Short Communication Effect of particle size reduction due to dust dispersion on minimum ignition energy (MIE) Pranav Bagaria a , Ben Hall a , Ashok Dastidar b , Chad Mashuga a, ⁎ a Mary Kay O'Connor Process Safety Center, Artie McFerrin Department of Chemical Engineering, Texas A&M University, College Station 77843-3122, USA b Fauske & Associates, LLC, IL 60527, USA abstract article info Article history: Received 2 May 2019 Received in revised form 29 July 2019 Accepted 14 August 2019 Available online 16 August 2019 The 20-L dust explosion apparatus is widely used for dust explosion risk assessment, however the 1-m 3 appara- tus remains the gold standard for explosion testing by generating a turbulent dust cloud consistent with indus- trial scenarios. Recent studies show a 1-m 3 dispersion leads to particle breakage, which can impact risk assessment. However, the effect of particle breakage on explosion risk assessment is not quantified. The focus of this work is to measure particle breakage in a 1-m 3 and to quantify the effect of resulting particle size distribution shift on the explosion risk assessment by measuring change in the minimum ignition energy (MIE). We observed Ascorbic Acid particle size reduction in a 1-m 3 , resulting in a reduced post-dispersion MIE as com- pared to the pre-dispersion sample. This work aims to create awareness of dust particle breakage to improve the risk assessment process, to better prevent incidents. © 2019 Elsevier B.V. All rights reserved. Keywords: Dust explosion Minimum ignition energy Particle size distribution 1-m 3 dust explosion apparatus 1. Introduction Dust explosion is a challenging problem for solids handling and pro- cessing industries. Dust explosion incidents have been occurring on a frequent basis (N1 major incident per month from1980–2012), causing multiple injuries, fatalities, and property loss [1]. Numerous statistics [2–4] demonstrate the seriousness of the dust explosion problem, the need for increased awareness and the importance of accurate risk as- sessment. Dust explosion risk assessment is conducted based on stan- dards defined by organizations such as ASTM International, ISO etc. [18,19]. These standards mention the use of the 20-L and the 1-m 3 appa- ratus for measuring the explosion parameters (P max ,K st ), which account for the resulting explosion pressure and rate of pressure rise. The stan- dard 20-L dust explosion apparatus is widely used for dust explosion testing due to its smaller volume and easy operability. However, the 1-m 3 apparatus remains the gold standard of dust explosion testing due to its larger volume, which better simulates the dust cloud genera- tion scenarios in process industries, resulting in more realistic data [5,6]. In fact, the 20-L apparatus is calibrated to yield similar results to that of the 1-m 3 apparatus [7]. Although the 1-m 3 apparatus has its advantages, a recent study [8] showed dust dispersion in the 1-m 3 apparatus could lead to dust particle breakage due to dispersion cloud turbulence similar to that in the 20-L apparatus [5,7,15,42–47]. Particle breakage in the 1- m 3 apparatus can have significant implications on dust explosion testing. Since the explosion parameters vary with particle size [16,17,20–40], size reduction due to dispersion in 1-m 3 apparatus can lead to misleading results due to the association of the explosion param- eters with the pre-dispersion particle size distribution [8,16]. This can result in an erroneous dust explosion risk assessment. In addition, since the 1-m 3 apparatus depicts industrial dust cloud generation sce- nario, particle breakage in the 1-m 3 apparatus shows turbulent cloud generation either due to an incident pressure wave, or a processing step (cyclone, dryers etc.) can cause dusts to break. The breakage gener- ates dust with a higher surface area, thereby increasing the risk of explo- sion in a facility. The aim of this work (as outlined in Fig. 1) is to quantify the particle breakage in the 1-m 3 apparatus to demonstrate that dispersion cloud in an industrial facility can cause particle breakage. In addition, this work will quantify the increased dust explosion hazard due to particle break- age by measuring the shift in the MIE (Fig. 1). This is important to study as the 1-m 3 apparatus represents the dust cloud formation scenario in the process industries, and any particle breakage in the 1-m 3 apparatus and its consequent effect on explosion parameters can affect the risk assessment. 2. Experiment 2.1. Apparatus This study used a 1-m 3 dust explosion apparatus to demonstrate particle breakage due to dust dispersion and cloud turbulence in an in- dustrial facility. The 1-m 3 apparatus [Fig. 2] consists of two air nozzles Powder Technology 356 (2019) 304–309 ⁎ Corresponding author at: 3122 TAMU, Room 205, Artie McFerrin Department of Chemical Engineering, Texas A&M University, College Station 77843-3122, USA. E-mail address: mashuga@tamu.edu (C. Mashuga). https://doi.org/10.1016/j.powtec.2019.08.030 0032-5910/© 2019 Elsevier B.V. All rights reserved. Contents lists available at ScienceDirect Powder Technology journal homepage: www.elsevier.com/locate/powtec