Скачать или смотреть Fluid Catalytic Cracking - FCC

“Gasoline hart” of Refinery, transform lower feeds in valuable products with an increase in volumetric flow rate, meaning that for each 1 (one) m3/h of feed shall result 1.1 m3/h of products – roughly 10% and for 100$ / m3 of feed come out 150$/m3 of products!

FCC main equipment:

1. Air Blower: centrifugal or axial type with turbine / electric motor, need to supply 250-550 Nm3 of air per m3 of feed with check valve on discharge who need to protect the machine for regenerator catalyst backflow, remember that in Regenerator the operating temperature could arrive at +700C, internals shall be SS

2. Regenerator operating pressure 2.8-3.6 barg & 690-750C need to burn the coke deposits on catalyst:

C + O2 — CO2 + Q (heat) = 7860 kcal/kg
C + ½ O2 — CO + Q (heat) = 2200 kcal/kg
CO + ½ O2 — CO2 + Q (heat)

Note that total combustion of coke to CO2 could be started by adding excess air or a special promoter, do not exceed 2% vol. of O2 in flue gases.

Remember that working with total combustion the coke deposits on catalyst shall be minimum, the T highest meaning that the catalyst circulation rate.

3. Reactor: so called “riser” a vertical tube where the fresh feed is well mix with regenerated catalyst, also steam is added to improve the mixing and atomization with operating pressure of 1.5-2.5 barg & 525-560C, transform the low value feed in desire products by various operation modes: max gasoline, max olefins or distillates

4. Slide valves are gate type with main goal to control the catalyst flow rate and due to catalyst fine particles presence, special construction is required with / without steam purging to avoid catalyst accumulation - the main issue is to resist to higher thermal expansion when becomes in contact with hot catalyst, meaning that the vendor shall proper design the clearances

5. Cyclones to remove/recover the catalyst particles from reactor effluent and flue gases using the centrifugal forces & high weight difference between catalyst particles and gas effluent

6. Orifice chamber is a vertical column with orifice trays with main purpose to reduce the flue gases velocity and pressure drop to near atmospheric value – from total pressure drop of flue gases 2/3 is lost in orifice chamber the remaining in the slide valve upstream

7. Main Column with 38-42 real trays and different sections with own efficiency is used to separate the reactor effluent in gases, gasoline, light & heavy cycle oil and the remaining heavy portion as column bottom product, with 1.0 barg & 120C at top and 2.0 barg/363C in bottom. It is worth to mention the disc & donut section from column bottom where the huge heat transfer take place by returning the cooled bottom product above top disc, the mentioned internals are suitable for plugging by catalyst fines and/or coke service.

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