US2374549A - Fractionating apparatus - Google Patents

Description

April 24, 1 945. w. A'. M MILLAN FRACTIONATING APPARATUS Original Filed Oct. 5, 1940 WALLACE A.McM|L| AN INVENTOIR HIS ATTORNEY m2 OumWumlIOO m ozrEzorruk 2232 ozjoou Patented Apr. 24, 1945 UNITED STATES PATENT OFFICE FRACTIONATING APPARATUS Wallace A. McMillan, Glenham, N. Y., assignor to The Texas Company, New York, N. Y., a corporation of Delaware Original application October 5, 1940, Serial No. 359,853. Divided and this application October 15, 1942, Serial No. 462,113

3 Claims. (cl. 202-160) This invention relates to distilling and fractionating apparatus of the type adapted for the analysis of mixtures of volatile liquids, gases of vapors'containing condensable liquid fractions, and more particularly to apparatus of this character by means of which eflicient control of the fractionation may be obtained while at the same time the temperatures andpressures of the fractionation may be accurately recorded.

The present application is a division of Serial With the apparatus to be described the operation can be conducted without the frequent attendance of any operator since the fractionation and the recording of the temperatures and pressures are automatic. Apparatus which is now on the market also necessitates several complicated elements which are fragile and very expensive and also involves a complicated measuring and re-' cording system which requires the use of preci- No. 359,853, flied October 5, 1940, for Fractionatthe pressure of the fractionated vapors increase to a predetermined value. Still another object' is to provide means for regulating the passage of fractionated vapors from the fractionating column to a receiver in accordance with the pressure of said vapors.

Apparatus for analytical distillation and fractionating comprising essentially a distilling bulb, an elongated fractionatirig tube or column surmounting the bulb and a condenser section at the upper end of the fractionating tube with equipment for collecting and measuring the distilled vapors is known; for example, see Podbielniak Patent No. 1,917,272, granted July 11, 1933. Apparatus of this type operates on the principle of sharp, relatively adiabatic fractionation to separate constituents of the mixture being analyzed in the order oi their boiling points. Apparatus 0! this type which is available on the market has so far sufliced to provide only a proximate analysis of the mixtures and has proved incapable of giving accurate quantitative results, or even reproducible results with different operators.

An apparatus for accomplishing these results, and by means of which accurate and reproducible'results may be obtained, is described in the McMillan Patent No. 2,005,323. granted June 18, 1935. The proper operation of that equipment necessitates the constant attendance of at least 7 "one operator since it is necessary to make various manual adjustments to the apparatus during the distilling and fractionation of a" given mixture.

'sion equipment which is difllcult to obtain. Much of this precision equipment is obtainable only from foreign countries. Moreover, with the apparatus now on the market there is considerable dead space in the pipe connections through the receivers and this, of course, interferes; with the accuracy of the determinations.

In accordance with the present invention, an apparatus comprising a distilling bulb, an elongated adiabatic iractionating tube disposed thereabove and surmounted by a condenser section is provided together with means for automatically supplying a cooling liquid to this con-denser in accordance with the pressure of the vapors leaving the condenser section. Means are also provided for decreasing the heat applied to the distilling bulb when or if the pressure of the vapors leaving the condenser section reaches a predetermined point. The invention also contemplates the use of a pressure-temperature recorder or the "recording potentiometer typ this instrument being operated automatically by and in accordance with variations in pressure in the vapors passing from the condenser section. A pen is adapted to trace a record on a. chart roll in accordance with variations in temperature of the vapors in the condenser section while at the same time the chart roll is advanced so that the chart travel is directly proportional to increases in pressure of the vapo'rs leaving the condenser section.

