US3440020A - Catalytic conversion - Google Patents

Description

April 22, 1969 c. H. owl-:N

CATALYTIC CONVERSION Sheet Filed Oct. 16 1964 COMBUSTION GASES REGENERATOR GAS OIL.

FEED

EXTRACT FE TO PRODUCT RECOVERY ATTORNEYS CATALYTIC C CONVERSION Filed Oct. 16, 1964 Sheet 3 of 2 [COMBUSTION GASES To PRODUCT RECOVERY 1 REACTOR REGENERATOR STRIPPING FLUID 1 GAS on. 29 FEED J EXTRACT FEED AIR] 29 J FIG. 2

INVENTOR. C.H. OWEN A T TORNEKS United States Patent 3,440,020 CATALYTIC CONVERSION Charley H. Owen, Phillips, Tex., assignor to Phillips Petroleum Company, a corporation of Delaware Filed Oct. 16, 1964, Ser. No. 404,334 Int. Cl. B01j 9/12 US. Cl. 23--288 7 Claims ABSTRACT OF THE DISCLOSURE Two different feed materials are fed to the reactor of a fluidized bed catalytic cracker through a riser conduit which is divided into two separate and parallel conduits with at least one of the conduits having its outlet above the fluidized bed of the fluidized bed catalytic cracker reactor. In this manner two different charge stocks can be contacted with two different catalyst-to-oil ratios at two different temperatures.

This invention relates to a catalytic conversion of reactant materials such as hydrocarbons. In one aspect it relates to a method and means for catalytic conversion of hydrocarbons of differing properties at different conditions in a unitary process and apparatus. In one of its more specific aspects it relates to a method and means for the simultaneous and separate catalytic cracking of a hydrocarbon such as gas oil and an aromatic hydrocarbon such as the extract obtained by solvent extraction of the cycle oils resulting from such cracking operation.

It is known to crack hydrocarbon fluids catalytically to increase the quantity and quality of the gasoline or motor fuel product. In such operations a refractory heavy product is produced, for which there is little demand, and therefore this heavy product is usually returned to the cracking operation. It has been proposed to solvent extract this heavy recycle oil so as to remove therefrom aromatic hydrocarbons which are carbon formers and gas formers and to recycle the raflinate from this solvent extraction step to the cracking operation. It has also been proposed to employ two or more catalytic cracking zones, wherein feed stocks containing different concentrations of contaminating metals are separately cracked, to solvent extract the heavier oil from the cracking zone that treats the feed stock containing the least amount of contaminants, to pass the raflinate to the cracking zone wherein the feed stock contains a greater amount of contaminants and to pass the extract oil to a carbon black process. Such process increases the aromatic or extract oil production. The extract from the solvent extraction step constitutes a preferred feed stock for the manufacture of carbon black by the furnace process and a considerable quantity of such extract is consumed in the carbon black process.

In the catalytic cracking of hydrocarbons wherein more than one catalytic cracking zone is employed, it is usually considered desirable to crack residual hydrocarbons, such as topped crude, pitch, and/or other hydrocarbon fluids containing relatively large amounts of metal compound contaminants or other coke and gas-forming components, in a reaction zone employing catalyst which has been discarded from a catalytic cracking zone wherein distillate hydrocarbons, such as gas oils and recycle oils from the catalytic cracking process which contain relatively small amounts of metal compound contaminants or coke and gas-forming components, are contacted with a fresh or relatively little-used catalyst. The distillate hydrocarbons are generally more refractory than the residual hydro carbons and therefore these distillate hydrocarbons are usually catalytically cracked at a higher temperature than are the residual hydrocarbons. The raflinate from the solvent extraction step is usually added as a recycle stream 3,440,020 Patented Apr. 22, 1969 to the catalytic cracking zone wherein distillates are cracked.

