Mineral oils: processes and products – Tar sand treatment with liquid
Reexamination Certificate
2002-07-12
2004-03-23
Griffin, Walter D. (Department: 1764)
Mineral oils: processes and products
Tar sand treatment with liquid
C208S408000, C208S428000, C208S433000, C208S434000, C201S030000, C423S352000
Reexamination Certificate
active
06709573
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention is related to the recovery of hydrocarbons from solid carbonaceous materials, and more specifically to an improved process using syn gas and liquid hydrocarbon in a generally horizontal rotary kiln.
2. Background
Worldwide demand for hydrocarbons and related petrochemicals and fertilizers is increasing at a rapid annual rate. Crude petroleum and natural gas are basic in satisfying these demands while at the same time many industries have experienced shortages despite the discovery of new oil and gas sources. Therefore, alternate solid hydrocarbon sources and feed stocks, such as coal, tar sands, oil shale and solid crudes present an ever increasingly attractive source for meeting demand for hydrocarbon products.
Oil shale and tar sands, also known as oil sands and bituminous sands, arc particularly promising sources of these needed products as large deposits are found in Canada and the United States. The largest known deposit of oil shale is the Green River formation in Utah, Colorado and Wyoming with about a third of such deposits in the state of Utah. The hydrocarbon resource locked in the Green River formation has been estimated to be in excess of 1.5 trillion barrels. This is a considerable resource considering known world oil shale reserves amount to just over 2.5 trillion barrels, by conservative estimates.
The demand for hydrocarbon resources makes development of the Green River formation virtually certain. During the 1970s and 1980s several oil shale operations were developed in Colorado and Utah, however due primarily to economic considerations most of these operations have since ceased. An average recovery of about 29 to 34 gallons of oil per ton of oil shale was typical of these previous recovery efforts.
Green River oil shale is a pctroliferous material (heavy viscous oil material) which is as high as 25% by weight with an average of 12% by weight hydrocarbon. The recovered oil is about 17°-25° API gravity, frequently averaging about 21°, and contains a low amount of sulfur and low aromaticity. The Green River shale has relatively high moisture content of between about 0.4% to 6%. Ranges for analysis of several samples of Green River oil shale are shown in Table 1. The balance of the components, not shown in the table, are made up primarily of various minerals and trace metals.
TABLE 1
Components
Green River Oil Shale (wt %)
Carbon
9.1-19.6
Organic Carbon
6.7-15.7
Hydrogen
1.1-2.0
Nitrogen
0.2-0.7
Sulfur
0.9-3.4
Fisher Assay
Oil
3.4-11.6
Water
0.4-5.9
Residue
83.4-91.0
Gas liquor
0.8-3.3
Gas and loss
2.1-4.1
The largest known deposits of tar sands are the Athabasca sands found in northern Alberta, Canada which underlay more than 13,000 square miles at a depth up to 2,000 ft. Of the 24 states in the United States that contain tar sands, about 90% of such deposits are in the state of Utah. The hydrocarbon resource locked in the Utah tar sands has been estimated to be in excess of 25 billion barrels.
However, the Utah tar sands, being of non-marine origin, have somewhat different chemical and physical characteristics than the Athabascan sands which are of marine origin, and do not respond as well to the traditional process used to extract oil from tar sands. Utah tar sands are generally hard consolidated sand stone closely associated with pctroliferous material (heavy viscous oil material) which is as high as 13% by weight with an average of 10.5% by weight hydrocarbon. The oil is about 13°-18° API gravity and contains a low amount of sulfur, e.g. less than about 0.9% by weight, low aromaticity and a very low water content. The Athabascan sand has an encapsulating water film surrounding each sand grain, which makes it amenable to a water-wetting process. The absence of this water film on the Utah sand grain necessitates using other technology for extracting the oils.
A comparison of the Athabascan tar sands with a sample of Utah tar sands obtained from Asphalt Ridge is shown in Table 2.
TABLE 2
Asphalt
Components
Athabasca Sands
Ridge Sands
Carbon (wt-%)
82.6
84.4
Hydrogen (wt-%)
10.3
11.0
Nitrogen (wt-%)
.47
1.0
Sulfur (wt-%)
4.86
.75
Oxygen (wt-%)
1.8
3.3
Average Mol. Wt (VPO-benzene)
568
820
Viscosity (poise)
6,380
325,000
77° F. (cone-plate at 0.05 sec)
Volatile material (535° C.) (wt-%)
60.4
49.9
The high viscosity, low sulfur content, low water content and other significant differences keep the Utah tar sands from responding well to commonly used extraction processes.
A number of oil recovery methods related to oil shale and tar sands have been tested in the laboratory or in small operations in the field. These processes involve various techniques such as hot water processes, cold water processes, solvent processes, thermal processes and the like, but in most eases, they possess certain limitations which make them unsuitable for use on a commercial basis. Further, many of these processes leave over 20% of the organic carbon behind in the spent shale. A process which would be effective with these particular oil shales and tar sands would be a significant advance in the art.
It is an object of the invention, therefore, to provide a new and efficient process for the extraction of hydrocarbonaceous material from solids containing such material and particularly from Green River oil shale. Another object of the present invention is to provide unique synergies to facilitate the economical production of various products from hydrocarbonaceous solids. It is a further object to provide such an extraction process which could utilize equipment now in commercial use, meet present day EPA standards and could be rapidly put into commercial production to meet the urgent demand for various hydrocarbon products.
SUMMARY OF THE INVENTION
It has now been discovered that these and other objects can be accomplished by the process of the present invention which relates to a new and improved process for extracting oil and other valuable hydrocarbons from crushed hydrocarbonaceous solids, such as oil shale, by means of a thermal technique using a special source of heat. The process of the present invention represents an improvement upon U.S. Pat. No. 4,725,350, hereby incorporated by reference in its entirety, and which is also the work of the present inventor.
Specifically, the present invention provides a new and efficient process for extracting valuable oils and other hydrocarbons from crushed hydrocarbonaceous solids which comprises blending the crushed solids to provide a substantially uniform feed composition and preheating the crushed hydrocarbonaceous solids to remove residual water. The crushed solids are treated in a generally horizontal rotary kiln having a slight slope downward with hot syn gas containing hydrogen and carbon dioxide at an elevated temperature and sprayed liquid hydrocarbon in the absence of water. The pressure inside the kiln is maintained below 30 psi and the crushed solids are cascaded into the hot syn gas for sufficient time to strip volatile hydrocarbon containing liquids and gases found in the crushed solids. The hydrocarbon rich vaporized materials, enriched syn gas and spent solids are removed from the kiln and the gaseous products are fractionated into desired fractions.
In a more detailed aspect of the present invention the hot syn gas is introduced into the rotary kiln at a temperature between 1000° F. and 2500° F. and the crushed solids are preheated to a temperature between 100° F. and 350° F. to reduce the heating load on the kiln.
In yet a more detailed aspect of the invention the hot syn gas is the product of coal gasification. Further, the enriched syn gas may be used as a starting material for the manufacture of other products such as methanol, ammonia, urea and natural gas or combusted and utilized in a combined-cycle electricity generation step to supplement the heating ad, power needs of the process.
The new process presents distinct advantages over the known processes for extraction of hydrocarbons from oil shale, and is particularly adapted for use i
Griffin Walter D.
Thorpe North & Western LLP
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