5 replies to this topic

[srihari]

I am working with LPG fractination project.  In our plant liquid blow down are provided at LPG Dehydrator drum , to depressurize to Hydro carbon sump drum in case of fire or emergencies.

 

LPG dehydrator is operating at 38 Barg and 40 C and flow rate 208920 kg/hr.

 

I have used hysys dynamic depressurization tool to find the peak flow rate for a duration of 4 Hrs for the design case : Fire  but the results are not matching with the plant data.

 

Can we use hysys tool to find peak flow rate for liquid blow down

 

 

 

 

 

 

[PaoloPemi]

some depressuring utilities (as example, that included in Prode) allow to select the vapor or the liquid side,
maybe you can do the same, these tools should be able to estimate peak flows...
it is not clear the meaning of "the results are not matching with the plant data"
Do you wish to obtain the same values calculated at design stage ?
If you have access to these values maybe you can obtain or estimate the inputs to utilize in your simulation...

[Padmakar Katre]

Hi,

I have used this utility in Hysys plenty of times in past and I can say it's reasonably good. It depends on how you model the system.

Please come with specific issue rather a general statement like 'it doesn't match with plant data' which is really unclear.

[srihari]

LPG dehydrator design pressure is 58.6 Barg . If emergency depressurization activates, liquid blow down valves will open for 4 hrs and it will depressurize to HC sump drum which is operating at 0.5 barg.

 

I have given the simulation link and process data attached here 

 

http://www.4shared.c...ehydration.html

 

Based on simulation , after depressurization destination pressure become negative

 

please check my simulation file , whether some parameters needs to be modified??

Attached Files

•  Condensate dehydration depressurization.docx   53.87KB   34 downloads

[PaoloPemi]

the final pressure can't be negative (meaning below 0 abs) but  that you have specified (within solver tolerance),

as said I do these cal's quite regularly with another tool (Prode Properties) and never found problems except with wrong specs,

which could be your case...

.. 

[srihari]

i am getting negative pressure after 2 to 4 sec of simulation initialization