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过程装备与控制工程专业英语————————————————————————————————作者：————————————————————————————————日期：过程装备与控制工程专业英语学院：化学化工学院1.Static Analysis of Beams⑴ A bar that is subjected to forces acting trasverse to its axis is called a beam. In this section weconsider only a few of the simplest types of beams, such as those shown in Flag.1.2. In every instance it is assumed that the beam has a plane of symmetry that is parallel to the plane of the figure itself. Thus ， the cross section of the beam has a vertical axis of symmetry .Also,it is assumed that the applied loads act in the plane of symmetry ,and hence bending of the beam occurs in that plane. Later we will consider a more general kind of bending in which the beam may have an unsymmetrical cross section.⑵ The beam in Fig.1.2, with a pin support at one end and a roller support at the other, is calleda simply support beam ,or a simple beam . The essential feature of a simple beam is that both ends of the beam may rotate freely during bending, but the cannot translate in lateral direction. Also ,one end of the beam can move freely in the axial direction (that is, horizontal). The supports of a simple beam may sustain vertical reactions acting either upward or downward .⑶ The beam in Flg.1.2(b) which is built-in or fixed at one end and free at the other end, iscalled a cantilever beam. At the fixed support the beam can neither rotate nor translate, while at the free end it may do both. The third example in the figure shows a beam with an overhang. This beam is simply supported at A and B and has a free at C.⑷ Loads on a beam may be concentrated forces, such as P1 and P2 in Fig.1.2(a) and (c), ordistributed loads loads, such as the the load q in Fig.1.2(b), the intesity. Distributed along the axis of the beam. For a uniformly distributed load, illustrated in Fig.1.2(b),the intensity is constant; a varying load, on the other hand, is one in which the intensity varies as a function of distance along the axis of the beam.⑸ The beams shown in Fig.1.2 are statically determinate because all their reactions can bedetermined from equations of static equilibrium. For instance ,in the case of the simple beam supporting the load P 1 [Fig.1.2(a)], both reactions are vertical, and tehir magnitudes can be found by summing moments about the ends; thus,we findL a L P R A )(1-= LL P R B 1= The reactions for the beam with an overhang [Fig.1.2 (c)]can be found the same manner.⑹ For the cantilever beam[Fig.1.2(b)], the action of the applied load q is equilibrated by avertical force RA and a couple MA acting at the fixed support, as shown in the figure. From a summation of forces in certical direction , we include thatqb R A =， And ,from a summation of moments about point A, we findM，The reactive moment MA acts counterclockwise as shown in the figure.⑺ The preceding examples illustrate how the reactions(forces and moments) of staticallydeterminate beams requires a considerition of the bending of the beams , and hence this subject will be postponed.⑻ The idealized support conditions shown in Fig.1.2 are encountered only occasionally inpractice. As an example ,long-span beams in bridges sometimes are constructionn with pin and roller supports at the ends. However, in beams of shorter span ,there is usually some restraint against horizonal movement of the supports. Under most conditions this restraint has little effect on the action of the beam and can be neglected. However, if the beam is very flexible, and if the horizonal restraints at the ends are very rigid , it may be necessary to consider their effects.