US1843171A - Process and apparatus for hydrocarbon oil conversion - Google Patents

Description

Feb. 2, 1932. J. c. MoRRELl. ET AL 1,843,171

PROCESS AND APPARATUS FOR H'YDROCARBON OIL CONVERSION Filed Dec. 31. 1927 2 Sheets-Sheet 1 Feb. 2, 1932. J. c. MORRELL ETAL 1,843,171

PROCESS AND APPARATUS FOR HYDROCARBON OIL CONVERSION Filed Dec. 3l, 1927 2 Sheets-Sheet 2 l u k g8 8 Patented Feb. 2, 1932 UNITED STATES PATENT ori-ICE J ACQUE C. MORRELL AND OSCAR H. FAIRCHILD, F CHICAGO, ILLINOIS, ASSIGNORS TO UNIVERSAL OIL PRODUCTS COMPANY, OF CHICAGO, ILLINOIS, A CORPORATION OF SOUTH DAKOTA PROCESS AND APPARATUS FOR HYDROCARBON OIL CONVERSION Applicationled December 31, 1927. Serial No. 243,801.`

The present invention relates to improvements in process and apparatus for hydrocarbon oil conversion, and refers more particularly to a process and apparatus especially adapted for vapor phase cracking.

The invention has for its principal object the subjection of hydrocarbons to conditions of vapor phase cracking for the production of maximum yields of desirable lighter' hydrocarbons therefrom with a minimum production of coke and non-condensible gas loss. The invention has for another object the conversion of hydrocarbon oils under conditions of vapor phase cracking in such manner that the condensed overhead product produced in the process will be suitable for use as motor fuel and will have high anti-knock properties, surpassing in this respect the product of the present day liquid or liquid-vapor phase processes.

The advantage, according to the present invention, is that substantially all of the conversion preferably occurs under substantially atmospheric pressure, although it is to be understood that an degree of superatmospheric pressure may e employed.

The art of conversion of hydrocarbons while subjecting same to conditions of vapor phase cracking is old. Heretofore one of the chief difficulties encountered in cracking in the vapor phase has been the accumulation of carbon or coke in the cracking zones, which interrupted the free conduction of heat .and caused premature shut downs, the length of the runs in most instances being so short as` Ato render the process unprofitable from a commercial standpoint. It is the purpose and one of the functions of the present invention to obviate this diificulty, and the manner in which this is done seems to be new and novel to the art.

A feature of the present invention resides in the utilization of cracking elements which long study and experience have demonstrated are the most eicient for the purpose of crack- In one of the preferred modes of carrying out the present invention, hydrocarbon oil vapors released from a concurrently operatingy distilling or cracking process are subjected to conditions of temperature which cause conversion of said vapors in the vapor phase. This heat is imparted to the vapors while the latter are iiowing through an elongated passageway of restricted cross section, the heat being supplied through the walls of the element forming the passageway and confining the vapors. The heating zone; preferably take a form similar to the fornofthe passageways through which the vapor: are caused to travel for a purpose now to be described.

The vapor phase cracking operation is continued until the cracking compartments or passageways have accumulated sufficient coke or carbon resulting from the cracking reaction to interfere with eiiicient operation. The further introduction of vapors to the vapor passageways in which vapor phase cracking has been effected is interrupted, While simultaneously the further introduction of the heating medium to the former heating compartments, for instance, hot gases, is also interrupted. The passageways or compartments which had previously been used as vapor phase cracking compartments are now used as heating compartments, that is, hot gases or other heating medium is diverted thereto while vapors are diverted to ythe compartments Whlch formerly functioned as the heating passageways. Conversion of the vapors continues to-take place until suiiicient coke and carbon accumulates to prevent eilicient operation. The alternate passageway/s or chambers are then converted,

'as above described, andthe operation rg-f peated.

By means of the present invention, therefore, it is possible to secure the beneficial advantages of vapor phase cracking while obviating the objection of premature shut down due to coke formation, it'l being understood that the carbon accumulated in a vapor phase cracking passageway is dissipated by combustion when that chamber is alternately used as a heating chamber.

