US3252888A - Conversion of hydrocarbons with the use of hydrogen donor diluents - Google Patents

Description

A. w. LANGER, JR. ETAL 3,252,883 CONVERSION OF HYDROCARBONS WITH THE USE OF HYDROGEN DONOR DILUENTS 2 Sheets-Sheet l lnvenrors Purenr Ahornev Arrhur W. L unger,dr. John A. Hmhcky w 15] MN: 2% mm 07 355 J 5 2w oz; zwwo% I mm 239; mm m vol 68 I w mm ozaauo ow vN mm Tail w mm vm {m 9 6w 8 N E 5 mm F mnmum mm in 2 ww ozimolom z 8 i 9 May 24, 1966 Filed NOV. 6, 1962 May 24, 1966 A. w. LANGER, JR. ETAL 3,252,888

CONVERSION OF HYDROCARBONS WITH THE USE OF HYDROGEN DONOR DILUENTS Filed Nov. 6, 1962 2. Sheets-Sheet 2 mw ll N8 f\ w m NN2 m 1 m 2% $1 3m 93 $9 mm? a 3&1 2 a 5mm mum 2m 02525894 3N $251539: NmN wm- NON w m: NNAWP wON m2 QNA mom 9 NR 4 M 59 mm EV- mm: 9.; m9 2 mm 4 oz 2mo. omn v: 3: 87* NF:

Arthur W. Longer, Jr. John A. Hinlicky \nVenTOfS By W V PctenrAfiorney United States Patent 0 3,252,888 CONVERSION OF HYDRGCARBONS WITH THE USE OF HYDROGEN DGNGR DTLUENTS Arthur W. Langer, In, Watchung, and John A. Hiniicky,

Irvington, N..l., assignors to Esso Research and Engineering Company, a corporation of Delaware Filed Nov. 6, 1962, Ser. No. 235,660 12 Claims. (Cl. 208-56) This invention relates to the conversion of high boiling hydrocarbons to lower boiling hydrocarbons. More particularly, the invention relates to the conversion of high boiling hydrocarbons to naphtha and/ or motor fuel gasoline in an integrated process involving hydrocracking of a gas oil fraction and utilizing hydrogen donor diluent cracking in such a manner as to produce ample quantities of aromatic hydrocarbons which can be hydrogenated partially to produce excellent hydrogen donor diluents for non-catalytic hydrogen donor diluent crack ing (HDDC) of residual oils or bottoms fractions.

The aromatic hydrocarbon bottoms from hydrocraclo ing gas oil are used on a once-through basis or with recycle as diluents for the HDDC conversion of residual oils.

Integration of the HDDC-hydrocracking processes with gas oil catalytic cracking and naphtha reforming produces a balanced refinery operation with complete residuum conversion which is self-sufficient with respect to hydrogen and hydrogen donor diluent. On crude, between 60 and 80% yield of gasoline is obtained with a leaded octane number in the range 98-100.

Hydrocracking of gas oils has been integrated with hydrogen donor diluent cracking in such a manner as to produce ample quantities of aromatic hydrocarbons in the hydrocracking step which can be hydrogenated partially to produce excellent hydrogen donor diluents for HDDC conversion of residuum or residual oils. In addition to providing the diluent for HDDC, this integration results in a number of other advantages. For example, the diluent fraction obtained from the hydrocracking operation has very low sulfur and, after being hydrogenated and used as a hydrogen donor diluent, this fraction ends up as a stable, low sulfur heating oil which requires little or no finishing treatment. Another advantage is the high octane gasoline obtained over a platinum hydrocracking catalyst supported on eta alumina. The high activity of this catalyst permits excellent conversions at high space velocity.

Other advantages will be evident as this refining scheme is discussed in greater detail, particularly with respect to the hydrogen balanced operations and the product distributions. Complete residuum reduction is obtained in this refining scheme together with a high octane gasoline pool.

The process is flexible and permits varying the severity of the hydrocracking and HDDC steps to vary product distribution and quality. In addition, the gasoline pool octane number can be varied by varying the quantity and the streams fed to the hydroforming step. The naphtha from the HDDC step is preferably hydroformed. The present integrated hydrocracking-HDDC process also offers an excellent route to maximize middle distillates at the expense of gasoline, should that be desirable. Both HDDC and hydrocracking can be operated at mild conditions to give high selectivity to middle distillates.

In-the drawings:

cat

3,252,838 Patented May 24, 1966 FIG. 1 diagrammatically represents one form of apparatus for carrying out the invention; and

FIG. 2 diagrammatically represents a modification of the apparatus shown in FIG. 1.

