US2073622A - Process and apparatus for refining mineral oils - Google Patents

Description

March 16, 1937 D. G. BRANDT PROCESS AND APPARATUS FOR REFINING MINERAL OILS Original Filed July 23. 1926 INVENTOR OAVI D BRANDT ATTORN EY UNITED. STATES PATENT OFFICE PROCESS AND APPARATUS Foe REFINING MINERAL OILS David G. Brandt, Westfield, N. J., assignor to Doherty Research Company, New York, N. Y., a corporation of Delaware Original application July 23, 1926, Serial No. 124,320. Divided and this application January 30, 1934, Serial No. 708,935-

13 Claims.

The present inventionrelates to the cracking of heavier hydrocarbons to obtain lighter hydrocarbons therefrom and more particularly to obtain from gas oil or like material a finished motor spirit or gasoline. The invention of the present application is an improvement upon my prior applications Serial No. 710,996 and Serial No.

654,532, (now Patent No. 1,872,879), filed May 5th, 1924 and July 30th, 1923, respectively. The

present application is a division of pending application Serial No. 124,320, filed July 23rd, 1926. In my said prior applications, I have disclosed a process and apparatus for the pressure distillation of relatively heavy hydrocarbons to obtain pressure benzine therefrom, said prior applications disclosing passing charging stock of the character of gas oil, or the like into a. crack ing chamber. A mixture of hydrocarbons is then Withdrawn from the cracking. chamber and forced through a pipe still or heating coil where the mixture is heated to cracking temperature.

From the pipe still the heated oil is discharged into a separating chamber wherein the liquids and vapors separate and both the liquids and vapors are taken from said separator into a vertical cracking chamber in which the vapors are passed in counter-current relation to the liquids while still at cracking temperature and under pressure to complete the cracking reaction.

Vapors from said cracking chamber are passed through a dephlegmator, the reflux from which is run back into the cracking chamber and uncondensed gases and vapors from which are passed through a pressure controlling and reducing valve and thence to a condenser. My prior application Serial No. 532,954, filed January 31st,

1922, (Patent No. 1,784,087), discloses also drawing off heavy liquid from the bottom or lower portions of said cracking chamber and relieving pressure thereon to permit the heat contained in the liquid so drawn off to drive over a pressure distillate which is condensed, the residuum liquid resulting after the passing off of said distillate being used for fuel or other purposes.

Certain objects of the present invention are improving the results obtained from my said prior processes and apparatus by controlling the circulation of the liquids in said vertical cracking chamber to prevent the mixing of the feed with the liquid from the separator within the cracking chamber proper; to obtain a finished gasoline from a cracking plant; and to conserve and return to the process part of the heat formerly lost in the residuum drawoif,

A further obect of the invention is to provide a process and apparatus suitable for effective rectification and fractionation of mineral oil va- The figure is an elevational View, partly dia,

grammatic in character, of an apparatus adapted to operate in accordance with the method or process of the present invention and including the novel features hereinafter described and claimed.

In the apparatus illustrated in the drawing,

, raw charging stock, preferably gas oil, is brought in through pipe 2 to the feed pump 4 and thence forced through pipes 6 and 8 to the upper portion of atower It combining the functions of a heat exchanger, a bubble cap tower and a dephlegmator. l2 at the top of the tower Ill and the oil thereupon passes through a coil or heat exchanger I i within chamber [2 and thence through coils ma lb, Me, and Hid, in the chambers [2a, I21), I20, and I2d arranged below the chamber I2 in the tower Iii and in the order mentioned in going from the top to the bottom of the tower. The chambers l2, I211, I21), I20, and I2d inclusive, and if desired others of like character not illustrated, comprise the bubble-cap or tray section of the tower I!) through which reflux passes. downwardly from one chamber to the other and vapors pass upwardly as indicated by arrows in counterfiow to the reflux in a wellknown manner, this type of apparatus being so well-known that the details of the bubble caps are omitted from the drawing. It will be seen that the bubble cap section of the tower l0 according to the present invention differs from the standard bubble cap apparatus primarily in that the chambers of the individual trays of the bubble cap section of tower l0 include coils M, Ma, Mb, I40, hid in contact with the vapors in the chambers and through which the ingoing charging stock passes in series, these coils thereby acting as heat exchangers, heating the ingoing stock at the same time that they condense a portion of the rising and outgoing vapors to increase the reflux condensate normally formed in such apparatus. Below the chamber [2d, tower 10 com.- prises two or more dephlegmating chambers 16,

