Manage simulation settings

The Simulation Settings dialog window contains various settings and options regarding different aspects of the schedule simulation. Each setting is described in the following sections.

To open the Simulation Settings window, click Settings in the Simulation group of the Home ribbon tab.

Result stream interval

This setting controls how often results in the user interface are updated while a simulation is running. Select the Result Stream Interval check box and specify an interval, in seconds, between updates to the user interface. For example, if you enter a value of 5, while the schedule simulation is running the numbers in the user interface will update every five seconds.

Assay recutting

In the Configuration Inspector you can override the original parameters of distillation units. Here you can choose how assays are recut to the new distillation parameters:

• Swing Cuts: Use swing cuts to interpolate new values from the Assay Preview table of the parent planning case. Faster but less accurate.

• Assay: Use the internal Assay engine for recutting. Slower but more accurate.

  Note: If you enter explicit overrides for property values, for instance in the Overrides pane or in the Import Inspector, the Assay engine will be used for recutting, even if you have selected the Swing Cuts option. This is because the overrides change the target feedstock, making the existing swing cuts obsolete.

Calculate recycles

Flowsheets may contain cycle pipes. A cycle pipe contains material that is produced by a unit, and also feeds that unit. In other words, the pipe carries a circular flow of material to and from a unit. The cycle pipe may not be directly connected to the producing unit but may be upstream of it.

When a flowsheet contains a cycle pipe, Schedule must perform a number of iterations in order to work out how the flow in the cycle pipe affects the performance of the process unit.

The available options to configure recycles are described in the table below:

Calculate rate target

This set of options control the use of iterative calculations for asset targeting. Each options is described in the following table.

If iterative calculations are enabled, Schedule will attempt to adjust targeted unit feed rates according to the upstream controllable assets (see: Base Delta Targeting). Target flow are defined as the average flow over the timespan defined by the iterative calculation interval. If an asset has a targeted flow rate during this interval, the control assets will be adjusted to attempt to meet the target. As such, activities are automatically generated on the targeted asset, as well as the upstream assets being controlled via targeting.

Calculate alerts

Clear the Calculate Alerts check box to deactivate the calculation of warnings and errors to be shown in places such as the Tabular view and the Gantt chart. Note that this is not the same as deactivating the Alerts button in the Show group of the Home ribbon tab:

• By deactivating the button in the Show ribbon group, the alerts will not be shown, but they will still be calculated.

• By clearing the check box in the Simulation Settings window, the alerts will not be calculated. Therefore they will not appear even if the Alerts button in the Show ribbon group is activated.

Aggregate material pools

In the Charts pane you can display graphs showing the aggregate properties of all tanks sharing the same service.

Example: If several tanks contain Naphtha, you may have defined a Naphtha service. You would then be able to chart aggregate values for this service by choosing Naphtha from the Material Pools group in the Charts View Manager.

If you clear this check box, aggregate values for material pools will not be calculated. Therefore material pools charts will not show any meaningful information.

Gauge frequency calculations

As material is added to and drawn from tanks, the properties and composition of tank contents must be recalculated regularly. This value is the interval in hours between these recalculations.

Tank heel significance

A tank heel is the amount of material left in a tank at a given point in time. As a tank is emptied and refilled, small quantities of previous components will remain. A tank component will be ignored by Schedule if its amount, as a percentage of the tank inventory, is lower than the value specified in this text box.

Note that the value you specify applies to each component separately. Any component present in smaller amounts than the Tank Heel Significance value will be ignored, even if the overall tank inventory is higher than the tank heel.

Warning: AVEVA recommends not to use zero as the normal setting of the Tank Heel Significance value. Doing so means that any residual material left in a tank will be included in future simulations, no matter how small its amount. This will eventually lead to a degradation in performance and large increase in model size, without improving the accuracy of the simulation.
The default value for the Tank Heel Significance parameter is 0.5%. A warning is displayed if you set it to zero.

Generate convergence diagnostics

Select the Generate Convergence Diagnostics check box to generate additional diagnostic messages on the convergence of iterative calculations for rate targeting. The messages are labeled as Target Loop and show information such as the scheduling period over which the targeting was done and how long it took to converge.

The number of diagnostic messages generated depends on the Interval (hours) setting in the Calculation options section of the dialog window. Shorter intervals mean more periods and therefore more messages.

Note that, if the rate targeting fails, a diagnostic message is generated anyway, regardless of whether the Generate Convergence Diagnostics setting is enabled.

Import discharge uses pipeline batches

To explain what this settings does, imagine you have material discharging into a pipeline which in turn leads to three tanks, each containing a different feedstock.

Suppose you have a cargo arriving with three compartments containing Arab Light, Bonny Light and Agbami. These must be routed to the correct tanks.

If this setting is enabled, Schedule takes care of routing each pipeline batch to the correct tank, including any batches already in the pipeline before the cargo is discharged. In the Import Inspector, you just have to specify the Arab Light tank as destination for your Arab Light compartment, and similarly for the other compartments.

If this setting is disabled, you have to manually take care of the routing of material to the correct tank. In this case you must choose the destination tank based on what is in the pipeline, rather than what you are discharging at any given moment. For example, suppose that a 50 kbbl batch of Agbami is already in the pipeline, and you discharge 100 kbbl of Arab Light. You have to choose the Agbami tank as destination and discharge 50 kbbl of Arab Light, so that the whole Agbami batch is pushed into the correct tank. Then you can switch destination to the Arab Light tank until all the Arab Light has been pushed out of the pipeline, and so on.

AVEVA recommends that you leave this setting enabled unless your workflow requires otherwise.

Warning: If you disable this setting and change the destination of an import discharge, the destination does not appear correctly in the Import Inspector.
This is a known issue that occurs only when the Import Discharge uses Pipeline Batches setting is changed. While the Import Inspector still shows the old destination, the simulation correctly uses the updated one.
As a workaround to correct this issue, close and reopen the scheduling environment after changing the setting.