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Volume 29 (1975 - 197･･･
- Issue 6 Pages 247-
- Issue 5 Pages 187-
- Issue 4 Pages 131-
- Issue 3 Pages 99-
- Issue 2 Pages 41-
- Issue 1 Pages 3-
Volume 29, Issue 5
Displaying 1-6 of 6 articles from this issue
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Fumikazu IKAZAKI, Shigeki TOYAMA, Masahito SATO, Tsutomu SUGETA1976 Volume 29 Issue 5 Pages 187-198
Published: 1976
Released on J-STAGE: February 19, 2013
JOURNAL FREE ACCESSThe optimal operation was studied for sponge-ball cleaning to recover the performance of heat transfer apparatus by removing deposited scale and sludge without stopping the operation.
The objective function to evaluate the operation in this study was composed of the additional energy cost owing to decreased performance ratio and the cost of sponge-ball lost during the operation. Their decision variables were the cleaning interval and the number of balls.
This model was applied to the MSF evaporator. The performance ratio of the evaporator was estimated on the basis of the material and heat balances of the process. In connection with the process equation, optimal calculation clarified effects of loss fraction of ball, sludge removal fraction, fouling factor, steam cost, and sponge-ball cost.
Followings are the results induced.
(1) The ball cost was a controlling factor in a short-cleaning interval, and the steam cost in a long interval. The optimal cleaning interval was the time when the both cost constituents in the objective function were comparable.
(2) The cleaning cost was apt to decrease in line with the increase of number of balls and the consequent decrease of cleaning time.
(3) The sensitivity of the fouling factor to the optimal cleaning interval was insignificant, even if the fouling factor would increase.
The results suggested that the sponge-ball cleaning could be widely used as a technique to recover the performance of heat apparatus if deposited scale and sludge were softened by adding appropriate chemicals.View full abstractDownload PDF (6687K) -
Studies on Mother Liquid in Salt-Manufacturing Process (Part 27)Tsutomu MASUZAWA, Yoshio YONEI, Taeko MATSUMOTO1976 Volume 29 Issue 5 Pages 199-208
Published: 1976
Released on J-STAGE: February 19, 2013
JOURNAL FREE ACCESSQualities of Korean solar salts were studied from the concentrating process of sea water and the growth of their crystals. And the following results were obtained;
1. According to the analytical results of the Korean solar salts imported in 1960-1962, they were composed of 88-91% sodium chloride, 6-7% water content, 0.3-0.5% ipsoluble matters, 0.3-0.4% magnesium ion and 0.09-0.17% calcium ion. They were much inferior to those of the Mexican and Australian solar salts which have been imported recently.
2. The observation of the samples taken from the Korean solar salt-field in 1971 showed that they were of 1-2 mm particle-size and porous crystals containing much mother liquid therein. Moreover, they contained a large amount of cavities in crystals.
3. Brines, mother liquids and salts from the worst section among Sorae Salt-Field (No.3100) taken in 1971 were analysed. The results showed that the compositions of the brines had been on the concentrating process line of sea water, while those of the mother liquids in the crystallizing pond had been excessively concentrated to such an extent of 30-32° Bé and shifted from the concentrating process line of sea water to the composition point of magnesium sulfate.
4. The inferior qualities of Korean solar salts are considered to be caused by the fact that they are crystallized in such an excessive concentrating process of sea water (30-32° Bé). Therefore, they contain much more cavities in crystals and because they are crystallized in the crystallizing pond where the depth of the brine is as shallow as about 10 mm, they grow rapidly towards {111} direction resulting in the porous structure containing a large amount of mother liquid. Also, only a day or two harvesting period brings about such small particle-size as 1-2 mm.
