Wash oil and emulsion breaker selection in ethylene production
Case history on resolving fouling challenges in the management of the separation and recycle of steam condensate and wash oil
Jorge Alfonso Garcia Mascareñas and Jorge Cabrera Braskem Idesa, S.A.P.I. Baltazar Suarez Vargas and Joice Gorete Boll Dorf Ketal Chemicals
E thylene serves as a fundamental building block in the production of plastics, synthetic fibres, detergents, ethanol, and numerous other chemicals. The process of ethylene production commences with the steam cracking of hydrocarbons, such as naphtha, natural gas, or ethane, at elevated temperatures within a cracking furnace. The subsequent series of processes downstream of the furnace must operate synergistically to yield products that meet specifications, minimise polymerisation, and efficiently recycle steam condensate and wash oil. In an era where sustainability is paramount, ethylene plants can mitigate risks, comply with regulatory requirements, enhance prof- itability, and, more importantly, contribute to constructing a more sustainable future for the global chemical industry. A joint effort between Dorf Ketal and Braskem Idesa to resolve fouling challenges in the management of the separa- tion and recycle of steam condensate and wash oil demon- strates the importance of selection of wash oil, chemical additives, and operating procedures that can assist other plants facing similar challenges. Unit description Braskem Idesa, in Coatzacoalcos, Mexico, is the largest ethane cracker in Latin America, with a capacity of 1,050 KTA, and is licensed by Technip design. The furnace, quench system, and first two stages of compression are shown in Figure 1 .
Problem background The plant encountered challenges with under-deposit cor- rosion in the dilution steam generator (DSG) system. The issue arose due to insufficient oil-water separation in the quench water (QW) loop upstream of the DSG and the resulting increased loading of hydrocarbons entering the DSG. During troubleshooting activities, it was understood that poor performance of the QW loop was a direct result of an oil-water emulsion created because of wash oil selection. CGC operational importance The need to enhance the performance of the cracked gas compressor (CGC) is growing as ethylene manufacturers aim to extend the run lengths of their cracker plants. Improved CGC performance also helps avoid unscheduled shutdowns, lower production rates, and higher energy costs, increasing plant reliability and profitability.1 To enhance performance, the following strategies are implemented generally: • Wash water : To regulate discharge temperature and mini- mise rates of polymerisation that can lead to fouling. • Wash oil : To dissolve low molecular weight oil-soluble polymers and transport them out of the system. • Additives : Incorporation of anti-polymerants to reduce cross-linking and minimise polymer molecular weight for wash oil efficiency, along with dispersants to help transport insoluble polymers.
Cracked gas to CGC 3rd stage
CGC 1st stage
CGC 2nd stage
Quench water tower
DS to furnace
Ethane
PWS
DSG
Coalescer
From 3-5th KO drums
2nd KO
Furnaces
1st KO
Blowdown
Flash drum
Oil/water
Light HC to storage
LPS
Water to quench water tower
Pre- lters Filters
Figure 1 Braskem Idesa partial block flow diagram
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PTQ Q3 2025
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