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(1). I am having some trouble with understanding conversion,yield,etc．in reacting systems．

我在理解反应系统的转化率、产率等问题上有一些困难。

(2). Chemical reactions involve the exchange of atoms between reacting species under certain rules．The conservation of mass is among the most intrinsic ones．

化学反应包含着各物质之间按一定规则的原子交换。质量守恒是其中最基本的规则之一。

(3). Stoichiometry tells us the useful way to help measure the conversion and conservation of matter taking part in a chemical reaction．

化学计量学给我们指出了有用的方法，帮助我们确定在化学反应中发生的物质转换和守恒。

(4). (writes down:Vla+v2B+v3C← →v4D+V5E．)This represents an exchange of atoms between substances or molecules,a,B and C resulting in the formation of the new substances D and E,strictly according to the ratio of their stoichiometric coefficients Vi．

(写出V1a+V2B+V3C←→v4D+V5E)这个方程代表原子在物质或称分子a、B、C之间交换生成新物质D、E，严格地按照它们的化学计量系数Vi之比进行。

(5). Selectivity expresses the amount of a desired product obtained from the reaction as a fraction of the theoretical amount which could be obtained from the amount of reactant supplied.

选择性表达了反应获得的目标产品的量与从提供的反应物质中按理论应该获得的产品量之比。

(6). In other words it’s a measure of the fraction of undesired by-products.

换句话，它是不希望有的副产品的生成分率的度量。

(7). Plant yield is a convenient way of considering all the chemical and physical losses, and is defined for a specific product as the ratio of amount produced to the theoretical amount calculated

工厂产率是一个考察所有化学和物理损失的方便的方法，对于某一特定产品，它被定义为实际产量与理论计算量之比

(8). Based on a reactant fed to the process according to the stoichiometric coefficients. all these different indicators approach unity as they approach their optimums.

后者是基于供给过程的反应物质量按化学计量系数算得的。所有这些指标当达到它们的最佳状态时，都接近1。

(9). I remember now, the first, second and third laws right.

现在我想得起的就是第一、第二和第三定律。

(10). The first law states that energy can neither be created, nor destroyed.

第一定律说明能量既不会产生．也不会消失。

(11). The second law was that randomness always goes up in a system.

第二定律是说一个系统的混乱程度总是增加的。

(12). As long as the system is isolated. In thermodynamics jargon, randomness is called entropy. The third law states that no system can be reduced to 0 K.

前提是系统要孤立。在热力学行话中，混乱程度叫做熵。第三定律断言，没有一个系统能达到绝对零度。

(13). Problem is, I still don’t follow the implications of those. It’s way over my head.

问题是我仍然不明白它们的含义，这超出了我的头脑的想象能力。．

(14). In chemical engineering, the first law is used to make our most basic equation: In Out + accumulation.

在化学工程中，第一定律用来建立最基本的方程，流入=流出+积累。

(15). So if you fill your sink up, but leave the plug out, when the water level stops rising, the water in = the water out.

比如你往洗手池里灌水却没把塞子塞上，当水位停止上升的时候，就可以说，流进的水=流出的水。

(16). The first reported experiments were done in the late 18th century, but it really took off in the mid 19th century with people like the famous Joule who did the ground work experiments for the discovery of the first law.

最早发表的报告是在18世纪末期，不过真正的起飞是在19世纪中叶，由焦耳等著名人物为第一定律的发现做了奠基性的实验工作。

(17). Myriads of molecules hurtling at high speed in random directions, occasionally moving close enough to one another to interact and maybe react. This is the situation in a chemical reactor.

无数个高速横冲直撞的分子，偶尔才能彼此靠近到足以相互作用并有可能发生反应。这就是化学反应器里的情形。

(18). Historically, a ridiculous cosmic consequence of the second law stated that the universe would end up as merely heat energy. I disagree. The problem lies in that the universe can’t be isolated as required by the law.

