US2102234A - Distillation of oil - Google Patents

Description

Dec. 14, 1937. D G BRANDT 2,102,234

DISTILLATION OF OIL Original Filed Jan. 31, 1922 F/MCT/M/AL. 35 mmoswsz-ws MIA/0V6 5.40am

Patented Dec. 14, 1937 UNITED STATES PATENT FFICE DISTILLATION OF OIL Application January 31, 1922, Serial No. 532,953

- Renewed January 14, 1928 32 Claims.

This invention relates to the distillation of oil, and more particularly to a process of and apparatus for cracking high boiling point oil distillates to obtain low boiling point distillates such as gasolene.

The major portion of all gasoline which is made today by cracking high boiling point distillates is made by treating the oil in large cylindrical batch stills. The cracking of the oil in these intermittently operated stills has been confined to the treatment of the high boiling point distillates, such as fuel oils, because the limitations of the mechanical construction, and the necessity of safe operating conditions will not permit these large stills to be operated at the high temperatures and pressures required for cracking the lower boiling point distillates such as kerosenes. When the high boiling point distillates are cracked a large amount of carbon is deposited, and if a still containing free carbon is directly heated, coke deposits are formed which require that the still must be stripped at frequent intervals to be cleaned.

An object of the present invention is to provide a process of and apparatus by which high boiling point distillates may be effectively cracked in a continuous operation.

Another object of the invention is to provide a process of and apparatus by which high boiling point distillates may be effectively cracked without being subjected to the direct contact of the furnace combustion gases.

In the preferred embodiment of the invention a high boiling point distillate is maintained in an elongated column and heated to a cracking temperature by vapors of a lower boiling point distillate, such as kerosene. The kerosene is vaporized under pressures of to 200 pounds per square inch, in order to obtain vapors at a temperature of 800 to 825 F., so that vapors at this temperature may be used for cracking the high boiling point distillate. When using low boiling point vapors for cracking high boiling point oil it is necessary that the temperature of this oil should be held above the condensing point of the vapors to prevent the gravity and boiling point of the oil from being lowered to substantially the gravity and boiling point of oil from which the vapors are formed. This may be accomplished by supplying a sufiicient quantity of vapors or by superheating a part or all of the vapors.

Accordingly, another object of the invention is to provide a process of cracking high boiling point 'distillates by heating them under pressure to a cracking temperature with a vapor of a lower boiling point distillate.

The use of a vapor heating medium in the present invention permits a high boiling point distillate to be cracked without applying heat direct- W to the still in which it is cracked.

With this in view, another object of the invention is to provide a process of and apparatus by which a high boiling point oil may be cracked by heating it to the cracking temperature with vapors of an oil which can be vaporized under pressure without depositing substantial amounts of carbon in the heater. With these and other objects and features in View, the invention consists in the process of and apparatus for cracking oil hereinafter described and particularly defined in the claims.

In the accompanying drawing is diagrammatically illustrated an apparatus in which the preferred form of the invention may be carried out.

To carry out the process outlined above in the apparatus shown in the drawing, a high boiling point hydrocarbon oil, such as fuel oil, is supplied through a pipe [0 to a pump l2 and forced through a pipe I4 into a series of fractional condensers I6. The high boiling point oil is preheated in the fractional condensers l6, and passes from the condensers through a pipe l8into the upper end of a cracking still 20. The oil introduced into the upper end of the still overflows from a series of trays 22 where it acts to scrub vapors rising from the main body of oil within the cracking chamber. The volume of oil introduced upon the trays 22 is preferably controlled to hold back the high boiling point fractions of the vapors, so that they may be returned to the body of the oil in the still to again be cracked.

