US2526966A - Treatment and transportation of hydrocarbons - Google Patents

Description

Oct. 24, 1950 G. G. OBERFELL EI'AL TREATMENT AND TRANSPORTATION OF HYDROCARBONS Filed Dec. 15, 1947 2 Sheets-Sheet l OIL t; IO 5 f; n: i g O ISOMER- I RAW o f f E '3 IZATION NATURAL U 28 l GAS 2 m '6 E is 29 30 I ll q 4 I 5 l9 1 l4 NATURAL J GASOLINE 1 I 7o I 6| 1 66 I 12 4 64 65 [SOMER- sa .T 1- l g I E IZATION I TOPP|NG "7 STRA|GHT I STILL RUN 62 GASOLINE 73 I 68 74 W J 85 as l HYDRO g GENATION 18 f 84 83 I 7 GASOLINE 77 88 l SETTLER I L 4 f4 1 x PIPE LlNE 1, 5,

g 80 INVENTOR.

- (3.6. OBERFELL FIG R.C. ALDEN ATTORNEYS Patented Oct. 24, 1950 TREATMENT AND TRANSPORTATION OF HYDROCARBONS George Grover Oberfell and Richard C. Alden, Bartlesville, 0kla., assignors to Phillips Petroleum Company, a corporation of Delaware Application December 15, 1947, Serial No. 791,678 2 Claims. (cries-1 This invention relates to a combination process for treating hydrocarbons.- In one of its more specific aspects it relates to a combination proc ess for increasing the output of a natural gasoline plant and for effecting economy in the transfer of petroleum products from production site to refinery.

In the petroleum industry today there is the constant problem of producing more and better petroleum products, with as little waste as possible, more quickly and economically, thus giving the public products of high quality at reasonable prices. This invention, which is a combination process, is another step toward solving this problem.

Natural gasoline plants as they are known today are actually plants for the separation and removal of C2 and heavier hydrocarbons from natural gas. Very little treating of the gasoline takes place in them. After the heavy products have been recovered they are transported by the most convenient method, usually a. pipe line, to the nearest refinery for further treatment such as blending, sweetening, cracking, and other known refining processes.

The practice of this invention will enable a natural gasoline plant to produce other products in addition to natural gasoline, and to become a still more important link in the petroleum industry. This invention is especially applicable to those oil fields where light gases, boiling below the gasoline range, are burned in flares, or removed by some other wasteful means. Further, the practice of this invention provides a means for reducing the cost of transporting topped crude oil from an oil field to a distant refinery.

In preparing a natural gasoline plant for the practice of this invention, minimum additional equipment is required, thus also tending toward economy. It is conceivable that more than one gasoline plant within the same area may be operated in conjunction with one another, pooling their products, and producing a high yield of valuable motor fuel components.

An object of this invention is to provide a method for increasing the output of natural gasoline plants.

Another object is to convert normally gaseous hydrocarbons to gasoline by an economical combination process.

A further object is to render topped crude oil more amenable to transfer by pipe line.

A further object is to make topped crude oil more amenable to refining processes.

Another object is to make transfer of petrole- 2 um and its products to distant refineries, via pipe line, more economical.

Other objects and advantages of this invention will be apparent to one skilled in the art from the accompanying disclosure and discussion.

In the preferred practice of this invention natural gas from an oil or gas field, or a portion thereof, is piped to a natural gasoline plant. The gas is passed through suitable separating equipment. The C2 and heavier materials may be removed by such means as absorption, and then passed to a fractionation unit where the light gases and natural gasoline are separated. A normal butane fraction is passed through suitable equipment and isomerized to isobutane. An ethane and propane fraction is dehydrogenated producing ethylene, propylene, and hydrogen, of which the ethylene and propylene may be alkyi ated with the isobutane to obtain diisopropyl, isooctane, neohexane, C6 to C9 isomers, and other gasoline range products. In addition, ethylene and propylene may be passed to a polymerization unit in which the olefins are converted to polymer gasoline. Raw crude oil, produced at the same general geographic location, is passed to a topping unit which removes light hydrocarbons and straight run gasoline. The remaining topped v crude is mildly hydrogenated, the main purpose of which is to increase the fluidity of the crude, so that it may be pumped more easily, and to purify it and make it more susceptible to refining proc esses. The more fluid a. crude oil the more easily is it transferred through pipe lines at a lower cost.

