Unit 10 What Is Chemical
Engineering?
什么是化学工程学
In a wider n, engineering may be defined as a scientific prentation of the techniques and facilities ud in a particular industry. For example, mechanical engineering refers to the techniques and facilities employed to make machines. It is predominantly bad on mechanical forces which are ud to change the appearance and/or physical properties of the materials being worked, while their chemical properties are left unchanged. Chemical engineering encompass the chemical processing of raw materials, bad 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 process.
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 bad 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 t chemical engineering apart from chemistry as a pure science, is “to find the most economical route of operation and to design commercial equipment and accessories that suit it best of all”. Therefore, chemical engineering is inconceivable without clo 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 process known at the time. Progress in science and industry has bought with it an impressive increa in the number of chemical manufactures. Today, petroleum for example rves 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 parated 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 inparable 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 business were first t 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 rearch within the university and who would occasionally provide the material for manufacturing innovation. By the 1880s, however, industrialists were beginning to recognize that the scaling up of consultants’ laboratory preparations, and synthes was a distinctly different activity from laboratory investigation. They began to refer to this scaling problem and its solution as “chemical engineering”—possibly becau the mechanical engineers who had already been introduced into works to who emed 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 ctor 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 process to suffice. Instead the expectation was that the process generic to various specific industries would be analyzed, thus making room for the introduction of thermodynamic perspectives, as well as tho being opened up buy the new physical chemistry of kinetics, solutions and phas.
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 cretary of the Society of Chemical Industry. In 1887 Davis, then a lecture at the Manchester Technical School, gave a ries of lectures on chemical engineering, which he defined as the study of “the application of machinery and plant to the utilization of chemical action on the large scale”. The cour, 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 cours elwhere, not only in Britain, but overas. The first fully fledged cour in chemical engineering in Britain was not introduced until 1909;though in America, Lewis Norton (1855-1893) of MIT pioneered a Davis-type cour 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Le
wis 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 crets of specific chemical process protected by patents or by an owner’s reticence—factors that had always riously inhibited manufacturers from supporting academic programmes of training in the past. Davis overcame this difficulty by converting chemical industries “into parate 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“能独立进行研究的单个的工序”从而克服了这个困难。并且在大学或专科学校的工厂里用中试车间进行了试验。
In effect he applied the ethics of industrial consultancy by which experience was transmitted “from plant to plant and from process to process in such a way which did not compromi the private or specific knowledge which contributed to a given plant’s profitability”. The concept of unit operations held that any chemical manufacturing process could be resolved into a coordinated ries of operations such as pulverizing, drying, roasting, electrolyzing, and so on. Thus, for example, the academic study of the specific aspects of turpentine manufacture could be replaced by the generic study of distillation, a process common to many other industries. A quantitative form of the unit operations concept emerged around 1920s, just in time for the nation’s first gasoline crisis. The ability of chemical engineers to quantitatively characterize unit operations such as distillation allowed for the rational design of the first modern oil refineries. The first boom of employment of chemical engineers in the oil industry was on.
他采用了工业顾问公司的理念，经验传递从一个车间到另一个车间，从一个过程到另一个过程。这种方式不包含限于某个给定工厂的利润的私人的或特殊的知识。单元操作的概念使每一个化学制造过程都能分解为一系列的操作步骤，如研末、干燥、烤干、电解等等。例如，学校对松节油制造的特殊性质的研究可以用蒸馏属性研究来代替。这是一个对许多其它工业制造也很普通的工艺过程。单元操作概念的定量形式大概出现在1920年，刚好是在第一次全球石油危机出现的时候。化学工程师能赋予单元操作定量特性的能力使得他们合理地设计了第一座现代
炼油厂。石油工业第一次大量聘请化学工程师的繁荣时代开始了。
During this period of intensive development of unit operations, other classical tools of chemical engineering analysis were introduced or were extensively developed. The included studies of the material and energy balance of process and fundamental thermodynamic studies of multicomponent systems.
在单元操作密集繁殖的时代，化学工程学另一些经典的分析手段也开始被引入或广泛发展。这包括过程中材料和能量平衡的研究以及多组分体系中基础热力学的研究。
Chemical engineers played a key role in helping the United States and its allies win World War Ⅱ. They developed routes to synthetic rubber to replace the sources of natural rubber that were lost to the Japane early in the war. They provided the uranium-235 needed to build the atomic bomb, scaling up the manufacturing process in one step from the laboratory to the largest industrial plant that had ever been built. And they were instrumental in perfecting the manufacture of penicillin, which saved the lives of potentially hundreds of thousands of wounded soldiers.
化学工程师在帮助美国及其盟国赢得第二次世界大战的胜利中起了关键的作用。他们发展了合成橡胶的方法以代替在战争初期因日本的封锁而失去来源的天然橡胶。他们提供了制造原子弹所需要的铀-23
5，把制造过程从实验室研究一步放大到当时最大规模的工业化工厂，而他们在完善penicillin的生产工艺中也是功不可没，它挽救了几十万受伤士兵的生命。
The Engineering Science Movement.Dissatisfied with empirical descriptions of process equipment performance, chemical engineers began to reexamine unit operations from a more fundamental point of view. The phenomena that take place in unit operations were resolved into ts of molecular events. Quantitative mechanistic models for the events were developed and ud to analyze existing equipment. Mathematical models of process and reactors were developed and applied to capital-intensive U.S. industries such as commodity petrochemicals.
工程学运动。由于不满意对工艺设备运行的经验描述，化学工程师开始从更基础的角度再审视单元操作。发生在单元操作中的现象可以分解到分子运动水平。这些运动的定量机械模型被建立并用于分析已有的
