US1934056A

US1934056A - Art of and apparatus for converting hydrocarbons

Info

Publication number: US1934056A
Application number: US475100A
Authority: US
Inventors: William L Gomory
Original assignee: Standard Oil Development Co
Current assignee: Standard Oil Development Co
Priority date: 1930-07-15
Filing date: 1930-08-13
Publication date: 1933-11-07
Anticipated expiration: 1950-11-07

Description

PURIFIEES Nov. 7, 19339.. w. L. GOMORY 119934356 ART OF AND APPARATUS FOR CONVERTING HYDROCARBONS Filed Aug.- 13 1930 2 Sheets-Sheet l fireman! Jl/PPLy NQVQ 1 7, 1933; w L, GOMQRY L934M56 ART OF AND AHARATUS FOR CONVERTING HYDROCARBONS Filed Aug. 13, 1930 2 Sheets-Sheet .-2

SUPPLY CONl/EEIIK Patented Nov. 7, 1933 UNITED STATES PATENT OFFICE ART OF AND APPARATUS FOR CONVERTING HYDROCARBONS William L. Gomory, Paris, France, assignor to Standard Oil Development Company, a corporation of Delaware 12 Claims.

This invention relates to the treatment of hydrocarbons and more especially to the treatment of hydrocarbon oils and the said invention provides a process and apparatus whereby hydrocarbon oils of the most varied kind can be success-- fully treated in a continuous operation in the presence of hydrogen or hydrogen-containing'gas or gas capable of liberating hydrogen, or in the presence of substances capable of liberating hydrogen or hydrogen-containing gas or gaseous hydrocarbons, and in the presence or absence of catalysts. All of these alternatives, either singly or in any desired combination will be herein after referred to as hydrogen.

According to thepresent invention the hydrocarbon oil to be treated is subjected to distillation temperature at atmospheric or super-atmospheric pressure in a distilling zone and the vapours evolved are led from this distilling zone into a vaporizing zone, whereas the distillation residue is subjected to cracking conditions of temperature, pressure and time in a heating and conversion zone in the presence of hydrogen the resulting products being discharged into the vaporizing zone for separation. Preferably the products of hydrogenation are intimately mixed with the distillation vapours and then discharged into the vaporizing zone for separation. The vapours obtained in the vaporizing zone are, for instance removed and fractionally condensed and separated and the residue is continuously withdrawn.

The oil may moreover be heated to distillation temperature while passing it through a heating zone under pressure before entering the distillation zone where the heated oil is maintained at distillation temperature and at atmospheric or super-atmospheric pressure as above mentioned.

Furthermore the residue obtained in the evap- 40 orator is advantageously subjected to cracking conditions of temperature, pressure and time in the heating and conversion zone in the presence of hydrogen According to the present invention the heating and conversion zone consists of small diameter tubes, which are arranged in a furnace setting, and of larger diameter heat-insulated conversion chambers; or in cases of hydrocarbon oils which do not require a very severe treatment a continuous coil made up from smaller diameter tubes which are arranged in a furnace setting may serve as a heating and conversion zone.

Furthermore, the residue obtained in the evaporator may beintroduced either wholly or partly into the inlet of the heating and conversion zone; or the said residue, in order to be subjected to only partial treatment, may be introduced at an intermediate point or points of the coil which either forms the heating zone (in cases where there are separate conversion chambers) or forms a combined heating and conversion zone. The residue may also be introduced into the stream of oil at the outlet end of the coil. The residue may moreover be introduced into the system at two or more of the positions above mentioned.

g The reflux condensate from the vaporizing zone is advantageously returned to the heating and conversion system for further hydrogenation treatment, for example, it may be introduced either wholly or partly into the inlet of the heating and conversion zone; or the said reflux condensate, in order to be subjected to only partial treatment, may be introduced at an intermediate point or points of the coil which forms either the heating zone or a combined heating and conversion zone. The reflux condensate may also be introduced into the stream of oil at the outlet end of the coil. The reflux condensate may however be introduced into the system at two or more of the positions above mentioned. The reflux condensate may be introduced at the positions above mentioned together with residue obtained from the evaporator.

