Intelligent sensor in chemical plant
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The general sensor can only be used as a sensitive element, and must be equipped with a conversion instrument to detect the changes of physical and chemical quantities. With the development of microelectronics technology, intelligent sensors appear. The intelligent sensor adopts VLSI and uses embedded software to coordinate internal operation. On the basis of completing nonlinear compensation, zero error, temperature compensation and fault diagnosis of input signal, it can also complete the control of industrial process and further disperse the functions of control system< Br > the intelligent sensor integrates all the functions of sensor and intelligent instrument as well as some control functions, which has high linearity and low temperature drift, reduces the complexity of the system and simplifies the system structure. The advantages are as follows: < br > ● a certain degree of artificial intelligence is the combination of hardware and software, which can realize the learning function and better reflect the role of instruments in the control system. According to different measurement requirements, we can choose the appropriate scheme, and can process the information comprehensively to predict the system state< Br > ● multi sensitive function integrates the original scattered and independent single sensor into a sensor with multi-sensitive function, which can simultaneously measure a variety of physical and chemical quantities and comprehensively reflect the comprehensive information to be measured< Br > ● it has high precision and wide measuring range. It can detect the influence of the measured changes on the characteristics of the detection elements at any time and complete various calculations. Its output signal is more accurate. At the same time, its range ratio can reach 100:1, up to 400:1. It can use an intelligent sensor to cope with a wide measuring range, especially suitable for control occasions requiring large range ratio< Br > ● the communication function can use standardized bus interface for information exchange, which is one of the key signs of intelligent sensor< Br > < br > the emergence of intelligent sensor changes the complex signal from centralized processing to decentralized processing, which can ensure the quality of data processing, improve the anti-interference performance, and reduce the cost of the system. It makes sensors develop from single function and single detection to multi-function and multi variable detection, from passive signal conversion to active control and information processing, and from isolated components to systematization and networking.
Intelligent sensor and instrument engineering in a chemical plant; A pressure sensor is installed at the bottom of the chemical tank to detect the liquid level. Due to the need of intrinsically safe instruments and data exchange in the chemical field, the control accuracy of the project is required to be high< Br > according to the engineering needs, combined with the actual situation of Siemens PLC control, the control system of chemical plant instrument engineering project can be constructed according to figure 2< Br > in this control system, DP / PA coupler is the combination point and physical connector of PROFIBUS-DP and profibus-pa. DP / PA coupler can be used alone or in combination with DP link. It can be used alone in this project< Br > there are two types of DP / PA couplers, exi DP / PA coupler and FDC 157-0 DP / PA coupler. The maximum output current of the former is 110mA, which is used for explosion-proof applications; The maximum output current of the latter is 1000mA. Since the control cabinet is installed in the central control room, only sensors and actuators are installed on site, and intrinsically safe field instruments are required, FDC 157-0 DP / P coupler is selected from the economic point of view< Br > selection of pressure sensor SITRANS P DS Ⅲ is an intelligent digital pressure transmitter with Hart, PROFIBUS PA or FF Bus communication, key operation, diagnosis function and high precision (as shown in Figure 3). The intelligent pressure transmitter is mainly used for pressure, differential pressure, absolute pressure and liquid level measurement, with special safety standards< Br > the advanced diagnostic functions of SITRANS P intelligent pressure transmitter include: < br > ● double time registers, which can set the prompt signal when preventive maintenance or calibration is needed< Br > ● three limit values that can be adjusted arbitrarily, which means that preset alarm or temperature monitoring can be performed< Br > ● overrun recording: record the maximum / minimum value of pressure, sensor temperature and electronic unit temperature with unrecoverable instantaneous actual value. The recording information also includes SITRANS P status, process and ambient temperature< BR>
