Dear all, Although I posted this initialy in other forum;somehow feel this forum was appropriate as very lttle response now.

We have revamped our Crude through put.Original Desalter Vessels(2XHorizotal 10 ft ID and 13 ft Tangential Length each)Rate 16000BPD
original design had Normal spring loaded Pressure relieving valve one on each delivering to flare system;that is now undersized.
Now reviewed route is propsed at the inlet pipeline of our preflash tower upstream and the revised scheme shows back pressure on the Relif Valves at the extent of >24% and
Balanced bellow type Relief valves are proposed at theis pipeline,closed to preflash inlet.
My quetion is that is this type suitable?
As the pre-flash Relief Valves open to atmos, the proposed scenario is increasing danger;true or not?
The crude water mix max. flow (i.e. 36000 BPD plus 5% wash water) will have upsetting scenario for preflash internals;true or not?
I have these reservations plus not very much satisfied if Conventional relief valves at least two should be used,instead of bellow type suggested.,The flare system upsizing is needed;I understand.Or the Pre-flash PSV's to be routed to Flare System,Not very sure!
Please help as soon as possible

Further more as of few days back i requested
Dear Art and Phil Hello and Good Afternoon, may I invite your kind attention to throw some light on this or should I pst again in the Industrial Professional's Forum.
Hoping an early positive/professional response covring any aspects might have been missed out,un-identified by me please!
Now I invite help/guidance on the matter as the matter is to be sorted out in correct perspectives.
Best Regards
qalander

Dear,


May I know why it is decided to route the pre-flash PSV to atmosphere?!

Qalander,
I think routing PSV's on a Desalter to a Preflash Tower or Flash Drum is common practice. You must ensure that you'll never send liquid water to the much hotter downstream equipment. In my most recent project, we had a Preflash Drum and its PSV's discharged into the vapors going to the Atmospheric Column. This seems quite sensible to me. Like you, I would be concerned with discharging to atmosphere large volumes of hot hydrocarbon vapors, and suggest you investigate this further. Perhaps the experts you petitioned or others could chime in.

You have identified a potential hazard in the high (and possibly variable) backpressure of the Preflash Tower. Within limits, balanced bellows PSV's can effectively protect your equipment even under conditions you describe. Provided you do an adequate job of identifying your relieving conditions, the PSV vendor should be able to provide a solution. Even if you exceed the capabilities of a balanced bellows PSV, you could go with a pilot operated PSV.

Good luck,
Doug