The main goal of this paper is to model a multiphase flow of a monodispersed suspensions in vario... more The main goal of this paper is to model a multiphase flow of a monodispersed suspensions in various types of crystallizers: Draft Tube Magma (DTM), Double Draft Tube (DDT) and Fluidized bed (FL). To do this, the CFD (Computational Fluid Dynamics) methods were used. The geometry of model apparatus was similar to those applied in industry. The composition of suspensions and their physical properties were the same as in practical cases. The computations showed that axial velocity distribution in the investigated types of crystallizers were far from optimal. In each case backward circulation loops have been observed.
Streszczenie W artykule omówiono ilościowe i jakościowe rozpoznanie najistotniejszych zagadnień, ... more Streszczenie W artykule omówiono ilościowe i jakościowe rozpoznanie najistotniejszych zagadnień, niezbędnych przy projektowaniu nowych instalacji przemysłowych, w przypadku, kiedy nie dysponujemy danymi ruchowymi z innych podobnych technologicznie układów. Jako przykład wykorzystano instalację do produkcji krystalicznego siarczanu amonu przeznaczonego dla rolnictwa. Surowcem do produkcji był roztwór (zawiesina) siarczanu amonu powstała w procesie odsiarczania spalin metodą amoniakalną. Wdrożona technologia umożliwia produkcję 60 tys. t/r nawozowego siarczanu amonu spełniającego Dyrektywę Unijną nr 1107/2008, z dnia 07.11.2008 Słowa kluczowe: krystalizacja przemysłowa, siarczan amonu, FGD, CFD
The scale-up problem of crystallization process is a difficult task. The commonly used in mixing ... more The scale-up problem of crystallization process is a difficult task. The commonly used in mixing tanks criteria of e.g. constant unit power input or tip speed together w ith geometrical similarity fail. In this paper the relaxation of geometrical s imilarity of crystallizers by considering different width of gap between the draft tube and the propell er was presented. The Computational Fluid Dynamics was used to investigate four volumes of th e tank. The primary circulation time (PCT) was chosen as the representative parameter to describe obtained results. In each scale the optimal width o f gap, in which the value of PCT was the smallest, wa s determined. From kinetic point of view PCT should not change with scale or even it should decr ease. Having that in mind the other ways to decrease the PCT value by relaxing geometrical simi arity should be investigated.
The presented study is focused on the possibilities of precipitation process intensification by m... more The presented study is focused on the possibilities of precipitation process intensification by means of processing conditions and the selection of a crystallizer construction. The main goal was to consciously intensify the precipitation and to obtain crystals with the defined characteristics. The research took into account the CaF2 precipitation. The process was carried out in a tank reactor placed in an ultrasonic bath to increase the turbulence intensity (PUS = 150 W, f = 40 kHz). The results were compared with the previous tests, provided in silent conditions in a stirred tank reactor, Koflo, and Kenics static mixers. For the comparison of measurement data obtained under different operating conditions, a new method was proposed. The method correlates with the results very well. It has been also shown that the use of ultrasounds does not contribute to the increase of the precipitation efficiency but allows to obtain a product with a decreased particle size together with a signifi...
Abstract On the basis of the CaF2 precipitation, the influence of a reactor construction on the o... more Abstract On the basis of the CaF2 precipitation, the influence of a reactor construction on the obtained solid product characteristics and the reaction efficiency has been analyzed. For experiments a tank reactor with a mechanical stirrer and two in-line reactors Kenics and Koflo static mixers were used. For the description of flow conditions, the definition of the equivalent Reynolds number Reeqv, based, among others, on the local unit dissipation energy e, has been introduced. According to the provided study, it was found, that in the tank reactor with stirrer the obtained solid product was present in the agglomerated form, where the size of each particular grain did not exceed 2.5 μm. The shape of the obtained particles was close to the sphere with the volume shape factor kv = 0.812. The precipitation of CaF2 in static mixers resulted in obtaining plate-shaped single crystals (kv = 0.347–0.943), where the agglomeration phenomenon was negligible, and where the mean particle size was in the range of 10–275 μm depending on fluid dynamic conditions. If it is about the reaction efficiency, the conversion rate in both types of reactors was at a very high level (η > 98%), however, the tank reactor showed a higher efficiency. To conclude, tank reactors are applicable when a very high conversion rate is desirable, when the agglomerated entity is acceptable and when the residence time should be selected in an individual way. If larger crystals with a negligible contribution of agglomerates are of order, static reactors become irreplaceable.
