Due to uncertainties such as piping issues, how can the pressure drops of flow control valves, pressure control valves, liquid control valves, etc. be determined?
Thread Content
During the process package design phase, due to uncertainties such as piping issues and various other factors related to the location of valves, it is difficult to determine the pressure drops before and after valves such as flow control valves, pressure control valves, and liquid control valves How to specify the pressure values before and after the valve in the data sheet of a control valve (these values are relevant to the selection of the control valve)? Please provide details, thank you! Comrades, stop talking nonsense if you want to earn points, so as not to confuse a newbie like me!
If the piping is uncertain, then it’s unclear how the head of your pump was determined; it’s really confusing.
We are in the preliminary design phase; the position of the control valves and the layout of the pipelines need to be determined during the detailed design stage. How can I estimate the pressure drop across the control valves at this point?
Wait, are you from the process engineering field? Those in automation control don’t need to calculate this. Ask the process team!
This matter is not related to the instrumentation field; it was proposed by the process engineering team, and the selection is made based on the conditions put forward. When designing, it’s essential to clarify the division of labor among different specialties; otherwise, things will get complicated. It’s mainly a matter of coordination between these specialties.
Judging from the poster’s words, it seems to be a small design firm, so they need to consider these issues on their own? Generally speaking, determining pressure drops is the task of chemical process engineers; they estimate the appropriate pressure drops in various throttling elements such as pipes, control valves, and flow meters, based on the flow rate. Then, according to these pressure drops and the requirements of the system, they decide on the head required for pumps, compressors, etc. So the pressure drop of the control valve is not determined by the people in the control department; it is fixed from the very beginning. If you are carrying out equipment modification, then find out the capacity headroom of the pump (or compressor), and determine the pressure drop of the control valve that was used before (rough figures for flow rate can be obtained based on the valve model); this can serve as a basis for determining the pressure drop of the valve after the modification. If you are aiming to evaluate the pressure drop of an existing device, you can simply examine the characteristic curve of the valve, look at the relationship between flow rate, pressure drop, and valve opening degree, and thus determine the valve’s pressure drop.
Simply put, if the process does not provide relevant data, it is impossible to determine the diameter of the control valve! Understood? Whether you are in a large design firm or a small one, this is a procedure.
That being said, those of us in the control field should work in conjunction with the process piping team. In my company, sometimes the process department cannot provide appropriate values, and we then help them determine the parameters, so that the process conditions can be adjusted!
Regardless of the selection of the primary instrument, the requirements are determined by the process. The instrumentation personnel select the appropriate models based on the process conditions, and then provide feedback on the connection methods and dimensions of the instruments to the piping and equipment designers. Take a look at the link below; it might be useful: http://bbs.hcbbs.com/viewthread.php?tid=141997&extra=page%3D1&frombbs=1. This post was last edited by spccjp on 2008-1-17 at 19:48.]