US3586619A - Conversion and desulfurization of hydrocarbonaceous black oils - Google Patents

Abstract

A PROCESS FOR CONVERTING HYDROCARBONACEOUS BLACK OILS INTO LOWER-BOILING, NORMALLY LIQUID HYDROCARBON PRODUCTS. THE PROCESS INVOLVES THE INTERGRATION OF HYDROGENATIVE CRACKING AND FIXED-BED CATALYTIC DESULFURIZATION, AND IS ESPECIALLY APPLICABLE TO THOSE HYDROCARBON CHARGE STOCKS CONTAINING LESS THAN 150 P.P.M. OF METALLIC CONTAMINANTS, AND MORE THAN ABOUT 10.0% BY VOLUME NON-DISTILLABLES. THE CHARGE STOCK IS INITIALLY SUBJECTED TO A FIXED-BED CATALYTIC HYDROGENATION AND DESULFURIZATION REACTION ZONE. FOLLOWING SEPARATION OF THE REACTION ZONE EFFLUENT, A HIGHBOILING CONCENTRATE IS THERMALLY CRACKED IN A HYDROVISBREAKING OPERATION.

Description

L. O. STINE June 22, 1971 CONVERSION AND DESULFURIZATION OF HYDROCARBONACEOUS BLACK OILS Filed 001'.. 28, 1968 523mm ME@ Q N VE/V TOR f Laurence 0. Stine VATTORNEYS United States Patent O 3,586,619 CONVERSION AND DESULFURIZATION OF HYDROCARBONACEOUS BLACK OIIS Laurence O. Stine, Western Springs, Ill., a'ssiguor to Universal Oil Products Company, Des Plaines, Ill. Filed Oct. 28, 1968, Ser. No. 771,251

' Int. Cl. C10g 37/04 U.S. Cl. 208-89 5 Claims ABSTRACT OF THE DISCLOSURE APPLICABILITY OF INVENTION The process described herein is adaptable to the desulfurization of petroleum crude oil residuals having relatively low metals content-i.e. containing less than 150 p.p.m. of total metals. More specifically, the present invention is directed toward a combination process for converting and reducing the sulfur concentration of hydrocarbonaceous charge stocks commonly referred to in the art as black oils.

Petroleum crude oils, and particularly the heavy residuals extracted from tar sands, topped or reduced crudes, and vacuum residuals, contain high molecular Weight sulfurous compounds in exceedingly large quantities, nitrogenous compounds, heptane-insoluble asphaltic material and high molecular weight organo-metallic complexes. With respect to the metallic complexes, containing nickel and vanadium as the principal metallic components, the various black oil charge stocks can be classified as (1) high metals residuals, or (2) low metals residuals. The present invention is primarily directed to the processing of those hydrocarbonaceous black oils having low metals contenti.e. less than about 150 p.p.m. of total metals, computed as if existing in the elemental state.

A black oil is generally characterized as a heavy carbonaceous material of which more than about 10.0% by volume boils above a temperature of 1050 F. (referred to as non-distillables). Such material generally has a gravity less than about 20.0 API and sulfur concentrations greater than about 2.0% by Weight, and which often range as high as about 5.0% by weight. Conradson carbon residue factors exceed 1.0% by Weight, and a great proportion of black oils indicate a Conradson carbon residue factor above 10.0. An abundant supply of such hydrocarbonaceous material exists, most of which has a gravity less than 10.0 API, and which is further characterized by a boiling range indicating that 30.0% or more boils above a temperature of 1050 F.

Exemplary of those hydrocarbonaceous black oils, to the conversion and desulfurization of Which the present invention is directed, include a crude tower bottoms product having a gravity of about 14.3 API, and contaminated by the presence of about 3.0% by Weight of sulfur, 3830 p.p.m. of total nitrogen, 85 p.p.m. of total metals and about 11.0% by weight of asphaltic non-distillables. The present invention affords the conversion of such ma- "ice terial into lower-boiling, normally liquid hydrocarbon products, and further converts a considerable quantity of non-distillables. Additionally, the normally liquid product of the process has been substantially desulfurized i.e. containing less than about 1.0% by Weight of sulfur.

