Steam Jet Pump Research Articles

Numerical heat transfer analysis of steam injection into subcooled water

Steam direct contact condensation (DCC) into subcooled water may be encountered in different important industrial process applications, such as steam jet pumps, steam ejectors, pressurizers, and emergency cooling systems of nuclear reactor core. In this work, a numerical simulation study has been done for injection of steam into a tank full of subcooled water. In the simulations, the Eulerian multiphase flow in addition to a realizable k-epsilon turbulence model has been utilized. Moreover, a DCC model has been used for condensation capturing. Fluent software with a user-defined function (UDF) for the DCC model was employed for simulations. The results obtained from simulations were validated with experimental results, and a fair agreement was observed. This study considered the local Nusselt number (LNN) the most suitable parameter for investigating the heat transfer rate (HTR) at the computational cell level. Therefore, the contours of the LNN, its axial distribution, and radial distribution were studied with respect to the inlet pressure of injected steam, temperature of tank water, and location along the axis of the nozzle. The results reveal the fact that the value of the LNN reaches a maximum at the nozzle exit along the axis of the nozzle at 323 K tank water temperature. LNN decreases by increasing or decreasing the tank water temperature beyond 323 K. It is claimed that the heat transfer (HT) study at such a local scale has been conducted for the first time to the best of our knowledge, and it unfolds various crucial facts regarding steam-water interaction.

Experimental study on direct contact condensation of saturated steam at low mass flux in subcooled quiescent water

Abstract The phenomenon of saturated steam jet injection in subcooled quiescent water has many practical applications including in heat exchangers, steam jet pumps, steam dumping systems in nuclear plants, etc. The experimental setup is designed and fabricated indigenously to investigate this phenomenon at lower mass fluxes ∼120 and 150 kg/m2 s. The steam jet of conical shape has been observed for all the test conditions. The recorded axial temperature distribution showed that near the nozzle region, the temperature is governed by the saturated condition of steam while the later region is dependent on the water pool temperature. The maximum temperature is observed to be at the center of the jet. It has been found that the dimensionless penetration length of the steam jet in water is directly dependent on both the temperature of the water pool and the mass flux of steam. The dimensionless jet length has been found in the range ∼1.54–2.02 and 2.07–2.19 for mass fluxes ∼120 and 150 kg/m2 s, respectively. The average heat transfer coefficient has been found in the range ∼1.97–2.37 MW/m2 K.

Design and flow simulation of a micro steam jet pump

The development of micropump is directly related to the popularization and application of microfluidic systems. Recently, microfluidic systems have more urgent requirements for stable operation and simple structure of micropumps. For these purposes, a novel micro steam jet pump which uses planar induction heating to evaporate the initial fluid is presented. This new micropump could generate continuous flow with merits of no moving parts, stable operation and easy integration. A negative pressure is formed flowed with high-speed flow of vapor in the chamber to pump and eject liquid, and then realize continuous pumping. The working chamber of the micropump is calculated with aerodynamic function, and the simulation analysis is carried on with COMSOL Multiphysics 5.5. By changing key working parameters, appropriate working conditions are adopted with simulation analysis. When the primary vapor temperature is 403.15 K, the inlet width of the tapered section of the mixing chamber is 0.4 mm and the outlet width of the diffuser is 0.5 mm, the mingling and enhancing pressure performance of the micro steam jet pump is better. The optimization of design and simulation involved in this paper provided a good guidance for the design and experimental study of the micro steam jet pump.

Design features of a high-vacuum steam jet pump and some results of its tests

This paper presents an original design of a high-vacuum steam jet pump in which a heater made of a heating cable is immersed in a working fluid located in a stainless steel boiler. At the same time, the boiler itself is vacuum isolated from the pump housing. There is also a heater made of a heating cable in a stainless steel shell, made in the form of a spiral and immersed in a working fluid. Such an arrangement of the heater is possible only when a liquid with a homogeneous chemical composition and a low saturated vapor pressure is used as a working fluid in high-vacuum pumps.

