The saturated solutions were prepared with the addition of analytical grade substances and distilled water. Based on the above arguments, the aim was to investigate the influence of particle size and suspension density on the ultrasound measurement.Įxperiments were conducted using NaCl, K 2SO 4, KNO 3, and MgSO 4 *7H 2O. In order to use the ultrasound technique in industrial crystallizers, the relationship between the ultrasonic velocity and particle size and/or solid concentration must be known. On the other hand, there is no report on the use of ultrasonic velocity in high suspended systems in crystallization. This effect is known as scattering effect and it can be a limiting factor for some ultrasound applications. Variation in factors such as particle size and solid concentration can have a significant effect on the measurements. Because there can be some problems concerning the correct measurements of concentration in multiphase systems by using the ultrasound technique. However, little of this information is of a direct use in the operation of industrial crystallizers.
Recently several workers have also investigated the validity of using ultrasonic methods to determine the concentration of solution and the metastable width of some inorganic salts in aqueous solutions. The ultrasound technique has been known since 1930 and this phenomena has been used for characterization of emulsions, colloids, and creaming systems. This technique measures either the ultrasonic velocity or attenuation coefficient of material and then uses empirical or theoretical equations to convert the ultrasonic parameters in to concentration profiles. The ultrasound velocity technique is an ideal technique for monitoring of a mass transfer processes. Therefore, it is not possible to determine the concentration of solutions with the technique that have been developed for optically transparent. Because, crystallization processes involves the production or use of the suspension and all of these system are usually optically opaque systems. But, almost all of them do not permit continuous measurements of concentration in the crystallization systems.
Up to now many different methods have been developed to determine the concentration of electrolyte solutions. One of the major problems in industrial crystallization is the on-line measurement of concentration.
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