In cases where there are separate heating and conversion zones the quantity of residue or of reflux condensate or of both residue and reflux condensate introduced into the stream of hydrogenated cracked products and hydrogen passing from the heating zone, e. g. a coil or series of coils, to the conversionzone, e. g. one or more conversion chambers, is so regulated that it will control the temperature of the oil in the conversion zone. A further means of effecting such regulation of the temperature, consists in that part of the oil from the furnace coil or series of coils is taken from an intermediate point in such coil or series of coils and is introduced into the stream of heated'oil passing from the furnace coil or coils into the conversion chamber or chambers.

In cases where the heating and cracking zone consists of a coil or series of coils only the quantity of the residue and/or reflux condensate introduced into the stream of hydrogenated 105 cracked products and hydrogen passing from the heating and conversion coil or coils to the evaporator, is so regulated that it will control the temperature of the oil before the same enters into such evaporator, or will control the tem- 110 perature of the oil in the evaporator.

Furthermore, part of .the oil passing through the coil or coils may be taken from an intermediate point of the coil or coils and introduced into the stream of products passing to the evaporator, in order to regulate the temperature thereof. The vapours, reflux condensate and residue are advantageously recovered and separately removed from the vaporizing zone.

The reflux condensate before it is introduced into the heating and conversion zone, is subjected to distillation at atmospheric or superatmospheric pressure for the purpose of separating the light fractions from the same.

The light vapours separated from the reflux condensate are introduced into the fractionator or fractionators either separately or together with the vapours obtained in the vaporizing zone. introduced into the vaporizing zone. Moreover the vapours obtained from the reflux condensate may be partly introduced into the vaporizing zone, e. g. the heavier fractions, and partly into the fractionator or fractionators, e. g. the lighter fraction. Or the said light vapours may be fractionated in a separate fractionator.

The residue removed from the vaporizing zone is advantageously subjected to a second vaporization at atmospheric or super-atmospheric pressure, the vapours so obtained being introduced into the first vaporizing zone, the final residue being withdrawn and if desired subjected to destructive hydrogenation for instance by being returned to the heating and conversion zone. The vapours obtained from the residue in the second vaporizing zone may be introduced into the fractionator or fractionators. The vapours obtained from the residue in the second vaporizing zone may be separately fractionated or they may be partly introduced into the first vaporizing zone and partly into the fractionator or fractionators receiving the vapours from the evaporator, e. g. the heavier and lighter fractions respectively.

In some cases it may be desirable to subject the residue from the first vaporizing zone to a second vaporization at atmospheric or super-atmospheric pressure in such a manner as to vaporize all volatile matter contained in the residue, the resulting solid residue being removed and the vapours introduced into the first vaporizing zone or into the fractionators or into both the first vaporizing zone and the fractionators. The vapours obtained from the residue in the second vaporizing zone, are advantageously subjected to fractional condensation, the uncondensed vapours being passed into the first vaporizing zone or into the fractionators, or. into both the first vaporizing zone and the fractionators, and the condensed heavier fractions being returned to the system with or without subjecting them to distillation in a still, which may be the still in which the reflux condensate from the first vaporizing zone is re-run.

In all the above forms of my improved process, the vapours from the evaporator may be separated into good end-point gasoline and other valuable fractions by passing them through fractionators and rectifiers provided with controlled cooling, which cooling may be effected either by the feed oil or by means independent thereof.

The reflux condensate obtained in the fractionator or fractionators may be introduced into the vaporizing zone for redistillation.

In cases where the heating and conversion zone consists of separate heating and conversion zones,

Or if desired such light vapours maybe tated during the reaction with the aid of agita tors. Or the material under conversion may be circulated from the lower part to the upper part or top of the conversion chamber or chambers.

Or it may be circulated from the conversion chamber or chambers into the furnace coil and back into the chambers.

According to the present invention, the hydrogen is introduced under pressure in sufficient volume and preferably in heated condition either to the inlet end of the heating and conversion zone or directly into the conversion chamber or chambers, or it may be introduced simultaneous- 1y both to the inlet end of the heating and conversion zone and into the conversion chamber or chambers. The hydrogen may also be introduced into the coil or coils at various intermediate points thereof. Or in cases where there is a combined heating and conversion coil the gas is introduced into the inlet end of such coil and at one or more intermediate points thereof.