The principal difficulty, heretofore encountered, resides in the lack of sulfur stability of many catalytic composites when the charge stock to be processed is characterized by the presence of large quantities of asphaltic material. This difficulty arises primarily as a consequence of the necessity for effecting the process at an operating severity level such that non-distillable conversion simultaneously takes place while the sulfurous compounds are being converted into hydrogen sulfide and hydrocarbons. The asphaltic material dispersed Within the charge stock has the endency to occulate and polymerize, whereby the conversion thereof to more valuable oil-soluble products is virtually precluded. Furthermore, the sulfur-containing polymerized asphaltic complexes become deposited upon the catalytic composite, steadily increasing the rate at which the catalytic composite becomes deactivated. These diiculties are further compounded with respect to those charge stocks characterized by a high metals content. Since these charge stocks can contain metals as high as 700 p.p.m., the catalyst deactivation rate is accelerated to the extent that processing to produce lower-boiling hydrocarbon products is not economically feasible.

The present invention is founded on recognition of the fact that acceptable desulfurization of low metals-containing black oils is possible at relatively mild operating severities which favor extended catalyst life without effecting a significant degree of asphaltene polymerization. In order that the process becomes economically attractive from the standpoint of producing lower-boiling hydrocarbon products, an essential feature of my invention resides in the subsequent processing of the liquid product efliuent from the fixed-'bed catalytic reaction zone. Therefore, as hereinafter set forth in greater detail, the catalytic reaction zone eiuent is separated at a temperature of from about 700 F. to about 800 F., and at substantially the same pressure as imposed upon the catalytic reaction zone, in order to provide a principally liquid phase which is subsequently subjected to a non-catalytic, thermal cracking reaction zone, or coil.

OBJECTS AND EMBODIMENTS A principal object of my invention is to provide an economical process for effecting the desulfurization and conversion of low metal black oils. A corollary objective is to extend the period of acceptable, economical catalyst life while desulfurizing and converting hydrocarbonaceous black oils containing less than about p.p.m. of total metals.

Another object is to convert heavy hydrocarbon charge stocks, a significant amount of which exhibits a boiling range above a temperature of l050 F., into lower-boiling distillable hydrocarbons having a sulfur concentration less than about 1.0% by Weight.

In one embodiment, therefore, my invention relates to a process for the conversion of a hydrocarbonaceous,v

sulfurous charge stock, of which at least about 10.0% Iboils above a temperature of 1050 F., into lower-boiling hydrocarbon products, which process comprises the steps of: (a) heating said charge stock to a temperature in the range of from 500 F. to about 800 F., reacting said charge stock with hydrogen in a first reaction zone, in contact With a catalytic composite and at a pressure above about 1000 p.s.i.g.; (b) separating the resulting reaction zone effluent, in a first separation zone, at substantially the same pressure imposed upon said first reaction zone to provide a first vapor phase and a first liquid phase; (c)

separating said rst vapor phase, in a second separation zone, at substantially the same pressure imposed upon said first separation zone, to provide a second vapor phase rich in hydrogen and a second liquid phase; (d) recycling at least a portion of said second vapor phase to said first reaction zone; (e) cracking at least a portion of said rst liquid phase in a non-catalytic second reaction zone; (f) separating the resulting cracked product efuent, in a third separation zone, to provide a third vapor phase and a third liquid phase; and (g) further separating said third liquid phase, in a fourth separation zone, at a pressure of from subatmospheric to about 50 p.s.i.g., to provide a fourth liquid phase containing distillable hydrocarbonaceous material and a non-distillable residuum.

