The Experts below are selected from a list of 207 Experts worldwide ranked by ideXlab platform
Masaaki Yokota - One of the best experts on this subject based on the ideXlab platform.
-
seeded batch multi stage natural cooling crystallization of Potassium Alum
Journal of Chemical Engineering of Japan, 2002Co-Authors: Noriaki Kubota, Norihito Doki, Shigeko Sasaki, Masaaki YokotaAbstract:Seed crystals of Potassium Alum were grown in batches with no secondary nucleation by a multi-stage natural cooling technique, where the temperature of the solution saturated at 40°C was lowered in steps from over the saturation temperature to 20°C. Seed crystals of 42 μm, which were introduced just at the saturation temperature of 40°C, were grown successfully to final sizes of 318, 563, 732, and 1070 μm, with 1-, 3-, 5-, 6-, 7-, and 9-stage coolings. The number of cooling stages and the required temperature decrease in each stage were determined a priori, using a mass balance equation, an experimental correlation of the critical seed loading ratio (over which seed loading it is guaranteed there will be no secondary nucleation) versus seed size, and solubility data. This multi-stage cooling method is a promising technique to grow seed crystals to a desired size in batch cooling crystallization.
-
determination of critical seed loading ratio for the production of crystals of uni modal size distribution in batch cooling crystallization of Potassium Alum
Journal of Chemical Engineering of Japan, 2002Co-Authors: Norihito Doki, Noriaki Kubota, Masaaki Yokota, Angelo ChianeseAbstract:Batch cooling crystallization of Potassium Alum in aqueous solution was conducted over a wide range of seed loading with various average seed sizes under the natural cooling condition. A solution of a low saturation temperature was used. In this dilute solution the supersaturation during crystallization did not become high so that agglomeration of the original seeds was avoided even for small seeds. The critical seed loading ratio Cs*, the critical value of the ratio of seed mass to the theoretical crystal yield, above which loading seed crystals were grown with no secondary nucleation, was determined. It was correlated as a second order equation of mean mass size Ls [μm], as Cs* = 2.17 × 10–6Ls2. The value of Cs* was confirmed, by comparing with previous data published by the present authors, not to change significantly with crystallizer volume, stirrer speed, the saturation temperature of the solution (i.e., the solution concentration) and the cooling mode. This correlation is shown to be conveniently used to determine the seed amount satisfying an optimal seeding condition of Cs ≥ Cs* for a given seed size. The mean mass size of product crystals and the volume of a crystallizer required for a desired production is easily determined for this optimal seed loading condition by the aid of a simple mass balance.
-
effect of cooling mode on product crystal size in seeded batch crystallization of Potassium Alum
Chemical Engineering Journal, 2001Co-Authors: Norihito Doki, Noriaki Kubota, Akira Sato, Masaaki YokotaAbstract:Potassium Alum was crystallized by seeding in a batch crystallizer under controlled and natural cooling modes. Regardless of the cooling mode, the product crystal size distribution (CSD) became bi-modal at low seed concentrations because of enormous secondary nucleation. The mean mass size of the product was smaller for the natural cooling mode compared to that for the controlled cooling mode with more intensive secondary nucleation. On the other hand, at high seed concentrations, the product CSD became uni-modal with the same mean mass size for both cooling modes, where the crystallization was dominated by seed growth. The low supersaturation caused by the growth of enough seeds plays a key role to produce uni-modal size distribution with suppressed nucleation. Adhering of small crystals (secondary nuclei) to growing seed crystals is also considered to be another mechanism for generating uni-modal CSD.
-
scaleup experiments on seeded batch cooling crystallization of Potassium Alum
Aiche Journal, 1999Co-Authors: Norihito Doki, Noriaki Kubota, Akira Sato, Masaaki Yokota, Osamu Hamada, Fumio MasumiAbstract:Potassium Alum was crystallized by natural cooling in two well-mixed laboratory-scale (12.2 L) and pilot-scale (600 L) crystallizers. When unimodal product crystals of grown seeds were used, no scaleup effect on product crystal-size distribution (CSD) was observed if enough seeds were loaded over a critical seed concentration. Cooling rate, crystal yield (crystal suspension density), and stirring condition do not seriously affect the product CSD under such a seeding condition. Low supersaturation peak caused by the growth of enough seeds, the short period of nucleation, and the agglomeration of nuclei to the growing seed crystals are considered to be mechanisms working to produce unimodal product crystals of grown seeds. Simple design calculations are demonstrated to determine the amount of seed with the help of a critical seed concentration, which can be determined easily from laboratory-scale experiments. Crystallizer volume was calculated simply from a mass balance.
