5 replies to this topic

[arvind]

Hi,

I am working for midstream project, for Oil treatment facility.

Brief Process:- In this facility crude is dehydrated and desalted then send it to crude oil stripper and Produce water send to saour water stripper. Fuel gas is using for stripping media for both Crude oil stripper and Sour water stripper at 23°C
For crude oil stripper Crude oil inlet is 400000 kg/hr and fuel gas 1300 kg/hr
Crude oil data:
density 850 kg/hr
viscocity- 6.5 kg/hr
fuel gas
inlet pressure 4 barg
Mol wt. 21
(stripping column use to lower the H2S concentration from 300 ppmwt. to 15 ppm wt.)
Column has been simulated for using 3 theoretical stages (Ideal)using hysys. but i need to calculate the actual number of stages, using overall column efficiency.
can anyone please guide me how to calculate column (tray) efficiency (in absence of similar plant data?

same regarding the Sour water stripper..


Your reply is highly appreciated.


Arvind

[arvind]

Hi,

could it possible it use O Connel rellation, ( Refer Perry - 8th Edition chapter 14, page 14-12)
plate efficiency Vs HP/viscosity

I have calculated it for Sour water stripper it arrives 7 %

Is it also depends on type of tray? (as in my simulation I have considered the ideal trays 2 ?)

I dont sure can anyone please guide me.....


Thanks and regards


Arvind

[Zauberberg]

Are you designing a new tower, or troubleshooting an existing one? Why do you need efficiencies?

[arvind]

Are you designing a new tower, or troubleshooting an existing one? Why do you need efficiencies?

Hi,

I am designing new one ( crude oil stripper )
from simulation I have calculated 4 numbers of Ideal stages, I wanted to calculate the actual numbe of stages. (Yes it can be obtain from vendor but I want to calculate and cross check with vendor)

for this perpoese we are going for movable Valve tray.


Arvind

[Zauberberg]

I think it's very difficult to calculate tray efficiency "in advance", even if you apply rigorous numerical methods (see attached example) - a lot of values you can find in the literature are experience-based. Even the vendors have similar guidelines based on previous installations.

In addition to that, stage efficiency changes with liquid/vapor loads (flows), their properties (which could be calculated erroneously if you rely on simulator models) and, even more important, they change across the tower so that uniform efficiency cannot be applied in almost every case.

You have to believe to the vendor, and you have a backup for that: process guarantee points for which the vendor is held responsible. One useful thing you could do, though, is to ask for references in similar or identical service/installation. From there you can get a sense of what is the overall efficiency of column internals. Also remember to include the Foaming Factor as it affects column dimensions in significant proportions.

Attached Files

•  A Simple Application of Murphree Tray Efficiency to Separation Processes.pdf   61.8KB   261 downloads
•  Process Simulators GPA-05.pdf   148.21KB   245 downloads

[arvind]

I think it's very difficult to calculate tray efficiency "in advance", even if you apply rigorous numerical methods (see attached example) - a lot of values you can find in the literature are experience-based. Even the vendors have similar guidelines based on previous installations.

In addition to that, stage efficiency changes with liquid/vapor loads (flows), their properties (which could be calculated erroneously if you rely on simulator models) and, even more important, they change across the tower so that uniform efficiency cannot be applied in almost every case.

You have to believe to the vendor, and you have a backup for that: process guarantee points for which the vendor is held responsible. One useful thing you could do, though, is to ask for references in similar or identical service/installation. From there you can get a sense of what is the overall efficiency of column internals. Also remember to include the Foaming Factor as it affects column dimensions in significant proportions.

Thanks Zauberberg...