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June 2l, 1938. c. B. FORWARD 2,121,026 PROCESS FOR REFININGHAND CONVERTING OILS- Filed May 5, 1932 à , mw «,t2u5m.: un-DWAI' *3:45am :05. Mm‘ZOn INVENTOR BY CHAUNCEY ß‘ FORWARD 2,121,026 Patented June 21, 1938 ` UNITED STATES PATENT OFFICE » 2,121,026 Pnocnss Fon REFINIITS; AND coNvEn'rINc o ` - Chauncey B. Forward, Urbana, Ohio, assignor, by mesne assignments, to Forward Process Company, Dover, Del., a corporation of Dela Application May 5, 1932, Serial No. 609,405 5 Claims. (Cl. 196-61) 'I'he present invention relates to the cracking of hydrocarbon oils in the vapor phase. More particularly the invention relates to an improved process for converting crude petroleum or high boiling point distillates thereof into synthetic gasoline or other low-boiling point distillates. The present process is a continuation in part of the inventions disclosed in my copending ap plications for patent, Serial No. 682,477, ñled De 10 cember 24, 1923, and. Serial No. 330,490, ñled October 13, 1919, now Patent No. 1,903,810 granted April 18th, 1933. Prior application Serial No. 330,490 filed in 1919 discloses a process for cracking petroleum 15 oils containing heavy residues in which the oil was passed through coil sections mounted in pre heaters and heated to a temperature suflicient to vaporize a substantial proportion of the oil. The resulting vapors and unvaporized oil constituents 20 Were then discharged into a vapor liquid sepa rator in which the heavy residual constituents were separated from vapors. The vapors were then passed at high pressure through a plurality of coil sections and heated to a high cracking 25 temperature to convert the oil constituents into a very high percentage of gasoline or motor fuel out in the carbon settling column and the re maining vapors conducted to the heat exchanger for preheating the oil stock to be cracked. The vapors were fractionated to recover a gasoline produced in the cracking operation. A pressure of from 200 to 500 poundsvper square inch was maintained in the enlarged carbon settling col umn. 'I'he primary object of the present invention is to provide a method of converting high boiling 10 oil to lower boiling products in a manner yield ing a high percentage of high quality product Without production of substantial amounts of low grade liquid and solid residue. To accomplish this object, the principal fea 15 ture of the invention contemplates the treat ment of the crude petroleum or other high-boil ing oil and vapors thereof, in a continuously and rapidly flowing stream of relatively small cross section, to the successive steps of:r preheating; 20 vaporization under pressure; separation of any unvaporized liquid; exposure of the iiowing va por stream under high pressure to cracking tem peratures for a period lof time suiiicient to effect substantial cracking while passing the vapor 25 stream through the cracking zone at a velocity content and a relatively small proportion 01E at which formation and deposition of coke or free carbon. The stream of vapors from the sludge in the cracking zone is prevented. Any cracking coils was passed at high velocity into an ' free carbon formed is deposited at the discharge 30 30 enlarged chamber in which the free carbon was end of the cracking zone in a dry, flulfy form; separated from the vapors. The vapors from separation of such carbon from the cracked gas the carbon separating chamber Wereconducted to a condensing system in which the desired gas oline product was recovered. Prior application Serial No. 682,477 discloses a process for cracking hydrocarbon oils, partic ularly distillates, which are completely Vaporiz able, by passing the distillate through a vapor heat exchanger in heat exchange with high tem 40 perature vapors produced in the cracking oper ation. The preheated oil was then conducted through a plurality of heating coils and brought to a temperature of approximately 850° F. after 35 which it was passed through a further series of 45 coils Where cracking was effected at temperatures of approximately 975° F. The oil vapors passing through the cracking coils were converted into a substantial proportion of gasoline and a rel atively small proportion of free carbon. The 50 resulting mixture was conducted from the crack ing coil into an enlarged carbon settling column Where a temperature of from 850° to 900° F. was maintained solely by the heat of the vapors in troduced into the column in which some further 55 cracking occurs. The free carbon was settled oline vapors being accomplished by simple grav ity settling in a carbon collecting chamber through whichl the cracked vapors pass at re tarded velocity before entering the first element 35 of the cooling and condensing train. Other ob jects and features of the invention will be appar ent from the following description. In the accompanying drawing I have shown in diagram apparatus adapted for the practice of 40 the process of the present invention. As illustrated in the accompanying drawing, the crude petroleum or high boiling oil distil late to be treated is forced under