US2393691A

US2393691A - Pumping unit

Info

Publication number: US2393691A
Application number: US508807A
Authority: US
Inventors: Igor J Karassik
Original assignee: Worthington Pump and Machinery Corp
Current assignee: Worthington Pump and Machinery Corp
Priority date: 1943-11-03
Filing date: 1943-11-03
Publication date: 1946-01-29
Anticipated expiration: 1963-01-29

Description

Jan. 29, 1946. I Ass K 2,393,691

PUMPING UNIT Filed Nov. 3, 1943 4 Sheets-Sheet l J 4/ V///// Iaon .IKAnAssIK BY Z/c A TTORNE Y l. J. KARASSIK 2,393,691

PUMPING UNIT Filed Nov. 5, 1945 4 Sheets-Sheet 2 IN VEN TOR A TTORNE Y Jan. 29, 1946.

Iaon JKABAss 1K l. .l. KARASSIK PUMPING UNIT Jan. 29, 1946.

Filed Nov. 3, 1943 4 Sheets-Sheet 3 I GOR J. KARASS 1K INVENTOR ATTORNEY Jan. 29, .1946. V J. KARASSIK PUMPING UNIT Filed Nov. 3, 1943 4 Sheets-Sheet 4 la'on J. KARASSJK IN VENT OR ATTORNEY Patented Jan. 29, 1946 PUMPING UNIT I Igor J. Karassik, South Orange, N. 1., assignor Worthington Pump and Machinery Cor-pore. tion, Harrison, N. J., a corporation of Delaware Application November 3, 1943, Serial No. 508,807,

23 Claims. (Cl. 103-87) This invention relates to pumping units. and more particularly to turbine driven centrifugal pumps designed for handling high. pressures such as five hundred to one thousand pounds per square inch and particularly adaptable for use as boiler feed pumps.

The general novelty and advantages of the present invention are particularly applicable for use in steam turbine driven boiler feed pumps,

refinery centrifugal pumps driven by natural ga and analogous pumping units.

An object of the present invention is to provide a turbine driven centrifugal pump for handling high pressures at high operating speeds which is of greatly simplified construction ever present day approved pumping units of similar nature, especially with respect to stumng boxes and sealing structures, and a pumping unit which will eliminate many of the problems and difficulties contingent with effectively sealing the pump. In modern power plant construction, the trend in design in boiler feed pumps is toward high operating speeds such as five thousand to seven thousand revolutions per minute and pressures per stage of the pump as high as five hundred pounds per square inch. This tendency results in a lesser number of stages, smaller casing areas, greater reliability of th axially split casing joint, and greater efilciency on the part of the driving turbine and the pump, but increases difllculty of 3 effectively sealing the pump structure against leakage, and introduces difllcult problems with reference to the stufiing boxes employed in the pump structure.

In the event a standard approved type of pump and turbine construction are employed, for instance, a two stage pump designed to develop one thousand pounds per square inch at a speed of seven thousand revolutions per minute, one 01 the stufllng boxes would be subject to suction pressure of the pump, while the second stuinng box would be under the discharge pressure of the first stage or five hundred pounds per square inch.

It is a well-known fact that the diiiiculty of packing a stufllng box under high pressures or temperatures or both can be linked with the product of pressure, temperature, and linear speed, or with the product of some exponential function of all three. Thus it can be said that doubling the rotating speed has about the same eflect on the stufllng box as doubling the pressure to which the stuifing box is subjected. No experience today exists of successfully packing a centrifugal a similar pump against a pressure of five hundred pounds per square inch and seven thousand revolutions per minute. While pressure reducing structures such as pressure reducing labyrinths might be employed to reduce the pressure in advance of the stufllng box such labyrinths are expensive, materially increase the bulk of the pump and are unsatisfactory both from the point of view of efllciency and satisfaction of the operation.

To obviate the disadvantages presented by the above outlined factors, the present invention contemplates the elimination of the second stufling box in such a pump; 1. e., the stumng box which would be subject to the discharge pressure of the first stage of the pump; by providing in such a pumping unit a combined turbine and pump in a condensation of a part of the steam in the mixing chamber, return of leakage water and condensate to the pump, and a stoppa e or dam- 9 ming of leakage of liquid into the turbine, thus eflectively sealing the pump at the high pressure leakage point without embodying the many disadvantages and problems of a stufllng box at such point in the pump.

