Fluid Catalytic Cracking for Maximum Olefins Process by Lummus Technology

The Indmax FCC (I-FCC) process cracks a wide range of feedstocks into light olefins. Feedstocks include virgin or hydrotreated gasoil that may include lube oil extract, coker gasoil and resid.

The I-FCC unit is designed for and operated at Indmax process conditions: riser reactor temperature from 560°C to 600°C, catalyst-to-oil ratio from 12 to 20, and lower hydrocarbon partial pressure compared to conventional FCC operations. The I-FCC process incorporates an advanced reaction system, high-efficiency catalyst stripper and a mechanically robust, single-stage fast fluidized bed regenerator. Oil is injected into the base of the riser via proprietary Micro-Jet feed injection nozzles (1). Catalyst and oil vapor flow upwards through a short-contact time, all-vertical riser (2) where raw oil feedstock is cracked under optimum conditions.

Reaction products exiting the riser are separated from the spent catalyst in a patented, direct-coupled cyclone system (3). Product vapors are routed directly to fractionation, thereby eliminating nonselective, post-riser cracking and maintaining the optimum product yield slate. Spent catalyst containing only minute quantities of hydrocarbon is discharged from the diplegs of the direct-coupled cyclones into the cyclone containment vessel (4). The catalyst flows down into the stripper containing proprietary modular grid (MG) baffles (5).

Trace hydrocarbons entrained with spent catalyst are removed in the MG stripper using stripping steam. The MG stripper efficiently removes hydrocarbons at low steam rate. The net stripper vapors are routed to the fractionator via specially designed vents in the direct-coupled cyclones. Catalyst from the stripper flows down the spent-catalyst standpipe and through the slide valve (6). The spent catalyst is then transported in dilute phase to the center of the regenerator (8) through a unique square-bend-spent catalyst transfer line (7). This arrangement provides the lowest overall unit elevation. Catalyst is regenerated by efficient contacting with air for complete combustion of coke. For resid-containing feeds, the optional catalyst cooler is integrated with the regenerator. The resulting flue gas exits via cyclones (9) to energy recovery/flue gas treating. The hot regenerated catalyst is withdrawn via an external withdrawal well (10). The well allows independent optimization of catalyst density in the regenerated catalyst standpipe, maximizes slide valve (11) pressure drop and ensures stable catalyst flow back to the riser feed injection zone.

Products: Light olefins (principally propylene, but also ethylene and butylenes), high-octane gasoline, blending components, and distillate. Flexibility of unit operation allows for maximizing propylene, propylene plus ethylene, or propylene plus gasoline.

Catalyst: The Indmax catalyst is a unique, proprietary, multi-component, multi-functional catalyst formulation that promotes selective component cracking to provide very high conversion and yield of light olefins. It is highly metals-tolerant and produces low delta coke and dry gas – properties that are particularly important when processing residue to make light olefins.

Licensor: Lummus Technology, a CB&I company.

Leave a Reply

Your email address will not be published. Required fields are marked *