Steam Jet Ejector Research Articles

Evaluasi Kinerja Steam Jet Ejector Tingkat Pertama Terhadap Kevakuman Kondensor

The steam jet ejector is a device for extracting NCG from the condenser. NCG can increase the pressure in the condenser until a vacuum condition is not reached. The diffuser pressure on the steam jet ejector has a normal operational limit of below 1 atm, meaning that the ejector performance will be optimal if it is operated at the operational limit under vacuum conditions. The expected objectives are to determine the effect of the steam jet ejector on condenser vacuum, calculate the performance of the first level steam jet ejector through pressure analysis in the diffuser section, calculate the performance of the steam jet ejector in actual conditions compared to the design data conditions and analyze actions that can be taken to improve the performance of the tool. Based on the results of calculations and analysis, it was found that the increase in steam jet ejector pressure had an effect on the increase in condenser pressure from the design pressure of 0.10 bar to 0.107-0.123 bar under actual conditions. The decrease in steam jet ejector performance results in the condenser vacuum level decreasing, but the equipment performance is within normal operational limit conditions, namely below 1 atm. The decrease in steam jet ejector performance is influenced by the motive steam mass flow rate, NCG mass flow towards suction, entrainment ratio value, NCG pressure and motive steam pressure which exceeds the design data.

Performance evaluation of a novel geothermal energy integrated single effect evaporator desalination with software simulation

Water desalination utilizing low-enthalpy geothermal fluid is a sustainable solution to the world's water shortage that has the potential to be integrated with thermal-based desalination technologies. This study presents a comprehensive method for the performance analysis of a geothermal combined single-effect evaporator without a steam jet ejector and a single-effect evaporator with a steam jet ejector for the production of 1 kg of fresh water per second. To build the geothermal combined single-effect evaporator system, we compared the outcomes of manual computations performed in Excel and MATLAB/Simulink. MATLAB/Simulink includes a Graphical User Interface (GUI) that allows users to generate block designs through click-and-drag mouse activities. Calculations performed manually, Excel or MTALB/Simulink, should all have the same value, with only a little variation. In this case, latent and sensible heat for seawater evaporation is supplied by low enthalpy geothermal heat employed as heating steam with a temperature of less than 130 °C. We focus on a wide range of characteristics to better understand the impact of design choices on evaluation findings. Some variables include heating steam temperature, boiling temperature, feed water salinity, and geothermal resource quality. The accuracy of the results of our fundamental model was assessed by adjusting their values. The simulation results show that using a low boiling temperature and a high motive steam pressure yields a greater PR.

Features of the Development and Operation of Multistage Steam Jet Ejectors

Features of the Development and Operation of Multistage Steam Jet Ejectors

Thermal modeling and simulation of a single-flash geothermal power plant involving non-condensable gas: a case study of Kamojang geothermal field in Garut, West Java, Indonesia

The presence of non-condensable gases (NCGs) in a geothermal fluid disrupts the vacuum process in the condenser, reducing turbine efficiency and decreasing the total power output of the geothermal power plant (GPP). Therefore, to optimize the thermodynamic efficiency of a GPP, NCGs should be removed using a gas removal system. Since there is a substantial lack of design and simulation software for a GPP including NCG removal alternatives, in this study, we aimed to model and develop a software-based interface to simulate mass and energy balance involving an NCG fraction in a single-flash GPP as well as examine the thermodynamic performance of the gas removal system, which is the most important step in the planning and designing phase of a GPP. This software was validated using outputs of Kamojang GPP Units 2, 3, and 4 located at Kamojang geothermal field, Garut, West Java, Indonesia. Units 2 and 3 use two ejectors which are installed in series, and Unit 4 utilizes a hybrid system (HS) that is mostly a combination of vacuum pumps and a steam jet ejector (SJE). Our results showed that Kamojang GPP Units 2 and 3 generate 55.295 MW of power with an absolute error of 0.53%, whereas Unit 4 generates 60.218 MW of power with a 0.36% absolute error concerning the field data. These results correspond with the expected minimum error; therefore, our model’s parameters are considered valid and can be used for simulation. We found that using the simulation, the total steam saved by the HS at Kamojang GPP Units 2 and 3 was 534 kW. Furthermore, the net power production was reduced by 1.6% for the HS and 2.03% for the SJE with every 1% increase in the NCG fraction. The power requirement of the vacuum pumps remained less than the power generated by the motive steam which the ejector requires to dispose of the same amount of NCG, indicating that Kamojang GPP Units 2 and 3 will be more efficient if an HS is used.

