Targetted recutting

Dia

When using a flowsheet it is possible to use Targeted Recutting to try and meet particular property targets for one or more cuts. Normally when producing an assay table all assays are recut using the same cut points to produce equivalent assay data for a stable set of distillation unit conditions. However in some situations it may be necessary to vary the cut points used for different crude oils in order to meet specific property targets. For example, when producing diesel some refiners may vary the cut point in order to meet distillation or cold property specifications. Similarly for refineries producing bitumen it is common to vary the vacuum residue cut point to meet a viscosity or penetration requirement.

Using the target tab it is possible to set properties to target for different cut points. When producing a report for each selected assay the ECP of the cut will be varied to try and match the property. A minimum and maximum range of ECP must be set to define the range in which the ECP can vary.

To set up a property target:

• select the Enable property targeting check box to allow property targeting

• select the Active check box next to the cut point you wish to modify in order to target the required property

• enter the Min and Max value that the ECP can vary between in order to try and match the property

• click the Cut cell and select the actual cut for which the property value should be matched, for example, to match vacuum residue viscosity on a cut between vacuum residue and HVGO select the vacuum residue cut

• select the property to target in the Property cell

• select the Unit of the target value

• enter the Target value to try and match.

  

When a cut is marked for targeted recutting on the Cuts (Cuts) tab of the Planning Template Manager the cut points that can vary are marked with a icon.

When using the Show Preview feature of the Planning Template Manager the FVT of the preview assay will update as the property target is changed - this can be used to ensure the appropriate minimum and maximum values have been entered.