The pipe 8 enters a chamber thru which vapors pass in series on their way to the bubble cap section of the tower l0. Owing to the character of chamber IS the bottom l5 of chamber l2d is not of the bubble-cap type but is perforated substantially uniformly to act as distributor for reflux liquid passing down thru it. Chambers l6 are partly filled with fragments I8 of glass, coke or other inert material to increase the dephlegmating effect. The lumps of fragments 18 rest on horizontal perforated partitions supported within tower ID at the lower ends of the chambers 16. vLower chamber it, contains also coil 26 through which the charging stock passes after leaving the coil 14d previously mentioned, coil 20 having the same function as the coils l4, l4a, etc. in the upper portion of tower l0. Directly below the lower chamber [6 is a chamber Ilia in which is mounted a coil 20a similar to and connected in series with the coil 20. The stock being charged into the apparatus through coils l4, etc. 20 and 20a is discharged into the chamber IGa where it is mixed with reflux flowing down into chamber l6a from upper chambers in the tower Ill as well as with that formed in chamber [6a. The bottom of the chamber I 6a is formed of two perforated plates spaced apart, the space being filled with fragmentary material it of the type referred to above. This arrangement causes intimate contact over an extended area, of the vapors entering and the liquids leaving the tower l0.

The dephlegmating tower H] preferably is set on top of a heat insulated cracking chamber 24, there being a frusto-conical plate 26 at the bottom of tower l0 and separating the tower from the cracking chamber 24. The plate or partition 26 has a central aperture 28 through which reflux condensate from the tower discharges into the cracking chamber. Charging stock after passing through the coil 20a and mixing with reflux in chamber I Go is discharged downward centrally through the opening 28 into the cracking chamber along with the reflux condensate.

. The cracking chamber 24 contains a considerable body of material which has been either cracked previously or is undergoing cracking and, according to the present invention, it is desired to prevent the reflux from tower l0 and the charging stock from mixing immediately with such material in chamber 24 until the material in the chamber has substantially completed the cracking action obtainable without reheating. According to the present invention therefore, a central conduit 30 of large dimension is set vertically beneath the aperture 28 to receive the reflux and charging stock coming down through the aperture. Preferably conduit 3i! carries at its upper end funnel-shaped mouth 32 for receiving the reflux and charging stock and guiding it into the conduit 30. Below the chamber 24 and spaced therefrom by a diaphragm 34 is a mixing chamber 36 and conduit 38 extends through the diaphragm 34 so as to conduct the mixed reflux and charging stock through chamber 24 and into the mixing chamber 36 before the charging stock and reflux can mix with the material from chamber 24. Material which has undergone cracking in chamber 24 passes from the lower end of said chamber into the mixing chamber 36 through pipes 38, 38. The mixture of reflux, charging stock and previously cracked material, in the proportions of about 60% previously cracked stock to 20% fresh stock and 20% reflux, is taken out of chamber 36 through pipe 49, returned to the system and forced by pump 42 through pipe 44 to a pipe still or heating coil 48 contained in the furnace 48. Any gas oil obtained as described below by separating it from liquid taken out of chamber 24 is included in the 20% fresh stock just mentioned. Ordinarily, the liquid passing through coils Ha, I 41), etc. in tower I0 is only 10% of the liquid entering pipe-still 40 from pump 42 and is seldom more than 20%. In most aspects however, the present invention is independent of the ratio between the liquid flowing through coils I411, I412, etc. and that pumped into pipe-still 46. In the coil 46, the oil is heated to between 750 and 900 F. under considerable pressure, and discharged through pipe 50 to the upper portion of the separator 52. Vapors from separator 52 pass out of the top of the separator through pipe 54 which passes through the side of the cracking chamber 24 and discharges into a distributor 56 near the bottom of the cracking chamber. Liquids entering the separator 52 pass to the lower portion of the separator through the interior of conduit 58 and the majority of these liquids leave the separator through a pipe 60 which passes through the side of the chamber 24 somewhat above the mid-level of the liquids therein and discharges directly into the chamber. The liquid discharged from pipe 60 thereupon works its way downwardly through the chamber 24 while undergoing further cracking and in a general way countercurrent to the vapors and gases discharged from the distributor 56. The majority of the liquids flowing downwardly in the chamber 24 as just mentioned and remaining unvaporized, passes through the pipes 38, 38 into the mixing chamber 36.

