high pressure high flow gas reducing regulator for a PRU station

[Alyreza]

Hello engineers,

I need a graphical modeling and simulation software for simulation of a Pressure Reduction Unit of a natural gas daughter station.

I have to calculate outlet temperature of a regulator.

inlet pressure of first regulator: 200 bar
outlet pressure of first regulator: 15 bar
inlet temperature after gas-preheating: 80 C

I am sure that I must use real gas formulas but I don't know them.

Please help me in this fields:

1-Introduce a software for simulation and modeling a PRU or CGS station graphically to print PFD
2-tell me the formulas of real gas for a gas regulator
Thank you