The Gasification of Carbonaceous Materials in Molten Sodium Phosphate

Citation

Siddoway, Mark Alan (1982) The Gasification of Carbonaceous Materials in Molten Sodium Phosphate. Dissertation (Ph.D.), California Institute of Technology. doi:10.7907/3t1x-qd32. https://resolver.caltech.edu/CaltechETD:etd-01232007-132837

Abstract

The gasification rates of petroleum coke, char, and residual oil were measured in molten sodium phosphate. Both oxygen and steam were used as oxidants, and a variety of reactor configurations were studied. Reactors consisted of fused ceramic parts sealed into a reactor configuration using castable refractory.

The reaction rate of carbon particles in a bubbling molten phosphate slurry was found to depend upon the rate of particle-bubble contacting. Upon contact, direct conversion of carbon particles with the gas phase occurs due to the large carbon-molten sodium phosphate contact angle (136°). The potential flow solution for flow around a bubble where particles are assumed to follow the streamlines gave a consistent picture of bubble-particle contacting. The reactivity of the carbon in the bulk liquid was found to be negligible due to the low solubility of oxygen in the melt.

Gas phase (no salt) results were generated to establish base cases and to examine treatment effects on the reactivity of green sponge and green needle cokes. The reactivities of both were favorably affected by toluene extraction and adversely affected by calcination to 1300 K. Extraction decreased the agglomerating nature of the sponge coke. Both extracts were largely aromatic with the needle coke extract being more so.

Molten sodium phosphate was found to catalyze the gasification of petroleum coke by steam and by oxygen. Such catalytic effects are limited due to the large carbon-salt contact angle and may be obscured in slurry reactors by the rate of particle-bubble contacting being slow. The steam reforming of residual oil revealed that the carbonized product in the molten salt phase closely resembled sponge petroleum coke (as produced by delayed coking).

Cold model experiments employing water and polymeric beads revealed that dilute slurries of small, non-wetting particles decreased the rise velocity of single bubbles and increased the rate of bubble coalescence in swarms. Dilute slurries of wetting particles had no effect in either case.

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