The proper functioning of a steam jet ejector is depen. Basic ejector components are the steam chest, nozzle, suction, throat, diffuser and they discharge fig. Nash has been designing, manufacturing and troubleshooting steam jet air ejector systems since 1986. The new standard now integrates the previous three separate standards on steam jet ejectors. Steam ejectors provide vacuum in many process industries and utility companies. After the cooking process the pressure inside the autoclave was around 3 bar. The first two stages of these units arefourstage ejectors usually steamjacketed. Used extensively throughout the process industries, steam ejector vacuum systems offer a reliable and economical means of handling high volumes of gas and vapor streams at low pressures. How an air ejector works in a boiler feed system the air ejector draws out the air and vapours which are released from the condensing steam in the condenser.
A steam ejector basically comprises of three 3 elements. It is has a wide range of application in steam ejector in boiler condenser, fresh water generator and in priming the centrifugal pump. Dec 11, 20 nash enerjet steam ejector how it works duration. Aug 08, 2012 an air ejector or steam ejector is a device which uses the motion of moving fluid motive fluid to transport another fluid suction fluid. Steam jet ejectors for the process industries robert b. The terms of jet pumps ejectors are defined in din 24290. What is the difference between a steam ejector and injector. I worked on a project before where a medical waste facility cooked the medical waste in a pressure vessel called an autoclave. The attached figures illustrate the two types of steam jet air ejector sjae systems used in the industry to remove noncondensables and water vapor from main condensers. Working principle of steam ejector power plant tutorials. Steam jet ejectors steam jet ejectors are based on the ejector venturi principal and operate by passing motive steam through an expanding nozzle. Jul, 2016 graham has mastered steam ejector design.
Depending on the application, an injector can also take the form of an eductor jet pump, a water eductor or an aspirator. In condesing system, steam ejector has function to extract air and other noncondensing gases from the sealed condenser, and in such way to maintain vacuum which corresponds to ratio of. The primary advantages of steam jet ejector are simplicity of operation, no mechanical drive and has no moving parts. However, at lower compression ratios, the optimal area of the mixing chamber becomes large relative to the motive nozzle throat area. An injector uses boiler steam to pump water into a boiler, an ejector uses boiler steam to pump air, water or other fluids. Ejector products steam jet ejectors unique systems inc. Ejector rack, an aircraft fitting for carrying bombs. Graham corporation ejector efficient operation youtube. Steam jet ejectors offer a simple, reliable, lowcost way to produce vacuum. Ejector design software ejector sizing calculation. In an increasing number of applications it is necessary to apply controls.
Review on ejector efficiencies in various ejector systems. Exhaustive survey has been conducted on the influence of geometrical parameters on the efficiency of the ejector as well as critical flow parameters to improve the overall performance. Featuring proven, unique internal geometries and tightly tolerancecontrolled steam nozzle configurations, graham ejectors produce very low steam. Pdf effect of nozzle geometry on a model thermocompressor. If you can then use the typical steam jet ejector, the second article tells points. The first two stages of these units arefourstage ejectors usually steam jacketed. An ejector performance curve gives the expected suction pressure as a function of watervapor equivalent loading fig. Lienhard vd a massachusetts institute of technology, cambridge, ma, u. Steam jet air ejectors sjae turbine bypass desuperheating systems general. Ejector or injector, a pumplike device without moving parts static mechanical equipment steam ejector, a railway locomotive component used to create vacuum ejection seat, an escape device for aircraft. The suction flow is compressed to a higher pressure. This paper presents a numerical investigation of an r744 liquid ejector applied to a supermarket refrigeration system. If you can then use the typical steam jet ejector, the second. Understanding ejector systems necessary to troubleshoot.
In operation, steam issuing through an expanding nozzle has its pressure energy converted to. Performance optimization of steam jet ejector using cfd. Combining low capital cost, simple operation, high reliability and the ability to handle large volumes at very high vacuum levels, they can be optimized to. Steam jet ejectors are based on the ejector venturi principle. Ejector design software to do conceptual design and generate ejector sizes. Steam jet ejectors for the process industries mcgrawhill.