Other embodiments of my invention, as hereinafter set forth in greater detail, reside primarily in preferred ranges of process variables and in various processing techniques. For example, the total charge to the first, fixed-bed catalytic reaction zone, consisting primarily of fresh charge stock, a recycle portion of the first liquid phase, a recycled hydrogen-rich gaseous phase and makeup hydrogen required to supplant that which is consumed within the overall process, is heated to a temperature Within the range of from about 650 F. to about 750 F. The precise temperature is controlled within the aforesaid range by monitoring the temperature of the reaction zone product efuent. Since the principal reactions being effected are highly exothermic, a temperature rise is experienced as the charge stock and hydrogen passes through the catalyst bed. In many instances, some temperature control is afforded through the use of a quench stream. Economically acceptable catalyst life is achieved when the maximum catalyst temperature, which is virtually the same as that of the product effluent, is maintained at a maximum level of about 900 F. In another embodiment, the first reaction zone effluent being introduced into the first separation zone, is at a temperature of from about 700 F. to about 800 F. in order that the portion of the rst liquid phase being subjected to the subsequent visbreaking reaction zone, contains from about 10.0% to about 40.0% of dissolved hydrogen. Other objects and embodiments of my invention will 'be evident from the following, more detailed description of the process encompassed thereby.

SUMMARY OF INVENTION As hereinbefore set forth, the principal function of the present invention resides in the production of maximum quantities of distillable hydrocarbons and which have been substantially reduced in sulfur concentration. Through the utilization of the present combination process, this is accomplished in a highly economical fashion while avoiding the difficulties of currently-practiced processing techniques. Paramount is the extension of the period of time during which the fixed-bed catalytic composite functions in an acceptable manner. With respect to the processing of high metals black oils, being those containing in excess of 150 p.p.m. of total metals, it has been found that a successful operation involves initially visbreaking the fresh hydrocarbon charge stock in the presence of limited quantities of hydrogen. While both technical and economical justification exists to support this processing technique, particularly respecting the attainable catalyst life experienced in the fixed-bed reaction zone, there is incurred a yield loss with respect to that quantity of the original non-distillable asphaltics which are not converted. This yield loss stems principally from the fact that thermal cracking, or visbreaking, in the presence of hydrogen, does not achieve the conversion of all the convertible asphaltics within the charge stock, the unconverted portion of which is removed as a heavy residual prior to subjecting the remainder of the thermally-cracked product efuent to further conversion in the xed-bed catalytic reaction zone. If the as-received high metals charge stock were processed initially in the fixed-bed CII Cal

catalytic reaction zone, the presence of the exceedingly high concentration of metals in an environment conducive to effecting acceptable desulfurization, results in extremely rapid catalyst deactivation. In accordance with the present process, primarily applicable to those charge stocks of low metals content, the residual charge stock is catalytically desulfurized, and at least partially converted, at relatively mild hydrogenation severities which favor extended catalyst life. The catalytically converted product effluent is separated into a principally vaporous phase and a principally liquid phase, at least a portion of the latter being utilized as the charge to a noncatalytic thermal cracking reaction zone. As hereinafter indicated, by an example integrated into the description of the drawing, this particular combination process affords maximum production of distillable hydrocarbons accompanied by maximum desulfurization of a charge stock, the metals content of which is less than about 150 ppm.

In a preferred embodiment, the total charge to the xedbed catalytic reaction zone will include the fresh hydrocarbon charge stock, recycled hydrogen, make-up hydrogen and a recycled diluent, the source of which is hereinafter set forth. This mixture is heated to a temperature of from about 500 F. to about 800 F., as measured at the inlet to the catalyst bed. Since the bulk of the reactions being effected are exothermic, the reaction zone efiiuent will be at a higher temperature. In order to preserve catalyst stability, it is preferred to control the inlet temperature at a level such that the temperature of the reaction product efliuent, or the maximum catalyst bed temperature, does not exceed about 900 F. The `reaction zone Will be maintained under an imposed pressure of from about 1000 to about 4000 p.s.i.g. The hydro-carbon charge stock contacts the catalytic composite at a liquid hourly space velocity of from about 0.5 to about 10.0, based upon the fresh charge stock. The hydrogen concentration will be in the range of from about 5000 to about 50,000 standard cubic feet per barrel, while the combined feed ratio (dened as total volumes of liquid charge per volume of fresh hydro-carbon charge) is in the range of from about 1.1:1 to about 3.521.

