简答题

翻译篇章B    炼化专业

A petroleum refinery is a manufacturing operation where crude oil is converted into usable finished products. In other words, it is the manufacturing phase of the oil industry. The methods used to refine crude oil are quite different. However, basically, all refining processes can be divided into four basic categories.

The first category is fractionation or distillation. This is a method we use to separate a mixture of compounds and "cut" them into fractions. These fractions are then further processed in the following refinery operations.

The second basic type of process is to chemically transform certain of these "cuts" into products of higher commercial value. There are many ways of doing this, but there is only one purpose. That is to change the molecular structure of the components by using certain processes, for example, catalytic reforming. 

The third basic category is treating. It removes the unwanted components, or convert them into less undesirable compounds. Sulfur is perhaps the commonest and most troublesome of the impurities found in petroleum. 

The fourth basic category is blending of the finished cuts into final products such as motor gasoline, kerosene, lubricating oils, and bunker fuel oil. These four basic categories form the fundamental operation of a refinery.