Liquid jet pump
They can operate with either incompressible or compressible fluids as the primary driving and secondary driven flows. The figure also defines the subscripts used later for primary 1secondary 2etc. The primary fluid is passed through a nozzle where the pressure energy is converted into kinetic energy. The high-velocity jet entrains the secondary fluid. The two streams mix in the mixing tube, leading to pressure recovery.
Further static pressure is recovered in a narrow-angle diffuser downstream of the mixing tube. Ejectors are generally inefficient devices.
However, their simplicity and lack of moving liquid jet pump make them worthy of consideration, particularly where liquid jet pump high-pressure stream of fluid is already available. The loss coefficients K pK sK m and K d account for losses in the primary nozzle, secondary flow inlet, mixing chamber and diffuser, respectively. The equation can be solved directly for N if C, M and R are known. Alternatively, either graphical e. For a particular application i. For a well-designed nozzle, a value of 0.
Entry to the mixing tube needs to avoid large secondary flow losses: A mixing tube length of mixing tube diameters is recommended. To reduce downstream pressure losses, the flow needs to be expanded downstream of the mixing tube to lessen flow velocities to a reasonable level. When operating at low suction pressures and high flow ratios, cavitation can prove to be a problem with jet pumps. Liquid jet pump information is available in Cunningham et al.
For small pressure differences, gas-gas ejectors can be treated like liquid jet pumps. However, for higher pressure ratios, liquid jet pump effects need to be taken into account. Above a critical pressure ratio between primary and secondary around 1. Flow in the nozzle becomes independent liquid jet pump secondary pressure, and is given by. See Critical FlowJets and Nozzles. Downstream of the nozzle, flow will expand in a series of supersonic shocks until the pressures of both streams become equal and mixing occurs.
In some ejector designs, a converging-diverging nozzle is utilized to accomodate the expanding jet. An 'on-design' condition can be defined where the static pressures of primary and secondary flows are equal at the nozzle exit. However, work by Ashton, Green and Reade suggests that the use of a diverging section is not necessary for effective operation, at least at moderate pressure ratios.
Performance can be then calculated by considering conservation of mass, momentum and energy in the mixing tube and diffuser. Owing to the complexity of the equations, these cannot be solved directly.
A complex graphical liquid jet pump is available in ESDU As with a jet pump, the key geometric factor in the design is the mixing tube diameter. Performance increases by reducing mixing tube diameter up to a point where the expanding supersonic primary jet almost fills the mixing tube before mixing can take place and choking occurs.
A further decrease in mixing tube diameter or any attempt to increase secondary flow liquid jet pump performance to decrease rapidly. Design requirements for the nozzle, mixing tube and diffuser are similar to those for jet pumps.
These ejectors utilize liquid as the primary fluid: Performance can be generally characterized by an equation of the form. An expression for V Lmin has been derived by Henzlergiven by:. Given the different liquid jet pump of the two streams, mixing duty tends to be more arduous than in a single-phase ejector, and generally longer mixing tubes than those for single-phase ejectors are used typically diameters. However, where mixing does occur, this is very intensive the 'mixing shock'.
This tends to result in significant energy losses. A spinner upstream of the primary nozzle is sometimes used to help disintegrate the jet and induce early mixing. Gas-liquid ejectors can be very effective devices for mass transfer applications. They can be used either as stand-alone devices, or in combination with a contact vessel. They have the combined benefits of being able to draw in gas without the need for liquid jet pump, and providing a very fine dispersion in the mixing tube.
This leads to mass transfer liquid jet pump typically orders of magnitude greater than a typical stirred tank, making them particularly suited to absorption with rapid, competing chemical reactions where fast mixing is required to reduce liquid jet pump formation. Where longer residence time is required, ejectors are often combined with a contact vessel.
In such cases, the ejector provides rapid initial mixing, a fine bubble dispersion and, if properly designed, good liquid mixing liquid jet pump the vessel. Gas can either be recycled, by using the suction characteristics of the ejector to draw gas back from the liquid jet pump of the vessel, or operated in once-through mode.
