The basic theory of compressed air - compression

The basic theory of compressed air (4)

Compression purpose

The compression of the gas has a basic purpose, namely to transmit gas pressure is higher than the original pressure. The original stress levels may be high and low range, from very low absolute pressure (a few parts per thousand kilograms) until a few thousand kilograms; Pressure from a few grams to thousands of kilograms; And transport gas from a few cubic meters/min until hundreds of thousands of cubic meters/min.

There are all kinds of: compressing the specific purpose of

1. The drive pneumatic tool in the compressed air system transmission power;

2. Provide air for combustion;

3. In the natural gas pipeline and city gas transmission and distribution in the gas distribution system;

4. Make the gas through a process or system cycle;

5. ｃｒｅａｔｅ a condition of chemical reaction more active;

6. Aim for a variety of manufacturing and maintain a stress level is higher than the original, way is to leak into or the gas flow into the system or the original of the mixed gas discharge system.

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Compression method

Compressed gas way there are four: two is intermittent flow method, the other two is the continuous flow method (this is the classification of descriptive terms, rather than according to the thermodynamics or functional classification). These methods are to:

1. To a certain amount of continuous gas entrapment in a container, reduce the volume so that the pressure increase, then the compressed gas containers.

2. To a certain amount of continuous gas entrapment in a container, but not take gas to vent to change its volume, compressed gas through exhaust system of flow, then the compressed air launch container.

3. By rapidly spinning rotor mechanical movement of compressed gas. The rotor speed and pressure to the flow of gases (diffuser or damper on fixed speed further into pressure).

4. Will be sent to the same or another gas (usually, but not necessarily the steam) high-speed nozzle, and the diffuser will be mixed gases of high speed is converted into pressure.

Using method 1 and 2 compressors belong to intermittent air class, called a varactor compressor; Adopt the method 3 is called speed type compressor; Adopts the method of 4 called injection compressor, the inlet pressure is generally lower than the atmospheric pressure.

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The types and characteristics of the compressor

Compressor main species listed in figure 1 a, below is the definition of all kinds of compressor. CAM type, diaphragm and the diffusion pump compressor is not included, because they use special and relatively small size.

Positive displacement compressor is to a certain amount of continuous flow confined to a closed space, make the pressure.

Reciprocating compressor is a positive displacement compressor, its compression components is a piston, within the cylinder for reciprocating motion.

Rotary compressor is a positive displacement compressor, compression is implemented by forcing movement of rotating components.

Sliding vane compressor is a rotary varactor compressor, its axial sliding vane on the same eccentric cylinder cylinder rotor radial sliding. Intercept the vane and the air is compressed between the back out.

Liquid - piston compressor is a rotary positive displacement compressor, in which water or other liquid as the piston to compress gas, then the gas discharge.

Roots double rotor compressor is a rotary positive displacement compressor, in which the two roots rotor meshing with each other in order to stop the gas, and from inlet to outlet. No internal compression.

Screw compressor is a rotary positive displacement compressor, in which the two rotor with a helical gear meshing, so the gas compression side by side.

Continuous air compressor, speed type compressor is revolving in the high speed rotating blade through its gas acceleration, thereby will speed can be converted into pressure. This transformation occurs on the rotor blades, part the diffuser in fixed or back panel.

Centrifugal compressor speed type compressor, in one or more rotating impeller (blade usually on the side) accelerates a gas. The main air flow is radial.

Axial flow compressor speed type compressor, in which the gas by bladed rotor speed. The Lord is axial airflow.

Mixed flow compressor and the speed type compressor, its the shape of the rotor is a combination of some characteristics of both centrifugal and axial flow.

Injection compressor with high gas or steam jet flow take suction gas, then the speed of the gas mixture in diffuser is converted into pressure.