Experimental simulation of the reactor section of fluid cokers: comparison of FCC and fluid coke particles.

Song, Xuqi ; Grace, John R. ; Bi, Hsiaotao 等

The hydrodynamics of fluid cokers were studied in a pressurized fully cylindrical cold model of diameter 483 mm, geometrically and dynamically scaled down by a factor of ~20 from commercial units. Differential pressure fluctuations, voidage distributions, solids momentum flux distributions and steady state gas mixing behaviour in the reactor section are compared for the same operating conditions with two kinds of particles, FCC and fluid coke. The voidage distributions and core-annular flow structures in the reactor section were similar enough that either FCC or fluid coke particles can be used for cold modelling of fluid cokers.

On a etudie l'hydrodynamique d'unites de cokefaction fluide dans une maquette froide cylindrique pressurisee de 483 mm de diametre, geometriquement et dynamiquement reduite d'un facteur 20 par rapport a des unites commerciales. Les fluctuations de pression differentielles, les distributions de vide, les distributions de flux de moment des solides et le comportement de melange de gaz a l'etat stable dans la section du reacteur sont compares pour les memes conditions operatoires avec deux sortes de particules, soient FCC et coke fluide. Les distributions de vide et les structures d'ecoulement noyau-espace annulaire dans la section du reacteur sont suffisamment semblables pour que des particules de FCC ou de coke fluide puissent etre utilisees pour la modelisation a froid d'unites de cokefaction fluide.

Keywords: fluidization, fluid coker, hydrodynamics, voidage, solids momentum, gas mixing

Fluid cokers convert bitumen or hydrocarbon residues to lower boiling point hydrocarbons, gases and coke. The thermal cracking process is carried out in large fluidized beds, where hot coke particles, introduced from above, carry the heat required for the endothermic reactions and collect solid byproducts on their surfaces. The hydrocarbon feed is steam-atomized and injected horizontally through multiple nozzles. Vapour products tend to channel up the centre of the bed, surrounded by dense, descending particles (Knapper et al., 2002; Song et al., 2004). Particles from the reactor pass down through a stripper, in which a counter-current flow of steam strips liquid hydrocarbon from the particle surface. The coke particles are then circulated to a fluidized bed burner for re-heating prior to reentering the fluid coker at a higher temperature (Matsen, 1996).

The distribution of liquid feed over the coke particles, which affects the liquid yield (Gray et al., 2001), is strongly dependent on the mode in which the spray from the feed nozzles interacts with the surrounding particles. To improve the understanding of the interaction between solids and feed jets, the voidage distribution, solids flow structure and the gas mixing behaviour have been studied in two geometrically and dynamically scaled cold model facilities using FCC particles (Knapper et al., 2002; Song et al., 2004, 2005). One of these units, designed to study the stripper section, was a plexiglas half-column with a scale ratio of ~1:10. The other is an ~1:20 scale steel full-column, capable of modest pressurization so that the hydrodynamic behaviour in the reactor section of the column can be simulated properly. Either FCC or fluid coke particles can be used in the cold model equipment, but FCC particles are desirable as more measurement techniques, such as fibre optical probes, can be deployed. Whether to use identical particles to those used in actual high-temperature full-scale processes or other particles designed to provide better modelling of dimensionless groups is a matter of debate in the industry and fluidization community. In the present work, the hydrodynamic behaviour of the bed when operated with FCC and fluid coke particles is compared in the same cold model column. This paper extends the studies of Knapper et al. (2002) and Song et al. (2004, 2005) in which FCC particles were used. Thus, the experimental data for FCC particles used for comparison with fluid coke particles are mainly taken from these earlier studies, whereas all of the coke particle data are reported here for the first time.

