Ignition characteristics of amino acid powders

Abstract

Herein, the ignition characteristics, including the minimum ignition energy (MIE) and minimum explosible concentration (MEC), of amino acid powders (L-leucine, L-valine, L-threonine, L-alanine, and L-serine) were experimentally investigated. The MIE and MEC values of branched-chain amino acid (BCAA) powders were much lower than those of the other powders such as L-threonine, L-alanine, L-serine and glycine powders. In particular, the MEC values for the BCAAs were constant, notwithstanding increasing particle size. The plateau range of BCAA particle size was wider than that of the other carbonaceous particles tested. Pyrolysis of the powders and the resultant pyrolyzates were investigated by thermogravimetry (TG) and the pyrolysis-gas chromatography-mass spectrometry (PyGCMS). A number of flammable materials were formed from the BCAAs, compared with the other amino acids tested. In addition, the propagating flame structure was discussed and different flame structures for the BCAAs were observed depending on the particle size distribution. The flame front for relatively small particle sizes was continuously smooth, whereas that for relatively large particle sizes was discrete. These results indicated that the BCAAs are sensitive to ignition and exhibit a high risk of dust explosion during the manufacturing process.