I'll leave it to Amit to answer about the support for the refinery blending parameters.
I have no experience of using the TIMES blending constraints myself, and I have not been able to figure out how
exactly
they have been designed to work.
Nonetheless, I think one could relatively easily formulate similar constraints without using the special attributes. For example, one can easily make a constraint saying that the carbon content of the refinery input feedstock fuels must be greater than or equal to the carbon content of the refined oil products. You only need to define a positive carbon content factor (e.g. REFC for refinery carbon) for all the input flows, and a negative carbon content factor for the outputs, and define the carbon commodity as an auxiliary output flow. To make sure that the auxiliary output flow is not reduced (and thus has a non-negative flow variable), one should additionally put some emission factor for the net carbon flow, e.g. UPNCO2. Then you have the overall carbon balance defined.
I guess a total octane balance constraint and a total sulphur content balance could be formulated in the same way. However, if one would like to formulate these balances individually for each product, then
apparently
a separate "blending process" would have to be introduced for each of the products. Consequently, unless I am missing something, I don't think the special blending constraints are really necessary. But perhaps they can be convenient, if only one knows how they are supposed to work?