Improving the efficiency of condensation installations of steam turbines by applying liquid-vapor ejector

This paper considers the possibility of using liquid-vapor ejectors in condensing units of steam turbines. This unit is designed for pumping out a steam-air mixture from a steam turbine condenser, in which the process occurs at a pressure lower than atmospheric. In the traditional scheme, this is provided by a two-stage steam-jet ejector unit. The proposed scheme involves the use of a single-stage liquid-vapor ejector and its possible pre-vacuum mode of operation in conjunction with a liquid-ring vacuum pump. A working process of the liquid-vapor ejector does not require the supply of working steam from the outside since its generation occurs in the active nozzle of the liquid-vapor ejector. A description of the traditional scheme and the proposed options is given, which are different both in the scheme solution and in the operating parameters. The object of this study is a liquid-vapor ejector, which is used in the condensing system of a steam turbine. Thermodynamic calculation of the proposed circuit solutions was carried out. As a result, the necessary mode parameters of the schemes were determined. To assess the feasibility of using a liquid-vapor ejector in the condensation systems of steam turbines, an exergy analysis was performed. The proposed scheme makes it possible to increase efficiency by 2.3 times, and when used with a liquid-ring vacuum pump – by 2.44 times. To assess the economic efficiency of the modernization of the condensing system, thermoeconomic analysis was performed. The use of the proposed scheme makes it possible to reduce the cost of generating boiler steam and reduce the cost of the resulting product of the steam turbine unit by about 51 %. The estimated cost of a unit of the amount of boiler steam consumed per ton of product and the unit cost of steam were established.

Enhancing the efficiency of a steam jet ejector chiller for chilled ceiling

• Steam jet ejector chillers (SJECs) can be suitable for buildings with high solar gains. • SJEC was combined with radiant chilled ceiling instead of convective cooling terminal. • Increasing evaporation temperature by using chilled ceiling improved COP. • This allows lower generation temperature resulting in smaller solar collector areas. Steam jet ejector chillers (SJECs) can be a suitable cooling technology in buildings where solar heat gains constitute a significant part of the cooling load. In this study, an SJEC was combined with a radiant chilled ceiling (CC) instead of traditionally used convective cooling terminals in an effort to increase the coefficient of performance (COP) by increasing the supply water temperature to the terminal ( T water,sup ) and thus the evaporation temperature. Experiments were used to verify a mathematical model of SJEC. The model was combined with T water,sup obtained from heat transfer calculations in three types of CC performed by a verified software. The COP of the ejector cooling system was 0.25 and 0.38 for R718 (water) and R1233zd, respectively, at a generation temperature of 130 °C and T water,sup of 7 °C, assuming a fancoil. Increasing T water,sup to 9 °C, which was considered to be the lowest T water,sup theoretically possible for CC involving pipes underneath the surface, improved COP by up to 14% while providing a maximum cooling capacity of about 80 W per m 2 of room area. Further increasing T water,sup to 15 °C improved the COP by 50% compared to the fancoil, while covering cooling loads of at least 40 W per m 2 . The estimated reduction in generation temperatures due to increased COP was up to 12% ( T water,sup = 9 °C) and 37% ( T water,sup = 15 °C). This means a lower energy input needed for the cooling machine, which allows a smaller solar collector area.

