Create a crude evaluation analytic

The Crude Evaluation analytic is used to determine the relative value of a crude when added to the refinery's base slate. Each crude being evaluated is known as a candidate crude, and is separately added to the refinery base blend. The objective function is determined in each case, thus measuring the value of each candidate crude.

You can also perform a sensitivity analysis by gradually changing conditions within the base case, to account for potential changes in refinery operations or market conditions. This helps reduce the chance that a small deviation from the plan would result in a very large loss in operating margin. For example, you could vary the price of gasoline over a range. If you had five gasoline pricing scenarios, five cases would be optimized for each candidate crude.

To create a Crude Evaluation analytic:

1. Select the case you wish to use as the basis for ranking crudes.

2. Click the Add Analytic > Crude Evaluation icon of the Cases group on the Home ribbon tab.

   

You can create several common crude evaluation workflows using the Crude Evaluation analytic:

• Base Loading: add crudes into a refinery base blend to review the effect of the crude to the economics.

• Balancing Crude: replace a crude in the refinery base blend with candidate crudes to review the relative effect of the crude versus the replaced crude.

• Incremental Blend: vary the amount of a crude in the refinery base blend to review the effect of the crude on the economics and changes in other crude purchases.

• Feedstock Reduction: remove a crude from the refinery base blend to review the effect on the economics and on other crude purchases.

• Price Sensitivity: change the price of particular products from the refinery to understand the sensitivity of crude purchase amount with respect to changing product prices.

Review stream values

The Stream Values page shows stream value analysis results for the crudes in the Crude Evaluation analytic.

Stream values show the change in objective function resulting from adding an extra free unit of a stream. See Stream Values for an explanation of the principle behind stream values and some examples.

Cells in the grid are shaded green or blue according to whether the stream value contribution to the objective function is positive or negative. The shading changes according to the absolute value of the contribution.

The different rows of the grid show you a breakdown of the effects of the extra unit of flow. The rows are divided into three main categories:

• Flow: The effect on the flow of material upstream and downstream (shown in the Direction column).

• Property: The effect on the stream properties. For example, an extra unit of a feedstock could result in a higher sulfur content, which would have a negative effect on the objective function.

• Other: The effect on other quantities not included in the two categories above.

The sum of all the contributions for each category is displayed at the bottom of the group of rows belonging to the category. A row at the bottom of the table shows the overall contribution from all categories for each crude.

Note: Stream values in the Crude Evaluation analytic are shown on the feed pipes to the process units. Since stream values are mode-specific, the feed pipe must also have modes matching these. This may require adding modes upstream of the process units for the feed assets. For example, if a process unit has a winter and a summer mode and a feed manifold, this feed manifold would also need a winter and a summer mode.

In order for stream values to be calculated, you must select Stream Values in the Result Retrieval Settings page of the Run Settings dialog box.

If this setting is not enabled, a warning appears at the top of the Stream Values page, with a link you can click to enable the setting.