Zhaowen Wang

Conducting a safety simulation assessment of gas release from the vent mast during the design stage holds significant importance for ship design and system operation safety on LNG-powered vessels. Based on a large-scale practical LNG-powered vessel, this paper employs the CFD method to carry out a safety assessment of the natural gas dispersion, and proposes an optimization design method to address the issue where the vent mast height of large-scale LNG-powered vessels fails to meet specifications. The influencing factors of gas dispersion are discussed. The simulation results indicate that the vent mast height, wind direction, and wind velocity significantly affect the gas dispersion behavior. A lower vent mast height results in a greater risk of flammable gas clouds accumulating on the deck surface. Hazards analysis of the 6 m vent mast condition with windless suggests that a cryogenic explosion hazard zone is formed on the deck centered around the mast position, with the maximum gas concentration reaching 30% and the minimum temperature below −55 °C. The gas cloud spreads along the wind direction, and the extension distance is positively correlated with wind speed. With the increase in wind velocity, the height and volume of flammable gas clouds decrease. When the wind speed is 15 m/s, the volume of the flammable gas cloud is less than half of that at 5 m/s and less than one-tenth of that at 0 m/s. Higher wind velocity can notably promote gas diffusion.

LNG is considered a promising alternative fuel for the marine industry with the increasingly strict environmental requirements while the safety problems caused by LNG leakage accidents need to be concerned and analyzed. In this article, the cryogenic safety analysis of the fuel gas preparation room in an LNG-powered ship during LNG leakage accidents was performed by CFD simulations. The simulation results showed as follows: the range of cryogenic region in the fuel gas preparation room was related to flow field direction during LNG leakage; The surface temperature of equipment dropped to some extent during LNG leakage accidents. The temperature drop was less than 15°C, which was confirmed to be a safe temperature range in engineering; In addition, for safety operation analysis, the NG distribution situation of dangerous regions with explosive limit was also obtained.

When considering resource shortages and environmental pressures, salvaging valuable metals from the cathode materials of spent lithium-ion batteries (LIBs) is a very promising strategy to realize the green and sustainable development of batteries. The reductive acid leaching of valuable metals from cathode materials using methanol as a reducing agent was studied. The results show that the leaching efficiencies of Co and Li are 99% under optimal leaching conditions. The leaching kinetics of cathode materials in a H₂SO₄–methanol system indicate that the leaching of Co and Li is controlled by diffusion, with activation energies of 69.98 and 10.78 kJ/mol, respectively. Detailed analysis of the leaching reaction mechanism indicates that methanol is ultimately transformed into formic acid through a two-step process to further enhance leaching. No side reactions occur during leaching. Methanol can be a sustainable alternative for the reductive acid leaching of valuable metals from spent LIBs due to its high efficiency, application maturity, environmental friendliness, and low cost.

The design of electrolyte systems suitable for room-temperature electrochemical extraction of Li, Mg, Al, Ti, rare earth elements, and other active metals from their salts or oxides has long been a scientific challenge. Herein, we report an exceptional organic solvent (1,3-dimethyl-2-imidazolidinone) supported by LiNO₃ with properties superior to those of conventional ionic liquids and show that it is well suited for room-temperature potentiostatic deposition of La coatings from LaCl₃ on high-purity Al substrates. Thus, this work paves the way to cost-effective La extraction and presents an innovative approach to the selection of electrolyte systems used for electrodeposition of active metals.