The solvent extraction of the heavy cycle oils in the catalytic cracking of hydrocarbons has resulted in the production of extract stocks which are sometimes in excess of the requirements of the carbon black process; however, solvent extracting the cycle oils has so improved these cycle oils in the form of raffinate for the catalytic cracking process that the solvent extraction of these cycle oils is continued even though an excess of extraction has resulted. The excess of extract oil has been added to the catalytic cracking zone wherein distillates are cracked because the extract is quite refractory and requires cracking temperatures higher than those that are tolerated by the residual oils that are cracked in the cracking zone utilizing the used catalyst. When extract oils are added to the distillate oils in the clean catalyst cracking zone, it is necessary to increase the cracking temperature and thus operate at a compromise temperature between the optimum cracking temperature for the distillate oils and the optimum cracking temperature for the extract oils. In this operation the cycle oils will contain an abnormally large concentration of aromatics.

It is an object of this invention to provide a method for cracking an extract oil in a catalytic cracking process such that the distillate oil charge, the residual oil charge, and the extract oil charge can each be catalytically cracked at its optimum cracking temperature. Another object of this invention is to provide a method for the economic disposal of excess extract oils. Still another object of this invention is to provide a method for cracking an extract oil in a catalytic cracking process so as to provide a minimum concentration of aromatic components in the cycle oils removed from the distillate oil cracking zone. Other and further objects and advantages of the invention will be apparent to one skilled in the art upon study of this disclosure including the drawing and the detailed description of the invention.

FIGURE 1 of the drawing is a diagrammatic flow plan of one embodiment of the invention;

FIGURE 2 is a modification of the embodiment of FIGURE 1;

FIGURE 3 is a view along lines 3-3 of FIGURE 2; and

FIGURE 4 is a modification of the invention of FIG- URES 1 and 2.

Broadly the invention contemplates the modification of a fluidized bed catalytic cracker so that at least a portion of the feed to the cracker is reacted in dilute catalyst phase rather than in the fluidized bed and at a temperature substantially different from that of the fluidized bed. This is accomplished by dividing the riser conduit into two separate and parallel conduits with one of these conduits having its outlet above the fluidized bed of the reactor. The riser conduit can be divided into two conduits by positioning a smaller conduit concentrically within the riser conduit or by securing a partition longitudinally within the riser conduit. The invention thus makes possible the cracking of two different feed stocks simultaneously in a conventional fluidized bed catalytic cracker under different conditions of temperature and catalyst-tooil ratios.

In catalytic cracking wherein two or more catalytic cracking zones are employed, the cleaner catalyst is contacted with cleaner oil, cleaner with respect to contaminating metal compounds, and the dirty or metals-contaminated catalyst is contacted with the more metals-contaminated or dirty oil.

The extract oil is more refractory than the residual oil converted in the dirty oil unit or the distillate oils converted in the clean oil unit and therefore a higher cracking temperature is required for satisfactory cracking of extract oil. It has been shown that separate cracking of extract oil and gas oil results in a substantial increase in gasoline production and a substantial reduction in coke production over cracking a mixture of gas oil and extract. The increase in value of the products obtained from the separate cracking of extract oil has ranged from about $2 to $3 per barrel of extract oil processed. In some runs on mixtures of gas oil and extract, the dollar value of the total products was actually less than if no extract were present. This was because the operating conditions, e.g., temperature, were not optimum for either gas oil or extract. Furthermore, when a mixture of gas oil and extract oil is cracked, the cycle oils contain an abnormally high concentration of aromatics.

When extract is introduced with catalyst into a fluidized bed catalytic cracker as a separate stream wherein gas oil is being cracked by employing the modified apparatus of the invention, the extract can be cracked at a temperature of about 980-1050 F. whereas the gas oil is cracked at a lower temperature of about 925-935 F. When the extract is cracked at these higher temperatures, the aromatics in the product are in the gasoline boiling range so that the cycle oils are not contaminated with the aromatics. Thus, when operating according to the invention, the quantity and quality of the gasoline is improved and the cycle oils can be used for diesel fuel blending stocks. Aromatics are undesirable in diesel fuels.

