remainder, used mostly for chemical production, comes from oil refinery fluid catalytic crackers. Refinery propylene is used mainly for alkylation.
丙烯除了做乙烯的副产品外很少被生产。乙烯蒸汽裂解产生大量丙烯，几乎所有都用于聚合物产品。剩余的大部分用于生产化学产品。来源于油炼制的液态催化饼干，炼油厂的丙烯主要用于烷基化。
Aromatics are usually thought of as coal-derived, but the amount from that source in 1980 was almost vanishingly small, 4 percent of the benzene, 0.9 percent of the toluene, and only 0.1 percent of the xylenes. Benzene can be made by dehydrogenation of cyclohexane or substituted cyclohexanes, by aromatization of methycyclopentane, and by demethylation of toluene or xylenes. The demand for aromatics is large and attention is being given to find catalysts to produce more BTX ( ) for chemical and high-grade fuel use.
芳香烃通常被认为是煤的衍生物,但是从1980年以来这种来源的芳香烃已经很少了,4%的苯,0.9%的甲苯,和仅仅0.1%的二甲苯苯能够用环己烷取代,通过芳构化甲基环戊烷,甲苯或二甲苯脱甲基。芳香族的需要量很大并且注意力放在发现催化剂生产更多的苯甲苯二甲苯混合物为化学和高级燃料油。
Naphthalene is used in smaller quantities than the lighter aromatics, but its consumption is far from trivial. Dealkylation of a selected reformate stream using chromate-aluminum carbide catalyst gives a product which is purified to be purer than that formed form coal tar.萘比轻芳香更小的使用量，但他是至关重要的。托烷基作用得到的萘比煤焦油得到的萘更纯。
Light distillates. Aviation gasoline, (automobile) motor gasoline, naphthas., petroleum solvents, jet-fuel, and kerosene are the fractions generally regarded as light distillates. Any given refinery rarely makes all of them. Gasoline is the most important product, and around 45 percent of the crude processed now ends up as gasoline.
轻馏分。航空汽油，汽油，石脑油，石油溶剂，发动燃料和煤油通常被认为是轻馏分的炼油厂不会一下生产上述所有列的轻质馏分，汽油是主要产品加工的大约45%的原油最终产物是汽油。
Intermediate distillates. These include gas oil, light and heavy domestic furnace oils, diesel fuels, and distillates used for cracking to produce more gasoline. These distillates are used mainly for transportation fuels in heavy trucks, railroads. small commercial boats, standby and peak-shaving power plants, farm equipment, and wherever diesels are used to produce power. Home heating furnaces use these distillates.
中间馏分。这些包括汽油，轻的和重的家用燃油，柴油和用来裂化生产裂化汽油部分的馏分，这些中间馏分主要用于交通燃油，像大卡车，火车，小型商船，备用发动机动力装置，农用机械，不论在哪，柴油都是用于生产动力，家用燃料也是用的这一馏分。
Heavy distillates. These are convened into lubricating oils，heavy oils for a variety of fuel uses, waxes, and cracking stock.重馏分。这一馏分被转化成润滑油，用于各种燃料的重油，蜡和抗暴成分。
Residues. Some constituents are simply not volatile enough to be distilled, even under vacuum These include asphalt, residual fuel oil, coke, and petrolatum. These difficult salable materials are by-products of the refining process, and while many are extremely useful, most are difficult to dispose of and are relatively unprofitable.
渣油。即使是在减压情况下，有一些组分也是不易发挥，不能被蒸馏。这些包括沥青，渣滓燃料油焦油和石蜡油。这些在精加工过程中的副产品是很难畅销的，但同时许多却非常有用，大多数很难处理并且利润相对少。
Petroleum-derived chemicals, commonly known as petrochemicals, are made from petroleum and natural gas. Production of some of these products is very large, and over 1000
organic chemicals are derived from petroleum. Examples are carbon black butadiene, styrene, ethylene glycol, polyethylene, etc.
源自石油的化学品通常称为石油化学品，是生产于石油和天然气。一些生产这些产品的规模是非常大的，超过1000种有机化学品是来源于石油。例如，炭黑，丁二烯，苯乙烯，乙烯，乙二醇，聚乙烯等
3．Processing or Refining 3.加工或精制
Refining involves two major branches, separation processes and conversion processes. Particularly in the field of conversion, there are literally hundreds of processes in use, many of them patented. Even in a given refinery running a single crude, daily changes to accommodate changing markets and changing parameters of the conversion apparatus take place. No refinery on any day will operate exactly as shown, but all refineries will operate along the basic lines indicated.
精致主要包括两个过程, 分离过程和转化过程。特别是在转化过程中, 上百种的工艺过程中, 上百种的工艺过程在实际中被采用, 许多工艺都是专利，即使是一个炼油厂只加工一种原油，每天产品也会发生变化以适应市场的变化并改变转化过程设备的操作参数。没有任何一个炼油厂会按着规定来进行操作，但是所有的炼油厂都是按着基本生产线进行操作的。
Separation processes. The unit operations used in petroleum refining are the simple, usual ones, but the interconnections and interactions may be complex. Most major units are commonly referred to as stills. A crude still consists of heat exchangers, a furnace, a fractionating tower, steam strippers, condensers, coolers, and auxiliaries. There are usually working tanks for temporary storage at the unit; frequently there are treating tanks, used for improving the color and removing objectionable components particularly sulfur; blending and mixing tanks; receiving and storage tanks for crude feed; a vapor recovery system; spill and fire control systems; and other auxiliaries．For the refinery as a whole, a boiler house and usually an electrical generating system are added. A control room with instruments to measure, record, and control, thus keeping track of material which permits heat and material balances, forms the heart of the system. One of the major functions of the instruments is to permit accurate accounting of the materials and utilities used.
分离过程。石油精致操作时很简单的的，这通常指但单一操作间的连接和相互作用是很复杂的。大多数装置通常指的是釜。一个原油釜包括换热器，炉子，分馏塔，蒸汽解吸塔，冷凝器，冷却器和附属设备。通常用一些储罐来进行临时储存；通过处理蒸汽以改变颜色和去除有刺激性气味的元素，特别是硫；混合罐；接受并储存罐进行简单培育；蒸汽回收体系；防爆和消防控制系统；和其他辅助设备。随着精致加工的普及，锅炉房通常是电力系提供提供动力装置。 一个控制室包括测量，记录和控制，因此能追踪并维持热平衡以及物料平衡，它组成了这个系统核心，其装置最主要的功能是维持原料和产物之间的平衡进行回收和利用。
Conversion Processes. About 70 percent of the crude processed is subjected to conversion processing both carbonium ion and free radical mechanisms occur. The presence of catalysts, the temperature, and pressure determine which type predominates. The following are examples of the more important basic reactions which occur: cracking or pyrolysis, polymerization, alkylation, hydrogenation, hydrocracking, isomerization, and reforming or aromatization.
转化过程。大约70%的缘由要加工都要经历包括正碳离子机理和自由基机理的转化过程。催化剂，温度和压力等条件将决定上述哪种类型机理将占主要地位。一些主要的基本反应有：裂解或热解，聚合，烷基化，加氢作用，降价清；裂化，异构化以及重整或芳构化。
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 operation 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 that 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
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