US3182897A

US3182897A - Turbine driven centrifugal compressor unit

Info

Publication number: US3182897A
Application number: US272660A
Authority: US
Inventors: William E Trumpler
Original assignee: Dresser Industries Inc
Current assignee: Dresser Industries Inc
Priority date: 1963-04-12
Filing date: 1963-04-12
Publication date: 1965-05-11
Anticipated expiration: 1982-05-11

Description

y 1965 w. E. TRUMPLER 3,132,897

TURBINE DRIVEN CENTRIFUGAL COMPRESSOR UNIT I Filed April 12, 1963 5 Sheets-Sheet 1 10 INVENTOR.

WIgI JAM E. TRUMPLER ATTORNEYS May 11, 1965 w. E. TRUMPLER TURBINE DRIVEN CENTRIFUGAL COMPRESSOR UNIT Filed April 12, 1963 s Sheets-Sheet 2 May 11, 1965 w. E- TRUMPLER 3,132,897

TURBINE DRIVEN CENTRIFUGAL COMPRESSOR UNIT Filed April 12, 1963 3 Sheets-Sheet I5 INVENTOR. WILLIAM E. TRUMPLER Q MJM ATTORNEYS United States Patent 3,182,897 TURBINE DRIVEN CENTRIFUGAL COMPRESSOR UNIT William E. Trumpler, ()lean, N.Y., assignor to Dresser industries, Inc, Dallas, Tex., a corporation of Delaware.

Filed Apr. 12, 1963, Ser. No. 272,660

9 Claims. (Cl. 230-116) This invention relates to improvements in a turbine driven centrifugal compressor unit, and more particularly to a hermetically sealed high speed turbine driven high pressure centrifugal compressor unit.

A primary purpose of the present invention is to provide apparatus which will. compress a gas which is already at a high pressure such as 20,000 pounds per square inch (hereinafter referred to as p.s.i.) to a still higher pressure such as 40,000 psi.

When handling gas at such high pressure levels in apparatus having relatively movable parts, it is impossible to seal against the leakage of gas past such parts. Another object of the present. invention is therefore to provide such apparatus which is hermetically sealed with respect to the environmental medium surrounding the apparatus notwithstanding unpreventable internal gas leakage.

In the handling of certain gases such "as ethylene, it is undesirable to lubricate'relativelyrotating parts such as bearings with conventional lubricating oils or greases inasmuch as such lubricant will contaminate the gas. Effective protection against frictional effects between the relatively rotating parts is still required, however, because of the high rotative speed of the rotor in the inventive apparatus, which speed typically may be 70,000 r.p.m. Accordingly, another object of the present invention is to provide. such apparatus which avoids using conventional liquid lubricants and employs the gas being handled.

to effectively lubricate 'the relatively'rotating parts.

Another object is toprovide such apparatus in which the gas lubricated bearings are supplied with the inevitable internal gas leakage aforementioned.

Another object is to provide such apparatus which is so constructed as to eliminate any end thrust by the rotating elements.

Another object is to provide such apparatus which handles inlet gas at a high pressure and compresses it to' even higher discharge pressure in an efiici'ent manner.

Other objects and advantages of the present invention will be apparent fromthe following detailed description of a preferred embodiment shown in. the accompanying drawings in which:

FIG. 1 is an end elevational view high speed turbine driven high pressure centrifugal compressor unit constructed in accordance with the principles of the present invention. 7 i

FIG. 2 isa vertical central sectionalview thereof taken on line 22 of FIG. 1, certain internal parts being shown in elevation. i a 7 FIG. 3 is an enlarged fragmentary vertic'al central sectionalview thereof, generally similar to FIG. 2.

FIG. 4 is a fragmentary vertical transverse sectional viewthereof taken on line 4-4 of FIG. 3.

FIG. S is a fragmentary vertical transverse sectional viewthereof taken on line 55 of FIG. 3.. a

FIG. 6 is a fragmentary vertical transverse sectional view thereof taken on line 66 of FIG. 3.

The turbine jdriven centrifugal compressor unit is shown as comprising a housing including a cylindrical barrelv section 10 having transverse flat end surfaces to which end heads 11 and 12 are removably secured. Each ofthe end heads 11 and 12 is shown as provided with axially extending holes 13 through which the shanks of machine screws 14 extend. The ends of these screw shanks are externally threaded and received in internally of a hermetically r 3,182,897 Patented May 11, 1965 threaded recesses 15 provided axially in each end of the barrel section 10. A plurality of such screws 14 arranged at circumferentially uniformly spaced intervals, as shown in FIG. 1, are employed for securing each end head to the barrel section.