To carry on the cracking operation within the still 29, a lower boiling point hydrocarbon oil, such as kerosene, is supplied through a pipe 24 to a pump 26 and forcedthrough a pipe 28 into the upper portion of a dephlegmating section 30 of a tower 32. The kerosene or low boiling point hydrocarbon overflows over a series of hoods 34 where it acts to scrub vapors leaving the cracking chamber 20 and introduced into the dephlegmator through a pipe 36. By this scrubbing action hydrocarbon vapors of a lower boiler point than those condensed in the upper end of the still 20 are held back and preferably these vapors have substantially the boiling point of the kerosene introduced by the pump 26. The kerosene and condensate which reaches the bottom 38 of the dephlegmating section 30 pass out through a g pipe 40 to a pump-i2, by which they are forced through a pipe coil 44 positioned within a furnace 46. The oil enters the pipe coil 44' at the bottom'or the coolest portion of the heating chamber and its temperature is gradually in:- creased as it flows throughtheacoil; The oil and vapor leaving the coil pass through a pipe 48 and are discharged into 'the'upper portion of a separator 59 formed within thetower 32. The. vapors separated from the oil rise to the top of the separating chamber 50 and pass out through a pipe 5| by which they are introduced into the lower portion of the cracking still 20. The vapors introduced into the bottom of the cracking still pass in'a circuitous path, around a series of distributing baffles 54, which causes the oil and vapors to have a long path of contact to assist in heating the high. boiling point oil andto aid'in cracking the high boiling point oil.

When the kerosene passes through the coil 44 practically all of it is vaporized, and if this vapor is depended upon to maintain the oil in the cracking still 20 at its cracking temperature it is necessary to circulate a'very large volume of vapors through the body of'oil to maintain its temperature sufficiently'high to prevent the va- 5 porsfrom, being condensed therein; If the vapors are'condensed', the gravity andboiling point of the oil will be lowered to substantially the same as the gravity and boiling point oi the kerosene, so that the cracking operation will be seriously interfered with. To avoid. the use of an ,excess volume of kerosene vapors'a portion or all of thevapors may be removed from the .cham- 1 ber 50through aplpe 52, and passed through a sup'erheating' coil '53, positioned above tile in the roof of .thefurnace 46. From the coil 53, the

superheated vapors pass through 'afpipe 55 -which connects with the pipe 5I'. A valve 56 positioned in the pipe 5| may be used to control the amount of vapor passing through the super heating coil and the pipe 5|. A valve 51 positioned in the pipe 52 may be used to cut off the circulation of vapors through the pipe 52 and coil 53. The coil '53 is of comparatively small size-and vapors can be circulated through the coil at. such a high rate that substantially no 7 carbon will be depositedtherein. If carbon trouble is encountered in the coil 53, steam may be introduced into the coil through an injector 58 which will effectively prevent the formation of carbon in the coil; It is preferred, however, to

avoid the use of steam if possible.

The oil which is separated from the vapors in 1 the "separator, .50 flows downwardly through a pressure seal tube 59 andcollectsin a reservoir 60 formed between the outer surface of the tube ,andvthe innersurface of the tower 32. The tube 59 extends downwardlyinthetower 32 a considerable distance vertically below the connection of the pipe'5l with the cracking chamber 20 whereby a suflicient liquid head will be maintained the separator to force the gas from the separator into the bottom of the crackingchamber. The, oilwhich accumulates in the reservoir .60. flows through an outlet 6| to the pipe 40 to circulated, along with the low boiling point oilccming from the dephlegmating chamber .30,

' through the heating coil 44.

.Asoutlined above, the vapors set free in the cracking chamber 20 .are first scrubbed by the highboiling point 'oiladvancing to the cracking chamber and are next scrubbed by the kerosene or lower boiling point oil which is passing to the pipe'still- 44. 7 By these two scrubbing operations 2,102,234 v V V a large portion of the high boiling point fractions is removed from the vapors. The remaining portion of the high boiling point fractions is removed by means of a steam boiler condenser 82, forming the upper end of the tower 32. Some of the vapors in a condenser 62 are condensed by within a chamber 64 surrounding a series of tubes 66 which-pass through tube sheets 68 and 10 positioned at opposite ends of the chamber .64. ,Water is continuously introduced into the chamber 64 through an inlet'iZ, and steam is continumeans of water or steamvwhich are positioned ously removed from the chamber by means of an outlet, 14%. To vary the boiling point of the vapors leaving the condenser 62 a series of tubes.