high pressure by'a pump I0 through preheating coils I2 with 45 in a hot vapor heat exchanger I4. After passing through the heat exchanger land therein becom ing preheated to a temperature of about 300° 400" F., the oil passes under‘pressure through a pipe I6 into the iirst of a connected series of 50 coils I8 of pipe of small diameter and great length. The first pipe coil I8 is mounted in the first member 20 of a connected series of heat ing, vaporizing and cracking chambers 20, 22, 24, 26, 28, 30, 32, 34, 36 and V38. After flowing 55 2 2,121,026 through coils I8 in chamber 20 the oil continues its flow successively and uninterruptedly through similar coils I8 mounted in each of the cham bers 22, 24, 26, 28 and 30. In passing succes sively through the coils of heat exchanger I4 and the ñrst few heating chambers 20 to 30, the oil is gradually heated to a temperature of Vapor heat exchanger I4, where they are cooled by direct heat exchange with the crude forced through the coils thereof by pump I0. High boiling point oils are separated from the cracked vapors by condensing in exchanger I4, and the lower boiling point cracked gasoline vapors pass out of the exchanger through a valved pipe 54 about 850° F., so that all of the gasoline and and are conducted through the coils of a con higher boiling point components of the oil are . denser 56 and thence through a train of con 10 vaporized, leaving only a small amount of the heaviest ends of the oil in an unvaporized liquid state. After passing through the coils I8 of chambers 20 to 30, the mixture of oil and vapors is discharged, still under high pressure and tem perature, into a separatoi` 40. Due to the de crease in velocity of flow of the oil and vapor mixture through the enlargedv cross section of the separator 40, gravity separation of the un vaporized liquid residue from the major vapor 20 ized fraction of the oil takes place therein prior to the subjection of the vapors to substantial cracking. Anyliquid residue collected at the bottom of separator 40 is continuously discharged through 25 valved pipe 42 and conducted to a cooler 44, and thence to a storage tank 46. The oil vapors are conducted from the top of separator 40 by a continuation of coiled tubing I8 in a rapidly flowing stream successively through the coils of densing and reiining apparatus (not shown). The oil vapors in separator 40 are maintained under high pressure and at a temperature up to 800° F. to 850° F. The cracked oil vapors enter ing the carbon settling column 50 are maintained preferably under pressures of 400 to 500 pounds 15 or higher and temperatures of 960° F. to 980° F. The temperature of the vapors drops during their sojourn in chamber 50 to about 850° F. to 900° F. The dry, fluiîy carbon which `collects in pre 20 cipitator 50 gradually accumulates and may be periodically removed through a relatively large valved pipe 58 to a second sealing chamber 60. From chamber 60 the carbon may be removed while the plant is operating without danger of 25 lire, through a manhole 62, during periods when communication between chamber 00 and pre cipitator 50 is cut off by closingr valved con nection 58. All of the heating chambers, heat 30 the vapor phase cracking zone of the apparatus exchangers, separators, and pipes conveying and 30 in heating chambers 32, 34, 3S and 38. In this holding the steam, hot oil and vapors are thor oughly insulated against heat losses with as bestos or other suitable heat insulating material. Heating of the crude oil and vapors passing successively through the tube coils I8 of cham 35 bers 20 to 38 may be effected by indirect heat exchange with superheated steam or hot fur cracking zone the vapors are further heated under high pressure, (i. e., 200 to 500 pounds per square inch or more) to temperatures of 35 950 to 1000° F. Y The cracked vapors issuing from the last chamber 38 of the cracking zone are conducted by a continuation of tubing I8, still under high pressure and temperature, through a valved in 40 let 48 into a carbon settling chamber 50. In chamber 50 the velocity of flow of the cracked oil vapors is reduced to a point where gravity separation takes place of the cracked vapors and any carbon formed in the cracking Zone. 45 The drop in velocity flow of the vapor stream re sults from the relatively large cross section of the chamber 50 as compared to the small cross section of the coils I8 of the vaporizing and cracking elements. The relatively small amount 50 of carbon formed as a decomposition product of nace gases passed successively in reverse direc tion to the flow of crude and vapors, through chambers 38 to 20 inclusive. When superheated 40 steam is used as a heating medium, it is prefer ably generated in coils 64 of a flash boiler 66 to which feed water is continuously fed by a high pressure feed pump 68. Superheated steam at a temperature of 1150° F. to 1200° F. or higher 45 and under a pressure above 250 pounds, is con ducted from the boiler directly to manifolds 70, thence through the chambers 32--38 forming the cracking zone of the apparatus. After pass ing through chambers 32-38 the steam is con the cracking operations in accordance with the present process is notable for having uniformly ducted successively through the chambers 30--20 forming the preheating and vaporizing zone, dry and finely powdered íiuiîy characteristics, from the ñrst element 20 of which the steam ñnally exhausts at a pressure of 100-200 pounds resembling carbon black. 