2019职称英语综合类阅读精选：An Introduction to Distillation

 　　An Introduction to Distillation 蒸馏概述

　　1. Petroleum refining is the separation of petroleum into fractions and the subsequent treating of these fractions to make them into petroleum products. Most petroleum products,including kerosenes,fuel oils,lubricating oils,and waxes,are fractions of petroleum that have been treated to remove undesirable components. Other products,for example,gasolines,aromatic solvents,and even some asphalts,are totally or partly synthetic in that they have compositions that are impossible to achieve by direct separation of these materials from crude petroleum. They result from chemical processes that change the molecular nature of selected portions of crude petroleum; in other words,they are the products of refining or they are refined products.

　　1、石油炼制即将石油分离成各种馏分，然后将这些馏分经过处理，制成各种石油产品。大部分石油产品，包括煤油、燃料油、润滑油和石蜡，都是原油经过处理去掉不需要的成分而得到的石油馏分。其他石油产品，如汽油、芳烃溶剂、甚至包括有些沥青，则是通过完全或者部分合成而制造的。因为组成这些产品的物质成分无法通过直接分离原油获得，而是通过化学反应过程，从原油中选定某些成分并改变其分子属性而获得的。换言之，它们是通过炼制得到的，或称为炼制产品。

　　2. Refining petroleum is a complex series of steps by which the original crude material is eventually converted into salable products with the desired qualities and,perhaps more important,in the amounts dictated by the market.

　　2、石油炼制包含一系列复杂的过程。通过这些过程，石油原料最终转化成为可销售的产品。这些产品在质量上符合人类需要，而更重要的是它们在数量上符合市场要求。

　　3. In fact,a refinery is essentially a group of manufacturing plants that vary in number with the variety of products produced; refinery processes must be selected and products manufactured to give a balanced operation: that is,crude oil must be converted into products according to the rate of sale of each. For example,the manufacture of products from the lower boiling portion of petroleum automatically produces a certain amount of higher boiling components. If the latter cannot be sold as,say,heavy fuel oil,they accumulate until refinery storage facilities are full. To prevent the occurrence of such a situation,the refinery must be flexible and able to change operations as needed. This usually means more processes-a cracking process to change an excess of heavy fuel oil into more gasoline with coke as the residual product or a vacuum distillation process to separate the heavy oil into lubricating oil stocks and asphalt-to accommodate the ever-changing demands of the market.

　　3、实际上，炼油厂从根本上说是一组生产装置，其数量根据生产产品的不同而不同。炼油工艺须经选择，产品生产应该平衡：即从原油生产产品必须依据每一产品的销售速度而进行。比如，从沸点较低的组分生产石油产品，就会自动产生一定数量的高沸点产品。如果高沸点产品，如重燃料油，无法销售，这些产品就会积压，直到装满炼厂的储存设施。要避免这种情况出现，炼厂应采取灵活措施，并能够根据需要改变操作。一般而言，这意味着需要更多的工艺以适应不断变化的市场需求：运用裂化工艺将过剩重燃料油转化成汽油，而焦碳成为残余品;或者运用真空蒸馏工艺将重油分解成润滑油和沥青。