2001年LNG工业综述

综述了液化天然气（LNG）贸易，回顾了历年LNG价格变化及市场形势，预测了以后10年内LNG供求趋势。介绍了天然气液化流程，LNG工厂、LNG运输及接收站。展望了LNG工业的现状与发展动向。     

Power generation potential of liquified natural gas regasification terminals

The share of liquified natural gas (LNG) in the international trade of natural gas (NG) is continually increasing. This presents increasing opportunities to build power plants to generate electricity at LNG regasification terminals rather than wasting the power generation potential of LNG at about −162°C by regasifying it by seawater, ambient air, or by burning NG. Typically, over 5% of the NG received at LNG plants is used to liquify the remaining incoming gaseous NG at environmental conditions. Theoretically, all the energy consumed at LNG liquefaction plants can be recovered at LNG regasification terminals. In this study, the theoretical and practical power generation potential of regasified LNG is investigated by performing energy and exergy analyses. It is shown that up to 0.191 kWh of electric power can be generated during the regasification of LNG per standard m³ of NG regasified. The potential economic gains associated with power generation at LNG regasification facilities are demonstrated by analyzing the 2018 LNG imports of Turkey as a case study and the world. It is shown that the 314 million tons of LNG imported globally in 2018 has the electric power generation potential of 88 billion kWh with a market value of over 10 billion USD. It also has the potential to offset 38 million tons of CO₂ emissions.     

文莱LNG的生产和出口

文莱在东盟地区天然气市场中占据着重要地位,其天然气储量为13.8×1012ft3,生产的天然气主要以LNG的形式出口至日本和韩国.文莱的天然气主要由文莱壳牌石油公司(BSP)进行生产,道达尔旗下的两个近海油田也提供一小部分天然气.生产的天然气在文莱液化天然气公司(BLNG)所属的液化处理厂进行液化处理,LNG年生产能力720×104t.文莱国内的天然气消费通过文莱石油销售公司(BSM)供应,其余的天然气由文莱壳牌油轮公司(BST)和文莱天然气油轮公司(BGC)运往海外.白1990年以来,文莱就一直将80％左右的天然气都出口到海外市场.从1973年开始,文莱每年向日本输出500×104t的LNG,1999年又签订了增加供货协议,每年增加到601×104t.韩国与文莱在1997年签订了为期16年的合同,保证每年70×104t的LNG供应.面对2013年即将到期的合同,日、韩两国都加紧了确保LNG长期供应的步伐.这使得中国、印度等国从文莱进口大量LNG的机会变小,但是通过日本和韩国在文莱整个LNG供应链建设过程中所付出的努力,其他LNG进口国至少能够借鉴到保障能源供应的一点经验.     

Utilization of the cryogenic exergy of LNG by a mirror gas-turbine

In the course of worldwide efforts to suppress global warming, the saving of energy becomes more important. Recently, LNG (liquefied natural gas) terminals in our country have received more than 50 million tons of LNG per year. Therefore, the utilization of the cryogenic exergy in connection with the regasification of LNG gains more and more importance. The aim of this paper is the recovery of the energy consumed in liquefaction using the MGT (mirror gas-turbine), which is a new kind of combined cycle of a conventional gas-turbine worked as a topping cycle and TG (inverted Brayton cycle) as a bottoming cycle. The optimum characteristics have been calculated and it is shown that this cycle is superior to the current-use gasification systems in employing seawater heat in terms of thermal efficiency and specific output. In the present cycle, the cold LNG is used to cool the exhaust gas from a turbine of a TG, and then the exergy of the liquefied natural gas is transformed, with a very high efficiency, to electric energy. The main feature of this new concept is the removal of an evaporation system using seawater.     

现代液化天然气工厂的投资趋势

回顾了３０年来ＬＮＧ工厂建设的投资情况，介绍了现代ＬＮＧ工厂的设计原则，指出了影响ＬＮＧ工厂投资的主要原因。     

Development of large-scale hydrogen liquefaction processes from 1898 to 2009

This paper presents a review of the development of large-scale hydrogen liquefaction processes throughout the world from 1898 to 2009. First, there is a concise literature review including numerous past, present, and future designs given such as the first hydrogen liquefaction device, long time ago simple theoretical processes, today's actual plants with efficiencies 20–30%, a list of the capacity and location of every hydrogen liquefaction plant in the world, and some modern more efficient proposed conceptual plants with efficiencies 40–50%. After that, further information about the development and improvement potential of future large-scale liquid hydrogen liquefaction plants is given. It is found that every current plant is based on the pre-cooled Claude system, which is still the same as was 50 years ago with little improvement. Methods to resolve the challenges of the future plants include proposing completely new configurations and efficient systems coupled with improved efficiencies of the main system components such as compressors, expanders, and heat exchangers. Finally, a summary and comparison of the process efficiencies are described, including a newly proposed Multi-component Refrigerant (MR) system being developed by NTNU and SINTEF Energy Research AS.     

