Method And Apparatus For In Situ Distillation And Hydrogenation Of Carbonaceous Materials

Abstract

A method of distilling and hydrogenating the hydrocarbon content of carbonaceous materials wherein hot hydrogen is introduced into the carbonaceous material in sufficient quantity and at sufficient temperature to concurrently release and distill the hydrocarbon content. Preferred apparatus for practicing the method includes a source of hydrogen, means for varying the temperature of the hydrogen, an underground cavern in the carbonaceous material, and temperature modulating means at the face of the shale for regulating the temperature temperature of the hydrogen.

Parent Case Text

The present application constitutes a continuation-in-part of my copending application, Ser. No. 550,343, filed May 16, 1966, which has been abandoned in favor of this application.

Description

BRIEF DESCRIPTION

This invention relates to thermal distillation and hydrogenation of the hydrocarbon content of naturally occurring deposits of oil shales and other carbonaceous materials, without first removing them from their underground locations. It is concerned with both a method for accomplishing such distillation and hydrogenation and with apparatus for carrying out the method to advantage.

Vast deposits of oil shale, oil-bearing sand, and other carbonaceous materials exist in many regions of the world. Little has been done to exploit such deposits for removing their hydrocarbon content, largely because of the great expense involved in mining them, in refining them, and in handling the vast quantities of solid waste matter usually involved. In my U.S. Pat. No. 3,237,689, granted Mar. 1, 1966, I disclose a method and plant for distilling solid carbonaceous materials in situ, which involves the controlled application of heat generated, for example, by a nuclear reactor so as to reduce the cost of producing usable hydrocarbon products.

If the heat is transmitted to the in situ deposit of carbonaceous materials in the form of hot hydrogen substantially undiluted by other gases I have found that even greater savings can be realized in the recovery of usable oil and gasoline products, since these useful products are effectively and efficiently produced and are recovered directly from the formation, without significant expense involved in further processing recovered vapors.

My method is useful wherever deposits of oil-bearing shale or other carbonaceous materials are found and, in contradistinction to other processes employing hydrogen for mild hydrogenation, is highly efficient, since substantially pure hydrogen is used to both carry the heat and to hydrogenate the kerogen almost instantaneously as it is released in response to application of the heat. Excess hydrogen that is not consumed in removing oxygen, nitrogen, and sulfur from the kerogen is recycled and is reused.

The hot hydrogen can be from any source, but preferably will be obtained from a nuclear reactor utilizing hydrogen as a coolant or from carbonization of coal. However, the hydrogen can be produced and heated in any conventional commercial manner. Naturally, in the handling of the hydrogen, customary safety precautions must be taken to prevent its being combined with oxygen and inadvertently ignited.

There is shown in the accompanying drawings a specific embodiment of the invention representing what is presently regarded as the best mode of carrying out the generic concepts in actual practice. From the detailed description of this presently preferred form of the invention, other more specific objects and features will become apparent.

THE DRAWINGS

In the drawings:

FIG. 1 is a somewhat schematic top plan view showing a typical structural arrangement of novel apparatus for carrying out the method of the invention;

FIG. 2, a top plan view of a typical bore hole arrangement according to the invention, drawn to a smaller scale than the other views;

FIG. 3, a vertical section taken on the line 3-3 of FIG. 1; and

FIG. 4, a horizontal section taken on the line 4-4 of FIG. 3.

DETAILED DESCRIPTION

Referring now to the drawings:

In the illustrated preferred embodiment, the apparatus of the invention includes a suitable source of hydrogen, as indicated, feeding through pipe 11 to a heat exchanger 12 and thence through a pipe 13, and distribution pipes 14 (FIGS. 3 and 4) to a cavern 15 that surrounds an underground room 16. An access hole 17 extends from the ground surface 18 to the room 16 and provides a convenient throughway for the pipe 13.

The source of hydrogen can be a nuclear reactor from which hydrogen coolant is discharged at very hot temperature, or the hydrogen can be produced by carbonization of coal either in situ, or after it has been mined, it being known that when heated to between 1,200.degree.--1,500.degree. F. practically all coals evolve large quantities of hydrogen. In these instances it will be desirable, at least initially, to cool the hydrogen to a working temperature of about 800.degree. F. for oil shale and within the range of about 200.degree. to about 500.degree. F. for oil-bearing sands by means of the heat exchanger. However, any other commercial means of producing hydrogen can be employed, with heat being supplied by means of the heat exchanger if necessary.

In practicing the method of the invention, and as a safety measure, it is preferred that valve 19 in line 11 be operated to first admit a relatively inert and inexpensive gas such as carbon dioxide or nitrogen from a source of purging gas 20 into line 11 and through the entire system. After the system has been purged, the valve 19 can be either manually or automatically manipulated to cut off the purging gas and to admit hydrogen into line 11.

