Diagnostics and alerts

The Last Run, Validation, Assay Cutting and Alerts windows show diagnostic messages and alerts about your case:

• The Last Run window shows messages about the last optimization or simulation run.

• The Validation window shows messages on issues affecting case components such as plant assets and calculations.

• The Assay Cutting window shows messages generated when the case assays are recut. This can happen when you optimize the case, when you enable validation on the flowsheet or when you manually recut the assays in the Assay Preview page.

• The Alert window shows violations of warning and error thresholds defined in the Constraints and Alerts page.

To open all four windows, click Diagnostics in the Views group of the Home ribbon tab. To open a specific window, click the arrow next to the Diagnostics button and choose the window you want to open from the list. You can dock these windows to the main planning environment window.

Note: No messages appear in the Validation diagnostics window if the Validation option on the Flowsheet page is disabled, even when optimizing the case (although validation messages still appear in the Last Run window).
To show messages in the Validation diagnostics window again, either click the Refresh diagnostics icon () in the window itself or enable the Validation option on the Flowsheet page.

You can organize the list of messages in several ways:

• Click the Errors, Warnings and Messages buttons to include or exclude messages of each type. The Alerts window does not have a Messages type.

• Click a column header to sort the messages according to the contents of the column. Click again to reverse the sorting order.

• Filter the messages by choosing a filter from the Filter drop-down list. Click the ellipsis button next to the list to edit or create a filter. Note that the Last Run pane includes the predefined Exclude Validation Messages filter. This filter hides all messages with Classification set to Case Translation or Case Construction.

• Choose which columns to display by selecting a view from the View drop-down list. Click the ellipsis button next to the list to edit or create a view.

Diagnostic messages are preserved across AVEVA Unified Supply Chain sessions. When you save your case, diagnostic messages are saved alongside optimization results.

You can export the list of messages via two icons in the toolbar:

• Click the Copy icon () to copy the contents of the window to the Clipboard, in tab-separated text format.

• Click the Export to Excel icon () to create an Excel spreadsheet with the list of messages.

The Validation window also has a Refresh icon () to refresh the list of diagnostic messages.

The numbers of validation, last run, assay cutting and alert messages are shown in the task bar of the planning environment.

The following are some examples of diagnostic messages:

Process unit non-operational

Process unit may not be operational for various reasons. Further information will be shown in the Diagnostics window or tooltip.

The unit process unit is not being supplied with the property property it requires to operate

If the feedback indicates that the unit is not being supplied with particular properties this means that the Material Type(s) associated with the unit feed(s) do not included the properties required by that unit's model.

For example, a reformer model would typically use properties such as density, aromatics content, sulfur content and so on as drivers to calculate the properties of the unit's products. In order to calculate the conversion of the input streams, all the input streams must carry the carry the properties required by the model, so the reformer input feed must have an associated density, aromatics content, sulfur content and so on. Without all this property data the model cannot calculate the unit's performance.

Properties are associated with streams by associating the stream with a particular Material Type.

Example: In the above example, the hydrotreating unit feed does not carry the properties required by the attached process unit model. Add the required properties to the feed heavy naphtha stream by associating the heavy naphtha with a gasoline material type, or by manually adding the properties in the Model Outputs grid.

Process Unit unit, Input Stream stream is not connected to an active flow

If a unit does not have all the required input feed streams to calculate, a message "Process Unit unit, Input Stream stream is not connected to an active flow" is shown. Connect a pipe to this unit which has the appropriate properties for this input.

The Process unit process unit has no upstream supply feeds or process units for the input input stream

One or more of the upstream units from the process unit is not completely supplied with feed, so the process unit is not receiving all of the property information it requires. For example, a unit may have a mixer upstream, and if the mixer is not correctly setup with all of its inputs defined, then it cannot pass all the required property information downstream to the unit.

Missing mode connectivity between Asset source unit and Asset destination unit

See Configuring Stream Routings.

Mode unit mode of Asset unit has no outputs

Where a unit has multiple modes, each of the modes must be connected to a downstream unit. To correct the error for the downstream unit that receives feed from the upstream asset, in the Mode Connectivity grid select the check box to show which upstream unit feeding column mode can feed which downstream unit row receiving mode.