55 The process contemplates high Velocity of flow of the oil vapors through the cracking tubes of 50 per square inch into a drum 'I2 having a valved 55 offtake ‘54. The temperature of the steam in the apparatus,--i. e~ through the coils I8 of chamber 30 is maintained at about 850° F. to chambers 32 to 38 inclusive, and a prolonged 900° F., and the temperature of the steam in time of exposure of the vapors to cracking tem drum 'I2 is normally maintained at about 400° 60 peratures in the chambers 32 to 38 and in the F., or in other words at a temperature at which 60 settling chamber 50, so that no deposition of it is still suitable for use in industrial heating coke or sludge takes place at any point in the' and for power purposes. cracking tubes. The above-noted character Valves are mounted at suitable points in the istics of the carbon residue of the cracking op pipe connections wherewith to regulate and 65 eration of the present process result apparently maintain the proper Working pressures in the 05 :from the controlled differential conditions of oil preheating, vaporizing and cracking Zones. rapid turbulent flow of vapors and prolonged Likewise valved pipe connections are provided time of exposure of vapors to cracking tempera between the boiler or equivalent source of heat tures and pressures in apparatus of the type, and ing fluid and the separators whereby to permit with the small dimensioned cracking tubes of preliminary heating of these apparatus elements 70 great length, illustrated in the accompanying drawing. From the carbon precipitator 50 the cracked vapors pass out at a temperature of about 850° 75 F. to 900° F. through valved pipe 5,2 into the in starting operations. Valved pipe connection 'I6 between chamber 60 and condenser 56 serves to release the small amount of vapors accumulat ing under pressure in chamber 60 periodically as a result of blowing carbon thereinto from the 2; 11e-1,0262' . carbonsettiingxcolurnn; ‘Manhoie 1'4la1iords'in- the‘liquidlstat‘ethrough an elongatedîzone 0f re-` spection ofthe interior of .the carbon settling stricted. cross sectionfat high velocity whereby chamber'. » » - ' ` " A small amount of vapor phase crackingr may ` take place `in the coil- section I8À mounted in vaporizing chamber 30, but the major portion ofthe cracking takes place in the coils of the cracking. zone `(chambers 32-38» inclusive) and in' carbon settling column- 50". The heavy oil taken off from the bottomy of> 10 heat exchanger IÍ4 throughvalved offtake '18, as well as that taken oif from the bottom of sep arator 40, carries substantially no free carbon in solution and accordingly is in a condition 15 where it can be put through the process again, either by itself or blended with some of the cru-de ` or distillate originally run. all components are maintained in intimate ad mixture and gradually superheating the vapors thereinto a temperature in excess of 950 degrees F., discharging the superheated vapors into an enlarged zone' wherein the velocity -of said vapors is reduced, maintaining the temperature of the vapors in said enlarged zone above the cracking temperature and controlling the time of exposure 10 ofv said vapors t'ol'the cracking treatment.` inthe last mentioned elongated heating zone and in said enlarged zone so as to permit the precipita tion of only substantially dry carbon in said enlarged zone. ' 15 3. 'I'he process of cracking mineral oils which comprises passing the oil constituents to be cracked while substantially all in vapor state and at an initial temperature of about 800° to 850° F. in a confined stream and at high velocity 20 through a heating and cracking zone, heating The lower 3 to 5 rows of pipe in the flash boiler may be made of specially treated tubing 20 or calorized pipe which will withstand several hundred degrees higher vtemperature than ordi nary steel tubing without oxidizing. Since no direct heating of the oil pipes by ñre or llame perature of approximately 1000° F. and effecting is used in this process there is no excess localized 25 heating of the oil. By reason of that fact, and substantial conversion of said vapors in said zone,passing the resulting highly heated vapors into an 25 the oil vapors of said stream to a cracking tem the speed of travel of oil and vapors through the enlarged externally unheated digesting zone in relatively small pipes composing the cracking which the vapors are maintained at a cracking coils, no Ideposit of coke or carbon occurs in them and the pipes are never fouled on that ac 30 count and are as clean at the close of a run of temperature solely by the heat from the vapors passed into said enlarged zone, maintaining a any length‘of time as they were at the start, thus permitting continuous operation with no