US2107269A - Hydrocarbon oil conversion - Google Patents

Description

' Feb. 8, 1938.- J. B. BARNES HYDROCARBON OIL CONVERSION Original Filed March 16, 1951 FURNACE 25 FRACTIONATOR FURNACE 56 INVENTOR JOHN B. BARNES BY F ozffi ATTORNE Patented Feb. 8, 1938 HYDROCARBON OIL CONVERSION John B. Barnes, Chicago, Ill., assignor, by mesne assignments, to Universal Oil Products Company, Chicago, 111., a corporation of Delaware Application March 16, 1931, Serial No. 522,865 Renewed March 4, 1936 to the primary heating zoneand the line leading the products from the primary heating zone to the primary reaction zone.

To assist-in more clearly defining the inven" tion and describing an operation comprised within its scope, the attached drawing is provided which shows diagrammatically a side'elevational view of an arrangement of equipment which may be used in efiecting some of its aims and objects.

Raw oil charging stocks typified by heavy hydrocarbon oil mixtures such as, for example, those obtained as residues when crude oils are stripped of their lighter fractions or relatively heavy distillates produced from similar crudes may be taken from line I by pump 3 through valve 2 and discharged into line 4 containing valve 5 or line 6 containing valve 1. Line 4 leads to secondary fractionator $6, hereinafter to be 2 Claims.

This invention relates to the treatment of hydrocarbon oils andrefers more particularly to the conversion of relatively heavy hydrocarbon mixtures into mixtures containing material amounts of hydrocarbons boiling within the range of motor fuels.

More specifically the invention contemplates the treatment under elevated temperatures and pressures of relatively heavy hydrocarbon fractions from petroleum and other naturally occurring hydrocarbons to produce therefrom substantial yields of motor fuel fractions of superior quality as regards their tendency to burn without knocking in the cylinders of internal combustion engines.

In one specific embodiment the invention com prises passing heavy hydrocarbon oils through'a heated zone, discharging the heated material into an enlarged reaction zone in which separation of vapors and nonvaporized liquids is effected, discharging the nonvaporized liquids into a vaporizing chamber under reduced pressure wherein further separation of vapors and nonvaporized liquids is efiected, discharging the nonvaporized liquids from the process, passing the vapors from thesecondary vaporizing zone to a primary fractionating zone to produce liquid refluxes to be returned to the primary heating zone and vapors which are combined with the vapors from the primary reaction zone to form a mixture which is further heated in a secondary heating zone, discharging the products of the second heating into a second reaction zone, again separating vapors and nonvaporized liquids which may be returned in part to the primary heating zone for further conversion and in part to a succeeding. secondary fractionating zone, passing the vapors from the secondary reaction zone into the secondary fractionating zone designed to produce vapors of desired boiling point range which may be cooled, condensed and collected and a plurality of higher boiling intermediate frac tions to be utilized as material for blending with the liquid products discharged from the vaporizing zone or returned in part to the primary heating zone for further conversion. The invention further comprises the injection of relatively cold raw oil at suitable points in the line of flow to reduce temperatures, such points of injection including the lower portions of the secondary fractionating zone, the line discharging refluxes from this equipment to the primary heating zone, the primary fractionating equipment, the liquid discharge line between the primary reaction. zone and the vaporizing zone, the combined feed line the raw oil asare admitted from thisline-may assist in fractionating the cracked-vapors from the secondary reaction zone of the process and be themselvespreheated and discharged through line l0 containing valve "in admixture with reflux condensates from the cracked vapors.

Line 6 constitutes a raw oil header having branch line 8 containing valve 9, line l0 containing valve II and line 12 containing valve I3. Line 8 containing valve 9 leads to line 10' containing valve H on the suction side of pump l6 which pump is preferably employed to return heavy liquid refiuxes from secondary reaction chamber 59 and fractionator fifi to primary heating zone 24. Line 60 containing valve 6| may provide a means of discharging nonvaporize'cl liquids from reaction chamber 59 into suction line 10' and line 10 containing valve H enables the admission of liquid r'efluxes from. secondary fractionator 66. lead from collecting pan 6! (typifying one of. any number of such devices that may be used at different levels in fractionator 66) to line 10 and 7B and thus to the suction side of pump l6. Line 62 containing valve 63 may branch from line 60 containing valve BI and enable the transferof liquid residuals either in whole or in part vfrom reaction chamber 59 to the bottom of fractionator G6 to assist in reboiling. Pump I6 which may be designated as the reflux pump for the secondary cracking stage of the process discharges through line ll containingvalve [8 into line 26 on'the discharge side of. combined feed pump I9.