Energy optimization for liquefaction process of natural gas in peak shaving plant

One of the most important sections in the gas peak shaving plant regarding the energy consumption is the liquefaction process of natural gas (NG). Thus, selection and development of this process with the lowest energy consumption, offer huge potential energy and cost benefits. Here, a single-stage mixed refrigerant (SMR) cryogenic cycle with two compression stages has been selected for producing Liquefied Natural Gas (LNG). Energy consumption of the process as an objective function is optimized by describing key variables of the design. The proposed process’s calculations of thermodynamic concepts and properties are applied in MATLAB software to generate the objective function; furthermore Genetic Algorithm (GA) is used as an optimization method. Concerning works done in this area, more key parameters – related directly to the objective function – are introduced in this paper. A low irreversibility is due to enhanced values of key parameters in the LNG heat exchanger observed under a low temperature difference between hot and cold composite curves. Finally, the exergy lost of equipments in the proposed process are evaluated and analyzed in details.     

Boil off gas (BOG) management in Spanish liquid natural gas (LNG) terminals

Spain is a country with six LNG terminals in operation and three more scheduled for 2011. At the same time an increasing number of LNG tanks are under construction to compensate the Spanish lack of underground storage. A method for evaluating the daily boil off generated is presented in this paper. This method is applied to evaluate the increase of BOG to be handle by LNG terminals in 2016, studying the best commercially available solution to be installed. Finally, as a solution to tackle with the BOG a cogeneration plant is suggested. This option will reduce terminal’s operational costs increasing its availability.     

大型联合循环机组关键问题的探讨

随着“西气东输”及“引进液化天然气”工程的实施,我国将建设一批大型燃气—蒸汽联合循环电厂。本文就大型燃气—蒸汽联合循环机组的效率、余热锅炉型式、轴系布置、进气冷却等关键技术问题进行了探讨。     

LNG development across Europe: Infrastructural and regulatory analysis

In this paper, a cross-section infrastructural and regulatory analysis of the European LNG sector is presented. The LNG chain is maintained as being a good tool to enlarge the number of natural gas exporters to Europe, adding in this way to competition and to the achievement of the targets of the liberalisation process, which is a decrease in price for final customers and security of supply. The main reason for this is to be identified in the minor specificity of the regasification-plant-related investment compared with pipeline transportation. As a matter of fact, as the infrastructural analysis will show, the construction of new LNG receiving terminals is likely to bring about an increase in the number of importers fostering competition among them and shrinking their margins among the value chain. In this context, regulation is meant to play a key role in promoting investments without hindering competition. Nevertheless it is questionable whether LNG will be able to introduce competition beyond the European border (that is among producers) according to the forecasted supply and demand balance that is leading to a seller's market in the upstream sector. In this case, a huger part of the rent would go to the exporters leaving minor scope for competition down the European border.     

Advanced exergetic analysis of a novel system for generating electricity and vaporizing liquefied natural gas

LNG technology has been in use since the 1960s. During the last 20 years the total cost of LNG technology has decreased by 30% due mainly to improvements of the liquefaction process and shipping. However, the regasification system has not been significantly improved. The paper presents a detailed advanced exergetic analysis of a novel co-generation concept that combines LNG regasification with the generation of electricity. The analysis includes splitting the exergy destruction within each component into its unavoidable, avoidable, endogenous and exogenous parts as well as a detailed splitting of the avoidable exogenous exergy destruction. The results of the advanced exergetic analysis are confirmed through a sensitivity analysis. Finally, some suggestions for improving the overall system efficiency are developed.     

