What is an ejector?: principle of operation and device of the ejector pump
What is an ejector?? This question often arises among the owners of country houses and cottages in the process of setting up an autonomous water supply system. The source of water entering such a system, usually, there is a pre-drilled well or well, the liquid from which must not only be raised to the surface, but also transport by pipeline. A whole technical complex is used to solve such tasks, consisting of a pump, set of sensors, filters and water ejector, established in that case, if the liquid from the source must be pumped from the depth, exceeding ten meters.
Water jet ejector with flange connections
In what cases is an ejector needed?
Before dealing with the question of, what is an ejector, should be clarified, what is a pumping station for?, equipped with them. Essentially, ejector (or an ejector pump) is a device, in which the energy of motion of one medium, which moves at high speed, transmitted to another environment. So, in the ejector pumping station, the principle of operation is based on Bernoulli's law: if a reduced pressure of one medium is created in the narrowed section of the pipeline, this will cause suction into the formed other flow of the medium and its transfer from the place of suction.
Everyone knows it well: the greater the depth of the source, the more difficult it is to raise water from it to the surface. Usually, if the depth of the source is more than seven meters, then an ordinary surface pump can hardly perform its functions. Of course, to solve such a problem, a more powerful pump can be used, but it is better to go the other way and purchase an ejector for a surface-type pumping station, significantly improving the characteristics of the used equipment.
External ejector, prepared for immersion in the well
Due to the use of a pumping station with an ejector, the pressure of the liquid in the main pipeline increases, at the same time, the energy of the fast flow of the liquid medium is used, flowing along its separate branch. Ejectors, usually, work in a set with water-jet type pumps, liquid mercury, steam and steam oil.
The ejector for the pumping station is especially relevant in that case, if it is necessary to increase the capacity of an already installed or planned station with a surface pump. In such cases, the ejector unit allows you to increase the depth of water intake from the tank to 20-40 meters.
Inspection and operation of a pumping station with an external ejector
Types of ejector devices
According to their design and principle of operation, ejector pumps can belong to one of the following categories.
Steam
With the help of such ejector devices, gaseous media are pumped out of closed spaces, and the rarefied state of the air is also maintained. Devices working on this principle have a wide range of applications.
Steam ejector for turbine with oil cooler
Steam jet
In such devices, the energy of a steam jet is used to suck gaseous or liquid media from a closed space. The principle of operation of this type of ejector is as follows, that par, which flies out of the installation nozzle at high speed, captures the transported environment, exits through the ring canal, located around the nozzle. Ejector pumping stations of this type are mainly used for quick pumping of water from the premises of vessels of various purposes.
Installation of water heating using a steam jet ejector
Gas
Stations with an ejector of this type, the principle of action of which is based on that, that the pressure of the gas medium, is initially under low pressure, occurs due to high-pressure gases, used in the gas industry. The described process takes place in the mixing chamber, from where the medium flow is sent to the diffuser, where its inhibition occurs, so, increasing pressure.
Air (gaseous) ejector for chemical, energy, gas and other industries
Design features and principle of operation
The design elements of the remote ejector for the pump are::
- camera, into which the pumped medium is sucked;
- mixing unit;
- diffuser;
- nozzle, the cross section of which is narrowing.
Remote ejector device
How any ejector works? As mentioned above, such a device functions according to the Bernoulli principle: if the velocity of the flow of liquid or gas medium increases, then an area is formed around it, characterized by low pressure, which contributes to the rarefaction effect.
If the shape of the pipe and the flow rate are chosen correctly, then the lead, located in the narrowed part, air or liquid will be sucked in
so, the principle of operation of the pumping station, equipped with an ejector device, is as follows:
- Liquid medium, which is pumped by the ejector unit, enters the latter through a nozzle, whose cross-section is smaller, than the diameter of the main entrance.
- Passing into the mixer chamber through a nozzle with a decreasing diameter, the flow of the liquid medium acquires a noticeable acceleration, which contributes to the formation of a region with reduced pressure in such a chamber.
- Due to the rarefaction effect in the ejector mixer, the liquid medium is sucked into the chamber, which is under higher pressure.
If you decide to equip the pumping station with such a device, as an ejector, keep in mind, the pumped liquid medium does not come from a well or a well, and from the pump. The ejector itself is located in this way, so that part of the liquid, which was pumped from a well or well using a pump, returned to the mixer chamber is narrowed through the nozzle. Kinetic energy of liquid flow, which enters the ejector mixer chamber through the nozzle, transferred to the mass of the liquid medium, suction pump from a well or well, thereby ensuring constant acceleration of its movement along the input highway. Part of the fluid flow, which is pumped out by a pumping station with an ejector, enters the recirculation pipe, and the rest - in the water supply system served by such a station.