For a further understanding of the invention "reference may be had to the accompanying drawing in which:

Figure 1 is an elevational view generally diagrammatic of the apparatus embodying the improvements oi the present invention:

Figure 2 is a vertical, sectional elevation through the liquid valve, and

Figure 3 is a vertical elevation showing a modifled form of valve- Referring to the drawing, an elongated, jacketed, tractionating tube or column I0 is provided at its lower end with a distillation vessel or bulb l2 and a jacketed condenser section I! at its upper end. The distillation bulb is provided with a suitable heating element such as the electrical resistance coil l8. A conduit l8 comprising a vapor passage leads from the condenser section to one or more receivers 28 in which a reduced pressure is normally maintained as by means of a suitable vacuum pump 2|. A container 22 of a cooling medium such as liquid nitrogen is connected to the condenser section H by means of v pipe 24 and a pipe 28 leading from a source of compressedair, not shown, is connected to the top of the vessel 22, the arrangement being such,

can be sealed into the opposite legs of the Tafter the T has been constructed, or the entire T may be cast around the ends of the pipes and the discs as will be described hereinafter, that the comerably formed of sintered glass filter plates and extending across the vapor passage. One legof a mercury manometer 32 is connected to the conduit l8 between the disc 38 and the other leg of the manometer is open to atmosphere as usual. A flexible tube 34 connects the lower end of the manometer 32 with a mercury bulb or reservoir 36 which can be adjusted up or down to vary the height of the mercury in the manometer. The porous discs 38 may be formed of glass ground to a powder, burned to a slntering point and formed into discs or plates of a convenient size and are of such construction that they are pervious to the passage of gas or vapor while impervious to the passage of mercury therethrough. Thus, when the pressure in the oiT- take l8 drops below a certain value the mercury will rise in the manometer leg connected to the ofitake and will fill the space between the two sintered discs 30, thus preventing vapor from the fractionator I8 from passing to the receivers 28.

38. In either case a construction is provided which is transparent so that mercury within the valve can be observed and which will provide an insulating medium in which electrical contac and wires may be mounted.

Within the valve 28 are arranged upper and lower electrical contacts 38 and 48, respectively, and at a lower point in themanometer 32 is disposed a third contact 42. Disposed in the pipe- 26 leading to the vessel of cooling medium 22 is a valve 44 normally held in an open position by means of a compression spring 48. The valve 44 is provided with a solenoid 48 and the solenoid winding is connected in circuit with a suitable source of electricity 50, the upper contact 38 and the third contact 42 in the manometer 32. In the operation of this portion of the apparatus when the mercury within the manometer 32 fills the space between the discs 30 so as to shut off the gas or vapor passage, the electrical circuit will be completed between contacts 38 and 42 and the solenoid 48 will be actuated to hold the valve 44 in its closed position against the compression of the spring 46. When the pressure increases in the ofitake I8, the mercury will be depressed in the manometer leg and the electrical circuit will be broken between contacts 38 and 42, whereupon the solenoid 48 will be deenergized and the spring 48 will open the valve 44 allowing compressed air to pass into the vessel 22 and force part of the liquid nitrogen into the condenser H to cool the vapors and thus reduce the pressure. When the pressure has been sufficiently reduced, the mercury will rise in the manometer leg, thus again closing the electrical circuit just I described, so that the valve 44 will be closed to stop the flow of cooling medium into the condenser, thereby allowing the pressure to increase again. It will be seen, that an apparatus has thus been provided whereby the fractionation will be controlled automatically in accordance with the is described in the aforementioned McMillan in Figures 2 and'3 and has proved to be very satisfactory. As shown in Figure 2, the discs 38 are sealed in the ends of pipes |8A, these pipes comprising a portion of the offtake |8 previously described. The ends of the pipes |8A containing the discs 38 are placed in a T 3| which may be of metal or other suitable material and the ends of the pipes are preferably seated against suitable gaskets 33. A sealing material is placed so as to seal the space around the ends of the pipes |8A and between the pipes and'the T 3|. It has been found that this construction is simple to effect and it renders unnecessary the importing of expensive equipment. Although the T 3| is shown as constructed of metal, this member may, of

course, be made of glass which will provide suit-1 to be placed within the va ve and which will be described hereinafter. other method of mounting the glass discs 38 is shown in Figure 3 able insulating means for 11: electrical contacts in which the discs are sealed in opposite legs of a T 35 formed of a plastic,'preferably of acrylic or styrene resin types. The ends of the pipes |8A armature 88 of the relay 54 is adapted to close' a circuit containing, a source of electricity 58 and a suitable alarm device such as a buzzer 88. Thus,

