The navigation course of Liquefied Natural Gas (LNG) carriers and fueled ships may cross vulnerable areas where commercial, civil, and industrial assets are present. Despite the effort made by ...scientific community and authorities, there are no consolidated methodologies addressing the risks arising from the interaction between LNG carriers and fueled ships accessing ports and onshore facilities. This work focuses on the development of a simplified methodology for risk assessment of LNG carriers and fueled ships in port areas able to identify accident scenarios involving the ship course and vulnerable targets. The analysis starts verifying the compliance with respect to the port regulations and the feasibility of the course with respect to the channels. Then, based on standard features of LNG carriers and fueled ships, a set of reference accidental scenarios to be considered during the risk assessment is identified. A specific guidance for the identification of hazards, estimation of frequencies and consequences is provided, finally adopting a customized risk matrix to support decision-making on prevention and mitigation measures. The application of the methodology to a real case study dealing with an important Italian harbor, highlights the capability of the method to support land use planning.
•Effects on onshore facilities due to LNG coursing, docking and onboard operations.•Reference accidental scenarios are identified and ranked using a risk matrix.•Compliance with respect to port-specific legislation is integrated.•Case-specific recommendations on risk prevention and mitigation.
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•LNG is re-gasified in two different ways during peak and off-peak times.•High-grade LNG cold energy is used for air liquefaction to enhance power generation.•Pressures of LNG ...vaporization and liquid air storage are minimized to 7 and 0.15 MPa.•The highest specific daily net power output is achieved at 85.7–94.8 kJ/kgLNG.•The economic advantages of the process are shown over other types of integrations.
Power plants for regasification of liquefied natural gas (LNG), integrated with liquid air energy storage (LAES), have benefits in terms of power generation flexibility to match the electricity demand profiles and increased operating profits from electricity arbitrage. However, issues with the flexibility and safety of this integration still remain. In addition, further improvements in power generation were identified from the use of high-grade LNG cold energy in LAES. Thus, this paper proposes a novel and advanced integration (denoted as LNG-LAES) for enhancements in flexibility, safety, and power generation. LNG is re-gasified in two different manners: it flows into a parallel two-stage regenerative Rankine cycle for conventional power generation during peak times or transfers high-grade cold energy to LAES for energy storage during off-peak times. Pressures of LNG vaporization and liquid air storage are minimized to 7 and 0.15 MPa to achieve an inherently safer design. The process assessment is performed considering possible demand and marketing scenarios, in which the LNG-LAES process exhibits the best performance in terms of power generation and economic benefits. In the base-case, the specific daily net power output increases up to 94.8 kJ/kgLNG and the electrical round trip efficiency of LAES achieves 129.2%. Moreover, the LNG-LAES process has design flexibility that the amount of LNG cold energy utilized in LAES can be varied at the design stage to maximize the operating profit corresponding to a specific electricity market scenario. The analyzes demonstrate that the proposed LNG-LAES process is both technically feasible and economically preferable for industrial applications.
Information about the solubility of benzene in light hydrocarbons is particularly important for the prediction of freeze-out risk in LNG production. Engineering models developed to predict this risk ...need to be tested against high quality experimental data covering a range of conditions to assess their validity. A visual high pressure sapphire cell, housed in a specialized cryogenic environmental chamber, was employed to measure the melting temperature of methane + benzene binary systems at temperatures from 120 K, pressures up to 22 MPa, and benzene concentrations ranging from 120 to 1012 parts per million (ppm) by mole. The results obtained were compared with literature data and the predictions of the thermodynamic model implemented in the software package ThermoFAST. These comparisons reveal that the literature data are in fact consistent with each other, and with the measurements and predictions made in this work, within their experimental scatter. ThermoFAST was able to represent the melting temperatures obtained for benzene concentrations of 1012 and 199 ppm with r.m.s deviations of 0.7 and 3.4 K, respectively. At 120 ppm and 6.3 MPa, the measured solid-liquid equilibrium (SLE) temperature deviated from the ThermoFAST prediction by less than 2 K. However, at the higher temperature conditions representative of solid vapour equilibrium (SVE), the data measured for mixtures with concentrations at 199 and 750 ppm benzene deviated from the model predictions by up to 5 K.
This paper is to evaluate the LNG bunkering safety for a 50,000 dead weight tonnage bulk carrier renowned as the world first LNG fueled bulk carrier. To establish a proper level of the safety zone ...against the potential risk of gas release from the LNG bunkering systems encompassing from truck to ship, it introduces an enhanced quantitative risk assessment process with two key ideas: firstly, the integration of the population-independent analysis with the population-dependent analysis, and secondly, the combination between the probabilistic analysis and CFD simulation for gas dispersion. Research results reveal that the appropriate levels of the safe zone can be set at 28.8 m in 1E-4/year criterion that concerns the individual risk of a fatality at the given distance to the risk source of 1 in 10,000 years, whereas at 46.6 m (in 1E-5/year criterion) and at 213.3 m (in 1E-6/year criterion) when the area within 5% and higher gas concentration in air is regarded the critical zone. On the other hand, in case of the critical area considered to be within 2.5% and higher gas concentration in air, the safety zone will much expand to 34.9 m (in 1E-4/year criterion), 80.4 m (in 1E-5/year criterion) and 541.8 m (in 1E-6/year criterion). These dissimilarities suggest that LNG bunkering ports pay attention to selecting appropriate safety criteria which would considerably change the range of safety zones. The case study also demonstrates the effectiveness of the proposed approach that can remedy the shortcomings/shortfalls of existing technical and regulatory guidance on establishing the zones. It is, therefore, believed that the risk assessment approach proposed in this paper can contribute to determining the appropriate level of safety zones whereas providing practical insight into port authorities and flag states.
•The excellence of the enhanced risk assessment method was presented.•The potential risk of LNG gas dispersion was investigated.•Research findings gave an insight into the proper approach for quantitative risk assessment.•Practical guidance on establishing the extent of safety zone for LNG bunkering was presented.
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