历史上，第二定律在宇宙学方面的一个荒谬的推论曾断言就像热能会终结一样，宇宙终有一天会沉寂。我不同意，问题出在宇宙不可能像热力学定律所说的那样被孤立起来。

(19). Molecules reacting occasionally are all well and good, but chemical engineers are interested in causing a lot of the correct reactions to produce useful products, as safely and cheaply as possible.

这些偶尔发生反应的分子确实很好，不过化学工程师更感兴趣的是尽可能安全、尽可能便宜地引发大量的理想反应来生产有用的产品。

(20). For this they must be able to design chemical reactors, which lie at the heart of most chemical plants, and are the site of all this frenetic activity. This is no small problem and a mistake here could be costly.

为此，他们必须能够设计出作为大多数化工厂的心脏的反应器，所有激烈的反应都在里面发生。这不是小事，任何一个错误在这里都要付出高昂的代价。

(21). Chemical engineers are not really concerned with all these microscopic effects for their own sake, but want bulk results.

化学工程师们并不从探索微观效应本身去考虑问题，而是需要总体效应。

(22). However they need some understanding of what is occurring at a microscopic level

不过他们需要在一定的微观层次上了解所发生的现象

(23). Because the rate at which the desired products are produced depends on both the rates of the chemical reactions involved, and any microscopic transportation effects to and from the reaction site.

因为目标产物的生成速率既取决于所发生的化学反应速率也取决于到达和离开反应活性点的微观传递效应。

(24). The transport effects can often be estimated by using standard principles. Unfortunately, not so with the chemical reaction rate. Current theory cannot adequately predict these, so they must be determined by experiments.

传递的影响常常可以使用标准的方法估算。遗憾的是，反应速率却不能这样。目前理论尚不能预测，而只有靠实验确定。

(25). This study of chemical reaction rates is called "chemical kinetics". Once the rate has been obtained, the full scale reactor can be designed.

对化学反应速率的研究称作"化学动力学"。一旦知道了反应速率，实际规模的反应器就可以设计出来了。

(26). The origins of chemical kinetics date back to the nineteenth century and Wilhelmy’ s observations of reaction rates.

化学动力学数据研究的起源可以追溯到19世纪威海姆对反应速率的观察。

(27). Arrhenius later developed his theories about reactions, coining the famous equation: k = ae-E/RT which shows the temperature dependence of the rate constant.

后来阿累尼乌斯发展了化学反应理论，创立了有名的方程式:K=ae-E/RT这个方程表达了反应速率常数对温度的依赖关系。

(28). What do a landing plane, a baking cake, a cooling tower and sweetened tea have in common? They all involve a transfer of momentum, heat or mass.

一架着陆的飞机、一个正在烘烤之中的糕点、一座冷却塔和一杯加糖的茶，它们都有什么共同点?它们全都包含有动量、热量和质量传递。

(29). As a plane lands, it’s momentum is transferred to the air around it, a baking cake has heat transferred to it by oven, sweetened tea contains sugar that has dissolved, which is mass transfer

当飞机着陆时，它的动量传递给它周围的空气，烘烤的糕点由烤炉把热量传给它;加糖的茶里糖已经溶化，这就是传质

(30). In a cooling tower, all three effects occur as evaporation takes place and the moisture is carried up the tower.

在一个冷却塔里，当发生蒸发而且水分被带上塔顶时，所有这三个作用都出现了。

(31). As you read this book you are certainly involved in all three processes. as you turn each page, you execute momentum transfer.

当你阅读这本书的时候，你也肯定参与所有这三个过程。

(32). Some of your kinetic energy has caused the page to accelerate from rest and to flip over.

当你翻开每一页书时，你在进行动量传递。你的动能有一部分引起书页加速，从静止到翻转。

(33). The principles describing momentum transfer can be used in applications as diverse as analysing fluid flows to designing the space shuttle.

描述动量传递的原理，可以被广泛地应用于从分析流体流动到设计宇宙飞船的各种不同的场合。

(34). When you take a breath, air is sucked into your lungs and oxygen diffuses across into your bloodstream. This is mass transfer in action.

