FLNG船舶能量管理系统设计与性能优化

浮式液化天然气生产储卸装置(floating liquefied natural gas system,FLNG)特种液货船作为开发海上天然气田的新式装置,极大的方便了对处于深海的气田的开发利用,该文以“Prelude”号FLNG作为母船,提出一种新型FLNG低温能量管理系统。该系统主要利用液态空气作为媒介储存和释放能量,通过液态空气冷能与混合制冷循环相结合实现天然气液化过程,在提高LNG生产性能的同时集成了CO_(2)液化循环和电力的生产,通过CO_(2)液化和剩余冷能发电提高系统的输出性能,实现了FLNG船舶冷能的多级利用,也为FLNG船舶冷能利用提供新方法,新途径。所提系统相较于基准模型具有更好的性能,在7.04年可实现成本回收。最后采用多目标性能优化,进一步提高系统㶲效率达60.67%,同时降低约2.3%的成本。该FLNG低温能量管理系统有高效、低耗、稳收益、低碳化等特点,可更好优化海上LNG供应链,促进航运业“双碳”发展。

适用于FLNG装置的紧凑高效换热器的可靠性分析

[目的]目前,紧凑高效换热器已成为海上浮式液化天然气(FLNG)换热装置的最佳选择。为了优化换热器的结构参数并提升工作性能,有必要针对换热器开展静强度分析和可靠性分析。[方法]首先,采用ANSYS Workbench静力学分析模块对换热器芯体进行静强度分析,建立可以代表大部分流道应力水平的简化模型;然后,采用ANSYS Workbench六西格玛分析模块对换热器芯体进行可靠性分析,并选择换热器芯体的冷侧流道壁厚、冷侧流道压力、热侧流道压力和弹性模量等参数作为随机输入变量,进而研究各个随机变量对其可靠性的影响。[结果]可靠性分析结果表明,冷侧流道压力对结构强度的影响最大,且换热器可靠性达99.9%以上,其发生失效的可能性很小。[结论]研究成果可为基于静强度的换热器可靠性分析提供参考。

FLNG与LNG运输船稳性规范要求的对比分析

以某型FLNG和LNG运输船为对象,运用NAPA软件,分别对浮式LNG生产储缷平台(FLNG)和LNG运输船需要满足的稳性衡准(包括完整稳性和破舱稳性)进行计算;对比分析二者的计算结果,提出了FLNG和LNG运输船稳性规范规则的重点和难点。

多点系泊的FLNG艉输作业可行性

以一艘多点系泊的浮式液化天然气船(Floating Liquefied Natural Gas Carrier,FLNG)为研究对象,结合西非海区特定的环境条件,采用耦合时域方法模拟其艉输作业时系统总体的动态响应,论证采用艉输方式的作业可行性,并对其外输临时系泊系统进行优化设计。研究表明:艉输作业时FLNG的多点系泊缆绳张力、外输缆绳张力、FLNG与LNG运输船之间的间距、立管顶部水平偏移等结果均可满足设计基础要求。随着外输海况的提升以及环境载荷入射角度的增大,外输系泊缆张力与生产立管顶部最大偏移量快速增大。外输系泊缆载荷受缆绳材料的影响较大,对于外输系泊缆绳布置而言,采用单根布置优于2根布置。

Time-Domain Analysis of the Relative Motions Between Side-by-Side FLNG and LNGC Under Oblique Waves

