Heat Transfer Based Scale-Down of Chemical Reactions

Abstract

Mathematical models of dose controlled reactions based on heat flow data(1, 2) are quite common and well developed; however, such predictions for nondose controlled reactions from heat flow data are difficult, requiring extensive study of the kinetics of multiple chemical transformations as well as physical phenomena such as dissolution and diffusion. Presented here is a new scale-down methodology to directly observe, in the laboratory, a variety of dose controlled and nondose controlled large scale thermal effects. This experiment-based scale-down approach has been derived mathematically from first principles, as well as demonstrated experimentally. This approach limits the heat transfer of the laboratory reactor to the scale equivalent of the intended large scale vessel by dynamic jacket set points based on the ratio of the heat transfer coefficients of lab and plant scale reactors. This allows large scale reaction temperature and other temperature-related effects to be mimicked on small scale while maintaining the time/reaction temperature response profile of the large scale vessel in the laboratory. The result is a method for the direct observation, in the laboratory, of the scale-up effects of changing a wide range of process variables for both dose controlled and non-dose controlled systems. Applications for this methodology could include evaluating the effects of proposed large scale process changes on process safety, product purity, or product physical properties as well as evaluating the effects of failure scenarios.