US2285276A - Shale oil distillation - Google Patents

Description

- June 2, 1942. c. E.' HEMMINGER' A2,285?76 SHALE oIL DIS'LILLATIONl Filed Nov. 24, 1939 ou. lsf/Az.: Malv- 22 www@ OOLEK 2f? -c JDE/PP/N l a Patented June 2, 1942 OFFICE SHALE OIL DISTILLATIONV Charles E. Hemminger, Westfield; N. J., assignor to Standard OiiDevelopment Company, a corporation oi' Delaware Application November 24,1939, Serial No. 305,899

(cl. 2oz-15) lOlaim.

The present inventionl relates to the recovery of oill from shales and the like. The invention 4is particularly directed to an improved process in which oilvbearing shales are heated quickly and the oil removed from the solid material with a minimum of destructive pyrolysis. In accordance with the present invention, -oil-bearing shales are powdered, suspended in a stream of gas,` passed through externally red tubes and then handled in a manner to recover the distilled oil. It is well known in the art to recover oils from solid oil-bearing materials, particularly to recover petroleum oils from petroleum oil-bearing shales. The recovery of the `oil from the oilbearing material may be accomplished by suspending the solid material in a liquid medium and then raising the same to distillinggtemperatures. These processes have not been Aentirely satisfactory since the liquid medium constitutes a rather large heat reservoir which prohibits raising the temperature of the oil readily and quickly to distilling temperatures. Other procsses treat relatively large solid particles. This is notentirely desirable since a considerable time may be readily and efiiciently recovered from oilbearing solid substances. My process overcomes l, previous inherent diiiiculties present in processes employed for the removal and recovery of oils ii'oi'nl shales and the like, and permits a maxirecovery ,of the oils with a minimum de-v composition of the same.

'I'he process of my invention may be readily understood by reference to the attached drawing illustrating one modification of the same. Oil shale is introduced into grinder or crushing unit I by means of line 2 which may comprise any suitable belt or equivalent conveyor. The shale in unit I is powdered to the desired extent and Y then passed to bin- 3 by means of line 4. The powdered shale is withdrawn from bin 3 by means of screw conveyor 5 and passed to mixer 6 in which the powdered `oil shale contacts hot suspension gases which are introduced into mixer 6 by means of line These gases are heated to any desired extent by means of heating unit 'I'. The colloidal suspension of powdered oil shale in suspension gases iswithdrawn from mixer 6 by means ofline B, passed through heat exchanger 9 and then passed through externally tired tubes I Il in furnace II. The heated mixture is withdrawn from furnace II by means oi.' line 'I2 and introduced into a cyclone Vor equivalent separator I3. The solid material is subjected to stripping by superheated steam which is introduced into stripping unit I5 by means of line I6. It is to be understood that super-heated recycled vapors may also be utilized as a stripping medium. The solid material free of oil iswithdrawn from stripping unit I5 by means of line II and handled in any manner desirable. A preferred modificationof the present invention is to introduce the hot stripped shale into burning unit I9 and to introduce a suiiicient quantity of air by means of line 35 to completely burn the carbonaceous material from the shale. The hot shale is then preferably passed through heat exchanger 9 in which the burned shale will raise the temperature of oil shale in suspension gases. The spent oil shade may then be withdrawn from the system by means of line I9 vand disposed of in any desirable manner. The suspension gases and distilled oils are removed from cyclone separator I3 by means of line 20 and combined with stripped oils'and stripping gases which are removed from stripping unit I5 by means of line 2l. The entire vaporous mixture is then passed through cooler 22 and introduced into fractionating unit 23 in which the stripping gases are separated from the recovered oils. The stripping gases and suspension gases are removed overhead from distillation unit 23 by means of line 24, while the condensed distilled oils are removed by means of line 25 and handled in any manner desirable. A modification of the present invention is to treat the condensed oils removed by means of line 25 in a manner to form relatively higher and relatively lower boiling fractions.-

gases. lnace is so adjusted that the suspension gases for the recovery of oils from any solid substance f and is particularly directed to the recovery of petroleum oils from petroleum oil-bearing shales.

