Dispersion of feed spray in a new type of FCC feed injection scheme

Abstract

A new type of FCC feed injection scheme in which the feed is injected downward into the riser to realize a countercurrent contact of feed oil with catalyst particles is put forward. The dispersion of feed spray and flow behaviors of particles in the new type of feed injection scheme are investigated via a large scale cold-riser model. Experimental results show that the proposed scheme provides a better contact of feed oil with catalyst particles. Furthermore, the centerline equations of both the feed main flow and the secondary flow in the riser are given by introducing a density correction coefficient. The momentum-ratio of the secondary flow to the main flow is then obtained and the trajectory of the feed main jets as well as the secondary flow is estimated by the centerline equation. The computed results give a reasonable agreement with the experimental data.

Flow Hydrodynamics in Pyridine Synthesis Coupled Reactor Feed Injection Zones

“…The main reason for this deviation is the asymmetrically circulated catalyst feed along the 0°radial direction in the feedstock injection zone (20 cm higher than the nozzle installation points). Similar phenomenon was also observed in the work of Yan et al 9 As shown in Figure 8, the circulated catalysts employ horizontal and vertical momentum, the horizontal momentum carries the catalysts near the radial position r/R = −1 toward the radial position r/R = 1, which results in a higher flux region around r/R = 0−1, and as the mixture of circulated catalysts and catalysts from the dense bed region flows upward, this deviation is weakened.…”

“…As shown in Figure 9, the height of the dense bed is determined by the nozzle jet flow behavior. According to Roach 36 and Yan et al, 9 the flow behavior of a nozzle jet can be briefly depicted by Figure 13. As shown in Figure 13, along the axial direction, the nozzle jet flows downward first with an inclination angle of 30°and then it reaches its farthest position along the axial direction when its vertical momentum dies out, after which, the nozzle jet flows upward owing to the force given by the prelift gas.…”

“…Previous works indicated that the nozzle jet trajectory is closely connected with fluid properties, nozzle jet velocities, and nozzle structures. 14−18 Yan et al 9 theoretically calculated the trajectory of the nozzle jet in the FCC riser feed injection zone and the following correlations are proposed:…”

“…First, research studies regarding the nozzle jet in the fast fluidized bed reactor were reviewed, which focus on the fluid catalytic cracking (FCC) process. − For the FCC riser reactor, the feed nozzle jet is introduced into the reactor and mixed with the prelift mixtures, after which the reactions take place. The gas–solid flow structures in the FCC feed injection zones were closely investigated by Fan et al, , and the results showed that the two-phase flow structures deviate from core-annulus typical distribution, which results from the introducing of the feed nozzle jet; in addition, the flow behavior of a so-called secondary flow was also given.…”

“…The gas–solid flow structures in the FCC feed injection zones were closely investigated by Fan et al, , and the results showed that the two-phase flow structures deviate from core-annulus typical distribution, which results from the introducing of the feed nozzle jet; in addition, the flow behavior of a so-called secondary flow was also given. Further, Yan et al − investigated the two-phase flow behavior in FCC riser feed injection zones, with the feed nozzles pointed downward. Yan et al − found that the downward pointed nozzle jet has less influence on the two-phase structures in riser feed injection zones than the upward case; based on experimental results, the nozzle jet trajectory function was given.…”