US1709874A - Distillation of oils - Google Patents

Description

I 192% A. a. FETERKIN. JR., ET AL. 9,8

DISTILLATION OF OILS Filed. June 4, 1925 FIST/A0476 BY M Mam? a ATTORNEY Patented aw. as, 1029..

i ears ALBERT G. PETERKIN, JR., F BRYN MA'WR, AND WILLIAM F. STROUD, JR., 0]?

CYNWYD, AND RICHARD B. CHILLAS, JR., 0F PHILADELPHIA, PENNSYLVANIA, AS- SIGNORS vTO THE ATLANTIC REFINING COMPANY, OF IHILADELPHIA, PENNSYL- VANIA, A CORPORATION OF PENNSYLVANIA.

DISTILLATION OF OILS.

Application filed June 4,

Our invention relates to the distillation of oils and moreparticularly to a process of distilling mineral oils without substantial cracking. v i

In accordance with our invention, crude petroleum, petroleum distillate or residuum is rapidly heated to a temperature in excess of its usual or normal cracking temperature to vaporize a substantial portion of the oil, 1 the vapors being kept in contact with the liquid oil until the maximum temperature is reached, and the vapors are then separated from the liquid, and the liquid oil is imme diately cooled to a temperat-ure'below the l cracking temperature, or to a temperature which .with, attendant conditions will pres,

. vent cracking. I

More partlcularly in accordance with our invention the oil is heated while passing at, high velocity through a series of tubes en-. closed in a suitable heating chamber, as in the wellknown pipe still, and the hot mixture of oil and vapor so produced is discharged into a chamber or vapor box from which the unvaporized oil or bottoms are drawn off and the vapors pass to a condenser or series of condensers, and if desired there may be utilized in conjunction suitable fractionating equipment. The high 4 velocity through the heater passageserves to keep the oil in the heating zone'for a minimum period of time, to produce turbulent flow, and to increase the rate of heat transfer to the Oil;

, Further in accordance with our-invention the aforesaid cooling is preferablyeflected, in part, by a cooling medium such as steam or: equivalent, preferably superheated, brought into, direct contact with the oil and vapor mixture, to vaporize an additional portion of the oil with consequent coollng of the residual oil due to abstraction therefrom of the necessary latent heat of vaporization. If desired, this cooling may be effected, in part, by a cooling medium passed through suitable heat-transfer structure out of contact with the mixture.

Further to prevent cracking of the residual liquid oil, it is passed through a cooler and to storage as soon as-possible. The time interval before cooling is shortened by making the vapor box of the smallest size necessary to handle the volume of vapors, thus uneconomical.

1925. Serial No. 34,750.

minimizing the time of passage of the oil therethrough.

Further in accordance with our invention,

by utilization of a process of the character aforesaid, there may be produced asphalt having desirable characteristics'from crude oils which heretofore have been considered unsluitable for the production of this materla In'the commonly used methods of distillmg petroleum oils, the oil is raised to a temperature of about 600 to 67 5 F. Such deslred fractions as fail to distill over at this temperature are carried over by use of steam which is forced through or otherwise brought into contact with the 'oil. The temperature used is limited by the fact that petroleum OllS above this temperature tend to decompose or crack with the formation of lower boiling point hydrocarbons. low temperature makes necessary the use of large amounts of steam, the proportion of .which increases with the boiling point and viscosity of the distillate fraction so as ul-- The timately .to render the distillation of oils above certain boiling points. or viscosities Qn account of this facthigh bOlllIlg 0118 of hlgh viscosity such as cylinder. oils are not distilled but leave the distillation process as still bottoms, from which must be separated by chemical or other means the asphaltic or other substantially non-volatile substances. Some of the disadvantages of the process may be overcome by conducting the distillation under subatmospheric pressures, whereby the boiling points of the oils are depressed. Even with this improvement, however, the distillation is still slow and cumbersome.

Our method is contrasted w ith the com monly used methods referred to, in that the oil is heated with extreme rapidity in a continuous stream while maintained in" con tact with the evolved vapors. It is further contrasted with common methods of operating pipe stills at such comparatively low temperatures as 600 to 700 F in that the oil in our process is heated to a temperature of the order of 750 F. which is considerably in excess of the normal cracking temperature. It is further contrasted with the process of cracking in a tube or pipe still in that the oil is maintained at the high temperature for a very short period of time and, after. separation of vapors, is immediately cooled before appreciable cracking can take place. Cracking of the vapors does 5 not occur as theydo not attain a sufficiently elevated temperature and cracking of the residual liquid oil doesnot occur since the period of time during which it is maintained above the cracking temperature is too short io to allow decomposition. The pressure upon the oil within the heating zone of'the tubular heater is preferably such only as is required to force the oil at the desired velocity through the tube structure, and may be, at

T disposed in the tube chamber A, whose' lower end communicates with a stack or flue a and into whose upper end are discharged from thecombustion chamber B the hot gases and products of combustion resulting from the burning of any suitable fuel, as, for example, oil or gas delivered to the'burner b. The oil to be treated is delivered from storage through the pipe 0 to the pump P, which-delivers it at suitable pressure to the inlet of the tube system T,

through which it rises, counter-current to.