Simulation function: the transmitter can check the electronic part behind the sensor and the whole circuit, such as system debugging before starting. This provides important information: is the electronic part of the transmitter working properly? How much pressure produces overrun response? Is the control loop working properly? Do all display functions work< Br > ● simple plug and play function: in the field, if the transmitter fails in the electronic or measurement unit, only the failed components can be replaced without recalibration< Br > ● field calibration is easier: DS III series intelligent transmitter has unique local button. Through the local button, the transmitter can be configured with various functions, such as zero point adjustment, upper and lower limit setting of pressurized and non pressurized measurement, unit selection, damping setting, output selection, etc. In addition, because the local button adopts the principle of magnetic induction, even in dangerous places, without opening the transmitter cover and using any special tools, it can also adjust parameters and operate freely. You can also lock the configuration buttonTo avoid misoperation< Br > selection of flow sensor in intrinsically safe type, SITRANS FM series electromagnetic flowmeter has various range types meeting ATEX and FM certification, including split and integrated installation. It has intrinsically safe input and output, Namur ne 21 compliant, multi information and multi language display, real-time flow and cumulative forward and backward flow, advanced self diagnosis function and error record. In the chemical industry, there are often harsh environments, so it is required to use a wide range of anti-corrosion materials. The lining, electrode and housing materials provided by Siemens SITRANS FM can withstand the corrosion of such harsh process media< The SIPART PS2 series valve positioners as shown in Figure 4 have the following advantages: < br > ● automatic initialization. SIPART PS2 can be automatically initialized in a few minutes through a simple menu. In this process, the microprocessor can determine the zero point, the end position, the direction of motion and the speed by itself. From these terms, the minimum pulse time and dead time can be determined and optimized< Br > ● low gas consumption. Another significant advantage of SIPART PS2 is very low air consumption. Traditional valve positioner will have a lot of instrument air emission or leakage in operation, resulting in large demand for instrument air and high operating cost. Due to the new piezoelectric valve technology, SIPART PS2 will not discharge any instrument air when the valve does not act, and only uses air at the most needed time (i.e. when the valve acts)< Br > ● rich diagnostic functions. The new SIPART PS2 can provide more parameters and additional diagnostic information, including working time record, current temperature, min / max temperature, working time of each temperature segment, online control of valve seat (up and down stroke position), monitoring or display of adjustable threshold, etc< Br > after the selection of valve positioner, the installation wiring is finished, as shown in Figure 5, which is the PA bus wiring of instrument.
< br > conclusion < br > with the continuous development of complex process industry, industrial process control puts forward newer and higher requirements for a large number of field signal acquisition, transmission and data conversion, as well as accuracy, reliability and management and control integration< Br > ● intelligent sensor and fieldbus are two important parts of intelligent sensor and instrument control system. < br > intelligent sensor and instrument control system use fieldbus to establish a high reliable data communication line in the control field, so as to realize the data communication between intelligent sensors and between intelligent sensor and host computer, It turns a single distributed intelligent sensor into a network node. The data processing in intelligent sensor can help to reduce the workload of the master control station, make a lot of information be processed locally, reduce the information round trip between the field instrument and the master control station, and reduce the requirement of network data communication capacity. The data preprocessed by the intelligent sensor is collected to the host computer through the field bus for more advanced processing (mainly system configuration, optimization, management, diagnosis, fault tolerance, etc.), so that the system can analyze and judge the controlled object from surface to point, and then from point to surface, so as to improve the reliability and fault tolerance of the system< Br > ● the difference between intelligent sensor and general sensor < br > compared with general sensor, intelligent sensor based on digital communication should have the following functions: < br > 1. Share a bus to transfer information, and have a variety of calculation, data processing and control functions, so as to reduce the burden of the host. Instead of 4-20mA analog signal transmission, the digital transmission signal is realized and the anti-interference ability of the signal is enhanced< Br > 2. Using the unified network protocol, it becomes the node of the fieldbus control system to realize the information exchange between sensors and actuators. The system can check, configure and test it, so as to improve the reliability of the system. Interface standardization, with "plug and play" features< Br > intelligent sensor is the mainstream product of industrial process control system in the futureIt will bring revolutionary changes to the traditional control system structure and method.
