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Title: The characterisation of vented dust explosions and their effect on structures
Author: Colwell, Sarah
ISNI:       0000 0004 2701 6811
Awarding Body: London South Bank University
Current Institution: London South Bank University
Date of Award: 2000
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The risk of dust explosions affects many industries. The range of particulate substances that are explosible is very wide; it includes natural products such as grain dust and sugar, synthetic materials such as pharmaceuticals and metal powders such as aluminium and magnesium. One of the earliest recorded dust explosions occurred in a Bakery in December 1785 and it was not until the nineteenth century, that the mechanisms of dust explosions were recognised and that research programmes were established to investigate this phenomenon. Explosion relief venting is a commonly used form of explosion protection, employed in a wide range of industries, to protect vessels and production units from the overpressures generated by dust or gas explosions. Considerable research has been undertaken on the control of the internal explosion pressure by relief venting and this has resulted in the production of a number of guidance documents for the use and sizing of explosion relief vents. However, the safe use of explosion relief vents requires that buildings and process plant be designed, constructed and sited in such a way that the pressure generated from vented explosions will not cause unacceptable damage. In spite of this, there is very little published guidance relating to the pressure and flames effects resulting from the vented explosion and how their magnitude can be estimated and what measures should be taken to minimise them. Based on a full-scale experimental programme involving over three hundred vented Maize starch and Coal dust explosions in chamber volumes of 20 m3 and 40 m3, this thesis provides techniques for characterising the external effects of vented dust explosions and assessing their effect on brick and steel structures in the surrounding environment. The structural response and loading data was obtained by using both specifically designed, brick and steel targets, which were representative of current UK building design, located directly in-line with the vented explosions and by using buildings already within the laboratory structure. In all cases these buildings were instrumented to provide information on both their structural characteristics and response to applied loads. By using this data comparisons were also made on the characteristics of the pressure time curves observed in complex geometries located away from the direct venting line with the results obtained in the direct venting line. Appendix A4 offers guidance to industry based on the findings from this research. Based on the results from the experimental study, a number of numerical techniques for predicting the response of structures were assessed. This work showed that many of the current methods were not applicable to this work as they were developed to study the response of complex steel structures, unrepresentative of typical building designs, subjected to relatively high pressure internal gas explosion loading scenarios. The methods identified for predicting the response of brickwork buildings to explosions were designed around vented gas explosions with simple impulse loading characteristics. It has been shown that these tools were unable to predict the structural response of the brickwork buildings to the vented dust explosions in this study with any degree of accuracy although they appear to offer a basis for future development.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available