-the descending hot gases," and is discharged through the pipe 03 into the chamber C, which, in the example illustrated, is a fractionating column. or tower, whose lower portion is in effect a vapor box, and which is provided with the vertically spaced fractionvat-ing members D of. any suitable type, such, for example, as bubble plates, perforated plates, or equivalent. The oil discharge d into thechamber C is preferably disposed at a point one or more plates above the bottom. The oil charged through the pipe 0 may be cold or it may be preheated, as by absorption of heat in"any one or more of the oil or vapor cooling structures hereinafter described, and is raised in temperature within the tube or pipe system T toa temperature in excess of cracking temperature, as, for example, of the order of 700 or 800 F. or higher, and passes through the tube structure at a velocity sufficiently high to shorten thev period of traverse of the heating zone to anextent sufficient to inhibit substantial cracking. Vapors are liberated in the oil within the tube structure, and these, assisted by the'velocity of the oil as delivered by the pump P, serve to effect turbuthe entrance to the tube structure, of the orlence of the oil, thereby enhancing the rate of heat transfer to the oil. The pressure of the oil as delivered by the I least such as to maintain the esired velocity of the oil through the tube system, the magnitude of the pressure at the entrance into ump P is at below the pipe, h, which delivers .the bottoms through a cooler F to the storage tank S. Connected with the upper end of the column C isthe )ipe i conducting vapors to the condenser cooledby any suitable medium, as, for example, water, introduced at y and discharged at The condensate, comprising oil and water, is delivered through the pipe m, controlledby valve n, to the water separator .I, inwhich the oil and Water separate, the Water passing off through thetrapped pipe. 0. The oil passes off through thepipe p to the flow box J in which the oil is divided in any desired proportions into two streams, one of which passes off through the pipe to the storage tank S and the other 0 which passes through the trapped pipe 7* into the upper end of the column C as a reflux stream which flows downwardly through the column countercurrent to the rising vapors.

In case the use of steam is not desired the water separator I may be cut out by closing valve n and the condensate from the condenser G passed direct-1y from the pipem through the valve 8 to the pipe p into the box J.

From suitable different altitudes within the column C may be withdrawn various desired fractions or cuts in liquid form through, forexample, the several pipes t, u, o, w, delivering through associated coolers K K K K, respectively, to the storage tanks S S S and S respectively.

The oil-vapor mixture entering the tower C at a? comes into contact with the steam delivered through the pipe (2, and is thereby immediately cooled to a temperature below the cracking temperature, or in any event, to a temperature which with the'attendant conditions within the tower prevents cracking. The steam inthe presence of the hot liquid oil causes part of the liquid oil to vaporize, and the vaporization so induced effects the cooling aforesaid by abstracting from the liquid oil the necessary latent heat of vaporization.

The unvaporized oil flows downwardly in the tower C, while in intimate contact with moaeaa the upwardly flowing steam, accumulating at the'lower end thereof as bottoms, with resultant vaporization of lower boiling point upwardly through the tower, being brought in the course of its flow into intimate 'contact with the downflow of liquid through the tower and effecting the necessary interchange for fractionation. 1 The liquid is 1 drawn off as various fractions through pipes 25, u, o and w, the heavier fractions at the lower altitudes and the lighter fractions at the higher levels. The lightest vapors pass through the pipe. 2'. to the condenser G,'the condensate eventually reaching the flow box J, which divides the condensate stream, part passing through the pipe to the storage tank S as aforesaid, and a suitable portion of the condensate being refluxed through the pipe r to the tower.

By means of our invention we are able, for example, to distill a mixed base midcontinent crude of an A. P. I. gravity of about 350 by raisinr it in the pipe still to a temperature of about 800 F. The oil may be passed through at such a rate that its time of subjection to the heat of the furnace is about 2 to 10 minutes. The oil-vapor mixture on entering the tower may be brought into contact iWlllh steam in a proportion of about 0.3 lb. per gallon of oil-charged. Under these conditions the bottoms, to the extent of about 10% of the crude charged, drawn 0d at the base of the tower, represent a satisfactory asphalt, which product is not obtained by the other well known methods of distilling such a crude. The character of the bottoms as well as of the distillate shows that no appreciable cracking has taken place in the distillation.