The utility of the invention as Well as other objects and advantages will hereinafter more particularly appear.

In the drawings, Fig. 1 is a diagrammatic elevational view of apparatus by which the objects of the present invention may be carried out.

Fig. 2 is a cross sectional view taken on line 2-2 of Fi 3.

Fig. 3 is an en arged vertical sectional view taken on line 3-3 of Fig. 1.

Referrin more in detail to the drawings, oil drawn rom any suitable source may be charged, for instance, under pump pressure, through the line 1 and diverted into l1ne 2 controlled by valve 3 or into the line 4 controlled by valve 5. That is, all or an regulated portion of the charge may be ed upwardly through the line 2 discharging into the dephlegmator 6 or all or any regulated portion may be passed directly through the line 4 to the heating coil 7 mounted in a furnace 8, which latter may bevheated by means of the burners 9. Assume, for the purpose of this illustration, that the oil is passed directly to the heating coil 7. While being passed through the heating coil it is raised to conversion temperature, passing out through the transfer line 10 controlled by valve 11 and discharging into the enlarged drum 12, which may act as a separator and/or conversion drum. In the drum 12 the vaporous products of reaction separate from the nonvaporous products, the vaporous products being released through the line 13, controlled by valve 14, discharging into the bottom of the dephlegmator 6 While the non-vaporous products of reaction may be withdrawn through the line 15 controlled by valve 16, discharging into the flash chamber 17.

While ascending through the dephlegmator 6 the vaporous products of reaction entering through the line 13 are subjected to the action of a suitable cooling medium whereby the insufficiently converted fractions condense and flow to the bottom thereof while the sufficiently converted vapors remain uncondensed, passing out through the line 18, controlled by valves 19, and if desired to a secondary fractionating tower from which the vapors pass out through line 21, being condensed in the condensing coil 22, the li uid being passed through the line 23 contro led by valve 24 into the receiver 25. The receiver 25 is provided with the usual liquid draw-ofi' line 26, controlled by valve 27, and with the non-condensible gas relief line 28 controlled by valve 29.

Returning to the dephlegmator 6, the reflux condensate collecting in the bottom of the dephlegmator may be withdrawn through the line 30, and by means of the pump 31 passed through the line 32, controlled by valve 33, merging into the line 4 whereby said reflux condensate is returned to the heating coil 7 for retreatment. The vapors released from the flash chamber 17 may pass through vapor outlet line 34, controlled by valve 35, the line 34 communicatin r with a line 36 in which is interposed va ves 37' and 38. Tn case it is desired to pass said vapors into the dephlegmator 6, the valve 37 is opened and the vapors permitted to pass through that branch of the line 36 which merges with the line 13, whereby said vapors are caused to pass to the dephlegmator 6. The non-vaporous residue from the flash tower 17 may be withdrawn through the outlet line 39 controlled by valve 40. Reflux collecting in the secondary fractionating tower 20 may bewithdrawn through the line 41, controlled by valve 42, and may be, if desired, returned to the heating coil 7 for the purpose of recracking.

All of the foregoing comprise elements of conventional type cracking processes and apparati, and we do not claim any. invention therein.

Now, referring to some of the features of the present invention, we provide a vapor phase cracker designated as a whole 43 (Fig. 1) and more particularly illustrated in Figs. 2 and 3. This vapor phase cracker 43 comprises a container 44 in which are mounted spaced side wall partitions 45, the ends of which are connected by the alternate end wall partitions 46 to provide two continuous separate parallel passageways 47 and 48, respectively. It is to be noted that the end wall partitions 46 are spaced a substantial distance above and below the Walls of the container 44 for the purpose of providing or forming the passageways 47 and 48. Communicating with each of the passageways 47 and 48 are a number of inlet pipes and outlet pipes, as will now be described. Communicating at `the lower left hand side of the passageway 47 and the passageway 48, and projecting through the wall 49 of the container 44 are two separate pipes 50, controlled by valve 51, the pipes 50 comprising branches of a main pipe 52. Similarly communicating with the passageways 47 and 48 at the other three corners of the container 44 are pipes, respectively designated as 53, controlled by valves/ 54 communicating with a main pipe 55, controlled by valve 56; branches 57, controlled by valves 58, which comprise branches of a main pipe 59 controlled by valve 60; and branch pipes 61 controlled by valves 62 which comprise branches of a main pipe 63. The purpose of providing the branch pipes 50, 53, 57 and 61, each communicating with each of the passageways 47 and 48, will now be explained.

