Davison circulation riser

In steady-state FCC operation with heavy cycle oil (HCO) recycling, it is conceivable that some hydrocarbon molecules could go through the riser multiple times. We developed a two-pass scheme that combines the Davison circulation riser (DCR) and advanced cracking evaluation (ACE) unit to simulate the recycling operation. 

Davison Circulating Riser, Reactor Temperature 52 TC, Regenerator Full Bum, Feed Pre-Heat varied, Countrymark feed, 0.9003 g/cc 15°C, 0.3 wt.% S, 0.53 wt.% ConCarb., 90% Pt. 530 C. Metals-free, steam equilibrated catalysts. 

Catalysts CPS (Mettallated and Cyclic) steaming. Test Conditions Davison Circulating Riser, Reactor Temperature 521° C, Full Bum Regenerator, Countrymark feed. 

Figure 5. Schematic diagram of the Davison Circulating Riser unit (Young and Weatherbee, 1989).

Another test involves use of the Davison full-circulating riser pilot unit (8). This unit is utilized mainly for testing and evaluating the aging properties of the most promising catalyst formulations. 

SOx Transfer Additives. Arguably, SOx transfer additives are the most cost-effective way to lower SOx emissions in an FCC unit. These materials, first developed by Davison Chemical, react with SOx in the FCC regenerator to form sulfates Figure 25). When the sulfated additive circulates to the riser/reactor section, the sulfate is reduced to H2S, which is recovered by amine absorption and sent to the sulfur plant. In some units, these additives reduce FCC SOx emissions by more than 70%. Consequently, if a pre-treater or post-treater still must be installed, its size can be reduced. 

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