Strong hydrodynamic interactions during the side-by-side offloading operation between floating liquefied natural gas(FLNG) and liquefied natural gas carrier(LNGC) can induce high risks of collision. The weather vane effect of a single-point mooring system normally results in the satisfactory hydrodynamic performance of the side-by-side configuration in head seas. Nevertheless, the changes in wave directions in real sea conditions can significantly influence the relative motions. This article studies the relative motions of the side-by-side system by using the theoretical analysis method and the numerical calculation method. Based on the three-dimensional potential theory modified by artificial damping-lid method, the frequency-domain hydrodynamic coefficients can be improved to calculate the retardation functions for the multi-body problem. An in-house code is then developed to perform the time-domain simulation of two vessels, through which the relative motions are subsequently obtained. A range of oblique waves are chosen for the extensive calculation of relative motions between the two vessels, which are further analyzed in terms of the phase shift of motion responses induced by specific resonant wave patterns. Investigation results show that wave directions have a significant influence on the relative sway, roll, and yaw motions. Under the circumstance that the absolute phase shift between the roll motions of two vessels approaches 180°, stronger relative motions are induced when LNGC is on the weather side.Moreover, the gap water resonances at high frequencies tend to cause the dangerous opposed oscillation of two vessels in the sway and yaw modes, whereas FLNG reduces the gap water resonances and relative motions when located on the weather side.

浮式液化天然气液化技术的选择及国产化面临的问题

浮式液化天然气(FLNG)已由研究走向实施及建造阶段。FLNG首先要确定选择何种液化技术,其选择受到许多因素的影响,最终确定的技术必然是一个综合比选后的结果。国产化液化技术及装备在应用于FLNG之前,需加快开展"运动对液化技术及设备影响的试验及研究"。

超重力条件下旋转填料层中流体流动特性研究

针对新型超重力天然气脱碳技术特点,以实际工程脱碳工艺数据为基础,构建了超重力机旋转填料层数值模型,研究了两相流体在超重力机旋转填料层中的流动特性,结果表明:在超重力条件下,改变流速、转速及进入方向对流体在旋转填料层中的运动几乎没有影响,旋转填料层中流体分布特性受海上晃荡工况影响可以忽略;流体分布的均匀性与旋转填料层内速度梯度及压降呈负相关的关系,速度梯度及压降越小,流体分布越均匀;随着时间的增加,流体在旋转填料层中逐渐均匀分布,此时的脱碳效果最好;提高旋转敏感度有利于流体在旋转填料层内的均匀分布。本文研究结果对超重力脱碳技术在海上工况条件下的应用具有指导意义。

浮式液化天然气系统液体装载船体的耦合响应

开发了一套分析浮式液化天然气(FLNG)系统中船体运动与液舱晃荡耦合响应的数值模拟程序.该程序基于频域势流理论获得船体的频域水动力系数,并根据脉冲响应理论(IRF)实现船体运动的时域计算;基于势流理论采用边界元法进行液舱晃荡的时域预报;通过迭代计算实现运动与晃荡响应的耦合预报.开展模型试验研究固体、液体装载船体在波浪中的运动响应.结合数值计算结果和试验结果研究晃荡和船体运动的耦合机理,讨论了不同液舱布置形式下的耦合响应变化.结果表明:液舱晃荡会显著改变船体的横荡、横摇运动响应,对垂荡运动影响较小;改变液舱宽度可以减小横摇运动引起的晃荡幅值,而横荡激励的晃荡响应主要与晃荡固有频率有关;液舱垂向位置变化仅改变与横摇模态的耦合响应,与横荡运动的耦合作用不变.

PRICO~?天然气液化技术在海上浮式装置上的应用

较之于岸上(陆地)天然气液化装置,海上浮式天然气液化(FLNG)装置具有投资低、建设周期短、便于迁移及可重复使用等优点,但也面临着易受海上工况及船体晃荡影响等诸多挑战。为此,借助于PRICO~?单循环混合冷剂(SMR)天然气液化工艺技术所具有的较大的灵活性,以及流程简单、易于操作、可满足不同客户的需求、成本更低等优势,运用模块化设计进行了FLNG装置的设备布置,针对海上操作环境对部分关键设备进行了改进,研发出了世界上第一个基于该工艺的浮式天然气液化装置——Exmar FLNG,并进行了现场调试及性能考核。应用效果表明:(1)PRICO~?天然气液化技术能够使FLNG从概念设计实现工程化,并获得更多的发展空间;(2)Exmar FLNG装置集合了天然气处理、天然气液化、LNG储存和装卸功能,工艺流程简短、装置设备数量少、操作简单,具有较短的开停车时间,能较好适应海上恶劣天气及原料气组成变化大的工况,其设计与建造完全符合船级社的相关规范和规定。结论认为,该技术为海洋石油伴生气处理、边际气田和深海气田开发利用提供了一种新的既安全又经济的解决方案。

