4 replies to this topic

[ahyong]

Dear All,

 

Lately I've been haunted by this new task which is to verify the pressure and temperature at KO Drum that provided by FEED Company by using Flare System Analyzer. This is my very first time and I am so confused. Though assistance is provided but questions keep arising and I hope you could kindly give me some guide. Please refer to the attachment for my questions and looking forward to your replies.  Flare System Analyzer.xlsx   42.84KB   201 downloads

[flarenuf]

hello ahyong
sad to hear yet another young engineer has been set a task with insufficient guidance from senior engineers on what to do .
Lets see if I can assist you

 

1) you must model the blocked outlet ( BO) in AFSA , you cannot take account of the BDV being opened by the operator. What if he fell over on the way to open the BDV ? the PSV must provide protection to the vessel.

Model the PSV to flare with the load set at the BO required rate, at the set pressure of the PSV of course and not 92%

2)_  the PCV will normally control the pressure in the tank by venting gas to flare . If it fails open then you will have  a flow of gas to flare, amount will be determined by the capacity of the PCV based on the pressure in the tank.
  If the PCV failed closed or became stuck in the closed position then the PRV , i assume this is a PSV, would open if the pressure rose above the tank design P and vent to flare.

 

3) you cannot model anything in AFSA without the pipe lengths and diameters , you are wasting your time here. The FEED Co must have this information as you say you are to verify their calculations. do you not have any information at all ? if No then you must get some otherwise you cannot do anything.
I am also surprised that you have warm wet and cold dry reliefs going into the same KO drum, you could have major problems with liquid knoc out, hydrates or thermal shock  mixing these.

4) they most likely did a different AFSA model for this , if at all .
 

5) AFSA will work in MW only but  if you have a HMB then you should get the detailed composition.

having read through your problems here i cannot believe that you have been asked to verify the FEED co workings without being given their AFSA model or sufficient other data. You do not have enough information to do anything ahyong. I could not do this for you given what you have been told , and i have 30 yrs experience in this field ..

go back to your boss and say you need more information or better still the AFSA model .

 

flarenuf

[ahyong]

 FST.xlsx   102.7KB   80 downloads

hello ahyong
sad to hear yet another young engineer has been set a task with insufficient guidance from senior engineers on what to do .
Lets see if I can assist you.....

 

Dear Sir Flarenuf,

Thank you for your detailed explanation.

2) Sir, I attached the relief system of the Flow Suction Tank for your review. The scenario is blanketing PCV wide open (one FST + one DWT combined with VRC failure. The downstream of the tank will be connected to tank flare header. I need your guidance in this case on how to sketch the network in AFSA.

 

3) My boss asked me to measure the pipe distance on the plot plan and multiply it by 2 for fitting. Is it workable? As i cant find any pipe length measurement from the documents provided in ITB.

 

5) When I first stated the AFSA, the composition input window pop out and asked me to key in composition. You mentioned that AFSA doestn work with composition but only MW. So in this case, if i just key in the MW, AFSA will automatically count the composition for me? I dont understand how it really works and kindly need your guidance.

 

Finally, the FEED Company did provide us with  "Flare, Relief and Blowdown Study Report and the Flare System Network model. But since the drawing is printscreened and attached, I cant really see it clearly. You mentioned that normally length of pipe from source to destination is provided, may I know normally where will FEED Company attached this file to? In case I missed it.

 

Thank you and have a nice day

 

 

Edited by ahyong, 15 July 2013 - 06:36 PM.

[flarenuf]

ahyong

 

!) firstly if you have never used AFSA , which i ssupect i suggest you run through the worked examples in the manual in order to gain some idea 

 

2) i cannot read the dwg properly

 

3) multiplying the plot plan length by 2 could work but there again so could 3,  you should be able to get a better idea from the P&ID and line list as to exact lengths

 

4) what i meant is that AFSA will work with composition or MW only, you still have to provide the components you are using though. Run through the worked examples to learn this .!!

5) if you have the Flare network model , as you say you do then all the compositions, lengths and diameters will be in there surely .

 

flarenuf
 

[ahyong]

Sure! Thank you for your help!~