With thes and other objects in view, as may appear from the accompanying specification, the invention consists of various features of construction and combination of parts, which will be first described in connection with the accompanying drawings, showing a pumping unit of a preferred form embodying the invention, and the features forming the invention will be specifically pointed out in the claims.

In the drawings:

Figure 1 is a side elevation of the improved pumping unit.

Figure 2 is a longitudinal section through the pumping unit.

Figure 3 is a detailed section of a part of the pumping unit showing a form ofmixer in the mixing chamber.

Figur 4 is a detail cross-section illustrating a further modified construction for providing thorough mixing of the steam and water in the mixpump against one thousand pounds per square inc chamber.

v bine 2 and the pump Figure 5 is a detail longitudinal section illustrating the embodiment of pressure reducing apparatus for preventing back flow of liquid into the turbine.

Figure 6 is a detail section illustrating a form of pressure reducing apparatus for reducing the leakage and the pressure of high pressure steam from the sealing arrangement into the back pressure portion of the turbine.

Figure '7 is a detail section of a slight modification of the sealing arrangement.

Figure 8 is a longitudinal section of a pumping unit constructed in accordance with the present I are formed, cast together, or connected to form a'continuous or sectionalized casing free from spaces which freely communicate with the at mosphere, thus providing in effect a unitary casing for the turbine 2 and the centrifugal pump I. Such a structure eliminates couplings or analogous structures between the turbine and the pump and with the novel sealing arrangement as will be hereinafter described eliminates a stufilng box for the pump and a stufling box for the turbine. The impellers 3 of the multistage pump are disposed in back-to-back relation with the inlet or suction I of the pump facing the end of the casing outwardly from the pump and away from the turbine so that the joint where the shaft 5 passes out of the casing to the bearing structure 8 is subjected only to suction pressure of the pump which is the lowest pressure in the pumping unit. The joint between'the casing and the shaft or rather the opening in the casing 6 through which the shaft 5 projects is packed or sealed with a stufiing box 9 of any approved construction. The first stage of the pump discharges through a cross over passage I0 into the suction passage ll of the second stage of the pump so that the opening in the casing 6 at the inner end of the pump through which the shaft 5 extends is subject only to the discharge pressure of the first stage of the pump. While in the drawings a two-stage centrifugal pump is shown, it is to be understood that any number of stages in a centrifugal pump may be employed without departing from the spirit of the present invention so long as the stage impellers are arranged in such manner that the outer end of the pump casing is subject to suction pressure and the inner end is subject tothe pressure of the second stage or one of the lower stages of the pump.

The casing 6 embodies a connecting portion I: which connects the pump enclosing portion of the casing 6 and the turbine enclosing portion of the casing 8. The connection portion 5 has an annular chamber I4 formed therein intermediate its ends which will be designated as a mixing chamber, and this chamber I4 is open through a leakage passage indicated at l5 to the suction chamber so that water or other liquid being pumped may leak from the suction chamber ll into the'mixing chamber M.

A second chamber I6 is formed in the connecting portion I2 and it has a steam supply line ll connected thereto for delivering steam into the chamber IS. The steam delivered to the chamher "5 maybe taken from the steam supply line |8 to the turbine 2 or from any other suitable supply source for steam under pressure greater than the pressure of water or other liquid in the suction chamber 7 The discharge from the first stage impeller of the pump through the cross-over passage I0 is divided into two streams, one of which flows into the suctionchamber H and the other through the passage l9 into the chamber It. The steamreceiving chamber I6 has connection with the mixing chamber l4 through a leakage passage 20 and with the back pressure area 2| of the I turbine through a leakage passage22.

The suction chamber H of the pumpisunder a pressure corresponding to the discharge pressure of the first stage of the pump and the same pressure exists in the mixing chamber I4. The live steam which is admitted to the chamber I6 is under a pressure in excess of the pressure in the mixing chamber I4. The pressure difference results from the fact that the discharge pressure of the centrifugal pump l is generally from. fifteen to twenty five percent in excess of the boiler pressure of the system in which the boiler feed pump is employed, and thus the first stage discharge pressure will be of an order of fifty-seven percent to sixty-two percent of the steam pressure at the turbine inlet and of the steam pressure in the chamber |6 if they are'fed by steam from the same boiler into which the boiler feed pump discharges.

