Laser Imaging of Potassium in Biomass Thermal Processing

Biomass is increasingly important as a source of renewable energy and in chemical synthesis. Biomass includes agricultural and forestry waste: maximising the utilisation of these resources contributes significantly to reducing fossil-fuel dependence and combating climate change. Biomass undergoes thermal processing, either by direct combustion to generate energy, or to produce sustainable fuels or chemical feedstocks. Potassium is naturally present in agricultural biomass residues. Inherent potassium in biomass has a substantial catalytic influence on its thermal decomposition, and thus affects the yield of bio-products and the overall energy efficiency from the advanced thermal treatment of biomass, e.g., pyrolysis and gasification. During thermal processing, potassium is released and forms various compounds such as KCl and KOH, which can be harmful to processing equipment. A step-change in imaging and sensing techniques would allow better understanding of biomass thermal processes associated with the synergetic impact of potassium, thus ultimately facilitating improved design of industrial processes.

The aim of this PhD project is to develop a laser-induced breakdown spectroscopy (LIBS) instrument for quantitative imaging of total potassium content in thermal processes. Laser-induced breakdown spectroscopy involves the use of a tightly focussed, pulsed laser beam to create a plasma in which the compounds in the flow are decomposed. The resulting spectral emission can therefore be related to the total elemental concentration. The proposed methods totally avoid the use of extractive sampling, which is intrusive to the flow, and use only techniques capable of spatially-resolved optical imaging. The application of these methods will be tested first in flames seeded with potassium before moving to biomass combustion and gasification processes of increasing practical relevance.

The student working on the proposed project will receive extensive training on both the principles and application of optical measurements in combustion, as well as the fundamentals of thermal energy processes and biomass processing. There will also be ongoing engagement with a wider network of collaborating researchers. Participation in national and international conferences will be encouraged with examples being “Laser Diagnostics in Combustion and Energy Science” and “International Symposium on Combustion”.

In addition to undertaking cutting edge research, students are also registered for the Postgraduate Certificate in Researcher Development (PGCert), which is a supplementary qualification that develops a student’s skills, networks and career prospects.

Information about the host department can be found by visiting:

www.strath.ac.uk/engineering/chemicalprocessengineering/

www.strath.ac.uk/courses/research/chemicalprocessengineering/