CA1248479A - Combination visbreaking and hydrorefining with recycle of hydrorefined bottoms - Google Patents

Abstract

ABSTRACT OF THE DISCLOSURE

A heavy hydrocarbon oil comprising consti-tuents boiling above 1050°F is upgraded by a combination visbreaking or hydrovisbreaking and hydrorefining process in which at least a portion of the hydrorefined bottoms fraction is recycled to the visbreaking zone. The hydrorefining zone is operated at conditions to convert at least a portion of the 1050°F+ constituents to lower boiling hydrocarbons.

Description

- 12~ 79 1 BACKGROUND OF THE INVE~lTION

2 1. Field of the Invention

3 The present invention relates to an improve-

4 ment in a combination visbreaking and hydrorefining process for upgrading hydrocarbonaceous oils.

6 2. Description of the Prior Art 7 Visbreaking is a well-known mild thermal 8 cracking process to which heavy hydrocarbonaceous oils 9 may be subjected to reduce their viscosity by depoly-merization and cracking in the liquid phase. See, for 11 example, Hydrocarbon Processing, September 1978, page 12 106.

13 The term "hydrorefining" is used herein to 14 designate a catalytic treatment conducted in the presence of added hydrogen, of a hydrocarbonaceous oil 16 to upgrade the oil by eliminating or reducing the 17 concentration of contaminants in the oil such as s~lfur 18 compounds, nitrogenous compounds and metal contami-19 nants, hydrogenation of unsaturated constituents of the oil and conversion of at least a portion of the heavy 21 constituents of the oil.

22 U.S. Patent 2,321,841 discloses visbreaking 23 a heavy hydrocarbonaceous oil and thereafter non-24 destructively catalytically hydrogenating the visbroken oil. The hydrogenated bottoms may be recycled to the 26 visbreaking zone.

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1 U.S. Patent 3,338,8'0 discloses hydrovis-2 breaking a hydrocarbonaceous oil. The lighter fraction 3 of the hydrovisbroken oil is catalytically hydro~
4 genated. The hydrogenated bottoms are recycled to the hydrovisbreaking zone.

6 U.S. Patent 3,050,457 discloses hydrovis-7 breaking a crude shale oll and catalytically hydro-8 genating the light fraction. The overhead gases are g recycled from the hydrogenation zone to the hydro-visbreaking zone.

11 U.S. Patent 3,132,088 discloses visbreaking 12 a residual oil and catalytically hydrogenating the 13 deasphalted bottoms of the visbroken oil.

14 It has now been found that a combination visbreaking, hydrorefining at conditions to convert at 16 least a portion of the heavy constituents of the 17 visbroken oil and a recycling of the hydrorefined 18 bottoms to the visbreaking zone will provide advantages 19 that will become apparent in the ensuing description.

SUMMARY OF THE INVENTION

21 In accordance with the invention there is 22 provided, a process for upgrading a heavy hydrocar-23 bonaceous oil which comprises the steps of:

24 (a) treating a chargestock comprising a fresh heavy hydrocarbonaceous oil comprising at least 26 about 10 volume percent materials boiling above 1050F
27 and a hydrorefined bottoms fraction recycled from step 28 (d) in a visbreaking zone at visbreaking conditions to ~L24~7~

1 produce a visbroken oil product, s~id visbroken oil 2 comprising materials boiling above 1050F;

3 (b) contacting at least a portion of said 4 visbroken oil with a hydrorefining catalyst in the presence of added hydrogen in a hydrorefining zone at 6 hydrorefining conditions such as to convert at least 7 about 5 weight percent of the materials boiling above 8 10s0F of said visbroken oil to lower boiling hydro-9 carbons, said hydrorefining conditions including a hydrogen partial pressure of at least 1000 psig, to 11 produce a hydrorefined effluent including a normally 12 gaseous phase and a normally liquid phase, including 13 normally liquid hydrocarbons;

14 (c) separating the hydrorefined oil product resulting from step (b) into fractions, including a 16 hydrorefined heavy bottoms fraction, and 17 (d) recycling at least a portion of the 18 separated hydrorefined heavy bottoms fraction to said 19 visbreaking zone.

By the terms "normally liquid" and "normally 21 gaseous" are intended herein that the components are 22 liquid or gaseous, respectively, at standard tempera-23 ture and pressure conditions.

Figure 1 is a schematic flow plan of one 26 embodiment of the invention.