当你呼吸的时候，空气吸进你的肺而氧气扩散进入你的血流。这就是传质在起作用。

(35). Momentum and heat transfer are of concern in many branches of engineering, but mass transfer is traditionally the domain of the chemical engineer.

动量和热量传递与许多工程分支有关，而质量传递传统上是化学工程师的主项。

(36). Many important chemical engineering applications involve mass transfer, distillation for example, surely one of the most economically important processes.

很多重要的化学工程的实用场合包含着质量传递，例如精馏，无疑是一个具有十分重要的经济意义的过程。....(please sign in for more)

(37). While you read, your body is constantly having to produce heat to keep you warm, because that heat is being transferred away from you, either by conduction through your chair, convection due to the movement of air around you, or by radiation.

你阅读的时候，你的身体必须不断地产生热量使你保持暖和，因为热量在不断地从你传出去，或者是通过你的座椅传导,或者是由于你身边的空气对流．或者是辐射。....(please sign in for more)

(38). Heat transfer is important from a planetary scale in issues such as global warming, to more domestic concerns, freezing garden peas for example.

热量传递无论在星球的规模上，比如全球变暖问题，或者是在许多家政琐事上，比如冰冷豆荚，都是很重要的。....(please sign in for more)

(39). Almost all chemical systems involve heat transfer at some stage, especially in heat exchangers. as these examples illustrate, transfer principles describe much of what goes on around us.

几乎所有化工系统都在某个阶段包含着热量传递，尤其是在换热器中。这些例子表明,传递原理描述了发生在我们身边的许多现象。....(please sign in for more)

(40). Mathematicians have developed many algorithms to help in the quest, including New-ton-Raphson and Muller search methods.

数学家们发展了许多算法来帮助求解，包括牛顿一辛普森法和米勒搜索法。....(please sign in for more)

(41). To conduct these searches by hand, through multidimensional terrain would be extremely time consuming, and so of course computers are used to speed our progress.

用手工作这种搜索，完成多维域的寻优相当费时，理所当然该用计算机来加速这一过程。....(please sign in for more)

(42). Many chemical processes require solids to be removed from liquid or gases and filtration is often the method used. In fact a significant part of what chemical engineers do is to design separation systems.

有许多化学工艺，常常使用过滤的方法从液体或气体中分离出固体颗粒，其实化学工程师的工作，相当大的一部分就是设计分离系统。....(please sign in for more)

(43). They underlie the "unit operations" and are therefore extremely useful to chemical engineers for successful equipment design, especially with the current movement away from empirical design to a more fundamental, analytical approach.

它们支撑着"单元操作"，因此对化学工程师成功地设计设备非常有用，尤其是现在正处于从经验设计方法向更加基础的、分析性的方法转移的潮流之中。....(please sign in for more)

(44). Such design relies on accurate models of these transfer effects.

这样的设计方法依赖于对传递现象的精确的模型描述。....(please sign in for more)

(45). An important goal in this design process is maximizing the amount of transfer. In equation form: amount of Momentum, Heat or Mass. Transferred = Driving Force / Resistance

在这种设计方法中，一个重要的目标是使传递的量最大，以方程表示:动量、热量或质量的传递量=推动力/阻力....(please sign in for more)

(46). We can see that to do this, the chemical engineer must maximize the driving force, which is the difference in concentration of momentum, heat or mass between two points, or minimize the resistance of the system to transfer.

这样,我们可以看到，化学工程师必须使推动力最大，也就是两点之间的动量、热量和质量浓度之差最大;或者使系统对传递的阻力最小。....(please sign in for more)

(47). Building a multi-million dollar chemical plant is a big financial risk. What if it does’ work? To avoid this situation, companies usually test parts of the process beforehand.

