US2050986A - Cracking of hydrocarbon oils - Google Patents

Description

Aug. 11, 1936. v A A ES 2,05%

I CRACKING OF HYDROCARBONOILS Filed April 12, 1935 2 Sheets-Sheet l ATTOR Aug. 11, 1936. v WALES 2,050,986

CRACKING 0F HYDROCARBON oILs Filed April 12, 1935 2 Sheets-Sheet 2 INVENTOR ATTORNEY Patented Aug. 11, 1936 FFHQE CRACKING OF HYDROCARBON OILS James A. Wales, Westmount, Quebec, Canada, assignor to McColl-Frontenac Oil Co. Limited, Montreal, Quebec, Canada Application April 12, 1935, Serial No. 15,981 In Canada April 2, 1935 4 Claims.

This invention relates to an improved process for converting relatively heavy or inferior hydrocarbon oils into lower boiling point products of 'a more valuable nature, the principal objects being to obtain an increased yield of the lower boiling point products and to improve the characteristics of the relatively heavier residual products obtained therewith.

The improved process comprises passing the oil through a suitable primary heating zone to a primary vaporizing zone where the reaction products are separated into vapors and residue, subjecting the vapors to primary and secondary fractionation thereby forming primary reflux condensate and a relatively lighter secondary reflux condensate, commingling theprimary reflux condensate with the residue in the primary vaporizing zone, passing the secondary reflux condensate through a secondary heating zone and thenv commingling it with mixed primary, refluxcon densate and residue drawn from the prim ary vaporizing zone, passing the so commingled products into a suitable reaction zone, passing liquid and vaporous reaction products from said reac.- tion zone to a secondary vaporizing zon e,'co mmingling vapors from the secondary vaporizing zone with vapors from the primary vaporizing zone and subjecting the commingledvapors to the aforesaid primary and secondary fractionar tion and finally condensing the dephlegmated vapors. V

Thisprocess, subject to observance of suitable temperature and pressure conditions hereinafter, specified, produces anexceptionally high yield of relatively light hydrocarbons due to the secondary cracking to which the, residue" from'th'e' primary vaporizing zone is subjected when corn-1 mingled, in the reaction chamber, with reaction products from the secondary heating zone. 1 This secondary cracking of the heavy residue from. the primary vaporizing zone also produces, as residue from the secondaryvaporizing zone, a. product which has a lower, viscosity for an equivalent gravity than" residue, produced by prior cracking processes. Thisloweri viscosity is a desirable property and represents a definite improvement in quality. The reaction products from the reaction chamber are fed to a secondary vaporizing zone in order to make possible the removal of the then highly cracked relatively heavy hydrocarbons in the residue from this zone. This is desirable since furthe r cracking; of such residue would result in coke formation.

carrying out the improvedprocess i is Con templated that residual oil withdrawn; iron; the;

secondary vaporizing zone may be subjected to further fractionation and the condensed vapors returned to the system commingled with the raw oil and/or as reflux to the primary and/or secondary fractionating zones. It is also contemplated that a portion of the residual oil withdrawn from the primary vaporizing zone may, if desired, be cooled and then fed to the lower section of the reaction chamber to prevent coke formation in this zone. v In order to assist frac- 1 tionation in the primary and secondary fractionating zones a portion of the 'secondary reflux condensate may be cooled and then introduced into the upper section of the primary fractionating zone and into an intermediate section of 15 the secondary fractionating zone. Fractionation in the secondary zone may be further assisted by returning to the upper section of this zone a portion of the condensed dephlegmated vapors derived therefrom. r

20 Proceeding now to a more detalled descrlptlon reference will be had to the accompanying drawings, in which Figure 1 is a diagrammatic representation of one form of apparatus which may be used in carrying out the improved process, and c Figure 2 is a view similar to Figure 1 but showing a slight modification.

In these drawings the primary heating zone is representedas a coil it contained in a suitable t furnace H. The raw' oil is fed to this zone 0 through supply line I, valve 2,;pu'mp 3, line A, heat interchanger 5, andline 6. During its passage through interchanger 5 the raw oil is heated by indirect heat exchange with relatively hot residual oil from vaporizing zone 30. Further heating of the oil to the desired conversion temperature under any desired pressure 'occurs'in zone l3, from whence the oil passes, through line l2 and valve l3, to a primary vaporizing zone I4, 40

preferably located in the lower section 'of fractionator 31. The vaporous products'from'zone l4 pass directly to 'fractionating zone 3|. The primary refluxcondensate' formed in fractionat ing zone 3! commingles with residual products in 45 zone It: and is passed therewith through line I5, valve l6, pump'll, line It, and valve ill to the upper portion of reaction chamber 25. A portion of the oil in line l8 may be fed to the lower section of the reaction chamber through line 19 and valve 8! and may be cooled, if desired, by passing same through line 81, valve 82, cooler 83, line 84, and valve 85, into the reaction chamber.