Enhancement of APCI cycle efficiency with absorption chillers

Liquefied natural gas (LNG) plants consume a great amount of energy. In order to enhance the energy efficiency of the LNG plant, the potential energy efficiency enhancements of various options of utilizing the waste heat powered absorption chillers in the propane pre-cooled mixed refrigerant (APCI) liquefaction cycle were investigated in this study. After developing models of the LNG process, gas turbine and absorption chillers, eight options of gas turbine waste heat utilization were simulated. The simulation results show that by replacing 22 °C and 9 °C evaporators and cooling the condenser of propane cycle at 14 °C and inter-cooling the compressor of mixed refrigerant cycle with absorption chillers which are powered by waste heat from the gas turbine, both the compressor power and fuel consumption reduction can be achieved as much as 21.32%. This enhancement requires recovering at least 97% of gas turbine waste heat.     

Comparative evaluation of LNG - based cogeneration systems using advanced exergetic analysis

During the last two decades the total cost of LNG technology has decreased significantly due to improvements of the liquefaction process. However, the regasification system has not been considerably improved. It is known that for the regasification process about 1.5% of LNG is used. Two novel, gas-turbine-based concepts for combining LNG regasification with the generation of electricity are discussed in this paper. These concepts have relatively low investment costs and high efficiencies. An advanced exergetic analysis is applied to one of these attractive LNG-based cogeneration systems to identify the potential for improvement and the interactions among components. In an advanced exergetic analysis, the exergy destruction within each component is split into unavoidable/avoidable and endogenous/exogenous parts. The advantages of this analysis over a conventional one are demonstrated. Some new developments in the advanced exergetic analysis and options for improving the concepts are also presented.     

A policy study examining the use of imported LNG for gas-fired power generation on the southeast coast of China

Since China's energy demand is growing quickly, speeding up the development of natural gas is an important substitute and supplement for coal and oil. The development of the natural gas market in many developing countries has demonstrated that the success of the whole project hinges upon the success of gas-fired power generation. However, under the current energy pricing system in China, the advantages of gas-fired power plants, such as low investment costs and high efficiency, have not been able to offset the low price of coal. The gas-fired power plants, both at downstream of the Liquefied Natural Gas (LNG) industry and upstream of the power sector, are faced with a dilemma. In order to solve the problems facing gas-fired power projects while providing policy guidance for the future development of gas-fired power projects, the policy of gas-fired power generation using imported LNG on the southeastern coast of China was examined. This study aims to identify the position of the national energy strategy that China should import some LNG from the other countries, to guide the development of energy policy in this region, and to formulate some clear policy measures.     

Analysis of the liquefaction process of exhaust gases from an underwater engine

In operating underwater engines, such as in exploring submarines, the dumping of the exhaust gas out of the engine requires a large portion of the total power, frequently amounting to 25–30% of the power generated. This can be solved by liquefying the exhaust gas and storing it. In the present study, two liquefaction systems are simulated to enhance the overall efficiency; one is a closed cycle diesel cycle and the other is a closed cycle liquefied natural gas (LNG) engine. LNG was chosen as a fuel not only because it is economical but also because its cold energy can be utilized within the liquefaction system. Since a mixture of oxygen and carbon dioxide is used as an oxidizer, liquefying carbon dioxide is the major concern in this study. To further improve this system, the intercooling of the compressor is devised. The power consumed for the liquefaction system is examined in terms of the related properties, including pressure and temperature of the carbon dioxide vessel as a function of the mass fraction of the exhaust gas that enters the compressor. The present study shows that much gain in the power and reduction of the vessel pressure could be achieved in the case of the closed cycle LNG engine. The compression power was remarkably low, typically only 6.3% for the closed cycle diesel engine and 3.4% for the closed cycle LNG engine, respectively, of net engine power. For practically, a design–purpose map of the operating parameters of the liquefaction systems is also presented.     

LNG加气行业运营模式研究和经济性分析

LNG作为车用燃料具有安全环保和经济性的优势,LNG汽车的优势和前景已得到了普遍认可。但是,我国目前现有的LNG加气站的数量远不能适应L N G汽车交通运输发展的需要。由于液化模式和技术等的不同,LNG加气站相比传统的汽柴油加油站的类型更加多样化。从LNG车用加注市场全产业链的角度,可以将LNG加气站的运营模式分为六种。它们的技术和工艺流程都不相同,因此影响其成本的主要因素也不同。可以综合考虑每种模式的使用条件和成本影响因素,来选择合适的运营模式。但是专用液化模式应是发展LNG加气站的主要方向,只用这样才能向市场提供大量廉价的LNG,进而形成跨地域的LNG加注网络。随着时间的推移,LNG车用燃料市场规模将会不断扩大,综合运用这六种LNG加气站运营模式才能满足日益增长的LNG车用燃料的市场需求。     

