Unit 1 Chemical Industry
化学工业
1.Origins of the Chemical Industry
Although the use of chemicals dates back to the ancient civilizations, the evolution of what we know as the modern chemical industry started much more recently.
Since 1940 the chemical industry has grown at a remarkable rate,
The chemical industry today is a very diverse sector of manufacturing industry, within which it plays a central role.
2. Definition of the Chemical Industry
At the turn of the century there would have been little difficulty in defining what constituted the chemical industry since only a very limited range of products was manufactured and these were clearly chemicals
It is therefore apparent that, because of its diversity of operations and close links in many areas with other industries, there is no simple definition of the chemical industry.
3. The Need for Chemical Industry
The chemical industry is concerned with converting raw materials, such as crude oil, firstly into chemical intermediates and then into a tremendous variety of other chemicals. It may seem strange in textbook this one to pose the question “do we need a chemical industry?” However trying to answer this question will provide(ⅰ) an indication of the range of the chemical industry?s activities, (ⅱ) its influence on our lives in everyday terms, and (ⅲ) how great is society?s need for a chemical industry. Our approach in answering the question will be to consider the industry?s co ntribution to meeting and satisfying our major needs. What are these? Clearly food (and drink) and health are paramount. Other which we shall consider in their turn are clothing and (briefly) shelter, leisure and transport.
(1) Food. (2) Health. (3) Clothing.
Parallel developments in the discovery of modern synthetic dyes and the technology to “bond” them to the fiber has resulted in a tremendous increase in the variety of colors available to the fashion designer.
Other major advances in this sphere have been in color-fastness, i.e., resistance to the dye being washed out when the garment is cleaned.
(4) Shelter, leisure and transport. In terms of shelter the contribution of modern synthetic polymers has been substantial.
Plastics and polymers have made a considerable impact on leisure activities with applications ranging from all-weather artificial surfaces for athletic tracks, football pitches and tennis courts to nylon strings for racquets and items like golf balls and footballs made entirely from synthetic materials.
Likewise the chemical industry?s contribution to transport over the years has led to major
improvements.
So it is quite apparent even from a brief look at the chemical industry?s contribution to meeting our major needs that life in the world would be very different without the products of the industry.
4. Research and Development (R&D) in Chemical Industries
One of the main reasons for the rapid growth of the chemical industry in the developed world has been its great commitment to, and investment in research and development (R&D).
The chemical industry is a very high technology industry which takes full advantage of the latest advances in electronics and engineering.
Individual manufacturing plants have capacities ranging from just a few tones per year in the fine chemicals area to the real giants in the fertilizer and petrochemical sectors which range up to 500,000 tonnes.
The major chemical companies are truly multinational and operate their sales and marketing activities in most of the countries of the world, and they also have manufacturing units in a number of countries.
Unit 2 Research and Development
研究和开发
Research and development, or R&D as it is commonly referred to, is an activity which is carried out by all sectors of manufacturing industry but its extent varies considerably, as we will see shortly.
1.Fundamental Research and Applied Research
In industry the primary reason for carting out R&D is economic and is to strengthen and improve the company?s position and profit ability.
We can pick out a number of areas of R&D activity in the following paragraphs but if we were to start with those which were to spring to the mind of the academic,
Fundamental research is typically associated with university research. It may be carried out for its own intrinsic interest and it will add to the total knowledge base but no immediate applications of it in the “real world” well be apparent.
Aspects of synthesis could involve either developing new, more specific reagents for controlling particular functional group interconversions, i.e.
2.Note, however, that there has been a major change in recent years as academic
institutions have increasingly turned to industry for research funding,
3.Types of Industrial Research and Development
The applied or more targeted type of research and development commonly carried out in industry can be of several types and we will briefly consider each. They are:
(1)Product development. Product development includes not only the discovery and development of a new drug but also, for example, providing a new longer-active anti-oxidant additive to an automobile engine oil.
(2) Process development. Process development covers not only developing a manufacturing process for an entirely new product but also a new process or route for an existing product.
The ability of penicillin to prevent the onset of septicemia in battle wounds during the Second World War (1939～1945) resulted in an enormous demand for it to be produced in quantity.
Process development for a new product depends on things such as the scale on which it is to be manufactured, the by-products formed and their removal/recovery, and required purity. Data will be acquired during this development stage using semi-technical plant (up to 100 liters capacity)
Note that by-products can has a major influence on the economics of a chemical process. Phenol manufacture provides a striking example of this.
A major part of the process development activity for a mew plant is to minimize, or ideally prevent by designing out, waste production and hence possible pollution. The economic and environmental advantages of this are obvious.
Finally it should be noted that process development requires a big team effort between chemists, chemical engineers, and electrical and mechanical engineers to be successful.
（3) Process improvement. Process improvement relates to processes which are already operating. It may be a problem that has arisen and stopped production. In this situation there is a lot of pressure to find a solution as soon as possible so that productio n can restart, since …down time? costs money.
down time: 故障期
More commonly, however, process improvement will be directed at improving the profitability of the process.
In recent years, however, the most important process improvement activity has been to reduce the environmental impact of the process, i.e.,
Note, however, with a plant which has already been built and is operating there are usually only very limited physical changes which can be made to the plant to achieve the above aims. Hence the importance
(4) Applications development. Clearly the discovery of new applications or uses for a product can increase or prolong its profitability.
Emphasis has already been placed on the fact that chemicals are usually purchased for the effect, or particular use, or application which they have.
3.Variations in R&D Activities across the Chemical Industry
Both the nature and amount of R&D carried out varies significantly across the various sectors of the chemical industry.
At the other end of the scale lie pharmaceuticals and pesticides (or plant protection products). Here there are immense and continuous efforts to synthesize new molecules which exert the desired,
Unit 3 Typical Activities of Chemical Engineers
化学工程师的例行工作
The classical role of the chemical engineer is to take the discoveries made by the chemist in the laboratory and develop them into money--making
By contrast, the chemical engineer typically works with much larger quantities of material and with very large (and expensive) equipment. Reactors can hold 1,000 gallons to 10,000 gallons or more.
The chemical engineer is often involved in “scaling up” a chemist-developed small-scale reactor and separation system to a very large commercial plant.
The chemical engineer must also work closely with mechanical, electrical, civil, and metallurgical engineers in order to design and operate the physical equipment in a plant--the reactors,
1.To commercialize the laboratory chemistry, the chemical engineer is involved in
development, design, construction, operation, sales, and research.
2.Development
Development is the intermediate step required in passing from a laboratory-size process to a commercial-size process.
The chemical engineer works with the chemist and a team of other engineers to design, construct,
Once the pilot plant is operational, performance and optimization data can be obtained in order to evaluate the process from an economic point of view.
3.The pilot plant offers the opportunity to evaluate materials of construction, measurement
techniques, and process control strategies.
4.Design
Based on the experience and data obtained in the laboratory and the pilot plant, a team of engineers is assembled to design the commercial plant.
The design stage is really where the big bucks are spent. One typical chemical process might require a capital investment of $50 to $100 million.
The product of the design stage is a lot of paper:
(1) Flow sheets are diagrams showing all the equipment schematically, with all streams labeled and their conditions specified (flow rate, temperature, pressure, composition, viscosity,
density, etc.)
(2) P and I (Piping and Instrumentation) Drawings are drawings showing all pieces of equipment (including sizes, nozzle locations, and materials), all piping (including sizes, materials, and valves),
5.(3) Equipment specification Sheets are sheets of detailed information on all the
equipment precise dimensions, performance criteria, materials of construction, corrosion allowances, operating temperatures,
6.Construction
After the equipment manufacturers (vendors) have built the individual pieces of equipment, the pieces are shipped to the plant site (sometimes a challenging job of logistics, particularly for large vessels like distillation columns).
After these initial activities, the major pieces of equipment and the steel superstructure are erected.
This is usually a very exciting and rewarding time for most engineers. You are seeing your ideas being translated from paper into reality.
Once the check-out phase is complete, “startup” begins. Startup is the initial commissioning of the plant.
The startup period can require a few days or a few moths, depending on the newness of the technology, the complexity of the process, and quality of the engineering that has gone into the design.
The engineers are usually on shift work during the startup period. There is a lot to learn in a short time period
7.Manufacturing
Chemical engineers occupy a central position in manufacturing. (or “operations” or “production,”
Chemical engineers study ways to reduce operating costs by saving energy, cutting raw material consumption, and reducing production of off-specification products that require reprocessing.
In addition to serving in plant technical service, many engineers have jobs as operating supervisors.
8.Technical sales
Many chemical engineers find stimulating and profitable careers in technical sales. As with other sales positions,
The marketing of many chemicals requires a considerable amount of interaction between engineers in the company producing the chemical and engineers in the company using the chemical
When the sales engineer discovers problems that cannot be handled with confidence, he or she must be able to call on the expertise of specialists
9.Research
Chemical engineers are engaged in many types of research. They work with the chemist in developing new or improved products.
