Патент USA US2105526код для вставки
Jam.l 18, 1938. 2,105,526 c. P. DuBBs PROCESS OF HYDROCARBON OIL ‘CONVERSION original Filed March 23, 1925 IU «hunl|. kuìëQ Il' 2,105,525 Patented Jan. 18, 1938 UNITE STATES PATENT OFFICE 2,105,526 PRÜCESS 0F HYDROCARBON OIL CONVER SION Carbon P. Dubbs, Wilmette, Ill., assignor to Uni versal Oil Products Company, Chicago, Ill., a corporation of Delaware @riginal application March 23, 1925, Serial No. 17,516. Divided and this application Decem her 3, 1932, Serial No. 645,523. Renewed Sep ternher 17, 1936 5 Claims. (C1. 196-48) This application is a division of my application charged through the transfer line I0, in which Serial No. 17,516 filed March 23rd, 1925. This invention relates to .improvements in a method of hydrocarbon oil conversion and refers more particularly to the treatment of hydrocar bon oils under conversion temperature and a substantial super-atmospheric pressure to pro duce light fractions therefrom suitable for com mercial use. The particular embodiment of the present in vention resides in passing a stream of hydrocar bon oil through an elongated passageway, for in stance, a continuous coil, mounted in a furnace, where the oil is heated to substantially a con version temperature while being maintained un der a super-atmospheric pressure. This heated oil is then discharged into an enlarged reaction chamber, where substantial separation of the lighter fractions in the form of vapors will take 20 place, said vapors being dephlegmated, condensed and collected in a receiver as distillate. This in vention contemplates that regulated portions of said distillate are to be returned from the re ceiver to the stream of oil heated in the elon gated passageway and mixed therewith, either at the point of introduction of said stream of oil to the elongated passageway, or after said stream has passed through the elongated pas sageway and been heated and while it is being transferred to the reaction chamber. Various advantages of the invention will ap pear more fully from the following description. The single ligure in the drawing is a diagram matic flow sheet of a commercial form of ap ll.) paratus in which the process may be carried out. Referring in detail to the drawing, the raw oil is withdrawn from the supply tank I and passed through the line 2, in which is interposed the raw oil pump 3, this line 2 communicating with the lines 4 and 5. The line 4 has valve 5 interposed therein and discharges the raw oil into the top of the dephlegmator 1. Instead of discharging into the top of the dephlegmator 1, the raw oil may be passed through the line 5, in which latter is interposed the valve 8, said line 5 communicating with the inlet side of elongated passageway 9, which may comprise a continuous coil of say 3 or 4 inch pipe, mounted in a suit able furnace. The feed of raw oil may be split, that is, part may be fed directly to the dephleg mator and part directly to the inlet side of the heating coil 9, The raw oil, in its passage through the heat ing coil 9, has its temperature increased and is brought to a conversion temperature, and is dis is interposed valve II, to the upper portion of the enlarged reaction chamber I2, which reac tion chamber may be vertically disposed, as shown. The reaction chamber I2 is provided with upper and lower manholes I3 for the pur pose of cleaning, and this chamber may be insu lated if desired. In the normal operation of the process, it is preferably unheated. The lighter fractions of the heated oil being introduced 10 through the line I0 will vaporize and be dis charged from the upper portion of the reaction . chamber I2 through the vapor outlet line I4, in which is interposed valve I5, said line I4 com municating with the lower portion of the de phleginator 1. Superimposed in the interior of the dephlegmator 1 are a plurality of horizontal pans or baffles I6, which need no particular de scription, as they are standard in commercial practice. The vapors passing upwardly through 20 the dephlegmator are retarded in their travel in order to condense any of the heavier fractions. The raw oil introduced through the line 4 acts partly as a cooling medium for this purpose. The vapors remaining uncondensed after 25 coursing upwardly through the dephlegmator 1 are discharged into the vapor outlet line I1, in which is interposed valve i8, said line I1 com municating with the condenser coil I9, which, of course, is mounted in the usual condenser box, 30 not shown. The discharge end of the condenser coil has a valve 20 interposed therein and com municates with the receiver 2I, which receiver is, of course, equipped with the usual sight-glass gauges, pressure gauge, and with the incondens 35 able gas outlet 22 controlled by valve 23 and liquid discharge 24 controlled by valve 25. The unvaporized residue from the reaction chamber I2 is withdrawn through the residue drawoff line 26, in which is interposed valve 21 40 communicating with the cooling coil 28, and dis