CFD modeling and simulation of complex flows in phosphate fertilizer manufacturing process: Preneutralization and granulation units

Résumé

Mathematical modelling and numerical simulations are widely used in many chemical industries, such as petrochemical industry. Its used for operator training, design, and process optimization. However, there is a lack of rigorous numerical modeling and simulations in the phosphate fertilizer industry. There exist many challenges in the production systems of phosphate fertilizers including; multiple phases in the system such as liquids, solids and gas, particles with different sizes and distributions, and variation in the physical properties including rheology and thermodynamics properties. Despite the available resources, limited studies have been focused on the understanding of the hydrodynamics within the components of the manufacturing process, to enhance the production yield and to adapt the manufacturing process conditions to the quality of raw materials. Computational Fluid Dynamics (CFD) represents a valuable tool to validate phenomenological models and allows an exhaustive understanding of process sensitivity to operating conditions, and geometrical details effects on the flow hydrodynamics. Furthermore, CFD permits a better understanding of physical phenomena, as exchange mechanisms occurring in the studied processes, which is not possible on the industrial plant or by laboratory scale experiments that require many considerations for the scale up. The aim of this thesis is to i) investigate the fluid dynamics of the master pieces in Di Ammonium Phosphate fertilizer process, which are the preneutralization and the granulation unit operations, using commercial simulation software Ansys Fluent, ii) to identify the effects of the complex phenomena in the formation of heterogeneities of the multiphase flows, and iii) to evaluate the effect of the operating conditions on the flows hydrodynamics. On the light of the obtained results, we aim to optimize the design and control of the preneutralization and granulation units and propose new recommendations for a better process performance. This research work is composed of two different studies; on the one hand, the three-dimensional modeling and simulation of the preneutralizer reactor, based on the Euler-Euler multiphase approach, and theMultiple Reference Frame (MRF) is applied to consider the rotational movement of the agitator. The tailored gas-liquid CFD model accounts for the transfer mechanisms and chemical species exchange between phases. The finite rate turbulence chemistry interaction model is adopted to demonstrate the strong relation between turbulence and chemistry in reacting turbulent flows. We evaluated the baffles effect on the fluid dynamics in a simplified preneutralizer model, we studied the sensitivity of the reacting flow hydrodynamics to the operating conditions, and we conducted a geometrical optimization study, giving birth to a new preneutralizer design, with optimal gas spargers type and positions. On the other hand, a rotary drum granulator CFD model is tailored. Gas-solid flow is numerically simulated using the Euler-Euler approach, coupled to the Kinetic Theory of Granular Flow (KTGF). The effect of fertilizer particles size on their dynamics is evaluated. We studied the CFD granulation model sensitivity to the drag model subcomponent of the CFD model, and to the key operating conditions. In light of the present study, new operating conditions combinations are proposed for the industrial plant to validate further by an experimental campaign. All the conducted simulations are fully three dimensional with the industrial scale dimensions.

Citer ce document

Accès au document

Ce document est hébergé sur son dépôt institutionnel d'origine.

Auteur(s)

Statistiques

Consultations : 2

Téléchargements : 0