It-has been found that the cracking reaction is one requiring an appreciable amount of time in which to complete itself. If the cracking reaction initiated by a given heating of the oil has not been permitted to complete itself before the oil is returned to the cracking coil, the oil which has not completed its cracking from a previous heating is almost sure to crack in the pipe still when returned thereto. The cracking of the oil in the pipe still is undesirable, not only because of the carbon which may thereby be deposited in the pipe still, but because of poor utilization of the heat imparted to the oil if the cracking has not been completed in the chamber 24. The capacity of the separator chamber 52 is preferably made such that the oil is held in chamber 52 until it is conditioned, or about to crack, before being transferred to chamber 24. The oil as introduced into chamber 24 being about to crack, the contact of the hot oil with the hot gases coming from the top of separator 52 and distributed through the oil in chamber 24 by the distributor 56 produces a rapid cracking action in the chamber 24. Moreover, the distributor 56 being adjacent the outlet from chamber 24 any oil leaving this chamber must come into contact with the hottest gases, thus insuring that any molecule of the oil which has absorbed enough heat in coil 46 to be chemically unstable will crack before leaving chamber 24. The heat delivered to the oil in the pipe still is therefore effectively utilized in chambers 52 and 24 and very high firing rates can be applied to the pipe still without depositing an objectionable amount of carbon in the coil 46. The capacity of the apparatus is therefore very high for a given area of heating surface in the coil 46. In addition to the advantages just discussed,

the gases and vapors delivered to the lower part of chamber 24 by the distributor 56 and rising through the liquid in the chamber strip out of the liquid undergoing cracking in the chamber substantially all of the gasoline-like material in this chamber.

fore prompted to a maximum degree owing to the substantial absence of any gasoline-like material in the feed to the still. In this connection, experience has shown that a partial pressure of gasoline in material being heated-to cracking temperature correspondingly reduces the amount of gasoline formed by a given heating.

It is necessary that a certain amount of'liquid be withdrawn from the cracking still, not only to prevent the liquid level in the apparatus from becoming too high but also to maintain the proper quality of the liquid in the. cracking circuit foroptimum conditions of operation. I have found that processes and apparatus employing a cracking circuit according to my said prior applications are operated with a minimum of difficulty while at the same time giving large yields of gasoline when substantially no free carbon can be detected in the liquid in the chamber 24. This is not to be taken to mean that no carbon forms in chamber 24, as the metal surfaces within this chamber which are exposed to the hot oil accumulate a layer of crystalline carbon, the metalseemingly catalyzing the separation of carbon from the liquid undergoing cracking. Nevertheless the liquid itself within the chamber 24, under the conditions desired accordingto the present invention, contains practlcallylno free carbon.

In order to maintain the desired condition of the liquid as to free carbon which has just been mentioned, the shell of chamber 24 moveover is tapped slightly above diaphragm 34 and an outlet pipe 62 connected into the shell at this level through which residuum may be drawn off at the rate desired from the chamber 24, the flow of liquid through pipe 62 being regulated by valve 64.

