ting the heavy and the light petroleum. Inside the towers the liquids and vapors are separated into fractions according to weight and boiling point. The lightest fractions are what we all know as “liquid petroleum gas” or LPG’s. Medium weight liquids are turned into diesel fuel and kerosene. The tar like fraction, or “residuum” comes from the bottom of the barrel. Most of this is what is used to make plastics and other products.The most complicated step in the refinement of petroleum occurs in the “conversion” stage. The most widely used method of conversion is call “cracking” or “Hydrocracking.” Once again, this is using heat and pressure to crack heavy hydrocarbon molecules into lighter ones. This process is what defines whether the LPG’s become gas, racing fuel, or jet fuel. The process occurs in the large bullet shape furnaces that you may have seen at refineries.The final step in refinement is adding all of the treatments that are required by the many government bureaucracies that were previously mentioned. Among the many variables that determine the blend are octane levels, vapor pressure ratings, and even MTBE’s. This is the production step that differentiates products throughout the industry. HousekeepingThe common denominator of processing hazardous materials brings industries, and even competitors together. According to Paul Thorvaldson (Operations Manager of the Tosco Santa Maria refinery), the “keep it clean and dry” policies now in effect throughout Tosco were adopted from the example set by Chevron. In 1997 it was discovered that all North Western refineries had been having problems with rust in their fuel. After researching the problem, analysts found that water was getting into the holding tanks and creating the rust.It happens that this was a shared problem with all refineries, and it was a quality issue that needed ...
