US1879948A - Process of distilling oil - Google Patents

Description

Sept. 27, 1932. A. E. PEW, JR

PROCESS OF DISTILLING OIL Filed April 4. 1929 5 Sheets-Sheet l fram/f ys.

Sept. 27, 1932. A. E. PEW, JR 1,879,948

PRocEss oF DISTILLING oIL Filed Apri14, 1929 i 5 Sheets-Sheet 2 sept. 2 7, 1932.

A. E. PEW, JR

PROCESS OF DISTILLING OIL Fild April 4, 192e 5 Sheets-Sheet 3 Patented Sept. 2?, i932 ras Ltdttt ARTHUR E. FEW, JR., F BBW EHAWR, PENNSYLVANIA, ASSGNOR T0 SUN @U4 COM- Pm, 01E' PHMEJLPHA, PENNSYLVANIA, A CORPORATION 01E NEW JERSEY rnoc'nss or Dreamtime oir.

Application led April 4, 1929. @crial No. @59,39%

ln a patent issued to me June 3, 1930, No. 1,761,153, I set forth certain conditlons which are either required or highly desirable in the manufacture, from crude oil, of lubricating distillates. These conditions may be enumerated as follows:

(l) Conining the oil against access of oxygen during the process of separating the lubricating stock from the crude oil as Wellv as during the process of distilling the lubri- 4 cating oils.

stock, to the lowest practicable temperatures so as to minimize decomposition, the effect known as cracking.

(4) The maintenance of the oil, while it is including subjected to the higher temperatures, under a very high vacuum, which should be, in the case of the` highest boiling fractions, the equivalent of an absolute pressure not higher than about ten millimeters mercury, and which may be much lower, thereby reducing the temperature required to evaporate such high boiling fractions.

(5) I The avoidance of a column of oil of any substantial height, thereby making the important factor of hydrostatic pressure negligible.

(6) The maintenance of the smallest practicable temperature diiference between the oil and the heating medium, especially in the distillation of the higher boiling fractions, so as to avoid local overheating.

(7) The application of heat, principally if not wholly, to the liquid oil and the avoidance of application of heat to the released vapors.

(8) rThe subjection of the oil to heat for the shortest practicable time; the time element being an important factor in cracking, f

which it is necessary to avoid or minimize.

(9) The subjection of oil to high temperature for the shortest practicable time.

(10) rlhe distribution of the lubricating stock, during heating, in the form of a comparatively broad, thin layer, or broad, shallow stream, which may be denominated film evaporation. Y

(l1) rllhe removal of such fixed gases as impart to the oil an odor which indicates the presence of these gases and injures the marketability of the oil;

lt may also' be added that other obvious desiderata, are low capital investment and low maintenance charges. v

The process set forth in my said application satisfies all the conditions above specified; but the construction of a plant of large capacity requires a considerable expenditure.

The object of the present invention is to simplify` the process, materially reduce the cost of the plant construction and measurably reduce the cost of operation, and reduce the size of that part of the plant wherein the oil is vaporized by extracting the heat of condensation of mercury vapor. While the latter purpose results in substantial saving in investment cost, I have found that it is also possible to reduce investment cost by dispensing, in whole or in part, with film evaporation provided the other requirements are satisfied; especially, the subjection of the oil Vto relatively low temperatures and pressures,

the avoidance of a deep column of oil and local overheating, and the application of heat to the oil for the shortest possible time, so as to enable the vaporization of desired fractions below their critical temperatures. torsincrease proceeds.

My new process fulfils the r:onditions above The importance of these facprogressively as the distillation decomposition explained, eie'cts a pronounced reduction in ing oil distillation plant.

' oil constituents 'ofthe crude oil.

, 1929. A tower of this Fig. 2 is a vertical sectional view of the tower inv which the lighter lubricating oils are fractionally condensed.

Fig. 3 is a plan view of the Aoil receiving panr of the tower of Fig. 2.

Fig. 4 is a vertical sectional view of one of the towers in whichone of the heavier lubricating oils are separated and uriied.

