Analytical solutions of sharp interface models with nth order kinetics.

• When a reaction occurs in a narrow layer of a porous particle, it is practical to simplify the calculation ofthe reaction rate by assuming global kinetic parameters based on the surface of the reaction front. Theassumption of such simplified situation allows formulation of a sharp interface model (SIM). Though,there are three difficulties for the application of a SIM in reactor simulations: (1) No analytical solutionis available for general SIM with nth order kinetics with respect to gas reactant. For reactor model simulation,with a variety of particles and operating conditions, a numerical model is still necessary to beapplied, leading to numerical difficulties and time consumption; (2) The global surface kinetic coefficientis not a priori known. The reason is that this coefficient depends not only on the intrinsic reactivity, butalso on physical factors such as the size and density of the solid, as well as operation conditions of thereactor like gas reactant concentration and temperature, varying during conversion of the particle; (3)The SIM is applicable when chemical reaction is rapid compared to intraparticle diffusion because in thissituation the reaction occurs within a narrow region compared to the size of the particle. However, noquantitative criteria has been developed to delimit the conditions for application of SIM. In the presentwork these questions are answered. Char conversion (combustion and gasification) is taken as reference,but most conclusions are applicable to isothermal non-catalytic gas–solid irreversible reactions with asingle gaseous reactant.b

Ämnesord

TEKNIK OCH TEKNOLOGIER  -- Maskinteknik -- Energiteknik (hsv//swe)

ENGINEERING AND TECHNOLOGY  -- Mechanical Engineering -- Energy Engineering (hsv//eng)

Nyckelord

modeling

char

Kinetics

gasification

combustion

gas solid reaction

Reactivity

Publikations- och innehållstyp

art (ämneskategori)

ref (ämneskategori)