Referring now the drawings, the reference character 10 designates a line for introducing whole crude petroleum oil into an intermediate part of vertically arranged fractionator 12. The oil is fractionated into a plurality of fractions and a light hydrocarbon fraction, including gases and boiling up to about 200 F., is taken overhead through line 14. This cut is normally fractionated further to obtain dry gas, LPG, and some pentanes plus higher boiling liquid products. The liquid products (and butanes if desired) are added directly to the gasoline pool or they may be treated to improve quality by desulfurization, isomerization, etc. A heavy naphtha fraction boiling between about 200 F. and 430 F. is withdrawn through line 16 from the upper portion of the fractionator 12. A kerosene fraction boiling between about 430 F. and 490 F. is withdrawn at a lower level from the fractionator 12 through line 18. A light gas oil fraction boiling between about 490 F. and 700 F. is withdrawn from a lower portion of the fractionator 12 through line 22. A heavy gas oil fraction boiling between about 700 F. and 900 F. is withdrawn further down from the lower portion of the fractionator 12 through line 24. A bottoms fraction higher boiling than about 700 F.-900 F. is withdrawn from the bottom of the fractionator 12 through line 26. In some cases it may be desirable to withdraw a 700 F.+ stream from the bottom of fractionator 12 through line 26 and make the separation into 700 F. to 900 F. and 900 F.+ fractions in vacuum still 27 hereinafter described.

The heavy naphtha fraction boiling below about 430 F. and withdrawn through line 16 is mixed with hydrogen from line 28 and introduced into hydroforming zone 32. The temperature is maintained between about 800 F. and 1050 F. in hydroforming zone 32, the pressure is maintained between about 0 p.s.i.g. and 800 p.s.i.g., and about 1000 s.c.f. to 15,000 s.c.f of hydrogen-containing gas per barrel of naphtha feed is used The preferred hydroforming catalyst is a platinum-alumina catalyst where the alumina contains about 0.001 to 5.0 wt. percent of platinum. The feed rate of naphtha is between about 0.1 and 10 w./w./hr. Instead of the 200430 F. naphtha, other feedstock boiling ranges, such as 200350 B, may be used to vary the hydroformer performance.

Other hydroforming catalysts such as molybdenaalumina, palladium-alumina, chromia-alumina, etc., as well as various modifications may be used. The platinum catalysts may contain stabilizers such as silica to stabilize the surface area of the alumina or thoria to prevent platinum crystal growth.

The preferred platinum-alumina catalyst may be used for both the hydroforming and hydrocracking operations. High activity is maintained by regeneration and chlorine treating the catalyst after each cycle. Regeneration may be carried out in a number of ways but preferably it is accomplished with air or flue gas at a pressure between about 0 and 1,000 p.s.i.g. and at a temperature in the range of 800 to 1050 F. After regeneration, the precious metal catalyst on an acidic support is chlorine treated to enhance activity. Although chlorine is preferred for this treatment, any known halogen compound, decomposable into free chlorine, non-metallic halide or aluminum halide may be used for this purpose. It is also preferred to do the treating'in an oxidizing atmosphere and this can be accomplished by introduction of air while chlorine treating.

During hydroforming, hydrogen is produced in a suflicient amount to be recycled to the hydroforming step, to supply hydrogen for a hydrocracking step to be presently described and for partially hydrogenating high boiling aromatic compounds to produce hydrogen donor diluents to be used in converting residual oil in a step hereinafter to be described. In some cases additional hydrogen is available for hydrodesulfurization of heating oil, etc.

The hydroformed products are passed through line 34 to a knockout drum or fractionating tower 36. In this tower 36, hydrogen gas containing some gaseous hydrocarbons is withdrawn overhead through line 38 and a portion recycled through line 28 to the hydroforming zone 32. Another portion of the hydrogen-containing gas is passed through line 42 and any excess hydrogen can be removed from the system through line 44. A light gaseous hydrocarbon fraction is withdrawn asa side stream through line 46 from an upper portion of tower 36. A gasoline fraction is withdrawn from an intermediate portion of the tower 36 through line 48. When the feed to hydroformer 32 contains material boiling in the 380-430 F. range, some 430 F.| bottoms may be produced and this will be withdrawn through line 54. This bottoms fraction is preferably added to the feed to hydrocracker 58 through line 60.

A kerosene fraction is withdrawn from tower 12 through line 18 for use as kerosene or heating oil. Preferably, this fraction is hydrocracked together with the gas oil from line 22 or separately in a blocked operation to make specialty fuels or aromatics. In one prefer-red operation, a 200-370 F. naphtha fraction is hydroformed and the entire 370-650 F. fraction is hydrocracked.

The gas oil fraction withdrawn from the fractionating tower 12 through line 22 is mixed with hydrogen-containing gas from line 61 and passed through the hydrocracking zone 58 maintained at a temperature between about 400 and 1050 F., and a pressure between about 200 and 10,000 p.s.i.g. The feed rate of the gas oil to the zone 58 is between about 0.1 and w./ w./ hr. About 2,000 to 20,000 s.c.f. of hydrogen-containing gas per barrel of feed are used. Additional hydrogen is recycled to line 22 through line 62. The catalyst in the hydrocracking zone 58 is preferably platinum-alumina similar to that used in the hydroforming zone but other hydrocracking catalysts such as cobalt molybdate on alumina, precious metals such as platinum or palladium on supports such as alumina, silica-alumina or molecular sieves, nickel sulfide on alumina, etc., may be used. The activity of platinum catalysts is improved by the addition of chloride.

