US2379152A - Vacuum production and apparatus therefor - Google Patents

Description

0 p o 0 00a 4 Sheets-Sheet l o f) o o 36 003C 0 O 4) Q Q June 26, 1945. K. c. D. HICKMAN VACUUM PRODUCTION AND APPARATUS THEREFOR Filed Sept. 10. 1943 INVENT OR ATTORNEYS KENNETH C. D. HICKMAN W BY June 26, 1945. K. c. D. HICKMAN VACUUM PRODUCTION AND APPARATUS THEREFOR Filed Sept. 10, 1943 4 Sheets-Sheet 2 I F|G.4.

KENNETH 0.0. HICKMAN INVENTOR W- BY C W ATTORNEYS June 26, 1945. K. c. D. HICKMAN VACUUM PRODUCTION AND APPARATUS THEREFOR Filed Sept. 10, 1943 4 Sheets-Sheet 3 KENNETH C.D.HICKMAN ATTORNEYS June 26, 1945. K. c. D. HICKMAN VACUUM PRODUCTION AND APPARATUS THEREFOR Filed Sept. 10, 1945 4 Sheets-Sheet 4 FIG. l3.

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E w W Y E M K m a \v Patented June 26, 1945 VACUUM PRODUOIION AND APPARATUS THEREFOR Kenneth C. D. Hickman, Rochester, N. 1., as-

signor to Distillation Products, Inc., Rochester, N. Y., a corporation of Delaware Application September 10, 1943, Serial No. 501,830

9 Claims.

This invention relates to improved procedure and apparatus for producing high vacua, andin particular to improved fractionating condensation pumps of the vertical type.

Fractionating condensation pumps have been known for about a decade and were described by me in U. S. Patent 2,080,421, May 18, 1937. Such fractionating condensation pumps are adapted to employ a mixed organic pump fluid and durin operation to fractionate the components thereof and deliver the fractionated vapors to appropriate jet nozzles so that the low vapor pressure components exert their pumping action toward the low pressure and the high vapor pressure components toward the high pressure side of the pump. Vertical concentric modifications of the fractionating pump described in the above-mentioned patent have been made and are disclosed in my United States Patents 2,211,329, August 13, 1940, and 2,206,093, July 2, 1940. The vertical concentric type of fractionating pump has not heretofore been of particular value. With small pumps the boiler areas are too small. With large pumps the base of the pump tends to bow inwardly due to atmospheric pressure causing great leakage of pump fluid from one boiler into another. With pumps of this type, and especially with large pumps, it has been difficult to avoid surging and leakage between boiler compartments which greatly impair and frequently destroy the fractionating power of the pump.

This invention has for its object to provide vertical fractionating pumps in which the foregoing dimculties are substantially avoided. A further object is to provide vertical fractionating pumps in which surging and leakage are avoided or minimized. A still further object is to provide improved high vacuum pumping procedure. Another object is to provide vertical fractionating condensation pumps which can be cheaply and economically constructed. Another object is to improve the state of the art. Other objects will appear hereinafter.

These and other objects are accomplished by my invention, which includes a. vertical concentric fractionating condensation pump provided with an elongated and helical-shaped boiler and with means for delivering vapors from diilerent sections of the helical boiler to different jet nozzles.

In the following description I have set forth several of the preferred embodiments of my invention, but it is to be understood that these are given for the purpose of illustration and not in limitation thereof.

Referring to the drawings wherein like numbers refer to like parts and wherein:

Fig. 1 is a vertical section of an improved vertical fractionating pump embodying th principles of my invention;

Fig. 2 is a vertical section of the boiler of the pump illustrated in Fig. 1 and taken on line 2-2 of Fig. 1;

Fig. 3 is a vertical section taken on line 3-3 of Fig. 1;

Fig. 4 is a vertical section of a modification 'of the pump illustrated in Fig. l and showing a tapered helix forming a helical boiler and vapor delivery means extending up to the vicinity of the high vacuum jet;

Fig. 5 is a horizontal section taken on line 5-5 of Fig. 4;

Fig. 6 is a horizontal section taken on line 6-6 of Fig. 4;

Fig. '7 is a modification of the pump shown in Fig. 1 being provided with a tapered spiral and directly attached spiral jet nozzle;

Fig. 8 is a horizontal section taken on line 8-8 of Fig. 8; and

. Fig. 9 illustrates the shape of the sheet from which the tapered spiral of Fig. 7 is constructed.

Fig. 10 is a horizontal section of a pump, the spiral element of which is constructed from split cylinders, but which is otherwise much the same as that shown in Fig. 4.

Fig. 11 is a fragmentary vertical section taken on line l'l-ll of Fig. 10; and

Figs. 12 and 13 are fragmentary vertical sections of various heating pins and battles for the heating coils positioned in the spiral boilers.

