US3106521A - Method for the production of light oils from oil shale through the recombination of hydrogen originally contained therein - Google Patents

Description

O 1963 M. G. HUNTINGTON 3,

METHOD FOR THE PRODUCTION OF LIGHT OILS FROM OIL SHALE THROUGH THE RECOMBINATION OF HYDROGEN ORIGINALLY CONTAINED THEREIN Filed July 25, 1960 31 T0 PESERl/O/l? l0] 89 f/AT EXCHANGE/P 56 9 I18 15 k W Q u D I if 5% Lu 3;} M N n b 6&2 E 3 E Q 114 150 w Q E E Q Q k Q L E 112 FRACTION/170i? H/GH zk izi 10mm B M5 F NO/VCUMBUSTABLE 3 GAS RESE'RVO/R 7'0 CHARGING (Of/f 78 A INVENTOR, Morgan 6-H ATTORNEYS United States Patent O Utah Filed July 25, 196i}, Ser. No. 45,038 14 Claims. (Cl. 208-1l) This invention relates to the destructive distillation of oil shale within an internally heated, pressurized, continuously fed, u-nrabbled vertical retort in which are combined the functions of drying, preheating, destructive distillation and coincidental, autogenous hydrofining of the organic volatile matter in the oil shale.

There are a number of known processes for the distillation of oil shale and the efforts to secure uniform heating with a good yield of oil have been numerous and the systems various. Although oil shales in America are available in tremendous quantities, and as compared to the known petroleum reserves are vastly greater in total energy content, no shale oil distillation process known has thus far proven sufliciently effective as to implement the commercial exploitation of these huge potential liquid fuel reserves.

Shale oil distilled by all known and previously demonstrated oil shale retort-ing systems is generally comparable to :a low temperature coal tar and presents about the same considerable refining difiiculties as do coal tars. That is,

neither shale oils nor low temperature coal tars are amenable to successful treatment in existing petroleum refineries with presently employed equipment.

One of the most common deficiencies in the processes now known, practiced, or demonstrated is the inadvertent over-heating of the primary volatile matter whereupon the total possible yield of condensable liquid, as indicated by the modified Fischer Assay, is reduced by 15 or 20% largely due to the thermal decomposition of the hydrocarbon molecules. One of the objects of this invention is to absolutely prevent the over-heating of the primary volatile matter and the resultant inadvertent destruction of the hydrocarbon molecules. Moreover, in the prior known systems, because of the inadvertent thermal destruction of the volatile matter the hydrogen content of the condensable oils is always somewhat less than that indicated by the Fischer Assay. It is another object of this invention to perform the pyrolysis and destructive distillation of oil shale in an atmosphere of hydrogen at substantial pressure in order to increase the yield of oils and reduce the amount of carbonaceous residue wasted with the shale and at the same time, reduce the tendency to form permanent gases during the destructive distillation process.

In the prior art oil shale retorting systems there is no provision coincidental with the system for the removal of oxygen, sulphur and nitrogen which are chemically cornbined with hydrocarbon molecules. Therefore, the crude shale oil resulting from all of these prior shale distillation processes contains highly reactive chemical functional groups which render almost insoluble the direct refining of such oil into saleable products competitive with those from petroleum. It is an object of this invention to provide a method whereby the primary volatile matter derived from the oil shale may be coincidentally hydrogenated and desulphurized during destructive distillation and immediately thereafter during the passage of the entire stream through suitable beds of catalysts.

The crude shale oil thus far produced in known retorting processes is of such consistency that it is impossible to pump it through unheated pipelines to refineries because 3,1 5,5 2 I Patented Oct. 8, 1963 this crude oil congeals at temperatures below to F. By the use of the process of this invention the products of oil shale distillation may be handled without special equipment such as heated pipelines and the product oils do not congeal at normal atmospheric temperatures.

All of the known oil shale retorting systems thus far developed and/or proposed are essentially thermal-cracking processes which preserve and accentuate all the very Worst qualities so far as crude oil refining problems are concerned. By cracking :off and rendering unusable approximately one-third of the hydrogen initially present in the kerogen, a high percentage of unsaturated hydrocarbon compounds is produced. This invention provides for the conservation of the hydrogen and hydrocarbon gases which are cracked from the kerogen during and following its pyrolysis.

Also, in the known internally heated oil shale retorting systems, such as those demonstrated by the U.S. Bureau of Mines and the Union Oil Company near Rifle, Colorado, the destructive distillation must necessarily take place under oxidizing conditions and at uncertain temperature levels. Therefore, there are inevitably produced within the usual crude shale oil the highly complicating cherne ical factors introduced by the presence of ox genated compounds in addition to the problems already posed by the rather high sulphur and nitrogen contents. The chemical functional and highly reactive groups containing oxygen, sulphur and nitrogen attach themselves to the primary hydrocarbon molecules and thereby cause the hydrocarbon molecules themselves to react with each other and so immensely complicate the refining problem. The system of this invention provides for the prompt elimination of most of the oxygen, sulphur and nitrogen which causes much of the aforesaid refining difficulties.