Referring now to FIGURE 1 of the drawing, a hydrocarbon distillate such as gas oil, cycle oils, raflinate and the like is charged to a conventional fluidized bed catalytic cracker reactor via conduit 11 and riser 12. A measured amount of hot, regenerated catalyst is admitted to riser 12 from regenerator 13 via conduit 14, conduit 15 and valve 16. Riser 12 terminates in a flared end 17 containing a distribution grid 18. The flared end 17 of riser 12 is below the level of the fluidized bed 19 of catalyst in reactor 10.

A hydrocarbon fraction requiring substantially different operating conditions for optimum cracking, such as extract oil, is charged to reactor 10 via conduit 21 and riser 22. A measured amount of hot, regenerated catalyst is admitted to riser 22 from regenerator 13 via conduit 14, conduit 23 and valve 24. Riser 22 terminates in reactor 10 above the level of fluidized bed 19. Cyclone separators 25 and 26 return catalyst fines from the vapor space above the fluidized bed to the fluidized bed. Reactor effluent vapors are removed from reactor 10 via conduit 27 and passed to a product recovery facility (not shown). Stripping fluid such as steam is introduced to the lower portion of reactor 10 via conduit 28. Catalyst stripped of hydrocarbons is passed from reactor 10 to regenerator 13 via onduit 29 along with a combustion supporting medium such as air introduced via conduit 31.

The temperature of the outlet of riser 12 is detected by temperature-sensitive element (thermocouple) 32 and transmitted to temperature controller 33 by temperature transmitter 34. Valve 16 is opened by action of temperature controller 33 to increase the temperature of the outlet of riser 12 and is closed to lower the temperatrue of outlet of riser 12. The temperature of the outlet of riser 22 is detected by temperature-sensitive element 35 and transmitted to temperature controller 36 by temperature transmitter 37. Valve 24 is opened by action of temperature controller 36 to increase the temperature of the outlet of riser 22 and is closed to lower the temperature of the outlet of riser 22.

The apparatus of FIGURE 2 is the same as that of FIGURE 1 except that riser 12 is closed at the outlet end 17a and has outlet openings 38 around the periphery of the riser and both riser 12 and riser 22 terminate above the level of the fluidized bed.

FIGURE 3 illustrates the relationship of risers 12 and 22. Riser 22 is shown as being concentric with riser 12; however, this is not necessary and usually will not be the case because it is only necessary that riser 22 be inside riser 12.

FIGURE 4 illustrates a modification of two risers in a common conduit wherein a partition 39 separates the stream represented by area A from that of area B in the same manner as the wall of riser 22 separates the stream represented by area A from that of area B.

Conventional cracking catalysts such as synthetic or natural clays, bauxite, brucite, silica-alumina, and the like can be used in the practice of the invention. Conventional reaction conditions of temperature, pressure, space velocity and the like are applicable in the practice of the invention.

The following example may be helpful in attaining a clear understanding of the invention but should not be construed as limiting the claims unduly.

The data in the following table compares representative runs wherein Reactor A and Reactor B represent separate risers in an over-and-under catalytic cracker and wherein the extract oil was charged through one riser, and Reactor C represents a mixture of gas oil and extract oil passed through the risers of an over-and-under catalytic cracker. Cracking an admixture of topped crude and extract oil is not economical because of the difference in optimum cracking temperatures of topped crude and extract oil.

TABLE-COMPARISON OF CRACKING EXTRACT SEPA- RATELY AND MIXED WITH GAS OIL Reactor A Reactor B Reactor C Charge Gas oil, b./d. (barrels per day). 38, 000 API at 00 F..60 F 32. 6 Reaction temp, F 960 Cat/oil wt. ratio 1 0. 1 Residence time, see. 1 10 Conversion, percent 1 48 Extract, b./d .3, 000 API at 1 32. 6

BMCI Reaction temp., F 900 Cat./oil wt. ratio 28 l 6. 1 Residence time, see. 2 I 10 Conversion, percent I- 62 1 Admixture of 38,000 b./d. gas oil and 3,000 b./d. extract oil.

Practice of the invention as indicated by the results of Reactor A and Reactor B increased gasoline production about 168 b./d. as compared to the mixture treated in Reactor C. Practice of the invention also decreased the amount of coke produced by about 14 tons per day and decreased C and lighter production by about 7 tons per day.

