Screw air compressor 7 large system quickly understand a concise tutorial
When it comes to the working principle of the oil-injected screw air compressor, the first thing that everyone thinks of is the three working processes of the screw main engine: suction, compression and exhaust. However, the relevant information of the air compressor is not so complete and detailed.
If the service personnel are not very familiar with the air compressor system process and the working principle of each component, there will be many unnecessary rework in the work, and the unclear description of the fault in the communication with the customer will result in the customer to the individual and the company. Professionalism is questioned. Today we will summarize and summarize how to quickly understand the screw air compressor!
Air compressor working principle: The machine must first press the power switch, and the electric control system can complete the unit's step-down start before it can run normally. (To reduce the impact on the power grid/energy saving and emission reduction, take the star-delta step-down start or frequency conversion. Soft start. The two kinds of step-down starting methods of Yanbian triangle and autotransformer are very rare due to the high cost and technical requirements, so it is very rare to apply on the air compressor. According to the command of the electronic control system, the power system starts to run and starts to establish the system quickly. The pressure is used to ensure the smooth circulation of the lubricating oil; after the internal pressure is established, according to the command of the electronic control system, the air intake system executes the opening command, so that the air compressor is normally inflated (inhalation, compression, exhaust); The post-oil mixture enters the separation system, completes the cyclone separation and separates the lubricating oil and the compressed air through the fine separation of the oil core, and the lubricating oil is returned to the bottom of the separation system (oil and gas barrel); the compressed air flows through the minimum pressure valve and is cooled by the cooler. Discharge the machine, the pressure control signal pressure point is generally set to the side of the cooler exhaust or Above (because the cooled compressed air has the least damage to the pressure sensor, and the upper part is free of condensed water, the detected pressure value is more accurate); the lubricating oil flows out of the oil and gas tank and flows into the cooler through the temperature control valve (if the temperature is lower than the valve) When the core is turned on, the lubricating oil is directly injected into the screw main body through the oil filter. The cooled lubricating oil is returned to the oil filter, and the impurities are filtered and injected into the compression chamber of the screw main body to assist the completion of the compression process.
According to the working process of the air compressor, the working principle of the air compressor and the principle of each component can be quickly, conveniently and comprehensively memorized. In order to facilitate the understanding of the working principle of the air compressor, the air compressor system flow is first removed. The air compressor can be divided into the following seven systems: electronic control system, air intake system, power system, separation system, cooling system, piping system, silencer system. It can be seen from these seven systems that there is a direct relationship between the first six systems and the air compressor system flow.
1
Electronic control system
The electronic control system consists of computer version, emergency stop button, transformer, sensor, contactor, transformer, fuse, terminal block, solenoid valve, wire (old battery box: button switch, thermal relay, time relay, intermediate relay, Components such as indicator lights).
The working principle of the electronic control system: after the computer version gives the start command, the star contactor works, and the motor starts running; after the motor speed is stable, the triangular contactor is operated according to the delay of the computer version (the star contactor is disconnected) : A contactor can be simply understood as a switch because it is a component that allows the circuit to be connected or disconnected. According to the "Star Triangle" startup principle, three contactors are generally used to complete the "star triangle" conversion (two contactors can also be used to complete the "star triangle" conversion).
If you pay attention to the configuration of the contactor in the electric box, you can find that the contactor of the "star" operation generally has less power than the contactor of the "triangle" operation, because it is connected to the star, the starting voltage applied to the stator winding of each phase. Only when the delta connection is directly started, the starting current is 1/ when the delta connection is directly used, and the starting torque is only 1/3 when the delta connection is directly started. Therefore, this step-down starting method is only suitable for light load or no-load start (the biggest advantage of Y△ step-down start-up is that the device is simple and the price is low, so it is widely used. The disadvantage is that it is only used for normal operation. The motor with Δ connection has a fixed step-down ratio and sometimes cannot meet the startup requirements).
The PC version can monitor the operating data such as pressure, temperature and current (the inverter can also monitor the input voltage, bus voltage, speed).
2
Intake system
The air intake system consists of air filter assembly, intake hose, intake valve, solenoid valve, relief valve, pressure regulating valve, proportional valve, control line and other components.
The working principle of the air intake system: the solenoid valve performs the electric control system to give the loading/unloading command to open/close the intake valve, the air is pressed into the air filter assembly, flows through the intake hose and finally flows into the screw main body through the intake valve ( Because the intake port of the main engine is negative pressure, a large amount of air will be pressed into the main unit after the intake valve is opened.
The air filter assembly is composed of an air filter core, a muffler casing, etc.; the air filter element is used to block external impurities from entering the screw main body, avoiding the internal screw of the main body from being sucked by inhaling impurities, or clogging the filter due to inhalation of dust to form sludge (oil filter) , oil) and cause unnecessary downtime to the machine.
