Efficient simulation of the effect of mixing and flow condition on product crystal qualities in a continuous crystallizer using coupled CFD-PBE approach

The majority of the active pharmaceutical ingredients (APIs) used in the pharmaceutical industries are crystals of organic molecules. In these industries, crystallization is widely used as the principal method of separation and purification. As opposed to the traditionally used batch mode, the interest is continuous crystallization has increased significantly in recent years due to several benefits such as consistency of product quality and reduced manufacturing cost by improving asset utilization. While designing continuous crystallizer at the industrial scale, e.g., plug flow crystallizer (PFC), the effect of imperfect mixing and flow condition has to be considered since they can affect the product crystal qualities as well as plant operation significantly. For example, imperfect mixing can lead to local variation in supersaturation within the crystallizer that may results in excessive fine crystals. In order to take this variation into account while modelling continuous crystallization, this work aims at combining computational fluid dynamics (CFD) describing flow field with population balance equation (PBE) describing changes in the crystal phase. The solution of the governing equations for coupled CFD-PBE is computationally expensive. Thus, in most of the previous works that consider coupled CFD-PBE approach, the PBE is solved only in terms of moments of the crystal size distribution (CSD).

In this work, efficient solution techniques such as lattice Boltzmann method (LBM) will be used for solving the coupled CFD-PBE model equations, where the solution of the PBE in terms of CSD will be explored. LBM is a simulation technique that takes a bottom up approach by solving simplified governing equations at the mesoscopic level which is equivalent to solving the complicated nonlinear governing equations at the macroscopic level. These results will be very useful in designing industrial continuous crystallizer with particular application to pharmaceutical and chemical sectors.

Candidates should have (or expect to achieve) a UK honours degree at 2.1 or above (or equivalent) in Chemical Engineering or similar discipline along with knowledge, or interest in, process design, simulation and experience in computer programming (e.g., C/C++/FORTRAN) are highly expected.

APPLICATION PROCEDURE:

• Apply for Degree of Doctor of Philosophy in Engineering
• State name of the lead supervisor as the Name of Proposed Supervisor
• State ‘Self-funded’ as Intended Source of Funding
• State the exact project title on the application form

When applying please ensure all required documents are attached:

• All degree certificates and transcripts (Undergraduate AND Postgraduate MSc-officially translated into English where necessary)
• Detailed CV

Informal inquiries can be made to Dr A Majumder ([Email Address Removed]) with a copy of your curriculum vitae and cover letter. All general enquiries should be directed to the Postgraduate Research School ([Email Address Removed])

Additional research costs (ARC) of £1,500 will be required to attend a National/International Conference (eg. British Association of Crystal Growth Annual Meeting).