新独立B型液化天然气船模拟舱蒸发率测试

为了研究新独立B型液化天然气船绝热结构的低温性能,以体积47 m3,绝热层厚度400mm的新独立B型液化天然气船模拟舱围护系统为研究对象,采用气体质量流量计法对模拟舱进行蒸发率测试,并通过绝热结构内的温度传感器得到低温下模拟舱的温度分布。随后通过建立修正公式将模拟舱的液氮蒸发率转换为实船工况下的LNG蒸发率。最终通过误差分析与计算表明,新独立B型天然气船模拟舱围护系统的绝热性能达到实船日均蒸发率0.1%/d的设计要求。     

铝合金液化天然气罐式集装箱的设计

液化天然气罐式集装箱是运输液化天然气的重要设备。文章介绍了铝合金液化天然气罐式集装箱的设计参数,针对罐体内筒主体材料采用铝合金复合材料及焊接结构进行探讨,并分析了内筒采用5083铝合金的效益优势。     

铝合金液化天然气罐式集装箱的设计

液化天然气罐式集装箱是运输液化天然气的重要设备。文章介绍了铝合金液化天然气罐式集装箱的设计参数，针对罐体内筒主体材料采用铝合金复合材料及焊接结构进行探讨，并分析了内筒采用5083铝舍金的效益优势。     

LNG物理NFDA1及其回收利用

液化天然气储存在-160 ℃左右的低温下,这种与环境状态的巨大差别,使得LNG在蒸发时可释放大量的冷能.为了回收利用LNG所具有的冷能,采用Peng-Robinson气液平衡状态方程,使用HYSYS软件对LNG的蒸发过程进行了模拟计算.研究了LNG冷能和物理NFDA2在不同蒸发压力下的释放情况,并考虑了甲烷的摩尔分数对此的影响,结果表明蒸发压力对LNG冷能的回收利用方式有决定性影响.依据研究结果,提出了采用Rankine循环和Brayton循环的方法来实现LNG物理NFDA2回收利用.     

40英尺液化天然气罐式集装箱的研制

简介了40英尺LNG罐式集装箱的技术参数、流程和结构;对真空多层绝热罐式集装箱进行了漏热量计算;阐述了内、外容器支撑和框架结构的设计,在制造过程中为保证真空度和清洁度而采取的措施以及型式试验情况;分析了40英尺LNG罐式集装箱的优点。     

爆炸作用下拱形结构反射系数计算方法研究

为了计算爆炸荷载作用下地下拱形结构上的动荷载,引入了Costantino 荷载模型考虑拱结构拱曲率对介质-结构相互作用机理的影响,在单自由度体系位移模式的基础上利用虚功原理,求解爆炸荷载作用下拱形结构的反射系数,即作用到结构上的均布动荷载峰值与结构板块处自由场应力的均布峰值之比.讨论了拱曲率、结构刚度、介质参数对反射系数的影响.在此基础上,与规范中平顶结构的综合反射系数计算方法进行了比较,引入修正系数对公式进行修正,改进后的反射系数计算方法对于不同的结构形式具有更广泛的适用性.     

液化天然气铁路罐车设计及试验

目的 本文通过对液化天然气铁路罐车的设计及试验验证进行研究，为LNG铁路罐车的应用提供参考。方法 介绍液化天然气铁路罐车的技术参数确定和结构组成，采用CAD、FEM技术对罐车的结构进行设计研究及仿真分析，通过铁路静强度和冲击试验、低温性能测试等手段验证罐车的力学性能和真空绝热指标。结果 液化天然气铁路罐车轴质量为23 t、载质量不超过41 t，在最高运行速度120 km/h时能够安全运行，每天的静态蒸发率(液氮)为0.08%，维持时间(液氮)达到92 d。结论 液化天然气铁路罐车的技术参数及性能指标达到了设计文件和相关标准的要求。     

