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 ejector uses a converging nozzle to increase the fluid velocity to transform. A steam jet ejector is illustrated below as example steam serves as motive fluid to create vacuum. 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. Steam ejector liquid ring pump systems for batch reactor 7. 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. If you can then use the typical steam jet ejector, the second article tells points. 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. The steam jet ejector utilizes high pressure steam to compress low pressure vapours or gases. 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.
In this paper, the steam jet ejector was designed and then the cfd analysis was carried out for the geometry and the inlet condition data verified by the performance evaluation of the jet ejector. Performance optimization of steam jet ejector using cfd. Graham corporation ejector efficient operation youtube. Steam ejectors provide vacuum in many process industries and utility companies. The steam ejector is a simple device consisting of three basic components, a motive steam nozzle, a suction chamber and a mixing diffuser. 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. Jul, 2016 steam jet ejectors, the largest vacuum producing devices available are used in the most demanding of applications. 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. The thermocompressor is a steam jet steam compressor, shown with a diaphragmoperated spindle for control purposes. Steam jet ejectors are based on the ejectorventuri principle.
Controlling ejector performance pumps operating on the ejector principle are in use on many processes. Ejector design software ejector sizing calculation ezejector. The major advantage of ejectors over vacuum pumps is the fact that they have no moving parts and are thus require little maintenance. Method of operation venturi consist out of three parts. Steam jet vacuum systems combine ejectors, condensers and interconnecting piping to provide relatively lowcost and lowmaintenance vacuum pumping. Ejector design software ejector sizing calculation. A steam jet ejector is illustrated below as ex ample steam serves as motive fluid to create vacuum.
When utilizing hp motive gas from existing sources, ejectors also called eductors or jet pumps have no running costs. Virtually maintenancefree with no moving parts, they can be fabricated from almost any material, and can be used in every industry that requires vacuum. 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. 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. Steam jet ejector water jet ejector vacuum jet ejectors. An additional use for the injector technology is in vacuum ejectors in continuous train braking systems, which were made compulsory in the uk by the regulation of railways act 1889. Ejector rack, an aircraft fitting for carrying bombs. Ejectors and steam jet ejectors document library graham.
This creates a vacuum in a vessel or chamber to which the ejectors is connected. Design, cfd analysis and performance evaluation of the steam jet. You can also get wet steam into an ejector and this will cause back firing on the ejector also putting material back into process. Steam jet ejector cooling powered by low grade waste or solar heat by adriaan jacobus meyer. Steam jet ejectors can be designed to pump liquids and even finely divided solids for pneumatic conveying systems. 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. The steam jet exhauster or vacuum pump is gas jet gas pump and is the basic stage for all high vacuum equipment. Steamjet ejector article about steamjet ejector by the. A study and analyze of an ejector in steam power plant. Rating is available when the video has been rented.
Such techniques are only suited to smallscale processes and equipment, and the use of vacuum is usually too exotic to consider. The steam jet blower is a steam jet or air jet air pump designed for large capacities at low drafts. Ejector or injector, a pumplike device without moving parts static mechanical equipment. Steam jet ejectors and associated equipment applied vacuum. Steam jet ejectors for the process industries robert b.
How an air ejector works in a boiler feed system steam. With increasing emphasis on stricter pollution control, their use was curtailed. The detailed operation of the steam ejector is further represented in the form of a literature study. Using a wealth of knowledge amassed over 35 years transvac. Steam jet ejectors were for many years the workhorse of the chemical process industries for producing vacuum. Steam jet ejectors and associated equipment home products steam jet ejectors and associated equipment. A steam injector is typically used to deliver cold water to a boiler against its own pressure, using its own live or exhaust steam, replacing any mechanical pump. Nash has been designing, manufacturing and troubleshooting steam jet air ejector systems since 1986. The function and fluid dynamics of a steam jet ejector is explained by means of a theoretical model found in literature. If the air were not removed from the system it could cause corrosion problems in the boiler. Pdf in this paper, the steam jet ejector was designed and then the cfd analysis was carried out for the geometry and the inlet condition data. I worked on a project before where a medical waste facility cooked the medical waste in a pressure vessel called an autoclave. In europe, an interesting equivalent to the water ejector is a centrifugal water jet ejector which combines a centrifugal pump with the.
Virtually maintenancefree with no moving parts, they can be fabricated from. From single stage ejectors to fully packaged multistage ejector systems all transvac products are custom designed to meet the clients. A vacuum ejector uses steam pressure to draw air out of the vacuum pipe and reservoirs of continuous train brake. When first developed, its operation was intriguing because it seemed paradoxical, almost like perpetual motion, but it was later explained using thermodynamics. A complete guide to getting the best from steam jet ejectors. 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 the speed of a fluid increases its pressure decreases and vice versa.
Based on the ejectorventuri principle, steam issuing through an expanding nozzle has its pressure energy converted to velocity energy. The application determines the design of the flow section. 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. In an increasing number of applications it is necessary to apply controls. Liquid jet ejectors can also pump liquids with good efficiencies as can steam jet ejectors. Ejector design software to do conceptual design and generate ejector sizes. Typical threestage steam jet ejector used in processing vegetable oils.
