US2874093A - Combination fluidized solids process for producing fuels and chemicals - Google Patents

Description

J. F. MOSER, JR COMBINATION FLUIDIZED SOLIDS PROCESS FOR Feb. 17, 1959 PRODUCING FUELS AND CHEMICALS Filed Dec. 8, 1954 FUELS PRODUCT QUENCH RECOVERY BURNER VESSEL R E E0 0 U U. 7 Hr F G W Al mm flnunnnn U 2 L F B m f .l 9 m W m 6 A E W v E w m m. mm w T s m o .P HHH R W i Q P G E A s 5 m& B P S N ME v P A EK lS RE R HO V T CC 2 S S W #T. C M 6 v U 2 E4, K E mo w 1 J W F M r Ts (W A v v v LG W0 3 3 2 Inventor Attorney COMBINATI ON FLUIDIZED SOLIDS PROCESS FOR- PRQDUCING FUELS AND CHEMICALS Jann -nastier Moser, Jr'.-, Baton Rouge, La, assignor to Esfso kesearch and Engineering Company, a corporation -of Delaware"- Application December 8, 1954, Serial No. 473,775

3 Claims; (Cl. 20220) to the-present invention comprises heavy high boiling oilscontaining catalyst contaminants or refractory constit'u entsth'at render other methods of upgrading unattractive.- Such materials as petroleum residue, coal tars,-shale' oils,- asphalts, extracts, etc., are illustrative of suitable'charging stocksr According to this invention, a heavy oil, e. g-., avacuum-residuum, is contacted-in a fluidized solidsfuelscoking zone with particulate solids-maintained at a coking temperature in therange of 850 to 1200"F." The oil, upon contact with the solids, undergoes vaporization'and pyrolysis evolving relatively lighter hydrocarbon vapors anddepositingresidue on the solids. The time of'contact-'is -regulated-so that only'a part of the feed isconverted to vapors. The'solids along Withthe adhering remaining'portion'of the heavyoil are then withdrawnfrom the coking zone and mixed With additional hightemperature particulate solids in a chemicals coking zone, prefcrably 'a transfer line zone, whereby the resulting mixture has atemperature in the range of 1200" 'to 1600" This-results in the'conversion of the-remaining portions of- 'the feed tolight unsaturates and similar-compounds suitable as chemical raw materials; After having entrained solids removed, the vaporousconversion products fr'om-th'e fuels and'chemicals coking zones areseparately recovered as products." The solids separated fromthe chemical cokingzone efliuentare stripped and amajor portionof thestripped solids is circulated to thefuels coking 'zone to maintain the: coking temperature. The; remainder; is scirculated through aheating'. zone wherein they are heated, preferably: by partial combustion, to a temperature-100 to 900 F. above the temperature in the chemicals coking zone; Thfereheated solids are then returned to-the chemicalscoking zone.

It canbe seen that-this fluidized solids coking system provides, in essence, for the production of-fuelsat high solids-oil ratios or: with low solids holdingtimes inta fuels coking zonetso that the oil undergoing treatmentls not completely converted or cracked. The unconverted atentt) 2,874,093 Patented Feb. 17, 1959 feed 'on the solids is then 'completely'converted in-a-high" temperature chemicals coking zone; The process uti lizesa single inventory of circulating solidsyand' all'of the heat for the process is supplied by a common :heat ing system. The heating system: comprises, preferably, a burner wherein a portionof the carbon-containingpar ticles are partially combusted.