车载LNG储罐蒸发率的理论与试验

为研究车载LNG低温绝热气瓶内液体的蒸发规律,以200 L高真空多层绝热气瓶为例,采用液氮(LN2)为工质,进行了一系列LN2日蒸发率试验。列出根据实验系统结构参数得到的相关传热学计算结果,包括试验系统分别贮存LN2和LNG各项漏热及理论蒸发率。对理论计算与实验结果进行比较,通过理论计算结果与LN2蒸发率实验结果对LNG试验蒸发率作了预测。根据大气压力下进行的各种充满率的LN2蒸发率实验,拟合出了系统蒸发率与充满率的关系曲线,并分析了系统中环境温度和压力对蒸发率的影响规律。     

液化天然气生产储运中的蒸气回收

为提高天然气能量密度,通常将天然气液化后在其常压沸点约 112 K下存储。由于环保的要求,对液化天然气 (LNG)的需求量越来越大。对 LNG的生产及接收终端的储存及运输工程中的蒸发气 (BOG)的回收和利用是提高工厂经济效益的重要一环。讨论了压缩和再液化 BOG的回收方法。认为运用计算机模拟这一工程上新的工具,对提高 LNG工厂的安全性和经济效益,同时降低投资成本是很有帮助的。简介了这方面的一些事例,并提出了一些建议。     

液化天然气加气机计量检测技术现状分析

本文主要论述了我国液化天然气(LNG)汽车和加气站发展现状及趋势、LNG加气机的技术标准、计量性能、试验介质及国内外LNG流量计量标准装置。分析了试验介质对LNG加气机计量性能的影响以及国际先进的LNG流量标准装置的主要技术指标及研究现状,以期为我国LNG加气机计量技术研究提供参考。     

泄放阀着火时LNG储罐外容器热-结构耦合分析

针对LNG储罐在泄放阀着火的工况,对受到外界高温火焰辐射的LNG外容器的传热和结构进行了耦合分析研究.建立了16万方LNG大型储罐的实体有限元模型,根据规范和相关文献中的推荐方法,获得了泄放阀火焰高温辐射时罐顶外表面的等效辐射温度,根据正常工作时的稳态传热工况进行储罐外容器内表面等效对流传热系数的计算,得到了正常工作时...     

B型LNG模拟舱内低温流体两相流动与相变传热数值研究

本文以内容积为40 m3，绝热层厚度为400 mm的新型独立B型液化天然气船模拟舱为研究对象，对模拟舱内低温流体的两相流动及相变传热问题进行了非稳态三维CFD模拟。采用流体体积函数（VOF）模型追踪气液相界面，利用Lee模型作为相变模型，在相变模型中考虑了静压的影响，对模拟舱的温度分布及静态BOG生成速率进行了计算。研究了在不同液位以及绝热层存在破损的情况下模拟舱的温度分布及静态BOG生成速率的变化，同时研究了当模拟舱密闭时的增压特性。对比模拟结果与实验结果，偏差在10%以内，模型对模拟舱内的低温液体的蒸发过程模拟较好，可为新型独立B型液化天然气实船的设计和改进提供参考。     

LNG储罐主容器泄漏时外罐壁的传热特性

以一种LNG储罐为研究对象,利用有限单元法(FEM)分析了在主容器泄漏时的混凝土外罐壁的传热特性,研究了泄漏发生时外罐壁温度随着时间的变化过程,泄漏发展后的外罐壁的温度分布和热流密度,以及热保护边角(TCP)对于外罐壁传热的影响,指出了外罐壁热传导达到稳定后的传热特性.     

Coupling dynamic blow down and pool evaporation model for LNG

Treating the dynamic effects of accidental discharges of liquefied natural gas (LNG) is important for realistic predictions of pool radius. Two phenomena have important influence on pool spread dynamics, time-varying discharge (blow down) and pool ignition. Time-varying discharge occurs because a punctured LNG tanker or storage tank drains with a decreasing liquid head and decreasing head-space pressure. Pool ignition increases the evaporation rate of a pool and consequently decreases the ultimate pool area. This paper describes an approach to treat these phenomena in a dynamic pool evaporation model.

