US1799640A - Process of refining oil - Google Patents

Description

April 7, 1931- A. E. PEW, JR

PROCESS OF R'EFINING OIL Filed June 14, 1927 2 Sheets-Sheet l Illl'lllllllllllllllllllllll Patented Apr. 7, 1931 UNITED STATES PATENT OFFICE ARTHUR E. PEW, .13., OF BRYN MAWR, PENNSYLVANIA, ASSIGNOR TO SUN OIL COM- PANY, F PHILADELPHIA, PENNSYLVANIA, A CORPORATION OF NEW JERSEY PROCESS OF REFINING OIL Application filed June 14,

My invention relates to the process of distilling oil by means of mercury vapor, wherein the mercury vapor is brought into physical contact with the liquid oil to be vaporized, the mercury Vapor being at a higher temperature than the liquid oil and their relative temperatures being such that the oil will condense the mercury vapor, or a large proportion thereof, and thus abstract from it its latent heat, the amount of latent heat absorbed being sufficient to effect the vaporization of a substantial proportion of the oil.

My improved process has for its object to insure the maximum degree of intimate physical contact between the oil to be vaporized and the mercury vapor to be condensed; to effect a complete and certain separation of the condensed mercury and the unvaporized oil and insure against withdrawal of any mercury with the unvaporized oil and the withdrawal of any unvaporized oil with the mercury; to separate from the oil vapors nearly or quite all the mercury entrained therewith before such vapors are condensed as a final product; to eifect a substantially continuous transfer of the condensed mercury to the boiler so as to maintain a substantially constant and ample volume of mercury vapor in' the boiler; and to insure against escape of mercury vapor'from the system. The process also involves other advantageous features which are set forth in the following description.

While my process may be carried out in many different apparatus, I have illustrated, in the drawings, a distilling plant wherein the process may be practiced to the best advantages. Figs. 1A and 1B comprise a diagram of such a plant.

Mercury is vaporized in boiler 1 and mercury vapor flows through pipe 2 to jet 3, which extends into the vaporizing tower 34. The rate of fiow of the mercury vapor is controlled by a valve 20L By means of pump 17 oil to be distilled is drawn from a source of supply through pipe 18 into jet 3, the feed of the oil being controlled by a valve 19.

In jet 3, the oil frompipe 18 and the mercury vapor from pipe 2 are intimately mixed. The mixing of liquid oil and mercury vapor,

1927. Serial No. 198,762.

prior to their admission to the vaporizing tower 34, insures that the heat exchange shall occur while the liquid oil and mercury are in the closest possible physical contact, thereby securing, in greater degree, the conditions required for low temperature of oil vaporiza' tion and small temperature difference between the mercury and the oil. Partly in the jet 3, but principally in the tower 34, into which the oil and mercury are injected in finely divided and intimately mixed condition, the mercury vapor, being at a temperature above that of the liquid oil, gives up its latent heat and condenses, while more or less oil will be vaporized. The proportion of the oil that will vaporize, which will vary from a comparatively small percentage to nearly 100 per cent., depends on the character of the oil, on the comparative amounts of oil and mercury, on the temperatures of the oil and mercury, and on the absolute pressure within the vaporizing tower.

The unvaporized oil and the condensed mercury flow down on the right hand side of bafiie 22, where they separate by gravity. The oil, after rising to the level of the oil outlet pipe 21, is pumped out therethrough. The baflle 22 prevents any condensed mercury flowing into this oil withdrawal space. The oil, withdrawn through pipe 21 by means of pump 23, may go to storage through line 25 or, through line 24, to line 18, where it is mixed with fresh oil coming from the source of supply; the passage of the oil to storage or its recirculation being controlled by " valves 26 and 29.

The condensed mercury flows from the con ical bottom of the tower 34 through pipe 4, clean-out 5, mercury seal 6, mercury stand pipe 7 and pipe 8 to the boiler 1.

The rate of outflow of condensed mercurv through pipe 4 is controlled by a Valve 16, which should be kept open to such an extent as to maintain the level of condensed mercury in the still at about that indicated by the line 11. This is done automatically by the fol lowing construction.

