透明膜加热管的应用——新型热虹吸再沸器用于硫酸工艺流程及设备改革的探讨

许多试剂的生产都使用玻璃瓶作为精馏釜或蒸发器,加热炉是用电阻丝绕制而成,传热效率低。本文选硫酸精制工业为改革对象,这是因为硫酸沸点高,操作条件苛刻,若能成功,有普遍意义,可推广到其它试剂生产的工艺设备改革。目前试剂厂生产精制硫酸,所用的精馏釜是直径为250毫米、高度600毫米(加热段300毫米)的玻璃瓶。每台设备的功率为4.5千瓦,产量仅有50公斤/天。热效率约为14.2％。我们最近用“透明膜加热管”制成热虹吸再沸器,用水作为介质,进行试验,取得满意结果。从理论上推算,将此新型设备用于硫酸精制,达到同样产量。总能耗(包括热损失)约为20～30千瓦。可节能80～90千瓦(每年六十万度电以上)。     

多组分蒸汽在水平管内冷凝传热的计算方法及验证

本文以Bell and Ghaly法(亦称气相热阻法)为基础,结合两相流流型的研究结果,提出多组分混合蒸汽在水平管内冷凝传热的计算方法。且用庚烷-己烷-氮气在空冷器内进行冷凝实验,计算值与实验值吻合较好,说明该法具有一定的可靠性和工程使用价值。     

回流冷凝器中液泛速度的研究

本文在4 m的长管回流冷凝器中对液泛速度进行了研究,观察了液泛过程及两相流动状况,建立了计算液泛速度的数学模型,用本模型计算出的液泛速度与实验值进行比较,计算值与实验值吻合较好。     

CONDENSING HEAT TRANSFER IN AN ADVANCED TWO-PHASE CLOSED THERMOSYPHON

1 INTRODUCTIONClosed thermosyphon has been developed to enhance heat transfer and recover wasteheat in various process industries [1,2].Stimulated by this success,a new type oftwo-phase closed thermosyphon was designed by inserting respectively two inner tubesinto the thermosyphon,one in the boiling section and the other in the condensing sec-tion.The two-phase flow boiling heat transfer coefficient was calculated successfully onthe basis of Chen's dual-mechanism [3].A boiling heat transfer model for thetwo-phase closed thermosyphon with an inner tube in the boiling section was pro-     

A STUDY ON FLOODING VELOCITIES IN INCLINED REFLUX CONDENSERS

This paper deals with the flooding velocities of the reflux condensers with various inclinations.The flooding phenomena and two-phase flow patterns in such condensers have been observed. A physical and a mathematical models for calculating flooding velocities are developed, which agree well with the experimental data. The flooding velocity in an inclined reflux condenser varies with the inclination and may reach the maximum value when the inclination is between 30° and 50°.     

INTERNAL THERMOSYPHON REBOILER

A very serious problem of instability that arises in the vertical thermosyphon reboilers can be solved by a newly developed equipment called internal thermosyphon reboiler. Experiments were carried out in both quartz tube and copper tube with the same geometrical dimensions. The former allowed better visual observation and the latter gave more quantitative informations. Water, sulfuric acid, triethanol-amine, heavy oil, ethanol-water, methanol-ethanol, ethanol-propanol and some other mixtures were used as working media. Particles of polypropene with density very close to water were used as the tracer in water system for investigating the flow characteristics. Rate of circulation, flow patterns, rate of heat transfer and fouling in this equipment were studied. A flow model and a design method were proposed. The results calculated could predict the characteristics of two-phase flow and heat transfer inside this boiling equipment.     

两相流及传热(一) 综述

许多生产工艺过程及设备都遇到处理气、液两相混合物的问题。这种混合物在管道或设备中流动,称为两相流动或两相流。两相流中还常常伴有传热过程及相的变化。两相流的流动机理和传热动机理都与单相流很不相同。应特别指出,两相流的研究远不如单相流充分,有关压降及传热的计算公式及方法亦不如单相流的完善和准确。     

两相流及传热(四) 冷凝传热

冷凝传热应用十分广泛,如蒸馏塔顶蒸气的冷凝,加热蒸气的冷凝,冷冻过程中冷冻剂蒸气的冷凝等。其主要设备有:管壳式冷凝器、空冷式冷凝器、板式冷凝器及螺旋板式冷凝器。 冷凝是指蒸气与低于蒸气露点温度的壁面接触时发生的过程。由于流型难于判断、通常归纳为两大类,即重力控制的冷凝和剪力控制的冷凝。     

高普朗特数液体的流动沸腾传热

在不同几何结构的热虹吸沸腾装置中对高Pr准数液体的流动沸腾传热进行实验研究.实验介质为乙醇、丙酮、异丁醇.Pr准数从3.81变化到26.3.将实验结果与文献数据进行比较.从机理上分析Pr 准数对两相流传热的影响,并探讨两相流因子F_(tp)的几个关联式的适用范围.     

内热虹吸式再沸器

立式热虹吸再沸器内的流动不稳定性是一个严重问题.本文作者最近研制的内热虹吸再沸器能够解决上述问题.采用相同几何尺寸的石英管及铜管进行实验,前者有利于观察研究,后者则能提供更多的定量结果.工作介质为水、硫酸、三乙醇胺 重油、乙醇-水、甲醇-乙醇、乙醇-丙醇及其他一些混合物.在观察水在管内的流动特性试验中,用聚丙烯颗粒作为示踪粒子,其密度与水非常相近.研究的内容包括循环速率、流型、传热速率及结垢等问题.提出了一个流动模型及设计方法.计算结果可用来推算此沸腾设备内的两相流及传热特性.