The hydrogen is brought to the required temperature in a heater which is preferably placed in the furnace in which the heating and conversion coils are disposed, but such heater may, if desired be located outside of the coil furnace.

A uniform super-atmospheric pressure may be maintained in the coil and in the conversion chambers, where such are employed, or a higher pressure may be maintained on the coil than in the conversion chamber or chambers. The pressure in the vaporizing zone may be maintained at a lower value than that in the conversion chamber or chambers, or in the coil or coils in cases where no separate conversion chamber is employed. The pressure in the still, in which the reflux condensate from the first or primary vaporizing zone is re-run, is maintained at a higher value than that in the first vaporizing zone or in the fractionators. Furthermore a higher pressure is advantageously maintained in the auxiliary or secondary vaporizing zone than the first or primary vaporizing zone. Generally speaking different pressure conditions may be maintained in the various parts of the system, for example lower pressure is maintained in the distillation zone or zones than in the coils. Moreover in cases where a coil forms a combined heating and conversion zone, uniform pressure conditions may be maintained in the coil and in the evaporator.

The material under conversion is advantageously subjected to the action of catalysts in the conversion chamber or chambers, or in the coils, or in both the coils and the conversion chamber or chambers. The catalysts and/or the substances capable of liberating hydrogen or hydrogen-containing gas or hydrocarbon gases may be spread on perforated trays or otherwise suitably disposed of in the chambers. Whilst being subjected to the action of catalysts in the conversion chamber or chambers, the material is advantageously agitated thoroughly.

The catalysts and/or the substances capable of liberating hydrogen or hydrogen-containing gas or hydrocarbon gases can be employed in suspension or in colloidal solution and thus circulated through the system together with the material to be treated.

According to the present invention the excess of hydrogen is separated from the vapours and is recovered and returned to the system.

The not condensed hydrocarbon vapours and gases on their way to the hydrogenating system may be subjected to dissociation in a dissociating furnace, for instance in an electric arc furnace or coil furnace, as it is described in my copending application Serial No. 475,102.

My said invention comprises a process wherein the oil is subjected to cracking conditions of temperature, pressure and time in the presence of hydrogen whilst it is conducted through a continuous heated coil and one or more heatinsulated conversion chambers, the oil or material under conversion being circulated from the lower part to the top or upper part of the conversion chamber or chambers.

The present invention also comprises suitable apparatus for carrying into practice the several forms of my improved process.

In order that the invention may be fully understood reference will be made to the accompanying drawings which illustrate in diagrammatic form with parts in section preferred apparatus for carrying my improved process into practice.

Referring to Figure 1, the oil to be treated is drawn from any convenient source of supply 1 by means of a pump 2 and is forced through

lines

1, 13 and 6 into a still 160. Valved bypass lines 90, 91 and 92 are provided in line 3 whereby a regulated amount of feed oil may be sent through cooling coils 8 and 9 which are located in the upper parts of the fractionators 10 and 11 respectively, and through cooling coil 16, which is located in the upper part of the evaporator 7, the preheated feed oil flowing through lines 12 and 6 into the still 160. The feed oil may advantageously be brought to the necessary distillation temperature by passage under pressure through branch line 3 and heating coil 4 which is located in a suitable furnace setting 5. If desired part of the feed oil may be sent through cooling coils 8, 9 and 16 and the remainder of the feed oil may be forced through heating coil 4, before the oil is passed to the still 160. The heated feed oil is preferably spread over a tray 161 which is placed in a some-- what tilted position in the vapour space of the still 160 so as to allow a thorough disengagement of the vapours.

The temperature to which the feed oil is subjected will vary widely in accordance with the composition of the oil undergoing treatment. The oil is heated to such a temperature that light products are obtained and removed from the feed oil. Live steam may be injected into the still 160 through a line 162 to assist the distillation.

Atmospheric pressure is maintained in the still 160, or,"-the still may be maintained under a super-atmospheric pressure depending on the nature of the material undergoing treatment.

