Boiler dcs control system

Distributed Control System (DCS), also known as distributed computer control system, is a new type of control technology that uses computer technology to centrally monitor, operate, manage and decentralize the production process. It is produced by the mutual penetration of computer technology, signal processing technology, measurement control technology, communication network technology, CRT technology, graphic display technology and human-machine interface technology. DCS is different from distributed instrument control and centralized computer control system, but overcomes the shortcomings of both and concentrates the advantages of both. The utility model has the advantages of strong versatility, flexible system configuration, perfect control function, convenient data processing, centralized display operation, friendly human-machine interface, simple and standardized installation, convenient debugging, safe and reliable operation, and can improve production automation level and management level. Reduce energy consumption and raw material consumption, increase labor productivity, ensure production safety, and create optimal economic and social benefits.

1, computer data acquisition and real-time display

The signal at the site includes analog quantity and switch quantity. The analog signal mainly includes boiler outlet water temperature, boiler outlet water pressure, boiler outlet water flow rate, furnace temperature, furnace negative pressure, boiler exhaust temperature, outdoor temperature, boiler return water temperature, return water pressure, etc. The switching signals mainly include various interlocking signals, manual and automatic switching signals, manual and automatic temperature setting signals, elimination of alarm signals, working signals of various motors, and other signals that need to be acquired. The above data enters the computer and can be displayed on the display in real time after being processed. While the above data processing, can also complete query, retrieval, statistics, reports, printing.

2. Automatic/manual control of boiler heating system

When the boiler heating system is manually controlled, it mainly plays the role of data acquisition and real-time display. When the collected data is abnormal, the system will give an audible and visual alarm. The operation of the equipment is controlled by the operator on site, which is suitable for equipment debugging. In automatic operation, the system is except It has the same data acquisition and real-time display function as the manual operation mode, and also has an automatic control function. According to the detected feedback signal, the boiler is controlled to operate under the optimal working condition to realize coal saving, power saving, water saving, and reduction of people. The purpose of synergy.

The manual control has the highest priority. When the “manual/automatic” changeover switch is “manual”, the controller's control is shielded, and the field device can be manually operated on the handheld communicator, such as opening and stopping; when “manual/automatic” When the transfer switch is "automatic", all control of the device is done by the controller. Manual/automatic with bumpless switching.

The automatic control uses the logic control function of the controller to provide linkage, interlock control and closed-loop control of the equipment automatic and associated equipment. The auxiliary equipment of the boiler room is mainly controlled by this type.

Operator station control is controlled by the operator station through the human-machine interface to remotely control the equipment in the boiler room to achieve macro control, handle local downtime accidents and emergency situations, and maintain overall coordination of the system.

3, the system's communication function

The control room computer uses the MODEM to perform automatic data exchange and remote control functions with the remote computer through the telephone line. It has external communication interface with other control system communication and standard, and there is no special requirement for network connection. The on-site process controller is connected into a complete control system through the controller network. The controller uses the operating station's database and runs the software installed in the operating station. The operator station continuously collects data from the controller to update the database. It is able to communicate with all control stations with a data scan period of 1 second.

1, hardware system

The computer system consists of a field control station and an operator station. The configuration principle is that each boiler controls one on-site control station. The public part of the boiler is equipped with one on-site control station. Each two on-site control stations is equipped with an operator station. The operator stations are alternate with each other and they can independently monitor the entire process. Display the operating status of the boiler, the dynamic parameters of the process flow, the trend of related parameters, and historical data records.

The sensor system includes the collection and transmission of field signals such as temperature, pressure, flow, and liquid level to the computer. The frequency converter control system controls the blower, induced draft fan and grate motor and communicates with the computer. Automatic or automatic control via the Communicator.

The instrument indicator system mainly includes the hand-held device: the manual/automatic bumpless conversion and signal switching of the inverter control is completed, and the actual application effect is remarkable; the furnace negative pressure and the boiler outlet water temperature are very important parameters, and the instrument direct display is both intuitive and beautiful ( The computer system is also displayed at the same time; many parameters of the alarm can be better with the computer alarm and the flash alarm output.

2, the software system

The control system not only needs to have reliable hardware equipment, but also has powerful, reliable, and user-friendly system software, programming software and application software. The software system is specially tailored to the specific situation and includes the industrial control configuration software package. Access to process data including all state points, analog variables, and software-generated variables should be in a high-level language. All processing data and operation data are displayed in Chinese. According to the factual data, we can watch the development trend during the expansion period. The alarms are given priority management and any management is displayed on the screen. The alarm record is completed and the alarm summary is displayed.

The system software has standardized, professional, mature, reliable and applicable boiler automatic control computing software, and has been widely used in the monitoring of similar boilers.

Based on Windows system, powerful graphic display function, support 128031024 resolution is a universal, open, real-time, multi-tasking operating system. With file management, 'text editing, network communication, backup and other functions. Online diagnostics for complete diagnostics of hardware and software failures. Support Chinese printing in data.

The system controls three boilers (two 40 tons and one 20 tons). After two heating periods, the system proves that the system is successful. The experience and lessons are mainly as follows:

1. The system must have strong anti-interference ability.

　　 Mainly take the following measures

The grounding end of the power supply, the casing and the instrument shall be separated; the analog signal lines shall be shielded cables, and the power supply (AC220V) of the shielded layer connected to the instrument ground shall be powered by the isolation transformer;

The switching signal of the lower computer should be isolated by the relay, and the analog signal is isolated by the active isolation module;

The strong and weak electrical terminals of the terminal block are respectively arranged; the UPS of the upper computer adopts one machine;

The software design takes a variety of anti-jamming measures.

2. All purchased instruments, sensors, host computers and lower-level machines, etc., under the premise of ensuring quality, pay attention to whether they have the nearest service conditions, and can solve them in time when problems arise;

3. The independent two-phase power switch should be set for the instrument and the lower computer of the console, so that it does not affect other equipment during maintenance.

4. The cabinet is sealed with IP54 package to protect the computer, PLC and other electrical components from dust pollution, improve system reliability and reduce maintenance and repair; at the same time, reserve enough space for wiring and component addition. maintain