In the process industry the use of static mixers is constantly rising. Notwithstanding, due to th... more In the process industry the use of static mixers is constantly rising. Notwithstanding, due to the multitude of available types, the selection of a proper construction is not as simple and requires the knowledge of complete description of a device. In the performed research there was an attempt to present the complete fluid-dynamic characteristics of two static mixers: Kenics – well known and commonly used and Koflo – which has not yet been described in the relevant literature. The empty pipe was also studied as a background for comparison. However, according to the huge amount of gathered data, the report was divided into separate parts, dedicated to pressure drops, residence time distributions and mixture homogeneity, respectively. The presented paper is focused on the pressure drop analysis which contains the experimental study, the validation of the obtained data on the basis of manufacturer’s correlations as so as computational values and the presentation of new pressure drop relations that enable the pressure drop predictions from Eu or Ne number. As a result of the accomplished study, a good accuracy between the values calculated form given equations and those achieved in the experimental manner was confirmed. It was also showed that due to smaller energy consumption Koflo static mixer can be successfully used instead of Kenics. What is more, the presented report clearly states that static mixers require a huge power demand which leads to the increased maintenance costs and that information should be considered during the system design. This article is protected by copyright. All rights reserved
In the process industry the use of static mixers is constantly rising. Notwithstanding, due to th... more In the process industry the use of static mixers is constantly rising. Notwithstanding, due to the multitude of available types, the selection of a proper construction is not as simple and requires the knowledge of complete description of a device. In the performed research there was an attempt to present the complete fluid-dynamic characteristics of two static mixers: Kenics – well known and commonly used and Koflo – which has not yet been described in the relevant literature. The empty pipe was also studied as a background for comparison. However, according to the huge amount of gathered data, the report was divided into separate parts, dedicated to pressure drops, residence time distributions and mixture homogeneity, respectively. The presented paper is focused on the pressure drop analysis which contains the experimental study, the validation of the obtained data on the basis of manufacturer’s correlations as so as computational values and the presentation of new pressure drop relations that enable the pressure drop predictions from Eu or Ne number. As a result of the accomplished study, a good accuracy between the values calculated form given equations and those achieved in the experimental manner was confirmed. It was also showed that due to smaller energy consumption Koflo static mixer can be successfully used instead of Kenics. What is more, the presented report clearly states that static mixers require a huge power demand which leads to the increased maintenance costs and that information should be considered during the system design. This article is protected by copyright. All rights reserved
The paper deals with a new method of utilization of the spent liquid from common salt plant. That... more The paper deals with a new method of utilization of the spent liquid from common salt plant. That brine is utilized by means of another liquid waste from the ammonia soda production. The experimental work was focused on the kinetics of the crystallization with chemical reaction as well as on the maximum decreasing possibility of sulfates concentration in the solution, with simultaneously preserving the possible high level of chloride concentration in liquid and forming well-filtrated suspension, respectively. It was found that hydraulic conditions in apparatus and supersaturation of solution weakly affect reduction of the primary nucleation rate. The best results have been obtained when the (i) reactants feed was close to the surface of solution, (ii) mean power input was below 0.35 W/kg, and (iii) mass ratio excess of mass precipitating agent was below 60%. Based on the collected data, a technological concept of spent liquid utilization for industry purposes has been worked out. The proposed solution red...
The paper is focused on (i) kinetics of trioxane vacuum crystallization from solution in differen... more The paper is focused on (i) kinetics of trioxane vacuum crystallization from solution in different apparatus volumes, (ii) vapour–liquid equilibrium and (iii) crystals hardness versus process temperature. It has been found that trioxane is a well-crystallized substance with relatively high effective growth rate and, simultaneously, to some extent, crystals are resistant to attrition. Unfortunately, their elongated shape promotes breaking in
T his paper deals with the effect of draft tube shape on pumping capacity, as well as power input... more T his paper deals with the effect of draft tube shape on pumping capacity, as well as power input in a typical crystallizer with inner suspension circulation forced by means of propeller. The common theoretical relationship between the main factors affecting pumping capacity has been derived. Four types of draft tubes were considered including cylindrical and conical-cylindrical draft tube with inner and outer baf es. The investigations substantiating the theoretical considerations, were carried out for a wide range of independent variables: unit power input 0.1-1.5 W kg ¡1 ; d r =d m ratio 0.8-0.95; h r =d r ratio 0.15-0.6. The experimental data proved to be consistent with the theoretical predictions. The results make it possible to determine the best shape and the optimum location of the draft tube in the apparatus for generating the maximum pumping effect at minimum power input.
