US2296640A

US2296640A - Rotary apparatus for pumping volatile liquids

Info

Publication number: US2296640A
Application number: US345309A
Authority: US
Inventors: Odd A Hansen
Original assignee: Linde Air Products Co
Current assignee: Linde Air Products Co
Priority date: 1940-07-13
Filing date: 1940-07-13
Publication date: 1942-09-22
Anticipated expiration: 1959-09-22

Description

9 1942- o. A. HANSEN 2,296,640

ROTARY APPARATUS FOR PUMPING VOLATILE LIQUID Filed July 15, 1949 3 Sheets-Sheet 1 INVENTOR W y a a/mxm/ dZm finwfiif P 1942- 0. A. HANSEN ROTARY APPARATUS FOR PUMPING VOLATILE LIQUID Filed July 13, 1940 s Sheets-Sheet 2 62. k a/wn,

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ROTARY- APPAfi KTUS FOR-PUMPING VOLATILE LIQUID Filed July 13 1940 3 Sheets-Sheet 3 Ill! G254 EXT Jim Patented Sept. 22, 1942 ROTARY APPARATUS FOR PUIWPING VBLATILE LIQUIDS Odd Hansen, Kenmore, N. Y... assignor to The Liude Air Products Company, New York, N. Y.,

a corporation oi. Ohio Application July 13, 1940, Serial No. 345,309

d Claims.

This invention relates to rotary apparatus for conveying or pumping a volatile liquid, and particularly to such apparatus adapted for. pumping -a liquefied gas having a boiling point materially below 273 K. at atmospheric pressure, for example, liquid oxygen.

The invention has for its object generally the provision of an improved arrangement and combination of elements for mounting the rotary element in pumps of the character indicated.

More specifically, the invention has for its object the provision of improved bearings for the rotary element of pumps of the character indicated, such bearings being self-lubricating and devoid of hydrocarbonlubricants and the like which may react with the liquid being pumped.

Another object is to provide an improved arrangement of the rotor element whereby it is relatively distant from the point where power is applied and hence little heat is conductedto the working parts.

Still another object is to provide a bearing construction in rotary pumps of the character indicated which employs at least one bearing completely enclosed from the outer atmosphere and which is self-lubricating and inert to the liquid being pumped.

Another object is to provide a pump of the character indicated with an arrangement utilizing bonded graphite as the bearing material.

Other objects of the invention will in part be obvious and will in part appear hereinafter.-

The invention accordingly comprises the features of construction, combination of elements, and arrangement of parts, which will be exemplified in the construction hereinafter set. forth, and the scope of the invention-will be indicated in the claims.

For a fuller understanding of the nature and objects of the invention reference should be had to the following detailed description taken in connection with the accompanying drawings, in which:

Fig. 1 is an elevational view showing a pump of the turbine type arranged in accordance with the invention;

larly to-Fig. 1, the pump is indicated as having a.

base ill on which is mounted a casing H having an extension 12 in which rotates a shaft H3. The

45 of the channel to provide relatively narrow clear- 50 channel shown in Fig. 2 at H6. A similar outlet 55 some point in the channel H! to. the exterior.

60 of the flange I20 which is welded or otherwise shaft is shown as protruding from the end of the extension i2 and journaled at M in a manner more fully explained below.

The end of the extension l2 through which the shaft l3 protrudes is provided with a suitable shaft seal or gland. That shown in the drawings by way of example is depicted as comprising a packing is interposed between follower sleeves l6 and ll. The inner sleeve 16 is. shown as pinned in place in extension l2, while the outer sleeve I1. is removable and pressed into place by means of a nut or cap l8 which makes screw-threaded engagement with the outer end of the extensionv H. A strut I9 is also preferably interposed between extension 12 and base ID for the purpose of insuring a more rigid alignment of the shaft with the journal at M.

The journal mounting here provided at ll is disposed on the base ID in a manner independent of the pump casing in order thereby to be in poor heat conducting relation therewith. To this end. it is shown as mounted on a block 20 which is secured on base It. Block 20 in turn supports a housing 26, the height of which may be adjusted by the insertion of shims in order to obtain the desired alignment with shaft J3. The bearing element for shaft l3, which is preferably one of the so-called antiiriction" variety, is depicted at 22 mounted in the housing 2 I Details of the casing II are shown in Fig. 3.

Here, it is seen to consist of interfitting members Nil and HI. When in assembled relation, these members provide a substantially annular-chamnel H2 which is arranged to enclose the outer or 5 working margin of an impeller or rotor element H3 which is carried by and secured to the shaft IS. The channel H2 serves hence as the pumping channel and is formed to clear the working parts of the impellerilS by proper clearances,

40 that for the margin being relatively large in order that the liquid impelled may advance therethrough in a plurality of helical paths. The channel H2 is seen to have a nearly rectangular cross-section and is hence restricted at the base ances at the sides of the impeller. The pumping channel thus provided is circumferentially disof the Such opening is shown in Figs. 1 and 2 as being. normally closed by a plug designated H9. The extension I! is secured to the casing member fl'l in any suitable manner, for example, by means permanentlysecured to the extension I 2, the flange being detachably secured to the casing by suitable means, for example by bolts Iii.