⑼ Example Find the reactions at the supports for a simple beam loaded as shown infig.1.3(a ). Neglect the weight of the beam.⑽ Solution The loading of the beam is already given in diagrammatic form. The nature of thesupports is examined next and the unknow components of reactions are boldly indicated on the diagram. The beam , with the unknow reaction components and all the applied forces, is redrawn in Fig.1.3(b) to deliberately emphasiz this important step in constructing a free-body diagram. At A, two unknow reaction components may exist , since roller. The points of application of all forces are carefully noted. After a free-body diagram of the beam is made, the equations of statics are applied to abtain the sollution.∑=0x F ，R Ax =0∑+=0A M，2000+100（10）+160（15）—R B =0，R B =+2700lb ↑ ∑+=0B M,RAY(20)+2000—100（10）—160（5）=0，RAY=—10lb ↓ Check ：∑+↑=0FX ，—10—100—160+270=0 ⑾ Note that ∑=0x F uses up one of the three independent equations of statics, thus onlytwo additional reaction compones may be determinated from statics. If more unknow reaction components or moment exist at the support, the problem becomes statically indeterminate.⑿ Note that the concentrated moment applied at C enters only the expressions for summationmoments. The positive sign of RB indicates that the direction of RB has been correctlyassumed in Fig.1.3(b). The inverse is the case of RAY ,and the vertical reaction at a is downward. Noted that a check on the arithmetical work is available if the caculations are made as shown.横梁的静态分析⑴ 一条绕其轴水平放置的棒就是所谓的横梁，本章节我们将研究最简单的横梁模型形式，如图1.2所示。
General Equilibrium Conditions of A System力系的一般平衡条件在这一部分，我们将研究为了使一个物体保持平衡，作用在其上的力和力偶所必须满足的条件。
根据牛顿第一定律，施加在一个静止物体上的力系的合力一定为零。
然而，请注意这个定律对力矩或力系的转动效应只字未提。
显然，合力矩也一定为零，否则物体将会转动。
这里的基本问题是原先叙述的牛顿第一定律（和第二定律）只适用于非常小的物体，或者尺寸可以忽略的非零质量的粒子。
然而，它可以扩展到如下所述的有限尺寸的物体。
考虑一个由两个质点组成的系统，假设1f 和2f 为它们之间的相互作用力(图.1.1)。
这些力称为内力，因为它们是由于系统内部的物体之间的相互作用而产生的。
假定内力服从牛顿第三定律，我们有12f f =-。
假如还有质点与系统外物体之间的相互作用力施加在质点上，如1,2F F 和3F ,这些力称为外力。
显然，作用在一个特定粒子上的力一定有相同的应用，因为粒子的尺寸可以忽略。
如果系统内的每一个质点处于平衡，我们就可以说系统是平衡的。
在本例中，依据牛顿第一定律，作用在每个质点上的力的合力一定为零。
对质点A 我们有：∑=++=0121f F F F A 而对质点B 有：∑032=+=F f F B作用在系统上的力的总和为：123120A B F F F F F F f f =+=++++=∑∑∑现在我们来研究这些力对于同一点P 的合力矩。
由图1.1，我们有：12()()P A B M r F r F =⨯+⨯∑∑∑ 由于力1f 和2f 有相同的作用线，力矩的条件可以改写为1121223()0P M r F F f f r F =⨯++++⨯=∑ 但12f f =-；所以力和力矩的条件简化为1210F F F F +=+=∑ 和111223()()()0P M r F r F r F =⨯+⨯+⨯=∑换句话说，如果系统处于平衡，那么作用在其上的合外力一定为零，而且这些力对于任一点的合力矩也为零。
Heat exchangers are equipment primarily for transferring heat between hot and cold have separate passages for the two streams and operate most versatile and widely used exchangers are the shell-and-tube types but various plate and other types are valuable and economically competitive or superior in some other types will be discussed briefly but most of the space following will be devoted to the shell-and-tube types primarily because of their importance but also because they are most completely documented in the they can be designed with a degree of confidence to fit into a other types are largely proprietary and for the most part must be process designed by their manufacturers.Plate-and-Frame Exchangers Plate-and-frame exchangers are assemblies of pressed corrugated plates on a frame. Gaskets in grooves around the periphery contain