HVGO Cutpoint/Yield improvement
HVGO Cutpoint/Yield improvement
(OP)
I was wondering what other refineries do to optimize their HVGO cutpoint/yield. In my refinery the strategy is to always maximize the heater outlet temperature. I have noticed, however, that the actual yield does not necesarily increase with the higher duty/temp and that sometimes maximizing the heater increases the tower vacuum (3-5mmHG). Can someone tell me how they maximize their HVGO yield? I think that I may be hurting myself by always maximizing the heater outlet Temp/duty.





RE: HVGO Cutpoint/Yield improvement
RE: HVGO Cutpoint/Yield improvement
In my refinery we try to improve the vacuum in the column, you will get more evaporatoin and deeper cut, improving the vaccum however is a design issue, in your case reducing the noncondensable gases and some operational adjustments may improve the cut.
You did not mension what temp you are using,current cut point and column vacuum, one of them may cause the problem.
RE: HVGO Cutpoint/Yield improvement
Is the overhead condensers performing? Are there any signs of fouling?
From the design point of view, packed tower generally gives a lower delta P drop. Is it a packed tower you are using?
RE: HVGO Cutpoint/Yield improvement
RE: HVGO Cutpoint/Yield improvement
Our unit is not a dry unit ( we use steam ),but the vacuum we have is 25-27 inHg60F ( if my memory serves me right; with the units that is ). We use a three stage steam ejector system.
IF you can increase the quinch temp or circulation rate there is a chance to improve the vacuum by lowering the cracking rate.
On the vacuum system check if you are in optimal conditions, Ejector systems are constant mass flow not vol. so if you have more overhead products or underperforming washing sections you may overload the system.Do a mass balance on the top section and check the ejector curves.
RE: HVGO Cutpoint/Yield improvement
Cutting deeper into the resid mean the marginal bbl of HVGO recovered is much poorer quality than the average quality of the HVGO stream.
The marginal value of this stream needs to be compared with alternative modes of operation of down stream processing units e.g. is it better to increase FCC conversion rather than increasing feed rate using a poor quality feed.
This is a fairly complicated optimization best done by a refinery-wide modelling tool. As well as changing coil outlet temp and quench rate, pumparound and wash oil rates also affect HVGO yield and quality.
Note that cutting too deep into the resid in a unit that is not designed for it can lead to excessive coking in the column and furnace.
If it "optimum" to maximize HVGO yield then performing a few test runs on the unit a various conditions is usually he best way to confirm the best process conditions.
RE: HVGO Cutpoint/Yield improvement
RE: HVGO Cutpoint/Yield improvement