Stability of Sodium Sulfate Dicarbonate in Black Liquor Concentrators

摘要

1. Sodium sulfate dicarbonate is a unique phase and can be crystallized in pure form at a range of solution composition and temperatures above 110℃ 2. Sodium sulfate dicarbonate is not a metastable species 3. Dicarbonate crystals are chemically stable in process at 115℃ 4. Dicarbonate does not transform or degenerate to other species on extended contact with mother liquor or hot air (200℃) 5. EDTA used to sequester calcium ions does not affect the sodium sulfate dicarbonate phase, but may influence crystal growth habit (shape) 6. Habit modification may be a key to reducing the fouling tendency of dicarbonate 7. Dicarbonate exists in black liquor evaporators and concentrators 8. Under certain condition, dicarbonate can form small nodules which can rapidly plug tube-type falling film units.