charging the cooled residue into the line 29, in which is interposed the valve 30, to a residue storage 3l. As the separation of lighter frac tions takes place within the reaction chamber I2, 45 carbon will be released and will gradually ac cumulate on the bottom and build up in the in terior of said chamber. It may then be neces sary to withdraw the unvaporized residue at various heights from the reaction chamber, and ' of course the single line 26 is purely diagram matic. Referring now to the important features of the present invention, portions of the distillate col lected in the receiver 2_I are withdrawn into the 2,105,526 2 line 32, in which is interposed valve 33, by means of the suction imposed by the pump 34, the `dis charge side of said discharge pump 34 discharg ing the distillate into the line 35. Said line 35 communicates with the receiving end of the transfer line il! by means of the connection 36, in residue unmarketable for fuel. I have discovered that by increasing the percentage of gasoline or light gravity cracked oil to the uncracked oil as it passes through the heating coil 9, and before discharging into the reactionV chamber, that this CII increased percentage of gasoline or light gravity which is interposed valve 3l, or said distillate may be by-passed through the line 38 in which is sive amount of this pitchy matter in the residue. interposed the valve 39, introducing said distil late into the stream of raw oil and reflux being passed into the inlet side of the heating coil 9.. A drain dll, having a valve 4I, may be provided ad jacent the inlet to» the coil 9. The reflux condensate produced in the de phlegmator 'l and the unvaporized raW oil are Withdrawn from the dephlegmator l through the reflux line 42, in Which is interposed Valve 43, and passed to the hot oil pump 44. The discharge side of the hot oil pump 44 discharges the mix ture of reflux condensate and unvaporized ravv oil into the line 45, in Which is interposed the valve 4t, said line 45 communicating With the line 46 going to the heating coil 9. In case it is not desirable to impose an applied pressure on the mixture of raw oil and reflux condensate be ing withdrawn through the line 42, a by-pass 4l is provided, controlled by valve 48, it being under stood that when the mixture is passed through the line 4l, valve 48 is opened and valves 43 and 30 46 closed, and vice versa. The particular utility and reasons for return ing regulated portions of the distillate from the receiver 2I and mixing said portions with the oil being heated before it is discharged into the re 35 action chamber, will be noW set forth. For illus tration, a 24° Baumé gravity fuel oil made from Mid-Continent Crude is treated in the plant and produces 30% Navy initial and end point gasoline. The capacity of the plant will be 700 barrels with 40 out the hot oil pump 44 and say 1000 barrels of raw charging stock per day with the reflux pump 44. The entire plant may be operated at 170 pounds pressure per square inch and the oil as it leaves the heating coil 9 Will be at a tempera 45 ture of say about 860° F. Sixty percent of the raw oil fed into the plant Will be converted into pressure distillate, 501% of Which pressure distillate will be gasoline and the remainder will be pressure distillate bottoms or 50 gas oil. The unvaporized portion in the reaction chamber I2 Will be a residue representing about 35% of the raw oil treated and will have a gravity of say 18° Baume. This unvaporized residue Will contain in suspension considerable 55 pitchy matter and only part of this pitchy matter held in suspension will settle out upon standing. This pitchy material seems to be in a more or less colloidal condition in the residue. From my experience, I believe that this pitchy 60 matter is made up of carbon in a very ñnely di vided state, Which carbon mechanically com bines With the heavy ends of the oil, and the combination is so strong as to resist the oil at tracted to the carbon from becoming dissolved 65 in the remainder of the oil, floating in the oil as a scum which seriously interferes With the oil being used as fuel on account of the fact this scum Will clog the pipes and burners of the fuel system. 70 Operating the plant so as to increase the yield of gasoline increases the amount of this pitchy matter, which stays in suspension in the residue, and as the residue to be marketable as fuel oil cannot lcontain over a certain amount of sedi ment, this suspended pitchy matter renders the cracked oil prevents the formation of an exces At the present time, I do not fully understand how this formation of an excessive amount of pitchy matter is prevented, but it is my opinion that part of the carbon produced from cracking unites mechanically with the heavy ends of the oil and forms a pitchy matter Which remains suspended in the oil. Therefore, that oil in 15 which the pitchy matter is suspended does not have the power to break down the at traction of the carbon to the heavy