Research engineers are likely to be found in laboratories or at desks working on problems. They usually work as members of a team of scientists and engineers.
Unit 4 Sources of chemicals
化学物质的来源
化学物质的数量多得惊人，其差异很大：所知道的化学物质的数量就达上千万种。如此的数量与理论
上可能形成的含碳化合物的数量相比，相形见绌。含碳化合物的数量之大是耦合的结果：即相对较强的碳
碳共价键的碳原子长链和异构体的形成。大部分这些化合物只是满足实验室好奇心或学术兴趣。然而，其
他剩余的达几千种，是商业和实践兴趣。因此，可以预料到这些化学物质的来源很广。虽然对无机化学品
如此，但是奇怪的是，大多数有机化学品来源于一种资源，即原油（石油）。
1. 无机化学品
Table1-1 无机化学品的主要来源
因为“无机化学品”这个词（术语）涉及到（cover，包括、涵盖）的是除碳以外所有元素构成的化合物。
其来源的多样性并不很大（见表1-1）。一些较重要的来源是金属矿（包括重要的金属铁和铝）以及盐和海
水（用于生产氯、钠、氢氧化钠和碳酸钠）。在这些情况下，至少两种不同的元素化合以一种稳定的化合
物在一起。因此，如果要得到单个元素（也就是金属），那么提取过程除了纯物理的分离方法以外，还必
须涉及到化学处理（过程）。金属矿或无机矿很少以纯物质的形式存在，因此，处理过程的第一步通常是：
（将无机矿中）从不要的固体如粘土或沙石中分离出来。固体筛分后经压碎和研磨，利用颗粒尺寸差异可
以完成一些物理分离。下一步骤则取决于所需矿物的本质及其特征。例如，铁矿常在磁分离器利用他们的
磁性加以分离。泡沫浮选是另一种广泛应用的分离技术。在该技术中，所需要的矿物，以细小颗粒形式存
在，借助被水溶液润湿能力的差异而与其他矿物加以分离。常加入表面活性剂（抗润湿剂），这些典型的
分子，一头为非极性部分（如长碳氢链），另一头为极性部分（如-NH2）。该极性基团与矿物相吸，形成不
牢固的键；而碳氢基团与水相斥而阻止矿物被润湿，因而矿物能浮选。相反，其他固体物质很容易被润湿
而沉在水溶液中。搅拌溶液或液体中鼓泡以产生泡沫能大大促进表面活性剂包裹的矿物的漂浮，这些矿物
从容器中溢出到收集容器中，在收集容器，矿物得到回收。显然，该过程成功的关键在于，为所处理矿物
选择一种高选择的特定的表面活性剂。
2 有机化合物
相比于无机化学品来自于众多不同的资源（这一点我们已经明白了），商业上的一些重要的有机化合
物基本上来源单一。如今，所有有机化合物的99%以上，可以通过石化工艺过程从原油（石油）和天然气
得到。这是一种有趣的情形——该情形一直在改变，而且将来也会变化，因为从技术上讲，相同的化学品
可以从其他原料得到。尤其是脂肪族化合物，可以通过由碳水化合物的发酵所得的乙醇加以生产，另一方
面，芳香族化合物可以从煤焦油中分离得到。煤焦油是煤炭化工过程的副产物。动植物油脂，是为数不多
的脂肪族化合物的特定的资源，这些脂肪族化合物包括长链脂肪酸（如正十八酸）和长链醇（如正十二烷
醇）。
化石燃料（即石油、天然气和煤）的形成要花上百万年，一旦用掉就不能被替换，因此，它们称之为
不可再生的资源。这与来自于植物的碳水化合物恰恰相反，碳水化合物能够较快被更新。一种较为普遍应
用的资源为蔗糖——一旦作物被收割和土地被清理，又可以种植和收割新的作物，通常少于一年。因此，碳氢化合物可称为可再生资源。据估计，植物原料（干重）的总的年产量为1*1011 吨。化石燃料－天然气、原油和煤，主要用作为能源，而不是作为有机化合物的资源。例如，各种石油分馏物的气体，用于家用烹调和取暖、用作为汽车用的汽油、加热建筑物重燃油，或用于在工业处理以产生
的蒸汽。通常，一桶原油的8%用于化学品的生产。下列数据可以说明，为什么化学工业在原油的使用方
面与燃料或能源消耗的工业展开着竞争。
显然，若我们愿意使用可代替化石燃料的其他能源，那么这些可替代能源可以利用的，同时，我们自
信地预料到在不久的将来，可以用上其他的可替代能源。因此，有必要要去保存宝贵的石油供应以用于化
学品的生产。“处理石油的最后一件事情是将之燃烧”该说法是有根据的。注意到这件事很有趣且有益的：
早在1894 年门捷列夫（发现元素周期表之俄国科学家）就向当局报道，“石油是太宝贵的资源而不能将之
燃烧掉，应该将之以化学品资源加以保存。”
来自于碳水化合物（植物茎杆）的有机化学物质，职务的主要成分是碳水化合物，碳水化合物组成职
务的结构。它们为多糖（如纤维素和淀粉），大量的淀粉存在于食物（如谷类、大米和马铃薯）之中，纤
维素是组成细胞壁的主要物质，因而广泛存在，可以从木材、棉花等中得到。因此，来自于碳水化合物的
化学品的潜力是相当大的，而且该原料可再生。
从碳水化合物得到化学物质的主要途径是通过发酵过程。然而发酵过程不能利用多糖（如维素和淀
粉），因此，淀粉必须先收到酸性或酶水解反应生成更简单的糖类（单糖或二糖（如蔗糖），这些较为简单
的糖是发酵过程中的）合适的起始原料。
发酵过程是利用单细胞的微生物（一般有酵母菌、真菌、细菌或霉菌）生产特殊化学品。有些发酵农
家已用了上千年。最著名的例子为，谷物发酵生产含酒精的饮料。直到1950 年，该方法才成为生产脂肪
族有机化学品的最普遍的途径。因为生产的乙醇脱水生成乙烯，而乙烯是合成大量脂肪族化合物的关键中
间体。尽管用此方法生产的化学品有所减少，但是用这种方法生产汽车燃料方面存在大量的兴趣。
反映在发酵过程的缺点可分为两方面（1）原料（2）发酵过程。因为植物茎杆是一种农业原料，其生
产和收割均为劳动力密集型的过程，所以相比之，它的原料费用高于原油的费用。同时，物料的运输更困
难，费用更高。与石化处理过程相比，发酵过程的主要缺点是：其一，时间通常要好几天，相比有些催化
石油反应只要几秒；其二，所得的产物通常是以稀的水溶液（浓度<10%）存在，因此，分离和纯化费用
较高。因为微生物是活的体系，过程的条件几乎不容许改变。为了增加反应速度，即使相对于小的温升，独有可能会导致微生物的死亡和发酵过程终止。
另一方面，发酵方法的独特优点是，其选择性高，一些结构复杂而很难以合成或者需要多步合成的化合物，通过发酵很容易制得。著名的实例有多种多样的抗生素的生产。如青霉素，头孢菌素和链霉素。
如果也基因工程中快速发展的过程中大量的实际问题得到解决，那么发酵方面的兴趣存在很大的兴趣。在基因工程中。微生物（如细菌）能定制地生产成所需的化学品。然而，因为发酵反应速度慢和产物
分离费用高，在不久的将来要实现用发酵方法生产大众化学品（即需求量极大的化学品如依稀，笨。）看来是不可能。
来自于动植物油和脂肪的有机化学品，动植物油脂（常指类肪）是由甘油脂组成，甘油酯为三羟基醇，甘油（丙烷-1，2，3-三醇，丙三醇）。有多种不同的种植物油资源，较为普通的有，大豆，谷物，棕树核，油菜籽，橄榄油，动物脂肪和巨鲸。这些油类可通过溶剂萃取分离得到。有相当大的部分，烹调油脂的形式用食品工业中，用于生产黄油，人选黄油和其他食品（如冰激凌）。这些食品的烷基对人的健康的影响，
尤其对血液中的胆固醇的影响，存在着争议。血液中的高胆固醇的含量会引起高血压和心脏
病。目前的观点似乎赞成高含量不饱和的基因在降低胆固醇的水平和降低心脏病（发病率）危险是有利的。这引起如下趋势。不用烹调脂类和普通黄油或人造黄油（这些物质中饱和烷基含量丰富），而转向用烹调油和不饱和烷基的含量高的人造黄油。
类脂属于脂类（物质），用于生产化学物质时，以水解反应开始，虽然水解反应可以用酸或碱催化，
但碱催化效果更好，因为碱催化反应不可逆。碱性条件下的水解反应叫做皂化反应。
注意到这样事实很重要—皂化反应，水解反应（脂肪分解）一级氢解反应不会利用单一甘油酯（或甲
基醇，实际上，所用植物油是各种甘油酯的混合物，因此（水解）产物也是混合物，需要分离。
Unit 5 Basic Chemicals
基本化学品
我们将化学工业部门分成两类，生产量较大的部门和产量较低的部门。在产量高的部门中，各种化学品的年产量达上万吨至几十万吨。结果这样所用的工厂专门生产某一个单个产品。这些工厂的连续方式进行操作，自动化程度高（计算机控制）归类于产量高的部门有硫酸，含磷化合物，含氮化合物，氯碱及其相关化合物，加上石油化学品和商品聚合物（如聚乙烯）（生产部门）。除商品聚合物外，其它的均为重要的中间体，或基本化学品。这些基本化学品是其他许多化学品的生产原料，其他许多基本化学品的需求量很大。
相反，产量低的部门主要从事精细化学品的生产。单个化学品的年产量只有几十吨到几千吨。然而，与高产量的产品相比，这些产品单位重量具有很高的价值。通常，精细化斜坡的生产与间歇方式操作在工厂中，而且这些工厂常进行多种产品的生产。低产量生产部门生产农用化学品，染料，药品和特种聚合物（如聚醚醚酮）。
