Method for recovery of hydrocarbon oils from oil shale and other carbonaceous solids
A continuous, efficient surface method for thermal recovery of hydrocarbons from a solid feedstock is described that includes a self-contained process that produces hydrogen for upgrading the hydrocarbons to produce motor fuel. The hydrogen also is used as a clean burning fuel for the thermal processing. The hydrogen is produced as a component of synthesis gas formed by gasification of coal. The synthesis gas is processed to remove and dispose of carbon dioxide and by-product sulfur. Combustion of the hydrogen to provide indirect heating of the solid feedstock maximizes hydrocarbons that can be upgraded and reduces or eliminates the emission of carbon dioxide into the atmosphere.
This invention was made with government support under DOE/SBIR Grant DF-FG-02-06ER84596. The Government has certain rights to this invention.
BACKGROUND OF THE INVENTION1. Field
This invention relates to methods for recovering hydrocarbon oils from various solid materials. More specifically, this invention is directed to methods for recovering hydrocarbon oils from oil shale, tar sands and other carbonaceous materials.
2. Statement of the Art
Oil has been produced commercially from shale since at least as early as the mid-nineteenth century. Currently, oil production from shale is being pursued in eighteen different countries world-wide. Over the past century, the extensive oil shale deposits of the western United States have been viewed as being a potential solution to the nation's energy problems. The economic viability of oil production from shale deposits has been affected by the expansion of crude oil availability. As the price for crude oil has risen due to political instability in the Middle East, a renewed interest in oil shale production has emerged. During the Carter Administration, the President announced a massive program to produce 2.5 million barrels of crude oil per day from coal and oil shale by 1990. However, a subsequent drop in oil prices resulted in a substantial discontinuation in investment in oil shale technology and research. Recently, political unrest and hostilities in the Arabian Gulf have again resulted in significant increases in the price of crude oil thereby reinvigorating the interest in the processing of the national reserves of oil shale and tar sands.
Past oil shale recovery techniques have typically made use of some form of heating to drive off the oil from the rock. Both in-situ (below ground) and above ground heating processes have been used. The advantages of the in-situ processes include:
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- (1) Mining of the shale is typically minimal or not required;
- (2) no disposal of the spent shale is mandated;
- (3) the process permits access to resources which are otherwise not minable;
- (4) the process allows for the use of lower quality shale; and
- (5) the process requires no crushing of the shale or transportation of the shale to a processing facility.
Although past in-situ shale recovery processes have significant advantages, they are not, however, devoid of disadvantages. Some of these disadvantages are as follows:
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- (1) such processes involve significant drilling costs;
- (2) control of the recovery process is oftentimes difficult;
- (3) such processes typically recover a low percentage of the available shale oil;
- (4) the oil shale treated typically has low permeability restricting flow rates of the shale oil and gas;
- (5) such processes carry the possibility of water contamination in the area in which the processes are employed;
- (6) control of the shale bed boundaries and operating conditions are difficult;
- (7) such processes typically have very long residence times; and
- (8) such processes conventionally consume high quantities of expensive energy, especially those processes which utilize electricity as the heating source.
The alternative approach of above ground processing offers the following notable advantages:
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- (1) high recovery efficiency;
- (2) improved control of process conditions;
- (3) easy product recovery; and
- (4) continuous processing capability.
Despite these advantages, prior development of methods for surface processing of U.S. shale ore to recover shale oil have not resulted in commercial viability and they have been criticized for producing unacceptable air emissions.
Another consideration of importance in the economical recovery and use of shale oil is the difference between shale oil and the oil produced from conventional oil wells. The conjugated olefin structure of the hydrocarbon molecule of crude shale oil requires substantial upgrading before it can be efficiently used as a motor fuel. Relatively large quantities of hydrogen and high temperature and high pressure catalytic operating conditions are required for the processing of the shale oil. The upgrading requirements and the availability of the hydrogen to carry out the upgrading often render such oil unamenable to the processing capabilities of existing conventional oil refineries.
It is readily apparent that there continues to be a need for more efficient and more environmentally acceptable processing methods for producing high quality oil products from solid feedstocks such as oil shale.
SUMMARY OF THE INVENTIONA process suited for thermally removing liquid hydrocarbons from a solid feedstock and upgrading these liquids is disclosed. The process is specifically directed to continuously removing condensable hydrocarbons from such feedstocks as oil shale. In preferred embodiments, the process is utilized on the surface as opposed to below the surface of the earth.
