US1714811A - Process of distilling mineral oil - Google Patents

Description

May 28, 1929. A, E FEW, JR., ET AL 1,714,811

PROCESS OF DISTILLING MINERAL OIL Filed AMay 29, 1926 2 Sheets-Sheet l NSER CONDE To zz` PRESSURE vAPoRlzER coNrRos. /S I VALVE l s Y/ il g 1"/ v nl :f L l x' e e 7 :l

f e C g v Q PRESSURE F/GJ.

May 28, 1929. A, E PEW9 JR., ET AL 1,714,811

PROCESS OF DISTILLING MINERAL OIL Filed May 29, 1926 2 Sheets-Sheet 2 Patented May 28, 1929.

f :UNITED Y '1,714,8141 PATENT OFFICE.,

.At-T HUR E. PEW, J R., oFl-IBRYN MA'WR, AND HENRY THOMAS, OF RIDLEY PARK, PENN- 'YLVANIA, ASSIGNORS TO SUN OIII COMPANY, OF IHILADELPHLA, PEN N SYL- VANIA,'A CORPORATION OF lNEIN JERSEY.

PROCESS OF DISTILIING MINERAL OIL.

Application filed may 29,

' In applications filed by us March 5, 1925, Serial No. 13,040 and March 13, 1925, Serial No. 15,262, we have disclosed a practicaland commercially operative process and apparatus for fractionally distilling mineral oil by heat exchange between mercury vapor and the oil to be distilled, the oil being p'artly vaporized and the mercury vapor being condcused and returned to a body of liquid mercury which is continuously *generating 'mercury vapor. In this process a stream of oil fiows through a series of confined spaces, preferably in the form of a rapidly flowing solid stream of approximately uniform thickness and width and of very small depth relatively .to its width and of ,small width relativelyl to its length.` p. Thelmei'cury; vapor generated in the mercury boilerl is 'lat such pressure that-it Iwill have a temperature of condensation above that of the, hottest part of the stream of oil, which isthe oil flowing through the last space of ther series. The mercury `vapor flows into confined paths, or chambers, arranged in multiple withrespect to each other and in heat exchange relation with the respective confined spaces, or oil vaporizing conduits, through whichthe oil is flowing in series. The amountof mercury vapor admitted to each chamber is sufficient to effect, by heat exchange and condensation ot' the lncrcurvvalimr, partial vaporization of the oil flowing through each of said -confined spaces. The proportion of oil vaporizcd in each vaporizer is predetermined by independently regulating the rate of flow of the mercury vapor into the mercury chamber of each vaporiziug unit. This'may be done by means of valves located at orvnear the admission openings into the several mercury chambers. y c A In such process, however, the pressure of mercury vapor and the temperature at which it condenscs may be thesame in the mercury vapor chambers of all the vaporizcr units. This does not militate against the successful operation of the process, particularly because. compared with other heating media, the difference in temperature between the mercury vapor and the hottest part of the oil stream need be relatively low, andhencc, even in the last vaporizing unit of the series, the temperature of' the mercury vapor need not bc so high as to effect cracking (decompo- 1926. ,serial No. 112,443.

sition) of the oil; which, in ordinary distillation processes, even where the oil is under vacuum, is a serious cause of damage to the distillate. Hence, it is practicable to feed to all the vaporizing units mercury vapor at the same pressure and temperature, which must of course be high enough to effect vaporization of the higher boiling point fractions inA the last vaporizer of the series.

lt is, however, desirable, from the standpoint of economical operation, to maintain a minimum practicable temperature difference between the mercury and the oil in the several vaporizing units, This is accomplished, to a degree, `in the process and apparatus of oursaid application, wherein two mercuryboilers Vare provided, which generate mercury vapor at different temperatures, and in which the vaporizing units are di- -vided into twoset-s or series, the first 'of which utilizes mercury 'vapor from one boiler ata relatively low pressure and temperature and the second of which utilizes mercury vapor from the other boiler at a relatively high pressure and temperature.

- It is. however, desirable to avoid the use of a plurality of boilers, and it is also desirable to secure a minimum practicable temperature difference between the mercury and the oil in cach vaporizer unit.- `In the present invention, this object is accomplished. Only one lnercuryboilcr, operating under a constant pressure. is required` while means arc afforded whereby any desired pressure and temperature of condensation` not crutcedincr that in the boiler itself, may be established in the mercury Yapor chamber of any vaporizcr unit.

It will alsobe understood that with a low pressurein the mercury vapor chamber and lin the condensate return pipes leading therefrom, the boiler pressure is effective to back up the liquid mercury in the condensate return pipes, thus necessitating the positioning of the vaporizingr units at a relatively high .altitude, which involves additional expense of construction and inconvenience of operation. A fifi-ther objecot our invention is to avoid the necessity of positioning the vaporizers at an inconvenicntly high level, which object is accomplished in the present invention.

luthe drawings, whiclrshow a preferred l. part of the same plant.

