Effect of 37Cl enrichment on neutrons in a molten chloride salt fast reactor

A molten chloride salt fast reactor(MCFR)is well suited to fuel breeding and the transmutation of transuranium(TRU)elements owing to its advantageous features of fast neutron spectrum and high TRU solubility.However,the neutron absorption cross section of 35Cl is approximately 1000 times greater than for 37Cl,which has a significant impact on the neutron physical characteristics of a MCFR.Based on an automatic online refueling and reprocessing procedure,the influences of 37Cl enrichment on neutron economy,breeding performance,and the production of harmful nuclides were analyzed.Results show that 37Cl enrichment strongly influences the neutron properties of a MCFR.With natural chlorine,233U breeding cannot be achieved and the yields of S and 36Cl are very high.Increasing the 37Cl enrichment to 97%brings a clear improvement in its neutronics property,making it almost equal to that corresponding to 100%enrichment.Moreover,when 37Cl is enriched to 99%,its neutronics parameters are almost the same as for 100%enrichment.Considering the enrichment cost and the neutron properties,a 37Cl enrichment of 97%is recommended.Achieving an optimal neutronics performance requires 99%37Cl enrichment.

Thermodynamic and Equilibrium Composition Analysis of Using Iron Oxide as an Oxygen Carrier in Nonflame Combustion Technology

Nonflame combustion technology （NFCT） is a harmonious energy utilization technology. There are not environmental-unfriendly gases such as NOx, CO2 discharged in the whole combustion process. Combustion processes realizes zero emission through this technology. Fe2O3 is involved as oxygen carrier, is examined thermodynamically, and the thermodynamic data of the redox reactions are calculated. Using the criteria of minimizing the Gibbs free energy, the equilibrium composition was investigated. The equilibrium analysis shows that producing complete oxidized resultants must have high molar ratio of Fe2O3/CH4. If quantity of Fe2O3 is not sufficient, more partial oxidized products such as CO, H2, even C will be produced.

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.

Thermodynamic Analysis and Experimental Investigation into Nonflame Combustion Technology(NFCT) with Thermal Cyclic Carrier

The utilization of fossil fuels causes serious negative impacts on the environment and human life. To mitigate greenhouse gases and other pollutants, a novel combustion process-the nonflame combustion technology with a thermal cyclic carrier of molten salt is introduced. In this technology, a whole combustion is divided into two steps, i.e., the section of producing oxide and the section of combustion. In the first step, oxygen is separated from air, and pure N_2 is simultaneously formed which is easily recovered. In the other step, the fuels react with lattice oxygen in the oxides formed in the first step, and at the same time, thermal energy, CO_2 and H_2O vapor are produced. It is noted that the CO_2 is easily separated from water vapor and ultimately captured. Theoretically, there are no environmental-unfriendly gases such as CO_2, NO_x and SO_2 discharged in the whole combustion process. Some metal oxides scattered into molten salts play the roles of oxygen carriers in the combustion system, and they can constantly charge and discharge oxygen element from air to fuels during the combustion process. A nonflame combustion system with Li_2CO_3+K_2CO_3+Na_2SO_4 as the molten salt system, CH_4 as the fuel and CuO as the catalyst was experimentally investigated. The experimental results show that the combustion process proceeded as it was theoretically analyzed, and CO_2 with a high volume fraction of 77.0%_95.0% and N_2 with a high volume fraction of 91.9%_99.3% were obtained. The high concentration of CO_2 is favorable for capturing and storing subsequently. Therefore, the potential of reducing CO_2 emissions of this nonflame combustion technology is huge.

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.

熔盐塔式太阳能吸热器传热特性计算模型研究进展

熔盐塔式太阳能热发电技术是目前国际主流的光热发电技术,熔盐吸热器作为将太阳能转换为热能的核心设备,其性能直接影响系统发电效率,吸热器安全性影响电厂运行小时数。因此,建立熔盐吸热器传热模型,获得准确的传热特性十分重要。对主流的外置圆柱式熔盐吸热器的传热计算模型进行了系统梳理,总结了传热模型中投入辐射能、辐射热损失、对流热损失及熔盐得热量的计算过程及基本方法。根据计算结果的精细程度,吸热器传热模型分为详细模型和简化模型。详细模型的计算精度高,能细致反映实际能量转换过程,但计算成本较高,瞬态过程计算耗时多,但其特定工况的计算结果可为简化模型提供计算结果的验证参考。简化模型是对描述熔盐吸热器传热特性的理论模型做合理简化,在较为准确地完成计算的同时具备较快的计算速度,多用于吸热器设计阶段。通过各模型特点及性能的总结对比,可为熔盐吸热器热性能计算过程的传热模型选择提供技术指导。