Some of the gas oil from line 22 may be withdrawn through line 64 as a heating oil product. Preferably, additional gas oil from a later stage in the process is also returned to the hydrocracking zone 58 through line 60.

The hydrocracked products are passed through line 68 into a knockout drum or fractionating tower 72 to separate hydrogen-containing gas overhead through line 74 and a normally gaseous hydrocarbon stream is withdrawn through line 76 as a side stream from the upper portion of tower 72. The hydrogen-containing gas in line 74 contains some impurities such as sulfur and nitrogen-containing compounds and is preferably passed through conventional scrubbing means 78 and the purified hydrogen-containing gas is recycled to the hydrocracking zone 58 through line 6-2. A portion of the hydrogencontaining gas can be bled 01f through line 82 and removed from the process.

Returning to the tower 72, when using the tower as a knockout drum, a gasoline fraction is withdrawn as a side stream through line 84 from an intermediate portion of the tower 72. The bottoms fraction withdrawn through line 86 is a relatively light fraction boiling above about 430 F. When functioning as a fractionating tower, valved line 88 is used to withdraw a higher boiling fraction from the lower portion of the fractionating tower 72. This fraction boils up to about 700 F. so that in this form of the invention the bottoms withdrawn through line 86 will contain material boiling above about 700 F.

In either case the bottoms withdrawn from the tower 72 through line 86 are mixed with hydrogen from line 42 and passed to a hydrogenation zone 92. This bottoms fraction contains higher boiling aromatic compounds which are partially hydrogenated in the hydrogenation zone 92 using conventional hydrogenation conditions and introducing about 50 to 1000 s.c.f. of hydrogen per barrel of the bottoms fractions. The temperature is maintained between about and 750 F. and the pressure between about 50 and 1000 p.s.i.g. in the hydrogenation zone 92. The oil feed rate is between about 0.1 and 10 w./w./hr. As the bottoms fraction contains impurities such as sulfur, it is preferable to employ a relatively sulfur-insensitive catalyst, such as molybdenum sulfide or tungsten nickel sulfide, which normally requires operation at the higher temperatures and pressures.

The hydrogen donor diluent precursor used in this invention is a distillate material or a bottoms material boiling above about 430 F. and preferably above 700 F. and should have an aromatic ring content above about 40 wt. percent. Partially hydrogenated condensed or polycyclic aromatic ring compounds contain aromaticnaphthenes having one or more aromatic nuclei which increase the reactivity of the naphthenic hydrogens and cause the molecule to function as a superior hydrogen donor. By partial hydrogenation is meant an extent of hydrogenation sutficient to introduce on the average one to three hydrogen molecules into the aromatic-naphthenic donor molecule, while leaving one or more rings unhydrogenated. This results in a diluent donor having a hydrogen to carbon atomic ratio in the range of 0.7 to 1.6. The donor diluent picks up enough easily removable hydrogen to be effective as a hydrogen donor but not enough to approach saturation or to convert it substantially to naphthenes. Reference is made to Langer Patent 2,953,513 granted September 20, 1960, and the disclosure there is incorporated here by reference.

The amount of hydrogen which must be added to the hydrogen donor diluent precursor will depend upon the feedstock and the conditions used in the hydrocracking stage (catalyst, hydrogen pressure, temperature, cracking severity, etc.). The more highly aromatic precursors can take up to 1,000 s.c.f. H /bbl. without harming the donor properties. When the hydrocracker is operated at high hydrogen consumption, the diluent precursor will be less aromatic and will require little additional hydrogen to be an effective hydrogen donor diluent. Generally, the most etficient hydrocracking conditions will yield a hydrogen donor diluent precursor which requires between about 100 and 500 s.c.f. added H /bbl. for the most effective hydrogen donor activity.

The recycle hydrogen donor diluent stream from a later stage in the process is passed through line 94, mixed with the bottoms stream in line 86 and introduced into hydrogenation zone 92. The partially hydrogenated higher boiling aromatic compounds are withdrawn from the hydrogenation zone 92 through line 96 and passed to the non-catalytic HDDC zone 98. Also introduced into the HDDC zone 98 is the bottoms fraction from fractionator 12 through line 99 or a portion of the bottoms fraction withdrawn from fractionating tower 12. The bottoms fraction in line 26 is introduced into the vacuum distillation zone 27 to separate overhead a higher boiling or heavy gas oil fraction boiling above about 700 F.900 F. and withdrawn through line 104. The product from 104 may be used as feed to catalytic cracking or hydrocracking, or as heavy fuel. The bottoms fraction from vacuum distillation zone 27 is withdrawn through line 186 and is passed into the HDDC zone 98. This fraction has a boiling point above about 1100 F.

In the HDDC zone the temperature i maintained between about 700 F. and 1000 F. and the pressure between about 100 and 5000 p.s.i.g. so that the conversion is carried out predominantly in the liquid phase. The feed rate of bottoms feed is between about 0.1 and v./v./hr. The hydrogenated diluent from line 96 is used in an amount about 0.1 to 2 parts by weight per 1 part by weight of residual feed passing through line 106.

