Study of Hydrodynamics of Trickle Bed Reactors and Plugging Phenomenon Due to Fine Deposition

  • Shahid Rabbani

Student thesis: Master's Thesis

Abstract

Trickle Bed Reactors (TBRs) are of great importance in refineries, petroleum and petrochemical industries. The importance of TBRs can be gauged from the fact that approximately 1.6 billion ton capacity of material processed through TBRs in a year which costs approximately US$ 300 billion. However, it is unfortunate that despite high importance of TBRs, fundamental understanding of hydrodynamics is still lacking. The first part of this work is contribution towards gaining a good insight of the flow behaviour and hydrodynamics of TBR while conducting a comparative analysis of different models available to predict important operating parameters of the flow. Based on the study of existing models, a new model to predict important parameters has been proposed which validates the experimental data more accurately than the existing hydrodynamic models for TBR. The second part of the work addresses the pore plugging phenomenon inside the fixed bed reactors. With the passage of time during operations, non-filterable fines such as coke, corrosion products and fine clay in oil sands bitumen deposit on the catalyst particles. The gradual entrapment and deposition of fine particles of range 0.7-20 μm cause the pore-plugging phenomenon to occur which consequently blocks the flow passages inside the porous medium. This pore plugging phenomenon is widely responsible for the increased pressure drop in the trickle bed reactors which in turn causes the operation to stop to clean the bed and replace the catalysts. Consequently a huge cost is incurred in the form of plant shut down and catalyst replacement. In order to understand the plugging phenomenon and its effect of hydrodynamic of the single phase packed bed reactor a CFD model has been formulated in terms of collection efficiency, Brownian motion and interfacial momentum exchange terms to simulate the increase in pressure drop due to deposition of fine particles in real conditions. This is for the first time that Ansys Fluent has been used to simulate fine-particle deposition in fixed-bed conditions. The results were compared with the experiments and excellent agreement was reached.
Date of AwardMay 2015
Original languageAmerican English
SupervisorMohamed Sassi (Supervisor)

Keywords

  • Trickle bed reactors
  • petroleum refineries
  • petrochemical industries
  • hydrodynamics
  • corrosion products
  • pore plugging phenomenon.

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