- Referring first to Fig. 1: 1o.

One end of one of the vaporizin units a comprising a chamber b for the oi and, in

i' -heat exchange relation therewith, a chamber along which the oil is adapted to .flow at conc-for the reception of mercury vapor, is shown 4in the'upper left-hand corner of Fig. l. This vaporizing unit' is an elongated cylinder'divided into said chambers by means of a longitudinally extending panor partition slightly inclined to the horizontal, and down siderable speed and spread out Athereon into a thin wide stream. The mercury boiler d, which is shown only in diagram, communicates with mercury vapor feed pipe e, which erably,

tended to maintain in the boiler.

in turn communicates with the mercury vapor chamber c of the vaporizer unit. A valve f' controls the flow of mercury' vapor into chamber c. i

A mercury vapor condensate outlet pipe g may connect directly with, or constitute the upper end of, a pipe section j hereinafter de-v scribed, but it is preferred tol connect the pipe directly with' the upper end of a cup h, which, together with the goose-neck pipe i, constitutes a' liquid mercury seal, or-trap. Any sediment will collect in this trap, which may be cleaned at intervals, if necessary.

The pipe g and the vapor space at the top of the cup i., connects, by means of a pipe n, with the upper end of the inflowsection y of a pipel m, which section extends downward for a considerable distance, thence upward for a distanceequal to half the len h of its downward extension (forming a -shaped sect-ion k) and thence laterally, in a slightly downwardly inclined direction either direct to the vapor space of the boiler, or prefas shown, to a vapor space at the top of a-vessel. o, which extends'below the level of the liquid mercury inthe boiler and connects therewith by means of a liquid mercury A pipe p. The vapor space in vessel o should communicate with the vapor space on the boiler, as, fo'r example, by means of a .pipe u connecting pipe m and the mercury vapor feed pipe e.

The desirable'depth of the Ushaped pipe' section 1c below the lateral outflow section ofA pipe lm, and the desirable height of the pipe section 7' above the lateral section of pi.pe m will depend on the pressure which it is in` If the boiler pressure be assumed to be 3Q pounds absolute, the height of pipe section Z and the depth of pipe section k should be 60 inches.

If it be assumed that the pressure in chamber c of the vaporizer unit be the same as the boiler. pressure, it is clearfthatthetwo columns of liquid in the U-shaped pipe section k'will have a common level, as shown on'the drawings. Assume, however, that a reduced pressure is establishedin the chamber'c of the vaporizer unit. In this case, the liquid mercury would be forced down the righthand llimb of pipe section lo and up the lefthand limb thereof and into pipe section 'j until an equilibrium of pressures is established. Ifit be assumed that. an absolute vacuum is established in the mercury vapor chamber c, the liquid mercuryjvapor would be forced' halfway to the bottom of the' rightliaiid limb of pipe section and would rise half way to the top of pipe section j; that is, the level of the left-hand column would be 60 inches above the level of the right-hand column. In either assumedcase, as mercury condensate runs into pipe j, the levels of both columns would rise in unison until the right-hand limb: of pipesection k is filled,

after which the copdensate would continu-Y ously overflow into the laterally extending section of pipe m. This condition would exist in normal operation.

Thi'ottliiig valve f so as to consti'ict the iow of mercuryvapor thereinto tends to reduce the pressure and thereforethe tempera.-

tureof condensation of themercuiy vapor in" chamber c.' -The arrangement 'shown permits and compels such' a result. It is, therefore, apparent' that by a mcremaiiipulation of valve f, not only may the rate of flow of mercury vapor int'o the' corresponding chamber c be regulated, but any desired absolute pressure may be established in such chamber. It, therefore, becomes possible toreduce to any desired minimum the temperature difference between the mercury rin chamber c andthe oil in chamber b. It becomespossible, also, to progressively increase the tenipeiature in the mercury chambers of successive vaporizing units, so that, as the oil is gradually raised iii temperature, the temperature difference between the mercury and the oil inall the vaporizing units may be maintained as nearly uniform as may be desirable. In practice, the absolute pressures'in the mercury vapor'chambers of all the vaporizing units, or in all-except the last unit of the sev ries, will be less than boiler pressure, so that,

there will be a coluinn of mercury condensate in pipe section As the mercury condenses and flows into the cup h, it flows out of pipe 'i into pipe sec- A tion j and a corresponding amount of condensate flows out of pipe section 7c into the laterallyextending pait of pipe m', whence it flows'iiito vessel o.