花数百万美元修建一个化工厂是一个很大的经济风险。万一它不行怎么办?为了避免这种情况，公司通常要事先对生产过程进行分部试验。....(please sign in for more)

(48). They seek to use the data obtained to improve the design of the full scale plant, or confirm it should work. This is called scale-up.

它们试图利用所获得的数据来改进工厂规模的设计，或者证明该设计可行。这就叫放大。....(please sign in for more)

(49). The amount that a process is scaled up is called the scale-up factor. The smaller the factor the smaller the risk, because the smaller scale test is nearer the size of the full scale version.

过程被放大的倍数叫放大系数。放大系数越小，风险越小，因为这种情况下小规模试验的尺寸已经更加接近实际规模。....(please sign in for more)

(50). In the mid 1940s the process to produce uranium-235 was scaled up from lab to plant with a scale-up factor of 1061.Obviously this is a big risk, but so were the perceived returns.

40年代中期，生产U-235的工艺从实验室规模到工厂规模的放大系数是1061显然这是个大冒险，不过也收到了大回报。....(please sign in for more)

(51). Catalytic reaction on an industrial scale is a good example of the uses of scale-up. Small-scale catalyst reactors can be tested thoroughly and the kinetic rate data analyzed to provide the intrinsic reaction rate.

工业规模的催化反应是利用放大的一个好例子。可以对小规模的催化反应器进行透彻的研究并分析动力学速率数据来求得本征反应速率。....(please sign in for more)

(52). This should be independent of scale, so this information can be used to help design the full scale reactor.

这与规模大小无关，所以这些信息可用于实际规模的反应器设计。....(please sign in for more)

(53). A very useful tool for scale-up is the dimensionless group. This is the grouping of system variables so as to cancel out their dimensions.

在放大中使用的一个很有用的工具是无量纲数群。这是系统变量无因次化的一种组合。....(please sign in for more)

(54). Reynolds number (Re)for example describes the flow of a fluid in a pipe. For a particular design Re should always, in theory, be the same, whatever the scale, if designed correctly.

例如，雷诺数(Re)描述流体在管道中的流动，针对某个特定的设计，不管规模大小，如果设计正确的话，Re总应该是相同的。....(please sign in for more)

(55). Scale-up is always an approximation, because ultimately molecules cannot be scaled. also it has been shown to be almost impossible to keep a system’s Reynolds and Fraud numbers constant when the equipment dimensions change.

放大只能说是近似的，因为说到底分子总不可能放大。当设备尺寸改变时．要严格保持系统的雷诺数与弗鲁德数为常数也几乎是不可能的。....(please sign in for more)

(56). "To boldly go where no-one has gone before! ", the famous phrase from america’s science fiction series "Star Trek", is apt to describe process optimisation. Like Captain Kirk, designers must make journeys through hyperspace to find solutions.

"勇敢地去无人去过的地方吧!"用美国科幻连续剧"星际旅行"中的这句名言来描述过程优化是十分贴切的。就像科克船长一样，设计者们必须在多维空间漫游去寻求问题的解答。....(please sign in for more)

(57). However, as we shall see, designers can do all this with the aid of a pen, paper and computer, from the comfort of their design office, without ever leaving Earth’s atmosphere.

不过你将看见，在笔、纸和计算机的帮助下，设计者们不用离开地球大气层，在自己舒适的办公室里就可以办到这一切。....(please sign in for more)

(58). optimization is the process of searching for the best solution from among a large or even infinite number of possible solutions.

优化是从大量的、甚至无穷的可能解中搜索最佳方案的过程。....(please sign in for more)

(59). Many chemical engineers feel that optimising existing plants will become the chemical industry’ s focus, rather than expanding them.

许多化学工程师们认为，化学工业的发展焦点在于使现有工厂最优化，而不在扩大规模。....(please sign in for more)

(60). Optimising a process can provide a cleaner, cheaper and more efficient process. For example an inefficient boiler may waste, much heat, due to poor insulation.

