US 3237689 A
Description (OCR text may contain errors)
March 1, 1966 DISTILLATION OF U NDERGROUND DEPOSITS OF SOLID CARBONACEO Filed April 29, 1963 C l. JUSTHEIM US MATERIALS IN SITU 3 Sheets-Sheet 2 cLaRg/cz u. JUSTHEIM,
Zn g l 4,, w 4 7M March 1, 1966 c. JUSTHEIM DISTILLATION OF UNDERGROUND DEPOSITS OF SOLI CARBONAGEOUS MATERIALS IN SITU 5 Sheets-Sheet 5 Filed April 29, 1963 INVENTOR. CLARENCE JUSTHEIM W M -M ATTORNEYS United States Patent 3,237,689 DISTILLATION OF UNDERGROUND DEPOSITS OF SOLID CARBONACEOUS MATERIALS 1N SITU Clarence I. Justheim, 709 Walker Bank Bldg, Salt Lake City 11, Utah Filed Apr. 29,1963, Ser. No. 276,635
4 Claims. (Cl. 166-11) The present application is a continuation-in-part of my similarly entitled application Serial No. 785,552, filed January ,5, 1959, which is a continuation-in-part of my previously co-pending, but now abandoned, application Serial No. 537,123, filed September 28, 1955.
This invention relates to the thermal distillation, i.e. decomposition, of naturally occurring deposits of solid carbonaceous materials, without first removing them from their underground locations. It relates also to the recovery of the products of distillation, and is concerned with both method and plant for the purpose.
Vast deposits of oil shale exist in many regions of the World. Very little has been done in the Way of exploiting such deposits for their valuble carbonaceous content, largely because of the great expense involved in mining them. While various methods have long been proposed for distilling the carbonaceous constituents of oil shale and other carbonaceous materials in situ, none have so far proven successful from a commercial standpoint.
Thus, as far back as the year 1918 (see Roger US. Patent No. 1,269,747) it was proposed to either introduce highly heated fluids, such as air, steam, or products of combustion, directly into passages provided in naturally occurring deposits of oil shale to be worked, or to introduce electrical heating elements in such passages, for the purpose of destructively distilling the carbonaceous content of such oil shale in situ. Subsequent proposals (see Day US. No. 1,342,741; Hoover et al. US. No. 1,422,204; Cooper U.S. No. 1,494,735; Clark US. No. 1,510,655; Crawshaw U.S. No. 1,666,488; and Karrick U.S. Nos. 1,913,395 and 1,919,636) have suggested variations and refinements on both of these proposed methods of heating and distilling solid materials in situ. Crawshaw US. No. 1,666,488, for example, explains a particular method utilizing a heater unit electrically heated to around 500 degrees Fahrenheit and introduced into a deposit of oil shale for raising the latter to distillation temperatures.
Despite proposals such as those noted above, the presently accepted approach to exploitation of oil shale deposits is the application of low-cost mining techniques and the distillation of the cheaply mined shale in retorts of one kind or another at the surface. I attribute this to the difficulty of maintaining proper working temperatures in and of supplying adequate quantities of heat to the material in situ.
The principal purpose of my invention is to provide a new and improved method of and plant for distilling deposits of oil shale and other solid carbonaceous materials in situ, whereby more effective and complete distillation is accomplished and significant Working economies are achieved.
My method as applied to the distillation of deposits of oil shale in situ is predicted upon the concept of establishing at least one localized thermal center of exceptional heat producing capacity, and of continuously supplying sufficient heat therefrom for advancing a thermal front through adjacent areas of the deposit at temperatures suitable for effecting distillation, i.e. decomposition, of the organic content of the material, but incapable of fusing the rock.
This is achieved, as a practical matter, by the utilization of a nuclear reactor adjacent the area concerned, to furnish a continuing and exceptionally great quantity of heat to a heat exchange medium, which is preferably circulated through one or more heat-exchangers strategically located with respect to the particular area of the deposit to be Workedv By maintaining sufficient heat-producing capacity at the thermal center and by thereby continuously imparting great quantities of heat to the thermal front or fronts, the nuclear reactor enables in situ distillation to be effectively carried out. Such diffusion of heat may be aided, if deemed necessary or desirable in particular instances, by a preliminary shattering of the material in the area concerned, as by the use of explosives, or may be aided by the driving of lateral passages through the formation being worked. In some instances, it may even be desirable to apply suction about the periphery of the area.
