What are the types of compressors

The compressor is a unit for compressing and moving various gases, including air, to various instruments and pneumatic tools. Compressor equipment is widely used in industry, construction, medicine, etc. Existing types of compressors and their classification determine the criteria for the operation of this equipment.

Classification of compressors on the principle of operation

By the principle of operation, compressors are classified into volumetric and dynamic.

Voluminous

These are units having working camerasin which the gas is compressed. Compression occurs due to periodic changes in the volume of chambers connected to the input (output) of the apparatus. To prevent the gas from returning from the unit set the valve system which open and close at a certain point of filling and emptying the chamber.

Dynamic

In dynamic compressors, an increase in gas pressure occurs due to accelerating its movement. As a result, the kinetic energy of the gas particles is converted into pressure energy.

Important! Dynamic compressors differ from bulk open flow part. That is, with a fixed shaft, it can be blown in any direction.

Types of volumetric compressors

The compressor equipment of volumetric type is divided into 3 groups:

• membrane;
• piston;
• rotary.

Membrane

Have in the working chamber elastic membraneAs a rule, polymer. Due to the reciprocating movements of the piston, the membrane is bent in different directions. As a result of membrane movements, the volume of the working chamber changes. Valves, depending on the position of the membrane, either let air into the chamber or release it.

The membrane can be set in motion from a pneumatic, membrane-piston, electric or mechanical drive.

Important! In membrane devices, air or gas in the process of moving through the working chamber is not in contact with other units of the unit (except the membrane and the housing). Due to this, high purity gas is obtained at the outlet.

Piston

Due to the presence crank mechanism the piston reciprocates in the working chamber, which causes its volume to decrease or increase.

Reciprocating compressors have one-way valves installed on the working chamber, blocking the movement of air in the opposite direction. Despite good performance, piston units have drawbacks: a rather high level of noise and noticeable vibration.

Rotary

In rotary compressors, air is compressed rotating elements - rotors. Each element, depending on the length and pitch of the screw, has a constant value of compression, which also depends on the shape of the gas outlet.

In such compressors, valves are not installed.Also, the design of the unit does not contain components that can cause imbalance. Because of this, it can operate at high rotor speeds. With this design of the apparatus, the gas flow reaches high values ​​at small dimensions of the compressor itself.

Rotary compressors are divided into several subspecies.

Oil free

They have an asymmetrical screw profile, which increases the efficiency of the unit due to the reduction of gas leaks during compression. To ensure synchronous counter-rotation of the rotors, an external gear train is used. During operation, the rotors do not touch, and they do not need lubrication, so the air leaving the unit has no impurities.. To reduce internal leakage, parts of the unit and housing are manufactured with high precision. Also oil free machines can be multistageto remove the temperature difference between the air inlet and outlet of the apparatus, which limits the increase in pressure.

Screw

Consist of one or more screws that are meshed, installed in a sealed enclosure.

The working space is created between the housing and the screws as they rotate.This type of compressor is different good performance and continuous air supply. To reduce friction between the screws in the hook, which increases the wear of parts, a lubricant is used. If you want to get compressed air (gas) without impurities of lubricants, then use oil-free screw devices. In the latter, in order to reduce the force of friction, moving parts are made from antifriction materials.

Gears

These compressors are also called gear because the main parts are gears. When rotating, they rotate in opposite directions, creating a working chamber between the teeth and the walls of the housing.

When the teeth enter into engagement on the side of the outlet of the unit, the volume of the chamber decreases, as a result of which air is released through the nozzle under pressure. Compressors of this type are widely used in situations where the supply of air or gas under high pressure is not required.

Spiral

This is a kind of oil-free rotary type compressors. Spiral devices also compress the gas in volume, which decreases gradually.

The main elements of this unit are spirals. One helix is ​​fixed motionless in the copra device. The other is mobile, connected to the drive. The phase shift between the spirals is 180 °, due to which air cavities are formed with a variable volume.

Rotary plate

The lamellar compressor has a slotted rotor. They inserted a certain number of movable plates. As can be seen from the figure below, the rotor axis does not coincide with the body axis.