基础化学品在化学工业中得不到支持，它们不那么引人注意（如药品），有时候利润不很高。其利润来自于经济盛衰时难以预测的周期。
这些基本化学品不被公众注意到和直接使用，因此其重要性常得不到理解。即使在化学工业中，其重要性也得不到足够的重视。然而，如果没有这些基本化学品，其他工业就不复存在。基本化学品处于原料（及那些从地下通过采矿、开采或用泵抽出来的物质）和最终产品的中间位臵。
基本化学品的一个显著的特征就是它们的生产规模，每一种（基本化学品）的生产规模都相当大。图2-1表示在1993 年美国市场上的25 中化学品。（为了使我们了解化学品的分类与生产量有关。）通常，基本化学品生产于那些年产量上万吨的工厂。年产量10 万吨的工厂每小时要生产1.25 吨。基本化学品的另一显著重要的特征是其价格。大多数价格相当便宜。基本化学品工业所作的工作（或任务）是找到经济的途径将原来转变为有用的中间体。生产厂家要对它们的产品收取较高的价格几乎没有余地，因此，那些最低费用生产产品的厂家可能获得的利润最高。这就意味着，厂家就必须不断准备寻求新的，更经济的生产和转变原料的方法。
许多基本化学品为石油精炼的产物，而部分基本化学品工业----硫、氮、磷和氯碱工业是把除C 和H、S 外的元素转变为化学品。总之，这些产品和石化工业的基本产物两者结合起来可生产无数重要的化学物质，这些重要的化学物质可作为其余化学工业的原料。
基本化学工业现在面临着其历史上中最大的挑战之一，该工业中的产品消费部门---农业以停止增长。同时大大减小了对肥料的需求。西方的农场主生产了大多的食物，政府减小了对农
业部门的津贴，结果导致了更少的土地用于耕种和所需的肥料减少。过量肥料的流失而引起的环境的关注也减少了对肥料的需求。
诸如含氯化合物之类的产品，已收到了来自环境学家的压力。根据《关于消耗臭氧层物质的蒙特利尔白皮书》，一些产品将受到禁止。而其它的物质，可以受得住环境学家的压力。基本化学品工业再也不会依靠在需求量方面的长期增长。
为了实现更好的规模经济和某一特殊产品更好的市场地位，厂家相互交换工厂（车间），该工业注重不断合并联合。这使从事某一工业的人员减少，使该工业达到更好的供需平衡和更好的利润。基本化学品工业正逐渐转向为其他化学工业服务，而越来越小地为农业服务。基本化学品受到的压力是许多大规模过程引起的（觉察得到的）较大的环境污染。尽管许多大厂家的生产效率较高，但是该工业要实现最好的环境标准还有很长的路要走。增加重复利用的驱动力和理想化的无排放的工厂，是影响接下来十年该工业发展的主要因素。
技术的进步不会停止，我们将日益重视无污染的工厂和过程。厂家将在效率上展开竞争。那些能以最低的成本生产最高质量产品的厂家将繁荣昌盛。这需要厂家在技术改进方面保持投资。基本化学品的合成有用的中间体的新颖方法将不断被人们发现。
在基本化学品工业中，仍然还有许多工作有待去做。
Unit 6 Chlor-Alkali and Related Processes
氯碱及其相关过程
纵观历史，大众化学品工业在氯碱及其相关过程之上。该部分通常包括氯气、苛性苏打（氢氧化钠）
无水碳酸钠（以各种形式存在的碳酸钠的衍生物），以及以石灰为基础的产品。
自从无水碳酸钠和氢氧化钠的各种制备工艺发现以来，两者在作为碱为主要原料方面相互竞争。电解过程的特殊经济性意味着不管对氯气和氢氧化钠这两种不同类型的产品的相对需求量如何，你只有以固定的比例同时制备氯气和氢氧化钠。这引起了氢氧化钠的价格的摇摆不定，从而使得纯碱作为一种碱或多或
少有利。
氯气苛性苏打和纯碱的生产都取决于廉价易得的原料供应，前者的生产需要廉价的海水和电力的供应，而纯碱的生产需要海水、石灰和大量的能耗。纯碱厂只有在其原料不必要长距离的运输时才能赢利。
这些原料供应利用是影响化工企业位臵分布的一个重要因素。
1. 石灰为基础的产品
一种关键（重要）原料是石灰石。石灰石主要是由CaCO3 组成，高质量的石灰石可直接用于下一步反应。石灰石通常在大型露天石矿中开采，许多采石矿也进行原料的一些处理。从石灰石得到两种重要的产物：生石灰（CaO）和熟石灰水，生石灰是由石灰石根据该反应是热分解
（1200-1500℃）制备得到。
CaCO3 —— > CaO+ CO2
一般的，石灰石经过粉碎加入倾斜旋转窑的较高端，在此发生热分解反应，生石灰在另一端回收。
然而，通常生石灰用于进一步反应而分离，而加入其它化合物，与生石灰在窑的较低口处生成最低产品。
例如，加入铝矿、铁矿和沙石可生成硅酸盐水泥。纯碱的生产，通常要向生石灰加入焦炭，焦炭燃烧生成纯碱所需的CO2，熟石灰由生石灰和水的反应制造，较生石灰更加方便。
大约40%的石灰工业的产品用于钢铁制造业。在钢铁制造业中，纯碱用来与铁矿石中难溶解的硅酸盐反应，生成流态矿渣，矿渣漂浮于表面上，很容易从液态金属中分离，叫少量但重要的石灰工业的产品用于化学品的制造，污染控制和水处理。从石灰石得到的最重要的化学茶品是纯碱。
2. 纯碱
索尔维工艺，该工艺发现于1965 年由ES 优化：工艺是以当含氮的盐溶液经来自于石灰窑中焦炭燃烧产物CO2 碳酸盐反应时，NaHCO3 沉淀析出为基础。NaHCO3 经过滤、干燥、煅烧生成CaCO3。过滤后NH4Cl溶液和熟石灰反应后（溶液体呈碱性）。蒸馏出NH3 在该过程中循环利用，生成物CaCl2 是废弃物或副产物。
对于某一简单的基本产物来说，索尔维法看起来十分复杂。该反应的基本原理是，以NaCl2 和CaCO3为原料生成产物CaCl2 和Na2CO3.然而发生于原料和产物之间的反应并不明显，需要利用NH3 和Ca(OH)2作为中间化合物。
该过程的基本原理为：利用准确的控制组分（尤其是NH3 和NaCl）的浓度，NaHCO3 能够从含NaCl、CO2 和NH3 的溶液里沉淀析出。该过程的关键是控制溶液的酸碱强度和结晶的速度，该工艺的基本路线如
下，NH3 气于氨气吸收器中吸收于事先经纯化的海水中，纯化的海水以减小Ca+、Mg+离子的
量。（Ca+、Mg+在生产过程中易产生沉淀而阻塞管道）。含NaCl 和NH4HCO3 的溶液经吸收了CO2 的吸收塔(CO2 气体量塔
底向上流) 开始时形成(NH4)2CO3 然后再生成NH4HCO3。
在工厂的下面步骤中，Nacl 和NH4HCO3 经复分解反应生成NaHCO3（以沉淀形式形成）和NH4Cl。
过滤将固体NaHCO3 从溶液中分离。将NaHCO3 送至旋转干燥器，在该干燥器中，NaHCO3 失去水和CO2后生成疏松的晶体块（即轻质纯碱）它的主要成分为Na2CO3 蓬松的晶体块很轻，是因为NaHCO3 失去CO2
后，留下很多空隙，而保留原来的晶体形状。通常要得到密度更大的物质很方便，加入水（水能引起咦密度较大的形式重结晶）进一步干燥即可实现。
值得争议的是，上述的化学知识是否为该过程的很好的描述，但这些只是肯定有助于理解过程。想要对此过程有详细的理解，必须要熟悉该组分体系中关于溶度积的很多知识。需要知道的重要知识是，该体
系是复杂体系，为了使该过程高效操作，需要对该过程每部分小心控制。
该过程的一个缺点是：产生的CaCl2 的量很大，其产生量比所需量大得多。因此，大部分CaCl2 只是简单的倒掉（CaCl2 毒性不大），如果能要该过程中的有的进料加以利用，那么该过程是有优势，例如，从该氯化物可产生HCl。
纯碱的用途，有50%的纯碱销往玻璃制造业，因为穿件是玻璃制造过程中的主要原料。因此纯碱工业的财富与玻璃需求量息息相关。纯碱作为一种碱在许多化学过程中与NaOH 存在直接竞争。Na2SO3 是由纯碱和SiO2 在1200-1400℃反应衍生而来的另一类化学物质。硅酸是具有大表面积细小颗粒的Na2SO3，可用于催化剂、色谱之中，洗涤剂和肥皂中作为部分磷酸盐的替代品。
3. 生成Cl2/NaOH 的电解过程
简介，在化学工业法杖是的各个时期，Cl2 和NaOH 两者的需求量均很大，但是不幸的是，对于电化学工厂的操作人员来说，两者的需求量必总是相同。Cl2 可作为漂白粉或作为漂白粉的生产原料，水供应的消毒剂，以及作为塑料和溶解剂知道的原料。苛性钠用于生产纯碱、肥皂和纺织品，以及在多种化学过程中作为一种十分重要的原料。
所有的电解有着共同之处，盐的电解生成Cl2 和NaOH。大多数生产过程是电解（盐的）水溶液，但是有些重要的工厂，电解熔融盐生成Cl2 和液态钠。这些电解熔融盐的过程用用于重要液态Na 的工业。虽
然石油添加剂厂家多种多样，设会出现液态钠的其他用途，但是他的主要是用于生产四烷基铅石油添加剂。
实质上用于水溶液电解过程有三种不同的电解槽：水银槽、隔板槽和膜电解槽。膜电解槽只是用于此案在化工厂中新的生产过程，但是还存在着大量的旧生产过程，尽管说阴曹涉及到对环境的影响，但是许多生产厂家上位法此案膜片电解槽代替水印电解槽的经济性。
所有的电解反应都是以电子作为化学反应的试剂的观点为基础。设水电解过程的基本反应可写成下式：
阳极2Cl—— 2e-→ Cl2