The catalytic composite disposed within the fixed-bed catalytic reaction, or conversion zone, can be characterized as cohtaining a metallic component having hydrogenation activity, which component is combined with a suitable refractory inorganic oxide carrier material of either synthetic, or natural origin. The precise composition and method of manufacturing the carrier material is not essential to the present invention, although a siliceous carrier, such as 88.0% by weight of alumina and 12.0% by weight of silica, or 63.0% by weight of alumina and 37.0% by weight of silica are generally preferred. Suitable metallic components are those selected from the group consisting of the metals of Groups VI-B and VIII of the Periodic Table, as set forth in the Periodic Table of The Elements, E. H. Sargent & Company, 1964. Thus, the catalytic composite may comprise one or more metallic components from the group of molybdenum, tungsten, chromium, iron, cobalt, nickel, platinum, iridium, osmium, rhodium, ruthenium, and mixtures thereof. The concentration of the catalytically active metallic component, or components, is primarily dependent upon the particular metal as well as the characteristics of the charge stock. The metallic components of Group VI-B are preferably present in an amount within the range of from about 1.0% to about 20.0% by weight, the iron-group metals in an amount within the range of about 0.2% to about 10% by weight, whereas the noble metals of Group VIII are preferably present in an amount within the range of about 0.1% to about 5.0% by weight, all of which are calculated as if these components existed Iwithin the catalytic composite as the elemental metal.

The refractory inorganic oxide carrier material may comprise alumina, silica, zirconia, ma-gnesia, titania, borin, strontia, hafnia, and mixtures of two or more including silica-alumina, alumina-silica-boron phosphate, silica-zirconia, silica-magnesia, silica-titania, alumina-zirconia, alumina-magnesia, alumina-titania, rnagnesia-znconla, silica-alumina-magnesia, silica-alumina-titania, silica-magnesia-zirconia, silica-alumina-boria, etc. It is preferred to utilize a carrier material containing at least a portion of silica, and preferably a composite of alumina, silica and boron phosphate with alumina being in the greater proportion.

Before further summarizing my invention, several definitions are believed necessary in order that a clear understanding be afforded. In the present specification and the appended claims, the phrase pressure substantially the same as, is intended to connote that pressure under which a succeeding vessel is maintained, allowing only for the pressure drop which is experienced as a result of the flow of uids through the system. For example, where the catalytic first reaction zone is maintained at a pressure of about 2750 p.s.i.g., the first separation zone, or hot separator will function at about 2630 p.s.i.g. Similarly,