In the known oil shale retonting systems, the primary volatile matter is inevitably diluted by products of combustion when the shale oil retort is internally fired and the primary volatile matter is usually further diluted by carbon dioxide evolved from the calcining of the carbonate shale residue, thus rendering the recovery of hydrogen a very di'liicult and expensive procedure. By the use of the process taught in this invention, the primary volatile matter is undiluted by the products of combustion and/ or by carbon dioxide resulting from the unnecessary calcining of the carbonaceous shale residue.

To be commercially successful, an oil shale retorting system must be capable of a relatively large materials throughput capacity per unit horizontal cross-sectional area. The limited capacity of prior apparatus in the destructive distillation of oil shale has contributed substantially to the impracticability of exploiting the oil shale reserves in America because of the resulting high investment and operating costs. The oil shale retorting system of this invention provides for markedly increased materials throughput per unit of cross-sectional area of a retort as a function of improved heat transfer between the thermal carrier fluid and the solid material. Also, in the process of this invention, the oil shale is heated through its distillation temperature at a rapid rate thereby minimizing the time of residence of oil shale within the retort at calcining temperature. This reduces the thermal-cracking of oils into fixed gases and into lower ranked oils, which degradation proceeds rapidly as a function of the time of residence in the range of the destructive distillation temperatures. 7

It is extremely desirable that an oil shale retortingsystern be constructed so as to enable it to handle all sizes of raw crushed oil shale Without the necessity of screening out small particles and therefore wasting the natural resource plus the expense of mining and preparing the wasted fraction. All other internally heated retorting processes waste one ton in five or six as rejected, unusable fines. This invention provides an oil shale retorting system capable of handling extremely fine oil shale particles along with the somewhat coarser fraction so that it is not necessary to screen out and waste any portion of the fine, raw oil shale.

To provide for the internal heating of an oil shale retort without mixing any products of combustion with the primary volatile matter evolved from the shale is, as mentioned previously, highly desirable. In the system of this invention the retort is internally heated, and not internally fired. The heat provided for the destructive distillation is from sources other than the burning of the combustible products of oil shale distillation and one such other source demonstrated herein is from an auxiliary coal distillation system.

By following the teachings of this invention, a number of major deficiencies and shortcomings of the prior art will be overcome and the desirable features of oil shale enumerated above are incorporated. The result is that this oil shale retorting system produces oils which, in physical and chemical properties and in all other respects, are competitive with the best grades of petroleum products. Moreover, when economically desirable, the entire product of this oil shale exploitation system may be high octane gasoline.

Other objects and advantages of this invention will be pointed out in the following description and claims and illustrated in the accompanying drawing which discloses, by way of example, the principles of this invention and the best mode which has been contemplated of applying these principles.

In the drawing:

The single FIGURE represents a semi-schematic diagram of the oil shale retorting method of this invention.

In general, this invention is particularly concerned with the conservation and maximum recombination and re-use of the hydrogen which is initially contained in the hydrocarbonaceous constituent of oil shale and further concerns itself with hydrofining and hydrocracking of the condensable volatile matter in order to achieve maximum production of the more useful light oils while not requiring an outside source of hydrogen. Raw crushed shale of various sizes may be fed vertically downward through an internally heated retort in measured amounts over gyrating shelf feeders. The raw shale of various sizes is concurrently contacted and heated by a stream of hot hydrogen and the primary volatile matter is distilled therefrom. This primary volatile matter is taken off from a duct in the vertical retort and the solid particles of shale continue to be fed downwardly. A moderate amount of unheated hydrogen is introduced to fiow countercurrently through the spent, broken shale to effect the final stripping of volatile matter and to achieve at least partial heat recovery. Safety gas locks continuously purged with noncombustible gas are provided at both ends of the hydrogen contacting area of the retort to insure against ignition of the thermal carrier hydrogen. Heat recovery and preheating sections are provided outside of the safety gas locks at the bottom and top of the retort respectively.

The primary volatile matter otftake is connected to a multiple bed catalyzer and then to a fractionator and the entire stream passes through both vessels at system pressure. From the fractionator the heavy bottoms are recycled for contact coking in a portion of an auxiliary apparatus such as a coal still, the middle oils are passed through a high pressure hydrocracker and the overhead stream is passed to a condenser. After being scrubbed, uncondensable gases from the condenser are thermally cracked and reheated in an auxiliary apparatus and then are recycled to the oil shale retort. All of the heat supplied for heating the oil shale retort is supplied from an auxiliary source.

This auxiliary source for supplying all the heat may be a coal still in combination with the oil refining processes previously described. This coal still not only furnishes all of the heat but also may be the auxiliary apparatus which provides the means (hot char) for cracking hydrocarbon gases into hydrogen at substantial pressures and in substantial quantities and thus furnishes the thermal carrier gas to accomplish the destructive distillation of the oil shale.

The heavy oil bottoms from the fractionator are also recycled into the coal still where coking and redistillation are performed in contact with incandescent char as is described in my hereinafter mentioned application Serial No. 41,679. The flue gas produced from the coal still may be utilized as the noncombustible gas for the safety gas locks of the oil shale retort, and for heat recovery and preheating.

Thus, it can be seen that this process produces high quality petroleum products without requiring a source of hydrogen and without requiring internal firing of the oil shale retort, Furthermore, by utilizing a system in which the thermal carrier fluid is essentially hydrogen and wherein the partial pressure of hydrogen has a tendency to increase the yield of condensable liquids and to decrease the splitting off of permanent gases during the pyrolysis and distillation of the kerogen, also, the apparent yield of intermediate semirefined shale oil is substantially greater than of that indicated by the modified Fischer Assay.