Referring to Figs. 1, 2, and 3, numeral in designates a cylindrical pump casing provided with an integral base plate l2 at its lower end and with a flange H at its upper end. Casing I0 is provided with an integral conduit l6 at the lower portion thereof which is intended to connect to a backing pump (not shown). Within casing l0 and concentric therewith is positioned a plurality of integral and superimposed collars I8, 20, and 22, which cooperate with one another to form the internal chimney of an umbrella-type multi-stage pump, l8 and 20 cooperating to form a jet nozzle 24; 20 and 22 cooperating to form a jet nozzle 26, and cover plate 28 and collar 22 cooperating to form a jet nozzle 30. Collar l8 extends to and rests upon the base l2 and is maintained in a central or concentric position by means of a plurality of spacers 32. Numerals 34, 38, and 38 designate holes in jet nozzles 24 and 29 respectively through which vapors pass from'the inside of the chimney compartments and thence into the jet nozzles.

Numeral 40 designates a helix, which is preferably flexible, positioned upon base l2 and forming a helical-shaped boiler compartment beginning at the collar is and terminating at the center or axis of the pump casing l6. Numeral 42 designates an electrically operated heating unit or coil which is in the form of a spiral. Numeral 44 designates a. central conduit which delivers va pors to the jet nozzle 80. This conduit terminates at the upper portion of collar 22 and is integral with the inside surface of collar 22. The lower portion of conduit 44 terminates somewhat above the upper portion of helix, and is provided with an extension 46 which is telescopically attached thereto and free to move in a vertical direction. Extension 46 is provided with a flange 46 which rests upon the top edge of helix 40.

Referring to Figs. 4, 5, and 6, it will be noted that the pump illustrated therein closely resembles the pump illustrated in Fig. 1, differing therefrom in that it is provided with two additional jets and with a tapered helix 50 the upper tapered portion of which serves to deliver vapor fractions to appropriate jet nozzles. This tapered helix rests upon base plate l2 in the same manner as helix 40 of Fig. 1. However, the central portion of the tapered helix extends upwardly into the vicinity of high vacuum jet nozzle 36 and the various convolutions terminate at intermediate points opposite or near to the various nozzles as illustrated. This tapered helix can be easily constructed by rolling a wedge-shaped strip of fiat and preferably thin metal starting at the widest end of the strip and rolling toward the narrow end so that the center portion of the helix is the highest part of the taper. Thin metal gives increased flexibility so that the helix remains at all times in close contact with the base even if it becomes distorted.

Referring to Figs. 7, 8, and 9, numeral 60 designates a tapered helix somewhat similar to that shown in Fig. 4. However, it is constructed by rolling a flat piece of metal having a shape such as that shown in Fig. 9. The pump of Fig. '7 differs from that of Fig. 4, in that it does not involve the use of superimposed collars I 8-22 to form the jet nozzles. In Fig. 7 th jet nozzle except for the high vacuum nozzle is in the form of a helix while high vacuum nozzle 30 is the same as that illustrated in the other figures. Numeral 62 of Fig. 7 designates a helical-shaped piece of sheet metal which is integral with the top portion of tapered helix 60 and cooperates therewith to form a long or continuous helical jet nozzle 64 which gradually decreases in diameter as it rises. Numeral 65 designates an annular collar which is integral with the wall of casing l and which closely approaches spiral 60 so as to leave a narrow gap 6! for return of pump fluid to the boiler.

Many shops are not equipped to cut spiral grooves. Th construction shown in Figs. 10 and 11 avoids this difiiculty since grooves can be cut approximately circular with a bridge between the grooves. Referring to Figs. 10 and 11, numeral 16 designates a somewhat irregular spiral which is analogous to and serves the same purpose as spiral vi) in Fig. 4. The spiral shown in Fig. is constructed of a plurality of concentric cylinders 12, 14, I6, 18, and 80, which are split longitudinally and a section bent inwardly to Join with the next inner concentric cylinder. Thus, cylinder 80 is split at 82 and the wall is bent inwardly to join with the similarly split wall of cylinder II at 64. Numeral l8 designates a time integral with cylinder 60. The cylindrical elements can be made as one integral element or may be assembled piecemeal and held together by a few suitably located bolts. These cylinder elements rest in a spiral groove 66 in the base plate l2, thus positively avoiding leakage from one spiral section into another. The immersion'heater 42 can be suitably bent to follow the spiral boiler thus formed. It will be noted that base plate 12 is thick to provide suflicient material for the formation of a groove 66.

