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.

An Improved Combined Power System Utilizing Cold Energy of LNG

In order to improve efficiency of a combined power system in which waste heat from exhaust gas could be efficiently recovered and cold energy of liquefied natural gas(LNG) could be fully utilized as well. A system simulation and thermodynamic analysis were carried out,the Kalina cycle was reorganized by changing the concentration of "basic composition",so that a better thermal matching in the heat exchanger could be obtained and the irreversibility of the system was decreased. It was found that the Kalina cycle generally used in the bottom of combined power cycle could also be used to recover the cold energy of LNG. The results show that the exergy efficiency of 42.97% is obtained. Compared with the previous system attained the exergy efficiency of 39.76%,the improved system has a better performance.

LNG轻烃分离工艺设计及分析

1t液化天然气(LNG)气化过程中大约可释放230 kW·h的冷能,轻烃分离后的LNG,既可有效调整热值,也能统一天然气产品标准。从利用LNG冷能的角度出发,设计一种LNG轻烃分离工艺,对工艺进行敏感性分析,选用P-R热力学方程,运用HYSYS模拟软件对工艺进行模拟计算,原料LNG的进料量为342.5 t/h,回收得到的天然气、乙烷和液化石油气(LPG)产品的质量流量分别为271.16 t/h、46.79 t/h和24.55 t/h,工艺总功耗为446.67 kW,而且模拟计算体系的物流能够满足物料平衡。

液化天然气(LNG)在海水淡化技术中的研究进展

综述了国内外液化天然气(LNG)在海水淡化技术中的应用现状及研究进展,总结了目前海水淡化技术存在的问题。分析表明国内外对利用LNG冷能进行海水淡化的研究日益重视,该技术与传统海水淡化技术相比更加的节能,具有广阔的应用前景。

Analysis and Economic Evaluation of Hourly Operation Strategy Based on MSW Classification and LNG Multi-Generation System

In this study,a model of combined cooling,heating and power system with municipal solid waste(MSW)and liquefied natural gas(LNG)as energy sources was proposed and developed based on the energy demand of a large community,andMSW was classified and utilized.The systemoperated by determining power by heating load,and measures were taken to reduce operating costs by purchasing and selling LNG,natural gas(NG),cooling,heating,and power.Based on this system model,three operation strategies were proposed based on whether MSW was classified and the length of kitchen waste fermentation time,and each strategy was simulated hourly throughout the year.The results showed that the strategy of MSW classified and centralized fermentation of kitchen waste in summer(i.e.,strategy 3)required the least total amount of LNG for the whole year,which was 47701.77 t.In terms of total annual cost expenditure,strategy 3 had the best overall economy,with the lowest total annual expenditure of 2.7730×108 RMB at LNG and NG unit prices of 4 and 4.2 RMB/kg,respectively.The lower heating value of biogas produced by fermentation of kitchen waste from MSW being classified was higher than that of MSW before being classified,so the average annual thermal economy of the operating strategy of MSW being classified was better than that of MSW not being classified.Among the strategies in which MSW was classified and utilized,strategy 3 could better meet the load demand of users in the corresponding season,and thus this strategy had better thermal economy than the strategy of year-round fermentation of kitchen waste(i.e.,strategy 2).The hourly analysis data showed that the net electrical efficiency of the system varies in the same trend as the cooling,heating and power loads in all seasons,while the relationship between the energy utilization efficiency and load varied from season to season.This study can provide guidance for the practical application of MSW being classified in the system.

LNG冷能发电模式分析

本文以项目实例,将朗肯循环运用到联合法发电流程,通过模拟计算表明,混合工质是用于低温朗肯循环最合适的工质,工质的蒸发温度和冷凝温度对系统净输出功的影响较为明显,利用周边装置余热作为工质蒸发热源可有效改善系统冷量回收率。

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 experi- mental investigation, etc.

唐山LNG项目冷能利用示范工程

中国石油唐山LNG项目是为适应京津冀地区供气需求,形成多气源供气格局,确保京津冀地区供气安全的国家重点工程,项目位于河北省唐山市唐海县曹妃甸港。在分析国内已有LNG冷能利用项目规划和所存在问题的基础上,论证了唐山LNG冷能项目是目前国内最可能形成以LNG下游产业链、冷能利用产业链、炼油化工产业链和炼钢、发电产业链一体化建设格局的项目,也是典型的循环经济示范工程。通过预测唐山曹妃甸地区的工业气体市场、冷工业状况及潜力、油田伴生气轻烃分离市场及乙烯装置冷量需求市场等发展前景,初步制订了唐山LNG冷能利用项目的规划,并形成了以LNG冷能为依托,以空分、伴生气轻烃分离和冷媒循环系统为纽带,集成炼油厂、乙烯厂、钢铁厂以及其他重化工业、油田伴生气资源优化利用和CO2沉积等产业统筹发展的格局。

液化天然气(LNG)冷能利用研究进展

液化天然气(LNG)作为一种清洁、高效的优质能源,其汽化释放的大量冷量具有极大的经济价值及环保价值,但却存在LNG冷能利用率不高的普遍问题。本文阐述了LNG冷能利用的各种方式,比较了各种方式的优缺点及冷能需求,分析了其利用前景及环保价值。介绍了国内外液化天然气冷能利用技术的开发与研究进展,指出了其冷能利用率普遍不高的原因。在此基础上强调了LNG冷能"温度对口,梯级利用"原则的重要性,开发蓄积和储存冷能的装置以及研发新型载冷剂的迫切性,并提出因地制宜选择冷能利用项目,拓展新的冷能利用形式。