Rotatably arranged completely within the housing is a shaft represented generally by the numeral 16. This shaft is symmetrically formed about longitudinal and transverse centerlines and is shown as including an enlarged, generally cylindrical central section 18. Similar

cylindrical sections

19 and 20 of slightly reduced diameter are arranged on opposite axial sides of the central shaft section 18. Similar further slightly reduced

cylindrical sections

21 and 22 are arranged axially outwardly of the

cylindrical sections

19 and 20, respectively. The shaft also includes similar

cylindrical sections

23 and 24 of still further slightlyreduced diameter arranged axially outwardly of the

cylindrical sections

21 and 22, respectively. In addition, similar generally cylindrical sections 25 and 26 of even further reduced diameter are arranged axially outwardly of the last mentioned

centrifugal sections

23 and 24, respectively. The extremiites of the shaft are formed as reduced externally threaded stems 27 and 28 which extend axially outwardly from the outer ends of the sections 25 and 26, respectively.

Centrally arranged on the shaft 16 so as to rotate therewith is an impeller indicated generally at 29. This impeller includes a hub portion 30 and an integral central radially extending annular disk-like portion 31. The hub portion 30 is shown as formed with an axially extending through hole 32 which is so dimensioned as to have a press fit with the central shaft section 18 whereby the impeller and shaft rotate together. Any other suitable mode of non-rotatively fastening the impeller 29 to the shaft 16 as by keying or splining may be employed but it should preferably be diametrically symmetrical so as to maintain the dynamic balance of the shaft.

The central shaft section18 is shown as provided with two pairs of diametrically opposed, axially extending uniformly circumferentially spaced through grooves 33. These grooves 33 establish communication between'opposite axial sides of the central shaft portion 18 for a purpose explained more fully infra.

l The annular radial portion 31 of the impeller 29 is shown as provided with symmetrical blading on opposite axially facing sides thereof. As shown in FIGS. 3 and 5, each side of the impeller is provided with a series-of circumferentially and uniformly spaced,radially; extending blades 34 which are preferably formed integrally with the radial impeller portion 31 and these blades 34 are shown as integrally joining at their outer ends to provide transverse paddles 35. 'The hub portion 30 and radial portion 31 of the impeller are shown joined by a smoothly contoured fillet as indicated at 36, the blades 34 beginning at their radially inner ends at about the radially outward terminations of such fillets36.

Surrounding the periphery of the impeller 29 and arranged symmetrically with respect thereto is a diffuser ring 38. This ring 38 is shown as supported on shoulders 39 of a pair of stationary housing inner rings 40 and 41. These rings 40 and 41 have anputer diameter corresponding to that of the diffuser ring 38' and are slidably end's'urfaces of the rings 40 and 41 are spaced apart to' provide with respect to the interposed impel1er.29 a

, chamber 43 associated with the ring 40 and a similar therebet-ween. The rings 40 and 41 have fiat radially chamber 44 associated with the ring 41. The radially inner portion of the rings 40 and 41 are provided with a rounded contour as indicated at 45 which opposes the fillets 36 on the impeller so-as to leave a passage 46 extending outer axially facing surfaces 48 which severally connect through a rounded contour indicated at 47 with the previously mentioned rounded contour 45.

Axially spaced outwardly of the housing inner rings 40 and 41 are stationary housing intermediate rings or diaphragms 49 and 50, respectively. Arranged axially outwardly of these rings 49 and 50 are stationary housing

outer rings

51 and 52, respectively. The rings 49-52 have an outside diameter corresponding to that of the barrel bore 42 so that these rings may be slid in and out of the housing barrel section 10.

The opposing axially facing sides of the housing intermediate rings 49 and 50 follow the shape generally of the corresponding opposing surfaces 47 of the inner housing rings 40 and 41 so as to provide passages 53 therebetween. In order to maintain such spaced relation, each of the rings 49 and 50 is formed preferably integrally with streamlined radially extending lugs or vanes 54, as best shown in FIG. 6. These lugs 54 are shown as circumferentially uniformly spaced to leave passages 55 therebetween which communicate with the passages 53. The outer ends of these passages 55 communicate with an annular recess. One such recess 56 is formed between the rings 40 and 49 and a similar recess 58 is formed between the rings 41 and 50. The

recesses

56 and 58 are severally in communication with radial passages 59 and 60, respectively, which extend radially through the housing barrel section 10.