It is observed, moreover, in order to maintain the optimum operating conditions in the cracking circuit that some of the heavy residuum should be withdrawn from the bottom of the separator 52. out of the bottom of separator 52; pipe 63 connected with the pipe 62 through which residuum is taken from chamber 24. t 7

While, according to the present invention, it is desired to prevent the formation of free carbon mixed with the liquid in the chamber 24, the presence of a small amount of free carbon in the liquid taken out of the bottom of separator 52 through pipe 63 is not harmful. As a general rule, the oil passing through pipe 62 to the concentrator is made up of about 60% of material taken from the bottom of the cracking chamber 24 and about 40% of material from the separator 52 although all of it may be withdrawn from 24 Pipe 62 delivers liquid into chamber 66 in the bottom of a concentrator 68. The pressure in concentrator 68 is substantially reduced as compared to that in the chamber 24 and gasoline and gas oil contained in the liquid entering chamber 66 are thereby permitted to evaporate under the reduced pressure and due to the heat contained in the incoming liquid itself.

For instance, if chamber 24 is at 250 lbs. gage pressure, concentrator 68 is operated at about 50 lbs. gage to give a certain gravity to the residuum The formation of gasoline-like material in the oil heated in pipe still 46 is there- 'tor 68.

For this purpose, the valved pipe 63 is led withdrawn from chamber '66. The proper pressure to holdxin chamber 66, therefore, varies with the pressure and temperature in chamber 24' as wellas with the grade of residuum or fuel oil desired. Moreover, when a fuel oil is desired of a gravity heavier than that readily obtainable merely by reduction ofpressure under the conditions prevailing at a given time, steam or gas maybe introduced into the lower part of chamber 66 to assist vaporizing liquid in this chamber. Vapors formed in chamber 66 pass out of the chamber through the opening 16 in the diaphragm 12 which forms the top of the chamber 56. The vapors from opening 10 pass into a bubble cap tower comprising chambers 14, 14a, 14b and 140 in the upper part of the concentra- The bubble cap portion of the concentrator comprises bubble cap sections or trays which may be of standard or other preferred design and the details of which are not illustrated.

It will be understood, however, that the vapors pass up through chambers 14, Ma, 14b and 140, the heavy vapors being condensed and flowing as a reflux back into chamber 14.. To assist in the formation of reflux and to prevent any vapors heavier thangasoline from passing out of concentrator 68, a cooling coil 16 is placed in the top of the chamber 140. Gasoline vapors passing the coil 16 are taken out of the top of the concentrator 68 through pipe 18 and passed thence through condenser 86 to suitable storage tanks. Reflux condensate, however, formed in bubble cap sections 14, 14a, 14b and 140, is not permitted to flow back into chamber 66 at the bottom of the concentrator 68, but, owing to the form given the diaphragm l2, and the outlet iii therethrough, it is trapped in the lower portion of the chamber 14 from which the condensate, consisting principally of gas oil may be drawn out through pipe 82 and forced by pump 84 back through pipe 86 intothe mixing chamber 36 mentioned above. By the arrangement and method just described, much of the heat of the residuum drawn from the bottoms of chambers 25 and 52 may be returned to the cracking circuit with the gas oil'or the the lower part of chamber 24 which enters the chamber 66 and which does not vaporize at the pressure and temperature in chamber is taken out of the lower part of this chamber through pipe 88 and passes through a cooler 90 from which it is taken to suitable storage. This liquid is a fuel oil.