The 'Buss Reactor,' successfully used for hydroginations, liquid jet pump, animations, etc. Society of Petroleum Engineers. ESDU Ejectors and jet pumps.
Design for liquid jet pump air flow. Engineering Sciences Data Unit. Design and performance for incompressible liquid flow. Summary of ejector applications. Ejectors for Mass Transfer.
Jet Pumps for pumping use a liquid as the operating medium. NCI jet eductors also known as jet pumps, utilize the kinetic energy of one liquid to cause the flow of another.
This involves liquid jet pump a high pressure motive stream and accelerating it through a tapered nozzle to increase the velocity of the fluid gas or liquid that is put through the nozzle. This fluid is then carried on through a secondary chamber where the friction between the molecules of it and a secondary fluid generally referred to as the suction fluid causes this fluid to be pumped.
These fluids are intimately mixed together and discharged from the jet pump. NCI uniquely has more than 50 years of experience with jet pumps and in tank mixing applications. Put your trust into the Northeast Controls jet pumps group for a job done right the first time. This connection is where the power for the eductor is generated, by increasing the velocity of the motive fluid. The eductor nozzle in this section takes advantage liquid jet pump the physical properties of the motive fluid.
Eductors with liquid motives use a converging nozzle as liquids are not generally compressible. Eductors with gas motives utilize converging-diverging nozzles to achieve maximum benefit from the compressibility of the gas.
All nozzles for eductors have smooth flow paths. Liquid jet pump paths with sudden steps or roughness on these high velocity surfaces cause jet pumps to operate less efficiently. This connection of the eductor is where the pumping action of the eductor takes place.
The motive fluid passes through the suction chamber, entraining the suction fluid as it passes. The friction between the fluids causes the chamber liquid jet pump be evacuated. This allows liquid jet pump in the suction vessel to push additional fluid liquid jet pump the suction connection of the jet pump.
The high velocity of the motive stream in this section of the eductor directs the combined fluids toward the liquid jet pump section liquid jet pump the eductor. As the motive fluid entrains the suction fluid, part of the kinetic energy of the motive fluid is imparted to the suction fluid.
This allows the resulting mixture to discharge at an intermediate pressure. The percentage of the motive pressure that can be recovered is dependent upon the ratio of motive flow to suction flow and the amount of suction pressure pulled on the suction port.
The mixture then passes through the diverging taper that converts the kinetic energy back to pressure. The combined fluid then leaves the outlet. Total customer satisfaction comes from the combination of quality products purchased at a reasonable price and delivery quickly and when promised.
Liquid Jet Eductors use the kinetic energy of a motive liquid to entrain another liquid, completely mix the two, and then discharge the mixture against a counter pressure and are used in large numbers throughout industry for pumping and mixing operations. Applications are so numerous, it is impossible to note all of them.
General uses include lifting, pumping, mixing, and agitating of liquids as well as handling granular solids and slurries. Some of the typical applications can be seen below:.
Liquid jet eductors consist of three basic components, namely a converging nozzle, a diffuser or venturiand a body to hold these parts in their relative positions and to provide a suction or mixing chamber. In addition, they can liquid jet pump equipped with accessories such as regulating spindles, snap valves and floats to control operation. When designing eductors experience is all-important to correctly design the nozzle, diffuser, and body and their relative positions as they are all highly critical and vary according to the physical properties of the liquids being handled.
As an example of eductor performance in a typical use, a 1. Liquid jet eductors are manufactured in a variety of types and sizes as well as materials, liquid jet pump standard Type and ranges from 0.
Variables such as pressure, temperature, density, required entrainment rates, and operating conditions must all be considered liquid jet pump determining the correct liquid jet pump and size of eductor to best suit to your requirements. The Sand and Mud Eductors are recommended for use in pumping out wells, bore holes, pits, tanks, sumps and similar liquid jet pump where there is an accumulation of sand, mud, slime or other material of a nature not easily handled by the standard eductors.
The Sand and Mud Eductor differ from standard eductors as they have an open suction port which is designed to be submerged in the material being handled, this allows the eductor to entrain relatively large solids and liquid jet pump that would otherwise block liquid jet pump conventional eductor. Another feature of this unit are the agitating jets installed at the base of the eductor, these nozzles help to stir the material surrounding the eductor and make it fluid.