15 are telescopically mounted within the tubes 66 and may be adjusted vertically by means of" a screw 18 operated by a motor 80. By vertically adjusting the tubes 16 the area of the tubes 66 in contact with the vapors may be varied to vary the condensing effect on the vapors. V

The vapors leaving the condenser are fractionally condensed by a heat interchange with the high boiling point. oil. advancing to the cracking still 20, and any desired. number of fractions may be recovered. When treating heavy, distillates such as fuel oiland' gas oil it is desirable that the fractional condensers shall sepa-' rate from the vapors all constituents except the 62 pass through .a pipe 82 to the first 'of the fractional. condensers I6. -In the condensers IS the vapors vapors which should be condensed as agasoline I cut. Accordingly, the vapors leaving the last con-i a pipe 92 and the condensate is removed through a pipe 94. If it is desired to use several of the' fractionalcondensers I 6 for condensing the gasolene fractions, a pressure reducing valve maybe i placed in any of the vaporlines 95 connecting the adjacentcondensers. The condensate recovered in the condenser l6 passes downwardly into traps 96 and may be collectedin a header '98 and returned through a'pipe I00 to the pump 26, to be again'circulated through the dephlegmatorand V pipe still. In case some 'of the condensers IBare used for condensing a gasoline fraction, or any desired distillate, suitable valves'and piping connections with the trapsfSEare providedwhereby the desired fractions may be separately collected.

The high boiling point distillates such as fueloil and gas oil are more unstable than the lower 7 boiling point distillates, such as kerosene, and the higher boiling point fractions can be cracked V or decomposed at much lower temperatures and pressures than the lower boiling point distillates. The high boiling point distillates, moreover, de

"posit carbon quite rapidly when subjected tohighl temperatures. This deposition of carbon greatly hinders the cracking operation and has practically limited, heretofore,.the cracking of oilito an" intermittent operation to permit the still to be strippedperiodically, to becleaned. In accordance with the example given above of the present invention, the fuel oil'isheatedto a cracking temperature within the still 20 by vapors of the kero sene which are heated in the. pipe still to a temperature. sufliciently high to crack fuel -oil;

Pressures of approximately to 200 pounds per square-inch, depending upon the character and quality of the oil, are maintained within the pipe still, and at those pressures the kerosene will vaporize at temperatures sufiiciently-high to crack gas oil and fuel oil without depositing carbon within the pipes of the pipe still 44. Both the sensible heat and heat of vaporization of the kerosene vapors are available for maintaining a cracking temperature of the high boiling point oil and'by superheating the vapors the temperatureof the oil may be accurately controlled.

When fuel oil is cracked, any carbon which is deposited in the still will float in the oil and gradually work its way to the bottom of the still and will not be formed into a hard coke because the still 20 is not subjected to direct heat of combustion gases. The agitation of oil in the still 20 by the vapors circulated therethrough will assist in carrying the carbon around the baflles 54, and permit it to pass into a collecting chamber I04.

The carbon and the heavy oil residuum which collect in the chamber I 04 may be intermittently withdrawn to prevent the oil in the cracking chamber from becoming so heavy as to interfere with the proper cracking operation. To accomplish this, a sludge pot or still I06 is connected by means of a pipe I08 with the lower portion of the still 20. A valve H0 is positioned in the line I08 and is normally closed during the operation of the cracking still. When a sufiicient volume of the residuum has accumulated in the chamber I04, the valve I I0 is opened to allow the. pressure within the cracking still 20 to blow the residuum out of the chamber I04. While the residuum is being forced into the still I06, a valve I I2 in a residue draw-off is closed and a valve II t in a vapor line H6 is closed. After the residuum has been removed from the chamber I04 the. valve H0 is closed and the vapor line valve H4 is opened to reduce the pressure in the still to substantially atmospheric pressure. In the still Ififi the superheat of the oil residuum derived from previously heating the oil under high pressure will cause an evaporation of the lighter fractions of the oil residuum, and these vapors are condensed in a condenser IIB. Preferably the condensate recovered in the condenser IIB is returned through a line I20 to the fuel oil pump I2 to be again returned to the cracking still '20.

, After the residuum has been evaporated in the still I06 it is withdrawn through the outlet valve I I2 and may be passed, if desired, through a heat interchanger for preheating kerosene which is advancing to the pump 26.