The production of satisfactory asphalt is a distinctive feature of our invention. In the ordinary methods of producing asphalt,

whereby.the crude oil is commonly reduced inv a shell still to the desired physical characteristics, the crude voil must be of such character as to contain a considerable proportion of asphaltic bodies in order to give a satisfactory product. Such crude oils are commonly described as asphalt base crudes and include in this broad classification crude oils such as the Mexican, Gulf Coast and the California crude oils; tinguished from those commonly known as mixed base crudes, of which the crude oils of the Mid-Continent area are typical, by showing a higher content of asphaltic bodies as indicated by the so called carbonresidue test which is described in detail in Bureau of Mines Bulletin #323-A, page #7 9, and referred to in the appended claims They are dis as Bureau of Mines carbon residue test. Calculated back to the crude oil itself, typical carbon residue tests on crude oils of these I two characters from well known fields-are as follows:

Mixed base omdes.

. I Per cent. Powell 2.2 Haynesville 22 Rainbow Bend 1.5 Mexia 2.0 Wortham 1.6

Asphalt base armies.

Per cent.

Smackover 3.4 Panuco 10.0 Venezuela 4.8 California (Long Beach Field) 6/1 The above figures indicate a carbonresidue value of about 2.5% as a fair boundary between the'mixed base and the asphalt base crudes. It has been general. experience, as above stated, that the mixed base crudes under normal methods of operation do not produce satisfactory asphalts. By our invention, however, we are able to produce" even from this type of crude oil an asphalt which is equal in every respect to that produced from the high grade asphalt crudes,- such as Panuco, and is even somewhat superior in that it shows a higher flash test. In accordance with our invention there becomes available a novel residual asphalt having a penetration (Dow) above 140 and a flash test (open cup) above 550 F. For any given penetration the corresponding. flash test of our product is higher than in the case of asphalts produced by the methods heretofore commonly practiced.

For example, a satisfactory asphalt pro-, duced by our process from a 35.0.A. P. I.

Gravity Mid-Continent crude oil shows a test as follows Per cent based on crude 9.34 Specific gravity 1.0225 Flash F. (open cup) 595 Fire F. (open cup) 695. Penetration 77 F. (Dow)--- 153 Melting point (B. &-B.) F. 112 Ductility (Dow) Sol. in CS, 99.65% Fixed carbon 11.96% Ash 0.09%

Engler viscosity at 300 F 11.5 units.

may be obtained a cut taken off from near the bottom of the tower, representing a distillate, too heavy for satisfactory pressing for removal of paraffin wax. Such a distillate iscommonly redistilled with little or no steam giving'a suitable paraffin distillate fractionand bottoms which are suitable only for fueL- I This cut may be redistilled by our process with much better results in that clean, uncracked 'bottoms result which are suitable in every way for high grade cylinder stocks. The test below is characteristic'of such bottoms by this process.

Gravity 21 1 A. P I Viscosity 210 F. (Saybolt Universal), 150' Flash i 540 F.

Eire 635 F.

In the commonly used method the paraffine distillate is the only lubricating oil fraction and its viscosity is much lower than that. of the lubricating 01]. produced by our method.

In connection with the rerunning, by our process, of a heav overhead such as the above, containing or example, a considerable percentage of oils with a Saybolt Universal viscosity of 100 seconds or above at' 210 F.,we have found it advantageous to add an amount of a'naphtha fraction, boiling largely below 500 F. at atmospheric pressure, in an amount of the order of 60% of the charge.

The addition of the naphtha makes use of the factthat the presence of the light boiling constituents has the effect of lowering .the boiling point of the high boiling oils.

- By its use distillation to a definite percent- 'er turbulence and shorteningthe time during which the oil must be maintained at "a high temperature. These three factors combine to minimize cracking.

The cylinderstock obtained in this manner is superior to the cylinder stock obtained in the usual steam distillation, in that having been once. distilled it is relatively free from asphaltic bodies whereas in 'steam'distillatibn the cylinder oil is a residue from the first distillation of the crude oil. As. a

result a smjallerquantity of acid is required to treat our product than is required for a eyllnd'erstock obtained in the usual manner.

Also we are able to obtain these high viscosity distillates from coking crudes which ordinaril do not yield a cylinder stock due to the relatively large asphaltic content.