ENHANCEMENT OF STEAM-TURBINE CONDENSER STEAM-JET EJECTOR

A three-stage steam-jet ejector EPO-3-200 with a working steam flow rate of 850 t / h is installed at the Combined Heat and Power Plant-2 of the city of Almaty on heating turbines. In this paper, the replacement of the existing three-stage steam-jet ejector with a two-stage steam-jet ejector is proposed and substantiated. As a result of the replacement, they obtained a saving of heat (steam) for their own needs for the production of electrical energy. It has been established that at a pressure in the turbine condenser significantly lower than 100 kPa, it is advisable to install a new two-stage ejector EPO-2-80 instead of EPO-3-200. Using the existing calculation methods, the geometric characteristics of the new ejector were obtained. The working steam flow rate of the new two-stage ejector is 579 t / h. In addition, the use of two stages makes it possible to simplify the design and make it more reliable, and also makes it possible to increase the pressure in the cooler of the 1st stage of the ejector. This is especially important for cogeneration turbines, which may have a high temperature of the main condensate, which adversely affects the performance of a conventional three-stage ejector.

Trends in Research and Development of Multistage Steam Jet Ejectors for Steam-Turbine Units

Three important avenues of perfecting multistage stream jet injectors aimed at improving their reliability, economic efficiency, and performance are presented, and examples of implementing them are given. In regard to reliability improvement, the designs of existing serially produced ejectors available from different manufacturers, in particular the Ural Turbine Works, Leningrad Metal Works, and Kharkiv Turbine Works, are analyzed. New technical solutions are developed, including external vertical ejector coolers and jet devices with a variable axial distance between the nozzle and diffuser. To reduce the ejector’s mass and dimensions, its first stage is split into two parts. Two approaches to improving the economic efficiency of the devices are considered: decreasing the working steam parameters to the ejector (the temperature and pressure) and taking into account the effect that the increased ejector capacity has on the deviation of vacuum in the condenser from its normal design value. Tests of serially produced ejectors under different conditions of their operation are carried out. The ejector performance can be improved through perfecting its jet device using calculation, numerical, and experimental methods. Based on the results from visual examination and flaw detection of existing serially produced ejectors, the lines of modernizing their designs are determined. A more accurate procedure for ejector calculating is developed. For elaborating the procedure, the geometrical parameters of existing serially produced ejectors and the results of their industrial tests were generalized, and their numerical modeling was carried out. The developed procedure and new design solutions have been successfully implemented in two types of ejectors. New ejectors have been installed at various thermal power plants as part of condensing and cogeration turbines; significant economic effect lies in reducing the deviation of the vacuum in the condenser from its standard values, which makes it possible to reduce overburning of fuel in the cycle of a steam turbine unit.

An integrated steam jet ejector power plant for drought adaptation considering water-exergy nexus in an optimal platform

Steam power plants contribute to anthropogenic climate change by emitting a considerable amount of carbon dioxide and losing significant freshwater. In the present study, a novel model-based steam jet ejector power plant is optimally designed to adapt to climate change by minimizing water losses and greenhouse emissions. An iterative thermo-mathematical program and a nonlinear mathematical model represent the system's energy and economic models. At the same time, an exergy analysis evaluates its performance according to the Second law of thermodynamics. A non-dominated sorting genetic algorithm generation III is interfaced with the developed empirical program to solve a multi-objective optimization model. Three decision-making scenarios including a maximum thermal efficiency (I), minimum cost of energy (II), and minimum heat losses (III) are considered to select appropriate configurations in the final Pareto front. Subsequently, a natural draft wet cooling tower and a once-through cooling system are coupled with the optimal configurations. The performance of the fully-integrated systems is evaluated using four new water-exergy nexus criteria including water withdrawal for exergy dissipation, lost exergy for exergy dissipation, water consumption for fuel and product exergies. Finally, a sensitivity analysis is performed to take the environmental fluctuations and model uncertainties into account. The comparative results showed that water consumption for product and fuel exergies improved by 63.65 and 64.08%, while water withdrawal for exergy dissipation of the system was approximately nine times smaller than available model-based steam power plants. Moreover, the energy efficiency of the proposed system was 1.42% greater than the previous systems at the cost of 0.018 $/MJ more cost of energy. Thus, the proposed system can tackle drought and mitigate climate change with more investment in the energy sector.