It is to be appreciated that-this'invention diverts'to fuels production the lighter, high hydrogen containing, fraction of thefeed' and divertsthe heavier, low hydrogencontaining, components to chemicals production. The present process isiparticularly adapted to handling a long residuum, i. e., a-residuum containing a substantial pro-- portion of constituents boiling below about 900 F; The

I fuels cokingzone is utilized to secure vaporization of the' lighter constituents of along residuum, and the-chemicals" coking zone is utilized to completely convert the'heavy low value ends of the residuum. The ease of controllingthe fraction converted" to fuels in the fuels "coking-"zone results in a very flexible process;

The heat transferring particulate solids used ilfjtll" practice of this invention comprise any finely divided,- substantially' catalytically inert, refractory solid such as pumiceQkieselg'uhr, spent catalyst; sand, metal andfre fractory jbed's, etc. Particulate coke produced bythe process is the preferred contactsolidl As this is 'aflfiuidized'solids process, the solids have, preferably, a size in-the range 0f740-500 microns, although in some instances-the solids may varyconsiderably beyond these limits,-e.*g., from 0 to 1000 micronsby'screen-analysis:

It-"is' an object of this-invention to devise a combine tion'fuels'and chemicals coking process whichutili'zesa single-inventory of circulatingcoke and a common coke heating system;

The drawing," attached to. and-forming aparhof this specification, will serve-to illustrate one preferredem' bodimentofthis invention." Thisfdrawing is for the purpose of illustration onlyand the invention is not to be limited thereto.

In brief compass, theobjects of'this'invention are .attained in the following'mannerz A charging'stockis con .t'a'cted in a fuels coking zone .withxafiuidized bed of high temperature particulate solids; preferably, finely divided coke. A relatively' low solids residence time is maintained in thecoking zone whereby only a portion of the charging stock is vaporizedand converted to gasiformprod ucts. Solids alongwith'adhering unconverted portions .ofthe charging stock are'removed from the fuels coking 'zone and transferred to'a chemicals coking zone wherein Referring now to the attached drawing, the major items of equipment shown are a fluid bed fuels coker 10, a transfer line chemicals coker 20 and a fluid bed burner vessel 30. The feed to the process, e. g., a vacuum re siduum, which may be suitably preheated to reduce the heat load of the system, is injected into fuels coker 10 via line 1. The injected oil is admitted to the vessel at a multiplicity of points and an atomizing gas may be used to suitably disperse the oil on the fluidized solids.

The fuels coker 10 has maintained in it a fluid bed of particulate coke in a manner well known by the art. The fuels coking temperature may vary from about 850 to 1200 F. Lower temperatures below 1,000 F. are used when heavy distillates suitable as catalytic cracking feed stock are desired and somewhat higher temperatures above 1,000 F. are used when lighter distillates, e. g., naphthas are desired as the primary products. An inert fluidizing gas, preferably steam, is supplied to the base of vessel 10 by line 2. Gas rates are adjusted to maintain fluidization velocities in the range of about 0.2 to ft./ sec.

A high solids to oil ratio, or conversely a low solids holding time, is utilized in the fuels coker such that only a portion of the injected feed is vaporized and converted. The amount of the feed converted in this zone is controlled primarily by the solids to oil ratio, but the coking temperature, fluidization gas rate, etc., may also be regulated to control the conversion. Generally, depending upon the nature of the feed, it is desired to convert approximately 30 to 80% of the feed in this zone to the products boiling below 1015 F.

The conversion products pass upwardly through the coking reactor to cyclone system 3 wherein entrained solids are removed from the vapors and returned to the fluid bed. This cyclone system may be external of reactor 10. The vapors are then separated by conventional means, e. g., fractionation, to obtain the desired liquid distillate products. As illustrated, a superposed scrubber 4 is used to quench and remove from the vapors the heavy high boiling ends. The heavy ends condensed from the vapors by this scrubbing are conveniently recycled via line 5 to the coker to be retreated therein. A portion of these heavy ends are cooled in heat exchanger 6 and transferred to the top of scrubber 4 by line 7 to serve as the quench oil. The initial boiling point of the heavy ends condensed in this arrangement is preferably in the range of 950 to 1150" F. The quenched vapors are removed from the scrubber 4 by line 8 and are transferred to further conventional processing, not shown. Solids along with the unconverted portions of the feed are transferred via line 9 to the chemicals coking zone 20. At the inlet of the chemicals coking zone, the wet solids are met with additional amounts of high temperature solids supplied by line 22, suflicient to raise the temperature of the mixture above 1200 F. The transfer line chemicals coker is preferably a vertically disposed, narrowly confined elongated conduit which may be suitably lined with refractory materials. A lift gas, preferably steam, although other gases such as light hydrocarbon gases may be used, is admitted to the base of the chemicals coker by line 11 in amounts suflicient to carry the suspension through the chemicals coker at velocities above 5 ft./sec.

