The intelligent control valve is a control valve with a microprocessor that enables intelligent control functions. The control valve is usually intelligent in the following forms: a. Pneumatic control valve with intelligent valve positioner; b. Intelligent electric control valve; has been fieldbus intelligent valve positioner pneumatic control valve. Intelligent control 'mainly include the following a. Easily modify the control valve flow characteristics. b. PID control operation. c. To achieve other computing functions, for example, range control range settings, nonlinear compensation operations. d, change the positive and negative reaction control valve. e. To achieve communication with the host computer, - to achieve information sharing. L to achieve the control valve fault diagnosis and alarm. g. To achieve self-locking control valve. h Achieve control valve status information management, the use of intelligent valve positioner has the following advantages. a. Reduce the control loop installation, calibration and debugging time. b. Using diagnostic functions, the control valve. Life expectancy, operating conditions can be timely monitoring. c. Reduce the skill requirements of the meter maintainer. Pneumatic control valve with intelligent valve positioner This type of control valve has the same structure as a normal control valve. The intelligent control valve is equipped with an intelligent function due to the intelligent positioner. The main differences between an intelligent valve positioner and a normal positioner are as follows: 1. Control valve flow characteristics of different ways to achieve. The feedback part of the intelligent positioner adopts linear feedback, and the required flow characteristics of the control valve are realized in the setting loop. The feedback part of the ordinary positioner is a cam of a different shape, which realizes the desired flow characteristics of the control valve by changing the cam shape. See section 5.3 for details. 2 different input and output methods. In general, smart valve positioners are smart electric valve positioners. Compared with the general electric valve positioner, intelligent electric valve positioner input signal is a standard 4 ~ 20mA or 1 ~ 5V electrical signal, which requires analog-digital conversion as the microprocessor input signal. The general electrical valve positioner input signal is 4-20mA or l ~ 5V electrical signals, but it does not require the analog-digital conversion can be sent directly to the electromagnetic coil electromagnetic force, to achieve balance. Intelligent valve positioner output signal is a digital signal, it usually send piezoelectric valve group, through the piezoelectric valve switch to adjust the pressure to send control valve membrane head, the general electrical valve positioner output signal is amplified by the pneumatic amplifier The gas signal. 3 different control methods used. Intelligent valve positioner and general computer control device, using discrete control, therefore, in the sampling interval, the control valve opening does not change. During operation, the control valve opening showed a step-shaped change. The general valve positioner adopts continuous control mode. Therefore, the change of the control valve opening is continuous (except for the transition caused by the dead zone) during the whole control process. 4. The feedback signal detection processing is different. Intelligent valve positioner control valve feedback signal to be sent to the microprocessor after the analog-digital conversion, and general valve positioner feedback signal directly as a feedback force (torque), do not need to be converted into electrical signals by the modulus. Some intelligent valve positioner input signals using standard analog signals, HART digital signals are also transmitted on the same wire to form a mixed signal smart valve positioner, which does not belong to the fieldbus smart valve positioner, but still belongs to the intelligent valve positioner. Intelligent electric control valve This type of control valve using intelligent servo amplifier, digital operator, deceleration mechanism, valve position detection and sending device and electric control valve and other components. The main difference with the general electric control valve is the use of intelligent servo amplifier. Intelligent servo amplifier is a miniature computer, which receives a standard analog current or voltage signal, the analog to digital signal converted by the microprocessor input signal and the set signal comparison, and according to a certain control law operation, the output signal After the digital-analog drive the corresponding electric control valve. The working principle of the pneumatic control valve with intelligent valve positioner is similar. The main difference between the intelligent electric valve and the electric control valve is that the output signal is sent to the motor (which can be a single-phase or three-phase motor) and is changed after being decelerated Electric valve opening. Intelligent electric valve is also used to set the nonlinear characteristics of the loop to compensate for the non-linear characteristics of the controlled object, thus avoiding the feedback loop caused by instability of the control system instability. At the same time, due to the digital way to achieve non-linear compensation, therefore, according to the pressure drop ratio of the control valve and the required flow characteristics of the work to determine the non-linear compensation points in the line position. Pneumatic control valve with fieldbus intelligent valve positioner Compared with the general intelligent valve positioner, this type of control valve with valve positioner features the following. a. The input signal is not a standard analog current or voltage signal, but a digital signal from the fieldbus device. b. With communication capabilities, can easily communicate with the host computer to achieve data exchange and data sharing. c. Direct power supply can be used and intrinsically safe way to run, in line with the relevant provisions of the field bus. d, to achieve the functions of open system interconnection, such as interchangeability, interoperability and so on. e. Full digital, two-way communication.
Electric Superheater,Superheater In Power Plant,Electric Steam Superheater,Working Of Superheater In Boiler
Jinan Yuanda Power Equipment Co.,Ltd. , https://www.jnyuandaboilers.com