LNG冷量优化集成利用技术

我国将相继在沿海地区建成多个LNG接收站,每年将进口数以千万吨计的LNG,同时携带数着巨额冷量,而这些冷量可用于发电、空气分离、制造干冰、低温冷库等众多领域。基于国外LNG冷量利用现状,指出我国即将展开和实施此项技术还存在着:过程火用损较大,缺乏系统、全面的LNG冷量利用技术的研发指导机制,以及宏观调控力度薄弱等问题,进而提出了发展LNG冷量的集成利用方案,可为此类技术的研发利用提供新思路。以福建即将进口的LNG为例,模拟了空气分离与干冰制备的集成工艺流程,结果表明:福建每年进口的260×104tLNG可以冷却290×104t空气,相当于60000m3/h的氧气制备规模,还可以生产100×104t的干冰,其过程火用损较小;其剩余的高温位冷量可应用于低温冻结库或冰灯等项目,这对主体装置的实施效果和过程火用损的影响较小。该技术的优点在于可灵活控制冷却空气的液化率,基本不用冷却循环水,流程简单,设备投资少,能耗低等。

基于液化天然气(LNG)冷量的废旧橡胶低温粉碎工艺流程

探讨了废旧橡胶低温粉碎中LNG冷量的利用问题。用空气作为中间冷媒,将LNG冷量先传给空气,再由空气去喷吹冷却胶粉。设计了此冷却换热的工艺流程,进行了物料及冷量的衡算,以实现冷量的有效利用。

液化循环中LNG冷量利用的热力学研究

LNG在气化过程中会有大量冷量释放。对LNG的冷量进行了初步的能量分析,并以克劳特液化循环为例,对LNG的流量和换热器压力对于气体液化循环的影响进行初步探讨,并采用流程模拟软件对其影响进行了验证,研究了LNG流量对循环液化系数、单位能耗、循环膨胀量和系统效率的影响。结果表明,利用LNG冷量的克劳特循环,可以减少其膨胀气量,提高液化系数,降低单位液化产品的能耗,提高循环效率。找到分析LNG冷量有效的方法,对实践中利用LNG冷量有积极的意义。

综合利用低品位余热与LNG冷能的复合循环系统

提出了一种可以实现低品位热能与液化天然气(LNG)冷能综合利用的复合式循环系统,以实现不同温度区间的循环匹配及热能梯级利用,并运用热力学定律对循环系统各部分性能进行热力性能分析,研究了复合循环系统各部分关键参数对系统性能的影响。结果表明:在给定工作条件下,系统的净发电效率和可用能效率分别达到了39.4%和47.33%;系统性能受循环工质状态参数和质量流量变化的共同影响,两者的综合作用效果决定了系统的优化方向。

基于LNG冷能的发电技术

液化天然气将成为人类在21世纪的主要能源之一。该文阐明了蕴涵在液化天然气中的巨大冷能利用价值,并指出两种利用方式:改善现有动力循环和相对独立的低温动力循环。前者主要体现在与燃气轮机及锅炉余热结合上,分析结果表明系统的热效率和火用效率普遍较高;后者则主要包括低温条件下的Rank ine循环、B rayton循环以及改进和复合的循环。总结了各种利用途径的特点和效果,同样说明了相当可观的液化天然气冷能利用价值。根据研究现状,最后指出了有待进一步研究和解决的诸多问题。

采用液化天然气(LNG)冷量的液体空分新流程及其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4.6 MPa降低到了2.6 MPa,液态产品的单位能耗降低约53%。对流程的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。

LNG冷能的梯级利用

液化天然气(LNG)中蕴含大量的冷能,具有很高的经济价值,国内外许多专家学者和商业机构提出了种种回收方案,但这些方案多数没有考虑合理用能。本文主要从能量和能质匹配的角度,利用火用的概念,探讨如何对LNG的冷能进行梯级利用,以期达到合理用能,使火用损失尽量减少。

高效利用LNG冷能的途径探析

阐述进口LNG冷能的利用价值,包括经济价值、环保价值。从技术环境、产业政策制约因素等方面分析了该产业的发展环境。同时分析了各种高效利用冷能的途径,从技术成熟性、发展空间、冷能利用效率和主要产品的竞争力4方面对利用方案进行比选。利用方案包括:冷能空分、冷能发电、低温粉碎、海水淡化、生产液体二氧化碳和干冰、冷冻冷藏、轻烃分离和分布式能源等。

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。

液化天然气(LNG)冷能分析及利用初步研究

本文分析了现有的多种LNG冷能利用的方式,并从原料、市场、冷能利用效率、与LNG接收站工艺相匹配、经济效益等多方面进行了对比分析。根据山东LNG接收站的实际特点,提出了利用LNG冷能进行空气分离是山东LNG接收站下一步利用LNG冷能的首选方案。

利用LNG冷量的空气分离流程的模拟与分析(英文)

介绍了一种利用液化天然气(LNG)冷量用于空气分离的流程,并采用模拟软件Asp-en Plus对整个流程进行了模拟与分析.计算结果表明,利用LNG冷量的空分装置,单位液体空分产品的生产能耗由传统装置的1.000 kW.h.kg-1降低至0.300 kW.h.kg-1,节能效果显著.LNG经空气分离装置回收利用冷量后,其温度仍然很低,剩余的冷量可继续用于低温粉碎和冷库等项目.作者对空气分离流程中的主要设备进行了模拟分析,并且分析了循环氮气被压缩至不同的压力对单位空分产品能耗的影响,结果表明,循环氮气压缩的压力越高,则LNG的用量越少,但单位液体空分产品的能耗基本不变.