A practical approach to eliminating rapid sodium carbonate - sodium sulfate scaling in black liquor concentrators

摘要

Black liquor concentrators perform as crystallizers as well as evaporators, producing up to 200 kg of sodium carbonate - sodium sulfate double salt (Na2CO3+Na2SO4) crystals per o.d. metric ton of pulp produced. One of these salts, sodium sulfate dicarbonate, rapidly fouls many concentrators as it crystallizes from solution. Design and operation of black liquor concentrators to manage its crystallization can eliminate or substantially reduce sodium sulfate dicarbonate scaling. Older equipment installed before sodium sulfate dicarbonate was discovered in 2002 would benefit the most. This paper explores options for reducing rapid sodium sulfate dicarbonate scaling in black liquor concentrators by applying today's knowledge of sodium sulfate dicarbonate crystallization characteristics and behavior during crystallizing evaporation.