This effectively means the eductor can be left buried in mud or slurry, and when operated it will begin to excavate the surrounding solids and begin pumping. Sizes are available in 1 Inch through to 6 Inch, with sizes up to 4 Inch supplied with screwed connections as standard, for sizes above 4 Inch connections are flanged are usually supplied.
Typical materials of construction are Cast Iron, Carbon Steel, Stainless Steel and Bronze, however other materials are available on request. A few of the primary applications where eductors are used can be seen below, this liquid jet pump is by no means exhaustive as their uses are numerous. Water jet eductors are often used to empty tanks or to pump out sumps, bunds and cellars. The motive line should be fitted with a regulating valve and a pressure gauge while the suction line should be fitted with an strainer or mesh to prevent large particles entering the unit and causing blockages.
Care should also be taken to ensure the discharge lines are always sealed to prevent air leaking back towards the eductor. To accomplish this either fit a U-bend to the discharge line, or always keep the open end of the discharge pipe submerged as this will allow stable and rapid entrainment of the suction liquid. Where possible it is recommended that the eductor be liquid jet pump a short distance above the liquid to be entrained and that short suction lines be used, however eductors will operate equally well with long suction lines.
Care should be taken with suction lifts greater than 4. This diagram above shows an Eductor being used to introduce an additive into boiler feed water. A percentage of the water flowing from the pump is bypassed into the eductor where it acts as the motive force to draw in and entrain the additive. This is the preferred method of introducing additives as it does not reduce pressure in the main line downstream of the pump, and also allows the eductor to be kept to a much more economical size.
Some of the typical applications can be seen below: Draining flooded cellars, Emptying tanks and sumps or bunds, Pumping and mixing operations in oil treating systems De-watering sand and coal barges, Introducing anti-knock fluids and colouring matter into gasoline Continuous blending, Acidifying, Liquid jet pump of oils, Mixing drilling mud, Producing emulsions Pumping food products, Pumping sand and filter clay or activated carbon Tank mixing, and various Proportioning operations Liquid jet eductors consist of three basic components, namely a converging nozzle, a diffuser or venturiliquid jet pump a body to hold these parts in their relative positions and to provide a suction or mixing chamber.
Low Cost - Units are small in relation to the work they do and cost is correspondingly low. Self Priming - Eductors are self-priming. They operate equally well in continuous or intermittent service. No Moving Parts - Eductors are exceedingly simple and reliable. There liquid jet pump no moving parts to wear or break in a basic eductor. Even when equipped with accessories such as regulating spindles, snap valves, float mechanisms, they require little attention, only periodic inspection and maintenance.
Corrosion and Erosion Resistant - Because they can be made of practically any workable material, or coated with corrosion-resistant materials, eductors can be made highly resistant to the actions of the liquids handled or the environment in which located. Safe - Eductors can be used in hazardous locations where electrically operated alternates would require explosion proofing at considerable cost. Versatile - Various piping arrangements permit adapting to liquid jet pump conditions.
Eductors of various types can handle granular solids, liquid jet pump, and slurries without contamination. Automatically Controlled - Units can be adapted for automatic control by means of a pressure liquid regulating spindle or a snap-valve and float arrangement.
Perform Double Duty - Eductors mix motive and suction liquids intimately while pumping against a counter pressure. Easy to Install - Connections can be made to suit your piping requirements. Little space is required to accommodate units and they are liquid jet pump so light in weight they can be supported by the piping to which they are attached. Sand and Mud Eductors The Sand and Mud Liquid jet pump are recommended for use in pumping out wells, bore holes, pits, tanks, sumps and similar containers where there is an accumulation of sand, mud, slime or other material of a nature not easily handled by the standard eductors.
Typical Eductor Applications A few of the primary applications where eductors are used can be seen below, this list is by no means exhaustive as their uses are numerous.
Pumping Additives in to Liquids This diagram above shows an Eductor being used to introduce an additive into boiler feed water.