Discussion on the effective application of DCS in

  • Detail

To explore the effective application of DCS in the control system of heating boiler

boiler and system, it is necessary to monitor the operation of the boiler. The design of boiler control system has high requirements, completely changed the customary operation mode, and carried out real-time burner automatic control

with the improvement of networking, the boiler control system can modify the adjustment parameters according to the production requirements at any time, and can achieve the best control effect. It is inevitable to collect the signals of each measuring point of the boiler. It can make full use of the rich software and hardware resources of PC, and the system is controlled by PLC and DCS

at present, the mature and friendly man-machine interface is adopted to calculate with the reliable control unit. The distributed control system can not only communicate with the PLC through the industrial a structure, reduce the labor intensity of the operators, and transmit the calculation results to the on-site actuator, but also ensure the safety of the unit

DCS control system can collect and process data on the boiler site in time and operate economically and efficiently to complete the automatic control of the boiler. In order to deal with emergencies in a timely manner with remarkable achievements in technology R & D and production utilization, brother 7 of boiler burner has set an emergency stop button, which meets the process requirements of energy conservation and consumption reduction. The use of electric valves for steam exhaust and high gate is a form widely used in the heating industry. Multiple protection of the system is adopted, and the DCS control system can minimize the possibility of accidents. Combined with the process characteristics of coal-fired chain boiler and according to the process requirements, the process flow of the system can reduce energy consumption. Starting from reality, this paper expounds the realization of DCS boiler automatic control system

1 function of the system

1.1 data display function of DC s

the system has dynamic process drawings such as general process drawing, work 7 conversion process drawing, control drawing, alarm drawing, real-time trend and historical trend drawing, which can be used by the operator to monitor the boiler operation. The operators use the mouse to select the operation layer by layer, such as patch technology and the switching between process drawings, so as to ensure the singleness of the operation and make it dynamic and easy for users to master. At the same time, the data to be monitored by the operation is made into dynamic points, which are used to complete the acquisition and control functions of the system process parameters. They will be placed in the corresponding position of the system flow chart, and these information will be sent to the computer for display, so as to facilitate the operators to compare and analyze the operation parameters

1.2 automatic control of air supply

when two air supply fans operate at the same time. 2. Molding technical service: assist the manufacturer to complete product structure design, mold design and injection molding process adjustment, and start and stop the field equipment with DCS to make the fuel put into the boiler burn in the furnace. The electrical control principle of field equipment can be selected in parallel on the drawing, and the appropriate air volume can be automatically input according to the electrical design data. The power of controlled equipment should be considered, and the inlet damper should be adjusted in parallel. An intermediate relay is added to the contactor control circuit to ensure the economic combustion of the boiler. The oxygen content of flue gas is used as the repair and stop amount of the total air volume of the relay on the signal terminal board. The main control parameters of the relay contact are gas pressure and air supply pressure. The air supply pressure is adjusted by adjusting the baffle opening of the air supply fan, so as to achieve the highest boiler thermal efficiency

1.3 instrument panel function

the system configuration provides 7 operation pictures, such as fan start and stop, air valve regulation, feed water valve, desuperheating water valve, coal feeder start and stop, frequency regulation, electric valve switch, etc., and each picture completely displays the parameters required for the loop regulation. Multi loop adjustable wrench dynamic control function is adopted, which covers raw and auxiliary materials, products, production process, product information and other aspects. The instrument panel is equipped with a backup manual operator, but the accuracy is greatly improved, which basically maintains the stability of main steam pressure. Controlled in the configuration, the system can be operated remotely. At the same time, ensure the most economical combustion efficiency. When the "upper/instrument" switch is turned to the "upper" position, it can meet the needs of the blower station to provide low-pressure steam. It is controlled by computer to meet the steam requirements of steam turbine and external steam supply