, Superatmospheric pressure conditions are preferably maintained inheating zone to, vaporizing zone I4, and fractionator zone 3|. The pressures in zone l4 and fractionator 3| may be substantially equalized with each other and may be substantially equalized with or lower than the pressure in the heating zone II].

The vaporous products from fractionator 3| pass through line and valve 46 to further fractionation inthe secondary fractionator 50. The relatively light desirable vapors are withdrawn from fractionator through line 5| and valve 52 and subjected to condensation and cooling in' condenser 53, products from which pass through line 54 and valve to a suitable receiver 56, from whence uncondensible gases are released through line 51 and valve 58. The distillate collected in receiver 56 is withdrawn through line 59 and valve 60. A portion of this distillate may be pumped through line 5|, valve 62, pump 63, line 64 and valve to the upper section of fractionator 50 to assist fractionation of the vapors contained therein. The secondary reflux condensate formed in fractionator 50 is conducted therefrom through line 61, valve 68, pump 69, line 10 and valve H to a secondary heating zone 12 for further conversion. Zone 12 is represented as a heating coil contained in a suitable furnace l3 and is preferably heated to a more severe conversion temperature than that employed in the primary heating zone l0. From zone 12 the reaction products are conducted through line 14 and valve 15 into line l8 where they are commingled with mixed primary reflux condensate and residues drawn from the primary vaporizing zone l4 and pass therewith into the upper portion of reaction chamber 25. The pressure employed in the secondary heating zone 12 may be substantially the same or higher than that employed in chamber 25. The liquid and vaporous reaction products formed in chamber 25 are conducted therefrom through line 26 and valve 21 to a second vaporizing zone 30 which is preferably maintained under a substantially reduced pressure relative to that employed in chamber 25 and wherein vapors may separate from residual products. v r

In Fig. 1 vaporizing zone 30 is shown as a section of fractionator 3| with a solid dividing wall between it and vaporizing zone 4 to preventcommingling of the liquid residual products in zones 30 and I4. In this case the vapors from both zones 30 and M commingle as they pass to the fractionating zone'3l.

In Fig. 2 vaporizing zone 30 is shown as a sepa-- rate chamber from which the vaporous products are discharged through line 42 and valve 43 to commingle, in fractionating zone 3|, with the vaporous products from zone l4.

Residual products formed in the secondary vaporizing zone 30 may be withdrawn therefrom through line 35, valves 36 and 31, heat interchanger 5, line 38 and valve 39 to further cooling and storage or may be withdrawn through line 35, valve 36, line 40 and valve 4| to any desired further treatment. In the latter instance the residual products withdrawn through line 40 and valve 4| may be delivered to a tertiary vaporizing zone and there separated into vaporous products and residue, the residue thus obtained being removed from the system and the vaporous products being subjected to dephlegmation and condensation and returned to the system with the raw oil charge and/ or as reflux in the primary or secondary fractionating zones.

A portion of the secondary reflux condensate from fractionator 50 may be passed from line 10 erably heated to conversion temperatures ranging from 850 F. to 920 F. under pressures ranging from to 350 lbs. per square inch. In the secondary heating zone 12 the reflux condensate derived from the secondary fractionating zone is preferably subjected to conversion temperatures ranging from 900 F. to 1200 F. under pressures ranging from to 750 lbs. per square inch. The pressure in the reaction chamber may be equal to or lower than the pressure in the secondary heating zone. The pressure in the primary and secondary vaporizing zones may be substantially the same as the pressure in the primary heating zone which is preferably substantiallylower than the pressures employed in the per square inch. It may be stated, however, that the range of temperattures and pressures mentioned herein is subject to considerable variation, it being possible to operate this process with pressures ranging from substantially atmospheric to higher pressures in the neighborhood of 2000 lbs. per square inch and with conversion temperatures ranging from a minimum of approximately 800 F. to a maximum of approximately 1200" F. Thefollowing is a specific example of the operation of the process when using a 27 A. P. 1. East Texas'topped crude as the raw oil which is supplied to the system through the supply pipe A temperature of 870? F. and a pressure of 150 lbs. per square. inch are maintained in the primary heating zone. 'This pressure is substantially equalized in the vaporizing, fractionating, con-, densing and collecting zones. Relatively light reflux condensate from the secondary fractionator.