The hydrogenated crude may be introduced and pumped through a pipe line in several ways. One method is to pass it directly to a pipe line after hydrogenation; a second method is to remix with the hydrogenated crude oil the light hydrocarbons and straight run gasoline removed in the topping operation, so that they may act as a diluent to facilitate pumping; and a third method is to admix. any or all of the natural gasoline recovered from the natural gas, alkylate, polymer gasoline, and/or the straight run gasoline. In using either of the last two methods, the crude oil and additional constituents are separated upon arrival at a refinery, and the hydrogenated topped crude is passed to a thermal and/or catalytic cracking unit.

A more clear understanding of some of the many aspects of our invention may be had by referring to the attached schematic flow diagram designated as Figures 1 and 1-A, which are to be aeeaoeo placed together on the dashed lines. The description of this flow diagram, and of the individual process units included in it, will serve to exemplify our invention.

Raw natural gas is introduced to absorber I3 through line H where it is contacted with absorber oil introduced through line I2 at a pressure in the range of 100 to 200 pounds per square inch. High purity methane is withdrawn from absorber through line [3. Enriched absorber oil is removed through line H to stripper I5 in which it is heated to remove absorbed hydrocarbons. Stripped absorber oil is recycled through lines is and I2 to absorber H). A hydrocarbon mixture containing ethane and heavier materials is passed through line I! to fractionator l8 from which stabilized natural gasoline is withdrawn through line it to natural gasoline storage unit 20. A light fraction containing ethane and propane is removed from iractionator it through line 2! and passed through lines 23 and 24 to dehydrogenation unit 25. If desired, ethane and propane may be dehydrogenated separately, by means not shown. An isobutane fraction is withdrawn through line 26, and passed through lines 21 and 32 to alkylation unit 33. A normal butane fraction is withdrawn from fractionator l8 and passed through line 28 to isomerization unit 29. Eiiluent from isomerization unit 29 is removed through line 30 and passed, with the isobutane from fractionator l8, through lines 26, 27, and 32 to alkylation unit 33.

Isomerization unit 29 is operated under conditions familiar to those skilled in the art and known to be suitable for conversion of normal butane to isobutane. A wide variety of conditions and catalysts may be used. It is preferred,

however, to use aluminum chloride supported on bauxite as a catalyst, a temperature in the range of 200 to 300 F., and a pressure in the range of 250 to 350 pounds per square inch. It is usually desirable to promote the isomerization reaction with hydrogen chloride.

Ethane and propane which have been passed to dehydrogenation unit 25 are dehydrogenated to obtain ethylene and propylene. The dehydrogenation may be carried out at a temperature in the range or 1000 to 1300 F., at about atmospheric pressure, with a gaseous space velocity of 650 to 2500 volumes of gas per volume of catalyst per hour, and in the presence of an aluminachromia-beryllia catalyst. Other catalysts may be used as desired and the operating conditions may vary somewhat for each diflerent catalyst. In some instances, it may be found desirable to operate in the absence of a catalyst; this will result in an increased yield of methane and ethylene and a smaller yield of propylene. Dehydrogenation effluent is passed through line 34 to fractionator 35 where a light fraction comprising hydrogen and methane is separated and withdrawn through line 36. If desired, methane may be removed from this fraction by means not shown. A fraction containing ethylene is withdrawn and passed through lines 31 and 32 to alkylation unit 33. Another fraction containing propylene is removed and passed through lines 39 and 40 to polymerization unit 42. Alternatively, a portion of the ethylene fraction may be passed through lines 31, 43, and 40 to polymerization unit 42, and/or a portion of the propylene fraction may be passed through lines 39, 21 and 32 to alkylation unit 33.

Polymerization of ethylene and propylene in unit 42 ma be obtained over catalysts such as nickel oxide, supported phosphoric acid, and silica alumina. Suitable operating conditions for a nickel oxide catalyst are: a temperature of 0 to 450 F., a pressure of atmospheric to 200 pounds per square inch, and substantially liquid phase. More specific conditions will depend upon the products desired and will be readily selected by one skilled in the art.