When a high pressure motive fluid steam liquid enters the steam nozzle, this result in a decreasing pressure and increasing velocity of the fluid again the fluid enters in the diffuser which result in a increasing pressure and decreasing velocity of the fluid so due to pressure difference vacuum is created in between the nozzle and diffuser we can say venture. These systems operate on the ejector venturi principle, which relies on the momentum of a highvelocity jet of steam to move air and other gases from a connecting pipe or vessel. Controlling ejector performance pumps operating on the ejector principle are in use on many processes. The motive fluid for these type of water jet ejectors is water instead of steam. Behind the first receiver nozzle there are additional nozzle stages, each of which has a bigger. The efficiency of the ejector cycle is very sensitive to the ejector efficiency. Other types of injector may use other pressurised motive. The partial vacuum in the vessel causes some of the. The jet ejector is classified into two types depending on its convergence configuration.
Ejector design very simply, an ejector is a pumping device. Normal range for a water jet ejector is from atmosphere to 45 mm hg abs depending upon the water temperature. Understand realworld problems of vacuum ejector performance. The heart of all hijet systems is the hijector a liquid jet ejector of proprietary design. Design features and operation of jet ejectors korting hannover ag. Ejector working principle mechanical engineering site.
Ejector efficiency is found to be highest at low compression ratios and at low driving pressure ratios. Steam is passed through a vacuum ejector of high efficiency to exhaust a separate, closed vessel which forms part of a cooling water circuit. How an air ejector works in a boiler feed system steam. A high pressure motive fluid, typically steam, enters the steam ejector and passes through the nozzle.
Typical threestage steam jet ejector used in processing vegetable oils. Basic principles of vacuum technology, brief overview festo. Besides liquid ring vacuum pumps lrvps, another common vacuum generating device is the steam jet air ejector or steam ejector basic steam ejector structure. Oct 22, 2016 ejector design very simply, an ejector is a pumping device. Free demo programs for a short time are offered to let you see how the ejector program works they are not intended for your design work. Pumps of the ejector types are small in relation to work they do and their cost is low in comparison with other type of equipment. Producing a vacuum with steam jet ejectors in a vacuum jet ejector, the lowpressure vent steam is the motive energy source. In some applications another condenser aftercondenser can be used at the low vacuum ejector discharge. Rotary airlocks can be replaced by venturi eductors to serve as conveying system for solids. Ejector design software ejector sizing calculation ezejector. Both are venture devices, jet pumps, and work with few or no moving part. Feb 21, 2018 an injector uses boiler steam to pump water into a boiler, an ejector uses boiler steam to pump air, water or other fluids. Ejectors thus have the advantage that they can be driven with waste heat, and used as heat pumps in appropriate cycles to produce heat upgrading, cooling or refrigeration effects, provided that a thermal source is available.
An ejector operates on similar principles to create a vacuum feed connection for braking systems etc. Threestage condensing steam jet ejectors consist of a booster ejector, a booster condenser, and a twostage ejector consisting of a highvacuum ejector, intercondenser, and low vacuum ejector. This create a vacuum in a vessels or chamber to which ejector is connected. The detailed operation of the steam ejector is further represented in the form of a literature study. Pdf on apr 10, 2012, kavous ariafar and others published effect of nozzle geometry on a model thermocompressor. Ejector efficiency, entrainment ratio, onedimensional model, perfect expansion. The figure 1 illustrates basic operation principle of the steam jet ejector. Steam ejectors are frequently used in condensing steam turbine systems for creation of vacuum in vacuum condesers thus improving turbine and system performance. The jet ejector performance is mainly affected by mixing, turbulence, friction, separation, and energy. Ejectors and steam jet ejectors document library graham.
The steam ejector utilizes high pressure steam to compress low pressure vapors or gases. Steam jet ejector water jet ejector vacuum jet ejectors. Apr 26, 2017 i worked on a project before where a medical waste facility cooked the medical waste in a pressure vessel called an autoclave. Very often, the motive fluid is steam and the device is called a steam jet ejector. Liquid jet mixers for food applicationsorbitally welded design. Steam jet vacuum systems combine ejectors, condensers and interconnecting piping to provide relatively lowcost and lowmaintenance vacuum pumping. The steam jet blower is a steam jet or air jet air pump designed for large capacities at low drafts.
Onedimensional model of an optimal ejector and parametric. The steam propellant expands while traveling through a divergent nozzle. Due to the pressure drop of the motive fluid, it will create a lowpressure zone before the mixing chamber. The author presents some of the more recent ejector design theories and compares. This basic principle applies to every jet ejector in different models and ranges of application. Onedimensional model of an optimal ejector and parametric study of ejector efficiency ronan k. Steam jet ejectors are based on the ejectorventuri principle. Four, five and sixstage steam jet ejector units are used for applications where required suction pressures are beyond the range of the ejectors previously described. Pdf download for some problems in the design and operation of jet.
