The thermocompressor is a steam jet steam compressor, shown with a diaphragmoperated spindle for control purposes. Inlet the port by which gas to be pumped enters a pump, also. Steam jet compressors, jet pump, thermocompressor, ejector. Process design of vacuum equipment vacuum pumps and steam jet ejectors project standards and specifications page 6 of 36 rev. This reduces the size and steam consumption of the succeeding stages and results in a reprinted from petroleum refiner, december 1958 1 ejectors ejectors are simple pieces of. The basic operating principle of an ejector is to convert the pressure into speed. Mechanism of these products are devised in a way that water can be used for creating vacuum with pressure, ranging from 3240 mm hg.
Steam jet ejectors, the largest vacuum producing devices available are used in the most demanding of applications. An ejector s individual compression ratio is a function of coolingwater temperature, steam use and condensation profile of hydrocarbons handled. In operation, steam issuing through an expanding nozzle has its pressure energy converted to velocity energy. The mass of highvelocity steam is discharged from the nozzle in a directed flow through an air chamber and into a convergentdivergent. The fundamental operation of an ejector is shown in the illustration. Technology and applications gea engineering for a better. Ejector modeling and examining of possibility of replacing. Steam jet ejectors steam jet ejectors are based on the ejectorventuri principal and operate by passing motive steam through an expanding nozzle. The many uses of ejectors are also described ejectors are everywhere.
A transvac ejector venturi, eductor, jet pump operation is based upon bernoullis principle which states. 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. Steam ejector design chemical process engineering engtips. Ejectors also known as jet ejectors fit the definition of pumps and compressors section 2. Multistage, steam jet vacuum systems, surface condenser. The gas that is to be induced into the suction chamber can be any fluid that is compatible with the steam and the components materials of construction. The result is a supersonic speed out of the nozzle. 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 are typically furnished in cast iron or steel with a nozzle of stainless steel. The principal application of ejectors in the food industry is their use for drawing a vacuum and for thermal vapor recompression in.
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. During the operation, the motive steam passes through the steam chest and enters the nozzle, where its pressure decreases but its speed increases. Due to the pressure drop of the motive fluid, it will create a lowpressure zone before the mixing chamber. The overall compression ratio required is approximately 55. For high compression ratios a long narrow diffuser is used, and for low compression ratios a shorter, wider design. Entrapment capture vacuum pump a vacuum pump in which the molecules are retained by sorption or condensation on internal surfaces.
S a k jeelani,k v kasipathi rao, g r balasubramanian designing steam jet ejectors chemical engineering april 9 1979 7. Sep 14, 2016 since 1936 graham corporation has been supporting our customers around the globe with heat exchangers, water heaters, steam surface condensers, steam jet ejectors steam vacuums, refrigeration. 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 steam jet refrigeration system also known as ejector system refrigeration system is one of the oldest methods of producing refrigeration effect. Steam jet compressors are part of many process engineering applications. Heat exchange institute standards for steam jet ejectors describes the method to convert the mixture air, water vapor, and.
In practice, for suction pressure below 100 mbar absolute, more than one ejector is used, usually with condensers between the ejector stages. Steam jet ejectors are based on the ejector venturi principle. The motive steam enters the ejector through the motive fluid nozzle and is expanded into the mixing diffuser converting pressure energy into velocity energy. The steam entrains the suction gases and the mixture.
Pumps of the ejector type are small in relation to the work they do and their cost is low in. It is one of the types of air ejector which is used in the steam like near the condenser to remove the non condensable gases and some vapour entering into main condenser by an air ejector and it is cooled by the main condensate and released in the ejector condenser. Virtually maintenancefree with no moving parts, they can be fabricated from. Operating principle the ejector consists of four main components. Review on ejector efficiencies in various ejector systems. Ts diagram of the steam ejector refrigeration and heat pump cycle. Since 1936 graham corporation has been supporting our customers around the globe with heat exchangers, water heaters, steam surface condensers, steam jet ejectors steam. The energy required to increase the pressure head of a fluid is provided by another fluid motive fluid moving at high velocity. In operation, steam issuing through an expanding nozzle has its pressure energy converted to. Figure 2 illustrates the principle of operation of an ejector based heat pump system. Two stage vacuum ejectors generally cover vacuum ranges between 3mm hga to mm hga, however depending up on actual operating conditions a. 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. Graham corporation ejector troubleshooting youtube.
The ejectors form an integral part of distillation columns, condensers and other heat exchange processes. A study and analyze of an ejector in steam power plant. The two major functions of ejectors are as follows. Ejector thermocompressor equirepsa vaccum production. Steam ejector systems for the process industries edwards vacuum. Staging of ejectors is required for more economical operation when the required absolute vacuum level is reduced.
