The air compressor is the core equipment in the air separation oxygen plant, and the normal operation of the air compressor is inseparable from the operation of its lubricating oil system. The lubricating oil system provides clean, temperature-controlled oil to the gearbox and motor bearings. The internal heater ensures that the tank temperature is maintained above 1000F. The system automatically controls the gearbox oil temperature to 900F, which is the required temperature for starting. Above, the fuel tank is equipped with a low oil level alarm and shutdown function. The operation of the oil pump determines the stable operation of the lubricating oil system. In Laigang Tianyuan Gas 5 Oxygen Generator, since the Drum Air Compressor does not have its own main oil pump, the working mode of the two auxiliary oil pumps is used to ensure that the air compressor can run continuously and reliably for a long time.
1 Defects of the traditional control scheme In the compressor system, the traditional control H mode is: the main oil pump. The other is an auxiliary oil pump. At system startup. The main oil pump always follows the start-up operation. Under normal working conditions, the auxiliary oil pump will not operate. Only when the main oil pump fails or the instrument detects low oil pressure, the auxiliary oil pump is put into operation. This will cause one job to be too frequent and the other to be underutilized. The main oil pump will have a shorter service life due to mechanical wear and other factors; the auxiliary oil pump may be damaged due to equipment corrosion and electrical failure due to long-term non-operation.
jobs.
2 Determination of control scheme 2.1 Hardware configuration system adopts Siemens S7-400PLC, with one operator station and engineer station, with Windows2000 as the transport T platform, and realizes automatic control of the whole process through standard TCP/IP protocol Ethernet. , data communication and PC management, can completely monitor the production of the entire system. The hardware configuration is as shown.
Hardware Configuration Schematic The system can set the run interrupt scan cycle and priority for each task. Depending on the compressor operating conditions, the controller responds quickly by calling different task interrupts. Therefore, the controller can meet the requirements of complex regulation loop control and fast interlock control of the switch quantity, so that one controller can cover the control requirements of all parts of the factory.
Automation Application 2013 4 丨1 DCS control system adopts Siemens-specific communication module, which is a fast Ethernet module conforming to TCP/IP protocol, which enables the system to connect with the factory LAN without adding equipment, and improve the communication speed of the network; Support OPC data exchange standard, make data exchange between system and third-party database or software easier, and provide powerful guarantee for future plant management and control integration. 2.2 The key idea of ​​control ideas is how to balance the two units of the system. Effective, that is, the mutual rotation of the working machine and the standby machine can be realized. In the oil pump system, the working oil pump is first started. When the working machine malfunctions or the oil pressure is lower than the set value, the system starts the standby oil pump, and when the oil pressure is normal, The working oil pump stops working, and the working oil pump at this time is automatically converted into the standby oil pump, and the standby oil pump is automatically converted into the working oil pump, and the next start preparation is ready. When the system is again required to start, the started working oil pump is the previous time. The spare oil pump at work, while the previous working oil pump is now used as backup oil Waiting for work, achieving two-machine rotation work, achieving work balance 3 control scheme implementation in Laigang Group Tianyuan Gas 5 air separation oxygen unit, using Siemens DCS control system, using PCS7 programming tool CFC to achieve two The alternate cycle control design of the oil pump provides two ways of manual automatic. The independent mode is manual control. The mutual backup mode is the automatic circulation control of the oil pump. When the sealing gas pressure is PIAS4407A>0.2MPa, PIAS4408A>0.2MPa, TIAS4407A>25*C3 When all the conditions are met, the screen shows that the oil pump is allowed to start (see the oil pump control screen). Before the vehicle is driven, the oil pump control is driven to an independent state. After the oil pump is started, the operator starts an oil pump and hits the mutual backup mode while storing the memory block. The first start state of the oil pump will be memorized and used as the working pump; when the PIAS4406A is 0.35 MPa, another standby pump will be automatically started, and the memory block will be stored to store the state of the second oil pump. After the two oil pumps work simultaneously, When the oil pressure PIAS4406A>0.45MPa, the first oil pump is automatically stopped, and the second oil pump becomes the measured value of the working pump system according to PIAS4406A. Cycle start and stop of two oil pumps, to a large extent to ensure that at least one oil pump can run, greatly improving the stability and safety of the equipment. 13 Oil pump alternate mode control process, as shown in the oil pump control screen, oil pump alternate mode control flow implementation Effect (1) After the system is rebuilt, the automatic switching and remote control operation of the main oil pump and the auxiliary oil pump are realized, the reliable interlock protection, data communication and upper computer management are realized; the parking failure rate is reduced, and the operation of the air compressor is greatly enhanced. Stability (2) Through the online monitoring of the program, the cause of the fault can be accurately determined, and the fault handling efficiency is greatly improved. 13 (3) The instability of the original operating system is changed, and the safety and reliability of the device are improved. Continuous and stable operation provides reliable protection (4) Make full use of the functions provided by the application software, and develop the running status of the hardware equipment. Online monitoring 13 has realized the on-site transmitter, analyzer, system power supply, CPU, I/0 module. On-line monitoring, while realizing remote fault diagnosis and management functions 13 5 Conclusion Loop oil pump automatic switching control method
The method effectively realizes the balance of working time of the main and auxiliary oil pumps, avoids the occurrence of mechanical and electrical faults, improves the use efficiency of the equipment, and prolongs the service life and maintenance period of the equipment. The DCS control system has simple hardware wiring, reliable operation and stable performance. Flexible control, easy maintenance and remarkable energy saving effect 13
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