should the pressure in the offtake l8 rise to an abnormal degree, the circuit between the contacts 48 and 42 will be broken, thus de-energizing the coil 82 and permitting a spring 82 to pull the armature 56 to the right to close the circuit to energize the alarm 88. In addition the circuit containing the electrical source 88 is preferably connected to the coil 84 of a relay 88 and a suitable switch 88 through wires 89. The relay 88 is connected in circuit with the electrical heating coil l8 of the distillation vessel |2 so that in the event of an abnormal increase in the pressure of the vapors in offtake l8, the relay 54 will be closed not only to actuate the alarm 88 but also to energize the relay coil 84, thus pulling the armature 12 to the right against the tension of spring 18 to open the circuit containing the heating element l8 of the distillation vessel l2. The

reduction of heat in the vessel l2 will, of course,

pressures and temperatures of the vapors leaving the condenser section It and passing through the conduit I8 to the receivers 28. To this end a second mercury manometer I4 has one leg 18 communicating with the conduit I8 through a valve I8. The other leg of the manometer is open to the atmosphere as usual and a flexible tube 88 connects the lower end of the manometer with a mercury bulb or reservoir 82. The reservoir 82 is mounted in a bracket member 88 slidable vertically on a guide rod 88 and having threaded connection with a rotatable threaded rod 88, the latter supported in suitable bearings 88. As the'rod 88 is rotated the bracket 88 and 7 thus the mercury reservoir 82 will bemoved up able wires I02. The instrument 82 may be of any suitable type as long as it includes the elements so far mentioned. A reversible electric motor I04 is arranged to drive the chart roll 88 through suitable gearing I88 and this motor is also connected through suitable reductidn gearing which may comprise a worm and wheel I88, to drive the threaded rod 88. Thus, when the motor I 84 is energized it will rotate the chart roll 88 to advance the chart 88 while at the same time the rod 88 will be rotated to raise the bracket 88 and thereby the mercury reservoir 82.

In order to control automatically the motor me, an electrical circuit is provided comprising a contact H0 mounted within and near the upper end of the manometer leg 18, and another contact II2 located within and adjacent the bot- I tom of the manometer I8. In addition to the contacts H8 and H2 this circuit also includes a ,source of electricity Ill .and a break relay 8.

The contacts, not shown, of the relay'II8 are connected in another circuit with the motor I88 and a source of electricity II8. As the receiver pressure rises during distillation the mercury I level in the manometer leg I8 will fall below the contact 8, which comprises a fixed reference point, and the circuit to the relay I I8 will thereby be broken and the actuation of the relay will then complete the circuit to energize the motor 688, As stated hereinbefore, when the motor 988 is energized it will drive the chart roll 84 to advance the chart 88 and simultaneously therewith it will rotate the threaded rod 88 so as to lift the mercury reservoir 82 to bring the mercury level in the manometer leg 18 back until electrical gontact is remade at 0, The completing of the circuit between,contacts H8 and H2 will thus actuate the relay Il8-to stop the motor I88 and the chart 88 and the mercury reservoir 82 will remain in the positions then obtained until the receiver pressure again depresses the mercury in the manometer leg I8.

sufllciently to open the circuit to the relay II8 when the cycle will be repe ted.

a As long as a certain co nent of a gaseous mixture is being distilled from the column I8 the temperature will. of course, remain substantially constant. The pressure in the receiver 28 and the ofltake I8 will, however, increase during this straight, vertical line such as I28 on the chart 88. When the distillation of one component of the gaseous mixture has been completed the temperature will, of course, rise until the boiling point of the next component or the next constant boiling mixture is reached. The pen 88 will thereupon move horizontally a certain distance across the chart 88 as indicated at I22 with very little vertical movement of the chart during this time so that the distillation curve will be a series of slopes and plateaus in the usual manner. The proportion of any ingredient in a gaseous mixture can be readily computed from the chart by calculation of the ratio of the length of the vertical line representing the distillation of that component, to the total vertical length of the chart during the entire distillation. When the mercury reservoir 82 has been lifted to the top of therod 88, 'or whenever it is desired to change a chart, to adjust the amount of mercury in the reservoir or to change distillate receivers it is merely necessary to close the valve I8 and to energize the motor I84 so that it will be operated in the reverse direction. The rod 88 will then rotate to lower the bracket 88 and the reservoir 82 to a point near the bottom of the rod after which the valve I8 can be opened and a. new recording started. a

