Proportional and integral time
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I would like to ask the experts here: In a DCS system, what are the typical set values for the proportional gain, integral time, and derivative time of valve regulators? Our system uses a semi-reverse slide valve to control the level of the second secondary material. When automatic control is enabled for this level, the response of the slide valve is slow – what’s the reason for that? For example, when automatic control is set at a material level of 50%, the slide valve starts to move only when the level rises to 60% or even 70%. Please, experts, analyze it for me. I’ve read Ma Bowen’s Q&A on catalytic cracking unit technology; there are formula analyses in it, but I don’t quite understand them. Could some expert please provide a practical example to illustrate this clearly?
For our DCS systems, if the response is slow, increase the value of P – for example, from 0.8 to 1 – and the effect is quite noticeable. (This seems to differ from what is described in the books.) We usually set the integration value between 50 and 300. In fact, once you understand the mechanism behind each parameter, you can choose a control valve that isn’t critical and practice with it; by doing this repeatedly, you will gradually master it.