ends and cause the heavy ends to go into solution and thus 20 precipitate the carbon. I do find that When I increase the percentage of gasoline or light gravity cracked oils to the total oil flowing from the coil 9 to reaction cham ber I2, that I decrease the amount of this pitchy matter held in suspension in the oil with the car 25 bon and by regulating the increase, I can practi cally prevent any substantial amount of carbon mechanically combining with the heavy ends of the oil to form a pitchy suspended matter in the residuum. I have also discovered that the 30 amount of free carbon accumulating in the re action chamber per barrel of gasoline produced is decreased by increasing the amount of gaso line or light gravity oil Contained in the oil as it is transferred to the reaction chamber. For 35 example, an oil producing normally about 40 pounds of carbon per barrel of gasoline produced 'can be so treated as to produce only about 30 pounds of carbon per barrel of gasoline produced. As a further illustration of my invention, in 40 operating the plant there is fed 500 barrels of raw oil through the elongated heating tube 9, and at the same time there is fed 2000 barrels of re flux tothe heating tube 9, making a total of 2,500 barrels of oil passing through the tubes and discharging into the reaction chamber every 24 Of this total, 2,300 barrels Will be va ' hours. porized in the reaction chamber, passing into the dephlegmator through the vapor line Iii. Ap proximately 2,000 barrels are condensed in the . dephlegmator and returned to the heating coil 9 mixed With a fresh supply of oil, as heretofore described. The remaining 300 barreis will dis-J charge as vapor from the top of the dephlegma tor and will be collected in the pressure distillate receiving tank 2l, after being condensed in the condenser coil I9. This 300 barrels of pressure distillate contains approximately 150 barrels of gasoline, which is 30% of the 500 barrels of raw charging stock used, but is only 6% of the 2,500 (10 barrels of oil passed through the heating tube 9. In order to enrich the amount of gasoline or cracked oil to the total amount of oil passed through the heating tube 9, there are passed 500 barrels of raw charging stock and 500 barrels of reflux through the heating tube 9, making a total of 1000 barrels going through the heating tube and into the reaction chamber. Approximately 800 barrels of this amount pass to the dephleg matcr l as vapor through the line I4, 500 barrels 70 of which are condensed in the dephlegrnator and returned to the heating tube 9, mixing with an other 500 barrels of fresh charging stock. The remaining 300 barrels pass out of the top of the dephlegmator in the form of vapor and are even 2,105,526 >tually collected in the pressure distillate receiver and come out in the form of distillate, this 300 »barrels containing approximately 150 barrels of gasoline. The 200 barrels remaining unvapor ized in the reaction chamber may be withdrawn; as residue. In the above illustration, the 150 barrels of .gasoline produced comprises 30% of the raw oil treated, but is 15% of the 1000 barrels of oil passing through the heating tube 9 and into the reaction chamber i2. By comparison with the run set forth above, it will be seen that I have doubled the percentage of gasoline produced in the oil passing through the heating tube. 15 Now I can still further increase these relative percentages by passing 500 barrels of oil directly through the heating tube 9 and discharge same into the reaction chamber I2, withdrawing from said reaction chamber 200 barrels as residue and 300 barrels as vapors, which pass through the dephlegmator, all of said 300 barrels going over into the pressure distillate receiver tank, and therefore, no reñux being furnished to the oil flowing through the heating tube 9. In this case, it will be seen that the gasoline produced is not only 30% of the raw oil treated, but is 30% of the amount of the oil passed through the heating tube 9, or ?lve times the amount of gasoline com pared with the first operation above described. This latter operation, however, will cause the heating tube 9 to become seriously congested with carbon unless the pressure is increased in pro portion, which of course, makes the pressure ex tremely high. Another method oi accomplishing the same result is to feed 300 barrels of raw oil into the plant and have 700 barrels of reñux, making a total of 1,000 barrels passing through the heat ing tube 9 and discharging into the reaction chamber. One hundred barrels of unvaporized residue may be withdrawn from the reaction chamber and 900 barrels of vapors passed to the dephlegmator, of which 900 barrels '700 barrels are condensed and refiuxed back' to the heating tube 9, as heretofore described, the remaining 200 barrels discharging from the top of the de phlegmator as vapors and condensed and col lected in the pressure >distillate receiver 2l, this 200 barrels containing approximately 150 barrels