US3093571A - Method and apparatus for treating shale - Google Patents

Description

June 11, 1963 L. w. FISH ETAL 3,093,571

METHOD AND APPARATUS FOR TREATING SHALE Filed Oct. 20, 1958 Leonard W. Fish George F. Poppos Inventors United States Patent 3,093,571 METHOD AND APPARATUS FOR TREATING SHALE Leonard W. Fish and George F. Pappas, Westfield, N.J., assignors to Ema Research and Engineering Company, a corporation of Delaware Filed Oct. 20, 1958, Ser. No. 768,456

' 19 Claims. (Cl. 208-11) The present invention is concerned with the treatment of oil bearing solids, such as shale and the like. More particularly, it deals with a unique combination of steps for liberating hydrocarbon constituents from shale and thereafter enhancing the quality of the hydrocarbons while employing a single heating zone for supplying requisite heat to both steps through the media of circulating fine particulate solids.

The existence of vast quantities of hydrocarbons in the form of deposits of oil-bearing solids, e.g., shale, tar sand, etc., has long been acknowledged. The concept of subjecting shale to elevated temperatures (retorting) in order to break down their hydrocarbon matter, i.e., kerogen, into lighter fractions suitable for recovery is well known in the art. Towards this end, numerous processes have been advanced. The broad principle of employing hot gases and/or solids as a means of supplying heat to the retorting zone has been taught. Such systems generally employ a distinct combustion zone wherein the oxidation of spent shale, product oil or extraneous fuels serves to raise the temperature of the heat transfer media, which then passes to the retort. Product hydrocarbons are removed from .the retorting system and passed to storage or .sent to a conversion system entirely distinct from the retorting operation.

However, though a good deal of work has been done on shale oil recovery and treatment, in most regions hydrocarbons produced from shale are still more expensive than those derived from petroleum sources. Hence, there is .a considerable need for a cheaper'and more efli eient means for liberating hydrocarbons from shale, and for increasing both the quality and. quantity of shale oil products. The present invention 'is directed towards the fulfillment of this need.

In accordance with the present invention, both retorting and quality improving conversion of the liberated hydrocarbons are effected within a single combination system. A two-zone hydrocarbon conversion process, e.g., a fluid coker and burner, are integrated with aretorting zone in a manner such that a single burner sup plies requisiteheat for both theretorting and hydrocarbon conversion steps. .More particularly, carbon-coated fine particles are withdrawn from the hydrocarbon reaction stage and passed to the burner wherein they are subjected to combustion. A portion of the particles heated in this manner are passed to the reaction zone and a second solids. stream passed to retorting zone therebysupplying requisite thermal energy thereto. Liberated hydrocarbons pass directly from the retort to the hydrocarbon conversion stage wherein they are commingled with conversion vapors. A heavy ends portion .of the total product vapors is condensed and circulated back -to the reaction zone. 7

The present invention offers numerous advantages. No equipment isrequired for condensing the shale oil from the retort. Little-or no shale oil need :be usedas a heat source since combustion of the carbon deposits on the circulatingfine solids is the primary source ofrheat. Good yields are thus secured. Since the hydrocarbon conversion system burner serves to supply heat for both retorting and conversion, the need for a distinct heating vessel for retorting is eliminated. The presence of re- 3,093,571 Patented June 11, 1963 tort make gas, i.e., very low boiling fractions, in the total overhead of the hydrocarbon conversion zone as passed to scrubbing-fractionation is advantageous in that it depresses gas oil partial pressure and thus permits better controls over product out point, i.e., enhances the quality of the final shale oil product.

Generally, it is preferred to use coke as the fine particle heat carriers and the sites of the hydrocarbon conversion. The coke has a relatively high heat capacity and thus less of it need be circulated to the retort for heat supply purposes. However, in some applications, ceramics, sand, fine mineral particles, etc., may be employed. The fine particles may be catalytic in nature, as when it is desired to process liberated shale oil by a catalytic conversion step such as catalytic hydrogenation. The shale preferably undergoes retorting in the form of a descending moving solids bed, countercurrently contacting fine particles from the unitary burner as they pass through the bed as a gas-solids suspension.

