8.3. Control valve and pressure regulator modelling
Any hydraulic system contains pressure regulating elements. The EA-PSM element library already contains a lot of natural gas pressure regulators, however EA-PSM gives the user the ability to model valve models based on sizing coefficients and flow tables.
The hydraulic valve modelling window is opened in the drop-down menu "Modelling"->"Valves".
First, the user should define the manufacturer and model of the valve. Different valves (control valve or pressure regulator) are defined differently, therefore it is important to choose the correct valve type. For example natural gas pressure regulator documentations usually depict a flow table, which can be imported to EA-PSM.
In the followind section of the window the user may define maximum inlet pressure, nominal pressure. The user must define the flowing material. Dimensions of the valve are not important. Parameter "Rangeability" is critical for calculations: it is the ratio of maximum controllable flow to minimum controllable flow. A ratio of 50:1 is defined as 50.
For the "Control valve" the valve size coefficient K or Cv is needed, as well as opening type. The user should also define the nominal valve flow and conditions (STP - standard temperature pressure, NTP - normal temperatūra slėgis).
"Pressure regulator" type requires a flow table - flow values should be defined at different outlet pressures. (The dimension for these values are defined at fields "Pressure setting unit" and "Nominal flow unit/conditions". The pressure regulators also have "Lockup pressure" SG and "Accuracy class" AC parameters which are given by the manufacturers.
The next picture is an example of a manufacturer "Schlumberger" pressure regulator model "RR-16" flow table given in the documentation.
Pressure regulator model flow tables can be imported from "Excel" sheets. If only the sizing values Cg and K1 are given, the flow tables can be generated with the flow table generation template (exported by clicking the button
). The description of these sizing coefficients is given in the template file. In the template file the user should input the maximum and minimum inlet and outlet pressures, as well as Cg and K1 values for different nominal diameter valves. Once the parameters are defined, the flow tables are automatically generated and the user is able to import the .xls file by clicking the button
.
It is necessary to fill these fields before importing the .XLS:
-
-
-
Flowing material - given by the manufacturer
-
Lockup pressure, SG - given by the manufacturer
-
Accuracy class, AC - given by the manufacturer
-
Nominal flow conditions (STP, NTP, - )
Clicking the import button will prompt the user to choose one of the two options:
-
Use default/multiple-sheet import: the template .XLS file is used to import the pressure regulator models. Different valve models are generated for every nominal pressure and diameter. To proceed, choose the file and click "Import".
-
Use custom sheet import: a single table is imported from an Excel sheet. The sheet numbering starts at 0. In the first column of the table inlet pressures (bar) are defined. In the first row - outlet pressures (bar) are defined. The flow values should be defined in m
3/h. In the following example the parameters should be defined as such:
-
-
-
-