The process may include the following steps:
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- (1) Preparing a first solid feedstock to a predetermined size and moisture content;
- (2) Preparing a second solid feedstock to complement first solid feedstock;
- (3) Drying and pre-heating the first solid feedstock;
- (4) Providing a reactor suited for processing the first solid feedstock at an elevated temperature;
- (5) Providing sufficient clean burning fuel to heat the reactor;
- (6) Providing a heated reactor sweep gas;
- (7) Feeding the first solid feedstock into the reactor to thermally liberate hydrocarbons from the first solid feedstock;
- (8) Directing the heated reactor sweep gas through the reactor to remove the hydrocarbons from the reactor;
- (9) Cooling the hydrocarbons to condense liquid hydrocarbons;
- (10) Separating the liquid hydrocarbons from gaseous hydrocarbons, other reactor off-gases and reactor sweep gas;
- (11) Treating the liquid hydrocarbon with hydrogen to produce a hydro treated and/or hydro cracked liquid hydrocarbon;
- (12) Processing the second solid feedstock and the reactor off-gases to produce a syngas;
- (13) Processing the syngas to produce an amount of hydrogen sufficient to hydro treat the liquid hydrocarbons producing the hydro treated liquid hydrocarbons and also to provide the clean burning fuel to heat the reactor.
In an alternative embodiment, the quantity of second solid feedstock which is processed is limited to the amount sufficient to solely produce an amount of hydrogen sufficient to hydro treat the hydrocarbons liberated from the first solid feedstock and to provide the thermal energy requirements for operating the reactor vessel.
In a preferred embodiment the process is utilized to process a first solid feedstock which may be oil shale or tar sands. Other first solid feedstocks are also within contemplation.
The processing of the second solid feedstock may include the use of a gasifer or alternatively may include the reforming of the second solid feedstock to produce the requisite hydrogen. Processing steps may be incorporated downstream of such a gasifier to remove carbon dioxide from the syngas produced by the gasifier in order to reduce carbon dioxide emissions. Various gasifier constructions may be utilized in the process, including but not limited to entrained gasifiers, fixed bed gasifiers and fluidized bed type gasifiers. In an alternative embodiment of the process, the second solid feedstock is processed by steam reforming. The process may utilize a number of solid, liquid and/or gases for second solid feedstocks such as, but not limited to, coal, gilsonite, petroleum and natural gas.
The reactor vessel utilized in the process may be an indirectly heated rotary kiln, or a stationary, i.e., non-rotating reactor with solid screw feed system and transport system. The reactor vessel may be constructed for operation at or near atmospheric pressure conditions. Alternatively, the reactor may be adapted for use at elevated pressures to thereby increase the capacity of the reactor.
As shown in
Shale ore 40 is mined and then crushed to a preselected size in processing step 41. The crushed shale ore 42, which forms the feedstock of the overall recovery process is introduced into preheating and drying unit 45 where, in direct contact with flue gas 48 from shale oil processing rotary kiln unit 50, it is dried and pre-heated. The cooled flue gas 37 enters flue gas cleaning unit 36 where solid particulates 38 are separated before the gas is vented to the atmosphere 39. Gas cleaning unit 36 may be a baghouse.
The dry and preheated shale 46 then enters shale ore processing rotary kiln unit 50 together with sweep steam 47. The shale is heated and pyrolysed sufficiently in unit 50 to liberate shale oil liquid, vapor and gas 53 from spent shale 51. Spent shale 51 is contacted and partially combusted with air 57 in spent shale processing unit 55. Spent shale processing unit 55 may be a fluidized bed. Heated and oxygen containing gas 56 from unit 55 enters a burner assembly surrounding shale ore processing unit 50 where it combusts with hydrogen 28B to indirectly heat the oil shale 46.
Shale oil liquid, vapor, shale gas and steam 53 are then cooled and separated in shale oil separation unit 60. (See
The pulverized coal within vessel 113 passes into lock hopper vessel 116, where it is pressurized by recycled off-gas 69D. Following pressurization it passes into feed vessel 117 then through feeding device 122 where it is picked up by recycled off-gas 69C and blown into the gasification reactor 18. Oxygen 16 from oxygen separator 15 is fed into gasification reactor 18 together with steam 17A. Ash produced in the gasification reactor drops into ash lock 131 where is picked up by a water stream 155 and periodically discharged 132 to separator 151. A particulate and ash stream 20 from separator 151 is combined with spent shale stream 52 for landfill disposal. (See
In another embodiment of the invention, hot cyclones are positioned upstream of gas cooler 140 or filter 141. The cyclones are used to remove the coarser ash and carbon particles. Wet scrubber 146 removes the final traces of particulates. Ammonia and trace metal compounds like lead, mercury and arsenic, present in very small amounts, are also removed at wet scrubber 146.