The space 2| isunder a pressure corresponding 40 to the back pressure of theturbine and, therefore, a differential exists between the chamber l6 and the space 2|. This chamber l8 and the space 2| which have communication through the leakage passage 22 are separated by suitable packing in this leakage passage 22. The packing in thepassa'ge 22 may be of any approved or suitable type similar to that used on back pressure steam turbines and similar to that indicatedat 23 in the opening about the shaft 5 at the end of the casing outwardly of the turbine.

In operation, when steam is admitted to the chamber l6 through the steam supply pipe H, a certain portion of this steam leaks into the back pressure space or chamber 2| of the turbine and another portion of the steam leaks into the mixing chamber I4. In the mixing chamber, the steam is condensed by the action of the incoming water into the mixing chamber l4 and leaksefrom the mixing chamber through the passage it into the suction chamber II of the pump from which it is picked up by the second stage impeller of the pump. The steam entering the steam space It need not necessarily correspond to the steam pressure in the turbine inlet since the pressure difference between the chamber l6 and the mixing chamber His more than sufiicient to cause fiow, and since such excess pressure would increase the steam leakage into the back pressure space or area 2| beyond that absolutely necessary. .Consequently, the pressure of the steam delivered through the steam inlet I! to the chamber It may be such as. to provide an adequate excess preslsaurenin the chamber l6 over that in the chamer I This excess pressure of the steam will cause a stoppage o damming of the water or liquid flow towards the turbine 2| and serve to seal the inner end of the pump casing against leakage without the employment of stuffing box or the like.

It may be desirable to facilitate the mixing of the steam and the water flowing into the mixing chamber l4, and Figures 3 and 4 of the drawings show different structures for facilitating this mixing.

In Figure 3 of the drawings, a mixing labyrinth member 30 is mounted in any suitable manner upon the shaft 5' and is located in the mixing chamber I 4' and it comprises a plurality of 9.1-.

ternate circular vanes and passages arranged to bring the steam flowing through the leakage passage 20' into full contact with the water entering the chamber l4 through the by-pass 19.

The modified construction of the mixing apparatus illustrated in Figure 4 comprises a circular partition 3! which is placed within the mix-- ing chambe I4a, dividing the mixing chamber into an outer space 32 and an inner space 33. The water flows through the by -pass I941 into the outer annular space 32, and from there through a plurality of openings 34 formed in the circular partition 3| into the inner space 33, while the steam flows into the inner space 33 through the communicating passage 2011; thus the water enters the inne chamber 33 in radial flow substantially perpendicular to the direction of the steam flowing into the mixing chamber causing a thorough and complete mixing of the steam and water in the mixing chamber.

It may be desirable to provide against the possibility of back flow of water from the mixing chamber into the steam chamber and Figure 5 of the drawings shows an arrangement for this purpose. In Figure 5, the mixing chamber l4b is connected to the steam chamber IGb by an annular passage 20?) surrounding the shaft 5b the same as in Figure 2 of the drawings. However, a labyrinth 36 comprising a stationary element 31 carried by the casing lb and a rotating element 38 carried by the shaft 5b is inserted in the passageway. As is usual in the construction of pressure reducing, flow retarding labyrinths, the elements 3'! and 38 comprise inner engaging sectionsspaced sufficiently to provide a restricted, sinuous passage which would result in a reduction of the pressure of water or liquid sufliciently to prevent its back flow into the chamber 16b in the event of lowering of the steam pressure therein.