unless otherwise specified, the phrase temperature subd stantially the same as, is used to indicate that the only reduction in temperature stems from normal loss due to the flow of material, or from the conversion of sensible to latent heat by ashing where a pressure drop occurs. When utilized, the phrase hydrocarbons boiling within the gasoline boiling range, is intended to connote those normally liquid hydrocarbons boiling in temperatures up to about 400 F. or 450 F., particularly including pentanes and heavier hydrocarbons, and, in some localities, butanes. Likewise, a commonly referred to boiling range for gas Oil is an initial boiling point of 525 F. and an end boiling point of about 1050 F. The higher boiling 70.0% to 80.0% thereof, the heavy gas oil, characteristically is considered as having an initial boiling point of about 750 F. Itis, of course, recognized that a light gas oil can have an initial boiling point as low as 320 F. and an end boiling point as high as about 800 F. Similiarly, the heavy gas oil can have an initial boiling point as low as about 650 F. The total product eiuent from the first catalytic reaction zone, at a maximum temperature of about 900 F., is passed into a rst separation zone hereinafter referred to as the hot separator. The principal function served by the hot separator is to separate the mixed-phase product eluent into a principally vaporous phase rich in hydrogen and a principally liquid phase containing at least about 10.0% of dissolved hydrogen. In a preferred embodiment, the total reaction product effluent is utilized as a heat-exchange medium to lower the temperature thereof to a level in the range of from about 700 F. to about 800 F., and preferably below about 750 F. The prncipally vaporous phase from the hot separator is introduced into a second separation zone hereinafter referred to as the cold separator. The cold separator, operating at substantially the same pressure as the hot separator, but at a lower temperature in the range of about 60 F. to about. 140 F., serves to concentrate the hydrogen in a second principally vaporous phase. The hydrogen-rich second vapor phase, comprising about 82.5 mol percent hydrogen, and only about 2.3 mol percent propane and heavier hydrocarbons, is made available for use s a recycle stream to be combined with the fresh black oil charge stock. Butanes and heavier hydrocarbons are condensed in the cold separator, and removed therefrom as a second principally liquid phase.

The iirst principally liquid phase from the hot separator, is in part recycled to combine with the fresh hydrocarbon charge stock to serve as a diluent for the heavier constituents. The amount of the hot separator liquid phase which is diverted in this manner is such that the combined feed ratio to the catalytic reaction zone is within the range of from about 1.1:1 to about 3.5 :1. The remaining portion of the principally liquid phase from the hot separator, containing at least about 10.0% hydrogen, is introduced into a thermal cracking reaction zone, or coil, at a reduced pressure in the range of from about 300 to about 500 p.s.i.g. The thermally cracked product eliluent is introduced into a third separation zone, hereinafter referred to as the hot ash zone. The hot flash zone functions at a temperature of from about 750 F. to about 850 F., and at a substantially reduced pressure in the range of from about p.s.i.g. to about 200 p.s.i.g. The principally vaporous phase from the hot flash zone comprises primarily hydrocarbons boiling below a temperature about 650 F., containing a relatively minor quantity of hydrocarbons normally considered to be in the heavy vacuum gas oil boiling range. This principally vaporous stream may be combined with the liquid stream from the cold separator, the mixture Ibeing introduced into a cold liash zone maintained at a pressure of from about atmospheric to about p.s.i.g. and a temperature of about 60 F. to about 140 F.

The principally liquid phase from the hot ash zone is introduced into a vacuum ilash column maintained at about 25 to 60 mm. of Hg., absolute. The vacuum liash zone serves as the fourth separation zone, the principal function of which is the recovery of an asphaltic residuum, containing high molecular weight sulfurous compounds and being substantially free from distillable hydrocarbons, In general, gas oil streams are recovered from the vacuum ash column as a separate light vacuum gas oil (LVGO) and a heavy vacuum gas oil (HVGO), although in some instances, a medium vacuum gas oil is also recovered. In one embodiment, at least a portion of the Ivacuum gas oil streams, and preferably the heavy vacuum gas oil stream, or slop wax, is recycled to combine with the hot separator lbottoms liquid being introduced into the thermal reaction zone. The amount so recycled is such that the combined feed ratio to the thermal visbreaking reaction coil is above about l.2:1, and generally not higher than about 3.0:l. In another embodiment, a portion of the heavy gas oil, or slop wax, may ybe recycled to combine with the charge to the catalytic hydrogenation zone.

The principal advantage, or benefit, attendant the use of my invention, resides in an extension of acceptable catalyst life with respect to the fixed-bed catalytic reaction zone. This stems primarily from the fact that desulfurization to a level less than about 1.0% by weight, is effected at a relatively low severity of operation with the result that the atmosphere within the reaction zone is not conducive to the formation of polymer products otherwise resulting from the presence of hydrocarboninsoluble asphaltenes. Another advantage resulting from the low severity of operation within the fixed-bed catalytic reaction Zone, involves the dissolution of hydrogen in the normally liquid heavier portion of the product eiluent,at least a portion of which is utilized as the charge to the thermal cracking reaction zone. Of further interest is the fact that the vacuum flash column is signiiicantly reduced in size which, as will be recognized as those having skill in the art of petroleum processing techniques, affords an added advantage with respect to the overall economics of the process.

