Tanks

From the Tanks page, you can configure the operating parameters and alert ranges for the tanks in your scheduling case. You can specify the Min and Max values outside which a Warning or an Error condition is triggered for a particular quantity. A warning or error message appears in the Diagnostics window and the cells corresponding to the quantity turn yellow or red in the Tabular pane.

Choose to show only a subset of tanks by creating an asset filter, and choosing it from the Filter list in the Assets group of the Home ribbon tab.

There are three views to select from the View list in the top right corner of the page. Each view shows a different set of parameters:

• Composition Alerts: In this view you can enter warning and error ranges for the amount of a particular traded material in a tank. Filter the traded materials shown in the table by clicking Traded Material Columns in the Home ribbon tab. This opens the Traded Material Columns dialog box.

  

  Select or clear a check box to show or hide the columns for a given traded material. Use the (Select All) entry at the top of the list to quickly show or hide all the traded materials shown in the list. Type in the text field at the top of the dialog box to reduce the list to entries with matching text.

  Column filtering is not preserved across sessions. All columns are shown by default when you open the Tanks page in a new session of Schedule.

• Inventory & Rate Alerts: In this view you can specify the following:

  • The Default values for the Feed Rate and the Draw Rate, that is, the rates at which material enters and leaves a tank.

  • Warning and error ranges for the feed rate, the draw rate and the Inventory, that is, the amount of material in a tank. These limits are used to control the scaling in tank inventory charts.

  • Whether the tank can act as a Running Gauge asset. A tank operating as running gauge can be filled and drawn from at the same time.

  • Whether the tank has Fixed Composition. A fixed composition tank maintains the same composition and properties throughout the schedule, irrespective of new material flowing in. The only way to change the tank composition is via overrides or baselines.

• Property Alerts: In this view you can enter warning and error ranges for the properties of the material in a tank.

Add, delete and rename tanks

You can add, delete and rename tanks in your Schedule case topology even if they are not in the original Plan topology.

To add a tank:

1. Go to the Tanks page.

2. Click Add Tank in the Assets group of the Home ribbon tab. The Add Tank dialog box opens.

3. Enter a unique name for the new tank.

4. Click Add. The new tank is added to the table.

5. Configure the new tank by editing its properties in the table, and setting connections in the Topology page.

To delete one or more tanks that have been added in Schedule:

6. In the Tanks page, select the tanks you want to delete. Selecting a cell in the corresponding table row is enough to select the tank.

7. Click Delete Tank in the Assets group of the Home ribbon tab. The selected tanks are deleted.

To rename a tank:

8. In the Tanks page, select the tank you want to rename. Selecting a cell in the corresponding table row is enough to select the tank.

9. Click Rename Tank in the Assets group of the Home ribbon tab. The Rename Tank dialog opens.

10. Enter the new name and click Rename.

You cannot delete or rename tanks that are part of the original Plan topology.

Tip: You can also add, delete and rename tanks and other asset types from the Topology page.

Tanks added in Schedule have an information icon next to their name, with the icon tooltip showing the tank name followed by (added in Schedule).

Buffer tanks

Some tanks in the flowsheet may be used for buffering flow to process units. When the flow to a downstream unit is too high, the excess material is stored in the tank. This material is then drawn from the tank when the feed to the unit drops below the unit maximum intake.

Any tank can be used for buffering. The tank should be marked as Running Gauge in the Inventory & Rate Alerts view of the Tanks page, since it will receive and give material at the same time. The downstream process unit should have an appropriate target set where the tank is identified as a possible source of material (see: Targeting in Simulation).

Tank services

Tanks can be assigned to services, which are ways of operating the tank at a particular time. Services are often associated with particular materials, such as a finished product grade, or an intermediate. Tanks may often handle several different types of material, which means they can have several services. However, a tank can only be in one service at a time.

The service is only a label and does not prevent incorrect material from being loaded into a tank. For example, a tank may be dedicated to naphtha service, however it is still possible to route and load kerosene into that tank.

All the tanks collectively assigned to a service make up a Material Pool.

You can see the service a tank is currently assigned to in the Tabular pane, by adding the appropriate column for the tank.

