浅谈液化天然气系统

简介了液化天然气的生产流程、运输工具以及液化天然气站的各组成设备 ,还较详细地介绍了给液化天然气汽车加气的有关设备     

The role of consequence modeling in LNG facility siting

Liquefied natural gas (LNG) project modeling focuses on two primary issues, facility siting and the physical layout of element spacing. Modeling often begins with an analysis of these issues, while ensuring code compliance and sound engineering practice. The most commonly performed analysis involves verifying compliance with the siting provisions of NFPA 59A, which primarily concern property-line spacing (offsite hazard impacts). If the facility is located in the US, compliance with 49 CFR 193 is also required. Other consequence modeling is often performed to determine the spacing of elements within the facility (onsite hazard impacts). Often, many issues concerning in-plant spacing are addressed with the guidance provided in Europe's LNG standard, EN-1473. Spacing of plant buildings in relation to process areas is also a concern as analyzed using the approach given in API RP 752. Studies may also include probabilistic analysis, depending on the perceived risk and cost of mitigation.     

LNG低温输送管路的绝热保冷

从绝热性能、外形尺寸与重量、施工工艺、制造成本及维护、使用寿命五个方面对PUH、PUB改性聚氨酯泡沫塑料包覆绝热与真空多层绝热的低温液体管道输送进行了比较,分析了各自在使用上的优势与不足。     

空分装置利用LNG冷量的热力学分析

简介了LNG冷量用于空分装置的实际例子及其节能效果 ;从空分装置液化率改变和压力改变两方面对利用LNG冷量的空分装置进行了热力学分析 ;最后指出 ,空分装置利用LNG冷量可达到多产液体、节省投资和运行费用的效果。     

150万m~3/d液化天然气工厂技术分析

2004年我国建成投运了目前国内规模最大的基本负荷型液化天然气(LNG)工厂,文章对该工厂的天然气预处理、天然气液化、液化天然气储存和液化天然气配送系统工艺流程进行了技术分析。     

液化天然气应用的基础研究

介绍液化天然气 (LNG)应用基础研究的目的、意义和内容 ,侧重介绍了天然气液化流程的热力学研究和液化天然气储存非稳性的研究。简述了各项研究的内容和成果     

A summary of some experimental data on LNG safety

In a recent paper, Luketa-Hanlin reviewed the information in the public domain related to LNG safety. The purpose of this paper is to supplement that work by providing a summary of the experimental information that Advantica has collected on LNG behaviour over the course of the last 30 years. This summary includes previously unpublished information obtained as a result of a number of collaborative projects. Subjective comments are also made on the status of modelling for each of the topic areas and, in a discussion, views are provided on those areas where there are currently gaps that may have a major impact on evaluating the individual or societal risks associated with LNG operations.     

Formal safety assessment based on relative risks model in ship navigation

Formal safety assessment (FSA) is a structured and systematic methodology aiming at enhancing maritime safety. It has been gradually and broadly used in the shipping industry nowadays around the world. On the basis of analysis and conclusion of FSA approach, this paper discusses quantitative risk assessment and generic risk model in FSA, especially frequency and severity criteria in ship navigation. Then it puts forward a new model based on relative risk assessment (MRRA). The model presents a risk-assessment approach based on fuzzy functions and takes five factors into account, including detailed information about accident characteristics. It has already been used for the assessment of pilotage safety in Shanghai harbor, China. Consequently, it can be proved that MRRA is a useful method to solve the problems in the risk assessment of ship navigation safety in practice.     

液化天然气(LNG)的冷量利用

阐述了液化天然气冷量(火用)数学模型和冷量(火用)特性分析,介绍了液化天然气冷量利用的几个方面,包括发电、空气分离、制取干冰和冷库.我国液化天然气的冷量利用潜力巨大.在兴建LNG接收站时,应当重视采用该项技术,有效回收LNG的冷量,节省能源.     

采用液化天然气(LNG)冷量的液体空分新流程及其(火用)分析

提出了2种采用液化天然气（LNG）冷量的新流程,并采用Aspen　Plus对流程进行了模拟计算。空气循环膨胀制冷的液体空分流程采用LNG冷量代替了空气外循环制冷,简化了制冷系统,与原始流程相比,液态产品的单位能耗降低约49％;氮气循环膨胀制冷的液体空分流程采用LNG冷量代替了高压氮气外循环制冷,系统所需循环氮气量减少,最高运行压力从4．6MPa降低到了2．6MPa,液态产品的单位能耗降低约53％。对流程的炯分析表明,与原始流程相比,新流程制冷单元的损失大大降低,系统整体的炯效率也得到了提高,LNG冷量回收用于空分流程制冷系统有利于节约生产成本,降低能耗,提高系统能量利用效率。     

The trans-critical heat transfer characteristics of LNG in a submerged combustion vaporizer under different operating pressures

It has been reported that trans-critical LNG vaporization process always occurs on the tube-side of typical submerged combustion vaporizer (SCV). In-depth analysis of this complex physical process is crucial for the stable operation of efficient SCV. In the present paper, a three-dimensional CFD numerical model was developed to analyze the flow and heat transfer characteristics of trans-critical LNG in the horizontal tube. Based on the numerical simulation results, the velocity, temperature and heat flux along the tube length were obtained. The distributions of local heat transfer coefficients under different operating pressures were also analyzed. The calculated results displayed that the representative phenomenon of “flow acceleration” occurs inside the horizontal serpentine tube. Affected by the variation of the physical properties, the heat transfer coefficient under the lower operating pressure was higher around pseudo-critical region, but decreased lower in the later field. Totally, the higher operating pressure may bring faster temperature rising and lower energy expenditure to reach the similar outlet temperature.     

