US1997159A - Treatment of hydrocarbon oils - Google Patents

Description

' April 9,1935. c. c. TowNE 4 TREATMENT OF HYDROCARBON OILS Filed Feb.v 6, 1932 meu-.s a raw/vf INVENTOR Patented4 Apr. 9, 1935 [UNITED ls'rxrlazs PATENT OFFICE TREATMENT' 0F HYDROCABBON OILS Charles C. Towne, Poughkeepsie,`N. Y., assignor to The Texas Company, New York, N. Y., a corporation of Delaware Application February s, 1932, serial No. '591,306

5 claims. (01. 19e- 52) 5 of improved anti-knock quality by converting paraffin hydrocarbons into compounds of 'anti-knock property.

According to the invention hydrocarbon oils such as petroleum naphthas or gasolines, particularly certain parafn oils such as straight run gasolines or other straight run petroleum fractions, may be reformed or converted into products of substantially the same boiling range but of high improved anti-knock value. The invention may also be useful in the treatment -of hydrocarbon oils of somewhat higher boiling point than the desired motor fuel, such as gas oil, wherein the oil may be subjected to high temperatures and high pressures to convert the oil into lower boiling products and simultaneously to transform the lower boiling hydrocarbons into compounds having a high anti-knock value. In the treatment of any oil it is advantageous to employ suillcient pressure to maintain that portion of the oil which is in effective contactwiththe catalyst in the liquid phase. The nature and scope of the invention will be further understood from the following description of the process and apparatus.

In order that the invention may be moreclearily understood reference will be made to the accompanying drawing in which the single figure is a diagrammatic view, partly in section, of one form of apparatus for carrying out the process of the invention.

In the gure, the reference character 2 represents a furnace" which isheated by the products of combustion from a burner 4. Positioned within the furnace are tubular heaters 6 and 8; the former located partly in the radiant and partly in the convection section, and the latter situated entirely in the cooler portion of -the convection section. Outside of and adjacent to the furnace 2 is another furnace setting I8 which surrounds the lower portion of the series of reaction vessels I2, I4 and` I6. A ilue I6 connects the furnace 2 with the furnace setting III whereby any or all of the products of combustion from the burner 4 may be conducted to the setting I0 or diverted to the stack 28 by suitable regulation of the dempers 22 and 24, respectively. An auxiliary burner 26 is adapted to supply additional heat to the setting III, if desired. A flue 28 serves to discharge the products of combustion whether from the nue I8. or the burner 26 to a stack (not shown).

A pump 20 interposed in fresh .feed line 32 charges oil to the inlet of coil 6. Transfer line 84 extends from the outlet of coil 6 to a point near the bottom of the first reaction vessel I2. Vapor lines 86 and 88 extend from the upper portion of vessels I2 and I4 to the lower portion of the succeeding vessels I4 and I6, respectively. lThe transfer line 34 and the vapor lines 36 and 88 are adapted to extend below the surfaces of the bodies of the catalyst in the lower portions of the reaction vessels. Pipes 42, 44 and 46 penetrate the bottoms of vessels I2, I4 and I6, respectively, to draw oi liquids from the vessels or to charge the catalyst thereto. Lines' 48 and 50 serve to transfer liquids from one vessel to another and also to maintain a certain level of liquid oil above the catalyst in the lower portions of the vessels.

A vapor line 52 extends from the top of the reaction vessel I6 to the lower portion of a vaporizer 54. A liquid line l56 connects the vessel I6 with the vaporizer 54 at a point above the point of entrance thereto of the vapors line 52. The lines 52 and 56 are provided with valves 58 'and 59, respectively, to control the pressure of the fluids passing therethrough. A pipe 60 extends tfrom the bottom of the vaporizer 54 to withdraw liquids therefrom and to conduct them to the line 62, referred to hereinafter, or to transfer them to a line 64 leading to storage (not shown) by suitable regulation of valves 66 and 68, respectively.

A vapor line 10 connects the upper portion of the vaporizer 54 with a fractionating column or fractionator' 12. A vapor pipe 14 extends from the top of the fractionator to a condenser coil 16, which in turn is yconnected'by a condensate line 18 to a receiver 80. The receiver 80 is provided with the usual gas release line 82 and liquid draw-off line 84. A reux condensate line 86 serves to withdraw the. condensate collecting in the bottom of the tower 12. A pipe 88 communi'- cating with the line 86 serves to conduct the condensate to storage or other suitable place of disposal, if desired. The line 62 in which is interposed a booster pump 88 is adapted to conduct the reux condensate withdrawn through line 86 to the heating coil 8 from whence it is transferred through line 92 into transfer line 84, or directly to the lower portion of reaction vessel I2. A by-pass line 84 serves to conduct the liquid from line 62 to coil 6 by suitable regulation of valves 86 and 98.

