(626d) Workflow for the Design of Seeding Application in Batch Crystallization

A workflow procedure that guides the decision making for seeding application in batch crystallization is presented to facilitate the production of crystals of desired quality, which include mean crystal size, crystal size distribution, crystalline state and impurity level. Such a workflow is embedded in the framework related to the design of a complete crystallization-based process. As a basis for decision-making in the workflow, the effect of seed production method on seed quality and how such seed quality affects the crystallization operation and the product quality are first summarized and presented in the form of a causal table, which is made according to experimental results and model-based simulations from literature. The developed workflow consists of three major steps. The first step involves the definition of process objectives and gathering of relevant thermodynamic and kinetic information of the system. In the second part, preliminary experiments are performed for seed preparation and for determining the safe operating region of the seeding application. A model equation is also used to calculate the optimum seed mass for a given seed size, based on which seeded batch crystallization are then conducted to produce crystals. The quality of such crystals is evaluated in the last step with the target values. If the objectives are not met, the seed quality is changed repeatedly with the aid of causal table and model equation such that product crystals of desired quality are finally obtained. Two selected binary systems, succinic acid-water and paracetamol-water, are used to illustrate the workflow.