[Freddy Martinez]

In your case, an economic driver to increase feed is working against the unit reliability, so you should work very hard to demonstrate the unit reliability is in jeopardy before being able to convince your managers to reduce the feed rate.
 
The main risk is to prematurely erode the cyclones, which will cause high catalyst losses on the reactor side, high catalyst content on the slurry and a possible plug off of the slurry circulation. Erosion could be an issue on the reactor overhead line elbows or main column feed nozzle so watch for erosion on them too and if the safety is in jeopardy recommends against the feed increase. However, tracking erosion on this hot line is not easy, there are some companies like SES or Capstone, that might know about how to do this.
 
Eventually a shut down might be required to repair the damage if the economics show that the catalyst losses are to high to maintain the operation.
 
Finally, my recommendation is to give it a try but closely monitor all variables, specially those related to safety issues.

[Freddy Martinez]

We did that in the past succesfully, it all depends on the quality of the ATB you are charging to your Cat Cracking and how you handle it. In our case we were charging a parafinic ATB wich helps to increase the conversion to gasoline, its crackeability was very good.
 
We did that on a MW Kellogg design which has a high dense catalyst phase in the riser, which helps to reduce the impact of the higher concarbon fed to the unit. Additionally an good blend of the ATB and VGO is required for better results, otherwise batches of high concarbon material in the feed will cause major upsets in the catalyst circulation and possibly a unit shut down.
 
The economic driver for this operation was excellent, as our refinery did not have Delayed Coker and part of the ATB was send to bunker fuel production.

[Freddy Martinez]

Liz,
 
“Circuito de fondo” should be translated as ” Bottom circulation”, which is the stream coming out of the Main Fractionator Bottom handled by the “Bottom Pumps”
 
Hope it helps

[Author]

Posts