US1714812A - Apparatus for distilling mineral oil - Google Patents

Description

May 28, 1929, A. E. FEW, JR., ET AL APPARATUS FOR DISTILLING MINERAL OIL 2 Sheets-Sheet l Filed May 29, 1926 PRESSURE v CONTROL VALVE VAPORIZER 30 lbs.

ABSOLUTE PRESSURE.

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APPARATUS FOR DISTILLING MINERAL OIL Filed May 29, 1926. 2 Sheets-Sheet 2 wrcwrms Patented ay 28, i929.

ARTHUR E. PEW, JR., OF BRYN MAWR, AND HENRY THOI VIAS, OF RIDLEY PARK, PENN- SYLVANIA, ASSIGNORS TO SUN OIL COMPANY, OF PHILADELPHIA, PENN SYL- VANIA, A CORPORATION OF NEW JERSEY.

APPARATUS FOR DISTILLING MINERAL OIL.

Application filed May 29, 1926. Serial No. 112,444.

In applications filed by us March 5, 1925, Serial No. 13,040 and March 13, 1925, Serial No. 15,262, we have disclosed a practical and commercially operative process and apparatus for fractionally distilling mineral oil by heat exchange between mercury vapor and the oil to be distilled, theoil'being partly vaporized and the mercury vapor being condensed and returned to a body of liquid mercury which is continuously generating mercury vapor. In this process a stream of oil flows 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 relatively to its length. The mercury vapor generated in the mercury boiler is at such pressure that it will have a temperature of condensation above that of the hottest part of the stream of oil, which is the oil flowing through the last space of the 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 which the oil is flowing. in. series. The amount of mercury vapor admitted to each chamber is sufficient to effect, by heat exchange and condensation of the mercury vapor, partial vaporization of the oil flowing through each of said confined spaces. The proportion of oil vaporized in each vaporizer is predetermined by independently regulating the rate of fiow of the men cury vapor into the mercury chamber of each vaporizing unit. This may be done by means of valves located at or near the admission openings into the several mercury chambers.

In such process, however, the pressure of mercury vapor and the temperature at which it condenses may be the same in the mercury vapor chambers of all the vaporizer units.

This does not militate against the successful operation of the process, particularly because, compared with other heating media, the difi'erence in temperature between the mercury vapor and the hottest part of the oil stream need be relatively low, and hence, even in the last vaporizing unit of the series, the temperature of the mercury vapor need not be so high as to effect cracking (decomposition) of the oil; which, in ordinary distillation 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 in the last vaporizer of the series.

Itis, 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 our said application, wherein two mercury boilers are provided, which generate mercury vapor at different temperatures, and in which the vaporizing units are divided into two sets or series, the first of which utilizes mercury vapor from one boiler at a 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 each vaporizer unit. In the pres ent invention, this object'is accomplished. Only one mercury boiler, operating under a constant pressure, is required, while means are aii orded whereby any desired pressure and temperature of condensation, not exceed ing that in the boiler itself, may be established in the mercury vapor chamber of any vapdrizer unit. 7

It will also be understood that with a low pressure in the mercury vapor chamber and in the condensate return pipes leading therefrom, the boiler pressure is ellective to back up the liquid mercury in the condensate return pipes, thus necessitating the positioning of the vaporizing units at a relatively high altitude, which involves additional expense of construction and inconvenience of operation. A further object of our invention is'to avoid the necessity of positioning the vaporizers at an inconveniently high level, which object is accomplished in the present invention.

In the, drawings, which show a preferred construction embodying our invention:

Fig. 1 is a diagrammatic View of part of a plant embodying our invention.

siderable speed and spread out thereon into a thin wide stream, The me gcury boiler d, which is shown only in diagram, communicateswith mercury vapor feed pipe e,. which in turn communicates with a mercury vapor chamber 0 of the vaporizer unit. A valve 7 gontrols the flow of mercury vapor into cham- A mercury vapor condensate outlet pipe 9 may connect directly with, or constitute the upper end of, a pipe section j hereinafter described, but it is preferred to connect the pipe directly with the upper end of a cup h, which, together with the goose-neck pipe 2', constitutes a liquid mercury seal, or trap. Any sediment will collect in this trap, which may be cleaned at intervals, if necessary. The pipe 9 and the vapor space at the top of the cup it, connects, by means of a pipe 92, with the upper end of the inflow section j of a pipe m, which section extends downward for a considerable distance, thence upward for a distance equal to half the length of its downward extension, (forming a U-shaped section '72) and thence laterally, in a slightly downwardly inclined direction either direct to the vapor space of the boiler, or preferably, as shown, to a vapor space at the top of a vessel 0, which extends below the level of the liquid mercury in the boiler and connects therewith by means of a liquid mercury pipe p. The vapor space in vessel 0 should communicate with the vapor space on the boiler, as, for example, by means of a pipe to connecting pipe m and the mercury vapor feed pipe 6.