As the hydrogen is passed through the heat exchanger 12 its temperature is modulated, if required, in a manner to be further explained, and pump 21 forces it through lines 13 and 14 and into the cavern 15. Should the pressure in the system increase above that desired, relief valve 22 will open to allow flow of hydrogen through line 23 to a recycle conduit 24.

The hot hydrogen in cavern 15 acts directly on the face 25 of the deposit of carbonaceous material, and, as the heat releases hydrocarbons from the deposit, the hydrogen reacts therewith to separate contaminating oxygen, sulfur, and nitrogen from the useful hydrocarbons.

The temperature of the hydrogen at the face of the deposit is regulated by a thermostat 26, i.e. any suitable temperature control means, placed adjacent to the face. The thermostat is electrically connected to control valves 27 and 28, and, in response to signals of the thermostat the controls are regulated to supply hot or cold fluid through jacket 29 (FIG. 1) of the heat exchanger. Thus, the temperature of the hydrogen is modulated as it passes through jacket 29 in accordance with the signal transmitted by the thermostat 26.

If, for example, the hydrogen is too hot when it reaches the face of the material being treated, flow through valve 28 to the heat exchanger will be increased in proportion to flow through valve 27, to thereby decrease the temperature of control fluid in jacket 29. Similarly, if the temperature of the hydrogen at the face 24 is too cold, then flow through valve 27 will be increased proportionate to that through valve 28 to increase the temperature of the water in jacket 29. Obviously, any commercially available heat exchange system capable of modulating the temperature of the hydrogen passing through pipe 11 could as well be used.

The thermostat will be set to maintain the temperature of the hydrogen at the deposit face at least high enough to insure distillation of the hydrocarbon content of the deposit. For oil shales this will be about 800.degree. F. and for bituminous tar sands about 200.degree.--500.degree. F., for example.

As the hydrocarbons are released in response to the heat application and are acted on by the hydrogen the resulting reaction vapors are forced up recovery holes 30, that terminate in cavern 15, to condenser 31. Because the bituminous material has some natural cracks and fissures in it some of the hot hydrogen is forced therein, and the vapors released and treated are forced up recovery holes 32 spaced away from the cavern. The cracks and fissures may increase as the hydrocarbon material is removed, apparently due to a settling of the material. If desired, the porosity of the material can be increased in preparation for treating in accordance with the invention. Thus, for example, explosives can be used in the fracturing process. Also, the temperature of the hydrogen can be increased as required to cause fracturing. For oil shale material, this has been found to be at least 2,000.degree. F., but not so high that fusion of the shale results. The fusion temperature is readily determined by laboratory tests on the material being treated. When this amount of heat is applied, it has been found that fissures are formed in the shale that extend ahead of the advancing thermal front. These fissures then provide channels in which the hot hydrogen can travel to more efficiently distill and hydrogenate the material being treated.

The spacing and number of recovery holes 30 and 32 will be in accordance with good design practices and will depend on the characteristics of the deposit being treated, the volume of hydrogen available and the equipment available for use.

Collector pipes 34 carry the vapors from the recovery holes 30 and 32 to the condenser 31.

The recovered vapors are passed into condenser 31 and useful hydrocarbon products are condensed and discharged through line 35. The gases are then separated at 36 and the unconsumed hydrogen is recycled through line 24 back to line 11, from where it can again be used in the distillation and hydrogenation process. The remaining gases are discharged through line 37 and can be used to operate a steam electric generating plant that will then generate the electrical energy necessary to operate the pumps and auxiliary equipment of the system in the manner disclosed in my U.S. Pat. No. 3,237,689. If desired, these gases could also be used for other purposes.

Door 38, through the insulated wall 39 of room 16, allows access by workmen to cavern 15 and the face of the carbonaceous material. Thus, the thermostat can be readily repositioned on the face as found desirable, and, if desired, it can be inserted in a plugged bore hole in the manner disclosed in my aforementioned U.S. Pat. No. 3,237,689.

It is within the scope of the invention that very high temperatures can be used to crack and fissure an area of shale surrounding the cavern 15 into which the hot hydrogen is supplied and thereafter the temperature may be reduced to permit efficient distillation of the hydrocarbon content.

Since during the release of hydrocarbons, hydrogen is also released from the carbonaceous bearing material, it is also within the scope of the invention that once the process is underway the released hydrogen is collected and cycled along with that from the illustrated hydrogen source, thus reducing the amount of hydrogen required from the illustrated source.

Whereas this invention is here described and illustrated with respect to a certain form thereof, it is to be understood that many variations are possible.

Claims

I claim:

1. A method of distilling and hydrogenating the hydrocarbon content of a deposit of carbonaceous material in situ, which comprises the steps of

introducing into such a carbonaceous material substantially pure

hydrogen at a temperature high enough to crack and fissure an area of the carbonaceous material beyond the point of introduction of said hydrogen;

thereafter regulating the temperature of the hydrogen to continue its introduction into the carbonaceous material at a lower temperature sufficient to release the hydrocarbon content of the material as a vapor; and

recovering fluid products produced by reaction of the hydrogen with heat-released hydrocarbon vapors.

