3 replies to this topic

[garych]

Hi, do anyone have experience in simulating tube rupture dynamic simulation?

 

I am trying to reach an optimum point which shutdown valve can close asap without letting the process gas (shell side) reaching into the utility system (tube side)  and also to ensure that pipeline design pressure can cater the surge pressure.

 

My results show that:

Case 1:

SDV A at the shell side pipeline closing time : 4 sec

SDV B at the tube side pipeline closing time :  1 sec

The peak flowrate that occurs at SDV A inlet = 1000m3/hr

 

Case 2:

SDV A at the shell side pipeline closing time : 4 sec

SDV B at the tube side pipeline closing time : 0.5sec

The peak flowrate that occurs at SDV A inlet = 1000m3/hr

 

I changed the SDV A closing time to ( 0.9sec, 0.8sec, 0.7sec,). Just trial even though the closing time seems to be no realistic in real plant.  The result that i got for the peak flowrate at the SDV A inlet is stil 1000m3/hr.

 

 

Is this result reliable? Just couldn't figure out why the peak flowrate stays the same eventhough i try to reduce the closing time. Is it something related to valve choked flow or any relevant issue??

 

 

[serra]

what do you mean for "dynamic" simulation ?
you can only estimate the flow from pipe due to rupture (unless you know in advance the exact cause and can create a perhaps more accurate model),

you know the volumes,

couldn't you simply integrate to find the solution ?

To answer your question, you should evaluate speed of sound (critical conditions)  in the different sections, the speed of sound can limit (maximum) flow.

[garych]

I create an event in which the tube rupture occurs when a high pressure is detected at the tube side using the hysys dynamic simulator.

In hysys, we can input the actuator closing time, so that's how i come out with the gas volume.

What do you mean by integrating the solution?..

[serra]

as first step you should attempt to estimate the flow due to tube rupture,
that may be not easy as it may appear utilizing the graphics on a simulator,
you may detect critical flow, chocking flow etc.
and may wish to adopt specific correlations (there are several which give different results, you may also adopt a specific flash operation, for example, constant energy which is available in Prode and other software)
a simulator gives limited or no control on these aspects,
once you know the flow and know the volumes (in different sections of the plant) it wouldn't be that difficult to integrate (with Excel or Matlab I solve at regular intervals keeping values of flow constant over each interval) to find the solution (i.e. flows & pressures vs. time).
You can find many textbooks discussing the matter and perhaps some reading may be useful,
to put it simply, how do you intend to validate the results from the software if you don't have a sufficient knowledge of the model ?

(I assume you wish to solve a real problem not  discussing the features of a sofware)