The general sensor can only be used as a sensitive element, and must be equipped with a conversion instrument to detect the changes of physical and chemical quantities. With the development of microelectronics technology, intelligent sensors appear. The intelligent sensor adopts VLSI and uses embedded software to coordinate internal operation. On the basis of completing nonlinear compensation, zero error, temperature compensation and fault diagnosis of input signal, it can also complete the control of industrial process and further disperse the functions of control system< Br > the intelligent sensor integrates all the functions of sensor and intelligent instrument as well as some control functions, which has high linearity and low temperature drift, reduces the complexity of the system and simplifies the system structure. The advantages are as follows: < br > ● a certain degree of artificial intelligence is the combination of hardware and software, which can realize the learning function and better reflect the role of instruments in the control system. According to different measurement requirements, we can choose the appropriate scheme, and can process the information comprehensively to predict the system state< Br > ● multi sensitive function integrates the original scattered and independent single sensor into a sensor with multi-sensitive function, which can simultaneously measure a variety of physical and chemical quantities and comprehensively reflect the comprehensive information to be measured< Br > ● it has high precision and wide measuring range. It can detect the influence of the measured changes on the characteristics of the detection elements at any time and complete various calculations. Its output signal is more accurate. At the same time, its range ratio can reach 100:1, up to 400:1. It can use an intelligent sensor to cope with a wide measuring range, especially suitable for control occasions requiring large range ratio< Br > ● the communication function can use standardized bus interface for information exchange, which is one of the key signs of intelligent sensor< Br > < br > the emergence of intelligent sensor changes the complex signal from centralized processing to decentralized processing, which can ensure the quality of data processing, improve the anti-interference performance, and reduce the cost of the system. It makes sensors develop from single function and single detection to multi-function and multi variable detection, from passive signal conversion to active control and information processing, and from isolated components to systematization and networking.
Intelligent sensor and instrument engineering in a chemical plant; A pressure sensor is installed at the bottom of the chemical tank to detect the liquid level. Due to the need of intrinsically safe instruments and data exchange in the chemical field, the control accuracy of the project is required to be high< Br > according to the engineering needs, combined with the actual situation of Siemens PLC control, the control system of chemical plant instrument engineering project can be constructed according to figure 2< Br > in this control system, DP / PA coupler is the combination point and physical connector of PROFIBUS-DP and profibus-pa. DP / PA coupler can be used alone or in combination with DP link. It can be used alone in this project< Br > there are two types of DP / PA couplers, exi DP / PA coupler and FDC 157-0 DP / PA coupler. The maximum output current of the former is 110mA, which is used for explosion-proof applications; The maximum output current of the latter is 1000mA. Since the control cabinet is installed in the central control room, only sensors and actuators are installed on site, and intrinsically safe field instruments are required, FDC 157-0 DP / P coupler is selected from the economic point of view< Br > selection of pressure sensor SITRANS P DS Ⅲ is an intelligent digital pressure transmitter with Hart, PROFIBUS PA or FF Bus communication, key operation, diagnosis function and high precision (as shown in Figure 3). The intelligent pressure transmitter is mainly used for pressure, differential pressure, absolute pressure and liquid level measurement, with special safety standards< Br > the advanced diagnostic functions of SITRANS P intelligent pressure transmitter include: < br > ● double time registers, which can set the prompt signal when preventive maintenance or calibration is needed< Br > ● three limit values that can be adjusted arbitrarily, which means that preset alarm or temperature monitoring can be performed< Br > ● overrun recording: record the maximum / minimum value of pressure, sensor temperature and electronic unit temperature with unrecoverable instantaneous actual value. The recording information also includes SITRANS P status, process and ambient temperature< BR>
