US1948345A

US1948345A - Method and apparatus for cracking oils

Info

Publication number: US1948345A
Application number: US488073A
Authority: US
Inventors: Ross J Garofalo
Original assignee: Union Oil Co of California
Current assignee: Union Oil Co of California
Priority date: 1930-10-11
Filing date: 1930-10-11
Publication date: 1934-02-20
Anticipated expiration: 1951-02-20

Description

Feb. 20, 1934. R J, OFALO 1,948,345

METHOD AND APPARATUS FOR CRACKING OILS Filed Oct. 11, 1930 INVENTOR. Ross J Garofalo ATTORNEY.

Patented Feb. 20, 1934 UNITED STATES PATENT OFFICE Ross J. Garofalo, Los Angeles, Calif assignor to Union Oil Company of California, Los Angeles, Calif., a corporation of California Application October-'11, 1930. Serial No. 488,073

22 Claims. (Cl. 196-70) This invention relates to an improved process and apparatus for the distillation of hydrocarbon oils, such as crude petroleum or its distillates. It relates more particularly to a process and apparatus for cracking oils in the vapor phase by means of molten metal, said molten metal being intimately mixed with vapors by means of an injector.

In the vapor phase cracking of oils, it is highly desirable to subject oil vapors to high temperatures for short periods and to cool rapidly the thus cracked vapors. A piocess carried out under these conditions will prevent the production of excessive quantities of fixed gases and carbon which are a consequence of overheating. It is, therefore, an object of the present invention to provide a novel process which will efiiciently ac-. complish these results of vapor phase cracking.

I have discovered that by using molten metal as a heating agent and producing contact with oil or vapors by means of an injector or other spray device, I can obtain the following:

First, intimate contact of sufficient duration between the oil and a small amount of heating medium;

Second, eflicient, rapid and uniform heating or cracking of the oil or vapors;

Third, immediate removal of oil from the heating zone; and 0 Fourth, continuous cyclic circulation of the molten metal without employing pumps.

In some of the prior processes for cracking oils in the vapor phase, the vapors are subjected to the action of a hot gaseous medium for a definite period of time and the resulting mixture of cracked vapors and gaseous cracking medium is then subjected to a fractional condensation operation in order to separate the various fractions from the gaseous cracking medium. This often results in undesirable overheating of the vapors due to inability to control the cracking through a large body of molten metal placed in a still or container which is maintained at a high temperature by heating the bottom of said container. This type of process usually necessitates the continuous heating of a large body of molten metal. Due to physical limitations this heating is not uniform nor eificient. Therefore, oils or,

vapors passed through the heated metal are likewise non-uniformly and inefficiently heated. Also, residue and carbon deposited upon the surface of the molten metal soon coke and incrust on the surface of themolten metal, thereby necessitating the removal and purification of the latter before the operation may be continued. Additionally, it is difilcult to get uniform and intimate contact and to control the cracking time. I

It is, therefore, an object of the present inven tion to overcome the prior difllculties of cracking with molten metal and to present a process which is simple in operation and an apparatus simple in construction. It is a further object of this invention to provide a process and apparatus having all of the advantages of cracking attendant upon the use of molten metal, such as uniform, rapid and more efiicient heat transference.

According to the present invention, the drawbacks inherent in prior processes are overcome by the intimate mixing of the oil or vapors. with small amounts of hot molten metal as by means of an injector for only a very brief period, quickly removing the molten metal from the cracked vaporsyreheating the removed molten metal and reintroducing the reheated molten metal into the mixer in order to crack further quantities of oil or vapors. The amount of molten metal employed and circulated in this process is small in comparison with the use of metal baths.

Another feature of this invention resides in effecting acyclic circulation of the molten metal in the system without the employment of pumps. This is accomplished by utilizing the velocity of the vapors produced by release of. pressure of the 011 after preheating under pressure to a temperature sufiicient to cause vaporization of the oil upon such release. These vapors are passed to an injector and utilized to draw hot molten metal into the injector and to force the mixture to a separator wherein the hot molten metal after having given up its heat to crack the vapors in the injector is quickly removed from the cracked vapors. The metal is then reheated and again injected into further quantities of vapors. The movement of molten metal into the injector may be aided by the head of metal in the separator which flows the metal through a reheater and into the injector.