Vapours liberated in the still 160 are discharged therefrom through lines 163 and 98 into the evaporator 7 where they are treated as will be shown later.

The distillation residue is continuously withdrawn from the still 160 through valve 164 and is forced under high pressure through line 45 by means of residue charging pump 46 to the inlet end of the furnace coils 23, which comprise three pipe sections 25, 26 and 27 located in different positions in asuitable furnace setting 24. The pipe section 27 of the furnace coils 23 may contain suitable hydrogenating catalysts, such as molybdenum and tungsten, or it may contain substances capable of liberating hydrogen or hydrogen-containing gas or gaseous hydrocarbons. The pipe section 27 may be of larger diameter than the pipe sections 25, 26. The furnace coils may advantageously be built up of a series of straight pipes in accordance with standard practice, e. g. with the ends of the pipes extending through the fiuewalls and suitably connected by headers having apertures provided with removable plugs to permit inspection of the pipes.

Hydrogen is withdrawn from a source of supply 99 by pump 101 and is forced through line 100 under high pressure through hydrogen heater 102 and thence through line 103 to the inlet of the furnace coils 23 where it mixes with the oil passing to the coils. The mixture of heated oil and hydrogen from the coils 23 passes through line 29 and thence through lines 31, 33and 34 to the lower portions of the conversion chambers 30 and 32. The conversion chambers are properly heat-insulated and are adapted to withstand very high pressures of the order of 200 atmospheres and more and to maintain the material undergoing conversionat the desired conversion temperature. The conversion chambers can be equipped with agitators to keep the material under treatment in vehement motion, whilst, if desired, catalysts may be spread on perforated trays 32 or otherwise suitably disposed within the chambers.

The hydrogen may be introduced at an intermediate point of the furnace coils 23 through branch line 104 or it may be introduced through line 105 into line 29 to mix with the oil passing from the furnace coils 23 to the conversion chambers 30, 32. The hydrogen may also be passed directly into the conversion chambers 30, 32 through lines 106 and branch lines 107, 108.

The products of the destructive hydrogenation treatment are withdrawn from the conversion chambers 30, 32 through lines 95, 96 and 9'? and pass through line 98 into line 98 where they are intimately commingled with the vapours obtained from still 160, the mixture then passing through pressure regulating valve 35 into the evaporator 7.

Valves are suitably disposed in lines 29, 31, 33,

'34, 95, 96 and 97 to enable the conversion chambers 30, 32 to be operated in parallel or series. For example the conversion chambers 30, 32 can be used in parallel by opening the valves in lines 33 and 96 and closing the valves in the line 29 and the valve in line 95. They may then be used in series by opening the valve in line 95 and closing the valve in line 33 and line 96. Although two conversion chambers only have been shown in the drawings, it is to be understood that any desired number of conversion chambers can be used, either in parallel or in series, depending upon the nature of the material under treatment and the time necessary to effect-the desired degree of conversion.

Oil undergoing conversion and hydrogenation in the conversion chambers 30, 32 may be agitated during the reaction with the aid of agitators or by a withdrawal of oil therefrom by means of pump 52 through branch lines 49, 50 and line 51 and circulation of such oil through line 53 back to the inlet of the conversion chambers, or through

lines

53 and 53 and branch lines 5311,

53b from the lower to the upper part of the conversion chambers, or such oil may be circulated through line 45 to the inlet of the furnace coils 23 and thence back to the conversion chambers through line 29.

The mixture of products from the conversion chambers and vapours from the still 160 are separated in the evaporator 7 into residue, reflux condensate and uncondensed vapour. The evaporator 7 is provided with controlled cooling and, in addition to cooling coil 16 through which a regulable amount of feed oil is passed, a further cooling coil 17 is provided in the upper part of the evaporator, so that the cooling may be effected by means which are independent of the supply of feed oil.

The separation of desirable overhead products from the residue in the evaporator 7 may be assisted by steam coil 15 through which live steam is introduced. In addition to steam coil 15, a heat exchanger coil 14 is also provided in the lower part of the evaporator 7, and hot residue or hot intermediate products -may be passed through such coil on their way to storage.

