Validation of FLACS against experimental data sets from the model evaluation database for LNG vapor dispersion

This paper discusses the performances of LNG vaporizers usually used in practice, it is very import to improve the functions of LNG vaporizer because the liquefied natural gas (LNG) must be heated and gasified when it is used, then analyses the advantages and disadvantages of these LNG vaporizers. This paper studies and designs creatively a new type of LNG vaporizer which uses a method of flue gas lashing and sending up spray, and puts forward the basic requirements and the design project of this vaporizer. Some techniques such as the gas flow circle unit, the inner and outer cylinders of combustion chamber, the flue gas nozzle of cone, the flue gas circulation, the automatic filling water system and so on are used in this LNG vaporizer. These techniques are creative and advanced, and the authors have had the intellectual property rights. The advantages of this LNG vaporizer are high efficiency, quickly starting up, fast gasified speed, compact structure, saving energy, protecting environment and so on. This LNG vaporizer is suitable for the independent small or middle scale areas which can not be contained into the large natural gas supplying networks for various reasons, the loads fluctuating largely areas in which the natural gas supplied loads are regulated in time, and supplied or stopped frequently, the particular areas in which the special parameters of natural gas must be needed.

Liquefied Natural Gas (LNG) is an important component in meeting the future energy needs of the United States and other industrialized countries. The ability to locate (produce), process, liquefy, transport, and re-gasify stranded natural gas is vital to maintaining a stable long-term natural gas supply necessary for sustained economic growth [1]. Two of the key components in this supply chain are the vaporization of the LNG at the import terminal and the peak shaver trains that liquefy pipe line natural gas, store it and then vaporize the liquid to feed the gas to the pipe line when additional flow is required. This paper outlines a novel approach incorporating a traditional fired heater with waste heat recovery to vaporize LNG at an import terminal or peak shaver train while maintaining a high thermal efficiency. A comparison is made between the new technology and more conventional methods, with emphasis on emissions. Some of the advantages and disadvantages associated with the design and implementation of these systems are explored in this presentation. As a fundamental cannon of ethics, engineers are obligated to address the most efficient and responsible use of resources. The environmental impact of supplying the necessary natural gas energy to industry and consumers is significant. This paper addresses these aspects as considered during the development of the alternative LNG vaporization technology.

In the present study, a Computational Fluid Dynamics (CFD) model was set up to analyse the dynamic behaviour of LNG (Liquefied Natural Gas) tanks adopted in heavy trucks refuelling stations in normal operating conditions or during process upsets. The CFD model was based on the Volume-Of-Fluid (VOF) method to simulate the transient behaviour of a multi-phase flow in a 100 m3 vertical cylindrical tank. The model first considered a fully insulated vessel, and subsequently it was modified to take into account possible damages of the insulation layer, this being a critical upset scenario. The CFD model allowed predicting the dynamic pressure build up in the damaged tank, thus obtaining key indications for the evaluation of the vessel mechanical resistance and set up of safety measures. The model also provided the prediction of vapor temperature with respect to time and external heat source, that is a key issue to assess the effectiveness of the thermal insulation.

A Micro Cogeneration System with LNG Cold Utilization-part 2: Exergy Analyses

Developing a CFD heat transfer model for applying high expansion foam in an LNG spill

Blanketing effect of expansion foam on liquefied natural gas (LNG) spillage pool

Application of computational fluid dynamics for LNG vapor dispersion modeling: A study of key parameters

The global demand of liquefied natural gas (LNG) has risen rapidly in recent years for the reasons of energy security and sustainable development. This has led to considerable recent research interests and efforts in the LNG production chain and associated risks in handling, storage, and transport of LNG, largely driven by the intrinsic process safety issues of LNG, potential terrorist threats, and public confidence in LNG safety. This review presents an overview on some recent advances in the LNG value chain, covering upstream gas production and gathering, liquefaction, shipping, and regasification processes. Recent developments in the experimentation and modeling of LNG spills associated with the LNG value chain are then summarized, covering the events following a LNG spill, including LNG pool formation, vapor dispersion, and combustion. The consequent hazards and safety issues are also discussed, with a focus on the methods for improving the safety of personnel, facilities, and ships. The key technical gaps in the related research areas have been identified, and future research directions are outlined.

The increasing demand to comply with new environmental regulations has caused liquefied natural gas (LNG) to be considered as an emerging potential fuel in high speed vessels. According to the SOLAS convention, damage stability calculations indicated that no damage should extend inside the line of breadth divided by five (B/5) of a vessel. To this end, the location of the LNG tanks on a high speed ferry is a key aspect; hence, the potential consequences due to an unintentional LNG release must be carefully addressed and their associated adverse impacts are to be fully assessed. This study aims at developing a risk-based approach through which the locations of LNG tanks are determined, considering the potential consequences associated with the accidental release of LNG, i.e. overpressure due to vapour cloud explosion and/or thermal radiation due to fire. The explosion overpressure is modelled by implementing the empirical approach multi-energy (ME) method. The fire heat radiation is simulated by the application of both empirical (solid-flames model) and computational fluid dynamic (CFD) code, fire dynamic simulator (FDS). Probit functions are used to define the human hazards caused by either explosion overpressure or fire heat radiation. Introducing a score scheme for different hazards and risks due to different impacts is defined. The final risk is estimated by the summation of each impact. The decision making on the optimum location of the LNG tank is performed based on the final risk profile on the vessel. Implementing the proposed methodology on a typical high speed LNG vessel proved the LNG tank located on the roof of a vessel has the minimum cumulative risk; hence, it is confirmed as the optimum location. It should be noted that this is the location based on the risk of the accidents; however, other factors affecting the operation of a vessel does not consider which may affect the final decision.

