LNG (liquefied natural gas): A necessary part in China's future energy infrastructure

This paper presents an overview of the LNG industry in China, covering LNG plants, receiving terminals, transportation, and applications. Small and medium scale LNG plants with different liquefaction processes have already been built or are being built. China's first two LNG receiving terminals have been put into operation in Guangdong and Fujian, another one is being built in Shanghai, and more are being planned. China is now able to manufacture LNG road tanks and containers. The construction of the first two LNG carriers has been completed. LNG satellite stations have been built, and LNG vehicles have been manufactured. LNG related regulations and standards are being established. The prospects of LNG in China are also discussed in this paper. Interesting topics such as small-scale liquefiers, LNG cold energy utilization, coal bed methane liquefaction, LNG plant on board (FPSO – floating production, storage, and off-loading), and LNG price are introduced and analyzed. To meet the increasing demand for natural gas, China needs to build about 10 large LNG receiving terminals, and to import LNG at the level of more than 20 bcm (billion cubic metre) per year by 2020.     

On the recovery of LNG physical exergy by means of a simple cycle or a complex system

The maximum and minimum temperatures available limit the usable fraction (or Carnot efficiency) of a power cycle. The construction of LNG terminals and the need to vaporize LNG offers a thermal sink at a very much lower temperature than seawater. By using this thermal sink in a combined plant, it is possible to recover power from the vaporization of LNG.To this purpose, in this paper combined systems using LNG vaporization as low-temperature thermal sink are considered and their pros and cons are presented. A system utilizing waste energy as heat source and with a single working fluid is analyzed in detail. However, the use of a single fluid is not the best solution from a thermodynamic point of view. Thus, a series of cascading cycles is also outlined. In these systems, both the thermal source and the thermal sink are exploited as exergy sources.     

Exergy analysis of liquefied natural gas cold energy recovering cycles

Liquefied natural gas (LNG) is known as ‘green fuel’ used in power plant, automobile and so forth due to its higher energy density and environmentally friendly advantages. LNG, besides its high quality chemical exergy, has plenty of physical exergy such as cold exergy and pressure exergy, which could be utilized further. Analysis of physical exergy and its affected factors has been conducted. Based on the analysis, several cycles used for recovering and applying the physical exergy of LNG, such as combined power cycle, gas turbine power generation cycle and automobile air‐conditioning system have been proposed. The parameters affecting the performance of the cycles are discussed. The recovery and utilization of physical exergy of LNG are the important measures to save energy and protect the environment. Copyright © 2005 John Wiley & Sons, Ltd.     

COOLCEP (cool clean efficient power): A novel CO2-capturing oxy-fuel power system with LNG (liquefied natural gas) coldness energy utilization

A novel liquefied natural gas (LNG) fueled power plant is proposed, which has virtually zero CO₂ and other emissions and a high efficiency. The plant operates as a subcritical CO₂ Rankine-like cycle. Beside the power generation, the system provides refrigeration in the CO₂ subcritical evaporation process, thus it is a cogeneration system with two valued products. By coupling with the LNG evaporation system as the cycle cold sink, the cycle condensation process can be achieved at a temperature much lower than ambient, and high-pressure liquid CO₂ can be withdrawn from the cycle without consuming additional power. Two system variants are analyzed and compared, COOLCEP-S and COOLCEP-C. In the COOLCEP-S cycle configuration, the working fluid in the main turbine expands only to the CO₂ condensation pressure; in the COOLCEP-C cycle configuration, the turbine working fluid expands to a much lower pressure (near-ambient) to produce more power. The effects of some key parameters, the turbine inlet temperature and the backpressure, on the systems' performance are investigated. It was found that at the turbine inlet temperature of 900 °C, the energy efficiency of the COOLCEP-S system reaches 59%, which is higher than the 52% of the COOLCEP-C one. The capital investment cost of the economically optimized plant is estimated to be about 750 EUR/kWe and the payback period is about 8–9 years including the construction period, and the cost of electricity is estimated to be 0.031–0.034 EUR/kWh.     