The desirable depth of the U-shaped pipe Section is below the lateral outflow section of pipe m and the desirable height of the pipe section 7' above the lateral section of pipe m will depend on the pressure which it is intended to maintain in the boiler. If the boiler pressure be assumed to be thirty pounds absolute, the height of pipe section j and the depth of pipe section should be sixty inches.

If it be assumed that the pressure in chamber 0 of the vaporizer unit be the same as the boiler pressure, it is clear that the two columns of liquid in the U-shaped pipe section k will have a common level,- as shown on the drawings. F Assume, however, that a reduced pressure is established in the chamber 0- of the vaporizer unit. In this case, the liquid merleft-hand column would be sixty inches above the level of theright-hand column..." In either. I

assumed case, as mercury condensate runs into pipe j, the levels of both columns would rise in unison until the right-hand limb of pipe section is is filled, after which the condensate would continuously overflow into the laterally extending section of pipe m. This condition would exist in normal operation.

Throttling valve f so as to constrict the flow of mercury vapor there'into tends to reduce the pressure and therefore the temperature ,of

condensation of the mercury vapor in cham-' her 0. The arrangement shown permits and compels such a result. It is, therefore, apparent that by a mere manipulation of valve f, not only may the rate of flow of mercury vapor into the corresponding chamber 0 be regulated,-but any desired absolute pressure may be established in such chamber. .It, therefore, becomes possible to reduce to any desired minimum the temperature difference between the mercury in chamber 0 and the oil in chamber 1). It becomes possible, also, to progressively increase the temperature in the mercury chambers of successive vaporizing units, so that, as the oil is gradually raised in temperature, the temperature difi'erence between the mercury and the oil in all 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 series, will be less than boiler pressure, so that there will be a column of mercury condensate in pipe section j.

As the mercury condenses and flows into cup h, it flows out of pipe 11 into pipe section j and a corresponding amount of condensate flows out of pipe section is into the laterally extending part of pipe m, whence it flows into Vessel 0.

It is desirable to maintain a constant boiler pressure, which it would be difiicult, if not practically impossible to do, withoutsome special provisions. That is, it is necessary to generate mercury vapor at a rate not less than the rate at which it is admitted to the vaporizer units, and to insure this it is practically necessary to generate mercury vapor at a rate slightly exceeding the rate at which it is admitted to the vaporizer units? Without some special provision to prevent it, this would result in a gradual building up of the mercury vapor pressure in the boiler and the feed line. Such special provision is disclosed in our said first application, but it is preferred to utilize the means herein shown and which will now be described.

A pipe 1 from the mercury vapor feed or supply line 6 communicates with a container 8 which contains a small chamber t having a small mercury vapor inlet in which seats a pressure control valve '0, the stem of which is loaded by a weight w. The weight of the Valve is such that it will open when the pressure of mercury vapor exceeds the desired mercury boiler pressure. Chamber 2? communicates with a condensers; and beyond it with a pipe y having at its lower end a goosenecl: 2. Assuming a boiler pressure of thirty pounds absolute, the goose-neck 2 should be sixty inches in height, and the pipe y should extend sixty 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 or with any vessel or pipe similarly connected with the boiler.

Any mercury vapor that enters chamber it, due to rise in boiler pressure above thirty pounds, will be condensed in condenser a: and will flow down pipe 3 while a corresponding amount of condensate will flow into vessel 0.

Fig. 2 shows in diagram the principal elements of a complete plant. In addition to vaporizer a, any number of additional vaporizers 10 and 11 are provided, the mercury chambers of which are respectively connected with branch inlet pipes 12 and 13 respectively controlled by valves 14 and 15 respectively. The mercury vapor chambers 10 and 11 are also provided with the mercury condensate outlet pipes 16 and 17, all of the condensate pipes being connected with the mercury boiler by means similar to those connecting mercury condensate pipe 9 with the mercury boiler.