Details of the impeller -I I3 are shown in Figs. 4 and 5, where it is seen that the working margin of the impeller comprises a plurality of straight-bladed teeth II5 which are readily formed by milling machines and the like, cutting grooves, as shown at H4, which taper from the base of the working margin of the impeller, such taper providing a narrow central edge H5 which separates the liquid being pumped into the two streams forming the helices, above referred to. The central or hub portion of the impeller is shown at I23 keyed to the shaft I3 and has thrust collars I24 and I25 disposed at the sides. One or more openings I 26 are also preferably provided in order to equalize the pressures on the two sides of the impellers in the central chamber of the casing in which the hub runs.

In order conveniently to position the impeller and its thrust collars on the shaft l3, one end of the same is advantageously enlarged as shown at I30. Such enlargement provides a shoulder against which the thrust collar I25 is seated. The collar I24 works against a bearing I34 held in the cupped-out portion of a disk I33 that has an inner reduced portion or nipple in screwthreaded engagement with a correspondingly threaded central, recess in the casing member H3. A bearing bushing I35 is also provided for the enlargement I30. The bearing bushing may have any convenient shape, for example, cylindrical, or provided with a shoulder as shown; such bushing is advantageously supported in a removable sleeve I36 which has a closing plate I31 over the outer end secured in place in any suitable manner, for example, by bolts I38. By this arrangement shims may be introduced between the thrust collars and the impeller hub in orderto achieve precise centering of the impeller in the casing.

The bearing member I35, by reason of its proximity to the impeller H3, is seen to sustain the major portion of the load. The bearing 22, in consequence, carries a relatively small portion of the load. To achieve better distribution of this major portion of the load, the shaft end I30 has been enlarged and the bearing member I35, which is thus the main bearing, is correspondingly enlarged. This bearing, by the arrangement employed, is not only totally enclosed but the inner end serves also as a thrust bearing.

In the present invention, both bearing members I34 and I35 serve without the application of any lubricant from the outside. While' these members may have substantially any convenient shape, they are made of a solid self-lubrieating material which is also inert to the liquid being pumped. A bonded graphite is a suitable material of this character where liquid oxygen is being pumped, 'and is at present preferred. Such material is not only inert to liquid oxygen and self-lubricating, but, in addition, has ability to withstand the impression of reasonable load with a satisfactory margin of safety.

The self-lubricating bearing here employed in accordance with the invention is seen to be necessarily located inside the pump casing in order to achieve proper operating conditions. This is readily seen if it be assumed that instead of usin an internal bearing, two external bearings of the type shown at 22 be employed, as is frequently done in this class of apparatus. In such an arrangement the shaft would be extended through both sides of the casing, and will be twice as long as the shaft here proposed, in order to avoid the conduction of heat to the impeller. Such construction involves the use of two packings and two extension tubes. For loads of noderate- 1y high values, forces are applied to the shaft in a radial direction as a result of the reaction of the liquid on the impeller, which result in excessive deflection of the shaft at the center. This resulting deflection would cause a shifting of the impellers position in the channel, with consequent loss of pumping efllciency or hydraulic performance. By avoiding the use of excessively long shafts, by the use of an internal hearing as here proposed, substantially all deflection of the shaft is avoided with consequent maintenance of the position of the impeller, which makes possible the employment of smaller clearances in the pump. Where the volatile liquid being pumped has aboiling point temperature at atmospheric pressure materially below 273 K. and is chemically active, such as liquid oxygen, the bearing is not only disposed within the pump casing but constructed in a manner avoiding the use of lubricants that otherwise could be applied from the outside. Hence only self-lubricating' bearings, as here proposed, may be used. The relatively low temperatures at which the apparatus of the present invention is to operate is seen also to cause excessive, contraction and expansion of the parts, so that even if it were otherwise feasible to use two external bearings, the resulting contraction of the parts would cause such displacement that internal rubbing between the casing and the impeller would result. By the arrangement of the present invention, such disadvantages are avoided.

While the embodiment of the invention above disclosed has been described as of the turbine type and employs but a single impeller wheel, namely, that shown at H3, it will be readily understood that the present invention is not confined to turbine type pumps but is applicable to rotary pumping apparatus in general, i. e., to centrifugal pumps, turbine pumps, gear pumps, etc. The invention is also applicable to multistage pumps, i. e., to pumps in which the liquid pumping element comprises a plurality of wheels arranged to pump the liquid in stages, each stage impartingp. desired portion of the ultimate delivery pressure. In such pumps, the pumping channels for the several stages are of course arranged to discharge successively each into the next, 1. e., in series. Such series connected channels may be collectively referred to as the pumping channel. In any such embodiment, the invention employs a solid type self-lubricating bearf the casing. The embodiment of the invention il-' lustrated in Figs. 1 to 3 is accordingly to be considered as merely exemplary and in no way excluding the application of the invention from rotary apparatus of types other than that here illustrated.