Noriaki Kubota - One of the best experts on this subject based on the ideXlab platform.
-
seeded batch multi stage natural cooling crystallization of Potassium Alum
Journal of Chemical Engineering of Japan, 2002Co-Authors: Noriaki Kubota, Norihito Doki, Shigeko Sasaki, Masaaki YokotaAbstract:Seed crystals of Potassium Alum were grown in batches with no secondary nucleation by a multi-stage natural cooling technique, where the temperature of the solution saturated at 40°C was lowered in steps from over the saturation temperature to 20°C. Seed crystals of 42 μm, which were introduced just at the saturation temperature of 40°C, were grown successfully to final sizes of 318, 563, 732, and 1070 μm, with 1-, 3-, 5-, 6-, 7-, and 9-stage coolings. The number of cooling stages and the required temperature decrease in each stage were determined a priori, using a mass balance equation, an experimental correlation of the critical seed loading ratio (over which seed loading it is guaranteed there will be no secondary nucleation) versus seed size, and solubility data. This multi-stage cooling method is a promising technique to grow seed crystals to a desired size in batch cooling crystallization.
-
determination of critical seed loading ratio for the production of crystals of uni modal size distribution in batch cooling crystallization of Potassium Alum
Journal of Chemical Engineering of Japan, 2002Co-Authors: Norihito Doki, Noriaki Kubota, Masaaki Yokota, Angelo ChianeseAbstract:Batch cooling crystallization of Potassium Alum in aqueous solution was conducted over a wide range of seed loading with various average seed sizes under the natural cooling condition. A solution of a low saturation temperature was used. In this dilute solution the supersaturation during crystallization did not become high so that agglomeration of the original seeds was avoided even for small seeds. The critical seed loading ratio Cs*, the critical value of the ratio of seed mass to the theoretical crystal yield, above which loading seed crystals were grown with no secondary nucleation, was determined. It was correlated as a second order equation of mean mass size Ls [μm], as Cs* = 2.17 × 10–6Ls2. The value of Cs* was confirmed, by comparing with previous data published by the present authors, not to change significantly with crystallizer volume, stirrer speed, the saturation temperature of the solution (i.e., the solution concentration) and the cooling mode. This correlation is shown to be conveniently used to determine the seed amount satisfying an optimal seeding condition of Cs ≥ Cs* for a given seed size. The mean mass size of product crystals and the volume of a crystallizer required for a desired production is easily determined for this optimal seed loading condition by the aid of a simple mass balance.
-
effect of cooling mode on product crystal size in seeded batch crystallization of Potassium Alum
Chemical Engineering Journal, 2001Co-Authors: Norihito Doki, Noriaki Kubota, Akira Sato, Masaaki YokotaAbstract:Potassium Alum was crystallized by seeding in a batch crystallizer under controlled and natural cooling modes. Regardless of the cooling mode, the product crystal size distribution (CSD) became bi-modal at low seed concentrations because of enormous secondary nucleation. The mean mass size of the product was smaller for the natural cooling mode compared to that for the controlled cooling mode with more intensive secondary nucleation. On the other hand, at high seed concentrations, the product CSD became uni-modal with the same mean mass size for both cooling modes, where the crystallization was dominated by seed growth. The low supersaturation caused by the growth of enough seeds plays a key role to produce uni-modal size distribution with suppressed nucleation. Adhering of small crystals (secondary nuclei) to growing seed crystals is also considered to be another mechanism for generating uni-modal CSD.
-
scaleup experiments on seeded batch cooling crystallization of Potassium Alum
Aiche Journal, 1999Co-Authors: Norihito Doki, Noriaki Kubota, Akira Sato, Masaaki Yokota, Osamu Hamada, Fumio MasumiAbstract:Potassium Alum was crystallized by natural cooling in two well-mixed laboratory-scale (12.2 L) and pilot-scale (600 L) crystallizers. When unimodal product crystals of grown seeds were used, no scaleup effect on product crystal-size distribution (CSD) was observed if enough seeds were loaded over a critical seed concentration. Cooling rate, crystal yield (crystal suspension density), and stirring condition do not seriously affect the product CSD under such a seeding condition. Low supersaturation peak caused by the growth of enough seeds, the short period of nucleation, and the agglomeration of nuclei to the growing seed crystals are considered to be mechanisms working to produce unimodal product crystals of grown seeds. Simple design calculations are demonstrated to determine the amount of seed with the help of a critical seed concentration, which can be determined easily from laboratory-scale experiments. Crystallizer volume was calculated simply from a mass balance.
