8 replies to this topic

[mehdi]

Dear all, in my ammonia plant at co2 removal section , that designed by BASF
we loss alot of CO2 from HP flash drum and we can not control of them if any body
have a experience about this problem please inform me
best regards
m.m.amiri

[Technical Bard]

Answering this question would require far more information, such as flows, compositions, temperature and pressure profiles, equipment dimensions, etc. Comparison of design values to operating data would be recommended to see if you are operating at the same conditions envisioned by the designer.

[mehdi]

Dear Bard thanks for your reply
feed of my ammonia plant is NG then we have limitation on co2, so flow of co2 is important for us
absorber column have a good condition and co2 slipe is lass than design but co2 amount of top of stripper is less than pfd and always urea plant capacity is below 100%
and offgas on top of Hp flash drum is too much mass balance around co2 removal section show us we losses CO2 from HP flash drum but we can not control of this upset

[S.AHMAD]

1. My experience with ammonia/urea plant is not BASF, so I cannot figure out the HP flash drum your are mentioning, unless you submit PFD.
2. Fist step in troubleshooting a plant upset is to gather information/plant data before and during the upset.
3. Then use problem solving technique such as 5-WHY to identify the causal factor/root cause and then verify probable causes with process data available.

[mehdi]

 ammonia.JPG   761.61KB   25 downloadsDear S.AHMAD
very thanks for your attention and i'm sorry for late reply the PFD is attached
flow of gas stream in outlet of HP Flash drum in PFD is 3333 Kg/hr but actually this flow is too much
all condition in co2 removal section is stabile and parameter is same as PFD exceptflow of overhead
of Hp flash drum


thanks
amiri

Edited by mehdi, 15 April 2012 - 10:13 AM.

[S.AHMAD]

Mehdi
1. I am very sorry that I am not that familiar with your BASF PFD.
2. My understanding is that, the vapor flowrate from the HP flash drum T-2003 is higher than design and the HP Flash drum bottom is sent to stripper T-2002. The CO2 from the stripper is sent to urea plant. The HP flash pressure is controlled by PC.
3. I still have some question though. Why do you need the HP flash drum? Where does the HP Flashed vapor go to? Can the vapor be sent to stripper direct? Can the liquid go direct to stripper bypassing HP Flash drum?
4. Have you cantacted the process licencor? What do the say?
5. The only thing that I can say at this moment is that HP Flash vapor flowrate is depending on the flash temperature, pressure and composition I am sure you are aware of these variables. Therefore, you need to determine the right pressure, temperature and composition that will minimize the vapor flowrate. Operate at higher pressure and lower CO2 concentration in at absorber bottom will reduce the flashed vapor. Temperature is fixed by the absorber requirement. Composition could be changed by increasing lean solution flowrate. Pressure can easily be increased by the PC.
6. If these operating parameters do not help in recovering CO2 from the HP flash then most likely you need some plant modifications to improve CO2 recovery.

Edited by S.AHMAD, 15 April 2012 - 09:11 PM.

[mehdi]

Dear S.Ahmad
1-we need the HP flash Drum for purification of CO2 product , the most H2 at rich ammin seperated in Hp flush drum ( H2 in co2 product is not suitable for Urea plant)
2- vapor stream on Hp flush drum have 30% H2 and we send that to fuel line
3-we can not cantacted the process licensor
4- during foaming of system the flow of Hp flush drum ( gas flow ) increase to 2 or 3 time more than pfd flow but at normal condition ( tem., Pre., and..... same as PFD ) this flow is 2 or 3 ton/hr more than PFD

thanks

[S.AHMAD]

Dear Mehdi
1. As I have informed you that I am not familiar to your system, there nothing more for me to contribution in solving your problem. Except for just a few more comments
2. If this a DAY 1 problem? if that is so that the problem is is related to design.
3. If the problem started later, than it is operating problem that you need to identify the root causes.
4. In any troubleshooting, the first-thing that we must have is a set of data before and after the problem. Analyze the data and determine what the differences between are before and after.
5. Then use troubleshooting technique such as "5-WHY" method or better still to use a more complex method such as "Kepner Tregoe".

[mehdi]

Dear S.AHMAD

Many thanks for your attention and your useful comment

M.M.AMIRI