In the operation of valve 64 and the valve in pipe 63 to admit liquid into chamber 66 from the cracking chamber 24, and the separating chamber 52, it is preferred that the valves be opened to their fullest extent whenever liquid is to be passed through them and closed tight again as soon as the desired amount of liquid has been withdrawn through them. I have found that this way sticking of valve 64 and of the valve in pipe 63 is avoided. When these valves are only cracked open to permit the desired amount of liquid to' vapors are dephlegmated, the clephlegmating tion due to the outer surface of tower in being assisted both by the cooling of the vapors by the coils I4, Ida, Mb, I40, Md, 20 and 20a previously mentioned and by pumping a volatile liquid such as gasoline into the chamber I2 of tower I0. The design and arrangement of the coils, I4, Ma, Mb, I 4d, 20, and 20a is such that the dephlegmating action is least in the section of tower I0 in which the vapor temperature is highest and is increased by steps to the section or chamber of the tower I0 in which the vapor temperature is lowest. It will be seen, moreover, that the increase in dephlegmating effect in the direction of decreasing temperatures in tower I0, in other words, in the direction of flow of the vapors being dephlegmated, is as specifically disclosed, a product of three factors; namely, the increasing area of the coil 20a, 20 etc. in the direction of flow of thevapors, the decreasing temperature of the raw liquid in the coils 20a, 20, etc. and the volatile liquid injected into the uppermost chamber I 2 of tower I0. By thus graduating the dephlegmating effect and increasing it in the direction of flow of the gases, the temperature at the lower or hotter end of tower I0 may be at a maximum temperature, with minimum of reflux at this point, thus producing optimum conditions for the escape of gasoline from the cracking chamber 24 both as to temperature and as to reduction of mechanical entanglement of gasoline vapors in the reflux. The temperature at the upper end of tower I0 is, however, maintained such that no vapors heavier than those of commercial gasoline pass out of tower I0, and I am thus enabled to produce commercial or end-point gasoline direct from the vapors of a cracking chamber without rerunning the distillate to eliminate heavy ends as is now the practice.

Of course it is impossible to maintain an absolutely constant rate of cracking in chamber 24. The dephlegmating effect of tower I 0 must therefore be varied to produce the desired end point gasoline. The variation of the cooling effect in tower I0 required by variations in the rate of cracking in the chamber 24 is obtained by varying the amount of gasoline pumped back into the chamber I2.

It has been found pomible to attain the desired results as to the temperature in the tower I0 and particularly in the upper end thereof by automatically controlling the speed of the pump I06 which returns gasoline to the tower in accordance with the temperature of the vapors passing from the tower to the condenser. A satisfactory method and arrangement for operating pump I00 in accordance with the temperature of the vapors in tower Iii is disclosed in my prior application No. 654,532, filed July 30, 1923. However, I do not limit myself to automatic control of pump I00 as this pump may be controlled by hand within the present invention. lhese vapors pass through an oiftake pipe 2, containing a pressure-maintaining valve I00, valve I00 preferably being in duplicate so that one may be used if the other is out of order. It has been found moreover according to the present invention, that maintaining the temperature in the top of the tower I0 at the point producing by condensation a given end point gasoline from the vapors which have passed therefrom, also automatically maintains the pressure in the dephlegmator I 0 substantially constant and avoids the necessity of adjusting the valve I00 during the normal operation of the apparatus. Maintaining a constant pressure in tower Iii also of course automatically maintains substantially constant pressures throughout the other parts of the apparatus.

Vapors not condensed in dephlegmator I 0 pass out of the top thereof through pipe 92 to condensers 04, 96 and 98 mounted in a cooling tower 99 through which vapors pass in series. Intermediate tower I0 and condenser 94, the pressure is reduced by controlling valve I00 previously mentioned. Condenser 94 is the first condenser through which vapors from pipe 92 pass. Gasoline condensed in condenser 94 passes through pipe I02 containing a cooler I03 to a container I04. Vapors uncondensed in the condenser 94 then pass through the condenser 96 and finally through condenser 98. Condensate from condenser 96 passes through a pipe I08 containing a cooler I09 to container I I0 and vapors, condensate and gases from condenser 98 pass through pipe II2 to container IIO. Uncondensed gases and vapors pass off from the receiving tank or container IIO through pipe II I. Gas or vapors from container I04 also may pass through pipe II6 into the top of container H0 and thence off through pipe I I4. Pipe II4 may lead to burners or to other means for utilizing the gas and uncondensed vapors. Preferably the gas in pipe I I4 is scrubbed for gasoline before being utilized. Gasoline from tank H0 is run to gasoline storage through pipe II8, the flow through pipe II8 being conveniently regulated by an automatic valve I20 operated by a float in chamber I22.