This Figure 5 also shows packing at 39 which will retard the flow of steam from the chamber Nib into the back pressure chamber or space of the turbine. This packing may be any standard form of packing used in high pressure steam turbines, or if it is so desired, a sealing arrangement such as that shown in Figure 6 of the drawings may be substituted for the packing 39 or the packing in the leakage passage 22.

for the steam chamber l6 may be taken directly from the steam line 18 to the turbine 2 in which event the steam pressure in the chamber It will be equal to the inlet pressure of the steam to the turbine, and it would be desirable to provide suit- The sealing arrangement illustrated in Figure 6 of the drawings comprises a sealing disc 40 carried by the shaft 50 which has a highly polished surface 4| co-acting with a highly polished surface 42 formed on the co-operating disc 43. The

.disc 43 is carried by the casing 60 and is mounted able means to prevent excessive flow of steam from the chamber l6 into the back pressure space or chamber 2|, or the steam to the steam chamber It may be taken directly from the boiler at a point where the pressure is lower than the pressure of the steam delivered to the turbine or from any other suitable source of steam having a pressure sufllciently in excess of the pressure of the water in the suction chamber l5 to insure the proper sealingopera-tion of the apparatus.

It may be desirable to provide means for preventing leakage of water along the shaft of the pumping unit into the turbine housing or casing when the pump is idle or at such other times as the pressure of the steam is lower than the pressure of the leakage water, and for the purpose of preventing the. leakage of water into the tur- Md, if necessary, at such times or when the pumping unit is shut down. Such means are shown in Figure 7 of the drawings as a venting or drainage pipe 48 having a manuallyoperated valve 49.

therein. The pipe 43 may drain to atmosphere or to any suitable low pressure point so as to prevent flooding of the mixing chamber l4d when the pump is shut down.

Figures 1 to 4 inclusive of the drawings show structures which are particularly applicable for use in steam-turbine driven boiler feed pumping units, however, the invention is equally applicable for employment in pumping units driven by gas turbines such as, for instance,,reflnery centrifugal pumps driven by gas turbines operated by natural gas under pressure, and Figures 8 and 9 of the drawings show structures of the pumping units of the gas turbine driven typ it being understood that the various features of Figures 3, 4, 5, 6, and '7 are applicable to these.

gas turbine driven structures if desired or needed.

In Figure 7 of the drawings, a multistage centrifugal pump 50 is shown which is driven froma natural gas turbine 5| of any approved construction through the drive shaft 52. The pump structure 50 is similar to or substantially the same as the pump structure shown in Figure 2 of the drawings having the discharge from the first stage 53 of the pump carried by a cross over passage 54 and discharged into the inlet space or chamber 55 of the second stage 53 of the pump and thus the two outside ends of the pump casing are subjected to the lowest pressures in the pump. The end of the casing outwardly of the inlet of the first stage 53 of the pump being subjected only to the suction pressure of the first stage, while the end of the casing which faces the turbine 5! is subjected only to the suction pressure of the second stage.

The casing 51 of the centrifugal pump is com nected to the casing 58 of the natural gas turbine 5| by a connecting portion 59. The connecting portion 59 has a mixing chamber 60 formed therein which is open through a pressure reducing bushing SI of any approved construction-to the suction chamber 55 of the second stage 56 of the pump thus permitting leakage from the pumpabout-the shaft I to pass into the mixing chamber 60. The pressure fluid or such as natural gas or the like employed in operating the turbine 5| is delivered to the turbine through a suitable delivery system or pipe 62, and a branch pipe 63 is-connected to the pipe 4 82 and opens into a second chamber 64 formed in the connecting portion 59. The second chamber '64 has communication with the mixing chamber 60 through a reduced communicating passage 55 so that the gas under pressure will enter the mixing chamber 60, and set up a counteracting pressure against the leakage fluid from the pump into the chamber 60 thus preventing leakage of the fluid pumped along the shaft out of the casing 51 or connection 59 or into the back pressure chamber 66 of the turbine 5|. Packing of any other, suitable leakage retarding pressure reducing means is provided between the second chamber '64 and the back pressure chamber 68 to retard leakageof gas from the chamber 64 into the turbine housing.

