2 replies to this topic

[runsaep]

Hello!

 

Someone who has performed steady state simulation of gas blowby in Unisim or in Hysys ? I know that steady state is very conservative, but I will do that as a first approach.

 

I know that pressure and level in upstream vessel is important, oil control valve Cv, relieving pressure in downstream vessel. Start level in downstream vessel. But is there some parameter, restraint that I have missed here in order to set up the simulation ?

 

regards Runar Saether, Statoil Norway

[Bobby Strain]

 Runar,        

        I never did such a simulation in any design. I simply calculated the vapor flow along with the normal liquid flow through the valve in the wide open position using the proper valve sizing software. But I suppose that you could simulate the situation by combining the normal liquid flow and a variable gas flow. Then adjust the gas flow until the Cv is that of a fully open valve. You would need to include calculations for the valve pressure drop. Otherwise you can assume a pressure drop (or Cv) and run multiple cases until you get the right value(s). Or through automation via Excel.

       And, often, you need to allow for a fully open bypass valve, too.

 

Bobby

[serra]

as alternative (discussed in several threads here) you may consider the direct integration method,

the procedure is relatively simple (I have been able to solve many problems with Excel + Prode library in areas where the built-in automatic procedure had limits),

you subdivide the whole process in several steps which you  solve in sequence...