CaS Oxidation by Reaction with CO<sub>2</sub> and H<sub>2</sub>O
Bibliographic record
Abstract
Calcium sulfide is an undesirable product from both FBC and topping cycle gasifiers. Unfortunately, its direct oxidation in a FBC environment is made difficult due to the fact that unreacted CaS is protected from further reaction with O 2 by formation of a CaSO 4 shell. In previous work it was often implied that oxidation of CaS occurred solely by reaction with O 2 . However, this study shows that CO 2 can be an effective oxidant for CaS at temperatures above 600 °C. Furthermore, it appears that the principal gas-phase products are SO 2 and CO, and direct attempts to measure COS using mass spectrometry suggest that its formation is negligible. Somewhat surprisingly, SO 2 /CO molar ratios are in the range of 0.4 to 0.5, which is problematic, if the dominant reaction is CaS + 3CO 2 CaO + 3CO + SO 2, unless CO 2 is reacting to form elemental carbon, which appears unlikely, or side reactions occur, leading to a variety of gaseous products. These results also suggest that CO itself has no significant part in the oxidation process at least up to 850 °C or more. Reaction with H 2 O also begins above 600 °C, but it is a much less effective oxidant, and experiments with CO 2 /H 2 O further support the idea that CO 2 is the more important oxidant and might be used to destroy CaS from topping cycle gasifiers.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.001 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".