常常有许多传热在石油.doc

螺旋折流扳换热器

常常有许多传热在石油，化工，电力，冶金，能源等工业部门所涉及的问题。 The shell and tube heat exchanger is the heat transfer equipment most widely used in the current industrial production.在管壳式换热器是换热设备在目前最广泛用于工业生产。 Compared with other types, its main advantages are the large heat transfer area in the unit volume and good heat transfer effect.与其他类型相比，它的主要优点是大型热单位体积传热效果和良好的换热面积。 Combined with a simple structure, wide range of materials required in manufacturing, and greater operation flexibility, it is more and more widely used in the chemical engineering fields.具有结构简单，制造所需的各种材料和更大的操作灵活性相结合，越来越广泛地在化工领域使用。
To increase the speed of shell fluid and intensify the turbulent level to improve the shell film coefficient of heat transfer, the traverse baffle is usually installed in the shell and tube heat exchanger.为了提高速度，加大壳程流体的湍流水平，以改善壳膜传热系数，横向挡板通常安装在管壳式换热器中。 The most common one is segmental baffle.最常见的是弓形折流。 Fluid winds in the shell outfit with segmental baffle at the continuously changing speed in different directions, and is easy to separation especially in the baffle edge.流体与弓形折流壳装在不同的方向，以适应不断变化的速度，这样就很容易分离，特别是在挡板的边缘。 Due to the flow dead zone between segmental baffles and the shell, fluid undergoes repeated movement of cross streams in the baffles, resulting in the reduction of driving force of heat transfer.由于流体弓形与壳体死区之间流动，流体经过反复十字运动经过溪流挡板，使驱动力的传热减少。 For obtaining higher heat transfer performance, only the plate spacing is reduced, which is inevitably accompanied by a higher flow resistance at the cost of higher energy consumption.为了获得更高的传热性能，板间距仅减少，在流动阻力陪同下成本较高和更高的能源消耗的是不可避免的。 Therefore, the traditional form change of baffle is badly needed.因此，改变传统形式的挡板，是迫切需要的。

Fig.图。 1 The Shell Flow Diagram of Heat Exchanger with Segmental Baffles 1，壳式换热器流程图弓形器
The heat exchanger with helical baffles becomes an ideal alternative because of its unique advantages.螺旋隔板换热器之所以成为一个独特的优势，因为It uses the continuous helical backing plate in support of heat exchange tube to make the shell medium do the inclined forward movement along the spiral channel from the shell entrance.它使用的热交换管支撑连续螺旋垫板，使壳中做从壳沿螺旋通道入口处的斜向前运动。 Since the traditional horizontal baffling way is changed to the vertical helical baffling means, the heat exchanger with helical baffles greatly enhances its heat transfer effect while reducing the resistance of shell side.由于传统的水平方式改为垂直螺旋式的螺旋折流板换热器，大大提高了换热效果，同时降低了壳侧阻力。 Its characteristics are: (1) The continuous smooth spiral flow of medium in the shell side avoids the serious pressure loss caused by horizontal baffling with lower pressure drop.其特点是：（1）连续介质中的螺旋壳侧流避免了严重的压力损失和更低的的压降水平造成的。 (2) Compared with the segmental baffle, in the state of same pressure drop, it can significantly improve the shell medium flow rate, and thereby increase the turbulence level and the medium heat transfer capability. （2）与弓形折流相比，在相同压降状态，它可以显着提高壳介质流量，从而提高水平和动荡中的传热能力。 (3) The spiral movement of the shell medium generates velocity gradient on the radial cross-section and form radial turbulence in favor of the thinned bottom layer of the heat-exchange surface detention and the enhanced film heat transfer coefficient. （3）壳中的螺旋运动产生的径向截面和在冷热交换表面拘留底层变薄和增强膜传热系数径向湍流速度有利于形成梯度。 (4) There is no dead zone. （4）没有死区。 While improving the heat transfer coefficient, the vertical helical baffling way reduces dirt deposition, has stable thermal resistance, and allows the heat exchanger in a highly efficient running state.同时提高了传热系数，垂直螺旋莫名其妙地减少污垢沉积，具有稳定的耐热性，并允许在一个高效换热的运行状态。 (5) Thanks to the stronger constraints on the heat exchanger than the segmental baffle, the helical baffle lessens the tube bundle vibration and extends the operational life. （5）就比弓形折流式换热器的强大制约下，螺旋隔板减少了管束振动，延长使用寿命。 (6) When the shell is condensing for heat exchange, the helical baffle can play the role of drainage of the condensate liquid, decrease the coverage of the condensate liquid on the lower rows of tubes, and thereby enhances the effect of heat transfer. （6）当外壳进行热交换凝结，螺旋隔板可以起到排水作用，凝析液减少了冷凝水的覆盖面，具有较低的管行液体，从而增强了传热效果。
According to StehlikP's researches, compared with the traditional heat exchanger with segmental baffles, the heat exchanger of helical baffle gets 1.8 times higher of the heat transfer coefficient and 25% lower of flow resistance in the same condition.据StehlikP的研究，在相同的条件下，相对于传统的弓形换热器，螺旋折流板换热器获得1.8倍的传热系数和25％的流动阻力。 Chen Shixing concludes: for high-viscosity oil, the heat exchanger with helical baffles has the convection heat transfer coefficient of about 1.5 times in the unit pressure drop that that of the ordinary heat exchanger with segmental baffles; for water, about 2.4 times.陈师兴结论：高粘度油，螺旋折流板换热器的对流换热装置中的压力下降，改用用弓形换热器是普通换热器的约1.5倍系数，对水，约是2.4倍。 Song Xiaoping presents the application of over ten units of heat exchangers with helical baffles in the refinery, and finds that its performance indicators are better than the original segmental baffle heat exchanger.宋晓平介绍了以上的炼油厂在螺旋折流板换热器十个单位的申请，并认为，其性能指标均优于原来的弓形折流式换热器更好。 The heat exchanger with helical baffles makes the efficiency of heat transfer greatly improved, the heat transfer area and metal consumption decreased, and thereby the investment in equipment installations reduced.与螺旋隔板换热器，使传热效率大大提高，传热面积和金属消费量下降，从而在设备设施的投资减少。
However, the spiral surface machining is difficult and the coordination between heat exchanger and baffle is hard to achieve.然而，螺旋曲面加工困难，换热器和挡板之间的协调是很难达到的。 Taking the processing convenience into account, a series of standard sectorial planes (known as helical baffles) are adopted in place of the curved surface alternate connections, to form the similar spiral surface in the shell side and to make the fluid generate continuous spiral flow.考虑到加工方便，扇形面的标准系列（已知的螺旋折流板）是在曲面备用连接的地方通过，形成了类似的螺旋壳侧表面，使流体产生连续的螺旋流动。 See Fig.见图。 2. 2。