In the HDDC step or zone the residuum or residual oil is converted to lower boiling hydrocarbons normally in the absence of extraneous hydrogen and in the absence of catalyst and is operated to give essentially 100% conversion on the fresh residuum per pass. An effective donor diluent used in proper concentration will provide sufficient active hydrogen to prevent coke formation but under some conditions it may be desirable to supplement the donor diluent with molecular hydrogen. In such cases the condensed ring aromatic compounds of the diluent act as homogeneous hydrogenation catalysts by consuming molecular hydrogen and transferring it to the cracked products from residuum. The reaction products from the HDDC zone 98 are passed through line 108 to fractionating tower 112 to separate lower boiling material from higher boiling liquids.

The bottoms from fractionating tower 112 are withdrawn through line 114 and recycled to the line 26 which feeds material to the vacuum distillation zone 27. A portion of this recycled material may be withdrawn from the process through line 116 to prevent accumulation of ash in the system. Alternatively, the bottoms from tower 112 may be recycled to the HDDC zone 98 through lines 114 and 117. Likewise, the bottoms from tower 12 may be used as feed to the HDDC zone 98 by proceeding through line 26 and line 99 which by-passes the vacuum tower 27. In the preferred operation, bottoms from both 12 and 112 are sent to vacuum tower 27 to recover distillate products and decrease the volume of feed to HDDC zone 98- A heavy gas oil fraction is withdrawn from the bottom of fractionating tower 112 through line 118. This fraction may be used as feed to catalytic cracking or hydrocracking, or as a fuel product. In a preferred operation to maximize gasoline yield, the heavy gas oil is catalytically cracked with recycle to 100% conversion. Higher up in the tower 112 a light gas oil fraction is withdrawn through line 122 and a portion of this gas oil fraction can be withdrawn from the system through line 124 as a low sulfur heating oil. A portion or all the oil fraction in line 124 can be recycled through line 68 for passage through hydrocracking zone 58. Any excess of bottoms from line 86 over that required for HDDC may also be recycled to hydrocracker 58 through line 60. Another portion of the light gas oil from line 122 may be passed through line 94 and recycled to the hydrogenation zone 92 as hereinbefore described. This fraction contains aromatic compounds which are partially hydrogenated in the zone 92 and form excellent diluents for the HDDC step.

Further up in the tower 112 a heavy naphtha fraction is withdrawn as a side stream through line 126 and this fraction is preferably recycled to line 16 to be hydro formed along with the virgin naphtha from tower 12. From the upper portion of the tower 112 a light naphtha fraction is withdrawn as a side streamthrough line 128 and added to the gasoline pool. In some cases it may be desirable to improve quality of the fraction in line 128 by desulfurization, hydrofinishing, isomerization, etc. Withdrawn overhead through line 132 is a gaseous fraction containing C hydrocarbons and lower.

The heavy gas oil fraction withdrawn through line 24 from tower 12 is preferably used as feed to catalytic cracking or hydrocracking. Although the catalytic cracking and its companion fractionation facilities have not been shown in the drawing, it is evident that further economies can be effected by integration with the various fractionation facilities of this invention.

Referring now to FIG. 2, whole crude oil is passed through line 152 into fractionating tower 154 to separate the lower boiling hydrocarbons and gas overhead through line 156. A heavy naphtha fraction is withdrawn through line 158 and passed to hydroforming zone 162 which is operated under similar conditions to those described in connection with FIG. 1. Hydrogen-containing gas from line 164 is also introduced into line 158.

The hydroformed products are passed through line 166 to fractionating tower 168 to separate hydrogen-containing gas which is withdrawn overhead through line 172 and in part recycled to the hydroforming zone 162 through line 164. A normally gaseous hydrocarbon fraction is withdrawn from the upper part of the tower 168 through line 174 as a side stream. Lower down a gasoline fraction is withdrawn as a side stream through line 176. The bottoms fraction withdrawn through line 178 contains hydrocarbons higher boiling than about 430 F. It is mixed with the gas oil in line 180 and hydrocracked in zone 181. Make-up hydrogen can be introduced into line 164 through line 182. Excess hydrogen can be withdrawn through line 184.

A kerosene fraction is withdrawn through line 186 from tower 154 and treated as described earlier in FIG. 1, tower 12, line 18. Further down in the tower 154 a gas oil fraction is withdrawn through line 188. This fraction may be used as heating oil, but it is preferably hydrocracked or catalytically cracked. In one preferred operation to maximize gasoline yield, the entire boiling range between heavy naphtha and vacuum gas oil may be hydrocracked to complete conversion in a recycle operation. Lower down in the tower 154 a higher boiling fraction or a heavy gas oil boiling between about 650 F. and 1050 F. is withdrawn through line 180 and passed into the hydrocracking zone 181 which is similar to that described at 58 in connection with FIG. 1. Also introduced with the feed is hydrogen-containing gas from line 196 which in part forms hydrogen-containing gas recycled from the hydrocracking step and in part from line 198 from the hydroforming step.