Our method of the character herein described may be practiced also in the treatment of paraffiue base, naphthenic base and asphaltic base crude oils, particularly because of the higher rate of distillation possible. In the treatment of asphaltic base crude oil, there will again be produced asphaltic bottoms having desirable characteristics; and in treating parafline base oil there will be produced cylinder stock bottoms.

What we claim is:

1. The process of distilling petroleum or petroleum products without substantial cracking, which comprises rapidly heating the oil to a temperature in excess of 7 50 degrees F. by passing it at high velocity through a zone in which heat is transferred thereto, maintaining thevapor in contact' with the liquid oil while in the heating zone, immediately thereafter separating the vapor from the unvaporized oil, reducing the temperature of the unvaporized oil while out of contact with the separated vapor by a cooling medium to prevent cracking, and fraction ating the, separated vapor by immediately passing it counterchrrent to a stream of reflex oil. 1 v t 2. The process of distilling petroleum or petroleum products without substantial cracking, which comprises rapidly heating the oil to a temperature in excess of 750 degrees F. without substantial cracking by passing it at high velocity through a zone in which heat is transferred thereto, maintaining the vapor in contact with the liquid oil while in the heating zone, immediately thereafter separating the vapor from the unvaporized oil, cooling the unvaporized -oil to 'prevegnt cracking by bringing it into .contact with steam in a. zone substantially devoid of the separated vapor, immediately fractionating the vapor by passing it coun- I tercurrent to a stream of reflux liquid oil, and drawing off a portion of said reflux-oil from contact with the vapor at an intermediate point in its course of travel.

3. The process of distilling petroleum or petroleum products without'substantial cracking, which comprises rapidly heating,

the oil to-'a temperature in excess of 750 degrees F. by passing it at high velocity through a zone in which heat is transferred thereto, maintaining the vapor in contact with the liquid oil while in the heatingzone,

immediately thereafter separating the vapor from the unvaporized oil, reducing the temperature of the unvaporized oil while out of contact with the separated vapor by a cooling medium to prevent cracking, immediately fractionating the vapor by passing it countercurrent to a stream of reflux oil,

oil into contact with steam in a zone substantially devoid of the separated vapors,

to efiect reduction of temperature to prevent A substantial cracking and to produce additional separation of non-asphaltic bodies to leave a residuum of asphalt.

5. The process of producing asphalt fromcrude petroleum containing asphaltic compounds in such quantity that the carbon residue is less than2.5 per cent of the crude oil by Bureau of Mines carbon residue test, which comprises rapidly heating the oil to a temperature in excess of its normal cracking temperature, immediately separating the Vapors from the liquid oil, and then before substantial cracking occurs cooling the asphaltic residuum by a cooling medium to prevent substantial cracking.

6. The process of producing asphalt from crude petroleum containing asphaltic compounds in such quantity that the carbon residue is less than 2.5 per cent of the crude oil by Bureau of Mines carbon residue test, which comprises rapidly heating the oil to a temperature in excess of its normal cracking' temperature, immediately separating the vapors from the liquid oil, and immediately cooling the liquid oil by bringing it into contact with steam thereby effecting further vaporization of non-asphaltic bodies and eifecting an asphaltic residuum.

7. The method of distilling hydrocarbon oils which comprises "rapidly heating the oil to a temperature above its normal cracking temperature, immediately thereafter separating from that portion of the oil which remains liquid the vapors which form as a result of the heating aforesaid, then before substantial cracking occurs passing the liquid oil into a zone substantially devoid of the separated vapors and bringing such oil into contact with steam to effect further vaporization and to effect cooling to prevent substantial cracking.

8. The method of distilling hydrocarbon oils which comprises rapidly applying heat to a continuous stream of oil to raise its temperature above that. at which it will normally crack, immediately thereafter continuously separating from that portion of the oil which remains liquid the vapors which form as a result of the application of heat aforesaid, then before substantial cracklng occurs continuously passing the liquid oil into a zone substantially devoid of the separated vapors and bringing such oil into contact with steam by passing it countercurrent thereto to effect further vaporization and to cool the liquid oil to prevent substantial cracking] I 9. The method of distilling hydrocarbon oils which comprises rapidly heating the oil to a temperature above its normal cracking temperature, maintaining the vapors which form as a result of the heating in contact with the liquid oil during application of heat thereto, immediately thereafter separating the vapors from the liquid oil, then before substantial cracking occurs passing the liquid oil into a zone substantially devoid of the separated vapors and bringing such oil into contactwith steam to elfect further yaporization and toeffec't cooling to prevent substantial cracking.

' ALBERT e. PETERKIN, JR. WILLIAM F. STROUD, an. RICHARD B. CHILLAS, JR.

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