US3350280A

US3350280A - Retort for oil-bearing shales

Info

Publication number: US3350280A
Application number: US320450A
Authority: US
Inventors: Howard F West
Original assignee: Standard Oil Co
Current assignee: Standard Oil Co
Priority date: 1963-10-31
Filing date: 1963-10-31
Publication date: 1967-10-31
Anticipated expiration: 1984-10-31
Also published as: GB1017410A; ES305605A1

Description

Oct. 31, 1967 H. F. WEST RETORT FOR OIL-BEARING SHALES Fi led Oct. 51, 1963 INVENTOR.

HOWARD F. WEST W .ATTO NEY United States Patent 3,350,280 RETORT FOR OIL-BEARING SHALES Howard F. West, Shaker Heights, Ohio, assignor, by mesne assignments, to The Standard Oil Company, Cleveland, Ohio, a corporation of Ohio Filed Oct. 31, 1963, Ser. No. 320,450 3 Claims. (Cl. 20299) The present invention relates to improvements in rotatable vessels for treatment such as grinding and drying, heating, dry-distillation or cooling, of piece-shaped material of different kinds by means of heated or cooled loose balls which are brought into direct contact with the mate rial to be treated.

The present invention is particularly useful in the drydistillation of such materials as bituminous shales and the like, peat, saw-dust, wood chips, coal and other distillable substances, but is especially useful in the dry-distillation of oil-bearing shales.

It is an object of the present invention to provide an apparatus useful in the distillation of oil-bearing shales and the like at low temperatures, with a rapid transfer of the distilling heat to the material being distilled, and without any necessity for employing the expensive heating surfaces heretofore required because of the slow and inefficient heat transfer of many of the prior low temperature distillation procedures.

In order to recover oil from oil shale and similar oilbearing solids, it is necessary to retort them to break down the solid or semi-solid hydrocarbon or oil-forming materials such as kerogen. The hydrocarbons, thus broken down to products of moderate molecular weight, are driven off as vapors or entrained liquids. Oil shale, for example, is usually broken into small lumps or particles and then heated to a temperature of about 850-l000 F. or more for a sufficient time to convert the kerogen and to recover the desired oil products.

It has previously been proposed to treat oil shale by heating it in a first rotating furnace by means of loose heat-carrying bodies and wherein said heat-carrying bodies are first heated in asecond rotating furnace by combustion of fuel in admixture therewith, the heat-carrying bodies circulating through both furnaces. It is not necessary that two rotating furnaces be employed so long as the heat-carrying bodies are heated by some external means and then brought into contact in a rotating furnace with the oil shale to cover grinding, heat transfer and retorting of the shale.

The present invention involves an apparatus presenting certain improvements on those used in the processes just described which will be described in detail.

The present invention makes effective use of the highly eflicient heat transfer from hot solid bodies and preferably attrition resistant solid bodies to cooler solids. At the same time it avoids the disadvantages of mixing combustion products with the recovered oil and gases.

In the present invention the heat transmission occurs practically exclusively within the material subjected to distillation, such as oil shale, so that the distillation gases are not exposed to a subsequent and undesirable action of heat.

The present invention is directed to a novel means for retorting oil bearing shale for the purpose of extracting the vapors. External-1y heated attrition resistant solid bodies such as steel or ceramic balls are used for transferring heat to the oil shale. The invention includes the use of a stationary drum retort equipped with an internal rotating screw which contains throughout its length perforated or slotted screw flights together with baflles designed in such a way that the solid bodies or balls are retained on the screw and do not fall through the slots or perforations'but the oil shale falls through. The oil shale which is crushed by action of the heated balls upon it is fed into the top of the retort and by gravity falls down through the perforations or slots in the screw in the retort to the bottom where the carbonaceous residue or shale coke is removed and may be burned to supply heat to the external heater which in turn supplies heat to the recycled balls. The externally heated balls flow by gravity from the heater to the bottom of the retort where the rotating screw picks them up and works them to the top and out of the retort to a point where they flow by gravity back to the external heater where they are reheated and recycled to the bottom of the retort. Proper baffles are present on the screw to retain the balls in their upward movement and to prevent the balls from rolling backwards or toward the bottom of the retort. The screw can be driven by any means such as a variable-speed motor and the degree of heat transfer or contact time between the balls and the oil shale can be varied by adjustment of the speed of rotation of the screw.

