US2772213A - Hydrocarbon oil conversion process by catalysis and hydrogen donor diluent non-catalytic cracking - Google Patents

Description

H. G. M. FlSCHER Nov. 27,21956 Filed June 11, 1954 T we i TH zoF zQ5 E Hm W V Q 9v EU on |v 3 35m: 9 3 mm we 1v $9.2 e H 6 Iv $96 #6:

5m Al Al monmo Q MW. O I? v mm 8 v N7 vuv a f ZQEEQEQI J Tv o 20:50:25 mm 2 6m low 2 A! 6 T t N on a T a zmoomo .8 1 m w 46 3:51 EE 2 J $25.2? E26 594 2 Em:

Herbert G. M. Fischer Inventor y Q 4 004) Ahorney United States Patent 2,772,213 HYDROCARBON OIL CONVERSION PROCESS BY CATALYSIS AND HYDROGEN DONOR DILUENT NON-CATALYTIC CRACKING Herbert G. M. Fischer, Westfield, N. J., assignor to Esso Research and Engineering Company, a corporation of Delaware Application June 11, 1954, Serial No. 435,993

' 5 Claims. (Cl. 19649) The present invention relates generally to the conversion of hydrocarbon oils. It pertains particularly to a process and a system for converting heavy petroleum oils to lighter and more valuable products by catalysis and hydrogen donor diluent cracking.

Recently a process termed hydrogen donor diluent cracking (HDDC) has been proposed. In this process, heavy oil is upgraded by admixing it with a hydrogen donor diluent material that contains aromatic-naphthenic constituents, and thermally cracking the mixture. The donor diluent is a material such as a thermal tar boiling in the range of, preferably, 650 to 1000 F. having the ability to take up hydrogen in a hydrogenation zone and readily release it in the thermal cracking zone. The donor material is partially hydrogenated by conventional methods using, preferably, a sulfur insensitive catalyst like molybdenum sulfide. In this manner of hydrocracking of oils, the oil being upgraded is not contacted directly with the catalyst and does not, therefore, impair its activity by contamination. The amount of concomitant light gases and coke produced by this process is relatively small, usually being in the order of about 5 to This technique of HDDC is more fully depicted in copending application, entitled, Upgrading of Heavy Hydrocarbon Oils, by Langer et al., S. N. 365,335, filed on July 1, 1953.

The present invention, by application of the above method of hydrogen donor diluent cracking to heavy, low value hydrocarbons such as vacuum residua, tars, asphalts, etc., and by selection of a catalytic cycle stock as a source of hydrogen donor diluent, proposes an attractive combination process heretofore unappreciated. By use of a normally surplusage catalytic cycle stock as the donor diluent and by specific processing sequences, the HDDC process is advantageously integrated with catalytic cracking processes to yield a highly eflicient petroleum oil conversion process.

it is, accordingly, a major object of the present invention to convert hydrocarbon oils, particularly heavy petroleum oils boiling above about 1000 F., to lighter, more valuable compounds. Another object is to develop a method for processing petroleum oils typified by a minimum production of degradation products, e. g., light gases and coke. A specific object is to propound a proces for upgrading hydrocarbon oils having as essential features the steps of catalytic cracking and hydrogen donor diluent cracking of selected fractions of the oils. Further objects and advantages will appear more clearly as the attached drawing, depicting schematically a preferred embodiment of the invention and forming a part of this specification, is discussed in detail.

The attached drawing illustrates diagrammatically a preferred process adapted to achieve the objects of this invention.

Generally the objects of this invention are obtained by catalytically cracking selected gas oils to obtain products of high quality and heavy cycle stocks and partially hydrogenating a portion or all of the heavy cycle stocks. The hydrogenated cycle stock is then blended with a hydrogen deficient material such as a vacuum residuum andthe resulting mixture is thermally treated or cracked to obtain naphthas and light and heavy thermal gas oils.

