Hostname: page-component-586b7cd67f-l7hp2 Total loading time: 0 Render date: 2024-12-05T03:15:57.596Z Has data issue: false hasContentIssue false
  • English
  • Français

Self-heating behaviour of low moisture content particles—modelling the basket-heating of solid particles and some aspects of the cross over behaviour using milk powder as an example

Published online by Cambridge University Press:  17 February 2009

Xiao Dong Chen
Xiao Dong Chen
Affiliation:
Department of Chemical and Materials EngineeringThe University of Auckland, Private Bag 92019, Auckland, New Zealand. Email: [email protected]
Rights & Permissions [Opens in a new window]

Abstract

Core share and HTML view are not available for this content. However, as you have access to this content, a full PDF is available via the ‘Save PDF’ action button.

Self-heating in packed paniculate that is exothermically reactive is a major cause of fire and explosion in the powder industry. This study is focused on part of the Auckland development of a mathematical model dealing with this hazardous process in industry using milk powder as an example. Milk powder is a primary powdered food product around the world.

An update of the detailed mathematical model is given here, and predictions are made using the model to simulate the basket-heating behaviour of a milk powder in the laboratory (so the model can thus be validated). Basket heating in an oven is a standard laboratory technique for measuring the exothermic reactivity of a solid material.

After a favorable comparison with the laboratory results, several aspects of basket-heating were investigated with a view to further improving the technique. Firstly, the model was used to explore the effect of elevated ambient humidity and initial sample water content upon the heating process in the basket. Secondly, the model was used to explore the cross over phenomenon which is related to a novel procedure for measuring activation energy and exothermicity (that is, the Crossing-Point-Temperature (CPT) method, which is a new version of the basket heating technique). The predictions together with the experimental evidence show that the reaction kinetics obtained using the Heat Release (HR) method (another version of the basket heating technique well published in the literature) may not be correct, especially for those measured at elevated oven temperatures and for larger basket sizes. Thirdly, simulations were performed to illustrate that the CPT phenomenon does not just occur at the center of the basket but also occurs everywhere else in the sample. This can become a significant advantage for further development of the CPT method in terms of reducing experimental duration and improving reproducibility.

Type
Research Article
Information
The ANZIAM Journal , Volume 43 , Issue 1 , July 2001 , pp. 165 - 181
Copyright
Copyright © Australian Mathematical Society 2001