By way of clarifying nomenclature, .the terms reaction zone, coking zone, etc., connotes both the very sites of hydrocarbon reaction, e.g., a fluidized solids bed, and associated areasnormally found in the same vessel, e.g., the disperse phase above the fluidized solids bed. The term two-zone system is used to describe the normal combination of a reaction and a heat supplying stage effecting treatment of feedstocks.

The various aspects of the present invention will be made more clearly apparentby reference tothe following description, drawing and accompanying example.

With reference to the drawing, shown therein is a combination system principally comprising retort 10, conversion vessel 11 and heater-burner 12. For the purposes of illustration, vessels 11 and 12 are afiuid bed Jcoking zone and a fluid bed burner zone. Within-coker 11 there is maintained a relatively dense, e.g., -30 to 60 lbs./ft. mass of coke particles ranging primarily from about 40 to 500 microns in size. Fluidizing gas, such as steam, is introduced by line 25 and serves to maintain the solids in the form of a highly turbulent bed of pseudo-liquid appearance. Feed oil, the source of which will be later discussedin detail, is contacted with the reaction solids which 'are at a-temperature in the range of -850-l200 F, e.g., 950 F. The oil upon contacting the hot solids is convertedinto vaporous .products such as gas oil, naphtha, etc. and carbonaceous residue,.the carbon residue depositing on, and coating, the contact particles. Vaporous reaction products, along with steam and vaporized feed, pass upwardly into disperse phase zone 43 locatedabove the;solids bed. After being subjected to solids-separation by one-or more cyclones 24, the gasiform material is normally passed to a scrubbing and fractionation unit 27 for rectification of its constituents.

A portion of the carbon-coated fine particles are wit-hdrawn fromcoker .11 through line 42 and passed with the aid of one or more aerationtaps44 to vessel 12. Within vessel 12, the carbonaceouscoating is subjected to combustion. Air 'or other oxygen-containing gas introduced by inlet 48serves tosupply requisite oxygen as well as maintaining the solidsin the form of a turbulentfluidized bed 45. Burner 12 is maintained at a temperature of Line 57 serves as a flexible means of altering the ,in-'

ventory of the burner vessel. If desired, a portion of the. reaction particles may be removed and recovered as product. Alternatively, it may serve as an inlet for introducingadditional fuel material to the burner. The fuel may be tar bottoms, a portion of the retorting zone make gas, or in some instances, spent shale. Normally, however, coker 11 is operated to lay down sufficient carbon on the contact solids so as to enable their oxidation to supply all requisite thermal energy for the over-all process.

In accordance with the present invention, a portion of the heated burner solids is circulated to coker 11 by means of line 49 and aeration taps 50 and 51. The hot coke serves to provide the necessary heat for the conversion process as well as serving as the sites of the coking reaction.

A second portion of the heated solids is circulated, by means of conduit 52 and multiple aeration taps 53, 54, 55, to retorting zone wherein the hot fine particles provide the requisite thermal energy for the breakdown of the kerogen matter found in the shale.

With respect to retort 10, introduced thereto by means of funnel-shaped inlet 13 and conduit 14 is a mass of shale solids. The shale is normally relatively coarse as compared to the hot coke particles, and is generally over 0.25 inch in size. Though not illustrated, the shale feed may be preheated to near retorting temperature by numerous means, such as heat exchange with burner flue gases, or with gases which had been heated by the hot spent shale which has been discharged from the retort.

