An Experimental and CFD Based Analysis on Industrial Biomass Drying Production

Pryce, Marcia and Aiouache, Farid and Cheneler, David (2021) An Experimental and CFD Based Analysis on Industrial Biomass Drying Production. Masters thesis, Lancaster University.

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Abstract

This thesis presents an investigation on the drying processes of woodchip, by means of convective drying and infrared, drying. Two processes are considered, woodchip- bed drying (based on industrial site Bowland Bioenergy) and the drying of a singular woodchip, with additional analysis of the dust released during the drying process. The core objectives were to investigate parameters influencing drying rate and to characterise dust produced during drying. Parameters considered surrounding woodchip drying were infrared radiation, temperature, air flow rate, bed depth, drier floor speed, and covering the drier. Primarily developing an understanding of the drying mechanism within wood and seeking to alter these parameters for a desired yield. Drying of woodchip is characterised by means of mathematical models and Computational Fluid Dynamics (CFD) simulations which are validated by experimental analyses and show qualitative agreement. Comparatively to the experimental results there was a correlation between temperature and airflow increase and drying rate in both experimental and simulation results. Woodchip bed results suggested that increasing bed-depth from 24.5 cm to 34 cm will dry the woodchip effectively whilst increasing woodchip production by 39 %, covering the drier increased to moisture loss by ~15 %, and increasing the time in the drier decreased the final moisture content, the influence of time on moisture content decreases as the curves show a falling rate period. Single chip results showed temperature and airflow impacted the drying rate. Characterisation of the wood dust showed the surface area results ranged from 0.429 to 0.825 m2.g-1, average density of 502 kg.m-3 and dust load of 2 g.m-3. Particle size results aided the proposed design of a dust removal system to mitigate the risks of wood dust using a cyclone filter.