Оценка модернизации включения газоотводящих аппаратов вакуумных деаэраторов

The issue of increasing the reliability of gas exhaust devices remains quite relevant, since a large number of violations of vacuum deaeration of water are associated with their failures. Jet gas removal devices - ejectors, are used as devices for removing non-condensable corrosive gases from vacuum deaerators. The article provides a detailed description of the designs and existing types of steam-jet and water-jet ejectors, provides a classification of ejectors, their scope. Moreover, in this paper, schemes for switching on ejectors are presented, the positive and negative aspects of each of the types of ejectors are considered. In particular, in this work, the scheme of operation of a combined heat and power plant (CHP) with the combined use of steam-jet and water-jet ejectors is considered, and an assessment is made of the modernization carried out at Ulyanovsk CHP-2, associated with an additional installation of a water-jet ejector.

Influence of Cooling Medium Flow Character on the Operation of Heat Exchangers with Steam Condensation Inside Tubes

The influence of the character of cooling medium motion in a heat exchanging apparatus on the process of steam condensation in the latter is considered in the cases of cross flow past a tube bank in the apparatus, longitudinal flow past tubes in the bank in the regimes of forward flow and countercurrent flow, superheated steam condensation, and of nonuniform distribution of the cooling medium in different zones of the apparatus. It has been established that in the case of cross flow past the first rows of the tube bank, cooling medium zones with reduced heat transfer efficiency appear in the apparatus. The dependence of the pressure losses by the steam, which condenses in a heat exchanger in regimes of countercurrent flow, forward flow, and cross flow, is investigated. Experimental data on the superheated steam temperature have been obtained and generalized. The positive influence of the throttle on the line of removal of the steam–air mixture to a steam–jet ejector in nonuniform cooling of the parallel channels of the condenser has been established experimentally, and the presence of the optimal size of the throttle on the line of removal of noncondensing gases has been confirmed.

Investigation of Parallel Operation of Vacuum Condenser Sections with Nonuniform Cooling

Vacuum condensers for steam turbines are usually designed at design conditions when all condenser sections are cooled identically with the flowrate of cooling water (or air for air-cooled condensers) and the same air inleakage in each section. A deviation from the design operating conditions occurs due to several causes, such as nonuniform cooling of the condenser heat transfer surface because of its fouling or a fan failure (in air-cooled condensers) and local air inleakage. To investigate condensation under nonuniform cooling conditions, a test facility simulating a condenser was constructed. It consists of two parallel channels. Nonuniformity of cooling in one of the channels was simulated by reducing the cooling water flow. There were regimes with steam feeding into air to model air inleakage occurring in actual condensing units. The experiments were performed in the condensation pressure range of pc = 8–20 kPa. The previous predictions suggest that installation of orifices with a low-pressure drop can reduce the condenser pressure in case of nonuniform cooling. The effect of orifices with different diameters on the condensation process parameters was studied in this test facility. It has been demonstrated that installation of the orifices facilitates a decrease in the condenser pressure with a cooling water flow rate through one of the channels less than 50% of the design value. A range of optimal orifice diameters for this experimental condenser model was determined. According to the experiments, the benefit of orifice installation is observed only in case of joint operation of the condenser with a volumetric degasser, such as a steam jet ejector. The experimental data demonstrate an increase in the efficiency of joint operation of a condenser and an ejector under nonuniform cooling conditions due to installation of orifices in the line of steam-air mixture ejection.

Current State and Trends in the Design and Operation of Water-Cooled Condensers of Steam Turbines for Thermal and Nuclear Power Stations (Review)

A review and analysis are presented of the available foreign publications on the modern methods of design, manufacture, design calculation, and operation of water-cooled condensers for large steam turbines used in Russia and abroad. A list of the world’s leading manufacturers of condensers is presented. The adopted alternative arrangements of condensers concerning the turbine centerline and available condenser design styles are examined. The condensers for turbines manufactured by General Electric and the Leningrad Metal Works (LMZ) are compared by their design characteristics and performance indices. The arrangements of tube bundles used in designing and upgrading condensers in Russia and abroad are presented. Information is given on construction materials of condenser tubes and tube sheets as well as on the methods for tube-to-tube sheet attachment. Data on air removal equipment of the condensers are presented. The basic lines of evolution of steam jet ejectors, water-ring pumps, and hybrid air removal systems are considered. The methods of condenser heat-transfer surface cleaning adopted in Russia and abroad are compared. The data on the number of failures and the basic causes of these failure are presented. The procedures for replacement of tubes during repair or modernization of condensers and the symptoms used to determine the necessity of tube replacement are described. Information derived from the authors' investigations and a review of American publications on the potential for heat transfer enhancement in the condensers through the use of shaped tubes is given. The condenser design methods and standards applicable in Russia and abroad are assessed. The lines of improvement in the design of condensers for modern steam turbines of thermal and nuclear power stations are outlined.

