Research progress on protective coatings against molten nitrate salts for thermal energy storage in concentrating solar power plants

Concentrating solar power(CSP) has garnered considerable global attention as a reliable means of generating bulk electricity, effectively addressing the intermittent nature of solar resources.The integration of molten salt technology for thermal energy storage(TES) has further contributed to the growth of CSP plants;however, the corrosive nature of molten salts poses challenges to the durability of container materials, necessitating innovative corrosion mitigation strategies.This review summarizes scientific advancements in high-temperature anticorrosion coatings for molten nitrate salts, highlighting the key challenges and future trends.It also explores various coating types, including metallic, ceramic, and carbon-based coatings, and compares different coating deposition methods.This review emphasizes the need for durable coatings that meet long-term performance requirements and regulatory limitations, with an emphasis on carbon-based coatings and emerging nanomaterials.A combination of multiple coatings is required to achieve desirable anticorrosion properties while addressing material compatibility and cost considerations.The overall goal is to advance the manufacturing, assembly, and performance of CSP systems for increased efficiency, reliability, and durability in various applications.

Electrochemical Lithium Storage Performance of Molten Salt Derived V_(2)SnC MAX Phase

MAX phases are gaining attention as precursors of two-dimensional MXenes that are intensively pursued in applications for electrochemical energy storage.Here,we report the preparation of V_(2)SnC MAX phase by the molten salt method.V_(2)SnC is investigated as a lithium storage anode,showing a high gravimetric capacity of 490 mAh g−1 and volumetric capacity of 570 mAh cm^(−3) as well as superior rate performance of 95 mAh g^(−1)(110 mAh cm^(−3))at 50 C,surpassing the ever-reported performance of MAX phase anodes.Sup-ported by operando X-ray diffraction and density functional theory,a charge storage mechanism with dual redox reaction is proposed with a Sn-Li(de)alloying reaction that occurs at the edge sites of V_(2)SnC particles where Sn atoms are exposed to the electrolyte followed by a redox reaction that occurs at V_(2)C layers with Li.This study offers promise of using MAX phases with M-site and A-site elements that are redox active as high-rate lithium storage materials.

Comprehensive Molten Salt Storage Shell and Supporting Structure Design and Analysis-Part I:A Conductive and Convective Theoretical Heat Transfer Analysis for Molten Salt Cylindrical Shells at 565℃ and 700℃

In this paper a full theoretical thermal analysis of a large molten salt container,80-foot in diameter and 46-foot high,including a four-foot elliptic shell roof,is presented for two temperatures,the standard 565℃ and a futuristic 700℃,which substantially improves the efficiency of the molten salt containers through the use of a highly stable chloride salt called SS700(SaltStream 700).The theoretical analysis includes conductive and convective heat transfer analysis in the steel container,elliptic roof shell,the fiberglass insulation,and firebrick insulation,and includes thermal insulation designs to safeguard against energy losses at high temperatures.The underlying soil and the high temperature concrete foundation were analyzed theoretically using conductive heat transfer,however the area surrounding the soil surface around the bottom of the molten salt storage tank had convective heat transfer analysis included.The final designs presented in this paper seek to limit heat losses to a maximum of 250 W/m^(2) while being able to operate at a minimum external ambient temperature of-10℃,which determines the thicknesses of the fiberglass and firebrick insulation.

Molten Salts and Applications Ⅱ: 565℃ Molten Salt Solar Energy Storage Design, Corrosion, and Insulation

Excess energy from various sources can be stored in molten salts (MS) in the 565 °C range. Large containers can be used to store energy at excess temperatures in order to generate eight hours or more of electricity, depending on the container size, to be used during peak demand hours or at night for up to a week. Energy storage allows for a stable diurnal energy supply and can reduce the fluctuation due to weather conditions experienced at thermal solar power stations. Supported by Office of Naval Research (ONR), this paper discusses the design considerations for molten salt storage tanks. An optimal molten salt storage tank design layout is presented, as well as alternative designs for the storage tanks. In addition, the costs and corrosion effects of various molten salts are discussed in order to show the effects these considerations have on the design process.

Molten Salts and Applications Ⅲ: Worldwide Molten Salt Technology Developments in Energy Production and Storage

Supported by Office of Naval Research (ONR), this paper presents a survey of molten salt technology used in solar power storage. Excess energy from solar power stations and other baseline power production methods can be stored in molten salts (MS) in the 565°C range, therefore allowing the use of large containers to store energy for up to a week and generate eight hours of electricity or more to be used during peak demand hours, at night, or adverse weather conditions, depending on the container size. The technology could also be used to conserve the spin off energy in the grids from nuclear or coal power production. Real life examples of concentrating solar power (CSP) plants, both domestically and worldwide, are presented with details about the type of solar collection, capacity, and energy production. Commercial solar power stations have been constructed in the United States and overseas, particularly in Spain, with molten salt being considered for use in these facilities. Some facilities use a field of flat mirrors and collection towers while others use parabolic troughs.

