Process Safety and Environmental Protection最新文献

Polyphenylene ether (PPE), used in the production of copper-clad laminate resin, can emit methane and ethane at elevated temperature during the aforementioned production process. Moreover, a cloud of PPE dust can form during the feeding process. Both these scenarios can lead to a dust or inflammable gas explosion at the feed port. This study investigated the explosion characteristics of PPE in air, methane, and ethane atmospheres by using 20-L apparatus. The study findings revealed that the presence of methane and ethane lowered the minimum explosive concentration of PPE dust. In air, the minimum explosion concentration was 40 g/m³, which decreased to 30 and 22 g/m³, respectively, in the presence of methane and ethane. However, the addition of these gases also increased the severity of explosions from St-2 to St-3. Furthermore, the thermal depolymerisation of PPE dust was examined. PPE was discovered to undergo thermal depolymerisation when heated, releasing a substantial quantity of inflammable gases. These gases, in combination with oxygen, can form an explosive mixture, expanding the explosion range. Moreover, these inflammable gases exhibit various degrees of toxicity, posing substantial health and safety risks to workers involved in PPE manufacturing.

Deeming about incessant consumption and disposal of pharmaceutical antibiotics in natural water bodies, this study demonstrates the synthesis of a novel Tulsi leaves (Ocimum Sanctum) derived carbon dots modified Z-scheme g-C₃N₄/CoFe₂O₄ heterojunction system. Characterization techniques namely XRD, FT-IR, XPS, FE-SEM, HR-TEM and EDX supported composite formation. Fabricated catalysts presented excellent photocatalytic performance towards removal of sulfamethoxazole (SMX). UV–vis DRS, PL and EIS findings suggested the augmented visible light absorption capability, suppression of electron-hole pairs recombination and effective separation of charge carriers which were accountable for degradation process. Probable mechanistic pathway for SMX removal was photo-Fenton assisted with Z-scheme separated electron-hole pairs via activation of H₂O₂, where hydroxyl radicals (•OH) were main reactive species. Additionally, the prepared material was employed as electrochemical sensor for individual as well as simultaneous detection of SMX and trimethoprim with quite impressive detection limits of 0.042 µM and 0.047 µM, respectively.

This paper presents a thermo-economic assessment of a novel geothermal integrated system enhanced by a fuel cell. The proposed system leverages the advantages of geothermal energy resources, featuring a sustainable and environmentally friendly solution for power generation and district heating applications. Integrating a fuel cell and thermoelectric within the geothermal system aims to improve overall system performance and energy efficiency by converting waste heat into electricity. A detailed mathematical model of the integrated system is developed, incorporating various performance parameters, component efficiencies, and thermo-economic considerations. The model is applied to simulate the system's performance under different operating conditions and parameters. Additionally, sensitivity analyses are conducted to evaluate the effects of key design variables on the system's performance, cost, and environmental impacts. The results indicate that the newly developed system generates 95594 kW of electricity with a total exergy destruction rate of 4616 kW. The electricity cost rate also obtained 0.309 $/kWh. The energy efficiency of the introduced system is 24.08 % and the exergy efficiency is 26.7 %. Comparison with the basic system represents that energy efficiency shows a 15.71 % improvement.

Lithium-ion batteries are susceptible to fires and explosions due to thermal runaway, a serious safety hazard. This study explores the potential of using hydrated inorganic salt (TCM40) composite phase change materials to prevent thermal runaway in battery packs. TCM40 composites stand out due to their exceptional thermochemical heat storage capacity, which allows them to effectively absorb excess heat during runaway events. The research investigates how thermal conductivity, thermal storage capacity, and cell spacing influence the propagation of thermal runaway. The findings demonstrate that TCM40 composites, with a thermal storage density exceeding 1000 kJ/kg, are significantly more effective in preventing thermal runaway compared to traditional latent heat storage phase change materials with lower capacities. To gain a comprehensive understanding of thermal runaway mitigation, a combined thermal management model was developed. This model integrates a battery thermal runaway model with a kinetic model describing the decomposition of TCM40 composites. The analysis reveals that the high heat absorption capability of TCM40 composites minimizes heat transfer to neighboring cells during thermal runaway. Furthermore, the model provides valuable insights into the synergistic effects of thermal conductivity and heat storage capacity on runaway propagation. This knowledge can be directly applied to design safer battery packs, even for compact configurations where cell spacing is less than 2 mm. This study offers significant advancements in both thermal protection materials and design strategies for lithium-ion battery packs. These advancements have the potential to significantly improve battery system safety and minimize the risk of explosions.

The extensive utilization of plastic in daily life has significantly contributed to per-day waste generation. The conversion of waste plastic through pyrolysis into fossil fuel is a promising solution to waste management and energy crises. The precise control of the process parameters in the pyrolysis would be a sustainable business model. Since the optimization of process parameters for production yield and the physicochemical properties of waste plastic oil have been underexplored. So, the current research optimized input process parameters of pyrolysis through response surface methodology using a central composite design. The input parameters of the experimental design were reaction temperature (350°C-550°C), retention time (60–300 min), nitrogen flow rate (0–40 ml/s), and ZSM-5 catalyst concentration (1–5 wt%). Waste plastic is converted into the optimized yield of oil (85 %), solid (3 %), and syngas (12 %). Waste plastic oil (WPO) had optimal results of physicochemical properties like heating value (48 MJ/kg), flash point (60 °C), kinematic viscosity (2.1 mm²/s), and density (820 kg/m³). American Society for Testing and Materials Standards validated the produced WPO, which had better fuel properties than petroleum diesel. However, the application of other sustainable biocatalysts and uncondensed gas may be explored in future research.

