US2002160A - Process and apparatus for converting hydrocarbon oils - Google Patents

Description

M?? 21, 1935 .14. w. THRocKMoR-roN 002,160

I PROCESS AND APPARATUS FOR CONVERTING HYDROCARBON OILS Filed sept. 2, 19:55

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Patented May 2l, 1935- PnooEss AND APPARATUS Fon coNvimr- ING HYDROCABBON olLs John Wyckliffe Throckmorton, New York, N. Yt.;

assignor to Gyro Process Company, Detrol Mich., a. corporation of Michigan Application September 2, 1933, Serial No..687,986

13 Claims.

This invention relates to improvements in converting relatively heavy hydrocarbon oils into lighter hydrocarbon oils having the character-V heater and there raising it to a distillation temperature, after which the vaporizable and unvaporizable constituents are separated by evaporation. The vaporized constituents are cracked vin the vapor phase and immediately thereafter are quenched below active vapor phase cracking temperature by`being intimately mixed with a relatively cooler oil. The liquidconstituents are passed to a heater maintained under pressure where they are subjected to a viscosity breaking reaction which reduces the percentage of .heavy fractions and increases the vaporizable or lighter fractions therein. The quenched cracked products mixed with those discharged from the viscosity breaker are liashed at reduced pressure in a flash tower, after which the vaporized portion is subjected to fractionation and condensation and the liquid bottom is diverted as a fuel oil from the system.

Further improvement lies in the arresting or quenching of the cracked vapors discharged from the cracking stage by mixing them with a clean distillate withdrawn from the fractionating stage and substantially completely vaporizable` at the temperaturefand pressure conditions existing in the flash tower.

The process differs from conventional methods in that the percentage of vapcrizable products in the substantially tar free bottoms accumulated in the evaporator is increased in the viscosity breaking stage. Also the temperature of the vaporizable products separated in the evaporator and returned to the vapor phase cracking stage is controlled by introducing a portion of theclean recycle stock utilized as quench oil in the evaporator stage.

'Ihe single figure is a diagrammatic elevation of one form of apparatus in which my process may be operated.

In operation, relatively heavy oil, such as topped crude, is introduced through pipe I, and is charged by means of a pump 2, through the line 3, which is connected'into the fractionating column 4. In the fractionating column, or tower, the charging stock is mixed with the reflux condensate which mixture is drawn olf from the bottom of the tower 4 through pipe 5, and is charged by means ofpump 6 through a line 1 into a distillation or primary coil 8, positioned in the compartment 8 of a double furnace. This coil may be arranged in a bank of tubes in the convection and radiant sections of the furnace in order to obtain'the most efficient heating of the oil, though I prefer to use only convection heat as shown in the drawing.

Heat is supplied to the furnace by means of burners I0 or by any other suitable means. In the coil 8 the charging stock is raised to temperatures of from 700 optimum temperature of 850 F. is maintained at the outlet from the furnace. The oil thus heated in primary coil 8 in the -furnace 9 is discharged through a transfer pipe II controlled by a valve I2 and is discharged into an evaporator I3. In the evaporator the vaporizable are separated from the unvaporizable products, the former passing out through the vapor line I3, and the latter being drawn olf through apipe I4 connected in the bottom of the evaporator. The vapors passing out through the line I3 are directed through a vapor phase cracking or secondary coil I5, positioned in the furnace compartment I6. The vapors are heated to temperatures from 950 to l300 F., normal operating temperatures being approximately 1100 to 1200 F. The cracked products are discharged from the cracking furnace, passing through the pipe I1 into an arrester I8 where the temperature is reduced by bringing' the cracked vapors in intimate contact with a cooler oil supplied to the arrester through pipe I9. The cracking furnace is heated by burners diagrammatically shown by 20.

The oil used as a quenching medium, that is, for reducing the temperature of the cracked products, is a clean tar free distillate withdrawn from the fractionating tower through pipe 2|, passed thence through a cooler 22, and is collected in a working tank 23 from which it is withdrawn through pipe 24 and forced by means of a pump 25, through the line I9 into the arrester I8.

The substantially tar free liquid oil accumulated in the bottom of evaporator. I3 is withdrawn through the line I4 and charged, by means of a pump 26 through line 21 into a viscosity breaker or tertiary heating coil 28 positioned in compartment 9 of the furnace. This coil may comprise radiant heat and convection heat section, in order to provide for efficient heating. This relatively heavy oil `is subjected to the temperatures of the order of '100 to 900 F. in the viscosity breaking coil 28, after which it is discharged through the transfer pipe 28 regulated by means of a valve-30. This valve may be used to hold to 900 F., preferably an 10 through a vapor line 33, which is connected.

, collected as liquid Ydium to the vapors.

