液化天然气冷能的利用

介绍了液化天然气冷能的概念及其在燃气轮机联合循环,低温发电,空气分离等方面的应用,为节省能源,提高液化天然气接收站的经济效益提供了新的途径。     

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％。     

液化天然气冷量利用发电方案探讨

本文分析了应用液化天然气（ＬＮＧ）冷量进行发电的可行性，阐述了其冷量利用原理着重介绍了ＬＮＧ冷量发电的典型流程，探讨了其性能影响因素，说明ＬＮＧ冷量具有较大发电潜力，应对其充分合理加以利用。     

LNG冷能发电技术研究进展

液化天然气是21世纪的主要能源之一。液化天然气中携带的大量冷能具有重要的回收利用价值。文中对LNG冷能发电技术的主要形式及改进优化途径进行分析,指出LNG冷能发电技术的发展方向和思路。     

利用液化天然气冷能空分新流程及模拟分析

提出了利用液化天然气（LNG）冷能空分新流程,产品是用于满足电厂富氧燃烧的气态富氧空气。空气视为N2（79.1 mol%）和O2（20.9 mol%）二元混合气体,采用Aspen Plus软件进行了流程模拟,物性方法选择Peng-Robinson方程。模拟结果表明,生产95.08 mol%富氧空气的能耗是0.667 kW.h/（kg.O2）,液化天然气（LNG）的消耗量是87.64 mol/（kg.O2）。与文献[7]生产多种液态产品模拟结果比较,单位氧气的能耗大致相等,LNG消耗减少约50%,精馏塔冷凝蒸发器两侧的传热温差从1.2 K增大到2.8 K,可大大减小换热器的面积。     

引进天然气优化发电能源结构

介绍我国发电能源结构,燃用天然气与煤炭的比较,天然气的储量,运输,安全性,引进ＬＮＧ以改善发电能源以煤为主的结构,以减轻环境污染治理的压力和改进调峰手段,供参考。     

利用液化天然气(LNG)冷源进行发电的理论分析

随着能源尤其是电力成本大幅增加,LNG冷源利用越来越显珍贵,本文利用LNG冷源进行发电功率计算,说明LNG冷源存在很大利用价值,如果充分利用将获得可观的经济和社会效益.     

引进天然气 优化发电能源结构

介绍了我国发电能源结构,燃用天然气与煤炭的比较,分析了天然气的储量,运输,安全性,建议引进液化天然气以改善发电能源以煤为主的结构,以减轻环境污染治理的压力和改进电网调峰手段。     

边远油气田天然气回收利用流程模拟研究

针对边远地区油气田小气量天然气资源目前存在的回收难、效益低的问题,提出了一种采用N-CH4作为制冷剂,两级压缩的方式,可以实现小气量天然气的回收.通过对小型天然气液化装置流程模拟,分析和优化了各个节点的参数.该流程具有结构和操作简单、容易集成撬装化的优点.     

液化天然气(LNG)冷能用于冷却发电燃气轮机进气的分析

对利用LNG冷能冷却燃气轮机进口空气系统的特点进行了分析,说明在适当的环境条件下应用此方法可明显改善燃气轮机发电机组的性能,并借鉴国外此项技术的实际应用并结合广州实际情况做出应用这项技术的可行性分析。     

空分设备在天然气输送工艺中余压和冷量的回收利用

介绍在天然气输送过程中的管道余压和LNG的冷量在空分上的利用,用热力学方法对其进行可行性研究,同时介绍利用余压和冷量的空分流程:让高压天然气逐级膨胀将压力降到中压后,产生的冷量再通过空分的主换热器,中压再进一步膨胀到低压范围后,产生的冷量补入空分的循环氮气;分析对比已有的利用LNG冷能的空分流程,指出由LNG冷能冷却的...     

Study on solidification of carbon dioxide using cold energy of liquefied natural gas

The present paper deals with solidification characteristics of carbon dioxide around the gas feed nozzle of the flue gas from a thermal energy power plant. The present experiment was carried out under dioxide contents between 3 and 50 vol%. The results obtained indicate that the solidification fraction of carbon dioxide increased with a decrease in cooling temperature. The solidification fraction of carbon dioxide was expressed as a function of the nondimensional temperature and concentration of the carbon dioxide. © 2000 Scripta Technica, Heat Trans Asian Res, 29(4): 249–268, 2000     

Development and assessment of concentrated solar energy driven ammonia synthesis from liquefied natural gas