the fluids and direct the flows into and out of the spaces between the spacing and the presence of the corrugations result in high coefficients on both sides several times those of shell-and tube equipment and fouling factors are accessibility of the heat exchange surface for cleaning makes them particularly suitable for fouling services and where a high degree of sanitation is required as in food and pharmaceutical pressures and temperatures are limited by the natures of the available gasketing materials with usual maxima of 300 psig and 400 F.Since plate-and-frame exchangers are made by comparatively few concerns most process design information about them is proprietary but may be made available to serious factors and heat transfer coefficients vary with the plate spacing and the kinds of costs per unit of heat transfer are said to be lower than for shell-and-tube stainless steel construction the plate-and-frame construction cot is 50%-70% that of the shell-and-tube.Spiral Heat Exchangers In spiral heat exchangers the hot fluid enters at the center of the spiral element and flows to the periphery; flow of the cold liquid is countercurrent entering at the periphery and leaving at the transfer coefficients are high on both sides and there is no correction to the log mean temperature difference because of the true countercurrent'action. These factors may lead to surface requirements 20% or so less than those of shell-and-tube exchangers. Spiral types generally may be superior with highly viscous fluids at moderate pressures.Compact (Plate-Fin) Exchangers Compact exchangers are used primarily for gas they have surfaces of the order of 1200 m2 /m3 corrugation height mm corrugation thickness mm and fin density 230-700 fins/ large extended surface permits about four times the heat transfer rate per unit volume that can be achieved with shell-and-tube have been designed for pressiIres up to 80 atm or close spacings militate against fouling compact exchangers are used in cryogenic services and also forheat recovery at high temperatures in connection with gas mobile units as in motor vehicles compact exchangers have the great merits of compactness and light kind of arrangement of cross and countercurrent flows is feasible and three or more different streams can be accommodated in the same drop heat transfer relations and other aspects of design are well documented.Air Coolers In such equipment the process fluid flows through finned tubes and cooling air is blown across them with fans. The economics of application of air coolers favors services that allow 25-40 1" temperature difference between ambient air and process the range above 10 Mbtu/l air coolers can be e conomically competítíve with watercoolers when water of adequate quality is available in su Hicient amountDouble-Pipe Exchangers This kind of exchanger consísts of a central pipe supported withín a larger one by packíng glands. The straight length is limited to a maximum of about 20 ft;otherwise the center pipe wi1l sag and cause poor distribution in the is customary to operate with the high pressure high temperature high density and corrosive fluid in the inner pipe and the less demanding one in the annulus. The inner surface can be provide with scrapers as in dewaxing of oils or crystallization from longitudinal fins in the annular space can be used to improve heat transfer with gases or viscous greater heat transfer surfaces are needed