Experimental study on the jet characteristics of a steam plasma torch

Thermal steam plasma jet is promising for applications in environmental industries due to its distinctive characteristics of high enthalpy and high chemical reactivity. However, the performance of the steam plasma torch for its generation is limited by the problems of the large arc voltage fluctuation and serious erosion of the electrodes. In this study, a gas-stabilized steam plasma torch which can operate continuously and stably was designed. Experiments were conducted to reveal the effect of the different working parameters, including the anode diameter, the cooling water temperature, the arc current and the steam flow rate, on its Volt-Ampere characteristics, arc voltage fluctuation, thermal efficiency, jet characteristics and electrodes erosion. Results showed that the use of hot water to cool the electrodes can effectively prevent the condensation of steam on the inner wall of the electrodes, thus significantly reducing the arc voltage fluctuations and electrodes erosion. This is crucial for increasing the working life of the electrodes and ensuring long-term stability of the steam plasma torch. In addition, suitable anode diameter can greatly reduce the arc voltage fluctuation of the steam plasma torch and effectively improve the stability of the steam plasma jet. Furthermore, high arc current can effectively reduce the fluctuations of the arc voltage and increase the length and the volume of the steam plasma jet. Finally, using steam as the plasma forming gas can achieve higher thermal efficiency compared to air. An ideal thermal efficiency can be achieved by properly reducing the arc current and increasing the steam flow rate.

Numerical Simulation of Direct-contact Condensation from a Supersonic Steam Jet in Subcooled Water

直接接触的冷凝作用的现象，在驾驶的蒸气使用喷气注射者，核反应堆紧急情况核心冷却系统和直接接触的热 exchangers，被在使过冷的水里为蒸气的直接接触的冷凝作用介绍一个热平衡模型计算地调查。介绍的冷凝作用模型是在接口的双方上照顾热转移过程并且使用一条可变蒸气水泡直径的二个抵抗模型。在使过冷的水坦克的超声的蒸气喷气的注射用 Euler-Euler 多相的流动模型被模仿流畅与冷凝作用模型一起的 6.3 代码合并了。模拟与出版试验性的数据和相当好的同意相比的计算液体动力学(CFD ) 的调查结果被观察在之间二，因此验证冷凝作用模型。为羽毛从 2.73-7.33 改变的蒸气的无尺寸的穿入长度的 CFD 模拟的结果，当冷凝作用热转移系数从 0.75-0.917 MW 汯敹桴牥?晬湯 ? 变化时 ???? 琠楲敭潳汹？？

A Study of the Jet System of the Recovery Concerning Waste Heat of Steam Condensate

This paper presents a frame figure of the recovery system concerning waste heat of steam condensate. When steam phase changes into liquid state in the condenser, the heat equilibium equation, gas state equation, mass flow calculating equation of the jet steam and incondensable gas equation are established. The coupling function between condensate unit and recovery pump of the hot condensate with ejector is studied. The paper sets up the fluid continuity equation, heat equilibium equation and efficiency equation of the ejector and points out the technical key how the prevent hot condensate change into steam phase. When fluid passes from circulation loop through pump to export, the energy equations are obtained here. At last, signal figure of the applied examples are given and settle the techanical questions of the jet system are discussed.

基于计算流体动力学的二次侧管板高压水射流喷嘴仿真

本文利用混合物模型的两相流仿真了核电站蒸汽发生器二次侧冲洗需要的高压水射流喷嘴中的流场分布和压力分布。通过有限元方法计算了两相流模型,获得了流场分布和压力场分布。从流场分布可以看出,当逐渐远离高压水射流喷嘴的中轴线时,高压水射流中的流场分布逐渐减小;在高压水射流喷嘴的中轴线处,流场最大;当高压水射流喷嘴的入口压力从40MPa逐渐增大到46MPa时,出口处的流场逐渐增大,从289.502m/s逐渐增大到312m/s,在一定范围内入口压力对出口流速的增加效果显著。

汽水双射冷凝制冷机性能测试分析

基于射汽射水真空泵独特的稳定性与高真空性能,分析了射汽射水真空制冷机原理特点,阐述了汽水双射冷凝制冷机制冷原理。通过实际测试系统,对射汽泵进行了增焓、混合大气等新的性能提升工况测试验证,对冷端不同制冷水量对汽水双射冷凝制冷机性能影响进行了测试验证,并获得了实验数据和结论。

New Formulation for Semi-Empirical Correlations for Penetration Jets

Correlations for the extension of a water vapor jet injected in a liquid pool were historically proposed considering the mass flux (kg/m2/s) as a constant. The results were satisfactory, however adjusting the values by linear regression. Although, it presents the following drawbacks: 1) the formulation is only valid for the specific range of data for what it was created;2) it does not allow the analytical evaluation of the heat transfer coefficient from the extension equation. This paper proposes a new formulation for the calculation of the mass flux, in such a way to remove both of these drawbacks.

