An Introduction to Distillation
蒸餾概述
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、石油煉制即將石油分離成各種餾分，然后將這些餾分經過處理，制成各種石油產品。大部分石油產品，包括煤油、燃料油、潤滑油和石蠟，都是原油經過處理去掉不需要的成分而得到的石油餾分。其他石油產品，如汽油、芳烴溶劑、甚至包括有些瀝青，則是通過完全或者部分合成而制造的。因為組成這些產品的物質成分無法通過直接分離原油獲得，而是通過化學反應過程，從原油中選定某些成分并改變其分子屬性而獲得的。換言之，它們是通過煉制得到的，或稱為煉制產品。
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、石油煉制包含一系列復雜的過程。通過這些過程，石油原料最終轉化成為可銷售的產品。這些產品在質量上符合人類需要，而更重要的是它們在數量上符合市場要求。
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、實際上，煉油廠從根本上說是一組生產裝置，其數量根據生產產品的不同而不同。煉油工藝須經選擇，產品生產應該平衡：即從原油生產產品必須依據每一產品的銷售速度而進行。比如，從沸點較低的組分生產石油產品，就會自動產生一定數量的高沸點產品。如果高沸點產品，如重燃料油，無法銷售，這些產品就會積壓，直到裝滿煉廠的儲存設施。要避免這種情況出現，煉廠應采取靈活措施，并能夠根據需要改變操作。一般而言，這意味著需要更多的工藝以適應不斷變化的市場需求：運用裂化工藝將過剩重燃料油轉化成汽油，而焦碳成為殘余品；或者運用真空蒸餾工藝將重油分解成潤滑油和瀝青。
4.In addition, a complete refining installation must include the following: all necessary non-processing facilities; adequate tankage for storing crude oil, intermediate, and finished products; a dependable source of electrical power, material-handling equipment; workshops and supplies for maintaining a continuous 24 h/day, 7 day/week operation; waste disposal and water-treating equipment; and product-blending facilities.
4、此外，一套完整的煉油裝置須包括以下設備：所有必須的非工藝設施：足夠的儲罐容量用以儲存原油、中間產品和成品；可靠的電力和物質處理設備來源；用于維持一天24小時，一周七天連續(xù)運轉所需的車間和物資：廢料和污水處理設備；以及產品調合設施。
5. In the early stages of refinery development, when illuminating and lubricating oils were the main products, distillation was the major and often only refinery process. At that time, gasoline was a minor, but more often unwanted, product. As the demand for gasoline increased, conversion processes were developed because distillation could no longer supply the necessary quantities.
5、在早期煉油工業(yè)發(fā)展過程中，照明用油和潤滑油是主要的產品，蒸餾則成了主要的甚至經常是唯一的煉油工藝。當時，汽油本身盡管不是重要產品，但也常討人嫌。隨著市場對汽油需求的增加，產品轉化工藝隨之發(fā)展，因為蒸餾已不能滿足對汽油的數量需求。
6. Nevertheless, distillation has remained a major refinery process and a process to which just about every crude that enters the refinery is subjected. A multitude of separations are accomplished by distillation, but its most important and primary function in the refinery is its use for the separation of crude oil into component fractions.
6、但是，蒸餾仍然是重要的煉油工藝，而且所有原油進入煉廠都必須經過蒸餾。許多分離過程是通過蒸餾進行的，但蒸餾在煉油廠中的最重要和主要的功能則是它在將原油分離成不同餾分過程中的作用。
7. Thus it is possible to obtain products ranging from gaseous materials taken off the top of the distillation column to a heavy residue or “bottom”, which is usually nonvolatile, with correspondingly lighter materials taken off at intermediate points. However, the majority of crude oils, and this applies to the heavier, more viscous petroleums, which are processed by distillation, are usually separated into the lighter fractions （gas, gasoline, naphtha, kerosene, and gas oil） and the bottom or, as it is more generally called, the reduced crude.
7、由此，我們有可能獲得石油產品，這些產品包括從蒸餾塔頂部得到的氣態(tài)物質，包括比重較大的渣油或稱“殘渣”（一般而言揮發(fā)性較差），以及從蒸餾塔中部得到的比重較小的其他相應物質。但是，經過蒸餾處理的大多數原油，包括比重較大、粘度更大的原油，一般都分離為較輕組分（氣、汽油、粗汽油、煤油和粗柴油）和殘渣，或者更多稱作常壓重油。
8.The reduced crude may then be processed by vacuum or steam distillation to separate the high-boiling lubricating oil fractions without the danger of decomposition, which occurs at high （>350℃, 660℉） temperatures. Indeed, atmospheric distillation may be terminated with a lower boiling fraction （“cut”） if it is thought that vacuum or steam distillation will yield a better quality product or if the process appears to be economically more favorable.
8、然后，通過真空蒸餾或蒸汽蒸餾，常壓重油可以分離成高沸點潤滑油組分而沒有分解的危險。這種分離在高溫狀態(tài)下進行（>350℃，660℉）。如果認為真空蒸餾或蒸汽蒸餾生產的產品質量更好，或者從經濟角度看更為有利，則低沸點組分分離出來后，常壓蒸餾即可結束。
