US1744261A - Process and apparatus for fractional distillation - Google Patents

Description

M. B. COOKE Jam, 21,. 1930.

PROCESS AND APPARATUS FOR FRACTIONAL DISTILLATIOH Filed Aug. 27. 1926 INVENTOR. Maunbc B. C k

Patented Jan. 21, 1930 I UNITED. STATES PATENT OFFICE MAURICE B. GOOKE, OI! PLAINFIELID, NEW JERSEY, ASSIGNOR TO THE ATLANTIC REFINING COMPANY, OF PHILADELPHIA, 'PENNSYLVANIA, A CORPORATION OF PENNSYLVANIA 4 PROCESS AND APPARATUS FOR FRACTIONAL DISTILLATION Application filed August 27, 1926. Serial No. 131,914.

My. invention resides in a method of and apparatus for fractionating vapors, mvolving their passage in contact with reflux l1quid, with withdrawal of liquid from the fractionating'system and return of at least a portion thereof, after cooling, to the fractionat-,

ing system.

More particularly myinvention relates to improvements in a continuous process for making lubricating oil distillate, which is of a higher quality than that made by other processes, particularly in that the'boilingrange of the distillate is liniited to predetermined temperatures whereby a more satisfactory lubricating distillate may be obtained from crudes of a different character, namely, asphaltic or parafiine base products.

The invention has further to do with a process for making pressable lubricating oil distillate, and comprises a method wherein crude oil or other lubricating oil bearing liquids are withdrawn from one or more trays of a conventional bubble tower fractionating device continuously in the liquid phase.

The use of other forms of fractionating towers common in niodern refineries are unsuitable for-preparing a pressable lubricat ing oil distillate carrying paraffin wax, for the reason that there is insuflicient fractionation or separation of deleterious substances existing in the crude oil or other lubricating oil bearing liquids. In other distillation sysremoved from the respective stages of the fractionating device and condensed. In the present invention the lubricating oil distillate is removed from the fractionating tower in the liquid phase and comparatively free from heavy coloring material as well as colloidal carbon and as halt. I

A further object o the invention is to produce in one distilling operation a lubricating oil distillate having a minimum boiling point range, a distillate which is comparativel free from coloring material, asphalt colloida carboil and other deleterious substances.

In one distilling operation a lubricating which is mounted a charge end of the still is connected by means of a line 3 to a bubble tower 4. 5, 6 and 7 conventional pressing operation. As a matter of fact lubricating oil'distillate'as it is produced at the present time has such physical and chemical characteristics that the wax cannot be removed by ordinary chilling, and

separation by present methods. As ordinarily made the lubricating oil distillate is removed from the fractionating device in the vaporphase and vacuum, steam or fixed gas is employed in order that the viscosity of the lubricating stock will not be destroyed by excess heat necessary to vaporize the oil and wax. Consequently lubricating oil distillate so made is of such physical structure that the wax whenchilled with the -oil is not in condition that all of the lubricating oil out can be freed of wax by pressing methods. There fore, part of the lubricatlng oil distillate is placed usually in a cylindrical still and subjected to heat without the use of steam, or with a very little steam, and'in this way the wax and oil are cracked and the physical nature of the wax particleschanged to the extent that when the oil is chilled the wax will be in such physical condition that it can be removed by pressing.

The figure is a diagrammatic side elevational view of an apparatus in which the proce'ss may be practiced with parts in section and parts broken away.

In the drawings at 1 is shown a furnace in pipestill 2. The disare heat exchangers; 8 is a cooler and 9' a pump.

Referring now to the methodxof operation. Crude oil is supplied through the line 10 from the lubricating oil distillates withdrawn from any convenient source of supply, l and is Y exchanger 6 the charge passes through a final heat exchanger 7 through which the products withdrawn from the bottom of the bubble tower through the line 14 are circulated.

-From the heat exchanger 7 the oil passes through a line 15 to the pipestill 2 where it is raised to a temperature which will produce the desired degree of evaporation. The oil from the pipestill is directed to the line 3 and is allowed to expand in the evaporation section, or lower portion of the bubble tower 4. Here the light volatile portions-of the crude evaporate and percolate through successive pools of oil supported by the bubble trays 16. The percolation of the vapors through these pools of oil is produced by capped risers 17.

