I. Overview
Electricity is an essential part of modern human civil society. Thermal power generation is a major component of electricity production. Thermal power generation refers to the use of fossil fuels (ie, coal, oil, and natural gas), which release heat energy through combustion to heat the working medium, and then heat the prime mover. Drive generator power generation. The installed capacity of thermal power accounts for 75% of the total installed capacity of power generation in the country. The large amount of ash and slag produced by coal-fired power plants is discharged into the atmosphere except a small amount of ash, and the rest is delivered to the ash yard in the form of ash and slag from the ash removal system. The ash removal system includes mechanical ash removal (for chain furnaces in small power plants), pneumatic ash removal, and hydraulic ash removal. The ash removal system includes ash hoppers under the precipitator, transport fans, liquid mobilization fans, ash sheds and ash shed auxiliary equipment, transportation equipment, pipelines, pumps, valves, etc. The modern automation control technology takes PLC (Programmable Controller) as the core, can operate the equipment such as the ash removal system warehouse pump regularly and automatically in accordance with a predetermined program, and has the intelligence to perform the abnormalities that may occur during the ash removal process. deal with.
This system uses pneumatic ash removal technology. Pneumatic ash removal system collects fly ash collected by economizers and dedusting hoppers under the electrostatic precipitator. It is discharged to the ash storage by pneumatic conveying and then transported by truck. The control system monitors the ash hopper material level, gas source pressure, hopper pump material level, hopper pump pressure, ash storage material level, ash tube pressure and other parameters in real time to achieve the ash removal process of feeding, fluidization, ash transport, and blow plugging. Fully automatic control. The program control system uses a programmable controller as the main control device to complete the program control of the entire process of the ash removal process. The analog display monitor station uses an industrial bus IPC, manages the controlled analog display and keyboard operation, and the upper computer adopts a group. Wangwang monitoring software undertakes tasks such as management, programming, network data collection, and fixed value modification, and designs corresponding ash removal monitoring system software. The ash removal systems of the four coal-fired boilers of the power plant share a single PC for unified control to simplify management and reduce costs. Ash removal program control system has perfect interlock protection, fault diagnosis, a variety of operating modes and man-machine dialogue capabilities, safe, practical and reliable. The Ethernet communication between the PLC and the monitoring computer in the system improves the communication speed and ensures the reliability of the data. The monitoring screen simulates various conditions such as status, pressure, material level of the warehouse pump, ash store level, and ash pipe pressure. It also has operation steps, alarms, etc. The IO monitoring point is about 200 points. Equipment acquisition, give full play to the configuration software and programmable controller software features. The application of programmable logic controller ensures the reliability of the system and improves the safety performance of the unit. The adoption of monitoring software improves the degree of automation of the system and reduces the workload of the operator. The intuitive screen makes operation possible. Simple, reliable, convenient and avoids misuse.
Second, the system process and design
1, system technology
The ash transport process of a thermal power plant is as follows: the electrostatic precipitator ash hopper → gas locker → chute → feed machine → warehouse pump → ash store → ash yard, and the concrete ash transport procedure from the dust collector ash hopper to the ash shed is: In the case of no pressure in the pump body of the warehouse pump, open the feed valve and the purge valve (the ash bucket of the conductive dust collector of the warehouse pump to ensure the air discharge of the warehouse pump), start the air lock, and remove the electricity from the dust hopper The ash is sent through the airlock → chute → feed → feed valve into the hopper pump. When the ash in the pump reaches a certain level, the air lock is stopped and the feed and air bleed are closed. , Open the discharge valve, then open the air valve, use the compressed air to pump the gray material through the ash pipeline to the ash tower. Then, the material is deflated, and the task of sending the ash separated from the electrostatic precipitator to the ash turret is completed. The system plays an important role in the entire production process. In normal operation, it can ensure timely delivery of the ash powder produced by the burning of coal in the boiler.
The working principle of warehouse ash pump control system:
Figure 1 Schematic diagram of the warehouse pump delivery system
The warehouse pumping system is of great significance in the entire ash control system. It mainly uses compressed air to transport dry ash along the ash removal pipeline to the ash or transfer warehouse. The process is mainly achieved through the control of various valves. As shown in Figure 1. The feed valve consists of a cone valve, a connecting rod and a piston switch. When the piston lacking the piston is pushed to the upper part by the air pressure, the connecting rod drives the rocker arm to drop the poppet valve, and the feed valve opens; on the other hand, when the piston switches When the piston is in the lower part, the poppet valve is pushed up by the pressure of the spring in the piston switch, and is pressed against the rubber ring. At this time, the feed valve is closed.