27 Figure 2 is a schematic flow plan of another 28 embodiment of the invention.

-` ~2a~8~79 1 Figure 3 is a graph showing effect of 2 recycle on residuum yield and toluene insoluble in 3 visbreaking.

4 Figure 4 is a graph showing effect of recycle on residuum conversion and toluene insoluble in 6 visbreaking.

. _ .... _ .

8 Referring to Figure 1, a fresh heavy 9 hydrocarbonaceous oil comprising materials boiling above 1050F and a recycled hydrorefined bottoms 11 fraction (line 44) are passed by line 10 into vis-12 breaking zone 12. All boiling points referred to 13 herein unless otherwise specified are atmospheric 14 pressure boiling points.

Fresh Heavy Hydrocarbon Oils 16 Suitable fresh heavy hydrocarbon oils for 17 the visbreaking zone of the present invention are:
18 hydrocarbonaceous oils comprising at least 10 volume 19 percent materials boiling above about 1050F, pre-ferably at least 25 volume percent boiling above 21 1050F. The 1050F+ materials generally include 22 asphaltenes. The initial boiling point of such oils 23 will generally range from about 550 to 650F, although 24 whole crude oils may be used. Suitable oil feeds for the visbreaking zone include heavy crude mineral oils;
26 residual petroleum fractions such as atmospheric 27 residua and vacuum residua. Such oil feeds usually 28 contain large amounts of sulfur and may contain 29 metallic contaminants such as nickel and vanadium. The total metal content of such oils may range up to 2000 31 weight part per million or more, and the sulfur content - ~248~79 1 may rang^ from at least 0.5 weight percent to 8 weigil~
2 percent or more. The Conradson carbon residue of the 3 oils will be above 2 weight percent, preferably from 5 4 to 50 weight percent, and more preferably above 7 weight percent (as to Conradson carbon, see ASTM Test D
6 189-65). The heavy hydrocarbon oil may be derived from 7 any source such as petroleum, shale oil, tar sand oil, 8 heavy oils produced by coal liquefaction processes, 9 etc., and mixtures thereof. The preferred oil feed is a petroleum residuum obtained from distillation or 11 other treating or separation process.

12 Visbreak ng Operating Conditions 13 Suitable visbreaking conditions in vis-14 breaking zone 12 include a temperature ranging from about 750 to 950F, preferably from about 800 to about 16 920F, a pressure ranging from 50 to 1500 psig, 17 preferably from 100 to 1000 psig, more preferably from 18 200 to 800 psig. The visbreaking zone may be a coil 19 disposed in a furnace. In such an embodiment, the stated temperatures refer to coil outlet temperatures 21 and the preferred pressures are coil outlet pressures 22 ranging from 200 to 800 psig. If desired, a hydrogen-23 containing gas may be introduced into the visbreaking 24 zone to conduct hydrovisbreaking. The heavy hydrocar-bonaceous oil chargestock is maintained at visbreaking 26 conditions only for a time sufficient to convert not 27 more than 50 volume percent of the 700F+ constituents 28 to products boiling below 700F. Under the above 29 conditions, the heavy oil chargestock is partially converted to lower boiling hydrocarbon products. The 31 effluent of the visbreaking zone is passed by line 14 32 to separation zone 16, which may be a flash zone, 33 wherein the lighter boiling materials are removed 34 overhead by line 18 and the heavier visbroken oil ~24~ 7~

1 product is removed by line 20, mixed with a hydrogen-2 containing gas, preferably containing more than 70 3 percent hydrogen, introduced into line 20 by line 22 4 and passed into hydror~fining zone 24. The initial boiling point of the visbroken oil removed by line 20 6 from separation zone 16 may range from 100 to 1000F.
7 The visbroken oil portion introduced into hydrorefining 8 zone 24 comprises unsaturated hydrocarbons, materials 9 boiling above 1050F and usually sulfur contaminants.

The Hydrorefining Catalyst 11 The hydrorefining catalyst present in 12 hydrorefining zone 24 can be any conventional hydro-13 refining catalyst. Suitable hydrorefining catalysts 14 include a hydrogenation component, such as a Group VIB
and a Group VIII metal, metal oxide, metal sulfide and 16 mixtures thereof, composited with a support, such as an 17 alumina-containing support. The catalyst may be, for 18 example, a catalyst comprising cobalt, mDlybdenum, 19 nickel, tungsten and mixtures thereof on an alumina support, which may additionally comprise phosphorus 21 and/or silica. Suitable catalysts are described, for 22 example, in U.S. Patents 3,770,618; 3,509,044 and 23 4,113,656 Suitable operating conditions in the 26 hydrorefining zone are summarized in Table I.

