Hygroscopic Properties of Calcium Chloride and Its Role on Cold-End Corrosion in Biomass Combustion
Bibliographic record
Abstract
In biomass combustion, hygroscopic and deliquescent salts may cause cold-end corrosion and operational problems, such as deposit buildup and decrease in heat transfer. Calcium chloride is a deliquescent salt that can be found in the cold-end of boilers. In this study, the hygroscopic properties and corrosiveness of CaCl2 in flue gas conditions were studied. The formation of hydrates and the deliquescent properties of CaCl2 were studied with various techniques. The hydrate formation, deliquescence, and water absorption at various temperatures, humidities, and cooling rates were studied using thermogravimetric analysis. A stable flow of water vapor (5–35 vol %) was created with a membrane humidifier with a humidity sensor. Deliquescence and recrystallization of CaCl2 were determined by a two-electrode chronoamperometric setup. The effect of mixtures containing CaCl2, CaCO3, and CaSO4 on deliquescence was also studied. Furthermore, the corrosivity of CaCl2 on mild steel was studied above and below the deliquescence temperature, and the corrosion products were analyzed by means of scanning electron microscopy with energy dispersive X-ray spectroscopy (SEM-EDX). This work revealed that both deliquescence and recrystallization of CaCl2 are of importance when assessing the corrosivity of the salt. When deliquescence occurred, the corrosion rate was substantial, and the corrosion rate was dependent on the ion concentration of the formed solution. Drying or crystallization of the salt solution occurred at 35–42 °C higher than the deliquescence temperature with 10–35 vol % H2O. Thus, large variations in the flue gas water vapor concentration will impact the wetting and drying of the salt. The observations presented in this paper give guidelines on how to prevent corrosion caused by deliquescent CaCl2.
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How this classification was reachedexpand
Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| 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) | 0.000 | 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 teacher head, 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".