In one method of operation, using an appara tus such as shown in the drawing, an oil such as straight run gasoline or naphtha or other petroleum fraction partially cracked or uncracked of low anti-knock property containing hydrocarbons substantially within the boiling range of commercial gasoline, is charged by pump 86 In the coil the oil is raised to a conversion temperature and then transferred through line 84' through the feed line 32 into the heating coil.

liquid oil and the catalyst in the bottom of the vessels. The liquid level of the oil in the various vessels is maintained at a substantial depth by the pipes 48 and 50 connecting the various reaction vessels. The pipes 48 and 50 project into the vessels I4 and I6 below the end of the vapor lines 36 and 38, thereby creating a small differential pressure sufficient to cause the vapors to pass through the lines 36 and 38 and to maintain the desired depth of the oil inthe bottoms of the vessels. Y y

The reaction vessels may beheated, if desired, to maintain the proper temperature by passing the hot flue gases fromthe furnace 2 through the flue I8 and around the lower portions ofthe vessels. In some cases it is desirable to use an auxiliary burner, such as burner 26. The heating of the vessels is often essential in the early stages of the operation in order to keep theA catalyst in a molten condition, but after normal operating conditions are attained the heat carried to the vessels by-the hot oil owing continuously thereto through transfer line 34 mayV be sucient to maintain a proper temperature,

" and in the latter instance the uevgases may be diverted to the stack 20. The vessels I2, I4 and I6 are preferably constructed to-provide lar'ge vapor space for substantial digestion of the vapors passing therethrough. The tops of the reaction vessels are preferably cooler than the bottoms in order to knock back polymers or `other high boiling liquids onto the catalyst. The tops of the vessels are normally somewhat cooler than the portion within the furnace setting I0,.but nevertheless it is sometimes desirable to have positive cooling in the tops of the vessels and this may be done by well known methods, such as air cooling the exterior of the .vessels or by using cooling coils `in which an oil, say fresh charge, is preheated; also, it may be advantageous in some instancesl to provide a reflux tower above the vessels and to permit the condensate or polymers to run back onto the catalyst in the bottom of the vessels.

Vapors and liquid oil are transferred from th last vessel I6 through lines 52 and 56, respectively, to a vaporizer 54. The'vaporizer is usually mainltained under a substantially reduced pressure by suitable regulation of the control valves 58 and 59in order to promote vaporization of the lowerv boiling constituents. Vaporization and thorough stripping of the unvaporized oil is further enhanced by the counterflow of liquids and vapors in the lower baffled portion of the vaporizer. The

vapors released in the vaporizer 54 are fractionated in the tower ,12 and vapors of the desired end point for a finished distillate are conducted through vapor line 'I4 to the condenser and the distillate collected in the receiver.

The reflux condensate fromfractionator 12 is usually returned as a recycle stock to the heating coils either alone orv together with any or all of the liquids withdrawn from the bott'om of the vaporizer 54. The character of the liquids determines whether the recycle stock is heated in coil6 or coil 8. If the recycle stock has tendencies toward coke depositions in the coils it is advantageous to heat it separately in the coil 8. However, if there is no such advantage it may be combined with the fresh feed and heated inthe coil 5.

The catalyst employed in the reaction vessels comprises selenium and under normal operating conditions the catalyst is preferably in a molten condition.' While relatively pure metallic selenium is preferable for use according to the invention,. nevertheless it is contemplated that an impure form, such as a sludge, or in mixture with other materials to increase the volume or to alter the boiling or melting points. In case it is desired to use the catalyst in a form which may not be in a molten condition at the operating temperatures, then the catalyst may be suspended, loosely packed or arranged on trays or shelves in the reaction vessels in such a manner to provide efficient contact with the oil under treatment.

The catalytic effect of the selenium has been found to be essentially a reaction causing conversion of the parailins into aromatic compounds. It has been noted in this connection that the percentage of the other constituents of the treated oil, such as unsaturates and naphthenes, remain substantially unchanged during conversion or reforming but there is substantially a conversion of parafns into aromatics. A particularly significant effect of the catalyst is the decrease in the loss of hydrocarbons as polymers or tars compared with ordinary methods of conversion, and a resulting increase in ultimate yield of the desired motor fuel hydrocarbons. This increase maybe vdueto the prevention by the catalyst of polymerization and the resulting prevention of tar and coke formation, since in treating certain oils the formation of heavier hydrocarbons or polymers is substantially eliminated.

The temperatures employed in the process may vary somewhat, depending on the nature of the oil and on the anti-knock quality desired. In general, temperatures between 400 C. and 600 C. have been found to be satisfactory. In treating the lighter oils a temperature from 460 C. to 480 C. is particularly satisfactory for the production of a motor fuel having an octane number in the region of 80. It will, of course, be understood that higher or lower octane numbers may be obtained by varying the temperatures. When using two coils such as 6 and 8 of the drawing for separately treating the fresh charge and the recycle stock a temperature of 400 C. to 600 C. may be used on fresh feed heating coil 6 and a somewhat lower temperature, say 300 C. to 500 C. in the recycle stock heating coil 8.

