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Piston compressor features
The piston compressor is a positive displacement compressor. It is suitable for medium and small gas transmission. The discharge pressure can be from low pressure to ultra high pressure. Compared with other types of compressors, it has a series of features:
The advantages are:
(1) Regardless of the flow rate, the required pressure can be obtained, the exhaust pressure range is wide, the highest pressure can reach 320MPa (industrial application), even 700MPa, (in the laboratory)
(2) Stand-alone capability is any flow below 500m3/min
(3) In the general pressure range, the requirements for materials are low, and ordinary steel materials are used.
(4) The thermal efficiency is high. Generally, the adiabatic efficiency of large and medium-sized units can reach 0.7~0.85.
(5) When the gas volume is adjusted, the displacement is almost independent of the variation of the exhaust pressure.
(6) The severity and characteristics of the gas have little effect on the performance of the compressor. The same compressor can be used for different gases.
(7) The drive machine is relatively simple, most of them use electric motors, generally no speed control
Due to the above advantages, piston compressors are widely used in the industry, but this model also has some shortcomings:
(1) The structure is complex and heavy, the wearing parts are large, the floor space is large, the investment is high, the maintenance workload is large, the service period is short, but after hard work, it can reach 8000 hours or more.
(2) The speed is not high, the machine is large and heavy, and the single engine displacement is generally less than 500m3/min.
(3) There is vibration during machine operation
(4) The exhaust gas is discontinuous, the airflow is pulsating, and it is easy to cause the pipe to vibrate. In severe cases, the pipe network or the mechanical parts are damaged due to the pulsation and resonance of the airflow.
(5) The flow adjustment adopts the auxiliary volume or bypass valve. Although it is simple, convenient and reliable, the power loss is large, and the efficiency is reduced during partial load operation.
(6) Oil-lubricated compressors with oil in the gas need to be removed
(7) When a large factory adopts multiple compressor units, there are many operators or work intensity
Second, the characteristics of the modified screw compressor:
Screw compressors are becoming more and more widely used, and various open and semi-closed screw compressors have been formed into series. In recent years, fully enclosed series screw compressors have appeared. Based on a series of advantages of screw and single screw compressors, its research and development fields are extensive, and its performance optimization potential is large.
Advantages of screw compressors
1) High reliability. The screw compressor has few parts and no wearing parts, so it runs reliably and has a long service life. The interval between overhauls can reach 40-80,000 hours.
2) Easy operation and maintenance.
3) The power balance is good. Particularly suitable for use as a mobile compressor, small size, light weight and small footprint.
4) Strong adaptability. The screw compressor has the characteristics of forced air transmission. The volume flow is almost independent of the exhaust pressure, and it can maintain high efficiency in a wide range. It can be applied to various working fluids without any change in the structure of the compressor. .
5) Multiphase mixing. The screw compressor actually has a gap between the tooth faces of the rotor, so that it can withstand liquid impact and can transport liquid-containing gas, dust-containing gas, and easily polymerized gas.
Screw compressor working principle
The structure of the screw compressor is shown in Fig. 8-23. In the "∞" shaped cylinder, two spiral rotors are placed in parallel and meshed with each other at a certain gear ratio. A rotor having a convex tooth outside a pitch circle is generally referred to as a male rotor (active rotor); a rotor having a concave tooth in a pitch circle is referred to as a female rotor (driven rotor). The spiral bodies on the male and female rotors are referred to as a female screw and a male screw, respectively. - The normal rotor (or the speed increasing gear set) is connected to the drive and the power is input therefrom; the male rotor (or the synchronized gear set) drives the female rotor to rotate. The main components of the screw compressor include a pair of rotors, bodies, bearings, synchronous gears (and sometimes speed-increasing gears), and seal assemblies.
Screw compressors can be classified into the following types depending on the mode of operation and use: oil-free screw machines and oil-injected screw machines.
In the oil-free screw, the male rotor drives the female rotor by the synchronous gear. The rotor meshing process does not touch each other.
In the fuel injection screw, the male rotor directly drives the female rotor, and there is no synchronous gear, and the structure is simple. A large amount of lubricating oil sprayed into the body acts to lubricate, seal, cool and reduce noise.
A screw compressor is a volumetric compression machine whose operation begins with an intake process, and then the gas undergoes compression in the sealed cogging volume and finally moves to the exhaust process. At both ends of the compressor cylinder, openings of a certain shape and size are respectively opened. One for air intake, called the intake orifice; one for exhaust and exhaust, called the exhaust orifice.
Tooth shape and internal and external pressure of screw compressor
Main features of screw compressor
As far as the principle of compressed gas is concerned, screw compressors, like piston compressors, belong to the volumetric compression machine; in terms of its motion form, the rotor of the compressor is the same as the dynamic machine for high-speed rotary motion. and so. Screw compressor has both characteristics.
The screw compressor has a high top line speed, and the speed can be as high as 10,000 rpm or more, so it can often be directly connected with the high speed drive. Therefore, the volume, mass, footprint, and exhaust pulsation of the unit displacement are much smaller than those of the piston compressor.
The screw compressor does not have a wearer such as a gas valve or a piston ring like a piston compressor, so that it is reliable in operation, long in life, and easy to realize remote control. In addition, since there is no reciprocating component and there is no unbalanced inertial force (moment), the screw compressor has a small foundation and can even achieve no basic operation.
This article is provided by Shandong Dingsheng Refrigeration Equipment Co., Ltd. If you have any enquiries, please call 15725158383
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