18.7 PhD RESEARCH

18.7 PhD RESEARCH

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RESEARCH


UPDATE FROM BCIA


POSTGRADUATE RESEARCH SCHOLARS


BCIA’s program of postgraduate research scholarships is part of our commitment to strategic investment in skills development. The aim of BCIA's support is to secure the scientific, engineering and trades expertise required for the development of new low-emissions brown coal technologies.

To date, BCIA has awarded 19 research scholarships to PhD candidates at top-ranking Australian universities.

In this edition of Perspectives we will hear from BCIA scholarship recipient Rahul Reza Chowdhury from Federation University.


The effect of Victorian brown coal fly-ash on Solvent Degradation during Post-Combustion Capture of CO₂

By Rahul Reza Chowdhury, PhD Student, Carbon Technology Research Centre, Federation University

Rahul Reza Chowdhury joined the Carbon Technology Research Centre in March 2015 as a PhD student. Before joining CTRC, he had a diverse research experience in the field of Solid Oxide Fuel Cell and Particle-laden flow. His PhD project focuses on heterogeneous reactions in amine absorbents during Post-combustion capture of CO₂.

Post combustion capture (PCC) of CO₂ is a major focus for mitigating greenhouse gas emissions. Acid-gas scrubbing with aqueous amines is the most mature technology for PCC from fossil fuel combustion flue gases. Power stations in the Latrobe Valley use electrostatic precipitators to remove fly ash from flue gases, but these are not completely effective. There is a concern that fugitive ultrafine fly ash will contaminate any amine solvents used for PCC, potentially leading to reduced solvent life and increased operating expenses.

My PhD project, which is supported by both BCIA and CSIRO, aims to understand the effects of fly ash on amine solvent degradation, which can occur via chemical reactions in solution and via reactions and interactions with metal surfaces. Solvent degradation has been linked to fly ash contamination in PCC plants overseas, but has not yet been investigated in Australia. The fly ash from Victorian brown coal has distinctly different properties from other coal ashes, so its role in solvent degradation merits further research.

My project involves characterisation of the degradative impact of fly ash by determining the identity and yield of water soluble organic and inorganic ions with respect to degradation time. The correlation between the formation of both soluble (e.g. metal ions, organic anions) and insoluble (e.g. metallic materials, metals adsorbed into mineral surfaces) products will enable further understanding of the heterogeneous reactions occurring during PCC operation. These interactions are being investigated using the advanced analytical technologies available at the new Carbon Technology Research Centre at Federation University in Churchill.


A detailed physicochemical characterization of Victorian brown coal fly ash samples collected from the CSIRO PCC pilot plant at AGL Loy Yang power station has already been completed. Scanning electron microscopy (SEM) revealed the ash samples contain very small particles of porous unburnt char, with morphologies associated with their botanical and microbial origins (Fig. 1A) and (Fig. 1B). These char particles have a relatively high surface area compared with the mineral components of the ash. They could potentially increase the rate of solvent degradation by facilitating degradation reactions, or inhibit it by removing deleterious compounds by adsorption.

SEM investigations have also been conducted on the surface corrosion of aged 316SS packing materials retrieved from the same plant. These packing materials


Figure 1: SEM micrographs
Top row: Char identified in flyash sampled downstream of PCC plant flue gas inlet
- A Woody structure - B Funginite structure
Bottom row: Surface of aged metal packing from a PCC absorber column -C Particle accumulation and grain boundary corrosion -D Depletion of metals from the surface of packing materials and grain boundary corrosion

experienced grain boundary corrosion and accumulated particles (Fig. 1C) and depletion of metals (Fig. 1D) during PCC operation. Interestingly, the corrosion in the absorber columns has not been found to correlate with temperature, CO₂ loading in the liquid phase or CO₂ loading in the gas phase. Further work is under way to investigate the physical and chemical processes that may be affecting corrosion within the PCC equipment.

Degradation of aqueous amine solvents is a critical area of research because it is the main source of environmentally sensitive compounds in PCC. Understanding and controlling this issue is necessary to support the “social licence to operate” for PCC in the Latrobe Valley.




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