Effect of Bed Material on Liquid-solid contact for non-reactive systems

systems

Figures 5.27, 5.28 and 5.29 shows that sand was a better bed material for liquids such as water, isobutanol and isobutanol-water emulsion, while coke was better for Varsol (figure 5.30). This is likely caused primarily by changes in wettability: Varsol wets coke better than sand while the other liquids wet sand better than coke (Table 5.2: Wettability for Various Liquids) The change in the bed material changes the wettability with the liquids fed hence the change in the dissipation time corresponding to improved liquid-solid contact. When the liquid wets the solid better more contact of the liquid occurs with the solid due to reduced contact angle which results into decreased dissipation time.

Table 5.2: Wettability for Various liquids

Wettability with Sand (o) Wettability with Coke (o)

Water 0 90

Isobutanol 35 46

Effect of Liquid properties on t_d for water RPM 0 20 40 60 80 100 120 140 160 td (s) 0 50 100 150 200 250 300 coke sand Temperature: 120 oC Feedrate: 4ml/min

Figure 5.27: Effect of Bed Material on Liquid-solid contact for water

RPM 0 20 40 60 80 100 120 140 160 td ( s) 0 10 20 30 40 50 Coke Sand Bed Material Temperature: 150oC Isobutanol Feedrate: 4ml/min

RPM 0 20 40 60 80 100 120 140 160 td ( s ) 0 20 40 60 80 100 120 140 160 Coke Sand Bed Material Temperature: 150oC Isobutanol-water emulsion Feedrate: 4ml/min

Figure 5.29: Effect of bed material on Liquid-solid contact for Isobutanol-water emulsion

Effect of RPM on t_d for Varsol

RPM 0 20 40 60 80 100 120 140 160 td ( s) 10 15 20 25 30 35 coke sand Temperature: 250 o C Feedrate: 4ml/min Nitrogen flowrate: 0.6 SLPM Varsol

5.3.3

Effect of Bed Material on Liquid-solid contact for reactive

systems

This section shows the effect of the bed material on liquid-solid contact and on thermal cracking of heavy oil and heavy oil-Varsol mixtures. Coke and sand were used as bed material.

Figure 5.31 shows that, for all agitator speeds, the liquid yield was slightly higher when coke was used as bed material. Figure 5.32 confirms that this was due to better liquid- solid contact with coke, since it gave a shorter dissipation time. Hydrocarbons such as heavy oil wet coke better than sand R. Caggiano et al., (1974) and experiments with non- reacting systems have already shown that a higher wettability is associated with better liquid-solid contact.

Effect of RPM on Liquid Yield of Pyrolysis Oil

RPM 0 20 40 60 80 100 120 140 160 Liquid Y ield ( w t. %) 66 68 70 72 74 76 78 80 82 coke sand Temperature: 500oC Feedrate: 4ml/min Nitrogen Flowrate: 0.6SLPM

RPM 0 20 40 60 80 100 120 140 160 td (s) 20 40 60 80 100 120 140 coke sand Temperature: 500 o C Feedrate: 4ml/min Nitrogen flowrate: 0.6 SLPM Heavy Crude Oil

Figure 5.32: Effect of bed material on liquid-solid contact for heavy oil cracking Figure 5.33 shows that, for each solid, there is a good correlation between the liquid yield and the dissipation time. The increase in the dissipation time decrease the liquid yield mainly because of the improved liquid-solid contact.

Effect of t_d on Liquid yield for heavy oil cracking

t_d (s) 20 40 60 80 100 120 140 Liquid Y ield ( w t. %) 66 68 70 72 74 76 78 80 82 COKE SAND Regression Temperature: 500o_C Feedrate: 4ml/min Heavy crude oil

Figure 5.33: Effect of dissipation time on liquid yield for heavy oil cracking

Figure 5.34 it can be observed that the reduction in the surface tension by adding Varsol 40 to the heavy oil improved the liquid-solid contact for coke as compared to that for sand as a bed material.

This improvement in the liquid-solid contact was much higher for coke as compared to that with sand. For the RPM of 120, the time for dissipation td for the Varsol-Heavy oil mixture was 60 s for sand. Using coke as a bed material reduced the time for dissipation td by more than half to 25 s.

Effect of bed material on td for heavy oil- Varsol Cracking

RPM 0 20 40 60 80 100 120 140 160 td (s) 20 30 40 50 60 70 80 90 100 coke sand Temperature: 500 oC

Varsol: Heavy oil = 50:50 Feedrate: 4ml/min

Figure 5.34: Effect of bed material on liquid-solid contact for Heavy oil-Varsol cracking

Figure 5.34 shows that better contact was achieved with coke than with sand when injection a 50:50 mixture of Varsol as with heavy oil. This is similar to the results that were obtained with pure heavy oil (Figure 5.32). Since mixing the two components did not alter the wettability.

6

Conclusions

1) The liquid-solid contact was successfully studied in the Mechanically Fluidized Reactor.

2) Increasing the agitator speed improved the liquid-solid contact in the MFR. With heavy oil, the effect was not gradual but occurred in stages.

3) The MFR was successfully used to simulate the Fluid CokingTM of heavy oil, improving the liquid-solid contact increased the liquid yield, reduced the coke yield and increased the gas yield. The quality of the product oil was also affected by the agitator speed. The liquid viscosity and calorific value increased as the agitator speed was increased.

4) Increasing the MFR temperature improved the liquid-solid contact for all the liquids while increasing the liquid feedrate degraded liquid-solid contact.

5) The liquid-solid contact improved as the latent heat of vaporization, the liquid surface tension and the wettability reduced in non-reacting systems. In reacting systems, adding Varsol to heavy oil improved the liquid-solid contact by decreasing the surface tension of the mixture or destabilizing wet agglomerates through flash vaporization. Forming an emulsion worsened the liquid-solid contact in the MFR.

6) In the Mechanically Fluidized reactor, better contact between injected liquid and bed particles is achieved when the liquid wets the solids better. A better liquid- solid contact increases the yield of valuable liquid product.

7

Recommendations

1) It was observed that increasing the agitator speed had significant effect on the liquid-solid contact and also on thermal cracking of heavy crude oil. Future work should investigate further increasing the agitator speed higher than present 140 RPM to study more resolute effects of the agitator speed on liquid-solid contact. 2) Increasing the feedrate degraded the liquid-solid contact. But when the feedrate

was further increased a plateau was reached. Future work should study the effect of further increase in the feedrate on the liquid-solid contact.

3) Many other bed materials can be used to illustrate the effect of bed material as well as the particle size. Future work should be to study the effect of particle size of the bed material as well as using various bed materials such as glass beads. The effect of treating a bed material on the liquid-solid contact should also be studied. 4) A comparison between MFR and a regular fluidized bed can be performed using

the methodology of dissipation time to study the model parameters for regular fluidized bed.

8

References

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Curriculum Vitae

Name: Mitesh Chaudhari

Post-secondary

Education and University of Mumbai

Degrees: Mumbai, India

2004-2008

Honours and Western Engineering Scholarship

Awards: 2011-2012

Related Work Graduate Research Assistant

Experience Institute of Chemicals and Fuels from Alternative Resources (ICFAR)

Western University 2011-2012