Isobutane is introduced through line 32 to alkylation unit 33 where it is alkylated with ethylene or propylene, or ethylene and propylene. A fluid aluminum chloride-hydrocarbon complex catalyst containing free aluminum chloride is introduced to alkylation unit 33 through line 44. Alkylation unit 33 is operated under conditions suitable for the preparation of dlisopropyl alkylate, preferably as described by H. J. Hepp in U. S. Patent 2,410,498, issued in 1946. Other products from alkylation unit 33 may be isooctane, neohexane, etc. Eflluents from alkylation unit 33 are passed through line 45 to settler 46 in which a hydrocarbon phase separates from a catalyst phase. The catalyst phase is withdrawn through line 41 and at least a, portion is passed to an aluminum chloride recovery unit not shown. The remainder is recycled through lines 43 and 44 to alkylation unit 33. The hydrocarbon phase is passed through line 49 to fractionator 50. From fractionator 50 an ethane-propane fraction is removed through line 22 and recycled through lines 23 and 24 to dehydrogenating unit 25. An isobutane fraction is removed through line 33 and recycled through line 32 to alkylation unit 33. A normal butane fraction is removed through line 53 and recycled through line 28 to isomerization unit 29. A normall liquid fraction containing diisopropyl alkylate and other alkylation products is removed from fractionator 50 through line 54 to allrylate storage unit 55.

The capacity of alkylation unit 33 is limited by the amount of excess butane recoverable from the raw natural gas (excess butane is that butane recovered in the stabilization of the natural gasoline). In many cases the amount of ethylene and propylene potentially available from the recovered ethane and propane is greatly in excess of the isobutane that is potentially producible, thus, only part of the potential supply of ethylene and propylene may be used in alkylation unit 33. In order to convert excess ethylene and propylene to gasoline, lines 43 and 40 are provided to remove ethylene and propylene that cannot be used in alkylation unit 33 and to pass same to polymerization unit 42. In unit 42 ethylene and propylene are catalyticall polymerized to heavier hydrocarbons. Suitable polymerization catalysts include nickel oxide, supported phosphoric acid, silica-alumina, etc. Specific conditions for polymerization will depend to some extent upon the composition of the feed stock and on the specific catalyst used. Polymerization eilluent is passed through line 56 to fractionator 51 where a normally gaseous fraction is removed and recycled to dehydrogenation unit 25 through lines 58 and 24. A normally liquid fraction, boiling for the most part within the gasoline range, is withdrawn through line 59 and passed to polymer gasoline storage unit 30.

Raw crude oil is introduced to the system through line 62 to topping still 63 in which straight run gasoline and light gases are separated. From topping still 63 light gases are removed through line' 6i and passed through line 64 to isomerization unit 35. If desired, at least a portion of the light gases ma be passed to is increased above that of the charge.

. rather wide range.

'fractionator I8 through lines SI, and I! for treatment as desprlbed above. Straight run gasoline from topping still 03 is passed through line 01 to straight run gasoline storage 68. If desired, a portion of the straight run gasoline may be passed through linesv 61, 81 and 64 to isomerization unit 65 and/or through lines 61, 81, 64, 66, 21 and 32 to alkylation unit 33., Isomerization unit 65 is operated under conditions known to those skilled in the art, such as in liquid phase at 100 to 300' F. in the presence of a liquid hydrocarbon-aluminum chloride catalyst, in such a manner that the octane number of the product Isomerization products are passed to straight run gasoline storage unit 68 through line I3. If desired, material from natural gasoline storage unit 20 may be passed to isomerization unit 65 through lines 10, I2, and 60, and/or t alkylation unit 33 through lines 10, I2, 64, 66, 21, and 32.