Liquid cargo storage tanks of liquefied natural gas (LNG) carriers are designed by strict standards to maintain the cryogenic state (−163 °C). For most LNG cargo storage tanks, it is mandatory to install a system that can safely store leaked fluid for 15 days in the case of leakage of liquid cargo due to crack of the insulation system. To ensure safety, it is necessary to predict the amount of LNG spilling from the cracks in the insulation panels. Although international regulations are provided, they rely on a conservative and consistent coefficient. In this study, experimental and numerical methods were applied to examine the design factor used to predict the flow rate in the tank design process. To check the amount of leakage that occurs under pressure conditions of LNG tanks, an experiment was conducted using crack specimens and pressure containers filled with water. In order to simulate the leakage of LNG, the amount of leakage was predicted using the Computational Fluid Dynamics (CFD) method. The distribution of leakage quantity was investigated according to the shape of the crack through the pressure vessel experiment and the analysis. Through CFD analysis, the leakage rate of LNG was calculated for each operating pressure condition through the crack. Finally, the results of this study examined the need to identify and reconsider the coefficients due to international guidelines and other factors in calculating orifice coefficients applied to the design of LNG tanks.

Liquefied natural gas (LNG) is commonly converted from liquid to vapor for gas distribution. One of the methods for vaporizing LNG is to use a shell and tube heat exchanger. Water is used on the shell side to provide the heat source and LNG is then vaporized through the tube side passages of the exchanger. In many of these applications, the LNG is at a high pressure on the tube side while the water is at a lower pressure than the LNG as it flows through the shell side. The industry consensus document API 521 [1] “Guide to Pressure Relieving and Depressuring Systems,” Fourth Edition, paragraph 3.18 “Heat Transfer Equipment Failure” states that a complete tube rupture is to be considered for the possible overpressure of the equipment. The typical shell and tube exchanger application described above has rupture discs on the shell body to protect the shell from being over-pressured due to a tube rupture scenario. The possible freezing of the water in the shell due to mixing with cryogenic LNG is a concern. The issue to consider is whether freezing will occur before the rupture discs can safely relieve a possible over-pressure condition of the shell. A numerical analysis of the condition was performed using Computational Fluid Dynamics (CFD) software. The exchanger service, the analysis procedure and the conclusions found are detailed in this paper.

The liquefied natural gas (LNG) industry employs a variety of release prevention and control techniques to reduce the likelihood and the consequences of accidental LNG releases. A study of the effectiveness of these release prevention and control systems is being performed. Reference descriptions for the basic types of LNG facilities were developed. Then an overview study was performed to identify areas that merit subsequent and more detailed analyses. The specific objectives were to characterize the LNG facilities of interest and their release prevention and control systems, identify possible weak links and research needs, and provide an analytical framework for subsequent detailed analyses. The LNG facilities analyzed include a reference export terminal, marine vessel, import terminal, peakshaving facility, truck tanker, and satellite facility. A reference description for these facilities, a preliminary hazards analysis (PHA), and a list of representative release scenarios are included. The reference facility descriptions outline basic process flows, plant layouts, and safety features. The PHA identifies the important release prevention operations. Representative release scenarios provide a format for discussing potential initiating events, effects of the release prevention and control systems, information needs, and potential design changes. These scenarios range from relatively frequent but low consequence releases to unlikely but large releases and are the principal basis for the next stage of analysis.

In this paper, three passive methods for the generation of swirl flow in the supersonic separator (3S) were investigated, and their structures were optimized by computational fluid dynamics (CFD) modeling. The influence of the structural and operational parameters on the dew point depression, phase envelope diagram, rate of natural gas liquid (NGL) recovery, and separation efficiency have also been evaluated. The collection efficiency was significantly improved for the nozzle equipped with the passive swirler compared with the simple nozzle. The selection of passive swirler type played a crucial role in the natural gas liquefaction and separation. The side injected swirler, and serpentine swirler showed the most significant improvement in separation efficiency than the U-turn swirler. For the side injected swirler at the optimum injection angle, the maximum collection efficiency was about 89% at the pressure loss ratio (PLR) of 0.2. Besides, the simulation results demonstrated that for the serpentine 3S, with the increase in serpentine twist number, the highest improvement on the collection efficiency of the investigated nozzle was obtained. In addition, it was observed that, when the convergent section profile was designed according to the Witoszynski line-type, a larger refrigeration zone was obtained than other considered profiles.

Numerical investigation of flammable vapour cloud formation from pools of heated organic liquids

Application of CFD (Fluent) to LNG spills into geometrically complex environments