13 replies to this topic

[Arsal]

what is the typical composition of refinery gases (mol%) of arabian light crude.?I have different testing results of refinery gases(sample taken from top of the reflux drum).all time different results were obtained.in some results Methane around 70 mol% and some cases butane 60 %.i want to know what is basically the Typical composition range of off gasses during arabian light crude processing...........

[PingPong]

Crude oil will contain very little methane. So if there are no other feed streams to the crude column than crude oil, then on the days that you measure 70 % methane there probably was oil cracking in the crude charge heater.

You should find out whether there is a relation between methane content of reflux drum gas and heater outlet temperature.

 

But it is also possible that the laboratory measurements are simply wrong.....

[Arsal]

Thank you pingpong,

I have just asked what is typical composition of refinery gases??,which is usually used as fuel gas via compressor.I think sampling error might be the result of high methane content.and cracking is not possible at our conditions because we have preflash column and these gases is recovering from Preflash reflux drum.

 

Normally the heater outlet temp in the range of 650-680 F (Depends upon Crude oil) and in case of arab light crude Cracking will occur after ~ 750 F.

 

If any body share the typical compostion, then it will be very helpful for me.

[PingPong]

The gas quantity and composition from the Preflash reflux drum will depend on the temperature and pressure in that reflux drum, as well as the amount of naphtha product (wt % on crude) from that reflux drum. Part of the lights from the crude (C3's and especially C4's) will dissolve in the naphtha product, and part of the naphtha (C5 plus) will end up in the gas product from the reflux drum.

 

So there is not really a typical gas composition, it depends not only on the crude but also on the particular design and operation of the unit.

 

In any case: I have never seen an assay of Arab Light (or any other similar crude), that showed a methane composition. So if your lab measures a lot of methane in Preflash gas you know that they are amateurs.

And that puts also doubt on any other measurements that are done by the same person and/or same apparatus.

[Arsal]

Thank pingpong,

 

Preflash reflux drum,there is a split range controll installed at vessel.makeup requirement fullfilled by natural gas,whenever makeup required in the vessel.I am quite sure that when sample was collected this makeup valve was maximum open thats why the methane contents report on higher side.

[PingPong]

Makes sense.

 

Please note that if you had mentioned right away that this was a Preflash reflux drum (so C1 due to cracking in crude heater), with a split-range PC that every now and then adds natural gas (so also a C1 rich feed other than crude oil), the cause of the strange analyses would have been obvious immediately.

[Arsal]

Ping pong,

 

There is any possibilty that we can dump all the off gasses to naphtha to increase the Naphtha RVP and IBP?Is it possible and how? if possible then i assumed there is no need to install a off gasses(Refinery gasses) compressor..

[PingPong]

To answer that question requires detailed info about design and operation of the CDU.

 

And what is the destination of that preflash naphtha product? The naphtha hydrotreater? Or what?

[Zubair Exclaim]

Ping pong,

 

There is any possibilty that we can dump all the off gasses to naphtha to increase the Naphtha RVP and IBP?Is it possible and how? if possible then i assumed there is no need to install a off gasses(Refinery gasses) compressor..

No .. you cannot dump all gases .. there will always be non condensables in off gases with which you cant put Naphtha to storage

[Arsal]

Yes this naphtha to naphtha stabilizer and then to splitter and then H/naphtha to reformer and L/naphtha for isomeriztion.

[Arsal]

Yes this naphtha to naphtha stabilizer and then to splitter and then H/naphtha to reformer and L/naphtha for isomeriztion.

[Arsal]

Non condensable gases in crude is very little,normally is arab light.might be negligible.i am talking about C1 and C2

[PingPong]

It is possible to design a Preflash column such that there is total condensation (no offgas) in the Preflash reflux drum, but whether your unit can achieve that is not clear due to lack of detailed info about design and operation of your Preflash column.

[Arunkannan]

Hi,

         i have some doubt in the Natural gas plant (Methane).If is used in diesel Generator,

           

          1)In what ratio or composition the CH4 is Burns in Diesel Generator(DG) and how to find out the efficiency of DG.

 

          2)In What Pressure CH4 burns in DG and how to Regulator

 

 

Kindly Reply,

             

Regards    

 

ARUN.A

Arunkannans90@gmail.com