In operation, the pump of the present invention is driven by the coupling of shaft I3 to a suitable source of mechanical power, such as an electric motor. The pump is started by starting the motor and opening priming connections, the showing of which is here omitted in the interests of cleamess of illustration in the draw- 2,296,6QU 1 f;

ing; such however, are shown in my copending application, Serial No. 345,308, filed July 13, 1940. The shaft l3, which carries the impeller H3, is

seen to run, when the pump is in operation, in

tus, the invention is not necessarily confined to any such apparatus, the invention being obviously applicable to apparatus wherever there are moving parts that are subject to relatively low temperatures, such as those materially below 273 K., and where the normal expansion and contraction of the parts would result in such movement or displacement of the parts as to interfere with the normal operating conditions when the apparatus has been cooled to the relatively low operating temperatures here contemplated.

The pump of the present invention is particularly adapted for use as a fore pump or firststage pump in the apparatus disclosed in the U. S. patent to Thompson, No. 1,930,731, the general role and operation of the present type of pump being disclosed in my copending application, Serial No. 340,848, filed June 15, 1940, issuing August 11, 1942 as Patent No. 2,292,375. Other features of construction disclosed herein but not claimed are set forth in my copending application, Serial No. 345,308, filed July 13, 1940.

Since certain changes may be made in the above construction and different embodiments of the invention could be made without departing from the scope thereof, it is intended that all matter contained in the above description or shown in the accompanying drawings shall be interpreted as illustrative and not in a limiting sense.

Having described my invention, what I claim as new and desire to secure by Letters Patent is:

1. In rotary type pumps and the like adapted for pumping a volatile liquid having a boiling point temperature at atmospheric pressure materially below 273 K., the combination with a casing having a liquid inlet, a liquid outlet and a circumferentially disposed pumping channel therebetween, of a shaft rotativeley disposed in said casing having an enlarged and and provided with a rotary pumping element adjacent said end and cooperatively disposed with respect to said pumping channel, means on said shaft in said casing including self-lubricating thrust bearings engaged between each rotor side and the casing portion adjacent thereto for positioning said rotor relatively to the casing and maintaining an equal thrust on each side of said rotor, and a bearing sleeve of self-lubricating material in said casing for said enlarged shaft end, said self-lubricating material comprising bonded graphite and said sleeve cooperating with the thrust bearing adjacent thereto.

2. A rotary type pump adapted for pumping a volatile liquid having a boiling point temperature at atmospheric pressure materially below 273 K., having in combination a casing, a liquid inlet and a liquid outlet therefor, a circumferen tial pumping channel extending from said inlet to said outlet around a major portion of the circumference, a shaft rotatably disposed in said casing, a rotary pumping element mounted thereon adapted to operate in said channel and having a relatively small clearance between it and the casing in the region thereof between its hub and said pumping channel, said shaft having an inner end terminating in said casing with said pumping element secured at its hub for rotation by the shaft and positioned on the shaft closely adjacent said end, a bearing in said casing for supporting said inner shaft end, said end and bearing being totally enclosed within the casing, and thrust-bearing means in said casing including self-lubricating thrust bearings about said shaft engaged between each pumping element hub side and the casing portion adjacent thereto for positioning said pumping element relatively to said casing to maintain said clearance substantially constant.-

3. In rotary type pumps and the like adapted for pumping a volatile liquid having a boiling point temperature at atmospheric pressure materially below 273 K., the combination of a casing, a liquid inlet and a liquid outlet therefor, a circumferentially disposed pumping channel extending from said inlet to said outlet, a shaft rotatably disposed in said casing, a rotary pumping element mounted thereon adapted to operate in said channel and having a relatively small clearance between it and the casing in the region thereof between its hub and said pumping channel, said shaft having an inner end terminating in said casing with said pumping element secured to the shaft closely adjacent said end, a bearing sleeve of solid permanently selflubricating material in said casing for supporting said inner shaft end, said shaft end and bearing sleeve being totally enclosed within the casing, means about said shaft in said casing including self-lubricating thrust bearings engaged between each pumping element hub side and the casing portion adjacent thereto for positioning said pumping element relatively to said casing to maintain saidclearance substantially constant, and a tubular member extending from said casing toward the other end of said shaft and having a shaft seal, and an outer bearing for said shaft beyond said tubular member remote from and independent of the main pump casing.

4. 1n rotary type pumps and the like, for pumping a volatile liquid having a boiling point at atmospheric pressure materially below 273 K., the combination with a casing having a liquid inlet, a liquid outlet, and a circumferentially disposed channel, of a shaft rotatively disposed in said casing and provided with a rotary pumping element or rotor cooperatively disposed with respect to said inlet, said outlet, and said pumping channel, said casing having portions on each side of said rotor axially spaced from said rotor, and means about said shaft in said casing including self-lubricating thrust bearings engaged between each rotor side and the said casing portion adjacent thereto for positioning said rotor relatively to said 'casing and maintaining a substantially equal thrust on each side of said rotor irrespective of the effects of temperature changes.

ODD A. HANSEN.