How an Oil Refinery Works

炼油厂是如何运作的

Though wind and solar continue to carve out larger and larger shares of world energy supply, the modern world still runs on petroleum, and will continue to do so for the foreseeable future. The world consumes over 100 million barrels of oil a day. As of 2023, oil was responsible for 30% of all energy use worldwide, higher than any other energy source (though its share has been gradually falling). In chemical manufacturing, petroleum is even more critical: an astounding 90% of chemical feedstocks are derived from oil or gas. Virtually all plastic comes from chemicals extracted from oil or gas, and petrochemicals are used to produce everything from lubricants to paint to plywood to synthetic fabrics to fertilizer.

尽管风能和太阳能继续在全球能源供应中占据越来越大的份额，但现代世界仍然依赖石油，并且在可预见的未来仍将如此。全球每天消耗超过 1 亿桶石油。截至 2023 年，石油占全球能源使用量的 30%，高于任何其他能源（尽管其份额一直在逐渐下降）。在化学制造业中，石油更为关键：令人震惊的是，90% 的化学原料来自石油或天然气。几乎所有的塑料都来自从石油或天然气中提取的化学品，而石油化工产品被用于生产从润滑剂、油漆、胶合板到合成纤维和化肥等各种产品。

Our enormous consumption of petroleum is made possible by oil refineries. When oil comes out of the ground, it’s a complex mixture of thousands of different chemicals. Oil refineries take in this mixture and process it, turning it into chemicals we can actually use. Because of the scale of worldwide petroleum consumption, oil refineries are some of the largest industrial facilities in the world. A large oil refinery will occupy thousands of acres and cost billions of dollars to construct, ultimately refining hundreds of thousands of barrels of oil each day.

我们对石油的巨大消耗离不开炼油厂。当石油从地下开采出来时，它是一种由数千种不同化学物质组成的复杂混合物。炼油厂接收这种混合物并对其进行加工，将其转化为我们实际可以使用的化学品。由于全球石油消费的规模，炼油厂是世界上规模最大的工业设施之一。一座大型炼油厂占地数千英亩，建设成本高达数十亿美元，最终每天可提炼数十万桶石油。

Crude oil basics

原油基础知识

Oil is a liquid produced from decomposing organic materials, mostly plankton and algae that died and sank to the bottom of ancient oceans. This dead organic matter gradually got covered with sediment, and over millions of years it transformed into crude oil. Crude oil is a mixture of thousands of different chemicals, most of which are hydrocarbons: molecules that are various arrangements of carbon and hydrogen atoms. The molecules in crude oil range from the simple, such as propane (three carbons and eight hydrogens) and butane (four carbons and ten hydrogens) to the complex — some asphaltene molecules in crude oil can contain thousands of individual atoms.

石油是由腐烂的有机物质产生的液体，主要是死亡并沉入古代海洋底部的浮游生物和藻类。这些死亡的有机物质逐渐被沉积物覆盖，经过数百万年的时间转化成了原油。原油是数千种不同化学物质的混合物，其中大部分是碳氢化合物：即由碳原子和氢原子以各种方式排列而成的分子。原油中的分子从简单的（如丙烷，含三个碳原子和八个氢原子；丁烷，含四个碳原子和十个氢原子）到复杂的应有尽有——原油中的一些沥青质分子甚至可以包含数千个独立原子。

Crude oils extracted from different parts of the Earth will have different mixtures of hydrocarbons and other molecules, which has given rise to a sort of crude oil taxonomy. “Heavy” crude oils, found in places like Canada’s oil sands, will have more heavy molecules, while “light” crude oils found in places like Saudi Arabia’s Ghawar field will have more light molecules. “Sweet” crudes, like the crudes extracted from the Brent oil field in the North Sea, have lower sulfur content, while “sour crudes,” like some of the crudes extracted from the Gulf of Mexico, have greater sulfur content.

