Application Measures of Shanxi Coal SHAN Screw Air Compressor on Electric Shovel Tian Yongfa (Open-air Equipment Maintenance Center of China Coal Pingyi Group Co., Ltd., Zhangzhou 036000, China) and automatic lubrication system; also used for air horn, boarding ladder, clean filtration Auxiliary equipment such as the device, as well as adjusting the driver's seat. This paper introduces the working principle of Sullair EMD08HH/30/A screw air compressor and the fault handling in its application.
The electric shovel used in the early days of Ping'an Antaibao Mine is a piston air compressor. Due to its noise, low efficiency and high failure rate, it has been changed to a screw air compressor (having a simple structure, Small size, less wearing parts, reliable operation, long life, simple maintenance, etc.).
1 The working principle of the screw air compressor works.
EMD08HH/30/A: power is 30HP; voltage is 380V; type is twin screw type; rated displacement is 150psi; cooling method is air cooling; lubricating oil uses life force 24K. Screw compressor is volumetric gas compression machine, volume The change is achieved by a pair of rotors of the compressor being rotated in the casing. It can be seen that in the body of the compressor, a pair of intermeshing helical rotors are arranged in parallel. During operation, the rotor rotates clockwise and the other rotor rotates counterclockwise. Generally, a rotor having a convex tooth outside the pitch circle is called a male rotor or a male screw (5*; a rotor having a concave tooth in the pitch circle is called a female rotor or a female screw (6*. male screw and female screw male screw) The asymmetrical shape of the basic structure of the female screw-screw air compressor is just matched with the pressure condition of the fuel-injecting air compressor. Generally, the male screw is connected with the motor, and the male screw drives the female screw to rotate. At the end, open the orifices of the shape and size, one for suction, called the inlet, and the other for exhaust, called the exhaust.
2 Air compressor system consists of screw air compressor consists of suction system, exhaust system, cooling lubrication system and control system. see.
D suction system: mainly composed of air filter and intake control valve. During operation, the air passes through the filter core and enters the compressor working chamber through the intake valve. Granular dust and airborne impurities are the first natural enemies of screw air compressors. The air filter element is the first line of defense against the entry of fine dust particles into the body. If the air filter element fails, the particulate dust in the intake air is not well filtered. Entering the host cooling and lubrication system will cause the cooling oil to become dirty and the exhaust temperature to be high. Blocking oil filter, oil and gas separation core pressure difference, control valve failure, reducing the life of the host, in serious cases will cause the host to die.
Square exhaust system: consists of oil and gas separator, minimum pressure valve, aftercooler, water gas separator and connecting pipeline. After the compressed oil and gas mixture enters the oil separator for oil and gas separation, the separated compressed air enters the cooler through the minimum pressure valve, and after cooling, the water is separated by the water separator to enter the gas supply pipeline. The oil and gas mixture enters the oil reservoir and strikes the curved surface. The flow rate is greatly reduced, the flow direction changes, and large oil droplets are formed. Most of them fall into the bottom of the tank because they are heavy. The remaining part of the oil is separated by two separate cores, deposited at the bottom of the filter element, and returned to the compressor main unit through the return line. After the pressure reaches 60 psi (4.2ba), the minimum pressure valve opens and the gas is delivered. The minimum pressure valve prevents gas backflow when shutting down or unloading.
Shanxi coal SHAN 5 - radiator; 6 - host pressure sensor; 7 - vent valve; 8 26 * muffler; 27 * water gas separator; 29 * exhaust pressure sensor; 37 * oil filter.
System composition of screw air compressor (working principle diagram) 3) Cooling and lubrication system: It consists of oil cooler, temperature control valve, oil filter and connecting pipeline. a. Oil cooler: used to cool high temperature lubricants, the efficiency of which will affect the exhaust temperature (T1) of the main engine. b. Temperature control valve: It consists of two parts: valve and temperature control component. The temperature control components include special expansion temperature paraffin wax and copper shell. At a specific phase transition temperature, the expansion stress of the expanded paraffin is fixed, much larger than the thrust required by the thermostatic valve. The expanded paraffin is sealed in the casing, and when the temperature rises to the melting point of the paraffin, the volume expands to push the ram. The slide valve that drives the temperature control valve is moved; when the temperature is lowered, the paraffin is cooled and contracted, and the valve is reset under the spring rebound. The temperature control valve has a large thrust, and the paraffin wax inside the component can reach more than 200 atmospheres, and the linearity of the stroke temperature curve is good, so the temperature control ability is strong, the rigidity of the component is large, the strength is high, and the service life is long. The lubricating oil flows out of the oil reservoir and enters the temperature control valve. When the oil temperature is lower than the set temperature, the oil does not pass through the cooler and directly enters the host; when the oil temperature is higher than the set value, the oil passes through the cooler and is then sent to the host. If the oil temperature is higher than 235*F (113*C), the temperature sensor at the bottom of the oil collector will cut off the air compressor motor power. c. Oil filter: Its function is to filter impurities in the oil to prevent solid impurities from entering the main machine and damaging the main bearing and the rotor.