The pool evaporation model developed here has two separate regimes. Early in the spill, momentum forces dominate and the pool spreads independently of pool evaporation rate and the corresponding heat transfer rate. After the average pool depth drops below a minimum value, momentum forces are largely dissipated and the thin edges of the pool completely evaporate, so pool area is established by the heat transfer rate. The maximum extent of a burning pool is predicted to be significantly less than that of an unignited pool because the duration of the first regime is reduced by higher heat transfer rates. The maximum extent of an LNG pool is predicted to be larger upon accounting for blow down compared with using a constant average discharge rate. However, the maximum pool extent occurs only momentarily before retreating.     

Design of a hybrid glass composite anchor for LNG cargo containment systems

Large cryogenic container for liquefied natural gas (LNG) should be joined to the inner hull of a ship. The minimum heat inflow, due to the large temperature difference between the LNG cargo container and inner hull, can induce considerable heat flux through the joined area.In this work, a hybrid composite anchor composed of two stainless steel caps and a glass fiber composite body was developed and optimized for strength, thermal stress and heat loss of the anchor. The stainless steel caps were adhesively bonded to the top and bottom areas of the glass composite body. The top stainless cap was then welded to the two stainless steel membranes, and the flange of the bottom stainless steel cap was bolt-fastened to the inner hull of a ship.The static adhesive strength and impact characteristics between the stainless steel caps and glass composite body of the hybrid glass composite anchor at the cryogenic temperature were investigated with respect to adhesive thickness. Finally, the optimal design for the hybrid glass composite anchor for the cryogenic containment systems of a LNG ship was suggested.     

LNG燃料汽车储罐自增压及供气特性

研究了车用液化天然气储罐自增压过程以及稳压供气特性,研究表明液化天然气储罐在自增压过程中储罐压力以及气腔气体温度稳步上升,而液腔主体液体温度基本保持不变。在稳压供气过程中,主要分析影响储罐压力波动的因素,因为压力波动频率太快不利于压力调节系统的准确控制和使用寿命。分析结果表明工作压力范围太窄以及汽车行驶震动越剧烈都将引起储罐压力波动频率的加快。     

大型LNG储罐罐底保冷层结构优化研究

针对大型LNG储罐罐底漏热量大及基础保冷性能差等问题,对储罐底部保冷结构进行了优化,并对不同储罐底部基础的温度场分布和漏热量进行了数值模拟和现场对比分析。结果表明:储罐冷损失与泡沫玻璃砖厚度呈双曲线函数关系,在内外壁温差为185 K时泡沫玻璃砖保冷层厚度设置为600 mm保冷效果显著,再增加厚度时保冷损失减小缓慢;储罐基础采用夯土基础时保冷性能优于柱桩基础,而夯土基础需在罐底设置加热系统,因此工程上大型LNG储罐需根据实际情况进行选择。     

Numerical investigation of supercritical LNG convective heat transfer in a horizontal serpentine tube

The submerged combustion vaporizer (SCV) is indispensable general equipment for liquefied natural gas (LNG) receiving terminals. In this paper, numerical simulation was conducted to get insight into the flow and heat transfer characteristics of supercritical LNG on the tube-side of SCV. The SST model with enhanced wall treatment method was utilized to handle the coupled wall-to-LNG heat transfer. The thermal–physical properties of LNG under supercritical pressure were used for this study. After the validation of model and method, the effects of mass flux, outer wall temperature and inlet pressure on the heat transfer behaviors were discussed in detail. Then the non-uniformity heat transfer mechanism of supercritical LNG and effect of natural convection due to buoyancy change in the tube was discussed based on the numerical results. Moreover, different flow and heat transfer characteristics inside the bend tube sections were also analyzed. The obtained numerical results showed that the local surface heat transfer coefficient attained its peak value when the bulk LNG temperature approached the so-called pseudo-critical temperature. Higher mass flux could eliminate the heat transfer deteriorations due to the increase of turbulent diffusion. An increase of outer wall temperature had a significant influence on diminishing heat transfer ability of LNG. The maximum surface heat transfer coefficient strongly depended on inlet pressure. Bend tube sections could enhance the heat transfer due to secondary flow phenomenon. Furthermore, based on the current simulation results, a new dimensionless, semi-theoretical empirical correlation was developed for supercritical LNG convective heat transfer in a horizontal serpentine tube. The paper provided the mechanism of heat transfer for the design of high-efficiency SCV.