DESCRIPTION OF DRAWING For the purpose of demonstrating the illustrated embodiment, the drawing will ybe described in connection with the conversion and desulfurization of a vacuum column bottoms product derived from a Sassan crude. The vacuum bottoms product has a gravity of 6.0 API, an average molecular weight of about 620, an ASTM 20.0% volumetric distillation temperature of about 1035 F., and contains about 4,000 p.p.m. of nitrogen, 5.5% by weight of sulfur, p.p.m. of 'vanadium and nickel and 6.0% by weight of heptane-insoluble asphaltenes.

In addition, the description will be directed toward a commercially-scaled unit having a capacity of about 8,000 barrels per day. In the drawing, the embodiment is presented by means of a simplified flow diagram in which such details as pumps, instrumentation and controls, heat-exchange and heat-recovery circuits, valving, startup lines and similar hardware have been omitted as nonessential to an understanding of the techniques involved. The use of such miscellaneous appurtenances, to modify the illustrated process ow, are well within the purview of those skilled in the art. Similarly, it is further understood that the charge stock, stream compositions, operating conditions, design of fractionators, separators and the like are exemplary only, and may be varied widely without departure from the spirit of my invention, the scope of which is dened by the appended claims.

This vacuum column bottoms is intended for conyversion to maximum distillable hydrocarbons recoverable by ordinary distillation in commonly used fractionation facilities. The charge stock is processed in a fixed-bed catalytic conversion zone in admixture with about 10,000 s.c.f./bbl. of hydrogen, based upon fresh feed, at an inlet catalyst bed temperature of about 800 F., and an inlet pressure of 3105 p.s.i.g. The liquid hourly space velocity,

based upon fresh feed only, is 0.5 and the combined feed ratio, with respect to total liquid feed, is 2.0:l.

With reference now to the drawing, the charge stock, in an amount of 7678 bbl./day (185.94 mols./hr.) is introduced into the process by way of line 1. A hot separator bottoms recycle, in an amount of about 7678 bb1./ day, is admixed from line 3, the mixture continuing through line 1 into charge heater 5. Make-up hydrogen from a suitable external source is introduced by way of line 4. The heated charge, at a temperature of about 800 F., passes through line 6 into a xed-bed reactor 7.

The conversion product effluent, in mixed phase in line 8, at a temperature of about 875 F., and a pressure of about 3055 p.s.i.g., is utilized as a heat-exchange medium to lower its temperature to a level of about 775 F., at which temperature, the effluent continues through line 8 into hot separator 9. A principally liquid phase is withdrawn via line 10, and a hydrogen-rich, principally vaporous phase through line 11. A portion of the principally liquid phase is diverted through line 2, and is recycled to combine with the charge stock in line 1, to provide a combined liquid feed ratio to reactor 7 of 2.021. The remaining portion continues through line 10 into thermal coil 13.

In the following Table I, the component stream analyses are presented for the separation effected in hot separator 9. With respect to line 10, the values, in mols/hr. for convenience, represent the material introduced into thermal coil 13; the indicated amounts do not take into account the quantities of various recycle streams.