Products are collected at alocation or locations remote from the introduced thermal source, usually by the provision of an outflow passage or passages leading to appropriate handling equipment at the surface.
A subsidiary feature of my method is the condensing of the distillation vapors, recovery of the resulting liquid products, burning of the gaseous components to useful purpose, and introducing of the resulting hot inert gases into the advancing heat from underground for the purpose of tempering the latter.
An optional feature is the driving of an access shaft or drift from the surface to the underground area concerned, permitting entry of operating personnel to such area, and the making of an underground room or chamber laterally adjacent the bottom of the shaft or the inner end of the drift but normally sealed therefrom, with access for operating personnel therebetween and with oil shale to be treated forming one or more of the walls of such room or chamber, whereby a shale-decomposing heat front can be maintained in such room or chamber, deriving its heat from either a nuclear reactor at the surface or at the bottom of the shaft or inner end of the drift.
Further objects and features of the invention will become apparent from the following detailed description of the preferred specific embodiment thereof illustrated in the accompanying drawing-s.
In the drawings:
FIG. 1 is a diagrammatic representation of a plant for carrying out the method of the invention, underground portions being illustrated in vertical section;
FIG. 2 is a top plan view showing a typical arrangement of drill holes utilized, this view being drawn to a reduced scale;
FIG. 3 is a view corresponding to a portion of FIG. 1, but illustrating application of the method to a deeply underground deposit of the material to beworked;
FIG. 4 is a view similar to that of FIG. 3, but drawn to a larger scale and showing only the underground portions of a different plant open to access by operating personnel, the nuclear reactor being shown as located underground; and
FIG. 5 is a horizontal section taken on the line 5-5 of FIG. 4.
Referring to the drawings:
The underground portion of the plant of the invention may be similar in many respects to what has been proposed heretofore for the distillation of oil shale and other solid bituminous materialsin situ. Thus, one or more holes 10 are drilled orbored in the deposit 11 concerned, usually from the surface of the earth above such deposit, by customary dnilling techniques and 'by the use of conventional drilling equipment. Also, one or more similar holes 1 2 are drilled or bored at points remote from the hole or holes 10, to serve as recovery channels for the fluid products of distillation.
The arrangement of such holes 10 and 12 will vary considerably, depending upon the nature of the deposit tobe worked and upon the terrain concerned. An advantageous arrangement for the more regular and accessible deposits is indicated in FIG. 2, where a single hole is concentrically surrounded by a series of recovery holes 12.
My method or process involves the establishment of a heat center of exceptional heat-imparting capacity within the one or more holes 10, and the rapid advancement of a heat front toward the recovery holes 12 by way of the oil shale to be treated.
One Way of accomplishing this is to install an elongate heat exchanger 13 within each drill hole 10, along with a closure cap 14 which seals the hole against entrance of air and escape of gases. By means of such heat exchanger, a fluid, heat-transfer medium of any suitable type capable of carrying a fluid heated to a temperature not unreasonably in excess of the decomposition temperature of kerogen (about 800 F.), is continuously circulated into and along the working length of the hole.
In the instance illustrated in FIG. 1, the deposit 11 is indicated as extending downwardly from a surface outcropping, and the heat exchanger 13 as extending throughout the entire length of the hole 10. The cap 14 is of any suitable and well-known construction adapted to accomplish its functions.
It should be realized, of course, that, in instances where the deposit of oil shale to be worked is covered by an over-burden 15, FIG. 3, of earth materials worthless so far as this process is concerned, the heat exchanger 13 will extend only throughout that portion of the total length of the drill or bore hole 10 which comprehends the deposit 16 to be worked, and the pipes 17 carrying the heatexchanger medium to and from the heat exchanger will be appropriately insulated, as at 18, against loss of heat to the worthless overburden 15. Furthermore, the drill or bore hole 10 will be preferably capped or plugged in the vicinity of the upper limits of the deposit, as at 19, rather than at its surface opening.
The heat exchanger -13 is here illustrated diagrammatically as made up of a coil of piping.
The heat generated is imparted to a primary heat-transfer medium of suitable nature, for example, a molten metal such as liquid sodium, which is circulated through an exchange circuit built into the reactor in customary manner, as indicated. An intermediate heat exchanger, as indicated at 20, within the flow circuits of the reactor exchange circuit and heat exchanger 13, imparts heat from the primary heat-transfer medium to a secondary heattransfer medium, which is circulated through heat exchanger 13 by a pump 21. Such secondary heat-transfer medium may be a liquid or a gas or a combination of both, for example, water, air, or superheated steam, it being realized that heat exchanger 13 must, in such instances, be sufliciently sturdy in construction to withstand the pressures accompanying heating of the fluid medium to the high temperatures involved.