Intermediate these radial passages 59 and 60, the housing barrel section is also shown as provided with another radially extending passage 61. The inner end of this passage communicates with an annular recess 62 formed on the internal surface ofthe barrel section 10. i This recess 62 jointly with the peripheral surface of the diffuser ring 38 provides a collecting chamber. This chamber communicates with the periphery of the impeller 29 through a series of circumferentially spaced, generally tangentially extending slots 63, as best shown in FIG. 5.

The communicating

passages

59, 56, 55, 53 and 46 establish an inlet conduit to the blading on the left side of the impeller 29 as viewed in FIG. 3. The communicating

passages

60, 58, 55, 53 and 46 provide a separate inlet conduit leading tothe blading on the right side of the impeller 29 as viewed in FIG. 3. The communicating

passages

61, 62 and 63 provide an outlet or discharge passage for gas compressed by the impeller 29.

Referring to FIGS. 1 and 2, means are shown for attaching supply and discharge lines to the various passages 59-61 in the housing barrel section 10. For this purpose, the barrel section is shown as formed centrally with a fiat surface 64 against which seats the flat surface of an attaching flange indicated generally at 65. This flange 65 is secured to the housing barrel section by several machine screws 66, four such screws being shown. Although not illustrated but readily understood, each of these screws 66 has a shank threadedly received in a recess formed in the barrel section 10. The flange 55 is shown as integrally formed with

inlet nipples

68 and 69 which severally and respectively aline with the inlet passages 59 and 60 in the barrel section. The flange 65 is also shown as provided with a nipple 70 which alines and communicates with the discharge passages 61 in the barrel section.

Preferably, as 'shown, 'a pair of freely rotatable plates or covers 71 and 72 are arranged on opposite axial sides of and coaxially with the impeller 29. The plate 71 is shown as arranged in the chamber 43 on the left hand side of the impeller 29, as viewed in FIG. 3, and the other plate 72 is arranged on the right hand side of this impeller in the chamber 44. Each of these plates 71 and 72 has a flat generally radial surface which is closely spaced to the land surfaces of the blading 34. The radially inner end of each plate 71 and 72 is shown as formed with an axially outwardly extending hub or annular flange portion 73 which surrounds and rotatably engages a coaxial sleeve portion 74 of a first bearing ring 75 associated with the plate 71 and a similar sleeve portion of a second bearing ring 76 associated with the other plate 72. Each of the bearing rings 75 and 76 has a radially outwardly extending annular flange portion 78. These portions 78 oppose the end faces of the hubs 73 of the plates 71 and 72, respectively, and absorb any end thrust exerted by these plates. The bearing rings 75 and 76 are supported on suitable shoulders formed on the housing inner rings 40 and 41, respectively. Referring to FIG. 3, it will be noted that the inner and opposing ends of the sleeve portions 74 of these bearing rings 75 and 76 are rounded in contour to follow generally the configuration of the opposing impeller fillets 36 and to form coterminous extensions of the respective rounded surfaces 45 on the housing rings 40 and 41.

Preferably the bearing rings 75 and 76 are composed of a self-lubricating material which will not require conventional oil or grease lubrication between the relatively rotating surfaces of these bearing rings and the freely rotatable plates 71 and 72. The preferred material of which the bearing rings 75 and 76 is composed comprises long chain fiuorinated polymers of ethylene such as tetrafluoroethylene which is known in the trade as Teflon. Such a material has dry, self-lubricating properties.

The outer or peripheral edges of the plates 71 and 72 are severally shown as having radially outwardly extending offset annular flange portions 79 which severally overlap radially inwardly extending annular flange portions 80 integrally formed on the dilfuser ring 38 on opposite sides of the diffuser slots 63. Thus the axially spaced annular diffuser ring flanges 80 form a gas collee-ting groove 81 which communicates with the groove 62 via the several slots 63 which extend through the diffuser ring 38 at circumferentially spaced intervals.

Gas type sleeve bearings 82 and 83 are provided for ournalling the shaft 16 inwardly of each thereof so as to leave overhung shaft end portions. The bearing 82 is shown as surrounding the cylindrical shaft portion 21. The other bearing 83 is shown as surrounding the cyl1ndrical shaft portion 22. The bearings 82 and 83 are shown' as supported on tubular members 84 and 85, respectively, in turn supported on the housing outer rings 51 and 52, respectively.

