Agglomeration studies in a 250kW pilot scale bubbling fluidised bed

biomass combustor

*Stephen Chilton1, Dr William Nimmo2

1 Energy Research Institute (ERI), School of Chemical and Process Engineering, University of Leeds, LS2 9JT

2, Energy Engineering Group, Department of Mechanical Engineering, The Arts Tower, level 1, Western Bank, Sheffield, S10 2TN

Abstract for oral presentation:

Fluidised bed combustion is a flexible method for combusting less conventional lower grade fuels for the utilisation in power generation facilities. A range of biomass fuels (white wood, oats, wheat straw, Miscanthus and peanut shell) and low grade coals were investigated in a pilot scale bubbling fluidised bed combustor (BFBC) operated at 250kW thermal. The results represent the physical and chemical process observed in full scale plant. The experimental tests recreated realistic conditions that would cause bed problems at full scale it was possible to study real agglomerated material and its effect on stable combustion and the consequences for the continued operation.

Post run samples form the fluidised bed were analysed using X-ray fluorescence (XRF), X-ray diffraction (XRD), Scanning electron microscopy (SEM-EDX) to determine the chemical and structural composition in order to understand the mechanisms and process involved. From this work the operating limits of the combustor can be defined by the composition of the fuel ash which in turn can help determine the maximum operating temperatures in order to avoid bed agglomeration and defluidisation.

Work thus far has been used to indicate the potential for agglomeration formation based on physical and chemical compositions of fuel, the health of the air distributor and the way air flow has changed has been analysed experimentally and the mechanisms leading to the formation of agglomerates and sintered material has been postulated. The results of this study is able to shed light on the applicability of these low grade fuels in full commercial operations and indicate as to the issue that can arise from these fuels.

Keywords: coal, biomass,fluidised bed combustion, X-Ray fluorescence.

Acknowledgement: Leeds University Doctorial training Centre has funded the student, project support came from the British Council [SP_254 INSPIRE] and acknowledgment should be made to the technicans that have assisted in the work load.

Corresponding author: Stephen Chilton

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