阴极2H2O + 2e—→ H2 + 2OH—
总反应为2Na+ + 2Cl—+ 2H2O→ NaOH + Cl2 + H2
该反应的自由能为正，因此，需要电驱使进行。
像其他许多化学品工艺一样，尽管该反应看起来似乎极其简单，但是有一些方面很复杂。首先，该反应的产物必须分开，如果H2 和Cl2 允许混合在一起，它们会剧烈反应。H2 和Cl2 反应生成HOCl 和氯化物
（两者均会浪费产物、生成副产物）。接着，HOCl 和次氯酸盐反应生成氯酸盐（ClO3 -）、质子和更多的氯化物。OH—在阳极区反应生成能污染Cl2 的O2。所有的这些反应可降低效率和（或）引起分解困难或污染
问题。因此，在产物销售之前，有必要对这些反应清理。理解各种用于电解过程的关键是各种类型的过程分离反应产物的方式。尽管不同的制造商所用的电解槽在细节方面有着多种改变，但是用于盐水的电解过程的电解槽基本可分为以上三类。
4、Cl2 和NaOH 的用途
NaOH 的用途之多，以致很难将它们方便地进行分类。最大的用途之一是用于造纸，造纸业中木材的处理需要强碱。有些国家造纸业中NaOH 的消耗占其产量的20%，另外的20%用于无机化学品（如，次氯酸钠、漂白粉和消毒剂）的生产。各种有机合成约消耗另外的15%，氧化铝和肥皂的生产需要少量的NaOH。
Cl2 广泛用于其它各种产品的生产。在全世界范围内大约有1/4 的Cl2 用于生产氯乙烯（生产PVC 的单体）。1/4 至1/2 的Cl2 用于水的纯化。尽管因为《关于消耗臭氧层物质的蒙特利议定书》多种溶剂正在被
逐步淘汰，但是仍有高达20%的氯气用于溶剂的生产（如甲基氯仿、三氯乙烯等）。全世界范围内，大约10%的Cl2 用于无机含氯的化合物的生产。尽管Cl2 用于漂白木材浆是来自环境压力的另一种途径，但是在一些国家Cl2 的十分重要的用途是用于木材浆的漂白。
Unit 7 Ammonia, Nitric Acid and Urea
氯、硝酸和尿素
虽然N2 占我们呼吸的空气3/4 以上，但是氯气不容易用于进一步化学应用。对化学工业来说，N2 的生成有用化学品的生物转化反应难以实现，因为所有的工业技术人员的努力（或尝试）还没有找到该过程
的简单其他方法。在常压和室温条件下，豆类植物能从空气中吸入N2 将之转化为NH3 以及含NH4-的产物。尽管（化学工艺师）花了一百年的精力，要实现上述转化，化学工业仍然需要高温和上百个大气压的
压力。直到Harber 过程的发明，所有的含N 化学品都来自于有生物活性的矿物资源。
基本上，所生产的化学品中所有的N（元素）都来自于Harber 法得来的NH3。NH3 的生产之大，（尽管因为氨分子较轻，生产的其它产品的量更大，但其生产的NH3 的分子数要多于其他任何化合物），以及
该过程的能源是如此的密集，以致于据估计，在二十世纪八十年代NH3 的生产就消耗全世界能源供应的
3%。
1、Harber 法合成NH3
引言所有的生产NH3 的方法基本都是以Harber 法为基础，稍稍加以改变，该过程是由Harber、Nerst、
Bosh 在德国于一战前开发出来的。
N2 +3H2≒2 NH3
原则上，H2 和N2 间的反应很容易进行，该反应是放热反应，低温时平衡向右移动。所不幸的是，
自然界赋予的N2 一个很强的叁键，这使得N2 分子不易受热力学因素的影响。用科学术语来说，该分子是动力学惰性的。因此，要使该反应以一定的速度进行，需要相当苛刻的反应条件。实际上，“固定”（意
思相互矛盾，“有用的反应活性”）氦的一种主要来源是闪电过程，闪电时生产大量的热量，把N2 和O2
转化为N2O.
在化工厂中要得到可观的NH3 的转化率，我们有必要使用催化剂。Harber 发现的催化剂（这使他获
得诺贝尔奖）。是一些价廉的含铁的化合物。即使有该催化剂，这反应也需要很高压力（早期高达600 个大气压）和高温（大约4000C）
因为四个气体分子转化为两个气体分子，所以增加压力使平衡向右（正方向）移动。然而，尽管高温使反应速度加快，但是高温使平衡向右移动，因此，所选的条件必须要折中的能以合理的速率得到令人满
意的转化率。条件的准确选择将取决于其他的经济因素和催化剂的具体情况。因为资本和能耗费用越发重
要，当代的工厂已经趋向于比早期工厂在更低的压力和更高的温度（循环使用未转化的物料）下进行操作。
氮的生物固定也使用了一种催化剂，该催化剂镶在较大的蛋白质分子中含有钼和铁，其详细结构直到
1992 年才被化学家弄清楚，该催化剂的详细作用机理尚未清楚。
原料。该过程需要以下几种原料（进料）的能源、N2 和H2。N2 很容易从空气中提取，但是H2 的来源很成问题。以前，H2 来源于通过煤的焦化反应，煤用作蒸汽重整的原料（主要是C 的来源），在蒸汽
重整过程中，水蒸气与C 反应生成H2、CO 和CO2。如今，以天然气（主要是甲烷）代替，尽管也使用来自石油的烃类物质。通常，制NH3 的工厂包括与NH3 生产相连接的H2 生产车间。
在重整反应之前，含硫化合物必须从烃原料中除去，因为它们既能污染重整催化剂又能污染Harber
催化剂。第一除硫步骤需要钴-铜催化剂。该催化剂能将所有的含硫化合物氢化生成H2S，H2S 能与ZnO
反应（ZnS 和H2O）加以除去。
主要的重整反应中，下列甲烷反应最为典型（甲烷的反应发生于约7500C.含镍催化剂上）CH4 + H2O→ CO + 3H2 （合成气）
CH2 + 2H2O→ CO2 + 4H2
其他烃经历类似反应。
在次级重整器中，空气注入温度11000C 的气流，除了发生其他反应外，空气中的O2 与H2 反应生成H2O，结果剩下不会污染的O2 的混合物，该混合物中O2 与H2 的比接近理想比3：1.然而，下一步
反应必须通过下列转化反应将更多的CO 转变为H2 和CO2 。
CO+ H2O→ CO2 + H2
为使其尽可能完全的转化，此反应应该在较低温度下以两步进行（一步是在4000C 用铁为催化剂，另
一步是在2000C 下用催化剂）。
下一步中，CO2 必须从气体混合物中除去。除去CO2 可以用该酸性气体与碱性溶液（如KOH 和（或）
单乙醇胺或二乙醇胺反应得以实现。
这一步中，任然存在CO（污染Harbor 催化剂）对H2-N2 混合物造成很大污染，需要用另一步去将CO 得量降低至PPM 级，这一步称为甲烷化反应，涉及到CO 和H2 反应生成甲烷（即一些重整反应的逆
反应），该反应大约在325℃操作，用一种Ni 催化剂。
合成气混合物准备用于Harbor 反应
NH3 的生产各种不同氨厂的共同特征是合成经过加热，压缩，递往含成催化剂的反应器中，该基本
反应方程式很简单：
N2 + 3H2≒2NH3
该工业要实现的事：反应速度和反应产率的结合要令人满意，不同的时期和不同的经济环境下谋求
不同的折中方案，早期的制氨厂热衷于高压反应（其目的是在单程反应器中提高产率）但是当今大多数氨厂采用在较低的压力，很低的单程转化率，同时为节能而选择较低温度。为了确保反应器中的转化率最大，
通常在当反应达到平衡时，冷却合成气，使用热交换器或者在反应器的合适位置注入冷却氨，可实现合成
气的冷却，这样做的作用是：在反应在尽可能接近平衡使其冷冻停止，因为此反应时放热反应（同时在较
高温度下的平衡对氨的合成时不利的）所以为了得到好的收率，可以用这种方法，对热量进行很好的控制。
哈伯法的产物由氨和合成气混合物（组成）因此，下一步需要将两者进行分离以能循环利用合成气，
这可以压缩氨气得以实现（氨气的挥发度较其他组成小得多，大约在— 40℃沸腾）
氨的用途氨的主要用途不是用于进一步应用的含氨化合物的生产，而是用于生产肥料（如尿素，硝酸铵和磷酸铵）。肥料消耗了所生产氨的80%。例如：在1991 年美国消费的由氨得来的产物如下：其中大
部分用作肥料（数量以百万吨计）尿素（4.2 百万吨）硫酸铵（二百二十万吨），硝酸铵（二百六十万吨），
磷酸氢二铵（一千三百五十万吨）。
氨的化学应用各式各样，尽管在制备纯碱的索维尔工艺中氨气得到回收而没出现于最终产品中，但是
该过程需要使用氨气，很多过程直接吸收氨气，这些过程包括氰化物和芳香族含氮化合物（如吡啶）的生
产。许多聚合物（如尼龙和丙烯酸类聚合物）中的氮可以追溯到氨，通常通过睛或氰（HCN）大多数的其
他过称（工艺）以氨制的硝酸或硝酸盐作氮源，硝酸铵，用作含氮的肥料，它的另一种主要用途用作大众
化炸药。
2 硝酸
硝酸的生产化学工业制造其他原料时，所用的大部分氮元素不是以氨的形式直接利用，而是先将氨
转化为硝酸，硝酸的生产大约消耗所生产的氨的20%
氨生成硝酸的转化反应是一个三步过程：
1 4NH3 + 5O2→ 4NO + 6H2O
2 2NO +O2→ 2NO2
3 3NO2+H2O→ 2HNO3+N O
第一个反应用铂（实际上是铂铑金属网）催化，该催化反应可以再实验室上用一根铂丝和浓氨水溶液
观察到。初看起来，生成硝酸的总反应似乎很简单，所不幸的事，实际过程比化学家和工程师所想的要糟
