Practical air compressor basics
Air compressor overview:
Air compressor: A machine that compresses gas to increase gas pressure or deliver gas.
Role: blowing gas production, refrigeration and separation, driving power, synthesis and polymerization, gas delivery.
Applications: Electronics, automotive, steel, plastics, molds, hardware, pharmaceuticals, chemicals, food, beverages, furniture, printing, diving, fire protection, glass, environmental protection, biology, energy, ceramics, cement, mining, power plants, petrochemicals, Ships, military workers, etc.
Common terms for air compressors:
Pressure pressure: The discharge pressure usually given on the compressor nameplate is gauge pressure, not absolute pressure.
Common pressure unit: bar, MPa, the air compressor industry said "kilogram" means "bar", that is, 1 kg means 1bar, 1MPa (MPa) = 1000kPa (kPa), 1bar (bar) = 0.1MPa.
Volume flow: In China, it is also called the displacement or nameplate flow. The volume of gas discharged by the air compressor per unit time is converted into the intake state, that is, the volume of the suction. According to the national standard, the actual discharge of the air compressor. The gas volume is ±5% of the nominal flow rate.
Commonly used units: m3/min, L/s.
Gas content: The mass of oil (including oil droplets, suspended particles, oil vapor) contained in compressed air per unit volume. Generally speaking, the PPM is the weight ratio unit: PPM, one millionth of a kilogram is 1 milligram. .
Pressure dew point: refers to a gas with a certain pressure cooled to a certain temperature, the unsaturated water vapor contained therein becomes saturated steam, and this temperature is the pressure dew point of the gas. Atmospheric dew point refers to the temperature at which the gas is cooled to a level of saturated water vapor at a standard atmospheric pressure. In the air compressor industry, the dew point indicates the degree of dryness of the gas.
Specific power: refers to the power consumed by the unit volume flow of the compressor. It is an important indicator for evaluating the energy efficiency of compressors. Air compressor specific power unit: KW / m3.
According to the standard GB19153-2009 "Volume-type air compressor energy efficiency limit value and energy efficiency rating", the air compressor energy efficiency rating is divided into 4 levels:
Level 1 (optimal level), Level 2 (energy saving evaluation value), T level (target energy efficiency limit value), and level 3 (energy efficiency limit value). Among them, level 1 has the highest energy efficiency, and level 3 is lower than production and sales. Class T is the target energy efficiency rating, and its energy efficiency is better than level 3. It has replaced the level 3 energy efficiency value since December 1, 2013.
Level 1 reaches the international advanced level, the most energy-saving, and the lowest energy consumption;
Level 2 is more energy efficient;
Level 3 High energy consumption is an indicator of market access.
Air compressors are divided into: 1, speed type; 2, volumetric type; volumetric type is divided into rotary type and reciprocating type; rotary type: (1) rotor type; (2) screw type; (3) sliding piece type. Reciprocating type: (1) piston type; (2) membrane type.
Speed type: It relies on the action of gas to rotate the impeller at high speed to obtain larger kinetic energy, and then rapidly decelerates in the diffuser, so that the kinetic energy of the gas is converted into potential energy, thereby increasing the gas pressure. The speed type mainly has two basic types: centrifugal type and axial flow type.
Volumetric type: It is the purpose of increasing the gas pressure by directly compressing the gas to reduce the volume of the gas, and the volumetric type is divided into two types, rotary type and reciprocating type, according to the characteristics of the cylinder measuring piston. Rotary type: The piston makes a rotary motion. The piston is also called dry-drying. The number of rotors varies, and the cylinders have different shapes. The rotary type includes a rotor type, a screw type, a slide type, and the like including a piston type air compressor.
Reciprocating: The piston reciprocates and the cylinder is cylindrical. Reciprocating type includes piston type and membrane type, of which piston type is the most widely used type.
Screw machine working principle:
The working process of the screw air compressor is divided into four processes of suction, sealing and conveying, compression and exhaust. When the screw rotates in the casing, the screw and the tooth groove of the casing mesh with each other, the air is sucked by the air inlet, and the oil is also sucked, and the sucked oil and oil is sealed and conveyed to the exhaust port due to the rotation of the meshing surface of the tooth groove; During the process, the meshing gap of the tooth groove gradually becomes smaller, and the oil and gas is compressed; when the meshing surface of the tooth groove rotates to the exhaust port of the casing, the higher pressure oil and gas mixed gas is discharged from the body.
Screw machine switching machine operating specifications:
First, precautions before starting:
1) Check the three-phase power supply and confirm that it is normal.
2) Open the machine door lock and observe the oil level of the air compressor. At this time, the oil level should not be lower than the lowest position, otherwise the coolant should be replenished to the normal position.
3) Turn on the controller power lock and observe if there is any abnormal display on the LCD. “Device is down” is displayed, indicating normal.
4) Open the air compressor outlet valve.
