12 replies to this topic

[daniwibowo8]

Dear Sir/Madam,

 

do you have any advice or experience for hydrolysis reaction begin? any reference for calculation the initial temperature for hydrolysis take place?

We have crude desalter and the inlet crude temperature now increase after crude preheat got tube bundle cleaning.

 

I was trying to use hysys but NaCl and Crude have different property package (NaCl = NTRL) and crude (peng robinson). 

 

Regards, DW

[PingPong]

It is not NaCl but MgCl₂ and CaCl₂ that you should focus on:

http://www.cheresour...alting-process/

[daniwibowo8]

Dear PingPong,

 

Highly appreciate for prompt response and good citation.

 

Do you have any reference for hydrolysis of NaCl/MgCl2/CaCl2 to be fouling substance if desalter inlet temperature too high like below reaction:

 

CaCl2 (s) + H2O (l) --> CaO (s) + 2HCl (l) 

 

MgCl2 (s) + H2O (l) --> MgO (s) + 2HCl (l) 

 

NaCl (s) + H2O (l) --> NaCl (s) + H2O (l)

 

Thank you again.

[PingPong]

CaO or MgO cannot form in presence of water.

[daniwibowo8]

Dear PingPong,

 

Is it possible that reaction take place and CaO/MgO dissolved in crude stream and makes exchanger/furnace fouling?

 

I just read some website and advise that desalter temparature should less than 150 deg C and the reason is above reaction and reliability of electrical busings.

 

We have petreco bilectric desalter which have high temp alarm at 157 deg C but i am truly confused why our alram setting higher than the common practice (150 deg C).

 

Regards, dani

[PingPong]

I just read some website and advise that desalter temparature should less than 150 deg C and the reason is above reaction

Which website?

[gegio1960]

my 2 cents....

the operating limit of 150°C is usually considered for the mechanical resistance of (teflon) bushing materials. of course there are some engineering margins on this figure: so that 157°C is acceptable as high temperature alarm set point.

as a refinery process engineer, I never had to think about the hydrolisis of salts to identify the operating temperature limit in a desalter. instead I had to think about the variations of density and viscosity, of crude and water, with the temperature.

The following link reports an interesting discussion on the desalter operations...

http://www.ogj.com/a...avy-crudes.html

good luck!

[daniwibowo8]

Dear Pingpong,

 

I found at http://kolmetz.com/p...tem_rev_web.pdf

 

 

Hi Gegio,

Thank you for your suggestion. Do your lab always check for crude viscosity for daily/weekly basis to make sure process engineer able to evaluate desalter performance? i will consider your suggestion and ask our lab guys to do the same since i believe it is very important.

 

I apologize that i cannot get full access to ogj.

 

one more question geggio. any suggestion for better desalter monitoring ? for example salt balance or other things?

 

Regards, DW

[PingPong]

I found at http://kolmetz.com/p...tem_rev_web.pdf

Formation of Na₂O or CaO or MgO cannot occur in the presence of free water, like in a desalter.

 

Only if all free water is vaporized, like in the crude heater, formation of such oxides might occur.

[daniwibowo8]

Dear PingPong,

 

Duly noted for deposit formation will only happened at furnace.

Please kindly share us the reference so i able put the reference on my desalter evaluation.

 

Regards, dw

[gegio1960]

Hi DW.

The content of the OGJ article is herewith attached.....

Viscosity of crude is a quite stable property, once you maintain unchanged (the crude and) the temperature. So, more than a continuous monitoring, it is better to have a "viscosity chart" providing a quick reference of the viscosity variation with the temperature (one line for each crude processed in your CDU).

Of course, monitoring of salt and water content at Desalter outlet, are very useful to quickly have an evidence of (possible) troubles.

Salt content at Desalter inlet is, as viscosity, a constant if you don't change the crude and/or the tank of origin.

Just to better understand the situation:

- which crudes are you processing?

- what are the relevant temperature (range) at Desalter inlet?

- what is the target (design) and the actual salt and water content at desalter outlet?

Good luck!

Attached Files

•  Optimizing desalter operations.pdf   319.95KB   38 downloads

[daniwibowo8]

Dear Gegio,

 

Thank you for your suggestion and share us the journal.

we are facing challenges in crude processing since we have so many different crude as feed.

The crude may change in even 1 day.

 

Regards, DW

[gegio1960]

a teapot is a very different story....