Experimental and Numerical Analysis of Coffee Husks Biomass Gasification in a Fluidized Bed Reactor

A two-dimensional computational model was developed in order to describe the biomass gasification process in a fluidized bed reactor using coffee husks within the commercial CFD code FLUENT. Both, gas phase and solid phase, were described using and eulerian-eulerian approach exchanging mass, energy and momentum. Results from the numerical model were later compared with experimental data. The study was conducted in a pilot thermal gasification plant, installed at Portalegre's Industrial Park based on the fluidized bed technology, with a processing capacity of 70 kg/h, and operating at around 800 °C. The gasification tests were performed continuously for several days in order to optimize the heat value and composition of produced syngas. The simulated syngas composition is in good agreement with the experimental ones although slight deviation was shown especially on CO and H2. This was mainly due to kinetics were taken from literature and, and there for may differ greatly from one source to another. Also devolatilization was assumed instantaneous and no particular attention was paid to char conversion.