EXPERIMENTAL

The experiments were carried out in a fully cylindrical cold model, geometrically scaled down by a factor of ~20 from two commercial fluid cokers operated by Syncrude Canada Limited in Fort McMurray, AB, Canada. A schematic is shown in Figure 1. Details of the experimental facility can be found elsewhere (Song et al., 2004). The reactor includes a complete set of nozzles, matching those in the commercial units, and a stripper section equipped with baffles and aeration to simulate steam addition in the commercial reactors. An external riser returns solids removed from the bottom of the stripper to the top of the reactor. Air is provided by a diesel-driven compressor. Cyclones and baghouses capture entrained particles. The equipment was designed so that dynamic similitude, in addition to geometric similitude, could be obtained between the cold model unit and both commercial units. The reactor sections in the cold model and commercial units operate in the bubbling fluidization flow regime. Scaling, based on dimensionless analysis (Glicksman et al., 1994), was achieved by matching important dimensionless hydrodynamic parameters

[A.sub.r], [F.sub.r], [[rho].sub.p]/[[rho].sub.g], [G.sub.s]/[[rho].sub.p][U.sub.f], dimensionless PSD, (1)

and all equipment dimension ratios

[FIGURE 1 OMITTED]

Scaling parameters based on FCC and fluid coke particles are summarized in Table 1. As seen, matching of the key dimensionless groups is not perfect, but is as good as can normally be achieved in practical systems. The cumulative particle size distributions for the FCC and fluid coke particles are plotted in Figure 2. In order to keep the same density ratio, [[rho].sub.p]/[[rho].sub.g], as for the commercial units, the cold model was operated at a slightly elevated pressure. The reactor section is axisymmetric and tapered, expanding in diameter from 305 mm at the bottom to 483 mm at the top. Despite the taper, the superficial gas velocity increases up the feed section because of stagewise addition of air through a series of horizontal injection rings. The axial profile of superficial gas velocity with six active feed rings, shown in Figure 3, was similar to that in the commercial units, with the superficial gas velocity decreasing with height between successive feed nozzle rings because of the diverging cross-section of the reactor.

[FIGURES 2-3 OMITTED]

In the commercial units, a mixture of bitumen and steam is injected into the fluidized bed of coke particles through six rings of nozzles. The jet geometry is assumed to be composed of a cone and a hemisphere attached to the base of the cone, with the jet half-angle assumed to be constant and equal to 6.25[degrees] (Merry, 1971). The jet penetration depth, L, defined as the horizontal distance from the end of the nozzle to the mean position of the end of the jet region, is estimated from the semi-empirical correlation of Merry (1971):

L/[d.sub.0] + 4.5 = 5.25 [([[rho].sub.0][u.sup.2.sub.0]/(1-[epsilon][[rho].sub.p]g[d.sub.p]).sup.0.4] [([[rho].sub.g]/[[rho].sub.p]).sup.0.2] [([d.sub.p]/[d.sub.0]).sup.0.2]. (2)

This equation has previously been found to give good predictions for our system (Copan, 1999; Knapper, 2000; Song et al., 2004; Donald et al., 2004; Song et al., 2005). The nozzle diameter was chosen to maintain the same ratio of jet-penetration-to-column-radius as for the commercial units.

Capacitance Voidage Probe

As the optical fibre probe measurement system cannot be used in conjunction with fluid coke particles (because of poor light reflection from the black coke), a capacitance measurement system, which measures the local dielectric constant of the fluidized bed (Hage and Werther, 1997), was developed for the coke particles in this work. The probe was originally used by Brereton and Grace (1993) and was improved by combining the probe and a reactance converter box to eliminate noise. After calibration of the output signals for known voidages, the capacitance probe was used to measure the voidage distribution in a fluidized bed of fluid coke particles.

The capacitance probe was always mounted horizontally, using one of the column side ports, between feed nozzle rings. The probe was traversed horizontally to allow measurements from the axis of the column to the near wall. Signals were recorded on a computer for periods of 80 s at a sampling frequency of 100 Hz. The signal was then analyzed to give the time-mean local voidage and the standard deviation of the voidage about the mean. Figure 4 shows a typical radial profile of time-mean voidage, whereas the inserts show fluctuations of local voidage for four radial positions. The time-mean voidage increases gradually from the wall to the axis of the column. The significant peaks in voidage in the insets correspond to passing voids containing fewer solids. The frequency of these voids is seen to increase in traversing from the wall to the centre of the column.