An important feature of the present invention is this cyclic circulation of the molten metal from the injector through the separator and molten metal reheater back into the injector without resorting to the use of pumps as a circulating medium.

Thus, it may be observed from the above that, in its broadest phases, the invention comprises a process and apparatus for the distillation of oil wherein the oil is intimately mixed with a small amount of molten metal in an injector. The invention also includes the mixing of oil with a small amount of molten metal in a confined stream and the separation of the molten metal after contact with the oil in the confined stream for a predetermined period. The invention further includes a process and apparatus for cracking oil or vapors wherein the hot molten metal is cyclicly circulated without resorting to the use of pumps.

In a more narrow aspect, the invention resides in a process comprising preheating oil under pressure to a temperature sufficient to cause vaporization thereof upon reduction in pressure, releasing the pressure on the thus heated oil and passing the vapors thus generated through an injector, intimately mixing said vapors with highly heated molten metal in said injector, passing the mixture of said molten metal and vapors through a conduit to complete cracking of the vapors, introducing said mixture into a separating chamber, separating the molten metal from the vapors in the separating chamber and circulating the molten metal through a heating zone and back to the injector, the circulation being effected by means of said injector.

Other objects and features of the present invention will be more readily understood from the following description in conjunction with the drawing wherein one embodiment is used to illustrate the invention.

In the drawing, oil, such as gas oil, is passed from tank 10 into line 11 controlled by valve 12 and pumped by pump 14 through heating coils 15 positioned in the furnace 16 and heated by burners 17. The oil is then vaporized by passing through expansion valve 19 positioned on line 18 and the vapors are passed into injector 20 of the venturi or other type wherein they meet a jet of high temperature molten metal as will be further described. v The mixture of molten metal and vapors is then passed through line 21, insulated with asbestos or other heat insulating material 22 and is introduced into separating chamber 25 wherein the molten metal is quickly separated from the vapors and drops to the bottom of the chamber. This separating chamber is provided with mist extractors 27 positioned in the upper part thereof.

The vapors separated from the molten metal pass into line 28 and are contacted with cold oil or other fluid passing through line 29 controlled by valve 30. The mixture then passes into separator 32 provided with mist extractors 33. Condensate in the separator passes into line 34 controlled by valve 35, is cooled in cooler 36 and collected in tank 3'7 from which it may be removed via line 38 controlled by valve 38'. The partially cooled vapors are removed from the separator 32 and passed through line 39 into fractionating column 40. Vapors introduced into the column are partially condensed and fractionated on bubble plates 41 while passing upwardly through the column countercurrent to condensate introduced through spray 42 as will be further described. Steam may be introduced into the bottom of the tower via line 43 to aid stripping and reboiling. The uncondensed vapors pass through line 45 into condenser 46 and through line 4'? into separator 48. The uncondensed vapors exit from the separator 48 via line 49 and are condensed in condenser 50, passed into line 51 and collected in run-down tank 52. The fixed gases are vented through line 53 while the condensate is withdrawn via line 54 controlled by valve 55. The condensate collected in separator 48 is withdrawn through line 60 controlled by valve 61. Part of the condensate may be bypassed into line 62 controlled by valve 63 and refluxed to the top of the fractionating column 40 to serve as cooling fluid. The condensate collecting at the bottom of the fractionating column 40 is withdrawn through line 65 controlled by valve 66.

The molten metal collecting at the bottom of the separator 25 is passed through insulated line 70 into reheating coil 71 positioned in furnace '72 and heated by'burners 73. The reheated molten metal is then passed through insulated line '74 controlled by valve '75 into injector 20. As molten metal becomes contaminated with continued use, part of the metal together with carbon and residue collecting on the surface of the 1 metal may be withdrawn from the separator 25 through the enlarged pipe or spillway 80 and passed into line 81 controlled by valve 82 and provided with trap 83. The mixture of molten metal and residue contacts a relatively high boil- I ing washing oil introduced into line 84 controlled by valve 85 and the mixture passes into separator 87. Any oil distilled passes through line 88 and is condensed in condenser 89 and the condensate is collected in run-down tank 91 from which it may be withdrawn through line 92 controlled by valve 93. The washing oil together with carbon and residue is withdrawn from the separator via line 94 controlled by valve 95. The oil free metal is passed through line 96 controlled by valve 9'7 and passed into a metal purifier 98.

