Dust explosion, one of the most serious and wide spread explosion hazards, which is recently a topic of concern for the developed countries are not even identified as a serious threat in developing countries. In this paper we present a review on the concept of dust explosion, by critically reviewing the work done in this domain, a brief on the equipment used for studying this field, followed by possible directions this research could be furthered in.

Dust Explosion: A Review

Despite extensive research and efforts in handling and mitigation of dust explosion, accidents involving dust explosion take place. The mention of dust explosion in the literature dates to 1785, but industry professionals from oil and gas are unaware of this hazard. An incident is reported leading to the demise of two workers while attempting to unload barite powders. The process industry is highly dependent on powdered chemicals which are used as an additive in drilling fluid and cements such as barite, bentonite, calcium carbonate, lead sulphides, NaOH, etc. The explosive behaviour of these dusts can be determined with the help of the Kst values. The Kst value is dependent on the confinement, dispersion of particles, size of the dust particle, the source of ignition, and presence of free oxygen. Usually, an experimental setup of 20L sphere with two different types of nozzles i.e., perforated annular nozzle or rebound nozzles are majorly used to calculate the value of Kst. While the setup is being prepared at our end, this work presents a comparison of the performance of these nozzles using Computational Fluid Dynamics (CFD) as a tool, to understand the different parameters of dispersion, and the impact they have on the dust explosion.

Comparative analysis of critical factors for nozzle consideration in dust explosion testing: Comparative analysis of critical factors for nozzle consideration in dust explosion testing

Dust is common in process industries that manufacture, store and handle particulate material. More than half of dusts processed in industries are combustible. Explosive dust clouds can be generated from most organic materials, many metals and even some non-metallic inorganic materials. Studies have reported techniques to control explosions occurring in coal mines and other process industries and such occurrences in varied locations due to different types of dusts, point to the fact that this issue needs further investigation. Industrial practices in India are similar to developed countries but information relevant to dust explosion occurring in India is almost negligible as the type of explosion remains uninvestigated. Further, use of nanoparticles and nano-dusts in upstream oil and gas industry is increasing significantly. Under conducive conditions, storage, transport and pumping down nanoparticles downhole can be considered to be potentially vulnerable situations, leading to explosions with catastrophic consequences, not only financial but including human loss. It is difficult to eliminate dust explosion, but it can be mitigated using different methods. Such events can be prevented if technical safety parameters of dust are known. One of the important measures is the determination of worst case explosion overpressure and provision of blast resistant walls or structural components. This work investigates the dust explosion characteristics of nano-dusts, by taking into account the settings and the circumstances in which the dust is being accumulated. In order to study these changing characteristics of dust particles from an explosion as well as a technical safety perspective, a mathematical model is developed to determine a practical solution for screening in terms of an equation and demonstrate that the equation is doing fair against the experimental data. Various types of nano-dusts and their explosions are simulated using the constructed model. A sensitivity analysis for all the relevant critical parameters is undertaken with this model, after it has been validated with experimental data. The model represents explosions carried out using both micro-powders as well as nano-powders, which can assist the end-user in estimating the approximate value of overpressure and thus, in turn would largely govern further handling and analysis.

Adnan Deshmukh

Papers

Mathematical Modelling and Analysis of Nano-dust Explosion

Assessment of Explosion Hazards Associated with Nano-Powders