Selective conversion of gas oil feedstocks. Catalytic and selective cracking in a short-contact-time riser where…
Resid Catalytic Cracking Process by Shaw and Axens
Selective conversion of gasoil and heavy residual feed-stocks.
For residue cracking the process is known as R2R (reactor–2 regenerators). Catalytic and selective cracking occurs in a short-contact time riser where oil feed is effectively dispersed and vaporized through a proprietary feed-injection system. Operation is carried out at a temperature consistent with targeted yields. The riser temperature profile can be optimized with the proprietary mixed temperature control (MTC) system.
Reaction products exit the riser-reactor through a high-efficiency, close-coupled, proprietary riser termination device RSS (riser separator stripper). Spent catalyst is pre-stripped followed by an advanced high-efficiency packed stripper prior to regeneration. The reaction product vapor may be quenched to give the lowest dry gas and maximum gasoline yield. Final recovery of catalyst particles occurs in cyclones before the product vapor is transferred to the fractionation section.
Catalyst regeneration is carried out in two independent stages equipped with proprietary air and catalyst distribution systems resulting in fully regenerated catalyst with minimum hydrothermal deactivation, plus superior metals tolerance relative to single-stage systems. These benefits are derived by operating the first-stage regenerator in a partial burn mode, the second-stage regenerator in a full-combustion mode and both regenerators in parallel with respect to air and flue gas flows.
The resulting system is capable of processing feeds up to about 6 wt% ConC without additional catalyst cooling means, with less air, lower catalyst deactivation and smaller regenerators than a single-stage regenerator design.
Heat removal for heavier feedstocks (above 6 CCR) may be accomplished by using a reliable dense-phase catalyst cooler, which has been commercially proven in over 56 units.
The converter vessels use a cold-wall design that results in minimum capital investment and maximum mechanical reliability and safety.
Reliable operation is ensured through the use of advanced fluidization technology combined with a proprietary reaction system. Unit design is tailored to refiner’s needs and can include wide turn-down flexibility.
Available options include power recovery, waste-heat recovery, flue-gas treatment and slurry filtration.
Existing gas-oil units can be easily retrofitted to this technology. Revamps incorporating proprietary feed injection and riser termination devices and vapor quench result in substantial improvements in capacity, yields and feed-stock flexibility within the mechanical limits of the existing unit.
Licensor: Shaw and Axens.
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