Assume for the purpose of illustration merely that the passageways 47 are being used as heating zones, that is, hot gases of combustion may be introduced from a suitable source,

forI instance, a conventional ty pe furnace, through one of the pipes 50 leading to the passageway 47, the valve 51 being so manipulated as to prevent the gases from passing through the other branch 50 into passageway 48. Simultaneously with the introduction of the hot gases of combustion into the chamber 47, vapors in heated condition released from a concurrently operating distilling or cracking operation will be introduced through branch 53, which communicates with the passageway 48, the valves 54 being so manipulated as to divert the vapors into the proper branch while preventing the vapors from passing through the other branch 53. By this arrangement, the passageway 47 will be used as a heating zone, the heated gases of combustion passing in the direction of the arrows throughout the entire `length of the passageway 47 being removed for instance, through the branch 57, controlled by valve 58, which communicates with the chamber 47, the valve 58 being so manipulated as to cut out the other branch 57. During the passage of the heated gases of combustion throughout the length of the passageway 47 heat will pass through the walls 45 and 46, being imparted to the vapors Howing through the passageway 48 in the direction of the arrows. The gases and vapors are caused to have an alternate back and forth travel by means of the baffles 64. The vapors will be withdrawn through that branch 61 which happens to be communicating with the passageway 48, the valves 62 being manipulated in an obvious manner for this purpose.

It will thus be seen that the vapors during their passage through the passageway 48 will be subjected to conditions of vapor phase cracking whereby the desirable amount of conversion takes place. After the operation has been carried out to the point where suliicient coke and carbon has been accumulated and deposited on the walls 45 and 46 to interfere with the efficient operation of the process, by the obvious manipulation of the valves shown, the introduction of vapors to the vapor passageway 48 will be stopped, while simultaneously interrupting the introduction of hot gases of combustion into the passageway 47. Subsequent to this interruption, and by the further proper manipulation of the valves illustrated, vapors may now be introduced to the passageway 47, which heretofore. had been used as a heating zone, while simultaneously hot gases of combustion may be introduced to the passageway 48 which had previously been used as a vapor passageway. The coke and carbon which had accumulated during the preceding cracking operation will now be dissipated through the medium of combustion formed by the introduction of the hot gases directly in contact therewith, coupled with the introduction of small amounts of excess air for the purpose of re-combustion if necessary, it being understood that it is the function and purpose of the alternate operation, as described, to dissipate and remove the carbon formed during the preceding cracking operation without substantially interrupting the operation of the process and without a substantial decrease in yield.

'lo insure safety of operation and prevent the formation of an explosive mixture when the hot gases of combustion are introduced to the passageway which had previously been used as the vapor passageway, steam or other suitable vapor or gas may be introduced to the vapor chamber either prior to or simultaneouslv with the introductlon of the hot gases for the purposes of sweeping out any hydrocarbon oil vapors which are present therein. The steam may have a further beneficial eiect in assisting in the removal of the coke and carbon.

It may be desirable in some cases, for the purpose of temperature control to introduce hot products of combustion into the heating passageway at separated points throughout its length. For this purpose we may provide burners 65 mounted in combustion chambers 66, each burner in each combustion chamber being independently regulated by means of the damper or gate 67 adapted to close or open the aperture 68 in the wall 69 of the chamber 44.

The arrangement is such that the vapors may pass cmmter-current or concurrent relative to the passage of the heating medium, and an operation may be completely reversed by manipulation of the proper valves with a minimum of effort and with a minimum loss of time. This is of the utmost importance in securing maximum yield and extended operating time. As a matter of fact it is Within the scope of the invention and one of the main objects thereof to provide a process and apparatus capable of substantially continuous operation until it is necessary to shut same down for repair or replacement of parts. This is revolutionary in the conversion of hydrocarbons under vapor phase cracking conditions.

