A new method was studied to represent the three dimensional field of NaCl crystallization on the Ordinary tetrahedron coordinate in the quinary system on a simple triangle coordinate. The spacial diagram on the tetrahedron was projected on the base (KCl-MgCl2-CaCl2) by using both the graphicalmethod of Schreinemakers and, at the same time, that of Janecke. The diagram thusprepared was composed of two figures, representing any arbitrary composition, within the field by two points; by one point the g/100g solution composition is represented and by the other the g/100g (KCl+MgCl2+CaCl2) composition. One can, also, find out the composition of any points in a rather simple way. As an example of practical application of the graphical representation, the concentration process of ion exchange membrane brine produced in salt manufacturing factory in this cOuntry was investigated by means of the diagram of the quinary system at 25°C.
The boiling point elevation of various aqueous solutions containing sodium chloride, potassium chloride, sodium sulfate, sodium carbonate, calcium chloride and magnesium chloride were measured by using a twin-type ebulliometer in the weight per cent range of 1% to 15% under the atmospheric pressure, and very accurate data were obtained there from. The B. P. E. data of each aqueous solution containing an inorganic salt were correlated with the weight per cent of the salt for three equations. The constants of the three equations for each solution were determined by the least square method. The best equation for smoothing the B. P. E. data was cubic equation of the weight per cent of each inorganic salt. The boiling point elevations calculated from the cubic equation were approximated to experimental values with high degree of accuracy.
The data related to the boiling point elevation is very important for designing a desalination plantand also as the constant for the thermodynamics of sea water. Many B. P. E. data have so far been reported, but some of them have less reliability because of a big discrepancy among the reported, values. Therefore, it is necessary to get the B. P. E. data with high degree of accuracy. In this study, the experimental B. P. E. data of sea water were obtained in the temperature range of 60.0°C to 130.0°C and in the salinity range of about 1.7% to 11% by using a new twin-type. ebulliometer made of stainless steel. The data obtained from this work agreed well with Lhe estimated values by Stoughton and Lietzke and with the observed values by Bromley. The B. P. E. data of sea water were correlated with salinity% and system temperature (boiling point of pure water) for an equation with six constants. Their constants were determined by the least square method, and the following equation was derived therefrom: B. P. E.=0.528764×10-1.X+0.826030×10-3·XT-0.315082×10-7·XT2+0.320553×10-2·X2-0.144367×10-4·X2T+0.184416×10-6·X2T2 where, B. P. E.=boiling point elevation, ° X=salinity, wt.% T=system termperature, ° The calculated values from the equation were approximated within 0.006°C of average deviation and 0.020°C of the maximum error to the experimental values.
Deaerated hot fresh-water produced by a multi-flush evaporator has much corrosive effect on ferrous materials used for the evaporator. To examine the effect of some environmental factors of the fresh-water on the corrosion of ferrous materials, autoclave tests were conducted. In this study, mild steel and 2 1/4 Cr-1 Mo steel were used as test samples and exposed to the fresh-water of various dissolved oxygen levels, chloride ion contents, and temperatures. The results obtained from this study were as follows. Speaking in general, both the corrosion losses and the effects of the environmental conditions were small under static condition. Under a dynamic condition (flow rate 2m/sec), however, the corrosion losses indicated a remarkable increase, and at the same time, the effect of each environmental condition became clear. In all the test conditions, the corrosion resistance of 2 1/4 Cr-1 Mosteel was proved to be superior to mild steel. The corrosion rate of mild steel in the fresh-water at a high flow rate was larger than expected, and it was as large as twice than that in 3% sodium chloride solution according to conditions. These unusual results were assumed to depend on the instability of some oxide film (it may be magnetite) formed in the fresh-water.
When seawater is desalted by evaporation method, some polluting materials contained in seawater seem to evaporate and concentrate into the product water. To examine the behaviors of such materials in this process, an experiment was made on ammonium ion (NH4+) by using a 3,000 m3/day multi-stage flash evaporator (Fig.1) and a laboratory-scale distillation flask. In the plant test, aqueous ammonium chloride solution was added to the make-up line of the evaporator, and the distribution of NH4+ in the plant was traced. When the pH of the circulating brine of the plant was 7.0 or higher, about 65-75% of the added NH4+ was found to concentrate into the product water (the concentration rate: 1.5-1.7)(Table 1, Figs. 6 A, 7 A). In the flask test, after the pH was adjusted at 6.0-9.0 with borate buffer and a small amount of NH4+ was added, the effluent brine of this plant was distilled under the atmospheric pressure. The distillate was taken when its amount reached 3.6% or 14.3% of the total volume, and the distribution of NH4+ in the distillate and in the residue was examined (Figs. 3, 4). The first 3.6% of distillate was found to concentrate NH4+ when the pH of the brine was higher than 6.4, and the first 14.3% of distillate was found to concentrate NH4+ when the pH was over 6.6. In the plant test where 13.6% of the brine was distilled, the limiting pH to concentrate NH4+ to the product water was around 6.9 (Fig. 8) probably because the distillation took place under various pressures and the gas-liquid equilibria varied from that of the flask test. The pH of the circulating brine in distillation plants is kept at 7.0 or higher in general, and naturally NH4+ is concentrated into the product water. Therefore, in case the distillation is carried out in a plant located near seawaters polluted with NH4+, some proper treatment must be made to remove NH4+ or the operation must be performed keeping the pH of the circulating brine under about 6.
The behavior of water molecules and NaCl aqueous solution on acetylcellulose was investigated by high resolution NMR measurement. The temperature dependence of half line width and chemical shift of water suggested that the interaction of water with acetyl cellulose was rather strong. The addition of NaCl or the elevation of temperature weakened the interaction. The lower the temperature became, the stronger the interaction was. Dissociated ions in the solution disturbed the interaction between the water molecules and the acetyl cellulose. However, the concentration dependence of the NaCl solution was not obvious. This suggested the degree of interruption by the ions was not so large.