Comprehensive Molten Salt Storage Shell and Supporting Structure Design and Analysis-Part II:A Conductive and Convective Numerical Finite Element Heat Transfer Analysis for Molten Salt Cylindrical Shells at 700℃,and Comparison with Theoretical Analysis

In this paper a finite element thermal analysis model-using COMSOL-of a large molten salt container,80-foot in diameter and 46-foot high that includes a four-foot elliptic shell roof,is presented for a futuristic 700℃ design,which uses a highly stable chloride salt called SS700(SaltStream 700)that improves the efficiency of the tank when compared to the traditional 565℃.The FEA(finite element analysis)includes conductive and convective heat transfer analysis in the steel container,elliptic roof shell,the fiberglass insulation,and firebrick insulation,and includes thermal insulation designs to safeguard against energy losses at high temperatures.The underlying soil and the high temperature concrete foundation were analyzed by finite element using conductive heat transfer,however the area surrounding the soil surface around the bottom of the MS storage tank had convective heat transfer analysis included.The finite elements analyses presented are to verify the final fiberglass and firebrick insulation designs,which seeks to limit heat losses to a maximum of 250 W/m^(2) while being able to operate at a minimum external ambient temperature of-10℃.These results are also compared to previously calculated theoretical results.

Molten Salts and Applications Ⅰ: Molten Salt History, Types, Thermodynamic and Physical Properties, and Cost

Excess energy from solar, nuclear or coal power stations can be stored in molten salts (MS) in the 565 °C range. At elevated temperature, large containers can be used to store energy for up to a week and generate eight hours or more, depending on the container size, of electricity to be used at night or during peak demand hours. A stable diurnal energy supply is made available by energy storage and the fluctuation experienced at thermal solar power stations caused by weather conditions is reduced. Supported by Office of Naval Research (ONR), this paper presents a survey of molten salt properties used in solar power storage, as well as the history of molten salt usage for energy storage and production. The history of molten salt usage includes past, current, and future developments involving molten salt usage for nuclear and solar energy storage and production. Density, melting temperature, viscosity, electric conductivity, surface tension, and heat capacity of various molten salts are discussed. Since costs are important factor in selecting a molten salt compound, salts costs are presented. Recommendations are made regarding the efficient use of various types of molten salt.

熔盐储热耦合压缩空气储能系统经济性分析

压缩空气储能作为一种大规模物理储能技术,广泛应用于可再生能源消纳和电网削峰填谷。设计了一种耦合熔盐储热的压缩空气储能系统,采用Ebsilon软件对复合系统进行建模仿真。基于该储能系统对外供应热水、蒸汽、电能的工况,研究不同系统运行模式下的?效率、热效率以及经济性。结果表明:复合系统在储气压力为7 MPa、排气温度系数为1.96时系统?效率最高,达到64.98%;在储气压力12 MPa时系统热效率最高,达到91.55%;在热汽电三联供应用场景下,最佳储能时长为6 h,储气压力为7、12 MPa时,最优发电时长分别为6、8 h;该研究可为耦合熔盐储热压缩空气储能热电联供提供理论指导。

基于再热蒸汽抽汽-熔盐储热的火电系统分析

提出了一种基于再热蒸汽-抽汽熔盐储热的火电联合系统,通过建立仿真模型对系统的运行过程及效率进行了分析。为了使熔盐放热过程匹配主蒸汽温度,需要在抽汽充热过程之后再配置电加热器对熔盐提温,在此基础上研究了充热过程平均换热温差、放热过程夹点温差、低温储热温度对系统性能参数的影响。结果表明:充热过程中维持10 K平均换热温差,放热夹点温差从5 K增加至15 K会导致最高等效往返效率从88.2%降低至85.0%,同时最佳储热温度从314℃升高至324℃;放热过程中维持10 K夹点温差,充热过程的平均换热温差从5 K增加至15 K时,最高等效往返效率从89.5%降低至85.8%;2个温差均在10 K时,机组的最高等效往返效率为87.1%,该条件下运行时机组最低负荷可从30%下调至24.3%。