[FIGURE 4 OMITTED]

The radial voidage profile in the reactor section of FCC particles was measured by the capacitance probe and compared with the earlier results obtained by the optical fibre probe (Song et al., 2004), as shown in Figure 5. The two measurement methods are seen to have given very similar results for FCC, increasing confidence in the validity of both types of probe measurements. This degree of validation of the two types of probes represents one of the contributions of this paper.

[FIGURE 5 OMITTED]

Solids Momentum Flux Measurement System

Solids momentum probes have been used in circulating fluidized beds to distinguish between upward and downward flow (Bai et al., 1995, Kim et al., 2004). As the optical fibre particle velocity probe cannot be used in a fluidized bed of fluid coke particles, a solids momentum probe was employed to investigate the local solids flow structure in the reactor section. As shown in Figure 6, the probe was simply made of two stainless steel tubes having the same inside diameter of 3 mm. Two tips (facing upward and downward), separated by 9.5 mm, were aligned vertically at the desired radial position. The pressure difference across the two tips, [DELTA][P.sub.M], was measured by a differential pressure transducer. To prevent particles from blocking the tubes, carefully controlled purge air flows were introduced into the two tubes. The instantaneous pressure difference across the tips, [DELTA][P.sub.M], should correspond to the net momentum flux of the gas-solids suspension flow, i.e.,

[DELTA][P.sub.M] = K[[[rho].sub.P](1-[epsilon])V|V| + [[rho].sub.g][epsilon][U.sub.g]|[U.sub.g]|] (3)

where K is a constant dependent on the probe geometry. The gas kinetic energy corresponding to the second term on the right-hand side in Equation (3) can reasonably be ignored because the solids density is about seven hundred times the gas density. Thus, averaged over time, we have

[MATHEMATICAL EXPRESSION NOT REPRODUCIBLE IN ASCII] (4)

[FIGURE 6 OMITTED]

A typical radial profile of measured [MATHEMATICAL EXPRESSION NOT REPRODUCIBLE IN ASCII] for a given set of operating conditions is shown in Figure 7. The fluctuations of [DELTA][P.sub.M] for given positions are also shown in the figure. Note that [MATHEMATICAL EXPRESSION NOT REPRODUCIBLE IN ASCII] is large, with a positive sign in the core region, indicating an upward flow of solids. With increasing r/R, [MATHEMATICAL EXPRESSION NOT REPRODUCIBLE IN ASCII] gradually decreases and finally becomes negative, corresponding to downflow of solids. The change in sign of [MATHEMATICAL EXPRESSION NOT REPRODUCIBLE IN ASCII] from positive to negative provides an indication of where the flow direction of solids changes from upward to downward. For the purpose of determining the distinction between upward and downward flow region, there is no need to calibrate the probe. We note, however, that the boundary position from solids momentum flux measurement will probably differ somewhat from that determined from the location where the time-mean particle velocity and time-mean solids flux pass through zero due to likely correlation between fluctuations in local voidage and local particle velocity (Bi et al., 1996).

[FIGURE 7 OMITTED]

The solids momentum flux probe provides a simple measurement technique for systems involving fluid coke, where optical fibre probes cannot work. In addition, it could be applied in commercial units to study the solid flow structure at elevated temperatures and pressures.

Steady State Gas Mixing

Helium tracer gas was used to study the gas flow behaviour in the reactor section. Details can be found elsewhere (Song et al., 2005). Helium was injected at steady state through all nozzles from feed ring 3, and the tracer concentration was measured at several levels upstream and downstream to monitor the gas mixing behaviour.