Referring to the drawing for a general description of the process, a vertical oil shale retort is indicated generally at 10. A coal distillation system is indicated gen erally at 12. The coal distillation retort may be of the general type disclosed and claimed in my co-pending application entitled Method for the Continuous Distillation of Coal and Other Hydrocarbonaceous Materials and for the Autogenous Hyrogenation of the Condensable Volatiles, Serial No. 41,679, filed July 8, 1960, and the coal still per se forms no part of this invention. Within both the oil shale retort 1t and the coal still 12 are a number of gyratory shelf feeder units and each of these feeder units has been illustrated only schematically as they are described in detail in my co-pending application entitled Method and Apparatus for the Continuous and Uniform Contacting of Fluids and Solids," Serial No. 17,293, filed March 24, 1960, now Patent 3,083,471.

The vertical oil shale retort 10 may be fed with raw crushed shale from a skip 11 into a measuring hopper 14 closed by a bell valve 16. Below the measuring hopper 14 is a charging lock 18 also closed at the bottom by a bell valve '20 making a substantially pressure-tight charging lock. The charging lock has an inert gas entrance duct 22 and an inert gas outlet duct 24 controlled respectively by valves 26 and 28. By this means inert gas may be charged into the charging lock to apply system pressure to the oil shale and to preheat the oil shale somewhat. Charging lock bell valve 20 may be opened to dump the contents of the charging lock onto a system gyratory feeder shelf unit 25, which in turn feeds the shale over its periphery in a controlled manner to several identical gyratory feeder shelf units such as units 23 and 27 constituting a preheating zone. Heat recovery gases at about 800 F. are admitted to the preheating zone through duct 29 and flow countercurrently therethrough to exit at duct 31. Efficient heat transfer will take place between these gases and oil shale particles to preheat the oil shale to about 600 F.

The preheated shale is then fed downwardly onto feeder shelf unit 30 which is indicated as having materials thereon SB denoting that it is a separating bed. The materials on the gyrating shelf 30 are kept, by suitable controls, at such a depth that they function as a separating bed, forming a noncombustible gas barrier between the area above and below shelf 30. The raw crushed shale is meteredoif the periphery of shelf 30 by the mechanism described in my aforesaid co-pending application and thus passes into a safety gas lock area 34 wherein it falls on a gyratory feeder unit shelf unit 36 also maintained as a deep separating bed (SB). With the two deep separating beds above and below gas lock area 34 an effective safety noncombustible gas lock is maintained. Noncombustible gas may be admitted to the gas lock area 34 through valve controlled duct 38 for start up and other purposes.

Fresh, crushed shale is continuously metered off the periphery of feeder shelf unit 36 onto feeder shelf unit 40 and in turn is continuously fed off shelf unit 40 to feeder shelf unit 42 then to feeder shelf unit 44 and on down to feeder shelf unit 4 15. It should be emphasized that the number of feeder shelf units are diagrammatic only and that they could be increased or decreased according to specific requirements. The area encompassed by the volatile matter of the oil shale is distilled by contact with a thermal carrier fluid consisting essentially of hydrogen at about 2000 F. or more, for example, up to and above 2500" F., and at system pressure of about 15 to 30 or more atmospheres. The hydrogen is admitted to the distillation zone through duct 48 and is partially supplied from cracking methane over very hot solid particles as will be discussed hereinafter.

The very hot hydrogen and the fresh, crushed oil shale arefed concurrently downward through the distillation zone and over-heating of even the finer particles of shale is unlikely. Furthermore, at the same time, the very large temperature differential between the cold shale and the hot hydrogen favors very rapid heat exchange. A further advantage of this concurrent movement of the thermal carrier hydrogen gas and the cold shale is obtained because the thermal carrier gas is continually dropping in temperature as it flows downward through the system and at the same time the shale particles are rising in temperature and there never exists suflicient thermal head in th thermal carrier gas to over-heat and destroy the primary volatile matter of the shale. The flow rate of thermal carrier gas is so adjusted that the volatile matter leaves the retort at a temperature above its initial condensation point. Concurrent flow of thermal carrier fluid and shale insures that it is entirely unlikely that any of the carbonates will reach the temperature of calcination in this distillation zone, even though the initial temperature of the hydrogen gas is very much above the temperature of calcining for the reasons set out above.

As the crushed oil shale is metered over the peripheries of feeder shelf units 40, 42, 44 and 45 and the thermal carrier hydrogen gas passes concurrently through the crushed shale supported on the feeder unit beds, the temperature of the shale rapidly comes up to its pyrolyzing temperature and by the time the shale reaches the bed of feeder unit 45, practically all the volatile matter has been expelled from the shale. This primary volatile matter from the shale flows 0a with the thermal carrier fluid through outtake duct 50 at a temperature sufiicient to prevent is recondensation.

