Innovative programmes for the petrochemical industry

Coke Inhibition in Cracking Processes.

Thermal cracking of gaseous and liquid hydrocarbons is the leading technology for the production of ethylene. Common feedstocks such as ethane, propane, butane, naphtha, gas oil or hydrocracker residues are fed to the cracking furnace in the presence of steam. This gas-phase reaction is called steam cracking or pyrolysis, where the ethylene production is a very complex process followed by cooling, compression and separation steps. Coking is a side reaction from thermal cracking. It is a major operational problem in the radiant section of steam cracking furnaces and transfer line exchangers.

In many cases catalytic coke formation is caused by nickel and sodium in the feed to the cracking furnaces. A continuous injection of a sulfiding agent such as DMS or DMDS is the historical method for coke reduction and controlling carbon monoxide formation. Kurita has many years of experience with the injection of polysulfides, which have significant advantages in comparison to DMS or DMDS. Our polysulfides reduce the formation of undesired carbon monoxide (CO) and significantly extend the run time of the cracking furnaces.

Kurita´s polysulfides are classified as non-hazardous and require no special handling and storage. The high flash point of about 100°C reduces the risk of potential flash fires, while the low sulfide odor, which is similar to gas oil, does not have to be masked with odorants to cover up bad odors. Reduced material stress and low decoking times of the furnaces are further advantages of our chemical treatment.

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