You assign services to tanks in the Tank Services page. To mark a tank as being able to have a particular service, select the check box in the intersection between the tank column and the service row. Note that, if a check box is not already selected, it appears only when a cell is selected, or when you hover the mouse pointer over the cell.

You can choose to show only a subset of tanks in the page by creating an asset filter, and choosing it from the Filter list in the Assets group of the Home ribbon tab.

Note: By default, services are added for each product grade from the plant, and each product tank is given the appropriate service.

To add a new service:

11. Click Add in the Manage group of the Home ribbon tab.

12. Enter a Name for the service, and choose an associated Type.

To remove a service:

13. Select the service to remove in the grid.

14. Click Delete in the Manage group of the Home ribbon tab.

Define custom tank statuses

You can add custom statuses to your tanks in addition to the default statuses (Filling, Drawing and Available). Define new statuses by clicking the Manage Tank Statuses button in the Manage group of the Home ribbon tab. In the Manage Tank Statuses dialog window you can add, remove and reorder custom tank statuses.

Once you have defined the new statuses, you can set how long each tank spends in each status by filling the Status (hours) column on the Tanks page.

A tank goes through the custom statuses in the order they have been defined, after the Filling and before the Available status, upon completing the filling activity. In the case shown by the previous figure, a tank goes through the Filling status until the filling activity is complete, then go through the Mixing, Settling and Available statuses.

The custom tank statuses are shown in the Tabular pane within each tank status column, and in the Tank Inspector within the new Statuses pane. They are also shown as separate blocks in the Gantt pane.

Custom tank statuses are reflected in the following locations of the scheduling environment:

• In single blend inspectors for product and pipeline blends, you can see the number of hours until the Next source tank status and until the next Available tank status. A tank may go through a number of custom statuses before reaching the Available status.

• In the Generate Liftings dialog you have a Time to Lifting and a Time to Available value. By default, the lifting begins only when the tank reaches the Available status, thus taking into account any custom statuses.

• When creating rules, you can use custom tank statuses in the Edit Target Filter dialog.

• In the Targeting tab of the Configuration Inspector for distillation and process units, you have the option to take into account the custom tank statuses, so that the unit will draw from a tank only when it reaches the Available status.

• Errors are issued when filling or drawing a tank in a custom status. This does not apply to running gauge tanks, and to activities created by rules and rate targeting.

Inspect tanks

The Tank Inspector shows information about the selected tanks, including the levels over the scheduling period and activities occurring at the tank. To open the Inspector, go to the Display page and click on the Inspectors button in the Home ribbon tab.

If you select multiple tanks in the underlying page (for example, the Tabular or Gantt pane) these are listed at the top of the Tank Inspector. Click on a tank to show its details in the Inspector.

The following elements appear in the Tank Inspector:

• Tank chart. Below the Name and Description of the tank, the Property drop-down menu allows you to select the quantities to display in the chart, together with any associated warning and error limits. Of particular interest are Inventory, showing the tank overall level, and Composition, showing the relative amount of each feedstock.
  Hover your mouse pointer on the chart to see a tooltip with date/time and data values for that point in the chart.

• Service. This table lists all the services the tank belongs to, together with their start and end dates and times.

• Alert configuration. This table shows the alerts configured for the selected tank, with their warning and error ranges. You can only review alert limits in the Tank Inspector. To set and edit alerts, go to the Tanks page.

• Transfers by period. This table lists the transfers of material to or from the tank for each period in the selection. A period corresponds to a row in the Tabular pane and depends on the granularity set in the Settings page.

• Transfers over the interval. This table lists transfers of material to or from the tank during the whole selected interval. If a transfer to an asset spans multiple periods, you will see multiple rows in the Transfers by period table, but a single row in the Transfers over the interval table.

The size, position and internal layout of the Inspector are preserved across sessions. These properties are preserved when you close and reopen the Inspector, or Schedule. You do not need to save your case explicitly.

The internal layout properties that are preserved include the following:

• The size and expanded/collapsed state of panes.

• The size and position of columns for advanced grids. The settings of legacy Grids are not supported.

The size and position of the Inspectors are preserved separately for each Display. You do not need to enter the Edit Mode of a Display for these settings to be preserved.

If you get a new version of a Display via the Synchronize pane, the local settings for the size and position of the Inspectors are overwritten.