Surface characterization of ash-layered olivine from fluidized bed biomass gasification

Abstract

The present study aims to present a comprehensive characterization of the surface of ash-layered olivine bed particles from dual fluidized bed gasification. It is well known from operation experience at industrial gasification plants that the bed material is activated during operation concerning its positive influence on gasification reactions. This is due to the built up of ash layers on the bed material particles; however, the chemical mechanisms are not well understood yet. Olivine samples from long-term operation in an industrial-scale gasification plant were investigated in comparison to fresh unused olivine. Changes of the surface morphology due to Ca-enrichment showed a significant increase of their surface area. Furthermore, the Ca-enrichment on the ash layer surface was distinctively associated to CaO being present. The presence of CaO on the surface was proven by adsorption tests of carbon monoxide as model compound. The detailed characterization contributes to a deeper understanding of the surface properties of ash layers and forms the basis for further investigations into their influence on gasification reactions.

Interactions of Olivine and Silica Sand with Potassium- or Silicon-Rich Agricultural Residues under Combustion, Steam Gasification, and CO2 Gasification

“…69 However, this process is unlikely to occur for olivine as the structure is already a nesosilicate. 69 Interestingly, the only reactive interaction found previously between olivine and biomass ash was for Ca-rich woody biomass, 22,28,70 for which Ca was found to diffuse into the olivine structure by substituting Mg 2+ /Fe 2+ . 29 This solid−solid substitution reaction was found to result in the formation of Ca-rich coating layers onto the olivine bed material, with little take-up of potassium composition (only 2.6 wt % in the inner layer 25 ).…”

A comparative study in 3D of bed particle layer characteristics in quartz and K-feldspar from fluidized bed combustion of woody biomass using X-ray microtomography

“…The fact that the imaging routine is non-destructive makes it possible to do repeated scans, perform multiscale studies, and follow structural changes/deformations in the sample in-situ when exposed to different loads or environments [19]. These features has made the technique a decent tool for 3D material characterization, with a wide range of applications [20][21][22].…”

Investigation of Biomass Fouling on Screw Feeder in Preconversion of Pyrolysis

“…Pyrolysis of biomass can generate liquid fuel, which is part of the portfolio of renewable energies replacing conventional fossil fuels. While biomass thermal conversion has seen significant advances in fundamentals, the actual production still faces many technical challenges, from equipment wear in feedstock size reduction − to plugging problems in biomass conveying. − …”

“…When high pressure and/or high temperature are present, biomass is prone to decompose into solid char and ash, noncondensable gases, and multiple liquid phases . In previous studies in the literature, characterization and modeling of biomass charring were often conducted after the conversion process. − There still exists a gap in knowledge on biomass thermal decomposition in the preconversion stage. When the feedstock is fed into a high-temperature reactor via a screw feeder, the biomass undergoes a large temperature gradient from room temperature at the inlet to the high temperature (several hundred degrees Celsius) at the outlet connected to the reactor.…”