Rotary compressor units are widespread in enterprises and in small workshops. This type of compressed air injection equipment is characterized by a robust design that provides high performance. To this it is worth adding practicality in servicing the unit. At the same time, rotary compressors have a number of disadvantages that limit the scope of their use.
Compressor device
Rotary models represent a whole group of compressors that differ in design and performance. The main share of stations of this type are rotary aerial installations. In this case, the device of rotary compressors is based on the shaft of the engine, providing a working function. A rotor is mounted on the shaft, but during operation, the movement is not from the center of the circle, but eccentrically. This is due to the fact that the shaft of traditional models has an offset.
Functional filling, in turn, is enclosed in a metal case - usually a cylindrical shape. Without fail, the technological gap is maintained from the shaft with the rotor to the surface of the housing. During operation, the rotary air compressor will reduce it in accordance with a value equal to the aforementioned shaft offset. Also, special plates and dampers are used to provide additional protection and to prevent overflow of process fluid.
Principle of operation
With each rotation of the rotor, a free zone will be formed between the cylinder wall and the working group. At this point, it is filled with dry superheated or saturated steam - these can also be varieties of refrigerants and oily liquids. On the other hand, the process of compression of this zone starts the pressure valves, contributing to the absorption of the same vapor from the evaporator. When a multiple revolving cycle is made, the optimum working pressure is achieved, which allows the main function of pumping compressed air to be performed, for which a rotary compressor is used. The principle of operation of rotary models provides for the automated supply of oil. This is especially true for industrial units operating at high loads. Liquid filling is carried out from a special tank - it enters the oil separator to a certain level. If necessary, the oil can be cooled with water.
Types of construction
Typically, rotary-type compressors with oscillating and stationary compression elements are distinguished. In the first model of the working group, it is assumed that the refrigerant is compressed by means of a rotary eccentric on the engine. It is in some way an independent element, providing a relatively high degree of compression. However, due to increased friction, such units are considered ineffective. At least costly in terms of maintenance. On the other hand, rotary vane compressors eliminate the undesirable effect of intense friction. Refrigerant compression is realized by plates fixedly mounted on the shaft. They are stationary relative to the shaft itself, but they perform their compression function with it.
Features of spiral models
Spiral models are more often used in small and medium power plants - for example, in refrigerators. The working group is formed by two metal spirals - one integrates into the other. In this case, the base spiral is stationary, and the outer one rotates around the axis. What is more important, in compressors these elements have a special involute profile, which allows rolling, but not slipping. It involves a scroll compressor and moving the contact points of the working elements. It is in it that the cycles of compression and pushing through the central hole occur. By the nature of the compression, spiral aggregates can be called softer and more gentle. Therefore, the output power allows them to be used in equipment of medium and low productivity. It is worth emphasizing the complexity of the technical implementation of such compressors, due to the need to comply with the tight fit of the spiral elements and the tightness of the ends.
Unit protection systems
The high quality of the element base and the carefully verified arrangement of functional parts are not enough for the equipment to regularly perform its tasks in the production environment. Therefore, modern models can not do without additional protective systems. First of all, it is an automatic shutdown of the unit when fixing network congestion. Thus, the motor control unit is protected. Since rotary compressors are prone to overheating of the mechanical part, it is introduced into the design and cooling system. It minimizes thermal loads affecting both technical fluids and structural details. For electronically controlled models, self-diagnosis systems are provided. Thanks to the sensors, the compressor, without operator intervention, can determine the malfunctions of the units and, depending on the nature of the breakdown, either fix them independently or send an appropriate alarm signal through the indicators.
Main characteristics
Compressor performance determines which equipment a particular model can optimally work with. This characteristic is expressed by the ratio of the released air volume per unit time - usually a minute. Domestic units most often have a capacity of about 100 l / min. This is quite enough for working with pneumatic tools like sprayers, grinders and hammers. But if, for example, the simultaneous use of several pneumatic devices is planned at the construction site, then the productivity should increase to 150-200 l / min and higher. In addition, it is desirable to use a compressor with a rotating rotor with a margin of power potential. That is, 15-20% will need to be added to the total planned load. This increase is justified by a decrease in the load on the elemental base. An essential characteristic is the working pressure, on average, varying from 6 to 15 bar. In this case, the selection is also done based on the requirements for a particular tool. For optimum performance, 2 points are added to the nominal pressure rating of the tool.