In order to strip the devolatilized heated shale of any remnants of volatile matter, some additional unheated hydrogen is introduced through duct 52 to flow upwardly through a stripping and heat transfer zone. This stripping and heat transfer zone consists of gyratory feeder shelf units 54, 56' and 58 which continually feed the crushed shale downwardly for its counter-current contact with the hydrogen introduced through duct 52. ln addition to stripping the last of the primary volatile matter from the oil shale, some of the sensible heat remaining in the shale calcine is transferred to. this stripping hydrogen which also flows through the main offtake duct 50 to a primary catalyst chamber. Also, all of the primary volatile matter contained within the thermal carrier hydrogen gas is removed from the system through the offtake duct 50.

The spent calcine is then fed onto a gyratory feeder shelf unit dd which contains a separating bed and is again fed oif said separating bed into another safety gas lock area 62, the bottom of which is defined by a separating bed SB on another gyratory shelf feeder unit 64. Inert gas is admitted to the gas lock area 62 through a valve controlled conduit 66. Below the gymtory feeder unit 63 there is a heat recovery zone includ- :ing one or more gyratory shelves 61, 63 below which the spent cool shale enters. Below this heat recovery zone is an exhaust lock 7% closed above and below by bell valves 7-2. and 74 and having ducts 76 and 73 controlled by valves 80 and 82 formaintaining the look at system pressure and for releasing system pressure prior to discharging the spent calcine through hopper as to suitable removal means, not shown.

Recycled, cold, non-combustible gas, which can be the flue gas from a companion coal still as described in my aforesaid copending application, enters the heat recovery zone through ductbll and passes countercurrently through one or more beds of the descending spent shale such as the beds carried on gyrating shelves 63 and 61 and thus removes the sensible heat from this spent shale. The heat recovery gas, now heated to about 800 F, leaves the heat recovery zone at exit 83 and bypasses the safety gas locks, the stripping zone, and the distillation zone, through bypass flue 85' to enter the preheating zone at entrance duct 29. The hot heat recovery gas then passes countercurrently through the raw crushed shale carried on the gyratory feeder shelf beds 27 and 23 in the preheating zone and thus transfers the sensible heat from the heat recovery gas to the raw crushed shale and raises the temperature of the shale as it is fed out of the preheating zone to about 600 F.

Leaving the preheating zone through exit duct 37, the heat recovery gas is at a temperature of about 200 F. Although at a temperature considerably below the saturation temperature of steam at the system pressure, the

circulating gas nevertheless will dry Rocky Mountain oil shale completely. For example: in order to raise the temperature of one pound of shale 600 F, about 200 B.t.u. must be supplied. As the heat recovery gas enters the preheating zone at about 800 F. and has a sensible heat content of about 1 B.t.u. per degree F. for each 44 standard cubic feet, approximately 30,000 standard cubic feet must be circulated per ton of raw shale if the heat recovery gas is to leave the preheating zone above 200 F. Thus, one quarter grain of water vapor per cubic foot absorbed by the heat recovery gas will remove one pound of Water per ton of shale. Likewise, 10 grains of water vapor per cubic foot will dry completely shale containing 2% of superficial moisture.

The heat recovery gas at about 200 F. passes through exit duct 87 from the preheating zone into a water and dust removal apparatus '39. Water may be injected into this apparatus from injector 91 in order to lower the temperature therein to 100-l50 F., the amount depending on the amount of water which must be removed from the raw shale and is thus contained in the gas circulated through the water and dust removal unit 89. A slurry consisting of the water and removed dust is taken off outlet drain 93. The water and dust removal apparatus '89 operates at system pressure. The cool heat recovery gas at substantially system pressure with the water thus removed passes through duct @5 at around 100 F. and this gas is saturated with water at this temperature. A small compressor 97 in duct 95 is utilized to make up for any pressure drop through the system. The output of the compressor 97 is through duct 99 into a non-combustible gas reservoir 101. The non-combustible gas reservoir functions as a gas receiver and supplies the heat recovery gasto be recirculated back through the system through duct 8.1. In addition, the flue gas reservoir supplies the gas for the charging and pressurized entrance and exit locks 18 and 70 respectively. The flue gas which is added to the non-combustible gas reservoir is supplied through duct 103 at the outlet of a small compressor 105 which is connected by duct 107 to the outlet from a preheating and drying section A of the coal still 12. An outlet duct 109 from the preheating and drying section A of the coal still can thus pass in three directions, through conduit 1G7 and compressor 165 and duct 193 to the flue gas reservoir 101, through duct 111 to accomplish the charging of the feeder lock in the coal still, and to a letdown stack (not shown) through valve controlled duct 115.

The entrained primary volatile matter from the distillation of oil shale passes through duct 50 into a heat exchanger 86 together with entrained primary volatile matter from the coal still 12 passing out through duct 88. The temperature of the combined oil shale retort and coal still volatile matter streams is suitably lowered by the heat exchanger 86 to enable the volatile matter to be passed at optimum temperature, into a moving bed catalyst reactor 99. This moving bed catalyst vessel may contain a number of the gyratory shelf feeder units such as described in my aforesaid copending application Serial No. 17,293 and is maintained at system pressure which may be anywhere from 15 or or more atmospheres.

The entire process stream leaves the primary reactor 90 through duct 92 and enters into a fractionator 94 also at system pressure. The fractionator with suitable reflux makes an overhead stream which is indicated as passing out through duct 96 and contains the usual naphtha frac tion with all the gases. A residual bottom fraction passes through duct 98 to the contact coking feeder shelf unit 191) of the coal still.