several double-pipes can be stacked in any combination of series or parallel.Double-pipe exchangers have largely lost out to shell-and-tube units in recent may be worth considering in these situations:1. When the shell-side coefficient is less than half that of the tubeside;the annular side coeHicient can be made comparable to the tube side.2. Temperature crosses that require multishell shell-and-tube units can be avoided by the inherent true countercurrent flow in double pipes.3. High pressures can be accommodated more economically in the annulus than they can in a larger diameter shell.4. At duties requiring only 100~200 sqft of surface the double-pipe may be more economical even in comparison with off-the-shell unts.Shell-and-Tube Exchangers This type of exchangers will be discussed in the following section.(Selected from: Stanley Chemical Process Equiment Butterworth Publishers 1988.)Words and Expressionsn.通道，通过a.多用途的，通用的a.专利的，私有的v.成波纹状，起波纹;corrugation nn.沟，槽n.系数n.密封垫片v.弄脏，堵塞;fouling factor 污垢系数n.卫生a.制药的；药物的n. ; a.逆流n.翅片;v.装翅片v.妨碍，起作用a.冷冻的，低温的n.恢复，回收，再生n.填料盖，密封套v.下垂，下沉n.环状空间; annular a环形的.v.脱蜡n.结晶，结晶体n.堆积，烟囱α.内在的，固有的v.调节，适度，容纳Unit 19 换热器的种类换热器起初是为了在热流和冷流中传热。
（建筑工程管理）过程装备与控制工程专业英语翻译GeneralEquilibriumConditionsofASystem力系的一般平衡条件在这一部分，我们将研究为了使一个物体保持平衡，作用在其上的力和力偶所必须满足的条件。
根据牛顿第一定律，施加在一个静止物体上的力系的合力一定为零。
然而，请注意这个定律对力矩或力系的转动效应只字未提。
显然，合力矩也一定为零，否则物体将会转动。
这里的基本问题是原先叙述的牛顿第一定律（和第二定律）只适用于非常小的物体，或者尺寸可以忽略的非零质量的粒子。
然而，它可以扩展到如下所述的有限尺寸的物体。
考虑一个由两个质点组成的系统，假设和为它们之间的相互作用力(图.1.1)。
这些力称为内力，因为它们是由于系统内部的物体之间的相互作用而产生的。
假定内力服从牛顿第三定律，我们有。
假如还有质点与系统外物体之间的相互作用力施加在质点上，如和,这些力称为外力。
显然，作用在一个特定粒子上的力一定有相同的应用，因为粒子的尺寸可以忽略。
如果系统内的每一个质点处于平衡，我们就可以说系统是平衡的。
在本例中，依据牛顿第一定律，作用在每个质点上的力的合力一定为零。
对质点A我们有：而对质点B有：作用在系统上的力的总和为：现在我们来研究这些力对于同一点P的合力矩。
由图1.1，我们有：由于力和有相同的作用线，力矩的条件可以改写为但；所以力和力矩的条件简化为和换句话说，如果系统处于平衡，那么作用在其上的合外力一定为零，而且这些力对于任一点的合力矩也为零。
内力不需要考虑，因为它们的效应相互抵消了。
如果系统处于平衡，那么and(1.1)这里是作用在系统上的所有外力的总和，而是这些力对任意点的合力矩，包括系统中可能作用有的力偶的矩。
方程（1.1）是平衡的必要条件；也就是说，如果系统处于平衡，必须满足这些方程。
一般来说它们不是平衡的充分条件。
然而，这并不会带来任何困难，因为我们的研究仅涉及平衡系统。
对于刚体，方程（1.1）既是其平衡的必要条件也是充分条件。
abrasiveness 研磨；腐蚀absolute 绝对的accumulate 堆积；积累acid 酸；酸性的，酸味的actuator 执行机构adjust 调整；调节agitation 搅拌air preheater 空气预热器air register 空气调节器airflow 气流alkali 碱allowance 公差，容差，容许量alloy 合金alternating current 交流电angle 角度，角apparatus 装置，仪器，仪表application 应用artificial 人造的；仿造的assembly 装配atmospheric 大气的，大气层的austenite 奥氏体automation 自动化，自动操作auxiliary 辅助设备，附属机构backflow 回流baffle 挡板；折流板；隔板batch 一批，批量bearing 轴承bellow 波纹管belt 带；腰带；地带blade 叶片blower 鼓风机boiler 锅炉bolt 螺栓bonnet 阀盖，阀帽，机罩box furnace 箱式炉brittle 易碎的，脆弱的burner 燃烧器bushing 轴衬；套管butterfly valve 蝶阀capacity 容积carbon steel 碳钢，碳素钢casing 机壳cast 浇铸catalyst 催化剂category 分类，种类cavity 腔；洞，凹处centrifugal force 离心力chamber 腔，室，船舱check valve 止回阀checklist 检查表，清单classify 分类；分等clockwise 顺时针方向的- 1 -coating 涂层，覆盖层coefficient 系数coil 盘管，线圈coking 结焦，焦化column 圆柱，柱形物combination 结合combustion 燃烧，氧化component 成分；组件；零件composition 组成，成分compressor 压缩机concentration 浓度concentric 同轴的，同心的condense 浓缩；凝结condenser 冷凝器；凝汽器conduction 传导cone roof 锥形顶constant 常量，常数contract 缩小，收缩contrast 对比，形成对照controller 控制器convection 对流convert 使转变；转换。
exert n.用力,施力fundamental v.基本的negligible a.可以忽略的moment n.力矩(各种矩 equilibrium n.平衡的cancel out 相约,相消preceding a.以前的pulley n.滑轮,皮带轮relegate vt.归类,委托Component n.分力,分量Scalar n.;a.纯量,标量Statically determinate 静定transverse a.横向,横切symmetry n.对称性pin support 铰支座roller support 滚轴支座translate 平移lateral 横向的,水平的sustain 支撑,承受住cantilever悬臂overhang外伸intensity 强度,密度reaction反作用力magnitude大小,量级equilibrate(使平衡inverse相反的counterclockwise逆时针方向的deliberately审慎的,故意的stress 应力strain应变deformable可(易变形的shaft轴derivation 推导,导出axially-loaded 受轴向载荷的blend 混合tension 拉伸,张力shear 剪切,剪力prismatic 等截面的at right angles to与。
