大型LNG液化装置设备对比和国产化解决方案的探讨

PFHE和SWHE的基本介绍和对比分析。     

LNG绕管式换热器壳侧单相传热模型的优化

天然气液化工艺中绕管式换热器的壳侧热力计算是当前亟待解决的问题之一,针对低温工况下壳侧传热模型的研究尚不多见,需要选取出适用的传热模型准确计算传热系数,为天然气液化工艺中绕管式换热器的设计选型和热力校核提供依据。本文比较分析了现有壳侧单相传热模型的优缺点,结合绕管式换热器壳侧低温实验数据,筛选出了适用于天然气液化预冷段的壳侧传热模型,并进行了优化。结果表明:对于天然气液化预冷段的壳侧传热系数计算,Abadzic传热模型计算精度最高、偏差范围最小、适用性最佳;Abadzic传热模型粘度修正后计算精度提高约50%,天然气液化预冷段的粘度修正系数可估算为1.05。     

绕管式换热器管道设计与应用浅析

在整个工业生产行业中,为了更好的实现物料之间热量传递过程的一种设备,被称之为换热器。本文主要针对绕管式换热器管道设计与应用进行分析,并尝试性提出在工程实际运用中应该注意的相关问题。     

防冻堵的船用绕管式LNG气化器设计

绕管式气化器具有高效紧凑、机械强度高的优点,可作为船载LNG气化设备使用,但需要合理设计气化器结构来避免水介质发生冻堵。本文设计了一种水加热型绕管式LNG气化器,在满足气化工艺要求的同时可防止气化器出现冻堵。首先提出了基于防冻堵的气化器结构设计思路:在保证管侧水温高于冰点和管侧出口水温分布均匀的前提下,设计绕管式气化器的关键结构参数;然后通过三维分布参数模型对气化器换热、压降性能以及防冻堵性能进行校核,并提出结构参数优化调整的方法。采用本文提出的设计方法,对一台已知设计参数的LNG气化器进行算例分析,优化调整后的绕管式换热器热负荷和压降能够满足设计要求,且管侧壁面温度最低温度为7. 32℃,管侧出口平均温度为31. 42℃,达到防冻堵的效果。     

螺旋绕管式换热器的特点及其制造工艺研究

相对于传统换热器,缠绕换热器独特的换热结构,大幅度提升了换热效率,在节约资源、提升生产效率、降低生产成本等方向发挥着巨大优势。为企业的发展带来经济效益。因此,该文主要分析了螺旋绕管式换热器的结构及特点,并在此基础上对螺旋绕管式换热器的制造工艺进行了研究,从而为今后制造换热器提供一种新的想法和途径。     

绕管式换热器换热面积的一种简捷计算方法

通过对绕管式换热器的换热分析,将某大型缠绕管式低温换热器和船用LNG系统换热器进行简化分析计算,并分别与其设计值比较,两个结果均表明此种换热器简捷计算方法能简单明了算出换热面积,并与传统计算设计值精度相当,满足设计计算要求,给换热器设计计算提供了参考。     

小型MRC天然气液化装置中板翅式换热器动态特性仿真研究

针对采用混合制冷剂液化流程(MRC)的小型天然气液化装置(LNG)中的板翅式换热器建立了动态特性仿真数学模型,基于气液两相流理论及气液相平衡理论,对多股流、多组分、有相变的板翅式换热器进行了动态仿真研究,并对该MRC-LNG装置中某换热器在非稳态工况下进行了仿真分析.结果表明:在小型MRC液化天然气装置设计和调试过程中,该模型对提高换热器设计效率、降低运行成本有指导意义.     

天然气液化技术及其应用

我国经济的快速发展,对天然气的需求量逐渐增大。尽管目前天然气产量连年增长,但仍不能满足经济发展的需求。天然气产地远离工业或人口集中地区,需要建设长距离的输送管线,这在一定程度上制约了天然气的利用。文章探讨了天然气液化过程中主要技术、液化天然气利用及安全问题,对于液化天然气的实际应用具有一定的参考价值。     

液化天然气的贮存及相关技术

液化天然气(LNG)的接收贮存是天然气应用的关键技术,LNG接收贮存中心同时又是向天然气用户供气的供应部门。从LNG的贮存、汽化、供应到设备的维护,由于LNG的特性,有很多具体的实用技术需要进行具体的研究。本文就LNG的贮存和汽化及一些相关技术作一简要的介绍。图5参1。     

150万m~3/d液化天然气工厂技术分析

2004年我国建成投运了目前国内规模最大的基本负荷型液化天然气(LNG)工厂,文章对该工厂的天然气预处理、天然气液化、液化天然气储存和液化天然气配送系统工艺流程进行了技术分析。     

Effect of multi-stream heat exchanger on performance of natural gas liquefaction with mixed refrigerant

A thermodynamic study is carried out to investigate the effect of multi-stream heat exchanger on the performance of natural gas (NG) liquefaction with mixed refrigerant (MR). A cold stream (low-pressure MR) is in thermal contact with opposite flow of two hot streams (high-pressure MR and NG feed) at the same time. In typical process simulation with commercial software (such as Aspen HYSYS®), the liquefaction performance is estimated with a method of minimum temperature approach, simply assuming that two hot streams have the same temperature. In this study, local energy balance equations are rigorously solved with temperature-dependent properties of MR and NG feed, and are linked to the thermodynamic cycle analysis. The figure of merit (FOM) is quantitatively examined in terms of UA (the product of overall heat transfer coefficient and heat exchange area) between respective streams. In a single-stage MR process, it is concluded that the temperature profile from HYSYS is difficult to realize in practice, and the FOM value from HYSYS is an over-estimate, but can be closely achieved with a proper heat-exchanger design. It is also demonstrated that there exists a unique optimal ratio in three UA’s, and no direct heat exchanger between hot streams is recommended.     

