An ejector is a device within which kinetic energy is transferred from input to output, increasing the output speed. The ejector is designed in such a way that it works according to Bernoulli's law and in most cases is intended for jet pumps. This device is designed to modernize the water supply system when supplying water from great depths.
Why are ejectors needed and what are they?
For many homeowners, organizing an autonomous water supply becomes a problem due to the large depth of the pit.
Already from the eight-meter mark problems begin. For pumping stations with ejectors, the same possibilities as for high-capacity pumps. The use of deep sources requires the use of powerful submersible pumps, which are expensive.
What are ejectors used for? So as not to waste money on expensive models. The use of inexpensive pumping stations with ejectors can solve the problem with the same efficiency. At the same time, modernization costs are minimal. Moreover, you can improve the system using a local method or purchase a complex that was originally designed for this.
Principle of operation
All ejectors for pumping stations operate according to the same scheme. The basis is Bernoulli's principle. In accordance with it, if the flow is accelerated, then a rarefaction zone is formed in the zone in front of the acceleration point. The pressure in it is lower, which causes a retracting effect. If you add it to the flow generated by the pumping station, then the result of such modernization is an increase in productivity.
Device
Whatever type of device is considered, the ejector pump consists of:
- suction compartment;
- mixing cavity;
- diffuser;
- tapering pipe.
The principle of operation is that liquid is ejected from the nozzle (pipe) at high speed. The outflow of water provokes the appearance of low pressure inside the working chamber, which draws in liquid. The cycle is repeated continuously, which allows maintaining constant pressure in the pipeline.
Local ventilation
Almost every enterprise has areas or workshops where hazardous production is organized. In order to prevent the spread of harmful substances throughout the enterprise, this type of ventilation is provided. It removes toxic substances immediately from the place where they are formed.
The local system can be of several varieties:
- Air shower.
- Veil.
- Exhaust umbrellas.
- Suction panels.
- Blowjobs.
- Fume hoods.
In supply ventilation, a type of air exchange is an air shower or an oasis. In these systems, an air shower supplies clean air to work areas and at the same time reduces the temperature in the inflow area. Oasis is a system that supplies cooled air, separated by partitions. Another type of local circulation system is an air curtain; it can change the direction of movement of air masses. Local ventilation not only allows you to effectively rid a room of toxic substances, but also do it quite economically.
General exchange ventilation is less effective than local ventilation, since it simply changes the air in the entire room at the same time. The so-called dilution of harmful substances with clean air occurs. At many chemical plants, the release of harmful substances can vary greatly, which makes the use of general ventilation completely uneconomical.
Also, in very large industrial premises and where the number of working people is small, it does not make sense to use general ventilation. It is enough to install a local system in places where there is the greatest concentration of workers.
Types of ejectors
Ejector pumps can be steam, steam jet and gas. The general principle of their operation is identical. But the devices are activated in different ways. A pump with a steam-type ejector is used to pump out gaseous media from a closed volume. You can maintain the pressure at a negative level, making the environment rarefied. Scope of application: industry.
Steam jet design designed to work with gaseous media and liquids. The difference in the operation of an ejector device of this type is that the steam passing through the nozzle draws the pumped medium with it at high speed. Given their high performance, the scope of application of these devices is urgent pumping of water, for example, on a ship.
Gas type is a separate category of ejectors. The devices operate on compressed gas, which, mixed with the pumped medium, is directed into a diffuser to slow it down. After its passage, the mixture escapes through the nozzle hole. Such devices are intended mainly for the gas industry.
Built-in models
When understanding what an ejector is, it is necessary to consider the classification of these devices depending on the installation location. Built-in models are part of the structure, or rather, its component. The ejector can be attached to the pump itself or next to it on a single frame. Installation consists of attaching the block to the base and connecting the forces
The scheme works when water rises from a depth of 10 meters. The exact parameters are indicated in the technical documentation. Installation is recommended to be done outside the home. This may be a well with a head installed, or a separate building. The reason for this is increased noise and vibration. If this is not possible, consider the following type of installation.
Remote models
In this case, the circuit must be supplemented with an additional tank for pumping liquid. The well must be wide enough to accommodate two hoses. Productivity in this case will decrease by a third due to a decrease in the diameter of the intake pipe. You will also need a separate pipeline for air supply.
But with this configuration, a vacuum area is created in the gas intake, which allows you to lift liquid from a height of more than 50 meters. In this case, the distance from the well to the consumer can be more than 40 meters. In this case, the pumping station can be installed indoors inside the house. This could be a basement, boiler room, storage room, etc.