H igh pressures have been found to be especially desirable for eicient operation of the process. Pressures may vary between 300-3000 pounds per square ingch and highly satisfactory results have been obtained at about 1500 pounds. f Higher temperatures and high pressures in the reaction vessels are preferable and in this way the reaction is substantially 'in the liquid phase. Itis not necessary, however, that vaporization of the oil be prevented but it is desirable to maintain the oilwhich is in effective contact with the catalyst in the liquid phase. 'I'he latter is brought about by maintaining sufficiently high pressures to retain the heavier fractions as liquids or to maintain the polymers in the liquid phase 2. The method of increasing the anti-knockA soldat the catalyst may'ccntact the ou in the liquid condition.

While the operation of the invention has been described in'connection with the reforming of gasoline or petroleum naphtha of low anti-knock value -into a motor fuel of high anti-knock value,`

' it will be understood that an oil of higher boiling range than commercial gasoline, for example, an oil containing the heavy ends of gasoline and light ends of gas oil, or a kerosene. or agas oil, or a recycle stock, or even a still heavier oil, may

be treated to advantage according to the invensubstantially reduced in the treatment of heavier oils as compared with that which normally occurs.

As an example of the results produced by my process, a straight run Pennsylvania gasoline of 40 octane number showing by analysis 3.4% 1msaturates, 6.8% aromatics, 12.8% naphthenes and 77% parains was treated according to the invention and a motor fuel of 70 octane number and having substantially the same boiling range was produced showing4.v2% unsaturates, 26.0%

aromatics, '15.1% naphthenes and 54.7% parafnns. Another sample of the oil reformed to the same octane number under similar conditions of temperature and pressure without the use of selenium as a catalyst produced an oil of 11.2% unsaturates, 15.3% aromatics, 24% naphthenes and 49.5% paramns, but the volume ofpolymers and other tarry compounds in the latter operation were" increased fourfold over that in which th catalyst was employed. Y

I am' aware that heretofore heavy hydrocarbon oils have been cracked at'substantially atmospheric pressure in the vapor phase in the presence of an alloy such as ferrous selenide which presents free selenium to the vapors and therefore no claim to such a process ismade in this application; Y

Obviously many modifications and variations of the invention. as hereinbefore set forth, may be made without departing from the spirit and scope thereof, and therefore only such limitations should be imposed as 4are indicated inthe appended claims.

l-I claim:

1. 'Ihe method of increasing'the anti-knock quality. of motor fuel that comprises maintaining a mass comprising selenium in the lower part of a reaction chamber, 'applying heat to said mass to maintain it. in a molten condition, introducing hydrocarbon oil comprising gasoline constituents into the reaction chamber and subjecting the hydrocarbons in contact with the seleniummasstoatemperaturewithintherangeofw- 600C.underapressureofupwardsof300 pounds, under conditions in which liquid conl stituents comprising polymer products of reac tionanddirectingtheresultingteinto contact with said seleniummas.

quality of motor fuel that comprises maintaining a mass comprising selenium in a reaction chamberl in a heated condition, introducing hydrocarbon oil comprising gasoline constituents into the reaction chamber, subjecting hydrocarbons in contact with the selenium mass to a temperature within the range of 400-600 C.

under a pressure of upwards of 300 pounds, under conditions in ,which liquid constituents com'- prising polymer products of reaction are in contact with the selenium mass, to eect conversion into constituents within the gasoline boiling range of increased 'anti-knock value, subjecting evolved vapors to dephlegmation to separate out acondensate comprising polymer products of reaction and directing the condensate into contact with Ythe selenium mass.

3. In the manufacture of gasoline of high antiknock value, the process that comprises maintaining a body of selenium in each of a plurality of reaction chambers, maintaining hydrocarbon oil in each of said reaction chambers, maintaining a temperature therein within the range of 400-600 C. under sumcient pressure that at least 4a. portion of the hydrocarbon constituents comprising polymer products of reaction is in liquid form, collecting said liquid polymers in the several reaction chambers in contact with the respective bodies of selenium and vapors evolved in one reaction chamber to a successive reaction chamber, to thereby effect con- Y version into gasoline constituents of high antikriock value.

4. In the manufacture of gasoline of high antiknock value, the process that comprises maintaining a.body of selenium in each'of a plurality of reaction chambers, maintaining hydrocarbon oil in eachof said reaction chambers, maintaining a temperature therein within the range of 400-600 C. under suiiicient pressure that at least a portion of the hydrocarbon constituents comprising polymer products of reaction is in liquid form, collecting liquid polymers in the several reaction chambers in contact with the respective bodies of selenium, introducing hydrocarbon oil into one of said reaction chambers and vapors evolved therein toa successive reaction chamber, to thereby effect conversion 'into gasoline constituents or high anti-knock value.`

5. The method of increasing the anti-knock quality of'motor fuels that comprises maintainingabodyofseleniumineaichofaplurslityy to effect vaporization of said oil, introducing the resulting vapors into the body of selenium in one of said reaction chambers, passing vapors 'evolved Vtherein to a successive reaction chamber into CHARLBCJIDWNI.

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