Energy, exergy and economic analysis of a hybrid spray-assisted low-temperature desalination/thermal vapor compression system

Integrating thermal desalination systems with vapor compression is an effective way to improve the energy efficiency. This paper investigates a spray-assisted low-temperature desalination system that is integrated with a thermal vapor compression system (SLTD-TVC). A detailed thermodynamic model is judiciously developed based on the principles of heat and mass transfer, heat balance, mass balance, and exergy balance. Applying the model, the energy efficiency of the combined SLTD-TVC process is first evaluated. The production ratio of the combined system is found to be 10–35% higher than that of the conventional SLTD process. Accordingly, an exergy analysis is conducted to quantify the sources of irreversibility within the system. The steam jet ejector is found to be the major source of thermodynamic irreversibility, accounting for more than 40% of the exergy destruction. The overall system efficiency is improved at a lower motive steam pressure, a higher number of operating stages and a medium cooling water flowrate. Finally an economic analysis is carried out, which reveals that the changes of both initial plant cost and operation cost are marginal after the integration of the thermal vapor compression system.

Experimental and numerical investigations on the effect of suction chamber angle and nozzle exit position of a steam-jet ejector

Implementation of renewable energy in existing applications has become an emerging trend in order to mitigate the environmental issues. Specifically, HVAC sector urges for more efficient and eco-friendly systems which can effectively replace the high grade energy in conventional systems. One of such promising environmental friendly systems is the ejector refrigeration system which has low initial and operating costs, simple system components and trouble free operation. In spite of these merits, it suffers from low performance due to the complex irreversible fluid flow prevailing in the ejector. Comprehensive analysis and understanding of all the geometrical and operating parameters governing the ejector flow are vital for increasing the performance of the entire system. In this study, the most crucial geometrical parameters such as suction chamber angle and the Nozzle Exit Position (NXP) of a steam operated ejector are systematically investigated using CFD and experimental techniques. The influence of operating conditions with respect to the geometrical parameters has been observed, and for the tested conditions of 700 W evaporator at 10 °C cooling temperature the suction chamber angle of 12° and the corresponding NXP of 24.7 mm delivered an optimum performance for the active and back pressures of 2 bar and 43 mbar respectively.

Conceptual design of high-speed underwater jet engine using high concentration of hydrogen peroxide

The conceptual design of high-speed underwater jet engine was conducted and demonstrated using high concentration of hydrogen peroxide as a green propellant. On the basis of the principles of steam jet ejector, the central water jet configuration was applied for the engine where a central water jet was surrounded by an annular steam flow. The annular steam flow as the primary fluid was the decomposition gas of hydrogen peroxide and cold water was the secondary fluid. The catalyst pack was composed of the alumina pellets doped with manganese oxides. The performance evaluation of the engine was performed without the flow field of the secondary fluid. The demonstrator successfully generated a practical propulsive force, which could be applied for the systems of unmanned underwater vehicles. For design of experiments, the nozzle exit areas were dealt with. It should be ensured that the exit area of nozzle was sufficiently large to prevent thrust instabilities due to the disturbance in the high-speed flows. In contrast, the excessively large area of the nozzle exit might decrease the efficiency of the engine performance in that the geometry of the engine failed to encourage the heat energy transfer between the primary and the secondary fluids.

Application of jet thermal compression for increasing the efficiency of vacuum systems

The article describes the principle of jet thermal compression with reference to vacuum systems. We consider liquid-vapor ejectors, the working process of which is based on this principle, as an alternative to existing steam jet ejectors. The results of a theoretical and experimental investigations of the liquid-vapor ejector of a vacuum unit are presented. With the help of thermodynamic analysis of exergetic efficiency, the range of operation of the liquid-vapor ejector and the vacuum unit on its base is determined, at which its performance is at the maximum level. The efficiency of vacuum creation by such units is estimated by the example of various pumped media, such as saturated, superheated steam and steam-air mixture.

