1 reply to this topic

[jangwy]

Hi,

I'm working in a refinery that plans to install an Auto-blending system, but I have a problem in reviewing the system, and I attach a sketch of the current situation and a question.

If anyone can suggest a system to control the booster pump, I'd really appreciate it.

 Question.ppt   230KB   58 downloads

[kkala]

I'm working in a refinery that plans to install an Auto-blending system, but I have a problem in reviewing the system, and I attach a sketch of the current situation and a question.
If anyone can suggest a system to control the booster pump, I'd really appreciate it.
 Question.ppt   230KB   58 downloads

1. Booster pump should have minimum flow return, as pumps 1, 2, 3 have (return of mixed products to one original "base" is assumed permissible).
2. Flow rates for each product are determined through FCVs 1,2,3 and the "program" (installed on PLC or the DCS); booster pump discharge pressure should be controlled (depending on destination tank for product 3, 4, 5) (*). Install new PI2 and PCV2 downstream of this pump.
3. Shifting PCV1 and PI to the branch towards Product 1, 2 is recommended. It is not certain that present position shall create problems though.
4. Startup flow will be 20% of 5000 BPH, which might cover booster pump minimum flow requirement. Specify 1000 BPH as minimum flow of the booster pump. Whenever you intend to fill with product 3, or 4, or 5: at startup close discharge valve of booster pump and let flow circulate through its minimum flow return. Then gradually open the discharge valve and let booster pump operate under pressure control through PT2 / PCV2, whose set point depends on destination tank (Product 3, 4, 5). Most probably an extension of the "program" can do all this sequence automatically, taking also input from FT1; if so, PCV2 is identical to mentioned "discharge valve of booster pump".
5. In brief, install PI2 / PCV2 at booster pump discharge , similarly to PI / PCV1 already operating at the discharge of Pumps 1, 2, 3. Issues per (4) above may have been faced(at least partially) in the past, when tanks of Product 1, 2 were filled.
6. There may be better alternatives and above one has not clarified all issues. E.g. a closed discharge valve of booster pump might cause minimum flow of Pumps 1, 2, 3, leaving no minimum flow to the booster pump. But hopefully it helps a bit.

PS: I had seen the questions on next page of the attachment too late, but these seem to be covered.
(*) Text corrected at this point on 13 Apr 10; see thread "PCV in blending manifold" in this forum by go-fish (12 Apr 10), where role of PCV downstream static mixture is discussed. In case of different tanks downstream PCV (this case) set can change manually depending on destination, though this is not the principal role of PCV.

Edited by kkala, 13 April 2010 - 04:45 PM.