Use this URL to cite or link to this record in EThOS: http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.261558
Title: The morphology of spray-dried particles
Author: Walton, David E.
ISNI:       0000 0001 2452 1247
Awarding Body: University of Aston in Birmingham
Current Institution: Aston University
Date of Award: 1994
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Abstract:
Samples of Various industrial or pilot plant spray-dried materials were obtained from manufacturers together with details of drying conditions and feed concentrations. The samples were subjected to qualitative and semi-quantitative examination to identify structural and morphological features. The results were related to measured bulk physical properties and to drying conditions. Single particles were produced in a convective drying process Analogous to spray drying, in which different solids or mixtures of solids were dried from solutions, slurries or pastes as single suspended droplets. The localized chemical and physical structures were analysed and in some cases the retention of volatiles monitored. The results were related to experimental conditions, viz.; air temperature, initial solids concentration and the degree of feed aeration. Three distinct categories of particle morphology were identified, i.e.; crystalline, skin-forming and agglomerate. Each category is evidence of a characteristic drying behaviour which is dependent on initial solids concentration. the degree of feed aeration, and drying temperature. Powder flow ability, particle and bulk density, particle-size, particle friability, and the retention of volatiles bear a direct relationship to morphological structure. Morphologies of multicomponent mixtures were complex, but the respective migration rates of the solutes were dependent on drying temperature. Gas-film heat and SDSS transfer coefficients of single pure liquid droplets were also measured over a temperature range of 50•C to 200•C under forced convection. Balanced transfer rates were obtained attributed to droplet instability or oscillation within the airflow, demonstrated in associated work with single free-flight droplets. The results are of relevance to drier optimisation and to the optimisation of product characteristics, e.g.; particle strength and essential volatiles-retention, in convective drying.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID: uk.bl.ethos.261558  DOI: Not available
Keywords: Applied Chemistry ; Chemical Engineering
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