An oxidizing gas such as air is passed into the purifier via line 99 controlled by valve 100 for the purpose of oxidizing any contained carbon and otherwise purifying the molten metal. gases are withdrawn from the purifier via line 101. The purified metal is withdrawn via line 102 and sent to storage or it may be introduced through line 77 into the separator 25.

It will be observed that a closed circuit is provided for the circulation of molten meta. from the injector 20, line 21, separator 25, line '70, reheater '71, line '74 and back into injector 20, the circulation being effected by the velocity of the vapors passing through the injector.

The.

This

velocity of the vapors upon release of pressure through the expansion valve is sufiicient to carry the hot molten metal introduced into the injector through line 21 to the separator. The head of metal in the separator and the position thereof with respect to the injector will necessarily aid the flowing of metal from the separator 25 through the heating coil '71. The function of the injector will be aided by the thermal circulation induced by the heating coil.

The operation of the process is expla ned below in connection with a specific example.

.Assuming that the operation is carried out on California gas oil having a gravity of about 28 A. P. I. and an average boiling point of about 550 F., the oil from tank 10 is passed into line 11 and pumped by pump 14 through coils 15 where it is heated to a temperature between 750 and 875 F., or in other words, to a temperature sufficient to cause a complete vaporization of the 'oil upon release of pressure. The pressure is maintained in the coils at about 500 to 2000 lbs. per square inch. The pressure on the oil is then released while passing through expansion valve 19 and the vapors are passed into the injector 20. The velocity of the vapors which is greatly increased due to the reduction in pressure-is sufiicient to create a suction in line 74 and to draw hot molten metal from the reheater 71 and line 74 into the injector and to pass the mixture through line 21 to the separator 25. This is aided by the thermal circulation'induced by 71. The combined forces are sufficient to cause the desired circulation through coil 71'. I

The temperature of the molten metal introduced into the injector is dependent upon the amount of molten metal introduced and upon the rate and amount of conversion desired as will be understood by those skilled in the art. Usually, in order to raise the vapor passing through the injector 20 and insulated line 21 to a temperature of above 1000 F., it is necessary to heat the molten metal to a temperature of above 1100 F.

The amount of conversion is also'dependent upon the duration of contact in line 21. Therefore, by providing a conduit 21 of proper length, the rate of conversion may be regulated. In operation, it is preferable to crack at temperatures above 1000 F. for short periods and therefore, a short conduit 21 is necessary. However, the temperature may be between 900 and 1500 F. depending on the rate and amount of conversion desired, as will be understood by those skilled in the art. For temperatures of 1000 F. and over the time contact should be approximately 2 seconds and less. For temperatures of approximately 900 F. the contact time should be about 2 minutes. The contact time will be doubled for approximately every 18 Fahrenheit degrees rise in temperature. The molten metal should be heated to a temperature of about 1500 F. and a sufficient quantity of molten metal should be introduced into the injector in order to effect a conversion of between 30 and in the injector and short'conduit.

If desired, the operation may be carried out under such conditions as to completely vaporize the oil in the coils 15 at high temperatures and pressures and the thus produced vapors are subsequently expanded and passed through the injector. Thus, temperatures of above 875 F. and pressures of 1000 to 1500 lbs. per square inch may be employed to completely vaporize the oil in the coils 15. These temperature and pressure conditions are dependent, of course, upon the particular oils treated, as will be readily understood by those skilled in the art.