References

[1]Banerjee, S. C., Spontaneous Combustion of Coal and Mine Fires (A. A. Balkema, Rotterdam, India, 1985).Google Scholar
[2]Beever, P. F. and Crowhurst, D., “Fire and explosion hazards associated with milk spray drying operations”, J. Soc. Dairy Tech. 42 (1989) 65–70.Google Scholar
[3]Bowes, P. C., Self-heating: Evaluating and controlling the hazards (Elsevier, Amsterdam, The Netherlands, 1984).Google Scholar
[4]Bradshaw, S., Glasser, D. and Brooks, K., “Self-ignition and convection patterns in an infinite coal layer”, Chem. Eng. Communications 105 (1991) 255–278.CrossRefGoogle Scholar
[5]Brooks, K., Svanas, N. and Glasser, D., “Evaluating the risk of spontaneous combustion in coal stockpiles”, Fuel 67 (1988) 651–656.Google Scholar
[6]Carras, J. N. and Young, B. C., “Self-heating of moist coal”. Progress in Energy and Combustion Sci. 20 (1994) 1–15.CrossRefGoogle Scholar
[7]Chen, X. D., “Basket heating methods for obtaining exothermic reactivity of solid materials. Part I. The extent and impact of the departure of the crossing-point temperature from the corresponding oven temperature”, Trans.IChemE Part B, (submitted).Google Scholar
[8]Chen, X. D., “On the mathematical modelling of the transient spontaneous heating in a moist coal stockpile”, Combustion and Flame 90 (1992) 114–120.Google Scholar
[9]Chen, X. D., “A new water sorption equilibrium isotherm model”, Food Research Internal. 30 (1998) 755–759.CrossRefGoogle Scholar
[10]Chen, X. D., “On the fundamentals of diffusive self-heating of water containing combustible materials”, Chem. Eng. and Processing 37 (1998) 367–378.Google Scholar
[11]Chen, X. D., “Temperature dependence function of equilibrium sorption isotherms established by a reaction engineering approach”, J. Food Engineering 37 (1998) 259–269.Google Scholar
[12]Chen, X. D. and Chong, L. V., “Some characteristics of transient self-heating inside an exothermically reactive porous solid slab”, Trans. IChemE 73B (1995) 101–107.Google Scholar
[13]Chen, X. D. and Chong, L. V., “Several important issues related to the crossing-point temperature (CPT) method for measuring self-ignition kinetics of combustible solids”, Trans. IChemE 76B (1998) 90–93.Google Scholar
[14]Chen, X. D., Lake, R. and Jebson, S., “Study of milk powder deposition on a large industrial drier”, Trans. IChemE 71C (1993) 180–186.Google Scholar
[15]Chen, X. D. and Xie, G. Z., “Fingerprints of the drying behaviour of particulate or thin layer food materials established using a reaction engineering model”, Trans. IChemE 75C (1997) 213–222.Google Scholar
[16]Choi, Y. and Okos, M. R., “Effects of temperature and composition on the thermal properties of foods”, in Food Engineering and Process Applications Volume 1: Transport Phenomena (eds. Le Maguer, M. and Jelen, P.), (Elsevier Applied Science Publishers, London, 1986) 93–101.Google Scholar
[17]Chong, L. V., “Thermal ignition of dairy powders”, Ph. D. Thesis, Department of Chemical and Materials Engineering, The University of Auckland, Auckland, New Zealand, 1997.Google Scholar
[18]Chong, L. V., Chen, X. D. and Mackereth, A. R., “Effect of composition on the thermal ignition kinetics of milk powders”, in Proceedings of the 25th Australasian Chemical Engineering Conference (Chemeca 97), on CD-ROM, 1997.Google Scholar
[19]Chong, L. V., Shaw, I. R. and Chen, X. D., “Thermal ignition kinetics of wood sawdust measured by a newly devised experimental technique”, Process Safety Progress 14 (1995) 266–270.Google Scholar
[20]Chong, L. V., Shaw, I. R. and Chen, X. D., “Exothermic reactivities of skim and whole milk powders as measured using a novel procedure”, J. Food Engineering 30 (1996) 185–196.CrossRefGoogle Scholar
[21]Cuzzillo, B. R., “Pyrophoria”, Ph. D. Thesis, Department of Mechanical Engineering, University of California at Berkeley, USA, 1997.Google Scholar
[22]Gray, B. F., Little, S. G. and Wake, G. C., “The prediction of a practical lower bound for ignition delay times and a method of scaling times-to-ignition in large reactant masses from laboratory data – II”, in 24th Symposium (Int.) on Combustion, (The Combustion Institute, 1992), 1785–1791.CrossRefGoogle Scholar
[23]Gray, B. F., Merkin, J. H. and Griffiths, J. F., “The prediction of a practical lower bound for ignition delay times and a method of scaling times-to-ignition in large reactant masses from laboratory data”, in 23rd Symposium (Int.) on Combustion, (The Combustion Institute, 1990), 1775–1782.CrossRefGoogle Scholar
[24]Gray, B. F. and Wake, G. C., “The ignition of hygroscopic materials by water”, Combustion and Flame 79 (1990) 2–6.CrossRefGoogle Scholar
[25]Hull, A. S., Lanthier, J. L., Chen, Z. and Agarwal, P. K., “The role of diffusion of oxygen and radiation on the spontaneous combustibility of a coal pile in confined storage”, Combustion and Flame 110 (1997) 479–493.Google Scholar
[26]Incropera, F. P. and De Witt, D. P., Fundamentals of Heat and Mass Transfer, 3rd ed. (John Wiley and Sons, New York, 1990).Google Scholar
[27]Jones, J. C., “On the thermal ignition of wood waste”, Trans. IChemE 76 (1998) 205–210.CrossRefGoogle Scholar
[28]Jones, J. C., Chiz, P. S., Koh, R. and Matthew, J., “Continuity of kinetics between sub- and supercritical regimes in the oxidation of a high-volatile solid substrate”, Fuel 75 (1996) 1733–1736.Google Scholar
[29]Jouppila, K. and Roos, Y. H., “Water sorption and time-dependent phenomena of milk powders”, J. Dairy Sci. 77 (1994) 1798–1808.Google Scholar
[30]MacCarthy, D. A., “Effect of temperature and bulk density on thermal conductivity of spray-dried whole milk powder”, J. Food Engineering 4 (1985) 249–263.Google Scholar
[31]McIntosh, A. C., “A Semenov approach to the modelling of the thermal runaway of damp combustible material”, IMA J. Appl. Math. 51 (1993) 217–237.CrossRefGoogle Scholar
[32]McIntosh, A. C., Gray, B. F. and Wake, G. C., “The ignition of combustible material in the presence of a damp atmosphere”, Phys. Lett. A 191 (1994) 61–71.CrossRefGoogle Scholar
[33]Nugrono, Y. S., McIntosh, A. C. and Gibbs, B. M., “Using the crossing-point temperature method to assess self-heating behaviour of Indonesian coals”, in Proceedings of the 27th Int. Sym. on Combustion,University of Colorado at Boulder,Colorado,Aug. 3–7(1998), 1998).CrossRefGoogle Scholar
[34]Rahman, S., Food Properties Handbook (CRC Press, Boca Raton, Florida, 1995).Google Scholar
[35]Sano, Y. and Keey, R. B., “The drying of a spherical particle containing colloidal material into a hollow sphere”, Chem. Engineering Sci. 37 (1982) 881–889.Google Scholar
[36]Sisson, R. A., Swift, S., Wake, G. C. and Gray, B. F., “The self-heating of damp cellulosic materials: I. High thermal conductivity and diffusivity”, IMA J. Appl. Math. 49 (1992) 273–279.Google Scholar
[37]Sisson, R. A., Swift, S., Wake, G. C. and Gray, B. F., “The self-heating of damp cellulosic materials: II. On the steady state of the spatially distributed case”, IMA J. Appl. Math. 50 (1993) 285–306.CrossRefGoogle Scholar
[38]Zhang, D. K., Sujanti, W. and Chen, X. D., “A low-temperature oxidation study using wire-mesh reactors with both steady-state and transient methods”, Combustion and Flame (1998), (in press).Google Scholar