As mentioned above, the satisfactory control of the dephlegmating eifect in tower I0 and more particularly the control of the dephlegmating effect in the top chamber of the dephlegmator has been found to be best achieved by introducing into chamber I2 a varying amount of gasoline of the end point itis desired to make in the apparatus. For this purpose a pump I 06 is provided whose intake is connected by pipe I23 with the tank I04. Pump I06 forces gasoline received by it from pipe I23 into chamber I2 through pipe I08 to maintain a constant end point on the gasoline formed from the vapors leaving chamber I2. The necessary variations in the amount of gasoline pumped to dephlegmator I 0 to compensate for changes in the vapor flow therethrough are readily produced by thermostatic control of the speed of pump I 06, a thermostat not shown) for this purpose being connected into the vapor line 92.

Liquid gasoline from the condensers has a cooling effect when introduced into tower I0 due both to its temperature and to its vaporization at the temperatures in the tower. The gasoline from tank I84 moreover, is preferably introduced into chamber I2 in sufiicient quantity so that a considerable portion of it does not vaporize in chamber I2 when pumped thereinto, but runs down into chambers below chamber I2 before vaporizing. Advantage is therefore taken in the design of dephlegmator or tower III of the cooling effect of the heavy gasoline from condenser 94 when pumped back into the chamber I2 by correspondingly reducing the size of the cooling coils in the chambers below the top tray.

All the gasoline from condenser 94, however, is not required to be put back into chamber I2 and gasoline from tank I 04 not used by pump I86 flows through valve I26 in pipe I24 to pipe H8 and thence to storage. Similarly, gasoline from condensers 96 and 98 collects in tank H8 and flows from this tank to storage through pipe II8. A valve I20 in pipe H8 is controlled by a float in float tank I22 connected to tank H0, so as to maintain a substantially constant level of gasoline in tank I Hi.

In addition to the pipe connections previously mentioned as used in the operation of the apparatus and process according to the present in Vention; there are illustrated in the drawing certainpipe connections used only on particular occasions. For instance, the vapor line d leading from the top of the separator chamber 52 to the cracking chamber 24 has a branch pipe I28 connected thereto and leading into the chamber 2 3 above the normal liquid level' in chamber 24 and whereby the pressure above the liquid in chambers 24 and 52 may be equalized when it is desired to draw out the liquid in the chambers when for any reason the apparatus is shut down. A valve'l29 is provided in the pipe I28 normally preventing passage of vapors through the pipe. Moreover, the feed line 6 for the raw oil has a pipe connection I39 passing through the side of the chamber 24 above the conduit 30 and arranged to-deliver more or less of the feed into the upper end of the conduit 30 whenever for any reason it is not desired that the entire feed pass through the cooling coils M, Ma and Mb, etc. and tower Ill. Also, special drawoffs are provided from chambers 36 and 52 for taking out liquid from the lower ends of these chambers whenever it is desired to drain the liquid from these chambers. For this purpose valved pipe I32 leads from the bottom of'chamber 36 connecting with the pipe 62 and valved bypass l3l connects the pipe 82 with pipe 18 for permitting reflux collecting in chamber M to pass into a recycle gas oil tank. Similarly a valved pipe I36 is connected into the lower end of cham- ',ber 52 and arranged to deliverto pipe 62. Another way of discharging oil from chambers 3t and 52 is provided by a pipe I38 connected at one end to a pipe 88 and coil 90, connection being provided from the coil 90 to a relief tank. When desired, liquid may be discharged from chambers 36 and 52 into pipe l38 and thence into the relief tank through valved pipe connections I40 and M2 respectively. Moreover, provision is made whereby, when desired, some or all of the liquid going through the pump 42 may be circulated through the chambers 52, 24 and 36 without passing through the pipe coil 46. The arrangement for this purpose comprises a connection between the pipes H8 and 44 including a valve I44. By opening the valve I44 and the valves in pipes I40 and M2, (when flow from pipe I38 to pipe 88 is out off) the pump 42 may be kept in operation while little or no" cracking is being carried out. It is preferred, moreover that the valves in pipes l32 and I36, as well as other valves which may be used to draw oif partially cracked material from-chambers 2d and 52 during the normal operation of the apparatus shall be operated like valve 64 so as to be open to the fullest ex tent when it is desired to draw off liquid and to close them tightat other times.

