höyrykrakkausta

Höyrykrakkaus, also known as steam cracking, is a petrochemical process used to break down heavy hydrocarbon molecules into smaller, more useful ones. This is achieved by heating the hydrocarbons to high temperatures, typically between 750 and 950 degrees Celsius, in the presence of steam. The steam acts as a diluent and helps to reduce the formation of coke, a carbonaceous residue.

The primary feedstocks for steam cracking are naphtha, gas oils, and ethane. The process is carried out in cracking furnaces, which consist of large tubes that are heated externally. The hydrocarbon feedstock and steam are fed into these tubes and rapidly heated. The high temperatures cause the hydrocarbon molecules to break apart, or crack, into a mixture of smaller hydrocarbons, including olefins such as ethylene, propylene, and butenes, as well as byproducts like hydrogen and methane.

Following the cracking stage, the product stream is rapidly cooled to stop further reactions. This is followed by a complex series of separation and purification steps, typically involving distillation, to isolate the desired products. Ethylene is the most important product of steam cracking and is a fundamental building block for the plastics industry, used to produce polyethylene. Propylene is another key product, used in the production of polypropylene and other chemicals. Butenes are also valuable, used in the synthesis of synthetic rubber and other chemicals. Steam cracking is a cornerstone of the petrochemical industry, providing essential raw materials for a vast range of consumer and industrial products.