Line l0 containingevalve H may permit the 7 described more in detail, and such portions of Line 68 containing valve 69 may i introduction of relatively cold charging oil into primary fractionator 40, the raw oil being preheated and stripped of its lighter portions and the effectiveness of fractionator being increased. Line l2 containing valve l3 may join with line 38 containing valve 3| conveying the liquid products from primary reaction chamber 28 to vaporizer 32, the introduction of raw oil in some instances serving to cool the discharge liquids to a degree sufficient to prevent continued reactions resulting in the deposition of coke in the line and evaporator. Line 14 containing valve l5- may branch from line [3 and convey cool raw oil to line 26 through which the products from the primary heating element 24 are passing, thus effecting a control of temperature at this point and providing a means of inhibiting undesirable side reactions which otherwise might occur in reaction zone 28. Combined feed pump I9 preferably takes suction on primary fractionator 40 through line 4| containing valve 42, heavy nonvaporized portions of the products entering this fractionator being thereby returned to the heating element for further conversion though a portion of this material may be diverted into reaction zone 28 through line 22 containing valve 23 to control coking reactions and insure the ejection of substantially liquid residues from reaction zone 28. Pump l9 discharges preferably into line 29 containing valve 2| so that a mixture of raw oil from line 6, reflux condensates from secondary reaction zone 59 and secondary fractionator 66 and reflux from primary fractionator 40 may pass in varying proportions into heating element 24 disposed in furnace 25,

Heating element 24 may be composed of tubular elements connected to produce a continuous coil and furnace 25 may be of any type found suitable for the transmission of heat thereto. During passage through the primary heating element temperatures necessary for cracking are preferably acquired by the oil mixtures, such temperatures being, for example, from 800 to 1000 F. more or less, at the exit of the heating element, the heated products passing preferably through line 26 containing valve 21 to primary reaction zone 28 which may be any arrangement of enlarged equipment inseries or parallel enabling the employment of prolonged reaction time in the conversion process. Pressures developed during the conversion period may be of the order of approximately 100 to 500 pounds per square inch in reaction zone28, suitable differentials being maintained at the entrance to the heating element to cause flow.

The reaction chambers of zone 28 may be provided with removable manheads 29 and 29 to permit cleaning at intervals andare preferably well insulated to conserve heat necessary for conversion reactions. The elements of reaction zone 28 are preferably provided with bottom outlet lines 30 cotaining valves 3| which release pressure so that vaporization may be effected in vaporizer 32 under substantially atmospheric pressure conditions. The vapors from reaction zone 28 may pass through line containing valve 46 with or without pressure reduction to a secondary heating zone to be described more fully later.

Vaporizer 32 preferably effects the separation of relatively heavy portions of the cracked products, these being released through line 33 containing valve 34 and passed through cooler 35, the cooled residue passing through line 36 containing valve 31 and passing to storage not shown after mixing with second stage refluxes from line 12 containing valve 14 as will also be described later. The vapors from vaporizer 32 may pass through line 38 containing valve 39 and enter primary fractionator 40 which preferably separates intermediate refluxes for further heat treatment which may be discharged through line 4| containing valve 42 topump l9 as already indicated, Vapors from this fractionator may pass through line 43 containing valves 44 and 49 under slightly superatmospheric pressure and pass either through line 41 containing valve 48 to join with the vapors coming from reaction zone 28 through line 45 or pass through valve 49 to pump 59 which may discharge into line 53 containing valve 54 leading to secondary heating element 55 disposed to receive heat from furnace 56. Pump 58 is preferably provided for raising the pressure on the vapors from fractionator 40 to any point.

desired for the secondary conversion stage but not above that pressure on the vapors in line 45 which pass intoline 5| containing valve 52 and join line 53 prior to its junction with the heating element.

