Basic theory of compressed air - compressed purpose

Basic Theory of compressed air ( 4 )

     Compression Purpose

Gas compression with a basic purpose , ie higher than the original gas pressure, pressure transmission . The original pressure level may be low , ranging from very low absolute pressure ( parts per thousand kg ) up to several thousand kilograms ; pressure from a few grams to several thousand kilograms ; the transport of the gas from a few cubic meters / minute until several hundred thousand m / min.

There are various specific purpose of compression :

1 in the compressed air system drive pneumatic tools transfer power ;

(2) provide for the combustion air ;

3 in the gas pipelines and city gas distribution gas transmission and distribution systems ;

4 of the gas circulating through a process or system ;

5 of chemical reactions ｃｒｅａｔｅ a more active condition ;

6 for a variety of purposes than the original manufacture and maintain a high level of stress would be to leak into the air or into the system or the existence of the original hybrid gas discharge system .

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Compression Method

Compressed gas approach has four kinds: two kinds of the intermittent flow method, the other two species are continuous flow method ( which is illustrative classification terms , rather than by thermal or functional classification ) . These methods should :

1 a certain amount of continuous gas trapped in a container , reducing its volume so that the pressure increases, and the compressed gas is introduced containers.

(2) the amount of continuous gas trapped within a container, the gas to the exhaust port , but does not change its volume , counter to the exhaust system through the compressed gas container and the compressed air introduced .

3 through rapid rotation of the rotor of the mechanical movement of compressed gas . The speed and pressure of the rotor to pass the flow of gas ( at a fixed diffuser or barrier speed is further converted to pressure).

4 gas into the same or another gas ( typically , but not necessarily the steam ) in a high-speed nozzle and the diffuser will be converted to a mixed gas pressure at high speed .

Methods 1 and 2 using a compressor is intermittent stream class called a variable displacement compressor ; using the method known as the speed-type compressor 3 ; using the method known as jet compressor 4 , the feed air pressure is generally lower than the atmospheric pressure .

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Compressor types and characteristics

The main types of the compressor shown in Figures 1A, the following definitions of various compressors . Cam , diaphragm and the diffusion pump compressor is not included, because they use special and relatively small size .

Displacement compressor is to a certain amount of continuous flow limitation in a closed space, the pressure rise.

Reciprocating compressor is a positive displacement compressor , the compression element is a piston reciprocates within the cylinder .

Compressor is a positive displacement rotary compressor , the compression element is forced by the rotating movement achieved.

Vane rotary compressor is a variable capacity compressor vane axial cylindrical cylinder in the same eccentric rotor for radial sliding . Trapped between the vane compressed air is discharged .

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

Roots is a dual-rotor rotary compressor displacement compressor , in which the two intermeshing rotors Roots thus the gas stopped them from the inlet to the exhaust port . No internal compression .

Rotary screw compressor is a positive displacement compressor, in which two rotors with helical gears meshing with each other , so that the gas is compressed and discharged .

Speed type rotary compressor is a continuous flow compressor, in which the high-speed rotating blades of the gas through its acceleration , so the speed can be converted into pressure . This transformation in part in the rotating blades , and in part in a fixed diffuser baffle or reflux .

Centrifugal compressors are speed type compressor, in which one or more rotary impeller ( usually the side blades ) the gas speed . Main gas flow is radial .

Axial compressors are speed-type compressor in which the gas is accelerated by a bladed rotor . Main gas flow is axial.

Is a mixed flow type compressor speed type compressor , a combination of the shape of the rotor centrifugal and axial some of the features of both .

A high-speed gas jet compressor or steam jet intake gas flow away , then the diffuser will be converted to velocity of the gas mixture pressure .