Supplies

The Supplies page is renamed to Purchases if you do not have a valid Spiral Network license.

For more information about checking for installed licenses, see the Configure your Licenses topic. Contact AVEVA support (spiral.support@aveva.com) for information about obtaining new licenses.

Supplies are the materials which are available to the network over time. You must enter each of the different materials available to each supply node, along with the timespan for which they are available and the amount and price available. Each supply is independent, so it is possible to add two supplies of the same material with different pricing and availability, and these will be optimized separately.

For example, if there is a supply of 10 kbbl at 100 $/bbl, and another supply of 15 kbbl at 120 $/bbl, and if the value of the material is 102 $/bbl (based on the finished product value) then the first supply would be purchased, but the second supply would not. That is, the first supply would have a +2 $/bbl marginal value, and the second supply would have a -18 $/bbl marginal value.

If a supply can feed more than one destination, the supply to each destination can be configured separately, or as a single unit. If the supply is configured separately, separate transport links must exist for each supply route.

Example: Nemba crude could be imported to two refineries on the US Gulf Coast. It is possible to configure each plant separately where each refinery receives an independent supply of Nemba. In this situation each plant requires its own supply node, and each of these has a separate supply of Nemba. To constrain the total amount of Nemba purchased, it would be necessary to write a calculation that spanned the two supplies, or create a supply group.
Alternatively, a single supply node could be created representing, for example, an off-shore terminal, and the supply of Nemba would occur here. Two separate transport links would then be created between the supply node and each plant. The total supply constraint would be applied to the original supply of crude, whereas individual plant supplies could be constrained as calculations on the transport links.

Add a supply

Follow these steps to add a supply:

1. Do either of the following:

   • Click Add Supply in the Supplies group of the Home ribbon tab.

   • Right-click anywhere in the table and choose Add Supply from the context menu.

     A new row is added to the table.

2. Make sure that the check box in the Active column is selected if you want the supply to be active within the optimization.

3. Enter a Name for the supply. Double click in the cell and type the new name.

4. Choose the Node from which the material is being supplied.

5. Optionally, select a Market for the supply. By default, the market selected for the node also applies to the supply, but you can override it.

6. Choose the feedstock Supplied from the node.

7. Enter the Start and End dates and times of the supply. This is the time during which the supply is available at the entered price and with any supply constraints.

   Supply dates are not restricted to existing period boundaries. Where supplies cross period boundaries, the amounts will be pro-rated across the different periods (Optimization across and within Periods).

8. If you want to alter the pro-rata behavior of the supply, clear the check box in the Pro Rata column. This column is only visible if you select All from the View menu in the Grid group of the Home ribbon tab.

   If the pro-rata behavior is not enabled, the optimizer is free to alter the allocation of the supply to periods, subject to other constraints.

9. Enter the Price of the supplied material and choose the unit of measure.

10. Optionally, enter any Minimum, Maximum or Fixed constraints on the amount of supplied material, and choose the associated unit of measure.

11. Optionally, enter a Description for the supply.

More settings are available in columns not visible by default. See Customize the Grid below for how to manage columns.

• If you want the supply to belong to a group, choose it from the Group column. This column is visible in the All view, not in the Default one.

• Add the Reference Density and Reference Density UoM columns to the Pricing band to specify a reference density.

  The reference density is used to convert between weight and volume basis. When an import is priced in weight terms and a reference density is used, the weight-based price is converted to a volume basis using the reference density. The purchase then occurs in a volume basis. Only the price is converted using the reference density: any weight/volume conversions necessary for flow constraints use the actual assay density of the feedstock.

  When a price set is in use, the reference density as defined in the price set is used. When the price set is overridden or entered manually, the reference density as defined in the grid is used.

• Add the Threshold column to the MIP band to specify a threshold.

  Thresholds allow semi-continuous amounts to be declared for certain items.

  Thresholds can be activated when these are set with zero or fixed amounts. When an item has a threshold applied, the amount must then be either zero or at least the minimum amount. For example, you could define a threshold on the supply of the crude Agbami of 500 kbbl. The valid solution would be either zero or 500 kbbl or more of the crude. That is, it would be impossible to purchase 254 kbbl of the crude, but 503 kbbl would be feasible.

  Where a minimum or fixed value is active, this setting allows for either zero or the minimum/fixed value to be used.

After you optimize the case, you can see the Solution value for each supply, and the and the Marginal value for any constraints that were applied.

