Effect of Bed Material on Oxygen/Steam Gasification of Two Solid Recovered Fuels (SRFs) in a Bench-Scale Fluidized-Bed Reactor

Abstract

The goal of this study is to assess the release of contaminants during the oxygen/steam gasification of two waste-derived fuels using three different bed materials. The solid recovered fuels (SRFs) were tested at 850 °C in a bench-scale fluidized-bed reactor with sand, dolomite, and olivine as bed materials. The effects of the experimental conditions were assessed based on the gasification performance (product yields, carbon conversion, etc.) and the presence of tar, including polycyclic aromatic hydrocarbons (PAHs) and minor contaminants (HCl, H2S, HCN, and NH3) in the producer gas. The results show higher gas yields with the use of catalysts, particularly dolomite, and a lower catalytic activity of olivine toward tar abatement. The presence of contaminant precursors (Cl, S, and N) together with the concentration of metals from both catalysts and waste fuel ashes appear to influence the evolution of contaminants. In general, dolomite is more efficient than olivine in reducing tar compounds and most minor contaminants but NH3, whereas olivine mainly exhibits the ability to reduce light PAHs and nitrogenous compounds (HCN and NH3) in the producer gas.

Distribution of Inorganics and Trace Elements during Waste Gasification in a Bench-Scale Fluidized Bed

“…The use of dolomite as bed material has also led to increased NH 3 yield and decreased HCN yield in peat gasification in a fluidized bed . This seems to be related to the catalytic properties of calcined dolomite in converting char and producing ammonia, as calcium oxide (CaO) is known to enhance the conversion of HCN into NH 3 . , Regarding the filter dust, it increases when using dolomite as the bed material, and this can be related to smaller particles being formed during the gasification due to attrition and then being elutriated from the bed and collected in the filter, which could explain the higher amount of filter dust–N . The conversion into tar–N was the lowest in experiment 6 (0.5 wt %), while it did not considerably vary in experiments 1 (1.3 wt %), 2 (1.4 wt %), and 3 (1.4 wt %).…”

“…37,42 Regarding the filter dust, it increases when using dolomite as the bed material, and this can be related to smaller particles being formed during the gasification due to attrition and then being elutriated from the bed and collected in the filter, which could explain the higher amount of filter dust−N. 11 The conversion into tar−N was the lowest in experiment 6 (0.5 wt %), while it did not considerably vary in experiments 1 (1.3 wt %), 2 (1.4 wt %), and 3 (1.4 wt %). This result may be related to the lower tar production in experiment 6 due to dolomite's catalytic properties for tar conversion, even though a reduction of total tars was not observed in experiment 6 (see Figure 4).…”

“…Among the thermochemical options, fluidized bed gasification is a suitable route to convert wastes since it is a flexible technology regarding fuel size and composition and can be applied to electricity production at small and medium scales . The content in pollutant species during gasification of wastes (as in other thermochemical options) is of concern, and thus, more complex downstream cleaning steps are needed compared to the processing of clean biomass depending on the syngas end application. , A great deal of work exists on the formation of pollutants and their fate during gasification of wastes. ,,− …”

Gasification of Low-Grade SRF in Air-Blown Fluidized Bed: Permanent and Inorganic Gases Characterization

“…In addition, part of the syngas water could have condensed in the Tedlar bag during sampling, possibly leading to NH3 dissolution [93]. Nevertheless, no trace of condensation was observed in the Tedlar bag during experiments.…”