最优化为的是获得一个更洁净、更经济和更高效的过程。例如，一个效率不高的锅炉，绝热不良会浪费很多热量。....(please sign in for more)

(61). Too much insulation, on the other hand,, would be costly, and not provide much more effectiveness. This is a classic type of optimization problem, balancing capital and operating costs.

另一方面，过度绝热，花费很大而且并不能大大提高效率。这就是在投资与操作费用之间求平衡的一个典型的优化问题。....(please sign in for more)

(62). The previous problem could be represented as a line graph using two axis, and the total cost would reach a minimum at some point, showing us the optimum insulation thickness.

这个问题可以用二维座标曲线图描述，某点处总的花费将达最小值，由此告诉我们最佳的绝热层厚度。....(please sign in for more)

(63). A problem with three variables could be represented using a 3-D graph, but if 4 or more are used then we can no longer physically represent it.

有3个变量的问题则用三维图形表达，然而假如有4个或者更多的变量，我们再也不能形象地表达。....(please sign in for more)

(64). To design an optimum shell and tube heat exchanger, there are many variables including pressure, diameter, length and baffle spacing, resulting in a very complex problem.

要设计一个最佳化的管壳式换热器，包含许多变量，如压力、直径、长度和折流板间距,结果使问题非常复杂。....(please sign in for more)

(65). The concept of hyperspace is used to imagine these solutions.

多维空间的概念就是用来推测这些问题的解。....(please sign in for more)

(66). A multi-dimensional space of possible solutions, bounded by the constraints we have defined, contains our optimum solution, but finding it may be another matter!

由可能的解构成的多维空间，以我们定义的限制条件为边界，肯定包含着我们所要求的最佳解答，但要把它找出来又是另一回事了!....(please sign in for more)

(67). Software such as Excel, a spreadsheet program, contain built-in search facilities allowing us to specify constraints such as "insulation thickness ＞0". They will then attempt to find an optimum solution to our problem.

像Exod这样的可扩展表格程序软件，内部已经设有搜索功能，并且允许我们设立限制条件．比如"绝热层厚度>O"，然后软件就会为我们找出问题的最佳答案。....(please sign in for more)

(68). For big problems such as flight scheduling, new algorithms are developing, cutting computing times dramatically, but of course these are highly proprietary information. As usual, "these are the voyages of the starship, Enterprise", as Captain Kirk would say.

针对一些大型问题，比如飞行计划，正在发展新的算法，可以大大减少计算时问．当然这些信息是高度产权化的。就像科克船长会说的那样，"这就是宇宙飞船--企业号的航向。"....(please sign in for more)

(69). Imagine universities offering courses in bitumen engineering, sulphuric acid engineering or even tea engineering. Such courses would be highly effective at producing engineers capable of working in a specific profession

设想大学里开设渣油工程，硫酸工程或者甚至茶叶工程课，这些课程对培养能胜任某一专业的工程师是很有效的....(please sign in for more)

(70). But these engineers would be ill-equipped to work in any other area. also, the range of courses taught would be unfeasibly large.

但是若要他们在任何别的领域工作，就显得训练很不够了。另外，这样安排的课程，范围会大得难以实施。....(please sign in for more)

(71). It was recognised in the early part of this century that there are processes in these systems that share the same basic principles, although they may be applied slightly differently.

本世纪早期人们认识到这些不同体系中的一些过程，尽管具体应用上或多或少有些差别，但却具有基本相同的原理。....(please sign in for more)

(72). For example, both the food and pharmaceutical industries dry some of their products, so "drying" can be taught instead of each individual process. Other examples include filtration, distillation and crystallization.

例如，食品工业和医药工作都有产品干燥，这样就以"干燥"而不是以某一个过程作为课程。还有类似的例子，包括过滤、蒸馏和结晶。....(please sign in for more)

(73). Using this approach, complex processes can be broken down into generic steps: "unit operations". a dramatic example of the successful application of this principle can be seen in the american Second World War effort.

