saving rate (ESR). Further, the variation of ESR with time induced by mechanical degradation is well fitted with two empirical decay equations. This technology has been industrially applied to reduce energy waste of the LRV pump, and a net energy cost saving 19.07% is achieved.

Experimental study on gas-liquid transient flow in liquid-ring vacuum pump and its hydraulic excitation

To study the gas-liquid flow in liquid-ring vacuum pump and its vibration characteristics, the test system was developed for flow visualization and vibration monitoring. The flow structure was captured by high-speed camera, and the vibration sensors were mounted on the bearing house and the pump casing respectively. The study shows that the vibration amplitude trends of the bearing house and pump casing are both a quadratic curve during start-up period, and the vibration amplitude of the pump casing is closely related to the unstable gas-liquid interface. With the increase of impeller rotation speed, more and more bubbles penetrate to the liquid ring, and the wakes are becoming more intense. Under different operating conditions, the main vibration of pump casing is highly relevant to the transient gas liquid flow. The main characteristic frequencies vibration of the bearing house is caused by mechanical resonance. The vibration level of the bearing house is significantly higher than the pump casing at all conditions. The vibration level of the pump casing increases with the decrease of flow rate and the increase of rotation speed for the transient flow. The vibration level of the bearing house reaches the maximum when the rotation frequency is consistent with the natural frequency.

Novel Construction of Liquid Ring Vacuum Pumps

Novel Construction of Liquid Ring Vacuum Pumps