with the pressure in the secondary heating element. The residual relatively heavy oil which has passed once through the primary heating zone commingled with the reflux condensate from the primary fractionating zone and is collected in the primary vaporizing zone at a temperature of about 800 F. and is then subjected;

to further conversion by being heated to about 870 F. by being commingled with the heated products from the secondary heating zone and.

then passing through the reaction chamber under conversion conditions. The commingling of these two streams of oil and vaporous products has the further desirable effect of preventing coke formation in the reaction chamber. The oil and vapors from the reaction chamber discharge at' a superatmospheric pressure of about 150 lbs.

per square inch into a secondary vaporizing zone, the vaporous products from which may commingle with the vaporous products from the primary vaporizing zone in the primary fractionating zone. The residual products from the secondary vaporizing zone may pass from the system at a temperature of about 800 F. through a heat exchanger or may pass to a further vaporizing chamber, the vaporous products from which may be condensed and returned to the system commingled with the raw oil charge or as reflux in the' primary or secondary fractionating zones. The residual product after cooling is a marketable fuel oil. This operation may yield approximately 55% of motor fuel having an anti-knock value of about 69 by the C. F. R. motor method. In addition about 37% of marketable fuel oil may be produced, the other products being uncondensible gas and relatively small percentage of coke or carbonaceous material.

Having thus described my invention, what I claim is:

1. A hydrocarbon raw charging stock cracking process which comprises passing the oil through a suitable primary heating zone to a primary vaporizing zone where the reaction products are separated into vapors and residue, subjecting the vapors to primary and secondary fractionation thereby forming primary reflux condensate and a relatively lighter secondary reflux condensate, commingling the primary reflux condensate with the residue in the primary vaporizing zone, passing the secondary reflux condensate through a secondary heating zone and then commingling it with mixed primary reflux condensate and residue drawn from the primary vaporizing zone, passing the so commingled products through a suitable reaction zone where further cracking of the mixed primary reflux condensate and residue is eifected under conditions tending to prevent coke formation, passing liquid and vaporous reaction products from said reaction zone to a secondary vaporizing zone, commingling vapors from the secondary vaporizing zone, with vapors from the primary vaporizing zone and subjecting the commingled vapors to the aforesaid primary and secondary fractionation and finally condensing the dephlegmated vapors.

2. A hydrocarbon raw charging stock cracking process which comprises heating the oil in a primary heating zone to cracking temperature under pressure, discharging the heated oil to a primary vaporizing zone maintained under substantially the same or lower pressure conditions, subjecting the vapors from the primary vaporizing zone to primary and secondary dephlegmation thereby forming primary reflux condensate and a secondary lighter reflux condensate, commingling said primary reflux condensate with the residue in the primary vaporizing zone, passing the secondary reflux condensate through a secondary heating zone in which said condensate is heated to a higher cracking temperature under pressure, commingling the said mixed residue from the primary vaporizing zone with the reaction products from the secondary heating zone, passing such commingled products into the upper portion of an enlarged reaction zone there effecting further cracking of the mixed residue from the primary vaporizing zone by direct heat interchange with the reaction products from the secondary heating zone and under conditions tending to retard coke formation, delivering the liquid and vaporous reaction products from the lower portion of the reaction zone into a secondary vaporizing zone maintained under lower pressure than the reaction zone, separating the reaction products into vapors and residue in the secondary vaporizing zone, removing said residue from the system, commingling said vapors with the vapors from the primary vaporizing zone and subjecting them to the aforementioned primary and secondary dephlegmation and finally condensing the dephlegmated vapors.

3. A hydrocarbon oil cracking process as set forth in claim 2 in which a portion of the mixed residue withdrawn from the primary vaporizing zone is delivered to the lower portion of the reaction chamber without previous commingling with the reaction products from the secondary heating zone, to assist in preventing coke, formation in said reaction chamber.

4. A hydrocarbon oil cracking process as set forth in claim 2 in which a portion of the mixed residue withdrawn from the primary vaporizing zone is cooled and then introduced into the lower portion of the reaction chamber without previous commingling with the reaction products from the secondary heating zone, to assist in preventing coke formation in said reaction chamber.

JAMES A. WALES.

Images