Design and performance analysis of a solar dual fluidized bed gasifier

The potential to conduct allothermal steam-gasification of biomass using a dual fluidized bed gasifier (DFBG) assisted by solar energy has already been conceptually proposed. In this paper the design and operation of a solar DFBG (SDFBG) device to deal with this concept is assessed by modeling, considering thermodynamic, kinetic and fluid-dynamic issues. The challenges identified in previous works, as well as the modifications required in the current state-of-the-art technologies of (no-solar) DFBG for implementing the new solution using heated particles as heat carriers, are worked out. Two SDFBGs, considering different arrangements for integrating the solids carrying the solar energy into the system, are designed. The operation of both under different solar-external heat loads, from autothermal operation (no external heat) to 3 MJ k(gbio,daf)(-1) of external heat, is assessed and compared. This work shows how the technology can be implemented and scaled up.