Means are shown for supplying leakage gas from the inlets for the impeller 29 to the opposing closely spaced peripheral surfaces between the bearing 82 and shaft section 21 and between the bearing 83 and shaft section 22. For this purpose, radially inner portions of the opposing axially facing surfaces of the housing rings 49 and 51, including the exposed end face of the tubular member 84, are spaced apart to provide a chamber 86. A similar chamber 88 is provided between the opposing and spaced surface portions of the housing rings 50 and 52, including the exposed end face of the annular member 85. It will be noted that the lugs 54 on the housing intermediate rings 49 and 50 keep the radially inner and opposing end surface portions of these rings axially spaced from the opposing end surfaces of the hub portion 30 of the impeller 29 so as to leave an annular clearance 89 to the left of the impeller, as viewed in FIG. 3, and a similar annular clearance 90 on the right side of this impeller. Intermediate the clearance 89 and the chamber 86, housing ring 49 is shown as internally formed with labyrinth seal means 91. The ridges of such labyrinth seal means 91 are closely spaced from the opposing periphery of the cylindrical shaft section 19. A similar labyrinth seal means 92 surrounds the cylindrical shaft section 20 intermediate the clearance 90 and chamber 88.

Each of the sleeve bearings 82 and 83 is shown as provided withan annular groove 93 in its outer periphery. Communicating with this groove 93 in each bearing is a series of circumferentially spaced radial holes 94, four such holes being typically'provided for each sleeve bearing. Also, each annular groove communicates with several circumferentially spaced axially extending grooves 95. In the case of the bearing 82, the grooves 95 open to the annular chamber 86. The grooves 95 in the bearing 83 open to the annular chamber 88.

In this manner, inlet gas under a high pressure can flow through the clearances 89 and 99 past the labyrinth seal means 91 and 92 into the

chambers

86 and 88, respectively from whence this gas can communicate through the connected passages 93-95 with the slight annular clearance that exists between the opposing peripheral surfaces of the bearings and shaft. The inner ends of the radial passages 94 and the bearings serve as orifices which are variably closed depending upon the relative radial position of the opposing shaft periphery. Gas escaping through the radial passages 94 will float the shaft on an annular film of gas to provide a dry journalling of the shaft which will not require lubrication by conventional liquid type lubricating materials such as oil or grease but which will be lubricated by the gas film so provided.

Provision is made for conducting any gas leaking outwardly past the bearings 82 and 83 to the inlets to a pair of similar turbine wheels 96 and 98. The turbine wheels 96 and 98 are shown as suitably non-rotatably mounted on the shaft sections 25 and 26, respectively. For this purpose the hub of the turbine wheel has an axially extending through hole 97 which has a press fit with the corresponding cylindrical shaft sections 25 or 26. Any other suitable fastening such as keying or splining, preferably diametrically symmetrical, may be employed. The turbine wheel 96 is shown as held against the shoulder formed by the

shaft sections

23 and 25 by a nut 99 screwed onto the threaded stem 27. A similar nut 100 is screwed onto the stem 28 at the other end of the shaft to hold the other turbine wheel 98 against the shoulder formed by the shaft sections 24 and 26.

The turbine wheels 96 and 98 are shown as being of the radially inward flow type. Thus each such turbine wheel is shown as comprising a disk portion 101 from one side of which vanes 102 extend. The vanes 102, best shown in FIG. 4, are arranged on the axially outer surface of the disk portions 101 so that the turbine wheels 96 and 98 effectively face in opposite axial directions or back to back.

A suitable interlocking seal means indicated at 103 is provided between the opposing end surfaces of the turbine wheel hubs and the cylindrical members 34 and 85 supported on the housing outer rings 51 and 52, respectively. These cylindrical members 84 and 85 are shown as being internally provided with labyrinth seal means 104 and 105, respectively, to hold back leakage axially outwardly past the bearings 82 and 83. However, some leakage will occur.

In the case of the left end of the shaft as shown in FIG. 3, such leakage is collected in an annular groove 106 formed on the internal surface of the member 84 adjacent its outer end. A series of radial holes 103 through this member 84 severally communicate at their inner ends with the groove 106 and at their outer ends with an annular groove 109 provided in the inner peripheral surface of the housing outer ring 51. A series of radial passages 110 in this ring 51 severally communi- 6 cate with an annular inlet chamber 119 for the turbine wheel 98.

Partially covering the axially facing outer surfaces of the turbine wheels 96 and 98 are

stationary cover members

120 and 121, respectively. Each of these members has a portion which opposes the vanes 102 on the corresponding turbine wheel and is closely spaced for the land surfaces of such vanes. This close spacing is maintained by a series of circumferentially uniformly spaced lugs 122 arranged around the periphery of the corresponding turbine wheel and preferably formed integrally with the

respective cover members

120 and 121. In the case of the member 120, its lugs 122 abut against the opposing outer end face of the housing outer ring 51. In the case of the other member 121, its lugs 122 abut against the opposing outer end face of the other housing outer ring 52. The lugs 122 are streamlined in contour and are inclined with respect to the radius of the corresponding turbine wheel to provide inlet vanes, as best shown in FIG. 4. The spacers 123 between adjacent lugs 122 communicate with the corresponding

turbine inlet chamber

112 or 119. The chamber 112 is formed jointly by the housing outer ring 51, turbine cover 120 and end head 11. The chamber 119 is formed jointly by the housing outer ring 52, turbine cover 121 and end head 12.