的多，因此，存在许多复杂的因素。
工业上，第一反应于含铂铑金属网的反应器中，在900 度左右进行，温度由该反应产生的热量得以维
持，在该温度下，一些重要的副反应也进行得很快，其一，氨和空气混合物能被氧化生成氨气和水（如果
反应器器壁的温度高，那么该反应趋向于在壁上进行，因此有必要特意将之冷却），其二，催化剂可促进
第一反应的产物NO 的分解，生成氨气和氧气，因此重要的是尽可能快地将产物移出反应器，尽管这一做
法与下列事实相矛盾：为使原料和催化剂得以反应，有必要保持原料与催化剂接触时间足够长。其三：反
应产物NO 与氨反应生成氨气和水，因此重要的事，不让过多的暗器流过催化剂床层，否则，
原料不可回
收而浪费。利用精心设计的反应器，控制温度和通过反应器的流速可以实现这些矛盾要素的控制。通常该
反应的实际接触时间约3×10-4 秒
第二步和第三步反应复杂性较小，但是，两者的反应速度很慢，尚未发现高效的催化剂，一般的，令
氨气和NO 的混合物流经一系列的冷凝压缩器，在这些压缩器中发生部分氧化反应，低温对该反应有利。
当混合气体流经大型泡罩吸收塔时，NO2 从该混合气体得以吸收，塔底为55%— 60%硝酸因为硝酸在68%时与水形成共沸物，所以不能用蒸馏法加工以浓缩，硝酸厂通常利用含98%的硫酸塔
在其塔顶去生成90%硝酸，如有必要，利用硝酸镁对之进一步脱水可得到接近100%的硝酸硝酸的用途在所生产硝酸大约有65%与氨反应制造硝酸铵，80%的硝酸铵用于肥料，其余的用作炸
药。硝酸的另一个主要作用是用于有机硝化反应，几乎所有的炸药最终都是来自硝酸（大部分为硝酸酯,如硝化甘油或为硝化芳香族化合物如三硝基甲苯）在合成重要的硝基或氨基芳香族中间体时（如苯胺）时，
第一步为利用和硝酸的硝化反应。苯胺的合成，第一步为芳香族化合物的硝化，然而将硝基还原为胺基。
许多重要的染料和药物最终都是通过该反应得到，尽它们的需求量很小，聚氨酯塑料的制备时以芳香族异
氰酸酯为基础，而芳香族异氰酸酯最终来自于硝化甲苯和苯，该用途大约要消耗5%— 10%的硝酸产量
3 尿素
尿素的生产，另一种重要的直接由氨大量生产的产物为尿素，大约有20%的氨用于尿素的生产，尿素
是通过CO2 和NH3 的高压反应合成（一般为200— 400 个atm 和180℃— 210℃）该反应可分为两步：
1 CO2+2NH3-NH2CO-2NH+4
2 NH2CO-2NH+4-NH2CONH2+H2O
该高压反应可实现将60%的CO2 转化为氨基甲酸酯，生成的混合物输入低压分解器使之转化为尿素，
未反应的物料被输回该工艺中高压步骤的开始阶段，这样做可以大大提高车间的总效率，第二阶段所得的
溶液可直接用作液态含氮肥料或经浓缩生产纯度为99%固体尿素
尿素的用途尿素的含氮量高使之成为另一种有利氮肥，尿素占氮肥市场的绝大部分，其他的用途也
很重要，但是只占所生产品尿素的10%左右。尿素的最大的另一用途是用于树脂（甲醛二聚氰酰胺和尿素
甲醛）例如这些树脂用作胶合板粘结剂和弗莱卡的表面。
Unit 10 What Is Chemical Engineering?
什么是化学工程学
In a wider sense, engineering may be defined as a scientific presentation of the techniques and facilities used in a particular industry. For example, mechanical engineering refers to the techniques and facilities employed to make machines. It is predominantly based on mechanical forces which are used to change the appearance and/or physical properties of the materials being worked, while their chemical properties are left unchanged. Chemical engineering encompasses the chemical processing of raw materials, based on chemical and physico-chemical phenomena of high complexity.
广义来讲，工程学可以定义为对某种工业所用技术和设备的科学表达。例如，机械工程学涉及的是制造机器的工业所用技术和设备。它优先讨论的是机械力，这种作用力可以改变所加工对象的外表或物理性质而不改变其化学性质。化学工程学包括原材料的化学过程，以更为复杂的化学和物理化学现象为基础。
Thus, chemical engineering is that branch of engineering which is concerned with the study of the design, manufacture, and operation of plant and machinery in industrial chemical processes.
因此，化学工程学是工程学的一个分支，它涉及工业化化学过程中工厂和机器的设计、制造、和操作的研究。
Chemical engineering is above all based on the chemical sciences, such as physical chemistry, chemical thermodynamics, and chemical kinetics. In doing so, however, it does not simply copy their findings, but adapts them to bulk chemical processing. The principal objectives that set chemical engineering apart from chemistry as a pure science, is “to find the most economical route of opera tion and to design commercial equipment and accessories that suit it best of all”. Therefore, chemical engineering is inconceivable without close ties with economics, physics, mathematics, cybernetics, applied mechanics, and other technical sciences.
前述化学工程学都是以化学科学为基础的，如物理化学，化学热力学和化学动力学。然而这样做的时候，它并不是仅仅简单地照搬结论，而是要把这些知识运用于大批量生产的化学加工过程。把化学工程学与纯化学区分开来的首要目的是“找到最经济的生产路线并设计商业化的设备和辅助设备尽可能地适应它。”因此如果没有与经济学，物理学，数学，控制论，应用机械以及其它技术的联系就不能想象化学工程会是什么样的。
In its early days, chemical engineering was largely a descriptive science. Many of the early textbooks and manuals on chemical engineering were encyclopedias of the commercial production processes known at the time. Progress in science and industry has bought with it an impressive increase in the number of chemical manufactures. Today, petroleum for example serves as the source material for the production of about 80 thousand chemicals. The expansion of the chemical process industries on the one hand and advances in the chemical and technical sciences on the other have made it possible to lay theoretical foundations for chemical processing.