Topped crude is withdrawn from topping still .63 to hydrogenation unit I through line It.

which not only purifies the crude oil from nitrogen and sulfur compounds, but also upgrades the asphaltic constituents, increases its fluidity, and makes it more easily refined. It is preferred to conduct the hydrogenation of topped crude in the presence of molybdenum oxide-alumina or molybdenum sulfide catalyst at a temperature in the ran e of 550 to 800 F., a pressure in the range of 2000 to 6000 pounds per square inch, a liquid space Velocity of 1 to liquid volumes of charge per volume of catalyst per hour, and a hydrogen circulation of 2500 to 6000 cubic feet per barrel of charge. Exact conditions used in any particular case will depend upon the properties of the topped crude being treated, particularly its refractoriness, and may vary within a It is preferred not to obtain extensive hydrogenolysis during this step, the main purpose being to increase the fluidity of the topped crude, and to make it a better charge stock for subsequent refinery processes.

Effluent from hydrogenation unit I5 is withdrawn through line 16 to settler 11 which may be operated at an elevated pressure, inasmuch as its purpose is to separate excess hydrogen from liquid and liquefiable hydrocarbon materials. separated hydrogen is recycled to hydrogenation unit I5 through lines I8 and 36. From settler I'I hydrogenated material is removed through line 19 to pipe line 80, and is pumped by pumps 8| t a distant refinery at a different and distant geographic location. In another embodiment, low-boiling liquid hydrocarbons removed from the crude oil in topping still 63 may be passed through lines GI, 64, 81, and 61, respectively, or through lines GI, 64, 81, 69 and II to line I9 where they are mixed with the mildly hydrogenated crude, thus further improving its fluidity. In another embodiment, natural gasoline from storage unit may be added to the hydrogenated crude through lines I0 and II, straight run gasoother piping arrangements may be made for' passing the products of this invention to the hydrogenated crude pumped through pipe line to a distant refinery. The above mentioned piping arrangements are not to be interpreted as limitations upon the process.

Hydrogenated topped crude, produced in conjunction with natural gasoline as just discussed,

enters a refinery from pipe line 80 through line 93, and may be passed to a refining process such as catalytic cracking in cracking unit 94. However, if some of the gasoline or alkylate products from the natural gasoline plant have been added to the crude, as described above, it'is desrable to pass the material from the pipe line through lines 93 and I03 to fractionator 96 in which various fractions may be separated and removed. For example, gasoline may be removed through line 91 to unit I00 for further treatment, kerosene may be removed through line 98 to unit IN, and a diesel fuel ma be removed through line 99 to unit I02. Residue from fractionator 96 comprising primarily hydrogen- .ated topped crude is passed through lines and 93, or hydrogenated topped crude direct from pipe line 80 is passed through line 93, to cracking unit 90. As an example, the topped crude may be catalytically cracked over such catalysts as silica-alumina or silica-magnesia. Suitable reaction conditions may be a temperature in the range of 850 to 1100 F., a, pressure from atmospheric to 100 pounds per square inch gauge, steam diluent in an amount of about 60 pounds per barrel of oil, and a space velocity in a fixed bed process of about 1 to 10 liquid volumes of charge per volume of catalyst per hour. The steam diluent is added to reduce carbon deposition on the catalyst and to improve the quality of the products. As a further example, the topped crude may be cracked in a fluid catalytic cracking process util zing a suspended finely divided catalyst. Effluent from cracking unit 94 is passed through line IIO to separation unit I04 from which normally gaseous materials are withdrawn through line I05. Gasoline range'hydrocarbons are removed through line I06 to treater I 01. Hydrocarbons heavier than gasoline are recycled from separation unit I04 through lines I II and 93 to cracking unit 94. Under certain conditions, it may be desirable to admix products from fractionator 96 with the cracked gasoline from cracking unit 94. Finished gasoline is removed from. treater I01 through line I08 to cracked gasoline storage unit I09. Other conventional commercial products may be produced from the hydrogenated crude. as desired. From this disclosure it may be seen that the output of a natural gasoline plant may be greatly increased and the variety of products from such a plant enlarged. Another great disadvantage is the reduction in transportation cost, and improvement as a cracking stock of topped crude oil by means of mild hydrogenation.

Although this process has been described and exemplified in terms of its preferred modifications, it is understood that various changes may assumes be made without departing from the spirit and scope of the disclosure and of the claims.