Investigation of the interaction of material of fuel cladding for WWER-1000 reactor with steam at a temperature of accident overheatings

The subject of this study is the oxidation of fuel rod cladding made of material Zr1Nb(0.1% O) in steam at temperatures in the range of 660℃ to 1200℃ with a surface in the initial state (after manufacturing - grinding) and after additional chemical etching. The changes in the microstructure of tubes due to the interaction with steam were investigated. A comparison was made between the oxidation rate of this material (weight gain) and the data on the oxidation of other alloys for nuclear power plants. The oxidation rate of Zr1Nb(0.1% O) is close to the oxidation rate of other zirconium alloys. It is shown that after chemical treatment of the surface of the samples there is a more even growth of oxide films, and they have a smaller thickness for the same time of exposure than after mechanical grinding. Surface treatment before oxidation also affects the change of microstructure of samples when heated to high temperatures.

海湾扇贝热处理开壳装置设计与试验

随着我国水产养殖业发展,海湾扇贝养殖量逐年上升,因其营养价值、药用价值高,受到广大消费者青睐。开壳工作是海湾扇贝加工重点,其内部有使两壳拉紧闭合的闭壳肌,开壳难度大。通过对海湾扇贝开壳方案研究,结合海湾扇贝生理结构特点,总结扇贝热处理开壳方案,并对火烤开壳、水浴冲击开壳、蒸汽喷射开壳3种热处理方案进行试验,选出最佳热处理方案是蒸汽开壳法。设计海湾扇贝蒸汽喷射开壳装置,对关键部件中仿形孔和成形刀进行尺寸及安装位置设计分析。以蒸汽喷射时间、蒸汽喷射距离、蒸汽阀门开度为试验因素,开壳效果感官评分为指标进行单因素试验,并通过Box-Behnken design进行因素交互试验分析,最终确定当蒸汽喷射3 s、喷射距离30 mm、蒸汽阀门开度90°时,开壳效果最佳,感官评分值为93.67分。通过对开壳方案的研究,解决扇贝开壳困难问题,改善扇贝加工脏乱差现状,填补我国扇贝加工工艺方案空缺,为提高我国扇贝加工机械化程度奠定基础。

基于RBF-ANN GA的水下空化水射流喷嘴结构优化

为使空化水射流的性能满足船舶水下清洁的需求,对喷嘴结构进行优化,提出一种基于径向基函数(RBF)、人工神经网络(ANN)和遗传算法(GA)的水下空化水射流喷嘴结构优化方法。通过数值模拟计算设计参数(如入口段长度、收缩段长度、圆柱段长度、扩散段长度、入口半径、圆柱段半径、收缩角和扩散角等)与空化性能参数轴线最大蒸汽体积分数的关系,通过RBF-ANN对该关系进行预测,解决采用GA进行结构优化时个体适应度难以计算的问题。将该方法与传统的方法进行对比,结果表明,该方法能快速且稳定地计算个体的适应度,相比传统方法能更有效地提升喷嘴的空化性能。

水蒸气喷射制冷系统中蒸汽喷射器性能研究

利用自然工质的水蒸气喷射制冷系统可有效利用低品位余热制冷,但系统性能受制于关键部件喷射器的性能,而有关研究中采用的理想气体模型,不能真实反映内部情况。通过建立蒸汽喷射器的湿蒸汽模型,着重研究流体参数对蒸汽喷射器引射性能的影响,并比较不同模型的差异。结果表明:湿蒸汽模型的引射系数高于理想气体模型6.92%;蒸汽喷射器存在临界压力值,超过临界值后,随着流体出口压力升高,引射系数下降;随着入口压力升高,引射系数先增加后减小,存在最佳工作流体入口压力;随着引射流体入口压力的增加,引射系数增加;引射系数随工作流体过热度的增加而增长,但随引射流体过热度的增加无明显变化。