It is desirable to maintain a constant boiler pressure. which it would be diilicul't, if not practically impossible to do, without some special provisions. That is, it is necessary closed in oursaid first application, but it is preferred to utilize the means herein shown 'and which .will'now be described.

from the mercury vaporfeed or A pipe r supply line c communicates with a container s which contains a small chambert having a small mercury vapor inlet in which seats a pressure control valve o, the stein of which`is loaded by a weight fw.l The weight of the valve is such that it will open when the pressure of mercury vapor exceeds the desired mercury boiler pressure. Chamber t communicates with a condenser a: and beyond it with a pipe y having at its lo'wer end a goose-neck 2.

Assuming a boiler pressure of thirty pounds absolute, the goose-neck z should be 6() inches in height, and the pipe y should extend G inches above the goose-neck. The latter may connect direct with the vapor space of the mercury boiler or' with the'vapor space of the vessel o or with any vessel or pipe simf ilarly connected with vthe boiler;

Any'mercury'vapor that enters chamber t, due to' rise in boiler pressure above 30 pounds, will be ycondensed in condenser a: andl will Howdown `pipe 1/ while a corresponding'a "'ount Yof condensate will flow into vesselio.

Fig. 2 shows in diagram the principal elements of a complete plant. In addition to vaporizer a, any number of additional vaporizers and 11 are provided, the mercury chambers ofwhich are respectively connected with branch inlet pipes 12 and 13 re- 'spectively controlled by valves 14 and -15 respectively. The mercury vapor chambers of vaporizers 10 and 11 are also provided with the mercury condensate outlet pipes 16 and 17, all of the condensate pipes eing connected w'ith the mercury boiler by means similar to those connecting mercury condensate pipe g with the mercury boiler.

The oil from-a-source of supply iows intoA -and through the oil vaporizer space of'vaporizing unit 10 at a rapid rate, spreading out over the partition separating this space from the mercury chamber in a thin sheet so as to bring every particle of the oil in heat exchange relation with the mercury vapor and condensing a fraction thereof whose percentage relative to theventire volume of oil admitted will depend (principally) on the length of time to which the oil is ex osed to the heat and to the temperature of t e mercury vapor. The temperature of the mercury vapor is regulated by regulating-its pressure, which is regulated bythrottling the valve 14: (correspon ing to valve f of. F 1g. 1) as heretofore explained. The oil vapors pass 'drectly out the top of the oil vaporizing space to a condenser (not shown). The residue which constitutes the dominant proportion of the oil admitted, then flows through pipe to the next vakporizing` unit 11, wherein a similar operation'occurs, a higher boiling point fraction being vaporized. In this vaporizing unit, the temperature of the mercury vapor is'preferably higher than in vaporizing unit 10, which higher; temperature is obtained by throttling the valve 15 to a less degree than valve 14 is throttled. In the last vaporizing unit a of thev series into which the residue from all the other v'aporizers is admitted through pipe 21, the valve f need not be throttled at all, so as to allow the mercury vapor therein to be, if desired.,v at boiler pressure.

While mercury is preferred as the direct heating medium, it is possible to substitute other vaporizable metals, such as cadmium and zinc.

Provision yshould be made for evacuating the mercury vapor systemI at the beginning of a run in order that no air may be present in thesystem at the start. For this purpose there is shown a valved pipe e communicating with the vapor feed pipe eand adapted to be connected with a vacuum pump (not shown). A

While the invention finds its probably most useful application in the distillation of lubricating oil from topped crude oil, it is adapted, also, to the distillation of crude oil which has been cracked and afterward purified by chemical treatment. The invention is also applicable to the distillation of higher constituents from the 'crude oil itself or from crude oil from which hasbeen distilled oit only part of such lighter constituents. To adapt the invention to any kind of distillation, it is necessary only to suitably modify the pressure andtemperature factors, which modiicationis within the capacity of those skilled in the art of refining oil.

IVe do not herein claim the apparatus herein described, as this forms the subjecttially less than the autogenous pressure on ysaid confined path a .vapor pressure substanf.

elfi

the body of 4liquid mercury, returning the mercury condensate to saidbody of liquid mercury and in the return of liquid condeir sate flowing the condensate through a vapor space subject to the vapor pressure in said confined path and'downward and upward through balancing columns of liquid mer'- curv whose heights diffe-r. in accordance'with theudifl'erent pressures to which they are exposed.

2. The process of distillingmineral oil which comprises flowing a stream ofoil continuously into, through and out of a confined space, generating mercury vapor from a body of liquid mercury, flowing nicrcuryr flowing the condensate through a. vapor space i subject to the reduced pressure in said confined path and successively'downward and upward through balancing columns of mercury whose relativeheights 'vary with the Variation in the extent to which the pressure in said confined path is reduced below that on the said body of liquid mercury.