The commingled cracked vapors and molten metal in exiting from line 21 are quickly separated from each other in separator 25 due to the greater specific gravity of the molten metal. This quick removal of the heating medium prevents further cracking of the vapors, thereby eliminating possible production of excessive amounts of fixed gases 3 and carbon. Carbon and heavy oil particles may also drop to the bottom of the separator with the molten metal. Mist extractors 33 are provided to prevent metal and oil particles from being carried into line 28. The uncondensed vapors in the separatorwhich are still at a relatively high tem- 20 to 30% of injection oil is introduced. These materials drop to the bottom in the separator 32 together with heavy oil fractions and are removed therefrom via line 34 controlled by valve 35, cooled in 36 and collected in tank 37 from which oil may be withdrawn via line 38 controlled by valve 38'.

The cracked vapors exiting from the separator 32 which are at a temperature of approximately 600-700" F. pass through the mist extractors 33 and through line 39 to fractionating tower 40 where they are fractionated by means of reflux condensate introduced through spray pipe.42 to produce a gas oil fraction which may be withdrawn through lineand valve 66. Part of the gas oil may be cooled and introduced into line 29 to serve as a quenching oil and part may be passed to tank 10 to be re-cracked. The uncondensed vapors pass through line 45 into the partial condenser 46 and thence through line 47 to separator 48. The uncondensed light vapors from the separator exit through line 49 and are condensed in condenser 50, collected in run-down tank 52 and the fixed gases vented therefrom through line 53. The condensate may be withdrawn from the tank via line 54. The condensate collecting at the bottom of the separator 48 which may comprise an intermediate fraction may be withdrawn therefrom through line 60 controlled by valve 61 and a portion may be by-passed through line 62 to the fractionating tower 40.

The molten metal collecting at the bottom of the separator is passed through insulated line and circulated through the molten metal reheater 71 where it is brought to a proper temperature for cracking further quantities of vapors and is then passed through insulated line 74 controlled by valve 75 into the injector. This circulation of molten metal is effected as previously stated by the injecting action of the vapors passing through the injector 20 and aided by the head of metal in the separator 25 and by the thermal circulation induced by the heater 71.

As molten metal becomes contaminated with continued use a portion should be removed and purified. For this purpose, I have provided an enlarged pipe or spillway 80. It will be observed that this spillway is positioned partly above and partly below the level of molten metal at the bottom of the separator 25. This insures the removal of carbon and heavy residuum collecting on the surface of the molten metal together with a portion of molten metaL Thus, by removing carbonaceous matter from the surface of the metal as soon as it is deposited, carbon incrustation is prevented. This also prevents the recirculation of carbon contaminated metal in the cycle. The mixture of carbonaceous matter and metal is passed through line 81 and is contacted -by a washing oil comprising a relatively heavy hydrocarbon oil introduced through line 84 and valve 85. The hot metal is cooled sufficiently to insure adequate flushing by this oil. The mixture passes into separator 87. Any oil distilled by the hot metal passes through line 88 and is down tank 91 from which it may be removed via line 92 and valve 93. The washing oil together with carbon and residuum is withdrawn from the separator 8'? via line 94 and valve 95 and passed to any suitable settling or separating device, not shown.

The oil free molten metal is withdrawn from the separator 8'7 via line 96 and valve 97 and passed to a metal purifier 98 wherein impurities contaminating the metal may be removed by contacting it with an oxidizing gas such as air introduced into the metal via line 99 and valve 100. Gases from the separator pass through line 101 While the purified metal is withdrawn via line 102 and may be passed to storage or introduced into the cracking cycle such as, for instance, via line 77. I

While no particular metal has been pointed out to be used in connection with this invention, it may be generally stated that any metal or substance may be employed having a melting point sufiicient to permit flow at the temperature employed. Thus, lead or certain alloys may be used advantageously for heating and cracking oils. The choice of the metal is easily within the skill of the ordinary engineer. It is merely essential to choose a metal or alloy having the proper melting and boiling point so as to be appreciably fluid but not volatile at the temperatures described herein. If desired, certain com-v pounds which will also purify the vapors may be used as the heating medium. Likewise, metals, metal or other compounds which act as catalysts may be employed in connection with the process when the process is desired to be operated catalytically as in hydrogenation and vapor phase cracking processes.

