1 Structure and functional characteristics of the automation control system The Daliuta Coal Preparation Plant adopts automatic control. The whole plant control system adopts a three-layer network structure. Ethernet is used for the management of the system. DH+ network is used for control layer communication between PLC controllers and computer operation stations. Remote I/ The O network is used for device control and data acquisition. It has fault diagnosis and alarm functions, multiple device protection functions, and remote monitoring functions. The control functions are flexible and practical, and the screen display functions are rich. The system is a real-time monitoring network structure, with a complete production monitoring and management function, real-time data collection, transmission, processing, display, recording and printing of the production process of the entire production process and related auxiliary links. It has centralized control of 303 main production equipments and related power distribution equipment, factory lighting and cleaning water systems, and is equipped with industrial television systems for security image surveillance. The automation of coal preparation plant is mainly reflected in: (1) Real-time online operation parameter monitoring. Each monitoring system collects complete parameters of production conditions in real time, including various electrical parameters (power, current, voltage, cosφ, electrical, etc.), belt speed, volume, ash, moisture, concentration, pressure, speed, temperature, and A kind of protection signal, etc., display the real-time working conditions of the system, output, position, etc. in the form of graphs and reports. (2) Production process control. Full system process control, automatic blocking, local automatic adjustment closed loop control or controlled by dispatcher operation. (3) Historical data query. The production real-time monitoring data can be stored in the production real-time data history database, which can realize the historical retrospective, historical trend analysis and comprehensive analysis of histogram and pie chart. (4) Equipment failure and analog over-limit alarm. When the equipment fails or the analog quantity exceeds the limit, the production monitoring and management network displays the fault or the device name synchronously, and can realize the language alarm, real-time fault printing, and statistical analysis of the running time of the coal feeder and other equipment. (5) Production real-time screen monitoring. (6) The control function is powerful. From the software, the functions of centralized control, local, and zone locking are set. (7) Control system and equipment layer, fully adopting industrial control software products. 2 Transformation and improvement of automation system The Daliuta Coal Preparation Plant was built in the 1990s. Compared with the most advanced high-efficiency coal preparation plants in the world, there are still some shortcomings in terms of overall process design, capacity of single equipment, and automation level. Therefore, the Daliuta Coal Preparation Plant has improved its control system. (1) Equipped with 102 sets of spare drawers required for the entire plant production equipment. (2) Renovation of the only frame switchboard in the power distribution room of the less-crushed workshop, adding a set of backup circuits, greatly shortening the repair time in the event of equipment failure, and using the same method to perform 18 sets of equipment in the crushing workshop. Complete renovation. (3) Renovation and improvement of the conveyor belt protection used in the whole plant, 65 anti-blocking protections for the chute, 25 under-speed protection for the conveyor belt, and 4 anti-corrosion protection for the conveyor belt. The deviation switch and the rope switch were modified, and the bracket was reworked and installed. (4) Completed the transformation of the coal feeder under the original coal bunker, the control and transformation of the hydraulic gate of the hydraulic station, the automatic control transformation of the pumping water pump, the power lock of the power distribution system, the centralized control of the lighting of all floors of the whole plant, and the warehouse More than a dozen technical transformations such as alarm, water level alarm, automatic control of pressure fan, and caller self-injection control system. (5) Install a mechanism that swings with the bucket elevator in the middle of the bucket lifter. By installing a proximity switch to detect the number of movements of the mechanism and feedback the signal to the computer, the program determines the bucket lifter. The operating state realizes the protection of the bucket lifter. The system can effectively prevent the blowout machine from being broken, breaking the board, tailing the tail of the tail, hitting the bucket and other faults and the electrical control loop is faulty. Since the installation, three major accidents have been avoided. (6) Renovation of the control of 16 high-voltage starters. Due to long-term operation of the high-voltage starter cabinet, the rectifier bridge of the high-voltage cabinet power supply often fails. If the on-site processing takes a long time, a set of standby power supply rectifier bridge is installed through technical transformation. Once the rectifier bridge in operation has problems, the conversion is completed. Switching the switch to the standby rectifier bridge will enable the equipment to operate normally, greatly reducing the impact time of the accident. (7) Improve the automatic control of capacitors in low-voltage power distribution room, the positive and negative control of some scraper, and the drawstring, deviation, chute anti-blocking, tape underspeed, tape tear-proof, etc. of the 42 belt conveyors of the whole plant. Protection and protection of the trigger and bucket lifter. (8) In order to handle faults more conveniently, many protections are separated from the electrical control loop and directly entered into the module for control, reducing the point of failure. Through this method, the overcurrent, voltage loss, high-voltage motor running current, motor operating temperature and other signals of the high-voltage starter cabinet can be converted into analog signals and transmitted to the dispatching room. The dispatcher can realize online monitoring and control through the computer. protection. In addition, online tests such as measuring instruments, water measuring instruments, level gauges, belt scales, and industrial televisions have been realized. 