The hydrocracked products are passed through line 202 to a knockout drum 204 for separating gases from by drocarbon liquids. Using a heavy gas oil as feed for the hydrocracking step yields aromatic material boiling in the range of 600 F.1000 P. which is suitable for use as a hydrogen donor diluent in HDDC. The gases containing hydrogen pass overhead through line 266 and a conventional scrubber 208 for removing impurities from the hydrogen-containing gas and the gas is recycled through line 196 to the hydrocracking zone 181. A portion of the gas may be bled off from line 196 through line 212.

A bottoms fraction from knockout drum 204 containing substantially all the normally liquid hydrocarbons is withdrawn through line 214 and passed to fractionating tower 216.

In tower 216, C hydrocarbons are withdrawn overhead through line 218 and a C fraction is withdrawn from the upper portion of the tower 216 through line 222. A naphtha fraction is withdrawn from the tower 216 as a side stream through line 224 and is preferably recycled to the hydroforrning zone 162.

Lower down in the fractionating tower a gas oil fraction boiling in the range of 430 F.700 F is withdrawn through line 226 and passed through the hydrogenation zone 228 into which hydrogen is introduced through line 232 for partially hydrogenating aromatic hydrocarbons to produce hydrogen donor diluent compounds. The bydrogenation zone 228 is similar to that at 92 described-in connection with FIG. 1. Hydrogen from the hydroforming step is used. In addition, a heavy gas oil fraction boiling between about 700 F. and 900 F. is withdrawn from the lower portion of the fractionating tower 216 and is withdrawn as a side stream through line 234 and may be recycled through line 236 to the hydrogenation zone 228 or may be recycled through line 238 to the hydrocracking zone 181 or catalytically cracked. Line 239 shows leading the stream similar to that in line 238 to bydrocracking zone 181.

The bottoms fraction boiling above about 900 F. from fractionating tower 216 is withdrawn through line 242 and mixed with the bottoms withdrawn through line 244 from the main fractionating tower 154 and this mixture is passed into the vacuum distillation tower 246. A portion of the stream in line 242 can be bled off through line 247 to prevent build up of ash in the system. The vacuum gas oil fraction boiling above about 900 F. is withdrawn overhead through line 248 and contains virgin constituents and also HDDC constituents. This stream is preferably used as feed to catalytic cracking or lended into heavy fuel. The bottoms from the vacuum distillation zone 246 are withdrawn through line 252 and introduced into the HDDC zone 254 which is similar to the HDDC zone 98 shown and described in connection with FIG. 1. The hydrogenated products from by drogenation zone 228 are passed through line 256 into HDDC unit 254 for converting the residual oil withdrawn from the vacuum tower 246.

The reaction products from HDDC zone 254 are passed through line 258 and flashed to a 430 F. cut point in fractionating tower 262. A C fraction is passed overhead through line 264 and a light naphtha fraction is withdrawn as a side stream from the upper portion of the tower through line 266. A heavy naphtha fraction is withdrawn as a side stream from the tower 262 through line 268 and is preferably recycled to the hydroforming zone 162.

The bottoms boiling above about 430 F. are Withdrawn from the tower 262 through line 272 and recycled to the fractionating tower 216 where they are further fractionated in the hydrocracking products fractionator 216 to separate and recover spent donor diluent mixed with make-up diluent precursor from hydrocracking 181.

Referring now to FIG. 1, an example will be given in which 200,000 b.d. of whole petroleum crude oil is separated and processed. Using West Texas crude oil and fractionating it in the tower 12, the light naphtha overhead fraction in line 14 has a boiling point up to about 200 F. and about 16,000 b./d. are removed and placed in the gasoline pool. The heavy naphtha fraction in line 16 has a boiling range between about 200 and 430 F. and the amount of naphtha withdrawn is about 47,000 b./ d.

The kerosene fraction withdrawn through line 18 has a boiling range of about 430 to 490 F. and the amount withdrawn is about 13,000 b./d. The hydrocracking feed stock in line 22 has a boiling range of about 490 to 700 F. and the amount withdrawn is about 42,000 b./d. The heavy gas oil withdrawn through line 24 has a boiling range between about 700 and 900 F. and the amount withdrawn is about 28,000 b./d. The bottoms withdrawn through line 26 boils above about 900 F. and the amount withdrawn is about 54,000 b./d.

The 200 to 430 F. fraction is heated up and passed to the hydroforming zone 32 together with hydrogencontaining gas introduced through line 28. The amount of hydrogen introduce-d is about 5,000 s.c.f/b. of feed. The temperature in zone 32 is about 930 F. and the pressure about 250 p.s.i.g. The catalyst is a platinumalumina catalyst containing about 0.6 wt. percent platinum. The reaction products are passed through line 34 and fractionated in the tower 36 to separate a C 430 F. gasoline fraction of about 95 research octane number. The amount of this gasoline fraction is about 39,900 b./d.