" 2,772,213 Ce Patented Nov. 27, 1956 cause not all of the hydrogen introduced into the cycle stock is transferred, the cycle stock is upgraded by the residual hydrogen remaining after the HDDC treatment, and is an improved catalytic cracking feed stock.

This invention proposes a processing sequence in which a suitable fraction of catalytic cycle stock, preferably a fraction boiling in the range of 650 to 1000 F., is hydrogenated for use as a donor diluent during thermal cracking of petroleum residua. For optimum operation, as much hydrogen as possible is introduced into the diluent short of reducing its activity by complete hydrogenation of the polynuclear aromatics to naphthenes. This diluent is blended with residuum using as high a diluent concentration as possible consistent with the relative volumes of cycle stock and residuum available. After thermal cracking or treatment, the recovered diluent fraction, e. g., material boiling above about 650 F., is returned to catalytic cracking as an improved cycle stock rather than regenerated and returned to the donor diluent cracking stage as is customary in normal HDDC operations.

As is known by the art, as the aromatic to naphthene ratio of a catalytic feed stock increases, cracking quality decreases. In the present invention, the residual hydrogen remaining in the cycle stock after HDDC serves to improve the quality of the cycle stock as a catalytic cracking charging stock by substantially decreasing its aromatic to naphthenic ratio.

Although the present invention is applicable to any type of crude oil, distillate or residual fractions therefrom, or mixtures thereof, it is most advantageously applied to the processing and converting of crudes that normally yield high percentages of residual fractions. As will be seen, in the practice of this invention, each fraction of an oil is selectively processed under conditions designed to secure optimum yields of motor gasolines and of middle distillates suitable for fuels for home or industrial heating, for use in diesel engines or gas turbines, etc.

For convenience, the pertinent operating conditions applicable to the following example are summarized in Table I. Referring now to the drawing, a crude enters the process by line 1, is heated in furnace 2 to a suitable temperature, and transferred to an atmospheric fractionation column 4 by line 3. Light gases are removed from the column overhead by line 5, a naphtha fraction and a heating oil fraction are removed by lines 6 and 7 respectively. Line 8 removes a gas oil fraction, boiling in the range of about 650 to 900 F. and designated as feed for catalytic cracking. The naphtha, heating oil and gas oil fractions can, of course, be further processed by conventional methods such as hydrofining, stabilization, blending, etc., to obtain commercially salable products.

Advantageously, the heavy portion of the naphtha can be subjected to processes such as hydroforming to increase the quality and octane rating of the gasoline product and to, concurrently, produce hydrogen. This hydrogen can then be used to hydrogenate the diluent, as is hereinafter described. With proper selection of operating conditions and feed stocks, the process, including the hydroforming step, may be made to be substantially balanced as to hydrogen production and consumption. If a crude source does not, however, supply a sufii-cient amount of hydrogen, then extraneous hydrogen is used.

Line 10 removes the residuum from the fractionation 3. tower and transfers it to a furnace 11 wherein it is reheated to a suitable temperature for further separation. From the furnace, the residuum is transferred by line 12 to a vacuum distillation unit 13. Further gas oils are removed from the residuum by the vacuum distillation and are blended with the material in lines by line 14. Heavy vacuum residuum boiling above about 1000 F. is removed from the vacuum tower by line 15. It is to be appreciated that in certain applications, there will be no need or justification for a vacuum distillation unit. In such a case, the atmospheric bottoms can be transferred to the HDDC unit.

The gas oil in line 8 is mixedv with thermal gas oil, obtained as hereinafter described, in line 16 and passed to a catalytic cracking unit 17. If desired, other catalytic cracking feed stocks may be admitted to the process by line 18. Suitable tankage may be interposed at this point to collect and blend these various feed streams to the catalytic cracking unit to add operating stability to the process.