While it is desirable and a feature of the present invention to utilize the highest possible temperatures for establishing the heat front or fronts required by my method, it should be realized that sufficient heat to fuse the inorganic components of the material being treated should not be permitted to accumulate in the immediate vicinity of the hole or holes 10. Furthermore, it is desirable to raise the temperature of the material to be treated only to a minimum extent beyond that required for distillation of the organic components thereof.
Accordingly, to insure that the temperature does not become excessive, a thermostat 22, having its control element 23 strategically positioned at the defining wall of the hole 10, is operatively arranged to start and stop the pump 21.
Normally, diffusion of heat through the fi-ssured materill ing tr d will be so r pid as to effectively maintain temperatures in the immediate vicinity of a heat introduction hole 10 well below the fusion point of the inorganic components of the material being treated. Thus, the thermostatic operating control for pump 21 may be regarded as a safety measure. It will be realized that the rapid distillation of organic components of the material in the immediate vicinity of a heat introduction hole 10 will create considerable vapor pressure, effective both outwardly into the shrinking and fissuring areas more remote from the hole 19 and backwardly into the hole 10. Such vapor pressure tends to enhance the shrinking and fissuring action and serves as a very effective medium for advancing the heat front.
The closure cap 14 serves both to seal the hole 10 against entry of air from the atmosphere outside and to retain the evolved vapor pressure within the hole. Control of the advancing heat front and, to a certain extent, of tem? peratures throughout the area being worked, may he exer cised by manipulation of a pressure-release valve 24 desrr' ably provided in the closure cap 14. A pressure gauge 25 and temperature indicator 26, preferably associated with the cap 14, show when and to What extent such control is necessary.
The great quantity of heat supplied continuously at a drill or bore hole 10 insures not only rapid distillation of organic components of the material immediately adjacent such hole, progressive shrinking and fissuring of more remote areas at a rapid rate, and rapid dissemination of heat by reason of high vapor pressure, but also insures rapid heating of the more remote areas to an extent which 1mg ly prevents or limits condensation of the advancing vapors, thereby insuring a steady outflow of distillation products in vapor form through the one or more recovery holes 12. While the placement of the recovery hole or holes 12 relative to the heat introduction hole or holes 10 will depend upon the nature of the material being Worked and of the contours of the deposit thereof, in most instances it will be found desirable to utilize a plurality of recovery holes 12, see FIG. 2, in mutually spaced, approximately circular formation on approximately a 12-foot radius about a heat introduction hole 10 as a center. The thickness of such a treatment zone need be limited only by what is found structurally practical for any particular installation.
The recovery hole or holes 12 are capped, see 27, in a manner similar to the capping 14 of holes 10, so as to maintain the entire underground system under operational control with respect to vapor pressure. Each recovery hole 12 is provided with a conduit 28 leading to a condenser, as indicated, for the recovered distillation vapors. Such condenser may be of any suitable and well-known construction for the purpose,
A highly efiicient system for any given operation is provided by a plant which includes a gas receiver and a steam glectric generating plant utilizing gas from the receiver as uel.
In FIG. 1, both the gas receiver and steam electric generating plant are indicated as such, gaseous products from the condenser being pumped to the gas receiver and being passed to the generating plant as required. Inert gases from both the condenser and the generating plant are advantageously passed to an insulated gas receiver for conserving their heat energy, and from there are passed to the one or more closed circuits between heat exchanger 13 and the primary heat exchanger, as indicated, under control exercised by, for example, a manually controlled valve 29. Thus, the inert gases may be employed as found necessary or desirable to temper the heat source or sources within the hole or holes 10.
Oils and other liquid condensates from the condenser tailed here.
the invention may be employed.
It should be realized'that the concept of applying heat from a nuclear reactor to an underground area containing materials to be treated in situ represents a highly significant part of the present invention. Heretofore, attempts to effectively work natural deposits in situ by the introduction of heat thereinto have been unsuccessful. I am able, however, by employing a nuclear reactor as the source of applied heat, to provide sufficiently great quantities of heat on a continuing basis to maintain working temperatures throughout an underground area of commercially feasible dimensions for whatever time period is required to effect the results desired.