TABLE L HOT SEPARATOR STREAM ANALYSES Line Number 10 11 1. 66 9. 34 15S. 23 7, 345. 66 24. 54 885. 36 28. l1 1, 106. 2l Ethane 6. 81 146. 01 Propane 3. 85 83. 87 Butanes 1. 88 35. 63 Pentanes 0. 83 13. 08 (lg-320 F 4. 03 43. 71 320 F.-520 F l0. 1l 53. 07 520 F,-650 F 14. 63 25. 36 650 F.750 F 20. 47 l0. 7 750 F.980 F. 60. 47 3. 74 980 F.-plus 8. 34 0. 0l Residuum 70. 04

The vaporous phase in line 11 is cooled to a temperature of about 120 F., and is introduced into cold separator 12 at a pressure of about 3000i p.s.i.g. A hydrogenrich gaseous phase is withdrawn from cold separator 12 via compressive means, and is recycled through line 3. A principally liquid phase is withdrawn via line 17. 1n order to further increase the concentration of hydrogen being recycled via line 3, a portion of a cold Hash zone liquid, hereinafter described, is admixed with the vapor- Line Number 3 Component, niels/hr.:

Nltr 9. 22 0. 12 Hydrogen 75. 81 Hydrogen sullid 117. 54 Methane 38. 16 Ethaue. 13. 33 Propane 14. 24 Butams 10. 78 Pentanes 6.51 Ct-320 F 37. 10 32.1 F.-520 F 52. 83 520 F.650 F 25.36 650 F.750 F 10. 78 750 11.-980 F 3. 74 980 F.plus 0. 01 Residuum A portion of the liquid phase from hot separator 9, comprising about 38.1 mol. percent hydrogen, continues through line 10, passes through a pressure reducing valve, and enters thermal coil 13 at a pressure of about 400 p.s.i.g. and a temperature of about 775 F. The thermallycracked product euent, at a pressure of about 250 p.s.i.g. and a temperature of about 930 F., is quenched to about 800 F., and is passed through line 4l into hot ash zone 15, at a pressure of about p.s.i.g. A Vaporous phase, about 91.8% of which boils below a temperature of 520 F., is removed via line 16, is admixed with the liquid phase in line 17 from cold separator 12, and continues through line 16 into cold flash zone 2'5. A principally liquid phase is withdrawn through line 18, and

.is introduced into vacuum flash column 19 functioning at about 30 mm. of Hg absolute. In the following Table III, component analyses a-re presented for the thermallycracked product eiuent (line 14), the vapor phase (line 16) and the liquid phase (line 1-8) from hot flash zone 15, exclusive of quench.

TABLE IIL-HOT FLASH ZONE STREAM ANALYSES Line Number 14 16 18 Component, mois/hr.:

regen 1. 66 1. 66 Hydrogen 164. 163. 19 0. 89 Hydrogen sulde 36. 20 20. 96 0.24 Methane 50. 69 50. 40 0. 29 Ethane 22. 70 22. 37 0.33 Propane. 27. 26 26. 71 0. 48 Butanes. 17. 77 17. 34 0.43 Pentanes 8. 40 8. 09 0. 31

Cs320 F 59. 46 55. 45 4, 01 320 SE1-520 F 60. 31 51. 65 B. 66 520 F.650 F d1. 60 21. 85 9. 75 650 F.750 F 25. 52 11.63 13. 89 750 F.980 F. .50. 26 10. 12 49. 14 980 F.plus 10. 42 10. 42 Residuum 30. 39 39. 39

Vacuum flash column 19` serves to concentrate the residuum, 39.39 mols/ hr. leaving via line l20, and to separate a heavy Vacuum gas oil (HVGO), line 22, and a light vacuum gas oil (LVGO), line 21. The HVGO is in an amount of 59.56 mols/hr., having a boiling range of 750 F. to about 1100 F. and the LVGO is in an amount of 32.30 mols/hr., having a boiling range of 320 F. to 750 F. The lighter material boiling below 320 F., is removed from vacuum ash zone 19 by the jets which are not indicated in the drawing.

For the sake of completeness, cold ash zone 25 has been illustrated in the drawing to indicate the separation of the mixture of the cold separator liquid (line 17) and the hot ash zone vapors (line 16). Normally gaseous material is withdrawn through line 23 to a light ends recovery system, while normally liquid hydrocarbons includin g butanes, are removed via line 24 to a fractionation system. A portion of this stream would be used to quench the thermal coil effluent in line 14. The following Table IV indicates the separation eifected in cold flash zone 25, exclusive of quench.