The control pipeline is connected to the oil and gas tank (cleaned compressed air after separation) to control the opening and closing of the intake valve.
3
power system
The power system consists of the screw main unit, the drive motor, the transmission (belt, pulley or coupling), and the connecting parts (standard parts such as bolts and washers).
The working principle of the power system: the motor executes the running command (the star-delta step-down start), the motor drives the screw main unit through the transmission device, and the screw main body rotates to start the suction compression and exhaust (the screw main engine inlet is in a negative pressure state during operation, so There will be a natural inhalation phenomenon. The screw main unit is injected with lubricating oil during compression to improve the working efficiency of the main engine. As long as the screw main unit rotates, there are working states such as suction, compression, and exhaust.
Description: The five major functions of the lubricating oil: sealing the compression chamber to reduce the leakage (sealing), absorbing and taking away the compressed heat (cooling), forming an oil film on the compression chamber and the bearing surface to avoid direct metal contact (lubrication), lubricating oil It can wash away the impurities that are not filtered out by the intake air (cleaning), and the super strong adhesion of the lubricating oil can well block the noise exposure (noise reduction).
Description: The common mature technology of the transmission has three driving modes, one is belt transmission, the other is coupling transmission, and the other is coaxial transmission through the main motor (the rotor of the motor is fixed on the protruding shaft of the main rotor of the screw main unit). ), the power system is controlled by an electronic control system.
4
Separation system
The separation system consists of oil and gas barrels, oil separators (oil cores), internal pressure gauges, differential pressure gauges, minimum pressure valves, blowdown valves, sight oil mirrors, oil return pipes, and joints.
The working principle of the separation system: the oil and gas mixture is injected into the oil barrel through the air inlet, the oil and gas mixture is separated by primary separation (rotation separation) in the oil barrel, and the lubricating oil is returned to the bottom of the oil and gas barrel. After the primary separation, the oil droplets are returned to the bottom of the oil and gas barrel. The compressed air is filtered and separated by the oil separator (oil core), and the clean compressed air flows through the minimum pressure valve to the cooling system and finally exits the machine.
After the oil separator (oil core) is separated and filtered, a small amount of lubricating oil is stored at the bottom of the oil, and is directly returned to the screw main body through the secondary oil return pipe for lubricating the bearing. The secondary return pipe is connected to the screw main machine position and has a return oil check valve to prevent the lubricating oil in the main engine from flowing back into the oil inside when the machine is stopped, causing oil flying phenomenon.
The lubricating oil flows into the oil filter through the temperature control valve or flows into the cooling system to cool down and enters the oil filter. After filtering, it enters the screw main machine cycle again.
5
cooling system
The cooling system consists of a plate fin cooler, a cooling fan (axial flow/centrifugation) and an air hood.
How the cooling system works: As the name implies, the cooling system is the heat generated by the cooling air compressor. The air cooler uses the air around the air compressor station as a medium for heat exchange, and exchanges heat between the lubricating oil and the compressed air of the air compressor, thereby forcibly taking away the heat and reducing the lubricating oil and compressed air in the air compressor. temperature.
The heat dissipation effect is mainly determined by the heat exchange area and air volume of the heat sink of its components. Simply: the same heat exchange area, the greater the air volume, the better the heat dissipation effect; the same air volume, the larger the heat exchange area, the better the heat dissipation effect.
Description: Here is the air-cooled air compressor.
6
Piping system
The pipeline system consists of oil and gas pipe, hot oil pipe, cold oil pipe 1, cold oil pipe 2, exhaust pipe and control pipe (addition and unloading control), secondary oil return pipe and so on.
The pipeline system connects the intake system, the power system, the separation system, and the cooling system to form a closed-loop working system, thereby ensuring normal circulation of fluids such as oil passages and gas passages, thereby ensuring normal operation of the machine.
7
Silencing system
The muffler system consists of chassis, bracket, frame, door panel, muffler cotton, sealing strip and other parts.
The main function of the muffler system: according to its naming, it can be clear, mainly to reduce the effect of noise; secondly, it can beautify the machine (various and simple shapes, various pipes and lines can be hidden inside the muffler system. The first six work The components of the system's work platform are installed on the muffler system.
The ordering of these seven parts is based on the air compressor workflow. Then understand the working process of the lower screw air compressor: after the start button is turned on, the electric control system runs, the intake system actuator starts to work, and the intake valve is opened to start normal air pumping. The air enters the power system through the air filter to start the operation and mixes with the cooling oil in the main engine. The oil and gas mixture is compressed by the screw main body and then flows to the separation system to separate the lubricating oil from the compressed air. The lubricating oil is cycled inside the machine; The separation system "oil drum" is directly returned to the screw main body; after the temperature rises, it is cooled by the cooling system and then returned to the screw main body through the oil filter.