In the normal operation of the process a very small amount of kerosene will be introduced into the apparatus through the pipe 24, due to the fact that a large amount of the kerosene or lower boiling point distillate is formed in cracking the heavy oil in the still 20, and these fractions are removed from the vapors leaving the still in the dephlegmator 30, the condenser 62 and the condensers I6, and returned to the kerosene circuit in the dephlegmator 30. The continued circulation i of the kerosene from the separator through the 5 H2 and H4 of the still I06 are closed, and a valve .ber 60 increases substantially above the normal specific gravity of the kerosene being vaporized, the oil from the chamber may be periodically transferred from the chamber 60 to the cracking still 20. To accomplish this a pipe connection I26 between the line 40 and the cracking still 20 is provided with a valve I28 by which oil may be introduced from the chamber 60 into the top of the cracking chamber. To transfer the oil from the chamber 80 to the cracking chamber a valve I in the kerosene line is closed, a valve I32 in the kerosene vapor line is closed, and valve I 28 is opened. Thereupon the vapor pressure in the separator will force oil from the chamber through the outlet 6 I, line 40 and line I26 into the cracking chamber. When sufficient oil has been removed from the chamber 60 so that the addition of kerosene thereto will lower its specific gravity to the desired point, the valve I28 is closed and the valves I30 and I32 are opened to continue the normal operation.

To secure the most eihcient operation in the cracking chamber, it is necessary that the volume and temperature of the kerosene or low boiling point oil vapor which is introduced into the cracking chamber shall be sufficient to maintain the temperature of the oil in the cracking chamber at such a pointthat substantially no oil vapors of the specific gravity or boiling point of the kerosene will be condensed in the oil bodies. If the kerosene vapors are superheated the amount of vapors required for heating the oil body may be decreased. Therefore, by controlling the amount of vapors being superheated the amount of raw kerosene being introduced and temperature in the condensers may be controlled.

Although the invention has been described as a process for cracking fuel oil by heating the oil with kerosene vapors, the invention is not limited to the use of these two constitutents. For example, fuel oil may be cracked by vapors of gas oil or gas oil may be cracked by the vapors of the kerosene. When gas oil is vaporized to crack fuel oil the pressures which are used in the pipe still and the cracking still are not so high as when kerosene is vaporized for cracking either gas oil or fuel oil. Further, when kerosene vapors are used for cracking gas oil, the temperatures and pressures maintained in the pipe still and the cracking still are higher than when kerosene vapors are used for cracking fuel oil.

The details of construction of the pipe still and furnace are not specifically claimed in this application. The furnace 46 comprises a combustion chamber I34 in which oil or gas are ignited and burned and the gases from the chamber I34 pass around a bafile I36 into a heating chamber I33. The upper end of the chamber I 38 receives the highest temperature gases so that the'upper coils of the pipe still 54 are subjected to the highest temperatures. As the gases pass between the pipe coils they are gradually cooled so that the lower coils of the pipe still are subjected to the lowest temperature. The combustion gases leaving'the chamber I38 pass through a flue I40 to a chimney'l42.

- The drawing only diagrammatically illustrates,

the apparatus and it is to be'understood'that the; cracking stillZB, the dephlegmating section 30 and the separating'section of the tower 32, and

the pipes and 48 may be 'well insulated to preserve the heat in the oil circulating through this apparatus. Also, insulation may be provided for the residuum still I06 and pipes I08 and I22.

Furthen'the pump 42 would be one'of the approved forms of hot oil pumps.v 7

The-preferred form of the invention having been thus described; what is claimed as new is:

1. A process of cracking high boiling hydrocarbon oils to form low boilinghydrocarbon oils 'body of oil.

comprising maintaining a firstbody of oil of high boiling point, maintaining a second body-of oil of lower boiling point, circulating oil from said second body through a heater and returning it 7 to said second'body; separating vapors from the heated: oil and passing them through the first V 2. A process of cracking drocarbon oils which comprises maintaining a body of high boiling point oil under superatmospheric pressure and at crackingternperature in anexternally unheated enlarged cracking zone,

vaporizing a portionof a body of lower boiling point oil, separating the vapors formed, super,-

heating the separated vapors and cracking the higher boiling point oil in said body'by passing therethrough in intimate contact saidsuperheated vapors. I V V V 7 V I 3. A process of cracking high boiling point hydrocarbon oils to form low boiling point hydrocarbon oils, comprising maintaining a firstbody of high boiling 'point oil,maintaining a second body of oil of lower boiling point, circulating oil from the second body through a heater and returning it to the said second body, separating vapors from the heated oil, superheating the vapors and passing them throughthe first body of oil. 7

4. A process of cracking high boiling point hy-' drocarbon oils to form low boiling point hydro carbon oils comprising maintaining a body of oil 7 of high boiling point, maintaining a second body of oil of lower boiling point, circulating oil from said second body through a heater and return ing it to the said second body; separating'vapors from the heated'oil, injecting steam into the vapors and passing them through a superheater and heated oil, and passing them through the first body, and scrubbing vapors leaving the first body with the lowerboilingpoint oil.