An essential feature of the present invention is that the oil-bearing shales are powdered and suspended in suspension gases which permits a ready and rapid increase in temperature and minimizes anytendency of the oil vapors to be overcracked. The extent to which the oil shale is powdered may vary somewhat, depending upon the particular oil shale being treated, the oil concentration, as well as upon other operating conditions. In general, the oil shale is powdered in the range from 100 to 500 mesh. It is preferred that the oil shale be powdered so that more than 50% will pass through a 300 mesh screen.

-The powdered oil shale is mixed with a sunlcient quantity of suspension gases so that a deslrable suspension of the powdered shale in the gases is secured. -In general, approximately 8 pounds to 10 pounds of powdered shale per cubic foot of suspension gases is satisfactory. The suspension gases employed likewise may vary considerably and may comprise any inert gas which maybe readily separated from the oil and which will not enter inw the reaction, as for example, nitrogen, recycled or light hydrocarbon gases, or similar gases. However, ingeneral, it

is preferred to employ super-heated steam. The

temperature of the suspension'gases likewise may vary considerably. In general, the temperature of the suspension gases should be in the range from about 100 F. to 1500o F., preferably in the range from about 1000 F. to 1200 F. The suspension gases containing the powdered oil shale are preferably preheated before introducing the same into the furnace in which the temperature is finally brought up to the distilling range. The prehating operation of the gases is preferably secured in the manner described, i. e.. by burning the carbonaceous material from the spent oil shale.

The velocity of the suspension gases is sumcient so that substantially no precipitation of ,the

oil shale occurs prior to the cyclone separator. In-general, the velocity is in the range from 10 feet to 50 feet per second. The temperature maintained in furnace I I- will depend upon the character of the powdered shale, the oil content of the shale, the volume of suspension gases used, as well as upon the velocity of the suspension In general, the temperature in the furcontaining the oil shale are removed from the furnace at a temperature from about 800 F. to 1100o F., preferably in the range above 900 F.

The length of time the suspension of oil shale is maintained at' this Vdistllling temperature will likewise depend upon the above enumerated factors. In general, the oil shale is maintained under distilling conditions for a time period not exceeding about 50 seconds, in which a moderate temperature in the range of about 900 F. to l000 F. is employed. When employing these temperatures, it is preferred that the time the oil shale is exposed to distillation conditions not exceed about 25 seconds. The relatively short time period is an essential feature which is permitted by the method of recovery of the present invention. 4The oil is substantially fully recovered when distilled in accordance with the present invention, and the short time period in which the oils are maintained under distillation conditions substantially eliminates the tendency of the oil to deterio'rate into undesirable products.

In general, the gases removed from the furnace 4 are under apressure from about 2 pounds to 50 using a non-liquid medium. a better separation l is secured between the solidv shale and the separated oils. Another distinct material improvement secured by the present process is that the powdered shale is suspended in a vapor such as steam or recycled gas so that the vaporization is aided by a low partial pressure over the shale and the cracking occurs in the vapor phase.

'I'he process of the present invention is not to be limited by any theory or mode of operation, but only in and by the following claim in which it is desired to claim all novelty in so far as the prior art permits'.

I claim:

Process for the recovery of oils from oil-bearing shales comprising powdering said shale in a manner-that more than-50% of the shale will pass through 300 mesh screen, suspending the same in inert suspension gases, heating the same as a confined stream to a temperature in the range from about 800 F. to 1100 F., maintaining the suspension gas containing the powdered shale at this temperature for a time period not exceeding about 25 seconds. removing the gaseous mixture comprising suspension gases and distilled oils from the spent shale, separating the distilled oils from the suspension gases without Y substantially cooling vthe mixture so that a dry separation is eiected, burning the carbonaceous materials from said spent shale and handling the same in heat exchanging equipment to preheat the suspension gases containing the powdered shale.

.CHARLES E. HEMMI'NGER.

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