使用这个办法，可以把各种复杂的工艺分解成一些基本的步骤，即:单元操作。二次世界大战中，美国做了一个尝试，应用这个方法大获成功。....(please sign in for more)

(74). Penicillin was being produced in a highly inefficient batch process, until a company (Shell Development)stepped in and applied their knowledge of unit operations. Within a year and a half, 60 times more soldiers could be treated!

在那以前，青霉素的生产使用的是效率很低的间歇方法，直到Shell发展公司介入并且使用他们的单元操作方法。此后1年半之内，青霉素救活士兵的数目增加了60多倍。....(please sign in for more)

(75). The unit operations approach has led to chemical engineers able to apply their knowledge in a variety of industries. This flexibility is becoming increasingly more important as people change their jobs more and more frequently.

单元操作方法使化学工程师们可以在各种各样的领域施展才能，尤其在人们越来越频繁地改变工作的今天，这个灵活性变得越来越重要。....(please sign in for more)

(76). Imagine London as it once was,plague ridden, with sewage flowing in the streets．The development of it’s sewer system in the nineteenth century brought substantial improvements to the health of it’s citizens．

想想过去的伦敦，一度瘟疫流行，大街上流淌着污水。19世纪由于排污系统的改善，才给它的市民带来了健康状况的明显好转。....(please sign in for more)

(77). In recent years London has had another problem,that of increased water demand．To combat this,major water supply projects have been undertaken to enable a rapid response to increased local demand．

而近年来．伦敦又遇到了另一个问题--不断增长的供水要求。对付这个问题，投入了若干大型的供水工程来对当地增长的要求作出迅速反应。....(please sign in for more)

(78). As we can see,to transport fluid from a to B is a basic human need,be it drawing water by bucket from wells in the Sahara Desert or pumping natural gas ashore from a gas drilling rig in the North Sea．

正如我们看到的,把流体从a送到B是人类的一个基本要求，就像在撒哈拉沙漠里用水桶把水从井里提出来以及从北海的天然气井台把气输送到岸上。....(please sign in for more)

(79). The chemical industry generally transports fluids continuously in pipes or open channels or in batches by road,rail or marine tankers,some of which can be vast,weighing up to half a million tons．

在化学工业，通常是在管道或明渠中输送流体，或者由公路、铁路和油轮间歇输送．它们有些会很大，重达50万吨。....(please sign in for more)

(80). However,this can cause many problems．In 1 996 the ship,The Sea Empress,ran aground spilling an estimated 70,000 tonnes of oil which has contaminated much valuable natural Welsh coastline.

可是，这会引起很多问题。1996年，海洋皇后号油轮搁浅．据估计泄漏了70，000吨原油，严重污染了拥有许多宝贵自然资源的威尔士海岸线。....(please sign in for more)

(81). Another process basic to human need is mixing, for example kneading dough for bread, surely a process used in almost every civilization in known history, and mentioned as early as Genesis in the Bible.

另一个与人类基本要求有关的过程是混合，例如做面包就要和面。显然这是一个人类有史以来在每一个文明世界都要用到的过程，而且早在<圣经>的<创世纪>一卷中即已提及。....(please sign in for more)

(82). Beyond cooking, almost all production processes involve a mixing stage as well.

除了烹调，几乎所有的生产过程都要包括一个混合阶段。....(please sign in for more)

(83). In industry almost anything may be required to be mixed with anything else, and for a variety of reasons, including obtaining a homogenous product, transferring heat or suspending a solid.

工业上，也许要求任何一种东西与别的一种东西混合，这样做的理由有许多，包括获得一种均匀的产品，传递热量或者使一种固体粒子悬浮。....(please sign in for more)

(84). There are many different types of industrial mixers available, but they can be classified in two main categories: static and dynamic mixers.

有多种可用于工业的混合器，但它们可以被分为两大类:静态和动态混合器。....(please sign in for more)

(85). The classical dynamic mixer is simply a turbine or paddle rotating in a vessel. Static mixers are obstructions in a flowing fluid which break it up, causing it to become mixed.