The 490 to 700 F. hydrocracking feed is passed through the hydrocracking zone 58 together with about 5,000

Yields Wt. Vol. 13 D percent percent The octane number of the gasoline is about 89.7 research clear and 88.3 motor+3 cc. lead. Operation at lower temperatures, such as 600750 F., produces much higher yields of gasoline but somewhat lower octane number. If yield is maximized in the hydrocracking stage, the gasoline may require hydroforming to improve quality.

The bottoms from the knockout drum 72 in an amount of about 12,180 b./d. pass through line 86 to the hydrogenation zone 92 together with 11,000 b./d. recycle from line 94. The recycle in line 94 has a boiling range between about 430 F. and 650 F. Hydrogen-containing gas from line 42 is passed to zone 92. The aromatic bottoms fraction in line 86 boils in the range of about 430 to 700 F. and this fraction together with the recycle from line 94 is partially hydrogenated over a sulfur resistant catalyst such as cobalt molybdate, until about to 1000, preferably 200 to 600, cubic feet of hydrogen has been added per barrel of feed to the hydrogenation zone 92 to produce hydrogen donor diluent compounds. The hydrogen donor diluent fraction is then mixed with about an equivalent amount of crude residuum from line 106 plus the unconverted recycle bottoms from the HDDC step. The oil feed in line 106 to the noncatalytic HDDC zone 98 includes 26,000 b./d. of virgin residuum and 19,000 b./d. of recycle HDDC. Data on the HDDC conversion of the residuum are as follows:

ing 12,000 490/700 F. Diluent recycle 11,000 Temperature, F. 880 Pressure, p.s.i.g 400 Feed rate, v./hr./v. 4 Yields on total feed-i-diluent, b./d,:

C gas (2.3 wt. percent) C (0.9 vol. percent) 620 C /430 F. (16.8 vol. percent) 11,400 430/650 F. (28.4 vol. percent) 19,300 650/1l00 F. (27.1 vol. percent) 18,400 1l00 F.+ (28.0 vol. percent) (Recycle) The products from the HDDC step are fractionated in a separate atmospheric tower 112 to provide components for recycle as well as the final products. The naphtha formed in the HDDC step is of relatively low octane number and is preferably separated to provide a fraction suitable for hydroforming. The 900 F bottoms from the HDDC step are withdrawn from tower 112 through line 114 and vacuum distilled to about 1100 F. cut point in the same vacuum distillation tower 27 used in the distillation of the crude residual oil thereby effecting a blending of the recycle bottoms with fresh residuum which is withdrawn through line 106 and passed to the HDDC step or zone 98.

The flexibility of the process of the present invention is apparent since product distribution and quality can be varied at will by varying the severity of hydrocracking, HDDC and catalytic cracking, and the gasoline pool octane number can be varied by varying the quantity and the streams fed to the hydroforming step. Using the combination of steps shown in FIG. 1 and hydroforming the 200 F. to 430 F. virgin naphtha and the naphtha formed by the HDDC conversion to obtain 48,520 b./d. of gasoline, hydrocracking the 490 to 700 F. gas oil to 42.3 vol. percent gasoline to obtain 21,277 b./d. of gasoline and catalytically cracking the heavy gas oil 700 to 1100 F. to 45 vol. percent gasoline to obtain 33,480 b./d. of gasoline, a yield of 59.6 vol. percent of C 430 F. or 119,277 b./d. of gasoline is obtained with 92.1 research octane number (clear) and 100 octane number (leaded). Inclusion of C polymer and C alkylate into the gasoline pool will raise the yield to over 60 vol. percent on crude and the octane number still higher. Adding the hydroformer bottoms and the 430-490 F. kerosene fraction to the hydrocracker feed and operating the hydrocracker at lower temperatures to maximize gasoline yield increases the total gasoline yield to about 160,000 b./d. or 80 vol. percent on crude.

The maximum yield of gasoline from West Texas crude petroleum oil by conventional processing is about 52.9 vol. percent including C s and C polymer, obtained by catalytic cracking of the total gas oil and visbreaking the residuum. The gasoline obtained in this conventional processing has only 88.6 research octane number clear. If hydroforming and C alkylate are included, the yield only increases to about 55% and the octane number to about 92. Thus, it is apparent that the process of the present invention following the steps in FIG. 1 yields much more gasoline of higher octane number than is obtainable by conventional processing. Further, the present invention produces only distillate products since the HDDC conversion completely eliminates residual fuels.

If desired, the process can be changed to remove only a bottoms fraction boiling mainly in the range of 650 to 700 F. from tower 72 and, as this bottoms fraction contains aromatic hydrocarbons, it is an especially good feed feed for the hydrogenation step for zone 92 where the aromatic hydrocarbons are partially hydrogenated to produce the hydrogen donor diluent compounds. The hydrogen donor diluent makeup requirements for the HDDC conversion can be easily satisfied by varying the amount of aromatic hydrocarbon bottoms Withdrawn from the fractionator 72 used for fractionating the hydrocracked products. In this case, the major portion of the hydrogen donor diluent is obtained by recycling essentially all of a 500-700 F. cut from fractionator 112. A 430700 F. fraction would be separated in tower 72 according to this process variation and withdrawn through line 83. This product is a stable low sulfur, heating oil.