生物质废弃物有序能源化利用评述

基于我国生物质废弃物的产量、分布和利用现状,分析了生物质废弃物资源利用过程中转运能耗大和碳排放量高的现状,指出相比于压缩、干燥、烘焙等方法,低温热解预处理技术在生物质废弃物减容提质方面更具优势;论证了生物质废弃物减容提质预处理对其资源利用过程的降耗减排具有一定的作用,提出将具有调峰能力强、使用寿命长、规模化成本低、安全环保等优点的熔盐储能技术应用于生物质废弃物低温热解预处理中,并通过基于耦合熔盐储能的生物质废弃物低温热解处理工艺案例的综合分析,验证了该工艺的可行性和经济性。结果表明:由于熔盐储能对清洁能源电能的消纳及波谷电的存储利用,可有效提高生物质废弃物能源利用过程中的能量利用率,使碳排放量减少达378.49 t CO_(2eq)/a,并可获得良好的经济效益回报(内部收益率大于行业基准收益率),从而实现“无序”生物质废弃物的“有序”能源化利用,对双碳战略具有重要意义。

高温熔盐储能提升燃煤机组动态响应的分析

为了提高燃煤机组调峰负荷响应速率,基于Dymola软件的Modelon组件库,建立某600 MW超临界燃煤机组的动态模型,研究采用高温熔盐替换抽汽加热给水对燃煤机组主要参数动态特性的影响。研究结果表明:替换低压加热器(简称低加)比替换高压加热器(简称高加)对机组主、再热蒸汽和给水参数的影响更小,随着机组负荷的降低,机组负荷响应能力降低。高温熔盐替换高加时,负荷响应时间较长、负荷变化量较大、负荷平均变化速率较小,而高温熔盐替换低加时的效果相反,熔盐替换高加时的热电转化效率比替换低加要高。

热储能技术在新型电力系统中的应用综述

热能是能源的重要组成部分,全球约90%能源是热能的转换、传输和储存。随着“双碳”目标的提出,储能成为促进新能源大规模、高质量发展的新动能,其中热储能是储能中最具有应用前景的技术之一。分析国内外热储能最新发展动态,重点介绍熔盐储热和固体储热的典型应用场景和发展建议。热储能可为绿电供热提供热能储存,解决绿电供热成本高的问题,也为新型电力系统提供巨大的可调节负荷资源。

基于Cite Space与VOSviewer的熔盐储能研究可视化分析

通过Cite Space与VOSviewer软件对2010~2021年熔盐储能技术的相关文献进行可视化分析,明确了熔盐储能研究现状与热点。结果表明,随着时间的增加,发文量逐渐增加;国内主要以国家自然科学基金和地方自然科学基金为主,以熔盐、储能光热发电、太阳能,储能材料等为研究热点;国外主要以英国伯明翰大学和西班牙莱里达大学为主,形成了熔盐储能、系统性、高温熔融盐的腐蚀、熔盐影响因素等4大聚类主题。学术成果在英文期刊Solar Energy、Solar Energy Materials And Solar Cells和中文期刊《无机盐工业》《低碳世界》和《广州化工》等期刊发文量较大。

Corrosion evaluation and resistance study of alloys in chloride salts for concentrating solar power plants

Thermal energy storage(TES)systems based on molten salt are widely used in concentrating solar power(CSP)plants.The investigation of the corrosion behavior of alloy materials in molten salt is crucial for the correct selection of alloy materials and the design of TES systems.In this study,the corrosion behavior of 304,310S,316,and In625 alloys in molten chloride salts(27 mol%NaCl-22 mol%KCl-51 mol%MgCl,)was investigated.The evolution of mass loss of the alloy samples with corrosion time and temperature and the analysis of the experimental results by scanning electron microscopy(SEM),energy dispersive spectrometer(EDS),and X-ray diffraction(XRD)revealed the corrosion mechanism of the alloy samples in molten chloride salts.The main factors affecting the corrosion of the alloy samples were further analyzed.It was found that the loose multi-layer corrosion was formed on the surface of the corroded alloy samples with the increase in corrosion degree.Moreover,the experimental results.showed that Mo played a positive role in improving the corrosion resistance of the alloy samples because the presence of Mo could inhibit the outward diffusion of alloying element Cr.This work enriches the molten salt corrosion database and provides a reference for the selection of alloy materials for TES systems with potential application in CSP plants.

