What Is the Claus Process?

Mary McMahon
Mary McMahon

The Claus method is used by some companies to process hydrogen sulfide, a common component of crude oil and various refined products, to remove the sulfur. Sulfur is an undesirable component that must be removed before further processing and sale. Natural gas and other products with an unacceptably high sulfur component are known as “sour,” and the removal process is known as “sweetening.” Numerous refineries have the capability to subject products to the Claus method.

Man with a drill
Man with a drill

In this refinery technique, the sour gas is fed into a chamber where it can oxidize at very high temperatures before flowing into a cooler area, where a catalyst works to pull out more sulfur. The gas may go through three or more repeats of this process. At each stage, more and more sulfur is pulled out. A highly efficient refinery with three or four Claus process beds to treat sour gas can extract 97% or more of the sulfur.

Gas which has been mostly sweetened can pass through what is known as a tail gas unit to filter out additional sulfur. This results in gas with an extremely high quality at the end of the Claus process. It can be refined into various other components or sold as natural gas. Meanwhile, the extracted sulfur can also be used to produce an assortment of useful products. At refineries, the goal is to use as many components of crude oil as possible, to make processing cost effective.

Refineries can approach the Claus process in a number of ways. Some add features like pressurization to increase the extraction rate. Sweetening gas can be a lengthy process, and many firms use research and development to explore possible alternatives that may be more effective to implement. Refineries also need to consider environmental issues, as they do not want to cause pollution with the Claus process.

Workers supervise the Claus process and have access to equipment they can use to check on sulfur content and test for other impurities in the gas. The various impurities in crude explain the wide variety of ratings assigned to it upon extraction. More valuable crudes have fewer unwanted components, and may be known as light, sweet crudes to reflect this. Each added component requires additional processing and drives the value of the oil down because refineries need to spend more money to get usable gas and other products out of it. These heavier crudes may sell at much lower prices.

Mary McMahon
Mary McMahon

Ever since she began contributing to the site several years ago, Mary has embraced the exciting challenge of being a wiseGEEK researcher and writer. Mary has a liberal arts degree from Goddard College and spends her free time reading, cooking, and exploring the great outdoors.

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