Performance comparison of different heat pumps in low-temperature waste heat recovery

The recovery of low-temperature waste heat can greatly reduce the fossil energy consumption, among whose technologies heat pumps show excellent energy saving effect and environmental friendliness. There are four commercial types of heat pumps, the absorption heat pump (AHP), absorption heat transformer (AHT), steam jet pump (SJP) and mechanical heat pump (MHP). To compare the energy performance of the four types of heat pumps in low-temperature waste heat recovery (WHR), simulation models for these heat pumps are established by Aspen Plus. The heat demand of the user side is described by a heat ratio (the ratio of the user side heat demand to the waste heat). The energy performance of four kinds of heat pumps in low-temperature WHR is compared and analyzed by the coefficient of performance (COP), exergy efficiency and annual savings of standard coal. The results show that when the heat ratio is higher than about 0.5, the MHP has the best energy performance. When the heat ratio is lower than about 0.5, the AHT is the best, for it can not only meet the heat demand of the user side, but make full use of the waste heat source as well. The performance of SJP is always better than that of AHP. Combined with qualitative economic analysis, it is recommended that the SJP is a good choice when HR is higher than about 0.7, otherwise the AHT is a suitable choice. This study can provide references for choosing a suitable heat pump in the low-temperature WHR.

О методе расчета параметров откачки ступени диффузионного вакуумного насоса

At present, steam jet vacuum pumps are widely used in various fields of science and technology due to a number of advantages, e.g., reliability, relative simplicity of design, and manufacturability, over other pumping means. The paper analyzes the existing mathematical models of working processes, methods for calculating the pumping parameters of steam-jet vacuum pumps. The problem of improving these methods, which are used in the design, is still urgent. The study attempts to further develop the models in order to increase their practical significance for the pumps design: in particular, the processes of pumping by the first stages of a diffusion pump are considered, since it is they that determine the efficiency of the pump as a whole. Analytical dependences for calculating the main pumping parameters of widely used diffusion vacuum pumps are presented. The obtained equations are a certain clarifying correction of the known provisions on this topic. Findings of research are of practical importance for the design of modern steam-jet vacuum pumps

A novel cascade heating system for waste heat recovery in the combined heat and power plant integrating with the steam jet pump

Waste heat utilization is an essential approach for improving the energy utilization efficiency of the combined heat and power (CHP) plant and a significant low-carbon way to achieve clean urban heating. To recover the excess exhaust steam heat of the CHP plant with the high back-pressure turbine (CHP-HBP), this paper proposed a novel heating system integrated with the steam jet pump (SJP). The EBSILON software was applied for modeling the proposed thermal system and analyzing the thermal performance of the CHP-HBP heating system under different operating conditions. On this basis, the coupled component-system design solution was proposed by combining the 1-D mathematical design model of the SJP with the heating system performance. Compared with the conventional system, under the design condition, the exhaust steam recovery rate and the heating capacity of the novel system had a significant increment of 8.66% and 31.8 MW with the same power output. Meanwhile, the total exergy loss and standard coal consumption rate for electricity generation of the novel system reduced by 5.74 MW and 6.77 g/kWh, respectively, with about 2.32% improvement in electricity generation efficiency. The critical parametric influence analysis on the overall performance showed that the novel system has better adaptability with some fluctuations of turbine back-pressure, supply/return water temperatures, and heating load. Under off-designed conditions, the recovery rate of the exhaust steam of the novel system was 5–20% higher than that of the conventional system, and the coal consumption rate and electricity generation efficiency both performed better. In all, the proposed system provided a promising method for the effective utilization of waste heat in the field of clean heating and the energy system optimization and integration for the coal-fired CHP plants.

Loop Heat Pipes with a Steam Jet Pump

Some configurations of cooling systems based on two-phase loops with control of the fl ow rate of the liquid and steam in them as well as experimental data obtained with these systems are presented. A model of an ejector-assisted loop heat pipe has been developed, and the results of calculations with it were compared with the corresponding experimental data.

Failure analysis of steam jet pump at top of crude oil vacuum distillation tower

The steam jet pump made by SAF 2205 duplex stainless steel (DSS) provides vacuum for vacuum distillation tower to improve the distillation efficiency of crude oil. The pump suffers from severe local wall thinning during service, especially at diffuser section. Failure analysis of the pump is carried out using traditional characterization techniques and computational fluid dynamics (CFD) simulation. The results show that the pump suffer from not only the electrochemical corrosion of acidic droplets forming in HCl-H2S-H2O environment, but also the mechanical erosion by high speed flow with a large value of wall shear stress. A vicious erosion-corrosion circle built by electrochemical corrosion together with mechanical erosion leads to severe damage at the diffuser section of steam jet pump.