The successive pools of oil are of decreasing temperature toward the top of the tower so that the vaporswhich pass ofi through the line 18 are only the lighter cuts which after passing through the heat exchanger are directed to a final condenser not shown through the pipe 19. Any condensate separated out in the heat exchanger is returned through the reflux line 20 to the top of the bubble tower. Between the bubble trays are positioned lay- 'ers of broken up material, or screens 21,

which serve as mist extractors, and prevent the passage of entrained material from one pool to the next pool above. The heavier portions of the oil vapors are liquefied by coming in contact with the reflux liquid carried on the trays. The unvaporized p rt ons of crude oil are allowed to collect in the bottom of the tower 4, and are continuously withdrawn in regulated quantities, and used as fuel oil or for any desired purpose. The lubricating oil distillate or wax distillate is collected on the trays in the upper part of the tower and may be withdrawn continuously through the pipes 12 and 13. The distillate withdrawn through the pipe 13 will be heavier "in specific gravity than that withdrawn from the pipe 12. and so in each of the trays above distillate will be of decreasing gravity.

In order to produce a lubricating oil distillate having a very narrow range of boiling points it has been found that by returning oil withdrawn from the tower through the line 13, and paming the same through the exchanger 6, and cooler 8, and returning this distillate bycharging it through a pump 9 and line 22, back to the tower just above the trays from which the lubricating oil distillate is withdrawn, a much more desirable distillate is produced. The cooler 8 may be either water or air cooled. Cuts or fractions withdrawn from the lines 12 and 13 will be in the liquid phase and will have had the heavy impurity, such as asphaltum, colloidal carbon and light impurities such as gas, oil,

therefrom by fractional condensation and vaporization, substantially as descri ed.

It is also clear that cuts or fractions with drawn from one or more bubble trays will have a smaller number of degrees boiling range '(initial' boiling point to end boiling point), and will consequently have a minimum boiling range for a given viscosity. This is an important advanta e in the present invention, for it has been ound that the quality of a lubricating oil depends on two characteristics FirstIf oils having the same viscosity are tested for lubricating ability, both regarding the stability of the oil and the revolutions of moving parts to be lubricated per unit of the oil used, it will be found that the oil with the least number of degrees between the initial boiling point and the end boiling point will be the more valuable oil.

Second-It has been found that asphaltic and parafline base oils are equal in lubrlcating value, if the viscosity and boiling range are the same, and if the asphaltic base oils can be properly treated to remove asphaltic particles so that their viscosity and boiling range is the'same as the parafline base lubricating oil, and the present'method described can accomplish this result by eflicient fractionation and the removal of the asphaltic particles.

The advantages of the process lie particularly in the fractionation and withdrawal in the liquid phase of a lubricating oil distillate from a bubble tower which is capable of limiting the fraction withdrawn within a very narrow boiling point range. Furthermore this process covers any lubricating oil distillate having a Saybolt viscosity at 100 F. of more than 50, and which may be fractionated in liquid phase from a tower and from which the contained wax may be extracted or removed by chilling and filtration.

It is to be understood that in accordance with this invention the liquid withdrawn from the fractionating column and cooled, may be returned, either directly'or indirectly, to the zone or plate from which it was withdrawn.

A distinct advantage of my process is that some of the heat which, by customary methods of fractionation, dependent-upon utilization of reflux liquid, is carried by the continuousumn the heat so removed, are no longer necessary and the quantity of reflux liquid introduced at the top of the column'may be accordingly reduced an appropriate amount. Such reduction of volume of vapors within the col- -kerosene and naphtha fractions, separated umn will permit the introduction of more with resultant control of the rate of abstrac-" tion of heat from the column. 1

I claim as my invention:

1. In the art of fractional distillation of petroleum, the process which comprises passing vapors upwardly through a lurality of fractionating. zones at difi'erent evels, passing reflux liquid downwardly in a continuous stream through said zones countercurrent to,

and in contact with said vapors, withdrawin liquid from one of said zones and cooling it;

and returning liquid so cooled to a zone at least as high as the zone from which it was withdrawn.

2. In the art of fractional distillation of petroleum, the process which comprises passing vapors through a pluralit of fractionating zones, passing reflux liquid in a continuous stream through said zones countercurrent to and in contact with said vapors, withdrawing liquid from one of said zones and cooling it, and returning liquid so cooled to the zone from which it was withdrawn.

3. In the art of fractional distillation of petroleum, the process which comprisespassmg vapors of t e oilthrough a lurahty of fractionating zones, passing re ux oil in, a continuous stream through' said zones countercurrent to and in contact with the vapors, circulating liquid oil from and back to one of said zones, and cooling the liquid oil while in circulation external to said zone.

4. In the art of fractional distillation of petroleum the process which comprises passing vapors of the oil upwardly through a plurality of fractionating zones at difierent' levels, passing reflux oil downwardly in a continuous stream through said zones countercurrent to and in contact with the vapors, circulatingliquid oil from one of said zones back to a zone at least as high as the zone from which it is withdrawn, and cooling theliquid oil while in circulation external to said zones.

etroleum, the process which comprises passmg vapors of the oil upwardly through a plurality of fractionating zones at diiferent levels, passing reflux oil downwardly m a continuous stream through said zones countercurrent to and in contact with the vapors, I

5. In the art of fractional distillation 0i said zones, and drawin ofi a portion of the oil withdrawn from said one of said zones.