6. A process of cracking high boiling point hydrocarbons to form lows-boiling point hydrocarbons comprising maintaining a first body of oil of high boiling point, maintaining a second body of, oilof lower boiling point, circulating oil from said second body through a heater andreturning it to the said second body, separating vapors from the heated oil and passing them through the first body, and scrubbing vapors turned in the first body with fresh incoming high high boiling pointhyboiling point oil to hold back the major portion of the condensates having aboiling point higher than that of the lower boiling point oil.

'7. A process of cracking high boiling point hydrocarbons to form low boiling point hydrocar bons comprising maintaining a first body of oil of high boiling point, maintaining a secondbody of oil of lower boiling pointrcirc'ulating oil from" said second body through a, heater and returning it to the said secondbqdmseparating;vapors from the heated oil and passing them through the first body, scrubbing vapors formed in the first 1 body with fresh incoming high boiling point oil" 7 to hold back condensates having a boiling point higher than the low boiling point oil, and further scrubbing the remaining vapors with fresh in.-' 7

coming" lower boiling [point oil to' condense a further portion of said vapors.

8. A process of cracking high boiling point hydrocarbons to form low ,boilingpoint'hydrocarbons comprising maintaining a first body of jail of high boiling point, maintaining a second body of oil of lower boiling point, circulating oil fro 7 said second body through a heater and returning" it to the said second body, separating vapors from the heated oil and passing them through the first body, and periodically transferring .toth

first body high'b oiling'po'int oil accumulating in V the second body. v 7 r V a V 9. A process of cracking high boiling'point hydrocarbons to form low boiling point hydrocarbons comprising maintaining a first body of high boiling pointroil; maintaining a second body 01' lower boiling point oil, circulating oil from'said second" body through a heater and returning it to the said second body, separating vapors from the heated oil, and passing-them through the first body of oil, condensing vapors leaving the V first body and withdrawing heavy residuum from A 'the-firstbodyh V e V '10. A process of cracking high boiling point hydrocarbons to form low'boiling point hydrocar bons comprising maintaining a first body of high boiling point oil, maintaining a'second body of. lower boiling point oil, circulating oil' from said second body through a heater, and returning it to the said second body, separating vapors from the heated oil and passing them through the first body, and intermittently withdrawing heavy residual oil from both bodies." V i 11. A process of cracking'hig'h boiling point carbons comprising maintaining a first body of high boiling point oil, maintaining a second body of lower boiling point oil,'circulating oil from said second body through a heater and returning it to the said second body, separating vapors from the heated oil, and passing them through the first body, withdrawing the heavy residuum from the first body, distilling the residuum, and returning condensate obtained therefrom to the first body. I I

' hydrocarbons to form low boiling point hydro 7 12. A'process of cracking high boiling point'j,

hydrocarbons to form'low boiling point'hydro-f carbons comprising maintaining a first body of high boiling point oil under pressure, main:

taining a second body of lower boiling point oilunder pressure, circulating oil from said secl a 70.

0nd body through a heater and returningit to the said second body, separating vapors from the heated oiland passing them through the first body, Withdrawing heavy residuum accumulating in the said oil bodies, reducing the pressure'of the residuum and distilling the sameby virtue. 6f 75:

its superheat and returning the resulting condensate to the first body.

13. A process of cracking high boiling point hydrocarbons to form low boiling point hydrocarbons comprising maintaining a first body of high boiling point oil under sufiiciently high pressure for cracking, maintaining a second body of lower boiling point oil, vaporizing oil of the second body under pressure, and passing the vapors through said first body, continuously supplying the high boiling point oil to said first body and the lower boiling point oil to be vaporized, and periodically transferring oil from the second body to the first body.