Bafile plates 17 are suitably disposed within the evaporator 7 to ensure: a thorough intermingling of ascending vapour with descending liquid and the evaporator is advantageously heat insulated. The temperature maintained in the' evaporator will vary according to the nature of the material undergoing treatment. The temperature in the evaporator is so regulated that the fractions which consist mainly of gasoline, naphtha, and light kerosene leave the evaporator as vapours, whilst heavier fractions are con densed therein to form reflux condensate and residue. Reflux condensate formed in the evaporator 7 is collected in a pan 18 from which it is withdrawn through line 19 by means of a pump 20. All or part of the reflux condensate may be passed to storage through line 171, or all or part of such condensate may be passed by pump 21 through lines 22' and 22 directly to the inlet of the furnace coils 23 for further treatment, or through line 45 tomix with the distillation residue passing to the furnace coils 23.

If desired, all or part of the reflux condensate can also be passed through line 22 and branch line 41 into the stream of heated oil and hydrogen passing along line 29 from the furnace coils to the conversion chambers, whilst all or part of the reflux condensate may be passed through line 38 to an intermediate point of the furnace coils.

Residue obtained in the evaporator 7 is withdrawn therefrom by line 43- and may be returned to the inlet of the furnace coils 23 through line 45 together with the distillation residue. Or all or part of the residue obtained in the evaporator may be returned through lines 44' and 22 together with the reflux condensate to the inlet of the furnace coils, or to an intermediate point thereof through line 38, or into the outlet end of the furnace coils through line 41. The reflux condensate from the evaporator 7 may be returned to the inlet of the furnace coils independently of the residue from such evaporator through

lines

19, 171, 172 and 37 by means of pump 36, or to an intermediate point of the furnace coils, through line 40 and branch line 39, or to the outlet thereof through line 40.

The mixture of heated oil and hydrogen passing through the furnace coils may be withdrawn from an intermediate point thereof through line 42 and passedthrough line 29 into the conversion chambers. 7

All the lines conveying oil or gas into the heating coil or to the outlet thereof or into the conversion chambers, are provided with check valves to prevent the hot products from backing into these lines and all the lines conveying hot oil are heat-insulated.

Vapour and gas from the evaporator .7 pass through line 54, having a pressure control valve into the lower portion of fractionator 11 from the upper portion of which vapour and gas are withdrawn by line 56 to a second fractionator 10. The fractionators 10 and 11 are heat-insulated and are provided with additional regulable cooling coils 58, 59 respectively in the upper portions thereof to provide cooling means which are independent of the supply of feed oil.

The vapours are properly fractionated in the fractionators 10 and 11 and separated into products having the desired boiling range and live steam may be injected into the fractionators through lines 60 to assist the fractionation. Condensates are withdrawn from the fractionators 10, 11 to coolers 61, 62 and thence to storage tanks 61, 62 respectively whilst vapour and gas from fractionator 10 is withdrawn through line 63 to a condenser 64. Incondensable gas is separated from condensed vapours in separation drum 109, the condensate flowing through a cooler 110 to a receiver 93. The incondensable gas including excess hydrogen is withdrawn from drum 109 by a 05 pump 111 and passed through line 112 to purification towers 114, 114, from which the purified gas is passed to the source of supply 99 through line 112. The incondensable gas is washed with an alkali solution in tower 114 to remove hydro- 110 gen sulphide and the like, and with a hydrocarbon oil in tower 114 to remove gaseous and low-' boiling hydrocarbons. Preferably the hydrocarbon vapours and gases while being returned to the hydrogenating system are subjected to opti- 115 mum dissociating conditions.

The dissociation treatment of these gases may be accomplished in a furnace, as shown in my copending application Serial No. 475,102 or an electric arc furnace can be used. 120

When catalysts such as molybdenum or tungsten are used, it is preferable not to remove the hydrogen sulphide from the gas as hydrogen sulphide increases the activity of such catalysts.

Part or all of the condensate from the fractionators 10, 11 may be passed by pump through line 79 to the evaporator 7 for redistillation.