loss of time or expense to clean out the coils. The temperatures and pressure specified both 35 may vary considerably according to the grade or kind of oil being run through the apparatus at Likewise the character of cracked products obtained may be affected considerably ` the time. ` by variation of the rate of iiow of oil and vapors 40 through the system, as well as by the temper atures and pressure obtaining in the cracking zone. The temperatures and pressures claimed are those which practice has found to be approx imately average when treating Mid-Continent 45 oils but it will be understood that the method could still be operated to advantage commercially » at higher or lower temperatures and pressures than those specifically stated above. The invention having been thus described, 50 what is claimed as new is: 1. The process of refining and converting oil herein described, consisting in preheating a con tinuously flowing stream of oil gradually and under high pressure, in heating this preheated oil 55 to a higher temperature while under high pres sure and separating the vapors and residue while under high but decreased pressure and prior to substantial cracking, in further gradually heat ing a rapidly flowing stream of said vapors at pressure of from 200 to 500 lbs. per square inch in 30 said zones, maintaining the heating and cracking conditions in said Zones such that a substantial portion of said vapors are’converted to constitu ents suitable as motor fuel, precipitating sub stantially dry carbon from the vapors in said en larged zone by decreasing the velocity of the vapors introduced thereinto from said heating and cracking Zone,> passing the resulting cracked vapors from said enlarged zone, and recovering a condensate suitable as a motor fuel from the 40 vapors passed from said enlarged zone. 4. The process of cracking mineral oils which comprises passing the oil constituents to be cracked While substantially all in vapor phase in a confined stream and at high velocity 45 through a heating and cracking zone, heating the oil vapors of said stream to a cracking tem perature of from 950° to 1000° F. and effecting substantial conversion of said vapor stream to lower boiling constituents in said zone, passing the resulting highly heated vapors into an en larged digesting zone, passing the introduced vapors through said enlarged Zone at a relatively reduced velocity in substantially unobstructed flow and precipitating therein only substantially ' dry carbon present or formed in the vapors intro duced into said enlarged digesting Zone, main taining a superatmospheric pressure in said zones of two hundred pounds per square inch 60 a temperature in excess of 950° F. and under i and maintaining the vapors in said zones a suf 60 taining them at cracking pressures and tem flcient length of time to convert a substantial portion thereof to constituents suitable as motor fuel, passing the resulting cracked vapors fromÍ said enlarged zone, and recovering a condensate suitable as a motor fuel from the vapors passed 65 from said enlarged Zone. 5. The process of converting mineral oil into peratures. lower-boiling products, which comprises subject high pressure to crack them in the vapor phase by maintaining a forced circulation of a fluid heating medium in indirect heat exchanging re lation therewith, and in subsequently precipitat 65 ing substantially dry carbon from the vapors by decreasing the speed of the vapors while main 2. In a process of converting oil, comprising ing mineral oil traveling in a stream of rela 70 heating a rapidly flowing stream of oil of re-; tively small thickness to heat at temperatures 70 below that at which substantial cracking takes , stricted cross section to a temperature in excess of 750° F. and separating the vapors generated place but sufñciently high to vaporize a desired portion of said oil while leaving heavy constitu thereby from unvaporized oil without substan ents of the oil as liquid commingled with the tial cracking, passing the separated vapors sub stantially free from hydrocarbon constituents in vapors, separating such liquid from the vapors, 75 4 2,121,026 passing said'vapors at high velocity through a heated coi1 and heating the vapors therein until ditional cracking substantially only by the super heat of said vapors passing said vapors through a substantial proportion thereof has been con said chamber slowly enough to permit separation verted into lower boilingl point constituents, of any carbon formed by the cracking to occur maintaining the conditions of velocity and tem and precipitating only substantially dry carbon perature in said heated coil such that no sub stantial deposition of carbon occurs from the from the vapors introduced into said enlarged chamber by the decrease in velocity of the va pors passed therethrough, and recovering a rela heating of the vapors therein, discharging the vapors into an enlarged chamber wherein the temperature is below that maintained in said coil but is maintained suf?ciently high to effect ad tively loW boiling condensate from the cracked vapors. ‘ . CHAUNCEY B. FORWARD.