Top 3 Refinery Octane Blending Mistakes | RefinerLink

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Top 3 Refinery Octane Blending Mistakes

By Optimization Specialist Robert

Mar 14, 2016

Common traps that refiners fall into when they try to reduce blend octane giveaway.


Similar to many other areas in refinery optimization, people can fool themselves into believing that operations are well when they are not.  In this article, I will explore the common mistakes that refineries make when trying to minimize gasoline octane giveaway.


Often times, refinery blenders are not engineers, but rather operators that have made their way up the ranks.  These folks are very intelligent people that do the best with the tools provided them.  However, they are often times not given all the proper tools or guidance.  Instead, they are just given stringent metrics to meet.


Minimizing octane giveaway is routinely one of the top 2 gasoline blending metrics that refineries focus on.  Depending on the location of the refinery and the complexity, this can either be a hard task to accommodate, or a very hard to task to accommodate.  This challenge leads many gasoline blenders to pursue different pathways to meet the objective. 


Most people believe that gasoline blenders are the ones who are responsible for octane giveaway.  WRONG!  If your refinery is currently operating under this guidance, then you are likely pissing money down the drain. 


Gasoline blenders are the ones who develop and execute blend plans from the blend components made available by the refinery.  They can no better control octane giveaway than a wide receiver controlling quarterback passing accuracy.  Gasoline blenders surely have the ability to make a blend worse, but they can only make a blend as good as the components provided.


So let’s cover some common mistakes that refineries make when trying to minimize octane giveaway.


1.  Setting a Constant Reformer Severity Target


Reformer severity is normally used to manage refinery hydrogen balances as well as refinery octane balances.  As hydrogen and octane balance are highly dynamic constraints that depend on multiple variables, setting a constant reformer severity target is normally a sub-optimal practice.


Refinery optimization planners and gasoline blenders should work together to understand their constraints. 


Is high reformer severity required all the time, or just

from time to time? 

Is high octane reformate required in all of the gasoline

blends, or just premium blends? 


Understanding these constraints can help determine how to set reformer severity.  Often times, batch operating reformer severity may be the right solution to meet gasoline pool requirements while maximizing refinery yields and catalyst utilization.



2.  Blending Low Octane Components to Reduce Giveaway


Using low octane blendstock (i.e. treated straight run naphtha) to reduce excess gasoline pool octane is equivalent to spraying Febreze in a Porta Potty.  You may cover the stink, but the rotten turd still exists. 


Before a blender uses high a volume of low octane blendstock, they should ask themselves:  Why do I have so much octane length in my blend pool?


If the answer is not hydrogen balance, then there’s a likely chance that improvements can be made.  Options include:


  • reducing reformer severity
  • batch operating reformer severity
  • reducing reformer feed rates
  • selling high octane components
  • or even just allowing the octane giveaway to remain

You may have made a double-take on the last bullet above.  Just allowing the octane giveaway to remain?  Yes, octane giveaway can make sense in markets where jet prices are higher than that of gasoline.  If the other options remain non-viable, blenders should avoid producing more naphtha at the expense of jet just to reduce octane giveaway. 



3.  Segregating the Wrong Blend Components in Tankage


Every refiner will say that they do not have enough tankage.  Every refinery blender will say this even louder.  However, it is not common for refiners to take a step back and ask themselves if they have existing tanks utilized in the proper service.


If gasoline blend components share common tankage, understand the drivers behind why the pairings were chosen.  A decade ago, these pairings may have made sense when blend specifications were not as complex, but do the pairings make sense today?  People often paired components based on octane ratings, but today other specifications such as benzene and sulfur need to be considered as well. 


For refineries that have dedicated rundown tanks for every blend component stream, they need not worry about this problem.  For refineries that combine multiple blend components into one tank, this may be an opportunity to improve refinery octane balances.   


While we are talking about tankage, tank size logistics may also play a factor in how to blend components are utilized.  Depending on component production rates or finished product lift schedules, changing tank services to manage logistic constraints can often times improve blend planning and execution. 


Engineers often spend too much time optimizing unit yields without understanding how poor logistics can negate all the front end efforts!



As with every single refinery constraint that we can focus on, minimizing gasoline blend octane giveaway relies on a combination of factors.  Refiners who fall into the trap of relying on their gasoline blender to manage performance are just plain foolish. 


Great performance relies on coordination between numerous planning, engineering, and operations resources, and organizations need to ensure that all functions are properly supported.  We all know that human beings will constantly endeavor to meet metrics. The real question is if the solutions to the metrics are the correct ones.


Next time when you review your refinery’s gasoline octane metrics, think twice before believing that you are satisfied with your results.

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  • M.j.sastry :   Kerosene supplied to. LAB plants for. C10 to. C14 parraffins,in this process four streams are formed, 1.lesss than. C-10 2.greater than. C-14 3.non paraffinic. C-10 to. C-14 4.the paraffinic- stream is taken for. LAB production The non parffinic stock has freezing point -70, since this stock has no parffins and rich in aromatics&napthenes. Octane no is high. This is to be used for gasoline blend

    Jun 11, 2014

  • Freddy Castro :   Excellent article

    Mar 20, 2016

  • Jeffrey Kelly :   An excellent article especially point #3 ... If you would like to learn more about how to *segregate* blendstocks including crude-oils, please see the following articles ... These articles will guide you through how to manage both the "logistics" and the "quality" details of capturing the benefits discussed in the blog.

    Mar 20, 2016

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