The question is unclear... lumped kinetic can be anything. LHHW kinetic can be considered lumped since you reduce a detailed kinetic scheme accounting for adsorbed species and reaction intermediates to a simple expression thanks to RDS assumptions. The resulting kinetic is function of only reactants and products concentrations and not of adsorbent/intermediates. The lumping can be done also for reactions where you have thousands of thousands of radical reactions and products in the resulting species, for instance, pyrolysis and gasification. However, if you have defined the species, I do not see problem to implement lumped kinetic in Aspen. I did for pyrolysis in a different software, it is not straightforward but you can succeed. It depends if you have clearly defined species and kinetics. Without this info, you cannot proceed.

Hi Filippo (Filippo Bisotti),

Many thanks for your answer.

In the reactor that I would like to simulate there are different intermediates due to the cracking, or isomerization and so on. We basically know the feedstock as well as the product stream composition. Therefore, we have no info of the intermediate steps actually and as results, we don't have the kinetics of those reactions. I am also naïve in this direction, and don't know what information I need (from the experiment) in order to proceed with the Lumped Kinetic Model in Aspen HYSYS. I would be thankful if you share your opinion on that as well as any documents or instruction to learn how to approach this problem.

Best regards,

Sadra

It is the same problem of pyrolysis and gasification of biomass. You should start with the complex kinetic scheme and then lumping. You do not have to start from scratch. Just have a look at the existing literature. Depending on feedstock (oil, bio-oil, plastics), you can find lumped kinetic models. My suggestion is to avoid complex systems where radicals are involved since the existing commercial process simulators are not suitable for accounting for these kinds of species. If you have to include intermediates (and they are radicals), you may think about a custom model to be plugged into your flowsheet.

Thanks.

If have understood properly, I need to first focus on the primary reactions and try to find the kinetics of them from the experiment, without considering the intermediates. I also should not include radicals and try to start lumping with the help of the available methods in the literature. Is this what I need to generally do?

I don't know what your system is and the most suitable option. Have a look to what the literature can offer

- Article Lumped Kinetic Modeling of Polypropylene and Polyethylene Co...

Article Lumped kinetic modelling of polyolefin pyrolysis: A non-isot...

Many thanks for your help. Filippo Bisotti