Corrosion of High-Alloy Superheater Tubes in a Coastal Biomass Power Boiler
Bibliographic record
Abstract
Metallurgical examinations were conducted on a set of damaged high-alloy (Type 310H [UNS S31009] stainless steel and Alloy 625 [UNS N66250] weld overlay) superheater tubes removed from a coastal fluidized bed biomass power boiler, to better understand the degradation mode. Active oxidation (gas-solid reaction occurring underneath the chloride-containing fi reside deposit) was found to be the mechanism responsible for the significant loss in tube wall thickness observed on damaged superheater tubes. There exists a complex, poorly-understood synergy between the critical factors that affect active oxidation, primarily tube temperature and the supply of reactants in the fluegas, namely, sodium chloride (NaCl), sulfur dioxide (SO2), and water vapor (H2O). Overall ranking in terms of increasing corrosion resistance to active oxidation follows the expected trend: T22 < SS310H < A625WO. Despite the favorable ranking, the Alloy 625 weld overlay can corrode by active oxidation at an appreciable rate (0.45 mm/y [18 mpy]) under existing boiler operating conditions. A promising corrosion control strategy involves reducing the steam temperatures in the outlet tubes of the three superheater sections to below 500°C.
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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".