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I would like to learn about the usage of Pyrolysis oil produced from Ethylene Cracker in the Delayed Coker Unit. I would like to use this pyrolysis oil which is around 2.5 wt% of total feed as a feed in the Delayed Coker Unit. Do you know any applications like this? If it is, have you encountered any issue to process pyrolysis oil to the coker unit?

In addition, what if I use this pyrolysis oil as wash oil stream in the coker fractionator column instead of using as a feed? Do you know any applications or example?

Oct-2023

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Imran Malik, www.Qchem.com.qa, immalik@qchem.com.qa

Question part: What if I use this pyrolysis oil as wash oil stream in the coker fractionator column instead of using as a feed? Do you know any applications or example?

At our site we use this Pyrolysis Oil as Wash oil in Quench tower, where it works wonders against tar, and keeps system exchangers fouling factor low, besides keeping tower packing clean. Higher dosage although has to be avoided for various other Cracker operations constraints.

May-2024
N Sekar Murthy, Ashphil Consultancy, nssvdvr@gmail.com

Sending pyrolysis oil via coke drum vapour line can be even more problematic in my view with high level of asphaltenes in it. The Coke drum overhead vapour line is normally quenched by HCGO PA stream which is practically has no asphaltenes or even high boiling resins. Hence, I would not try. I am told of a refinery used pyrolysis oil successfully in FCC riser and it added to coke starved unit. One can try it too. Good luck.

Nov-2023
SECIL UZUN, KBC PROCESS TECHNOLOGY, secilgunaydin@hotmail.com

Many thanks for your answer. My other question is the similar. This pyrolysis oil is a small amount which is around 2% of the total coker feed and what happens if I use this oil as a quench oil for coke drum overhead line. I can give this oil via Blowdown tower and directly to the coke overhead line. Can I encounter the same issues? Do you have any suggestions?

Nov-2023
N Sekar Murthy, Ashphil Consultancy, nssvdvr@gmail.com

The pyrolysis oil from naphtha cracker has high aromatics content along with significant amount of n-hexane insoluble's (i.e. asphaltenes). Hence, using this in Coker specially in wash oil section of the fractionator needs to be avoided to prevent precipitation of asphaltenes on the shed trays. Also, it will be worth looking at compatibility of pyrolysis oil with feed of Coker (i.e. short residue) which has a fair level of paraffin wax. However processing of 100% pyrolysis oil in coker for producing needle coke or anode grade coke is a possibility.

Nov-2023
Marcio Wagner da Silva, Petrobras, marciows@petrobras.com.br

The pyrolysis oil from steam cracking units can be an attractive feed for delayed coking units, especially for those dedicated to producing high quality needle coke due to the high aromaticity of the pyrolysis oil. Despite this advantage, the participation of this stream in the feed can be limited due to the high potential of coke lay down in the fired heaters which will reduce the operational campaign of the processing unit like quoted in the que question.

Despite being a relatively common feed for delayed coking units, unfortunately I don't have experience in operating delayed coking units with this feedstream, but the main side effect can be the acceleration of the coke deposition in the fired heaters which demands sensibility analysis to determine the maximum participation of the pyrolysis oil in the feed in order to balance the economic return between the pyrolysis oil advantages (needle coke production, for example) with the shorter operational life cycle of the processing unit.

About the use of pyrolysis oil as wash oil stream in the main fractionator, my point of view is that the pyrolysis oil is much heavy to this service and tends to raise the coking rates in the fractionating and thermal exchanges beds which will reduce the operational life cycle of the delayed coking unit or, at least, reduce the performance of the processing unit.

Oct-2023