Functioning efficiency of intermediate coolers of multistage steam-jet ejectors of steam turbines

Designs of various types of intermediate coolers of multistage ejectors are analyzed and thermal effectiveness and gas-dynamic resistance of coolers are estimated. Data on quantity of steam condensed from steam-air mixture in stage I of an ejector cooler was obtained on the basis of experimental results. It is established that the amount of steam condensed in the cooler constitutes 0.6–0.7 and is almost independent of operating steam pressure (and, consequently, of steam flow) and air amount in steam-air mixture. It is suggested to estimate the amount of condensed steam in a cooler of stage I based on comparison of computed and experimental characteristics of stage II. Computation taking this hypothesis for main types of mass produced multistage ejectors into account shows that 0.60–0.85 of steam amount should be condensed in stage I of the cooler. For ejectors with “pipe-in-pipe” type coolers (EPO-3-200) and helical coolers (EO-30), amount of condensed steam may reach 0.93–0.98. Estimation of gas-dynamic resistance of coolers shows that resistance from steam side in coolers with built-in and remote pipe bundle constitutes 100–300 Pa. Gas-dynamic resistance of “pipein- pipe” and helical type coolers is significantly higher (3–6 times) compared with pipe bundle. However, performance by “dry” (atmospheric) air is higher for ejectors with relatively high gas-dynamic resistance of coolers than those with low resistance at approximately equal operating flow values of ejectors.

Analysis of experimental characteristics of multistage steam-jet electors of steam turbines

A series of questions for specification of physical gas dynamics model in flow range of steam-jet unit and ejector computation methodology, as well as functioning peculiarities of intercoolers, was formulated based on analysis of experimental characteristics of multistage team-jet steam turbines. It was established that coefficient defining position of critical cross-section of injected flow depends on characteristics of the “sound tube” zone. Speed of injected flow within this tube may exceed that of sound, and pressure jumps in work-steam decrease at the same time. Characteristics of the “sound tube” define optimal axial sizes of the ejector. According to measurement results, the part of steam condensing in the first-stage coolant constitutes 70–80% of steam amount supplied into coolant and is almost independent of air content in steam. Coolant efficiency depends on steam pressure defined by operation of steam-jet unit of ejector of the next stage after coolant of steam-jet stage, temperature, and condensing water flow. As a rule, steam entering content of steam-air mixture supplied to coolant is overheated with respect to saturation temperature of steam in the mixture. This should be taken into account during coolant computation. Long-term operation causes changes in roughness of walls of the ejector’s mixing chamber. The influence of change of wall roughness on ejector characteristic is similar to the influence of reverse pressure of the steam-jet stage. Until some roughness value, injection coefficient of the ejector stage operating in superlimiting regime hardly changed. After reaching critical roughness, the ejector switches to prelimiting operating regime.

Investigation of the Overall Efficiency of Steam Jet Ejector over a Range of Working Conditions

A common use of steam ejector is a simple vacuum pumping. It has been shown many advantages, primarily the ejector is inexpensive, small, no moving parts to go wrong, and also the equipment has shown significant cost reduction in the operating stage over the mechanical pumps when the exhaust steam be put to an effective use. The present work addresses with the development of a steam jet ejector by studying the effect of nozzle geometry on the efficiency and performance of steam jet ejector. The main objective of this study is to assess the efficiency of steam ejector as pump and as feed heater with variable pressures and temperatures for different nozzle diameters used (2, 3, 4, 5, 6 mm). The system that has been built in the present work consists of boiler, feed water tank with feed pump, suction and delivery tank, and ejector. The results show that the efficiency of ejector as pump will increase, while the efficiency as a feed water heater decreases if the steam mass flow rate or steam pressure increases. Also, the ejector efficiency will rise up for smaller nozzle inlet diameter, and the best performance was obtained at 4.5 bar steam pressure.