The shale is distributed across retort 10 by grid 15 or the like and flows downwardly through the retort, preferably in the form of a moving fixed bed of 60 to 95 lbs./ft. density. During the course of its descent, it is subjected to temperatures of the order of 850 to 1200 F. or more by contact with the upwardly flowing stream of hot fine particles introduced by line 52. Conical grid member 16 serves to provide uniform contact between the fine solids and the coarse shale. Spent shale, i.e., shale which has been depleted in hydrocarbon matter, is withdrawn through outlet 17. Valve 19 serves to control holdup time with the retorting zone. A gas such as steam is injected through line 18 into the spent shale mass being withdrawn through outlet 17 in order to strip occluded hydrocarbons as well as provide separation of the fine particle heat carriers from spent shale. The spent shale may then be utilized as a heat source in a manner well known to those skilled in the art or simply discarded. The retort and conversion vessels usually operate at above atmospheric pressure, the retorting step taking place at the higher pressure.

While not shown, various techniques, eg a lock hoppet, for sealing the retort 10 from feed preheat or spent shale recovery zone may be employed.

Liberated hydrocarbons, principally in the Vaporous state, are withdrawn from retort 10 through conduit 20 and thereafter passed to hydrocarbon conversion vessel 11. Since normally the fine heat carrying particles pass through the retort as a rapidly moving suspension, the fine coke particles are also withdrawn through conduit 20. However, in those cases where a bed of fine particles is formed in the retort, the particles may be separately withdrawn through outlet 56 for passage to coker 11 and/or burner 12.

The retort product stream may be processed in several ways. Preferably, hydrocarbons and entrained particles (coke from the burner) are passed directly to disperse phase zone 43 of the hydrocarbon reactor by means of line 21. Solids are separated in cyclones 24 and passed to the reaction bed wherein heavy end fractions deposited on them during retorting undergo further thermal treatment. Vaporous retort products are passed from the cyclones by means of conduit 28 to scrubbing and/or fractionation unit 27, preferably in superimposed relationship to the reaction vessel.

Alternatively, the products of the retort zone and entrained coke particles may be passed directly into the reaction bed by means of line 22.

It is preferred to pass retort vapors into the disperse phase of the reaction vessel and then directly to the fractionation zone 27 in order that light hydrocarbon not be subjected to cracking in reaction bed 23 but rather be recovered without further conversion. The presence of retorting zone make-gas (light ends) in the fractiona tion zone will also permit better control over the end point of the coker products since it serves as a gas oil partial pressure depressant. Additionally, the retort vapors can serve to heat the disperse phase of the reaction zone, thereby minimizing condensation of upflowing vapors.

With respect to scrubber-fractionator 27, the unit contains various means for promoting good vapor-liquid contact such as sheds 29, plates 30, etc. Hot vapors from retorting and coking zone are contacted with downcoming, relatively cool oil streams thereby separating individual components by fractional condensation. Thus, a heavy ends fraction, having an initial boiling point of at least 900 F., collects as liquid pool 35 in the bottom of the scrubber. A gas oil fraction having an initial boiling point of about 430 F. is recovered through lines 32 and 34, normally a portion of the gas oil being returned to the fractionator as reflux, generally after being cooled, by means of conduit 33. A light naphtha may be removed overhead through outlet 31. A portion of the heavier hydrocarbons may be used as a quenching medium after removal by outlet 36, the heavy ends being cooled in cooler 38 and returned to the fractionator by line 37.

Heavy ends pool 35 serves as a convenient means for collecting the heavier hydrocarbons released in retort 10, it usually being particularly desired to subject this lowvalued fraction to cracking into lighter components. Thus, at least a portion of the heavy ends are passed to the reaction bed by means of lines 40 and one or more feed inlets 41. Generally, the heavy ends separated in the scrubber tower comprise the major portion of the feed to conversion bed 23. The heavy ends are thus cracked to gasiform material while depositing carbon on the reaction solids. As described previously, the carbon-coated reaction solids ultimately serve as the basic source of heat for the over-all process as well as being the heat carrying medium. If desired, heavy ends may be recovered as such by line 39.

In some instances, it may be desirable to add other coker feed material to vessel 11 by means of conduit 26. Thus, the present system is capable of being integrated with the treatment of heavy ends fractions resulting from the other refinery operations.