Not only is it possible to supply the quantities of heat required on a continuing basis, but the supply of heat is subject to almost instantaneous variation over an extremely wide range, for the purpose of accommodating the system to variations in heat requirements substantially as and when demanded for effective temperature control throughout the underground area being worked. Also, the supply of heat may be easily maintained on a uniform and constant basis when required,
The manner of exercising control over the energy output of a nuclear reactor is well-known, and need not be de- 7 Any type of nuclear reactor capable of furnishing the energy requirements for a given installation of Its particular construction isfnot important so far as the functional effectiveness of the method is concerned, though itmay be anticipated that considerable economies will be effected in the commercial application of the invention as .nuclear reactor design is simplified and construction and operating costs reduced.
The plant shown in'FIGS. 4 and 5 for carrying out the method of the invention is unique, in that it locates the nuclear reactor in an underground space 30 at'the bottom of a shaft or man-way 31 affording access for'operating personnel. Surrounding or at least contiguous to space 30, and thermally sealed therefrom by an insulating wall 32, is a thermal room 33, into which a heat exchanger 34, corresponding infunction to the heat exchanger 13 of FIGS. 1 and 3, extends from its heat-receiving association with the coolant heat exchanger of the reactor in a manner similar to that indicated in FIG. 1.
This thermal room 33 establishes the requisite high capacity heat front for imparting, by radiation or convection, the great quantity of nuclear-energy-generated heat to exposed face 35 of the oil shale fronting on such thermal room.
One or more thermostats 36, regulating the electrical controls 37 for heat-exchange-fluid pump 38, are positioned on the shale face 35 in a manner similar to the corresponding equipment in FIG. 1.
It is a feature of this embodiment of the invention that access is provided for operating personnel right up to the working face of the shale to inspect progress and exercise manual control where justified. Thus, access doors 39 lead through the insulating wall 32 and into thermal room 33, providing passage directly to the heat front for personnel properly equipped with heat-resistant clothing and built-in oxygen supply.
Holes (not shown) may be drilled directly into the body of shale from room 33 or fracturing techniques utilized in order to hasten distillation progress if deemed advisable.
Product vapors and gases are recovered through one or more recovery wells 40, FIG. 4, extending to the surface, with flow controlled by valves which are indicated as such on the drawing. In some instances it may be desirable to save the expense of drilling wells 40 and run one or more insulated and valved recovery conduits, as indicated in broken lines at 40-1, through wall 32 and up to the surface by way of man-way 31. Any liquid products collect in a sump and are pumped to the surface by means of any suitable equipment (not shown).
The thermostats 36, or other suitable heat measuring between opposing edges of the sheets, as indicated.
and control instruments, are set at the temperature desired for kerogen decomposition and act to start and stop pump 38 as the recorded temperatures indicate heat requirements. Because the thermal room 33 affords direct access for operating personnel and workmen to the shale face, it is possible to reset the thermostats to higher temperature levels when and as required by the progress of the operation, for example, when the decomposition progresses outwardly so far that higher temperatures are required to make up for heat dissipated in worked out areas lying between the heat source and any given kerogendecomposing area.
As an aid in determining how far to advance the control temperature in resetting the thermostats, one or more exploratory bore holes 41 are advantageously core drilled from the shale face 35 as the operation progresses, the resulting cores being inspected to determine the rate and extent of progress being made in kerogen decomposition.
If desired, the thermostats may be relocated at the ends of such bore holes, with temperature settings unchanged, and the cores 42 replaced after being wrapped with respective sheets of heat-insulating material 43 to hold them together, if necessary, and to provide a reasonably snug fit, the leads from the thermostats being accommodated In this way, control progresses in accordance with the progress of kerogen decomposition, and is subject to prompt and effective manual adjustment as may be required from time to time.
Although the invention is particularly concerned with the treatment of oil shales, it may be similarly applied to bituminous sands, such as those of the Athabasca region of Canada and the like, by utilization of appropriate temperature ranges, e.g. from 200 to 800 F.
In the treatment of oil shales particularly, there will come a time when the mass of spent rock materials resulting from decomposition and release of the kerogen extends back from the exposed face a distance such that the heat front can no longer be maintained efficiently for the production of decomposition products. Under these circumstances, it will be advantageous to excavate part or all of such spent shale and remove it from thermal room 33 by way of doors 39 and man-way 31, utilizing appropriate hoisting equipment (not shown), and to relocate heat exchanger 35 closer to the new exposed face to be treated. The distance to which thermal room is thereby extended outwardly is limited only by practical and economic considerations with respect to material removal and ceiling support.