A selected middle oil is pumped through duct 102 to a high pressure hydrocracker 104. The product stream from the high pressure reactor is then passed to the fractionator or a separate similar fractionating system through conduit 106 after flowing through suitable coolers, degassers and depressurizers indicated at 108.

The overhead stream passing out of the fractionator 94 to conduit 96 enters a condenser 110 and produces a liquor passing out through conduit 112, a naphtha which is sent to a reformer (not shown) through conduit 114, and a gas which contains hydrogen sulfide, some hydrogen cyanide, some ammonia, and some carbon dioxide. The gas passes through duct 116 to a gas scrubber 118. The gases may be scrubbed successively in scrubber 118 by dilute ammonia to remove carbon dioxide, hydrogen sulfide and hydrogen cyanide; water to remove ammonia; a wash oil to remove light oil; and an alkali to remove the remaining CO After this or other suitable scrubbing, the gas, consisting mostly of hydrogen and the C C and C hydrocarbon gases is recycled by conduit 120 through hot char in the coal still 12 where the hydrocarbons are cracked into hydrogen and elemental carbon and leave the coal still heated to around 2000 F. and are again reintroduced into the oil shale retort 10 through conduit 48.

The conduit 120 from gas scrubber 118 leads into two or more heat transfer and methane cracking zones E and E through branch conduits 122 and 124 controlled by valves 126 and 128. The upper heat transfer and methane cracking zone E utilizes the hydrogen and entrained elemental carbon produced as a thermal carrier fluid for the primary distillation of coal and this thermal carrier fluid passes through conduit 130 into the coal distillation zone as described in detail in the aforesaid copending application Serial No. 17,293. In addition to the combustion zone D which provides heat for the coal still, there is an additional combustion zone D and the hot char fed off separating bed 134 at the bottom of the second combustion zone D goes into another heat transfer and methane cracking zone E wherein the gases passing through the hot char will also be cracked into methane and elemental carbon to return through conduit 48 at system pressure back into the distillation zone of the oil shale retort 10 to be utilized as the thermal carrier fluid as described above. The carbon black which results from the thermal cracking of the C C C and C hydrocarbon gases is so finely divided that it is almost completely entrained in the thermal carrier hydrogen. Thus, the sensible heat of the entrained elemental carbon plays an important part by contributing to the total volumetric heat content of the thermal carrier gases and this somewhat decreases the theoretical amount of hydrogen required.

Other than having more than one separate combustion zone and more than one separate heat transfer and methane cracking zone, the second combustion zone being indicated at D; and the second heat transfer and methane cracking zone being indicated at E the coal still 12 is substantially identical to that described in my aforesaid copending application and reference may be had thereto for the further details of operation. The various zones of the vertical coal still 12 are set out on the drawing and they include a top drying and preheating zone A, a primary volatile matter distillation zone B, a contact coking zone C within the distillation zone B, a first combustion zone D, a first heat transfer and methane cracking zone E, a second combustion zone D a second heat transfer and methane cracking zone E and a total gasification zone F, in addition to charging and pressurizing locks at the top and bottom of the vertical vessel. The various passages shown on the coal still are for the purpose of bypassing the thermal carrier fluid around the combustion zone, utilizing the products of combustion for supplying the drying and preheating heat to the coal still, as described in my aforesaid copending application.

An example of the operation of the oil shale retorting system will be set out in general terms below. Rocky Mountain oil shales, which are finely laminated sedimentary rocks, the mineral matter of which is 40 to 50% magnesium and calcium carbonate. The organic matter content of these oil shales ranges from about 8 to 40% with an average of about 15% by weight. The hydrocarbonaceous constituent .of these oil shales is called kerogen and is a mixture of amorphous, structureless solid material resembling that of some boghead and cannel coals, and has the following approximate analysis:

Percent Carbon 81 Hydrogen 10.5 Nitrogen 2.3 Sulfur 1.0 Oxygen 5.2

When Rocky Mountain oil shale is destructively distilled under the conditions of the modified Fischer Assay the In general, the carbon to hydrogen weight ratio of the Fischer Assay condensable liquid is about 7.7 to 1 and all retorting processes so far demonstrated further degrade the shale oil so that the carbon to hydrogen ratio is somewhat worse (i.e. higher) than 8 to 1.

It will be noted from the above analysis that the carbon to hydrogen ratio is almost exactly the same in the original kerogen as in the condensable oil from the modified Fischer Assay. Further, after sufficient hydrogen is apportioned to combine with all the shale oil nitrogen as ammonia, all the sulfur as hydrogen sulfide, and all the oxygen as water, there remains in the Fischer Assay gases, sufficient hydrogen to increase the hydrogen content of the condensable oils from about 10.5% hydrogen to about 14% hydrogen if all this hydrogen were to be recombined. Since the reformed gasolines which are possible from this process may be about half aromatics and about half paratlins, the actual hydrogen content of the product gasoline by weight is 11% to 15%. There- 'hydrogen to form ammonia.

fore, by the judicious conservation and reuse of hydrogen originaly contained in the kerogen as disclosed herein, complete hydrofining of the intermediate shale oil may be effected plus the complete hydrogenation and hydrocracking of the heavier oils to form high octane gasoline may be accomplished even though the hydrogen split off by the final reforming operation is not recycled to the oil shale retort.