Ejector pumps
The procedure for connecting an ejector as an independent device consists of two stages:
- An additional pipe is laid according to all the rules that were taken as the basis when installing the water supply pipeline. An additional pipe is needed to supply the injection medium.
- Connecting the pipe to the suction unit. It is necessary to install a coarse filter and a return pipe. It is recommended to install a valve to regulate the operation of the system.
The valve is necessary if the water level in the pit is higher than that for which the pump is designed. In this case, you can adjust the discharge flow.
Ejector pumping station
A pumping station with a built-in ejector is a set of equipment originally designed to perform work under certain conditions. The main parameters that are taken into account when choosing are power and performance. The first characteristic means the ability to maintain pressure in the system, as well as the ability to retain a water column and transmit liquid over a distance through a horizontal pipeline.
The second characteristic is productivity. This is the amount of liquid pumped per unit of time. This parameter cannot be greater than the well flow rate. If we are talking about purchasing a pumping station with a built-in ejector, then the technical documentation indicates the general output characteristics. This means that no additional calculations will have to be made.
Device Features
The ejector device is very simple; it can even be assembled manually from ordinary materials. The design of the device consists of the following parts:
- Diffuser;
- Offset node;
- Water suction chamber;
- Nozzle narrowed downwards.
Pump operating principle
The operation of the device is based on Bernoulli's law. When the speed of a certain flow increases, a field with a low level of pressure is created around it. In this regard, a discharge effect is created. The liquid, passing through the nozzle, narrowed downward according to its design, gradually increases speed. After which the liquid, entering the mixer, creates low pressure in it. Thus, the pressure of the liquid that enters the mixer through the water suction chamber increases significantly.
It is also worth noting that for the ejector to work properly, it must be installed on the pump so that some of the liquid that is lifted by the pump remains inside the device, or more precisely, the nozzle, constantly creating the necessary pressure . It is thanks to this operating principle that it is possible to maintain a constant accelerated flow. Using such a device can significantly save energy.
Disadvantages and advantages of the natural air system
Equipment of this type of air exchange does not require additional costs. With it you can easily organize the cleaning of large rooms. Artificial ventilation in this case would require the installation of special equipment and high energy consumption. In addition, it is necessary to have people on staff who would service all these devices.
Despite the positive aspects of such air exchange, disadvantages can always be found. For example, using a natural system, it is impossible to regulate humidity in a plant. Natural air circulation will not be able to clear it of dust, and it is also impossible to ensure flow to certain areas in the workshops.
Difference from injector
Both of these devices are jet devices, that is, for suctioning liquid and gaseous substances.
An ejector is a device in which kinetic energy is transferred from a working medium at high speed to a non-working, that is, passive, medium through their displacement.
An injector is a device in which gases and liquids are compressed.
The main difference between these devices is the method of transmitting energy to the passive medium. For example, in an injector the supply occurs due to pressure, and in an ejector the supply occurs due to the creation of a self-priming effect.
This old new inkjet machine
Inkjet devices have been in use for almost two centuries, but the level of knowledge about their functionality can hardly be called sufficient. Therefore, their scope of application is currently extremely limited.
The first such devices - they were used for water and water vapor - were created by famous scientists Bernoulli, Zeiner and Rankine. Russian scientists Sokolov, Singer and Temnov developed jet devices for various gases and liquids, as well as bulk materials.
It is worth noting that intensive theoretical research and widespread practical implementation of inkjet devices have been noted during periods of economic downturns: they make it possible to use energy more efficiently - and, therefore, reduce resource consumption.
Ejector and injector
A jet apparatus, as is known, is a device for pumping or suctioning liquid, gaseous or granular substances. Its work is based on the exchange of mechanical energy between two flows of substances during the process of mixing. A flow with a higher pressure is called a working one (or a flow of a working medium), and a flow with a low one is called a passive one (a flow of a passive medium).
As a rule, the design of such a unit includes a nozzle, diffuser, receiving and mixing chambers. The working flow is ejected from the nozzle into the receiving chamber at high speed and carries along the passive medium. In the mixing chamber, the speeds (pressures) of the media flows are equalized. Then the mixed flow is directed to the diffuser, where its kinetic energy is converted into potential compression energy, under the influence of which further transportation of the pumped medium occurs.
Along with the simplicity of design, reliability of operation and ease of maintenance, a significant advantage of inkjet devices is the absence of electrical equipment, as well as moving and rotating components and parts. And although the efficiency of the devices is not very high, their clear advantages over other devices for similar purposes allow them to be used in many branches of technology.
There are two types of jet devices: ejectors and injectors.