At this high temperature, the liquid residue on the solids is rapidly converted to light unsaturates and similar compounds. To avoid undue thermal degradation of the conversion products, conversion times are held at a minimum. It is preferred to maintain the average vapor residence time of the conversion products before quenching in the range of 0.1 to 1.0 second. Stated somewhat differently, C conversions, on a coke free basis, of the liquid residue transferred to the chemicals coker on the solids range from about 20 to 50 Wt. percent. The solids in passing through the transfer line reactor are substantially completely dried with the carbonaceous residue deposited thereon forming coke which becomes a part of the solids. The effluent from the chemicals coker 20 is rapidly separated in a cyclonic separator 12. The conversion products are removed from separator by line 13. Preferably these products are quenched by a quench medium supplied by line 14 to below cracking temperatures, as they issue from the cyclonic separator. The quench medium used is preferably a heavy hydrocarbon oil and may be composed of the heavy ends removed in scrubber 4. The quenched products in line 13 are then sent to conventional processing equipment to recover the desired chemicals and hydrocarbon fractions. Crystallization, fractionation, absorption, adsorption, etc., processes may be used to effect the desired separation.

The solids removed by separator 12 are transferred by line 15 to a stripping vessel wherein occluded hydrocarbons are removed from the solids. A stripping gas, e. g., steam, is admitted to the base of the stripping vessel 16 by line 17 in amounts sufiicient to fluidize the solids therein. The gases are recovered overhead from the stripping vessel and transferred to the dilute solids phase in the fuels coker 10 by line 18. A major portion of the solids in the stripping vessel 16 are transferred by line 19 to the fuels coker to supply heat thereto. A cooler, steam generator or heat exchanger 28, is preferably used to partially cool the solids circulated to the fuels coker. This gives greater flexibility to the process in that the chemicals coker can be operated at higher temperatures and permits a higher solids/oil ratio to be used in the fuels coker without exceeding temperature limitations. Conveniently, steam can be generated in cooler 28 for use within theprocess.

The remainder of the solids in vessel 16 are transferred by line 21 to the burner vessel to be reheated. A lift gas, e. g., steam or air, is supplied to the contents of line 21 by line 23 to aid in the transfer of the solids to the burner vessel 30. The method of circulating the contact solids used in the method of the present invention forms no part of this invention. Reference is made to co-pending application by Whiteley and Molstedt, Serial No. 439,702, to illustrate one method of circulating solids applicable to the present invention.

The means of supplying heat to the process also forms no part of the present invention. As shown, a fluid bed burner vessel is used to partially combust the carboncontaining solids transferred thereto. Air or other free oxygen-containing gas is admitted to the base of the burner vessel 30 by line 24 in amounts sulficient to fluid: ize the solids therein and to support a partial combustion of the solids. By this means, the temperature of the solids is raised to a temperature 100 to 900 F. above the chemicals coking temperature. Entrained solids are removed from the flue gases by a cyclone separator system 25 located in the dilute solids suspension phase above the fluid bed. The flue gases are then vented by line 26. Normally an excess of coke is produced by the process and this excess may be removed by line 27. The reheated coke is transferred to the chemicals coker 20 by line 22 as previously described. A

Other means of supplying heated solid particles to the coking process can, of course, be used. Besides the fluid bed burner illustrated, gravitating bed burners or transfer line burners may be used to accomplish the partial combustion.. Other direct or indirect heat exchange means may be used if desired, such as shot heating systems, and, further, extraneous liquid or gaseous fuels may be preferentialy combusted in the burner to heat the solid particles.