In heating element 55 pressures maintained may be substantially lower than those maintained on primary element'24 being, for example, of the order of 100 pounds per square inch more or less. and temperatures employed may be substantially higher, being, for example, of the order of from 900 to 1200 R, such changed conditions being in general conducive to the formation of relatively large amounts of hydrocarbon compounds of a cyclic or closed ring character, which compounds have notably high anti-knock ratings when used as motor fuel.

The heated materials from element 55 pass preferably through line 51 containing valve 58 to secondary reaction zone 59 in which time for reconversions and reformations may be given, liquid portions being withdrawn. through line 60 as already indicated and vapors leaving through line 64 containing valve 65 to secondary fractionator 66. This fractionator may be of a construction known as bubble tray construction and be designed to effect an efficient separation of low boiling hydrocarbon fractions. Raw oil may be admitted from line 4, refluxes withdrawn through line 18 and intermediate or side cuts taken off through line 68 as previously described. Vapors of desired boiling point range may pass through line 15 containing valve 16 to condenser H which may cool and partially liquefy the entering products, these passing through line 18 containing valve 19 to receiver 80 in which liquids and gases may be segregated, the former being withdrawn to storage through line 83 containing valve 84 and the latter released through line 8| containing valve 82. The gas release may fur nish a convenient method of controlling pressure on preceding portions of the equipment.

To assist in controlling the boiling point range of the vapors issuing from fractionator 66, a pump 81 may be provided to take suction on a suitable portion of the end product liquids through line 85 containing valve 86 and discharge the same into the top of fractionator 66 through line 88 containing valve 89. A portion of the intermediate fractions produced as side cuts and bottom refluxes in fractionator 66 may pass through line 10 to blending pump I2 as permitted by the opening of valve 10", pump I2 discharging through line 13 containing valve "to the residuum run-down line 36.

The foregoing detailed description will serve to indicate the general operations characteristic of the process of the invention but since many other types and arrangements of equipment may be employed the specific description is not to be considered in a limiting manner.

As an example of an operation that may be conducted according to the process of the invention and results obtainable therefrom, the case of a 24 A. P. I. gravity Mid-Continent topped crude may be taken. The feed of this charging stock may be split so that approximately 20% of the same is admitted to the secondary fractionator, 75% to the primary fractionator and the remaining 5% to the line leading from the primary heating element to the primary reaction zone. The temperature maintained at this lastnamed point may be approximately 945 F. which is immediately cooled to approximately 900 F. before the products enter the primary reaction zone. Pressures maintained on the primary reaction zone may be 250 pounds. per square inch, the nonvaporized liquids being reduced to substantially atmospheric pressures for vaporization and the vapors reduced in pressure to approximately 100 pounds per square inch before admission to the secondary or substantially vapor phase conversion zone, in which case the vapors from the primary fractionator may be compressed to an equivalent degree. Temperatures employed in the secondary conversion zone may be of the order of 1050 to 1100 F. more or less and there may be produced as an overall yield a fraction of gasoline boiling point range equal to of the raw oil charged. At the same time there may be produced a yield of low viscosity fuel oil residuum equal to 20% of the charging oil, the remaining 20% being represented by losses in gas and coke, the latter being formed in minimum or negligible amounts. The gasoline fractions produced may be of a highly aromatic nature so that their benzol equivalent as determined in test motors may be as high as to or higher depending on the inherent character of the charging oil and the details of operation of the process.

The above example is given merely for purposes of illustration and is not intended as a limitation of my invention.

I claim as my invention:

1. A hydrocarbon oil cracking process which comprises subjecting the oil to cracking conditions of temperature and pressure and separating the same into vapors and unvaporized oil, flash distilling the unvaporized oil by pressure reduction, dephlegmating the flashed. vapors and returning resultant reflux to the cracking step, combining the flashed vapors uncondensed by the dephlegmation with the first mentioned vapors, heating the commingled vapors tovapor phase cracking temperature, dephlegmating the is raised to a cracking temperature, thence passing the oil in succession through a series of vapor releasing chambers, uniting vaporous fractions taken off from said chambers, subjecting the same to vapor phase cracking in an independent heating zone, separating the products of the vapor phase cracking step into vapors and residue, and directly returning the residue thus obtained to the initial heating zone.

JOHN B. BARNES.

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