Means are provided for supplying pressurized working gas to the

turbine inlet chambers

112 and 119 for driving the turbines 96 and 98. As shown in FIG. 2, the end' head 11 is provided with a pair of diametrically opposed axial through passages 124 which at their inner ends severally communicate with the annular chamber 112. The outer end of each passage 124 is covered by an attaching flange 125 having a nipple 126 which forms an extension for the corresponding passage 124. Each of these flanges 125 is shown in FIG. 1 as secured to the end head 11 by a pair of machine screws 128, the shanks of which are threadedly received in recesses provided in the end head 11. a

In similar fashion, the other end head 12 is provided with a pair of diametrically opposed axially extending through passages 129 each covered by an attaching flange 130 having a nipple 13 1. The attaching flanges 130 are secured to the end head 12 in a similar manner to that described for the attaching flanges 125.

Gas flows from the

annular inlet chambers

112 and 119 through the respective passages 123 and over the blades 102 on the respective turbine wheels 96 and 98 to rotat-ively drive these wheels. The spent Working gas discharged by the turbine wheel 96 flows through a central axially extending hole 132 provided in the turbine cover 120. This hole 132 is in alinement with an axially extending through hole 133 provided in the end head 11. The outer end of this passage 133 is covered by an attaching flange 134 having a nipple 135 as shown in FIG. 2. The attaching flange 134 is secured to the end head 11 in any suitable manner as by machine screws 136, four such screws being shown in FIG. 1. The shanks of these screws 136 are threaded into recesses provided in the end head 11.

The other end head 12 has a central axially extending through pasage 138 which at its inner end al-ines with a central axially extending hole 139 provided in the turbine cover 121. The other end of the passage 138 is covered by an attaching flange 140 having a nipple 141 and secured to the end head 12 by machine screws (not shown) in a manner similar to that described for the attaching flange 134.

Operation While the turbine driven centrifugal compressor unit may handle any desired gas, its opera-ion will be described in connection with the handling of ethylene gas. It is assir-med that this unit is the last or topping stage of an array of compression apparatus. It is further assumed that ethylene gas under a pressure of say 20,000 p.s.i. is supplied to the inlet nipples 68 and 69.

It is further assumed that ethylene gas at a lower pressure, say 2500 p.s.i. and derived from a lower stage of the aforementioned compression apparatus is utilized as a working fluid for the turbines 96 and 98 and is therefore supplied to the

nipples

126 and 131. This working fluid for the turbines enters the annular

turbine inlet chambers

112, 119 from whence it flows through the spaces 123, being directed therethrough by the inclined guide vanes 122 into impingement with the blades 102 on the turbine wheels 96 and 98. Such impingement causes the turbine wheels 96 and 98 to rotate in the same direction and thereby rotate the shaft 16 to which these turbine wheels are fast, also in the same direction. The spent turbine working gas is discharged through the

outlet passages

133 and 138 to the associated

discharge nipples

135 and 141, respectively. Typically, turbine exhaust gas may have a pressure of 1,000 p.s.i. and is returned to a suitable point in the reciprocating compressor system where the pressure is at the exhaust level of the drive turbine.

Adverting to the compressor part of the unit, the relatively high pressure inlet process gas entering through the

nipples

68 and 69 flows through the respective associated passages into the inlet passages 53 leading to opposite sides of the impeller 29 adjacent the hub thereof. These streams of process gas are turned by the configuration of the passages 46 into a radially outward direction and flow over the blading 34 on opposite sides of the impeller 29 and are compressed by centrifugal action.

Typically, the shaft and hence the impeller 29 which is fast thereto may rotate at a high speed such as 70,000 r.p.m., being driven at this speed by the turbine wheels 96 and 98. With such high speed of rotation it has been found desirable to dispose opposite the bladed sides of the impeller the freely rotatable plates 71 and 72 which will assume some slower speed of rotation with respect to the rotating impeller. Rotation of the freely rotatable plates 71 and 72 is induced by the circumferentially directed drag of the gas flowing between these plates and the impeller. The provision of the plates 71 and 72 has been found to improve the efliciency of compression as compared to a situation where a stationary wall or surface opposes the blading on the rotating impeller.