This occurs by an adiabatic expansion of motive steam through a convergentdivergent nozzle from the motive pressure to suction pressure. Working principle of a steam jet pump and the pressure differences over the flow path 1 head 2 motive nozzle 3 inlet cone. They require almost no maintenance for long periods. In this example two jet ejector stages are connected in series to achieve a suction pressure of 1 mbar with a minimum of motive medium.
Steam at pressure pi expands through a nozzle and exits at very low pressure px and at very high velocity. Steam ejectors handle high volumes of gasses, including wet, corrosive, or particulateladen vapors. The steam ejectors utilizes high pressure steam to compress low pressure vapours or gases. Also known as thermocompressors or vapour compressors, steam jet compressors compress steam flows in various processes in a simple way. 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. This is actually a combination of an air jet ejector and a vacuum pump. Korting jet pumps and ejectors enjoy a reputation of being particularly straightforward and robust in their functioning as well as being low in maintenance and wear. The exhaust from the ejectors is invariably directed to the smokebox, by which means it assists the blower in draughting the fire. Design and thermodynamic analysis of a steam ejector. The steam ejector is a simple device consisting of three basic components, a motive steam nozzle, a suction chamber and a mixing diffuser. The ejector design has basic advantages such as absence of moving parts and simplicity of operation. If you can then use the typical steam jet ejector, the second article tells points to.
Steam jet ejectors offer a simple, reliable, lowcost way to produce vacuum. Ejectors can be divided into two categories based on the type of performance. In order to become fully versed in the essential elements that make up a steam jet ejector, the principle of operation will be considered first. In a steamjet ejector, the suction chamber is connected to the vessel or pipeline that is to be evacuated under vacuum. Steam ejectors can also be combined with liquid ring vacuum pumps to create a hybrid capable of deep vacuum that ejectors can deliver but with lower energy use. Product catalog gea engineering for a better world. In this article, we will see the ejector working principle. 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 suction flow is compressed to a higher pressure. Steam is passed through a vacuum ejector of high efficiency to exhaust a separate, closed vessel which forms part of a cooling water circuit.
The fundamental principles of the steam ejector sage journals. Ejectors will handle highly corrosive vapours and fluids. The motive steam enters the ejector through the motive fluid nozzle and is expanded into the. Ejectors can be installed indoors or outdoors without restriction. This reduces the size and steam consumption of the succeeding stages and results in a reprinted from petroleum refiner, december 1958 1 ejectors ejectors are simple pieces of equipment. Where the steam from the ejector is discharged into a hotwell, the discharge line should not be submerged more than 12 and preferably not more than 68.
Multi stage steam ejectors multi stage gas ejectors also. The steam or air converts that pressure or potential energy to velocity or kinetic energy. Very often, the motive fluid is steam and the device is called a steam jet ejector. Steamjet ejectors for vacuum duty or vapor recompression represent only one area of ejector application. 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. It would be better if you can get hold of the standard. Steam jet air ejectors have a low initial cost, so are an economical means and reliable equipment for producing a vacuum. The steam nozzle discharges a highvelocity jet across the suction chamber. Steamjet vacuum systems combine ejectors, condensers and interconnecting piping to provide relatively lowcost and lowmaintenance vacuum pumping. In this study, semiempirical models are developed for design and rating of steam jet. As a first estimate, a five stage ejector is assumed. Steam jet ejectors are based on the ejectorventuri principle. Corrosion erosion resistant as ejectors can be constructed from various materials so as to handle even corrosive fluids.
An ejector performance curve gives the expected suction pressure as a function of watervapor equivalent loading fig. However, for higher pressure ratios, compressibility effects need to be taken into account. If the difference in elevation between the ejector discharge and the hotwell water level is less than 34 feet, the discharge line should have a. May, 2015 a transvac ejector venturi, eductor, jet pump operation is based upon bernoullis principle which states. These power systems have found wide acceptance in modern plants because of the small space requirements, simplicity, reliability, low maintenance and quick starting characteristics. Ezejector now offers a program for design of multi stage steam ejectors. This creates a vacuum in a vessel or chamber to which the ejectors is connected. In a vacuum jet ejector, the lowpressure vent steam is the motive energy. They are designed in a multitude of materials and optimised for. Steam jet ejectors operating principles steam jet ejectors operate on a massvelocity principle. In a jet or ejector, a relatively highpressure gas, like steam or air, expands through a nozzle. In a steamjet ejector, the suction chamber is connected to the vessel or pipeline that.
Working principle of steam ejector power plant tutorials. Singlestage steam jet ejector principle of operation. Ejector design software ejector sizing calculation. Ejector design software ejector sizing calculation ezejector. Can be fabricated in any materials of construction. When the speed of a fluid increases its pressure decreases and vice versa. The model makes use of the field data collected over 35 years by power 1994 for vapor entrainment and compression ratios of steam jet ejectors. Hence low maintenance cost when to compare with other peer equipment. The steam jet ejector is modeled by the semiempirical model developed by eldessouky 1997. Ejector systems watersteam jet vacuum ejector manufacturer. Abstract steam jet ejectors are an essential part in refrigeration and air conditioning, desalination, petroleum refining, petrochemical and chemical industries.