We claim: 7

1. An improved process for increasing the output of natural gasoline plants and for effecting economy in the transfer of petroleum products from production site to refinery, which comprises recovering ethane and heavier hydrocarbons from a raw natural gas, iractionating said ethane and heavier hydrocarbons obtaining an ethanepropane fraction, an isobutane fraction, a normal butane fraction, and a stabilized natural gasoline fraction, isomerizing said normal butane to isobutane, dehydrogenating said ethane-propane fraction obtaining ethylene, propylene, and hydrogen, alkylating said 'isobutane fraction and isobutane obtained from the isomerization of said normal butane with a portion of olefins resulting from said dehydrogenation to form hydrocarbons boiling in the gasoline range, polymerizing a further portion of olefins produced by said dehydrogenation to obtain polymer gasoline, controlling the quantities of reactants to the above steps in such a manner that the desired quantities of each gasoline are produced to provide the desired blend, topping an asphaltic raw crude oil and recovering therefrom a straight run gasoline and light gases, hydrogenating the resulting topped crude with hydrogen produced by said dehydrogenation of ethane and propane, under conditions such as to remove sulfur compounds contained therein and upgrade asphaltic constituents, said hydrogenated topped crude being more amenable to pumping and subsequent refining, blending together the gasolines produced as described hereinabove, admixing with said hydrogenated topped crude the aforesaid blended gasoline products as a diluent, and pumping said mixture through a cross-country pipe line to a distant refinery, i'ractionating said oil-gasoline mixture at said refinery into a high quality motor fuel stock and a heavier hydrogenated topped crude, and cracking said topped crude to produce additional motor fuel stock.

2. An improved process for the conversion and transportation of naturally occurring hydrocarbon mixtures which comprises obtaining from natural sources in a first geographical location natural gas and an impure and asphaltic crude oil, removing from the natural gas gasoline range hydrocarbons as natural gasoline, removing from the crude oil material boiling in and below the gasoline range, subjecting the lighter than gasoline hydrocarbons to processes for the manufacture of gasoline by alkylation and polymerization resulting in the formation of by-product hydrogen, subjecting the topped crude to mild hydrogenation with said by-product hydrogen, blending the gasoline products and admixing said blend with the topped hydrogenated crude to act as a diluent therefor, pumping said admixture via pipe line to a refinery in a second geographical location, separating and recovering the gasoline from the topped crude at said refinery, and further treating the topped crude by cracking to produce gasoline range materials.

GEORGE GROVER OBERFELL. RICHARD C. ALDEN.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,762,423 Scharpenberg June 10, 1930 1,933,047 Clark Oct. 31, 1933 2,225,814 Youker Dec. 24, 1940 2,376,077 Oberfell et al. May 15, 1945

Claims (1)

1. 2. AN IMPROVED PROCESS FOR THE CONVERSION AND TRANSPORTATION OF NATURALLY OCCURRING HYDROCARBON MIXTURES WHICH COMPRISES OBTAINING FROM NATURAL SOURCES IN A FIRST GEOGRAPHICAL LOCATION NATURAL GAS AND AN IMPURE AND ASPHALTIC CRUDE OIL, REMOVING FROM THE NATURAL GAS GASOLINE RANGE HYDROCARBONS AS NATURAL GASOLINE, REMOVING FROM THE CRUDE OIL MATERIAL BOILING IN AND BELOW THE GASOLINE RANGE, SUBJECTING THE LIGHTER THAN GASOLINE HYDROCARBONS TO PROCESSES FOR THE MANUFACTURE OF GASOLINE BY ALKYLATION AND POLYMERIZATION RESULTING IN THE FORMATION OF BY-PRODUCT HYDROGEN, SUBJECTING THE TOPPED CRUDE TO MILD HYDROGENATION WITH SAID BY-PRODUCT HYDROGEN, BLENDING THE GASOLINE PRODUCTS AND ADMIXING SAID BLEND WITH THE TOPPED HYDROGENATED CRUDE TO ACT AS A DILUENT THEREFOR, PUMPING SIAD ADMIXTURE VIA PIPE LINE TO A REFINERY IN A SECOND GEOGRAPHICAL LOCATION, SEPARATING AND RECOVERING THE GASOLINE FROM THE TOPPED CRUDE AT SAID REFINERY, AND FURTHER TREATING THE TOPPED CRUDE BY CRACKING TO PRODUCE GASOLINE RANGE MATERIALS.

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