垂直analogous类似的hydrostatic流体静力学submerge浸没,沉没denote 表示,指示resultant合力;合成的centroid质心,矩心,重心elongation伸长,延伸率adjacent 相邻的,临近的free-body自由体bendin moment弯矩convention协定,惯例algebraic 代数的truss 桁架unknowingly 无意中,不知不觉的lowercase 小写visualize 假设patently 明白的perpendicular 垂直,直立vector 矢量squash 压缩tangential 切向subscript 下标,脚码say 假定algebraic 代数差unidirectional 单向,单自由度的postulate 假设ductile 可塑,可锻,韧性的criterion 标准,规范rupture 断裂,破坏specimen 样本,试件monitor 监视,控制multitude 众多,大批sin 罪恶,犯罪ignorance 未知yield-point 屈服点longgitudinal 轴向的,纵向的circumferential 圆周的,环形的oscillatory 振荡的,摆动的confront 面临,面对wear 磨损,耐磨性fatigue 疲劳acute 敏锐,尖锐impair 损害,减少symmertrical 对称的,均匀的propeller 螺旋桨,推进器compact 压实,压紧chaff 废物,渣滓thresh 猛烈摆动glider 滑翔机panel 底座helical 螺旋(线,面,形 springboard 跳板,出发点pendulum 振动体bob 振子球displacement位移,平移customary 通常,习惯的reciprocal 相互的,倒数的amplitude 振幅angular 角,成角度的dissipative 损耗,消耗的damp 阻尼,减震viscous 粘性的constrain 约束coordinate 坐标specify 指定,确定detect 探测,检测knife-edges 韧性支承rotor转子armature 电枢,转子crankshaft 曲轴,centtrifugal 离心式的,离心机rock 摇动,摆动bearing 轴承equivalent 相等的,等价的converse 逆的,反的oz. ounce 盎司alloy 合金crystal 结晶,晶体lattice 晶格aggregate 集合,集合体valence 化合价electrostatic 静电的conductor 导体wrought 精制的,可锻的cast 浇铸,铸件ferrous 含铁的nonferrous 不含铁intake 吸入,入口manifold 集气管aluminum 铝magnessium 镁beryllium铍brass 黄铜bronze 铜tin 锡zinc 锌elusive 难以理解的ductility 韧性,延展性fracture 破裂brittle 脆性的interplay 相互作用manufacture 加工制造strength of materials 材料力学rheology 流变学outset 开头,开始relevant 有关的,相关的component 分量,组件scope 范围,工作域realm 领悟,范围concept 概念,原理harden 变硬,硬化classification 分类,分级conserve 保存,守恒melt 融化,熔融evaporation 蒸发,汽化forging 锻造characterize 表征,表示。
General Equilibrium Conditions of A System力系的一般平衡条件在这一部分，我们将研究为了使一个物体保持平衡，作用在其上的力和力偶所必须满足的条件。
根据牛顿第一定律，施加在一个静止物体上的力系的合力一定为零。
然而，请注意这个定律对力矩或力系的转动效应只字未提。
显然，合力矩也一定为零，否则物体将会转动。
这里的基本问题是原先叙述的牛顿第一定律（和第二定律）只适用于非常小的物体，或者尺寸可以忽略的非零质量的粒子。
然而，它可以扩展到如下所述的有限尺寸的物体。
考虑一个由两个质点组成的系统，假设1f 和2f 为它们之间的相互作用力(图.1.1)。
这些力称为内力，因为它们是由于系统内部的物体之间的相互作用而产生的。
假定内力服从牛顿第三定律，我们有12f f =-。
假如还有质点与系统外物体之间的相互作用力施加在质点上，如1,2F F 和3F ,这些力称为外力。
显然，作用在一个特定粒子上的力一定有相同的应用，因为粒子的尺寸可以忽略。
如果系统内的每一个质点处于平衡，我们就可以说系统是平衡的。
在本例中，依据牛顿第一定律，作用在每个质点上的力的合力一定为零。
对质点A 我们有：∑=++=0121f F F F A 而对质点B 有：∑032=+=F f F B作用在系统上的力的总和为：123120A B F F F F F F f f =+=++++=∑∑∑现在我们来研究这些力对于同一点P 的合力矩。
由图1.1，我们有：12()()P A B M r F r F =⨯+⨯∑∑∑ 由于力1f 和2f 有相同的作用线，力矩的条件可以改写为1121223()0P M r F F f f r F =⨯++++⨯=∑ 但12f f =-；所以力和力矩的条件简化为1210F F F F +=+=∑ 和111223()()()0P M r F r F r F =⨯+⨯+⨯=∑换句话说，如果系统处于平衡，那么作用在其上的合外力一定为零，而且这些力对于任一点的合力矩也为零。
General Equilibrium Conditions of A System力系的一般平衡条件在这一部分，我们将研究为了使一个物体保持平衡，作用在其上的力和力偶所必须满足的条件。
根据牛顿第一定律，施加在一个静止物体上的力系的合力一定为零。
然而，请注意这个定律对力矩或力系的转动效应只字未提。
显然，合力矩也一定为零，否则物体将会转动。
这里的基本问题是原先叙述的牛顿第一定律（和第二定律）只适用于非常小的物体，或者尺寸可以忽略的非零质量的粒子。
然而，它可以扩展到如下所述的有限尺寸的物体。
考虑一个由两个质点组成的系统，假设1f 和2f 为它们之间的相互作用力(图.1.1)。
这些力称为内力，因为它们是由于系统内部的物体之间的相互作用而产生的。
假定内力服从牛顿第三定律，我们有12f f =-。
假如还有质点与系统外物体之间的相互作用力施加在质点上，如1,2F F 和3F ,这些力称为外力。
显然，作用在一个特定粒子上的力一定有相同的应用，因为粒子的尺寸可以忽略。
如果系统内的每一个质点处于平衡，我们就可以说系统是平衡的。
在本例中，依据牛顿第一定律，作用在每个质点上的力的合力一定为零。
对质点A 我们有：∑=++=0121f F F F A 而对质点B 有：∑032=+=F f F B作用在系统上的力的总和为：123120A B F F F F F F f f =+=++++=∑∑∑现在我们来研究这些力对于同一点P 的合力矩。
由图1.1，我们有：12()()P A B M r F r F =⨯+⨯∑∑∑ 由于力1f 和2f 有相同的作用线，力矩的条件可以改写为1121223()0P M r F F f f r F =⨯++++⨯=∑ 但12f f =-；所以力和力矩的条件简化为1210F F F F +=+=∑ 和111223()()()0P M r F r F r F =⨯+⨯+⨯=∑换句话说，如果系统处于平衡，那么作用在其上的合外力一定为零，而且这些力对于任一点的合力矩也为零。