新建350MW超临界机组耦合熔盐储热系统方案研究

本文设计了一种燃煤机组耦合熔盐储热系统新型技术方案,依托某新建350MW超临界机组灵活性调峰项目,提出采用抽汽+电加热联合式加热熔盐的技术路线。为提高系统效率并最大化利用高温蒸汽携带的热量,抽取的主汽采用部分凝结释放潜热加热熔盐的方案,抽取的主汽未凝结部分与熔盐换热后回到再热器冷段,解决了因抽主汽流量过多导致的再热器壁温超温问题,该方案不需要对现有机组方案做任何改动,在保证系统安全稳定高效运行的同时,能够使机组实现从30%THA负荷降至20%THA负荷的深调目标。

熔盐蓄热技术在提高钢厂能源效率中的作用

钢铁企业作为能源消耗大户,在能源资源日益紧张的情况下,迫切需要采取有效措施提高能源利用效率。熔盐蓄热技术作为一种新兴的能源利用技术,为钢厂提供了一种有效途径。文章对熔盐蓄热技术进行了一定论述,明确了其基本原理、构成及工艺流程等,在此基础上,进一步分析了熔盐蓄热技术在钢厂能源效率提升中的作用,并探讨了其在钢厂能源系统中的具体应用,有助于促进钢厂能源效率的不断提高。

一种“绿电”熔盐储能系统的建模与动态特性研究

提出一种“绿电”熔盐储能系统,同时对熔盐储热系统的关键设备进行了机理模型分析,并进行了数学模型辨识实验和动态特性分析。结果表明:熔盐储热系统普遍具有大惯性的特点,通过设计多级加热和换热装置可以有效控制熔盐系统中熔盐和蒸汽的温度、流量和压力等参数的变化,提高供热蒸汽的品质,保证整套系统的运行稳定性,满足工业现场供热与发电需求。

670 MW燃煤机组耦合熔盐储能系统方案设计及性能分析

为应对新能源发电机组的反调峰特性对电网平稳运行带来的挑战,煤电机组急需提高灵活性运行和深度调峰能力。针对某670 MW一次再热机组,设计了利用蒸汽引射器调配再热器蒸汽入口流量等9种储-释能方案,基于Ebsilon软件建立热力仿真模型并对耦合系统的各项性能进行了分析。研究结果显示:所有方案均能有效拓宽机组的调峰区间;储热时相同调峰深度下抽汽储热方式的热经济性优于电加热储热,集成蒸汽引射器调配抽汽补偿再热入口流量的储热方案可以有效地解决大量抽取主蒸汽带来的再热器超温问题;释热时高温熔盐加热高压给水可以获得更好的热经济效益;储-释热组合方案C1-S2表现出最好的经济性能,其向上调峰深度达到76.89 MW,循环热效率和?效率分别达到42.48%、41.31%。

基于光热的熔盐储热技术现状及发展趋势

针对常规太阳能利用具有间歇性和不稳定性等问题,介绍了光热技术在光热发电和太阳能直接热利用方面配备储热系统实现太阳能稳定供热的研究进展。总结了目前储热技术的分类方法和技术应用场景,综述了主流熔盐储热体系(碳酸盐、氯化盐、氟化盐、硝酸盐)的技术原理和研究进展,指出不同熔盐储热体系的优势和存在的技术问题。针对熔盐储热的技术关键,总结了在光热技术领域不同场景下的研究现状和工艺流程,并归纳出熔盐储热体系在光热领域的发展趋势。一是根据应用场景选择合适的集热方式,优化光热集热、熔盐储热的容量配置和协调控制;二是研发更低熔点、更宽液体温域、低腐蚀性的熔盐来提高熔盐储热的适用性;三是降低成本的同时兼顾熔盐储能系统运行的安全、稳定性,为未来熔盐储热技术的应用发展提供参考。

熔盐储热技术在油田生产的探索与应用

在全球能源加速转型、我国新能源转向全面推广的关键期,减少化石能源消耗首当其冲。目前国内油田在生产过程中化石能源消耗普遍占比较高,都在积极开展绿色低碳转型发展。熔盐储能技术是利用熔盐高热容、高分解温度、高流动性、低腐蚀性等特点,以其作为储热介质,将谷时电或绿电等以热能的形式储存起来,再利用储存的热能放热进行工业生产的技术,该技术已广泛应用于太阳能光热发电、火力发电机组的调峰调频、供暖与余热回收利用等领域.目前对熔盐储热技术的研究普遍以太阳能光热发电为中心展开,探索熔盐储热技术如何在油田生产系统中得到应用,分析熔盐物性,研究其蓄热温度区间,适宜的加热方式、关键设备部件及系统工艺流程等,实现以较为低廉的谷时电加热熔盐进行储热放热循环,满足油田生产加热需求,提高油田绿电消纳水平,减少化石能源消耗,对于“双碳”目标实现意义重大。