Biomass solar fast pyrolysis with a biomimetic mini heliostat field and thermal receiver for nitrogen heating

Biofuels may significantly influence the world's transition from hydrocarbons to renewable energies. Pyrolysis uses thermal energy in an anaerobic ambiance to crack biomass and create biofuels (bio-oil and synthesis gas). This work reports a detailed computational study of a novel system to develop fast biomass pyrolysis with concentrated solar energy. A fluidized bed reactor was coupled to a solar thermal receiver to heat the inert fluid (nitrogen) using a biomimetic mini heliostat field which provides the required thermal energy. A detailed kinetic model for the pyrolysis of lignocellulosic biomass was solved simultaneously with a set of differential equations based on mass, momentum, and energy conservation principles. An Eulerian-Eulerian approach was considered with three phases. The computational model was compared with data reported in the literature for the fluidized bed reactor and heat transfer in the solar thermal receiver with good agreement. Concentrated solar fluxes on the receiver, nitrogen outlet temperatures, temperature contours inside the reactor, concentration contours of relevant gases, and global product percentages (Tar, Char, and Gas) are reported. The products reach an almost constant composition of Gas, Tar, and Char after 6 s of reaction, indicating the annual operational stability of the solar pyrolysis plant in terms of biofuel production.