of gasoline, which comprises 50% of the raw oil passed into the plant, but 15% of the total oil passed through the heating tube 9. It will be noted that this 15% is more than twice the amount produced on the basis of oil cracked, as compared with the first operation above de scribed. The plant described in the flow chart is based on the principle that at a given pressure, the 00 maximum of the cracking of oil passing through the heating tube 9 is limited below that amount of cracking that will cause a substantial deposit of carbon in the heating tube 9. This maximum can be increased to a certain extent by increas _ ing the pressure under which the plant is operat gasoline and thus avoid excessive deposits of car bon in the heating tube 9. I now seek to increase the percent of gasoline o-r similar cracked products and at the same time prevent excessive formation of pitchy matter in 5 the residue and produce less coke per barrel of gasoline produced. I have already described how this percentage of gasoline can be increased by increasing the pressure, but the amount of pres sure increase is, of course, limited, and there may be objections to high pressures. Therefore, in order not to violate any of the principles in volved in a successful operation of the cracking plant as above deñned, I have discovered that by increasing the percent of gasoline or light gravity cracked oil in the oil passing through the heating tube, these results .can be accom plished. Therefore, I add distillate or light grav ity cracked oil to the stream of heated oil which is to be discharged into the reaction chamber, either before it is passed through the heating tube 9 or after it is passed through the heating tube 9 and before discharge into the reaction chamber. Said distillate or light gravity oil is added in such proportion as to substantially pre vent the formation of pitchy matter in the resi due, and these proportions will, of course, vary, not only with the character of oil being treated, but with the manner in which the regular opera tion is carried out. 30 A by-pass 49 controlled by valve 50 is provided in the line 32 in case it is not necessary to use the pump 34, valves 5| and 52 being closed in this event. By my invention, I ñnd I am able to obtain high yields of gasoline, even when cracking fuel oil, and at the same time produce therefrom a residue containing only a very low percentage of pitchy matter in suspension, which residue is marketable for fuel. In addition, I find that there is produced less solid matter per gallon of 40 gasoline produced. It is of course, understood that the stream of distillate may be split and part introduced through the line 35 into the mixture flowing through the transfer line l0, and part being in 45 troduced through the line 38 into the mixture feeding toward the heating tube 9 through the pipe 46. I have disclosed the idea of returning portions of the pressure distillate from the receiver 2|. 50 It is, of course, obvious that the gasoline or other lighter gravity oil may be introduced from any source of supply and need not be the distillate produced in the operation. A preheater 53 having valves 54 introduced ‘ therein may be connected into the line 35, the valve 55 in line 35 being closed. The use of the preheater is, of course, optional. The operator of the plant may ñnd it desirable when treating cer tain oils under certain conditions to preheat the 60 lighter gravity oil. ’I‘he degree of heating will be governed by conditions surrounding the opera tion. In other Words, it may be advisable to pre heat the lighter gravity oil only slightly, that is, below the temperature of the oil discharging from the outlet end of the coil 9, or it may be advan ing and also the velocity at which the oil passes through the tube. Having established this prin ciple, I increase the yield of low boiling point . tageous to heat same to or just below the temper products by keeping at or below the maximum percentage of cracking in each pass of the oil through the heating tube 9 and then separate from this oil the uncracked portion, returning same to the tube for further heating, this oper ating cycle being repeated until the desired per centage of the total oil has been converted into ature at which the oil passing through the coil 9 is discharged, in order that no appreciable cool ing of the oil heated in the coil 9 will take place in the transfer line I0, and yet preventing any substantial decomposition of the lighter gravity oil such as the distillate heretofore referred to into ñxed gas. When the distillate is introduced 75 2,105,526 4 Vthrough-the pipe 38, the valve 3l being closed, the oil is preferably not preheated. Regulated portions of the lighter gravity oil may be introduced to the reaction chamber through the connecting line. 5S, valve 51 con trolling said introduction. This pipe 56 may dis charge at any height into the reaction chamber. As another method of operation, regulated por tions of the vapors