US1880836A - Process and apparatus for converting petroleum hydrocarbons - Google Patents

Description

Oc. 4, 3932. W. M. @Ross 4 PROCESS AND APPARATUSy FOR CONVERTING PETROLEUM HYDROCARBONS Filed March 1l, 1925 INTOR.

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LMO/W Patented Oct. 4, 1932 UNITED STATES Las WALTER M. CROSS, OF KANSAS CITY, MISSOURI, ASSIGNOB, BY MESNE ASSIGNMENTS, TO GASOLINE PRODUCTS COMPANY INC., OF WILMINGTON, DELAWARE, A CORPORATION OF DELAWARE PROCESS AND APPARATUS iZEOB. CONVEBTING- PETROLEUM HYDROCABBONS Application mea umh 11, 1925. serial 110,111,641.

This invention relates to improvements in a process and apparatus for converting petroleum hydrocarbons, and refers more particularly to a continuous process operated at relatively high pressure wherein hydrocarbon oils are subjected to a cracking temperature and pressure regulated to prevent any substantlal vaporization during the cracking reaction.

Among the objects of the invention are, to provide a process in which low boiling point or gasoline like products are obtained by utilizing the contained heat of the converted products to distill off the lighter fractions under reduced pressure in a separate evaporating zone and thereafter reducing the vapors to what is termed an end point gasoline y a properly regulated refluxing and condensing system; to provide a process which includes an automatic temperature control in the top of the reuxing column in order to definitely regulate the temperature of the overhead material passing from the column which is preferably in the form of a bubble tower ;4 to `provide a process, the novelty of which primarily lies in the utilizing of a portion of the contained heat of the cracked materials as they are withdrawn from the-zone of reaction to redistill the reflux condensate separated out in the retluxing or dephlegmating tower in a separate redistilling or reboiling stage. 4

The single drawin is a diagrammatic side elevational view of t e apparatus with parts broken away and parts in section.

Referring to the drawing, at 1 is shown a furnace in which are positioned the heating coils consisting of an -u yper preheating coil 2 and a lower coil 3. coils by means of burners shown at 4. Five is a reaction chamber; 6l is an evaporator; 7 is a dephlegmator or reuxing tower preferably of the Abubble tower type as diagrammatically shown in the broken away portion;

8 is a refiuxpondensate reboiler; 9 is a vcharging pump', 10 is a condenser or cooling box; and 11 is a gas separator.

Describing now briefly the operation, the charging stock, which may be of any desired character such as gas oil, kerosene distillate,

eat is applied to the fuel oil, refineryl slops or other cracking stocks, is introduced from any convenient source through the line 12 controlled by a 'valve 13, flowing to the suction side of the pump 9 through the pipe 14. The material is discharged from the pump through a line 15 into a closed coil 16 positioned into the top of the tower, or it may be bypassed by the automatic manipulation of the valve 17 through a mechanism di'agrammatically shown at 18 in the top of the tower whereby circulation through the coils 16 is only permittedwhen the temperature of the overhead material passing from the top of the tower is within a desired range. After passing the valve 17 or through the coil 16 as the case maybe, the charging stock proceeds through the .line 19 to the preheating coil 2 where it is brought just below acracking tempera- -ture after which it passes to the lower coil 3 where it is rapidlyy heated to the desired condition to e'ect a proper degree of reaction or cracking on being dischargedinto the reaction chamber 5 through the transfer line 20. The velocity of the oil passing through the heating coils and the rate of heating is controlled to prevent any. substantial degree of cracking in the coil, thus eliminating the objectionable carbon accumulation in the heating tubes. The time that the oil remains in the heating coils after it hasarrive'd `at a cracking temperature is of considerable importance, as it is this condition which causes diiiculty due to carbon accumulation. At the same time suiicient temperature must be given the oil in thecoils to produce the proper degree of reactionl in the cracking stage 5 which is entirely out of the heating zone and where loss of heat is prevented by heavy insulation. The reaction vchamber' 5 has removable end plates for cleaning purposes. The oil, `after conversion in the reaction stage, is discharged through the line 21 to the coil 22 positioned in the reboiler 8. From the coi-l 22 it passes through aline 23 at arev duced pressure into the evaporator 6. Thel valve 24 is interposed in the line 21 and a valve 25 in the line 23. The'pressure Lmay be released by either of these valves.. With the reduction of pressure, there is distllle'd'of 5 subjected to a dephlegmating or retluxing action in a bubble tower type of construction. The vapors percolate through a pluralitv of pools of decreasing temperature until'they are finally discharged from the top of the tower through the line 27 and are subjected to a final condensing action in the coil 28 positioned in the condenser box 10. The liquid distlnate passes through the line 29 regulated by a valve 30 to the gas separator 11 Where the gases are separated out and returned through a line 31 regulated by a valve 32'to'the burners 4. During the initial stages of conversion or during those periods of op-7 eration where there is not sulicient gas to furnish an adequate fuel supply of liquid or gases, fuel may be supplied from any con# venient extraneous source through the line 33 controlled by valve 34.*XThe distillate from the gas separator may be drawn off as desired through the line 35 bv manipulation of the valve 36.`

