|Publication number||US3018243 A|
|Publication date||Jan 23, 1962|
|Filing date||Mar 9, 1959|
|Priority date||Mar 9, 1959|
|Publication number||US 3018243 A, US 3018243A, US-A-3018243, US3018243 A, US3018243A|
|Inventors||Nevens Thomas D|
|Original Assignee||Oil Shale Corp|
|Export Citation||BiBTeX, EndNote, RefMan|
|Patent Citations (3), Referenced by (11), Classifications (5)|
|External Links: USPTO, USPTO Assignment, Espacenet|
Jan. 23, 1962 T. D. NEvENs 3,018,243
PLANT AND PROCESS FOR PRODUCTION OF LOw TEMPERATURE PUMPABLE OIL FROM OIL sHALR AND IRE LIKE Filed March 9. 1959 BY M RR@ I Qfawg MM. une NN l vvv mm www* v United States Patent 3,018,243 PLANT AND PROCESS FOR PRODUCTION F LOW TEMPERATURE PUMIABLE OIL FROM OIL SHALE AND THE LIKE Thomas D. Nevens, Denver, Colo., assigner, by mesne assignments, to The Oil Shale Corporation, Beverly Hills, Calif., a corporation of Nevada Filed Mar. 9, 1959, Ser. No. 798,083 Claims. (Cl. 208-11) This invention relates generally to a plant and process for -the production of oil from solid substances leaving a carbonaceous residue, such as oil shale, peat, etc., and more specifically relates to a plant and process for the production of shale oil and the like having a low pour point and reduced viscosity. The term carbonaceous residue denotes a residue which includes xed combustible carbon.
inasmuch as the large deposits of solid materials, such as loil shale, are found some distance from renery centers, it has heretofore been considered desirable to crack all the oil pyrolyzed from the solid materials in such a manner as to reduce its viscosity, and/ or pour point prior to its introduction into a pipeline for ease in transportation. Such a thermal cracking is sometimes referred to as visbreaking, or if the cracking is prolonged, as coking. While the pour point of an oil is not the most accurate measure of its purnpability, the pour point test does give a fair indication, and generally speaking, the lower the pour point, the better the pumpability at the lower ternperatures.
One plant and method wherein combined pyrolysis and cracking are advantageously employed to secure a lower temperature pumpabili-ty of shale oil is disclosed in my copending U.S. application, Serial No. 777,354 entitled Plant and Process for Production of Low Temperature Pumpable Oil From Oil Shaleand the Like. In that application, a plant and process are disclosed for the production of oil having a low pour point and reduced viscosity wherein the amount of valuable oil loss in the form of non-condensable gases is substantially reduced over prior art processes known to me. Prior to that plant and method, the combined pyrolysis and cracking processes, while resulting in the lowering of pour point of the oil product, inherently produced a relatively high amount of oil loss in the form of non-condensable gases.
The basic concept involved in my copending application is the condensation of the heavier pyrolyzed oil vapors and the cracking thereof in a separate cracking unit, the cracked oil vapors and the nncracked oil vapors being then combined and condensed, the composite oil thereby produced being a low temperature pumpable oil having only approximately one-half or less the normal amount of oil loss. The process of my copending application and of other combined pyrolysis and thermal cracking processes known to me requires that a separate pyrolysis drum and cracking unit be employed.
The process of my above-identied and described copending application is extremely advantageous and desirable in many instances. For example, the thermal cracking operation may be conducted within wide temperature limits and within wide limits of residence time. However the equipment required to perform the process is relatively expensive since in addition to the pyrolysis unit or drum, a separate cracker must also be employed. Bearing in mind the foregoing facts, the major object of the present invention is to provide a plant and process for the production yof oil having a low pour point and reduced viscosity from solid material such as oil shale and the like wherein the amount of valuable oil loss in the form of non-condensable gases is substantially refice and gases is accomplished over a wide range of tempera-' v tures and residence times. v
Yet a further object of the present invention is to provide a plant and process for the production of oil from oil shale and the like wherein a low capital investment in plant equipment is required for both a pyrolysis and cracking operation, but with no sacrifice in ease and variation of control during both the pyrolysis and cracking phases of the process.
