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In this study, a shear-stiffening composite porous material (PU@CS) was developed using the dipping-drying technique, with polyurethane (PU) as the substrate. PU@CS not only overcomes the cold flow drawbacks of shear-stiffening gel (SSG) but also significantly enhances the mechanical properties of PU (with a one-order-of-magnitude increase in maximum storage modulus). The introduction of multi-walled carbon nanotubes (MWCNTs) overcomes the electrostatic aggregation drawback of PU. Due to its outstanding shear hardening effect, PU@CS exhibits superior explosion-proof compared to PU, and when filled to a length of 50 cm, it achieves complete quenching of hydrogen gas explosion flames, with a maximum explosion overpressure attenuation ratio of 87.2%. This work provides data support for the application of SSG in the field of explosion protection. [Display omitted] • Shear stiffening gel was applied in the explosion-proof for the first time. • The shear-stiffening composite explosion-proof material was prepared. • PU@CS has excellent antistatic properties and its explosion-proof mechanism is revealed. [ABSTRACT FROM AUTHOR]

A self-built gas explosion testing platform was used to explore the quenching effect of flame-retardant polyurethane foam on a gas explosion. The effect of the foam's filling position and length on the explosion suppression performance was explored. The results demonstrate that polyurethane foam exhibits an excellent flame-quenching performance, with a minimum of a 5 cm length of porous material being sufficient to completely quench the flame during propagation. Furthermore, the attenuation function of this porous material on the pressure wave is insignificantly affected by the change in ignition energy. Compared with the explosive state of the empty pipeline, the best suppression effect is obtained when the polyurethane foam is 20 cm in length with a filling position at 1.8 m, and the maximum explosion pressure and maximum rise rate are attenuated by 86.2% and 84.7%, respectively. This work has practical significance for the application of porous materials in explosion suppression and explosion-proof technologies in the chemical industrial processing and oil (gas) storage fields. [ABSTRACT FROM AUTHOR]

This work explores the possibility of ammonium polyphosphate (APP) as the inhibitor for starch dust deflagration. The flame propagation behaviors of starch dust samples are investigated in a half-closed vertical duct. Flame images and temperature are recorded by high speed camera and fine thermocouples, respectively. The high speed photographs indicate that flame propagation and flame luminous intensity of starch dust at the initial stage are greatly suppressed by APP. Maximum temperature values are also significantly decreased by APP. Thermal decomposition behavior and kinetics of starch samples are studied to ascertain the influence of APP on the decomposition activation energy. The combustion heat release of starch samples are tested by pyrolysis combustion flow calorimetry. Inhibition mechanisms of APP on starch dust deflagration are concluded according to the results of flame propagation, thermal decomposition kinetics and heat release. This work proposes a new strategy for exploration of inhibition mechanisms of dust explosion. Image 1 • Flame propagation behaviors of starch dust deflagration were investigated. • Thermal decomposition kinetics of starch samples were studied. • The inhibition mechanisms of APP on starch dust deflagration were ascertained. [ABSTRACT FROM AUTHOR]

Experiments of partial inerting on flame propagation of starch dust deflagration in a vertical duct were conducted to reveal the differences in flame structure evolutions. Particle pyrolysis and combustion behavior combined with time scale analysis are used to discuss the flame inerting mechanism. The results showed that the inerting process makes the flame front fuzzy, discrete and irregular. The thickness of flame reaction zone increases as O 2 concentration decreases, while the preheat zone decreases accordingly. The pyrolysis rate always controls the flame propagation process under inerting conditions. With the decrease of O 2 concentration, the control effect of pyrolysis rate is gradually weakened, and the effect of combustion reaction rate on flame propagation appears. A physical model of starch dust flame propagation under partial inerting is established, and the inerting process of dust pyrolysis and combustion on the flame structure evolution is further revealed. Unlabelled Image • Partial inerting on dust flame structures has been experimentally investigated. • Inerting significantly influences thermal pyrolysis and gas products release. • Thickness of combustion reaction zone increases in the low oxygen levels. • Suppression mechanism is revealed. [ABSTRACT FROM AUTHOR]

Lysine sulfate (LS) powder is at high risk of fire and explosion during its production, processing and storage. Considering its edible and nutritive values, the selection for its explosion inhibitor requires both excellent inhibition performance and environmental friendliness. The inhibition performance of a natural food additive of sodium phytate (SP) on LS dust deflagration is investigated by comparing it with ammonium polyphosphate (APP), which is a widely used flame retardant. The deflagration characteristics of LS mixtures with various mass fractions of SP and APP are recorded by high-speed photography and fine thermocouples. The combustion heat is tested by micro-scale combustion calorimetry. Thermal stability of samples are studied by using a synchronous thermal analyzer. The results show that the deflagration of LS dust is completely suppressed when the mass fractions of APP and SP increase to 2% and 8%, respectively. The corresponding inhibition mechanisms are proposed based on the dust deflagration macroscopic results and microcosmic analysis on thermal decomposition products and residuals. These findings may provide a solution to reduce the probability and damage of dust explosions. [ABSTRACT FROM AUTHOR]

