What is the process from the field instruments to the display of the entire instrument system on the computers in the control room, and what are the components involved?
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Dear experts: I’m a novice working in a chemical plant and need some help with knowledge related to instruments; please provide some guidance. 1. Control valve (or isolation valve): From the field instrument air supply to the display and operation on the DCS in the control room, what is the process involved in between, and what related instrument devices are there? 2. Level gauges, flow meters, thermometers, pressure gauges: From the field to the display on the DCS, what is the process involved in between, and what additional instrument devices are there?
The DCS generates a current signal to control the piezoelectric element of the control valve; this piezoelectric element in turn controls the amount of instrument air, thereby causing the control valve to move. That’s it – what more is needed?
What are cabinet rooms, card holders, and things like that? I’m not clear about the equipment that is used throughout this entire process and how it operates; I’d like to find out more
Oh my god, that’s way too much! ! ! Just remember: after setting the valve position on the computer, it goes through~~switches··firewalls··DCS controllers~~~~~~~~~~(it’s quite complicated). The current output from the AO card goes to the safety barrier (which may not be used in some cases), then to the field wiring box (which may also not be needed), followed by the locator (either intelligent or mechanical type). The control locator uses piezoelectric elements and amplifiers; the piezoelectric elements control the amount of instrument air supplied, thereby enabling the control valve to move
The computer sends commands to the DCS controller, which in turn generates current signals. These signals pass through the AO card, the safety barrier, the terminal blocks, the field wiring box, the positioner, the valve stem, the position feedback system, another field wiring box, more terminal blocks, the safety barrier, the AI card, the CPU, and finally back to the computer
First, the DCS controller processes the input signals related to level or flow rate, and then uses Ao or Do cards to output commands to control valve positioners or solenoid valves in order to regulate the instrument air.