Ejectors (literally translated as “pusher”) are a device in which kinetic energy is transferred from a working medium moving at a higher speed to a passive medium. Energy transfer occurs during the process of mixing media. Ejectors are widely used as mixers, for example in the chemical and oil refining industries.
An injector (literally a supercharger) is a device for compressing gases and vapors, as well as pumping liquid into various devices and reservoirs. Injectors have found their application in cars, steam locomotives, locomotives and small boiler plants - for supplying feed water to a steam boiler.
The main and fundamental difference between an ejector and an injector is the method of supplying a passive medium to the device. If a passive medium is supplied to the injector under pressure, then the passive medium enters the ejector due to the occurrence of a self-suction effect.
For the first hundred years of their existence, jet devices were used only to increase the efficiency of the thermodynamic “steam-condensate” cycle. However, as industry developed, the range of their practical use began to expand. Nowadays, jet devices prepare foam-air and foam-water fire extinguishing mixtures, remove water, increase the efficiency of oil and gas wells, transport bulk and liquid media, supply lubricant and fuel to machines and mechanisms, and perform other functions.
What is the difference between an ejector and an injector?
An injector is a standard linear accelerator , thanks to which the process of introducing charged particles inside the main accelerator occurs. There are several types of injectors that differ in their operating principles and many other characteristics.
An ejector is a device for sucking out liquid or gaseous substances and transporting hydraulic mixtures. It differs from an injector due to the direction of its work in the opposite direction. It is natural that all these technical differences are taken into account by the design of the equipment, designed to perform the function assigned to it as quickly and efficiently as possible.
It is worth noting that both devices are compact and have a high speed of action, which is required of them due to the design of adjacent parts assemblies and the speed of movement of the liquid or other substances used in the design.
Both options are one device only with different directions of action. This device is a jet pump.
If the pump operates in the direction of the injector, it will pump liquid or gaseous substances. If it is water-based, then a injection system will be used for this, which allows it to work even at high pressure values . This is the difference between the injector and other equipment.
It produces a pressure of injected water that exceeds the pressure of the steam itself. Very often, injection-based pumps are used in boiler rooms, where effective equipment is required to create high-quality injection.
As for ejectors, things with their use are somewhat different. To do this, water is supplied inside the device and reaches a special nozzle . Next, it enters the so-called mixing chamber, where a significant decrease in pressure occurs to operating parameters.
When water then passes through a narrow section of the diffuser and takes air with it, creating a rarefied atmosphere, which is created in the same mixing chamber to facilitate the passage of water. The injector flow can be simply adjusted using a special pipe, which is connected to the working part of the equipment.
While there are many common features, it is worth noting that the difference in purpose also implies a difference in design, because if the device needs to pump, it will be able to work with much higher pressure than a device that is only required to do a wide range of work to suck out excess water.
Part. 4 Ejection Effect
I would like to talk about the Ejection Effect as an independent physical process (phenomenon).
This process is described very sparingly on the Internet. The maximum that can be found is something like this:
“The Ejection effect is that a flow with HIGHER pressure, moving at high speed (ejecting flow or active or primary), carries along a LOW pressure medium. The entrained flow is called ejected (either passive or secondary). In the process of mixing (mixing) the two media, the speeds are equalized, accompanied, as a rule, by an increase in Pressure. The main feature of the physical process is that mixing (mixing) of flows occurs at high speeds of the ejecting (primary) flow.”
In order not to break the language from the words “ejecting flow” and “ejected flow”, for ease of communication we will call them this way: “Primary high-speed flow” and “secondary flow”, respectively. As we see, already in the definition of this process there are some inconsistencies and disagreements: 1. If the “Primary high-speed flow” has a HIGHER pressure, then how does it capture molecules of the Environment (OS) and create a “secondary flow”? After all, we know that air masses ALWAYS move from a zone of high pressure to a zone of low pressure. But according to this definition, everything happens exactly the opposite, i.e. OS molecules with lower pressure rush (create a secondary flow) towards a flow with higher pressure - nonsense! 2. It is further stated that in the process of mixing (mixing) two media (two flows) in parallel with the process of equalizing speeds (i.e. braking of the primary flow), as a rule, an increase in Pressure occurs. And the question arises: the “Primary high-speed flow” already has (by definition) a HIGHER pressure, and it turns out that the Pressure increases even MORE - again nonsense! 3. It is further stated that: The main feature of the physical process is that mixing of flows occurs at high Speeds of the Primary Flow. Ha. Ha. Ha. Why doesn’t the Ejection effect occur at low speeds? And what is “high speed” - how much is it?