Note: Redefining model supplies
Even though the network may contain plant models, which already have supplies defined in them, these supplies can be redefined in the model.
For example, you may create a network model using the Corsicana plant model; this has a list of crude supplies including Agbami and Arab Heavy. These supplies can be added again with their availability to the network model. The values and materials in the original source plant model are not automatically used. Alternatively you can link directly to the plant Purchases table (Items incorporated from planning cases).

Tip: The grid supports sorting and grouping of items as explained in Advanced grids.

Supply traded materials

All feedstocks have an associated traded material. The traded material associated with a feedstock is used to determine if the material can flow through constrained transport links, and where in plant nodes the feedstock can be routed.

In a plant node, feedstocks are added to feedstock groups. A feedstock group registers the traded materials that can enter the flowsheet at that location. For example, you may have a crude feedstock group containing Arab Light, meaning that any material labeled Arab Light can enter at that location.

Materials which can be purchased are listed on the Supplies page according to their feedstock reference and traded material. As the Supplies table does not directly map to feedstock groups, traded materials are used instead to determine where supplies can flow.

Buying and selling a material without processing it

If you want to buy and sell a material without processing it (for example buy ethanol at one location, transport via your trucks and then sell it at a different location), both the supplied material and the sold grade must have the same traded material.

Supplies and transport links

All materials required by a plant must be available at that plant's supply nodes, and there must be a transport link between a plant and its supply node. Supplies are not limited to crude oil, so a plant may also require supplies of imports such as hydrogen and ethanol.

Where a plant node is included, supplies are routed to the feed units in the plant node according to the traded materials defined at that feed node. A routed supply can enter the plant at any feed unit with a matching traded material. If there are multiple feed units and they all contain the same traded material, then the material can enter at any of those units.

Edit linked supplies and supply groups

When the Import options are active, supplies are automatically created based on the plant-level purchases. Edits in the planning environment are reflected in the Network environment, and vice versa.

This also applies to linked purchase groups, which appear in the Supply Groups tab.

Other tasks

The following are additional tasks you can carry out from the tabs of the Supplies page. Some of the ribbon groups described in the following sections are not available from all tabs.

Lock solutions

Solution values can be locked during subsequent runs. This means that a solution value will not change in any subsequent run, even if other input to the run is changed.

Example: The flow of naphtha from a crude could be locked, and in subsequent runs it would not be able to change. Therefore, if a fixed swing cut point was changed and the model re-run, the crude blend would have to change in order to match the fixed flow rate.

Locking a solution value acts in a similar way to fixing the value. The advantage over fixing a value is that the lock can be clearly seen in the user interface, so it is simpler to distinguish true fixed values from those which are temporarily locked.

To lock one or more solution values, select the corresponding rows in the table and do either of the following:

• Click Lock Solution in the Behaviour group of the Home ribbon tab.

• Right-click on the table and choose Locking > Lock from the context menu.

To unlock one or more solution values, select them and either click Unlock Solution in the ribbon or choose Locking > Unlock from the context menu.

Show differences with the master case

Whenever a value in the row is different from the value in the parent case within the model, the unnamed column next to the Active column shows a double arrow icon () . Note that this column may not be present in all views.

The Deltas group of the Home ribbon tab lets you further manage these differences:

• Click the Show button to display a blue triangle icon in the top right corner of every cell whose value overrides the value in the parent case. This allows you to pinpoint the specific cells with overridden values, rather than whole rows.

  • A dark blue triangle means that the value is different from the parent case value.

  • A light blue triangle means that the value is the same as in the parent case, but has been entered manually, so it is still treated as an override. Future changes in the parent case value will not be reflected in the subcase value.

    

• Click Restore to change the values of the selected cells back to those of the parent case. You can also right click and choose Restore from the context menu.

  Tip: To show all the differences between cases within a model, see Compare Cases.
  To merge differences across cases, see Update Cases.

Customize the grid

Customize the grid from the Grid group of the Home ribbon tab:

• Click Find to show or hide a text field at the top of the grid to filter the grid contents. Type in the text field to show only the rows with text matching what you have typed. The matching text is highlighted in the grid. See Filters for more details.

• Click Columns to open a small dialog windows where you can drag column headers to remove columns from the grid. You can then drag the headers back to the grid to restore the columns. See Add and Remove Columns in Manage Columns for more details.

• Choose a View from the list, or click the cogwheel icon to remove a view or save any changes. See Views for more details.

Show per-period information

Click the Periods button in the Periods group of the Home ribbon tab to expands each row of the grid to show per-period optimization results.