Progress, problems, and potential of technology for measuring solution concentration in crystallization processes

Measuring the solution concentration of processes for product quality control in industrial crystallization processes is a hot topic. In recent years, with the development of process analysis technology, various innovative measurement technologies for different situations and operating conditions have been developed. This paper systematically reviews the research on various solution concentration measurement technologies that have been developed for the crystallization process. These measurement technologies are divided into off-line, at-line, on-line, and in-situ methods based on their measurement modes and principles. The measurement principle, advantages, disadvantages, application field, and development status of each of the existing measurement technologies are illustrated in detail, with a particular focus on measurement methods based on spectroscopy technology, which are very popular for crystallization processes. In addition, this paper presents the problems of solution concentration measurement technology and points out future research directions.