4 control system: mainly used to adjust the amount of intake air, so that the gas supply amount matches the gas consumption. The control system includes: an intake control valve, a pressure regulator, a start solenoid valve, a loading/unloading solenoid valve, a shuttle valve, a vent valve, and the like. The air compressor will continue to compress the air at the fastest rate while forming the system air pressure. When the system pressure approaches its maximum set point, the air compressor intake control valve will begin to close and reduce the compression speed. When the pressure is around 160 psi (11.2 bar), the valve begins to close. As the system air pressure continues to rise, the intake valve will remain closed. At 170 psi (11.9 bar), the intake control valve should close completely and stop compression. The air compressor will continue to operate, reducing the system air pressure to 170 psi if necessary, and the intake control valve will begin to open and increase the amount of compression. The air compressor thus adjusts the amount of compression and produces a near constant system pressure of 170 psi, while the air compressor does not need to be stopped, unloaded, and restarted. The intake control valve is controlled by the pneumatic pressure within the control line. The control line air pressure rises, the intake control valve closes; the control line pressure drops, and the intake control valve will open accordingly so that more air can enter the air compressor.
The control system is divided into starting conditions, loading conditions, adjustment conditions, and unloading conditions. a. Start-up condition: start mode is YA conversion start (set time 5, within 5s conversion time, the intake control valve opens under the pressure difference generated by the screw rotation, a small amount of control gas will pass the load/unload solenoid valve will The intake control valve is closed. At this time, the load/unload solenoid valve has no electricity, the vent valve is open to the atmosphere, and is in the exhaust state, and the air compressor is lightly loaded. b. Loading condition: 5s, the load/unload solenoid valve is powered The intake control valve is fully open and the unit is in the loading mode. When the system pressure reaches 60 psi, the minimum pressure valve opens and begins to supply air to the system. Before the set pressure is reached (typically 160psD, the unit runs directly in this state). Description: The loading/unloading solenoid valve is a normally open solenoid valve, no electricity is always on, and the power is off. c. Adjustment condition: If the gas consumption is less than the rated air supply of the unit, the line pressure will rise above 160 psi. This pressure can be overcome. The spring pressure of the pressure regulating valve, the pressure regulating valve is opened, the control gas will act on the intake control valve, partially close the inlet valve, and reduce the intake air amount to match the gas consumption.
At this point, the pressure will pass through the venting orifice of the pressure regulating valve to keep the system air pressure stable. When the line pressure is between 160170 psi, the control system is always adjusted in the above manner. d. Unloading condition: When the air compressor is stopped manually or the sudden power failure causes the machine to stop, the loading/unloading solenoid valve is de-energized, and the control gas will pass through the loading/unloading solenoid valve to reach the control terminal P end of the vent valve, so that the oil collector The gas inside is discharged through the exhaust end I end of the vent valve. Note The air compressor will only be unloaded during manual shutdown or power failure, otherwise it will remain in the “adjustment conditionâ€.
3 common faults and analysis and processing) Fault description: the air compressor is not loaded, and the pressure cannot be established. Cause analysis: a. First check if air intake. Place your hand on the air filter inlet. If there is no obvious suction feeling, the air filter is clogged. Solution: Replace the air filter. b. If there is a large amount of gas entering, it means that the system has leaked Shanxi coal SHAN. When the air compressor is unloaded, the gas in the main engine can only pass through the exhaust end of the vent valve (Hou Chaojun, Guo Lisheng, Gou Panfeng. Coal Road Anchor Support Network. Xuzhou: China University of Mining and Technology Press, 1999. Kang Hongpu, Wang Jinhua. Coal road bolt support theory and complete technology network. Beijing: Coal Industry Press, 2007. Editor: Liu Xinguang
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