Сравнение выпарных установок с механической компрессией пара и установок с применением парогенератора

Evaporation is a process through which solvent is partially removed from solutions by subjecting the latter to evaporation. Aqueous solutions of solid materials are generally subjected to evaporation; however, other liquids may also serve as solvents. The solvent being removed is in this case in vapor form and is called secondary vapor. The vapor used for heating and evaporation is called heating steam. At present, evaporation plants are widely used in purification and concentration of industrial waste waters to obtain demineralized water and sludge, which makes it possible to set up a closed water cycle at a production enterprise, to exclude discharges of hazardous substances into water bodies, and to decrease the amount of discharged waste; in obtaining demineralized water; in desalination of seawater; in evaporation of various process solutions to the required concentration (aluminate solutions, mineral salt solutions, alkalis, acids and so on); in milk and food industries; and in medicine. As a rule, evaporation is performed by applying the heat of steam produced at a boiler house or a thermal power plant. Steam is an efficient heat carrier owing to its having high heat of condensation. In some cases, when evaporation has to be carried out at high temperature, furnace gases and high-temperature heating agents (diphenyl mixture, superheated water, or oil) are used. If it is necessary to evaporate liquids sensitive to temperature effects, special equipment for creating deep vacuum (steam-jet and water-jet vacuum pumps, mechanical vacuum pumps, and others) is used. As a result, evaporation can be carried out at 60 °С (in the milk industry) and even at 35°С (in medicine). In many cases, production sites do not have a steam source, and construction of new boiler houses is economically unprofitable or unfeasible for some or other reason. In such situations, an alternative heat source is selected subject to the operation conditions of a particular plant. Process circuit versions of evaporation plants with mechanical steam compression and plants using steam generators operating on different kinds of fuel are considered. The possibilities of using one or another version depending on the properties of treated process solutions, process implementation conditions, and the number of shells in the plant (one- or multi-shell evaporation) are studied. The net cost of one ton of steam is evaluated, and the equipment payback period is estimated.

An experimental study of loop heat pipes with steam jet pump

Heat transfer devices based on the two-phase loops (TPL) technology can convert heat and kinetic energy of steam jet condensation into motive power for circulation of working fluid. TPL systems with capillary pumps can be used for transferring heat in the direction of the gravity force. This paper presents some configurations of TPL systems with liquid and steam injection flow rate control and examines the experimental data for cooling systems. In particular, a loop heat pipe with injector-condenser (LHPI), which uses a steam jet pump (SJP) as a key component, can be used in cooling systems with increased heat transfer distance.

The Economics of Cryosorption Pumping. The Practice of Using a Cryosorption Pump in an Industrial Pumping System

It is shown that in the case of well-developed infrastructure for the use of liquid nitrogen the usage of nitrogen cryosorption pumps (NCP) is significantly more economical compared to the pumping means associated with the use of mechanical and steam jet pumps. The results of preliminary tests of the experimental sample NCP as part of a vacuum unit at the NPO Geliymash confirm the prospects of using NCPs in serial production of cryogenic vessels.

The Research Progress of Steam Jet Pump Design Method

The use of steam steam ejector is formed in a Laval nozzle entrained flow speed airflow to the power unit of the body, has a simple structure, easy maintenance, stable and reliable, pumping capacity, etc.which is widely used in metallurgy, chemical, pharmaceutical , food and other industries. Based on the comprehensive domestic steam jet pump theory and design based on the results of its variety of design methods reviewed, and in accordance with design features and compare their design processes, raise steam jet pump design trends.

Experimental and numerical investigation of the effect of mixing section length on direct-contact condensation in steam jet pump

The phenomenon of direct-contact condensation is very important with respect to several industrial applications, such as steam jet pumps, direct-contact heat exchangers and nuclear reactor cooling systems. The direct and quick transfer of heat, mass and momentum across the steam–water interface makes the physics of direct-contact condensation very complex. In this work the phenomenon of direct-contact condensation, in steam jet pump, has been studied experimentally and computationally. The length of the mixing section has been varied to study its effect on the phenomenon occurring there. The experimental and CFD results obtained in this study match closely with each other and indicate towards an important process known as interface vibration process in direct-contact condensation of steam jet pump. It was found that this process has a strong dependence on the length of mixing section and plays an important role in producing high suction at the water nozzle outlet. As a result we get efficient transfer of heat, mass and momentum across the steam–water interface in steam jet pump.

Numerical and experimental study of steam‐water two‐phase flow through steam jet pump

ABSTRACTThe Steam Jet Pump (SJP) is the most suitable pump for pumping radioactive and hazardous liquids because of its mechanical simplicity, no maintenance, low cost, easy construction, no leakage, simple control, and so on. The only problem with the SJP is the complexity in the transport phenomena involved in it. In this study, the void fraction in the mixing section has been measured experimentally through gamma‐ray densitometry technique, and the flow through the SJP was simulated numerically. The reported numerical study of the SJP is very limited because of the complexity of the problem. In this work, three‐dimensional steady state numerical simulations of the SJP were carried out using the Shah Direct‐Contact Condensation (DCC) model developed previously. The experimental and Computational Fluid Dynamics (CFD) results of void fraction have been compared at different steam inlet pressure, and it was found that they match closely with each other. The transport phenomena in the SJP were explained using the CFD results of condensation heat transfer coefficient, steam plume shape, radial temperature distributions, and contours of static pressure and steam density. This study helps in validating the Shah direct‐contact condensation model and providing valuable information about the transport phenomena occurring within the mixing section of the SJP. © 2013 Curtin University of Technology and John Wiley & Sons, Ltd.