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1 T~BLE I

3 Conditions Broad ~ange Preferred Range 4 Temperature, F 600-850 650-800

5 Total pressure, psig 1000-3000 1000-2500

6 Liquid hourly space

7 velocity, V/V/HR0.05-5.0 0.1-2.5

8 Hydrogen Rate, SCF/BBL 300-10,000 2000-6000

9 Hydrogen partial

10 pressure, psig1000-3000 1000-2000

11 The hydrorefining zone is operated at

12 conditions, including a hydrogen partial pressure of at

13 least 1000 psig, such that at least about 5 weight

14 percent, preferably more than 10 weight percent of the 1050F+ materials of the portion of the visbroken oil 16 introduced into the hydrorefining zone is converted to 17 lower boiling hydrocarbon products while simultaneously 18 hydrogenating unsaturated hydrocarbons, converting 19 asphaltenes to non-asphaltenes, and desulfurizing, and demetallizing the visbroken oil. The hydrorefining 21 zone effluent is passed by line 26 to separation zone 22 28 wherein a normally gaseous phase, including hydro-23 gen, hydrogen sulfide, light hydrocarbon gases and 24 which may comprise ammonia, is separated from a normally liquid phase which includes normally liquid 26 hydrorefined hydrocarbon oil. The normally gaseous 27 phase is removed from separation zone 26 by line 30. If 28 desired, hydrogen sulfide may be removed by conven-29 tional methods from the gaseous phase recovered by line and the substantially hydrogen-sulfide free 31 hydrogen-containing gas may be recycled to hydro-32 refining zone 24. Optionally, the hydrogen-containing 33 gaseous phase recovered by line 30 may be recycled to 34 visbreaking zone 12 with or without prior hydrogen ~2~47~3 1 sulfide removal. The hyd orefined oil product is 2 removed by line 32 and passed to separation zone 34 3 such as a fractional distillation zone, to separate the 4 oil into light gases removed overhead by line 36, a naphtha fraction recovered by line 38, an intermediate 6 boiling fraction recovered by line 40 and a heavy 7 hydrorefined bottoms fraction comprising material 8 boiling above 1050F removed by line 42. At least a 9 portion of the bottoms fraction is recycled by line 44 to line 10 in which is carried a fresh heavy oil feed 11 for introduction into visbreaking zone 12. The bottoms 12 fraction is recycled at a volumetric ratio of bottoms 13 fraction to fresh oil feed ranging from 0.1:1 to 5:1, 14 preferably at a volumetric ratio ranging from 0.5:1 to lS 2:1. If desired, a portion of the intermediate 16 fraction may also be recycled to the visbreaking zone 17 12 via line 46.

18 The figure 2 embodiment differs from the 19 figure 1 embodiment in that the hydrogen and hydrogen sulfide-containing gas recovered from the hydrorefining 21 zone effluent is recycled to the visbreaking zone which 22 is operated as a hydrovisbreaking process. Hydrogen 23 sulfide is removed from the gases recovered from the 24 hydrovisbreaking effluent and the substantially hydrogen sulfide free hydrogen-containing gas is 26 recycled to the hydrorefining zone. Referring to 27 Figure 2, a fresh heavy oil feed of the same type as 28 described with reference to Figure 1 is passed by line 29 110 to hydrovisbreaking zone 112. The hydrovisbreaking zone effluent is passed by line 114 to separation zone 31 116 (such as a flash zone1 wherein a normally gaseous 32 phase is separated from a normally liquid phase. The 33 gaseous phase is passed by line 118 to separation zone 34 119 in which a gaseous phase is separated from a normally liquid hydrocarbon phase. The hydrogen and ~ 2~847~

