Thieving Fuel Companies

[shygye]

It is the octane rating. Basically a higher octane fuel ignites at a higher temperature. That is why a high octane engine will "knock" if you use a low octane fuel.

 

Some tankers have separate compartments to hold the different gasoline grades. CA gets screwed because the State requires a special fuel blend to reduce pollution that is only produced at a few refineries.

[pasathai1]

I think the price of fuel is based on a ratio of a nations use of gas.

 

better mileage cars, higher prices per "serving", gas companies still make the same profit, selling less gas

[Mekong]

I have been told by people who know about cars, gas and consumer shit, that the premium is the same gas as the regular, just oxygenated at the pump differently, or some such stuff...makes sense, as only one truck carrying 1 type of gas ever shoes up at the station...

 

OH what you have been told about is a misconception, Oxygenate blending is carried out at the refineries.

 

Oxygenate Blending adds oxygen to the fuel in oxygen-bearing compounds such as MTBE, ethanol and ETBE, and so reduces the amount of carbon monoxide and unburned fuel in the exhaust gas, thus reducing smog. In many areas throughout the US oxygenate blending is mandatory. For example, in Southern California, fuel must contain 2% oxygen by weight. The resulting fuel is often known as reformulated gasoline (RFG) or oxygenated gasoline. The federal requirement that RFG contain oxygen was dropped in 2006.

 

It is the octane rating. Basically a higher octane fuel ignites at a higher temperature. That is why a high octane engine will "knock" if you use a low octane fuel.

 

Knocking (or pinking) is caused by pre-ignition, pre-ignition is not related to the Octane Rating but the compression ratio of the engine, from simple combined gas laws the higher the pressure the higher the temperature. Once the Fuel / Air Mix gets hotter than its auto-ignition point it will explode. Adding lead to the Mogas blend increased the Auto-Ignition point. It is using unleaded fuel in a high compression engine that will cause knocking.

 

As for the Research Octane Number (RON), it is just a metric of energy per unit.

 

Regular Gas RON 91 31.6 MJ/L

Premium Gas RON 95 32.84 MJ/L

 

Octane Number is determined by what components and in what ratios are blended to produce Mogas. Whilst most people know that Petrol / Gasoline / Mogas (Call it what you want) is refined from Crude Oil what some don't realise is that it is not a specific product but a mixture of different streams. Refining processes that produce components of Mogas include

 

* Reformate, produced in a catalytic reformer with a high octane rating and high aromatic content, and very low olefins (alkenes).

* Cat Cracked Gasoline or Cat Cracked Naphtha, produced from a catalytic cracker, with a moderate octane rating, high olefins (alkene) content, and moderate aromatics level.

* Hydrocrackate (Heavy, Mid, and Light), produced from a hydrocracker, with medium to low octane rating and moderate aromatic levels.

* Virgin or Straight-run Naphtha, directly from crude oil with low octane rating, low aromatics (depending on the crude oil), some naphthenes (cycloalkanes) and no olefins (alkenes).

* Alkylate, produced in an alkylation unit, with a high octane rating and which is pure paraffin (alkane), mainly branched chains.

* Isomerate which is obtained by isomerising the pentane and hexane in light virgin naphthas to yield their higher ocatane isomers.

 

Overall Mogas is predominantly a mixture of paraffins, naphthenes, aromatics and olefins plus additives (MTBE, ETBE and ethanol etc), but the streams blended varies from Refinery to Refinery depending on the complexity and also what Crude is being refined.

 

I for one would never complain about the cost of fuel, after all it does pay my salary.

 

 

 

 

[shygye]

So I was right!