传统的动态混合器就是一个涡轮或浆，在一个容器中旋转。静态混合器是流动流体中的障碍物，使流体分开，引起混合。....(please sign in for more)

(86). Micro-machined static mixers only 22mm2, etched from silicon wafers, can be used for small chemical sensors.

微型加工的静态混合器只有22mm2大，由硅片刻蚀而来，可用于小型化学传感器。....(please sign in for more)

(87). Mixer selection depends largely on the economics of the situation and the fluid’s characteristics, especially it’ s viscosity.

混合器的选择很大程度上取决于过程的经济性和流体的特性，尤其是粘度。....(please sign in for more)

(88). I remember at university we did a lab experiment using ultra-filtration. That could filter microscopic things, even viruses, hence the name "ultra".

记得在大学时做过一个超滤实验，很小的东西，甚至就连病毒都可以滤掉，这就叫"超"。....(please sign in for more)

(89). Other separation processes are distillation, dust extraction, decanting, leaching

别的分离过程有精馏、捕尘、倾析、浸取..........(please sign in for more)

(90). (Interrupting)Leaching! What on earth is that! ? You don’t use real leaches do you?

吸血!(注:英文中浸取leaching与吸血leeching同音)你说的到底是什么?你们不会真用吸血的水蛭，对吧?....(please sign in for more)

(91). It’s the process of extracting a soluble component from a solid by passing a suitable solvent over it. For example the sugar industry uses it to remove sugar from sugar beet.

我们说的浸取是指用某种合适的溶剂从固体中萃取可溶成分的方法，比如制糖工业从甜菜中提取糖就是用的这种方法。....(please sign in for more)

(92). Have you seen those new vacuum cleaners that don’t need a bag? How do they work?

你见过不要过滤器的新型真空吸尘器吗?它们是怎样工作的呢?....(please sign in for more)

(93). I saw it on television a while ago. They use what’s called a "cyclone".

不久前电视上见过，它们使用"旋风分离器"。....(please sign in for more)

(94). The air is spun around in a cylinder, throwing the dust out to the side, where it falls down to be collected, leaving fairly clean air to leave through the top.

空气绕着一个圆筒旋转，灰尘被甩到边上顺筒壁往下掉就被捕集了，而高度净化的空气从上部离开分离器。....(please sign in for more)

(95). Cyclones have been used in industry for a long time to remove dust from gases before they are vented.

工业上输气之前用旋风分离器除尘，已经用了很久了。....(please sign in for more)

(96). Decanting you might use in cookery to separate two liquids like draining the fat from the top of a cooking mixture.

烹调的时候你也许会用到倾析来把两种液体分开，比如把煮的东西上面的一层油去掉。....(please sign in for more)

(97). I knew whisky is distilled. You say "pure", but what is the difference between purification and separation?

我知道威士忌是蒸馏来的。你刚才说"纯"，提纯和分离有什么不同呢?....(please sign in for more)

(98). Purification is merely separating components from a mixture until there is almost only one component left. Separation to a limit as it was.

提纯只不过是从混合物中把各组分分开，最后只剩下单一组分。似乎可以说提纯是分离的极限。....(please sign in for more)

(99). Tourists are sometimes disappointed when visiting historic buildings or landmark like Big Ben in London, to find it covered by a cage of scaffolding and polythene sheeting.

当旅游者参观历史建筑物或纪念碑，比如伦敦大笨钟，而却看见它被脚手架笼子或聚乙烯网子罩住时，会大失所望。....(please sign in for more)

(100). SO2 in the atmosphere causing acid rain, has caused much corrosion of the detail of such buildings. One way to clean chemical factory emissions of SO2 is to absorb it using lime.

大气中的S02引起的酸雨，已经造成了这些建筑物细致部分的严重腐蚀。清除化工厂排放的S02，一个方法是使用石灰(水)吸收。....(please sign in for more)