With the rapid development of national economy, compressors have been widely used in industry. Compressors are called "general machinery" because of their wide applications. According to the different characteristics of compressed gas, it can be divided into the following categories:
1, compressed air as power:
* * * drives all kinds of pneumatic machinery. The exhaust pressure of pneumatic tools is 7-8kg/cm2, which is used to control instruments and automation devices. The pressure is about 6kg/cm2, the vehicle is automatic, and the doors and windows are opened and closed. The pressure is 2-4kg/cm2, and it is 4kg/cm2 for pharmaceutical industry and brewing industry. The weft blowing pressure of air-jet loom is 1. The starting pressure of medium and large diesel engines is 25 ~ 60 kg/cm2, the oil well rupture pressure 150 kg/cm2, the "secondary method" oil production pressure is about 50 kg/cm2, and the high-pressure blasting coal mining pressure is about 800 kg/cm2. The pressure compressed air in the national defense industry is its driving force. The ups and downs of submarines, the shooting and driving of torpedoes and the salvage of sunken ships are all powered by compressed air with different pressures.
2. Compressed gas is used for refrigeration and gas separation:
Gas is liquefied by compression, cooling and expansion, and used for artificial refrigeration (refrigeration and air conditioning, etc.). Such as ammonia or freon compressors. Its compression pressure is usually 8 ~ 12 kg/cm2. This kind of compressor is usually called "refrigerator" or "ice maker". In addition, if the liquefied gas is a mixed gas, each component can be separated separately in the separation device to obtain various gases that are qualified by lip reading. For example, pure oxygen, pure nitrogen and pure rare gases such as xenon, krypton, argon and helium can be obtained after air liquefaction and separation.
3. Compressed gas is used for synthesis and polymerization;
In chemical industry, gas compression to high pressure is often beneficial to synthesis and polymerization. For example, nitrogen and hydrogen synthesize ammonia, hydrogen and carbon dioxide synthesize methanol, and carbon dioxide and ammonia synthesize urea. Taking the chemical industry as an example, the pressure of high-pressure polyethylene reaches 1500 ~ 3200 kg/cm2.
4. Difficulties in hydrofining compressed gas oil:
In the petroleum industry, hydrogen reacts with oil by artificial heating and pressure, which can recombine and decompose hydrocarbons into light components of hydrocarbons, such as lightening of heavy oil and hydrofining of lubricating oil.
5, gas transmission:
The pressure of the compressor used to transport gas through the pipeline depends on the length of the pipeline. When sending remote gas, the pressure can reach 30 kg/cm2. Chlorine bottling pressure is 10 ~ 15 kg/cm2, and carbon dioxide bottling pressure is 50 ~ 60 kg/cm2.
The following is Baidu Encyclopedia's introduction about "air compressor".
air compressor
The machine used to generate compressed air is also called compressed air machine, or air compressor for short. The compressor is directly driven by the motor, which makes the crankshaft rotate and drives the connecting rod to make the piston reciprocate, causing the volume change of the cylinder. Due to the change of pressure in the cylinder, air enters the cylinder through the intake valve and the air filter (muffler). In the compression stroke, due to the reduction of cylinder volume, compressed air enters the air storage tank through the exhaust pipe and the one-way valve. When the exhaust pressure reaches the rated pressure of 0.7MPa, it is automatically stopped by the pressure switch. When the pressure of the gas storage tank drops to 0.5-0.6MPa, the pressure switch is automatically turned on and started.
1. Brief introduction of working principle of air compressor
1.2 air compressor classification:
Air compressors are divided into screw air compressors, single-screw air compressors and twin-screw air compressors, centrifugal air compressors, piston air compressors, vane air compressors, scroll air compressors and rotary vane air compressors.
A twin-screw single-stage compressed air compressor is introduced, which is composed of a pair of mutually parallel male and female rotors (or screws) rotating in the cylinder, so that the air between the rotor tooth grooves constantly produces periodic volume changes, and the air is transported from the suction side to the output side along the rotor axis, thus realizing the whole process of suction, compression and discharge of the screw air compressor. The air inlet and air outlet of the air compressor are located at both ends of the shell, and the grooves of the mother rotor and the teeth of the rotor are driven by the main motor to rotate.
The compressor is directly driven by the motor, which makes the crankshaft rotate and drives the connecting rod to make the piston reciprocate, causing the volume change of the cylinder. Due to the change of pressure in the cylinder, air enters the cylinder through the intake valve and the air filter (muffler). In the compression stroke, due to the reduction of cylinder volume, compressed air enters the air storage tank through the exhaust pipe and the one-way valve. When the exhaust pressure reaches the rated pressure of 0.7MPa, it is automatically stopped by the pressure switch. When the pressure of the gas storage tank drops to 0.5-0.6MPa, the pressure switch is automatically turned on and started. For others, please pay attention to the relevant terms.
2. Compressor lubricating oil
2. 1 rotary vane compressor
Each type of compressor has different requirements for lubricating oil. The lubricating oil of rotary vane compressor is used to lubricate the blades that slide in and out during compression. Lubricating oil is also used as a sealant between the blade and the frame, which makes gas compression possible. Generally speaking, ISO68- 150 products meet the viscosity requirements of rotary vane compressors.
2.2 Reciprocating compressor
The reciprocating compressor provides a large discharge pressure capacity from 1 bar g to 1000 bar g(4). Reciprocating compressor oil lubricates cylinders, crankcase parts, coils, pistons, valves and oil injection rods. Crankcase assembly includes crosshead bearing, crosshead joint, crosshead guide rail and crank pin. The recent refrigeration application shows that ISO 15 lubricating oil with working viscosity less than 10 cSt can provide suitable lubrication. However, according to the operation of gas molecular weight and flow pressure, the classic use of reciprocating compressors for processing and hydrocarbon gas is ISO68-680 products.
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