The apparatus of the present invention has numerous advantages. The countercurrent flow of hot balls and oil shale provides in combination very efficient heat exchange and grinding action on the shale. The apparatus of this invention is simple to seal at the points where the screw shaft enters and leaves the retort. The apparatus lends itself to variable speed operation, thus making the degree of heat exchange easily controlled. The circulation of the balls from the retort through the external ball heating furnace and back to the retort can be accomplished all by gravity and does not require an external lifting device' such as a bucket conveyor and the like. The connections for the shale entering and leaving, the gas outlet connection and the connection for the balls entering and leaving can all be made of very simple and rigid construction because the shell of the retort does not rotate or turn.

The invention will be readily understood as this description proceeds, reference being made to the accompanying drawing wherein is depicted a specific embodiment of my invention. In the drawing the retorting vessel 1' is an inclined stationary drum equipped with a rotatable screw mounted on the shaft 2, said shaft being secured by suitable bearing and seal means at the top and bottom 3 of the retorting vessel. The screw is equipped with openings 4 which are large enough to allow the shale to fall through but small enough to retainthe balls and cross baffles 5 which carry the balls in an upwardly direction in the retorting vessel as the screw rotates. The cooled heat carrying solid bodies or balls are continuously removed from the retorting vessel and pass through conduit 6 and are heated in the external heater 7 and the heated balls pass by gravity flow 8 to the bottom of the retorting vessel and enter the retorting vessel at the opening 9. In this particular illustration the rotatable screw is driven by a driving means 10 which may contain a gear system 11 for varying the speed of rotation of the screw and the screw rotates in counter-clockwise fashion when in operation. As the hot balls are moved upwardly in the retorting vessel by action of the rotation of the screw, they come in intimate contact with downwardly moving oil-shale 12 which may be externally preheated which enters the upper portion of the retorting vessel at 13 and the shale is ground to a finer particle size and the oil is removed from the ground shale by pyrolytic action of the hot balls. The balls move upwardly by action of the screw and bafiles and the crushed shale moves downwardly as it falls through the openings. The gas and oil vapors resulting from the pyrolysis of the oil shale are removed at points 14 and the spent shale or shale coke is removed from near the bottom of the retort 15. The shale coke preferably is used as fuel and is combusted with an oxygen containing gas such as air or oxygen alone in the burner 16 which supplies heat to the external heater 7 and the flue gas from the burner escapes at 17.

Although less preferred, it is to be understood that the apparatus of this invention may also be used as a ball mill for grinding substances without heat exchange or wherein a heated gas is used as the exchange medium. In such cases the cool balls from the top of the retorting vessel are simply circulated by gravity to the ball inlet 9 thus by-passing the external heater 7 and are recycled through the retorting vessel. Such application wherein a heated gas serves as heat exchange medium and the balls serve mainly to grind the heated oil shale is more fully described and claimed in the copending US. patent application of Marlin U. Zimmerman, Jr., Ser. No. 320,451, filed Oct. 31, 1963, now abandoned.

The solid bodies which serve as heat carriers in the present invention are usually attrition resistant bodies in the form of balls, pebbles or shot of suitable size and specific gravity. The solid heat carrier may be composed of inexpensive metals such as iron, steel, aluminum, high melting lead alloys, and the like as well as refractory materials and particularly ceramic materials which have relatively large heat capacities and are not subject to oxidation or reduction. The particle sizes of the solid heat carriers usually vary from about 50 mesh to about one inch in diameter. As was stated earlier, the balls must be large enough so that they do not fall through the openings, which may be slots or perforations in the screw and it is proposed that the balls be larger than the shale particles, particularly after the shale particles have been subjected to some grinding action.

Just prior to the time it enters the distillation apparatus the oil-shale may be preheated to a temperature in the range of from about 400 to 600 F. Above approximately 600" F. pyrolysis of the shale commences.

In the pyrolysis of oil-shale, for instance, a temperature of from about 750 F. to 1800 F. and more preferably about 800 F. to about 1200 F. may be employed within the reaction zone. The pressure is not critical and may be atmospheric or a few pounds above atmospheric, in other words, sufiicient to overcome pressure drops in the system. The use of the apparatus of this invention for vacuum stripping operation is less preferred, but such use is within the scope of the present invention. It is preferred in the operation of the apparatus of this invention that the oil-shale remains resident in the reaction zone for a suflicient period of time to effect the desired conversion.