Returning now to the disposal of the reflux condensate which is separated out as liquid material" in the retluxing tower, this liquid,` which may be condensed in any of the successive pools, gravitates downwardly and is collected in the bottom of the tower where'it is drawn ol through the line 37 controlled by a valve 38 and directed to the reflux condensate reboiler 8. Here it is maintained at a definite level by means of an automatic liquid level regulating-device diagrammatically shown at 39. This control mechanism manipulates the valve 40 in the discharge line`41 o f the reby this liquidlevel regulator at a height sufcient to immerse at all times the coil 22 through which the hot oil from the cracking chamber is circulated. The heat from this hot, oil is transferred by conduction to the liquid condensate oil body in whichthe coil 22 is immersed, giving the liquid sucient temperature to distill oi asubstantial portion thereof vin the form of vapors which pass out through the vapor line 42 and are returned Vto the refluxing tower where they are combined with the vapors from the evaporator. The unvaporized material passes out through 'sis' theline 41 to a cooling coll 43 positioned in the condenser box 10 and this li uid is di-v rected through a line 44 controlled y a valve 45 back to the charging line 14 where it is recirculated with the charging 'stockfor retreatment in the system. If desired, the unvaporized material from thereboiler may be ypassed aroundthe cooling coil..and returned directly through the lines 46 regulated by a valve 47 and line 44 to the charging pipe 14. u The hydrocarbon material unvaporizqed by boilingl unit. The condensate is maintained` the reduction of pressure in the evaporating v stage 6 is automatically discharged by means of relatively heavy material such crease 1n temperature from the inlet totheQ outlet of the reaction chamber will'normally range from 50 to 100 F. Pressures in the heating and reaction stages are preferably maintained in excess of 500 pounds per square inch, normal pressures being from 600 to 800 pounds per square inch. On dischargefrom the reaction stage, the pressure is reduced to substantially atmospheric, which is maintained throughout the remaining units of the system. In the' treatment of gas oil of`30 to 32 Baum ravity under these operating conditions, a yield of from 50% to 70% of the original charging stock may be obtained,-

I the final product, collected as liquid distillate in the gas separator, being endpoint gasoline which requires but little refinement in the way 0f cleaning, purifying, decolorizing and'desulphurizing to make it a marketable product.

The system offers a decided improvement in the utilizatign ofthe contained heat of the oil, not only on vaporizing and distilling oli' the lighter products with a reduction in pressure in. the evaporating stage, but also the utilizing of the heat in the cracked products discharged from the reaction stage in redistilling the reflux condensate in a separate stage designated as a reflux condensate reboiler.y There is also a decided advantage in having this reboiling stage asa separate unit, as its parts are mechanically more available for repair than when positioned in the bottom of the refluxing tower; also, a unit may be constructed whi h is adapted to withstand pressure and temperature conditions reducing considerably the cost in constructing such a unit within the bottom ofthe dephle ating tower. It will be? noted that the re oiler is heavily insulated to prevent loss of heat through radiation.