Tabulated below is a compilation of data applicable to the system heretofore described.

Table 1 Broad range Preferred range Retorting zone temperature, F 700 to 1, 600 850 to 1, 200 Hydrocarbon conversion zone temperature, F 850 to 1,500 850 to 1,200 Burner zone temperature 1, 050 to 1, 600 l, 100 to l, 500 S ze of shale in retorting zone, inches Over 0.25 O. 25 to 3 S1ze of circulating fine particles,

microns 40 to 500 40 to 300 Fine solids density in retorting zone,

1bs./fl7. 0.1 to 50 0.1 to 5 Solids density in reaction zone, lbs./[t. 25 to 30 to 60 Numerous modifications may be made to the system described above without departing from the spirit of the present invention. For example, a portion of the light gases derived from shale retorting may be used as conveyor gas for the circulation of the heat carrying fine particles. Though less desired, the burner and/or conversion zone may be other than fluidized bed zones. Similarly, the shale may be retorted in a form other than a compact solids column. While a suspension of fine solids in the retorting zone is preferred, the heat carriers may be in the form of a dense fluidized bed.

Summarily, the present invention offers means whereby shale retorting and the refining of liberated shale products zone hydrocarbon conversion system, said system-com prising a reaction zone and a burner zone, passing finely divided carbon-coated solid particles from said'reaction zone to said burner zone for oxidation therein, recycling at least a portion of the particles thus heated from said burner zone to said reaction zone, introducing and passing larger sized oil-bearing solids down through said retorting zone, passing at least aportion of said heated finely divided particles from said burner zone upwardly through said retorting zone to contact said downflowing larger sized oil-bearing solidsand to supply requisite retorting heat thereto and to form vaporous hydrocarbons, withdrawing spent oil-bearing solids from the bottom portion of said retorting Zone and discarding them from the method, withdrawing the vaporous hydrocarbons from said retorting zone and passing them to said reaction zone for further reaction, withdrawingvaporous reaction products overhead from said reaction zone, and returning finely divided solid particles from said retortingzone to said two-zone hydrocarbon conversion system.

2. The method of claim 1 wherein said'conversionsystern comprises a fluid bed coking zone and a burner zone, said burner zone serving to maintain said coking zone at a temperature of 850-1200 F. and said retorting zone at a temperature of 850-1500" F. by circulation of burner zone solids to each of said zones.

3. The method of claim 1 wherein said reaction zone contains a mass of solids and a disperse solids phase thereabove, and wherein at least part of the products of said retorting zone is passed to said disperse phase for commingling with reaction vaporous products, simultaneous product recovery being realized while improving recovered yields of reaction zone products.

4. The method of claim 1 wherein at least .a portion of the products of said retorting zone serve as fuel material for said burner zone.

5. An improved method for treating oil-bearing solids, which comprises maintaining a retorting zone and a twozone hydrocarbon conversion system, said system comprising a reaction zone and a burner zone, passing finely divided carbon-coated solid particles from said reaction zone to said burner zone for oxidation therein, recycling at least a portion of the particles thus heated from said burner zone to said reaction zone, passing larger sized oil-bearing solids through said retorting zone, passing at least a portion of said heated finely divided particles from said burner zone into said retorting zone to contact said larger sized oil-bearing particles and to supply requisite retorting heat thereto and form vaporous hydrocarbons, withdrawing spent oil-bearing solids from said retorting zone and discarding them from the method, withdrawing the vaporous hydrocarbons from said retorting zone and passing them to said reaction zone for further reaction, withdrawing vaporous reaction products overhead from said reaction zone, .and returning finely divided solid particles from said retorting zone to said two-zone hydrocarbon conversion system.

