| Description |
The bituminous sand deposits of Utah are estimated to contain 25 - 29 billion barrels of oil in place and are the largest petroleum resource of this type in the United States. There are six major deposits of commercial importance* some of them potentially amenable to surface mining techniques. In this investigation an experimental program was conducted to determine the feasibility of an aboveground fluidized bed thermal process rfor the recovery of - a synthetic crude from the minable bituminous sand deposits of Utah. A continuous bench-scale, fluidized bed reactor, designed for a maximum throughput capacity of 2.25 kilograms of feed sand per hour, was developed for this investigation. Bituminous sands of distinctly different origin were processed, that is, (i) the Sunnyside bituminous sand, a deposit of fresh water origin having a bitumen content of 8.5 percent by weight, and (ii) the Tarsand Triangle sand, a deposit of marine origin having a bitumen content of 4.5 percent by weight. The effects of the following variables on the synthetic liquid yield and on the liquid quality were studied: Reactor Temperature: 698 - 898 K Solids Retention Time: 20.4 - 31.4 minutes Particle Size of Feed Sand: 162 - 507.5 microns The maximum liquid yield for the Sunnyside sand, 70 weight percent of the bitumen fed, was obtained at 773 K and a solids retention time of 20.4 minutes for a feed sand particle size of 358.5 microns. The remaining 30 weight percent of the bitumen was converted to coke and light hydrocarbon gases. Increasing the solids retention time lowered the liquid yield and shifted the-temperature for maximum liquid yield to a lower value. The physical properties and chemical nature of the synthetic liquid obtained were correlated with the reactor temperature. The synthetic liquid obtained was paraffinic and contained a low percentage of heteroatoms. A mechanism for the thermal cracking of the bitumen has been developed to explain the results obtained. Extrapolation of the data to a solids retention time of 16 minutes predicts a yield of 80 weight percent synthetic liquid, 8 weight percent light hydrocarbon gases (C-j - C4 ), and 12 weight percent coke. The thermal processing of Tarsand Triangle sand was studied as a function reactor temperature in the range 723 - 898 K. It was found that the liquid yield was lower than that obtained with the Sunnyside feed. The maximum liquid yield of 51 weight percent based on bitumen fed was obtained at 798 K and a retention time of 27.2 minutes. Despite the differences in the origin of the feed sand and the operating temperature range, the yield of coke (19 - 22 wt %) was comparable to Sunnyside coke yields. The liquid product was more aromatic than the Sunnyside liquid product. |