Steam is produced in cooling passages of coal gasification reactor 18, in gas cooler 140 and HRSG 35.
As shown in
As further shown in
The syngas stream from amine unit 144 contains hydrogen, carbon monoxide, carbon dioxide and small amounts of methane, nitrogen and argon. The hydrogen is separated from this mixture in a pressure swing absorption unit 145 that produces 99% pure hydrogen 28 for plant hydro-processing 28A and fuel needs 28B and 28C. (See
Flue gas 37 is drawn from drier and heater 80 and through cyclones 82 and dust bag house 83 by fan 84 and then exhausted to the atmosphere through stack 85. Dust 38 from the cyclones and bag house is transported to the dry, pre-heated ore stream 46 by conveyors 85 and 86.
In rotary kiln 90 the shale ore is indirectly heated to a temperature typically between 900 F and 1100 F resulting in pyrolysis reactions releasing oil liquid, vapor, hydrocarbon gases, hydrogen, carbon monoxide, carbon dioxide and hydrogen sulfide. This final temperature must be closely controlled in order to release the hydrocarbon material while not releasing significant amounts of CO2 by decomposition of the calcite and dolomite (carbonate) materials present in the shale ore.
Kiln 90 is heated by burning hydrogen 28B with pre-heated oxygen rich flue gas 56 from the spent shale processor 55, which may be a fluidized bed contactor 94. Flue gas 56 is produced by blowing air with fan 95 through spent shale processor 94 where it is heated and reacts with charred hydrocarbon material in the spent shale.
Coal ash slurry 20 is fed into the lower outlet of kiln 90 to enable disposal with the spent shale. The spent shale and ash are discharged through screw 89 into spent shale processor 94. Waste water stream 64 enters the lower section of processor 94 to enable disposal of waste water with the spent shale and the cooled, moist spent shale and ash 52 is discharged through screw 98. In an alternate embodiment, in order to take advantage of the cement like properties of the spent shale and ash the feed rate of water in stream 64 may be adjusted and proportioned so as to obtain a moisture content of about 20% in the resultant mixture.
Shale oil, liquids, vapors and gases 53 pass through cyclone 91 before leaving kiln 90 in order to remove entrained particulates. Fine particulates are removed from the gases 53 using electrostatic precipitator 92. In an alternative embodiment precipitator 92 may be eliminated.
The shale gas 166 is then further cooled to 150-175 F using a water stream (condensed steam) in gasoline condenser 170. A gasoline boiling cut 61C is condensed out in this step, along with most of the steam 64A. Gasoline boiling cut 61C is thereafter directed through cooler 165C and pump 174. Steam 64A is directed through pump 175. A portion of stream 64A is directed to an air cooler 162 and subsequently reintroduced into condenser 170. A gas and water vapor mixture 167 is withdrawn from condenser 170 and is The gas is next compressed to 100 psig by gas compressor 178 and cooled in a water-cooled heat exchanger 165D, where the remainder of the steam [water] and a fraction of the shale oil is condensed. Gases 62, composed of C1, C2, C3, CO, CO2, H2, and H2S, are sent to the coal gasification and hydrogen production and purification section of the plant. The C4, C5 and C6 fraction 61D is directed to further processing. The condensate gases are directed to a receiver gravity separator vessel 190 which functions to separate light gases 62 from liquids 61D (C4-C6 fractions) (and water 64B. Water 64B is thereafter directed through pump 176 and thereafter mixed with water 64A, which is exiting pump 175, to form water stream 64. A portion of residual product 70A is recycled through compressor 211 to heater 201 and hydro cracker 204.
Diesel fraction 61B, diesel fraction stream 191 and hydrogen stream 28A2 pass through heater 202 and then pass through hydro pyrolysis unit 205. The resulting upgraded liquids are then separated in cooler and knock-out 208 from unreacted excess hydrogen 222 and off-gases 66B. The unreacted excess hydrogen is compressed and recycled by compressor 217 and the off-gas 66B is compressed in compressor 218 and recycled to the coal gasification and hydrogen production section of the plant. The final upgraded diesel product is stream 70B.