深远海天然气田开发的储存和运输新技术分析

我国南海拥有1000多亿吨油当量的油气资源,其中天然气资源占83%,在天然气资源中70%来自距离我国大陆500 km之外的深水区;如何经济有效地开发南海深远海的天然气资源已逐渐成为关注的焦点之一。采用常规的管线输送开发模式,可能会带来技术和经济的不可行;在海上设施上,将天然气高度压缩、液化或固化等创新性技术,被认为是开发南海深远海天然气资源的可行方案。目前,浮式液化天然气(FloatingLiquid Natural Gas,简称FLNG)、浮式压缩天然气(Floating Compressed Natural Gas,简称FCNG)和浮式天然气水合物(Floating Natural Gas Hydrate,简称FNGH),被认为是深远海气田开发较有潜力和较有推广应用前景的海上天然气储存和运输技术。论文从海上FLNG、FCNG和FNGH三种技术的现状出发,分析了各自的技术特点、需要解决的核心关键技术、面临的技术挑战以及推广应用前景等,为我国南海深远海气田和海外气田的经济高效开发提供借鉴;分析结果认为,目前世界上FLNG相对比较成熟,已经有2艘FLNG投产运行,但还需要加强适合于我国南海气田开发,且具有知识产权的FLNG独立型LNG货物围护系统的工程应用开发,加强低温绝缘材料、建造施工技术以及系统集成技术攻关。此外,还有关键设备国产化问题;目前世界上虽然有1艘CNG(压缩天然气)运输船投入使用,但还没有投入运营的FCNG项目;海上FNGH储存和运输技术研究大多还处于试验阶段,技术尚未完全成熟,距离FNGH走向商业应用还有很多关键技术要攻克。一般情况下,FLNG适合于距离远和储量大的气田开发,FCNG比较适用于距离短和输量小的气田开发,FNGH比较适用于输量小,距离相对长的气田开发。

浮式液化天然气装置BOG处理方式研究

蒸发气(Boil Off Gas,缩写为BOG)的处理回收方式不仅会影响浮式液化天然气(FLNG)装置上的设备配置及装置投资,同时会直接影响到整个装置生产运营的安全性、经济性和环境保护。为了能够选择经济合理的BOG处理回收方式,以惠生海洋工程正在执行的3.0 MTPA FLNG标准化项目为例,介绍了浮式液化天然气装置上两种主要的BOG处理回收方式即作为燃气轮机的燃料气和返回制冷剂换热器进行再液化。通过Aspen HYSYS模拟软件,分析了在不同工况下BOG的产生量及不同的处理回收方式对装置能耗的影响。并建议了针对不同的原料气组分以及装置内主要转动设备的驱动方式,选择针对性的BOG处理方式,避免BOG直接燃烧造成环境污染和经济损失,降低装置投资,为浮式液化天然气装置的国产化以及BOG处理系统设计提供参考。

浮式液化天然气装置LNG预处理工艺大型分离设备研究进展

分离设备是海上浮式生产系统上天然气预处理的重要设备,在海上油气田特殊环境下,分离设备在气液不均匀分布条件下会严重影响分离效率,使预处理工艺效率降低。通过调研有关晃荡条件下分离设备气液流动和传质性能的研究现状,分别对气液分离器、填料塔等典型设备和常用的净化工艺进行讨论分析,为提高浮式设备的分离效率提供新的研究思路。结合工程实际,指出晃荡条件下分离设备运行性能的现有问题和今后的研究重点,为浮式环境中分离器的选型和优化设计提供建议。