• Ceramic foam damages the spread of wheat dust flame and the flow field in pipeline. • Temperature of upper end is proportional to aperture, but inversely to layers. • The pressure increases and then decreases with the increasing PPI and layers. • The effect of ceramic foam on combustion pressure is more manifested as incentive. A vertical dust combustion pipeline with high-speed photography, micro-thermocouple and pressure sensor was built to investigate the influence of ceramic foam on the wheat dust explosion flame. Ceramic foams with different parameters were adopted in this paper, and compared with metal mesh. The chemical structures of dust explosion residue were characterized by X-ray photoelectron spectroscopy. Results indicate that the wheat dust flame propagation and structure were significantly destroyed by ceramic foam. With the decreasing aperture or increasing layer, the blocking effect of ceramic foam was aggravated on the dust flame. The flame cannot pass through the ceramic foam with 20 PPI and 3 layers. On the upper end of ceramic foam, the flame temperature is positively proportional to the aperture but inversely proportional to the layers. With the PPI and layers of ceramic foam increases, the combustion pressure firstly increases and then decreases when the dust combustion intensity is strong. Ceramic foam shows the incentive effect to some extent on the combustion pressure, but the continuous inhibition effect is found for the metal mesh. [ABSTRACT FROM AUTHOR]

(NH 4) 2 HPO 4 is widely used in industrial product as a typical additive. To reveal the inhibition of (NH 4) 2 HPO 4 on the wheat dust explosion, a vertical pipeline was built to study the explosion of wheat dust with different particle size distribution under the addition of (NH 4) 2 HPO 4. The characteristics of wheat dust explosion were recorded by high-speed photography, ion probe and micro-thermocouple. The pyrolysis behaviors of wheat dust and (NH 4) 2 HPO 4 were investigated by simultaneous thermal analyzer, and the explosion residues were characterized by FTIR and XPS. The results indicate that the flame propagation distance, velocity and temperature were significantly decreased under 25% (NH 4) 2 HPO 4 , and the wheat dust explosion was significantly inhibited. In the explosion reaction zone, the ion current increases and then decreases with the content of (NH 4) 2 HPO 4 increases. Furthermore, the inhibition mechanism of (NH 4) 2 HPO 4 on wheat dust explosion was presented by analyzing the samples and residues of wheat dust explosion. Unlabelled Image • (NH 4) 2 HPO 4 can inhibit the explosion flame of wheat dust. • The ion probe was adopted to diagnose the explosion reaction zone of wheat dust. • The samples and residues of dust explosion were characterized. • Inhibition mechanism of (NH 4) 2 HPO 4 were summarized by the explosion characteristics. [ABSTRACT FROM AUTHOR]

Dust explosion accidents frequently occur in dedusting pipes of wheat dust, causing huge casualties and property losses. In this paper, a vertical pipeline of combustion experimental platform was established to obtain the effects of working conditions and double-layer wire mesh parameters on wheat dust flame propagation. The results show that the double-layer wire mesh has an obvious suppression effect on the flame propagation of wheat dust. At the combination of the same mesh number, both the peak flame temperature and the maximum flame propagation velocity decreased with the increasing of the mesh number, and the flame quenching phenomenon occurs at 80 mesh. At the combination of different mesh numbers, the flame temperature at the upper-density and lower-sparseness combination is lower than that at the upper-sparseness and lower-density combination under all working conditions. The flame temperature difference (ΔT) gradually increases with the increasing of mesh number difference, and the maximum ΔT appears at the mesh difference of 40 mesh. As the separation distance increases, the flame temperature rises, and the suppression effect is best at the separation distance of 1 cm. The peak combustion pressure is negatively linear with the separation distance. Image 1 • Double-layer wire mesh has an obvious suppression effect on the flame propagation. • Upper density and lower sparseness have a better suppression effect than upper sparseness and lower density. • Flame temperature rises with the increasing of wire mesh separation distance. [ABSTRACT FROM AUTHOR]

• Structural and propagating features of wood dust explosion flame is investigated. • Flame intensity of dust explosion is significantly decreased by ultrafine Mg(OH) 2. • Composite suppression mechanism of ultrafine Mg(OH) 2 on explosion flame is studied. • Some characteristics of nano-powders improve suppression effect of nano-Mg(OH) 2. The suppression effects of ultrafine Mg (OH) 2 powders with different particle sizes and mass fractions on explosion flame of wood dust are experimentally studied in a half-closed vertical experimental duct. Flame structures and characteristic parameters, including flame light emission images, propagation velocity, temperature, during the flame propagation of wood dust explosion are recorded by high-speed photography and fine thermocouple. Thermal decomposition behaviors of wood dust and Mg(OH) 2 powders are studied using synchronous thermal analyzer. Chemical structures of residual dust samples after the explosion are characterized by Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy. The experimental results show that explosion flame of wood dust is obviously suppressed by physical and chemical effects of Mg(OH) 2 powders, and the suppression effect of nano-Mg(OH) 2 is better than that of micron-Mg(OH) 2 under same mass fractions. By analyzing multiple characteristics of nano-powders, the advantages of nano-Mg(OH) 2 over micron-powders are further investigated. [ABSTRACT FROM AUTHOR]