A leak-01f line 68 is connected to the mixing chamber 60 and may have its outlet at any point in the pumping cycle where a lower pressure exists than the pressure in the mixing chamber 69. A pressure reducing orifice '59 is interposed in the leak-ofi line '68. This pressure reducin orifice 69 may be of any approved type which may be purchased upon the open market, such for example, the type of pressure reducing oriflce shown in application for U. S. Letters Patent, Serial No. 499,780, filed August 24, 1943. The dimensions of the pressure reducing orifice 69 are calculated in such manner as to impose a back pressure of a known quantity at the mixing chamber 60 and to provide for a relatively small quantity of leak-off of' the mixture of fluid pumped and gas from the mixing chamber 59 through the leak-off line 58. The back pressure in the mixing chamber (ill is preferably selected in such manner as to be lower by fifty to one hundred pounds per square inch than the pressure at the entrance chamber 55 of the second stage of the pump, and thus it will be seen that the pressure drop through the pressure reducin bushing Si is relatively low and the life of this pressure reducing bushing will therefore be considerably longer than if it were selected to act as a pressure reducing labyrinth ahead of a conventional stuffing box;

The form of the invention shown in Figure 9 of the drawings likewise is a centrifugal pump adapted forbeing driven by a gas operated turthe shaft 1 I. As in all of the constructions shown in the drawings of the present invention, the turbine 12 is directly connected to the impeller of the pump which it drives without the use, of couplings, gearing or any analogous structure.

The casing I3 of the centrifugal pump is connected to the casing 14 of the turbine by a connecting portion 15. The connecting portion 15 has a mixing chamber 16 therein which has com-'- munication through a pressure reducing bushing structure 11 with the space 18 in the pump casing 13 behind the impeller, 10, thus an leakage from the-pump casing along the shaft 'II' will be through the pressure reducing bushing 11 into the mixing chamber I6. The connecting portion 15 alsohas a second chamber 19 formed therein which receives gas under pressure either from the supply line 80 of pressure motive fluid to the turbine 12 or from any other suitable source where the gas will have-a pressure in excess of the pressure of the fluid leaking into the mixing chamber 16. The gas entering the chamber 19 will passthrough the restricted passageway 8| into the mixing chamber 16 where its pressure will counteract the outward flow presure of the leakage fluid and where the gas and fluid pumped will be thoroughly mixed. A leak-off line 82 is connected to the mixing chamber 16 and to any suitable point in the pumping circuit or elsewhere where the pressure is lower than the pressure in the mixing chamber. A pressure reducing orifice 83 is mounted in the leak-off line 82 and serves the same function and may be of the same construction as the pressure reducing orifice 59 shown in Figure 8 of the drawings. Packing is provided in the space between the second chamber 19 and the back pressure area 84 of the housing or casing 14 of the turbine 12 so as to reduce the pressure of any gas leaking into the back presure chamber 84 and also so as to retard the leakage of such gas into the back pressure chamber.

In all of the forms shown, the manner of preventing leakage of liquid pumped out of the pump casing along the shaft thereof prevents the loss of any water or liquid pumped by the'pump out of the pumping system or cycle, andin the case of steam driven turbines and boiler feed systems it not only prevents the loss of feedwater from the system but the steam employed, going'back into, the system, serves as a make up thus requiring the addition of a smaller quantity of nondeaerated or treated make-up water which it is necessary to feed into the boiler feed system during operation.

It will be understood that the invention is not to be limited to the specific construction or arrangement' of parts shown, but that they may be widely modified within the invention defined by the claims.

What is claimed-is:

1. In a turbine driven pumping unit adapted to pump liquids at a pressure from 500 lbs. per sq. in. orupwardly, a casing for the pump, a casing for the turbine and a connectin portion between the pump and turbine, said connecting portion having a chamber therein for receiving liquid under pressure from the pump, a connecting liquid leakage passage leading from said pump casing into said chamber, said passage being of smaller cross sectional area than the chamber and having a second chamber therein for receiving pressure fluid at-a pressure in excess of leakage pressure from the turbine, said chambers having connection whereby the liquid and pressure fluid pressures will counteract each other to prevent leakage of liquid into the turbine or leakage of pressure fluid into the pump.

2. In a turbine driven pumping unit adapted to pump liquids at a pressure froml500 lbs. per sq. in. or upwardly, a casing for the pump, a casing for the turbine, and a connecting portion between the pump and turbine, said connecting portion having a chamber therein for receiving liquid under pressure from the pump and'having a second chamber therein for receiving pressure fluid from a source exteriorly of the turbine, said chambers having connection whereby the liquid and pressure fluid pressures will counteract each other to prevent leakage of liquid into the turbine or leakage of pressure fluid into' the pump, and pressure reducing means in the connection between said chambers.