RESULTS AND DISCUSSION

Axial Pressure Gradient

Pressure fluctuations provide one of the easiest and least costly means of studying the hydrodynamics of fluidized beds (Bi et al., 2000, Ellis et al., 2002). Differential pressure measurements, with the separation distance between ports of the order of a few centimetres, can reflect the local flow behaviour. Pressure gradients in the reactor section were measured at different heights using differential pressure taps. Dynamic signals of differential pressure fluctuations were recorded at a sampling frequency of 100 Hz for durations of 85 s. Time-averaged pressure gradients in the reactor section are compared in Figure 8 for FCC and fluid coke particles under similar operating conditions. The average pressure gradients, which are nearly proportional to the cross-sectional average bed density, are seen to be very similar for the two materials. Power spectral diagrams of differential pressure for four axial positions in the reactor section in Figure 9 also give similar distributions for the FCC and coke, indicating similar local flow structures.

[FIGURES 8-9 OMITTED]

Voidage Distributions

In experiments with FCC particles, local voidages measured by an optical fibre probe showed a dense annular region surrounding a more dilute core region (Song et al., 2004). Radial profiles of local voidage measured by the capacitance probe in a fluidized bed of fluid coke particles are compared in Figure 10 with results from the optical fibre probe in the FCC. All of the measurements were performed under base conditions with [U.sub.s] = 0.25 m/s and [U.sub.f] = 0.74 m/s. The distributions are similar, with a dense annular region surrounding a more dilute core in both cases. The radial distributions of standard deviation of voidage fluctuation are also close together, indicating similar local flow structures in the reactor section for the FCC and coke particles.

[FIGURE 10 OMITTED]

Solids Momentum Flux Distribution

The solids momentum flux probe was used to investigate the solids flow structure in fluidized beds of FCC and fluid coke particles. The experimental radial profiles of [MATHEMATICAL EXPRESSION NOT REPRODUCIBLE IN ASCII], the time-average pressure difference across the tips of the solids momentum probe, are shown in Figure 11 for three heights. [MATHEMATICAL EXPRESSION NOT REPRODUCIBLE IN ASCII] indicates much more non-uniform flow in the upper part of the reactor section than near the bottom, possibly due to the coalescence of the jets in the core of the column. In the lower part, i.e. the transition zone between stripper and reactor sections, [MATHEMATICAL EXPRESSION NOT REPRODUCIBLE IN ASCII] is positive at all radial positions. Hence, there is no clear boundary between regions of upward and downward solid momentum flux.

[FIGURE 11 OMITTED]

The effect of the superficial gas velocity on the solids momentum flux is shown in Figure 12. [MATHEMATICAL EXPRESSION NOT REPRODUCIBLE IN ASCII] decreases significantly with decreasing superficial gas velocity in the central region. The internal circulation of solids is more intense at a higher superficial gas velocity. The boundary between zones of upward and downward solids momentum flux disappeared when the superficial gas velocity decreased beyond a certain value.

[FIGURE 12 OMITTED]

Measured [MATHEMATICAL EXPRESSION NOT REPRODUCIBLE IN ASCII] values are compared in Figure 13 for FCC and fluid coke particles for very similar operating conditions. There is a strong similarity in the radial profiles of solids momentum and in the boundary between zones of upward and downward solids momentum flux. These results indicate that the fluidized beds tested with FCC and fluid coke particles have similar local solids flow structures for the range of conditions investigated.

[FIGURE 13 OMITTED]

Gas Mixing Behaviour

Gas radial mixing and backmixing in the reactor section can be evaluated from tracer concentrations monitored downstream and upstream of the tracer injection level. Details about gas residence time distributions and backmixing for FCC particles have been provided by Song et al. (2005). The overall distributions of helium concentration in the reactor section, both upstream and downstream, with helium tracer injected continuously from feed ring 3, are compared in Figure 14 for FCC and fluid coke particles. Radial positions indicating the jet region were calculated from Equation (2). For the two kinds of particles used, radial profiles of helium concentration are similar, both upstream and downstream of the tracer injection level. The helium concentrations above the jet region are higher than at other locations within a limited distance downstream of the injection level. The non-uniformity of concentration across the bed decreases with distance above the tracer injection ring due, at least in part, to radial gas mixing. In the fully developed mixing zone far above the tracer injection level, the radial concentration profiles become almost uniform.