It will thus be seen that by a comparatively simple construction the apparatus of the present invention accomplishes the following operations entirely automatically: controls the supply of cooling medium to the condenser jacket of the distillation column, in accordance with the distillation pressure at the outlet of the column; controls the supply of heating fluid to the still, in accordance with the distillation pressure, and actuates the chart of the recording instrument so that the travel of the chart is made proportional to the pressure increase within the vapor receiver.

Obviously many modifications and variations of the invention, as hereinbefore set forth, may be made without departing from the spirit and scope thereof and therefore only such limitations should be imposed as are indicated in the appended claims.

I claim:

1. In apparatus for distillation and fractionation, comprising in combination a distilling means, a fractionating column communicating with said distilling means, a partial condenser for'condensing vapors passing from said fractionating column and for supplying reflux to the fractionating column, means for supplying a refrigerant to said condenser, a receiver, avapor ofitake leading from said condenser to said receiver, a liquid valve in said oiftake including a member porous to vapor but impervious to liquids and a mercury manometer communicating with said vapor ofltake at the downstream period and the pen 88 will, therefore, draw a II side of said porous member and responsive to pressure in said ofitake, and means associated with said liquid valve and actuated on a predetermined movement of the mercury in said liquid valve for actuating said refrigerant supplying means, said last named means comprising an electrical circuit including an electrical contact in said liquid valve, a second electrical contact in said manometer, a source of electricity, and a device for actuating said refrigerant supplying means when the electrical circuit is open between said two contacts.

2. In apparatus for analytical distillation and fractionation having a distilling section and an elongated fractionating column communicating with said distilling section, means for cooling the upper end of said fractionating column, means for actuating said cooling means, a vapor oiTtake from said column, a liquid valve in said 05- take comprising a pair of discs porous to vapor but impervious to liquid and a mercury manometer having one leg communicating with said valve between said discsand responsive to pressure in said oiftake, an electrical contact within said valve normally covered by said' mercury, a source of electricity, and an electrical circuit including said contact, the mercury in said manometer, said source of electricity and laid actuating means, the arrangement being such that on a predetermined increase in pressure in said ofitake the mercury in said valve and said manometer leg will be depressed to uncover said contact and open said electrical circuit thereby actuatingsaid cooling means to cool said column and reduce the pressure in said ofltake.

3. In apparatus for distillation and fractionation, comprising in combination a distilling .means, a fractionating'colu'mn communicating with said-distilling means, a partial condenser for condensing vapors passing from said frac .tionating column and for supplying reflux to the fractionating column, a supply of compressed as connected to force a refrigerant into said condenser, a receiver, a vapor ofltake leadgig fro said condenser to said receiver, a valve said ofitake responsive to the pressure therein, said valve comprising a pair of vertically disposed flat members porous to vapor but impervious to liquid, said members being arranged in separated relation to form a liquid chamber therebetween, a mercury manometer communicating with said chamber, and means associated with said valve for operating said refrigerant supplying means, said operating means comprising a source of electricity, an electrical contact in the upp r part of said chamber, a second contact in the lower portion of said manometer, a solenoid operated valve in said compressedgas connection, and an electrical circuit including said contacts, said solenoid and said source of electricity, the arrangement being such that on a, predetermined increase in pressure in said oil'- take, the mercury in said chamber will be depressed to open said electrical circuit to actuate said solenoid to allow compressed gas to force said refrigerant into said condenser.

WALLACE a. McMILLAN.

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