从地球不同地区开采的原油具有不同比例的碳氢化合物和其他分子混合物，这产生了一种原油分类法。在加拿大油砂等地发现的“重质”原油含有更多的重分子，而在沙特阿拉伯加瓦尔油田等地发现的“轻质”原油则含有更多的轻分子。“甜”原油（如从北海布伦特油田开采的原油）硫含量较低，而“酸”原油（如从墨西哥湾开采的一些原油）硫含量较高。

The job of an oil refinery is to process this mixture of hydrocarbons and other molecules: separating the mixture into individual chemicals or groups of chemicals, and using various chemical reactions to change low-value chemicals into more valuable, useful ones.

炼油厂的工作就是处理这种碳氢化合物和其他分子的混合物：将混合物分离成单一的化学品或化学品组，并利用各种化学反应将低价值的化学品转化为更有价值、更有用的化学品。

Refinery basics

炼油厂基础

A refinery makes use of several different methods to separate and process crude oil, but the most important process of all is probably distilling. Different molecules within crude oil boil at different temperatures, and condense back into liquid at different temperatures. Smaller, lighter molecules boil and condense at lower temperatures, while larger and heavier molecules boil and condense at higher temperatures. You can describe this range of boiling points with a distillation curve, which shows what fraction of the crude oil boils at different temperatures.

炼油厂利用几种不同的方法来分离和加工原油，但其中最重要的工艺可能就是蒸馏。原油中的不同分子在不同的温度下沸腾，并在不同的温度下冷凝回液体。较小、较轻的分子在较低的温度下沸腾和冷凝，而较大、较重的分子则在较高的温度下沸腾和冷凝。你可以用蒸馏曲线来描述这种沸点范围，它显示了原油在不同温度下沸腾的比例。

Substances derived from crude oil are often mixtures of chemicals defined by their range of boiling points. Gasoline, for instance, isn’t just one chemical: it’s a mixture of hydrocarbons, mostly molecules with between four and 12 carbon atoms. The EIA defines finished gasoline as “having a boiling range of 122 to 158 degrees Fahrenheit at the 10 percent recovery point to 365 to 374 degrees Fahrenheit at the 90 percent recovery point.”

从原油中提取的物质通常是由其沸点范围定义的化学混合物。例如，汽油不仅仅是一种化学物质：它是碳氢化合物的混合物，主要是含有 4 到 12 个碳原子的分子。美国能源信息署（EIA）将成品汽油定义为“在 10% 回收点时沸程为 122 至 158 华氏度，在 90% 回收点时沸程为 365 至 374 华氏度”。

Oil refineries can use this range of boiling and condensation to separate crude oil into different groups of chemicals, or fractions, using a distillation column. When crude oil enters a refinery, the salt gets removed from it, and it’s then heated to around 650-750°F, which turns most of the oil into a vapor. The vapor is then fed into a tall column containing trays at different heights, each filled with liquid. As the hot vapor rises through the column, at each tray it passes through the liquid, which cools it slightly. When the vapor cools enough, it condenses back into liquid. The heaviest molecules with the highest boiling points condense first, at the bottom of the column, while the lighter ones condense last, at the top.

炼油厂可以利用这种沸腾和冷凝的范围，通过蒸馏塔将原油分离成不同的化学品组或馏分。当原油进入炼油厂时，其中的盐分会被去除，然后被加热到约 650-750°F，这使大部分石油变成蒸汽。蒸汽随后被送入一个高大的塔中，塔内不同高度设有托盘，每个托盘都装有液体。当热蒸汽上升通过塔时，它在每个托盘处穿过液体，液体会使其稍微冷却。当蒸汽冷却到足够程度时，它就会冷凝回液体。沸点最高的重分子首先在塔底冷凝，而较轻的分子最后在塔顶冷凝。

Essentially every oil refinery first distills crude oil into various fractions in a distillation column, though the exact fractions separated might vary from refinery to refinery. Because this distillation is done at atmospheric pressure, this first step in the refining process is referred to as “atmospheric distillation.” The simplest refineries might only do atmospheric distillation, but most refineries will then send these various fractions along for further processing.

基本上每家炼油厂都会首先在蒸馏塔中将原油蒸馏成各种馏分，尽管具体分离出的馏分可能因炼油厂而异。由于这种蒸馏是在大气压下进行的，炼油过程中的这一第一步被称为“常压蒸馏”。最简单的炼油厂可能只进行常压蒸馏，但大多数炼油厂随后会将这些不同的馏分送去进行进一步加工。