SCI和EI收录∣中国化工学会会刊

Chinese Journal of Chemical Engineering ›› 2020, Vol. 28 ›› Issue (8): 2064-2074.DOI: 10.1016/j.cjche.2020.03.041

• Fluid Dynamics and Transport Phenomena • Previous Articles     Next Articles

CFD investigation of the agitation in the desupersaturation during the wet-process phosphoric acid (WPPA) process

Asmaa Hadane1,2, Lhachmi Khamar2,3, Saad Benjelloun2, Abderrahman Nounah1, Mohammed Khamar1   

  1. 1 LGCE, Higher School of Technology in Salé, Mohammed V University in Rabat, Morocco;
    2 MSDA, Mohammed 6th Polytechnic University, Benguerir 43150, Morocco;
    3 LIPIM, National School of Applied sciences in Khouribga, Sultan Moulay Sliman University in Beni Mellal, Morocco
  • Received:2019-10-01 Revised:2020-02-05 Online:2020-09-19 Published:2020-08-28
  • Contact: Asmaa Hadane

CFD investigation of the agitation in the desupersaturation during the wet-process phosphoric acid (WPPA) process

Asmaa Hadane1,2, Lhachmi Khamar2,3, Saad Benjelloun2, Abderrahman Nounah1, Mohammed Khamar1   

  1. 1 LGCE, Higher School of Technology in Salé, Mohammed V University in Rabat, Morocco;
    2 MSDA, Mohammed 6th Polytechnic University, Benguerir 43150, Morocco;
    3 LIPIM, National School of Applied sciences in Khouribga, Sultan Moulay Sliman University in Beni Mellal, Morocco
  • 通讯作者: Asmaa Hadane

Abstract: Desupersaturation is a complex cooling operation that involves hydrodynamic, thermal and mechanical phenomena. This process requires continuous agitation to avoid fouling problems and sludge deposition. The current work aims to investigate the well mixedness in the desupersaturation tank for optimal performance. For this purpose, a multi-fluid CFD study was conducted based on the Euler-Euler modeling approach, considering a multiphase flow involving a liquid phase (phosphoric acid) and a poly-dispersed solid phase, i.e. a sludge with three different sizes where each size is considered as a separate phase. First, the hydrodynamic behavior of the flow within the agitated desupersaturator is analyzed through the investigation of the velocity fields as well as the power and pumping numbers, to determine both the agitator capacity to pump the flow and its power consumption during the operation. Then, in order to assess the mixture homogeneity, we evaluated the solid suspension in the desupersaturation reactor following conventional methods and two new proposed methodologies: the first approach is to evaluate the suspension quality in the mixing system by compartment and the second consists on the assessment of the uniform convergence of the solid concentration. Furthermore, we calculated the time required to achieve a full suspension at different solid concentrations. On other hand, we conducted a detailed analysis of the solid distribution dependency on the impeller rotational speed at different solid volume fraction, which allows a good understanding of the parameters controlling the homogenization in the desupersaturator.

Key words: CFD, Multiphase flow, Mass transfer, Phosphoric acid, Agitation

摘要: Desupersaturation is a complex cooling operation that involves hydrodynamic, thermal and mechanical phenomena. This process requires continuous agitation to avoid fouling problems and sludge deposition. The current work aims to investigate the well mixedness in the desupersaturation tank for optimal performance. For this purpose, a multi-fluid CFD study was conducted based on the Euler-Euler modeling approach, considering a multiphase flow involving a liquid phase (phosphoric acid) and a poly-dispersed solid phase, i.e. a sludge with three different sizes where each size is considered as a separate phase. First, the hydrodynamic behavior of the flow within the agitated desupersaturator is analyzed through the investigation of the velocity fields as well as the power and pumping numbers, to determine both the agitator capacity to pump the flow and its power consumption during the operation. Then, in order to assess the mixture homogeneity, we evaluated the solid suspension in the desupersaturation reactor following conventional methods and two new proposed methodologies: the first approach is to evaluate the suspension quality in the mixing system by compartment and the second consists on the assessment of the uniform convergence of the solid concentration. Furthermore, we calculated the time required to achieve a full suspension at different solid concentrations. On other hand, we conducted a detailed analysis of the solid distribution dependency on the impeller rotational speed at different solid volume fraction, which allows a good understanding of the parameters controlling the homogenization in the desupersaturator.

关键词: CFD, Multiphase flow, Mass transfer, Phosphoric acid, Agitation