11 replies to this topic

[onair266]

I'm doing simulation of CDU using HYSYS - V10. I used Crude assay from BP site for Basrahlight16Y. Everything seems ok except sulphur content in the middle distillate. I have three products coming off from CDU, Light Naphtha, Middle Distillate and Atm residue. Sulphur content is middle distillate show only 24 ppm as it is more than 1 % in the input assay. I really seek urgent advice and help to sort out the issue. Hysys support is useless. They are not responding.

[titim]

salut, et le résidu Atm? quelle est la valeur du soufre dans?

[titim]

hello, and the Atm residue? what is the value of sulfur in?

[gegio1960]

hysys provides a lot of good things but it is simply unreliable to provide S distributions in oil cuts.

the reliability increases if you have a very detailed S distribution by lab and you input it -in a very good way- to hysys...but, anyway, it will be a pure mathematical exercise.

hysys support always answers to the subscriber questions....maybe not in the more appropriate way, because it try to be a low cost service

[onair266]

It is 4.81% in atm residue

[onair266]

Thank you gegio1960. What you would suggest other than crude analysis?

[gegio1960]

if you want good answers you should declare your scope...

anyway, for a quick estimate, you can use the few data reported by the mentioned crude assay.

just for starting, if you've kept the TBP cut points of the crude assay, your S content should be something above

(.216*8.2+1.48*17.25+2.88*4.4)/(8.2+17.25+4.4) = 1.34 %w

better is the separation between middle distillate and residue in your simulation, slighter the difference between the estimate figure and the real S content (because you have less residue in the distillate)

good luck!

[onair266]

Thank you so much for the reply. I'm sorry I did not understand your calculation. I'll appreciate if you further explain. The scope is CDU simulation as it's feed to licensor unit where we need to define S contents.

[onair266]

This is what I want to know from the simulation.

[gegio1960]

I used the data reported on the crude assay you mentioned to elaborate a (sample) S balance.

the data used are, simply, S content and yield (wt on crude) for the 3 cuts that build the middle distillate: kero. LGO and HGO.

this kind of data, and not the simulation, are normally used for your scope (ie provide S content of middle distillate fraction to a catalyst vendor/licensor of HDS technology, to select the catalyst and to obtain the yields/performance of the HDS reactor).

good luck!

[onair266]

Thank you so much. Actually we've done this but need the HYSYS do for us.

[gegio1960]

in that case, the basic procedure would be as follows:

a ) define a sulfur distribution curve along the TBP by starting from the few data available in the crude assay.

in other words, you have to decide how much S is contained in narrow cuts of 20-30°C.

the curve would be better if you can find a real S distribution curve for a similar crude (S curves are not like TBP, but are characterized by a kind of "S" shape)

b ) create a Hysys user property for your crude and put the obtained data for each narrow cut

c ) choose a weight mixing rule for the property

d ) run your simulation and see how the user property is calculated by Hysys for your products (wide cuts)

as already told, the calculation is simply mathematics (no chemistry, no thermodynamics) and so the results will be as reliable as the input data (gigo concept always apply!)

Edited by gegio1960, 31 July 2018 - 09:13 AM.