5. The apparent densities of the Korean solar salts were 0.7-0.8g/cm3(coarse) and 1.0-1.1g/cm3(dense), which were smaller than those of any other solar saits.View full abstractDownload PDF (6829K) -
Yoshinobu TANAKA1976 Volume 29 Issue 5 Pages 209-217
Published: 1976
Released on J-STAGE: February 19, 2013
JOURNAL FREE ACCESS(1) From the membrane potential measurement of ion exchange membranes immersed in aqueous sodium chloride, concentration changes at diffusion layer and thickness of the diffusion layer were estimated. It was recognized that concentration polarization showed a trend to occur more easily at cation exchange membranes than at anion exchange membranes.(2) In the dialysis of aqueous sodium chloride or sea water, the limiting current density for concentration polarization and for dissociation of water was measured from current density-voltage curve and current density-solution pH curve. It was observed that with anion exchange membranes, both limiting current densities coincided with each other for the most part, but that with cation exchange membranes, the limiting current density for the dissociation of water was larger than that for the concentration polarization.(3) The influence of the concentration and velocity of the solution in a desalting cell upon the limiting current density was measured.(4) The limiting current density formula for the concentration polarization, which is applicable in the dialysis of multiple component ionic solutions, was led, and the limiting current density in the dialysis of sea water was estimated by using this formula.View full abstractDownload PDF (5246K) -
Desorption of Oxygen and Carbon Dioxide from Sea Water (Part 3)Kenzaburo OBATA, Kunio SUGINO, Koichi TAWARA, Takayoshi YAGASAKI1976 Volume 29 Issue 5 Pages 218-227
Published: 1976
Released on J-STAGE: February 19, 2013
JOURNAL FREE ACCESSIn general, vacuum deaeration is in practical use for the prevention of the sea-water desalination plant from corrosion. In this paper, an experiment of deaeration from fresh water was conducted to examine the application of spray towers combined with liquid jet for vacuum deaeration.
Those towers used for this experiment were 2-2.6 meters high and 40-130 mm in diameter. The spray nozzles were single nozzles with 2-3 mm diameter and a multi-nozzle with 20 perforations of 2 mm diameter. The liquid flow-rate at the nozzle was varied from 0.7 m/sec to 12 m/sec, and the distance of liquid fall-down was varied from 0.1 m to 1.9 m.
The results were that the tower pressure, the length of the nozzle and the flow-rate of stripping steam caused no influence to the H. T. U. of the tower. Very small influence of the liquid flowrate at the nozzle on the H. T. U. was observed. On the other hand, the H. T. U. showed a remarkable increase when there was an increase in the distance of the liquid fall-down.
The relation between the H. T. U. and the operating conditions of the tower and the chracteristics of the liquid observed in this study, nearly agreed with J. Mada's dimensionless equation obtained by the absorption experiment of carbon dioxide. However, when the gas bubble entrainment caused by liquid fall-down was restrained, this relation was found to deviate from the equation. This meant that the disturbance by gas bubbles promoted deaeration. When a portion of the feed flashed, the influence on the H. T. U. was not so remarkable as in the vacuum deaeration in the packed tower.
From these results, it was considered possible to apply the vacuum deaeration by the spray tower combined with liquid jet to the sea-water desalination plant if in the plant some pressure drop was allowed, the distance of liquid fall-down made shorter, and the multi-stage splayed to the spray tower.View full abstractDownload PDF (6172K) -
Osamu MIYATAKE, Toshiaki TANAKA, Tetsu FUJII1976 Volume 29 Issue 5 Pages 228-231
Published: 1976
Released on J-STAGE: February 19, 2013
JOURNAL FREE ACCESSAn experimental investigation was made to clarify the effect of injection of nuclei of gas bubbles produced by the electrolysis of flashing liquid upon the flash evaporation.
Under various flashing conditions, measurements were made on the temperature distributions and the non-equilibrium temperature differences in a 1.0 m long flash chamber with and without baffle plates.
The results were compared with the previous measurements made for the case of no injection of nuclei.
In the case of a flash chamber without a baffle plate, the effect of nucleation is to increase the penetration depth of the flash evaporation and to decrease the non-equilibrium temperature difference.View full abstractDownload PDF (2488K) -
[in Japanese]1976 Volume 29 Issue 5 Pages 232-239
Published: 1976
Released on J-STAGE: February 19, 2013
JOURNAL FREE ACCESSDownload PDF (5283K)
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