3. In a turbine driven pumping unit adapted to pump liquids at a pressure from 500 lbs. per sq. in. or upwardly, a casing for the pump, a casing for the turbine, and a connecting portion between the pump and turbine; said connecting portion having a chamber therein for receivin liquid under pressure from thepump and having asecond chamber therein for receivingpressure fluid from the turbine operating supply at a pressure in excess of the leakage pressure from the turbine, said chambers having connection whereby the liquid and pressure fluid pressures will counteract each other to prevent leakage of liquid into the turbine or leakage of pressure fluid into the pump, said liquid chamber opening into the pump to permit leakage of liquid from the chamber back into the pump at a point where the pressure is lower than the pressure liquid received into the chamber from the pump.

4. In a turbine driven pumping unit adapted to pump liquids at a pressure from 500 lbs. per sq. in. or upwardly, a casing for the pump, a casing for the turbine, and a connecting portion between the pump and turbine, said connecting portion having a chamber therein for receiving liquid under pressure from the pump and having a second chamber therein for receiving pressure fluid from the turbine operating supply at a pressure in excess of the leakage'pressure from the turbine, said chambers having connection whereby the liquid and pressure fluid pressures will counteract each other to prevent leakage of liquid into the turbine or leakage of pressure fluid into the pump, said second chamber connected to the back pressure chamber of the turbine to permit limited leakage of pressure fluid from the second chamber into the turbine, and pressure reducing means in the connection between the second chamber and turbine.

5. In a steam turbine driven pumping unit adapted to pump liquids at a pressure from 500 lbs. per sq. in. or upwardly, a casing for the pump, a casing for the turbine, and a connecting portion between the pump and turbine, said connecting portion having a chamber therein for receiving liquid under pressure from the pump and having a second chamber'therein for receiving steam from a source external of the turbine and at a pressure in excessof leakage pressure from the turbine, said chambers having connection whereby the liquid and steam pressures will counteract each other to prevent leakage oi liquid into the turbine or leakage of steam into the pump, and mixing means for causing thorough mixing of the steam and liquid in the liquid chamber to cause condensation of thesteam, said liquid chamber opening into the pump to permit leakage of liquid and condensation; from the chamber back into thepumpat a point where the pressure is lower than the pressure of liquid received by the chamber from the pump.

6. In a turbine driven pumping unit'adapted to pump liquids at a pressureffronriwo lbs, per sq. in. or upwardly, a casing for the pump, a casingfor the turbine, and a connecting portion between the pump and turbine, a shaftextending through said housing and forming the turbine driven shaft and the pump driving shaft, a packing carried by said housing at the outer end of the pump, said pump being arranged whereby said packing will be subject only to the lowest liquid pressure in the pump. g

'7. In a steam turbine driven ,pumpingunit adapted to pump liquids at a pressure from 500 lbs. per sq. in. or upwardly, a'casing forthe pump, a casing for the turbine and a connecting portion between the pump and turbine, said housing being constructed and arranged so as not to have any spaces between" the pump and turbine which freely communicate with atmosphere, said connecting portion having a chamber therein for receiving liquid under pressure from the pump and having a second chamber therein'for receiv ing steam,; said chambers having connection whereby the liquid-and steam pressures will counteract each other to I prevent leakage 'of liquid into the turbine or leakage of 'st'eaminto the pump,,a shafteiitcnding-through said hous ing and i'ormingthe turbine driven shaft and the pump driving shaft, a stumng box'carried by said housing at the outer end of the pump, said pump being arranged whereby said stufling box will be subject only to the lowest liquid pressure in the p mp- I 8. In a steam turbine driven pumping unit adapted to pump liquids at a pressure from 500 lbs. per sq. in. or upwardly a casingfor the pump, a casing for the turbine, and-a connecting portion between'the pump and turbine, said connecting portion having a chamber thereinfor receiving liquid under pressure'from the pump and having a second chamber therein'for receiving steam, said chambers having connection whereby the liquid and steam pressures will counteract each other to prevent leakage of liquid into the turbine 01' leakage of steam into the pump, a shaft extending through said housing and forming the turbine driven shaft, and the pump driving shaft, a stuffing box carried by said housing at the outer end of the pump, said pump being arranged whereby said stufiing box will be subject only to the lowest liquid pressure in the pump, and pressure reducing means in the connection between said chambers.