天然气的全球市场和贮运发展趋势

概述全球天然气市场的发展情况,比较分析了LNG和CNG的生产、贮存和运输方式,分析世界LNG的贸易状况、方式以及发展趋势和意义,最后阐述中国当前LNG贮运设备的技术水平以及气体行业的应对措施。     

Analysis of temperature and pressure changes in liquefied natural gas (LNG) cryogenic tanks

Liquefied natural gas (LNG) is being developed as a transportation fuel for heavy vehicles such as trucks and transit buses, to lessen the dependency on oil and to reduce greenhouse gas emissions. The LNG stations are properly designed to prevent the venting of natural gas (NG) from LNG tanks, which can cause evaporative greenhouse gas emissions and result in fluctuations of fuel flow and changes of fuel composition. Boil-off is caused by the heat added into the LNG fuel during the storage and fueling. Heat can leak into the LNG fuel through the shell of tank during the storage and through hoses and dispensers during the fueling. Gas from tanks onboard vehicles, when returned to LNG tanks, can add additional heat into the LNG fuel. A thermodynamic and heat transfer model has been developed to analyze different mechanisms of heat leak into the LNG fuel. The evolving of properties and compositions of LNG fuel inside LNG tanks is simulated. The effect of a number of buses fueled each day on the possible total fuel loss rate has been analyzed. It is found that by increasing the number of buses, fueled each day, the total fuel loss rate can be reduced significantly. It is proposed that an electric generator be used to consume the boil-off gas or a liquefier be used to re-liquefy the boil-off gas to reduce the tank pressure and eliminate fuel losses. These approaches can prevent boil-off of natural gas emissions, and reduce the costs of LNG as transportation fuel.     

Performance improvement of nitrogen expansion liquefaction process for small-scale LNG plant

Liquefaction of natural gas is usually a kind of high energy consumption process. Therefore, any performance improvement of the liquefaction process will definitely reduce the energy consumption. Nitrogen expansion liquefaction process is regarded as a suitable process for small-scale LNG plant due to its simplicity, quick startup and convenient maintenance. However, the disadvantage of the process is high-energy consumption. An efficient way to lower its energy consumption is to add a precooling cycle. In this paper, two different precooling cycles including propane precooling cycle and R410a precooling cycle are proposed to the nitrogen expansion liquefaction process to improve the liquefaction process performance. Unit energy consumption as an objective function is optimized in terms of several key operating parameters. Based on the optimization results, the effects of the liquefaction rate and methane recovery rate on the process performance are investigated. The thermodynamic analyses are adopted to the processes as well as the two precooling cycles. Furthermore, the exergy analyses of the main equipment are also presented and discussed. The results show that the unit energy consumption for the nitrogen expansion process with R410a precooling and with propane precooling reduce by 22.74% and 20.02% respectively, compared with nitrogen expansion process without precooling.     

大型常压LNG贮罐的国产化探讨

大型常压液化天然气贮罐的开发和建造正逐步实现国产化,开发初期的问题值得大家共同探讨。文章对LNG的性质、国内外LNG大型贮罐现状、贮罐结构形式、贮罐流程组织、附件的选择及标准的遵循等方面进行了阐述。     

液化天然气(LNG)冷能用于斯特林发动机和燃气轮机的联合系统研究

利用LNG冷能具有较好的节能潜力和经济效益,通过流程的创新设计,提出了一种将LNG冷能用于燃气轮机和斯特林发动机的联合系统。基于热力学第一、第二定律,对联合系统进行热力学分析,结果表明:在环境温度35℃条件下,联合系统的输出功率为5715.48kW,热效率为31.62%,效率为43.65%;相比燃气轮机系统和直接冷却进气系统,联合系统的输出功率分别提高了7.84%和0.78%,热效率分别提高了3.16%和1.18%,效率分别提高了4.23%和1.63%。联合系统在不同环境温度下,可将燃气轮机的进气温度降低10℃左右,系统的输出功率和效率随着进气温度的降低均有所提高。     

Spread of large LNG pools on the sea

A review of the standard model of LNG pool spreading on water, comparing it with the model and experiments on oil pool spread from which the LNG model is extrapolated, raises questions about the validity of the former as applied to spills from marine tankers. These questions arise from the difference in fluid density ratios, in the multi-dimensional flow at the pool edge, in the effects of LNG pool boiling at the LNG–water interface, and in the model and experimental initial conditions compared with the inflow conditions from a marine tanker spill. An alternate supercritical flow model is proposed that avoids these difficulties; it predicts significant increase in the maximum pool radius compared with the standard model and is partially corroborated by tests of LNG pool fires on water. Wind driven ocean wave interaction has little effect on either spread model.     

Improving pilots' risk assessment skills in low-flying operations: the role of feedback and experience

Risk assessment is one of the most important skills that pilots are expected to acquire to ensure the safe and successful management of flight. The traditional approach to the development of these skills requires pilots to directly engage with potentially hazardous events. Using low-flying as a context, the present study sought to test whether engagement with hazards in a simulated environment, together with feedback concerning performance, would improve pilots' risk assessment during a subsequent simulated test flight. The results indicated that engagement with the hazards, rather than the provision of feedback per se, was associated with behavior that reduced the risk to the aircraft, while maintaining operational performance. It was concluded that exposure to hazards within a simulated environment could provide the basis for the development of risk assessment skills amongst less experienced pilots.     

铝合金液化天然气罐式集装箱的设计

液化天然气罐式集装箱是运输液化天然气的重要设备。文章介绍了铝合金液化天然气罐式集装箱的设计参数,针对罐体内筒主体材料采用铝合金复合材料及焊接结构进行探讨,并分析了内筒采用5083铝合金的效益优势。