The reflux condensate from the evaporator 7 sometimes contains low-boiling hydrocarbons which it is not desirable to return to the system for further treatment. In these cases, the reflux condensate is passed through

lines

19, 171 and 65 by means of pump 65' into the re-run still 66 wherein it is subjected to distillation in order to separate the light fractions contained therein. 135 The re-run still can be heated directly or hot residue from the system may be passed through heating coils placed in the still (not shown), whilst live steam can be passed into such still through line 67.

Residue from the re-run still may be withdrawn to storage through line 68 or returned through lines 68', 22' and 22 to the inlet of the furnace coils, or to an intermediate point thereof or to the outlet of the furnace coils to enter the con- 145 version chambers.

The vapours separated from the reflux condensate in the re-run still 66 are withdrawn through line 69 to the upper part of the fractionator 11, or all or part of such vapours may be passed 1 0 through branch line '70 of the evaporator 7, or, if desired, such vapours may be recovered in a separate fractionator.

Sometimes, it is desirable to subject the residue from the evaporator 7 to a second vaporization. In these cases, such residue is withdrawn from the evaporator through line 71 by means of pump 72 and is passed through lines 72, 73 into the auxiliary evaporators 74, 75 which are heated by the injection of steam through spray pipes 76, or by direct heat or both.

Final residue from the auxiliary evaporators may be withdrawn by pump 94 through line 77 to storage or it may be returned to the hydrogenation system through line 113 by means of pump 21 and line 22. Vapour passes from the auxiliary evaporators through line 78 either to the evaporator 7 through line 81 or into fractionator 11 through branch lines 82, 83. Or, if desired, such vapour may be passed through line 84 to a separate heat-insulated fractional condenser 85 which is provided with a cooling coil 85 in the upper part thereof and with a spray pipe 85"--for steamin the bottom thereof, and uncondensed vapours from the fractional condenser 85 are returned through lines 86, 78 either to the evaporator 7 or to the fractionator 11. heavier fractions from the fractional condenser 85 are passed either to the re-run still 66 through line 88 or returned to the furnace coils 23 by pump 87 through

lines

89, 68', 22 and 22.

The temperature to which the mixture of oil and hydrogen is heated in the furnace coils will vary within very wide limits, according to the composition of the oil to be treated and the degree of treatment required but will be normally between 750 to 1200 degrees F. and the pressure used both in the coils and conversion chambers is of the order of 50 to 200 atmospheres or more. If desired a somewhat lower pressure can be maintained in the conversion chamber than in the heating coils.

The temperature in the conversion chamber is maintained at the optimum. Should the outlet temperature from the coil be higher than the optimum temperature desired in the conversion chambers, a relatively cooler oil is introduced into the stream of oil and gas mixture entering the conversion chambers. temperature of the oil in the chambers is successfully regulated and maintained, preferably not below 700 degrees F.

For this purpose, preferably part of the reflux condensate is introduced from pan 18 through

lines

19 and 170 into the stream of oil and gas passing from the coils into the conversion chambers.

It is desirable to maintain a super-atmospheric pressure on the evaporator '7 and on the fractionators 10, 11 so that the separation may be carried out under proper control, but the separation may be carried out at atmospheric pressure.

Valves are suitably disposed throughout the apparatus to control the flow of oil and gas to the different parts of the system and to enable any desired pressure to be maintained therein.

In cases where the material to be treated does not require a very severe treatment, the conversion can be completely accomplished in the heating and cracking coils and in such cases the conversion chambers can be dispensed with.

Referring to Figure 2 it will be seen that the furnace coils 23 comprise both the heating and the conversion zones and that the conversion chambers have been dispensed with. Generally The condensed By this means the products immediately they leave the coils so as to avoid the occurrence of undesirable after-ree actions. This cooling can advantageously be achieved by the introduction of reflux condensate from pan 18 through line 170 into the stream of oil and hydrogen passing to the evaporator 7.

In the operation of my improved process in which the conversion chambers are dispensed with, the oil may be subjected in the heating and conversion coil to temperatures of 750 to 1500" F. at a pressure of 50 to 300 atmospheres or more and atmospheric pressure or a pressure of 5 atmospheres or more can be maintained in the evaporator.