The process gas is centrifugally compressed by the rotating impeller 29 and collects in the annular chamber 81 from whence it is discharged through the diffuser slots 63 into the annular groove 62. From this groove 62 the compressed process gas is discharged through the passage 61 and out the outlet nipple 70.

With the compressor handling process gas having such a high pressure it is impossible to prevent the leakage of gas between relatively rotating parts. Accordingly the high pressure inlet process gas which is present in the inlet passages 53, 46, leaks through the annular radial clearances 89 and 90 and is equalized by reason of the axially extending communicating passages or. grooves 33 in the central shaft section 18. This high pressure process gas leaks axially outwardly pass the labyrinth seal means 91 and 92 to collect Within the

internal housing chambers

86 and 88.

From these chambers gas flows through the connected passages 93-95 to the corresponding opposing surfaces between the sleeve bearings 82, 83 and

shaft sections

21 and 22, respectively. The cylindrical shaft section opposing the radial holes 94 acts as a valve closure for the inner ends of these holes and thereby controlsthe pressure of gas. For example, should the shaft tend to settle downwardly clue to gravity, as viewed in FIG. 3, the lower I holes 94 depicted in that figure will tend to be closed off more by the opposing peripheral surface of the

corresponding shaft section

21 or 22. This tends to increase the pressure in these lower passa ges94 and this pressure is utilized to tend to lift the shaft. In this manner an annular film of gas is provided between the opposing surfaces of the shaft and sleeve bearings and thus the shaft floats on such gas film. This type of support does not require any conventional lubrication such as with oils or greases. In fact contamination of ethylene gas with oil or grease would be deleterious.

Obviously with some necessary clearance provided between the opposing bearing and shaft surfaces, there will be additional axially outwardly directed gas leakage. This gas leakage therefore flows pass the labyrinth seal means 104 and 105 to collect in the annular grooves 106 and 113, respectively. From the groove 106, the gas flows through the connected passages 108-111 into the turbine inlet chamber 112. From the groove 113 the gas flows through the connected passages 114416 and 118 into the other turbine inlet chamber 119. By the time the leakage gas escapes through the branch outlets 111 and 118, its pressure will have been reduced to about 2500 p.s.i. so that this leakage gas comingles with the working gas in the respective annular

turbine inlet chambers

112 and 119 at substantially the same pressure.

It will be seen that the symmetrical blading 34 on 0pposite sides of the impeller 29 will not produce any resultant end thrust or axially directed thrust. Likewise, the drive turbine wheels 96 and 98, being similar and arranged back to back, will not produce any resutlant end or axially directed thrust. In fact, the whole design of the turbine compressor unit is symmetrical and no special end thrust bearing means need be provided.

From the foregoing, it will be seen that the present invention provides a hermetically sealed high speed turbine driven high pressure centrifugal compressor unit which accomplishes the various objects stated supra. Modifications and changes may occur to those skilled in the art without departing from the spirit of the present invention and therefore the preferred embodiment shown and described is illustrative and not limitative of the present invention, the scope of which is intended to be measured by the appended claims.

What is claimed is:

1. In a hermetically sealed turbine driven centrifugal compressor unit, the combination comprising a housing, a shaft, fluid type bearings supported by said housing and journalling said shaft inwardly of each end thereof so as to leave overhung shaft end portions, an impeller arranged within said housing intermediate said bearings and fast to said shaft, symmetrical blading on opposite axially facing sides of said impeller, a pair of similar turbine wheels arranged within said housing and severally nonrotatively mounted on said overhung shaft end portions and facing in opposite axial directions, fluid inlet passage means of said turbines through which pressurized fluid is supplied, fluid inlet passage means for said impeller through which fluid under a higher pressure is supplied, and means conducting fluid leaking internally from said impeller inlet passage means toward said turbine inlet plasiage means through said hearings to fluid float said s at.

2. In a hermetically sealed turbine driven centrifugal compressor unit, the combination comprising a housing, a shaft, fluid type sleeve bearings supported by said housing and journalling said shaft inwardly of each end thereof so as to leave overhung shaft end portions, an impeller arranged within said housing intermediate said bearings and fast to said shaft, symmetrical blading on opposite axially facing'sides of said impeller, a pair of similar turbine wheels arranged within said housing and severally non-rotatively mounted on said overhung shaft end portions and facing in opposite axial directions, means providing fluid inlet passage on each axial side of said impeller and communicating with said impeller adjacent its radially inner end, and means supplying fluid internally leaking from said passages to said hearings to fluid float said shaft and including labyrinth seal means surrounding said shaft on each side of said impeller intermediate the same and the corresponding one of said bearings, the inner end of each of said seal means being 'in communicationwith the corresponding one of said the inner peripheral surface'of the corresponding one of said bearings.