14. A process of cracking high boiling point hydrocarbons to form low boiling point hydrocarbons which comprises maintaining a first body of high boiling point oil under pressure, maintaining a second body of lower boiling pointoil under pressure, continuously supplying high and. low boiling point oils to their respective bodies, vaporizing oil of the second body and forcing the vapors through the first body, condensing vapors leaving the first body, and preheating the oil supplied to both said bodies by vapors leaving the first body. 1

15. A process of cracking high boiling point hydrocarbons to form low boiling point hydrocarbons comprising maintaining a first body of high boiling point oil under pressure, maintaining a second body of lower boiling point oil under pressure, continuously supplying high and low boilingpoint oils to their respective bodies, vaporizing oil of the second body and forcing the vapors through the first body, scrubbing vapors leaving the first body with oil advancing to both of the said bodies, and preheating the high boilingpoint oil advancing to the first body by a heat interchange with vapors from the first body.

16. A process of cracking heavy hydrocarbons to form low boiling point hydrocarbons therefrom comprising maintaining a first body of high boiling point distillate under pressure, maintaining a second body of lower boiling point distillate under pressure, vaporizing oil of the second body at a temperature sufliciently high to. crack oil of the first body and passing the vapors through the first body, fractionally condensing vapors leaving the first body under pressure, returning a higher boiling point fraction to the first body, and passing a lower boiling point fraction to be vaporized with oil of the second body.

17. An oil distilling apparatus comprising a cracking still, a separator, means for introducing oil into said still, a heater, means for circulating oil in a closed circuit from the separator through the heater and return, means for introducing oil into the closed circuit, means for conducting vapors from the separator to the cracking still, a dephlegmator connected to the still, means for conducting condensate from the dephlegmator directly to the heater, and a condenser connected with the dephlegmator.

18. An oil distilling apparatus comprising a cracking still, a separator, means for introducing oil into the still, a heater, means for circulating oil in a closed circuit from the separator through the heater and return, means for introducing oil into the closed circuit, a vapor connection between the upper portion of the separator and the lower portion of the still, a vapor sealing leg in said separator extending vertically below the point of vapor connection with the still, and a condenser connected with the still.

19. An oil distilling apparatus comprising a cracking still, a separator, means for introducing oil into the still, a heater, means for circulating oil in a closed circuit from the separator to the heater and return, means for introducing oil into the closed circuit, means for conducting vapors from the separator to the cracking still, a liquid scrubbing condenser in the upper portion of the still, a dephlegmator having a vapor connection with the still, means for conductingcondensate from the dephlegmator to the separator, and a fractional condenser connected with the dephlegmator.

20. An oil distilling apparatus comprising a cracking still, a separator, means for introducing oil into the still, a heater, means for circulating oil in a closed circuit from the separator through the heater and return, means for introducing oil into the closed circuit, means for conducting vapors from the separator to the crack-' ing still, a dephlegmator and a series of surface condensers connected in succession with the still, and means for returning condensates from the dephlegmator and condensers to the separator.

21. An oil distilling apparatus comprising a cracking still, a separator, means for introducing oil into the still, a heater, means for circulating oil in a closed circuit between the separator and the heater, means for introducing oil into the closed circuit, a vapor line for conducting vapors from the separator to the lower portion of the still, a pipe connection between the upper portion of the still and the separator, valves in the vapor line and pipe connections by which,oil maybe transferred from the separator to the still.

22. An oil distilling apparatus comprising a cracking still, a separator, a heater, means for circulating oil in aclosed circuit between the separator and the heater, means for introducing vapors from the separator'into the still, means for introducing oil into the still, means for scrubbing vapors formed in the still with the incoming oil, a dephlegmator connected with the still, means for introducing oil into the dephlegmator, means for scrubbing vapors passing through the dephlegmator with oil introduced therein, means for conducting oil and condensate from the de- .phlegmator into said closed oil circuit, and a condenser connected with the dephlegmator.

23. In the process of cracking petroleum oils, in which a reflux condensate is produced from cracked vapors and a distillate is produced from cracking still residuum, the improvement which comprises introducing said distillate into a cracking chamber Where a body of oil is maintained at a cracking temperature, vaporizing said condensate, heating the vapors to a temperature substantially higher than the oil of said body in a separate zone, andintroducing the result ing vapors while at a high temperature into said chamber to heat and crack said distillate.

24. In the process of cracking petroleum oils, in which a reflux condensate is produced from cracked vapors and a distillate is produced from cracking still residuum, the improvement which comprises introducing said distillate into a cracking chamber where a body of oil is maintained at a cracking temperature, independently vaporizing and superheating said condensate, and using the resulting highly heated vapors as the sole heating means, to heat and crack said distillate.