Instead of using a relatively narrow aromatic hydrocarbon fraetion, the hydrocracker feed and the product boiling ranges may be varied to yield an aromatic hydrocarbon fraction boiling in the range of about 600l000 F. which is also suitable for use as a hydrogen donor diluent in the HDDC conversion step. The choice of boiling range permits flexibility in the product distribution from the HDDC conversion. In the form shown in FIG. 2 the HDDC products are flashed to a. 430 F. cut point. The 430 F.| bottoms fraction is fractionated further in the fractionator 216 used to separate the hydrocracked products thereby adding fresh diluent makeup continuously to the spent diluent.

The octane number of the gasoline from hydrocracking can be varied by changing the hydrocracking severity. Furthermore, the properties of the 430 F.| bottoms can be varied appreciably by changing the cracking severity. Thus by integrating hydrocracking with HDDC, one can tailor-make the best diluent for HDDC. This is shown in the following table:

By increasing the hydrocracking severity from 47% to 68% conversion, it can be seen that the 430 F.+ bottoms increased in aromaticity to a remarkable extent as shown by the decrease in API gravity and the great decrease in aniline point. It has been shown that highly aromatic refinery streams boiling above 430 F. are excellent hydrogen donor diluents upon partially hydrogenating the condensed ring aromatics. The aromatic bottoms from the platinum hydrocracking step boil in the range 430700 F. and this fraction is utilized in the HDDC conversion step as shown in FIGS. 1 and 2.

Although several alternative refining schemes utilizing integrated hydrocracking-HDDC processes have been discussed, various other modifications can readily be visualized by those skilled in the art as a result of these disclosures. It is within the scope of this invention to include the various modifications which are necessary to fit the hydrocracking-HDDC process to any particular refinery. For example, this process can be combined in many different ways with a variety of other refining processes such as catalytic cracking, thermal cracking, isomerization, hydrofining, polymerization, etc. Similarly, it is obvious that each refinery situation will require different cut points for the various products as well as different choices of streams to segregate for specialty products or to combine or recycle to the various processes. Likewise, there will be wide variations in the conditions under which the various processes are operated depending on such things as crude oil types, desired product distribution, etc. Such variations and modifications are considered as coming within the teachings of this invention.

What is claimed is:

1. A process for treating hydrocarbons which includes separating a whole petroleum crude oil into a naphtha fraction, a gas oil fraction, and a bottoms fraction boiling above about 700 F., hydroforming said naphtha fraction to produce gasoline, hydrogen and higher boiling hydrocarbons, catalytically hydrocracking said gas oil fraction to produce gasoline and a higher boiling hydrocarbon fraction including polycyclic aromatic hydrocarbons, recycling hydrogen from said hydroforming step to said hydroforming and hydrocracking steps, partially hydrogenating said higher boiling fraction to produce partially hydrogenated polycyclic aromatic hydrocarbons as hydrogen donor diluents, mixing at least a portion of said bottoms fraction with said partially hydrogenated polycyclic aromatic hydrocarbons, passing said mixture to a thermal conversion zone to non-catalytically convert said bottoms fraction to lower boiling hydrocarbons including naphtha, and recovering a naphtha fraction from the last mentioned converted hydrocarbons.

2. A process according to claim 1 wherein said bottoms fraction is vacuum distilled to separate lower boiling hydrocarbons to produce a second bottoms fraction boiling above about 900 F. and said second bottoms fraction is passed to said non-catalytic thermal conversion step together with said partially hydrogenated polycyclic aromatic compounds.

3. A process according to claim 1 wherein said rcovcred naphtha fraction is recycled to said hydroforming step to produce additional gasoline.

4. A process according to claim 1 wherein the conversion products from said non-catalytic thermal conversion step are fractionated to separate a hydrogen donor diluent fraction containing partially hydrogenated aromatic condensed ring compounds and said last mentioned fraction is recycled to said non-catalytic conversion step.

5. A process according to claim 1 wherein the products from the said non-catalytic thermal conversion step are fractionated to separate a spent diluent fraction and said spent diluent fraction is recycled to said partially hydrogenating step to produce partially hydrogenated polycyclic aromatic hydrocarbons as hydrogen donor diluents and said partially hydrogenated fraction is recycled to said non-catalytic thermal conversion step.