EXPERIMENTAL INVESTIGATION OF EFFECTS OF INNER-TANK SLO-SHING ON HYDRODYNAMICS OF AN FLNG SYSTEM

The present research focuses on experimentally clarifying the effect of inner-tank sloshing on the hydrodynamics of an Floating Liquefied Natural Gas（FLNG）system.Through the comparisons of the results obtained from the model tests carried out with the vessel model ballasted with liquid and solid cargo separately,the effects of the inner-tank sloshing on the hydrodynamics of an FLNG system are highlighted and presented.Statistical languages of the maximum,minimum,mean values and the standard deviations and power density spectra calculated with the help of the algorithm of Fast Fourier Transformation（FFT）are provided.It is concluded that the effects of the inner-tank sloshing on the responses of the FLNG system are sensitive to wave excitation frequencies,and that the effects of the inner-tank sloshing play an important role,particularly in the roll motion of the FLNG hull.The outcome of the proposed technique would offer constructive feedback,which can lead to more practical applications and can serve as a reference for the verification of the potential numerical simulations by other researchers.

HYDRODYNAMIC INTERACTION BETWEEN FLNG VESSEL AND LNG CARRIER IN SIDE BY SIDE CONFIGURATION

The Floating Liquefied Natural Gas （FLNG） is a new type of floating platform for the exploitation of stranded offshore oil/gas fields. The side by side configuration for the FLNG vessel and the LNG carrier arranged in parallel is one of the possible choices for the LNG offloading. During the offloading operations, the multiple floating bodies would have very complex responses due to their hydrodynamic interactions. In this study, numerical simulations of multiple floating bodies in close proximity in the side by side offloading configuration are carried out with the time domain coupled analysis code SIMO. Hydrodynamic interactions between the floating bodies and the mechanical coupling effects between the floating bodies and their connection systems are included in the coupled analysis model. To clarify the hydrodynamic effects of the two vessels, numerical simulations under the same environmental condition are also conducted without considering the hydrodynamic interactions, for comparison. It is shown that the hydrodynamic interactions play an important role in the low frequency motion responses of the two vessels, but have little effect on the wave frequency motion responses. In addition, the comparison results also show that the hydrodynamic interactions can affect the loads on the connection systems.

海上晃动对FLNG再沸器液面波动的影响

在浮式液化天然气船(FLNG)的天然气处理工艺中,含有酸性气体的富胺液进入再生塔内解吸,再沸器位于再生塔塔底,为富胺液的解吸过程提供热量。使用ANSYS内嵌模块Geometry建立再沸器的三维物理模型,再沸器主要由外壳、加热装置和溢流堰组成,只研究晃动对液面波动的影响,所以未设置加热介质和胺液的进出口。将再沸器设置为一个封闭的装置,内部仅有水和水蒸气2种介质。使用ANSYS内嵌模块Mesh进行网格划分,网格类型选择非结构网格,对再沸器模型进行网格独立性检验,网格数量取3891653,网格最大尺寸为3mm。为实现模拟过程的晃动,编写晃动角速度、晃动线速度的UDF函数,导入到Fluent软件中。分别对横摇、纵摇、艏摇、横荡、纵荡、垂荡6种单自由度晃动和横摇8°+纵摇8°、横摇8°+艏摇8°、横摇8°+横荡150mm、横摇8°+纵荡150mm、横摇8°+垂荡150mm这5种两自由度耦合晃动工况下,初始时刻与晃动至0.25倍晃动周期时的再沸器液面波动情况进行模拟。得出结论:在单自由度晃动工况下,横摇对再沸器的性能影响最大,纵摇、艏摇、垂荡、横荡、纵荡对再沸器的性能影响很小。在耦合晃动工况中,横摇对液面波动起主导作用,对再沸器的性能影响较大;横摇8°+横荡150mm、横摇8°+纵荡150mm、横摇8°+垂荡150mm这3种耦合工况下的液面波动与横摇工况相比更大。在FLNG再沸器的设计和安装过程中,应充分考虑横摇晃动工况以及以横摇晃动为主的耦合晃动工况。