滨海盐渍土易溶盐竖向分布特征及其腐蚀性研究

通过对山东潍坊北部沿海地区盐渍土的试验研究,分析了易溶盐含盐量、Cl^(-)、SO_(4)^(2-)含量的竖向分布特征及盐渍土的腐蚀特性,提出了适宜的防腐措施。结果表明:研究区土质以氯盐型盐渍土为主,易溶盐含量随土层深度的增加而逐渐减少并趋于稳定,土质中Cl^(-)是本区域最主要的腐蚀因子,显示对钢筋、砖、水泥、石灰的中到强腐蚀性作用,针对结构、基础及地基处理提出了防腐措施,同时提出了适宜本地区的桩基础施工新技术,对建筑防腐具有一定的借鉴意义。

高频加热-红外光谱法测定氯化熔盐中碳含量

碳是熔盐氯化的重要反应物之一,其含量影响氯化反应的进度。因此,准确测定熔盐中碳含量,对指导生产有重要意义。氯化熔盐属高氯样品,目前用管式炉或高频炉燃烧,红外吸收法测定熔盐中碳含量时,存在无相应标准样品建立仪器标准工本曲线和燃烧产生的氯气易腐蚀仪器的问题。实验提出用氯化钠稀释石油焦标准样品,配制不同浓度的碳校准样品,同时对仪器试剂管改装,以石英砂-氢氧化钙(3∶1)吸收氯气,可以有效解决上述问题。此外,实验还研究了高频功率、助熔剂对碳测定的影响,以高频加热-红外吸收法测定氯化熔盐中碳含量。实验结果表明:加入0.5 g纯铁、1.0 g钨锡混合助熔剂,高频功率为70%时,碳完全氧化成二氧化碳;采用人工合成校准样品建立标准曲线,碳的质量分数在0.86%~6.46%范围内,线性良好,满足生产控制要求。

电阻炉加热-库仑电解法测定氯化熔盐中碳含量方法研究

碳是熔盐氯化重要反应物之一,其含量直接影响钛矿中二氧化钛的氯化效率,同时对维持氯化炉热平衡有重要作用。氯化熔盐属高氯样品,目前用管式炉或高频炉燃烧,红外吸收法测定熔盐中碳含量时,存在无相应标准样品建立仪器标准工作曲线和燃烧产生的氯气易腐蚀仪器的问题。实验研究了电阻炉加热-库仑电解法测定氯化熔盐样品中碳含量的方法,通过对仪器净化系统改造,以0.2 mol/L氯化亚铁溶液吸收燃烧生成的氯气,有效解决了氯对碳测定的干扰;其次,用氯化钠稀释石油焦标准样品,配制不同浓度的碳质控样品,有效对实验过程及仪器状态监控,确保测量结果准确。实验结果表明:当样品量为400~450 mg,加热温度1150℃时,氯化熔盐中碳完全氧化成二氧化碳。采用实验方法对样品及质控样品测量,方法精密度小于1.0%,质控样品测量结果与理论值相符。

富氧燃烧-红外吸收法测定氯化熔盐中游离碳含量方法研究

游离碳是熔盐氯化重要反应物之一,对二氧化钛氯化反应速率影响较大,准确测定熔盐中游离碳含量,对控制氯化反应及炉料添加有重要指导意义。氯化熔盐属高氯样品,目前用管式炉或高频炉燃烧,红外吸收法测定熔盐中碳含量时,存在无相应标准样品建立仪器标准工作曲线和燃烧产生的氯气易腐蚀仪器的问题。实验提出用氯化钠稀释石油焦标准样品,配制不同浓度的游离碳校准样品,同时对仪器试剂管改装,以石英砂-氢氧化钙(m_(石英砂)∶m_(氢氧化钙)=3∶1)吸收氯气,有效解决上述问题,实验还讨论了燃烧温度、氧气压力、样品量对游离碳测定的影响。实验结果表明:当样品量为0.15 g,燃烧温度700℃、氧气压力0.50 MPa时为氯化熔盐中游离碳的最佳测量条件。采用实验方法对生产过程中氯化熔盐样品及配制的校准样品测量,方法精密度小于2.0%,校准样品测量值与理论值在实验允许误差范围内。

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。

Molten hydroxide for detoxification of chlorine-containing waste: Unraveling chlorine retention efficiency and chlorine salt enrichment

Hazardous waste dechlorination reduces the potential of creating dioxins during the incineration process. To investigate the salt effect on waste dechlorination, molten hydroxides with a low melting temperature were utilized for the pre-dechlorination and decomposition of chlorine-containing organic wastes(COWs) including trichlorobenzene(TCB),perchloroethylene, hexachlorobenzene and chlordane. The results showed that a eutectic mixture of caustic sodium and potassium hydroxides(41 wt.% NaOH and 59 wt.% KOH) led to a low melting point below 300°C and a relatively high chlorine retention efficiency(CRE) with TCB as a representative COWs. The amounts of hydroxides, reaction time, and temperature all had notable influence on CRE. When the mass ratio of hydroxides to TCB reached 30:1,approximately 98.1% of the TCB was destroyed within 2.5 hr at 300°C with CRE of 71.6%.According to the residue analysis, the shapes of reaction residues were irregular with particles becoming swollen and porous. The benzene ring and C–Cl bonds disappeared, while carboxyl groups formed in the residues. The stripped chlorine was retained and condensed to form chloride salts, and the relative abundance of the chloride ions associated with the mass of TCB in residues increased from 0 to 75.0% within the 2.5 hr reaction time. The observed concentration of dioxins in residues was 5.6 ngTEQ/kg. A reaction pathway and possible additional reactions that occur in this dechlorination system were proposed. Oxidizing agents may attack TCB and facilitate hydrogenation/dechlorination reactions, making this process a promising and environmentally friendly approach for chlorine-containing organic waste treatment.

