Jens Uwe Rapke

Bio: Jens Uwe Rapke is an academic researcher from Technical University of Berlin. The author has contributed to research in topics: Crystallization & Population balance equation. The author has an hindex of 1, co-authored 1 publications receiving 11 citations.

Modelling of crystallization process and optimization of the cooling strategy

Abstract: To obtain a uniform and large crystal in seeded batch cooling crystallization, the cooling strategy is very important. In this study, an optimal cooling strategy is obtained through simulation and compared to linear and natural cooling strategies. A model for a crystallization process in a batch reactor is constructed by using population balance equation and material balance for solution concentration, and a prediction model for meta-stable limit is formulated by the dynamic meta-stable limit approach. Based on this model, an optimal cooling strategy is obtained using genetic algorithm with the objective function of minimizing the unwanted nucleation and maximizing the crystal growth rate. From the simulation results, the product from the optimal cooling strategy showed uniform and large crystal size distribution while products from the other two strategies contained significant amount of fine particles.

Model-Based Systematic Design and Analysis Approach for Unseeded Combined Cooling and Antisolvent Crystallization (CCAC) Systems

Abstract: A novel model-based systematic analysis and design approach for unseeded combined cooling and antisolvent crystallization (CCAC) processes has been proposed and evaluated for the crystallization of aspirin in ethanol–water mixture. The approach can be easily implemented in practice using automated lab reactors, and gives the optimal times for the start of a linear cooling profile or constant antisolvent addition rate. According to the proposed analysis, based on the sensitivity of the solubility surface, the simplified operating procedures should either belong to cooling first or antisolvent first strategy, depending on whether the initial solution locates at temperature sensitive region or antisolvent concentration sensitive region. The proposed approach can be used to produce operating surfaces based on which the performance of combined cooling and antisolvent crystallization systems can be understood and operating strategies rapidly designed depending on the initial concentration, solvent composition a...

Solubility Measurement and Thermodynamic Modeling of Benzoic Acid in Monosolvents and Binary Mixtures

Abstract: The solid–liquid equilibrium of benzoic acid has been determined in six monosolvents—tributyl phosphate, diacetone alcohol, methyl-n-propyl ketone, methyl acetate, amyl acetate, and isooctane—at temperatures from 283.15 to 328.15 K and five binary systems—ethanol + hexane (288.15–328.15 K), isopropyl alcohol + hexane and chloroform + hexane (288.15–323.15 K), acetone + hexane (288.15–318.15 K), and acetone + water (288.15–318.15 K)—at atmospheric pressure with varying mole fraction of the binary mixture. The solubility was estimated by three different methods—titrimetry, gravimetry, and high-pressure liquid chromatography methods. The solubility of benzoic acid was found to increase with an increase in temperature and mole fraction. Experimental solubility data was correlated with various thermodynamic models such as the Buchowski equation, the NRTL model, and the modified Apelblat–Jouyban–Acree model. The mathematical models demonstrated that the calculated and experimental solubilities of benzoic acid i...

Impact of seed loading ratio on the growth kinetics of mono-ammonium phosphate under isothermal batch crystallization

Abstract: The effect of seed load ratio on the growth kinetics of Mono-ammonium phosphate (MAP) under isothermal batch crystallization was investigated quantitatively. A direct parameter estimation method was proposed and applied to extract the growth kinetic parameters from a simple crystallization model using our experimental solution concentration decline data. The method assured the globally best parameters to be obtained and was found less sensitive to experimental errors. The linear growth constants k g and the growth order g were found to be in the range of 1,000-2,600 μm·min−1 and 0.93-1.12, respectively, for MAP crystallized at 40 °C. Both parameters decreased significantly with increase of seed load ratio and k g even showed a strong linear decline trend. The effective crystallization time also decreased with the seed mass. The proposed methodology could be extended to study the effect of other operation variables such as temperature and initial supersaturation on the crystal growth rate.