Emissions from biomass and coal combustion

 

Abstract

simplified kinetics solidIn the latest decades, the numerical prediction of such pollutants as nitrogen oxides (NOx) or Polycyclic Aromatic Hydrocarbons (PAH) has been gaining major importance because of the limitations imposed by legislation. This is even truer when the energy source is different from the traditional ones, mainly based on liquid or gas fossil fuels. As an instance, the combustion of biomass and coal can be very problematic in this sense because of their composition (oxygenated and/or sulphureted compounds). The prediction of emissions with the required accuracy (often of the order of ppm or less) requires the use of a detailed kinetic mechanism, but it cannot be directly coupled to CFD models for computational reasons. A possible solution is based on adopting kinetic post-processing techniques: since NOx and other pollutants affect only marginally the combustion process, a partial decoupling between chemistry and fluid dynamics is possible: the CFD results (obtained with a simplified kinetic scheme) are post-processed by using a large, detailed kinetic scheme, which is able to accurately predict the formation of the involved compounds. This approach has already been implemented into a software, named KPPSMOKE, able to exploit the parallel structure of modern clusters and supercomputers: in this way, even very large CFD models (like those representing full-scale, industrial devices) can be post-processed, and their design can then be optimized in order to control the concerned emissions before their physical manufacturing. Therefore, the application of this tool to burners fed different energy fuels is the next step towards the validation of the effectiveness of this approach.

 

Details

Duration: 10-12 months

Experimental activities: no

Skills: transport phenomena, fundamentals of combustion, fundamentals of chemical kinetics

People involved: Tiziano Faravelli, Alessio Frassoldati

Contacts: Tiziano Faravelli