-
Minimum seed crystal size for secondary nucleation of Potassium Alum in a stirred-vessel crystallizer.
Journal of Chemical Engineering of Japan, 1990Co-Authors: Noriaki Kubota, Masato FujiwaraAbstract:The minimum seed crystal size or the minimum size, usually defined as the critical size greater than which seed crystals can produce secondary nuclei, was measured for Potassium Alum secondary nucleation using a seeded stirred-vessel crystallizer. The value was lowered with increasing stirrer speed both for stainless steel and acrylic resin impellers. The former impeller gave a smaller minimum size than the latter. The minimum size was newly interpreted as a measure of difficulty of nucleation, by defining it as the seed size at which the nucleation rate, being increased as the seed crystals grow, reached a certain detectable level. The behavior of the experimental results and literature data (effects of stirrer speed, supersaturation, impeller materials, impurities and system size) for laboratory crystallizers were reasonably but qualitatively explained in terms of secondary nucleation caused by crystal-impeller collisions. It was concluded that nucleation data obtained in a laboratory, using a small crystallizer, would be difficult to apply to industrial crystallizers because crystal-impeller collisions are unlikely to occur in large-scale industrial systems.
Norihito Doki - One of the best experts on this subject based on the ideXlab platform.
-
seeded batch multi stage natural cooling crystallization of Potassium Alum
Journal of Chemical Engineering of Japan, 2002Co-Authors: Noriaki Kubota, Norihito Doki, Shigeko Sasaki, Masaaki YokotaAbstract:Seed crystals of Potassium Alum were grown in batches with no secondary nucleation by a multi-stage natural cooling technique, where the temperature of the solution saturated at 40°C was lowered in steps from over the saturation temperature to 20°C. Seed crystals of 42 μm, which were introduced just at the saturation temperature of 40°C, were grown successfully to final sizes of 318, 563, 732, and 1070 μm, with 1-, 3-, 5-, 6-, 7-, and 9-stage coolings. The number of cooling stages and the required temperature decrease in each stage were determined a priori, using a mass balance equation, an experimental correlation of the critical seed loading ratio (over which seed loading it is guaranteed there will be no secondary nucleation) versus seed size, and solubility data. This multi-stage cooling method is a promising technique to grow seed crystals to a desired size in batch cooling crystallization.
-
determination of critical seed loading ratio for the production of crystals of uni modal size distribution in batch cooling crystallization of Potassium Alum
Journal of Chemical Engineering of Japan, 2002Co-Authors: Norihito Doki, Noriaki Kubota, Masaaki Yokota, Angelo ChianeseAbstract:Batch cooling crystallization of Potassium Alum in aqueous solution was conducted over a wide range of seed loading with various average seed sizes under the natural cooling condition. A solution of a low saturation temperature was used. In this dilute solution the supersaturation during crystallization did not become high so that agglomeration of the original seeds was avoided even for small seeds. The critical seed loading ratio Cs*, the critical value of the ratio of seed mass to the theoretical crystal yield, above which loading seed crystals were grown with no secondary nucleation, was determined. It was correlated as a second order equation of mean mass size Ls [μm], as Cs* = 2.17 × 10–6Ls2. The value of Cs* was confirmed, by comparing with previous data published by the present authors, not to change significantly with crystallizer volume, stirrer speed, the saturation temperature of the solution (i.e., the solution concentration) and the cooling mode. This correlation is shown to be conveniently used to determine the seed amount satisfying an optimal seeding condition of Cs ≥ Cs* for a given seed size. The mean mass size of product crystals and the volume of a crystallizer required for a desired production is easily determined for this optimal seed loading condition by the aid of a simple mass balance.
-
effect of cooling mode on product crystal size in seeded batch crystallization of Potassium Alum
Chemical Engineering Journal, 2001Co-Authors: Norihito Doki, Noriaki Kubota, Akira Sato, Masaaki YokotaAbstract:Potassium Alum was crystallized by seeding in a batch crystallizer under controlled and natural cooling modes. Regardless of the cooling mode, the product crystal size distribution (CSD) became bi-modal at low seed concentrations because of enormous secondary nucleation. The mean mass size of the product was smaller for the natural cooling mode compared to that for the controlled cooling mode with more intensive secondary nucleation. On the other hand, at high seed concentrations, the product CSD became uni-modal with the same mean mass size for both cooling modes, where the crystallization was dominated by seed growth. The low supersaturation caused by the growth of enough seeds plays a key role to produce uni-modal size distribution with suppressed nucleation. Adhering of small crystals (secondary nuclei) to growing seed crystals is also considered to be another mechanism for generating uni-modal CSD.