Any conventional catalytic process is suitable for the purpose of this invention. Such a catalytic process may have a fluid bed, a fixed bed or a gravitating type of bed. A fluidized catalyst bed reactor with a fluid bed regenerator (not shown) is preferred and is used as the catalyticprocess in this example. The effluent from the catalytic cracking unit is transferred to a fractionation column 20 by line 19. Lines 21, 22 and 23 remove light gases, naphthas and heating oils respectively, from column 20 as products of the process. Line 24 removes a cycle stock boiling in the range of about 650 to 1000 F. and designated as feed to a hydrogenation unit 30, In

, some instances it may not be necessary to hydrogenate all the cycle stock to serve as a diluent during HDDC. Thus, lines 25 and 25a may be used to recycle a portion of this cycle stock to the catalytic cracking unit. A portion or all of the excess cycle stock may be removed from the process as product by lines 25 and 25b.

Broadly, any material boiling above the gasoline range from the catalytic cracking unit will serve as a hydrogen donor diluent after partial hydrogenation. In certain applications or with particular feed stocks, it may be desired to use as a hydrogen donor diluent fractions boiling above the preferred diluent boiling range in order to maintain heat and material balances and/or to obtain optimum product distributions. It is to be understood that although the preferred donor diluent boiling range is from about 650 to 1000 F., other diluent boiling ranges can be satisfactorily used. For example, when heart cut recycle catalytic cracking is practiced, the diluent boiling range can be 900 to 1050 F. It shouldbe noted that as the boiling point of a selected diluent increases, its aromaticity will increase and thus its ability to take up and to transfer hydrogen will increase;

Bottoms areremoved from fractionator 20 by line 27; Although it is not shown, a separation step can be incorporated at this point to concentrate the catalytic solids. remaining in the bottoms, as is customary in some processes. ing process Without such a separation step. A portion of' the bottoms, or slurry oil, if a separation step be used, may be recycled to the cracking unit by line 27a. It is desirable to remove by line 27b a portion of the bottoms as purge to prevent an excessive build-up of contaminants in the system.

Generally, a petroleum oil process can consume roughly about 840% of the material processed as fuel to'supply heat. As the process of this invention minimizes the amount of degradation and low value products produced, this process can be made to be substantially balanced as However, it is known to operate a catalytic crack-- tov fuel requirements. The light gases produced will oils existing beyond this requirement can be recycled substantially to extinction.

The material to be hydrogenated is transferred toa hydrogenation unit 30 which is supplied by line 31 withhydrogen from a source not shown. Conventional operating conditions are used during the hydrogenation and it is preferred to use a relatively sulfur insensitive catalyst such as molybdenum sulfide or cobalt molybdate. Line 32 removes tail gases from the hydrogenator, a portion of which may be recycled byline 33.

The conditions are so chosen that the diluent is only] partially hydrogenated for it has been found that complete hydrogenation greatly reduces the effectiveness of the donor diluent. The. diluent should pick upenough easily removable hydrogen. to be efiective as a donor, but

not enough to approach saturation or to convert it substantially to naphthenes. However, the degree ofhydrogenation used in this invention is generally higher than that normally used inHDDC operations.

The partially hydrogenated donor diluent is transferred via line 34 to the HDDC unit 38. The hydrogen-deli cient material to be upgraded is supplied tothe'unit by line 35. Thishydrogen deficient material will be-composed primarily of the vacuum residuum supplied by line 15. However, it maybe desired in some applications to also subject other low value materials to HDDC.

These can be admitted to the process by line 26.-; The

relative proportions of diluent and residuum used will depend. upon the degree of hydrogenation of the diluent,

the amounts of the materials available and like factors.

The resulting mixture is passed to furnace 36, wherein it is. heated to a; conventional; thermal. cracking temperature, e. g., 750 to 1000" F. under a pressure to main: tain the mixture substantially in the liquid state. From the furnace, the heated mixture is transferred by line 37 to a soaking or time drum 38, wherein the mixture is held for a. suflicient period of time to allow the crack-:; l ing and hydrogen exchange to' take place to the degree desired. In some cases, such as in vis-breakingtypeop erations, a soaking drum may not be required.