These, and other objects, of the present invention will become clearly understood by referring to the following description and to the accompanying igure in which the figure is a diagrammatic elevational View of one preferred embodiment of the invention showing the important parts of the plant and process of the invention.
In general, the plant and process therefor of my pres ent invention includes operations which remove the lighter fractions of oil vapors and gases resulting from the pyrolysis (eg. gas oil, gasoline and kerosene) prior to the cracking step, in much the same manner as in my copending application, since the cracking of these fractions contributes relatively little to the reduction in both pour point and viscosity of the resulting oil, but if cracked, they give rise to a relatively large loss of oil in the form of non-condensable gases. On the other hand, the cracking of the heavier oil fractions resulting from ,the pyrolysis does contribute considerably to the reduction in viscosity and the pour point of the resulting oil product but does no-t produce relatively large amounts of non condensable gas.
More specifically, the process of my present invention comprises the steps of pyrolyzing oil shale or the like to produce efuent oil vapors and gases, cooling the eiiuent to a predetermined temperature to thereby condense the heavier fractions contained therein but not the lighter fractions, thermally cracking the heavier fractions within a certain predetermined period of residence time, by recycling at least a portion of the heavier fractions to the zone wherein the pyrolysis takes place, either indirectly, i.e. via one of the several material streams entering therein or directly to the zone of pyrolysis itself, all of which will be described in detail hereafter. The uncracked lighter fractions, as well as the thus cracked heavier fractions, are then 4condensed to thereby produce a composite oil product which has a pour point and viscosity comparable to, or slightly less than that of shale oil produced after the pyrolysis and cracking of all the euent oil vapors and gases from the pyrolysis, the loss of oil by my present process being substantially less than in such prior art processes.
Referring now to the figure a solid material, such as oil shale, and generally spherical solid heat-carrying bodies, enter a reactor zone, which is preferably in the form of a rotatable drum 10, via the conduits 12 and 14, respectively. The oil shale enters the conduit from a hopper 16 communicating therewith. The conduit 12 has a conveyor means 17 mounted therein driven by a motor 18 to insure a proper rate of inflow of oil shale :into the reactor drum 10.
The oil shale usually enters the drum 10 at a low temperature, e.g. 50 F., althoughfrequently it is desirable to preheat the oil shale to a temperature as high as 500 to 600 F. 'Ihe heat-carrying bodies or ball; are made of a hard-resistant material, such as alumina, or other ceramic material, or steel and preferably have a diameter somewhat larger than the average mesh size of -the` incoming cold or preheated oil shale. For example, the
ball diameter usually ranges between one-half to onek inch, whereas the average oil shale mesh size is usually minus one-quarter or minus one-half inch.
The heat-carrying bodies or balls preferably enter the reactor drum at a temperature lying within the range of 1,000" to 1,400 F., and are preferably intermixed in parallel ow, with the oil shale. Counter-flow of balls and oil shale is also employed, although parallel ow is presently preferred. The ratio of the balls to oil shale generally ranges between 1:1 and 3:1, depending upon the inlet temperature of the oil shale being processed, the vtype of heat-carrying bodies being employd, and the rate of heat-transfer sought.
ilt should be noted .that while other modes of preheating and pyrolyzing oil shale and the like can be employed, e.g. tluidized bed processes employing heated gases for the preheating and pyrolysis, the preferred method and means for such operations (and also for the thermal cracking) utilizes generally spherical solid heat-carrying bodies of the type above described. The advantages of such method and means are several, and are gone into in detail in a copending application Serial No. 702,150, entitled Method and Apparatus for Stripping Oil From Oil Shale, filed December 1l, 1957.