Experimental study of the characteristics of steam jet pump and effect of mixing section length on direct-contact condensation

Steam jet pump (SJP) is a simple mechanical device and may be regarded as the most suitable pump for pumping hazardous liquids because of its mechanical simplicity, no maintenance, simple control etc. In this study, an experimental setup of SJP was developed in which the mixing section was made transparent for flow visualization. The effect of the mixing section length on the transport process in SJP has been studied using three different lengths of the mixing section (110, 130 and 150mm). Moreover experiments were performed to study the suction characteristics of SJP at various operating conditions. Better performance was observed in the SJP geometry with shorter length of the mixing section. A new concept of interface vibration process in direct-contact condensation (DCC) of SJP was introduced using the experimental results. An effort has been made to explain the process of DCC in SJP using the concept of interface vibration process. The performance characteristics of SJP have also been studied in the light of interface vibration process in DCC of SJP.

Numerical Study on the Flow Structure of a Steam-Jet Vacuum Pump at Different Throat Length

The aim of the study is to reveal the complication of the flow process of a steam-jet by using the simulation software package (FLUENT). The paper is able to analyze the flow phenomena inside the steam-jet when its throat length was varied. It is found that the entrainment ratio remains unchanged when the throat length is varied. It is also found that the shocking position moved closer to the exit of the vacuum pump and the critical back pressure of the steam-jet pump increased with the elongation of the throat.

The spontaneously condensing phenomena in a steam-jet pump and its influence on the numerical simulation accuracy

A wet steam model for transonic flow was proposed to investigate the flow behaviours in a steam-jet pump. Contrary to the general ideal gas assumption adopted by the most of the researches focusing on steam-jet pump investigation, the numerical simulation using this wet steam model that was implemented based on a commercial computational fluid dynamics code, and the simulation results demonstrated the existence of the spontaneous condensation as the supersonic flow passing through the nozzle. Our results also gave good agreement with the referenced experimental data, and with higher accuracy when comparing with the results generated from ideal gas modelling. The present study confirms that the simulation accuracy can be improved by the wet steam modelling, and gives a proper prediction of pump operating status.

Numerical Research About the Internal Flow of Steam-jet Vacuum Pump: Evaluation of Turbulence Models and Determination of the Shock-mixing Layer

Steam-jet vacuum pump is widely used in a range of applications. This paper evaluated the performance of four well-known turbulence models for predicting and understanding the internal flow of a steam-jet vacuum pump first. With the help of a commercial computational fluid dynamics (CFD) code ANSYS-Fluent 6.3, the simulation results obtained from the concerned turbulence models were compared with experimental values, the k-omega-SST model was chosen as a tool model for carrying out numerical simulations. Then, based on the simulation results obtained from specific operating conditions, a method for locating the shock-mixing layer was put forward. The shape of the shock-mixing layer shows that the secondary steam does not mix with the primary steam immediately after being induced into the mixing chamber of the pump; actually, they maintain their independence till the shocking position instead. After the shock happens, the shock-mixing layer disappear, the two fluid in the pump begin to mix with each other and discharge to the next stage with almost the same state. Based on the shape of the shock-mixing layer and the supersonic region of the secondary steam, a detailed analysis for the flow duct of the secondary steam was carried out. It is found that the throat of the secondary steam flow duct plays a crucial role in maintaining a stable operating state and the length of the throat reflects the back pressure endurance for the pump.

Numerical Simulation on Flow Structure of a Steam-Jet Pump Influenced by Primary Nozzle Geometries

The aim of the paper is to reveal the flow structure and the mixing process of a steam-jet pump by using a computational fluid dynamics code FLUENT. Discusses the effect on a steam-jet pump’s entrainment ratio when the throat diameter of the primary nozzle as well as the outlet diameter of the primary nozzle is varied. Analyzes the position of shock wave which will bring the steam-jet pump’s performance a great loss. The performances of a steam-jet pump are studied by changing back pressures while the distance between primary nozzle outlet and mixing chamber inlet (DPM) is varied. The entrainment ratios of a steam-jet pump with different values of DPM and different back pressures are calculated.