Comparison of two schemes for district cooling system utilizing cold energy of liquefied natural gas

Two schemes（scheme Ⅰ and scheme Ⅱ）for designing a district cooling system（DCS）utilizing cold energy of liquefied natural gas（LNG）are presented.In scheme Ⅰ,LNG cold energy is used to produce ice,and then ice is transported to the central cooling plant of the DCS.In scheme Ⅱ,return water from the DCS is directly chilled by LNG cold energy,and the chilled water is then sent back to the central plant.The heat transportation loss is the main negative impact in the DCS and is emphatically analyzed when evaluating the efficiency of each scheme.The results show that the DCS utilizing LNG cold energy is feasible and valuable.The cooling supply distance of scheme Ⅱ is limited within 13 km while scheme Ⅰ has no distance limit.When the distance is between 6 and 13 km,scheme Ⅱ is more practical and effective.Contrarily,scheme Ⅰ has a better economic performance when the distance is shorter than 6 km or longer than 13 km.

Distribution and Chain Pattern of Liquefied Natural Gas Industry in China

The production and consumption of natural gas in China has been developing rapidly in recent years.It is expected that the annual growth rate of the demand for natural gas will reach 12% in the next 15 years,and the gas consumption in the primary energy will increase from 0.3% to 10% or more by 2020.However,since the supply of natural gas cannot satisfy the requirements,China has begun to build liquefied natural gas(LNG)terminals in the coastal regions such as Guangdong and Fujian,and solve this problem by importing LNG from foreign countries.LNG needs to be transported by LNG ships from abroad.With the rapid growth of global gas production,the volume of LNG trade also increases,and the interregional production increased from 0.3% in 1970 to 26.2% in 2004.So,we need LNG ships more than before.This article puts forward the distribution of LNG ships and the speculation of the future of LNG transportation based on the studies on foreign LNG production,the LNG trade,the building of LNG ships,the LNG transportation,the chain model of LNG distribution,etc.

Socio-Economic Implication of Nigeria Liquefied Natural Gas (NLNG) Project in Bonny Local Government Area, Rivers State, Nigeria

Notably, the Nigeria Liquefied Natural Gas (NLNG) project is the pioneer Liquefied Natural Gas (LNG) plant in Nigeria, aimed at both the diversification of the petroleum industry and utilization of the vastly flared natural gas resources of the nation. However, large scale energy projects have been known to generate both positive and/or negative impacts. Environmental Management Plans (EMP) have often been the compendium of information on approved mitigations, which normally include activities that could maximize the benefits of the host communities, and it’s not unusual for the Community Development and Corporate Social Responsibility (CDCSR) department of such an organization to be saddled with these contributions. But the activities of Nigeria LNG Ltd.’s CSR department have often been the source of criticism, as well as aspiration for improvement by host communities and other stake holders. This article thus aims to present a comprehensive compendium of NLNG’s CDCSR activities, up to the year 2010, and also highlight the level of satisfaction of the immediate and distant host communities against the level of performance of other donors in the area. Also the arrays of negative socio-economic consequences of the Nigeria LNG Ltd.’s activities were identified based on community perception. The results generally showed that comparatively, NLNG project has made more innovative positive socio-economic and health contributions to its areas of operation than the three tiers of government and other donors (including SPDC and Mobil Producing Nigeria). Surprisingly, agitations against Nigeria LNG Ltd.’s activities have not overshadowed its community development provisions, which have been of major assistance in several communities. There is however a dire need to review several aspects of Nigeria LNG Ltd.’s CDCSR activities, especially in the fulfilment of documented promises, as well as in project conception and community participation, for better completed projects acceptance by indigenous host communities. Conflict management strategies also need to be improved, while the dissatisfaction over benefits in New Finima needs to be urgently addressed.

