(95a) Applying Computational Fluid Dynamics (CFD) Modeling to Improve the Para-Xylene (PX) Crystallization Process

In this paper, computational fluid dynamics (CFD) modeling is employed to study the fluid dynamics and heat transfer in BP's PX crystallizers. Due to the low mean velocity through the crystallizer and external cooling, significant buoyancy effects provide a challenge to the modeling. To fully understand the fluid dynamics and its effect on heat transfer in this application, a pilot plant scale vessel and the commercial crystallizer are investigated. For the isothermal pilot plant model, CFD predicted residence time distribution (RTD) compares well with the experimental curve. For the commercial crystallizer, both fluid dynamics and heat transfer are modeled and a simple crystallization model is included to introduce the effect of solids on physical properties and fluid dynamics. Validation against experimental RTD data is reasonable. This model is now being used to help improve the performance of PX crystallizers.