The main goal of this paper is to model a multiphase flow of a monodispersed suspensions in vario... more The main goal of this paper is to model a multiphase flow of a monodispersed suspensions in various types of crystallizers: Draft Tube Magma (DTM), Double Draft Tube (DDT) and Fluidized bed (FL). To do this, the CFD (Computational Fluid Dynamics) methods were used. The geometry of model apparatus was similar to those applied in industry. The composition of suspensions and their physical properties were the same as in practical cases. The computations showed that axial velocity distribution in the investigated types of crystallizers were far from optimal. In each case backward circulation loops have been observed.
Streszczenie W artykule omówiono ilościowe i jakościowe rozpoznanie najistotniejszych zagadnień, ... more Streszczenie W artykule omówiono ilościowe i jakościowe rozpoznanie najistotniejszych zagadnień, niezbędnych przy projektowaniu nowych instalacji przemysłowych, w przypadku, kiedy nie dysponujemy danymi ruchowymi z innych podobnych technologicznie układów. Jako przykład wykorzystano instalację do produkcji krystalicznego siarczanu amonu przeznaczonego dla rolnictwa. Surowcem do produkcji był roztwór (zawiesina) siarczanu amonu powstała w procesie odsiarczania spalin metodą amoniakalną. Wdrożona technologia umożliwia produkcję 60 tys. t/r nawozowego siarczanu amonu spełniającego Dyrektywę Unijną nr 1107/2008, z dnia 07.11.2008 Słowa kluczowe: krystalizacja przemysłowa, siarczan amonu, FGD, CFD
The scale-up problem of crystallization process is a difficult task. The commonly used in mixing ... more The scale-up problem of crystallization process is a difficult task. The commonly used in mixing tanks criteria of e.g. constant unit power input or tip speed together w ith geometrical similarity fail. In this paper the relaxation of geometrical s imilarity of crystallizers by considering different width of gap between the draft tube and the propell er was presented. The Computational Fluid Dynamics was used to investigate four volumes of th e tank. The primary circulation time (PCT) was chosen as the representative parameter to describe obtained results. In each scale the optimal width o f gap, in which the value of PCT was the smallest, wa s determined. From kinetic point of view PCT should not change with scale or even it should decr ease. Having that in mind the other ways to decrease the PCT value by relaxing geometrical simi arity should be investigated.
The presented study is focused on the possibilities of precipitation process intensification by m... more The presented study is focused on the possibilities of precipitation process intensification by means of processing conditions and the selection of a crystallizer construction. The main goal was to consciously intensify the precipitation and to obtain crystals with the defined characteristics. The research took into account the CaF2 precipitation. The process was carried out in a tank reactor placed in an ultrasonic bath to increase the turbulence intensity (PUS = 150 W, f = 40 kHz). The results were compared with the previous tests, provided in silent conditions in a stirred tank reactor, Koflo, and Kenics static mixers. For the comparison of measurement data obtained under different operating conditions, a new method was proposed. The method correlates with the results very well. It has been also shown that the use of ultrasounds does not contribute to the increase of the precipitation efficiency but allows to obtain a product with a decreased particle size together with a signifi...
Abstract On the basis of the CaF2 precipitation, the influence of a reactor construction on the o... more Abstract On the basis of the CaF2 precipitation, the influence of a reactor construction on the obtained solid product characteristics and the reaction efficiency has been analyzed. For experiments a tank reactor with a mechanical stirrer and two in-line reactors Kenics and Koflo static mixers were used. For the description of flow conditions, the definition of the equivalent Reynolds number Reeqv, based, among others, on the local unit dissipation energy e, has been introduced. According to the provided study, it was found, that in the tank reactor with stirrer the obtained solid product was present in the agglomerated form, where the size of each particular grain did not exceed 2.5 μm. The shape of the obtained particles was close to the sphere with the volume shape factor kv = 0.812. The precipitation of CaF2 in static mixers resulted in obtaining plate-shaped single crystals (kv = 0.347–0.943), where the agglomeration phenomenon was negligible, and where the mean particle size was in the range of 10–275 μm depending on fluid dynamic conditions. If it is about the reaction efficiency, the conversion rate in both types of reactors was at a very high level (η > 98%), however, the tank reactor showed a higher efficiency. To conclude, tank reactors are applicable when a very high conversion rate is desirable, when the agglomerated entity is acceptable and when the residence time should be selected in an individual way. If larger crystals with a negligible contribution of agglomerates are of order, static reactors become irreplaceable.