A Novel Process for Natural Gas Liquids Recovery from Oil Field Associated Gas with Liquefied Natural Gas Cryogenic Energy Utilization

A novel process to recovery natural gas liquids from oil field associated gas with liquefied natural gas (LNG)cryogenic energy utilization is proposed.Compared to the current electric refrigeration process,the proposed process uses the cryogenic energy of LNG and saves 62.6%of electricity.The proposed process recovers ethane, liquid petroleum gas(propane and butane)and heavier hydrocarbons,with total recovery rate of natural gas liquids up to 96.8%.In this paper,exergy analysis and the energy utilization diagram method(EUD)are used to assess the new process and identify the key operation units with large exergy loss.The results show that exergy efficiency of the new process is 44.3%.Compared to the electric refrigeration process,exergy efficiency of the new process is improved by 16%.The proposed process has been applied and implemented in a conceptual design scheme of the cryogenic energy utilization for a 300 million tons/yr LNG receiving terminal in a northern Chinese harbor.

A power plant for integrated waste energy recovery from liquid air energy storage and liquefied natural gas

Liquefied natural gas(LNG)is regarded as one of the cleanest fossil fuel and has experienced significant developments in recent years.The liquefaction process of natural gas is energy-intensive,while the regasification of LNG gives out a huge amount of waste energy since plenty of high grade cold energy(-160℃)from LNG is released to sea water directly in most cases,and also sometimes LNG is burned for regasification.On the other hand,liquid air energy storage(LAES)is an emerging energy storage technology for applications such as peak load shifting of power grids,which generates 30%-40%of compression heat(-200℃).Such heat could lead to energy waste if not recovered and used.The recovery of the compression heat is technically feasible but requires additional capital investment,which may not always be economically attractive.Therefore,we propose a power plant for recovering the waste cryogenic energy from LNG regasification and compression heat from the LAES.The challenge for such a power plant is the wide working temperature range between the low-temperature exergy source(-160℃)and heat source(-200℃).Nitrogen and argon are proposed as the working fluids to address the challenge.Thermodynamic analyses are carried out and the results show that the power plant could achieve a thermal efficiency of 27%and 19%and an exergy efficiency of 40%and 28%for nitrogen and argon,respectively.Here,with the nitrogen as working fluid undergoes a complete Brayton Cycle,while the argon based power plant goes through a combined Brayton and Rankine Cycle.Besides,the economic analysis shows that the payback period of this proposed system is only 2.2 years,utilizing the excess heat from a 5 MW/40 MWh LAES system.The findings suggest that the waste energy based power plant could be co-located with the LNG terminal and LAES plant,providing additional power output and reducing energy waste.

Thermodynamic design of a cascade refrigeration system of liquefied natural gas by applying mixed integer non-linear programming

Liquefied natural gas(LNG) is the most economical way of transporting natural gas(NG) over long distances. Liquefaction of NG using vapor compression refrigeration system requires high operating and capital cost. Due to lack of systematic design methods for multistage refrigeration cycles, conventional approaches to determine optimal cycle are largely trial-and-error. In this paper a novel mixed integer non-linear programming(MINLP)model is introduced to select optimal synthesis of refrigeration systems to reduce both operating and capital costs of an LNG plant. Better conceptual understanding of design improvement is illustrated on composite curve(CC) and exergetic grand composite curve(EGCC) of pinch analysis diagrams. In this method a superstructure representation of complex refrigeration system is developed to select and optimize key decision variables in refrigeration cycles(i.e. partition temperature, compression configuration, refrigeration features, refrigerant flow rate and economic trade-off). Based on this method a program(LNG-Pro) is developed which integrates VBA,Refprop and Excel MINLP Solver to automate the methodology. Design procedure is applied on a sample LNG plant to illustrate advantages of using this method which shows a 3.3% reduction in total shaft work consumption.

Flow characteristics by particle image velocimetry in liquefied natural gas vaporizer model with several baffles

Shell-and-tube vaporizers are the most commonly used and dominated types of vaporizers in liquefied natural gas （LNG） realm. Due to efficient performance, shell-side flow in this type of vaporizers has received considerable attention and has been investigated extensively. However, the detailed flow structure in the shell needs to be determined for reliable and effective design. Therefore, the objective of this study was to clarify the flow structure in shell by particle image velocimetry （PIV）. Experiments were conducted using two types of model; 15% baffle cut having inlet and outlet positions !n the direction of 90° to the cut and 30% baffle cut having inlet and outlet positions in the direction of 180° to the cut. Each test section is 169 mm in inner diameter and 344.6 mm in length. The flow features were characterized in different baffle cuts with regards to the velocity vector field and velocity distribution. The results show that the flow characteristics of 15% baffle cut type vaporizer are comparable to those of 30% baffle cut type vaporizer.