温差发电和动力装置联合回收液化天然气冷能

对液化天然气(LNG)冷能的回收,提出了温差发电器与动力装置联合的回收系统,对系统的各个状态 参数和转化能量及其效率进行了分析计算。计算显示甲烷在天然气中的摩尔含量会显著地影响功量的输出,但 对系统的效率影响不大。系统对LNG最大可用能的回收效率可达29％。     

Technical-Economic Parameters of the New Oil Shale Mining—Chemical Complex in Northeast Estonia

The history of oil shale mining in Estonia has reached its century mark. Three oil shale branches have been formed and have been working on the basis of Estonian oil shale deposits: the mining industry (underground and surface extraction), the power industry (heat and electric energy generation), and the chemical industry (gas and synthetic oils). The authors attempted to summarize the experience of the activities of these branches and to make into a whole the results of their research developments in the past years, as well as to form a notion about perspectives of oil shale in Estonia. Variants of the mining-chemical oil shale complex production and trade patterns differed from used ones. Mining methods, thermal processing of oil shale, and solid, liquid, and gas waste recovery have been studied, analyzed, and worked out up to the present. Setting up a flexible trade structure within the framework of that complex is considered the main economic mechanism capable of balancing production costs of such a complex with its earnings, which could respond properly to any, even peak, fluctuations of the market for final products processed from oil shale. Data of the working “Estonia” oil shale mine were used as the basis of the analysis and practical conclusions. Information on the mine being projected in the region of Ojamaa in the northeast of Estonia was taken as the data of the worthwhile supplier. Oil shale processing chemical complex is considered in two structural alternatives: in technological chain with the “Estonia” mine (the first variant), and with the projected mine of a new technical level (the second variant).     

Novel cogeneration power system with liquefied natural gas (LNG) cryogenic exergy utilization

We propose a new cogeneration power system with two energy sources of fuel chemical energy and liquefied natural gas (LNG) cryogenic energy, and two outputs of electrical power and cooling power. Due to the advanced integration of system and cascade utilization of LNG cryogenic energy, the system has excellent energy saving: chemical energy of fuel and LNG cryogenic energy are saved by 7.5–12.2% and 13.2–14.3%, respectively. As CO₂ is selected as working fluid and oxygen as fuel oxidizer, CO₂ is easily recovered as a liquid with LNG vaporization. In this paper, the typical recuperative Rankine cycle and the corresponding cogeneration system are described and a detailed thermodynamic analysis is carried out to reveal the principle of the cycle and system. Furthermore, the influence of key parameters on performance is discussed. Considering the engineering application, the technical advantages and concerns are pointed out.     

Thermodynamic analysis of a new double-pressure condensation power generation system recovering LNG cold energy for hydrogen production

Cold energy during the LNG regasification process is usually applied for power generation, but the electricity demand varies with the time. Therefore, a thought that transforming electrical energy into hydrogen energy by PEM electrolyzer is put forward to adjust the adaptability of power output to electricity demand. This paper proposes a new double-pressure condensation Rankine cycle integrated with PEM electrolyzer for hydrogen production. In this system, seawater is used as the heat source, and binary mixed working fluids are applied. Meanwhile, multi-stream heat exchanger is introduced to improve the irreversibility of heat transfer between LNG and working fluid. The key system parameters, including seawater temperature, the first-stage condensation temperature, the second-stage condensation temperature, and outlet temperature of LNG, are studied to clarify their effects on net power generation, hydrogen production rate and energy efficiency. Furthermore, the hydrogen production rate is as the objective function, these parameters are optimized by genetic algorithm. Results show that seawater temperature has positive impact on the net power output and hydrogen production rate. The first-stage condensation temperature, the second-stage condensation temperature, and outlet temperature of LNG have diverse effects on the system performance. Under the optimal working conditions, when the LNG regasification pressure are 600, 2500, 3000 and 7000 kPa, the increasing rate for optimized net power output, hydrogen production rate and energy efficiency are more than 11.68%, 11.67% and 8.88%, respectively. The cost of hydrogen production with the proposed system varies from 1.93 $/kg H2 to 2.88 $/kg H2 when LNG regasification pressure changes from 600 kPa to 7000 kPa.     