6. An improved process for treating shale which comprises, in combination, maintaining a two-zone fluid coking system and a retorting zone, said coking system comprising a fluid bed reaction zone and a fluidized burner zone, circulating carbon-coated particulate solids from said reaction zone to said burner zone for combustion therein, passing at least a portion of the thus heated particulate solids from said burner zone to said reaction zone to supply requisite heat, passing shale particles through said retorting zone, circulating hot particulate, solids from said burner zone to said retorting zone to maintain a retorting temperature therein, hydrocarbon products thereby being liberated in said retorting zone, withdrawing spent shale particles from-the lower portion of said retorting zone and discarding them from the process, returning particulate solids from said retorting zone to said coking system and introducing at least aportion of the retorting zone products into said reaction zone and withdrawing vaporous reaction products from said reaction zone.

7. The process of claim 6 wherein said shale particles are primarily above 0.25 inch in size and said particulate solids range from 40 to 500 microns in diameter.

8. The process of claim 6 wherein a scrubbing zone is positioned above said fluid bed reactionzone for treatment of reaction zone vaporous products, and wherein said retorting zone products are commingled with reaction zone vaporous products prior to their passage to said scrubbing zone,

9. The process of claim 6 wherein shale passes through said retorting zone as a downwardly moving solids bed, and said particulate solids pass upwardly through said moving solids bed in the form of a flowing solids-gas suspension.

10. The processof claim 8 wherein the commingled products of said retorting zone and reaction zone are subjected to solids separation prior to passage to said scrubbing zone.

11. A combination process for retorting shale and improving the qu-ality of the hydrocarbons liberated there from, which comprises, establishing a retorting zone, a fluid bed coking zone and a fluid bed burner zone, circulating carbon-coated particulate solids below about 500 microns from said coking zone to said burner zone for combustion therein and returning at least a portion of said particulate solids thus heated from said burner zone to said coking zone to supply requisite heat thereto, flowing shale particles predominately over 0.25 inch in size down through said retorting zone in the form of a descending solids column, withdrawing spent shale particles from the bottom portion of said retorting zone and discarding them from the process circulating hot particulate solids from said fluid bed burner zone to said retorting zone in order to supply requisite heat thereto, passing said particulate solids through said retorting zone in the form of an upwardly moving suspension, hydrocarbon products thereby being liberated from said shale, withdrawing hydrocarbon products and par-ticulate solids from said retorting zone and passing at least a portion thereof to said fluid bed coking zone.

12. The combination process of claim 11 wherein said particulate solids are coke particles ranging primarily from 40 to 500 microns in diameter, and said burner solids maintain both said retorting and coking zones at a temperature in the range of about 850 to 1200 F.

13. Apparatus for treating oil-bearing solids which comprises, in combination, a retorting vessel, a hydrocarbon reaction vessel and a burner, conduit means for passing particles from said reaction vessel to said burner for heating herein, means for flowing heated particles from said burner to said reaction vessel, inlet means for introducing oil-bearing solids into said retorting vessel and a bottom outlet for withdrawing and discarding solids from the bottom portion of said retoring vessel, passageway means for flowing heated particles from said burner to the bottom portion of said retorting vessel, outlet means for withdrawing liberated hydrocarbons and particles from said retorting zone, and conduit means operating in conjunction with said outlet means for passing at least part of said liberated hydrocarbons to said reaction vessel.

14. The apparatus of claim 13 which further comprises 7 a scrubbing unit in superimposed relationship to said reaction vessel, said unit being adapted to treat both the products of said reaction and said retorting vessels.

15. A process for treating oil-bearing solids to recover hydrocarbon oil which comprises providing a retorting zone and a two-zone hydrocarbon conversion system, said system including a coking zone and a burner zone, circul ating finely divided solids between said zones including passing such solids from said coking zone to said burner zone for burning and heating the solids and recycling part of the heated solids to said coking zone, flowing oil-bearing solids down through said retorting zone, passing another portion of the heated solids from said burner zone upwardly through said retorting zone to supply retouting heat to said oil-bearing solids therein, withdrawing spent solids from the bottom portion of said retorting zone and discarding them from the process, removing retorted vapors and upflowing solids overhead from said retorting zone and passing them to said coking zone and removing vaporous reaction products overhead from said coking zone.

