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