g 1 hydrogen sulfide-containing gaseo~s phase is removed by 2 line 121. If desired, hydrogen sulfide may be removed 3 from the gaseous phase and the resulting hydrogen-4 containing gas may be recycled to line 122. The normally liquid hydrocarbon phase is recovered by line 6 123. The liquid hydrovisbroken oil from separation 7 zone 116 is passed by line 120 to hydrorefining zone 8 124. A fresh or recycled hydrogen-containing gas or 9 mixtures thereof is introduced into line 120 by line 122. Hydrorefining zone 124 is operated at the same 11 conditions and comprises the same type of hydrorefining 12 catalyst as described with reference to Figure 1. The 13 hydrorefining zone effluent is passed by line 126 to 1~ separation zone 128 wherein a gaseous phase is sepa-rated from the hydrorefined oil phase. The gaseous 16 phase, which comprises hydrogen, hydrogen sulfide, 17 ammonia and light gaseous hydrocarbons, is removed by 18 line 130 and passed by line 131 into oil feed line 110 19 for introduction into the hydrovisbreaking zone 112.
The hydrorefined oil is passed by line 132 into 21 separation zone 134 in which it is separated into 22 fractions. Light gases are removed by line 136. A
23 naptha fraction is removed by line 138. An inter-24 mediate boiling fraction is removed by line 140. The hydrorefined bottoms fraction, comprising materials 26 boiling above 1050F, is removed by line 142 and 27 recycled by line 144 to fresh oil feed line 110 in the 28 same volumetric ratio as previously described with 29 reference to Figure 1. If desired, a portion of the intermediate fraction 140 may be recycled to oil feed 31 line 110 by line 144.

32 The following examples are presented to 33 illustrate the invention.

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1 ~AMPLE 1 2 A fresh virgin whole Cold Lake crude oil was 3 visbroken. The visbroken product was distilled to 4 obtain a 300C+ (572F+) residuum. The visbroken residuum was hydrorefined utilizing a conventional 6 cobalt-molybdenum on alumina hydrorefining catalyst.
7 The total hydrorefined liquid product was distilled to 8 obtain a 510C+ (950F+) hydrorefined bottoms portion.
9 These steps represent a first-pass operation. The operating conditions and results of these process steps 11 are summarized in Table II. The hydrorefined bottoms 12 fraction (recycle) and fresh whole Cold Lake crude oil 13 were blended in a volumetric ratio of 1:2. The blend 14 was visbroken. Visbreaking of the blend simulates a second-pass operation in accordance with the present 16 invention. Table II summarizes data for a typical 17 second-pass visbreaking which includes the recycle 18 hydrorefined bottoms portion. The conversion of 510C+
19 on fresh feed (recycle free basis) was 58 LV~, in contrast to 31 LV% obtained without recycle.

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7 CUT TEMPERATURE (WHOLE (TOTAL FEED (TOTAL
8 CRUDE) LIQUID) (5720F+) LIQUID) 9 Total Stream 10 Gravity, API at 11 at 60F 10.3 13.7 6.4 16.4 12 Carbon, wt% 82.25 -- -- 87.29 13 Hydrogen, wt% 10.59 ~ 11.16 14 Sulphur, wt% 4.43 4.36 4.51 0 795

15 Nitrogen, wt% 0.41 -- 0.51 0 32

16 CCR(l~, wt% 13.1 14.8 18.2 8.3

17 NI (2), wt% 12.7 12.7 16.2 6.4

18 Metals, wppm

19 Nickel 77 77 99 27.1

20 Vanadium 190 190 245 54.2

21 950F+ Residuum

22 Yield, LV% 54 0 37 4 5 37.8

23 Sulphur, wt% 5.8 5.4 5.5 1.79

24 CCR, wt% 22.9 35.8 35.8 20.4

25 NI, wt% 22.2 30.7 30.7 --Metals, wppm

26 Nickel 135 186 186 67

27 Vanadium 333 459 459 133

28 Conversion of 950F+

29 LV% -- 30.7 -- 24.2

30 wt% -- 27.5 -- 22.8

31 Operating Conditions

32 Tempërature, F -- 838 -- 700-734

33 Space Velocity,

34 v/h/V __ 5-10 -- 0.3-0.6

35 H2 Pressure, psi __ 200 -- 2000

36 H2 Rate, SCF/B -- Nil -- 6000

37 % Desulphurization 82.4

38 % Denitrogenation 37.3

39 % Nickel removal 72.6

40 % Vanadium removal 77 9

41 % CCR(l) removal 54 4 4 % NI(2) removal 60.5 ...... _ 43 (1) CCR denotes Conradson carbon residue 44 (2) NI denotes naphtha insolubes ~L248~