Example: In the image above, CDU2 Feed has a mode 'Default CDU2 Feed' mode which is currently not connected to a downstream mode on the receiving CDU2 unit. To correct the problem, the check box at the intersection of the 'Default CDU2 Feed' column and 'Default Mode CDU2' row should be selected. This shows that when in mode 'Default CDU2 Feed' mode the feeder can pass material to the CDU in 'Default Mode CDU2' mode.

Process unit is missing a value for an operating parameter

Some process unit models require extra parameters in order to be evaluated. If all of the necessary parameters are not correctly configured the unit's performance cannot be calculated. A unit's operating parameters are set on the Operating Parameters tab of the Process Model page.

Example: A reformer model usually requires a target RON parameter in order to model the unit's performance. Without this parameter the model cannot be used to calculate the conversion of the input feed.

Process unit is missing a value for input property property

The process unit is not being supplied with values for all the properties required for its operation. Usually this means one or more of the streams feeding the unit is not carrying a value for the property. Add the required property value for the stream on the Process Models or Feedstocks pages.

Unit has insufficient availability

The availability of the unit needs to be increased. (Note you can only view availability in Simulation view.)

Unit availability cannot be negative

It is not possible to enter negative availability values. To correct the problem, enter the correct availability as a positive number between 0-100%. (Note you can only view availability in Simulation view.)

Example: In the figure above, you might replace the negative value of -50 with a positive value of 50.

Operating parameter parameter on unit has missing or invalid bounds

Process modes may have one or more operating parameters each of which is only valid over a range of values. If a value for the operating parameter which is outside this range is entered then it is not possible to simulate or optimize the unit. To correct the problem enter a fixed value for the operating parameter which is within the allowable range.

Input pipe pipe name is not used by any model

Where a pipe is connected to a process unit, this pipe must also be connected to at least one process model contained within that unit. This message shows that currently the named pipe does not correctly feed a unit. To correct the problem, associate the pipe with a process model on the Stream Associations page.

Example: In the image above, the unit feed pipe 'Kero - KHT' is currently unassigned. This should be mapped to the model SR Kerosene input port.

Model Connection model connection name of process model process model name on process unit process unit name in mode mode name is not mapped to a flowsheet pipe

Each process model has one or more outputs, and each of these outputs must be connected to a flowsheet pipe. This is true for each operational mode where the process model is used which are configured separately. To correct the problem, ensure that for each operational mode of a process unit the associated process model has all of its output connections connected to a flowsheet pipe.

Example: In the image above, the H2S model output connection is not connected to a flowsheet pipe. This should be assigned a connection on the Stream Associations page.

Reference density for name must be greater than zero

Reference densities are used to convert between weight and volume basis. The reference density is used in preference over any calculated value for a stream. Any entered reference density must be greater than zero.

Distillation tower unit output stream has a property override which takes another property as an input

It is possible to configure overrides for calculated property values in order to better match behavior found in actual plants. Overrides may be simple entered values, or complex calculations based on other stream properties.

Output streams from distillation units, such as CDUs, cannot use other stream property values as input for an override formula.

Distillation tower unit output stream has a property override which takes a property from another stream as an input

Example: In the image above, the override uses a variable called DECDOUT6, which takes Light Gas as an input. To fix this error, you should edit the override to use a different variable, or delete the override entirely. If it makes sense in your situation, you could alternatively route the variable input to the stream the override is on (in this case, that would mean routing the Light Gas into the Distillation tower).

Material has no active sales

Feed feed unit has no active purchases

The feed unit is not associated with any purchases; either a feedstock group has not been assigned (double-click the unit to assign groups) or the selected groups do not have active feedstocks.

Purchase name is missing a price

The named purchase does not have an entry in the Purchases page. Enter a price for the material.

Purchase name is missing an amount

When using the Simulation functionality of Plan all the purchases must have an amount. Enter the amount purchased on the relevant tab of the Purchases page.

Sale name is missing a price

The named product does not have an entry on the Products tab in the Sales page. Enter a price for the material.

Asset Name has minimum blend composition constraint of -X, which is less than the minimum allowed of 0%

Each individual blend component must have constraints in the range of 0-100%.

Asset Asset Name has maximum blend composition constraint of X proportion, which is greater than the maximum allowed value of 1 proportion.

Each individual blend component must have constraints in the range of 0-100%.

