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Our FCC has a throughput of 1900 Ton per Day. The total gas make of the plant is 24 wt %. The Gasoline make of the Unit is 52 wt %. There is a recycle stream of 8 % from the main column bottom. The Reactor design is having a T type disengager with Rough cut Cyclones. The Riser Outlet Temperature is 496 deg C.
We would like to process 5% Atmospheric Residue (AR) in the FCC. Please give a possible implications for processing AR and steps to be taken for processing the same.
 
Answers
15/03/2010 A: Snehamoy Halder, Bharat Petroleum Corporation Limited, sneha123moy@yahoo.co.in
Implications are given below:-
1.Your existing catalyst may not able to 5% Atmospheric Resdue. Therefore you may require to change the existing catalyst.
2. You did not mention the Capacity of your FCC. However you may need to check MAB capacity to burn extra coke due extra 5% Atmospheric Resdue and its high CCR which depends on Crude quality and Crude unit operation.
3.There will be some temperature hike in Regenerator. Therefore, whole regenerator air grid to cycloe, Orifice chamber bottom, DDSV,SCSV,RCSV slide valve, all the expansion below design is to be check before going for 5% AR in your FCC.
4.Dry Gas formation is expected to be high. Therefore, you to check your WGC capacity and flooding velocity of your top portion of the Main column as well as PSV & RV's higher set pressure may require.
5.With this 5% AR, higher corrosion protection is expected at the main column over-head area.
23/02/2010 A: Virendra Kapoor, Petroleum Refining Consultants, vkkapoor9@yahoo.com
I agree with Mr. Saidalu's observations. Regenerator, MAB and WGC should be examined not to offer any constraints
19/02/2010 A: PRAVEEN SUTHAR, Honeywell, praveen_cfcl@yahoo.co.in
Many times it is not desirable to add atmospheric tower bottom for FCC cracking. ATB have the higher metal contents and the little amount of metal in feed may will increase light gas by by enormous amount, causing the wet gas compressor to come to limit and reducing the plant load. Also the zeolite structure of the catalyst is going to be damaged.
If the atb is having very less metals, then to crack that, you may land up in less conversion. To cope up with this, we may have to increase the matrix content of the catalyst and for the exact composition, it is better to take the advise of catalyst vendor for proper composition.
01/06/2009 A: Sandeep Kaur, Indian Oil Corporation Limited, KAURS@indianoil.in
Atom residue has high metal content and high ccr (conardson carbon number) values.High ccr of feed can lead to high regenerator temperature. High regenerator temp can be controlled by increasing the catalyst circulation rate which can be achieved by reducing the feed preheat and for high metal content, to maintain the activity of system catalyst, fresh catalyst addition rate may have to increase further up. If your unit has no constraint for handing feed having higher ccr and metal content, then there is no as such implication for processing AR.
13/04/2009 A: Saidulu G, IOCL, saidulug@iocrd.co.in
It is not clear what is your objective of processing AR. T'put maximisation? Whether any gas handling contratints? Coke burning limitation?
Overall, I suggest you replace recyclone with AR. If it is partial burn mode, I suggest you don't use recycle slurry. Instead, push more fresh feed. It can be any virgin feedstock as it is more crackable than recycled. In your case, conversion should increase, provided the feed nozzle performance is good.