3. In a hermetically sealed turbine driven centrifugal compressor unit, the combination comprising a housing, a shaft, fluid type sleeve bearings supported by said housing and journalling said shaft inwardly of each end thereof so as to leave overhung shaft end portions, and impeller arranged within said housing intermediate said bearings and fast to said shaft, symmetrical bl-ading on opposite axially facing sides of said impeller, a pair of similar turbine wheels arranged within said housing and severally non-rotatively mounted on said overhung shaft end portions and facing in opposite axial directions, means providing a fluid inlet passage on each axial side of said impeller and communicating with said impeller adjacent its radially inner end, and means supplying fluid internally leaking from said passages to said bearings to fluid float said shaft and including labyrinth seal means surrounding said shaft on each side of said impeller intermediate the same and the corresponding one of said bearings, the inner end of each of 'said seal means being in communication with the corresponding one of said passages, means establishing communication between the inner and opposing ends of said seal means, means providing a compartment at the outer end of each of said seal means and means establishing communication between each of said compartments and the inner peripheral surface of the corresponding one of said bearings.

4. In a hermetically sealed turbine driven centrifugal compressor unit, the combination comprising a housing, a shaft, fluid type sleeve bearings supported by said housing and journalling said shaft inwardly of each end thereof so as to leave overhung shaft end portions, an impeller arranged within said housing intermediate said bearings and fast to said shaft, symmetrical blading on opposite peller and communcating with said impeller adjacent its radially inner end, means supplying fluid internally leaking from said passages to said bearings to fluid float said shaft and including labyrinth seal means surrounding said shaft on each side of said impeller intermediate the same and the corresponding one of said bearings, the inner end of each of said seal means being in communication with the corresponding one of said passages, means providing a compartment at the outer end of each of said seal means and means establishing communication between each of said compartments and the inner peripheral suraxially facing sides of said impeller, a pair of similar turbine wheels arranged within said housing and sever-ally non-rotati-vely mounted on said overhung shaft end portions and facing in opposite axial directions, means providing a fluid'inlet passage on each axial side of said impeller and communicating with said impeller adjacent its radially inner ends, and means supplying fluid internally leaking from said passages to said bearings to fluid float said shaft and including labyrinth seal means surrounding said shaft on each side of said impeller intermediate the same and the cor-responding one of said bearings, the inner end of each of said seal means being in communication with the corresponding one of said passages, means establishing communication between the inner and opposing ends of said seal means, means providing a compartment at the outer end of each of said seal means, means establishing communication between each of said compartments and the inner peripheral surface of the corresponding one of said bearings and another labyrinth seal means surrounding said shaft and arranged between each of said bearings and the corresponding one of said turbine wheels. 7

compressor unit, the combination comprising a housing, a shaft, fluid type sleeve bearings supportedby said housing and journalling said shaft inwardly of each end thereof so as to leave overhung shaft end portions, an impeller arranged within said housing intermediate said bearings and fast to said shaft, symmetrical blading on opposite axially facing sides of said impeller, a pair of similar turbine wheels arranged within said housing and severally non-rotatively mounted on said overhung shaft end portions and facing in opposite axial directions, means providing a fluid inlet passage on each axial side of said im- V mediate said bearings and fast to said shaft, symmetrical face of the corresponding one of said bearings, means providing an inlet passage associated with each turbine wheel for supplying fluid to drive the same, and means conducting fluid leaking past each of said hearings to the corresponding one of said turbine inlet passages.

6. In a hermetically sealed turbine driven centrifugal compressor unit, the combination comprising a housing including a barrel section and end heads, a shaft arranged entirely within said housing, fluid type sleeve bearings supported by said housing and journalling said shaft inwardly of each end thereof so as to leave overhung shaft end por- .tions, an impeller arranged within said housing intermediate said bearings and fast to said shaft, symmetrical blading on opposite axially facing sides of said impeller, means providing a pair of fluid inlet passages extending through said barrel section and leading to opposite sides of said impeller adjacent its radially inner end, means providing a fluid outlet passage extending from the periphery of said impeller through said barrel section, a pair of similar turbine wheels arranged Within said housing and severally non-rotatively mounted on said overhung shaft end portions and facing in opposite axial directions, means providing a working fluid inlet passage for each of said turbine wheels and extending through the corresponding one of said end heads, means providing a working fluid outlet passage for each of said turbine wheels and extending through the corresponding one of said end heads, means conducting fluid leaking from said impeller inlet passages to the space between the corresponding opposing peripheries of said sleeve hearing and shaft to fluid float said shaft, and means conduct-ing fluid leaking from each of said bearing spaces to the corresponding one of said turbine inlet passages.

