Regarding control valves
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Hello everyone. I am currently working on a sulfur recovery project, and there is an outlet pipeline in the tube side of a heat exchanger for which a control valve is needed. The operating pressure of this pipeline is 0.65 MPa, and the temperature is 42 degrees Celsius. I would like to know how the pressure before and after the valve are determined – is it related to the operating pressure of the pipeline? Is this pressure difference calculated or based on empirical values? If it’s calculated, how is it done? And if it’s based on empirical values, where can such values be found? Please advise me, thank you! ! !
Please give me your guidance, experts. Perhaps my question is simple, or maybe I haven’t expressed myself clearly. Please help this beginner like me to grow faster
The calculated pressure difference for selecting a control valve is primarily determined based on the pressure drop in the system, which is composed of process pipelines, equipment, etc., as well as any changes in that pressure drop. The steps are roughly as follows: 1. Select two constant-pressure points in the system, and use the two devices with the most stable pressures immediately before and after the control valve as the scope for system calculations. 2. Calculate the total pressure loss YZ caused by the local resistance of various devices or piping components in the system (except control valves), by performing calculations for each maximum flow rate to determine the sum of their pressure losses. Calculating resistance is a rather tedious and complex task. 3. Select the s value. The s-value is the ratio of the pressure difference QK when the control valve is fully open to the sum of the system pressure losses XYZ. s=QK/(YZ+XYZ) 4. Calculate the operating pressure difference JYZ for the control valve. JYZ=sYZ/(1-s)