Experimental results of different control strategies in a solar air-conditioning system at part load

In this article, different control strategies used in a solar cooling installation are presented and compared, publishing real working data from three summer periods, with the system working at part load.The facility consists of two solar fields that feed a heating system during the winter and a 35 kW Li-Br absorption chiller during the summer period to cool part of an office building.The improvements obtained using control based on critical radiation and a variable flow mass have been compared on the solar plant with a conventional constant flow control. In the same way, the improvements obtained in the yields of a cooling production plant have been compared when programming three different controls: the first one with fixed flow masses, the second adapting the temperature on the condenser as a function of the generator temperature (constant flow mass), and the third adapting the condenser temperature and the flow mass on the generator as a function of the system loads.     

A review of cryogenic power generation cycles with liquefied natural gas cold energy utilization

Liquefied natural gas (LNG), an increasingly widely applied clean fuel, releases a large number of cold energy in its regasification process. In the present paper, the existing power generation cycles utilizing LNG cold energy are introduced and summarized. The direction of cycle improvement can be divided into the key factors affecting basic power generation cycles and the structural enhancement of cycles utilizing LNG cold energy. The former includes the effects of LNG-side parameters, working fluids, and inlet and outlet thermodynamic parameters of equipment, while the latter is based on Rankine cycle, Brayton cycle, Kalina cycle and their compound cycles. In the present paper, the diversities of cryogenic power generation cycles utilizing LNG cold energy are discussed and analyzed. It is pointed out that further researches should focus on the selection and component matching of organic mixed working fluids and the combination of process simulation and experimental investigation, etc.     

Exergy-energy analysis of full repowering of a steam power plant

A 320 MW old steam power plant has been chosen for repowering in this paper. Considering the technical conditions and working life of the power plant, the full repowering method has been selected from different repowering methods. The power plant repowering has been analyzed for three different feed water flow rates: a flow rate equal to the flow rate at the condenser exit in the original plant when it works at nominal load, a flow rate at maximum load, and a flow rate when all the extractions are blocked. For each flow rates, two types of gas turbines have been examined: V94.2 and V94.3A. The effect of a duct burner has then been investigated in each of the above six cases. Steam is produced by a double-pressure heat recovery steam generator (HRSG) with reheat which obtains its required heat from the exhaust gases coming from the gas turbines. The results obtained from modeling and analyzing the energy-exergy of the original steam power plant and the repowered power plant indicate that the maximum efficiency of the repowered power plant is 52.04%. This maximum efficiency occurs when utilizing two V94.3A gas turbines without duct burner in the steam flow rate of the nominal load.     

船用核汽轮机装置仿真研究

建立了适合船用核汽轮机装置实时仿真分析计算的两相流仿真模型。利用该仿真模型对快速变负荷工况下船用核汽轮机装置的动态特性进行了计算分析。结果表明,该模型能准确模拟核汽轮机装置的变负荷运行特性,满足核动力二回路系统实时仿真分析要求。模型已经成功应用于两型船用核动力训练模拟器的开发,对操纵人员的培训及操作规程的验证具有重要意义。     

液态天然气销售对燃气发电市场的影响

叙述了国内液态天然气（LNG）的资源、市场情况,并以广东LNG市场为例,从LNG资源、LNG运输、LNG卫星站建设、经济性比较的角度分析了中、小型燃气发电厂或分布式能源站自建LNG卫星站气化进行发电的可能性。     

