Research on the Rule of Explosion Shock Wave Propagation in Multi-Stage Cavity Energy-Absorbing Structures.

The propagation laws of explosion shock waves and flames in various chambers were explored through a self-built large-scale gas explosion experimental system. The propagation process of shock waves inside the cavity was explored through numerical simulation using Ansys Fluent, and an extended study was conducted on the wave attenuation effect of multiple cavities connected in a series. The findings show that the cavity's length and diameter influenced the weakening impact of shock waves and explosive flames. By creating a reverse shock wave through complicated superposition, the cavity's shock wave weakening mechanism worked. By suppressing detonation creation inside the cavity, the explosive flame was weakened by the cavity's design. The multi-stage cavity exhibited sound-weakening effects on both shock waves and explosive flames, and an expression was established for the relationship between the suppression rate of shock force and the number of cavities. Diffusion cavities 35, 55, 58, and 85 successfully suppressed explosive flames. The multi-stage cavity efficiently reduced the explosion shock wave. The flame suppression rate of the 58-35 diffusion cavity explosion was 93.38%, whereas it was 97.31% for the 58-35-55 cavity explosion. In engineering practice, employing the 58-58 cavity is advised due to the construction area, construction cost, and wave attenuation impact.

Regeneration mechanism of a novel high-performance biochar mercury adsorbent directionally modified by multimetal multilayer loading.

Biochar that is directly obtained by pyrolysis exhibits a low adsorption efficiency; furthermore, the process of recycling adsorbents is ineffective. To solve these problems, conventional chemical coprecipitation, sol-gel, multimetal multilayer loading and biomass pyrolysis coking processes have been integrated. After selecting specific components for structural design, a novel high-performance biochar adsorbent was obtained. The effects of the O2 concentration and temperature on the regeneration characteristics were explored. An isothermal regeneration method to repair the deactivated adsorbent in a specific atmosphere was proposed, and the optimal regeneration mode and conditions were determined. The microscopic characteristics of the regenerated samples were revealed along with the mechanism of Hg0 removal and regeneration by using temperature-programmed desorption technology and adsorption kinetics. The results show that doping multiple metals can reduce the pyrolysis reaction barrier of the modified biomass. On the modified surface of the sample, the doped metals formed aggregated oxides, and the resulting synergistic effect enhanced the oxidative activity of the biochar carriers and the threshold effect of Ce oxide. The optimal regeneration conditions (5% O2 and 600 °C) effectively coordinated the competitive relationship between the deep carbonization process and the adsorption/oxidation site repair process; in addition, these conditions provided outstanding structure-effect connections between the physico-chemical properties and Hg0 removal efficiency of the regenerated samples. Hg0 adsorption by the regenerated samples is a multilayer mass transfer process that involves the coupling of physical and chemical effects, and the surface adsorption sites play a leading role.