熔盐电加热器在熔盐储能系统应用中的优化模拟分析

为了探究熔盐储能系统中熔盐电加热器不同布置形式的优劣问题,以某熔盐储能项目为研究对象,分析系统中熔盐电加热器的布置特点及其内部的熔盐工质热动力模拟,总结不同布置形式的利弊,为熔盐储能项目中熔盐电加热的布置设计提供参考。

混合氯化熔融盐的腐蚀性实验

混合氯化盐是一种非常有前途的高温传热蓄热介质。为了确定混合氯化盐传热蓄热系统适用的金属材料,本文对2520、304、321和316L四种常用不锈钢在混合氯化盐中的腐蚀情况进行了实验研究,并与混合硝酸盐的腐蚀特性进行了对比。结果表明,混合氯化熔盐比混合硝酸盐对四种不锈钢的腐蚀性要大几十倍,混合氯化盐对四种不锈钢腐蚀速率从大到小依次为316L、304、321和2520。

TiCl_4熔盐氯化炉熔盐体系恶化原因分析及稳定控制措施探究

总结了评价TiCl4熔盐氯化炉熔盐体系性能优劣的表征参数,并对其影响因素进行了初步分析。结合生产实践,分析了TiCl4熔盐氯化过程熔盐体系恶化的原因;根据熔盐体系恶化的原因及相关影响因素,提出了稳定控制熔盐体系的措施。

高钛渣加碳氯化反应热力学在熔盐氯化中的应用

通过对高钛渣各组分氧化物加碳氯化反应的热力学计算与分析,发现循环氯气中的氧气与石油焦的燃烧反应是影响熔盐氯化炉温度的主要因素,而炉温的稳定控制是提高熔盐氯化炉运行效率的关键;在900-1 500 K时,高钛渣加碳氯化热力学趋势表明：所有氧化物在氯化过程中全部转变为氯化物,但实际反应中Al2O3、尤其是SiO2仅有很小一部分被氯化,同时确定了此温度区间各组分氧化物加碳氯化难易顺序;热力学条件对TiO2和SiO2氯化率的影响近于一致,所以从热力学角度不能进一步有效降低SiO2的氯化率而减少TiCl4中Si含量。

氯化物熔盐中钙镁离子固化工艺的热力学分析

分析了在高钛渣熔盐氯化过程中氯化物熔盐介质物化性能恶化的原因,并提出钙镁离子固化工艺以改善氯化物熔盐介质的物化性能,通过热力学研究了钙镁离子固化工艺的可行性。固化剂与钙镁离子反应的吉布斯自由能均小于零,反应均能自发进行。当以Na2SO4作为固化剂,温度低于1 073 K时,氯化物熔盐中kp=[Ca2+][SO24-]和kp=[Mg2+][SO42-]均小于2.5×10-3;当以Na3PO4作为固化剂,温度低于1 173 K时,kp=[Ca2+][PO43-]2/3<2.5×10-6,kp=[Mg2+][PO43-]2/3<1×10-7。

石油焦中硫含量对熔盐氯化过程的影响

利用HSC软件计算了硫在熔盐氯化过程中发生化学反应的标准吉布斯自由能,研究了石油焦中硫含量对粉磨性质、熔盐氯化过程控制、粗四氯化钛质量和精制除杂的影响。结果表明,硫在熔盐氯化体系中的主要反应产物是SO_2、COS、SO_2Cl_2和SOCl_2;硫含量不会影响熔盐氯化过程连续稳定运行,但会导致熔盐、收尘渣、尾气和粗四氯化钛中硫含量增大;硫在精制过程中难以除去,应选择硫含量低于0.45%的石油焦。

海绵钛生产中熔盐氯化废渣无害化处理的研究

海绵钛生产过程中熔盐氯化所产生的废渣含有大量的水溶性氯化物,对环境污染较大。本文对熔盐氯化废渣无害化处理进行了研究,探索适合的水溶处理条件,制定方案,在降污减排的同时获得一定的经济效益。

锂及其含锂合金的研究与应用现状

对锂、含锂及锂合金的研究情况进行总结,综述金属锂的制备工艺,Al-Li合金、Mg-Li合金的特性、性能改善途径及制备工艺,锂合金热电池阳极材料的研究概况。还阐述了含锂及锂合金的应用现状。