6FEED tHYDRO- TOTAL PRODUCT
7 STREAM (WHOLE GENATED FEED (TOTAL
8 CRUDE) 950F+) (BLEND) LIQUID) 9 Yield, LV% 67.2 32.8 100 101.9 Yield, WT% 66.7 33 3 100 99.7 11 Gravity, OAPI at 60F 10.3 5.9 9 4 12.5 13 Carbon, wt% 82.26 -- 83.79 14 Hydrogen, wt% 10.59 --- 10.23 0.17 Sulphur, wt% 4.43 1.79 3.55 --Nitrogen, wt% 0.41 --17 Toluene insolubles, wt% Nil Nil Nil 0.1 18 CCR(l), wt% 13.1 20.4 15.5 17.5 19 NI(2), wt% 12.7 15.7 13.7 14.1 20 Metals, wppm 21 Nickel 77 67 74 74 22 Vanadium 190 133 171 171 23 Yield of 675F+, LV% 82.5 100 88.2 74.6 24 Yield of 950F+, LV% 54.0 100 69.0 48 , wt% 57.1 100 71.4 52.4 Conversion of 950F+
26 on Fresh Feed, LV% -- -- -- 58.1 27 Operating Conditions 28 Temperature, F 824 29 Space velocity, v/h/v 3.2 Pressure, psi 200 31 (1) CCR denotes Conradson carbon residue 32 (2) NI denotes naphtha insolubles I ~4~34~

1 Example 2 2 To demonstrate the effect of recycling 3 hydrorefined bottoms on visbreaking performance, the 4 visbreaking step was operated at different severities with and without recycle. The results of these tests 6 were summarized in the graphs of figures 3 and 4.
7 Figure 3 shows toluene insolubles in total visbroken 8 product versus reduction of 510C+ (950F+) yield with 9 and without recycle. Toluene insolubles are indications of coke forming tendency. As shown in figure 3, recycle 11 of hydrorefined bottoms produced less toluene insol-12 ubles at a given bottoms reduction or achieved higher 13 bottoms reduction at a given toluene insolubles. Figure 14 4 shows toluene insolubles versus conversion of 510C+
(950F+) as expressed on fresh feed. Under operable 16 conditions, visbreaking without recycle converted only 17 35% of the 510C+ in fresh feed, whereas with recycle, 18 about 60% of the 510C+ materials were converted while 19 toluene insolubles remained low (about 0.1 wt.%).

Claims (10)

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:

1. A process for upgrading a heavy hydro-carbonaceous oil, which comprises the steps of:
(a) treating a chargestock comprising a fresh heavy hydrocarbonaceous oil containing at least about 10 volume percent materials boiling above 1050°F
and a hydrorefined bottoms fraction recycled from step (d) in a visbreaking zone at visbreaking conditions to produce a visbroken oil product, said visbroken oil comprising materials boiling above 1050°F;

(b) contacting at least a portion of said visbroken oil with a hydrorefining zone at hydrorefin-ing conditions such as to convert at least about 5 weight percent of the materials boiling above 1050°F of said visbroken oil to lower boiling hydrocarbons, said hydrorefining conditions including a hydrogen partial pressure of at least 1000 psig, to produce a hydro-refined effluent comprising a normally gaseous phase and a normally liquid phase, including normally liquid hydrocarbons;

(c) separating the hydrorefined oil product resulting from step (b) into fractions, including a hydrorefined heavy bottoms fraction, and (d) recycling at least a portion of the separated hydrorefined heavy bottoms fraction to said visbreaking zone.

2. The process of claim 1 wherein said fresh heavy hydrocarbonaceous oil comprises sulfur and metallic contaminants and wherein said hydrorefining conditions of step (b) are such as to desulfurize and demetallize at least partially said portion of vis-broken oil.

3. The process of claim 1 wherein said visbreaking conditions include a temperature ranging from 750 to 950°F and a pressure ranging from 50 to 1500 psig.

4. The process of claim 1 wherein said hydrorefining conditions include a temperature ranging from 650 to 800°F and a total pressure ranging from 1000 to 2500 psig.

5. The process of claim 1 wherein said hydrorefined bottoms fraction is recycled at a volu-metric ratio of recycled bottoms fraction to said fresh oil ranging from about 0.1:1 to 5:1.

6. The process of claim 1 wherein said fresh heavy hydrocarbonaceous oil feed comprises at least about 25 volume percent materials boiling above 1050°F.

7. The process of claim 1 wherein said oil feed is treated in said visbreaking zone in the presence of added hydrogen.

8. The process of claim 1 wherein said hydrorefined effluent is separated into said normally gaseous phase and into said normally liquid phase and wherein at least a portion of said normally gaseous phase is recycled to said visbreaking zone.

9. The process of claim 1 wherein said hydrorefining catalyst comprises a hydrogenation component selected from the group consisting of a Group VIB metal component, a Group VIII metal component and mixtures thereof, and an alumina-containing support.

10. The process of claim 1 wherein said recycled portion of separated hydrorefined heavy bottoms fraction of step (d) comprises materials boiling above 1050°F.