25. In the process of cracking petroleum oils, in which a reflux condensate is produced from cracked vapors and a distillate is produced from cracking still residuum, the improvement which comprises heating said distillate and introducing 1 'it into a'cracking chamber where a body of oil is maintained at a crackingtemperature, independently heating said condensate to a temper- 1 ature substantially above that maintained in said chamber, mingling the vapors produced-from said operations, and fractionally condensing the combined vapors from said heating and cracking operations to produce said'condensate.

26. The proc'essof cracking hydrocarbon oils,

V which comprises heating reflux condensate to a high temperature under pressure and passing the resulting products into an enlarged chamber where a body of oil is maintained, withdrawing and distilling residuum from said chamber, separately heating the resulting residuum distillate and introducing'it into a separate cracking chamher where a body of oil is heated and maintained at a cracking temperature, and passing vapors from said chambers into a reflux condensing zone to produce said refluxco'ndensate.

V 127. The-process 'of i cracking petroleum oils, which comprises maintaining a' body of oil in a chamber at a high temperature under superatmospheric pressur passingoil from said chamber through a heater and returning the heated products to said chamber, passing residuum from said chamber into a vaporizer maintained under a lower pres's'urethan saidgchamber, thereby to vaporize portions" ofsaid residuum by the heat contained therein, removing vapors from said vai porizer, producing a condensate therefrom, introducing the condensate into a separate cracking :zone where itis subjected to crackingconditions of temperature and pressure, removing vapors fromsaid cracking zone to a vapor fractionating 1 zone in which a reflux condensate is produced,

.and introducingat least aportion-of said reflux condensate into said heater. V a

28. An oil heating apparatus comprisinga fur nace having a fire chamber and a tube chamber separated fromthe fire chamber by'a'bridge wall 7 [over which heating gasesifrom the fire chamber I enter the tube chamber at the top 'and h'avin'g an outlet for heating gases at the bottom'of the tube chamber, a bank of horizontally 'disposed tubesin said tube chamber, an external tank, a

circulating pump and connections between said tubes, pump, and tank-, whereby1the pump forces oil from the tank successively through tubes at successively. higher levelsin said tube bank and thence backinto the chamber, I

29. An oil treating apparatus, comprising a pipe still in which the oil to be treated is subjectedto heat while in liquid phase, a separating chamber into which the oil from said pipe stillis discharged for separation of vapors from -unvaporized oil constituents, a superheater in' which the vapors from said separatorare subjected to a high temperaturewhile in vapor phase, means for heating the vapors in the, superheater to a a high temperature with products of combust ion,

and means for utilizing the same products ot combustion which are used for heating the vapors in the superheater at a high temperature ior heating the oil in the pipe still at a lower tem perature.

30. An oil distilling apparatus comprising a plurality of enlarged chambers adapted to contain bodies of oiL'apipe still heater, means' for conducting oil from one of said chambersthrough said heater wherein the oil is heated to a high temperatureand thenback to said chamber, sepa,

rate means forconducting vapors and liquid from said chamber into the body of oil maintainedin a second chamber in which said vapors are used for heating the oil therein, and means for introducing fresh oil charging stock into-said second chamber.

31. A process of cracking petroleum oils, which comprises maintaining a' plurality of bodiesoi oil under a superatmospheric pressure'and at, a high temperature, passing oil at av superatmospheric pressure from one, of said bodies through'a heating zone'wherein'theoil is heated t'o'ahigh tem-" perature, separating vapors produced Tin I said;

heating zone from unvaporized oilconstituents,

passingunvaporized oil constituents from said heating zone directly into the body 01 011 from which they were withdrawn, contacting the vapors from said heatingzone with the oil inaseparate body of said pluralityv of bodiesto heatand crack portions thereof, producing a reflux condensate a heater, means for circulating oil in aolosed patnfr'om'the separator throughthe heater and 7 back to the separator, means forintroducingloil.

into said closed path, means for s'uperheating V vapors from said separator and m introducing the resulting superheated vapors into the body of oil in said still,'a condenser connectedwiththe stillQand means for withdrawing residuum from the still. r V

= DAVID G. BRANDT.

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