GTL or LNG:Which is the best way to monetize "stranded" natural gas?

A large portion of world＇s natural gas reserves are ＂stranded＂ resources, the drive to monetize these resources leads to the development of gas-to-liquids （GTL） and liquefied natural gas （LNG） technologies. LNG has the advantage of having been developed for the past 40 years and having an excellent safety record. GTL on the other hand is another option with substantial benefits, but its development stage and commercial viability are far behind LNG. This paper presents a techno-economic comparison of GTL with LNG, including technical development, plant efficiency, market potential for the products, and capital cost for the infrastructure. The aim is to give an overall view on both LNG and GTL and provide a perspective on the profitability of these two technologies.

Research on the navigational risk of liquefied natural gas carriers in an inland river based on entropy:A cloud evaluation model

Due to the flammability and explosive nature of liquefied natural gas(LNG),an extremely strict process is followed for the transporta-tion of LNG carriers in China.Particularly,no LNG carriers are operating in inland rivers within the country.Therefore,to ensure the future navigation safety of LNG carriers entering the Yangtze River,the risk sources of LNG carriers’navigation safety must be identi-fied and evaluated.Based on the Delphi and expert experience method,this paper analyses and discusses the navigation risk factors of LNG carriers in the lower reaches of the Yangtze River from four aspects(human,ship,environment and management),identifies 12 risk indicators affecting the navigation of LNG carriers and establishes a risk evaluation index system.Further,an entropy weight fuzzy model is utilized to reduce the influence of subjective judgement on the index weight as well as to conduct a segmented and overall evaluation of LNG navigation risks in the Baimaosha Channel.Finally,the cloud model is applied to validate the consistent feasibility of the entropy weight fuzzy model.The research results indicate that the method provides effective technical support for further study on the navigation security of LNG carriers in inland rivers.

LNG储运安全保障技术发展与展望

中国作为液化天然气(LNG)进口大国主要通过LNG运输船运至沿海地区的LNG接收站,经气化后向内陆地区通过管道进行输送,其中,储罐和高压泵等储运关键设备发挥着核心支撑作用。本文阐述了LNG从船运到LNG接收站再进入管线输送过程中所涉及的LNG储运技术与关键设备发展状况,分析了LNG船运过程传热与蒸发抑制技术,储存、冷凝及气化等静设备以及长管线输送动力设备等关键设备的研发难点,讨论了LNG管线安全输送保障技术。提出了要进一步加强理论研究和关键技术突破,重点研发LNG储运关键设备,确保LNG储运过程的安全可靠性,实现LNG储运关键设备全部国产化和能源重大工程的自主可控发展。

LNG储罐内燃料泄漏扩散与爆燃事故特性模拟

为了定量评估液化天然气储罐泄漏意外爆燃事故的危害后果,基于ALOHA软件对天然气储罐发生泄漏时天然气的扩散以及意外点火爆燃事故特性进行了模拟,针对不同泄漏压力时,液化天然气储罐泄漏后气化产生的甲烷扩散引起的易燃区域、爆炸产生的超压和热辐射影响区域进行了计算分析。结果表明,甲烷蒸气云的最大扩散距离、爆炸产生的超压和热辐射影响范围会随着泄漏压力的增加而增大。该研究可为新建储罐区储罐间安全距离的确定、在役储罐区的安全防护以及相应应急预案的制定等提供参考。