-
scaleup experiments on seeded batch cooling crystallization of Potassium Alum
Aiche Journal, 1999Co-Authors: Norihito Doki, Noriaki Kubota, Akira Sato, Masaaki Yokota, Osamu Hamada, Fumio MasumiAbstract:Potassium Alum was crystallized by natural cooling in two well-mixed laboratory-scale (12.2 L) and pilot-scale (600 L) crystallizers. When unimodal product crystals of grown seeds were used, no scaleup effect on product crystal-size distribution (CSD) was observed if enough seeds were loaded over a critical seed concentration. Cooling rate, crystal yield (crystal suspension density), and stirring condition do not seriously affect the product CSD under such a seeding condition. Low supersaturation peak caused by the growth of enough seeds, the short period of nucleation, and the agglomeration of nuclei to the growing seed crystals are considered to be mechanisms working to produce unimodal product crystals of grown seeds. Simple design calculations are demonstrated to determine the amount of seed with the help of a critical seed concentration, which can be determined easily from laboratory-scale experiments. Crystallizer volume was calculated simply from a mass balance.
Akira Sato - One of the best experts on this subject based on the ideXlab platform.
-
effect of cooling mode on product crystal size in seeded batch crystallization of Potassium Alum
Chemical Engineering Journal, 2001Co-Authors: Norihito Doki, Noriaki Kubota, Akira Sato, Masaaki YokotaAbstract:Potassium Alum was crystallized by seeding in a batch crystallizer under controlled and natural cooling modes. Regardless of the cooling mode, the product crystal size distribution (CSD) became bi-modal at low seed concentrations because of enormous secondary nucleation. The mean mass size of the product was smaller for the natural cooling mode compared to that for the controlled cooling mode with more intensive secondary nucleation. On the other hand, at high seed concentrations, the product CSD became uni-modal with the same mean mass size for both cooling modes, where the crystallization was dominated by seed growth. The low supersaturation caused by the growth of enough seeds plays a key role to produce uni-modal size distribution with suppressed nucleation. Adhering of small crystals (secondary nuclei) to growing seed crystals is also considered to be another mechanism for generating uni-modal CSD.
-
scaleup experiments on seeded batch cooling crystallization of Potassium Alum
Aiche Journal, 1999Co-Authors: Norihito Doki, Noriaki Kubota, Akira Sato, Masaaki Yokota, Osamu Hamada, Fumio MasumiAbstract:Potassium Alum was crystallized by natural cooling in two well-mixed laboratory-scale (12.2 L) and pilot-scale (600 L) crystallizers. When unimodal product crystals of grown seeds were used, no scaleup effect on product crystal-size distribution (CSD) was observed if enough seeds were loaded over a critical seed concentration. Cooling rate, crystal yield (crystal suspension density), and stirring condition do not seriously affect the product CSD under such a seeding condition. Low supersaturation peak caused by the growth of enough seeds, the short period of nucleation, and the agglomeration of nuclei to the growing seed crystals are considered to be mechanisms working to produce unimodal product crystals of grown seeds. Simple design calculations are demonstrated to determine the amount of seed with the help of a critical seed concentration, which can be determined easily from laboratory-scale experiments. Crystallizer volume was calculated simply from a mass balance.
Fumio Masumi - One of the best experts on this subject based on the ideXlab platform.
-
scaleup experiments on seeded batch cooling crystallization of Potassium Alum
Aiche Journal, 1999Co-Authors: Norihito Doki, Noriaki Kubota, Akira Sato, Masaaki Yokota, Osamu Hamada, Fumio MasumiAbstract:Potassium Alum was crystallized by natural cooling in two well-mixed laboratory-scale (12.2 L) and pilot-scale (600 L) crystallizers. When unimodal product crystals of grown seeds were used, no scaleup effect on product crystal-size distribution (CSD) was observed if enough seeds were loaded over a critical seed concentration. Cooling rate, crystal yield (crystal suspension density), and stirring condition do not seriously affect the product CSD under such a seeding condition. Low supersaturation peak caused by the growth of enough seeds, the short period of nucleation, and the agglomeration of nuclei to the growing seed crystals are considered to be mechanisms working to produce unimodal product crystals of grown seeds. Simple design calculations are demonstrated to determine the amount of seed with the help of a critical seed concentration, which can be determined easily from laboratory-scale experiments. Crystallizer volume was calculated simply from a mass balance.