早期的化学工程学以描述性为主。许多早期的有关化学工程的教科书和手册都是那个时
候已知的商品生产过程的百科全书。科学和工业的发展使化学品的制造数量迅速增加。举例来说，今天石油已经成为八万多种化学产品生产的原材料。一方面是化学加工工业扩张的要求，另一方面是化学和技术水平的发展为化学工艺建立理论基础提供了可能。
As the chemical process industries forged ahead, new data, new relationships and new generalizations were added to the subject-matter of chemical engineering. Many branches in their own right have separated from the main stream of chemical engineering, such as process and plant design, automation, chemical process simulation and modeling, etc.
随着化学加工工业的发展，新的数据，新的关系和新的综论不断添加到化学工程学的目录中。然后又从主干上分出许多的分支，如工艺和工厂设计，自动化，化工工艺模拟和模型，等等。
1. A Brief Historical Outline
Historically, chemical engineering is inseparable from the chemical process industries. In its early days chemical engineering which came into being with the advent of early chemical trades was a purely descriptive division of applied chemistry.
1．简要的历史轮廓
从历史上来说，化学工程学与化学加工工业密不可分。在早期，化学工程学随着早期化学产品交易的发展而出现，是应用化学的纯描述性的分支。
The manufacture of basic chemical products on Europe appears to have begun in the 15th century when small, specialized businesses were first set up to turn out acids, alkalis, salts, pharmaceutical preparations, and some organic compounds.
在欧洲，基础化学产品的制造出现在15世纪。一些小的、专门的企业开始创立，生产酸、碱、盐、药物中间体和一些有机化合物。
For all the rhetoric of nineteenth-century academic chemists in Britain urging the priority of the study of pure chemistry over applied, their students who became works chemists were little more than qualitative and quantitative analysts. Before the 1880s this was equally true of German chemical firms, who remained content to retain academic consultants who pursued research within the university and who would occasionally provide the material for manufacturing innovation. By the 1880s, however, industrialists were beginning to recognize th at the scaling up of consultants? laboratory preparations, and syntheses was a distinctly different activity from laboratory investigation. They began to refer to this scaling problem and its solution as “chemical engineering”—possibly because the mechanical engineers who had already been introduced into works to who seemed best able to understand the process involved. The academic dichotomy of head and hand died slowly.
由于十九世纪英国的学院化学家强调纯化学的研究高于应用化学，他们的要成为工业化学家的学生也只是定性和定量分析者。在19世纪80年代以前，德国的化学公司也是这样。他们愿意聘请那些在大学里进行研究的人作顾问，这些人偶尔为制造的革新提供一些意见。然而到了80年代，工业家们开始认识到要把顾问们在实验室的准备和合成工作进行放大是一个与实验室研究截然不同的活动。他们开始把这个放大的问题以及解决的方法交给“化学工程师”—这可能是受到已经进入工厂的机械工程师的表现的启发。由于机械工程师熟悉所涉及的加工工艺，是维修日益复杂化的工业生产中的蒸气机和高压泵的最合适的人选。学院研
究中头和手两分的现象逐渐消亡。
Unit operation. In Britain when in 1881 there was an attempt to name the new Society of Chemical industry as the “Society of Chemical engineers”, the suggestion was turned down. On the other hand, as a result of growing pressure from the industrial sector the curricula of technical institutions began to reflect, at last, the need for chemical engineers rather than competent analysts. No longer was mere description of existing industrial processes to suffice. Instead the expectation was that the processes generic to various specific industries would be analyzed, thus making room for the introduction of thermodynamic perspectives, as well as those being opened up buy the new physical chemistry of kinetics, solutions and phases.
单元操作。1881年英国曾经准备把化学工业的一个新的协会命名为“化学工程师协会”，这个建议遭到了拒绝。另一方面，由于受到来自工业界日益加重的压力，大学的课程开始体现出除了培养分析工作者还要培养化学工程师的要求。现在仅仅对现有工业过程进行描述已经不够了，需要对各种特殊工业进行工艺属性的分析。这就为引入热力学及动力学、溶液和相等物理化学新思想提供了空间。
A key figure in this transformation was the chemical consultant, George Davis (1850-1907), the first secretary of the Society of Chemical Industry. In 1887 Davis, then a lecture at the Manchester Technical School, gave a series of lectures on chemical engineering, which he defined as the study of “the application of machiner y and plant to the utilization of chemical action on the large scale”. The course, which revolved around the type of plant involved in large-scale industrial operations such as drying, crashing, distillation, fermentation, evaporation and crystallization, slowly became recognized as a model for courses elsewhere, not only in Britain, but overseas. The first fully fledged course in chemical engineering in Britain was not introduced until 1909;though in America, Lewis Norton (1855-1893) of MIT pioneered a Davis-type course as early as 1888.
在这个转变期，一位关键的人物是化学顾问George Davis，化学工业协会的首任秘书。1887年Davis那时是Manchester专科学校的一名讲师，做了一系列有关化学工程学的讲座。他把化学工程学定义为对“大规模化学生产中所应用的机器和工厂”的研究。这们课程包括了大规模工业化操作的工厂的各种类型，如干燥、破碎、蒸馏、发酵、蒸发和结晶。后来逐渐在别的地方而不仅仅在英国，而是国外，成为许多课程的雏形。英国直到1909年化学工程学才成为一门较为完善的课程，而在美国，MIT的Lewis Norton早在1888年就已率先开出了Davis型课程。
In 1915, Arthur D. Little, in a report on MIT?s programme, referred to it as the study of “unit operations” and this neatly encapsulated the distinctive feature of chemical engineering in the twentieth century. The reasons for the success of the Davis movement are clear: it avoided revealing the secrets of specific chemical processes protected by patents or by an owner?s reticence—factors that had always seriously inhibited manufacturers from supporting academic programmes of training in the past. Davis overcame this difficulty by converting chemical industries “into separate phenomena which could be studied independently” and, indeed, experimented with in pilot plants within a university or technical college workshop.
1915年，Arthur D. little 在一份MIT的计划书中，提出了“单元操作”这个概念，这几乎为二十世纪化学工程学的突出特点做了定性。Davis这一倡议的成功原因是很明显的：它避免了泄露特殊化学过程中受专利权或某个拥有者的保留权所保护的秘密。过去这种泄露已经严重限制了制造者对学院研究机构训练计划的支持。Davis把化学工业分解为“能独立进
城市学院英语课文翻 译
Don't Wait Until Death Does Its Part We have but one body. It must last a lifetime. Without it, life ends, and we are done and finished. But do we treat our body fairly, lovingly, like prized possessions? Do we appreciate our body's nonstop efforts to function smoothly? My body asks for little: water to keep hydrated; food for nutrients, energy, and strong bones; rest when I'm tired or sick; and play to lift my spirits. Its ability to self-repair and respond to good care is incredible. But until recently, I have abused my body with excesses of all kinds. Not only did I take its resiliency for granted, I was annoyed when a physical problem, such as a cold or injury, kept me from doing what I want. Moreover, I was harshly critical when it failed to conform to standards of beauty in the media. My overeating, lazy lifestyle, and excessive work had a negative impact on my life, though not fatal. I've also seen friends and family members destroy their body through drugs, alcoholism, or workaholism. For years I had good intentions to change, but I didn't follow through. I could see my future: increased medical expenses, exhausted senses, premature death. Once I understand that it is in my own self-interest to take care of it, I'm struggling to develop a positive relationship with my body. Evidently, I'm not the only one with this awareness now. I begin to make more constructive choices. Instead of asking the question, “What do I want?” I ask, “What does my body need?” And then I respond acc ordingly. Positive actions — exercising, eating mindfully, getting enough rest and water, limiting my work hours, and scheduling recreation — have gradually become regular habits rather than disciplined efforts. After all, each of us gets only one body. So don't wait until death does its part. Appreciate our body and treat it lovingly. It will reward us with a longer, healthier and happier life.
现代大学英语精读翻译 Revised by Hanlin on 10 January 2021
第三课 T1. Today we are in the throes of a worldwide reformation of cultures, a tectonic shift of habits and dreams called, in the curious vocabulary of social scientists, “globalization”. (Para.1)今天我们正经历着一种世界范围文化剧变的阵痛,一种习俗与追求的结构性变化,用社会科学家奇特的词汇来称呼这种变化,就叫“全球化”. T2. Whatever their backgrounds or agendas, these critics are convinced that Western—often equated with American—influences will flatten every cultural crease, producing, as one observer terms it, one big “McWorld”. (Para.4) 不管他们的背景和纲领如何,这些对全球化持反对态度的人深信西方的影响—往往等同于美国的影响—会把所有文化上的差异一一压平,就像一位观察家所说的,最终产生一个麦当劳世界,一个充斥美国货和体现美国价值观的世界. T3. But I also discovered that cultures are as resourceful, resilient, and unpredictable as the people who compose them. (Para.8) 不过我也发现文化就如同构成文化的民族一样,善于随机应变,富有弹性而且不可预测.
