Q & A > Question Details
To what extent can we blend fuel oil into gas oil without affecting the viscosity characteristics and maintaining the flash point specifications for gas oil or to keep them within the allowed limits?

Additional info:
First of all we don't have neither FCC, Hydrocracker nor VDU...we only run a conventional CDU
the objective here is to maximize the yield of gas oil...(we call it solar in our national markets) by extra stripping out from fuel oil or residue...the question is; Is there any equations or experimental methods to calculate or estimate the resulting viscosity and flash point of either the gas oil or fuel oil?
Thanks a lot.
 
Answers
16/05/2011 A: Sudhakara Babu Marpudi, Dangote Oil Refinery Company, m_sudhakarababu@yahoo.com
Gas oil is quality is governed by the 90% or 95% (T90 - T 95) recovery temperature (whatever is the applicable case for the refinery) as well as the cold properties viz., Pour point and cloud point. One blends the Fuel oil to the extent that both their recovery temperature and the cold properties are not violated.
08/04/2011 A: NS Murthy, Reliance Industries, ns.murthy@ril.com
From your query, it looks that you want to blend Fuel Oil (i.e. long residue or atm bottom in your case) into gas oil - Solar oil which I guess is diesel. The answer is pl do not do as metals and other CCR components in fuel oil will get added into diesel which is no desirable for high efficiency diesel automobiles. Further, the heavy boling distillates in fuel oil will generate substantial smoke while driving and end up in engine deposits too. The best way to lift the front end of long residue into diesel is to operate the Crude tower at the possible lowest pressure and higher furnace outlet temperature within possible lowest overflash.
25/01/2011 A: Jayaraj Jayam, Chennai Petroleum Corporation Limited, njayaraj@gmail.com
To clear every one's doubt about the question, please spell out clearly whether it is GO to fuel oil or fuel oil to GO. This will help to give more appropriate answer for the question.
24/01/2011 A: Ralph Ragsdale, Ragsdale Refining Courses, ralph.ragsdale@att.net
If you are referring to gas oil as conventional feed to the FCCU, many refiners increase the cut point of vacuum unit bottoms until the maximum coke burning capacity of the FCCU is reached.
If the gas oil is hydrocracker feed, increasing the End Point is not recommended due to the affect on run length.
If you mean “gasoil”, aka “diesel fuel”, the amount of resid shifted to the gasoil can be determined in the lab. Distill the front end of the resid under vacuum as done in a crude assay, collecting small cut samples. Make a series of blends of gasoil and these cuts until the blend no longer meets the gasoil specifications when tested.
If you mean dropping diesel fuel into FCCU feed, some refineries have had to do this when the diesel fuel market is depressed. If you do it incrementally by cut point, lab test blending will tell you when the diesel fuel will still meet specifications. Otherwise, dump full range diesel into FCCU feed until you reach a capacity limitation in the FCCU, or until your LP model tells you that it is a mistake to run that operation.