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https://hdl.handle.net/1959.11/9079
Title: | Deposition of hydroxyapatite and calcium oxalate dihydrate on a heat exchanger tube | Contributor(s): | East, CP (author); Doherty, WOS (author); Fellows, Christopher (author) ; Yu, H (author) | Publication Date: | 2011 | DOI: | 10.1002/apj.487 | Handle Link: | https://hdl.handle.net/1959.11/9079 | Abstract: | Most studies on the characterisation of deposits on heat exchangers have been based on bulk analysis, neglecting the fine structural features and the compositional profiles of layered deposits. Attempts have been made to fully characterise a fouled stainless steel tube obtained from a quintuple Roberts evaporator of a sugar factory using X-ray diffraction and scanning electron microscopy techniques. The deposit contains three layers at the bottom of the tube and two layers on the other sections and is composed of hydroxyapatite, calcium oxalate dihydrate and an amorphous material. The proportions of these phases varied along the tube height. Energy-dispersive spectroscopy and XRD analysis on the surfaces of the outermost and innermost layers showed that hydroxyapatite was the major phase attached to the tube wall, while calcium oxalate dihydrate (with pits and voids) was the major phase on the juice side. Elemental mapping of the cross-sections of the deposit revealed the presence of a mineral, Si-Mg-Al-Fe-O, which is probably a silicate mineral. Reasons for the defects in the oxalate crystal surfaces, the differences in the crystal size distribution from bottom to the top of the tube and the composite fouling process have been postulated. | Publication Type: | Journal Article | Source of Publication: | Asia-Pacific Journal of Chemical Engineering, 6(6), p. 921-932 | Publisher: | John Wiley & Sons Ltd | Place of Publication: | United Kingdom | ISSN: | 1932-2143 1932-2135 |
Fields of Research (FoR) 2008: | 030199 Analytical Chemistry not elsewhere classified 090499 Chemical Engineering not elsewhere classified |
Socio-Economic Objective (SEO) 2008: | 820304 Sugar | Peer Reviewed: | Yes | HERDC Category Description: | C1 Refereed Article in a Scholarly Journal |
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Appears in Collections: | Journal Article |
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