Analysis of Grinding Machine Material Inspection Procedures in Power Stations in the Mainland

Material Level Control The ball mill level monitoring system uses a microprocessor to implement automatic control functions. The control block diagram is shown. It can be seen that the level signal obtained by the material level sensing device after being processed by the material level monitoring system is compared with the set value of the material level after the setting value is selected, and the deviation is outputted to the coal feeder after PID operation. The controller controls the speed (coal feed) of the coal feeder so that the material level of the coal mill is controlled near the set point of the material level.

The ball mill level monitoring system selects four automatic control modes such as “fixed value”, “tracking”, “maximum” (maximum output optimization mode), and “economy” (optimal economic optimization mode) through setting values. When the coal mill is in normal operation, the “fixed value” control method should normally be adopted, and the material position setting value will remain unchanged, so that the coal mill will be maintained in a constant working condition. "Maximum" and "economy" self-optimizing methods are used in the ball mill level monitoring system to find the maximum output and the most economical material level setting, which can be used to find the optimal material level during commissioning and not used during normal operation. .

In automatic mode, the system is designed with control output protection. When the material level and material level related quantity exceed the upper and lower limits set by the panel of the device, the control output protection action of the system will reduce the speed of the coal feeder to the lower limit to ensure that the coal mill will not block the tank; Discuss Hunan power signals so that relevant personnel can handle them in a timely manner.

Connection between the system and the DCS The ball mill level monitoring system is an independent system. It does not have an operator on its own and must be connected to the operator of the coal feeder to complete the speed control function of the coal feeder. After the transformation of the DCS system at Shimen Power Plant, the speed control of the coal feeder was achieved through a soft hand operation station within the DCS system. To achieve the relevant functions of the ball mill level monitoring system, it must be connected to the DCS system to introduce hand/automatic switching signals from the DCS system, coal mill start/stop status signals, coal mill inlet/outlet differential pressure signals, and hand operation stations. Output signal, the level signal measured by the system is transmitted to the DCS system for online monitoring by the operating personnel, and the control output signal of the control system is transmitted to the soft hand operation station of the DCS system, and the coal is controlled by the soft hand control station when the automatic transmission is performed. The speed of the machine. The ball mill level monitoring system is connected to the DCS system as shown.

Installation and commissioning of the system The installation of the ball mill level monitoring system includes the installation of the STA-2 ultrasonic audio sensor, the installation of the material level monitor TCS-200A and the connection of the system. The STA-2 ultrasonic audio sensor is installed in the soundproof room of the coal mill, and the sensor can be fixed on the wall of the soundproof room according to the size of the sensor installation; the level monitor TCS-200A is generally installed in the thermal control room; STA-2 Ultrasonic audio sensor and level monitor TCS-200A is connected with the audio cable provided by the manufacturer. The audio cable must be installed with anti-jamming measures. The best use of metal pipe; between the material level monitor and the DCS system using the general Shielded cables, wiring according to the drawings to complete the installation and connection.

Application effect The Shimen Power Plant No. 1 furnace No. 1 furnace 4 coal mills 4 sets of material level monitoring system began construction in May 2003, July 2003 installation and commissioning is completed. Now four sets of material level monitoring systems can be put into operation normally, and the utilization rate is over 98%. Moreover, due to the stable material level of the coal mill, the powder leakage phenomenon of the coal mill is further controlled, and the level of civilized production has been improved; and The automatic control of the coal feeder is realized, the operation of the pulverizing system is standardized, the operation amount of the pulverizing system is reduced, and the labor intensity of the operating personnel is reduced. The ball mill level monitoring system has achieved good results.