Energy consumption issue in evaporating and concentrating 30% liquid caustic to 50% concentration
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Currently, the evaporation and concentration of 50% caustic soda solution is carried out using a two-effect vacuum evaporation process. Part of the secondary steam is ultimately condensed in surface condensers, with the energy being wasted into the cooling water. If there is a way to utilize the secondary steam generated by evaporation (for example, to heat low-temperature brine), can raw steam be used directly for evaporation at atmospheric pressure, thereby avoiding the use of double-effect vacuum evaporation (since the quality of the secondary steam produced by vacuum evaporation is too low to be utilized)? Which of the two methods is more energy-efficient?
MVR can repressurize and reuse steam, making it more energy-efficient than multi-effect evaporation
I’m not sure what level the temperature rise and pressure ratio of current steam compressors can reach, nor whether it’s possible to compress the secondary steam and return it to the evaporator as a substitute for fresh steam. Liquid caustic has a very high boiling point