Crude distillation unit optimization

**guga23** · 03-02-2010, 05:49 AM

Ive been working on a CDU simulation and now I wanna focus on doing some optimization cases, reduce cost, optimize the production,etc. For the moment Ive been playing with the "pump arounds" and all the "steams" that are added to the column/strippers, but I dont know on which exact case I should pay attention. Any ideas?

Thanks

best regards

**kermitel** · 03-02-2010, 02:17 PM

hi

depends by mode :design or rating/tray or structured packed
type of column A,U,R concerning Watkins
stripers column/ reboilers or steam str
quality specifiic,ASTM,TBB,MON RON for gasolineline/freeziing points for kero&diesel,densitity.....=REFINERY PROPERTIES
heat integration/pinch,exergy analysys
program simulation RECOMANDED:
proII/-shortcut &rigorous colum [with Sure Algoritm]
hysys rigorous vers 2.1 aspen V7
hysys/refsys PED +Aspen Plus models 2006, v7
petrosim-Distop+hysys rigorous
winsim design ii recc in PERRY
umist

**omli** · 03-07-2010, 02:16 PM

I think that you should start by heat efficiency
try diffrent feed temperature you w'll observe clearly the effect of feed temperature on the column product purity, uantities of products etc..
than you have to fixe a variable (an objectve) (which of the column products you want to perform )

I guess that the column you want to optimize exists, so don't try to change in mechanical data ( trys, diam, high...), play only by feed conditions, reflux rate, steam rate etc....

good luck

**yogi_process** · 03-27-2010, 11:57 AM

I love Crude columns...very first you have to check the heat balance in the unit...there are two ways of optimizing CDU...1st you fix the column specifications & use the heat available for the pump arounds ( This method is traditional...2nd you fix the heat requirement for the preheat trains & back calculate the heat flow in column (it is more rigorous & contemporary approach for column design). If you using the HYSYS simulator for this then keep in mind to split the feed in vapor & liqiud by checking the box available in HYSYS simulation. Also, the feed temperature to column & so exit temperature of fired heater should not exceed 690 deg F to avoid -----ing. Use double stage condeser configuration on column overhead as it gives more recovery of distillates. Keep in mind flashing of crude is at correct temp & pressure is most important in CDU..otherwise you have to rearrange the values of overflash.. I would recommend you to go through R. Watkins articles to know CDU optimization...also I have uploaded refinery material...follow this link...

[link Point to another website Only the registered members can access]
Please let me know once you optimized the scheme..its really exciting....

**Pericle** · 03-27-2010, 10:26 PM

I don't know your feed rate through unit, i don't know your type of crude that you use,i don't know your design of your column,heaters etc. so i will give you some general advices:

If you try to optimize the Crude Unit you should give a look to your preheat train, try to make a pinch analysis to see how can you optimize the feed temperature on the inlet to Crude Heaters (more hotter feed- less fuel consumption).

On the heaters (very important) try to establish the minimum O2 % in the burn gases, an excess air will indicate a waste of energy.In literature many engineers sad that good target for Oxygen content in the burn gases is 2 - 3 %.But i can tell you from my experience that this is not a good target for all the heaters.

On the column, try to optimize the steam consumption on the bottom and also on the strippers.Do tests run, and play with this steam.Establish a target that operators must rich for steam consumption.
Make a heat balance on your column and according with your results you should "play" with pump-around.
And another very important thing you should check the control valve and also the automatization on you column.Many problems are cause by sticky valves and/or bad tuning of the controls.

Regards