Gasoline fraction 61C, C4-C6 fraction 61D and gasoline fraction stream 192 pass with hydrogen stream 28A3 through heater 203 and then through hydro pyrolysis unit 206. The resulting upgraded liquids 223 are then separated in cooler and knock-out 209 into unreacted excess hydrogen 224 and off-gases 66C and gasoline product 225. The gasoline product 225 is then passed through reformer 210 to form gasoline product 70C. The unreacted excess hydrogen 224 is compressed and recycled by compressor 217 and the off-gas 66C is compressed in compressor 218. Both gases are recycled, with some of the gases being directed to the coal gasification and hydrogen production section of the plant. The upgraded liquid 225 is sent to reformer 70C to produce the final gasoline product, stream 70C. The off gases 66A, 66B, 66C and 220 are compressed by compressor 218 and a portion thereof is used as fuel for heaters 201, 202 and 203. The balance of the gases 66 is combined with off gas 62 to form stream 69 (See
All hydrogen produced in the process is used either for liquid upgrading or for producing process heating, with any excess being used for generating steam. Any steam so generated which is not needed for the process would be sent to a turbine for purposes of electrical power generation.
Changes may be made to the embodiments described in this disclosure without departing from the broad inventive concepts they illustrate. Accordingly, this invention is not limited to the particular embodiments disclosed, but is intended to cover all modifications that are within the scope of the invention as defined by the appended claims.
Claims
1. A surface method for continuously producing hydro treated and/or hydro cracked liquid hydrocarbons from a solid feedstock, said method comprising:
- preparing a first solid feedstock to a predetermined size and moisture content;
- preparing a second solid feedstock to complement first solid feedstock;
- providing a reactor suited for processing said first solid feedstock at substantially atmospheric pressure;
- providing sufficient thermal energy to said reactor to operate said reactor;
- preheating a reactor sweep gas;
- feeding said first solid feedstock into said reactor to thermally liberate hydrocarbons from said first solid feedstock;
- directing said preheated reactor sweep gas through said reactor to remove said hydrocarbons from said reactor;
- cooling said hydrocarbons to condense liquid hydrocarbons;
- separating said liquid hydrocarbons from gaseous hydrocarbons, other reactor off-gases and reactor sweep gas;
- treating said liquid hydrocarbon with hydrogen to produce a hydro treated and/or hydro cracked liquid hydrocarbon;
- gasifying or reforming said second solid feedstock to produce a syngas; and
- processing said syngas to produce an amount of hydrogen sufficient to hydro treat said liquid hydrocarbons, producing said hydro treated liquid hydrocarbons and also to provide said clean burning fuel to heat said reactor.
2. The method of claim 1, wherein said first solid feedstock is oil shale.
3. The method of claim 1, wherein said first solid feedstock is tar sands.
4. The method of claim 1, wherein said second solid feedstock is coal.
5. The method of claim 1, wherein said reactor is an indirectly heated kiln.
6. The method of claim 5, wherein said kiln is a rotary kiln.
7. The method of claim 1, wherein said condensing is accomplished using a coolant.
8. The method of claim 7, wherein said coolant is water.
9. The method of claim 1, wherein off-gases produced in said reactor are captured and utilized in said method to provide a source of heat.
10. The method of claim 1, wherein spent said first solid feedstock is collected from said reactor, said spent first solid feedstock being mixed with said second solid feedstock during said gasifying.
11. The method of claim 1, wherein fines produced during said preparing of said first solid feedstock are mixed with said second solid feedstock during said gasifying.
12. The method of claim 1, wherein said gaseous hydrocarbons and said reactor off-gases are mixed with said second solid feedstock during said gasifying.
13. The method of claim 1, wherein said gasifying is accomplished in a device selected from a group consisting of an entrained gasifier, a fixed gasifier and a fluid bed gasifier.
14. The method of claim 1, wherein said syngas is processed to remove particulates and contaminants from said syngas.
15. The method of claim 14, wherein said contaminants include sulfur and carbon dioxide.
16. The method of claim 1, wherein said gasifying or reforming of said second solid feedstock is performed physically proximate to said reactor.
17. The method of claim 1, where the treating of said liquid hydrocarbon with hydrogen to produce hydro treated and or hydro cracked liquid hydrocarbon is preformed physically proximate to said reactor.
18. The method of claim 1, wherein said thermal energy is provided by burning said second solid feedstock directly.
19. The method of claim 1, wherein said second solid feedstock is selected from the group consisting of coal, natural gas, gilsonite, spent shale and shale fines.
