Define the user calculation

The User Calculation's value is entered as a standard mathematical formula. If the calculation depends on the values for other properties these must be defined as variables before they can be used in the formula definition. It is possible to add several different types of variable by clicking the icon:

• Add Existing Input from Case as a Symbol...: adds an existing input property to the Case as a variable for use in the formula.

• Add Existing Output from Case as a Symbol...: adds an existing output property from the Case as a variable for use in the formula.

• Add Recut Property as a Symbol...: adds a property recut from the feed assay as a variable for use in the formula.

• Add Model Parameter as a Symbol...: adds a model parameter defined in the Case as a variable for use in the formula.

• Add Utility as a Symbol...: adds a utility defined in the Case as a variable for use in the formula.

• Add Sub-Calculation as a Symbol: adds another of the calculations listed on this page as a sub-calculation for use in the formula. There must be at least another calculation defined for this option to be enabled.

After selecting the type of variable to use in the formula a dialog allows the exact property to be selected. Each variable must be given a Name which is used to refer to the variable in the formula definition.

Tip: You can insert in your formulae the calorific values for Standard Refinery Fuel and Non-Liquid Fuel Equivalent. These values are defined in the Details page ("Details" on page 81), together with the corresponding variable names (SRF and NLFE by default).