9. In a steam turbine driven pumping unit adapted to pump liquids at a pressure from 500 lbs. per sq. in. or upwardly, a casing for the pump, a casing for the turbine, and a connecting portion between the pump and turbine, said connecting portion having a chamber therein for receiving liquid under pressure from the pump and having a second chamber therein for receive ing steam, said chambers having connection whereby the liquid and steam pressures will counteract each other to prevent leakage of liquid into the turbine or leakage of steam into the pump, a shaft extending through said housing and forming the turbine driven shaft and the pump driving shaft, a stufllng box carried bysaid housing at the outerfendoi"the'pump,'jsaid pump being arranged whereby said stumng box' willbe subject only to the lowest liquid pressure in" the and having a second chamber therein for receiving steam, said chambers having connection whereby the liquid and steam pressures will counteract each other to prevent leakage of liquid into the'turbine or leakage of steam intothe pump, a shaft extending through said housing and forming the turbine driven shaft andthe pump driving shaft, a stufling box carried by said housing at the outer end of the pump, said pumpbeing arranged whereby said stufling box will be subject only to the lowest liquid pressure in the pump, said steam chamber connected to the back pressure chamber of the turbine to permit leakage of steam from the chamber into: the turbine, and leakage retarding means in the connection between the steam chamber and turbine, said liquid chamber opening into the pump to permit leakage of liquid from the chamber into the pump.

11. In a steam turbine driven pumping unit adapted to pump liquids at pressures from500 lbs. per sq. in. a housing including a casing for thepump and a casing for the turbine, said pump being arranged in the casing so that the lowest liquid pressure area in the pump will be at the outer end of the housing, a shaft extending through said housing and forming the turbine driven shaft and the pump driving shaft, a stufling box in said housing and about said shaft at the outer end of the housing which stufflng box is subject to. the lowest liquid pressure .in the a pump, a connecting portion formed in said housing between the pump and turbine, said connecting portion having a chamber therein for receiving liquid under pressure from the pump and a second chamber for receiving steam, said connecting portion being provided with a passage connecting said steam and liquid chambers to permit flow of steam'into the liquid chamber- 12. The method of preventing leakage of fluid pumped out of a turbine driven centrifugal pump about the shaft of the pump, which consists in counteracting the flow of leakage by subjecting it to counteraction of and mixing with apart of the pressure motive fluid employed to drivethe turbine, and returning the mixed pressure fluid and leakage to the circuit of the fluidpumped.

13. The method of preventing leakage of fluid pumped out of a turbine driven centrifugal pump about the shaft of the pump, which consists in counteracting the flow of leakage by subjecting it to counteraction of and mixing with a part of the pressure motive fluid employed to drive the turbine, and returning the mixed pressure fluid and leakage to the circuit of the fluid pumped, and providing a back pressure of a predetermined known quantity on the point of mixing of the the pressure motive fluid employed to drive the turbine, allowing the mixed leakage and motive I fluid to leak of! to a point of lower pressure, and

providing a back pressure of a predetermined known quantity to the point of mixing of the leakage and motive fluid.

15. In a steam turbine driven pumping unit adapted to pump liquids at high pressures, a casing for the'pump, a casing for the turbine, said pump being arranged in the casing so that the lowest liquid area in the pump will be at the outerv end of the casing, a shaft extending through said casing and forming the turbine driven shaft and the pump driving shaft, a connecting portion in said casing between the pump and turbine, said connecting portion having a chamber therein for receiving liquid under pressure from the pump and a second chamber for receiving steam, said connecting portion being provided with a passage connecting said steam and liquid chambers to permit flow of steam into the liquid chamber.

