Intelligent control valves
Intelligent regulator is the regulator contains microprocessor, can realize the intellectualized control function. The regulator intelligence usually adopts the following several forms:
a． with intelligent valve locator pneumatic regulator
b． intelligent electric control valve, with smart fieldbus valves locator pneumatic regulator. Intelligent control functions mainly include the following contents:
a． easy modify regulator flow characteristic.
b． realize PID control operations
c． achieve other operating function, for example, taking sectional control range setting, nonlinear compensation operation, etc.
d， change regulator positive, reaction method.
e． realize communication with superordination machine, realizing information sharing. - L realize regulator fault diagnosis and alarm.
g． realize regulator self-lock.
h. realize regulator state information management, using intelligent valve locator advantages are as follows.
a. reduce control circuit installation, check and debugging time.
b. using diagnosis function, make regulator operating. The life extended, operating condition can be timely monitoring.
c. Reduce requirements for instrument maintenance worker skills.
pneumatic regulator with intelligent valve locator
This kind of regulator structure is the same with ordinary regulator, because incidental intelligent valve locator and make the regulator with intelligent functions. The primary difference between intelligent valves locator and common valves locator are as belows:
1. The regulator flow characteristics realization types are different. Intelligent locator feedback part adopts linear feedback, the required regulator flow characteristic is realized in a setting loop. Ordinary locator feedback part is different shapes of CAM, by changing the CAM shapes to achieve required regulator flow characteristic. See 5.3 section.
2. Different input and output way. Usually, intelligent valve locator is intelligent electric valves locator. Compared with general electric valves locator, intelligent electric valves locator input signal is standard 4 ~ 20mA or 1 ~ 5V electrical signal, it needs after analog digital conversion as microprocessors input signal. While general electric valves locator input signal is 4—20mA or l ~ 5V electrical signals, but it doesn't need analog digital conversion, can directly send magnetic coil produce electromagnetic force, realizing force balance.
Intelligent valve locator output signal is digital signal, it usually send piezoelectric manifolds, through the piezoelectric manifold to adjust regulator diaphragm head pressure, general electric valve locator output signal is the gas signal after amplified by pneumatic amplifier.
3. The control mode is different. Intelligent valve locator is similar to general computer control device, adopting discrete control mode, therefore, within sampling interval, the regulator opening does not change. During operation, the regulator opening presents stepped-weir changes. General valves locator uses continuous control mode, therefore, the entire control process, the regulator opening change is continuous (except dead zone caused an abrupt change).
4. Feedback signal detection handle is different. In intelligent valve locator, regulator feedback signals must be processed by microprocessor after analog digital conversion, and generally valves locator feedback signals directly as force feedback (moment), do not need analog digital conversion as electrical signals. Some intelligent valve locator input signal adopts standard analog signals, in the same conductor also transmit HART digital signals, composed mixed signal intelligent valve locator, it does not belong to fieldbus intelligent valves locator, but still belongs to intelligent valve locator.
intelligent electric regulator
This kind of regulator uses intelligent servo amplifiers, digital operators, reducing mechanism, valve position detection sending device and electric regulator etc. The main difference with general electric regulator is adopting servo amplifier with intelligent functions. Intelligent servo amplifier is small-sized computer, it receives the standard simulating current or voltage signal, via analog digital conversion as digital signals, by mircoprocessor to compare input signal and setting signal, and calculate according to certain rules operations, output signal after analog digital conversion driving corresponding electric regulator. It is similar with intelligent valve locator pneumatic valve working principle, intelligent motorized regulator main difference is using electric regulator, therefore, output signal transmit motors (can be single phase or three phases motor), and after the deceleration device to change electric valves opening. Intelligent electric valves is also using the setting loop nonlinear characteristics to compensate for controlled object nonlinear characteristics, therefore, avoid the feedback loop nonlinear control systems caused instability phenomena. At the same time, because of using digital means to realize nonlinear compensation, therefore, can according to the pressure drop ratio and required working flow characteristic to determine nonlinear compensation link each line point location.
With fieldbus intelligent valves locator pneumatic regulator
Compared with general intelligent valves locator, this kind of regulator with valve locator features are as belows.
A. the input signal is not standard simulate current or voltage signal, but fieldbus devices digital signal.
B. with communication function, can be easily communicate with superordination machine, realizing data exchange and data sharing.
C. can use directly power-supply modes and the Ann running, conforms to the provisions of the fieldbus relevant standards.
D, may realize open systems interconnection related functions, such as replacement, interoperability, etc.
E. fully digital, two-way communication.
