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Calculation Routines Supporting the use of   Diesel Fuel Cold Flow Improvers

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Request file:  n-Paraffin.xlsm

Gas Chromatogram Trace for Wax Extracted by Cooling Diesel Fuel.  

The GC trace above identifies the carbon number range for n-paraffin wax separated as it crystallises out of a typical diesel fuel between the cloud point and CFPP target.  This fuel based on a North Sea feed, contained 19% n-paraffin and less than 1% of wax is formed from the higher carbon number n-paraffins.  The graph below compares the extracted wax with the n-paraffin range of the diesel and is typical of many European fuels blended to the EN-590 specification.

The amount of wax crystallising from fuels can be measured directly by Differential Scanning Calorimetry and can also be reliably correlated from the n-paraffin distribution.  This correlation  can be used in the production planning process to check if proposed blends are feasible for the Cold Flow specifications.  

The Excel calculation file, n-Paraffin.xlsm, is set-up with the correlation for wax crystallisation from the n-paraffin distribution.  GC analysis of diesel is not usually available in a refinery and a routine is added to make an approximation of the n-paraffin distribution from the distillation range and cloud point of a component.