The oil from a source of supply flows into 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 daamber 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 the entire volume of oil admitted will depend (principally) on the length of time to which the oil is exposed to the heat and to the temperature of the mercury vapor. The temperature of the mercury vapor is regulated by regulating its pressure, which is regulated bythrottling the valve 14 (corresponding to valve f of Fig. 1) as heretofore explained. The oil vapors pass direclly 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 20 to the next vaporizing 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 pressure is obtained by throttling the valve 15- to a less degree than valve 14 isthrottled. In the last vaporizing unit a of the series into which the residue from all the other Vaporizers is admitted through pipe 21, the valve 7 need not 7 be throttled at all, so as to allow the mercury vapor therein to be, if desired, at boiler pressure.

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

Provision should be made for evacuating the mercury vapor system at the beginning of a run in order that'no air may be present in the system at the start. For this purpose, there is shown a valved pipe 0' communicating with the vapor feed pipe 0 and adapted to be connected with a vacuum pump (not shown).

While the invention finds its probably most useful application in the distillation of lubrieating 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 has been distilled 01f only part of such lighter constituents. To adapt the invention to any kind of distillation, it is necessary only to suitably modify the pressure and temperature factors, which modification is within the capacity of those skilled in the art of refining oil.

We do not herein claim the process herein described, as the same forms the subject-matter of a separate application.

Having now fully described our invention, what we claim and desire to protect by Lettors Patent is:

1. In an apparatus for distilling oil, the combination with an oil vaporizer comprising an oil vaporizing chamber and a mercury vapor condensing chamber in heat exchange relation, the oil vaporizing chamber having an oil vapor outlet, of a mercuryboiler, a mercury vapor feed pipe connection from the boiler to the mercury chamberof the vaporizer, and a mercury condensate return llow pipe connection from the mercury chamber of the vaporizer to the boiler, said last named pipe connection comprising means adapted to provide balancing columns of liquid mercury to take care of pressure differences between the boiler and the mercury chamber of the va' porizer anda vapor-containing space between said balancing columns and the mercury chamber of the vaporizer.

2. In an apparatus for distilling oil, the

an oil vaporizing chamber vapor condensing chamber in heat exchange combination with an oil vaporizer comprising anoil vaporizing chamber and a mercury vapor condensing chamber in heat exchange relation, the oil vaporizing chamber having an oil vapor outlet, of a mercury boiler,'a mercury vapor feed pipe connection from the boiler to the mercury chamber of the vaporizer, and means afl'ording a passage for mercury condensate from the mercury 'cham ber of the vaporizer to the boiler: said passage comprising an outflow section communicating with the boiler, an inflow section communicating with the mercury chamber and extending above the outflow section, and an intermediate section extending downward from the inflow section and thence upward to the outflov section; thereby providing means for a seal of liquid mercury comprising balancing columns of mercury adapted to take care of pressure diflerences between the boiler and the mercury chamber of the vaporizer.

3. In an apparatus for distilling oil,'the combination with an oil vaporizer comprising an oil vaporizing chamber a'nda mercury vapor condensing chamber in heat exchange relation, the oil vapor izing chamber having an oil vapor outlet, of a mercury boiler; a mercury vapor feed pipeeonnection from the boiler to the mercury chamber of the vaporizer, means to regulate the rate of flow of mercury vapor from said feed pipe connection into the mercury chamber of the vaporizer, and a mercury condensate return flow pipe connection from the mercury chamber of the va porizer to the boiler, said last named pipe connection comprising means adapted to provide balancing columns of liquid mercury to take care of pressure diflerences between the boiler and the mercury chamber of the vaporizer and a vapor-containing space between the mercury chamber of the vaporizer and said balancing columns. l

4-. In an apparatus for distilling-oil, the combination with an oil vaporizer comprising and a mercury relation, the oil vaporizing chamber having an oil vapor outlet, of a mercury boiler, a mercury vapor feed pipe connection from the boiler to the mercury chamber of the vaporizer, and means affording a passage for mercury condensate from the mercury chamber of the vaporizer to the boiler; said passage comprising an outflow section communicating with the boiler, an inflow section communicating with the mercury chamber and extending above the outflow section, and an intermediate section extending downward from the inflow section and thence upward to the outflow section and providing a seal of condensed mercury to take care of pressure differences between the inflow and outflow sections of said passage; a trap interposed in the inflow section of said passage, said trap affording a space for condensateand a space for vapor, and a pipe for mercury vapor communicating with the vapor space of said trap and with the part of the inflow section of the passage beyond the trap.

