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Simulation of solids processes accounting for particle size distribution
Solids processing is prevalent throughout the chemical manufacturing industry and includes any process which produces solid products or uses solids processing steps such as crushing, crystallization, dissolution, or filtration. One unique feature of a solids process is that each solids stream is characterized by its particle size distribution (PSD), shape, habit, internal porosity and mechanical strength as well as other attributes such as composition and temperature. Because of these added complexities, there is an absence of adequate tools for the design of solids processes. Recent surveys indicate that solids plants perform poorly compared to vapor-liquid plants and the need for improvements in solids processing technologies is now widely recognized. The objective of this research is to develop a comprehensive design framework for the simulation of solids plants. Emphasis is placed on accounting for the evolution of the PSD as a material stream is processed by each equipment unit. A key component is a new set of discretized population balance equations (PBEs) which account for such changes due to the basic mechanisms of nucleation, growth, dissolution, agglomeration, and breakage. This new approach is compatible with the data structure of large-scale simulation codes, correctly predicts changes in both the total mass and the total number of particles simultaneously, allows modeling of an equipment unit by combining the basic mechanisms appropriate for that unit, and is flexible in that it allows the user to choose equal or geometric size intervals for discretization. With this framework, models for various units of solids processing equipment are formulated and linked together to simulate a solids process. Specific industrial examples, such as the production of alumina, are used to demonstrate the effects of the PSD on an entire process as well as on process subsystems. This new tool provides more accurate predictions of plant performance and significantly better estimates of equipment size than models which ignore the PSD. Based on these simulation results, insights for plant retrofit are identified.
Chemical engineering|Mechanical engineering
Hill, Priscilla June, "Simulation of solids processes accounting for particle size distribution" (1996). Doctoral Dissertations Available from Proquest. AAI9619395.