The proposed system targets the production of carbon dioxide-free hydrogen from liquefied natural gas through a solar-driven catalytic thermal cracking process integrated into the ammonia synthesis unit. The catalytic material is being regenerated in an adjacent vessel by burning the deposited coke. As a result, pure carbon dioxide stream is obtained and can be used directly in urea synthesis, sequestration or other related applications. It is expected that the system will reduce the amount of fossil fuel consumption in the ammonia synthesis and mitigate the associated environmental impacts. The energetic and exergetic analyses are carried out to assess the performance of the developed system and to identify the optimum operating conditions. At an operating temperature of 900 °C of thermocatalytic cracking, the optimum pressure for optimal production of hydrogen is determined to be 23.8 bar. The corresponding overall energy and exergy efficiencies are calculated as 35.8% and 37.4%, respectively. At the same conditions, the energy and exergy efficiencies of the thermal cracking unit reach 61.8% and 59.3%, respectively. Several parametric studies are conducted to evaluate the effects of operating conditions at the cracker, irradiance day-night ratio, and consideration of CO₂ for transport and sequestration activities on the overall performance and production of the system. Ammonia production can reach 974 Metric Tons per Day (MTPD) and 893 MTPD considering operating conditions of 900 °C and 800 °C, and inlet LNG flow rate of 688 MTPD and 630 MTPD, respectively.     

利用文丘里引射装置回收利用高压天然气压力能

介绍引射器的基本工作原理及其特性,并对该项技术中的关键设备超音速引射器进行设计研究。工程应用表明,采用文丘里引射装置是以高压天然气引射低压人工煤气,不仅拓宽了天然气的应用领域,而且通过回收天然气管网压力能,可大幅度节省电耗,降低生产运营成本,提高城市燃气管网运行的可靠性。     

Simulation of natural gas transmission pipeline network system performance

Simulation has proven to be an effective tool for analyzing pipeline network systems （PNS） in order to determine the design and operational variables which are essential for evaluating the performance of the system. This paper discusses the use of simulation for performance analysis of transmission PNS. A simulation model was developed for determining flow and pressure variables for different configuration of PNS. The mathematical formulation for the simulation model was derived based on the principles of energy conservation, mass balance, and compressor characteristics. For the determination of the pressure and flow variables, solution procedure was developed based on iterative Newton Raphson scheme and implemented using visual C＋＋6. Evaluations of the simulation model with the existing pipeline network system showed that the model enabled to determine the operational variables with less than ten iterations. The performances of the compressor working in the pipeline network system xvhich includes energy consumption, compression ratio and discharge pressure were evaluated to meet pressure requirements ranging from 4000-5000 kPa at various speed. Results of the analyses from the simulation indicated that the model could be used for performance analysis to assist decisions regarding the design and optimal operations of transmission PNS.     

Analysis and optimization of a cascading power cycle with liquefied natural gas (LNG) cold energy recovery

The effective utilization of the cryogenic energy associated with LNG vaporization is quite important. In this paper a cascading power cycle with LNG directly expanding consisting of a Rankine cycle with ammonia–water as working fluid and a power cycle of combustion gas is proposed to recover cryogenic energy of LNG. Energy equilibrium equations and exergy equilibrium equations of each equipment in the cascading power cycle are established. Taken some operating parameters as key parameters, influences of these parameters on thermal efficiency and exergy efficiency of the cascading power cycle were analyzed. Optimization of the cascading power cycle with maximum economic benefits as objective function together with optimum variables and constraint conditions was solved. The optimum objective and variables were achieved.     

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.     

Real option valuation of free destination in long-term liquefied natural gas supplies

This paper presents a real option model for the valuation of destination flexibility in long-term LNG supplies. Stochastic price dynamics in the different markets is modelled through geometric Brownian motion processes. Mean reversion is considered as well as correlation between markets, but instead of the usual correlation in return shocks, a price convergence term is introduced representing the arbitrage streams between markets. Model parameters are estimated from market data on LNG prices by maximum log-likelihood. The goodness of the fit for the proposed model is tested as well as for two alternative models. Confidence intervals for the parameters are given. Results for the model are calculated by Monte Carlo simulation. Frequency distributions for the main results are plotted. The effect of the main parameters of the model is studied (i.e. price volatilities, price convergence, initial prices in the markets, mean reversion, extra transportation costs, number of alternative markets). The value of destination flexibility is found to be an important share of the value of LNG.     

液化天然气汽车技术及存在问题探讨

推广和应用液化天然气汽车（LNGV）是降低汽车排放污染的有效途径,文章介绍了LNG的理化特性,安全性,LNGV车载燃料系统和LNGV加气站技术,对LNGV在实际应用中存在的问题作了一些探讨。     

The prospects for liquefied natural gas development in the US

The objective of our paper is to analyze the prospects for LNG development in the US. In particular, we discuss LNG investment projects with respect to natural gas supply and demand, existing transmission infrastructure, and competing pipeline projects. At the same time potential competition between natural gas and coal in power generation is taken into account. We conclude that in the mid-term, LNG will assume an essential role in meeting US demand because of stagnating and declining domestic production in North America accompanied by an expected increase in demand for natural gas. Additional net imports will be required in the western US (mainly southern California), the Southeast, and in the Northeast—three areas of the nation that lack adequate supply. When accounting for the current status of existing natural gas infrastructure and forthcoming investments, we conclude that there should be little concern about sufficient investment incentives and supply security in the US competitive natural gas market.