基于多载荷联合作用的LNG船泵塔结构建模与强度分析

对液化天然气(LNG)船泵塔结构进行建模和强度分析,提升LNG船结构的安全性。构建由弹簧单元组连接泵塔主体结构与底部基座区域的“船体-泵塔”组合模型,分析液舱内液体晃荡时历运动、液体惯性力、超低温载荷的特征及计算和加载方式,提出多载荷联合作用下的LNG船泵塔结构强度分析方法。以一艘LNG实船为例,采用该方法计算得到泵塔结构的变形和应力,在此基础上分析弹簧单元数量、刚性系数和材料初始参考温度等关键参数对计算结果的敏感性。研究结果表明:提出的多载荷联合作用下的泵塔结构建模与强度分析方法符合《钢质海船入级规范》关于LNG船章节的细化实施方案和实船应用要求,采用该方法所得结果可供LNG船泵塔结构设计和校核参考。

LNG动力船燃料罐疲劳强度分析

为全面有效地执行国际海事组织发布的《使用气体或其他低闪点燃料船舶国际安全规则》(IGF规则),采用两参数Weibull分布表示应力范围的长期分布,基于IGF规则中液化天然气(LNG)等液化气体对B型燃料舱疲劳设计条件的相关要求,结合国际船级社协会和中国船级社相关规范及指南对疲劳评估规范的要求,推导出累积损伤计算的简化公式。算例表明,简化的计算方法能方便、有效地计算不同设计使用寿命(对应于总的波浪遭遇次数)和对应概率水平载荷下的液化气体B型燃料舱累积损伤度。在IGF规则要求框架下,所提算法可直接满足IGF规则要求的累积损伤计算要求。

Theory, technology and prospects of conventional and unconventional natural gas

The development of natural gas in China has entered a golden and leap-forward stage, which is a necessary bridge to clean energy. This in-depth study on the status quo, theory, technology and prospect of natural gas development shows:(1) The global remaining proven recoverable reserves of natural gas are 186×1012 m3, and the reserves-production ratio is 52.4, indicating a solid resource base for long-term and rapid development.(2) Ten formation and distribution laws of conventional and unconventional natural gas reservoirs have been proposed. In terms of exploration geology, the theory of conventional "monolithic" giant gas fields with different gas sources, and an unconventional gas accumulation theory with continuous distribution of "sweet areas" in different lithologic reservoirs have been established; in terms of development geology, a development theory of conventional structural gas reservoirs is oriented to "controlling water intrusion", while a development theory of unconventional gas is concentrated on man-made gas reservoirs.(3) With the geological resources(excluding hydrates) of 210×1012 m3 and the total proven rate of the resources less than 2% at present, the natural gas in China will see a constant increase in reserve and production; by 2030, the proven geological reserves of natural gas are expected to reach about(6 000-7 000)×108 m3, the production of conventional and unconventional natural gas each will reach about 1 000×108 m3, and the gas consumption will reach 5 500×108 m3. The dependence on imported natural gas may be 64% by 2030, and 70% by 2050.(4) Ten measures for future development of natural gas have been proposed, including strengthening exploration in large-scale resource areas, increasing the development benefits of unconventional gas, and enhancing the peak adjusting capacity of gas storage and scale construction of liquified natural gas.

面向能效设计指数的LNG燃料船CO_(2)捕集系统设计及性能分析

为满足国际海事组织(International Maritime Organization,IMO)第三阶段船舶能效设计指数(energy efficiency design index,EEDI)的要求,提出一种液化天然气(liquefied natural gas,LNG)燃料船船载碳捕集系统(onboard carbon capture system,OCCS)。OCCS通过醇胺溶液对主机烟气中的CO_(2)进行富集,并回收主机烟气余热用于醇胺溶液再生,再利用LNG汽化过程中释放的冷能对解吸出的CO_(2)进行液化。以一艘Kamsarmax型船为例,构建基于冷热能综合利用的OCCS模型,分析烟气质量流量、溶剂质量流量和吸收塔进口处的贫液温度对CO_(2)捕集量及比热耗的影响。结果表明:提高贫液温度能够有效减少热量消耗,烟气和溶剂质量流量对CO_(2)捕集量影响显著,当溶剂质量流量大于18000 kg/h时,OCCS能满足IMO第三阶段的CO_(2)减排要求。该船通过所设计的OCCS可以满足IMO第三阶段EEDI的要求,其比热耗在10.9~12.2 GJ/t范围内。