,/Numeral 66 designates baiiies positioned at intermediate points along the spiral boiler upon which rests the immersion heater 42. These baffles reduce surging to a minimum. They may be attached directly to the heater or, if desired, to the base. Further modifications along this line are shown in Figs. 12 and 13. Fig. 12 shows a battle integral with the electric heater 42 and spaced at intervals along the length of the heater. This baille indicated by the numeral 66 not only serves to reduce surging but also to convey heat from the heater 42 to the pump fluid. Fig. 13 illustrates a continuous spiral flange 62 integral with the heater 42 which flange serves to conduct heat to the boiler as well as to prevent surging. For the best results, the liquid should extend abtzlzlt one-half inch above the top of the heater During operation of the apparatus illustrated in Figs. 1, 2, and 3, suitable low vapor pressure organic pump fluid is introduced into the pump so that it fills the lower section of plate l2 to a height above the electric heating unit 42 as indicated by the line 4|. Conduit i6 is connected to a backing pump and flange I4 is connected to the system to be evacuated. When the system has been suitably reduced in pressure by the backing pump, electrical heating unit 42 is put into operation. Vapors rise upwardly through riser tube 44, pass through openings 38 and thence pass as a high-velocity stream from jet nozzle 30. Gases from the system to be evacuated are entrained in this jet of vapors and are forced downward into vapors issuing from jet nozzle 26. Working vapors for jet nozzles 24 and 26 are derived from the outside convolutions of the helical boiler formed by helix 40 and the vapors from this portion of the helix or boiler rise upward and pass out through these jets. Vapors issuing from the various jets eventually push the gases being pumped into conduit l6 from which they are removed by the backing pump. The working vapors are condensed upon air-cooled walls in and flow by gravity downward between wall l0 and collar l8. The return pump fluid thence flows through opening 43 into the outside convolutions of helical boiler 40. The liquid then flows in a helical path through the helical boiler during which passage vaporization takes place and the vapors are supplied to the various jets as mentioned.

As the pump fluid proceeds to flow through the helical boiler from the outside toward the center it is progressively fractionated to remove high vapor presure constituents. Therefore, only the lowest vapor pressure constituents are vaporized in the central portion of the helix and these low vapor pressure constituents supply the low pressure jet nozzle 30. This is a very desirable distribution of vapors and results in optimum pumping conditions.

The flange 48 causes some of the vapors generated near the center of the helical boiler to center and thus increases the countercurrent iractionating effect. Such an arrangement is illustrated in Fig. 4 wherein numerals l5 and 41 designate taps on the electrical heating element 42 whereby the temperature of the element can be varied particularly in the central portion.

During operation of the apparatus shown in Figs. 4, 5, and 6, pump fluid is introduced as previously described, the backing pump is connected to conduit I8, flange I4 is connected to the system to be evacuated, etc. The vapors are generated in the helical boiler which is the same shape as that mentioned in Fig. 1. However, since the helix extends upward these vapors are not immediately released, but are conveyed upward in the various convolutions of the tapered helix and appropriate vapor fractions are released at appropriate jets; i. e., the first convolution of the tapered helix terminates near the high pressure jet 24 so that the highest vapor pressure components derived from thepgtside of the helical boiler are released merit-his high pressure jet. whereas the highest convolution of the helix conveys the vapors from the central portion of the boiler, which contains the lowest vapor pressure components, to the lowest pressure jet 30.

The operation of the apparatus illustrated in Fig. 7 is substantially identical to that of Fig. 4, except that the helical jet nozzle 64 being integral with the tapered helix is positively supplied with appropriate fractions with little or no intermixture of the fractions delivered to the jet nozzles.

Operation of the apparatus illustrated in Figs. 10 and 11 is substantially identical with the operation of the apparatus of Fig. 4, as discussed above. Figs. 10 and 11 serve mainly to illustrate a modified method of constructing a spiral baflle when facilities for cutting spiral grooves are not available.

It will be noted that immersion heaters have been illustrated throughout. However, my inuention is not restricted to such heating means. The pump can be operated equally well with external heating means.

The helical elements which are used to form the helical boiler and tapered helix elements can be easily constructed by merely rolling a suitable wedge-shaped flat piece of sheet metal. The metal need not be of high strength, it being necessary only that it be strong enough to support its own weight without distortion. The use of thin, flexible metal is particularly advantageous, since the helix will then readily assume the shape of the base plate I! in the event that it becomes warped or distorted because of pressure or temperature changes. A particular advantage of the invention is the simplicity of construction as compared with the great diificulty heretofore encountered in rigidly supporting a plurality of tubes so that they would make close contact with the base of the boiler.