' .On admixture of the heat-carrying bodies with oil shale in the rotating reactor drum 10, heat is transferred from the bodies to the oil shale by solid to solid heat transfer. `The hot bodies continually come into contact with all of the oil shale due to the rotation of the drum 10. Pyrolysis of the oil shale then occurs and theeluent oil vapors and gases leave the drum 10 via a vapor outlet line located at the oil shale-and-ball inlet end 21 of the pyrolysis drum 10. Attention is drawn to the fact that the oil and gas vapors could be removed from the ball and shale coke outlet end 23 of the pyrolysis drum 10 instead of the ball and shale inlet end 21 (as shown) if desired. It is preferable, however, to remove the oil and gases from the ball and shale coke inlet end 21. For it has been found that the majority of .dust Ithat is generated within the reactor drum 10 is generated at the ball and shale outlet end 23 during and after the shale is pyrolyzed and the entrainment of dust within the oil and gas vapors is minimized when the oil and gas vapors travel the length of the drum back to the inlet end 21 and through an area of less dust before they are removed.
The pyrolyzed oil vapors and gases have a temperature preferably lying between 750 F. to 950 F. They are passed into a partial condenser unit 30, and are cooled therein to a temperature lying preferably between 500 F. and'8.00 F. in a manner described below. Those fractions of the oil vapors and gases which remain a vapor at 500 F. to 800 F., e.g. gas oil, kerosene and gasoline are, of course, not condensed and pass directly into a condenser 32 via overhead line 34.
The partial condenser unit 30 also preferably functions as a combination dust scrubber and oil aerosol scrubber. Thus those liquiied heavier fractions of the eflluent oil vapors and gases, such as the high boiling tars, etc. include agglomerated aerosols and dust, all of this material being removed from the bottom of the partial condenser 30 by a pump 42, capable of handling sludges, located in bottom discharge line 36.
The oil vapors and gas sent into the partial condenser 30 preferably meet, and are cooled by, cool heavy oil (preferably uncracked heavy shale oil) having a temperature of between 400 and 750 F. 'Ihe cool oil is preferably atomized counter-currently to the oil vapors and gases thereby liquefying and removing the heavier fractions and also causing the removal of dust and oil aerosols. The amount of cooling of the oil vapors obtained by this means is preferably between approximately 50 to 250 F. This means of condensing the heavier oil fractions is extremely advantageous inasmuch as dust and oil aerosol are substantially completely removed from the oi-l vapors and gases.
The condensed heavier oil fraction which usually cornprises approximately 10% to 50% of the total collectible oil product is passed from conduit 36 into either or both recycle lines 3S and 40 by means of the pump 42. This heavier oil fraction has a pour point usually in the range of to 130 F. `but yis pumped easily by pump 42 since it is at a temperature of 500 to `800 `F.
The heavier oil is sent ,into recycle lines 3,8 and 40 respectively in any desired proportion. For example, approximately 75% of the heavier fractions can be recycled through a heat exchanger 44, `thence to the top of the partial condenser 30 via line 46. The heat exchanger 44 serves to cool the recycled oil from approximately 50 to 350 F. and it is then atomized countercurrently to the pyrolyzed oil vapors and gases to Vremove dust, agglomerated oil aerosol and the heavier oils therefrom, as described above.
That portion of the heavier fraction of oil not recycled for cooling purposes through line 40, is recycled via line 38 -to the reactor drum 10 for thermal cracking, by one of several of a number .of different methods described below. It is important that the degree of thermal cracking be controlled to as great an extent as possible. This in turn requires a control of the temperature of the recycled heavier oil fraction and also a control of its residence time, while it is in the reactor drum 10. 'Ihe thermal cracking operations are found to be. controlled to a very great degree by lthe manner in which the heavier oil fraction is introduced into the reactor drum 10.
In order to obtain a relatively large amount of thermal cracking, the heavier oil fraction is sent from line 38 into line 58, the valves 56, 65 and 52 being closed, While the valve 55 is open. The heavier oil fraction is sent from line 58 directly into the hot incoming ball stream, entering via line 14. As mentioned, the balls entering the drum have a temperature of approximately between l,000 and 1,400 F. and the amount of cracking that the heavier oil fraction will undergo is substantial compared with the amount of cracking obtained by methods to be described.
To obtain a reduced amount of thermal cracking of Ilthe heavier oil fraction, the oil vapors may be sent to any one of a number of other locations. For example, they may lbe sent along line 38, valve 52 located Vtherein being opened and the valves 55, 56 and 65 located in the auxiliary (dotted) lines 58, 60 and 63 respectively being closed. The recycled heavier oil fraction is thus introduced directly into the shale inlet line 12, which has a temperature of between 50 to 600 F.