Crude oil, which may have een heated by means of heat exchangers and dehydrated', with removal also of sand and other foreign matter, as known in the art, or as disclosed in my said Patent No.- 1,761,153, is pumped through a coil or coils' in still 1, wherein it is heated by combustion products of burning fuel and by hot waste gases from still 15. The oil leaves still l at a temperature sufficient to allow the vaporization'and separation i'n tower 2 of predetermined lighter hydrocarbon fractions.` Preferably the oilleaves the still at a temperature of about 600 F., which is suiiicient to allow the vaporization, in tower 2, of the gasoline, kerosene and gas This temperature is merely illustrative. It will vary with the type of crude being run. The speciiic temperature approximates that which wouldbe preferable in runing a heavy Gulf Coastal crude.

Tower 2 may have any suitable internal construction. referably it may be a bubble tower of the type disclosed in the Pew and Thomas Patent No. 1,723,368, issued Aug. 6, type is shown in Fig. 2 herein.

In tower 2, gasoline escapesat the top through line 3 to condenser 4. Gasoline also escapes through line 5 to condenser 6, whence it is pumped back, through line 7, to the tow er in suilcient volume to extract a suiiicient amount of heat to cause the tower to properly function.

In tower 2,- kerosene is obtained through line 8, going to condenser 9; and gas oil is obtained through line 11, going to condenser 12. A certain proportion of kerosene and A gas oil may also escape and return through lines, 10 and 13 respectively. v

The residual product (which may be lubricating oil stock) is ,pumped from tower 2 through line 14` at a temperature of (say) 4550 F. and thence through a coil or coils in still 15, wherein the oil is heated to a a solution of any suita lagent, such as caustic soda, which intimatetemperature of (say) 650 F. and leaves through line 16 and enters thevaporizing se'ction o f a small tower 17. These temperatures are merely illustrative and approximate those which would be preferable with the type of crude above speciied and with an assumed temperature of about 600 F. for the oil leaving still V1. The reduced temperature of the oil leaving tower 2 is due to radiation loss llnd some conversion of sensible heat to latent eat. y Into tower 17 is pumped, through line 18,

le acid neutralizing ly mixes with the hot oil. The oil and soda mixture flows downward through the tower into a settling tank 21, while the water vapor generated by the high temperature leaves the tower through line 19 and goes to condenser 20. From tank 21, the oil, containing soda in solution,'lows through line 22 and, after passing through a pressure reducing valve v23, enters tower 24. ByV means version of sensible heat to latent heat, with consequent cooling of the incoming oil, the

desired oil fractions will be vaporized. A

Tower 24 may be of any suitable conventional design. It mav be a bubble tower, and if this type be adopted it is preferred to 4construct it substantially as shown in Fig. 2. Another feasible t'ype'of tower, for use at this stage of the process, is a packed tower similarV to that shown in Fig. 4 but modified to adapt it to the separation of fractions of different ranges.

Assuming that the type of tower shown in Fig. 2 is adopted, the following operations,

will 0001111- ,A large partvof the oil, after passing valve23, is converted into a vapor, due to the greatly reduced absolute pressure in tower 24. The, conversion of this part of the `oil is complete after admission to the tower. The discharge end of ipe 22 is directed tangentially against t e inner peripheral wall of a pan 25,. which may contain a screen 26 arranged concentrically within the'pan. Above the pan is a series of plates 27 each having openings from which project upward nozzles 28. over which are arranged caps 29. Depending from.- the plates are tu es 30,'which extend above the plates and vdetermine the liquid level thereon and allow Laramie liquid oil to How from one plate down to and over the plate next below it. Over the tier of plates is a partition 31 having a central opening from which extends upward a tube 32.

Above partition 31v is another series of bubble plates and above these another partition, and so on, thereby providing a series of reiiuxing and fractionating chambers from the lowest of which escapes the residual oil with some condensate, while from the others escape condensates` of progressively decreasing boiling ranges as. the top of the ,tower is approached. In each chamber the vapor bubbles up through pools of oil on the plates 27 and thence through the partition immediately above and the condensate descends from plate to plate through the tubes 30.