I claim as my invention:

1. An improvement in the art of 011 conversion, whlch comprises the ste s of heating and cracking the oil without istlllation, releasing the pressure to cause the hghter fractions to distill oli' by reason of the contained heat of the oil, subjecting the evolved vapors to a refluxing action in a tower and passing the refiuxed condensate to a separate 'stage of distillation wherein it is subjected to a reheatin by Qcontained heat of all of the treated o1 sucient to drlve otf a conno p siderable portion of the lighter fractions, passing this distilled olf portion back to the refluxing tower for retreatment.

2. An improvement in the art of oil conversion for producing lighter from heavier hydrocarbons, which comprises the steps of subjecting the oil to cracking conditions of temperature and pressure in a cracking stage without distillation, releasing the pressure on the heated oil whereby the lighter fractions are distilled ofi', passing the evolved vapors to a refluxing condenser, passing the reiuxed liquid to a separate zoneof reheating wherein the material is brought to a boiling temperature by heat obtained from the converted materials finally discharged from the cracking stage, passing the vapors distilled from the lreheated vreflux back to the said reflux condenser for retreatment and withdrawing the unvaporized refiux condensate from the reheating stage.

3. An improvement in theart of oil conversion for producing lighter from heavier hydrocarbons, which comprises the steps of subjecting the oil to cracking conditions of temperature and pressure in a cracking stage imposing sufficient pressure therein to retain the oil substantially in liquid phase without distillation, releasing the pressure on the heated oil in an evaporating stage whereby the lighter fractions are distilled olf, passing the evolved vapors to a reflux condenser, passing the refluxed liquid'to a separate Zone of reheating wherein the material is brought to a boiling temperature by heat obtained from the converted materials discharged from the cracking stage prior to their introduction to the evaporating stage, passing the vapors distilled from the reheated reflux back to the said reflux condenser for retreatment and withdrawing the unvaporized re iux condensate from the reheating stage, and returning said unvaporized reflux condensate directly to the cracking stage for retreatment.

4. An improvement in the art of oil conversion for producing lighter from heavier hydrocarbons, which comprises the' steps of heating the oil to a conversion temperature at a relatively high pressure without distillation, passing the oil While in a heated state to a vaporizing stage of reduced pressure in which aconsiderable portion of the liquid hydrocarbons is distilled olf, subjecting the overhead product to a reiiuxing action and thence to a final condensation, passing all the refiuxed liquid to a separate stage of reheating wherein the heat for redistillation of the refiuxed products is supplied by the excess heat contained in the converted products discharged from the conversion stage and prior to their introduction into the vaporizing stage, Vwithdrawing the unvaporized products from the vaporizing and reiux reheating stages.

5. In an apparatus for producing lighter from heavier hydrocarbons by pressure conversion, the combination of heating and cracking means, vaporizing and refluxing elements serially connected to said cracking means whereby the converted oil is passed through the vaporizing element and vapors through the refluxing element subsequent to cracking, a reduction valve between the cracking and vaporizing stages whereby vaporization takes place with the reduction of pressure, a vapor line connected to they top of the reiuxing element, a condenser in said vapor line, a separate reflux reheater, a liquid oil line communicatingl between the bot-k tom of the reiuxing element and said reheater, a vapor line from the top of the reheater to the refiuxing element, and a closed heating coil within said reheater and interposed in the line communicating between the cracking means and the vaporizing element,

Yand liquid withdrawal lines for the vaporizof said stream of oil and a connection for'.

transferring vapors from said still to the refiux tower.

WALTER M. CROSS.

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