An air compressor is an energy conversion device that converts electrical energy into air pressure energy. The compressed air it produces provides a variety of pneumatic tools and equipment power to serve the mine production and construction. It occupies an important position in the production and construction of coal mines and is known as one of the four major mechanical equipments in coal mines. Its operating performance directly affects the production efficiency and safety of coal mines. Therefore, real-time monitoring and safety protection of the entire pressure blower room can further improve the safety, reliability and utilization of the equipment, improve the management level of the coal mine, and improve the labor environment of the workers to produce good economic and social benefits. 2 Air compressor frequency conversion system overview. A coal mine is equipped with 3 sets of screw air compressors, two of which are 20m3 /min type and one 40m3 /min. The power supply of the pressure blower room is specially set to 6kV transformer and power distribution station. The 6kV main power supply of the substation is two circuits, one working, one standby, and manual switching after the fault. The 6kV system uses a single bus section operation mode. The pressure blower room is designed and installed with two 20m3 /min, 0.8Mpa compressors, and each compressor is equipped with one 110kW asynchronous motor. 1 set of 40m3 / min, 0.8Mpa compressor, compressor with 1 220kW asynchronous motor, the current operation mode asynchronous motor is directly started, usually 40 cubic compressor has been running, when the wind pressure is insufficient, then manually start a 20 cubic space Press, another air compressor as a spare. The long-term idling of the air compressor leads to a large amount of energy waste, and on the other hand, increases the production cost of the mine. In order to reduce energy consumption and save costs, the inverter is driven by an inverter to drive the motor according to the requirements of air volume and wind pressure, saving a large amount of electric energy, which is to save production costs. According to the empirical data and the production situation of each mine, the energy saving is about 40%, and the investment of equipment is recovered in the energy saving of 2-3 years. Several requirements were put forward for the transformation of the old system. (1) Drive the motor with the inverter. (2) The three air compressors can be controlled separately, which can realize the direct start operation of a single machine. (3) Three air compressors can realize linkage control. When the normal 40-cube air compressor can not meet the wind pressure requirements, a 20-cubic air compressor is automatically started. One air compressor can not meet the wind pressure. Start another 20 cubic air compressor when required. (4) The three air compressors still need to be guaranteed to be independent. Each unit can be power-off and repair, and does not affect the operation of the other two. The linkage logic of the air compressor still needs to ensure optimal operation. (5) The operating status of the three air compressors shall be monitored in the total duty room, including all pressure and temperature signals, inverter voltage, current, motor speed, etc. 3 system structure. One of the three air compressors is in long-term standby. For cost reasons, two inverters are used to drive two common air compressors, one 250KW inverter drives 220kW motor, and one 132KW inverter drives 110kW motor. The backup compressor is still in direct start mode. From the perspective of integration and network, the centralized control system of the pressure blower room is designed to make the system safe, reliable, economical and easy to operate. The system is a two-stage step-by-step computer distributed control system that detects, displays, controls, protects, and manages the operation of the pressure blower. The system is divided into two parts: the operation station (host computer and operating PLC) and the field control station. The field control station adopts SIEMENSS7-300 series PLC, and the operation station adopts SIEMENSS7-200 series PLC. Two inverters, field control station (master PLC) and operation station (operation PLC) Forming the DP network, the control data and operation feedback data of the inverter interact with the field control station through the DP network. The operation station mainly performs data interaction with the field control station, and transmits control commands and operational status feedback. The programmer, the touch screen, the field control station, and the operation station form an MPI network. The programmer can program and debug all three parties, and the touch screen collects the operation data of the field control station and the operation station for human-computer interaction. 4 air compressor control function is realized. 4.1 Start function. Before the host starts, confirm that the solenoid valve of the outlet pipe of the pressure blower is in the closed state. The system checks whether the inverter is in the standby state, receives the start command from the driver's station, the controller starts the inverter, and the air compressor starts to run when the pressure reaches the set value. At 0.6MPa, the current air compressor speed is maintained, the air compressor outlet valve is opened, and the air compressor is put into operation. The S7-300 can realize pressure closed loop, and the closed loop output controls the speed of the inverter to maintain a constant pressure. In addition, the working status of a single air compressor is uploaded to the master control PLC, and the master control PLC determines whether it is necessary to start another air compressor. 