小型氮膨胀天然气液化流程的设计及优化分析

根据气源条件,设计了3套氮膨胀天然气液化流程,选择PR(Peng-Robinson)方程进行混合物的相平衡计算,采用大型数值模拟软件Aspen Plus进行了数值模拟计算;分析比较了不同液化流程的关键热力学参数,并进行了关键设备的可行性分析.结果表明:丙烷预冷氮膨胀液化天然气流程的比功耗比无预冷的单级氮膨胀天然气液化流程的低,比无预冷的两级氮膨胀天然气液化流程的稍高,两级氮膨胀天然气液化流程较难实现.综合分析结果,选用了丙烷预冷氮膨胀液化天然气流程.     

Failure analysis of 101-C ammonia plant heat exchanger

Long-term overheating is a major cause of failures in boiler tubes of different designs and operation conditions. These failures are usually related to the formation and growth of internal oxide scales or deposits at areas of high heat flux. Deposits might have different sources; poor water treatment and general corrosion in the system are two common types of these sources. Thickening of the deposit layer hinders heat transfer and local spots of high metal temperature are created in the tube wall. With increasing metal temperature, creep becomes much faster leading to tube failure under internal pressure. In this paper, a case history involving this type of failure is presented. Using finite element modeling the failure are analyzed and some methods to prevent this type of failure are recommended.     

绕管换热器壳侧气相流动实验与数值模拟

搭建了绕管换热器壳侧流动实验平台,并对一个竖直布置的4层绕管式换热器进行了壳侧空气流动实验。与关联式进行对比,包含换热器结构参数的Messa压降关联式,平均绝对偏差12.82%。同时,针对绕管式换热器壳侧几何结构的周期性,利用周期性边界条件,简化了绕管换热器壳侧的几何模型。并应用简化后的三维微元结构对绕管壳侧的传热和压降特性进行了数值模拟。模拟结果与实验较为吻合,压降的平均绝对偏差为16.81%。     

水平面气泡法在板翅式换热器气密性检漏中的应用

介绍板翅式换热器气密性检漏的常用方法及其优缺点,阐述使用水平面气泡法进行板翅式换热器气密性检漏试验的器材、流程、准备工作、具体步骤和试验数据。通过对比应用水平面气泡法与其他方法进行气密性检漏的结果,得出水平面气泡法具有时间短、效率高、易操作、成本低、准确率高的优点。     

The recovery and liquefaction of helium from natural gas in Poland

The Polish helium plant due to start operating at the end of 1974 will have a production capability of 150 MM ft³ per annum. It will be the first bulk helium liquefaction plant to be built in Europe and will play an important role as the major indigenous source of helium in the Eastern hemisphere.     

Motion of a gas in a cyclone heat exchanger

A semi-empirical theory of turbulence is used to obtain relations for calculation of the field of gas velocity in the flow core and boundary layer in a cyclone chamber. To close the system of Navier-Stokes equations, the apparent shear stress is represented in the form of the gradient dependence in circulation. The relations for calculating the tangential component of velocity were derived using experimental data on the qualitative character of the distribution of apparent shear stress over the radius of the cyclone.Translated from Inzhenerno-fizicheskii Zhurnal, Vol. 60, No. 2, pp. 277–284, February, 1991.     

第三类边界条件下套管内天然气中CO2凝华换热分析

针对带压液化天然气(PLNG)流程中对高二氧化碳含量天然气进行二氧化碳凝华分离的设想,分析了天然气中二氧化碳在套管内的凝华换热。将天然气简化为甲烷+二氧化碳的二元混合物,该混合物在圆管内流动,被管外冷氮气冷却直至其中二氧化碳凝华析出。建立了该传热过程的数学模型,采用四阶Runge-Kutta法求解微分方程,分析了天然气和氮气流速、二氧化碳进口体积分数、氮气进口温度、管长对第三类边界条件下凝华换热过程的影响。     

Failure analysis of heat exchanger fluid vapor phase vent lines in a Polyester plant

A Polyester plant is using Proprietary heat exchange fluids (26.5% biphenyl, 73.5% diphenyloxide). The plant hot condensate tank, condensate feed tank, and heat exchanger vapor phase dead end and ventable lines (ASTM 106 Grade B) with isolation valves were suffering frequent leakages with severe gouging and pitting corrosion. Lustrous (shiny) coke deposit was prominent inside the cut sections due to coke formation by low boiler products. Some adhered brown iron oxide (rust) deposits were also visible. A sludge sample was analyzed by XRD which revealed that carbon was the major constituent with γ-Maghemite-C (an iron oxide) as second mineral in order of abundance. The failure was diagnosed as severe localized corrosion and gouging at temperatures of about 200 °C and 53 psi by non-condensable low boilers decomposed corrosive products. The remedy was suggested which has been validated over the 2 years trouble free performance.     

转轮式热交换器在湖南地区的应用

介绍湖南地区的气候情况及使用焓频率法分析转轮式热交换器在湖南各主要城市全年能量回收情况，并进行经济性分析。