Cooling crystallization of ammonium persulfate in a crystallizer with a pseudo-fluidized layer
Abstract
The expediency of using classifying crystallizers for obtaining a coarse-crystalline product with a homogeneous granulometric composition is substantiated. At the same time, it is noted that in this type of crystallization equipment, under conditions of controlled supersaturation, along with the process of crystal growth in the upward flow of the solution, their hydraulic classification by size takes place. Based on the literature analysis, the purpose and tasks of this work, which consist in conducting experimental studies and identifying the main factors affecting the process of crystallization of ammonium persulfate in a fluidized bed, as well as in developing a method for calculating the cooling classifying crystallizer in the production of ammonium persulfate, are formulated. The method of mathematical processing of experimental results, which is based on a dynamic model of the hydroclassification process and crystal growth in a cylindroconical classifying crystallizer. is described At the same time, it is proposed to consider the entire volume of the fluidized bed of crystals divided into a finite number of narrow monofractions, each of which is characterized by certain hydrodynamic and mass transfer parameters. The results of experimental studies and their mathematical processing according to the appropriate method present the determination of the main characteristics of the process of crystallization of ammonium persulfate in a fluidized bed, namely: the average equivalent diameter of the monofraction and polydisperse mixture of crystals, the local porosity of the fluidized bed of crystals, the speed of movement of the solution in the local free section of the crystal grower and the speed of free precipitation of crystals, the average supersaturation of the solution in the fluidized bed, the average and local surface and volume mass transfer coefficients, the expected yield of crystals upon complete removal of the supersaturation of the solution, as well as the average size of the resulting crystals. During the discussion of the research results, it was noted that solutions of ammonium persulfate and ammonium sulfate are moderately stable, which, under the conditions of low controlled supersaturation of the solution and the presence of a sufficient mass of the fluidized bed, allows them to be used in classifying crystallizers to obtain a large-crystalline classified product of good quality
Keywords
classifying crystallizer; crystals; solution supersaturation; hydroclassification; mass transfer
References
[1] Handbook of Industrial Crystallization, 3rd ed., Allan S. Myerson, Massachusetts Institute of Technology, Deniz Erdemir, BristolMyers Squibb, USA, Alfred Y. Lee, Merck & Co., Inc., Eds. Cambridge University Press, 2019. doi: 10.1017/9781139026949.
[2] S. Y. Misyura, and V. S. Morozov, "Crystallization of salt solutions on surface of droplet and layer", J. Eng. Thermophys., no. 28, pp. 381-391, 2019. doi: 10.1134/S1810232819030081.
[3] D. A. Weingaertner, S. Lynn, and D. N. Hanson, "Extractive crystallization of salts from concentrated aqueous solution", Ind. Eng. Chem. Res., vol. 30, iss. 3, pp. 490-501, 1991. doi: 10.1021/ie00051a009.
[4] H. Svanoe, "Krystal" classifying crystallizer", Ind. Eng. Chem., vol. 32, iss. 5, рр. 636639, 1940. doi: 10.1021/ie50365a011.
[5] J. W. Mullin, "Crystallizer design and operation", in Industrial Crystallization, J. W. Mullin, Ed. Springer, Boston, MA., рр. 291-302, 1976. doi: 10.1007/978-1-4615-7258-9_28.
[6] C. D. Han, and R. Shinnar, "The steady state behavior of crystallizers with classified product removal", AIChE Journal, vol. 14, iss. 4, pp. 612-619, 1968. doi: 10.1002/aic.690140413.
[7] A. P. Vragov, "Simulating and designing cylinder-cone classifying crystallizers", Chem. Petrol Eng., no. 35, pp. 189-198, 1999. doi: 10.1007/BF02368679.
[8] C. Frances, B. Biscans, and C. Laguerie, "Modelling of a continuous fluidized-bed crystallizer effects of mixing and segregation on crystal size distribution during the crystallization of tetrahydrate sodium perborate", Chem. Eng. Science, vol. 49, iss. 19, pp. 3269-3276, 1994. doi: 10.1016/0009-2509(94)00135-9.
[9] E. Temmel, J. Gänsch, A. SeidelMorgenstern, and H. Lorenz, "Systematic investigations on continuous fluidized bed crystallization for chiral separation", Crystals, vol. 10, no. 394, 2020. doi: 10.3390/cryst10050394.
[10] K. Shimamura, T. Tanaka, Y. Miura, and H. Ishikawa, "Development of a highefficiency phosphorus recovery method using a fluidized-bed crystallized phosphorus removal system", Water Science and Technology, vol. 48, no. 1, pp. 163-170, 2003.
[11] D. Binev, A. Seidel-Morgenstern, and H. Lorenz, "Continuous separation of isomers in fluidized bed crystallizers", Cryst. Growth Des., vol. 16, no. 3, pp. 1409-1419, 2016. doi: 10.1021/acs.cgd.5b01513.
[12] C. Y. Tai, Ch.-Yu Chen, and J.-F. Wu, "Сrystal dissolution and growth in a lean fluidized bed crystallizer", Chem. Eng. Communications, vol. 56, iss. 1-6, pp. 329340, 1987. doi: 10.1080/00986448708911953.
[13] D. Zheng, W. Zou, J. Yan et al., "Coupling of contact nucleation kinetics with breakage model for crystallization of sodium chloride crystal in fluidized bed crystallizer", Journal of Chemistry, vol. 2019, pp. 1-11, 2019. doi: 10.1155/2019/2150560.
[14] C. Y. Taia, P. C. Chenb, and T. M. Tsao, "Growth kinetics of CaF2 in a pH-stat fluidized-bed crystallizer", Journal of Crystal Growth, vol. 290, iss. 2, pp. 576-584, 2006. doi: 10.1016/j.jcrysgro.2006.02.036.
[15] C. Bartscha, V. Wiedmeyer, Z. Lakdawala et al., "Stochastic-deterministic population balance modeling and simulation of a fluidized bed crystallizer experiment", Chem. Eng. Science, vol. 208, no. 115102, 2019. doi: 10.1016/j.ces.2019.07.020.
[16] Ja. E. Mikhajlovskiy, "Dynamics of the crystallization process in a cylindroconical classifying crystallizer", Ph.D. thesis, Vyd-vo SumDU, Sumy, 1999 [in Ukrainian].
[17] Fluidization, J. F. Davidson, and D. Harrison, Eds, Moscow, Russia: Khimiia, 1974 [in Russian].
[18] A. P. Vragov, Design and calculation of crystallization plants with classifying molds. Kiev, Ukraine: UMK VO, 1988 [in Russian].
[19] A. P. Vragov, Zhurn. prykl. khimiyi, vol. 60, no. 9, pp. 2007-2019, 1987 [in Russian].