GENDBS Failed (Error Code = 36).

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This error message occurs in the OLI Chemistry Wizard when the mathematical model is not internally consistent. This applies to all versions of the OLI Chemistry Wizard not just for Aspen Plus which is shown in this example. The most common cause of that is a problem with REDOX chemistry.

This is the error message:


Look at this example component list


The problem occurs with these "EL" species. If you have these types of inflow components you will also need to enable solids since these are almost always a base metal. The only exception to this rule is mercury, HGEL, which has a solubility in water without redox being required. All other metal “EL” type species are solids and require redox.

When Redox Chemistry is enabled, we would see a panel similar to:


If you look at the sub-systems (such as platinum, PT) you will notice various oxidation states listed. In the case of Platinum, there is a PT(0) state. This is platinum in the elemental state and it is a solid phase. This means OLI will need some sort of equation that involves the solid. Specifically, we are looking for the equation to be written:


Where PTELPPT is the elemental platinum species. The problem occurs on the next panel:

In most cases, the user had turned off solid-phase consideration as in the following image:


This will cause the error code to be displayed. Here the solid phases has been turned off. This is also represented that the individual solid phase is grayed out. This means we will not create the above equilibrium expression for platinum. Mathematically speaking, we will have a species (PTELPPT) and no associated equation. We will have a mismatch in the number of unknown variables and the number of equations. The program flags this as the infamous error code = 36 (we really need better error codes.).

The workaround is straightforward. That is to turn on the solids in the above panel.


After you do this, the solid phases become live in the tree-view to the right (not grayed out).

The model will now generate properly.