7.6 SKILLS

7.6 SKILLS

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RESEARCH


Chemical Looping Combustion of Victorian Brown Coal ... Continued from previous page

By Sharmen Rajendran, PhD Student in Energy, Fuels and Reaction Engineering Group,
Department of Chemical Engineering, Monash University


My postgraduate degree is titled Chemical Looping Combustion of Victorian Brown Coal and is supervised by Associate Professor Sankar Bhattacharya at the Department of Chemical Engineering, Monash University, and Professor Klaus Hein.

The main focus of my research is to determine the applicability of the CLC technology with Victorian Brown Coal, and this involves investigation of a number of aspects of the process:


  • What is the appropriate ratio of oxygen carrier to Victorian brown coal?
  • What is the CO2 capture efficiency of the process? Would it be close to 100% or towards the other end of the spectrum?
  • How reusable is the oxygen carrier with Victorian brown coal?

  • What is the rate of loss of oxygen carrier, or attrition, with time?
  • What is the rate of oxygen carrier reactivity degradation with respect to time?
  • What factors affect the reactivity of the oxygen carrier?
  • Would commercial metal oxides provide sufficient reaction rate for the CLC process or would synthetic oxygen carriers be necessary?
  • What are the optimum operation conditions with respect to temperature, fluidization gas concentration, fluidization velocity etc.?

While there has been increasing research into coal fuelled CLC in recent times, very little literature exists for brown coal and even lesser for Victorian brown coal. My research will serve to fill in this knowledge gap and will be accomplished through my scope of study as follows:

  • Chemical looping combustion of Victorian brown coal on various experimental scales starting with a Thermogravimetric Analyzer (TGA) followed by a small bench scale fluidized bed and ultimately with a large four metre tall bench scale fluidized bed reactor.

    The TGA was used for kinetic studies to obtain the parameters of CLC with Victorian brown coal. The small scale fluidized bed reactor is used to assess the performance of Victorian brown coal fuelled CLC.

    Lastly, the large fluidized bed reactor can be used to study not only the performance but the scale up characteristics, drawing on the work done using the small fluidized bed reactor. Figure 2 shows the large bench scale fluidized bed reactor which will be used in this project.


Figure 2: Large four metre tall bench scale fluidized bed reactor configuration

  • The oxygen carrier is characterised using various analytical instruments such as Scanning Electron Microscope (SEM), Electron Dispersive X-Ray (EDS), X-Ray Diffraction (XRD), X-Ray Fluorescence (XRF) as well as X-Ray Photoelectron Spectroscopy (XPS). These are conventional analytical techniques that are typically employed in this field of study whereby the oxygen carrier is subjected to ex-situ analysis.

    Recently, a synchrotron application was approved and CLC experiments were performed in an in-situ manner to shed more light with regards to the reduction of the oxygen carrier with temperature and time. A photograph of the beamline can be found in Figure 3.


Figure 3: X-Ray Diffraction beamline at the Australian Synchrotron (Shuai Zhang, visiting PhD student from Southeast University, China (left) and Sharmen Rajendran (author) right)

  • Performance of different oxygen carriers, in particular synthetic materials, in terms of reduction and oxidation reactivity. Current preliminary findings suggest that whilst synthetic oxygen carriers have a higher reactivity, the cost of manufacturing such materials will render them unfeasible even in a large scale application.

An exchange student from Southeast University, China is also working on this project. This student is presently at Monash for a total duration of one year at our laboratory investigating the performance of synthetic oxygen carriers, which is part of the research scope.

This project has also hosted four students undertaking their final year project with the Department of Chemical Engineering. Two students have undertaken their summer research with this project which qualifies as working experience needed for their graduation. These two students were selected to present their research at Monash-Warwick International Conference on Undergraduate Research.

Finally, this project has allowed me to perform some experiments at Southeast University marking the initiation of collaborative work between the two universities in this research front. Additional collaborations in this project include Chalmers University, University of Alberta and the Huazhong University of Science and Technology.





For more information on this research, go to the previous page of this e-newsletter.




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