7. In a turbine driven centrifugal compressor unit, the combination comprising a housing, a shaft, bearings supported by said housing and journalling said shaft inwardly of each end thereof so as to leave overhung shaft end portions, an impeller arranged within said housing intermediate said bearings and fast to said shaft, symmetrical blading on opposite axially facing sides of said impeller, a pair of freely rotatable plates arranged within said housing coaxially with said impeller and severally opposing the bladed sides thereof, and a pair of similar turbine wheels arranged within said housing and severally nonrotatively mounted on said overhung shaft end portions and facing in opposite axial directions.

8. In a turbine driven centrifugal compressor unit, the combination comprising a housing, a shaft, bearings supported by said housing and journalling said shaft inwardly of each end thereof so as to leave overhung shaft end portions, an impeller arranged within said housing interbl-ading' on opposite axially facing sides of said impeller, a pair of freely rotatable plates arranged within said housing coaxial-ly with said impeller and severally opposing the bladed sides thereof, a bearing ring rotatably supporting each of said plates and composed of long chain fluorinated polymers of ethylene such as tetrafluoroethy'lene, and a pair of similar turbine wheels arranged within said hous-- ing and severally non-rotatively mounted on said overhung shaft end portions and facing in opposite axial directions.

9. In a turbine driven centrifugal compressor unit, the combination comprising a housing, a shaft, bearings supported by said housing and journallingsaid shaft inwardly of each end thereof so as to leave overhung shaft end portions, an impeller arranged within said housing intermediate said bearings and fast to said shaft, symmetrical blading on opposite axially facing sides of said impeller, a diffuser ring arranged within said housing and surrounding said impeller, a pair of freely rotatable plates arranged within said housing coaxially with said impeller and severally opposing the bladed sides thereof, an inner bearing ring rotatably supporting each of said plates on said housing, said diffuser ring and plates having overlapping portions, and a pair of similar turbine wheels arranged within said housing and severally non-rotatively mounted on said overhung shaft end portions and facing in opposite axial directions.

References Cited by the Examiner UNITED STATES PATENTS 1,171,926 2/16 Carpenter 230-116 2,064,126 12/36 Schellens et a1. 230116 2,321,276 6/43 De Bolt 10398 X 2,334,625 11/43 Heppner 10398 X 2,929,548 3/60 Crooks et a1. 230116 FOREIGN PATENTS 22,753 1/06 Austria. 418,900 9/25 Germany.

LAURENCE V. EFNER, Primary Examiner. ROBERT M. WALKER, Examiner.

Claims

1. IN A HERMETICALLY SEALED TURBINE DRIVEN CENTRIFUAL COMPRESSOR UNIT, THE COMBINATION COMPRISING A HOUSING, A SHAFT, FLUID TYPE BEARINGS SUPPORTED BY SAID HOUSING AND JOURNALLING SAID SHAFT INWARDLY OF EACH END THEREOF SO AS TO LEAVE OVERHUNG SHAFT END PORTIONS, AN IMPELLER ARRANGED WITHIN SAID HOUSING INTERMEDIATE SAID BEARINGS AND FAST TO SAID SHAFT, SYMMERTICAL BLADING ON OPPOSTIE AXIALLY FACING SIDES OF SAID IMPELLER, A PAIR OF SIMILAR TURBINE WHEELS ARRANGED WITHIN SAID HOUSING AND SEVERALLY NONROTATIVELY MOUNTED ON SAID OVERHUNG SHAFT END PORTIONS AND FACING IN OPPOSITE AXIAL DIRECTION, FLUID INLET PASSAGE MEANS OF SAID TURBINES THROUGH WHICH PRESSURIZED FLUID IS SUPPLIED, FLUID INLET PASSAGE MEANS FOR SAID IMPELLER THROUGH WHICH FLUID UNDER A HIGHER PRESSURE IS SUPPLIED, AND MEANS CONDUCTING FLUID LEAKING INTERNALLY FROM SAID IMPELLER INLET PASSAGE MEANS TOWARD SAID TURBINE INLET PASSAGE MEANS THROUGH SAID BEARINGS TO FLUID FLOAT SAID SHAFT.