The process and apparatus exemplified in Figs. 2 and 3 of the drawings lnay be utilized in the cracking of hydrocarbon vapors from any source. For the purpose, however, of practical illustration we have thought it well to illustrate a few of a number of sources from which these vapors may be obtained. Returning to Fig. 1, the vaporous products of reaction released from the drum 12 may be removed through the vapor outlet 13 and by proper manipulat-ion of the valves 14, 37 and 38 any regulated portion or all of said vapors may be passed into the vapor phase cracker 43. 0r all or regulated portions of the vapors removed from the top of the primary dephlegmator 6 may be diverted through the line 7() controlled by valve 71 and passed to the vapor phase cracker 43. The passage of vapors removed from the top of the dephlegmator through a vapor phase cracker is possible where it is desirable to change the com/position of said vapors and impart thereto qualities, for instance, of increased antiknock character. By closing the valve 37 and opening valve 38, the vapors released during the flashing operation may pass from the p1pe 34 into the pipe 36 and from the latter into the vapor phase cracker- 43. Or, the conditions of operation may be so adj usted that all or a portion of the reflux condensate passing down through the reflux leg 30 may be diverted into the line 72 controlled by valve 73, said reflux flashing 1nto vapor due to reduction of pressure brought about by proper manipulation of the valve 73. The line 72 merges with the line 36. The heat exchanger 74 may be interposed in the line 59, passing to the line 19 or to the secondary fractionating tower 20 for the purpose of removing a portion of the heat of the vapors, said heat may be used, for instance, for heating the incoming charge.

It is to be understood that the diagrammatic illustration of the vapor phase cracker 43 together with its various inlet and outlet branches as illustrated in Fig. l is not ,intended to limit the broad concept of the invention as described above and as illustrated in Figs. 2 and 3. Hot gaseous products of combustion removed from the vapor phase cracker 43 may be passed back through. the line 75 into the furnace 8.

From the foregoing various combinations for vapor phase cracking will suggest themselves to those skilled in this art.

`We claim as our invention:

1. A process of vapor phase hydrocarbon oil conversion consisting in passing a wide shallow stream of hydrocarbon oil vapors through a heating zone in a serpentine, ribbon-like path, and heating the vapors to a vapor phase cracking temperature b passing a stream of gases of combustion t rough a similar path continuously adjacent the path of the. vapors in heat interchange relation therewith.

2. A process of hydrocarbon oil conversion consisting in passing a stream of hydrocarbon oil vapors into one side of a heating zone 'to occupy a portion thereof, passing a stream of combustion gases into the other side of said zone to occupy the remaining portion thereof in indirect heat exchange relation with said vapors, directing the vapors passing through said zone in a path comprising return loops projecting into the combustion gas side of said zone, and directing the combustion gases in a path comprising return loops projecting into the vapor side of said zone intermediate the return loops thereof.

3. A process of cracking heavy hydrocarbon oils in the vapor phase for the production of lighter condensible hydrocarbons which comprises vaporizing the heavy oil, passing the resultant vapors in a tortuous path through a heating zone, heating said vapors in said zone to a vapor phase cracking temperature by assing 1n heat exchange relation therew1th a gaseous heating medium moving in a path at all times arallel to the tortuous path of the vapors uring their travel through said heating zone, removing the cracked vapors from said zone and subjecting the same to dephlegmation and condensatlon.

4. A vapor phase cracking process for the conversion of hydrocarbon oils which comprises supplying hydrocarbon vapors to and passing the same in a tortuous path through a cracking zone, passin through a heating zone, adjacent sald crac ing zone a heating medium in a tortuous path corresponding to the path of said vapors, said medium being in heat exchange relation'with said vapors and sufficiently hot to heat the vapors to cracking temperature, continuing such passage of vapors and heating medium through said cracking zone and heating zones respectively until substantial amounts of carbon have deposited in the former, then diverting the supply of vapors into said heating zone and the heating medium into said cracking zone, and continuing the cracking operation in said heating zone.

JACQUE C. MORRELL. OSCAR H. FAIRCHILD.

Images