Suppression of Maize Dust Explosions

Abstract

The results of a systematic series of maize (corn) dust explosion suppression trials in vessel volumes of 6.2, 10, and 25 m3 are presented. Tests are reported for explosions of both medium and high turbulence dust clouds. The four suppressants, Halon 1011, ammonium phosphate powder, water, and halon/powder hybrid, were tested. The ammonium phosphate powder proved to be significantly more effective than the other suppressants. In the case of highly turbulent maize dust explosions, the halon suppressant catastrophically failed to suppress the incident. Suppression effectiveness is shown to be more dependent on the speed of deployment of the suppressant agent than on the absolute concentration delivered into the vessel. Thus, deployment of suppressant from a larger number of smaller suppressors results in a lower suppressed explosion pressure. The criteria for the limits of effectiveness of a given suppression system are defined and the experimental results compared with a theoretical estimate of the expected suppressed explosion pressure. It is shown that there is a reasonable correspondence between the theoretical estimate and corresponding experimental measurement and concluded that a theoretical model can be used as a basis for the design of effective explosion suppression systems for industry.

Understanding dust explosions. The role of powder science and technology

“…Moore (1987) discussed the results of his own comprehensive experimental and theoretical research, which resulted in a logical basis for systematic design of industrial suppression systems. He introduced the concept of a critical mass M t of suppressant that is just sufficient for suppressing the flame when evenly distributed throughout the flame volume.…”

Numerical and experimental investigation of the morphology development of expansion clouds by a powder jet flow

“…The momentum transfer from the continuous phase to the particle phase is computed by examining the change in momentum of a particle as it passes through each control volume, this momentum change is computed by equation (3).…”

“…Eckhoff [2] gives a detailed description of the suppression process. To date, most of the research carried out in this field has focused on experimental work [3]. However, the time consuming and expensive nature of experiments carried out in this area mean that computational studies of the processes taking place will become more important.…”

“…It is generally the case that for a particular type of nozzle to be effective, it needs to fill as much of the volume to be protected as quickly as possible. Preliminary trials [3] have shown that selection based purely on the basis of the pattern of dispersion is an effective way of choosing a nozzle for a given application.…”

Understanding Dust Explosions. The Role of Powder Science and Technology

“…Moore [30] discussed the results of his own comprehensive experimental and theoretical research, which resulted in a logical basis for systematic design of industrial suppression systems. He introduced the concept of a critical mass M, of suppressant that is just sufficient for suppressing the flame when evenly distributed throughout the flame volume.…”