A steam jet ejector is a simple device that uses pressurized steam to create a partial vacuum inside an enclosed system by pumping gases and vapors out of the system. How it works working principle hvac industrial engineering phx heat transfer duration. The operating principle of the ejector is the pressure energy in the motive fluid is converted to velocity energy by an adiabatic expansion in the convergingdiverging nozzle. Ejector transformers, a character from the transformers franchise. Steam jetejectors educt process gases into the steam chest and then through a specially understand realworld problems of vacuum ejector performance use these guidelines and case histories to evaluate and troubleshoot. An air ejector or steam ejector is a device which uses the motion of moving fluid motive fluid to transport another fluid suction fluid. The ejector sprays high speed steam, gas, or liquid through a nozzle and can produce vacuum stages. The definitions of overall ejector efficiency and ejector component efficiencies in literature are. Basic operating principle of the hijector is a momentum transfer from highvelocity and highdispersed liquid flow to gas or vapours, formation of supersonic two phase flow, subsequent braking of the flow and thus converting kinetic energy of. A steam jet ejector is illustrated below as example steam serves as motive fluid to create. Figure 2 illustrates the principle of operation of an ejector based heat pump system.
Basic components of a steam jet ejector a single stage steam ejector can produce only a limited vacuum cfr. Steam ejector, a railway locomotive component used to create vacuum. Heat exchange institute standards for steam jet ejectors describes the method to convert the mixture air, water vapor, and. A complete guide to getting the best from steam jet ejectors. The fourstage unit consists of 1 a primary booster while four, five, and sixstage ejectors are usuallyejector. Ejector or injector, a pumplike device without moving parts static mechanical equipment. When a high pressure motive fluid steamliquid enters the steam nozzle, this result in a decreasing pressure and increasing velocity of the fluid again the fluid enters in the diffuser which result in a increasing pressure and decreasing velocity of the fluid so due to pressure difference vacuum is created in between the nozzle and diffuser. Operating principles of hijet systems liquid jet ejectors. Steam flow to an ejector must be maintained at the design rates, otherwise vacuum column operating pressure may increase. Some problems in the design and operation of jet ejectors, m. The nozzle provides controlled expansion of the motive steam to convert pressure in to velocity which creates a vacuum with in the body chamber to draw in and entrain gases or vapours. The use of the liquid ejector enables the operation of the evaporator in a flooded mode and recirculates the r744 liquid phase, which improves the energy efficiency of the refrigeration system.
A jet ejector requires no mechanical drive and has no moving parts. These power systems have found wide acceptance in modern plants because of the small space requirements, simplicity, reliability, low maintenance and quick. The attached article has a equation english units as given in the standards for steam jet vacuum systems published by heat exchange institute hei. The function and fluid dynamics of a steam jet ejector is explained by means of a theoretical model found in literature. The ejector design principles used in the ejector calculations for the program are explained including the ejector energy balance and effects of the ejector flow cones. When first developed, its operation was intriguing because it seemed paradoxical, almost like perpetual motion, but it was later explained using thermodynamics. The operation of steam ejectors is based upon the massvelocity venturi principle. Steam jet ejectors for the process industries by robert b. If the air were not removed from the system it could cause corrosion problems in the boiler. In addition, the sizes in the major sections of the novel ejector lie in the best range.
Constantarea jet ejector the different between both types is shown in figure 1. Ejectors are essentially a fixed capacity device since the. It would be better if you can get hold of the standard. The ejector design principles used in the ejector calculations for the program are explained including the ejector energy balance and effects of the ejector flow cones free demo programs for a short time are offered to let you see how the ejector program works they are. Jet ejectors the term jet ejector describes a device in which a pumping effect is achieved using a motive fluid. The application determines the design of the flow section.
Reliable vacuum service for the process industries. The applica tion determines the design of the flow section. Four, five and sixstage steam jet ejector principle of operation. The nozzle is designed to produce a jet at high velocity by expanding the motive fluid from inlet to suction pressure. The single stage ejector, in its simplest form, consists of an actuating nozzle, suction. Due to the lowpressure zone, the suction fluid will start to. They are especially effective in the chemical industry where an onsite supply of. In a vacuum jet ejector, the lowpressure vent steam is the motive energy.
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