What I claim is:

1. A multi-stage vertical fractionating condensation pump adapted to employ a mixed organic fluid and during operation to fractionate the components thereof and deliver the. fractionated vapors to appropriate superimposed jet nozzles so that the low vapor pressure components exert their pumping action toward the low pressure side and the high vapor pressure components toward the high pressure side, said pump being characterized by an elongated and helicalshaped boiler and by means for delivering vapors from diflerent sections of the helical boiler to diilerent appropriate jet nozzles.

2. A multi-stage vertical fractionating condensation pump adapted to employ a mixed organic fluid and during operation to fractionate the components thereof and deliver the fractionated vapors to appropriate superimposed jet nozzles so that the low vapor pressure components exert their pumping action toward the low pressure side and the high vapor pressure components toward the high pressure side, said pump being characterized by an elongated and helicalshaped boiler having relatively little leakage between difierent convolutions of the helix and by means for delivering vapors from difl'erent sec-1 tions of the helical boiler to different appropriate jet nozzles.

3. A .multi-stage vertical fractionating condensation pump adapted to employ a mixed organic fluid and during operation to fractionate the components thereof and deliver the fractionated vapors to appropriate superimposed jet nozzles so that the low vapor pressure components exert their pumping action toward the low pressure side and the high vapor pressure components toward the high pressure side, said pump being characterized by an elongated and helical-shaped boiler having substantially no leakage between convolutions of the helix and by a plurality of vertical 40 tubes communicating at their lower ends with different sections of the helix and at their upper ends with different appropriate jet nozzles.

4. A multi-stage vertical fractionating condensation pump adapted'to employ a mixed organic fluid and during operation to fractionate the components thereof and deliver the fractionated vapors to appropriate superimposed jet nozzles so that the low vapor pressure components exert their pumping action toward the low pressure side and the high vapor pressure components toward the high pressure side, said pump being characterized by an elongated helical-shaped boiler and by means comprising a tapered helix for delivering vapors from diiferent sections of the helical boiler to different appropriate jet nozzles.

5. A multi-stage vertical fractionating condensation pump adapted to employ a mixed organic fluid and during operation to fractionate the components thereof and deliver the fractionated vapors to appropriate superimposed'jet nozzles so that the low vapor pressure components exert their pumping action toward the low pressure side and the high vapor pressure components toward the high pressure side, said pump being characterized by an elongated helical-shaped boiler and by means in the form of a tapered helix constituting an extension of the helical-shaped boiler walls for delivering vapors from different sections of the helical boiler to, different appropriate jet nozzles.

6. A multi-stage vertical fractionating condensation pump adapted to employ a mixed organic fluid and during operation to fractionate the components thereof and deliver the fractionated vapors to appropriate superimposed jet nozzles so and the high vapor pressure components toward the high pressure side, said pump being characterized by a tapered helix positioned within a tapered let chimney which helix rests upon the inside base of the pump and divides it into a helicalshaped boiler with substantially no communication between the convolutions of the helical shaped boiler and which extends upward that the upper tapered convolutions oi the tapered helix terminate at or near the portions of the wall of Jet chimney upon which the jet nozzle are positioned. I

'7. A multi-stage vertical fractionating condensation pump adapted to employ a mixed organic fluid and during operation to fractionate the components thereof and deliver the fractionated vapors to appropriate superimposed Jet nozzles so that the low vapor pressure components exert their pumping action toward the low pressure side and the high vapor pressure components toward the high pressure side, said pump being characterized by a removable helical-shaped partition having relatively little leakage between different convolutions, which helix-rests in the boiler and divides it into an elongated helix and by means for delivering vapors from different sections of the helical boiler to different appropriate jet nozzles.

8. A multi-stage vertical fractionating condensation pump adapted to employ a mixed organic fluid and during operation to i'ractionate the components thereof and deliver the fractionated vapors to appropriate superimposed iet nozzles so that the low vapor pressure components exert their pumping action toward the low pressure side and the high vapor pressure components toward the high pressure side, said pump being characterized by an elongated helical-shaped boiler, by a central riser tube with flange communicating at its lower end with the central portion 01' the helical boiler and at its upper end with the high vacuum Jet, and by means for supplying an excess of heat to the central portion of the helical boiler.

9. A multi-stage vertical fractionating condensation pump adapted to employ a mixed organic fluid and during operation to iractionate the components thereof and deliver the fractionated vapors to appropriate superimposed jet nozzles so that the low vapor pressure components exert their pumping action toward the low pressure side and the high vapor pressure components toward the high pressure side, said pump being characterized by an elongated helical-shaped boiler by means comprising a taperedhelix for delivering vapors from difierent sections of the helical boiler to diflerent appropriate jet nozzles and by means for supplying an excess 01' heat to the central portiOn of the helical boiler.

KENNETH C. D. HICKMAN.

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