6. In a hydrocarbon conversion process wherein a naphtha fraction is hydroformed and hydrogen is produced, a gas oil fraction is catalytically hydrocracked and a bottoms or residual fraction boiling above about 900 F. is separated from crude petroleum oil, the improvement which comprises catalytically hydrocracking at a temperature of about 1015 F. said gas oil fraction with hydrogen added from said hydroforming step to produce gasoline and a higher boiling fraction containing condensed ring aromatic hydrocarbons boiling above about 430 F, partially hydrogenating said higher boiling fraction to introduce on the average one to three hydrogen atoms into said aromatic hydrocarbon molecule and to produce partially hydrogenated condensed ring aromatic hydrocarbons which are useful as hydrogen donor diluents, mixing at least a portion of said partially hydrogenated condensed ring aromatic hydrocarbons with said bottoms or residual crude oil fraction, passing the last mentioned mixture through a non-catalytic conversion zone maintained at a temperature between about 700 F. and 1000 F., a pressure between about 100 p.s.i.g. and 5000 p.s.i.g., at an oil feed rate between 0.1 v./v./hr. and v./v./hr. and using said partially hydrogenated condensed ring aromatic hydrocarbons in a weight ratio of about 0.1 to 1 to 2 to 1 said bottoms or residual fraction to produce lower boiling hydrocarbons.

7. In a hydrocarbon conversion process wherein a naphtha fraction is hydroformed and hydrogen is produced, a gas oil fraction is catalytically hydrocracked and a bottoms or residual fraction boiling above about 900 F. is separated from crude petroleum oil, the improvement which comprises catalytically hydrocracking said gas oil fraction with hydrogen added from said hydroforming step to produce gasoline and a higher boiling fraction containing condensed ring aromatic hydrocarbons boiling above about 430 F., partially hydrogenating said higher boiling 'fraction to produce partially hydrogenated condensed ring aromatic hydrocarbons which are useful as hydrogen donor diluen'ts, mixing at least a portion of said partially hydrogenated condensed ring aromatic hydrocarbons with said bottoms or residual crude oil frac tion, and passing the last mentioned mixture through a non-catalytic thermal conversion zone to produce lower boiling hydrocarbons.

8. The process according to claim 7 wherein the conversion products from said non-catalytic thermal conversion zone are fractionated to separate a spent hydrogen diluent, said spent hydrogen diluent is recycled to said partial hydrogenation step to produce fresh hydrogen donor diluent and said fresh hydrogen donor diluent is recycled to said non-catalytic thermal conversion zone.

9. A process according to claim 6 wherein said lower boiling hydrocarbons are treated to recover a naphtha fraction and the naphtha fraction is recycled to the hydroforming step.

10. A process according to claim 1 wherein all the hydrogen necessary for the hydroforming step, the hydrocracking step and the hydrogenation of the polycyclic aromatic hydrocarbons is obtained from said hydroforming step.

11. A process according to claim 1 wherein substantially all of said crude oil feed is converted to distillate stocks in the process.

12. A process according to claim 1 wherein the polycyclic aromatic hydrocarbons which are partially hydrogenated to form hydrogen donor diluents are obtained entirely in the process without need of makeup extraneous donor diluents.

References Cited by the Examiner UNITED STATES PATENTS 2,843,530 7/1958 Langer et al. 20856 2,932,611 4/1960 Scott et al. 208 3,008,895 11/1961 Hansford et al. 208112 3,019,180 1/1962 Schreiner et al. 20879 3,092,567 6/1963 Kozlowski et al. 20857 3,132,086 5/1964 Kelly et al 208112 3,147,206 9/1964 Tulleners 208111 DELBERT E. GANTZ, Primary Examiner.

ALPHONSO D. SULLIVAN, Examiner.

A. RIMENS, Assistant Examiner.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3,252,888 May 24, 1966 Arthur w. Langer, Jr., et a1.

It is hereby certified that error appears in the above numbered patent requiring correction and that the said Letters Patent should read as corrected below.

In the drawings, Sheet 1, FIG. 1, in approximately the middle of the figure, for "8" read 86 column 11, line 22, for "atoms" read molecules Signed and sealed this 3rd day of December 1968.

EAL)

test:

ward M. Fletcher, Jr. EDWARD J. BRENNER testing Officer Commissioner of Patents

Claims (1)

1. A PROCESS FOR TREATING HYDROCARBONS WHICH INCLUDES SEPARATING A WHOLE PETROLEUM CRUDE OIL INTO A NAPHTHA FRACTION, A GAS OIL FRACTION, AND A BOTTOMS FRACTION BOILING ABOVE ABOUT 700*F., HYDROFORMING SAID NAPHTHA FRACTION TO PRODUCE GASOLINE, HYDROGEN AND HIGHER BOILING HYDROCARBONS, CATALYTICALLY HYDROCRACKING SAID GAS OIL FRACTION TO PRODUCE GASOLINE AND A HIGHER BOILING HYDROCARBON FRACTION INCLUDING PLYCYCLIC AROMATIC HYDROCARBONS, RECYCLING HYDROGEN FROM SAID HYDROFORMING STEP TO SAID HYDROFORMING AND HYDROCRACKING STEPS, PARTIALLY HYDROGENATING SAID HIGHER BOILING FRACTION TO PRODUCE PARTIALLY HYDROGENATED POLYCYCLIC HYDROCARBONS AS HYDROGEN DONOR DILUENTS, MIXING AT LEAST A PORTION OF SAID BOT-

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