Asset Blender Name, Output Pipe Pipe Name is constrained to have a total maximum output composition proportion less than 1.0

Consider one blender with three outputs. If the maximum of each output is 10%, then the total is only 30%. You must change your outputs to make sure they sum to at least 100%.

Asset Blender Name, Output Pipe Pipe Name is constrained to have a total minimum output composition proportion greater than 1.0

You must change your outputs so they sum to 100% or less.

Optimization is infeasible

The optimization problem does not have a solution within the current constraints. Try enabling Infeasibility Breakers and run the optimization again to check which constraints have been violated.

Optimization solution required infeasibility breakers

Plan could find a solution to the optimization problem only by violating one or more constraints via Infeasibility Breakers.

Optimization not needed

Optimization was unnecessary as it was not required to calculate the results. This is usually because none of the blending pools require optimization to produce their products.

Recycle simulation converged in count iterations

Flowsheets may contain cycle pipes. A cycle pipe contains material that is produced by a unit, and also feeds that unit. That is, 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. For example, in the above flowsheet the reformer produces hydrogen, which is used to feed a hydrotreater, which feeds the reformer. This forms a circular flow within the flowsheet.

When a flowsheet contains a cycle pipe, Plan must perform a number of iterations to determine how the flow in the cycle pipe affects the performance of the process unit. The diagnostic message shows the number of iterations that were necessary to calculate the flow of the pipe.

Cycle pipe stream has flow flow rate and convergence delta delta

The diagnostic message shows the flow rate through the cycle pipe, and the delta for the pipe on the last iteration, that is, the difference in the cycle pipe flow between the iteration prior to the results converging and the iteration that resulted in convergence. For n iterations, this is the difference in flow between the n-1th and the nth iterations.

Recycle simulation failed to converged in count iterations

The cycle pipe could not be simulated because the flow rate delta did not converge within the allowed number of iterations.

Unit was not simulated as not all blend fractions were specified

In order for Plan to calculate the properties of a product from a blender, all of the inputs to the blender must be fully specified, and each stream must have a flow rate and the properties required by that blender. If each input does not have these properties, the blender cannot be simulated.

To correct the problem, the inputs to the blender should be assigned all of the properties required by the blender.

Unit was not simulated as upstream units could not be simulated

Simulation occurs downstream through the plant, from the inputs to the outputs. If a unit cannot be simulated, then any units downstream of this unit will also be unable to be simulated. To correct the warnings, ensure the upstream units have all the necessary configuration to be simulated.

Example: In the above example, the reformer is not supplied with a target RON and so cannot be simulated. As a result, any units downstream of this unit cannot be simulated, as they depend upon the performance of this model.

Unit was not simulated as not all operating parameters were specified

When simulating a model, it is necessary to supply fixed values for all operating parameters of each process unit. If these are not specified the simulation will fail. To correct the problem, enter the fixed value for the operating parameter.

Example: In the above example, the reformer cannot be simulated as the Target RON operating parameter has not been entered. The correct Target RON values should be typed in to allow the unit to be simulated.

Process unit unit in Mode operational mode could not be simulated as it has no process model

For each operational mode of a process unit, the mode must be connected to a single process model. To correct the problem ensure that on the Process Model page for a unit each Mode row in the grid is marked against a single process model column.

Example: In the above image, the 'Default Mode Coker' mode is not connected to a process model. A tick should be placed in the check box to connect this mode to the 'Coker' process model.

One or more components of the primary feed to Process Model process model name on Process Unit process unit name operational mode is a component of the primary feed of other Process Models on the same Process Unit

Where a process unit has multiple operating modes, and multiple process models, each of the components of the mode feed can only feed a single process model. To correct the problem, each unit model should be associated with only a single mode.

For example, in the above example the 'Alkylation (Propylene feed)' model is associated with both the operating modes of the alkylation unit. To correct the problem, the 'Alkylation (Propylene feed)' model should only be associated with the 'Default' operational mode. This would leave the 'Low Catalyst Activity' mode without process models (as the same would have to be done for the mixed butylene model). Therefore, it would be necessary to add two new process models (corresponding to low catalyst activity) and connect these to the 'Low Catalyst Activity' mode.

Sometimes, however, it may be desired to connect a single process model to more than one operational mode. In this situation, the individual components which make up the process model feed must be directed to a single process model. This is done by setting Stream Associations for each component in the pipe which feeds the unit.