If the heavy oil fraction is cracked to a point greater than desired by its introduction into the reactor drum 10 via the high temperature ball inlet line 14, it may be desirable to introduce Ithe recycled oil into the reactor drum just in front of the oil Vapor takeoff line Z0 at a point designated by the numeral 61. In this case, the recycled oil lwill pass from line 38 directly into line 60 through open valve 56. The other valves 52, 55 and 65 are, of course, closed. This mode of introducing the recycled heavy condensed oil fraction has the added advantage that the dust and yoil aerosols in the effluent oil vapors and gashes are scrubbed or removed therefrom, by contact with the entering recycled oil, prior to their entry into the oil or vapor take-oli:` line 20. In this manner, the load of the partial condenser is appreciably reduced.
It is also vfrequently vdesirable to introduce the recycled oil fraction directly into the ball-oil shale mixture in the reactor drum 10, as for example, via dotted line 63 and through open valve 65. Valves 52, 56 and 55 are closed. The line 63 may extend to any point axially located anywhere between ends 21 and 23 of drum. Thus, the line 63 may extend only to some point nearer the inlet end 21 of the drum or could extend nearer the shale and ball outlet end 23 of the drum in order to reduce the residence time and thus reduce the amount of thermal cracking that is desired.
While all the oil recycled, via line 38, may be sent t a single location for inlet into the reactor drum 10, it is frequently desirable to introduce the recycled oil into the reactor drum at two or more different locations. For example, it has been found desirable to introduce a portion of the recycled oil to be thermally cracked into the line 60, as above described, so as to remove an appreciable part of the dust and oil aerosols from the pyrolyzed eluent oil vapors and to send the remaining portion of the recycle heavy oil to the location in the reactor drum 10 where the optimum thermal cracking, for the particular heavy oil fraction, can be realized.
The cracked oil vapors and gases leave the reactor drum 10 with the pyrolyzed oil vapors and gases, via take-olf line 20, the lighter oil fraction passing, via overhead line 34, to the condenser 32. The oil product leaves condenser 32, via line 33, at a low temperature preferably, of the order of 100 F.
The oil product produced according to the above process is highly advantageous in that, for Colorado oil shale, the pour point generally lies in the neighborhood of 30 to 60 F.; and what is also extremely important, the loss of oil in the process typically amounts to approximately only to 15% of the total oil collectible. In most prior art processes, wherein shale oil of such a pour point is produced, appreciably more oil loss occurs in the form of non-condensable gases and coke due to the cracking of all the pyrolyzed oil vapors and gases.
The amount of liquid oil sent to the reactor drum is of the order of 1% to 2% of the total solids entering the drum. The tars in the heavy oil fraction, and the coke produced during the thermal cracking do not however gum up, or stick to, the walls of the reactor drum 10 because of the great proportion of solids to liquids sent to the reactor drum. Most of the coke and tar formation in the reactor drum 10 is picked up by the balls and/ or shale coke and is later combusted to furnish additional heat for the reheating of the balls, as will be described hereafter. After the pyrolysis of the oil shale in the reactor drum 10, the carbonaceous residue (which, in the case of the carbonaceous shale residue, is hereinafter, and in the claims, termed shale coke) passes, together with the balls, into the chamber 62. The carbonaceous residue passes downwardly together with the balls, through the passageway 64 and into a ball-heating zone 66 via line 67. The shale coke is then combusted by means of air or preheated air to furnish heat for the reheating of the balls, and the heated balls are then passed via line 68 into the ball-inlet line 14 for the pyrolysis and thermal cracking operations in the reactor drum 10.
In many cases it is found desirable to combust the shale coke in a zone separate from that of the 'ball heating zone and to this end, the carbonaceous residue is separated from the larger balls in any convenient manner, such as, for example, by screening operations (not shown). In this connection, the carbonaceous residue is considerably reduced in size over the initial oil shale mesh size due to the grinding and crushing action of the hard balls on the oil shale in the reactor drum 10. The separation of the carbonaceous residue from the balls is thus readily effected by screening means. It should also be understood that other methods of separation of balls from carbonaceous residue can also be employed, such as by magnetic or elutriation means, or trommels.
