Characterization of Thermal Stability and Heat Absorption for Suppressant Agent/Combustible Dust Mixtures via Thermogravimetric Analysis/Differential Scanning Calorimetry

Abstract

Combustible dusts continue to present a critical threat toward personnel and process equipment in a wide variety of bulk solids processing industries. The addition of noncombustible inert material to combustible dust mixtures, either through premixing or high-rate injection as the flame front begins to develop, is common practice for preventative inhibition or explosion protection via active suppression, respectively. Metal dusts in particular present an extremely reactive explosion risk due to amplified heat of combustion, burning temperature, flame speed, explosibility parameters (K St and P max ), and ignition sensitivity. Establishment of proper prevention and mitigation designs for metal fuel deflagrations has posed challenging. The aim of this paper is to propose a method for the characterization of the inhibition efficiency of five suppressant agents (sodium bicarbonate [SBC], potassium bicarbonate [PK], monoammonium phosphate [MAP], diammonium phosphate [DAP], and sodium chloride-based [Met-L-X]) when mixed with both organic (cornstarch) and metallic (zinc) fuels. For each 1:1 wt % fuel/agent mixture, thermal stability and heat absorption have been evaluated using thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC).

Characterization and properties of high-temperature resistant structure adhesive based on novel toughened bismaleimide resins

“…The thermal stability of the co-polymerization systems was assessed by TGA in nitrogen atmosphere. 33,34 The thermal degradation behavior was characterized in term of the initial decomposition temperature (T i ), the temperatures of 5%, 10% and 50% weight loss (T 5% , T 10% , T 50% ), the temperature of maximum rate of decomposition (T max ) and the char yield at 800 C, and the corresponding data were compiled in Table 2. Seeing from Figure 7, the co-polymerization systems exhibit similar decomposition behavior and all have good thermal stability.…”

Mitigation of Iron and Aluminum Powder Deflagrations via Active Explosion Suppression in a 1 m3 Sphere Vessel

“…Analogous analytical studies on zinc powder combustion directly support claims of amplified chemical inhibition due to alignment of the agent decomposition range with the fuel oxidation temperature range. 8 Prior to suppression testing on a large scale, appropriate measures were taken to assess the toxicity concerns associated with heating a substantial quantity of metal/inhibitor mixture to high burning temperatures. To appropriately identify the agent decomposition volatiles, TGA-DSC experiments were performed, with evolved gas analysis via mass spectrometry The intensities of these evolutions are trivial relative to other evolved species.…”

“…Confirmed through TGA, the majority of MAP sample mass loss occurs from 500 to 750°C, directly atop the iron powder combustion region (see the TGA profile for MAP; Supporting Information, Figure B-2). 8 Such overlap is theorized to prompt an amplified chemical inhibition effectiveness due to the dilution of oxygen content on the particle surface and increased competition for radical intermediates (•O, •OH, •H), which would otherwise 8 Primary endothermic agent decomposition of SBC and Met-L-X, however, occurs outside of the iron powder oxidation window, as confirmed through suppressant agent TGA profiles (Supporting Information, Figures B-1 and B-3, respectively), such that the agents are able to operate solely through physical inhibition mechanisms as a result of their solid-state heat capacity and oxygen dilution mechanisms.…”

“…As investigated by Reding and Shiflett through the thermogravimetric and differential scanning calorimetry analysis of zinc powder oxidation, the overlap of the fuel combustion temperature region and the agent decomposition range seems to allow for increased consumption of free combustion radicals, amplified chemical inhibition effect, and increased heat absorption. 8 A greater degree of overlap results in a kinetically dampened combustion rate and inhibited volatilization of surrounding fuel particles in the preheat zone. Selection of inert materials with increased chemical inhibition could allow for lower agent concentrations required to achieve equivalent total suppressed pressures (TSPs) within the equipment being protected.…”

Mesoporous Hydrophobic Silica Nanoparticles as Flow-Enhancing Additives for Fire and Explosion Suppression Formulations

“…33 The successful use of mesoporous materials in other areas was previously confirmed. 34,35 Park et al discovered that mesoporous silica can be successfully used as an adsorbent of chemical warfare agents. 36 Ni et al demonstrated that nanocomposites consisting of porous 4A zeolite and the gaseous extinguishing agent 2-bromo-3,3,3trifluoropropene significantly improve the characteristics of an ordinary dry NaHCO 3 powder at a relatively short extinguishing time and with a lower number of agents.…”