Fig.图。 2 Helical Baffle Arrangement in the Shell Side 2，壳程螺旋折流板安排
To reach the spiral flow stability of the shell medium, the helical baffles are required to have the consistent spacing (called baffle spacing F), the same installation angle α, and generally be placed in the lower part of the top entrance and exit axes or the upper part of the bottom axes.为了达到壳介质螺旋流的稳定性，螺旋隔板须有一致的间距（称为挡板间距F）时，相同的安装角α，一般都在顶部的入口和出口轴或下部放置底部轴的上部。 See Fig.见图。 3. 3。

Fig.图。 3 Helical Baffle Arrangement in the Entrance and Exit Ports 3，在入口和出口港口螺旋隔板安排
Since 1997 its first domestic application in Fushun Petroleum Factory, thousands of heat exchangers with helical baffles have been rapidly promoted in the chemical & refining devices in more than 20 companies.自1997年以来第一次在国内的抚顺石油厂适用，从那之后数以千计的螺旋折流板换热器中得到了迅速推广，使用螺旋折流板换热器等炼油化工设备的公司超过20家。 Application results show that the helical baffle in the shell side imposes the impact on reducing the fluid pressure drop compared to the vertical segmental baffle.应用结果表明，壳程螺旋折流板与垂直弓形折流板相比加强了流体压降比的影响。 But it's not fairly obvious in the heat exchanger efficiency.但它明显不是公平的热交换效率。 Some heat exchangers, in particular, the large-diameter heat exchangers with helical baffles are inferior to those of segmental baffles.一些热交换器，特别是大直径螺旋隔板换热器不如弓形的换热器热交换率好。 Through many simulation experiments of different diameter shells and different angles of heat exchangers with helical baffles, it is proved the main reason are the mechanical processing restriction and the extremely difficult achievement of complete helical continuous baffle processing.通过对不同直径弹，并与螺旋折流板换热器不同的角度很多模拟实验，证明了它是主要的原因是机械加工的限制，在完全连续螺旋折流处理极难实现。 Traditional helical baffle is overlapped by two or four panels and arranged into a similar spiral surface.传统的螺旋折流板是重叠的两个或四个小组并安排了类似的螺旋面。 The segmental baffles of 360°/x in projection are placed in correct order with the shell axis in the end-to-end binding at an angle. 360 °的弓形/投影是放置在正确的顺序与在终端到终端的角度结合的壳轴。 The straight flanges of the adjacent two baffles intertwine at the top and butt joint.相邻两个挡板顶部交织的直法兰对接。 The triangular space formed between two adjacent baffles is likely to lead to the medium flow along the baffles, form the short-circuit leakage current and depart the spiral flow.三角相邻两个挡板之间的空间形成的可能导致沿挡板介质流，形成短路漏电电流和离开的螺旋流动。