Exporting natural gas in the form of LNG

The export of liquefied natural gas (LNG) is much more capital intensive than the export of oil, requiring an initial investment perhaps three to five times greater per unit of energy transported. Moreover, a minimum recoverable reserve of 5 to 6 × 10¹² ft³ must be available to support an LNG export project. This threshold is a compromise between scale economies, on the one hand, and the difficulties of mobilizing large-scale financing on the other. Countries considering the export of LNG must take into consideration potential cost increases and the difficulties of synchronizing revenue streams with debt-service requirements. The investment costs of liquefaction and LNG transportation are presented in this paper, along with discussions of alternative financing methods and potential LNG markets.     

Can the Shanghai LNG Price Index indicate Chinese market? An econometric investigation using price discovery theory

China became the world’s second largest liquefied natural gas (LNG) importer in 2018 but has faced extremely high import costs due to a lack of bargaining power. Assessments of the Shanghai LNG Price Index, first released in 2015, are vital for improving the understanding of these cost dynamics. This paper, using the LNG price index data from the Shanghai Petroleum and Gas Exchange (SHPGX) coupled with domestic and international LNG prices from July 1, 2015 to December 31, 2018, estimates several econometric models to evaluate the long-term and short-term equilibriums of the Shanghai LNG Price Index, the responses to market information shocks and the leading or lagging relationships with LNG and alternative energy prices from other agencies. The results show that the LNG price index of the SHPGX has already exhibited a long-term equilibrium and short-term adjustment mechanisms to reflect the average price level and market movements, but the market information transparency and price discovery efficiency of the index are still inadequate. China’s LNG market is still relatively independent of other natural gas markets, and marketization reforms are under way in China. The influence of the SHPGX LNG price index on the trading decisions of market participants is expected to improve with further development of China’s LNG reforms, the formation of a natural gas entry-exit system, and the increasing liquidity of the hub.     

Design and analysis of liquefaction process for offshore associated gas resources

Liquefaction is the key section on floating platform. Some experts and designers selected mixed refrigerant process for floating platform, while some recommended expander cycle. However, few of them compared the two types of processes systemically before making a choice. In this paper, the liquefaction processes of propane pre-cooled mixed refrigerant cycle (C₃/MRC), mixed refrigerant cycle (MRC) and nitrogen expander cycle (N₂ expander) for the special offshore associated gases in South China Sea have been designed and studied. These processes have been analyzed and compared systematically considering the main factors including the performance parameters, economic performance, layout, sensitivity to motion, suitability to different gas resources, safety and operability, accounting for the features of the floating production, storage and offloading unit for liquefied natural gas (LNG-FPSO) in marine environment. The results indicated that N₂ expander has higher energy consumption and poorer economic performance, while it has much more advantages than C₃/MRC and MRC for offshore application because it is simpler and more compact and thus requiring less deck area, less sensitive to LNG-FPSO motion, has better suitability for other gas resources, has higher safety and is easier to operate. Therefore, N₂ expander is the most suitable offshore liquefaction process. In addition, the exergy analysis is conducted for N₂ expander and the results indicate that the compression equipments and after coolers, expanders and LNG heat exchangers are the main contribution to the total exergy losses. The measures to decrease the losses for these equipments are then discussed.     

Life cycle CO2 analysis of LNG and city gas

An analysis was conducted on greenhouse gas emissions from the liquified natural gas (LNG) chain and life cycle of City Gas 13A [caloric value: 46 MJ/Nm³(11,000 kcal/Nm³)], which is produced from LNG. The analysis was based on highly reliable data which are qualified in terms of source and representativeness. Actually, the latest data for CO₂ and CH₄ emissions from the natural gas field and liquefaction plant were obtained from field studies. Moreover, the analysis includes CO₂ emissions during the LNG transportation from exporting countries to Japan, city gas production and distribution stage in Japan and the manufacturing of facilities associated with the production of natural gas overseas to final domestic consumption. The reduction effect of CO₂ using LNG cryogenic energy was also considered. The evaluation showed that the level of greenhouse gas emissions and energy consumptions in the modern natural gas production and liquefaction plants were lower than those previously reported due to improvements in the production process. The results of the analysis also provide basic data essential for conducting life cycle analyses in many fields using natural gas.