The above description is not to be taken as limiting but merely as illustrative of the invention and as one mode of carrying it out. Many changes can be made within the scope of this invention which is set forth'in the following claims.

I claim:

1. A process for cracking oil which comprises heating an oil under pressure to a temperature sufficient to vaporize said oil while under pressure, releasing the pressure on said vaporized oil and intimately commingling said vaporized oil with hot molten metal in an injector.

2. A process for distilling oil which comprises preheating an oil under pressure, releasing the pressure on said preheated oil, passing said pressure released oil into an injector and simultaneously introducing hot molten metal into said injector to effect distillation of said oil.

3. A process for distilling oil which comprises heating an oil under pressure to a temperature sufficient to cause vaporization of said oil upon release of pressure, releasing the pressure on said heated oil, introducing the generated vapors into an injector and simultaneously introducing hot molten metal into said injector.

4. A process for cracking oil in the vapor phase which comprises heating an oil under pressure to a temperature sufficient to cause vaporization of said oil upon release of pressure, releasing the pressure on said heated oil, introducing the generated vapors into an injector and simultaneously introducing hot molten metal into said injector.

5. A process for cracking oil in the vapor phase which ""mprises heating an oil under pressure to a temperature sufficient to completely vaporize said oil while under pressure, releasing the pressure on said vaporized oil and intimately commingling said vaporized oil with hot molten metal to crack said vaporized oil.

6. A process for cracking oil in the vapor phase which comprises heating an oil under pressure to a temperature sufficient to vaporize said oil while under pressure, releasing the pressure on said vaporized oil and intimately commingling said vaporized oil with hot molten metal in an injector to crack said vaporized oil.

7. A process for cracking oil in the vapor phase which comprises heating an oil under pressure to a temperature sufficient to completely vaporize said oil while under pressure, releasing the pressure on said vaporized oil and intimately commingling said vaporized oil with hot molten metal in a confined stream of predetermined length to crack said vaporized oil.

8. A process for cracking oil in the vapor phase which comprises completely vaporizing an oil, passing said vapor through an injector to cause 1 an aspirating effect-drawing hot molten metal into said injector by the aforesaid aspirating effect, separating said molten metal from said vapor and returning said molten metal to said injector.

9. A process for cracking oil in the vapor phase which comprises completely vaporizing an oil, passing said vapor through an injector to cause an aspirating effect, drawing'hot molten metal into said injector by the aforesaid aspirating effect, separating said molten metal from said vapor, reheating said removed molten metal and reintroducing said reheated molten metal into said injector.

10. A process for cracking oil in the vapor phase which comprises completely vaporizing an oil, passing said vapor through an injector, introducing hot molten metal into said injector to crack said vapors, passing said mixture of molten metal and vapor through a conduit to complete cracking of said vapor, separating said molten metal from said cracked vapor in a chamber, circulating said molten metal through a heater and reintroducing said reheated molten metal into said injector.

11. A process for cracking oil which comprises intimately mixing oil and heated molten metal in a confined stream, maintaining said mixture in said confined stream to cause cracking of said oil, separating oil vapor from said metal and residual carbonaceous matter from said oil in a separating zone, reheating said separated molten metal,

returning said reheated molten metal to said confined stream, withdrawing a portion of said molten metal and carbonaceous matter from said separating zone, purifying said withdrawn molten metal of said residual carbonaceous matter and returning said purified molten metal to said separating zone.

12. A process for cracking oil which comprises heating oil under pressure, expanding said heated oil through an injector to cause an aspirating effect, introducing molten metal under the aforesaid lifting eifect into the injector to cause intimate commingling of oil and metal, passing said mixture of metal and oil through a confined stream of predetermined length to effect cracking of said oil, introducing said mixture into a separator, separating said metal and carbonaceous matter from said oil in said separator, withdrawing a portion of said metal from said separator, reheating and reintroducing said portion into said injector, withdrawing a second portion of metal and carbonaceous matter from said separator, separating said carbonaceous matter from said metal, reheating and reintroducing said secend portion of metal into said injector.