When rotating the rotor, the plates are moved by a centrifugal force from its center to the periphery and pressed against the inner surface of the body. As a result, there is a continuous creation of working chambers bounded by adjacent plates and rotor and apparatus bodies. By offset axes the volume of working chambers changes.

Liquid ring

In these units auxiliary liquid is used. A rotor with plates is installed in a statically fixed housing.

The design features of this unit are the offset axes of the rotor and the body relative to each other. A liquid is poured into the body, which takes the form of a ring, clinging to the walls of the apparatus as a result of its discarding by the rotor blades.When this occurs, the restriction of the working space, filled with gas, between the liquid ring, the housing and the rotor blades. The volume of the working chambers is changed by means of a rotating rotor with an offset axis.

Important! To prevent the pumped gas from carrying off the liquid particles, liquid separation devices install a separation unit that cuts off moisture from the air. Also on devices of this type, a system is installed that provides water for the working chamber with auxiliary liquid.

Types of dynamic compressors

Devices with a dynamic principle of action are divided into axial, centrifugal and jet. They differ in the type of impeller and the direction of air flow.

On a note! Also, dynamic vehicles are also called turbo compressors, since their design resembles a turbine.

Axial vehicles

In axial compressors, the gas flow moves along the axis of rotation of the shaft through fixed guides and moving impellers. The flow rate of air in the axial apparatus is gained gradually, and the energy conversion takes place in the guides.

Axial compressors are characterized by:

• high speed;
• high efficiency;
• high air flow;
• compact size.

Centrifugal units

Centrifugal compressors are designed to provide radial air outlet. The air flow, falling on a rotating impeller with radially located impellers, due to centrifugal forces is ejected to the walls of the housing. Further, the air moves into the diffuser, where its compression process takes place.

Centrifugal devices have no reciprocating movements, therefore they provide a uniform flow of air, the force of which can be regulated. Also, this type of unit is durable and economical.

Jet Compressors

In the apparatus of the jet principle of action to increase the pressure of the gas (passive) is used active gas energy.

For this, 2 gas streams are supplied to the device: one with low pressure (passive) and the second with high (active). At the outlet of the device, a gas stream is formed with a pressure higher than the passive one, but lower than that of the active gas.

Important! A distinctive feature of jet compressors is the simplicity of design, the absence of moving parts, high reliability.

Classification of compressors by other parameters

In addition to the classification of compressors on the principle of compression, it is customary to divide these units according to the following parameters:

1. type of drive. Compressors can work both with electric motors and internal combustion engines (ICE). Accordingly, the devices are direct transmission (coaxial) and belt driven. As a rule, a direct drive compressor is a domestic unit. The coaxial compressor attracts the consumer with an affordable price and is widely used in summer cottages in garages, etc., since the air pressure delivered by the device does not exceed 0.8 MPa. If we compare the gasoline and diesel compressor, the latter is more reliable in operation. Also, diesel has a simpler device and is easy to maintain.
2. Cooling system. Devices are liquid or air cooled or without it.
3. terms of Use. Devices can be stationary, working only indoors from the power supply network, and mobile (portable) which work is allowed in the open air and at low temperatures.For example, mobile compressors with an internal combustion engine are widely used in places where there is no centralized power supply.
4. Final pressure. According to this parameter, the devices are divided into four groups. Low pressure units (0.15-1.2 MPa) are used as part of installations for compressing gases (air). Devices of average pressure (1.2-10 MPa) are used for the separation, transportation and liquefaction of gases in the oil refining, gas and chemical industries. High-pressure (10-100 MPa) and ultra-high pressure (over 100 MPa) devices are used in installations for the synthesis of gases.
5. Performance. Indicated in units of volume for a certain period of time (m³/ min) The performance of the unit depends on parameters such as the speed of rotation of the shaft, the diameter of the cylinder, the stroke of the piston. According to the performance, it is customary to divide the apparatuses into 3 categories: small - up to 10 m³/ min; average - from 10 to 100 m³/ min; large - over 100 m³/ min

In addition, compressors are divided depending on the field of application into general-purpose units, petrochemical, chemical, energy, etc.