The range of operating conditions applicable to the process illustrated in the drawing are summarized in Table I. Table I also presents a specific example of operating conditions. Table H presents a specific example of the products obtainable from the charging stock indicated when a process is operated in accordance with the example of Table I.

Pressure vapor outlet, p. s. i. g. Coking temperature, F 1,015 F. Conversion, percent Temperature fresh solids, F Coke/oil ratio 1 t 20 Average solids, residence time,

min. Fluidizing steam rate, wt. percent fresh feed. Bed density, lbs/C. F Transfer line chemicals coker:

Pressure outlet, s. i Avg. temperature, F Reheated coke/wet coke from fuels coker ratio.

Temperature of reheated coke-.. 1,400 to 2,000---- 1,650.

Lift gas rate, 0. F./lb. wet coke 0.05 to 1 0.48.

Solids loading, lbs/O. F 1 to 20 4.

Coke throughput, lbs./Min./ft. 1,000 to 20,000.-. 10,000.

Solids velocity, ft./sec Above 6 20.

Average vapor residence time 0.1 to 10 1 before quenching, sec.

Ca conversion; percent 10 to 50 30. Fluid Bed Burner:

Temperature, F 1,400 to 2,000 1,650.

Bed density, lbs/O. F 25 to 60 40.

1 1,0l5 F. conversion is defined as 100 vol. percent fresh feed minus products boiling above 1,015 F. less coke.

2 conversion is defined as wt. percent of products having three or less carbon atoms divided by 100 wt. percent fresh feed, on a coke free basis.

TABLE II Feed: South Louisiana long residuum 17.7 API gravity 4.8 wt. percent Conradson carbon 850 F. initial boiling point 0.1 wt. percent ash 1.51 H/C atomic ratio Products: percent on fresh feed CHEMICALS COKER FUELS (JOKER C wt. percent-.. 4.0 C Hydrocarbons vol. percent 1.5 C 430 F., naptha vol. percent 10.5 430-10l5 F. gas oil vol. percent..- 63.5 Gross coke make wt. percent 5.3

NOTE.AI1 1015 F.'+material from fuels coker efliuent is recycled to extinction.

Numerous variations of this invention will occur to those skilled in the art. It is to be appreciated that in certain applications either a transfer line reactor zone or a fluid bed fuels coking zone may be used to accomplish either the initial low temperature conversion of the feed or the high temperature conversion of the remaining portions of the feed. As indicated, however, a fluid bed operation is preferred for the fuels coking step and, because of the short contact times required in the chemicals coking zone, a transfer line reactor zone is preferred for this step. As an example of another variation, instead of stripping all of the solids in line 15, only the portion transferred to the burner vessel need be stripped.

Havingdescribed the invention, what is sought to be protected by Letters Patent, is succinctly set forth in the following claims.

What is claimed is:

l. A fluidized solids petroleum residua coking process for converting charge stock to fuels products and chemical unsaturates which comprises, in combination, coking a charging stock in a fluid bed fuels coking zone while maintaining a relatively low solids residence time whereby only a portion of the charging stock is converted to gasiform products, withdrawing solids and unconverted charging stock from the fluid bed, heating the withdrawn portion to a temperature above 1200 F. by adding additional high temperature solids, passing the heated portion through a transfer line reactor to convert the remaining portions of said charging stock to coke and light unsaturates while maintaining an average vapor residence time of less than 10 seconds in said transfer line reactor, and separating and recovering the conversion products from each zone from the contact solids therein.

