2024/7/25 17:17:44
1. Power system
The power system of air compressor refers to the prime mover and transmission device. The prime mover of the air compressor is mainly the motor and the diesel engine.
Usually the prime mover of the fixed air compressor is the motor, and the mobile motor and the diesel engine are both available.
Whether from the purchase cost, efficiency ratio or maintenance operation, the motor has an absolute advantage, so only in some field construction, mining and other lack of power supply, only the use of diesel engine drive, and generally only used in pneumatic tools, equipment drive.
The transmission mode of screw air compressor is more, there are belt transmission, gear transmission, direct transmission, integrated shaft transmission and so on.
Belt drive (belt), usually used in small models, early used in the 90kW below most, now generally only 45kW below will be used. Characteristics are simple, economic, convenient modification, the manufacturer of the whole machine design and integration ability is not high requirements, the disadvantage is loud noise, easy wear and slip belt, transmission efficiency is lower than other ways.
Gear drive is generally used in high-power air compressors (110kW or more) that need to increase or decrease speed, and it is the same as belt drive, which is for occasions that require a speed ratio (transmission ratio). That is, the speed of the motor is different from the speed of the head (positive rotor). Usually the gear and the main engine are arranged in a housing.
Direct transmission, that is, the shaft of the motor and the main engine are driven by a coupling, and the couplings used in the industry are flexible couplings, that is, there is a certain deviation in the pair of two rotors, and there are various types, such as plum flower type, tire type coupling and so on.
The so-called "1:1 direct connection", which is a commercial propaganda of the industry, means that the transmission ratio is 1. That is to say, the motor shaft is connected to the shaft of the host positive rotor through the coupling. That is, the speed of the host is equal to the speed of the motor, which is used to indicate that the speed of the host is low, the host specification is large, and it is not a short-lived machine with a small head pulling at high speed, and it is worth the money.
However, if it is actually the use of gear and direct connection two transmission modes. Since the main engine and gear are made into one, it seems that the motor and the main engine are also directly connected. As shown in the following figure, it can not be said that 1:1 direct connection.
Integrated shaft transmission is the transmission mode that has emerged with permanent magnet integrated machines in recent years, that is, the shaft of the motor and the shaft of the main engine are the same shaft, and the extended shaft of the main engine is the rotor of the motor, which is completely direct transmission.
Compared with the direct transmission, the size is much shorter, which facilitates the miniaturization layout of the whole machine. (Missing center bracket and coupling position).
2. Host
The main engine of the oil injection screw air compressor is the core of the whole set, including the compressor and its related accessories, such as oil cut-off valve, check valve and so on.
At present, the screw host on the market is divided into two kinds of single-stage compression and double-stage compression from the working principle. As for the various integrated innovative models, such as all-in-one machines, essentially the working principle has not changed.
The most significant structural difference between single-stage compression and double-stage compression is that single-stage compression has only one pair of yin-yang rotors, while double-stage compression has two pairs of yin-yang rotors.
The difference in principle is that single-stage compression has only one compression process, that is, the gas is inhaled and discharged by a pair of rotors to complete the compression process. The two-stage compression is to cool the compressed gas after the compression of the first stage compressor, and then send it to the second stage compressor for further compression.
At present, the two-stage compression host on the market mainly has two structures, including the upper and lower structure is the most common. The so-called "split" structure of two permanent magnet motors with two hosts still needs to be further tested by the market.
3. Air intake system
Air compressor intake system mainly refers to the compressor suction atmosphere and its related control components. It is usually composed of two parts: intake filter unit and intake valve group.
The intake filter unit is relatively simple in structure, usually composed of an air filter and an intake duct (soft and hard tubes). Some minicomputers do not have an intake duct, or even an air filter housing, and directly install the air filter element on the intake valve. Some units with larger flow rates will also use multiple sets of air filters to obtain better filtration effects and reduce suction resistance.
The role of the air filter is literally to filter the air inhaled by the compressor, which mainly refers to filtering solid particles such as dust and debris in the air inhaled.
The filter element of the air filter is a consumable product, and the maintenance of the screw air compressor "three filters and one oil" is "air filter element, oil filter, oil separator core and air compressor oil".
The intake valve group is installed on the intake port of the compressor host, which is used to control the amount of inhaled air to achieve different working states such as air compressor loading, unloading and proportional adjustment.
An intake valve group usually consists of a valve body, an actuator such as a cylinder, and a control element such as a solenoid valve. The intake valve has a variety of forms, according to the valve body structure commonly used for piston and butterfly.
The piston intake valve uses the piston in the intake valve to control the air intake of the air compressor, usually only open/closed two states, generally used for small flow situations.
