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.
2011-04-12