8. The process of distilling mineral oil which comprises flowing a stream of oil continuously into, through and out of a confined space, generating` mercury vapor from a body of liquid mercury, flowing mercury vapor toward and into a confined path in heat exchange relation with the oil in said space and partly vaporizing the oil and condensing the mercuryvapor, maintaining in said confined path a va por pressure substantially less than the autogenous pressure on the body of liquid nier-cury, returning the mercury condensate to said body of liquid mercury vand in the return of liquid condensate' flowing the condensate through a vapor space communicating with the vapor space in said confined path and through a column of said condensate whose hydrostatic pressure is sufficient to balance the difference in vapor pressures on the body of liquid mercury and in said confined path.

4. The process of distilling mineral oil v which comprises flowing a stream of oil continuously into, through and out of a confined space, generating mercury yapor from a body t said bday f liquid mercury and inV theirel turn of liquid condensate flowing the condensate through a vapor space communicating with the vapor space in said confined path Yand, a va por space in communication with the mercury vapor flowing from said body of mercury and .establishing between said vapor spaces a column of said condensate whoseV hydrostatic pressure is sufficient to 'balance the differencebetween the vapor pressure in said vapor spaces..v .y

5. The process of distilling mineral oil which comprises flowing a ystream of oil con tinuously into, throughand out of a confined space, generating mercury` vapor from a body of liquid mercury, flowing mercury vapor toward and into a confined path ,in heat exchange relation with the oil iii said space and partly vaporizingthc oil and condensing the mercury vapor, `maintaining in said confined path a va por pressure substan-U tially less than the utogenous pressure on tliebodyofliquid mercury, retaining the niercurycondensate to said body of liquid mercury and in the return of' liquid condensate fiowin the condensateithrough a vapor space subject to the vapor pressure ink said confined path andrjdownward and .upward through balancing columns of 1 liquid mercury, and thence through ava'por space in coniniunics'rgtion with themercury vapor flowing from said body of inercuryfoward said confined path.

6. The lprocess of distilling mineral oil whichcomprises flowing a. stream of oil continuously into, through and out of a confined space, generating mercury vapor from a body of liquid mercury, flowing mercury vapor to- Ward 4and into a confined path in heat exchange relationwith the oil in said space and partlyvaporizing the oil and condensing the mercury vapor, maintaining in said confined path a. vapor pressure substantially less than the autogenous pressure, on the body of liquid mercury, returning the mercury condensate to lsaid body of liquid. mercury and'in the return `of liquid condensate flowing the condensatethrough a vapor space into a second body ot liquid mercury condensate in which sediment is adapted to be trapped, and thence through balancing columns of liquid niercury whose heights differ in accordance with the difterentpressuresfto which theyvare exposed.

7: The process ofdistilling mineral oil which comprises flowing a stream of oil continuously into. through and out of a confined space, generating mercury vapor from a body `of liquid mercury, flowing mercury vapor towardmand into a confined path in heat exchange relation with the oil in said space and -partly vaporizing the'oil and condensing the mercury vapor, maintaining in said confined path a vapor pressure -substantially less than the autogenous pressure on the body of liquid mercury. returning the mercury' condensate to said body of liquid mercury and in the return of liquid condensate flowing the con.- densate through a vapor space subject to the vapor pressure in said confined path and downward and upward through balancing columns of liquid mercury, and thence into a second body of liquid mercury communicating 'with'the first body of liquid mercury and haying a vapor space in communication with the. mercury vapor flowing from said body of mercury toward said confined path.

A8. The process of distilling mineral oil which comprises flowing a stream of oil continuously into, through and out of a confined space, generating mercury vaporfrom a body of liquid mercury, flowing mercury vapor toward and into a confined path in heat exchange relation with the oil in said space and partly vaporizing the oil and condensing the mercury vapor, maintaining in said confined path a vapor pressure substantially less than the autogenous pressure on the body of liquid mercury, returning the mercury condensate to said body of liquid mercury and in the return of liquid condensate flowing the condensate through a vapor space into a second body of liquid mercury in which sediment is adapted to be trapped, and thence through balancing columns of liquid, mercury, and thence, through a vapor space in communication with the mercury vapor flowing toward said confined path, into a. third body of liquid mercury in communication with the first body of liquid mercury.

relation with the respective confined spaces to effect, by heat exchange and condensation of mercury vapor, partial vaporization ofthe oil flowing` through each of said confined spaces, and returning the mercury condensed in each of said confined paths to said body of liquid mercury, .maintaining differential pressures in a plurality'of said confined paths by differentially regulating the rate of 'flow thereinto of mercury vapor, and in the return of said condensate from each of said confined pathsflowing it through a vapor space subject to the pressure in said confined path and downward and upward through balancingcolumns of mercury whose relative heights automatically' vary with the variations in the extent to which the pressure in such confined path is reduced below that on said .body of liquid mercury.

In testimony of whichA invention, we have hereunto set our hands, atl Marcus Hook, Pennsylvania, on this 18th day of May, 1926.'

` ARTHUR E. REW. JR. HENRY THOMAS. -1

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