第一章汽车总论 1)Today’s average car contains more than 15,000 separate, individual parts that must work together. These parts can be grouped into four major categories: body, engine, chassis and electrical equipment 。P1 现在的车辆一般都由15000多个分散、独立且相互配合的零部件组成。这些零部件主要分为四类：车身、发动机、底盘和电气设备。 2)The engine acts as the power unit. The internal combustion engine is most common: this obtains its power by burning a liquid fuel inside the engine cylinder. There are two types of engine: gasoline (also called a spark-ignition engine) and diesel (also called a compression-ignition engine). Both engines are called heat engines; the burning fuel generates heat which causes the gas inside the cylinder to increase its pressure and supply power to rotate a shaft connected to the power train. P3 发动机作为动力设备，常见的类型是内燃机，其原理是通过发动机缸内的液体燃料燃烧而产生能量。发动机可分为两类：汽油机（点燃式）和柴油机（压燃式），都属于热力发动机。燃料燃烧产生热量使缸内气压上升，产生的能量驱动轴旋转，并传递给动力传动系。 第二章内燃机 1)Power train system: conveys the drive to the wheels 2)Steering system: controls the direction of movement 3)Suspension system: absorbs the road shocks 4)Braking system: slows down the vehicle P4 传动系把发动机输出的扭矩传递给驱动轮。传动系包括离合器（对应机械变速器）或液力变矩器（对应液力自动变速器）、变速器、驱动轴、主减速器、差速器和驱动桥。 5)Drum brakes have a drum attached to the wheel hub, and braking occurs by means of brake shoes expanding against the inside of the drum. With disc brakes, a disc attached to the wheel hub is clenched between two brake pads. P6 鼓式制动器的制动鼓和轮毂连接，制动蹄张开压紧制动鼓内侧从而产生制动。在盘式制动器上，连着轮毂的制动盘被紧紧夹在两个制动块之间。 1)Linking the piston by a connecting rod to a crankshaft causes the gas to rotate the shaft through half a turn.The power stroke"uses up"the gas,so means must be provided to expel the burnt gas and recharge the cylinder with a fresh petrol-air mixture:this control of gas movement is the duty of the valves;An inlet valve allows the mixture to enter at the right time and an exhaust valve lets out the burnt gas after the gas has done its job . P10 活塞通过连杆和曲轴连接，使得气体带动曲轴旋转半圈。作功冲程耗尽了所有的气体，这样就必须采取相应的措施排出废气并且向气缸内充入新的可燃混合气：气体的运动由气门来控制。进气门使可燃混合气在恰当的时刻进入气缸，排气门使燃烧后的废气排出气缸。 2)The spark-ignition engine is an internal-combustion engine with externally supplied in ignition,which converts the energy cntained in the fuel to kinetic energy.The cycle of operations is spread over four piston strokes. To complete the full cycle it takes two revolutions of the crankshaft. P11 火花点火式发动机是由外部提供点火的内燃机，从而将含在燃料内的能量转化成动能。发动机的一个工作循环分布在活塞的四个行程中，一个完整的工作循环曲轴需要转动两圈。 3)The oil pump in the lubricating system draws oil from the oil pan and sends it to all working parts in the engine. The oil drains off and runs down into the pan. Thus,there is constant circulation of oil between the pan and the working parts of the engine. P15
Book 4-Unit 5 Text A The Telephone Anwar F. Accawi 1.When I was growing up in Magdaluna, a small Lebanese village in the terraced, rocky mountains east of Sidon, time didn't mean much to anybody, except maybe to those who were dying. In those days, there was no real need for a calendar or a watch to keep track of the hours, days, months, and years. We knew what to do and when to do it, just as the Iraqi geese knew when to fly north, driven by the hot wind that blew in from the desert. The only timepiece we had need of then was the sun. It rose and set, and the seasons rolled by and we sowed seed and harvested and ate and played and married our cousins and had babies who got whooping cough and chickenpox—and those children who survived grew up and married their cousins and had babies who got whooping cough and chickenpox. We lived and loved and toiled and died without ever needing to know what year it was, or even the time of day. 2.It wasn't that we had no system for keeping track of time and of the important events in our lives. But ours was a natural or, rather, a divine—calendar, because it was framed by acts of God: earthquakes and droughts and floods and locusts and pestilences. Simple as our calendar was, it worked just fine for us. 3.Take, for example, the birth date of Teta Im Khalil, the oldest woman in Magdaluna and all the surrounding villages. When I asked Grandma, "How old is Teta Im Khalil" 4.Grandma had to think for a moment; then she said, "I've been told that Teta was born shortly after the big snow that caused the roof on the mayor's house to cave in."
Unit 3 Out of Step Bill Bryson 1 After living in England for 20 years, my wife and I decided to move back to the United States. We wanted to live in a town small enough that we could walk to the business district, and settled on Hanover, N.H., a typical New England town—pleasant, sedate and compact. It has a broad central green surrounded by the venerable buildings of Dartmouth College, an old-fashioned Main Street and leafy residential neighborhoods. 2 It is, in short, an agreeable, easy place to go about one’ s business on foot, and ye far as I can tell, virtually no one does. 3 Nearly every day, I walk to the post office or library or bookstore, and sometimes, if I am feeling particu larly debonair, I stop at Rosey Jekes Caféa cappuccino. Occasionally, in the evenings, my wife and I stroll up to the Nugget Theatre for a movie or to Murphy’ s on the Green for a beer, I wouldn’ t dream of going to any of these places by car. People ha ve gotten used to my eccentric behavior, but in the early days acquaintances would often pull up to the curb and ask if I wanted a ride. 4“ I’ m going your way,” they would insist when I politely declined. no bother.”
我们像在暖房里种花那样养孩子是错误的。我们必须让他们接触各种社会问题，因为不久他们就将作为公民来应对这些问题。 It was wrong to raise our children the way we grow flowers in the greenhouse. We must expose them to all social problems because very soon they will be dealing with them as responsible citizens. 随着时间的推移，我们不可避免地会越来越多地卷入国际事务。而冲突必然会发生，因为国家之间总有不同的观点和利益。 As time goes on we are inevitably going to get more and more involved in international affairs. And conflicts are sure to occur because there always exists different views and interests among nations 我们为我们的成就而骄傲，我们有理由感到骄傲。但是我们永远不能变得狂妄，不然我们就会失去我们的朋友。 We are proud of our accomplishments, and we have reason to be. But we must never become arrogant. Otherwise we will lose our friends. 信息现在唾手可得。一个普通的电脑就能储存一个普通图书馆的信息。 Information is now easily available. An average computer can store the information of a small library. 那家建筑公司没有资格操作这个项目。他们没有任何法律文件能证明他们具备必要的专门技术。我们必须找一个专门建造歌剧院的公司。 That construction company is not qualified to handle the project. They do not have any legal document to certify that they have the necessary expertise. We must find a company that specializes in building theatres. 这些智囊团不作决策。他们力图提出一些对决策者十分有用的新主意和深刻的分析。These think tanks do not make decisions. They are out to generate new ideas and penetrating analyses that will be extremely useful for decision makers. 国内生产总值不是一切。如果人民的生活质量没有真正改善的话，我们国家就不能说已经现代化了。 The growth of GDP is not everything. Our country cannot be said to have been modernized unless the quality of our people?s lives is really improved. 虽然那时候我们在很多方面都很困难，但作为孩子我们仍然幸福，因为有干净的空气、水；江河湖泊里有很多鱼、螃蟹，黄鳝；田野里有花，有树，有鸟。 Poor as we were in many ways at that time, we were still quite happy as children, for there was clean air, clean water, a lot of fish, crabs and eels in the rivers, lakes and ponds; and a lot of flowers, trees and birds in the fields.
Unit1 Another School Year — What For Let me tell you one of the earliest disasters in my career as a teacher. It was January of 1940 and I was fresh out of graduate school starting my first semester at the University of Kansas City. Part of the student body was a beanpole with hair on top who came into my class, sat down, folded his arms, and looked at me as if to say "All right, teach me something." Two weeks later we started Hamlet. Three weeks later he came into my office with his hands on his hips. "Look," he said, "I came here to be a pharmacist. Why do I have to read this stuff" And not having a book of his own to point to, he pointed to mine which was lying on the desk. New as I was to the faculty, I could have told this specimen a number of things. I could have pointed out that he had enrolled, not in a drugstore-mechanics school, but in a college and that at the end of his course meant to reach for a scroll that read Bachelor of Science. It would not read: Qualified Pill-Grinding Technician. It would certify that he had specialized in pharmacy, but it would further certify that he had been exposed to some of the ideas mankind has generated within its history. That is to say, he had not entered a technical training school but a university and in universities students enroll for both training and education.