In the following claims the term fresh oil has been used to denote the oil as fed into the system and to distinguish from streams which may be withdrawn from some part of the system and recirculated to another part thereof.

Obviously many modifications and variations of the invention, as hereinbefore set forth, may be made without departing from the spirit and scope thereof, and therefore only such limitations should be imposed as are indicated in the appended claims- I claim:

1. A process for the conversion of hydrocarbon oil to lower boiling fractions comprising subjecting the fresh oil to distillation in a separate distilling zone without substantial decomposition, discharging the vapors into a vaporizing zone, subjecting the distillation residue to cracking conditions of temperature and time in a heating and conversion zone in the presence of hydrogen under a pressure in excess of about 50 atmospheres, discharging the resulting products into said vaporizing zone and separating to lower boiling fractions.

2. A process for the conversion of hydrocarbon oil to lower boiling fractions comprising heating the hydrocarbon fresh oil to distillation temperature while passing them through a heating zone under pressure without substantial decomposition and then discharging the heated hydrocarbons at distillation temperature ina separate distilling zone, discharging the vapours into a vaporizing zone, subjecting the distillation residue to cracking conditions of temperature and time in a heating and conversion zonein the presence of hydrogen under pressure of the order of about 50 to 200 atmospheres, discharging the resulting proddistillation zone into a vaporizing and fractionating zone, subjecting the unvaporized oil from the distillation zone to a conversion operation in a heating and conversion zone in the presence of hydrogen under pressure in excess of about 50 atmospheres, discharging the products from the heating and conversion zone into said vaporizing and fractionating zone, withdrawing a vapor fraction and reflux condensate and a residue from said last mentioned zone and returning the hot residue to said heating and conversion zone.

5. A process for the conversion of hydrocarbon oils into lower boiling fractions which comprises passing the fresh oil through a preheater without substantial decomposition into a separate distillation zone, discharging the vapors from the distillation into a vaporizing and fractionating zone, subjecting the unvaporized oil from the d stillation zone to a conversion operation in a heating and conversion system in the presence of hydrogen under pressure of the order of 50 to 100 atmospheres, discharging the hot products from the heatng and conversion zone into said vaporizing and fractionating zone, withdrawing a vapor fraction, a reflux condensate and a residue from said last mentioned zone and returning he hot reflux condensate to said heating and conversion zone.

6. A process substant'ally as defined in claim 4 in which the residue, prior to return into the heating and conversion zone, is subjected to partial distillation and the resulting vapors passed directly to the vaporizing and fractionating zone.

'7. A process substantially as defined in claim 4 in which the residue instead of being returned to the heating and conversion zone is subjected to distillation and a distillate therefrom returned to said heating and conversion zone.

8. A process substantially as described in claim 5 in which the reflux condensate, prior to introduction into the heating and conversion zone, is subjected to partial distillation and the resulting vapors passed to the vaporizing and fractionating zone.

9. An apparatus for the conversion of hydrocarbon oils, a combination of a preheater coil, 2. still, means for passing fresh oil through the proheater into said still, a vaporizer, a vapor line connecting the still with the vaporizer, a tube and drum converter, means for passing oil from the still to the converter, means for introducing hydrogen into the converter, connections for transferring hot products from the converter directly into the vaporizer, means for withdrawing a vapor fraction and reflux condensate and a residual liquid fraction from the vaporizer and means for conducting the residual liquid fraction drectly into the converter.

10. An apparatus substantially as described in claim 9 including means for partially distilling the residual liquid fraction prior to passing the same to the converter and for conducting the evolved vapors from the partial distilling opera tion to said vaporizer.

11. An apparatus for the conversion of hydrocarbon oils, the combination of a preheater coil, a still, means for passing fresh oil through the preheater into the still, a vaporizer, a vapor line connecting the still with the vaporizer, a tube and drum converter, means for introducing hydrogen into the converter, means for passing oil from the converter to said vaporizer, means for withdrawing vapor, reflux condensate and residue from the vaporizer, means for conducting the reflux condensate into said converter.

12. An apparatus substantially as described in claim 11 includng means for partially distilling the reflux condensate prior to conducting the