8 replies to this topic

[Preeti Shetty]

Good Afternoon Everyone,

 

I am sizing a Transfer Line i.e. from Furnace heater to the inlet of column, I have sized this line based on two phase line sizing criteria. I needed the Transfer line sizing criteria, like what parameters need to be checked while sizing transfer line as these line are critical lines.

 

Thank you,

 

Preeti.

[Himanshu Sharma]

if the column in question is a  Vacuum Column ?

[Preeti Shetty]

Hi,

Thanks for your response

 

The column is not a VDU its a Crude Distillation Tower operating at 2.5 bara.

 

Preeti S.

[AzoTik1985]

You have to keep annular regime in transfer line. Line should not be sharp turns.

[Himanshu Sharma]

well life is comparatively easier if it's an atmospheric Column rather than a Vacuum Column !

 

Please take care of Following

 

1.Annular flow Regime is most stable amd most preferable for any General Two-phase flow ,however also check for flow ragimes at turndown flowrates also and advise Mechanical piping group for proper supports.I would also prefer to size line in segments as per varying operating pressure along the length from variousheater passes to the Main tranfser line  (however that is more significant in case of vacuum heater/Column)

 

2.Ensure that pressure drop in the line matches with Furnace Outlet pressure(Infact heater and transfer line hydraulics should be done simultaneously)

 if Pressure Drop is higher Builtup backpressure at Furnace Outlet is more than it was designed and hence there are chances of         coking

if Pressure Drop is lower that designed Heater Oulet pressure there may be more flashing and increased velocity thereof may erode lines/cause piping supoort issues.

 

3.Try to minimize the run length  ,long transfer lines with many crosses and tee’s will rapidly coke and increase the pressure on the furnace which usually results in increased fouling of the tubes in the furnace.

 

4.For Design Pressure consideration,Calculate backwards from Column Maximum operating pressure and keep on adding dynamic loss elements.

 

5.Design Temperature is genreally governed by Heater COT.

 

Hope this helps,

 

Regards

Himanshu

[TechExpert]

Are there specific softwares for design of transfer lines?? 

[Himanshu Sharma]

PKS,

 

Well i am not aware of any software for transfer line sizing,we generally combine simulation(Pro-II) and Hydraulics softwares(In-house) for this sizing,needless to say Engineering acumen governs all !

 

Regards

Himanshu

[AzoTik1985]

I use Pro/II+Pipephase.