Expendable materials
In the workflow of rotary compressors, oil plays a special role. The main function of compressor fluids is to maintain the wear resistance of parts, to prevent depressurization and the formation of deposits. But modified formulations with individual improved properties are also available on the market - for example, it can be frost resistance, corrosion protection, etc. As for the type of substrate, a scroll compressor operating at temperature loads of up to 100 degrees can be filled with synthetic means. If this threshold increases, then you should turn to more expensive, but high-quality mineral oils. Technical accessories are also a necessary complement. In this group of consumables, hoses, adapters, fittings, valves, filters and fasteners are distinguished. Thanks to component equipment, the infrastructure of interaction of the compressor with the working tool or equipment is organized.
Manufacturers and prices
Although the compressor segment as such is very extensive and offers products from almost all major manufacturers of construction and industrial equipment, the category of rotary models is the least popular, and therefore offers are significantly limited. The most popular installations are manufacturers of refrigeration equipment Matsushita, Galanz, Toshiba, etc. They cost about 20 to 50 thousand rubles. Abac, FUBAG and COMARO are recommended for construction and industrial applications. These companies offer mainly high-performance units designed for operation in large enterprises. At the price, rotary compressors of this type also differ markedly - on average they cost 200-300 thousand. By the way, Abac offers one of the most expensive stations in its GENESIS line. This is a model with a capacity of 3320 l / min and a working pressure of 8 bar, available for 650 thousand.
What to consider in the choice?
Consumers who need a low-cost, low-noise and at the same time productive source of compressed air are usually suitable for the selection of rotary compressors. Therefore, the industry with all its operating features will be the main area where this type of compressor is used. The rotation engine most often focuses on a network voltage of 380 V. If there is no three-phase line in the use area, then you will have to make a discount on productivity, focusing on 220 V. In addition to the main operating values, the design is also taken into account. Usually it is stationary, but even large-sized modifications in some versions provide the ability to move. This nuance should be borne in mind if it is planned to service several technological points located in different places at the facility.
Maintenance
In the conditions of regular operation, preventive testing sessions should be carried out in accordance with the schedule. An oil change and revision of the connecting parts is carried out before each application procedure. If critical deformation of elements or wear of consumables is detected, air compressors are repaired, which can be expressed by replacing faulty components. Technical restoration of the same deformed elements is undesirable, since their service life will in any case be lower.
Special attention is paid to oil and coolant supply channels. Filters, membranes, gaskets and hoses interact with them - this infrastructure should be regularly cleaned, rinsed and also replaced if necessary. By the way, repair of air compressors in the form of restoration of fan blades and a radiator grill is carried out just in those cases when the maintenance personnel paid insufficient attention to the fight against blockages and pollution of the structure.
Fields of application
It has already been said that compressor installations are often used to service pneumatic-based construction tools. But this is only part of the tasks that units of this type are capable of performing. Their specialized niche is still refrigeration equipment. Moreover, it can be directly industrial refrigerators with refrigerators, and domestic air conditioners. In the second case, compact and low-power rotary compressors are used. Application in industry also focuses on the possibility of the unit working with refrigerants - the equipment is used at the technological stages of processing slaves, meat, semi-finished products and other food products.
Conclusion
Despite all the differences with reciprocating compressors, rotary units operate according to the same principle of displacing the medium. Differences are determined by the structural implementation of mechanics, which ensures the whole process. Among the advantages possessed by rotary compressors against the backdrop of piston counterparts, it is possible to note the possibility of connecting to the engine, balanced travel with reduced vibration, uniform flow of gas media and the absence of a group of valves. But there are also disadvantages. So, for example, the tight interaction of mechanical parts contributes to their rapid physical deterioration. Rotational models also have weaknesses in terms of manufacturing technology - they require high-precision assembly, otherwise the unit will not be able to meet the declared performance indicators.