The Peer review has evaluated this group as Average
Research Focus # 1: Detailed kinetics of pyrolysis and combustion processes Since the 1960-70, strong research efforts have been devoted to the mathematical modeling of chemical reactions with particular emphasis to the kinetic modeling of steam pyrolysis reactions to produce ethylene, starting from different hydrocarbon feeds (from ethane up to heavy gasoils). This activity is well recognized in the SPYRO™ program, a software code used by most of the ethylene producers. The natural extension of this activity was the analysis of pyrolysis reactions in the condensed phase. Thus, detailed kinetic models of visbreaking, thermal and delayed coking processes were successfully developed. The study of thermal degradation of plastic wastes was the natural fall-out of these activities in the area of the pyrolysis and upgrading of liquid and solid wastes. The research group extended this activity and know-how in the detailed kinetic modeling of complex reacting systems in the field of combustion processes. In this area, a number of national and international cooperations are active. As a result, a very large mechanistic scheme for the characterization of pyrolysis, partial oxidation and combustion of liquid and gaseous hydrocarbon mixtures was developed (TOT0512). Particular attention was also devoted to the environmental aspects and to pollutants formation (NOx, PAH and soot). A growing interest is now directed to the devolatilization and gasification of coals and biomasses with detailed prediction of primary products and intermediates. The research activity in the field of chemical reaction engineering and combustion processes is schematically divided into the following areas: Energy and transports Kinetic modeling and simulation of internal combustion engines and new engines (HCCI). Low temperature oxidation mechanisms: cool flames, autoignition and knocking. Evaporation and autoignition of fuel droplets in diesel engines. The kinetic characterization of liquid fuels and anti knocking additives is particularly difficult due to the complexity of the hydrocarbon fuel mixtures. At present, a particular attention is devoted to the definition of surrogate mixtures to mimic the combustion behaviour of real transportation fuels. Energy and environment Kinetic analysis of the combustion processes, properly coupled with a rigorous approach to fluid-dynamics, allows reliable predictions of pollutant formation from combustion processes (unburned hydrocarbons, aldehydes, poly-aromatic hydrocarbons, nitrogen oxides and soot particles). The design of combustion systems requires compliance with stringent emission limitations. This need increased the demand of reliable computational tools in order to optimize combustion systems in terms of both efficiency and reduction of pollutants. CFD codes are successfully applied to these problems, but their computational cost significantly increases with the number of chemical species. Even with the continuous increase of computer power and speed, it is still unfeasible to directly couple fluid-dynamics and detailed kinetics, especially when considering the typical dimensions of the computational grids used for practical applications. Pollutant species affect only marginally the main combustion process and consequently do not influence the overall temperature and flow field. This consideration allows post-processing the CFD results with a detailed kinetic mechanism. A newly-conceived numerical tool, a Kinetic Post-Processor (KPP), solves the overall system of mass balance equations with detailed kinetic schemes by assuming Dipartimento di Chimica, Materiali e Ingegneria Chimica “Giulio Natta” – Research Assessment Excercise 2003-2006 48 the temperature and flow fields as predicted by the CFD code. Special attention is devoted to the numerical methods: intensive use has been made of specifically conceived C++ libraries (BZZMATH). Consequently, the KPP is able to accurately predict also the formation of different pollutants, such as NOx, CO, PAH and soot with reasonable CPU times. Gasification and innovative energy processes Gasification and pyrolysis of coal and biomasses, as well as plastic wastes, are useful ways for gas fuel production. The detailed chemistry of thermal degradation and partial oxidation of these materials is very useful for the prediction of syngas and hydrogen production. Moreover, the chemistry and kinetics of hydrogen containing mixtures becomes relevant for describing ignition times, burning velocity, explosion and flammability limits. Research Focus # 2: Modeling, control and optimization. Risk Analysis of Industrial Processes. Moving from all the experiences in modeling and simulation, different research threads were undertaken. Steady and dynamic simulation of conventional and unconventional units and processes produced relevant theoretical and applied results (PRISMA: simulator of chemical plants; ORO: On-line Reconciliation and Optimization; DYCODIS: dynamics and control of distillation columns; WATERSIM: water treatment simulator; FC2000 and others). In the field of incineration processes and energy production, a large experience allowed the development of CYCOM program, very useful for design and simulation as well as for on-line applications. Also in this research line, most of the programs are based on specifically conceived robust and efficient numerical libraries BZZMATH. A research line on the modeling and simulation is always active: Modeling and simulation of conventional and unconventional process units This research line is addresses to the deep characterization of transport phenomena inside different units: fluid-dynamics, thermodynamics and kinetics of gas- liquid, liquid-liquid systems (e.g. urea reactor, solid-state polymerization reactor, soap production units, structured packing systems, liquid-liquid contactor, waste treatment units, micro-encapsulation and drug release, high energy mechano-chemical activation). The natural evolution of modeling, simulation and control is represented by the Risk Analysis and the Safety of industrial processes. The keywords of this research line are qualitative, quantitative and interdisciplinary multicriteria risk assessment, emergency preparedness and response, human and organizational factors engineering.
Guido Buzzi Ferraris