Simulation function: the transmitter can check the electronic part behind the sensor and the whole circuit, such as system debugging before starting. This provides important information: is the electronic part of the transmitter working properly? How much pressure produces overrun response? Is the control loop working properly? Do all display functions work< Br > ● simple plug and play function: in the field, if the transmitter fails in the electronic or measurement unit, only the failed components can be replaced without recalibration< Br > ● field calibration is easier: DS III series intelligent transmitter has unique local button. Through the local button, the transmitter can be configured with various functions, such as zero point adjustment, upper and lower limit setting of pressurized and non pressurized measurement, unit selection, damping setting, output selection, etc. In addition, because the local button adopts the principle of magnetic induction, even in dangerous places, without opening the transmitter cover and using any special tools, it can also adjust parameters and operate freely. You can also lock the configuration buttonTo avoid misoperation< Br > selection of flow sensor in intrinsically safe type, SITRANS FM series electromagnetic flowmeter has various range types meeting ATEX and FM certification, including split and integrated installation. It has intrinsically safe input and output, Namur ne 21 compliant, multi information and multi language display, real-time flow and cumulative forward and backward flow, advanced self diagnosis function and error record. In the chemical industry, there are often harsh environments, so it is required to use a wide range of anti-corrosion materials. The lining, electrode and housing materials provided by Siemens SITRANS FM can withstand the corrosion of such harsh process media< The SIPART PS2 series valve positioners as shown in Figure 4 have the following advantages: < br > ● automatic initialization. SIPART PS2 can be automatically initialized in a few minutes through a simple menu. In this process, the microprocessor can determine the zero point, the end position, the direction of motion and the speed by itself. From these terms, the minimum pulse time and dead time can be determined and optimized< Br > ● low gas consumption. Another significant advantage of SIPART PS2 is very low air consumption. Traditional valve positioner will have a lot of instrument air emission or leakage in operation, resulting in large demand for instrument air and high operating cost. Due to the new piezoelectric valve technology, SIPART PS2 will not discharge any instrument air when the valve does not act, and only uses air at the most needed time (i.e. when the valve acts)< Br > ● rich diagnostic functions. The new SIPART PS2 can provide more parameters and additional diagnostic information, including working time record, current temperature, min / max temperature, working time of each temperature segment, online control of valve seat (up and down stroke position), monitoring or display of adjustable threshold, etc< Br > after the selection of valve positioner, the installation wiring is finished, as shown in Figure 5, which is the PA bus wiring of instrument.
< br > conclusion < br > with the continuous development of complex process industry, industrial process control puts forward newer and higher requirements for a large number of field signal acquisition, transmission and data conversion, as well as accuracy, reliability and management and control integration< Br > ● intelligent sensor and fieldbus are two important parts of intelligent sensor and instrument control system. < br > intelligent sensor and instrument control system use fieldbus to establish a high reliable data communication line in the control field, so as to realize the data communication between intelligent sensors and between intelligent sensor and host computer, It turns a single distributed intelligent sensor into a network node. The data processing in intelligent sensor can help to reduce the workload of the master control station, make a lot of information be processed locally, reduce the information round trip between the field instrument and the master control station, and reduce the requirement of network data communication capacity. The data preprocessed by the intelligent sensor is collected to the host computer through the field bus for more advanced processing (mainly system configuration, optimization, management, diagnosis, fault tolerance, etc.), so that the system can analyze and judge the controlled object from surface to point, and then from point to surface, so as to improve the reliability and fault tolerance of the system< Br > ● the difference between intelligent sensor and general sensor < br > compared with general sensor, intelligent sensor based on digital communication should have the following functions: < br > 1. Share a bus to transfer information, and have a variety of calculation, data processing and control functions, so as to reduce the burden of the host. Instead of 4-20mA analog signal transmission, the digital transmission signal is realized and the anti-interference ability of the signal is enhanced< Br > 2. Using the unified network protocol, it becomes the node of the fieldbus control system to realize the information exchange between sensors and actuators. The system can check, configure and test it, so as to improve the reliability of the system. Interface standardization, with "plug and play" features< Br > intelligent sensor is the mainstream product of industrial process control system in the futureIt will bring revolutionary changes to the traditional control system structure and method.
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