TABLE 1V.-COD FLASH ZONE STREAM The overall product yields, exclusive of light, normally gaseous material, but inclusive of butanes and the normally liquid hydrocarbons recoverable from the vacuum jets and light ends recovery (line 23), are presented in the following Table V.

TABJE V: OVERALL PRODUCT YIELDS Component: Mols/hr. Butanes 28.55 yPentanes 14.91 C6-320 F. 96.66 320 F.-520 F. 113.14 520 F.-650 F. 56.96 650 F.-plus 109.73 IResiduum 39.39

On a volumetric basis, and based upon a fresh charge stock capacity of 7,678 bbl/day, about 7,735 bbL/day of distillable products, having a sulfur concentration of about 0.76% by weight, are produced. Of this total product, 2,486 bbl./day result from the-separation of vacuum gas oils in the vacuum iiash column 25.- When compared to a processing scheme in which the hydrovisbreaker is not integrated within the system, the capacity increase necessary to separate the gas oil from the residuum requires a vacuum flash column having an internal diameter of 2.0' larger.

With respect to extending the period of time during which the catalytic composite, inthe :fixed-bed conversion zone, functions in an economically acceptable manner, without experiencing deactivation, the present process increases catalyst life from 50% to 80%. Catalyst life is commonly expressed as barrels of fresh charge stock (a) heating said charge stock to a temperature in the range of from 500 F. to about 800 F., reacting said charge stock with hydrogen in a first reaction zone, in contact with a catalytic composite and at a pressure above about 1000 p.s.i.g.;

(b) separating the resulting reaction zone efliuent, in

a first separation zone, at substantially the same pressure imposed upon said iirst reaction zone, and at a temperature in the range of about 700 F. to about 800 F., to provide a rst vapor phase and a rst liquid phase;

(c) separating said iirst vapor phase, in a second separation zone, at substantially the same pressure imposed upon said first separation zone, to provide a second vapor phase rich in hydrogen and a second liquid phase;

(d) recycling at least a portion of said second vapor phase to said rst reaction zone;

(e) cracking at least a portion of said rst liquid phase,

without intermediate heating thereof, in a noncatalytic second reaction zone;

(f) separating the resulting cracked product efuent, in a third separation zone, to provide a third vapor phase and a third liquid phase; and,

(g) further separating said third liquid phase, in a fourth separation zone, at a pressure of from subatmospheric to about 50 p.s.i.g., to provide a fourth liquid phase containing hydrocanbonaceous material boiling above about 1050 F. and a fifth liquid phase boiling below about 0 F.

2. The process of claim 1 further characterized in that at least a portion of said first liquid phase is recycled to combine with said charge stock, to provide a combined feed ratio to said iirst reaction zone in the range of from about 1.1:1 to about 3.5: 1.

3. The process of claim 1 further characterized in that at least a portion of said fifth liquid phase is recycled to combine with said first liquid phase to provide a combined feed ratio to said non-catalytic second reaction zone above about 1.2: 1.

4. The process of claim 1 further characterized in that said char-ge stock is heated to a temperature in the range of from about 650 F. to about 750 F.

5. The process of claim '1 further characterized in that at least a portion of said fifth liquid phase is recycled to Combine with said charge stock.

References Cited UNITED STATES PATENTS 1,932,174 10/1933 Gaus et al. 196--24 2,282,451 5/ 1942 Brooks 196-24 2,327,099 8/ 1943 Eastman 196-49 2,339,918 1/1944 Thomas 196-52 2,355,366 8/1944 Conn 196-24 3,409,538 11/ 1968 Gleim et al 208-59 DELBERT E. GANTZ, Primary Examiner R. M. BRUS-KIN, Assistant Examiner U.S. Cl. X.R.

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