A float chamber 120 is connected with the tower by means of a ipe 9, which communicates with the'oil' bo y, and a pipe 10, which communicates with the liquid mercury body. Within the float chamber is a float 12, which may be a solid iron ball and must be of such density that it will float on the liquid mercury but not on the oil. The float is on one end of a pivoted lever 121, which, through a flexible connection 13, extending around pulleys 14, is connected with a weighted lever 15 carried by valve 16. Should the level of mercury vapor in the tower and float chamber fall, the float falls, pulling cord 13, lift!- ing weighted lever 15, throttling valve 16, and reducing the outflow of mercury. Should the level of mercury vapor in the tower and float chamber rise, the float rises, allowing weighted lever 15 to fall and turning valve 16 to increase the outflow of mercury. Should the boiler be stopped, the mercury in the float chamber will lift the float sufficiently high to close valve 16, so that at no time will the tower be drained of mercury, which acts as a seal to prevent any oil from getting into the mercury boiler.

By maintaining the normal level of the oil as described, a body of liquidmercury is maintained sufficiently deep to give sufficient time for the oil to separate from the mercury before the mercury is allowed to return to I the boiler.

The oil vapors pass through grid 33 and through a column of chemical tiles 32 (preferably the well known Raschig rings) supported thereon. Thence the vapors,through line 35, pass into a dephlegmating tower 47 Through this tower extends a tube 46, through which air is forced by a blower 45. This effects a condensation of part of the oil.

The uncondensed vapors pass through pipe 48 into another tower 49, in which the remaining condensable vapors are condensed, the uncondensed (stink) vapors escaping through pipe and being condensed in a condenser 61.

Any desired proportion of the vapors may be condensed in each dephlegmating tower and there may be any number of such towers. The number of towers that will be provided will depend on the number of fractions desired. v

The oil condensed in each tower flows out through a line 36, a water cooler 37 (having an inlet 38 and outlet 39) and thence through a line 40 into a receiving tank 42; there being a separate series of these elements for each fractional oil condensate. The stink oil, condensed in condenser 61, flows into a similar tank 42. Each tank 42 is pumped out continuously by means of a pump 51. Any foreign matters entrained therein, particularly any mercury vapor that possibly may have escaped condensation in the vaporizing tower or any fine particles of liquid mercury that may have been entrained with the oil vapors, will be caught by baflies 43 and will be drawn ofl, occasionally, through valve 44 into a tank 50. From tank 50 the mercury is removed and poured into a funnel 73 through valve 72 into a small mercury storage tank 70. When tank 7 O is filled or nearly filled, valve 72 is closed and valve 71 opened and the mercury is allowed to flow back into the system.

Inasmuch as only minute quantities of mercury are likely be entrained in the oil, thetransfer of mercury from tank 50 to tank 7 0 need take place only at long intervals, and a long time will be required to fill tank 70.

It is preferred to provide a shunt line 31 around pump 17 and to provide this line with an automatic relief valve 310. It is also preferred to provide, around pump 23,'a shunt line 27 having an automatic relief valve 28.

From appropriate points, say from the combination oil receiving and separating tanks 42, connections 41 are provided to vacuum pumps (not shown) for maintaining any desired degree of vacuum in the oil system.

The described process may be operated either in batch or continuously.

Vvhile, in the claims, I have specified mercury vapor as the heating medium, I do not mean to exclude, as equivalents, any metal, metallic compound, metal alloy or other substance, that may be found to possess the characteristics of mercury vapor that adapt it to the present process. Such characteristics are, principally, as follows: Its boiling points, at practicable absolute pressures, correspond to temperatures desirable in oil distillation; the heat transferred to the oil, with each degree of temperature difference between the mercury vapor and the oil, is very much greater than where a hot gas or vapor, such as steam or furnace gases, is used as a heatin medium; most of its heat is usefully expen ed in heating the oil; the temperature difference between the heating medium and the oil is permissibly very small; the

amount of'the heating medium required to efl ect the desired vaporization, is relatively very small, making it practicable to avoid the use of an apparatus of excessive size; no injury is done to either the oil or the heating medium by their temporary admixture; and no serious difficulty is presented in effecting a complete separation of the oil and the heating medium, so that the latter may be re-used indefinitely.