A proportion of the condensate that falls to the bottom of each chamber except the lowest escapes through line 33 to a deodorizer 34, which is similar in structure and operation to the deodorizer on subsequent towers and which is shown in detail in Fig. 4. In the deodorizer, which is under a very high vacuum, odor producing gases are removed. From the deodorizer the purified oil distillate Hows to cooler 35 and thence to tank 36, from which it is pumped to storage.

The remainder of the condensate that falls to the bottom of each chamber of tower 24 except the lowest escapes through reilux line 37 back into the chamber just below it.

As an example of the lubricating oilsthat may be separated in tower 24, the oil leaving the tower through the highest of the lines 33 may be a light lubricating oil of (say) 100 at 100 F. viscosity. Through the successively lower lines 33 respectively heavier oils outflow, say, for example, oils of 200, 300 and 500 at 100 F. viscosity.

Heat .removal from tower 24 may beiefected in any known'way, as by jacketing at they top with a cold water jacket, as shown at 38, or by heat transfer to the atmosphere. A high vacuum is maintained in the deodorizers 34, and also in tower 24, by means of a. thermal compressor, ejector, or vacuum pump 39. A

The residual oil from tower 24 is pumped through line 40 and through a pipe coil 41 in a heating chamber 7 0. rll`he heating medium in this chamber is, preferably, mercury vapor, but other heating media may be substituted, particularly substances such, possibly,

as diphenyl oxide, benzo phenone, sulfur, or perhaps a suitable metal alloy, as may be found to possess those characteristics of mercury vapor that make it especially advantageous in the distillation of the higher boiling lubricating oils. In chamber the mercurv vapor condenses and imparts its latent heat to the oil flowing through coil 41. The mercury vapor is generated in a mercury boiler 71 from which extends a mercury vapor pipe line 72 to chamber 70. Pipe 72 is equipped with a valve 73, by means of which the rate of How of the mercury vapor into chamber 70, and thereby the pressure and temperature of condensation within the same and the heat to which the oil is subjected may be accurately regulated. This temperature of condensation should be such that there will be a comparatively low temperature difference between the oil flowing through coil 41 and the surrounding mercury vapor as measured by the logarithmic mean temperature di'erence at the inlet and the outlet of the coil. i`

Extending from chamber 70 is a mercur condensate return; which comprises a clean out cup 74, a goose-neck- 75, pipe 76 and chamber 77 communicating with boiler 71. The connections shown are adapted not only to allow mercury condensate to return to boler 71, but also to provide balancing columns of liquidmercury (in goose-neck to take care of pressure dierences between boiler 71 and chamber 70. I

ln coil 41 the oil is heated to the desired temperature, say 625 F., and suiiicient latent heat is applied to vaporize the desired fraction within the coil; or, alternatively, the pressure within the coil may be so fixed as to prevent vaporization within the coil and permit the conversion of sensible heat to latent `heat in tower 42, as hereinafter more fully described. Assuming that the vaporization is effected within the coil, the oil thus heated and partly vaporized enters tower 42,

which may have the internal ,construction shown in F ig. 4. ln this tower the vapors are condensed. A small proportion of stink oil, Amainly incondensible gases, escapes through line 43 and condenser 44 into receiving tank 45, whence the stink oil may be pumped to storage. The main partof the condensed -product flows through line 46 into a. deodorizer 47, which is subjected to a high vacuum and in which the remainder of the odor-producing gases are removed, the purified oil flowing through aV- cooler 48 into a tank 49, from which it is pumped to storage.

escaping through line 46 flows through another coil 51 in another mercury vapor condensing chamber 80. Herein the oil is heated 1':

to a somewhat higher temperature than in coil 41, resulting in another partial vaporization, Yand flows into a tower 52, whereln the 'vaporized fraction is condensed; the operation being the same as in tower 42, but with This high vacuum may be estab the production of a higher boiling range oil distillate.

I have shown still another mercury vapor condensing chamber 89, coil 61 and tower 62, in series with the fractional distillation units 70, 41, 42 and 80, 51, 52,*above described, for the production of a still higher boiling range distillate. There may be a variable number of these units, dependent on .the iineness of the cuts desired, and dependent also on the proportion of the distillates which it is desired to produce by the use of mercury vapor as a heating medium as compared with the proportion of distillates which it is desired to obtain in tower 24. Other factors' also will govern `.the design of the plant. With the use of a considerable number of units, the temperature elevations in each unit will be reduced.. with the resultant advantage that the oil will be subjected to the action ofthe heating medium for very short periods of time.

