Calibration Helper - Migrating and Recalibrating Reactor Cases

Introduction

The Calibration Helper will automatically generate new calibrations for SIM reactors (that is, FCC-SIM, REF-SIM, DC-SIM, HCR-SIM, NHTR-SIM, DHTR-SIM, VGOHTR-SIM and RHDS-SIM) that are included in the Petro-SIM case, uploading those new calibrations to the case. The process looks for reactors in your case that contain embedded calibration data generated by the standalone SIM reactors in older versions of Petro-SIM. It then recalibrates those you select by:

• Loading the embedded data to a SIM Suite V3-style Excel reactor workbook
• Migrating the reactor to a Petro-SIM V4 version, creating a new Petro-SIM case in the background
• Calibrates the reactor in this new case
• Exports calibration factors from the case to an XML file
• Imports the new calibration to the reactor in your loaded case

The created files (V3 Reactor workbook, V4 Petro-SIM case and V4 Calibration xml file) are available to be opened and inspected after the process completes.

Please also see Migrating Petro-SIM Cases to V4.

Accessing the Calibration Helper

When you load a simulation case from Petro-SIM 2.x or 3.x and it contains refinery reactor models that require calibration, Petro-SIM will display this view after recalling the case:

If you do not see this view, go to the PFD button bar and click on the calibration drop down button, and select Calibration Summary:

Limitations

The helper can only recalibrate reactors where:

• The reactor contains embedded data
• The calibration case number is 1 or the embedded data contains only 1 calibration case

To explain what this means, let's look at how the embedded data gets created. The standard reactor calibration technique in older versions of Petro-SIM was to use the SIM standalone Excel interface to calibrate the reactor. You exported a calibration case from the Excel workbook to Petro-SIM, which copied the calibration factors and other data you selected to Petro-SIM. It recorded the Calibration Input sheet case number and also saved a copy of the calibration input data into the Petro-SIM reactor in the form of a SIM DAT file. This dat file was generated using the standard SIM case export function and would contain all the calibration and prediction cases in your workbook that had been marked for export. Because of the way the export process and the dat file work, the case number used in Excel may not always correspond to the same case position in the dat file, meaning version 4 cannot always rely on the dat file contents matching the recorded case position.

The helper will report where it cannot recalibrate because of these limitations. You may see one of the following two responses:

• Does Not Contain Calibration Data
• Multiple Calibration Cases in Excel - Calibration Not Attempted

Reformer Migration and Recalibration

In the reformer view, on the calibration tab, Autotune Setup 1 page, see if all the tuning targets are displayed in red. During migration from v 3.X, existing targets from the original case get migrated into the v4 Petro-SIM case as Blue inputs. A lack of blue targets indicates that neither this new v4 calibration nor possibly the original calibration file were tuned.

Reformer calibrations should always be tuned via autotune otherwise all subsequent predictions are invalid. Calibrating a Reformer is a multistep process that is necessary in order to have confidence in the step out predictions and responses of the model. Comparing a v3 case that may or may not have been tuned to a v4 case that has not be tuned is going to show differences and deviations simply due to the lack of completeness of the calibration. We recognize that calibration data can often be suspect or incomplete and in these cases, as educated guesses must be made in regards to the tuning. This is not our primary recommendation in this type of situation but is sometimes necessary.

Having said that migration/calibration of Reformer cases to v4 is different and even slightly more complex than other reactor models. This is due to the nature of the required inputs during calibration for the reformer. In v3 Ref-SIM, there are really two stages to calibration. The first is data validation and generating of calibration and tuning targets. This should be done in Ref-Bal. This is accomplished by entering all the feed and product data into the Ref-Bal input sheets. Ref-Bal then generates the C5+ yield targets (vol or weight yield RON, and RVP) as well as the autotuning targets. These can then be copied to the calibration input sheet for calibration. Thus, the calibration input sheet does not contain all of the necessary product information it only contains information regarding the yields. The Ref-Bal case data is not then associated to the corresponding calibration case. So in v4, we only have access to the calibration case data not the Ref-Bal data. This is the source for the difference in migration for Ref-SIM and the other reactor models. This leads to the “reduced calibration” option in v4. For cases migrated from v3 to v4, we can only migrate across the C5+ yield data and any autotuning targets in the calibration case data. In v4, users that migrate cases or start new cases can always switch to doing a full calibration, however in order to do so, the user must input all the feed and product data that would have been done via Ref-BAL. In v4, we have combined the Ref-Bal data validation step with the calibration step.

Why is there no flow in the other product meters after a migration?

During migration, the only product stream yield information available in the calibration case data is the C5+ yield (which is either in vol or wt). Thus, we can only calculate what the C5+ Reformate stream flowrate is since the other required information is not available. Thus, looking at the data rec utility will say that there is insufficient information to give balances.

What does the ‘data rec’ use to do the mass balance?

It automatically picks up feed and product meters, and uses a lot of information from other sources to determine what to use or ignore. The best bet is to double click on the mass imbalance result on the Run page and look at the data rec utility which will show you what values it is using the calculate said imbalance.

When would you need to take note of the mass imbalance warning?

For cases where all the feed and product data has been input by the user so that there is enough information for the data rec utility to calculate the balances, the user should take note of the warnings. In Ref-SIM, we do not recommend using data that has a raw imbalance greater than 1% for the mass and Carbon and 0.5% for the hydrogen. Calibration cases and subsequent predictions are only as good as the original calibration data. This is why it is imperative to use good data. We do not as a rule recommend doing material balance reconciliation blindly or even automatically. Often the data will need to be adjusted to close the material balance, but this should be done by a user with firsthand knowledge of where the uncertainties lie rather than an algorithm with no first hand experience with reformers or the unit being modeled.

Is it possible to run in a mode other than ‘reduced mode calibration’ where it does use the effluent flow rate data? What do you mean by ‘But you could have data in the effluent meters that are used to generate yield data’?

Yes it is possible, under the calibration setup, there is a check box that enables/disables doing the “reduced calibration” mode of calibration. In order to switch between the two modes, however, the user must then fill in the missing product data from the Ref-Bal portion otherwise the model will be unable to calculate this required yield information.

General Questions

I choose to calibrate, and a Calibration Helper view comes up but it freezes.

Recalibration may take several minutes at least. Be patient. This problem may manifest if multiple instances of Petro-SIM or Excel are running, or if either have crashed in the past. Use the task manager and terminate all Petro-SIM and Excel instances, and try again.

Helper reports the reactor does not contain calibration data.

While most reactors will have been calibrated using the SIM Excel standalones, the calibration factors may also be set up in other ways. For example, the original case author may have used copy and paste to copy factors from one model to another. You will have to find the original source information for the reactor and recalibrate based on that.

Helper reports Multiple Calibration Cases in Excel.

This happens when there is data exists but the helper cannot work out which data case to use as the basis for calibration. You will have to inspect the data and calibrate it yourself:

• Select the reactor in the helper view and click View Source. This will open a V3-style reactor workbook in Excel containing the available data.
• Use the SIM workbook button on the Petro-SIM ribbon bar to migrate the workbook to a V4 reactor workbook and case.
• Inspect the data and work out which original case was used. Then use the new workbook to calibrate that data case.
• Switch back to Petro-SIM and activate the Petro-SIM case you are migrating
• Now return to Excel and use the Petro-SIM ribbon bar Load button to load the calculated calibration factors to your case