[FIGURE 14 OMITTED]

The upstream tracer concentrations are higher near the wall than in the core of the column. The radial concentration profiles indicate considerable axial dispersion of gas near the wall due to downflow of solids there. Tracer gas, together with solid particles, is entrained by the feed jets from the downward flowing annular region into the upward flowing core region. Note that the tracer gas penetrates down to the top of the stripper section due to the vigorous internal circulation of gas and solids in the reactor zone.

CONCLUSIONS

Axial and radial distributions of voidage in the reactor section of a fluid coker cold model were measured by an optical fibre probe and by a capacitance probe. Both probes gave very similar results for the FCC particles. The data show a dense annular region surrounding a more dilute core region for both FCC and fluid coke particles. The voidage profiles indicate that the voidage increases gradually from the wall to the axis of the column, rather than showing a sharp transition between annular and core regions.

The hydrodynamic behaviour of differential pressure fluctuations, voidage distributions and solids momentum flux distributions in the reactor section were very similar for FCC and fluid coke particles under similar operating conditions. This suggests that strict dynamic similarity is not required for the conditions studied and that either FCC or fluid coke can be used for cold modelling purposes.

ACKNOWLEDGEMENT

The authors are grateful to Syncrude Canada Limited for sponsoring this work and for permission to publish the results. We are also grateful to Chevron Canada Ltd. for providing the FCC particles.

NOMENCLATURE

Ar Archimedes number [MATHEMATICAL EXPRESSION NOT
 REPRODUCIBLE IN ASCII]

D column diameter at top of reactor section (m)

[d.sub.0] inner diameter of nozzle (m)

[d.sub.p] particle diameter (m)

F fraction of particles by mass smaller than a given
 [d.sub.p](-)

[F.sub.r] Froude number (= [U.sup.f.sub.2]/g[d.sub.p])

g acceleration due to gravity (9.81 m/[s.sup.2)

[G.sub.s] local net solids circulation flux corrected for
 cross-sectional area (kg/[m.sup.2]s)

[G.sub.sf] net solids circulation flux based on cross-sectional
 area at top of reactor (kg/[m.sup.2]s)

H expanded bed depth in reactor section (m)

K momentum transfer coefficient defined in
 Equation (3) (-)

L horizontal jet penetration (m)

[u.sub.0] feed nozzle jet velocity (m/s)

[U.sub.c] transition velocity at which standard deviation of
 pressure fluctuations reaches a maximum (m/s)

[U.sub.f] superficial gas velocity at dense phase bed surface (m/s)

[U.sub.g] superficial gas velocity at a given level corrected for
 gas flow rate and cross-sectional area (m/s)

[U.sub.s] superficial gas velocity at top of stripper section (m/s)

V particle velocity (m/s)

Z height coordinate measured from top of highest
 stripper shed (m)

[Z.sup.*] dimensionless height coordinate (Z / total height
 of reactor section) (-)

Greek Symbols

[DELTA][P.sub.M] pressure difference across tips of momentum
 flux probe (kPa)

[epsilon] local voidage (-)

[mu] gas viscosity (Pa x s)

[[rho].sub.o] gas density at nozzle tip (kg/[m.sup.3])

[[rho].sub.g] gas density (kg/[m.sup.3])

[[rho].sub.p] particle density (kg/[m.sup.3])

REFERENCES

Bai, D., E. Shibuya, Y. Masuda, K. Nishio, N. Nakagawa and K. Kato, "Distinction between Upward and Downward Flows in Circulating Fluidized Beds," Powder Technol. 84, 75-81 (1995).

Bi, H. T., N. Ellis, I. A. Abba and J. R. Grace, "A State-of-the-Art Review of Gas-Solid Turbulent Fluidization," Chem. Eng. Sci. 55, 4789-4825 (2000).

Bi, H. T. and J. R. Grace, "Effects of Measurement Method on Velocities Used to Demarcate the Transition to Turbulent Fluidization," Chem. Eng. J. 57, 261-271 (1995).