After the thermal cracking, the cracked mixtureis transferred to a fractionation tower 40 by line 39'. Light, V

larly suitable as a charging stock to the catalytic crack: Bottoms boiling above about 1000 F. are reing unit. 7 moved from fractionator 40 by line 43, a major portion of which may be recycled for. further treatment. It is desirable, however, to purge or bleed oifla portion of.

the contents. :of line 43 by line 44 in order, to prevent excessive buildup of contaminants in the system and to provide fuel to the process.

An attractive alternative processing scheme is to pass the product from the HDDC unit directly to fractionator- 4 by lines 39, 45 and 3 to be separated-therein whereby fractionator 40 is eliminated.

To further elucidate this example, Table I summarizes operating conditions pertinent to the presentinvention and presents a specific example of operating conditions.

Example 1 of Table II lists the products obtainable by stock when conventional processing techniques are used,

c. g., primary fractionation, vacuum distillation, andjcatalytic cracking of the virgin gas oil with heartcut recycle.

By comparison of the two examples-,theadvan'tages ob-' tainable by, practice of the present invention are readily Y apparent. It can be seen that this invention results in a 95% decrease in the amount of residual oil produced.

TABLE I Range Example Catalytic Cracking Conditions, Fluid Unit:

Catalyst Temperature, T. Pressure, p. s. i. g Feed Rate, WJHn/W Catalyst/oil ratio 430 F. Conversion per pass Vol. percent Hydrogenation Conditions:

Catalyst Temperature, F Pressure, p. s. i. g Throughput, V./V./hr Hz Consumed, S. C. 1?./

bbl. diluent. HDDC Conditions (Coil and] or Drum)- Silica Alumina.

Nickel Tungsten Sulfide. 650.

Diluent/ Oil Ratio 1.2.

Diluent Boiling Range, F 650 to 1,000.

430 F. Conversion per 45.8.

pass, Vol. percent 1 430 F. Conversion is defined as: 100 vol. percent feed-vol. percent products boiling above 430 F., based on fresh feed.

TABLE II 14. 1 2. 187 7 +10 Flash, F +80 Example Example 1 2 Products, percent based on Feed:

Light Gas, 03-, Wt. percent- At-mospheric fractionator 0. 1 0. 1 Catalytic Unit fractionator- 4. 6 3. 7 HDDC Unit iractionator 2.

Total 7. 2 3.8

Naphtha, C4- 430" F., Vol. percent- Vir in 7. 5 7. 5 25. 3 l9. 9 19. 4

Total 52. 2 27. 4

Heating Oil, 430-650 F., Vol. percent ir in l7. 5 l7. 5 Catalytic 11. 2 8. 8 HDDC 16. 7

Total 45. 4 26. 3 1,000t F.+Bott on1s (Inc. Bleeds), Vol. percen Catalytic (Heavy Cycle Stock) 1. 1 O. 9 HDDC 0. 9 Vacuum 41 Total 2.0 41. 9

Coke (including catalytic carbon) 8. 5 6. 6

Internal Flows, Vol. percent based on feed:

Gas Oils to Catalytic Unit, 650 to 1,000 F.-

Source: Virgin 34. 5 HDDC Unit 1 50. 9

Total 85. 4

Diluent to Hydrogenator, 650 to 1,000 F 48 Vacuum residuum to HDDC Unit, 1,000 F.+ 41

Total 89 1 Includes diluent recycled.

Although the above example depicts the present process as initiating with the separation of a. whole crude, the process is not limited thereby. The catalytic cracking charging stock can originate from any convenient source and the hydrogen deficient material upgraded in the HDDC unit can include tars, asphalts, extracts, shale oils, coal tars, pitches, whole crudes, residual and distillate fractions therefrom, or mixtures thereof,

Having described the invention, what is sought to l protected by Letters Patent is succinctly set forth in t1 following claims.