While an apparatus according to the present invention and adapted to operate in accordance with the process of the present invention is illustrated in the accompanying drawing and described herein in detail, it should be understood that such detailed disclosure is'illustrative only and is not intended as limiting the scope of the appended claims.

The separator and cracking chamber have been shown as being insulated. The usual practice for cracking stills is to insulate all equipment including pipe lines which handle hot oil. This insulation is not illustrated in the drawing for the trolled refluxing conditions in a dephlegmating zone to thereby condense the high boiling point constituents in said vapors, passing the u'ncon densed vapors having substantially the desired end point for gasoline from said zone through a series of condensing zones of decreasing tempera-; ture in each of which a portion of said uncondensed vapors is condensed, separately withdrawing the condensate formed in each zone,"cooling and introducing into the dephlegmating zone gasoline condensate formed in the highest temperature zone of said series of. condensing zones unmixed with'any of the other of said condensates to thereby control the end point of the vapors discharged from said dephlegmating zone.

2. In the fractionation of hydrocarbon oils, the 7 condenser to a cooling action to condense a portion thereof, cooling the condensate thus formed and introducing the cooled condensate into the fractionating column.

3. In the manufacture of gasoline, the process that comprises passing mixed hydrocarbon vapors including components adapted for gasoline to a fractionating column wherein said vapors are subjected to fractionation, removing vapors comprising essentially gasoline components from the upper part of said column, subjecting said vapors to a partial condensing action to condense a portion thereof while conducting the uncondensed gasoline vapors to a final condenser, cooling the condensate formed by said partial condensing action and introducing the cooled condensate to the fractionating column as a reflux condensate.

4. In the fractionation of hydrocarbon oils, the process which comprises introducing the hydrocarbon vapors to be fractionated to a fractionating column wherein vapors are subjected to fractionation, removing uncondensed vapors from the upper end of the fractionating column, passing the said removed vapors to a partial condenser wherein a portion thereof is condensed, passing the uncondensed vapors from the partial condensed to a final condenser and collecting the resultant condensate from said vapors, cooling the condensate from the partial condenser and conducting a regulated quantity of the cooled condensate to the upper portion of the fractionatin column.

5. In apparatus for fractionating hydrocarbon oils, a fractionating column, a partial condenser in vapor communication with said column, means including a conduit adapted to conductliquid condensate from said partial condenser to the upper portion of the fractionating column, means for applying a cooling medium to a portion of said conduit, a final condenser in vapor communication with said partial condenser, and means for collecting the condensate obtained in the final condenser.

6. The process of fractionating hydrocarbon oil vapors, which comprises introducing a mixture of oil vapors including gasoline hydrocarbons and higher boiling point hydrocarbons into a fractionating column in which the vapor mixture is subjected to progressively lower temperatures, withdrawing the lower boiling point portion of the vapor mixture including the gasoline hydrocarbons from the upper portion of said fractionating column, passing the withdrawn vapors through a condensing zone and condensing the higher boiling point constituents thereof, separately condensing the remaining vapors, cooling condensate produced in said condensing zone and introducing it into the upper part of said fractionating column to aid in the fractionation of the vapors passing therethrough.