Bi, H. T., J. Zhou, S. Z. Qin and J. R. Grace, "Annular Wall Layer Thickness in Circulating Fluidized Bed Risers," Can. J. Chem. Eng. 74, 811-814 (1996).

Brereton, C. M. H. and J. R. Grace, "Microstructural Aspects of the Behaviour of Circulating Fluidized Beds," Chem. Eng. Sci., 48, 2565-2572 (1993).

Copan, J., "Macroscopic Modeling of a Fluid Bed Coker and Experimental Studies of One- and Two-Phase Feed Jets," MSc Thesis, University of Saskatchewan, Saskatoon, SK, Canada (1999).

Donald, A., H. T. Bi, J. R. Grace and C. J. Lim, "Penetration of Single and Multiple Horizontal Jets into Fluidized Beds," in "Fluidization XI," U. Arena, R. Chirone, M. Miccio and P. Salatino, Eds., Ischia, (2004), pp. 117-124.

Ellis, N., C. J. Lim, J. R. Grace, H. T. Bi and K. S. Lim, "Frequency Analysis of Pressure Fluctuations in Turbulent Fluidized Beds," in "Circulating Fluidized Bed Technology VII," J. R. Grace, J. Zhu and H. de Lasa, Eds., Ottawa: CSChE (2002), pp. 287-294.

Glicksman, L. R., M. R. Hyre and P. A. Farrell, "Dynamic Similarity in Fluidization," Int. J. Multiphase Flow 20S, 331-386 (1994).

Grace, J. R., "Contacting Modes and Behaviour Classification of Gas-Solid and Other Two-Phase Suspensions," Can. J. Chem. Eng. 64, 353-363 (1986).

Gray, M. R., T. Le, W. C. McCaffrey, F. Berruti, S. Soundararajan, E. Chan, I. Huq and C. Thorne, "Coupling of Mass Transfer and Reaction in Coking of Thin Films of Athabasca Vacuum Residue," Ind. Eng. Chem. Res. 40, 3317-3324 (2001).

Hage, B. and J. Werther, "The Guarded Capacitance Probe-- A Tool for the Measurement of Solids Flow Patterns in Laboratory and Industrial Fluidized Bed Combustors," Powder Technol. 93, 235-245 (1997).

Kim, S. W., G. Kirbas, H. Bi, C. J. Lim and J. R. Grace, "Flow Behaviour and Regime Transition in a High-Density Circulating Fluidized Bed Riser," Chem. Eng. Sci., 59, 3955-3963 (2004).

Knapper, B. A., "Experimental Studies on the Hydrodynamics of Fluid Bed Cokers," MS Thesis, University of Saskatchewan, Saskatoon, SK, Canada (2000).

Knapper, B., F. Berruti, J. R. Grace, H. T. Bi and C. J. Lim, "Hydrodynamic Characterization of Fluid Bed Cokers," in "Circulating Fluidized Bed Technology VII," J. R. Grace, J. Zhu and H. de Lasa, Eds., Ottawa: CSChE (2002), pp. 263-270.

Matsen, J. M., "Scale-Up of Fluidized Bed Process: Principle and Practice," Powder Technol. 88, 237-244 (1996).

Merry, J. M. D., "Penetration of a Horizontal Gas Jet into a Fluidized Bed," Trans. Inst. Chem. Eng. 49, 189-195 (1971).

Song, X. Q., H. T. Bi, C. J. Lim, J. R. Grace, E. Chan, B. Knapper and C. McKnight, "Hydrodynamics of the Reactor Section in Fluid Cokers," Powder Technol. 147, 126-136 (2004).

Song, X. Q., J. R. Grace, H. T. Bi, C. J. Lim, E. Chan, B. Knapper and C. A. McKnight, "Gas Mixing in the Reactor Section of Fluid Cokers," Ind. Eng. Chem. Res. 44, 6067- 6074 (2005).

