Utilization Ratio of Sea Water and Calcium Carbonate Scale Deposition
Scale Formation in Concentrating Sea Water with Ion Exchange Membrane Method (Part IV)
1972 Volume 26 Issue 1 Pages 26-32
Details
1972 Volume 26 Issue 1 Pages 26-32
In case sea water is concentrated by ion exchange membrane method, an improvement in the utilization ratio of sea water which is intended to lower the cost of salt production promotes the probability of scale deposition. The author estimated utilization ratio of sea water for CaCO3 scale deposition from the expulsion process of sea water components by the method he had previously reported, and he confirmed the results of his estimation by experiment. The results of the experimentwere as follows:
1. It was observed that carbonates (CO2+HCO3-+CO3--) in sea water showed a sudden increase in their permeability during their expulsion process. In case the temperature was higher, this phenomenon tended to occur at an early stage of the expulsion process.
2. When this phenomenon occurred, there was observed an abrupt gain in the concentration of CaCO3 on the concetrating surface of anion exchange membrane. Thus, the consequent deposition of the scale was predicted.
3. The limited utilization ratio of sea water for CaCO3 scale deposition was estimated at φUCl=0.4-0.5, and this indicated a probability, of scale deposition without the decomposition of water.
4. The experiment of some 100 hours clarified that the limited utilization ratio of sea water was 0.5-0.55. This fairly agreed with the estimated value.
5. Crystals of CaCO3 scale deposited were Aragonite in elliptical figure in any cases.