不同流型下气溶胶水洗效果影响因素实验研究

在核电厂严重事故下,安全壳内混合气体通过喷射器注入到乏燃料水池中以降低安全壳超压失效的风险,同时减少放射性向环境的释放。本文建立了气溶胶水洗去除实验装置,研究水池对气溶胶的去除机制。开展了不同流型下通过喷射器的混合气体质量流率对气溶胶水洗净化系数(DF)的影响以及蒸汽冷凝对气溶胶去除效果的影响。结果表明:在注入流型为射流的情况下,由于射流注入区液滴拦截和惯性碰撞去除机制的增强,导致DF随着质量流率的增大而增大;在注入流型为气泡流的情况下,上升区气溶胶去除占主要作用,随着质量流率增大,气泡上升速度增快,导致气泡在水池内运动时间减少,DF降低。同时,在蒸汽存在的情况下,气溶胶去除效果明显增强,蒸汽冷凝是气溶胶去除的主要机制。

二维喷射液滴在重力场中的运动模型研究

准确高效的气液两相流模拟对于核蒸汽发生器的设计具有重要意义。欧拉-拉格朗日方法虽然可以准确模拟粒子运动,但其计算复杂度随着粒子数量的增加而显著增加,难以实际应用。因此,本文在对汽水分离装置中液滴运动物理机理解释的基础上,结合单液滴欧拉网格逼近模型,得到了大尺寸喷射液滴的欧拉网格模型,给出了欧拉网格逼近模型对较大尺寸喷射液滴的物理机理解释和数学表达,将欧拉网格逼近方法应用于实际AP1000重力分离空间中大液滴的计算,分析了3种尺寸喷射液滴在重力分离空间中的行为,为汽水分离等装置中的大液滴分析提供有效的计算分析工具。

船用电站汽轮发电机组抽气设备选型分析

抽气设备用于维持汽轮发电机组冷凝器和汽封系统的真空度,提高汽轮机的运行效率,保证机组安全可靠地运行。分析目前广泛使用的水环式真空泵、射水抽气器和射汽抽气器3种类型抽气设备的工作原理、功能流程和系统组成等,考虑船用汽轮发电机组的抽气设备要求结构尺寸小、系统组成简单和无须外供电源等特点,得出使用射汽抽气器是合理选择,也为业内相关研究提供参考。

LNG储罐泄漏扩散模拟分析

为预防液化天然气(LNG)储罐泄漏安全事故,利用PHAST软件,以湘潭新奥荷塘储配站的储罐为研究对象,探究不同泄漏孔径及风速2个条件对LNG蒸气云泄漏扩散距离及泄漏导致的喷射火与爆炸范围的影响机制。结果表明:蒸气云泄漏扩散距离、喷射火辐射影响半径及爆炸超压影响半径与泄漏孔径尺寸成正比,蒸气云泄漏扩散距离、爆炸超压影响半径与风速成反比。泄漏孔径为25 mm的泄漏场景,易燃易爆区临界距离、喷射火辐射死亡区半径、爆炸超压50 kPa对应超压半径分别是5 mm场景的10、7、8倍;泄漏孔径为100 mm的泄漏场景,易燃易爆临界距离、喷射火辐射死亡区半径、爆炸超压50 kPa对应超压半径分别是5 mm场景的37、21、33倍。

基于液气射流的负压蒸汽加热系统设计与试验

针对当前100℃以下的低温加热工艺在农业、化工、食品加工业中存在加热效率低、温度难以精确维持、自动化程度低、设备成本高等问题,集成射流泵抽空技术、PLC控制技术、控温调压技术,设计开发一种基于液气射流的负压蒸汽加热系统。该系统由智能控制系统、液气射流真空循环系统、降温调压系统和循环水调节系统组成,通过液气射流泵抽空提供蒸汽负压环境,结合减温减压装置和PLC智能控制系统对负压蒸汽进行控制,实现负压蒸汽对物料的精准自动化加热。详细阐述负压蒸汽加热系统的工作原理,确定关键部件射流泵设计结构和相关参数,并对其进行流体数值模拟的相关验证,模拟结果与实际误差在10%以内,表明射流泵设计合理可靠性高。对系统的加热性能进行试验,结果表明:基于液气射流的负压蒸汽加热系统可以精确控制蒸汽温度进行加热,同时加热温度曲线平缓,快速升温阶段真空度上下浮动0.003 MPa,平衡阶段真空度上下浮动0.002 MPa,加热温度浮动也在±1℃,更好地适应不同物料的加热温度,在加热效率方面优于水浴加热约2倍。该研究可解决传统水浴加热显热加热不均匀、控制精度差、加热过程缓慢、生产能力较低等问题,为农产品、化工产品深加工的加热方式、系统及装置提供新的思路与参考。