Thermodynamic modeling and exergy investigation of a hydrogen-based integrated system consisting of SOFC and CO2 capture option

The current study deals with the thermodynamic modeling of an innovative integrated plant based on solid oxide fuel cell (SOFC) with liquefied natural gas (LNG) cold energy supply. For the suggested innovative plant the energy, and exergy simulations are fully extended and the plant comprehensively analyzed. According to mathematical simulations of the proposed plant, a MATLAB code has been extended. The results indicate that under considered initial conditions, the efficiencies of SOFC and net power generation calculated 58% and 78%, respectively and the CO₂-capture rate is obtained 79 kg/h. This study clearly shows that the integrated system reached high efficiency while having zero emissions. In addition, the efficiencies and net amount of power generation, cooling or heating output and SOFC power generation are discussed in detail as a function of different variables such utilization factor, air/fuel ratio, or SOFC inlet temperature. For enhancing the power production efficiency of SOFC, the net electricity, and CCHP exergy efficiency the plant should run in higher utilization factor and lower air/fuel ration also it's important to approximately set SOFC temperature to its ideal temperature.     

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.     

Thermodynamic analyses of the performance of a thermal-storage system with water as its working fluid

A thermal storage system for air-conditioning with water as its working substance is proposed and analyzed. Because water is a natural substance, the system has no environmental problems. The system consists of a steam compressor, a condenser, an expansion valve, a separator, two ejectors, an evaporator and a pump. Owing to the pump and ejectors, the compression ratio and the swept volume of the compressor are much smaller than those of a traditional system at lower evaporating temperatures. The new system can be used for ordinary air-conditioning or for thermal storage or both. A numerical simulation has been conducted to analyze the characteristics of the system under different working conditions. The results were compared with those of traditional systems using water or R22 as the working medium.     

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.     

High efficiency power plant with liquefied natural gas cold energy utilization

This article proposes a novel power plant comprising a closed Brayton cycle (CBC) and a Rankine cycle (RC) coupled in series with respect to the flue gases instead of a conventional combined cycle, where the cold energy of the LNG is used to cool the CBC compressor suction. The research study focuses on finding working fluids best suited to the proposed CBC–RC plant and on achieving high efficiency. The proposed working fluids that fulfil the requirements for the CBC are He, N₂ and for the RC are CO₂, ammonia, ethanol or water. An analysis of the power plant using different working fluids is carried out and it is ascertained that the best efficiency conditions for the CBC are achieved with He and CO₂ for the RC. As a result, a thermal efficiency of 67·60%, an overall efficiency of 55·13% and a specific power of 2·465 MW/(kg s⁻¹ LNG) is achieved.     

用于电动钻机的LNG发电机性能分析及改进方案

针对LNG发电机在钻井现场试验中,出现的工况不稳定、功率利用率低、容易熄火等问题,通过分析发动机的特性曲线、各个工况的特点以及气体发动机的特性等认为:问题的原因为LNG发动机加速性较慢,进气系统的随动性较差。据此,从发动机控制系统以及外围设备等方面提出解决问题的方案,为LNG发电机在钻井工程上的推广应用提供了有效思路。     

核电应急柴油发电机组机外压缩空气系统设计及抗震计算

应急柴油发电机组（EDG）是核电厂失去正常电源后向厂内安全系统和其他指定的重要安全设备紧急提供可靠电力,以保证在假设突发事件后能将电厂维持在安全状态的厂内自备应急发电系统。压缩空气起动系统的作用是使应急柴油发电机组从静止状态进入到工作状态。压缩空气起动系统的性能决定着应急柴油发电机组能否及快速的投入运用。机外压缩空气系统是压缩空气起动系统的重要组成部分,负责向柴油机起动装置提供满足要求的压缩空气。本文介绍了某核电厂应急柴油发电机组项目中,机外压缩空气系统的设计和型式试验,并运用抗震计算的方法对系统的抗震性能进行了验证。