The solutions containing predicted salts obtained from univalent permselective cation and anion exchange membranes were evaporated to given stages at boiling point (1 atm.) and equilibrated at 70, 45 and 25°C respectively, for the purpose of the studies on the elevation of specific gravity, the change of the composition and the deposition of salts. The results obtained were as follows: 1) After 700g water per 1 kg brine was evaporated, both boiling point and specific gravity increased sharply. Magnesium chloride seemed to have the most influence on the boiling point elevation and increase of the specific gravity. Between the latter two and chlorinity, linear relations were recognized, which can be used for the index of evaporation in the actual salt-factories. 2) Amount of deposited salts increased linearly with that of evaporated water. The more water was evaporated, the less temperature affected the amount of deposited salts. 3) Calcium sulfate precipitated in about same concentration as sodium chloride. If brine contains 0.1% calcium sulfate, it was deposited after deposition of sodium chloride. Thus, it will hardly affect the heat transfer as scale. 4) Potassium chloride was deposited in more advanced range of concentration than sodium chloride or calcium sulfate, that is, after 95% deposition of sodium chloride was at 25°C. It may be said, therefore, that there seems to be no fear of contamination of sodium chloride with potassium chloride in the usual salt makings.
It has been already made clear in our previous report that a small-sized cooling tower (4m2, 5m height) of the natural draft type showed an excellent capacity both in cooling and concentrating sea water or brine. In this report, the authors made another study on various effects which the increasing rate of the feed exerted upon the cooling and concentrating capacities of a practical-size cooling tower. Major results obtained from this study were as follows: 1.Effects exerted by the amount of feed L/S (excluding L/S≥3m2/m2·hr) upon the overall volumetric coefficients KOG·a and the overall volumetric heat transfer coefficients Kv could be expressed by the following experimental formulae: KOG·a=K (L/S)0.45(Kcal/m3·hr·Δi) and Kv=K (L/S)0.32(Kcal/m3·hr·°C) where K was constant. 2. Apparent wind velocity in the cooling tower was in the range of 1/10 to 1/20 of the open wind velocity at the top of the cooling tower. 3. Effects exerted by the open wind velocity u m/sec at the top of the cooling tower, the temperature t1°C and by the amount of the feed L/S upon the amount of evaporation were expressed by the following formula: e=0.05u0.16(L/S)0.46.(t1)1.67(mm/hr)
In this paper, an experiment was made on the hydrolysis of sodium chloride solution by using a combined double membrane of anion exchange and vinylon membranes. As the result, it was confirmed that the current efficiency of hydrolysis showed a decrease in proportion to an increase in the concentration of sodium chloride solution and to a decrease in current density, but the use of the double membrane made it possible to hydrolize with an efficiency of 70-75% in 0.1 N solution. It is of great interest to the manufacture of hydrolysis membrane that the combined membrane of anion exchange and neutral membranes showed such an excellent hydrolizing ability.
Mobilities of counter ions in exchange membranes were measured by newly devised electrophoretic apparatus. In this case, two different methods were used. A first method was a direct one, by which electrophoretic distance of counter ions was measured by using22 Na and36 Cl isotopes. A second method was an indirect one, by which the mobility of counter ion was calculated from its transport number, ionic concentration in membrane and specific conductance. The results obtained were as follows: 1. In general, the mobility of the counter ion could be estimated by the second indirect method, since the value obtained by this method approximated to that of the direct method in case the same kind of membrane was used. 2. The mobility of counter ions in the membranes was lower than that in aques solution, and the value decreased to about 1/10 of that in aqueous solution for univalent ions excluding hydroion and hydroxidion, and it also decreased to about 1/20-1/50 for divalent ions. 3. The great decrease in the mobility of divalent ions in the membrane was derived from the fact that the affinity of divalent ions for functional group in the membrane was greater than that of univalent ions.