4 quenched cracked lclean distillate as a material .into the evaporator ture of the vapors backpressure'on the coil 23 when desired. The transfer pipe 2i connects to the discharge line 3| which directs the quenched cracked products from the arrester to a flash tower 32 wherein reduced pressures are maintained, or the transfer pipe 29 may be connected directly with the ash tower. Relative lower pressures are maintained in the flash tower than in the viscosity breaking coil and in the vapor cracking coil so that substantially complete vaporization ofthe quench oil is effected. In the flash tower, I eifect another separation of the vaporizable and unvaporizable products, the former passing overhead to fractionating tower 4 below-the line 3, through which the charge is introduced 4into the tower, thel charging stock thus acting as a reiluxing me- The liquid bottoms or fuel oil accumulated in the ash tower and containing the tar formed by the vapor phase lcracking is withdrawn through the pipe 34 and is, discharged by means of a pump 35 through pipe 36 into a cooler 31, from which the residue passes through line 38 controlled by valve 39 to storage,

'not shown.

It will be observed that I may introduce a portion of the cleandistillate quenching stock through line .60, controlled by valve 6I, into the evaporator, thus controlling in a measure, the temperature, volume and -composition of the vapors which pass through line I3 to .the -vapor phase cracking step.

Vapors' passing from the flash tower into the fractionating column 4 rise and in their passage therethrough are subjected to the refluxing action of a plurality of pools 0f oil maintained upon bubble trays diagrammatically shown by dotted lines in the tower. 'Ihe material still in vapor form at the top 0f the tower passes oif through the vapor line 40 to a vapor condenser 4| and is distillate in the separator 42 which is equipped with a gas relief line 43 regulated by a valve 44, and the distillate drawot line 45 controlled by a valve 48. A portion of `the distillate may be returned through the pipe 41 by the agency oi' the pump 48 tothe top of the tower as reiluxing medium.

In the event it is desired to charge the oil directly to the heating coil 3 instead of subjecting it to predisti-llation in the tower, a cross over line 49 is provided between the pipes 3 and 1. Valves l50 and 5 I- serve t0 control the flow through the' cross over and direct the charge directly to .the distillation heater 8 instead of to the tower 4. By the arrangement, a part of the charge may go direct to the heater and a part t0 the tower if desired.

As suggested, the invention lies principally in reducing the percentage of relatively heavy or high 'boiling point fractions in the bottoms drawn ou from the evaporator by subjecting the same to bottoms in aflash tower maintained under reduced pressure to separate the heavy tar and gums from the vaporizable constituents.

- Invention resides also in the use solely of a clean tar free distillate as a quench oil for the cracked vapors and the utilization of a portion of this to be introduced for controlling the temperacharged to the vapor phase cracking stage. I

a gravity of approximately 27.0

An illustrative run typical of the operation is as follows: a topped crude from an oil of the Mid Continent area of the United States, having A. P. I. was charged to the fractionating tower and there mixed with a cycle stock. 'Ihe mixture was heated in the furnace chamber 3 to a distillation temperature of approximately 750 F. The vaporizable and unvaporizable constituents were separated in the evaporator i3. The vapors were then cracked in the furnace i6 at temperatures in the neighborhood of 1100o F. and immediately thereafter cooled by being mixed with a cooler quench oil returned from the fractionating tower down to about 650 F. The bottoms from the evaporator were heated in the viscosity breaking coil '84 in the furnace chamber 9 to 850 F..and under a pressure of 200 pounds or above. On being discharged from the viscosity breaker the pressure in the oil was reduced and a combination of the quenched cracked products and the heated oil from the viscosity breaking coil was flashed under a' reduced pressure of from 10 to 80 pounds in the tower 32. The vapors released were fractionated and the motor fuel fractions condensed. 'I'he liquid bottom from theash tower was diverted from the system as marketable fuel oil meeting bunker C. specifications (according to U. S. Bureau of Mines Technical Paper No. 323B). The motor fuel distillate had an end boiling point of 420 F. and an antiknock rating of 85 (C. F. R. research method) Havingl thus described my invention, what I claim is:

1. The process of converting hydrocarbon oils comprising the steps of charging a mixture of relatively heavy oil and light oil to a .primary heating zone and there heating it to a distillation temperature, separating by evaporation the vaporizable and unvaporizable materials in an evaporating zone, cracking the vapors in a secondary heating or cracking zone, and inmediately thereafter reducing they temperature of the cracked vapors to below active 'vapor phase cracking temperature by quenching them with a. cooler hydrocarbon, heating in an elongated confined stream the unvaporized oil recovered fromthe initial separating zone to temperatures suiiciently high to increase the percentage 0f 'vaporizable material therein in a tertiary heating or viscosity` breaking zone, combining the quenched products dischargedfrom the secondary vapor cracking stage and the bottoms dischargedy from the tertiary heating stage and'ashing the mixture at reduced pressure in a flash zone, diverting the unvaporized oil from the system, subjecting the vapors sepsratedin4 the dash zone to fractionation in a fractionating zone and condensing the vapors.