Producing a vacuum with steam jet ejectors in a vacuum jet ejector, the lowpressure vent steam is the motive energy source. The basic components of this system are an evaporator, a compressor device, a condenser and a refrigerant control device. The propelling steam expands through a divergent nozzle, converting its pressure energy into velocity energy. Steam jet vacuum systems combine ejectors, condensers and interconnecting piping to provide relatively lowcost and lowmaintenance vacuum pumping. In multistage ejectors, it is usually advantageous to condense the steam from each stage in a watercooled intercondenser so as to reduce the load to the succeeding stage. Can operate safely under the most hazardous conditions. 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. 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. Understanding ejector systems necessary to troubleshoot.
Air ejector theory learn how and air ejector works. A2a praveen, steam jet ejectors are steam driven devices that suck air and other undissolved gases from the condenser and build up vacuum. A jet pump works without a mechanical drive and therefore offers high reliability in continuous operation mode. Because operating conditions may change during the operating life of the geothermal power plant, the motive steam nozzles for steam jet ejectors should be replaceable. Jet pumps, also referred to as ejectors, are devices for the conveyance, compression or mixing of gases, vapors, liquids or solids in which a gaseous or liquid medium serves as the motive force. The blog includes discussions of ejector efficiency and multi stage ejectors for vacuum systems. First, equal steam flow rate is assumed to each stage. Designing air jet ejectors chemical engineering september 25 1976 p5 6. Chem process has a full fledged test facility to simulate actual.
The familiar water jet pump found in chemistry laboratories is, in essence, an ejector that uses water as the motive fluid. Ejectors are remarkably simple yet extremely useful devices. Pumps of the ejector type are small in relation to the work they do and their cost is low in comparison with other types of equipment. Steam jet vacuum ejectors remove gases andor vapours from process operations thereby generating a vacuum in the reactor. Steam ejectors operate in rough or medium vacuum range 7600. The figure on the right illustrates a 3stage system. Basic ejector components are the steam chest, nozzle, suction, throat, diffuser and they discharge fig.
The principal advantages of steam jet ejectors over other types of vacuum producing units are. Multistage steam jet ejectors stage steam jet ejector. Graham corporation ejector efficient operation youtube. Steam jet ejectors at geothermal steam plants are typically fabricated from type 316l stainless steel to resist corrosion from the noncondensable gas and steam mixture. Basic components of a steam jet ejector a single stage steam ejector can produce only a limited vacuum cfr. The vacuum pump is designed and selected to operate at optimum interstage pressure. The ratio of discharge pressure to suction pressure is the ejector compression ratio. For small pressure differences, gasgas ejectors can be treated like liquid jet pumps. 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. Nash is globally recognized for assembling the most efficient steam jet and air ejectors and ejector vacuum systems.
Using them reduces the energy consumption of the process and cuts the machinerys operational costs sustainably. Single and multistage steam jet ejectors scam technology. After the cooking process the pressure inside the autoclave was around 3 bar. Both the motive vent steam and the suction vaporsgases pass through a venturi throat and are released through a diffuser. Air andor water vapor are sucked from the process into the mixing chamber at nearvacuum conditions. Condensing of motive steam greatly improves ejector set efficiency. They operate by the con version of pressure energy into velocity in suitable. Since at least 5000 pounds per hour is reduced in the amount of steam consumed of ejectors total of all three stages, the maximum ratio of return on investment roi and the mini mum initial investment will be needed. Above a critical pressure ratio between primary and secondary around 1. Ejectors can be operated with many different motive fluids. Calculation of a required motive nozzle throat diameter is based on the necessary amount of motive steam, its pressure and specific volume.
Liquid jet ejectors steam jet liquid jet ejector combination systems steam jet vacuum pump combination systems pressure which may be selected between 814 mbar. They are especially effective in the chemical industry where an onsite supply of. Ejectors and steam jet ejectors document library graham. The compression ratio, cr, is the pressure ratio of the compressed and entrained vapors. Ejector working principle mechanical engineering site. The new standard now integrates the previous three separate standards on steam jet ejectors.
Steam ejectors use steam or gas instead of moving parts to compress a gas. These units have no moving parts to adjust or repair. Technology and applications steam jet vacuum pumps. Programs are available for steam ejectors where steam is the motive fluid, gas ejectors where gas is the motive fluid, liquid ejectors and gas subsonic ejectors where gas. Steam jet electors function on the principle of a nozzle and a convergent divergent section. Due to the broad range of applications for steam jet vacuum equipment, the units are frequently specified in special alloys and plastics.
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