7. The process of fractionating hydrocarbon oil vapors containing a substantial proportion of gasoline hydrocarbons, which comprises subjecting the vapors to controlled refluxing conditions in a fractionating tower to condense higher boiling point constituents of the vapors and leave the gasoline hydrocarbons uncondensed, passing the uncondensed vapors from said fractionating tower through a series of condensing zones of decreasing temperature in each of which a portion of said uncondensed vapors is condensed, separately withdrawing the condensate produced in the highest temperature zone of said series, cooling and introducing a regulated quantity thereof unmixed with any of the condensate from the other of said zones into the upper part of the fractionating tower to thereby thereby aid in controlling the end point of the vapors withdrawn therefrom.

8. In the fractionation of hydrocarbon oil vapors in which such vapors are introduced into a fractionating column and condensation of a portion thereof effected in said column, the improvement which comprises withdrawing vapors from the upper part of said column, condensing a portion of the withdrawn vapors in a partial condensing zone, and thereafter condensing the remaining portion of the vapors in a subsequent condensing zone, cooling the condensate formed in the partial condensing zone and introducing a regulated quantity thereof into the fractionating column to aid in controlling the fractionation of the vapor therein.

9. The process of manufacturing gasoline as defined by claim 3 in which the quantity of cooled condensate introduced into the fractionating column is regulated in accordance with the temperature of the vapors removed from the upper part of said column.

10. The process of fractionating hydrocarbon oil vapors, which comprises subjecting a stream of hydrocarbon oil vapors to fractionating conditions in a fractionating zone, maintaining a superatmospheric pressure on the oil vapors in the fractionating zone, withdrawing a stream of uncondensed vapors from the fractionating zone and subjecting it to cooling and condensing conditions to condense a portion of the withdrawn vapors, separating the resulting condensate and uncondensed vapors, further cooling the separated condensate and introducing it into said fractionating zone to aid in the fractionation of the oil vapors therein, and subjecting the separated vapor stream to cooling and condensing conditions to produce a final distillate.

11. The process of fractionating hydrocarbon oil vapors, which comprises introducing the vapors to be fractionated into a fractionating column and passing the same therethrough in intimate contact with condensate formed therein, passing a hydrocarbon oil in indirect heat exchange with vapors in the upper part of said column and then in direct heat exchange with the vapors in the lower part of said column, withdrawing uncondensed vapors from the upper part of said column and passing them through a series of condensing zones of progressively lower temperature in each of which a condensate is formed, cooling condensate from the condensing zone of highest temperature, and introducing a regulated quantity thereof into the upper part of said fractionating column.

12. The process of fractionating hydrocarbon oil vapors containing a substantial proportion of gasoline hydrocarbons, which comprises subjecting the vapors to controlled refluxing conditions in a fractionating tower to condense higher boiling point constituents of the vapors and leave the gasoline hydrocarbons uncondensed, passing the uncondensed vapors from said fractionating tower through a series of condensing zones of decreasing temperature in each of which a portion of said uncondensed vapors is condensed, withdrawing the condensate produced in the highest temperature zone of said series, cooling it and introducing a regulated quantity thereof into the upper part of the fractionating tower to thereby aid in controlling the end point of the vapors withdrawn therefrom.

13. The process of fractionating hydrocarbon oil vapors containing a substantial proportion of gasoline hydrocarbons, which comprises subjecting the vapors to controlled refluxing conditions in a fractionating tower to condense higher boiling point constituents of the vapors and leave the gasoline hydrocarbons uncondensed, passing the uncondensed vapors from said fractionating tower through a series of condensing zones of decreasing temperature in each of which a portion of said uncondensed vapors is condensed, passing condensate from the highest temperature zone of said series through a cooling zone and then in regulated quantity into the upper part of the fractionating tower to thereby aid in controlling the end point of the vapors withdrawn therefrom, and mixing any remaining condensate produced in said highest temperature zone with the condensate produced in a succeeding condensing zone.

DAVID G. BRANDT.

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