Process Design: 【One Question per Week】Week 44, 2011: Calculation or estimation of the pressure drop across pipeline valves.
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This post was last edited by crjgood on 2011-11-2 at 12:19. In the process design of long-distance pipelines, the process engineering team needs to provide information to the automation engineering team regarding the pressure difference across the valves. In this way, the control engineering field can calculate the Cv value of valves, thereby selecting the appropriate valves. This differential pressure value is particularly important for valve selection; an inappropriate choice will result in reduced control performance. So, what is the correct and convenient method to determine the differential pressure across the valves in automation systems? Everyone is welcome to discuss this issue. For example, there are methods such as the equivalent length method and the drag coefficient method, but all of these require certain calculations. Are there any practical methods or estimation techniques that are accurate and effective? Everyone is welcome to discuss this as well. For example, in the case of flow control valves, what is typically the pressure difference across the valve, and so on? For example, in the case of pressure control valves, the differential pressure across the valve varies at the maximum and minimum flow rates, and this also affects the selection of the appropriate control valve. So how is the differential pressure corresponding to these two flow rates determined? Last week, the questions were released late, which prevented effective discussion; we will continue to discuss these questions this week, and we hope everyone will participate actively. 1. Those who give positive responses will receive a certain amount of extra points as encouragement, and constructive replies may earn additional points or increased charisma points as appropriate. 2. Please hide replies~
This is generally calculated using simulation, and it seems there is a software available for doing this.
This post was last edited by crjgood on 2011-10-28 at 18:17. It is usually estimated based on the friction loss in the pipeline where the control valve is located; an initial estimate of 70 kPa or 60% of the friction loss is used, with the value that is higher being taken as the standard. Later on, an accurate calculation can be made for the pipeline using the pump curve, so as to provide the instrument with an exact value for Dp.
I’m not from an instrumentation field, but I came to listen; I’m actually thinking about learning it~:handshake
Come and listen, learn*learn*~~
Reply to 2# luoye888: What software is it? Could you be more specific? Thank you~
Aspen and HYSYS can both do the calculations, right?
I want to see how everyone responds first!
Reply to 7# poqwie007: Is the pressure difference before and after calculation done via software manually set?
Come to learn*. Hope to see something new.