16. In a turbine driven pumping unit, a casing for the pump, a casing for the turbine, and a connecting portion between said pump and turbine casing, said connecting portion having a chamber therein for receiving liquid under pressure from the pump, a connecting liquid leakage passage leading from the pump casing into said chamber, said leakage passage being of smaller cross sectional area than the chamber, said connecting portion having a second chamber therein for receiving pressure fluid at a pressure in excess bers having connection whereby the liquid and pressure fluid pressures will counteract each other to prevent leakage of liquid into the turbine or leakage of pressure fluid into the pump, and pressure reducing means associated with said chambers to prevent back flow of pressure fluid into the turbine. r

17. In a steam turbine driven pumping unit adapted to pump liquids at high pressures, a casing for the pump, a casing for the turbine, said pump being arranged in the casing so that the lowest liquid area in the pump will be at the outer end of the casing, a shaft extending through said casing and forming-the turbine driven shaft and the pump driving shaft, a connecting portion in said casing between the pump and turbine, said connecting portion having a chamber therein for receiving liquid under pressure from the pump and a second chamber for receiving steam, said connecting portion being provided with a passage connecting said steam and liquid chambers to permit flow of steam into the liquid chamber, and pressure reducing means associated with said chambers to prevent back flow of pressure fluid into the turbine. v

18; In a steam turbine driven pumping unit adapted to pump liquids at high pressures, acasing for the pump, a casing for the turbine, said pump being arranged in the casing so that the lowest liquid area in the pump will be at the outer end of the casing, a shaft extending through said casing and forming the turbine driven shaft and the pump driving shaft, a connecting portion in said casing between the pump and turbine,

with said chambers to prevent back flow of pressure fluid into the turbine, said pressure reducing means comprising a stationary element, and a co-acting rotary element carried by and rotatable with said shaft.

19. In a turbine driven pumping unit, a casing for the pump, a casing for the turbine, a connecting portion between the pump and turbine, said connecting portion having a chamber therein for receiving liquid under pressure vfrom the pump and having a second chamber therein for receiving pressure fluid from the operating fluid supply to the turbine, said chambers having connection whereby the liquid and pressure fluid pressures will counteract each other to prevent leakage of liquid into the turbine or leakage of pressure fluid into the pump, and pressure reducing means in the connection between said chambers. 1

20. In a turbine driven pumping unit, a casing for the pump, a casing for the turbine, a connecting portion between the pump and turbine, said connecting-portion having a chamber therein for receiving liquid under pressure from the pump and having a second chamber therein for receiving pressure fluid from the operating fluid supply to the turbine, said chambers having connection whereby the liquid and pressure fluid pressures will counteract each other to prevent leakage of liquid into the turbine or leakage of pressure fluid into the pump, and pressure reducing means associated with said chambers to prevent back flow of pressure fluid into the back pressure area of the turbine.

21. In a turbine driven pumping unit, a casing for the pump, a casing for the turbine, a connecting portion between the pump and turbine, said connecting portion having a chamber therein for receiving liquid under pressure from the pump and having a second chamber therein for receiving pressure fluid from the operating fluid supply to the turbine, said chambers having connection whereby the liquid and pressure fluid pressures will counteract each other to prevent leakage of liquid into the turbine or leakage of pressure fluid into the pump, and pressure reducing means in the connection between said chambers, said pressure reducing means comprising a stationar element, and a coacting rotary element.

22. In a turbine driven pumping unit, a casing for the pump, a casing for the turbine, a connecting portion between said pump and turbine casings, said connecting portion having a chamber therein for receiving liquid under pressure from the pump and having .a second chamber therein for receiving pressure fluid at a pressure in excess 01' the leakage pressure from the turbine, said chambers having connection whereby the liquid and pressure fluid pressures will counteract each other to prevent leakage of liquid into the turbine or leakage of pressure fluid into the pump, an outlet connection for said flrstnamed chamber, and pressure reducing means in said outlet connection.

23. In a turbine driven pumping unit, a casing for the pump, a casing for the turbine, a con" necting portion between the pump and turbine, said connecting portion having a chamber therein for receiving liquid under pressure from the pump and having a second chamber therein for receiving pressure fluid from the operating fluid supply to the turbine, said chambers having connection whereby the liquid and pressure fluid pressures will counteract each other to prevent leakage of liquid into the turbine or leakage of pressure fluid into the pump, pressure reducing means in the connection between said chambers, an outlet connection for said first-named chamber, and pressure reducing means in said outlet.

IGOR J. KARASSIK.