7 replies to this topic

[process16]

hi all!!

i have a shell and tube heat exchanger with a surface of 479 ft² to treat 70000 barrel of crude oil / day

i mad a calculation  to find the surface nedded to treat 20000 barrel /day

i found the suface =139 ft²

how will the new surface will effect on the exchager, what kind of problem can be appear in this  case???

ans what we can propose as solution???

 

2/ if the speed of the crude inside tubes gets lower , would that make problems too???

Edited by process16, 04 July 2015 - 07:59 AM.

[srfish]

The lower velocity inside the tubes could cause problems. It depends on what is contained inside the crude oil.

[Alfred210]

The turndown ratio is 29% which is too low for the typical design of 50%. Too low velocity will cause lower heat transfer and most importantly, much higher fouling rate which will reduce your run length. You still can run the heat exchanger, but with much less efficient.

 

Please provide more information regarding the layout and control for better solution.

[process16]

ok I will give you more information

tubulair heat exchager with a surface of 479 ft² , 196 tubes, 2passes tube side, one passes shell side

tube side crude oil

shell side hot oil ( Dowtherm )

after th calculation i found that we need a surface of 139 ft²  to get the required temperatur of crude oil

i need to make an intrepretation what will this surface cause ? is there any calculation i have to make ?

what if i changed somme given to get at least a 50% of the surface to avoid fouling ( because i can chage the flowrate of hot oil )

[gegio1960]

how did you obtain 139 ft2?

this figure is very similar to 479*2/7 that means you've considered the same U for the STHE (if the temperatures remain the same)...

it seems you're very far from the solution.

good luck!

 

ps: please kindly take into account what zauzerberg already told you only 1 month ago

http://www.cheresour...-verification/ 

Edited by gegio1960, 05 July 2015 - 11:21 PM.

[process16]

crud oil condition is given

* inlet and out let temperatur

* the flow rate

about hot oil i have just the inlet temperature, i have to choose the other parameters with out ignoring (process parametrs)

i mad a full calculation by using the exchanger data sheet

my results are correct

i guess that i have to use a lower flow rate of hot oil ,  but i neeed an argument why i should use it and why i have to get at least 50%.

of designe surface

[AlertO]

as gegio1960 mention, you might go with the wrong U of the exchanger. The lower flow rate reduce the fluid velocity in the tube as well as the heat transfer coeff. please aware this.

 

good luck.

[process16]

as gegio1960 mention, you might go with the wrong U of the exchanger. The lower flow rate reduce the fluid velocity in the tube as well as the heat transfer coeff. please aware this.

 

good luck.

whene the flow rate of crude oil get lower and you use a hight flow rate of hot oil , the surface sur will be lower

i thin its  clear whene this exchanger treat 70000 barrel/day  sur with 20000 barrel we need an other surface  less than the first!!

Edited by process16, 08 July 2015 - 03:50 AM.