20. The method of claim 1, wherein said reactor is a stationary reactor having a solid screw feed system and transport system.
21. The method of claim 1, wherein said reactor is also suited for operation at elevated pressures.
22. The method of claim 20, wherein said reactor is operated at a pressure which exceeds atmospheric pressure.
23. The method of claim 1, wherein spent said first solid feedstock and off-gas produced in said reactor are subsequently burned to generate electrical energy.
24. The method of claim 1, wherein said reactor sweep gas is formed by heating water to produce steam.
25. The method of claim 1, wherein said second solid feedstock is selected from the group consisting of a solid, liquid and gaseous feedstock.
26. The method of claim 24, wherein said second solid feedstock is selected from the group consisting of gilsonite, petroleum and natural gas.
27. The method of claim 1, further comprising processing spent said first solid feedstock to produce cement.
28. The method of claim 1, wherein the second solid feedstock is further processed to produce a fuel.
29. The method of claim 28, wherein said fuel is further processed to remove particulates and contaminants.
30. The method of claim 28, wherein said fuel is combusted to provide the thermal energy requirements of said reactor.
31. The method of claim 1, wherein said first solid feedstock is preheated.
32. The method of claim 31, wherein said first solid feedstock is preheated using a heated gas selected from the group consisting of effluent gas, a reactor off-gas and gas produced from a combustion of spent said first solid feedstock.
33. The method of claim 1, wherein said sweep gas is preheated using a heated gas selected from the group consisting of effluent gas, a reactor off-gas and gas produced from a combustion of spent said first solid feedstock.
34. The method of claim 1, wherein said second solid feedstock is processed in a quantity sufficient to solely heat said reactor during said processing of said first solid feedstock and produce a quantity of hydrogen sufficient to hydro treat said liquid hydrocarbon.
35. A continuous surface method for producing hydro treated and/or hydro cracked liquid hydrocarbons from a solid feedstock, said method comprising:
- preparing a first solid feedstock to a predetermined size and moisture content;
- preparing a second solid feedstock to complement the first solid feedstock;
- providing a reactor suited for processing said first solid feedstock at substantially atmospheric pressure;
- heating said reactor;
- preheating a reactor sweep gas;
- feeding said first solid feedstock into said reactor to thermally liberate hydrocarbons from said first solid feedstock;
- directing said preheated reactor sweep gas through said reactor to remove said liberated hydrocarbons from said reactor;
- cooling said hydrocarbons to condense liquid hydrocarbons;
- separating said liquid hydrocarbons from gaseous hydrocarbons, other reactor off-gases and said reactor sweep gas;
- treating said liquid hydrocarbon with hydrogen to produce a hydro treated and/or hydro cracked liquid;
- gasifying or reforming said second solid feedstock to produce a syngas;
- further processing said syngas to remove particulates, sulfur, carbon dioxide and other contaminants and to produce hydrogen;
- combusting a fuel selected from the group consisting of said second solid feedstock, said syngas, spent said first solid feedstock, said reactor off-gas, fines produced during said preparing of said first solid feedstock, and said hydrogen;
- utilizing heat produced from said combusting to heat said reactor and said preheating reactor sweep gas; and
- preheating said first solid feedstock by direct contact with hot flue gas from said combusting or from gases produced by combusting a fuel selected from the group consisting of said second solid feedstock, said syngas, spent said first solid feedstock, said reactor off-gas, and said hydrogen.
36. A method of claim 35, wherein said second solid feedstock syngas is shifted to produce mostly hydrogen and then cleaned to remove sulfur, carbon dioxide and other contaminants producing a nearly pure hydrogen stream.
37. A method of claim 36, wherein said hydrogen is divided into two portions, the first to hydro treat and/or hydro crack said liquid hydrocarbons and the second portion of said hydrogen combusted with air within the external shell of said reactor to produce principally high temperature steam and nitrogen with no carbon dioxide.
38. A method of claims 36 and 37, which results in little or no emissions of carbon dioxide gas from such process method in order to reduce the impact on global warming.
Type: Application
Filed: Feb 23, 2007
Publication Date: Aug 28, 2008
Applicant: Combustion Resources, L.L.C. (Provo, UT)
Inventors: Kent E. Hatfield (Salt Lake City, UT), Ralph L. Coates (Salt Lake City, UT), L. Douglas Smoot (Provo, UT)
Application Number: 11/710,389
International Classification: C10G 1/06 (20060101);