Fire hazard of titanium powder layers mixed with inert nano TiO2 powder

Chunmiao Yuan; Jingzhi Cai; Paul Amyotte; Chang Li; Yajie Bu; Kangfu Liu; Gang Li

doi:10.1016/j.jhazmat.2017.12.010

Fire hazard of titanium powder layers mixed with inert nano TiO₂ powder

J Hazard Mater. 2018 Mar 15:346:19-26. doi: 10.1016/j.jhazmat.2017.12.010. Epub 2017 Dec 6.

Authors

Chunmiao Yuan¹, Jingzhi Cai², Paul Amyotte³, Chang Li⁴, Yajie Bu², Kangfu Liu⁵, Gang Li²

Affiliations

¹ Key Laboratory of Ministry of Education on Safe Mining of Deep Metal Mines, Northeastern University, Shenyang 110819, China; State Key Laboratory of Explosion Science and Technology, Beijing Institute of Technology, Beijing 100081, China. Electronic address: yuanchunmiao@mail.neu.edu.cn.
² Key Laboratory of Ministry of Education on Safe Mining of Deep Metal Mines, Northeastern University, Shenyang 110819, China.
³ Department of Process Engineering & Applied Science, Dalhousie University, 1360 Barrington Street, P.O. Box 15000, Halifax, NS, B3H 4R2, Canada.
⁴ Department of Civil Engineering, Shenyang Jianzhu University, Shenyang 110168, China.
⁵ Department of Civil Engineering, Shenyang Jianzhu University, Shenyang 110168, China; FAW-Volkswagen Automotive Co., Ltd., Changchun 130011, China.

PMID: 29232613
DOI: 10.1016/j.jhazmat.2017.12.010

Abstract

Metallic dust layers are highly sensitive to ignition from common ignition sources, even when mixed with high percentages of inert solids. In turn, dust layer fires are a potential ignition source for dust explosions or other damaging fires. Flame spread velocity (FSV), as a potential parameter for evaluating fire hazard, was investigated for titanium powder layers mixed with inert nano TiO₂ powder in both natural convection and in forced airflow conditions. Increased mass percentage of nano TiO₂ powder decreased FSV of Ti powder mixtures as expected. The mixing ratio of nano TiO₂ to fully suppress layer fires was 80% and 90% for micro and nano Ti powder, respectively. Mechanisms governing flame spread across a layer of nano Ti powder differed from those of a layer of micro Ti powder. FSV in no airflow conditions was higher than in aided airflow for micro Ti powder because conduction was the dominant heat transfer mechanism. However, FSV in no airflow was lower than in opposed airflow for nano Ti powder because convection/radiation was the dominant heat transfer mechanism. A fly fire phenomenon contributed to greater FSVs and higher fire hazard with nano Ti powder mixtures under aided airflow conditions.

Keywords: Dust explosion; Dust layer; Flame spread velocity; Layer fire; Metallic dust.

Publication types

Research Support, Non-U.S. Gov't