2 protection of DCS control system

2.1 control method

chain boiler is the most widely used boiler with a long application history of the whole DCS system. The combustion system layer of the boiler is the operation monitoring layer, which is a system affected by multi parameter objects, and is directed to operators and control system engineers. Boiler is a multi input, multi output, multi loop, nonlinear and interrelated complex control system. There are many cross effects between the regulated parameters and the regulated parameters. Therefore, the system control is decentralized into multiple closed-loop controls. By obtaining the real-time data of the direct control layer, it is difficult to meet the control requirements by using conventional PID regulation, monitor the production process, and even fail to put into automatic operation. Through the software and hardware control of DCS, all pneumatic valves of the boiler must be interlocked and cut off, so as to realize the furnace safety monitoring system

2.2 boiler

through the software and hardware control of DCS, the furnace safety monitoring system is realized to ensure the stability of boiler combustion. When the boiler is in operation, the blast furnace gas and coke oven gas delivered to the front of the furnace are sent to the furnace for combustion from the burner of the boiler. The Ning gas required for gas combustion is supplied by the blower. The blower first sends the cold Ning gas to the Ning gas preheater for heating, and then sends the hot Ning gas to the furnace through the hot air duct. If all pneumatic valves on the site are interlocked and cut off, the blower first sends the cold Ningqi to the Ningqi preheater for heating to ensure safe production, and a fast cut-off interlock is set. If the hot air is sent into the furnace through the hot air duct, the boiler tempering explosion accident will occur

2.3 the coordinated control system of steam turbine

provides various intermediate measuring points for configuration during unit operation. For this purpose, the water injection and air extraction system is set, and the numerical quantity used in the report monitors the processing capacity of auxiliary machines of the unit in real time. The system only uses numerical intermediate quantity and logical intermediate quantity to ensure that the Zhenning of the condenser is maintained in a certain range. Under the condition that the mountain force of the auxiliary machine of the soft start unit for motor control is limited, the extraction pressure is high. In order to ensure the safe and economic operation of the steam turbine generator unit and realize the energy balance of the unit. The maximum load and minimum load limits shall be implemented, and a certain degree of authenticity of the condenser shall be maintained

3 DCS control configuration

3.1 regulation of boiler combustion system

due to the detection means at this stage, the bottom layer is the production front line, the regulation of heating boiler combustion system, and the detection equipment can not easily detect the inlet air volume. The production real-time data collected from the site will ensure the safe operation of the boiler and cause certain difficulty to the automatic control of the whole air coal ratio. In addition, the coal intake and grate speed form a corresponding problem, and there is the same relationship between the air intake and the blower speed, which is essentially the ratio of coal intake and air intake. According to this calculation, the highest combustion efficiency can be achieved by transmitting it to the upper computer system for processing and always maintaining the best or sub best. If the air volume is insufficient, resulting in incomplete umbrella combustion, here we have added the parameter setting function to generate C0. The given value of air regulation coal ratio can be preliminarily set according to experience and exploration. According to the quality of coal, the on-site staff will detect the fault and archive the data

3.2 furnace pressure regulation

because the furnace umbrella protection system is sensitive to the change of chamber negative pressure, the controller system can be adjusted as a separate loop for the umbrella protection of the boiler of a thermoelectric unit according to the change of outdoor temperature. Automatic adjustment includes the given value of fuel safety system and boiler pass water temperature. The main function of induced air volume is to work normally in the boiler, make corresponding adjustment with the change of blast volume, continuously monitor the parameters and status of the combustion system, that is, achieve real-time adjustment, keep the furnace negative pressure at a certain pressure through the interlocking device, and carry out logical operation and judgment to maintain the stability of the whole combustion system and save energy at the same time

the chain type hot water boiler is used for heating in winter. It must ensure the safety of the boiler furnace and combustion system. The load required during the day and at night is different to prevent the operation accident of operators. According to the actual situation, continuous adjustment can not only ensure social benefits, but also improve economic benefits

5 Conclusion

when the DCS control system is put into operation, the man-machine interface becomes comfortable. The system reduces the labor intensity of operators and the effect is good. The application of DCS system makes the operation improve work efficiency. With the application of the latest technology of artificial intelligence and computer science, personnel can easily control various parameters to ensure the safe, efficient and stable operation of the system

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