discharging from the top of the dephlegmator may be diverted through the line 5S, lcontrolled by valve 59, and forced by means of pump 60 interposed in said line 58 to ' the transfer line Iû, or to any point in the heating tube 9 which may be found desirable. Vapors may be. diverted in this manner either with or without the return of -any liquid distillate and with or Without the introduction of any other lighter gravity oil in case the distillate is not utilized for this purpose. I claim as my invention: l. A cracking process which comprises passing hydrocarbon oil in a restricted stream through a heating zone and heating the same therein to cracking temperature under pressure, discharg ing the hot oil stream into an enlarged reaction zone maintained under cracking conditions of temperature and pressure, removing vapors from the reaction zone and dephlegrnating the same to condense insufficiently cracked fractions thereof, '30 returning resultant reflux condensate to the heat ing zone, combining a gasoline-containing por tion of the dephlegmated vapors with the hot oil stream discharging from the heating Zone to the reaction Zone, finally condensing the remaining portion of the dephlegrnated vapors and intro ducing a portion of the resultant distillate into the reaction zone at a point remote from the point of discharge of the hot oil stream thereinto. 2. A cracking process which comprises passing hydrocarbon oil in a restricted stream through a heating zone and heating the saine therein to cracking temperature under pressure, discharging the hot oil stream into the upper portion of an enlarged reaction zone maintained under crack ing conditions of temperature and pressure., re moving vapors from the reaction Zone and de phlegmating the same to condense insuinciently cracked fractions thereof, returning resultant re flux condensate to the heating Zone, combining a portion of the dephlegmated vapors with the hot cracking temperature under pressure, discharg ing the hot oil stream into an enlarged vertical reaction vzone maintainedv under cracking condi tions of temperature and pressure, passing the unvaporized oil downwardly through the enlarged zone and removing the same. from the lower por tion thereof, removing vapors from the reaction zone and dephlegmating the same to condense insufficiently cracked fractions thereof, subject ing the dephlegmated vapors to further condensa 10 tion to form a gasoline-containing distillate, passing a gasoline-containing portion of said dis tillate through a second heating zone and heat ing the same therein sufficiently to prevent cool ing of said hot oil discharged from the first-men tioned heating Zone upon commingling therewith, and then discharging the thus heated distillate directly into the lower portion of the reaction Zone to commingle with the unvaporized oil therein. 4. A cracking process which comprises heating hydrocarbon oil to cracking temperature under pressure while flowing in a restricted stream through a heating zone, subsequently discharg ing the heated oil into the upper portion of an enlarged separating zone and separating the same therein into vapors and unvaporized oil, fractionating the vapors to condense heavier fractions thereof and to form a gasoline-contain ing distillate, passing a gasoline-containing por- ‘ tion of said distillate through a second heating zone and heating the same therein sufficiently to prevent cooling of said heated oil upon com mingling therewith, and then discharging the thus heated distillate directly into the lower por- " tion of the separating zone to commingle with the unvaporized oil therein. 5. A method of hydrocarbon oil conversion, consisting in passing a stream of hydrocarbon oil through a continuous elongated passageway, 40 Where it is heated to a conversion temperature, maintaining a substantial super-atmospheric pressure on the oil, discharging said heated oil into an enlarged zone where substantial separa tion of lighter fractions in the form of vapors will take place, separately withdrawing the vapors and subjecting them to dephlegmation, in con densing portions of the uncondensed vapors after dephlegmation and collecting them as liquid dis tillate, returning regulated portions of the vapors oil stream discharging from the heating zone to the reaction zone, finally condensing the remain ing portion of the dephlegmated vapors and in without substantial condensation and mixing troducing a gasoline-containing portion of the' resultant distillate into the lower portion of the heated oil prior to discharge into the enlarged 55 reaction zone. 3. A cracking process which comprises passing hydrocarbon oil in a restricted stream through a heating zone and heating the same therein to them with the heated oil prior to discharge into the enlarged zone, also returning and mixing regulated portions of the liquid distillate with the zone for the purpose of increasing the percentage of lighter fractions in said oil. CARBON P. DUBBS.