Combustion Characteristics of Solid Sustained-Release Energetic Materials

A solid sustained-release energetic material sample,an eruption device and a complete test system were prepared further to analyse the combustion characteristics of solid sustainedrelease energetic materials.The high-temperature heat flux generated by the combustion of the samples from the eruption device was used to penetrate the Q235 target plate.In addition,the meaning and calculation formula of energy density characterising the all-around performance of heat flux were proposed.The numerical simulation of the combustion effect of samples was carried out.According to the data comparison,the numerical simulation results agreed with the experimental results,and the maximum deviation between the two was less than 8.9%.In addition,the structure of the combustion wave and high-temperature jet was proposed and analysed.Based on theoretical analysis,experimental research and numerical simulation,the theoretical burning rate formula of the sample was established.The maximum error between the theoretically calculated mass burning rate and the experimental results was less than 9.8%.Therefore,using the gas-phase steady-state combustion model to study the combustion characteristics of solid sustained-release energetic materials was reasonable.The theoretical burning rate formula also had high accuracy.Therefore,the model could provide scientific and academic guidance for the theoretical research,system design and practical application of solid sustained-release energetic materials in related fields.

Synthesis and Characterization of Ordered Mesoporous Aluminosilicate Molecular Sieves with High Stability in High-Temperature Steam

The ordered mesoporous aluminosilicate molecular sieve （MASMS-1） stable in the high-temperature steam has been successfully synthesized from the assembly of diluted ZSM-5-type precursor with mesoporous MCM-41. The material was characterized by XRD, N2 adsorption-desorption, FE-SEM, TEM, FT-IR spectroscopy and 27A1 MAS NMR techniques. This mesoporous material shows high stability in the high-temperature steam [H2O （φ=20%） in N2 at 800 ℃ for 4 h], which might be ascribed to the synergistic effect of both thick walls containing zeolite-like five-membered ring subunits and highly condensed surface silanol groups.

蒸汽压力对蒸汽喷射泵凝结水率的影响研究及应用

蒸汽喷射泵是一种以蒸汽为动力源的机械设备。蒸汽作为一种能源,普遍应用在化工、冶金等诸多行业中。文章研究了蒸汽喷射泵的基本原理,阐述蒸汽喷射泵在车间的运行现状,探究泵在运行过程中蒸汽压力对凝结水率的影响规律,在满足企业生产的凝结水率要求下,通过实验优选出合理的蒸汽压力范围,压力值在0.692~0.775 MPa(表压,下同)之间,凝结水率不高于10%,达到了企业生产要求,降低了后期对凝结水的处理成本。

基于引射流技术与压缩闪蒸汽的节能装置

生产中的蒸汽冷凝水经疏水装置从生产加热装备排入凝水系统时闪蒸出大量二次蒸汽,二次蒸汽依旧含有很高的热焓值,直接排放不仅会造成严重的污染和危害,还造成了大量的浪费。目前节能工艺设计不尽完善,通过分析其节能利用的性价比,经过计算设计了一套基于引射流技术与压缩闪蒸汽的节能装置,搭建了符合装置特点的控制系统,使这部分热能得到了有效使用,达到了降低危害、节能环保的要求。

小型堆非能动安全壳内喷射实验分析

本研究搭建了一个由蒸汽供应装置、安全壳、外部喷淋系统等组成的实验装置,模拟小型堆非能动安全壳在发生破口故障后,蒸汽喷射流量、破口直径、破口高度、外部喷淋流量4个因素对壳体内热分层与壳壁传热的影响。文章围绕4个因素分别设计了实验,结果表明:在蒸汽喷射流量较大、破口直径较小、破口高度较高、外部喷淋流量较大的情况下,安全壳壳体热流密度较大,热分层现象明显,安全壳呈现出上部温度偏高、下部温度偏低的情况。