5) After the above check is correct, press the air compressor start button, that is, the (ON) button, the air compressor can work normally.
Second, the operation notes
1) After starting the machine, observe the air compressor for 3 to 5 minutes. Observe whether there are abnormal noises and vibrations, whether there is any leakage of oil or gas, or you should stop the inspection immediately.
2) There are pressures in the pipeline and the container during the rotation. It is forbidden to loosen the pipeline or plug and open the unnecessary valve.
3) Pay attention to the oil level during operation. It is normal for the oil level to decrease after the machine is running. If the oil level is not visible and the exhaust temperature is as high as 100 degrees, stop immediately. Observe the oil level after 10 seconds of shutdown, if not enough, replenish the coolant when there is no pressure in the system;
4) After the gas is cooled by the cooler, a certain amount of condensed water will be generated, which should be discharged regularly, otherwise the water will be carried into the rear system by the gas; according to the weather, the discharge time can be flexibly adjusted, generally in summer. 5) During operation, at least daily parameters such as voltage, current, outlet gas pressure, outlet exhaust temperature, oil level should be recorded for future inspection and reference.
Third, the precautions for shutdown
1) Press the OFF button first. After 10 to 15 seconds, the intelligent controller stops according to the preprogrammed program. The motor will stop. Avoid direct shutdown of the air compressor under heavy load;
2) If necessary, turn off the power lock switch (red button) and turn off the power lock.
3) After the air compressor is stopped, it cannot be started immediately. It takes about 1~2 minutes, and the system will automatically drain the internal pressure to prevent the heavy load from starting to damage the motor.
4) After the machine is commissioned, adjust the pressure and other parameters according to the actual situation, and set it to the fully automatic control mode. Under normal circumstances, users do not have to adjust themselves.
Piston machine operating specifications
First, precautions before starting
1) Check the three-phase power supply and confirm that it is normal.
2) Check the belt tension.
3) Check if the oil level is normal.
4) Check if the fuselage leaks oil and the joint is loose.
5) Turn on the power switch to start the test intermittently. If there is no abnormal noise, press the air compressor start button to work normally.
Second, the operation notes After the boot, observe the air compressor for 3 to 5 minutes, and then officially run.
1) Observe whether the pressure switch is operating normally.
2) Observe the abnormal sound and vibration.
3) Whether there is leakage of oil or gas, otherwise it should be stopped immediately.
4) Manually check if the air inlet is normal.
Third, the precautions for shutdown
1) First press the OFF button to stop.
2) Turn off the power if necessary.
Screw machine oil:
Function: anti-lubrication, anti-rust, anti-corrosion, sealing, cooling.
Classification: generally consists of two parts: base oil and additive, often divided into mineral oil, synthetic oil, light, medium and heavy load three levels.
Use: L-DAG, viscosity 15#, 32#, 46#, 69#, 100#, 150#
L-DAH, viscosity 32#, 46#, 100#, 150#.
Note: It is forbidden to mix and use different brands and models. It is forbidden to mix new and old ones and must be replaced in time.
Common failures of screw machines:
First, high temperature or high temperature shutdown
Poor quality oil or oil, lack of oil; oil filter blockage or poor oil path; fan motor failure (contactor failure); air filter blockage; temperature sensor failure; poor heat dissipation of the cooler or blockage of the heat sink; The host is damaged.
Second, the whole machine consumes a large amount of oil
Non-exhaust oil content is high: lubrication pipe leakage or seal failure ()
High oil content: whether the return pipe is unblocked;
Oil level is too high; long-term low-pressure operation; oil component failure; oil emulsification or deterioration; precision filter failure;
Third, electrical failure
Whether the electrical part of the action is normal (high voltage, low, poor contactor); motor failure; poor contact of the power switch.
Fourth, do not load gas production
Intake valve failure; solenoid valve failure;
Other faults: control air leak/blockage, loose control wiring, and controller button failure.
5. Abnormal shutdown
Non-overload shutdown: high temperature shutdown, power failure, loose wiring, loop relay or insurance failure;
Overload shutdown: Exhaust pressure is too high, thermal relay failure, lubricating oil viscosity, main motor failure, motor or contactor wiring loose, host failure, set value is too small.
Always turn off the power and completely relieve the pressure during maintenance.
Common faults in piston machines:
First, the sound is not normal
The clearance between the piston and the cylinder head is too small and directly impacts;
The piston rod and the piston connecting nut are loose or tripped;
Metal fragments fall into the cylinder;
Internal crankshaft bolts, nuts, connecting rod bolts, crosshead bolts loose, tripped, broken, etc.;
The shaft diameter is worn and the gap is increased;
Bearing or crankshaft wear is large;
The cross pin and the bushing have a large clearance or a large wear;
The belt is loose.
Second, do not breathe or slow exhaust
The intake valve or drain valve fails; the check valve is broken; the piston and piston ring are worn seriously.
