An important difference between chars from biomass and from fossil fuels (e.g. coal) is their reactivity.
Specifically, in the case of biomass it was found that char reactivity increases with the conversion degree, while that
of char from coal decreases [16]. Therefore the char reactivity is a key aspect of the gasification process. It
significantly depends on parameters, such as: char porosity, number of active sites and biomass particle size. In order
to take into account this aspect, some authors introduce in their kinetic equations pre-exponential factors corrected
by a constant. This constant is generally known as char reactivity factor (CRF) [17, 18].
In the model presented in this work, the CRF coefficient was considered a parameter and, keeping fixed operating
conditions such as: gasifying agent, temperature, and pressure, its effect on the quality of the produced gas and
energy balance of the reactor was studied. A summary of the obtained results is presented in Table 2.
The simulated data showed that by increasing the CRF coefficient, a better gas composition is obtained, since it
becomes richer in H2 and CO. However it has to be considered that as the CRF value increases, the temperature
within the reactor drops very rapidly due to the fact that the gas undergoes endothermic reactions in the downflowing
chamber. Therefore, if the same flow conditions are kept, the combustion reactions in the up-flowing
chamber becomes critical for the energy balance of the entire reaction. In order to make autothermal the entire