The hydrocarbon oil recovered from the shale can be further processed at the retorting site or may be shipped or pumped via pipeline to the refinery where it can then be converted to a volatile product and a tar or coke. The volatile hydrocarbons are then treated according to the customary oil refining practice and separated into various fractions, such as normally gaseous hydrocarbons, gasoline constituents, gas, oil, tar, coke and the like, as desired, The fixed carbon or coke which is left on the sand or spent shale is burnt to supply heat for the process.

While the preferred embodiment of my invention has been shown and described, it will be understood that changes and modifications may be made that lie within the skill of the art. Hence, I intend to be limited only by the appended claims.

I claim:

1. A device for the treatment of oil-bearing shales by means of the grinding action of attrition resistant solid bodies which are brought into direct contact with the shale during its operation; said device comprising a stationary cylindrical drum fixed in an inclined position; said drum containing near its top an inlet for the introduction of said shale, an outlet for the removal of gaseous products and an inlet near the bottom for the introduction of said attrition resistant solid bodies; said drum containing a centrally located rotatable shaft equipped with a screw, said shaft being secured by suitable bearing and seal means at the top and bottom of said drum; driving means for rotating said shaft; said screw being equipped with openings large enough to allow the shale to pass through and small enough to retain the solid bodies and said screw also being equipped with cross bafiies adapted to carry the solid bodies in an upward direction in the drum as the screw rotates; said drum having an outlet at the top for continuous removal of said attrition resistant solid bodies and an outlet at the bottom for continuous removal of the treated shale.

2. The device of claim 1 wherein there is an external means for transferring the attrition resistant solid bodies from the outlet at the top of the drum to the inlet near the bottom for introduction of said attrition resistant solid bodies ino the drum.

3. The device of claim 2 wherein said external means includes a heater for supplying heat to th attrition resistant solid bodies.

References Cited UNITED STATES PATENTS 843,599 2/1907 Hamrriatt 20l32 XR 2,009,122 7/1935 Reed et al 2022l8 2,984,602 5/1961 Nevens et al 201-12 FOREIGN PATENTS 848,644 9/ 1952 Germany.

MORRIS O. WOLK, Primary Examiner.

I. SCOVRONEK, Examiner.

Claims

1. A DEVICE FOR THE TREATMENT OF OIL-BEARING SHALES BY MEANS OF THE GRINDING ACTION OF ATTRITION RESISTANT SOLID BODIES WHICH ARE BROUGHT INTO DIRECT CONTACT WITH THE SHALE DURING ITS OPERATION; SAID DEVICE COMPRISING A STATIONARY DRUM CONTAINING NEAR ITS TOP AN INLET FOR THE INTRODUCTION OF SAID SHALE, AN OUTLET FOR THE REMOVAL OF GASEOUS PRODUCTS AND AN INLET NEAR THE BOTTOM FOR THE INTRODUCTION OF SAID ATTRITION REISTANT SOLID BODIES; SAID DRUM CONTAINING A CENTRALLY LOCATED ROTATABLE SHAFT EQUIPPED WITH A SCREW, SAID SHAFT BEING SECURED BY SUITABLE BEARING AND SEAL MEANS AT THE TOP AND BOTTOM OF SAID DRUM; DRIVING MEANS FOR ROTATING SAID SHAFT; SAID SCREW BEING EQUIPPED WITH OPENINGS LARGE ENOUGH TO ALLOW THE SHALE TO PASS THROUGH AND SMALL ENOUGH TO RETAIN THE SOLID BODIES AND SAID SCREW ALSO BEING EQUIPPED WITH CROSS BAFFLES ADAPTED TO CARRY THE SOLID BODIES IN AN UPWARD DIRECTION IN THE DRUM AS THE SCREW ROTATES; SAID DRUM HAVING AN OUTLET AT THE TOP FOR CONTINUOUS REMOVAL OF SAID ATTRITION RESISTANT SOLID BODIES AND AN OUTLET AT THE BOTTOME FOR CONTINUOUS REMOVAL OF THE TREATED SHALE.