3 Examples of transformation of weak links in production 3.1 Reconstruction of jig automatic decontamination system in Daliuta Coal Preparation Plant Large-scale coal mine production inevitably mixes wood, gun line and waste garbage from the overhaul process into raw coal. The bulk of the coal is larger than the fine coal, which can be discharged by jigging with the meteorite, but the proportion is smaller than that of the clean coal. Rubber, plastic bags and other debris often enter the clean coal product with overflow. In order to ensure the quality of coal, a set of decontamination nets was designed and installed on the jig, and the floating nets on the bed were intercepted by the barrier net. At the same time, the anti-jamming hooks in the extension bed were used to hug the gun lines. Linear debris such as tape. The decontamination device has a good trial effect, but it also has some drawbacks. First, the decontamination net is fixed, and it cannot be deep inside the bed. Small debris will leak through the net. If the large debris is stopped, if it is not cleaned up in time, it will pass through the net. Therefore, the decontamination system Further improvements were made: first, the barrier plate was placed diagonally, and a small side panel was added, so that the floating debris was guided to the overflow port, collected in a container, and discharged. The second is to change the entire blocking mechanism to automatically track and adjust the height with the water level and the height of the bed, thus avoiding the damage to the bed and improving the precision of the impurities. The automatic adjustment mechanism is driven by the PLC system to drive the servo motor mechanism to drive the on-and-off adjustment of the miscellaneous barrier to accurately track the bed changes. After the implementation of the system, the effect of removing impurities and removing impurities is obvious. 3.2 Reconstruction of tape anti-slip protection system There are more than 40 belt conveyors in the Daliuta Coal Preparation Plant with a width of more than 1000mm. In the production process, any belt conveyor has accidents such as slipping and breaking, which will cause great accidents and losses if not discovered in time. The Daliuta Coal Preparation Plant has always attached great importance to the research on belt conveyor underspeed protection devices. At first, the Daliuta Coal Preparation Plant used the tape underspeed protection device produced by Xuzhou Ramsey Co., Ltd., but it has two shortcomings: First, it cannot resist electromagnetic interference, and the transmitting frequency of the intercom will interfere with the underspeed protection device, resulting in interference. Misoperation; Second, the detection principle of the protection device is flawed, and the detection signal is inaccurate and unstable. After repeated trials, the LJMl8T-8Z/NK type inductive proximity switch produced by Zhengtai Group Shilian Instrument Co., Ltd. was used as the probe, and its I/O signal was transmitted to the PLC, and a delay protection program was implemented in the PLC software. Very good, the specific transformation is as follows. (1) Installation of the underspeed protection device detection board. Mounting an arc-shaped iron plate, iron plates on the inner wall of the drum rear wheel driven belt length should be 1/4 ~ 1/2, the exact dimensions of the circumference of the drum according to the tape speed and tape roll diameter calculated to . (2) Installation of the underspeed protection device sensor. First, a device that can adjust the detection sensor back and forth is processed and a protective cover is attached. (3) Determination of parameters. When the belt conveyor is in normal operation, the sensor of the protection device sends a pulse signal to the PLC every time the tail roller rotates. By comparing the measured pulse signal interval time with the set time, it can be judged whether the belt conveyor is running normally. If the belt conveyor is underspeed, the PLC will automatically lock and stop the equipment in the coal direction. If the tail roller of the belt conveyor stops rotating, the detection plate and the sensor probe are just aligned, the PLC will detect a continuous signal, and the PLC will also consider it an accident and stop. 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Automation Reform of Production System of Daliuta Coal Preparation Plant
Daliuta election coal plant is a design production capacity of 17 million t of coal washing man of large modern group central mine coal preparation plant, with a multi-point, wide, long line characteristics. The factory has 7 production workshops, 19 power distribution rooms, 6 high-voltage power distribution rooms, two opening and closing stations, 303 sets of main production equipment and more than 610 auxiliary production equipment. The automation system of American AB company is adopted, and the degree of automation is very high. With the continuous expansion of the production capacity of the coal preparation plant, the automation system has to undergo corresponding transformation and upgrading.