13. An apparatus for cracking oil which comprises means for heating oil under pressure, means for expanding said oil, means for intimately mixing said oil with hot molten metal to crack said. oil, means for separating said hot molten metal from said cracked oil, means for reheating said separated moltenmetal, and means for returning said'reheated molten metal to said mixing means.

14. An apparatus for cracking oil which comprises means for completely vaporizing oil, an injector, means for intimately mixing said vapor with hot molten metal in said injector, a conduit of small diameter, means for passing said vapor and hot molten metal through said conduit to efiect conversion of said vapor, means for separating said holt molten metal from said 'vapor, means for reheating said molten metal and means for returning said reheated molten metal to said injector. x/

15. An apparatus for cracking oils in the vapor phase which comprises means for heating oil under pressure to above its boiling point, means for releasing the pressure on said heated oil, means for intimately mixing said pressure released oil with hot molten metal to eifect cracking of said oil, means for separating said hot-molten metal from said cracked oil, means for reheating said separated molten metal, and means for effecting a cyclic circulation of said molten metal from said mixing, separating and reheating means, said circulation being effected by the passage of said pressure released oil-through'said mixing means. 1

16. An apparatus for'cracking oils in the vapor phase which comprises means for heating oil under pressure to above its boiling point, means for releasing the pressure on said heated oil, injecting means, means for mixing said oil with hot molten metal in said injecting means to crack said oil, means for separating said molten metal from said cracked oil, means for reheating said molten metal and means for effecting a cyclic circulation of said molten metal from said injecting, separating and reheating means, said circulation being effected by the passage of said pressure released oil through said injecting means.

17. An apparatus for cracking oils in the vapor phase which comprises means for completely vaporizing oil, means for intimately mixing said vapor with a heating fluid, means for separating said heating fluid from said vapors and means for efiecting a cyclic circulation of said heating fluid from said mixing means and separating means, said circulation being effected by means of an injector.

18. In combination, an oil preheater, an.injector, an expansion valve intermediate said preheater and injector, a separator, a conduit connected to said injector and separator, a metal heater, and conduits connecting the bottom of said separator, metal heater and injector.

19. In combination, an oil preheater, an injector, an expansion valve intermediate said preheater still and injector, a separator, an insulated conduit connected to said injector and separator, a heater for molten metal, conduits connecting the bottom of said separator, heater and injector, and a draw-off connection positioned above the bottom of said separator for withdrawing metal and carbonaceous matter from said separator.

20. An apparatus for cracking oil which comprises means for intimately mixing oil with hot molten metal in a confined stream to crack oil, means for separating said hot molten metal and residual carbonaceous matter fromsaid cracked oil, means for reheating said separated molten metal, means for returning said reheated molten metal to said mixing means, means for withdrawing a portion of said molten metal and residual carbonaceous matter from said separating means, means for purifying said withdrawn molten metal of said residual carbonaceous matter and means for returning said purified molten metal to said separating means.

' 21. An apparatus for cracking oil which comprises an injector, means for intimately mixing oil with hot molten metal in said injector at a temperature suflicient to crack said oil, means for separating said hot molten metal and re- .sidual carbonaceous matter from said cracked 1113 oil, means for reheating said separated molten metal, means for returning said reheated molten metal to said injector, means for withdrawing a portion of said molten metal and residual carbonaceous matter from said separating means,

into said injector, means for separating said molten metal from said oil, means for withdrawing a portion of said molten metal and carbonaceous matter from said separating means, means for separating carbonaceous matter from said molten metal, means for reheating said separated molten metal and means for returning said reheated molten metal to said injector.

ROSS J. GAROFALO.

CERTIFICATE OF CORRECTION.

Patent No. 1,948,345 February 20, 1934.

ROSS J. GAROFALO.

It is hereby certified that error appears in the printed specification of the above numbered patent requiring correction as follows: Page 5, line 20, claim 14. for "holt" read hot; and line 84, claim 19, strike out the word "still"; and that the said Letters Patent should be read with these corrections therein that the same may confonn to the record of the case in the Patent Office.

Signed and sealed this 19th dav of June, A. D. 1934.

Bryan M. Battey (Seal) Acting Commissioner of Patents.