Reading Material 18Packed TowersIn comparison with tray towers, packed towers are suited to small diameters (24 in. or less ), whenever low pressure is desirable, whenever low holdup is necessary, and whenever plastic or ceramic construction is required. Applications unfavorable to packings are large diameter towers, especially those with low liquid and high vapor rates, because of problems with liquid distribution, and whenever high turndown is required. In large towers, random packing may cost more than twice as much as sieve or valve trays.Depth of packing without intermediate supports is limited by its deformability; metal construction is limited to depths of 20~25 ft, and plastic to 10~15 ft. Intermediate supports and liquid redistributors are supplied for deeper beds and at sidestream withdrawal or feed points. Liquid redistributors usually are needed every 2 . 5~3 tower diameters for Raschig rings and every 5~10diameters for Pall rings. But at least every 20 ft.The various kinds of internals of packed towers are represented in Fig. 4. 2 whose individual parts may be described one-by-one:(a)is an example column showing the inlet and outlet connections and some of the kinds ofinternals in place.(b)Is a combination packing support and redistributor that can also serve as a sump forwithdrawal of the liquid from the tower.(c)Is a trough-type distributor that is suitable for liquid rates in excess of 2 gpm / sqft intowers 2 feet and more in diameter. They can be made in ceramics or plastics.(d)Is an example of a perforated pipe distributor which is available in a variety of shapes,and is the most efficient type over a wide range of liquid rates; in large towers and where distribution is especially critical, they are fitted with nozzles instead of perforations.(e)Is a redistribution device, the rosette, that provides adequate redistribution in smalldiameter towers; it diverts the liquid away from the wall towards which it tends to go.(f)Is a hold-down plate to keep low density packings in place and to prevent fragile packingssuch as those made of carbon, for instance, from disintegrating because of mechanical disturbances at the top of the bed.The broad classes of packings for vapor-liquid contacting are either random or structured.The former are small, hollow structures with large surface per unit volume that are loaded at random into the vessel. Structured pakings may be layers of large rings or grids, brt are most commonly made of expanded metal or woven wire screen that are stacked in layers or as spiral windings.There are several kinds of packings. The first of the widely used random packings were Raschig rings which are hollow cylinders of ceramics, plastics, or metal. They were an economical replacement for the crushed rock often used then. Because of their simplicity and their early introduction, Raschig rings have been investigated thoroughly and many data of their performance have been obtained which are still useful, for example, in defining the lower limits of mass transfer efficiency that can be realized with improved packings.Structured packings are employed particularly in vacuum service where pressure drops must be kept low. Because of their open structure and large specific surface, their masstransfer efficiency is high when proper distribution of liquid over the cross section can be maintained.阅读材料18填料塔与板式塔相比，填料塔适用于小直径、低压力、小储量及塑料或陶瓷材料。