The shale which has been crushed to pass a screen aperture of approximately A" by 3 inches is fed by a skip 12 into the measuring bin 14 and then through pressurizing lock 18 on to feeder reservoir 32 where it passes through gas lock 34 and into the distillation zone of the oil still retort. It is there heated by concurrent flow heat exchange with the hot thermal carrier hydrogen gases at approximately 2000 F. The amount of hydrogen required as thermal carrier gas will, of course, vary with the particular shale treated, but will approximate 11,000 standard cubic feet per ton of shale retorted, considering all likely heat losses and with recovery of heat from the spent calcine.

As the primary volatile matter is distilled from the oil shale during its passage downwardly through the retort, the thermal carrier fluid with the volatile matter leaves the retort through duct 50. A small amount of unheated hydrogen entering duct 52 strips the remaining volatile matter from the spent shale and transfers some of the heat from the calcine to the stream leaving the retort through duct 50. Non-combustible gas enters the heat recovery zone from the reservoir 101 at about 100 F. and is raised in temperature to about 800 F. After bypassing the other zones this heated gas is passed into the preheating zone to preheat the cold crushed shale to 650 while thereby cooling down to about200 F.

An explanatory heat balance is as follows:

B.t.u./lb. Spent calcine at 150 F. plus heat transfer gas at 200 F 75.0 Thermal carrier gas and volatile matter at 950 F,

11,000 cubic feet per ton shale 111.0

' 185.0 Losses to the surroundings 19 Total heat per pound of shale 204.0

Total heat required per ton of shale distilled B.t.u./ton- 408,000

The primary volatile matter together with the thermal carrier fluid leaves the retort at about 950 F. and will pass through the heat exchanger 36 and be rapidly reduced in temperature to the optimum hydrofining temperature which lies between 750 and 850 F. and then flow in contact with a suitable catalyst such as tungsten suiide or cobalt molybdate in catalyst chamber ht) in atmosphere of hydrogen at system pressure of approximately to 30 atmospheres or more. After allowing suitable catalyst contact time, practically all of the oxygen wil combine with hydrogen to form water and.

sore than 90% of the sulfur will combine hydrogen to form hydrogen sulfide and approximately 50% of the nitrogen present in the volatile matter will combine with Thus, these three elements, oxygen, sulfur and nitrogen can be substantially removed by the usual hydrofining reaction with catalyst contact time of a few seconds at optimum temperatures and pressures. It is worth noting that sulfur removal is favored by low pressures and the hydrogenation of olefins and other unsaturates is independent of pressure and strictly a function of temperature and the catalyst contact time. Therefore, it is obvious that hydrofining may be effectively performed at this system pressure in'the order of 15 to 30 atmospheres provided that the partial pressure of hydrogen is 80 to 90% of the total pressure.

This process is essentially a two stage hydrogenation system in which oxygen, sulfur and nitrogen are substantially removed at retort and multiple bed catalyst pressure of about 15 to 30 atmospheres. After leaving the fractionator 94, which is also at system pressure, I

the middle oils are further hydrocracked at elevated pressures in the order of 1500 to 3000 psi. The heavy bottoms are contact coked and continuously restilled in the coal still which is a separate vessel. The thermal energy and the thermal carrier fluid for the oil shale retorting system is supplied in the preferred embodiment from the coal still 12 although the coal still is not necessarily a limitation to the process and the methane and other gases may be cracked into hydrogen and elemental carbon in other sorts of heat transfer devices and contact coking may take place in other apparatus, however, the coal still fits in with all the requirements of the oil shale retort and furnishes a convenient adjunct for supplying the thermal carrier hydrogen gas at elevated temperature and pressures as well as furnishing the means for cracking the methane and other gases and the means for contact colting of recycled heavy residua.

While there have been shown and described and pointed out the fundamental novel features as applied in the prefered embodiment, it will be understood that various omissions and substitutions and changes in the form and details of the device illustrated and in its operation may be made by those skilled in the art without departing rom the spirit of the invention. It is the intention, therefore, to be limited only as indicated by the scope of the following claims.

What is claimed is:

1. A method for destructive distillation of oil shale including the conservation and mfiimum recombination of hydrogen which is originally contained in a hydrocarbonaceous constituent of oil shale the method comprising; feeding oil shale by gravity downward through an internally heated and pressurized retorting zone, passing a thermal carrier fluid comprising essentially hydrogen at high temperatures and pressures of about fifteen to thirty atmospheres concurrently through the so fed oil shale in heat exchange contact therewith for distilling the volatile matter from the oil shale, passing the thermal carrier fluid and the primary volatile matter distilled from the oil shale at least at the pressure in the retorting zone through a separate catalytic hydrofining operation and separating the same into liquid products, and gas, passing the gas so produced in heat exchange contact with a medium at sufiicient temperature to crack the carbon and hydrogen constituents of the gas into gaseous hydrogen and carbon 4. A method as defined in claim 2 wherein the thermal carrier fluid comprising principally hydrogen is passed concurrently in heatexchange relationship with cold crushed oil shale falling vertically downward in stages within the internally heated retorting zone, and further comprising continuing to feed the oil shale downwardly after most of the primary volatile matter is distilled there- 'from and passing unheated hydrogen at system pressure countercurrently in heat exchange relationship thereto to accomplish a stripping of the remaining volatile matter in the oil shale and a transfer of some of the heat from the hot spent oil shale to the unheated hydrogen.