The above runs demonstrate that operating variables such as temperature, catalyst-to-oil ratio and conversion of the topped crude and extract oil are quite different for optimum operation and that these variables can be controlled independently according to practice of the invention.

That which is claimed:

1. A catalytic cracking apparatus comprising, in combination:

a reactor chamber containing a fluidized bed of solid catalyst particles;

a regenerator chamber containing a fluidized bed of solid catalyst particles;

means to pass catalyst from said reactor chamber to said regenerator chamber;

means to remove combustion gases from said regenerator chamber;

a riser conduit extending vertically into said reactor chamber;

a partition wall positioned longitudinally in said riser so as to divide said riser into two separate conduits with one conduit extending above the terminus of the other conduit in said reactor chamber;

means to introduce catalyst from said regenerator and means to introduce a first hydrocarbon into one of said conduits;

means to introduce catalyst from said regenerator and means to introduce a second hydrocarbon into the other of said conduits; and

means to recover the products of the process.

2. The apparatus of claim 1 wherein the partition is a second conduit coaxially positioned in the riser conduit.

3. The apparatus of claim 1 wherein the partition is a vertical wall longitudinally positioned in said riser conduit parallel to a vertical plane passing through the longitudinal axis of the riser conduit.

4. A catalytic cracking apparatus comprising, in combination:

a reactor chamber containing a fluidized bed of solid catalyst particles;

a regenerator chamber containing a fluidized bed of solid catalyst particles;

means to pass catalyst from said reactor chamber to said regenerator chamber;

means to introduce a combustion supporting gas to the fluidized bed in said regenerator chamber;

means to remove combustion gases from said regenerator chamber;

a first riser conduit extending vertically into said reactor chamber and having its outlet end in said reactor chamber;

a second riser conduit positioned coaxially within said :first riser with its outlet end at a point above the outlet end of the first riser and above the fluidized bed;

means to introduce a first hydrocarbon to said first riser separate from said second riser;

means to introduce a second hydrocarbon tosaid second riser separate from said first riser;

a first valved means adapted to pass a measured amount of catalyst from said regenerator to said first riser separate from said second riser;

a second valved means adapted to pass a measured amount of catalyst from said regenerator to said second riser separate from said first riser;

a first temperature controller operatively connected to said first valved means;

a first temperature sensing means adapted to sense the temperature of the outlet of said first riser and pass a signal representative of said temperature to said first temperature controller;

a second temperature controller operatively connected to said second valved means;

a second temperature sensing means adapted to pass a signal representative of the temperature of the outlet of said second riser to said second temperature controller; and

means to recover vapors from said reactor chamber.

5. The apparatus of claim 4 wherein the first riser has its outlet end within the fluidized bed in the reactor chamber.

6. The apparatus of claim 4 wherein the first riser has its outlet end above the fluidized bed in the reactor chamber.

7. In a catalytic cracking apparatus comprising a reactor chamber containing a fluidized bed of solid catalyst particles, a fluidized catalyst supply source, a vertical conduit extending upwardly into said reactor chamber with its upper open end beneath the surface of said fluidized bed, means to pass catalyst from said supply source to said conduit, means to pass a first hydrocarbon charge to said conduit, means to remove vapors from said chamber, and means to remove catalyst from said chamber, the combination therewith of a pipe coaxially positioned in said vertical conduit having its inlet means separate from the inlet means of said conduit and terminating in an open end in said chamber above said fluidized bed; means to pass catalyst from said source to said pipe; and means to pass a second hydrocarbon charge to said pipe.

References Cited UNITED STATES PATENTS 2,719,114 9/1955 Lefl'er 23-28835 XR 2,735,803 2/ 1956 Leffer 23288.35 XR 3,05 3,75 3 9/ 1962 Slyngstad et a1. 2 3-28835 XR MORRIS O. WOLK, Primary Examiner.

D. G. CONLIN, Assistant Examiner.

US. Cl. X.R.

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