Manuscript received January 5, 2005; revised manuscript received December 22, 2005; accepted for publication December 26, 2005.

Xuqi Song (1), John R. Grace (1 *), Hsiaotao Bi (1), C. Jim Lim (1), Edward Chan (2), Brian Knapper (2) and Craig McKnight (2)

(1.) Fluidization Research Centre, Department of Chemical and Biological Engineering, The University of British Columbia, 2216 Main Mall, Vancouver, BC, Canada V6T 1Z4

(2.) Syncrude Research Centre, 9421 - 17 Avenue, Edmonton, AB, Canada T6N 1H4

* Author to whom correspondence may be addressed.

E-mail address: jgrace@chml.ubc.ca

Table 1. Summary of dimensional similitude based on reactor section

 Commercial Syncrude
 units, base conditions

Gas Vaporized hydrocarbons
 and steam
Temperature, [degrees]C 510~540
Pressure, kPa 360
Gas density, [[rho].sub.g], kg/[m.sup.3] 2.28
Gas viscosity, [mu], Pa.s 2.5 x [10.sup.-5]
Type of particles Fluid Coke
Particle density, [[rho].sub.p], kg/[m.sup.3] 1600
Mean particle diameter, [[??].sub.p] [micro]m 145
Geldart powder group * A
Superficial velocity at top of 0.8
 reactor, [U.sub.f], m/s
[U.sub.f]/[U.sup.[yen].sub.c] 0.88
Solids circulation flux at top of 20.3
 reactor, [G.sub.sf], kg/[m.sup.2]s
Density ratio, [[rho].sub.p]/[[rho].sub.g],-- 701
Froude number, Fr,-- 485
Archimedes number, Ar,-- 174
Solids-to-gas mass flow ratio, 10.7
 [G.sub.sf]/([[rho].sub.g][U.sub.f]),--
Inventory of solids, H/D 2.18

 UBC, base conditions
 with FCC

Gas Air

Temperature, [degrees]C 25
Pressure, kPa 200
Gas density, [[rho].sub.g], kg/[m.sup.3] 2.34
Gas viscosity, [mu], Pa.s 1.8 x [10.sup.-5]
Type of particles FCC
Particle density, [[rho].sub.p], kg/[m.sup.3] 1700
Mean particle diameter, [[??].sub.p] [micro]m 99
Geldart powder group * A
Superficial velocity at top of 0.74
 reactor, [U.sub.f], m/s
[U.sub.f]/[U.sup.[yen].sub.c] 0.92
Solids circulation flux at top of 18.6
 reactor, [G.sub.sf], kg/[m.sup.2]s
Density ratio, [[rho].sub.p]/[[rho].sub.g],-- 726
Froude number, Fr,-- 567
Archimedes number, Ar,-- 117
Solids-to-gas mass flow ratio, 10.7
 [G.sub.sf]/([[rho].sub.g][U.sub.f]),--
Inventory of solids, H/D 2.15

 UBC, base conditions
 with Fluid Coke

Gas Air

Temperature, [degrees]C 25
Pressure, kPa 195
Gas density, [[rho].sub.g], kg/[m.sup.3] 2.28
Gas viscosity, [mu], Pa.s 1.8 x [10.sup.-5]
Type of particles Fluid Coke
Particle density, [[rho].sub.p], kg/[m.sup.3] 1600
Mean particle diameter, [[??].sub.p] [micro]m 133
Geldart powder group * AB boundary
Superficial velocity at top of 0.74
 reactor, [U.sub.f], m/s
[U.sub.f]/[U.sup.[yen].sub.c] 0.84
Solids circulation flux at top of 18.3
 reactor, [G.sub.sf], kg/[m.sup.2]s
Density ratio, [[rho].sub.p]/[[rho].sub.g],-- 701
Froude number, Fr,-- 429
Archimedes number, Ar,-- 251
Solids-to-gas mass flow ratio, 10.7
 [G.sub.sf]/([[rho].sub.g][U.sub.f]),--
Inventory of solids, H/D 2.15