5. In an apparatus for distilling oil, the

combination with an oil vaporizer comprising an oil vaporizing chamber and a mercury vapor condensing chamber in heat exchange relation, the oil vaporizing chamber having an oil vapor outlet, ofa mercury boiler, a mercury vapor feed pipe connection from the boiler to the mercury chamber of the va-- porizer, and a mercury condensate return flow pipe connection from the mercury chamber of the vaporizer to the boiler, said last named pipe connection comprising means adapted to provide balancing columns of liquid mercury to take care of pressure differences between the boiler and the mercury chamber of the vaporizer, and means aflording a shunt passage from said mercury vapor feed pipe connection; said shunt passage comprising an outflow section communicating with the boiler, an inflow section communicating with said feed pipe connection and extending above the outflow section, and an intermediate section extending downward from the inflow section and thence upward to the outflow section and adapted to contain a seal of condensed mercury; and a pressure control. device adapted to oppose the flow of mercury vapor into said shunt passage but adapted to yield to allow such flow on a predetermined increase of vapor pressure in said feed pipe connection.

6. In an apparatus for-distilling oil, the combination with a number of oil Vaporizers each comprising an oil vaporizing chamber and a mercury vapor condensing chamber in heat exchange relation, and pipe connections between adjacent oil vaporizing chambers to allow oil to flow through the Vaporizers successively, of a mercury boiler, means providing passages for mercury vapor from the boiler to the mercury chambers of the several Vaporizers, and means providing independent mercury condensate return passages from the mercury vapor chambers of the several Vaporizers, the last named passages com municating with the boiler, said last named passages comprising means adapted to provide balancing columns of liquid mercury to take care of substantially different pressure difl'erences between the boiler and the respective mercury chambers.

7. In an apparatus for distilling oil, the combination withva number of oil Vaporizers eachcomprising an oil vaporizing chamber and a mercury vapor condensing chamber in heat exchange relation, and pipe connections between adjacent oil vaporizing chambers to allow oil to flow through the vaporizers successively, of a mercury boiler, means providing passages for mercury vapor from the boiler to the mercurychambers of the several Vaporizers, and means providing independent mercury condensate return passages from the mercury vapor chambers of the several Vaporizers, the last named passages communicating with the boiler, valves independently controlling the rate of flow of mercury vapor into the mercury chambers of the respective Vaporizers, whereby the pressure and temperature of condensation in change relation, the oil vaporizing chamber having an oil vapor outlet, of a mercury boiler, a mercury vapor feed pipe connection from the boiler to the mercury chamber of the vaporizer, a mercury condensate outflow pipe from the mercury chamber of the vaporizer, a sediment cup communicating with said pi e, and means between said cup and the boi er to take care of pressure differences between the boiler. and the mercury chamber of the vaporizer and return the condensate to the boiler.

9. In an apparatus for distilling oil, the combination with an oil vaporizer comprising an oil vaporizing chamber and a'mercury ,va or condensing chamber in heat exchange re ation, the oil vaporizing chamber having an oil vapor outlet, of a mercury boiler, a mercury vapor feed pipe connection from the boiler to the mercury chamber of the vaporizer, a mercury condensate. return flow pipe connection from the mercury chamber of the vaporizer to the boiler, said last named pipe connection-comprising means adapted to provide balancing columns of mercury one of which is subject to the pressure in the mercury chamber of the vaporizer and means providing a vapor space communicating with said mercury vapor feed pipe connection and to the pressure in which the other column of mercury is subject.

10. In an apparatus for distilling oil, the combination with an oil vaporizer comprising an oil vaporizing chamber and a mercury vapor condensing'chamber in heat exchange relation, the 011 vaporizing chamber having an oil vapor outlet, of a mercury boiler,'a mercury vapor feed pipe connection from the boiler to the mercury chamber of the vaporizer, a mercury condensate return flow pipe connection from the mercury chamber of the vaporizer to the boiler, said last named pipe connection comprising means adapted to provide balancing columns of mercury, a vessel adapted to receive condensate flowing through said balancing columns,

and a condensate outflow pipe from said vessel to the boiler; and means providing vapor communication between. said vessel and said mercury vapor feed pipe connection. In testimony of which invention, we have hereunto set our hands, at Marcus Hook, Pennsylvania,|on this 18th day of'May', 1926. ARTHUR E. PEW, JR.

HENRY THOMAS.

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