Fig.图。 4 Traditional Structural Arrangement of Helical Baffle 4传统的螺旋形结构安排
Short-circuit leakage current decreases the flow of an ideal channel.短路漏电电流降低了一个理想的通道流动。 Especially in the large-diameter helical baffle shell and tube heat exchanger, because numerous media flow along the triangle space and gap formed by two adjacent baffles, the spiral flow of main sprue is reduced, the medium flow slowed down, and the efficiency of heat transfer severely affected.尤其是在大口径螺旋折流板管壳式换热器，因为众多媒体沿三角形空间和两个相邻的挡板形成间隙流，主浇道螺旋流量减少时，介质流动速度减缓，以及热效率转让受到严重影响。 To ensure the efficiency rate of heat exchange, Dalian Haite Heat Transfer Technology Co., Ltd. developed a new anti-short circuit helical baffle to make the medium in the shell side flow through in the almost ideal spiral flow pattern.为了保证热交换效率提高，大连海特传热技术有限公司开发的一个新的反螺旋折流短路板，使通过的几乎理想的螺旋流动格局的壳侧流媒体。

Fluid Flow Analysis流体流动分析
On the basis of the segmental baffle, the new anti-short-circuit helical baffle is widen with one or two row(s) of tube spacing on both side of straight flanges, and overlapped in the two adjacent straight flanges, and then penetrated by one or two row(s) of heat exchange tubes.论弓形折流的基础上，新的抗短路螺旋折流板是扩大与一个或两个排在两个直管法兰面间距（s），而在两个相邻的直线法兰重叠，然后穿透一个或两个排热交换管（s）。 The flow simulation experiments show that the short circuit still exists when both sides of the straight flanges of the segmental baffle are widen to 5~10mm more simultaneously.流动模拟实验表明，仍然存在短路时的弓形折流直法兰双方都扩大到5〜10毫米以上同时进行。 The shell medium flows through in the almost ideal helical flow pattern and short circuit is put to an end when one row or two rows of tube spacing is added.通过在螺旋流的几乎理想的模式和壳短路介质流向就有了结束的时候一排或两排管间距增加。 The structural arrangement of anti-short-circuit helical baffle is shown as Fig.反短路螺旋折流板结构布置图所示。 5. 5。

Fig.图。 5 Structural Arrangement of New Anti-short-circuit Helical Baffle 5结构布置新的抗短路螺旋折流
The overlapping connection exerts good guiding effects on the media of the tube bank, reducing short circuit of the triangle space formed by the crossing of two adjacent straight flanges and ensuring the heat transfer efficiency.重叠的连接管上发挥了很好的指导作用，减少由两个相邻的直线穿越法兰和保证传热效率形成的三角形空间短路。 The penetration of one row or two rows of two adjacent heat exchange tubes into the adjacent two segmental baffles reinforces the tube bundle rigidity and avoids the quadrant separation trends.在一行或一两个相邻的两个热交换管行到相邻的两个弓形渗透加强了管束刚性，并避免了象限分离的趋势。 The helical baffle structure in the overlapping part has a good anti-vibration effect.在重叠部分螺旋折流板结构具有良好的抗振动的影响。
In a word, the heat exchanger with helical baffles proves its advantages in the combination property as long as it is properly designed.总之，与螺旋折流板换热器，只要证明了它的综合性能优势，因为它是正确的设计。 However, in comparison with the traditional segmental baffle type, there are still much more researches needed to do, for example: the studies on shell and tube heat exchangers are mostly focus on the segmental baffle until now, and TEMA standard is also directed against it.然而，与传统的弓形折流型比较，仍然有很多需要做更多的研究，例如：对管壳式换热器的研究大多集中在弓形折流至今，提玛标准也是直接反对。 Regarding to the standardized design of helical baffle, it's needed to conduct detailed analyses and studies on the flow and heat transfer mechanism.关于对螺旋隔板标准化设计，它需要在进行的流动和传热机制之间做详细的分析和研究。 Besides the factors to affect the traditional segmental baffle, there are geometrical factors (layout pattern, spiral angle, thread pitch), phase-change cases, and physical properties of different media to be considered.除了传统的影响因素弓形折流，有几何因素（布局模式，螺旋角，螺距）相变的情况下，以及对不同介质的物理特性加以考虑。 Along with the constant development of computer technologies and in-depth studies of the mechanism, the helical baffle heat exchanger is believed to have wider applications.随着计算机技术和机制的深入研究和不断发展，螺旋折流板换热器被认为是更广泛的应用。