Third, system configuration and function implementation
1, system configuration
Hardware: The monitoring center is equipped with two IPCs, Kingview software is installed, and a dust removal monitoring system is provided for the staff to perform monitoring operations. The dual-system hot backup mode is configured. At the same time, the Omron PLC is installed to perform data acquisition on the field devices. Monitor and connect to 2 upper computers via Ethernet switch for data communication.
Software: The ash removal system monitoring software designed by Kingview manages and controls the collection of data and process flow; PLC programming software downloads the control program to the PLC and performs PLC network configuration. The hardware configuration is scalable for adding devices or communicating with other systems.
2, system function to achieve
According to the system process requirements, the system has designed a rich display of the screen, the dynamic display of the image in addition to the gray warehouse pump, ash delivery pipe valve layout, and the use of different colors of the display to reflect the operation of the equipment. The system has simulation, remote operation, automatic, manual and other control functions, which can achieve a variety of control methods for the device. The upper computer monitoring system forms an effective data analysis chart by displaying time, current, and pressure data such as bar graphs and trend graphs. The system has perfect alarm processing. When the system has an alarm, it automatically pops up an alarm screen, displays the alarm content, and records the alarm for query and printing. In order to improve system security, when a fault occurs, corresponding protection measures can be automatically taken according to the type of fault, and protection functions such as over-current, overload, and medium abnormality can be provided. The system software and hardware configuration are all extensible, can be easily extended to the whole plant auxiliary control system, to achieve centralized control of the entire plant.
* Screen display function: including the warehouse pump system monitor screen and the gray library monitor screen, as shown in Figure 3 and Figure 4, to monitor the field devices.
Fig. 3 1# furnace monitor
The pressure, time, material level and other parameters of the warehouse pump system are monitored, and the process parameters can be manually set to control the equipment accordingly. The system monitors the warehouse pumps of the four units and the limit alarm status is also included in the screen. And other information.
Figure 4 Ash Library Monitor Screen
The ash library monitoring system monitors two ash stores. The monitoring devices in the ash library system include pipeline switching valves, ash store level meters, heaters, mixers, bulk machines, and gasification fans. There is a switching valve in each pipe in the picture, its status clearly reflects the on-site valve position signal, and can be operated by the staff. Advanced technology-based radio frequency admittance level sensors installed in the grey library can accurately convey the gray level signal to the PLC and display it in the configuration screen, enabling the crew to clearly analyze the status of the gray level.
Data management function: The system collects data and reflects it on the simulation screen. It generates real-time reports through the reporting tool and stores it through the Kingview history record function. It is used to generate historical trends and historical reports and provides reliable analysis of process data. The basis. The historical data screen is shown in FIG. 5, and the real-time report screen is shown in FIG. 6. The system can conveniently generate the files for the analysis results of these data for output or storage.
Figure 5 Warehouse Pump History Curve Monitoring Screen
Figure 6 System Report Monitor Screen
System alarm function: The system has a perfect alarm function, in the device monitoring screen with a different color to represent the state, the analog value has a limit alarm, switch value setting state transition alarm, and specifically set the total alarm list screen, as shown in Figure 7 , shows all alarm status and related information. The system is equipped with voice alarms, voice prompts can be provided, and it is convenient for the staff to provide alarm information even if the accident is handled accordingly. Alarms can be stored to prepare for accident recalls.
Figure 7 system alarm monitoring screen
System Network Function: The system utilizes the Kingview's dual-system hot backup function to configure the two upper computers of the monitoring center into a redundant mode to ensure the security of the system. The historical data can be processed in a consistent manner to ensure the reliability and integrity of the data. . The extensibility of the network provides a communication interface for the plant-wide auxiliary control system, which facilitates communication.
IV. Conclusion
The entire system has a reliable PLC for centralized control of the equipment, and the two-machine hot standby PC system provides security assurance for the software. The system has a complete configuration function, which improves the automation level of the ash removal production of the power plant and ensures the unit The normal operation. According to the long-term operation of the project, the equipment is operating normally, and the maintenance and inspection workload is reduced, which greatly reduces maintenance and inspection costs. Through the monitoring system staff can accurately understand the material level and operation status of the warehouse pump, the operation of the warehouse pump will have an effective signal basis, improve the operating efficiency of the warehouse pump and other equipment, reduce the loss of equipment and energy waste, ensure the The entire system operates normally according to the process requirements, providing favorable protection for the normal operation of the power plant. Kingview Configuration Software Advantech