The towers 42, 52, 62, etc., may have any suitable internal construction. Preferably i they are designed similarly to those disclosed in my said Patent No. 1,7 61,153. Adetailed` view of a'practicable form of tower is shown in Fig. 4. The pipe 90 beyond coil 41 discharges into a pan 91, similar to pan of ' Iigs 2 and 3. Above pan 91'is a grid 92, which supports a pile of chemical tiles, preferably Raschig rings 93.` Above the pile of tiles 93 is another grid 94, which supports another and higher pile of tiles 95. Below grid 94 is a partition 97 having a central opening surrounded by an upstanding tube forming a central vapor passage. Secured to the bottom of grid 94 is a deflector 96.

Any vapors carried into .the tower that are heavier `than the friction which it is desired to segregate kwill condense while going through tiles 93 and How down to the bottom of the tower, thence escaping, with the main body of unvaporized oil, to the next heating chamber of the series. Any particles of oil that are entrained with the vapors will also flow to the bottom of the tower. The uncondensed vapors pass up through the opening in 'l partition 97, and through grid 94 and tiles95,

wherein the vapors are cooled and most of them condensed. The incondensible gases escape through stink pipe 43. The condensate flows back through tiles 95 into a receptacle formed by the annular partition 97 and thence escapes through pipe 46 into deodorizer 47.

Deodorizer 47 contains low plates 98 over which the distillate is distributed in very shallow streams. The deodorizing chamber is provided with outlets 99 located between adjacent platesf The bottom of the deodorizing chamber connects with one of the vacuum pumps 50, as hereinbefore explained. Thev without substantial distillation, from the oill I on the plates 98, while the puried oil vflows,

through cooler 48, into tank 49.

- Any number of boilers may be used. In the 'I shown as connecting with oil heater 70 and boiler 81 with oil heater 89, while each boiler is connectible with oil heater through branch mercury vapor inlet pipes 720 and 820 respectively and mercury condensate return line 78, which latter may be connected with either line 76 or line 86 through one of the goose-necks 84. Mercury vapor lines 72 and 82 may be cross-connected by means of pip'e 700. By means of suitably positionedvalves,

either boiler may be connected, and the othery i' bers.' d

The described arrangement of boilers may be varied as desired. The use of two boilers is desirable, since it allows the generation of mercury vapor at pressures more nearly approximating the pressures desired in the oil heaters connected therewith and it also provides against a shut down-in case one boiler should be disabled. .One boiler, however, is all that is required, in view of the capacity tolndependently regulate the pressures in the several chambers by means of the throttle valve 73, 83 or 88 and the balanced mercury columns in the goose-necks 7 5.84 and 85.

While, as hereinbefore described, the par-4 tlal vaporization of the'oil flowing through coils 41, 51 and 6loccursin the coils themselves, it may be preferable to prevent vaporization within the coils, thereby preventing any direct transfer of heat to the vapors. This can be effected by means of pressure regulating valves 101, 102 and 103 on the pipes leading from the coils to the towers 42, 52 and 62. When this variation is adopted, it is necessary to heat the oil in each coil to a somewhat higher temperature than would be otherwise required to permit the conversion of sensible heat to latent heat in the succeeding tower. Such variation of the process is also of advantage in keeping the tubes clean, since the entire contents are a liquid-and therefore able to carry more suspended matter. With certain crudes,` however, the higher Y temperatures necessitated by the maintenance of the oil would tend to cause cracking or decomposition. This may be largely or wholly overcome, however, by using a multiplicity of unit-s. It is, of course, possible to apply pressure regulating valves only to the units just beyond tower 24. since the required temperature to which the oil must be raised therein is comparativelylow. In the absence of pressure control regulators, the oil in each coil will be under a vacuum but little lower than that in the tower, 42, 52. or 62, just beyond the coil.

disconnected, with all the oil heating cham It is desirable that provision be 'made to shut the boilers down if it becomes necessary to shut ofi' the flow of mercury to the oil heaters. Should the main valves 94 on lines 72 and 82 be closed, the safety valves 95 would open and the mercury would rise and condense in condenser 96, flowing back, through the seals97 into lines 76 and 86 and thence into the boiler.

