Doctoral Dissertations

Keywords and Phrases

CFD; Gas dynamics; Liquid dynamics; Moving bed reactor; Two tip optical probe


"Upflow Moving Bed Hydrotreater (MBR) reactor is used for hydrotreating resid crude oil. It is a two-phase upflow reactor having a catalyst bed with conical bottom, and plena. At industrial conditions the reactor is not performing at its best and encountering issues such as hot spots, catalyst agglomeration inside the catalyst bed leading to frequent shutdown of the reactor. The root cause of these problems are linked to the improper hydrodynamics inside the catalyst bed. To investigate this, the industrial scale MBR is scaled down to a pilot scale and indicative and key hydrodynamic parameters are investigated using developed experimental methods and CFD simulation.

The local hydrodynamics is quantified using an experimental technique called two-tip optical probe (TTOP). Developed algorithms for TTOP to derive the local phase saturations, velocities, backmixing, maldistribution using the time series data of the probe. The results indicates high maldistribution zones inside the catalyst bed and found convincing evidence to link this to the conical design and plena of MBR.

Overall Gas and Liquid dispersion/Mixing in the catalyst bed is investigated by tracer studies using a developed methodology based on residence time distribution (RTD), Convolution, Regression, and Catalyst Bed Models based on axial dispersion and wave model. Good gas/liquid dispersion is seen at the industrial scaled down operating condition.

A CFD model is developed for the lower plenum of MBR and validated with gamma ray densitometry (GRD) for radial profile of line average phase volume fraction. The simulation indicates that the current design of lower plenum is enabling a dominant movement of phases only in the central region outlets of this plenum. A modification of the current design proves to perform better in terms of movement of phases along entire outlets of the lower plenum"--Abstract, page iv.


Al-Dahhan, Muthanna H.

Committee Member(s)

Smith, Joseph D.
Neogi, P. (Partho), 1951-
Park, Joontaek
Schlegel, Joshua P.


Chemical and Biochemical Engineering

Degree Name

Ph. D. in Chemical Engineering


Missouri University of Science and Technology

Publication Date

Summer 2018

Journal article titles appearing in thesis/dissertation

  • Local hydrodynamics investigation of industrial scaled down upflow moving bed hydrotreater (MBR) reactor using two-tip optical probe
  • Gas phase dispersion/mixing investigation in gas-liquid upflow moving bed hydrotreater reactor (MBR) using developed gas tracer technique and method based on convolution/ regression
  • Liquid phase dispersion/mixing investigation in gas-liquid upflow moving bed hydrotreater reactor (MBR) using developed liquid tracer technique and method based on convolution/regression
  • Phase mass distribution based performance evaluation of lower plenum of upflow moving bed hydrotreater reactor (MBR) and proposal of an improved design using CFD


xiv, 154 pages

Note about bibliography

Includes bibliographic references.


© 2018 Vineet Alexander, All rights reserved.

Document Type

Dissertation - Open Access

File Type




Thesis Number

T 11467

Electronic OCLC #