2. A hydrocarbon conversion process which comprises injecting a heavy hydrocarbon oil into a fuels coking zone containing a fluidized bed of particulate coke maintained at afuels coking temperature in the range of 850 to 1200 F. to produce relatively lighter normally liquid conversion products while maintaining an average solids residence time in said fuels coking zone within the range of l to 10 minutes whereby a 1015 F. l conversion in the range of 40 to is obtained, introducing heated coke particles into said fuels coking zone at a solids/ oil ratio in the range of l to 10, removing entrained solids from and recovering said conversion products, withdrawing particulate coke along with the liquid residue of said charging stock and heating the withdrawn coke to a chemicals coking temperature in the range of 1200 to 1600 F. by mixing said withdrawn coke with 0.1 to 10 parts of additional coke per part of withdrawn coke having a temperature to 900 F. above the temperature of said withdrawn coke, passing the resulting mixture through a transfer line chemicals coke at velocities above 5 feet/see, whereby the remaining, heavier portion of said charging stock is converted to light hydrocarbon gases and coke, the average vapor residence time before quenching in said transfer line chemicals coker being under 10 secs., separating coke from said light hydrocarbon gases and recovering the gases as product, stripping the coke so separated, partially cooling and returning a major portion of the coke so stripped to said fuels coking zone as said heated coke particles, circulating the remaining portion of the stripped coke to a heating zone wherein the temperature of the coke is raised 100 to 900 F. above said chemicals coking temperature by partial combustion, and returning the reheated coke to said chemicals coking zone.

3. A combination fluid coking process for producing distillate fuels and chemical raw materials which comprises coking a petroleum residual oil in a fuels coker containing a fluid bed coking zone with a low solids holding time whereby only a portion of the residual oil is converted and the remainder is deposited on the solids, passing solids from said fluid bed coking zone to a transfor line chemicals coker, mixing additional hot solids with the solids in the chemicals coker to raise the temperature therein above 1200 F., passing the mixture through said chemicals coker for a relatively short reaction period whereby light unsaturates are produced, separating solids from the eflluent from said chemicals coker, passing a major portion of the solids so separated to said fuels coking zone to supply heat thereto and circulating the remainder of the separated solids to a heating zone and back to said chemicals coker.

(References on the following page) References Cited in the file of this patent UNITED STATES PATENTS Blanding Mar. 5, 1946 Weikart Mar. 6, 1951 Huff Nov. 6, 1951 Rex Aug. 26, 1952 8 Mattox Jan. 25, 1955 Kimberlin et a1. Oct. 18, 1955 Molstedt et a1 Feb. 21, 1956 Boston et a1 Feb. 21, 1956 Burnside et a1. Feb; 28, 1956 Russell Apr. 10, 1956

Claims (1)

1. A FLUIDIZED SOLIDS PETROLEUM RESIDUA COKING PROCESS FOR CONVERTING CHARGE STOCK TO FUELS PRODUCTS AND CHEMICAL UNSATURATES WHICH COMPRISES, IN COMBINATION, COOKING A CHARGING STOCK IN A FLUID BED FUELS COKING ZONE WHILE MAINTAINING A RELATIVELY LOW SOLIDS RESIDENCE TIME WHEREBY ONLY A PORTION OF THE CHARGING STOCK IS CONVERTED TO GASIFORM PRODUCTS, WITHDRAWING SOLIDS AND UNCONVERTED CHARGING STOCK FROM THE FLUID BED, HEATING THE WITHDRAWN PORTION TO A TEMPERATURE ABOVE 1200*F. BY ADDING ADDITIONAL HIGH TEMPERATURE SOLIDS, PASSING THE HEATED PORTION THROUGH A TRAANSFER LINE REACTOR TO CONVERT THE REMAINING PORTIONS OF SAID CHARGING STOCK TO COKE AND LIGHT UNSATURATES WHILE MAINTAINING AN AVERAGE VAPOR RESIDENCE TIME OF LESS THAN 10 SECONDS IN SAID TRANSFER LINE REACTOR, AND SEPARATING AND RECOVERING THE CONVERSION PRODUCTS FROM EACH ZONE FROM THE CONTACT SOLIDS THEREIN.

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