Hydrotreated shale oil

We will consider three processes in more detail to show how the sulfur in the original feedstock material (coal or oil shale) is recovered as elemental by-product sulfur. In this way yields of sulfur per barrel of product can be computed. The three processes will illustrate examples of coal gasification for production of SNG, methanol or indirect liquids, direct liquefaction for production of naphtha and synthetic crude oil and finally, oil shale retorting for production of hydrotreated shale oil. 

The process considered is the Colony hydrotreated shale oil plant using the TOSCO II pyrolysis retort (4). In this process raw shale, crushed to 1/2" or smaller, is contacted with hot ceramic balls in a rotating drum. Downstream of the retort the balls and spent shale are separated by screening. The balls are then transported by an elevator to a vessel in which they are reheated by direct contact with hot combustion gases. The heated balls are then recycled to the rotating retort. 

The plant will produce 198 TPSD of elemental sulfur. This represents a sulfur output of 0.0045 tons of sulfur/barrel of hydrotreated shale oil. 

The shale oil residual had been hydrotreated to a substantial degree, providing it with a hydrogen content very similar to the No. 2 petroleum distillate fuel. The shale oil residual fuel had viscosity characteristics similar to a viscous No. 4 petroleum distillate fuel. The nitrogen content of the hydrotreated shale oil residual was 0.49 weight percent. 

The character and hydrocarbon-type composition of several syncrudes have been investigated by adaptation of methods developed for heavier fractions of petroleum crude oils. The methods are reviewed briefly, and results are summarized for five coal liquids and a hydrotreated shale oil Refining requirements for removal of heteroatoms, especially nitrogen, and conversion of polynuclear aromatics are discussed in relation to the composition of the syncrudes and the character of refined products to be expected. A preliminary report is given on the preparation of liquid samples from coals of widely different rank to permit more systematic correlation of hydrocarbon character with coal source in relation to refining. 

Coal Liquids and Shale Oil. Some properties of five coal liquids and a hydrotreated shale oil are given in Table I, including sulfur, nitrogen, acid and base contents, and distributions by boiling range. Ring-number... 

Table II. Ring-Number Distributions for Saturate Concentrates Derived from Five Coal Liquids and a Hydrotreated Shale Oil...

Hydrotreated shale oil has an advantage as a refinery feed. In contrast to most petroleum crude oils, it contains essentially no residuum. Properties of the hydrotreated product from whole shale oil are similar to those of distillate fractions from waxy petroleum Arabian or Sumatran crudes. An exception is the sulfur content which is much lower for hydrotreated shale oil than for most crudes. 

The 650°F+ fraction of the hydrotreated shale oil was processed in in FCC pilot plant, and the results show that it is an excellent feed for a conventional refinery. The resulting FCC yields, activity, and product qualities are quite similar to those derived from normal petroleum gas oils. 

The properties of the 650° F+ fraction of the hydrotreated shale oil also indicate that it will be an appropriate feed to an extinction recycle hydrocracker in situations where jet fuel is a desired product. Supporting pilot plant studies are described elsewhere (1,2,3). 

At this point, our original shipment of raw shale oil ran out. While waiting for the next shipment from Laramie, we reran some partially hydrotreated shale oil collected during off-test periods on other runs. 

Table III. Properties of Narrow Boiling Mid-Distillate Fractions from Hydrotreated Shale Oil Blend...

Table V. Properties of Naphtha Fractions from Hydrotreated Shale Oil Blends and from Arabian Light Crude...

Table VI. Comparison of Straight-Run Vacuum Gas Oils (VGO) with 650°F+ Hydrotreated Shale Oil...

The FCC process is the most common conversion unit in use today. As such, it is important to determine the performance of an FCC when feeding hydrotreated shale oil. The two 650° F+ feeds shown in Table VI were evaluated in an FCC pilot plant operating in a fixed fluidized-bed mode. The catalyst was withdrawn from an operating commercial FCC unit. It is a zeolite catalyst, CBZ-1, produced by Davison Chemical Division of W. R. Grace and Company and is moderately active as well as contaminated with metals. 

Table VIII. Catalytic Cracking of Hydrotreated Shale Oil...

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