Published January 2003
UOP's Alkylene™ process is a potential successor to HF alkylation processes. The driving force behind developing this process is the desire to produce high quality alkylate at competitive economics and yet to avoid the safety issues, or perception of safety issues, associated with HF or sulfuric acid alkylation.
The economic evaluation in this Review is based on a nominal capacity of 10,000 BPSD of alkylate at 0.95 on stream factor from 8,015 BPSD of C4 cut obtained from a 85,000 BPSD fluid catalytic cracking (FCC) unit. An additional 4,890 BPSD of 95 wt% isobutane is imported from other refinery and NGL sources. The material balance shows 10,423 BPSD of 95.8 RON alkylate produced and sent to the gasoline pool. 739 BPSD of n-butane, about 155 BPSD of 32 wt% propane-isobutane LPG and 0.4 MM SCFD of hydrogen rich fuel gas are the by-products.
The Alkylene process uses a liquid phase riser reactor with a solid catalyst similar in concept to FCC. The reactor operates at about 350 psia with an external isobutane to olefin ratio of about 6 to 15 and refrigerated temperatures, 50-100°F (10-38°C). The isobutane-to-olefin ratio and temperature are similar to HF alkylation. Catalyst reactivation and regeneration are key steps in the Alklene process. A lock hopper system periodically transfers a portion of the catalyst to a thermal regenerator and back to the reactor. This catalyst movement concept is similar to that used in continuous catalyst regeneration in catalytic reforming. In the Alkylene regenerator, heavy molecules on the catalyst are hydrogenated, released from the catalyst and washed off.
The reactor effluent is fractionated to remove alkylate. A side stream is fractionated to produce a n-butane bottoms product and isobutane rich overhead that is recycled to the reactor. The fractionator overhead is further fractionated to remove fuel gas and produce LPG distillate. The isobutane rich bottoms are recycled to the reactor.