Steam ejector design chemical process engineering engtips. This create a vacuum in a vessels or chamber to which ejector is connected. After the cooking process the pressure inside the autoclave was around 3 bar. Steam jet ejectors are based on the ejector venturi principal and operate by passing motive steam through an expanding nozzle. The efficiency of the ejector cycle is very sensitive to the ejector efficiency. Steam is passed through a vacuum ejector of high efficiency to exhaust a separate, closed vessel which forms part of a cooling water circuit. Due to the pressure drop of the motive fluid, it will create a lowpressure zone before the mixing chamber. Very often, the motive fluid is steam and the device is called a steam jet ejector. The motive fluid for these type of water jet ejectors is water instead of steam. 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 at pressure pi expands through a nozzle and exits at very low pressure px and at very high velocity. Ejector working principle mechanical engineering site. The fluid jet range is a group of products, most of which operate on the ejector principle.
Basic ejector components are the steam chest, nozzle, suction, throat, diffuser and they discharge fig. An air ejector or steam ejector is a device which uses the motion of moving fluid motive fluid to transport another fluid suction fluid. It is has a wide range of application in steam ejector in boiler condenser, fresh water generator and in priming the centrifugal pump. The theory behind the steam jet ejector involves converting highpressure motive steam into a high velocity jet in a converging diverging nozzle. 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. Key design parameters the compression ratio of the injector, is defined as ratio of the injectorss.
Steam jet ejectors, the largest vacuum producing devices available are used in the most demanding of applications. The function depends, above all, on the design of the motive. The steam ejectors utilizes high pressure steam to compress low pressure vapours or gases. Steam jet ejectors are a simple alternative to mechanical pumps for vacuum raising applications. Review on ejector efficiencies in various ejector systems. They are especiallyeffectivein the chemicalindustry where an onsite supply of the highpressure motivegas is available. Depending on the specific application, an injector is commonly also called an eductor jet pump, a water eductor, a vacuum ejector, a steam jet ejector, or an aspirator. These systems operate on the ejectorventuri principle, which relies on the momentum of a highvelocity jet of steam to move air and other gases from a connecting pipe or vessel. Northvale korting fluid jet theory and applications of eductors by patrick belcher eductor basics. Steam, air or gas under pressure is used to pump, mix liquids and handle solids. The fundamental operation of an ejector is shown in the illustration. In the latter service, they are becoming widely used to transfer fluidized catalyst with ease and a minimum of loss. Jet ejectors are used to create vacuum, to compress gases, to convey liquids, to trans. The proper functioning of a steam jet ejector is depen.
Vacuum products steam jet ejectors by graham corporation. Pdf design, cfd analysis and performance evaluation of. This means that they use no moving parts and generally utilise a pressurised motive fluid such as water, steam or compressed air to drive and or mix media. In general, the melt in the ladle or some other vessel is placed in an evacuated chamber connected to a vacuum pump, or a ladle filled with molten steel is subjected to a lower pressure by a degassing chamber positioned above it and typically using steamjet ejectors. These power systems have found wide acceptance in modern plants because of the small space requirements, simplicity, reliability, low maintenance and quick starting characteristics. Transvac design and manufacture steam jet ejector systems in both standard and exotic materials. A steam jet ejector is illustrated below as example steam serves as motive fluid to create. Venturi fluid jets ejectors the fluid jet range is a group of products, most of which operate on the ejector principle. A jet ejector requires no mechanical drive and has no moving parts. Steam jetejectors offer a simple,reliable,low cost way to produce vacuum. Ejectors are essentially a fixed capacity device since the.
Steam jet ejectors the largest vacuum producing devices available are used in the most demanding of applications. 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 we can say venture. Key design parameters the compression ratio of the injector, is defined as ratio of the injectorss outlet pressure to the inlet pressure of the suction fluid. The proper functioning of a steam jet ejector is dependant on the following parameters. An ejector is based upon bernoullis principle which states. Because a steam jet ejector will operate with worn parts, operators sometimes delay the inconvenience and expense of replacing worn parts by increasing steam pressure to the ejector. Ezejector is a computer model for gas ejector and steam ejector design that has been developed based on a unique approach using fundamental principles. Steamjet vacuum systems combine ejectors, condensers and interconnecting piping to provide relatively lowcost and lowmaintenance vacuum pumping. These power systems have found wide acceptance in modern plants because of the small space requirements, simplicity, reliability, low maintenance and quick starting. In europe, an interesting equivalent to the water ejector is a centrifugal water jet ejector which combines a centrifugal pump with the ejector principle and which recirculates the motive water han. The design and performance of steam ejectors for applications in jetpump refrigerators. Four, five and sixstage steam jet ejector principle of operation. Pdf design, cfd analysis and performance evaluation of the.
The steam ejector utilizes high pressure steam to compress low pressure vapors or gases. Depending on the specific application, an injector is commonly also called an eductorjet pump, a water eductor, a vacuum ejector, a steamjet ejector, or an aspirator. There are still many applications, however, such as those with large capacity requirements, where ejectors. Normal range for a water jet ejector is from atmosphere to 45 mm hg abs depending upon the water temperature.
If discharge side of ejector is blocked in and steam is not the steam is going to path of least resistance, back to process. 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. Steam jet ejectors for the process industries mcgrawhill. The motive steam enters the ejector through the motive fluid nozzle and is expanded into the mixing diffuser converting pressure energy into velocity energy. Efficiencies of each step within the ejector based on. Pdf the design and performance of steam ejectors for. The model gives the entrainment ratio as a function of the expansion. Figure 2 illustrates the principle of operation of an ejector based heat pump system. The result is a low priced and efficient vacuum pumping system.
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