Reverting to the nature of the control exercised by the thermostats in the illustrated embodiments, it should be noted that not only is the pump which controls circulation through the heat exchanger 13 or 34 controlled, but so is the pump which controls circulation of the reactor coolant through the intermediate heat exchanger, and also the operation of the nuclear reactor itself.
Thus, as shown in FIG. 5, the thermostat 36 operates the electrical control 44 for pump 45 and also any suitable servomechanism 46 for adjusting the carbon rods or other regulating means employed by the particular reactor utilized. Obviously, the same or similar arrangement could be employed with the embodiment of FIG. 1.
Whereas this invention is here illustrated and described with respect to specific embodiments thereof, it should be realized that changes may be made within the scope of the following claims, Without departing from the essential contributions which I have made to the art.
1. A plant for the in-situ distillation of the bituminous content of bitumen-impregnated earth materials, comprising underground workings including a man-way extending from the surface to a selected underground area within the said earth materials, and a laterally expanded working space surrounding the inner terminus of said man-way; a heat-insulating wall enclosing at least said inner terminus and separating it from the expanded space to define a thermal room insulated from said man-way and having walls of said earth materials exposed inwardly of said room; heat-retarding passage means through said insulating wall for operating personnel; a nuclear reactor having a fluid-circulating coolant system for generating heat at a temperature at least suflicient to decompose the bituminous material making up said bituminous content and in quantity required to progressively distill the bituminous content from said earth materials which are exposed and adjacent to said room; means for introducing heat into said room from said heat generating means; and means for controlling the introduction of heat into said room.
2. The plant of claim 1, wherein the means for introducing heat into the room is a heat exchanger through which a fluid heat exchange medium is circulated; and wherein the means for controlling introduction of heat into the room comprises an intermediate heat exchanger through which the reactor coolant circulates, means for circulating said heat-exchange medium, means for circulating said reactor coolant, means for regulating the reactor, and thermostatically controlled means for regulating operation of all of said means.
3. A plant for the in-situ distillation of the bituminous content of bitumen-impregnated earth materials, comprising underground workings including passage means extending from the surface to a selected underground area within the said earth materials and exposing a face of said materials; a nuclear reactor for generating an unusually abundant supply of heat at a temperature at least suificient to decompose the bituminous material making up said bituminous content, said reactor having a fluidcirculating coolant system; a heat exchanger through which a fluid heat exchange medium is circulated, said heat exchanger being disposed in said passage means adjacent said face; an intermediate heat exchanger, through which the reactor coolant circulates, disposed in heat exchange relationship with the first-named heat exchanger; means for circulating said heat-exchange medium; means for circulating said coolant; means for regulating the reactor; thermostatic means at the said face; and means under the control of said thermostatic means for controlling the respective circulating means and the reactor regulating means.
4. An in-situ process of distilling the kerogen content of oil shale, comprising generating by means of a nuclear reactor an unusually abundant supply of heat at temperature at least sufficient to decompose said kerogen; passing a heat exchange medium in heat exchange relationship with said nuclear reactor; drawing on said heat exchange medium continuously as required for sufficient heat to effectively decompose said kerogen within a selected underground area of said shale; continuously introducing said heat exchange medium by way of a heat-input channel to apply heat to the heat-input face portion of the shale at said channel to progressively disseminate the heat through said selected area until the kerogen content thereof is decomposed; recovering by way of heat-recovery channels decomposition products as they collect following formation thereof; and controlling the heat input from said reactor to said input channel by means of a thermostat placed on said heat-input face portion of said shale.
References Cited by the Examiner UNITED STATES PATENTS 1,269,747 6/ 1918 Rogers 2992 2,593,477 4/ 1952 Newman et al. 2,732,195 1/1956 Ljungstrom 16611 2,789,805 4/ 1957 Ljungstrom 16639 2,951,943 9/1960 Goodman. 2,951,946 9/1960 Frey et al. 2,989,453 6/ 1961 Esselman et al 17620 3,079,995 3/1963 Natland 166-11 3,085,957 4/1963 Natland 1661 FOREIGN PATENTS 217,265 9/ 1958 Australia. 1,147,517 6/1957 France.
823,777 11/1959 Great Britain.
252,909 10/ 1948 Switzerland.
REUBEN EPSTEIN, Primary Examiner.
CARL D. QUARFORTH, Examiner.