5. A process for destructive distillation of oil shale with in an internally heated and pressurized retort and for the recovery of hydrogen and other permanent hydrogenous gases undiluted by the products of combustion or carbon dioxide, said process comprising; feeding oil shale continuously through an internally heated pressurized retorting zone, at a pressure between about fifteen to thirty atmospheres passing a hot thermal carrier gas comprising principally hydrogen and containing carbon particles therein in contact with said so fed oil shale and thereby distilling most of the primary volatile matter from the oil shale at a temperature below about 950 F., passing the thermal carrier fluid mixed with the primary volatile matter distilled from the oil shale through a hydrofining process and condensing an overhead stream into liquid products, and a resulting gas, passing the resulting gas containing C C and C gases in heat exchange relationship with a hot heat exchange medium at system pressure for the purpose of disassociating said gases into gaseous hydrogen and carbon particles, and recycling the gaseous hydrogen and carbon particles so produced and at high temperature and system pressure back through the oil shale retorting zone as the thermal carrier fluid so that the hydrogen originally present in the thermal carrier gas is utilized in the hydrofining process and the hydrogen contained in the resulting gases is reused as the thermal carrier gas for the oil shale distillation.

6. A method as defined in claim 5 comprising distilling coal in-an adjunct internally tired, pressurized coal distilling zone, utilizing the heat of the products of combustion of said coal for preheating the coal and for furnishing a safety gas lock for the hydrogen thermal carrier fluid in the oil shale retort and further comprising disassociating carbon and hydrogen gases into carbon particles and gaseous hydrogen by passing such gases over hot char resulting from the partial combustion of coal.

7. A method for the production of light oils from oil shale through the recombination of hydrogen originally contained therein that comprises; feeding raw crushed oil shale vertically downward through an internally heated pressurized restorting zone, at a pressure between about fifteen to thirty atmospheres, passing a thermal carrier fluid comprising principally hydrogen at about 2000 F. concurrently through the oil shale as it is fed vertically downwardly, and thereby distilling most of the primary volatile matter from the oil shale at a temperature below about 950 F., withdrawing the primary volatile matter and thermal carrier fluid, continuously feeding the oil shale vertically downward after most of the volatile matter and thermal carrier gas has been Withdrawn as recited above, and contacting the so fed mostly devolatilized oil shale with unheated hydrogen for stripping the remaining volatile matter therefrom and for transferring some of the heat from the spent but hot oil shale to the unheated hydrogen, passing the withdrawn thermal carrier fluid and the primary volatile matter of the oil shale at an optimum temperature into a catalytic reaction zone at system pressure, passing the stream from the catalytic reaction zone at system pressure to a fractionating zone at system pressure, frac-tionating the stream of thermal carrier fluid and primary volatile matter into heavy bottoms for contact coking, middle oils and an overhead fraction, passing the middle oils to a high pressure hydrocr-acker and passing the entire stream from the high pressure hydrocracker back to the fractionator, passing the overhead naphtha fraction to a condenser and taking out of the condenser liquid products and gases, passing the gases from the condenser to a scrubber to scrub out undesirable components, cracking the scrubbed gas and disassociating the hydrogen from the carbon of the scrubbed gases while at the same time heating the cracked gas to a suflicient temperature and at sufiicient pressure to be utilized as the thermal carrier fluid in in the oil shale retort, and passing said cracked gas comprising essentially hydrogen into said oil shale retort to be utilized as the thermal carrier fluid.

8. A method as defined in claim 7 further comprising safety locking both ends of the thermal carrier gas stream 12 in the pressurized retorting zone by inert gas to prevent hydrogen explosion.

9. A method as defined in claim 8 further comprising; distilling coal in an auxiliary internally fired, pressurized retorting zone, contact coking said heavy bottoms produced from the fractionator on devolatilized coal in the coal still retorting zone and cracking the scrubbed gas over hot char in the coal still retort, thus utilizing the coal still retorting zone to furnish the heat necessary to accomplish said oil shale distillation.

10. A method for destructive distillation of oil shale including the conservation and maximum recombination of hydrogen which is originally contained in a hydrocarbonaceous constituent of oil shale, comprising; continuously feeding oil shale through an internally heated and pressurized retorting zone, passing a thermal carrier fluid comprising essentially hydrogen at high temperatures of about 2000 F. and pressures between about fifteen to thirty atmospheres through the oil shale in concurrent flow heat exchange contact therewith for distilling the volatile matter from the oil shale, withdrawing the thermal carrier fluid and the primary volatile matter distilled from the oil shale and passing them at optimum temperatures and at least system pressures through a separate catalytic hydrofining operation for the purpose of eliminating high- 1y reactive and some undesirable components and separating the same from a condenser into liquid products and gases, passing the gases so produced in heat exchange con tact with a medium at sutficient temperature to crack the carbon and hydrogen constituents of the gases into gaseous hydrogen and carbon particles and recycling the cracked gas comprising principally hydrogen with some carbon particles therein through the internally heated oil shale retort as the thermal carrier gas.