Numerical Investigation on the Hydrodynamic Diference Between Internal and External Turret-Moored FLNG

Motion responses of the floating liquefied natural gas(FLNG)hull and the mooring loads in a 100-year return environmental condition are predicted with the help of the well known coupled dynamic analysis code DeepC.A ship-shaped turret-moored FLNG moored by 4×3 chain-polyester-chain lines in 1.5 km depth of water is studied.Two types of turrets such as internal and external turrets,resulting from diferent locations of the turrets,are adopted respectively in the numerical simulations.Motion responses of the FLNG hull and forces of the mooring lines obtained from the internal turret case and external turret case are compared with each other.Significant diferences are obtained.Statistic analysis is also used to analyze the comparison results,and efects of the turret location on the FLNG hydrodynamic characteristics are summed up.The conclusion regarding the hydrodynamic diferences between internal and external turret-moored FLNG systems would provide help for design of the FLNG system.

Numerical Study of Heat Transfer Characteristic for Subcooled Falling Film outside the Shaped Tubes under Rolling Motion

The heat transfer performance of spiral wound heat exchanger used in the floating liquefied natural gas(FLNG)may be significantly affected by the sloshing conditions.In this paper,a three-dimensional numerical model combined with the dynamic mesh technology is conducted to study subcooled falling film heat transfer under static and sloshing conditions.The three-dimensional velocity distribution of the liquid film on the shell side is observed.The effects of cross-section shape of heat exchange tubes,Reynolds numbers and sloshing parameters on heat transfer characteristics are analyzed.The results indicate that the heat transfer performance of the egg-shaped tube is superior to that of the elliptical and circular tube under both static and sloshing conditions due to significant heat transfer improvement in the lower half of the tube.The heat transfer coefficients of three different kinds of tubes decrease under sloshing conditions.When the rolling amplitude is 6°,the average heat transfer coefficients of the circular tube,elliptical tube and egg-shaped tube are reduced by 2.1%,3.7%and 4.9%respectively.Under the current sloshing parameters,increasing the rolling amplitude,the heat transfer coefficients of three different tubes are slightly increased,while the sloshing period has little effect on heat transfer.The egg-shaped tube and elliptical tube are greatly affected by sloshing motion at the low Reynolds number,while the effect is relatively small at the high Reynolds number.

Numerical simulation and analysis of periodically oscillating pressure characteristics of inviscid flow in a rolling pipe

Floating liquefied natural gas （LNG） plants are gaining increasing attention in offshc,re energy exploitation. The effects of the periodically osciUatory motion on the fluid flow in all processes on the oil＂shore plant are very complicated and require detailed thermodynamic and hydrodynamic analyses. In this paper, numerical simula- tions are conducted by computational fluid dynamics （CFD） code combined with user defined function （UDF） in order to understand the periodically oscillating pressure characteristics of inviscid flow in the rolling pipe. The computational model of the circular pipe flow is established with the excitated rolling motion, at the excitated frequencies of 1-4rad/s, and the excitated amplitudes of 3^-15~, respectively. The influences of flow velocities and excitated conditions on pressure characteristics, including mean pressure, frequency and amplitude are systematically investigalted. It is found that the pressure fluctuation of the inviscid flow remains almost constant at different flow velocities. The amplitude of the pressure fluctuation increases with the increasing of the excitated amplitude, and decreases with the increasing of the excitated frequency. It is also found that the period of the pressure fluctuation varies with the excitated frequency. Furthermore, theoretical analyses of the flow in the rolling circular pipe are conducted and the results are found in qualitative agreement with the numerical simulations.