Risk Analysis on Spontaneous Ignition of Soy Sauce Squeezing Residue

摘要

A number of serious fires caused by spontaneous ignition have occurred frequently in Japan. The soy sauce manufacturing is mainstay industry of Choshi where Chiba Institute of Science has been established. There would have occurred fires caused by soy sauce squeezing residue (SSSR), although no report is available on such fires. Our group has started to elucidate the possibility of SSSR fires. In this paper, presented are the results of studies on the spontaneous ignition behavior of SSSR. Thermo-gravimetric characteristics of those samples were examined, and possibility of the spontaneous ignition of each sample is discussed. Based on the results of discussion, a spontaneous ignition tester (SIT) was developed, with which the apparent activation energy Ea and spontaneous ignition temperature Tc can be easily determined. Further, the critical ignition temperature (equivalent to To) of the SSSR is theoretically estimated on the basis of the FrankKamenetskii's theory of thermal explosion, and the relation between the Tc and the amount of each sample is elucidated.