In the process industry the use of static mixers is constantly rising. Notwithstanding, due to th... more In the process industry the use of static mixers is constantly rising. Notwithstanding, due to the multitude of available types, the selection of a proper construction is not as simple and requires the knowledge of complete description of a device. In the performed research there was an attempt to present the complete fluid-dynamic characteristics of two static mixers: Kenics – well known and commonly used and Koflo – which has not yet been described in the relevant literature. The empty pipe was also studied as a background for comparison. However, according to the huge amount of gathered data, the report was divided into separate parts, dedicated to pressure drops, residence time distributions and mixture homogeneity, respectively. The presented paper is focused on the pressure drop analysis which contains the experimental study, the validation of the obtained data on the basis of manufacturer’s correlations as so as computational values and the presentation of new pressure drop relations that enable the pressure drop predictions from Eu or Ne number. As a result of the accomplished study, a good accuracy between the values calculated form given equations and those achieved in the experimental manner was confirmed. It was also showed that due to smaller energy consumption Koflo static mixer can be successfully used instead of Kenics. What is more, the presented report clearly states that static mixers require a huge power demand which leads to the increased maintenance costs and that information should be considered during the system design. This article is protected by copyright. All rights reserved
In the process industry the use of static mixers is constantly rising. Notwithstanding, due to th... more In the process industry the use of static mixers is constantly rising. Notwithstanding, due to the multitude of available types, the selection of a proper construction is not as simple and requires the knowledge of complete description of a device. In the performed research there was an attempt to present the complete fluid-dynamic characteristics of two static mixers: Kenics – well known and commonly used and Koflo – which has not yet been described in the relevant literature. The empty pipe was also studied as a background for comparison. However, according to the huge amount of gathered data, the report was divided into separate parts, dedicated to pressure drops, residence time distributions and mixture homogeneity, respectively. The presented paper is focused on the pressure drop analysis which contains the experimental study, the validation of the obtained data on the basis of manufacturer’s correlations as so as computational values and the presentation of new pressure drop relations that enable the pressure drop predictions from Eu or Ne number. As a result of the accomplished study, a good accuracy between the values calculated form given equations and those achieved in the experimental manner was confirmed. It was also showed that due to smaller energy consumption Koflo static mixer can be successfully used instead of Kenics. What is more, the presented report clearly states that static mixers require a huge power demand which leads to the increased maintenance costs and that information should be considered during the system design. This article is protected by copyright. All rights reserved
The paper deals with a new method of utilization of the spent liquid from common salt plant. That... more The paper deals with a new method of utilization of the spent liquid from common salt plant. That brine is utilized by means of another liquid waste from the ammonia soda production. The experimental work was focused on the kinetics of the crystallization with chemical reaction as well as on the maximum decreasing possibility of sulfates concentration in the solution, with simultaneously preserving the possible high level of chloride concentration in liquid and forming well-filtrated suspension, respectively. It was found that hydraulic conditions in apparatus and supersaturation of solution weakly affect reduction of the primary nucleation rate. The best results have been obtained when the (i) reactants feed was close to the surface of solution, (ii) mean power input was below 0.35 W/kg, and (iii) mass ratio excess of mass precipitating agent was below 60%. Based on the collected data, a technological concept of spent liquid utilization for industry purposes has been worked out. The proposed solution red...
The paper is focused on (i) kinetics of trioxane vacuum crystallization from solution in differen... more The paper is focused on (i) kinetics of trioxane vacuum crystallization from solution in different apparatus volumes, (ii) vapour–liquid equilibrium and (iii) crystals hardness versus process temperature. It has been found that trioxane is a well-crystallized substance with relatively high effective growth rate and, simultaneously, to some extent, crystals are resistant to attrition. Unfortunately, their elongated shape promotes breaking in
T his paper deals with the effect of draft tube shape on pumping capacity, as well as power input... more T his paper deals with the effect of draft tube shape on pumping capacity, as well as power input in a typical crystallizer with inner suspension circulation forced by means of propeller. The common theoretical relationship between the main factors affecting pumping capacity has been derived. Four types of draft tubes were considered including cylindrical and conical-cylindrical draft tube with inner and outer baf es. The investigations substantiating the theoretical considerations, were carried out for a wide range of independent variables: unit power input 0.1-1.5 W kg ¡1 ; d r =d m ratio 0.8-0.95; h r =d r ratio 0.15-0.6. The experimental data proved to be consistent with the theoretical predictions. The results make it possible to determine the best shape and the optimum location of the draft tube in the apparatus for generating the maximum pumping effect at minimum power input.
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