I do not herein claim the herein described construction and arrangement of mercury vapor boilers and mercury flow pipes, the same forming the subject matter of a separate divisional application filed Aug. 6, 1921, S. N. 555,391.

What I claim and desire to protect by Letters Patent is:

l. The process of producing lubricating oil distillates of different boiling points which comprises distilling lower boiling oil fr actions by flowing acid-neutralized lubricating oil stock, containing such lower boiling fractions and also higher boiling fractions under a relatively high absolute pressure into a tower and therein subjecting the stock to a relatively low absolute pressure and thereby vaporizing such lower boiling oil fractions and separately condensing and outowing the vaporized oil fractions of different boiling points; and then distilling higher boiling oil fractions of said stock by iowing the residue 'from the specified distillation through one or more stills in which the oil is heated while flowing in a continuous' stream of restricted cross-section and is partially vaporized and by condensing and separately removing the vapors. 2. The process of producing lubricating oi distillates of different boiling points which comprises distilling lower boiling oil fr actions by iowing acid-neutralized lubricating oil stock containing such lower boiling fractions and also higher boiling fractions under a relatively high absolute pressure into a tower and therein subjecting the stock to a relatively low absolute pressure and thereby vaporizing such lower boiling oil fractions and separately vcondensing and outfiowing the vaporized oil fractions of different boiling points; and then distilling higher boiling oil fractions of said stock by flowing the residue from the specified distillation through one or more stills inA which the oil is heated while flowing in a continuous stream under an absolute pressure suliicient to prevent substantial vaporization and is then partially vaporized by subjection to a relatively low sub-atmospheric pressure and thereby efecting its partial vaporization and by condensing and separately removing the vapors.

The process of producing oil distillates of different boiling points which comprises distilling lower boilin oil fractions by flow'- ing acid-neutralized oi stock, containing such and also higher boillower `boiling fractions ing fractions under a super-atmospheric pressure into a tower under a sub-atmospheric pressure and therein, without substantial application of heat thereto, and by the specified reduction in absolute pressure, vaporizing such lower boiling oil fractions and fractionally condensing and separately outfiowing the vaporized low boiling oil fractions of different boiling points; and then distilling higher boiling fractions of said stock by flowing the residue from the specified distillation through one or more stills of which the oil is heated while flowing in a continuous stream of restricted cross-section and is partially vaporized and by condensing and separately removing the vapors.

4. The combination with a chemical treating apparatus, of areflux condensing tower providedv with a series of outlets for condensed vapors and a residual oil outlet, a connection from the chemical treating apparatus to the tower, a pressure reducing valve in said connection, and a number of stills in series with each other and with said tower; each of said stills comprising an oil flow pipe coil and in series therewith a reflux condensing tower having an outlet for conto the tower, a pressure reducing valve in said connection, and a number of stills in series with each other and with said tower; each of said stills comprising an oil flow pipe coil, a refiux condensing tower having an outlet for condensed vapor and a residual oil outlet, and a pressure reducing valve between the pipe coil and the corresponding tower; andmeansto heat the pipe coils.

6. The combination with a chemical treating apparatus, of a reflux condensing tower provided with a series of outlets for condensed vapors and a residual oil outlet, a deodorizer communicating with each outlet for condensed vapor, a connection from the chemical treating apparatus to the tower, a pressure reducing valve in said connection, and a number of high boiling lubricating oil stills in series with each other and with said tower; each of said stills comprising an oil flow pipe coil and in series therewith a reflux condensing tower having an outlet for condensed vapor and a residual oil outlet; a deodorizer communicating with each of the last named towers, and means to heatthe pipe coils.

In testimony of whichinvention, I have hereunto s'et my hand, at Marcus Hook, Pennsylvania,on this 2nd day of April, 1929.

. ARTHUR E. PEW, J R.

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