The main structure of the butterfly intake valve is a butterfly valve, and the moving part is a valve plate, which is driven by the push rod of the servo cylinder, and the opening/closing of the control valve plate and the opening degree can realize the control of the inlet flow rate. Usually used in large traffic situations.
4. Cooling system
Air compressor cooling methods are air-cooled and water-cooled, air-cooled and water-cooled and no one is good or bad, only applicable and not applicable.
Water cooling requires the owner to have a cooling water system, and air cooling is more flexible, but there are also requirements for good ventilation in the installation site;
The cooling effect in the use of water-cooled models is completely dependent on the cooling water system, if the cooling water system of the owner's enterprise is operating normally, the cooling effect is very stable and reliable. Air cooling is greatly affected by the ambient temperature and installation environment, but usually the design of manufacturing enterprises has taken into account the extreme situation, so the installation according to the requirements can also achieve satisfactory cooling effect.
There is no need for electrical equipment in the cooling process of the water-cooled air compressor, and it does not occupy the energy consumption of the air compressor itself (the circulating cooling water of the owner's enterprise needs electricity is another matter). The air-cooled air compressor needs to be equipped with a cooling fan, which occupies the energy consumption of the air compressor body.
Water-cooled heat exchange efficiency is high, small volume, more concise and compact than air-cooled structure, in addition, because the air-cooled cooling fan, the wind noise is larger during work, so the water-cooled machine noise value is lower than the air-cooled machine.
The medium that the air compressor needs to be cooled is compressed air, and the cooling oil (or air compressor oil, lubricating oil, and coolant all mean the same thing), of which the latter is the most critical, and it is the key to the continuous and stable operation of the entire unit.
Air compressor oil needs to circulate indefinitely in the body, play the role of heat carrier, and bring the heat released by the air in the compressor process and other heat to the cooler, which is taken away by the cold medium (wind or water).
In engineering, air-cooled air compressors almost all use plate-fin coolers, usually air cooling and oil cooling into one, a part of the compressed air (air cooling) and a part of the air compressor oil (oil cooling). The water-cooled also almost all use shell type (or column tube type), oil cooling cooler and air cooling cooler.
The air cooled plate fin cooler is made of aluminum or aluminum alloy material brazed, and the high temperature oil and compressed air flow in the cooler, and the heat is taken away by the forced convection of the cooling fan.
Water-cooled shell and tube type (tubular type) cooler, the hot medium is high temperature oil and compressed air, the cold medium is cooling circulating water. Through heat exchange, the heat is taken away by the cooling water.
5. Oil-gas separation system
In the process of air compression, the "oil injection" of the air compressor is involved in compression, and there must be a system to separate the oil and gas, keep the oil in the body and continue to cycle, and discharge the pure compressed air. This is where the oil-gas separation system comes in.
It is because the separation efficiency of the oil and gas separation system has reached an acceptable level that the oil injection screw model can be widely used.
The oil and gas separation system of air compressor is mainly composed of oil storage tank and oil and gas separator.
Working process: The oil and gas mixture from the main engine exhaust port enters the oil separation tank space, and most of the oil gathers in the lower part of the tank after air collision and gravity action, and then enters the oil cooler for cooling. The compressed air containing a small amount of lubricating oil is fully recovered through the oil separator core, and flows into the low pressure part of the main engine through the throttle check valve.
6. Control system
The control system of air compressor includes logic controller, various sensors, electric control part and other control elements. Figuratively speaking, the air compressor control system is the brain, cerebellum, neural network, muscle tendon, etc., and the air compressor without a control system is just a bunch of parts.
The controller of the screw machine is generally two kinds (almost no pure instrument) : a single chip microcomputer, a PLC. The former is generally produced by a special air compressor controller factory, which is used to meet the general needs of air compressor control, and the logic program cannot be changed. PLC (Programmable controller) is a general industrial controller, which needs to realize the function of air compressor control through its own programming, and can also meet the unique control needs of its own products (for the whole air compressor factory).
Sensors are mainly used in air compressors for pressure and temperature sensors, and of course, some parts will use differential pressure switches.
The electric control of the motor is the main part of the control of the air compressor, in simple terms, it is through the on/off operation of the motor to achieve the control of the air compressor unit. Including a variety of AC contactors, circuit breakers, transformers, relays, etc., generally the electronic control part of the main motor is called the "starting plate".
Frequency conversion technology is more and more widely used in the industry, which is the motor start and stop control, another control purpose: to control the motor speed. This part is completed by the frequency converter or embedded frequency conversion component, and the start/stop of the electromechanical control part of the air compressor that uses frequency conversion is also controlled by the frequency converter, unless it is an air compressor with a dual system of frequency conversion.
In addition to electrical control, there are many mechanical controls on air compressors, such as temperature control valves and minimum pressure valves.