Calculation of steam control valve CV
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Maximum steam flow: 10 t/h. Pressure before the valve: 1.2 Mpa; pressure after the valve: 0.4 Mpa. Steam density: 6.264 kg/m3. Adiabatic index: 1.3. A cage-type sleeve valve is planned to be selected! Help me calculate the CV and select the valve diameter
There is no superheat, no flow on/off; it’s impossible to calculate. A superheat of 0 corresponds to 73.25
https://bbs.hcbbs.com/thread-1578922-1-1.html The expert’s post
1. The pressure before the valve is 1.2 Mpa (gauge pressure); the density of steam is 6.264 kg/m3. Using the formulas from IAPWS-IF97, the corresponding temperature is: 210℃； The saturation temperature corresponding to 1.2 Mpa (gauge pressure) is: 191.6°C. 2. According to the IEC 60534-2-1:2011 standard, for compressible gases, with a known mass flow rate and density, Cv can be calculated as 73.25 (per unit volume of flow). The diameter selected is DN100, with an opening degree of around 80%. If the superheat method is used, the calculated value is Cv=73.18; slight variations may occur in the calculation process due to differences in significant figures.
According to the information on the fourth floor； Why is my calculated CV: 72.36 ； The selected CV value is 125, with a normal opening degree of 83% ； Choose a bore size of 80, with flange connections of 150 or 200 ； :lol:lol
The minimum diameter of the valve seat in your case should be DN100; the diameter of the valve body can be either 100 or 150. The rated CV value should be 175 (125 or 140 is also acceptable if available). I’m not sure what the normal CV value is; it’s probably around 60. Choosing a rated CV value of 100 would be too low.