16. A process for treating oil shale which comprises providing a two-zone fluid coking system and a retorting zone, said coking system including a fluid bed reaction zone and a fluid bed burner zone, introducing oil shale particles into the upper portion of said retorting zone and passing said oil shale particles downwardly through said retorting zone, passing hot finely divided solids from said burner zone into the bottom portion of said retorting zone and then upwardly through said downwardly moving oil shale particles to supply heat to said oil shale particles and maintain a retorting temperature in said retorting zone, withdrawing spent shale particles from the bottom portion of said retorting zone and discarding them from the system, withdrawing said finely divided solids and liberated hydrocarbons from the upper portion of said retorting zone and passing them to said reaction zone, rcmoving hydrocarbon vapors overhead from said reaction zone, passing carbon coated solid particles from said reaction zone to said burner zone for combustion and heating therein, passing at least a part of the thus heated solids from said burner zone to said reaction zone to supply heat of reaction thereto, and passing another portion of the thus heated solids to the bottom portion of said retorting zone as the finely divided solids previously mentioned.

17. A process according to claim 16 wherein at least part of said hydrocarbon vapors liberated in said retorting zone is passed through said fluid bed in said reaction zone. in

18. A process according to claim 17 wherein said finely divided solids contain heavy hydrocarbon ends and are separated from said liberated hydrocarbon vapors from said retorting zone and passed to the fluid bed in said reaction zone.

19. A process according to claim 18 wherein at least part of said separated liberated hydrocarbon vapors is introduced into the space above the fluid bed in said reaction zone for commingling with the products from said reaction zone fluid bed.

References Cited in the file of this patent UNITED STATES PATENTS 2,455,915 Borcherding Dec. 14, 1948 2,726,196 Bloomer Dec. 6, 1955 2,734,852 Moser Feb. 14, 1956 2,807,571 Murphy et a1 Sept. 24, 1957 2,890,993 Kleiber June 16, 1959

Claims (1)

1. AN IMPROVED METHOD FOR TREATING OIL-BEARING SOLIDS, WHICH COMPRISES MAINTAINING A RETORTING ZONE AND A TWOZONE HYDROCARBON CONVERSION SYSTEM, SAID SYSTEM COMPRISING A REACTION ZONE AND A BURNER ZONE, PASSING FINELY DIVIDED CARBON-COATED SOLID PARTICLES FROM SAID REACTION ZONE TO SAID BURNER ZONE FOR OXIDATION THEREIN, RECYCLING AT LEAST A PORTION OF THE PARTICLES THUS HEATED FROM AID BURNER ZONE TO SAID REACTION ZONE, INTRODUCING AND PASSING LARGER SIZED OIL-BEARING SOLIDS DOWN THROUGH SAID RETORTING ZONE, PASSING AT LEAST A PORTION OF SAID HEATED FINELY DIVIDED PARTICLES FROM SAID BURNER ZONE UPWARDLY THROUGH SAID RETORTING ZONE TO CONTACT SAID DOWNFLOWING LARGER SIZED OIL-BEARING SOLIDS AND TO SUPPLYING REQUISTS RETORTING HEAT THERETO AND TO FORM VAPOROUS HYDROCARBONS, WITHDRAWING SPENT OIL-BEARING SOLIDS FROM THE BOTTOM PORTION OF SAID RETORTING ZONE AND DISCARDING THEM FROM THE METHOD, WITHDRAWING THE VAPOROUS HYDROCARBONS FROM SAID RETORTING ZONE AND PASSING THEM TO SAID REACTION ZONE FOR FURTHER REACTION, WITHDRAWING VAPOROUS REACTION PRODUCTS OVERHEAD FROM SAID REACTION ZONE, AND RETURNING FINELY DIVIDED SOLID PARTICLES FORM SAID RETORTING ZONE TO SAID TWO-ZONE HYDROCATBON CNVERSION SYSTEM.

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