第三部分UNIT 1 Composition of Petroleum石油的组成Petroleum or crude oil is a naturally occurring, toxic, flammable liquid consisting of a complex mixture of hydrocarbons of various molecular weights, and other organic compounds, that are found in geologic formation s beneath the Earth’s surface.. Petroleum is recovered mostly through oil drilling. It is refined and separated, most easily by boiling point, into a large number of consumer products, from gasoline and kerosene to asphalt and chemical reagent s used to make plastics and pharmaceutical s.石油或原油是天然形成的、有毒的、可燃性的液体，是含有不同分子量的碳氢化合物以及其它有机化合物的复杂混合物。
它是在地球表面下的地址层中发现的。
石油大部分是通过石油钻探开采得到的。
石油很容易按不同馏程进行炼制和分离成为大量的消费产品，从汽油、煤油到沥青以及用作制造塑料和药品的化学试剂。
In its strictest sense, petroleum includes only crude oil, but in common usage it includes both crude oil and natural gas. Both crude oil and natural gas are predominantly a mixture of hydrocarbons. Under surface pressure and temperature conditions, the lighter hydrocarbons methane, ethane, propane and butane occur as gases, while the heavier ones from pentane and up are in the form of liquids or solids. However in the underground oil reservoir the proportion of gas and liquid varies depending on the subsurface conditions, and on the phase diagram of the petroleum mixture.严格意义上说，石油仅仅包含原油，但是在惯用法上，它包含石油和天然气。
石油和天然气主要是烃类混合物。
在地球表面压力和温度条件下，轻质的碳氢化合物甲烷、乙烷、丙烷和丁烷以气体的形式出现，而重质的碳氢化合物如戊烷和重于戊烷的烃都是以液体的形式出现。
然而，在地下油藏。
气体或液体的比例变化取决于亚地表层条件和石油混合物的相图。
An oil well produces predominantly crude oil, with some natural gas dissolved in it. Because the pressure is lower at the surface than underground, some of the gas will come out of solution and be recovered (burned) as associated gas or solution gas. A gas well produces predominately natural gas. However, because the underground temperature and pressure are higher than at the surface, the gas may contain heavier hydrocarbons such as pentane, hexane, and heptane in the gaseous state. Under surface conditions these will condense out of the gas and form natural gas condensate, often shortened to condensate. Condensate resembles gasoline in appearance and is similar in composition to some volatile light crude oil.油井主要生产原油，伴有一些天然气溶解在其中。
因为地表的压力低于低下的压力，一些气体将从溶液中溢出，或者以伴生气或溶解气被回收（或燃烧）。
气井主要产生天然气。
然而，由于地下温度和压力比地表面高一些，气体中或许含有较重的碳氢化合物，例如气态的戊烷、己烷和庚烷。
在地表条件下，这些较重的碳氢化合物将会从气体中析出，形成天然气的凝聚物，经常简称为凝析油。
凝析油外观上类似于汽油，组成上类似于一些挥发性的轻原油。
Exercise: 汉译英任何石油产品中，都不希望硫的含量高，柴油也不例外。
对于这些燃料油，人们声称硫加剧了磨损和沉积物的问题，但对其产生的后果的大小仍有争议。
不过，不管对柴油要求的低硫含量有无技术上的理由——对于减少空气污染这个道理是不辩自明的。
生成模式已经确立，炼油厂必须接受这一规定。
正因为如此，许多炼油厂通常安装有粗柴油加氢脱硫的工艺装置。
In any petroleum product, a high sulphur content is considered undesirable, and diesel fuels are no exception. For such fuels, sulphur is claimed to aggravate problems of wear and deposits, but the magnitude of the effect is still a matter of some controversy. However, whether or not there is technical justification other than that of abatement of air pollution – for the low sulphur levels demanded for diesel fuels, the pattern has been established and must be accepted by the refiner. For this reason, processing units for the hydrodesulphurization of gas oils are commonly installed in refineries.UNIT 2 Petrochemicals石化产品Petrochemicals are generally chemical compounds derived from petroleum either by direct manufacture or by indirect manufacture as by –products from the variety of processes that are during the refining of petroleum. Gasoline, kerosene, fuel oils, lubricating oils, waxes, asphalts, and the like are exclud ed from the definition of petrochemicals, since they are not, in the true sense, chemical compounds but are in fact intimate mixtures of hydrocarbons.石化产品通常指直接或间接从石油中提炼的化合物，这些化合物往往是石油炼制各种过程中产生的副产品。
汽油、煤油、燃料油、润滑油、石蜡、沥青以及诸如此类的产品不属于石化产品。
因为，从严格意义上说，它们不是化合物，而是(性质相近的)烃类的混合物。
The classification of materials such as petrochemicals is used to indicate the source of the chemical compounds, but it should be remembered that many common petrochemicals can be made from other sources, and the terminology is therefore a matter of source identification.像“石化产品”这样的物质分类用来表明化合物的来源。
但应记住，许多我们所熟知的石化产品也可以通过其它途径生产，因而这一术语只用来识别原料的来源。
The manufacture of chemicals from petroleum is based on the ready response of the various compound type to basic chemical reactions, such as oxidation, halogenation, nitration, dehydrogenation, addition, polymerization, and alkylation. The low-molecular-weigh paraffins and olefins, as found in natural gas and refinery gases, and the simple aromatic hydrocarbons have so far been of the most interest because it is these individual species that can readily be isolated and deal with. A wide range of compounds is possible, many are being manufactured, and we are now processing the stage in which a sizable group of products is being prepared from the heavier fractions of petroleum. For example, the carious reactions of petroleum heavy ends, in particular the asphaltenes, indicate that these materials may be regarded as chemical entitied and are able to participate in numerous chemical or physical as conversions to, perhaps, more useful materials. The overall effect of these modifications is the production of materials that either afford good-grade aromatic cokes comparatively easily or the formation of bearing functional groups that may be employed as a nonfuel material.丛石油生产化学品是基于各种类型的化合物对各种基本化学反应响应迅速，如氧化反应、卤化反应、硝化反应、脱氢反应、加成反应、聚合反应和烷基化反应。