'I'he separated shale coke is sent to the combustion zone 70 via dotted line 72, air is provided for combustion, entering zone 70 via line 71, and the products of combustion are sent to the ball heating zone 66 via dotted line 74.
Mention has previously been made of the fact that the oil shale entering the reactor drum i10 may either be cold or preheated. A preferred method of preheating involves mixing fresh oil shale with hotter balls in either parallel or counterflow, las is disclosed in detail in the aboveidentified copending U.S. application of William J. Cul bertson, Jr. The hot balls employed for the solid material preheating step are preferably those taken from the reactor drum 10. After preheating the oil shale, the balls are sent through the ball-heating step previously described.
Attention is drawn to the fact that the thermal cracking operations made possible :by the process of the present invention have an extremely wide range of temperature limits and also wide residence time limits within the reactor drum or chamber 10.` At `one extreme, the initial cracking temperature can be as high as 1000" F. to 1400 F. (if the heavy oil fraction is introduced indirectly into the drum 10 via the ball inlet line 14) or as low as 50 to 600 (if introduced indirectly into the drum 10 via te oil shale inlet line 12). If initial temperatures desired are in the intermediate range, c g. 750 F. to 950 F., the heavy oil fraction is introduced into the ball-oil shale admixture directly, at the appropriate point, in the reactor drum 10 corresponding to the period of residence time desired. In this connection, it is possible that the recycled heavier oil fraction in the reactor drum 10 can contact hot moving heat-carrying bodies for a period of time ranging between approximately several seconds to approximately ve minutes.
A specific example of one preferred form of the process is set forth below:
A ton of Colorado oil shale, of approximately 1A inch mesh size, having a Fischer assay of 22.5 gallons of oil per ton of shale, enters the drum 10 via line 12, along with 1.2 tons of si aluminum oxide-containing ceramic balls, the balls entering the drum 10 via line 14. The oil shale has an average inlet temperature of 500 F. and the balls have an average inlet temperature of 1300 F.
Approximately 180 pounds of oil vapors and 25 pounds of gases are produced during the pyrolysis in the reactor drum 10, the oil vapors and gases (at a temperature of 850 F.) passing, via the oil vapor and gas takeoff line 20 to the partial condenser 30. Ihe oil vapors and gases are cooled in the partial spray condenser 30 to a temperature of approximately 700 F., about 60 pounds of oil being condensed thereby.
The 60 pounds of heavier oil fractions are pumped, by pump 42, through line 36 and approximately 75% or 45 pounds, are recycled through line 40 for cooling purposes. The remaining 25 or 15 pounds, is recycled into the reactor drum 10 for thermal cracking and revaporization. Actually, as much heavy oil eventually passes through line 38 as comes through line 20. It is, however, split in the 3:1 ratio as between lines 38' and 40.
The recycled oil for cooling is passed through an air or water heat exchanger 44, then along line 46 to be then atomized counter-currently to the incoming oil vapors and gases thereby condensing the heavier portion of these, as well as agglomerating the oil aerosols, and bringing down substantially all the dust.
The lighter non-condensed fractions pass through the overhead line 34 and are sent to the condenser 32, and are cooled to F. The condensed oil is then sent to a storage tank for transportation at some later time, or may be directly transferred to a pipeline. 'I'he non-condensable gases pass from the condenser 32, via line 35, for processing or use.
The heavy oil fractions are recycled, via line 38, into line y63 which leads into the reactor drum 10 at a point such that the residence time of the oil is approximately one minute and the temperature of the ball-shale admxture is in the neighborhood of 850 F. The heavy oil is thermally cracked and the cracked oil vapors are taken from the reactor drum 10 along with freshly pyrolyzed oil vapors to the condenser 30. 'Ihe lighter oil fraction,
7 including the thermally cracked oil, is drawn off the top of the unit 30, via line 34, into condenser 3-2.
Approximately only 18 pounds or -10% of the maximum oil recovery is converted into non-condensable gases and coke. The pour point of the composite product is approximately 40 F.