What is claimed is:

l. A process for converting hydrocarbon oils Whi( comprises catalytically cracking heavy distillate oils 1' a catalytic cracking zone under catalytic cracking co] ditions, separating from the efiluent therefrom a cyc stock, partially hydrogenating said cycle stock in a hj drogenation zone under hydrogenation conditions to 01 tain a hydrogen donor diluent, admixing said hydroge donor diluent with a relatively high boiling heavy oi cracking the mixture in a thermal treating zone und: non-catalytic hydrogen donor diluent cracking cond tions, separating from the thermally treated mixtln thermal gas oils including spent hydrogen donor diluer and passing said thermal gas oils to said catalytic cracl ing zone to form at least a portion of said heavy distilla1 oils.

2. A process for upgrading hydrocarbon oils compri ing catalytically cracking a petroleum oil :boiling in t1: range of 650 to 1000 F. in a catalytic cracking zon separating the eflluent therefrom into at least produ fractions boiling in the naphtha and heating oil range a cycle stock fraction boiling in the range within tl limits of 650 to 1000 F. and bottoms boiling aboi 1000 F., partially hydrogenating at least a portion said cycle stock in a hydrogenation zone, to obtain hydrogen donor diluent, admixing said hydrogen don: diluent with a hydrogen deficient oil boiling above abol 1000 F. in a proportion in the range of 0.25 to 2 V0 umes diluent/volume of oil, thermally treating the n sulting mixture at a temperature above 750 F. in non-catalytic thermal cracking zone, separating from tl: efiluent from said thermal cracking zone into furthc product hydrocarbons and a recycle fraction includir spent hydrogen donor diluent boiling in the range 4 about 650 to 1000 F., and returning said recycle fra tion to said catalytic cracking zone to be treated therei along with the said petroleum oil.

3. The process of claim 2 wherein said petroleui oil boiling above about 1000 F. comprises a vacuui residuum and a bottoms fraction obtained from the e fluent from said thermal cracking zone.

4. A method of processing petroleum oils which con prises separating a crude oil into at least product hydr( carbons, gas oils and residuum boiling above about 1000 F., catalytically cracking at least a portion of said g2 oils along with a thermal cycle stock, obtained as hen inaiter described, separating the catalytically cracked 0 into at least further product hydrocarbons, catalytic cycl stock and bottoms, partially hydrogenating at least portion of said catalytic cycle stock, admixing the h drogenated material with said residuum, thermally cracl ing the resulting mixture at a treating temperature abov 750 F., under non-catalytic hydrogen donor diluer cracking conditions, separating the thermally cracke mixture into at least a still further product hydrocarbon thermal cycle stock which includes partially dehydn genated products from said hydrogenated material an residue, and recycling and admixing said thermal cycl stock with said portion of gas oils to be catalyticall cracked therewith.

5. The process of claim 4 when said thermally cracke mixture is admixed with said crude oil and the resultin mixture is separated in a common separation zone.

References Cited in the file of patent UNITED STATES PATENTS 2,426,929 Greensfelder Sept. 2, 194 2,459,465 .Smith Jan. 18, 19 2,467,920 Voge et a1. Apr. 19, 19 2,620,293 Blue et al. Dec. 2, 195

Claims (1)

1. A PROCESS FOR CONVERTING HYDROCARBON OILS WHICH COMPRISES CATALYTICALLY CRACKING HEAVY DISTILLATE OILS IN A CATALYTIC CRACKING ZONE UNDER CATALYTIC CRACKING CONDITIONS, SEPARATING FROM THE EFFLUENT THEREFROM A CYCLE STOCK, PARTIALLY HYDROGENATING SAID CYCLE STOCK IN A HYDROGENATION ZONE UNDER HYDROGENATION CONDITIONS TO OBTAIN A HYDROGEN DONOR DILUENT ADMIXING SAID HYDROGEN DONOR DILUENT WITH A RELATIVELY HIGH BOILING HEAVY OIL,

Images