This study presents a comprehensive thermodynamic assessment of a trigeneration plant producing electricity, fresh water through multi-effect desalination (MED), and cooling through an absorption refrigeration cycle. The MED and absorption refrigeration systems utilize the rejected heat from the power cycle, driven by concentrated solar power (CSP). Situated in Qatar, the present system leverages the abundant solar irradiance to optimize the efficiency of electricity generation, water desalination, and cooling. The design features parabolic trough collectors with synthetic oil as the heat transfer fluid, direct thermal storage, and a Rankine steam turbine cycle with three turbine stages. The system also incorporates phase change materials (PCMs) based thermal energy storage (TES) to improve the system performance and offset the mismatch between demand and supply. The present system evaluation is based on energy and exergy analyses, while the Aspen Plus is used to simulate the power production and desalination operations, providing detailed insights into its efficiency and potential for large-scale implementation. The proposed system operates with an energy efficiency of 56.72 % and an exergy efficiency of 31.24 %, respectively.

Investigating the explosive characteristics of H₂/n-C₄H₁₀ mixtures is crucial for the safe utilization of this blended fuel. Our study focused on varying equivalent ratios and hydrogen blending ratios within a closed 20-L spherical explosion vessel. Additionally, the microscopic kinetics of the reactions were analyzed through chemical reaction simulation. Our findings indicate that the most violent explosion occurred at an equivalent ratio of 1.2. Increasing hydrogen content intensified combustion reactions, reducing flame thickness and inducing cellular structures along the flame front. This escalation also increased explosion pressure, flame temperature, and flame propagation speed, elevating explosion risk. Moreover, the equilibrium molar fraction of O₂ and CO₂ decreased while that of H₂O increased with higher hydrogen blending ratios. Correspondingly, the heat release rate and generation rates of H•, O•, and OH• radicals increased. Notably, the peak time of C₂H₄ and CH₄ consumption rates preceded. Additionally, R5: O₂ + H• = O• + OH• and R978: C₄H₁₀ + H• = SC₄H₉ + H₂ represented crucial promoting and inhibiting steps, respectively. These insights deepen our understanding of the explosion mechanism of H₂/n-C₄H₁₀ mixtures, providing a theoretical basis for designing safer protective measures and evaluating explosion risks in industrial production.

Metagenomic sequencing technology was applied to evaluates the microbial diversity, functional activity, and synergistic relationships during the anaerobic fermentation process of landfill leachate and weathered coal, aiming to assess the key metabolic pathways in the combined anaerobic fermentation process of leachate and weathered coal. The results indicate that co-fermentation significantly enhances the production of biogenic methane. Furthermore, co-fermentation promotes the abundance of Paracoccus that involved in the degradation of organic pollutants, and enriches methane-producing archaea such as Methanothrix and Methanoculleus. Significant increases in carbohydrate enzymes such as lignin-degrading enzyme AAs, as well as GH2, GH43, GT4. The relative abundance of genes related to toluene degradation in co-anaerobic fermentation is 2.5 times and 1.3 times that of singular weathered coal and landfill leachate, respectively. The addition of leachate promotes the metabolic pathway of acetate conversion to methane. This research provides mechanistic studies on the treatment of waste leachate and weathered coal, and provides new ideas for environmental protection and clean energy.

Atmospheric oxidation is one frequently–used method to immobilize arsenic-bearing wastewater as nonhazardous scorodite. Its kinetic research is indispensable for improving synthesis on an industrial scale. In this study, the kinetic for the conversion from ionic Fe(II) and As(V) solution to scorodite was elaborately researched and discussed based on temperature–dependent experiments and software calculations. This work was divided into three parts. In experiments, scorodite synthesis was based on the optimal conditions of initial pH 2.0, 20 g/L of As, Fe/As molar ratio 1.4, O₂ flow rate 0.5 L·min⁻¹ at 95℃ for 12 h. Moreover, scorodite is developed from polymerization and oxidation determined by solution pH, residual [As] and [Fe(II)] with the precipitate phase transformation observed by X–ray diffraction and scanning electron microscope. In kinetic analysis, the activation energy of Fe(II)–As(V) polymerization and oxidation varied at 33.81–435.27 kJ·mol⁻¹ and 52.66–599.25 kJ·mol⁻¹, respectively, calculated from Arrhenius equation based on the established matrix equation solved by Matlab software. In synthetic improving, the whole process is comprised of atmospheric polymerization at 90 ℃ for 1.5 h followed by pressurized oxidation at 130 ℃ and P_O2=1.5 MPa for 3 h as the rate constants of polymerization far outweighs that of oxidation. In general, this kinetic research is reliable and can be applied to other arsenic immobilization from arsenic–bearing solution. The improved synthesis for scorodite is more advanced in reaction duration and oxygen utilization for potential industrial application.

Flame acceleration in rough narrow channel was experimentally studied for the mixtures of hydrogen with air and acetylene with air. The experiments were carried out in a 7 by 7 mm smooth channel or a channel with one or two opposite walls covered with sandpaper which had a grain size of 100 μm or 500 μm. Using high-speed schlieren and self-luminance visualization several flame acceleration regimes were discovered depending on the channel roughness and composition of the combustible mixture. In all cases, the highest maximum flame velocity was observed in rough channels. Detonation was also obtained only in the rough channels, despite the smaller effective channel size when using sandpaper. It was found that the maximum flame velocity and DDT distance depended non-linearly on the channel blockage ratio (BR). The highest flame velocity and the shortest transition to detonation were recorded at BR of 0.035. At highest BR of 0.16, detonation was not recorded in any of the combustible mixtures used. Using schlieren diagnostics, it was discovered that disturbances of the unburned mixture occur above the rough surface, which lead to an increase in pressure ahead of the flame front. The occurrence of detonation was also detected near the rough surface.