Comparing the results of the process when all conditions are equivalent to those just described except that all the effluent vapors are cracked, the pour point of the resulting oil was 40 F. and the loss of oil was in the neighborhood of 36 pounds or 20% of the total oil collectible.
The balls and shale coke produced leave the reactor drum via chamber 62 in line y64, the balls being then reheated to a temperature of l300 F. by directly contactingvthem with the hot product of combustion of the shale coke. The balls are then sent to the reactor drum 10 via line 68 to contact fresh incoming oil shale.
Attention is drawn to the fact that the eliminaion of a separate cracking unit, besides having the advantage of lower equipment costs and variation of controlled thermal cracking conditions, also has the advantage that fewer vapor or gas seals are required. The amount of piping is reduced and the number of connections between various pieces of equipment is also reduced. This is an important advantage in reducing the loss of gases from the system.
While several preferred embodiments of my invention have been shown and described herein, it will be understood that modiiications and changes may be made herein that lie within the ordinary skill of those in the art. For this reason, I do not intend to be bound by the embodiment herein shown and described, but intend to be bound only by the appended claims.
l. An continuous process for producing a low temperature pumpable oil from attritionable solid -material which upon heating leaves a combustible carbonaceous residue which comprises contacting the solid material in particulate form in a heating zone in solid-to-solid milling contact with hot, solid, heat-carrying bodies larger in particle size than said combustible residue, to produce oil vapors and gases, said vapors containing Va heavier oil fraction and a lighter oil fraction; condensing at least part of the heavier oil fraction in Isaid oil vapors; returning at least a portion of said condensed heavier oil fraction to the heating zone to thermally crack and vaporize said fraction; condensing s-aid thermally cracked oil vapors and said lighter oil fraction to produce at -least one oil product; burning said combustible residue to produce hot products of combustion; and employing heat produced by the burning of said combustible residue to reheat said heat-carrying bodies.
2. A process according to claim l in which the oil vapors yand gases produced in the heating zone have a temperature between about 750 and about 950 F. and
8 are cooled during condensation to between about 500 and about 800 F.
3. A process according to claim l wherein a portion of the heavier condensed oil fraction is cooled and, after being cooled, is directly cont-acted with said oil vapors and gases to thereby condense heavier oil therefrom and to entrap and carry down dust.
4. A process according to claim l in which the condensed heavier oil fraction is introduced directly into the heating zone. Y
5. A process according Vto claim 1 in which the condensed heavier oil fraction is introduced into the heating zone in admixture with one of the solid materials fed to the heating zone.
6. A process according to claim l in which the attritionable solid material is oil shale.
7. A plant for producing oil from solid attritionable materials leaving a solid carbonaceous residue, which comprises: a continuously circulating load of heat-carrying solid bodies harder than the solid material and having a particle size greater than said carbonaceous residue; reactor means for heating said solid material to an elevated temperature and causing the evolution of oil vapors and gases therefrom, including inlet means for said solid material, inlet means vfor said heat-carrying solid bodies; outlet means for discharging from said `reactor means said oil vapors and gases, said carbonaceous residue, and said he-at-carrying bodies; partial condensation means, communicating with said outlet means for oil vapors and gases, ffor cooling the oil vapors and gases to a temperature such that a substantial por-tion of the heavier oil fractions contained therein, but not the lighter fractions, are condensed; means for recycling at least a portion of said heavier oil frac-tion to said reactor means for the cracking thereof; and means for condensing said cracked `heavier oil fractions and said lighter fractions to produce a composite oil product.
8. The apparatus of claim 7 wherein said recycling means leads to said solid material inlet means.
9. The apparatus of claim 7'wherein said recycling means leads to said heat-carrying body inlet means.
10. The apparatus of claim 7 having a conduit means for recycling a portion o-f the heavier oil fraction to a cooling means, and having another conduit means for recycling the cooled oil fraction to said partial condensing means for condensing additional heavy oils from said oil vapors and gases by direct contact therewith.
References Cited in the tile of this patent UNITED STATES PATENTS 2,457,457 Frejacques Dec. 28, 1948 2,489,702 Coast Nov. 29, 1949 2,905,595 Berg Sept. 22, 1959
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|International Classification||C10G1/02, C10G1/00|