Unit 1 Text A Howard Gardner, a professor of education at Harvard University, reflects on a visit to China and gives his thoughts on different approaches to learning in China and the West. 哈佛大学教育学教授霍华德·加德纳回忆其中国之行，阐述他对中西方不同的学习方式的看法。 Learning, Chinese-Style Howard Gardner 1 For a month in the spring of 1987, my wife Ellen and I lived in the bustling eastern Chinese city of Nanjing with our 18-month-old son Benjamin while studying arts education in Chinese kindergartens and elementary schools. But one of the most telling lessons Ellen and I got in the difference between Chinese and American ideas of education came not in the classroom but in the lobby of the Jinling Hotel where we stayed in Nanjing. 中国式的学习风格 霍华德·加德纳 1987年春，我和妻子埃伦带着我们18个月的儿子本杰明在繁忙的中国东部城市南京住了一个月，同时考察中国幼儿园和小学的艺术教育情况。然而，我和埃伦获得的有关中美教育观念差异的最难忘的体验并非来自课堂，而是来自我们在南京期间寓居的金陵饭店的大堂。 2 The key to our room was attached to a large plastic block with the room number on it. When leaving the hotel, a guest was encouraged to turn in the key, either by handing it to an attendant or by dropping it through a slot into a box. Because the key slot was narrow, the key had to be positioned carefully to fit into it. 我们的房门钥匙系在一块标有房间号的大塑料板上。酒店鼓励客人外出时留下钥匙，可以交给服务员，也可以从一个槽口塞入钥匙箱。由于口子狭小，你得留神将钥匙放准位置才塞得进去。 3 Benjamin loved to carry the key around, shaking it vigorously. He also liked to try to place it into the slot. Because of his tender age and incomplete understanding of the need to position the key just so, he would usually fail. Benjamin was not bothered in the least. He probably got as much pleasure out of the sounds the key made as he did those few times when the key actually found its way into the slot. 本杰明爱拿着钥匙走来走去，边走边用力摇晃着。他还喜欢试着把钥匙往槽口里塞。由于他还年幼，不太明白得把钥匙放准位置才成，因此总塞不进去。本杰明一点也不在意。他从钥匙声响中得到的乐趣大概跟他偶尔把钥匙成功地塞进槽口而获得的乐趣一样多。 4 Now both Ellen and I were perfectly happy to allow Benjamin to bang the key
Lesson Eight The Kindness of Strangers Mike Mclntyre 1. One summer I was driving from my home town of Tahoe City, Calif, to New Orleans. In the middle of the desert, I came upon a young man standing by the roadside. He had his thumb out and held a gas can in his other hand. I drove right by him. There was a time in the country when you' d be considered a jerk if you passed by somebody in need. Now you are a fool for helping. With gangs, drug addicts, murderers, rapists, thieves lurking everywhere, "I don't want to get involved" has become a national motto. 2. Several states later I was still thinking about the hitchhiker. Leaving him stranded in the desert did not bother me so much. What bothered me was how easily I had reached the decision. I never even lifted my foot off the accelerator. 3. Does anyone stop any more? I wondered. I recalled Blanche DuBois's famous line: "I have always depended on the kindness of strangers." Could anyone rely on the kindness of strangers these days? One way to test this would be for a person to journey from coast to coast without any money, relying solely on the good will of his fellow Americans. What kind of Americans would he find? Who would feed him, shelter him, carry him down the road? 4. The idea intrigued me. 5. The week I turned 37, I realized that I had never taken a gamble in my life. So I decided to travel from the Pacific to the Atlantic without a penny. It would be a cashless journey through the land of the almighty dollar. I would only accept offers of rides, food and a place to rest my head. My final destination would be Cape Fear in North Carolina, a symbol of all the fears I'd have to conquer during the trip. 6. I rose early on September 6, 1994, and headed for the Golden Gate Bridge with a 50-pound pack on my back and a sign displaying my destination to passing vehicles: "America." 7. For six weeks I hitched 82 rides and covered 4223 miles across 14 states. As I traveled, folks were always warning me about someplace else. In Montana they told me to watch out for the cowboys in Wyoming, In Nebraska they said people would not be as nice in Iowa. Yet I was treated with kindness everywhere I went. I was amazed by people's readiness to help a stranger, even when it seemed to run contrary to their own best interests. 8. One day in Nebraska a car pulled to the road shoulder. When I reached the window, I saw two little old ladies dressed in their Sunday finest." I know you're not supposed to pick up hitchhikers, but it's so far between towns out here, you feel bad passing a person," said the driver, who introduced herself as Vi. I didn't know whether to kiss them or scold them for stopping. This woman was telling me she'd rather risk her life than feel bad about passing a stranger on the side of the road. 9. Once when I was hitchhiking unsuccessfully in the rain, a trucker pulled over, locking his brakes so hard he skidded on the grass shoulder. The driver told me he was once robbed at knifepoint by a hitchhiker. "But I hate to see a man stand out in the rain," he added. "People don't have no heart anymore." 10. I found, however, that people were generally compassionate. Hearing I had no money and would take none, people bought me food or shared whatever they happened to have with them. Those who had the least to give often gave the most. In Oregon a house painter named Mike noted the chilly weather and asked if I had a coat. When he learned that I had "a light one," he drove me to his house, and handed me a big green army-style jacket. A lumber-mill worker named Tim invited me to a simple dinner with his family in their shabby house. Then he offered me his tent. I refused, knowing it was probably one of the family's most valuable possessions. But Tim was determined that I have it, and finally I agreed to take it. 11. I was grateful to all the people I met for their rides, their food, their shelter, and their gifts. But what I found most touching was the fact that they all did it as a matter of course.
About car engine Of all automobile components,an automobile engie is the most complicated assembly with dominant effects on the function of an autombile.So, the engine is generally called the"heat"of an automobile. 在汽车的所有部件中，汽车发动机是最复杂的组件，其对整车性能有着决定性的作用。因而发动机往往被称作发动机的“心脏”。 There are actually various types of engines such as electric motors,stream engines,andinternal combustion engines.The internal combustion engines seem to have almost complete dominance of the automotive field.The internal combustion engine,as its name indicates,burns fuel within the cylinders and converts the expanding force of the combustion into rotary force used to propel the vehicle. 事实上，按动力来源分发动机有很多种，如电动机、蒸汽机、外燃机等。然而内燃机似乎在发动机领域有着绝对的统治地位。就像其字面意思一样，内燃机的染料在气缸内燃烧，通过将燃烧产生气体的膨胀力转换成转动力来驱动发动机前进。 Engine is the power source of the automobile.Power is produced by the linear motion of a piston in a cylinder.However,this linear motion must be changed into rotary motion to turn the wheels of cars or trucks.The puston attached to the top of a connecting rod by a pin,called a piston pin or wrist pin.The bottom of the connecting rod is attached to the crankshaft.The connecting rod transmits the up-and-down motion of the piston to the crankshaft,which changes it into rotary motion.The connecting rod is mounted on the crankshaft with large bearings called rod bearing.Similar bearings, called main bearings,are used to mount the crankshaft in the block. 发动机是整部车的动力来源。能量来自于活塞在气缸内的（往复）直线运动。然而这种（往复）直线运动必须要转换成旋转运动才能驱动车轮。活塞与连杆通过一个销来连接，这个销称为活塞销。连杆的下部连接于曲拐。连杆把活塞的上下往复运动传递给曲拐，从而将往复直线运动转变成旋转运动。连杆和曲拐的连接使用大的轴承，称之为连杆轴承，类似的轴承也用于将曲轴连接到机体，称之为主轴承。 They are generally two different types of cooling system:water-cooling system and air-cooling system.Water-cooling system is more common.The cooling medium, or coolant, in them is either water or some low-freezing liquid, called antifreeze.A water-cooling system consists of the engine water jacket, thermostat, water pump, radiator, radiator cap, fan, fan drive belt and neccessary hoses. 主要有两种类型的冷却系统：水冷和风冷。水冷系统更为普遍。系统所用冷却介质或是冷却液常委水或其他低凝固点液体，称为抗凝剂。一个完整的水冷系统包括机体水套，节温器，水泵，散热器，散热器罩，风扇，风扇驱动皮带和必需的水管。 A water-cooling system means that water is used as a cooling agent to circulate through the engine to absorb the heat and carry it to the radiator for disposal.The ebgine is cooled mainly through heat transfer and heat dissipation.The heat generated by the mixture burned in the engine must be transferred from the iron or aluminum cylinder to the waterin the water jacket.The outside of the water jacket dissipates some of the heat to the air surrounding it, but most of the heat is carried by the cooling water to the radiator for dissipation.When the coolant temperature in the system reaches 90°,the termostat valve open fully, its slanted edge shutting off