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- Ma, Charlie, et al.
(author)
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Ash formation during pilot-scale trials of pressurized entrained-flow gasification of woody biomass
- 2012
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Conference paper (peer-reviewed)abstract
- Deposits, ash samples and residues from pressurised entrained-flow gasification (PEFG) of stem wood, bark and rejected pulpwood have been characterised with SEM-EDS during trials in an O2-blown pilot-scale reactor. Global thermochemical equilibrium calculations based on the conditions inside the hot reactor were carried out to investigate the phase distribution of potassium as both a function of temperature and Si reactivity. Substantial deposit formations on the reactor probe were only evident in the trials with the woody fuels containing a higher ash content; i.e., experiments with pulpwood and bark. Of these, the deposits formed during gasification of the pulpwood fuel, likely to have been relatively highly contaminated, showed more hard and sintered material. The deposits/slag formed contained typical sand particles (e.g. quartz and feldspars) embedded in a silicate rich melt. The melt in the slag is dominated by silicon 40-55 mol%, aluminium ~15 mol% and calcium 10-20 mol%, with a further ~10 mol% consisting of alkali metals sodium and potassium. The preliminary results suggest that fuel contaminants (e.g., quartz and feldspars) may play a significant role in the slag formation process in entrained flow gasification of woody biomass fuels and that a significant share of the potassium is leaving the hot reactor as gaseous alkali species.
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| 3. |
- Ma, Charlie, et al.
(author)
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Characterization of reactor ash deposits from pilot-scale pressurized entrained-flow gasification of woody biomass
- 2013
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In: Energy & Fuels. - : American Chemical Society (ACS). - 0887-0624 .- 1520-5029. ; 27:11, s. 6801-6814
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Journal article (peer-reviewed)abstract
- Pressurized entrained-flow gasification of renewable forest residues has the potential to produce high-quality syngas suitable for the synthesis of transport fuels and chemicals. The ash transformation behavior during gasification is critical to the overall production process and necessitates a level of understanding to implement appropriate control measures. Toward this end, ash deposits were collected from inside the reactor of a pilot-scale O 2-blown pressurized entrained-flow gasifier firing stem wood, bark, and pulp mill debarking residue (PMDR) in separate campaigns. These deposits were characterized with environmental scanning electron microscopy equipped with energy-dispersive X-ray spectrometry and X-ray diffractometry. The stem wood deposit contained high levels of calcium and was comparatively insubstantial. The bark and PMDR fuels contained contaminant sand and feldspar particles that were subsequently evident in each respective deposit. The bark deposit consisted of lightly sintered ash aggregates comprising presumably a silicate melt that enveloped particles of quartz and, to a lesser degree, feldspars. Discontinuous layers likely to be composed of alkaline-earth metal silicates were found upon the aggregate peripheries. The PMDR deposit consisted of a continuous slag that contained quartz and feldspar particles dispersed within a silicate melt. Significant levels of alkaline-earth and alkali metals constituted the silicate melts of both the bark and PMDR deposits. Overall, the results suggest that fuel contaminants (i.e., quartz and feldspars) play a significant role in the slag formation process during pressurized entrained-flow gasification of these woody biomasses.
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