I am aware that it is known to crack hydrocarbons by vaporizing the hydrocarbons, commingling with the hydrocarbon vapors mercury vapor which has been superheated, thereby cracking the hydrocarbon vapors, conducting the cracked hydrocarbons and the mercury vapor to a condenser and therein condensing the mercury vapor and the heavier hydrocarbons and then separating out the uncondensed hydrocarbons from the condensed however, the object is not to crack, but to tainty.

avoid cracking. The mercury vapor must not be superheated. The mercury vapor is admixed with the oil while it is in a liquid condition and not as a vapor. The heat imparted to the oil is not that due to the reduction in temperature of the mercury vapor, which has a comparatively low rate of heat transfer and involves a great initial temperature difference between the oil vapor and the mercury vapor, but is the latent heat which the mercury vapor gives up in its condensation, which permits a very small initial temperature difl'erence between the liquid oil and the mercury vapor. The condensation of the mercury vapor .is not effected after the reaction and outside the reaction zone, but necessarily is involved in the reaction and occurs in the reaction zone.

It is not intended, however, to claim, broadly, any process of distilling oil by the intimate mixture of oil in a finely divided state with mercury vapor so as to effect partial vaporization of the oil and accompany ing condensation of mercury vapor, nor, broadly, the subsequent separation of the condensed oil vapors and the mercury entrain-ed therewith, nor, broadly, the return of the condensed mercury to the mercury boiler; although I believe that my process is the first in the art to effect these operations with efficiency and cer- Among the principal features of the process is the owing of the oil and mercury vapor in a confined path and the spraying of the mixture into a relatively unconfined space, so as to insure a most intimate physical contact of the oil and mercury vapor and thereby afford the conditions adapted to effeet the vaporization of the oil at the lowest practicable temperature and with the smallest practicable temperature difierence between the mercury and the. oil. The complete and certain separation of the unvaporized oil and condensed mercury and the substantially continuous return of the latter to the boilers also involves a problem the solution of which forms an important part of my invention and is necessary to the practical operativeness of the broad process. The tendency of the oil vapor to carry with it entrained mercury necessitates the separation of the oil condensate and the mercury. In my invention this separation is almost wholly effected by a partial condensation of the oil vapors above the reaction space inwhich the mixture of oil and mercury vapor is sprayed, so that nearly or possibly uite all of the mercury entrained with the 011 vapors drops, with the fractionated oil distillate, through said space into the lower space which receives the mixture of unvaporized oil and the major part of the condensed mercury and wherein the separation of the mercury occurs. a While provision is made for recovering any mercury that may possibly be entrained in the particularly pointed out in the appended I claims. 1

Having now fully described my invention, what I claim and desire to protect by Letters Patent is: I

1. The process of distilling oil which comprises flowing a stream of mercury vapor and a stream of relativel confined path wherein they intimately mix and thence flowing the oil-mercury mixture into a relatively unconfined space, the mercury vapor being at such higher temperature than the oil that, by heat exchange and condensation of mercury vapor, a portion of the oil will be vaporized, and separating the condensed mercury from the unvaporized oil.

2. The process of distilling oil which comprises generating mercury vapor from abody of liquid mercury, spraying the oil and mercury' vapor into an open space, the mercury vapor being at such higher temperature than the oil and in such intimate physical contact therewith as will effect, by heat exchange and condensation of mercury vapor, the vaporization of a part of the oil, allowing the unvaporized oil and condensed mercury to fall cold liquid oil into av through said space, fractionally condensing the oil vapors, and returning the fractionated distillate through said space to the unvaporized oil, and separating the unvaporized and condensed oil from the condensed mercury condensate by gravity.

if. The process of distilling oil which comprises flowing a stream of mercury vapor and a stream of relatively cold liquid oil into a confined path wherein they intimately mix prises generating mercury vapor from a body of liquid mercury, introducing the oil in a finely divided condition and the mercury vapor into an open space, the mercury vapor being at such higher temperature than the oil and in such intimate contact therewith as will effect, by heat exchange and condensation of mercury vapor, the vaporization of a part of the oil, allowing the unvaporized oil and condensed mercury to fall through said space and the oil vapors to rise in said v space, condensing part of the vapors as they rise, the condensate returning through said space to the unvaporized oil, and separating the unvaporized and condensed oil from the condensed mercury.

In testimony of which invention, I have hereunto set my hand, at Philadelphia, Pennsylvania, on this 2nd day of June, 1927.

ARTHUR E. PEW, JR.

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