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We operate one of the largest cokers in the world and are keen to increase the distillate yield. There is lots of information currently floating around wrt concepts like 'zero recycle', use of additives to reduce coke yield, recycling of LCGO to recover distillates, etc. As zero recycle is promising, our questions are:-
1. Yield improvement obtained with zero recycle?
2. Quality of HCGO post implementation of zero recycle wrt Metals, CCR, particulates, etc.
3. Destination of any extra heavier HCGO stream (from main fractionator bottom) along with quality of this stream.
4. Any issue wrt reliability of the plant post zero recycle option.
 
Answers
21/10/2009 A: Eric Vetters, ProCorr Consulting Services, ewvetters@yahoo.com
I suggest that you contact the ConocoPhillips Coke Licensing group. They should be able to answer your questions on zero recycle as well as distillate recycle. You can reach them through the ConocoPhillips website. The link is found in Downstream Technologies in the Technologies & Innovation portion of the site.
With zero recycle you can expect a significant improvement in yields, with a corresponding decrease in gas oil quality. Where you route the flash zone gas oil stream will depend on your refinery configuration and constraints. Reliability impacts will depend on how you design the zero recycle system and where the flash zone gas oil is being routed.