Solar gasification of carbonaceous waste feedstocks in a packed‐bed reactor—Dynamic modeling and experimental validation

Abstract

Thermochemical gasification of carbonaceous waste feedstocks (specifically: scrap tire powder, industrial sludge, and sewage sludge) for high‐quality syngas production is numerically modeled and experimentally validated using concentrated solar process heat. The solar reactor consists of two cavities separated by a radiant emitter, with the upper one serving as the solar radiative absorber and the lower one containing the reacting packed bed. The reactor is modeled by considering combined heat transfer coupled to the reaction kinetics, driven by the applied solar flux at the reactor's aperture. Model validation is accomplished in terms of converted mass, reactor temperatures, efficiency, and solar upgrade based on experiments with an 8‐kW reactor subjected to solar fluxes up to 2560 suns and packed bed temperatures up to 1490 K. The transient operation of a 200‐kW pilot‐scale reactor for gasifying industrial sludge is simulated for a solar day, yielding a maximum solar‐to‐fuel energy conversion efficiency of 89%. © 2011 American Institute of Chemical Engineers AIChE J, 2011

Assessing biomass steam gasification technologies using a multi-purpose model

“…The ratio of steam quantity, as shown in Figure 5, injected in the reactor directly influences the H 2 production as widely recognised in the literature [8,11,16,47]. However, a relatively high S/C ratio also increases the CO 2 production due to the water-gas shift reaction saturation and a consequent CO consumption.…”

“…The power losses in a solar-reactor are principally due to the cavity receiver efficiency, to re-radiation and reflection losses as well as cold-surface radiation losses [16]. In this study heating losses are not considered.…”

“…The one dimensional problem formulation for packed-beds is usually sufficiently accurate to describe all the phenomena acting in the reactors without introducing radial derivatives, at least as a first modelling approach [16]. As suggested by several other researchers the bed void section can withstand only minimal variations, in our case, and therefore it is supposed to be constant [24,25].…”

“…An example of 0D model for steam and solar gasification can be found in [14], where it was used to predict the output of a combined drop-tube and fixed-bed reactor. A 1-D model was proposed for an indirectly-irradiated solar reactor consisting of two cavities separated by a radiant emitter, with the upper one serving as the solar radiative absorber and the lower one containing the reacting packed bed [16]. A one-dimensional model based on autothermal gasification reactions kinetics has been proposed to simulate and validate an updraft fixed-bed HTSG pilot plant [17].…”

Design and demonstration of a prototype 1.5 kWth hybrid solar/autothermal steam gasifier

“…Previous indirectly-irradiated designs have implemented absorbing/ emitting tubes [7][8][9][10][11][12], plates [13][14][15], or cylindrical cavities [16,17] to transfer heat to reactants. SiC is commonly used as an absorbing material due to its favorable properties: high emissivity, high thermal conductivity, inertness at high temperatures, and low coefficient of thermal expansion.…”