11. A method as defined in claim 10 further comprising continuing to feed the oil shale downwardly after most of the primary volatile matter is distilled therefrom and withdrawn, and passing unheated hydrogen at system pressure countercurrently in heat exchange relationship with the so fed mostly devolatilized oil shale to accomplish a stripping of the remaining volatile matter in the oil shale and a transfer of some of the heat from the spent hot shale to the unheated hydrogen.

12. A method as defined in claim 11 comprising distilling coal in an adjunct internally fired, pressurized coal distilling zone, utilizing the heat of the products of combustion of said coal for preheating the coal and for furnishing safety gas locking of the hydrogen thermal carrier fluid in the oil shale retorting zone and disassociating carbon and hydrogen components of said gases into carbon particles and gaseous hydrogen by passing such gases over hot char resulting from the partial combustion of coal in said coal distillation vessel.

13. A process for destructive distillation of oil shale within an internally heated and pressurized retorting zone for the recovery of hydrogen and other permanent hydrogenous gases undiluted by the products of combustion or carbon dioxide, and for the production of light oils from the oil shale by the recombination of the hydrogen originally contained therein, said process comprising; feeding oil shale continuously and in a controlled manner through an internally heated, pressurized retorting zone, at a pressure between about fifteen to thirty atmospheres passing a thermal carrier fluid comprising principally hydrogen and containing carbon particles therein concurrently in contact with said so fed oil shale and thereby distilling most of the primary volatile matter from the oil shale, withdrawing the thermal carrier fluid mixed with the primary volatile matter distilled from the oil shale and passing the same through a hydrofining process at least at system pressures, and condensing an overhead stream into usable products and a resulting gas, passing the resulting gases in heat exchange relationship with a hot solid medium at system pressure for the purpose of disassociating said gases into gaseous hydrogen and carbon particles, and recyolmg the gaseous hydrogen and carbon particles so produced and at high temperature and system pressure back through the oil shale retort as the thermal carrier fluid whereby the hydrogen in the thermal carrier gas is utilized in the hydrofining process and the hydrogen contained in the resulting gases is reused after cracking as the thermal carrier fluid for the oil shale distillation.

14. A method for the production of light oils from oil shale through the recombination of hydrogen originally contained therein that comprises; feeding raw crushed oil shale vertically downward in a controlled manner through an internally heated retorting zone, passing a thermal carrier fluid comprising principally hydrogen at at least 2000 F. and about 15-30 atmospheres pressure concurrently throu-gh the oil shale as it is fed vertically downwardly, and thereby distilling most of the primary volatile matter from the oil shale, taking off the primary volatile matter and thermal carrier fluid from the retorting zone, at about 950 F. continuously feeding the mostly devolatilized oil shale vertically therebelow and contacting said oil shale with unheated hydrogen for stripping the remaining volatile matter therefrom and for transferring some of the heat from the hot calcine to the unheated hydrogen, passing thethermal carrier fluid and the primary volatile matter of the oil shale from the oiftake duct through a heat exchanging zone into a catalytic reaction zone at optimum temperature and system pressure, passing the stream from the catalytic reaction zone at system pressure to a fraotionating zone at system pressure, fractionatin-g the stream of thermal carrier fluid and primary volatile matter into heavy bottoms, middle oils, and a naphtha fraction, passing the middle oils to a high pressure hydrocracker and passing the entire stream from the high pressure hydrocracker back to the fractionator, passing the overhead naphtha fraction to a condenser and separating at the output of the condenser into liquid products and gases, scrubbing the condenser output gases to scrub out undesirable components, and passing the gases from the scrubber to a means tor cracking the gas and disassociating the hydrogen tfirom the carbon of the scrubbed gases while at the same time heating the hydrogen to a suflicient temperature and at suflicient pressure to be utilized as the thermal carrier fluid in the oil shale retort, and passing said hydrogen as said thermal carrier fluid into said oil shale retort.

References Cited in the file of this patent UNITED STATES PATENTS 2,474,345 Clark et a1 July 28, 1949 2,694,037 Johnson et a1. Nov. 9, 1954 2,885,338 Evans May 5, 1959 2,895,896 Vander Ploeg July 21, 1959 2,898,272 Odell Aug. 4, 1959 2,991,164 Elliott et a1. July 4, 1961 FOREIGN PATENTS 171,785 Great Britain Nov. 23, 1921 450,168 Canada July 27, 1948

Claims (1)

1. A METHOD FOR DESTRUCTIVE DISTILLATION OF OIL SHALE INCLUDING THE CONSERVATION AND MAXIMUM RECOMBINATION OF HYDROGEN WHICH IS ORIGINALLY CONTAINED IN A HYDROCARBONACEOUS CONSTITUTENT OF OIL SHALE THE METHOD COMPRISING FEEDING OIL SHALE BY GRAVITY DOWNWARD THROUGH AN INTERNALLY HEATED AND PRESSUREIZED RETORTING ZONE, PASSING A THERMAL CARRIER FLUID COMPRISING ESSENTIALLY HYDROGEN AT HIGH TEMPERATURES AND PRESSURES OF ABOUT FIFTEEN TO THIRTY ATMOSPHERES CONCURRENTLY THROUGH THE SO FED OIL SHALE IN HEAT EXCHANGE CONTACT THEREWITH FOR DISTILLING THE VOLATILE MATTER FROM THE OIL SHALE, PASSING THE THERMAL CARRIER FLUID

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