晃荡条件下LNG船液舱蒸发相变分析

天然气以其绿色清洁的优点,市场需求与日俱增。为了保证液化天然气(LNG)运输船安全运行,分析计算不同工况下的舱室日蒸发率尤为重要。通过Fluent软件研究LNG船液货舱在晃荡状态下的相变蒸发状态,并在LNG舱室蒸发计算中引入了晃荡变量因素。计算结果表明:内壁面过热度与液舱装载率均能大幅影响LNG的蒸发状态,LNG能快速转入稳定蒸发阶段,且蒸发质量流率趋于稳定。研究结果可为相关船舶研发提供参考。

甲烷化催化剂在高碳焦炉煤气制LNG项目中的应用

介绍了新疆某焦化厂高碳焦炉煤气制液化天然气(LNG)装置的概况及甲烷化工艺流程,重点分析了甲烷化催化剂在近3年间的运行情况。运行数据显示:甲烷化催化剂经过长周期运行,催化剂性能保持良好,甲烷化工段出口未检出CO和CO_(2),各反应器床层压差保持在初始值附近,未明显上升,且催化剂还具有较好的裂解功能。

火灾中大型LNG储罐内爆失效特性及其碎片飞散研究

建立大型LNG储罐的三维模型,采用有限元相容拉格朗日-欧拉(CLE)方法和流固耦合相互作用(FSI)原理,讨论储罐暴露在800℃环境中罐内不同位置发生内爆的破裂失效情况,分析其碎片的飞散特性,得到顶部爆炸的初速是罐中爆炸初速的1.57倍,质量均值相差约52%;根据碎片的飞散轨迹可以得到碎片的飞散落地距离在50 m内,研究结果可为大型LNG储罐的安全防护设计与罐区的安全距离提供一定参考依据。

LNG双燃料油船燃料舱结构强度评估方法研究

随着国际社会对绿色低碳要求逐步提高,采用液化天然气(liquefied natural gas,LNG)燃料的海船正成为运输船主流趋势。国际海事组织发布《使用气体或其他低闪点燃料船舶的国际安全规则》(简称“IGF规则”),虽然对使用低闪点燃料的燃料舱围护系统设计给出了载荷和设计条件的原则性要求,但对如何开展LNG燃料舱结构强度评估并同油船、散货船、集装箱船等运输船型的装载工况和评估衡准进行协调,则缺乏明确的指导,故操作性不高。该文结合IGF规则的燃料舱设计载荷要求及共同结构规范相关要求开展研究,提出了一种使用LNG燃料的油船燃料舱区域的船体结构强度直接计算方法,包括模型范围、载荷工况和强度评估衡准等,并以某油船为例,进行了燃料舱区域有限元直接计算的实船验证。结果表明该方法合理可行,并可为同类船舶的LNG燃料舱结构强度评估提供指导。

小型LNG站便携式取样技术研究

目的为了解决小型液化天然气(LNG)站缺乏有效质检取样技术,现有便携式LNG取样技术缺少取样应用实践,可靠性需要进一步验证的问题,提供一种新型便携式LNG取样装置和技术,以及取样可靠性验证方法。方法基于LNG相图控制理论基础,通过理论计算设计取样装置真空保冷探头和气化器,研制了基于真空保冷技术的便携式LNG取样装置,保障在取样过程中LNG以过冷态进入气化器并完全气化,确保LNG样品的代表性,并研制了基于LNG循环保冷技术的便携式LNG取样装置,通过对比两种取样装置所取样品的组成分析结果,进行了便携式LNG取样技术可靠性研究。结果在LNG加气站和LNG工厂的示范应用实践结果表明,采用便携式LNG取样装置11次连续取样获得的样品几乎一致,连续取2次LNG液体样品后组成分析的结果满足GB/T 13610-2020《天然气的组成分析气相色谱法》的再现性要求,且通过两种取样方法获得的样品的组成分析结果相吻合,表明便携式LNG取样技术可靠。结论该便携式LNG取样装置和技术取样效果达到了预期,满足了小型LNG场站LNG质量检测取样需求。