4.2 automatic protection. The electronic control system should be equipped with exhaust overpressure/overtemperature, inverter fault, overheating of lubricating oil, overheating of bearing bush, low cooling water pressure and low pressure of lubricating oil. (1) Main circuit failure: When the motor main circuit is overcurrent or overvoltage due to reason, the control system should automatically stop and fully unload. (2) Cooling water system failure: This technical specification requires the cooling water pump and the fan to be locked. When the inlet pressure of the cooling water is lower than the lower limit set by the pressure regulator (two levels in total), the control system should automatically follow the situation. Sound and light alarm or shutdown and full unloading. (3) Lubricating oil system failure: This technical specification requires the lubricating oil pump and the fan to be locked. When the lubricating oil pressure is lower than the lower limit value set by the pressure regulator (two levels in total), the control system should automatically alarm according to the situation. Or stop and fully unload. (4) Exhaust overrun: When the compressor is in the load regulation state, when the I (II) class exhaust pressure exceeds the upper limit set by the pressure regulator (two levels in total) When the control system should automatically emit an audible and visual alarm or stop according to the situation and fully unload. (5) Temperature overrun: The protection range of temperature overrun includes Class I exhaust, Class II intake, exhaust, lubricating oil, aftercooler, front, middle, and rear bearing bush temperatures, when the above temperature exceeds the temperature regulator When the upper limit value is set (two levels in total), the control system shall automatically issue an audible and visual alarm or stop and fully unload according to the situation. 4.3 Parameter measurement. Including pressure measurement, temperature measurement, motor electrical parameter measurement. (1) Pressure measurement: The range of pressure measurement includes exhaust pressure, lubricating oil pressure, cooling water inlet pressure, tank pressure, and air filter inlet and outlet differential pressure measurement. The pressure measurement uses a pressure sensor plus a pressure transmitter and provides the measured data to the PLC system. (2) Temperature measurement: The temperature measurement range includes exhaust temperature, lubricating oil temperature, aftercooler drain temperature, gas tank temperature and front, middle and rear bearing temperature. Temperature measurement uses temperature sensor plus transmitter and gives The PLC system provides the measured data. (3) Electrical measurement of the motor: The electrical measurement range includes the main circuit current of the motor, active energy, power factor, excitation voltage, and current. 4.4 Single and three automatic operation control functions. The control system is equipped with a single-unit power distribution and control system for each compressor, including a frequency conversion cabinet. When the pressure blower is running in a single machine, it can realize the startup, normal stop, emergency stop, automatic adjustment and other control of the host, and realize various automatic protection and parameter measurement for the host. The system should be able to realize automatic interlock control of 3 pressure fans, automatically control the start of the pressure fan according to changes in environmental conditions and production conditions, normal stop, emergency stop, load regulation, and at the same time realize various automatic protections for the host, and Parameter measurement. The three-machine interlock control adopts the PLC system, and the three-machine joint control cabinet and the centralized control console are set. 4.5 system data recording function. The system data logging function enables real-time data logging for query run status and failure analysis. In the historical data query interface, the upper machine can query the exhaust pressure, wind pressure, exhaust temperature, wind package temperature and drainage temperature to analyze the real-time data. The main faults in the system are communication faults, air compressor faults, inverter faults, and sensor faults. Communication faults are divided into two types in this system, one is MPI communication failure, and the second is DP communication failure. The system has a self-diagnosis communication fault function. When starting, the inverter and the main control loop are normal, the air compressor still does not start, check whether the air compressor itself shows a fault. The motor cannot start after the inverter has failed. At this point, check the fault code displayed on the operation panel of the inverter to find the source of the fault alarm information on the manual. During the operation of the air compressor, the signal of one of the sensors is not monitored, the sensor line is checked for a problem, or a new sensor is replaced to check whether the sensor is damaged. 5 Conclusion. The system has been stable and reliable since it was put into operation for one year, and has met the needs of production and achieved the intended purpose. Practice has proved that the frequency converter is used in air compressors with high reliability and remarkable energy saving effect, which greatly reduces the advantages of equipment maintenance workload and maintenance cost, and has obvious direct and indirect economic benefits. Customized Box,Custom Gift Boxes,Black Gift Box,Custom Printed Boxes Jiangmen Yingzhihui Electronic Commerce Co., LTD , https://www.yzhprint.com
Innovative Presupposition and Application of Air Compressor Structural Components
1 Overview.