6. A fractionating system for petroleum comprising a fractionating column, means therein for defining aplurality of fractionating chambers at difi'erent levels, means within said column for conducting reflux liquid in a continuous stream downwardly therethrough, means for passin vapors of the liquid to be fractionate upwardly through the column countercurrent to and in contact with the reflux liquid, cooling means external to said column, and connections for withdrawing liquid from one of said chambers to said cooling means and for returnin it to a chamber at least as high as the chem er from which it is withdrawn.

7. A fractionating system for petroleum comprising a fract1onating column, means therein for defininga plurality of fractionating chambers at difi'erent levels, means within said column for conducting reflux liquid in a continuous stream downwardly therethrough, means for passing vapors of the liquid to be fractionated upwardly through the column countercurrent to and in contact with the reflux liquid, cooling means external to said column, connections,

for withdrawing liquid from one of said chambers to sai cooling means and for returning it to a chamber at least as high as 'the chamber from which it is withdrawn, and means for drawing oflf a portion of the liquid withdrawn from said one of said chamers.

8 A fractionating system for petroleum comprising means for vaporizing the liquid to be fractionated, a feed line delivering to said means, a fractionating column receiving vapors from said means, means within sa1d column for conductin reflux liquid in a continuous-stream theret rough, a plurality of fractionating chambers in said column at diiferent levels therein, means for conducting vapors upwardly from one of said chambers to another, cooling means'external to said column, connections for delivering liquid from said feed line as cooling medium to said cooling means and for recirculating liquid from one of said chambers to said cooling means and back to .a chamber gt least as high as said one of said chamers.

9. A fractionating system for petroleum comprising a fractionating column, a plurality of fractionating chambers therein at different levels, means for delivering vapors into and upwardly through said column, means for passing reflux liquid in a continuous stream downwardly through said column countercurrent to and in contact with said vapors in the several chambers ofsaid column, connections from a lurality of said chambers for withdrawing hquid therefrom,

' tercurrent to and in contact with said vapors,

withdrawing liquid from a zone intermediate the uppermost and lowermost of said zones, cooling the liquid so withdrawn, and returning cooled liquid to the zone from'which it was withdrawn.

11. A continuous process for producing a lubricating oil distillate having a narrow boiling point range, and from which wax is removable, which comprises passing the vapors through a series of fractionating zones one above another, passing reflux liquid in a continuous stream from zone to zone countcrcurrent to and in contact with said vapors, withdrawing liquid from a zone intermediate the uppermost and lowermost of said zones, cooling the liquid so withdrawn, returning cooled liquid to a zone above that from which it was withdrawn, and again bringing the liquid so returned into contact with the vapors passing through said zones.

MAURICE B. COOKE.

DISOLAEMER 1,144,26L-Maw-iae B. Cooke, Plainfield, N. J. PROCESS AND ArrARA'rUs FOR FRAC- TIONAL DISTILLATION. Patent dated January 21, 1930, Disclaimer filed August 25, 1939, by the assignee, The Atlantic Refining Oompany.

Hereby disclaim any meaning of the terms reflux liquid and/or reflux oil, as

used in the specification and claims of the aforesaid patent, other than the commonlyaccepted meaning of such terms in the fractional distillation art, namely, an oil or liquid characterised in that when it starts in its course through the plurality of fractionating zones or chambers it corresponds substantially in composition to an oil or liquid formed by condensation or partial condensation of vapors which have passed through the ,fractionating system, and therefore, it necessarily contains only constituents of the character of those in the vapors; and further, in that in its passage through he plurality of fractionating zones or chambers, its composition changes due to interchange of its light constituents for heavy constituents of the vapors passing countercurrent to and in contact therewith, so that in any particular zone or chamber the reflux liquid or reflux oil contains no substantial amount of components having boiling points higher than the boiling points of the highest boiling components of the vapors entering the particular zone or chamber.

[Officz'al Gazette September 9. 1.9301

DISCLAIMER 1,744,261.Maar'ice B. Cooke, Plainfield, N. J. PRocEss AND Arrann'rus FOR 'FRACTIONAL DISTILLATION. Patent dated January 2 1, 1930. D sclaimer filed December 2, 1930, by the assignee, The Atlantic Refining Company.

Enters this its further disclaimer, to wit: Petitioner disclaims from the scope of all the claims of said Letters BatentNo. 1 ,744,261 all processes and systems of fractionation in which there is passed countercurrent to' and in contact with the vapors, or in WhlCll the hquid oil cooled' 1ncludes, an extraneous oil or an oil other than reflux oil as defined in the aforesaid former disclaimer.

[Qfliv'idl Gazette December 16, 1930.]

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