How can the instrument control of a distillation tower be made more stable?
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How do the controls regulate temperature, feed rate, production rate, and return flow? I’m trying to adjust the parameters in this single-loop system, but none of them remain stable. I’d like to ask how others go about adjusting these settings or what the logic is behind it; I’d like to learn from it!
Flow meters, control valves, and shut-off valves suitable for the operating conditions are installed for feeding, extraction, and reflux. Additionally, the liquid level, temperature, and pressure inside the tank must be monitored. During calibration, a fixed test value is chosen; for example, if the temperature or pressure is to remain constant, then by gradually adjusting the feeding rate, it is checked whether there are any changes in temperature or pressure. If such changes occur, feeding is stopped and either reflux or feeding is initiated to see if the temperature or pressure returns to normal levels. Then, by adjusting the feeding and discharge valves, the behavior of the system is explored, with attention paid to the temperature and pressure values throughout the process. It takes some time to get the PID control working properly.
First, stabilize the feed and discharge. If temperature control is difficult, manual control can be used temporarily
This post was last edited by 1111111 on 2018-5-27 09:14. Keep a close eye on the liquid level, ensure accurate and stable measurement of it; focus entirely on adjusting the level until it’s correct. Additionally, the step size of the control valve should be precise enough. If a valve with such high precision isn’t available, two valves of different sizes can be used together for adjustment – this makes it easier to control the precision, and it is likely to cost less as well. However, the algorithm for switching between the two valves will require writing some small programs. Beautiful love is always devoted; perfect adjustments are always unique. When multiple factors are mixed together haphazardly, with indecision and carelessness, it’s easy for things to become unstable. . . Friendly reminder: He has never adjusted a single power unit of industrial scale. I don’t understand high-voltage electricity; I’m a complete novice in it. I have only adjusted desktop-type micro-pressure control devices; taking 1 MPa as an example, I can adjust the pressure so that it remains constant within the range of (1±0.00001) MPa. Brother said those words above based on his experience of adjusting the pressure using this small container. Although the methods used to adjust content may vary, the underlying principles are similar and can be used as a reference. . . I hope my brother isn’t leading you astray. .
I guess the pressure control device system you’ve set up is relatively simple
The feed flow rate also cannot be stabilized. Under normal operation, the valve should be set at 30% open; I think the valve selected is too large, and I’d like to use one that is smaller. Moreover, this control valve is installed at the pump outlet, so the pressures before and after the valve that I provide are not accurate. Do the pressures before and after the valve refer to the condition when the valve is closed or when it is in normal operation?
The feed flow rate also cannot be stabilized. Under normal operation, the valve should be set at 30% open; I think the valve selected is too large, and I’d like to use one that is smaller. Moreover, this control valve is installed at the pump outlet, so the pressures before and after the valve that I provide are not accurate. Do the pressures before and after the valve refer to the condition when the valve is closed or when it is in normal operation?
The pressures before and after the valve represent the pressures under normal operation; if the pressure at the pump outlet is high, the manual valve in front of the control valve can be adjusted to a lower setting
Also, do not set the dead zone of the on-site valve positioner to be too large
Adjusting a control valve is a delicate task that requires slowly adjusting several variables, one by one
The valve should not be placed too close to the pump outlet; maintain a certain distance between them. As mentioned above, for the manual valve located ahead, if the pressure at the pump outlet is high or unstable, adjust the manual valve to a smaller setting. If that doesn’t work, invest some money to have someone from the valve manufacturer come and help you make the adjustments