2. A process such wherein pressure is as that described in claim 1, reduced between the'tertiary heating zone and the flash zone. as that described in claim 1,

up to 150 pounds are main- 3. A process such wherein pressures tained in the evaporating zone, pressures up to 50 pounds on the flash zone, pressures up to 75 pounds on the `secondary heating or vapor cracking zone, and pressures up to 400 pounds on the tertiary or viscosity breaking zone.

4. A process such as that described in claim 1 including the step of blending the heavy and light oils of the charge in the fractionating zone, withdrawing a selected clean distillate from said fractionating stage and utilizing it to quench the f introduced into oil vapors lecular cracked products from the secondary vapor cracking stage and combining a portion thereof with the oil in the evaporating stage to control thetemperature of the vapors charged to the vapor cracking stage, as well as the quality or percentage of cycle stock in the bottoms returned to the tertiary or viscosity breaking stage.

5. An apparatus for cracking hydrocarbon oils comprising primary, secondary, and tertiary heaters, an evaporator connected to the primary heater and by vapor and liquid lines to the secondary and tertiary heaters respectively, a hash tower connected to the secondary and tertiary heaters, a fractionating tower and condensing means serially connected to the hash` tower, areturn line from the fractionating tower to the discharge from the secondary heater and to the evaporator and a residue drawoi line from the hash tower.

`6. A process of converting hydrocarbon oils into hydrocarbons of lower molecular weight including the steps of passing hydrocarbon oil in an elongated conhned stream and heating it to distillation temperature in a primary heating zone, hashing the oil into vapors and unvaporized oil in an evaporating zone, withdrawing the vapors from the evaporating zone and passing them in an elongated confined stream and heating them to active vapor phase cracking temperatures in av conversion zone, withdrawing the cracked vapors from the conversion zone and immediately reducing their temperature to below an active vapor phase cracking temperature by contacting them with a sufiicient quantity of relatively cooler hydrocarbon oil in a reaction arresting zone, withdrawing the unvaporized oil from the evaporating zone, passing it in an elongated conhned stream and heating it to temperatures suhiciently high to produce an appreciable amount of lower boiling hydrocarbons in a viscosity-breaking zone, withdrawing the heated oil from the viscosity breaking zone, withdrawing the oil and vapors from the reaction arresting zone, introducing the oil from the viscosity breaking zone and the oil and vapors from the reaction arresting zone into a hashing zone maintained at a reduced pressure, and there separating the material thereinto and unvaporized oil, withdrawing the unvaporized oil from the process,` fractionating the oil vapors in a iractionating zone and recovering hydrocarbons of lower moweight from the fractionating zone.

'7. A process as in claim 6 wherein a selected side stream distillate is withdrawn from the iractionating zone and used as the oil introduced into A the reaction-arresting zone.

^ trol the evaporation therein.

8. A process as in claim 6 where a selected side stream distillate is withdrawn from the tractionating zone and a portion introduced into the reaction arresting zone to-reduce the temperature of the cracked vapors and another portion thereof introduced intothe evaporating zone to con- 9. A process as in claim 6 wherein the oil charged to the primary heating zone comprises rehux condensate withdrawn from the fractionating zone and fresh oil t0 be converted is charged to the fractionating zone.

10. An apparatus for cracking hydrocarbon oils comprising in combinations. hrst heating means, a viscosityl breakingheating means and a cracking heating means, an evaporator tower, means for passing oil-from said vfirst heating means tosaid evaporator tower, means for passing-vapors from said evaporator tower to said cracking heating means, means for passing oil from said evaporator .tower .to said viscosity breaking heating means, a reaction-arresting chamber, means for passing vapors from said cracking heating means directly to said reaction arresting chamber, a hashing chamber, means for passing oil from the reaction arresting chamber into the hashing chamber, means for introducing oil from said viscosity breaking heating means into said flashing chamber along with oil passed thereinto from said reaction arresting chamber, means for withdrawing from the process oil from said hashing chamber, a iractionating tower, means for introducing vapors from said flashing chamber into said fractionating tower, means for introducing reflux condensate from said Iractionating towe` into the reaction arresting chamber, a condenser, means for passing vapors from the fractionating tower to said condenser.

11. An apparatus as in claim 10 including means for introducing hydrocarbon oil into the fractionating tower and means for passing rehux condensate from the fractionating tower to said hrst heating means.

12. An apparatus as in claim l0 including gressively decreasing pressures in the order named.

J OHN WYCKLIFFE TIBOCKMORTON..

the cracking heating means,

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