2. Apparatus for distilling and hydrogenating the carbonaceous content of carbonaceous materials, in situ, comprising

a source of substantially pure hydrogen;

an underground cavern in which humans can work formed in a deposit of material to be treated;

means for transporting the hydrogen from the source to the face of the deposit defining the cavern;

means for modulating the temperature of said hydrogen to maintain the hydrogen at the face at a desired temperature for distillation of the carbonaceous materials; and

means for recovering distilled and hydrogenated products resulting from the application of said hydrogen to said face of the deposit.

3. Apparatus for distilling and hydrogenating the carbonaceous content of carbonaceous materials, in situ, comprising

a source of substantially pure hydrogen;

an underground cavern formed in a deposit of material to be treated;

means for transporting the hydrogen from the source to the face of the deposit defining the cavern;

a heat exchanger through which the hydrogen is passed for modulating the temperature of said hydrogen to maintain it at the face of the deposit at a desired temperature for distillation of the carbonaceous material;

a thermostat at the face of the deposit;

means for changing the effect of said heat exchanger on the hydrogen passed therethrough in response to the temperature sensed by the thermostat; and

means for recovering distilled and hydrogenated products resulting from the application of said hydrogen to said face of the deposit.

4. Apparatus according to claim 3, further including

an insulated room in the cavern;

an access hole extending from the ground surface to the room; and

an access door allowing individual movement from within said room to the face of the deposit.

5. Apparatus according to claim 3, further including

means for supplying purging gas through the means for transporting hydrogen from the source to the face of the deposit prior to the supplying of hydrogen therethrough.

6. Apparatus according to claim 3, further including

means for recycling unconsumed hydrogen recovered with the distilled and hydrogenated products.

7. A method of distilling and hydrogenating the hydrocarbon content of a deposit of carbonaceous material in situ, which comprises the steps of

purging the carbonaceous material by the introduction thereinto of an inert gas;

introducing into the purged carbonaceous material substantially pure hydrogen at a temperature adapted to release the hydrocarbon content of the material as a vapor; and

recovering fluid products produced by reaction of the hydrogen with heat-released hydrocarbon vapors.

8. A method of distilling and hydrogenating the hydrocarbon content of a deposit of oil shale in situ, which comprises the steps of

applying substantially pure hydrogen to an exposed face of the shale at a temperature sufficient to fissure the shale as the heat front advances, but not high enough to cause fusion of the shale;

introducing into the fissured shale substantially pure hydrogen at a temperature adapted to release the hydrocarbon content thereof as a vapor; and

recovering fluid products produced by reaction of the hydrogen with heat-released hydrocarbon vapors.

9. The method of claim 8, wherein the temperature at which the hydrogen is applied is at least 2,000.degree. F.

10. The method of claim 9, wherein the hot hydrogen is supplied by a nuclear reactor.

11. Apparatus for distilling and hydrogenating the carbonaceous content of carbonaceous materials in situ, comprising

a heat exchanger;

means for passing substantially pure hydrogen through said heat exchanger in heat exchange relationship with a thermal fluid;

means for introducing the hydrogen into an underground deposit of carbonaceous material;

temperature responsive means within said underground deposit;

means for modulating the temperature of the hydrogen for maintaining it at a desired temperature for distillation of the carbonaceous material; and

means for recovering distilled and hydrogenated products resulting from the introduction of the hydrogen into the carbonaceous material.

12. A method of distilling and hydrogenating the hydrocarbon content of a deposit of a carbonaceous material in situ, comprising the steps of

heating substantially pure hydrogen to a temperature sufficient to release the hydrocarbon content of said carbonaceous material as a vapor;

introducing said heated hydrogen into the carbonaceous material in the natural unheated state of said material; and

recovering fluid products produced by reaction of the hydrogen with the heat-released hydrocarbon vapors.

13. The method of claim 5 wherein

hydrogen released from the carbonaceous material is collected and circulated with the unconsumed hydrogen introduced into the carbonaceous material from a source independent of the said carbonaceous material.

14. The method of claim 5 further including the steps of

condensing the vapor products to form useful oil products;

separating extraneous gases from unconsumed hydrogen; and

recycling the unconsumed hydrogen into the carbonaceous material.

15. The method of claim 5 wherein

the temperature of the hydrogen is modulated prior to introduction in accordance with the release temperature of the hydrocarbon vapors.

16. The method of claim 5 wherein hydrogen is introduced in excess of the stoichiometric amount necessary to react with the oxygen, nitrogen, and sulfur present in the kerogen.

17. The method of claim 16, wherein the excess hydrogen is recycled in continued application of the process.