Connecting pumps with an external ejector
Dealing with that, how the pumping station works, equipped with an ejector, you will understand, that she needs less energy for that, to raise the water to the surface and transport it through the pipeline. So, not only the efficiency of using pumping equipment increases, but the depth also increases, with which the liquid medium can be pumped out. in addition, when using the ejector, suction liquid independently, the pump is protected against idling.
The device of the pumping station with an ejector assumes the presence of a crane in its equipment, installed on the recirculation pipe. With the help of such a crane, which regulates the flow of liquid, which enters the ejector nozzle, you can control the operation of this device.
Types of ejectors by installation location
Buying an ejector to equip a pumping station, keep in mind, that such a device can be built-in or external. The device and principle of operation of the ejectors of these two types are practically the same, the differences are only in the place of their installation. Built-in type ejectors can be placed inside the pump housing, or be mounted in the immediate vicinity of it. The built-in ejection pump has a number of advantages, which should include:
- minimum space, required for installation;
- good protection of the ejector from contamination;
- no need to install additional filters, that protect the ejector from insoluble inclusions, contained in the pumped liquid.
Centrifugal pump with built-in ejector
Meanwhile, it should be kept in mind, that the built-in type ejectors demonstrate high efficiency in that case, if they are used to pump water from sources of shallow depth - to 10 meters. Another significant disadvantage of pumping stations with built-in type ejectors is that, that they make quite a lot of noise during their work, therefore, it is recommended to place them in a separate room or in the caisson of a water-bearing well. It should also be borne in mind, that the ejector device of this type involves the use of a more powerful electric motor, which activates the pumping unit itself.
Portable (or external) ejector, as its name suggests, installed at a certain distance from the pump, moreover, it can be quite large and reach up to fifty meters. Portable type ejectors, usually, placed directly in the well and connected to the system using a recirculation pipe. A pumping station with a remote ejector also requires the use of a separate storage tank. This tank is necessary for that, to ensure the constant availability of water for recirculation. The presence of such a tank, in addition, allows to reduce the load, which accounts for a pump with a remote ejector, and reduce the amount of energy, necessary for its functioning.
Pump with external ejector
The use of removable type ejectors, the efficiency of which is somewhat lower, than in built-in devices, which allows pumping of liquid medium from wells of considerable depth. in addition, if you make a pumping station with an external ejector, then it can be placed in the immediate vicinity of the well, and mount at a distance from the source of water intake, which can be from 20 to 40 meters. This is important, that the location of the pumping equipment at such a significant distance from the well will not affect its efficiency.
Production of the ejector and its connection to the pumping equipment
Having figured it out, what is an ejector and having studied the principle of its action, you will understand, that you can make this simple device with your own hands. Why make an ejector with your own hands, if it can be purchased without any particular problems? It's all about saving. Find the drawing, according to which you can make such a device yourself, does not present any particular problems, and for its manufacture you will not need expensive consumables and complex equipment.
How to make an ejector and connect it to the pump? For this purpose, you need to prepare the following components:
- tee with female thread;
- Union;
- couplings, knees and other fitting elements.
Components for a home-made ejector
The ejector is manufactured according to the following algorithm.
- A fitting is screwed into the lower part of the tee, and do so, so that the narrow nozzle of the latter is inside the tee, but at the same time did not speak from his reverse side. The distance from the end of the narrow nozzle of the fitting to the upper end of the tee should be about two to three millimeters. If the fitting is too long, then the end of its narrow nozzle is ground, if short, then build up with the help of a polymer tube.
- In the upper part of the tee, which will be connected to the suction line of the pump, screw in the adapter with an external thread.
- A branch in the form of a corner is screwed into the lower part of the tee with an already installed fitting, which will be connected to the recirculation pipe of the ejector.
- A branch in the form of a corner is also screwed into the side branch of the tee, to which the pipe is connected using a collet clamp, which supplies water from a well.
Self-made ejector assembly
All threaded connections, which are performed during the manufacture of a home-made ejector, must be airtight, which is ensured by the use of FUM tape. On the pipe, along which water will be taken from the source, a non-return valve and a strainer should be placed, which will protect the ejector from clogging. As pipes, with the help of which the ejector will be connected to the pump and storage tank, ensures recirculation of water in the system, you can choose metal-plastic products, and from polyethylene. In the second option, non-clamps are required for installation, and special crimping elements.
After all the necessary connections are made, a home-made ejector is placed in the well, and the entire pipeline system is filled with water. Only after that, you can start the pumping station for the first time.
