US1910811A

US1910811A - Centrifugal pump

Info

Publication number: US1910811A
Application number: US512863A
Authority: US
Inventors: Peterson Arvid
Original assignee: Laval Steam Turbine Co
Current assignee: De Laval Steam Turbine Co
Priority date: 1931-02-02
Filing date: 1931-02-02
Publication date: 1933-05-23
Anticipated expiration: 1950-05-23

Description

N Vw A. l Av J U 2 Shasta-Sheet 1 i: l//v A. PETERSQN CENTRIFUGL PUMP Fxled Feb 2 1931 May 23 1933' A. PETRsoN 1,910,311

` CENTRIFUGAL PUMP Filed Feb. 2, 1931 2 Sheets-Sheet. 2

Patented May 23, 1933 UNITED `STATES PATENT OFI-VICE ARVID PETERSON, 0F TBENTON, NEW JERSEY, .ASSIGNOR TO DE LAVAL STEAM TUR- BINE GOIPANY, 0F TRENTON, NEW JERSEY, A COREORATION 0F NEW JERSEY CENTRII'UGAL PUMP Application filed February 2, 1931. Serial 110.512,863. l

fisfactorily take care of pressures slightly in excess of 300 pounds per square inch at ordinary temperatures, Iit is rapidly destroyed when subjected to pressures of higher degree or pressures of lower degree when the tem-v perature is high. Under some circumstances, for example, the suction chamber of a multistage boiler feed pump may contain water having a temperature above 500o F. and a pressure as high as 800 pounds per square inch. The soft packing is unable to withstand this pressure or temperature.

It is the broad object of the present invention therefore to provide a means for pro-A tecting this suitable type of packing against the combined action of high temperatures and pressures existing both at the intake and discharge vends of centrifugal pumps, particularly of the multistage type.

ther objects relating to details of construction will be apparent from the following description read in conjunction with the accompanying drawings in which:

Fig. 1A is a vertical sectionalview, partly diagrammatic in form, of the lefthand suction end of a. multistage centrifugal pump and Fig. 1B is a similar view of the righthand Vdischarge end of the same.

The illustrated pump comprises a casing 2 preferably formed in upper and lower sections in the usual fashion in which is journalled the impeller shaft 4 through the medium of, suitable bearings (not shown) located at the ends of the casing. At each end where the shaft passes through the casing, it is provided with a sleeve 6' passing through Va suitable stuffing box containing soft packing 8 compreed into position within the stuffing box wall 10 by means of a gland 12,

the packing being backed up by an annularv member 14 engaglng a portion of the casing. As will be seen from the drawing, this'construction is duplicated at the two ends.

At the intake and discharge ends there are j respectively provided labyrinthine packings 16 and 18 providing tortuous passages through 'which liquid may leak only with considerable drop in pressuref` At the left- 'hand end of the pump inwardly of thelabyrinthine packing 16 is located the suction chamber 20 from which liquid is taken by the first-stage impeller 22 and passed thereby inthe usual fashion through the series of impellers, finally being discharged by the impeller 24 of the last stage into the discharge chamber 26. Leakage from the discharge chamber is controlled to some extent by the annular member 28 ixed to the shaft and running between an annular ring at its lnner sideand an adjustable shim 30 atl its outer side. Outside of the adjustable shim is a chamber 32 receiving leakage passing the member 28, this chamber 32 being connected through a balancing pipe 34 with the suction chamber 20. The labyrinthine packing 18 permits leakage from the chamber 32 with a considerable drop in pressure.

and bounded on its outer side by the member- 14. A similar chamber 38y on the discharge end of thev pump is outwardly bounded by the duplicate member 14.

Pipes

40 and 42 connect the chambers 36 and 38 to each other and to a relief valve 44 which may be set to pass liquid whenever the pressure exceeds a predetermined amount.

VLeading from the discharge of the rst stage impeller 22 is a pipe 46 serving to p ass liquid to a cooler 48 in which the temperature may be dropped from the region of up to 550 F. to 212 F. or lower. The liquid from the cooler passes through pipe 50 to a regulating valve 52 and thence through pipes'54 and 5G torannular chambers 58 and 60 surrounding the sleeves 6 and formed in the '62 and 64 communicating with the upper and lower sides respectively of a diaphragm with-` in a housing 66, which diaphragm is con-v nected to a valve controlling the flow through theregulating valve 5.2. A spring 68y normally urges the valve member within the valve 52 to unseated position in oppositionk to pressure exerted through pipe 62 'upon the top of the diaphragm. A vent may be provided to permit the discharge of liquid from the pipe 62.

The pressures in

chambers

20 and 32 are substantially equal. Similarly the pressures in chambers 36 and 38 are substantially equal by reason of their interconnection through

pipes

40 and 42. The pressures in 58 and 60 are also maintained substantially equal through the connections 54 and 56.` Accordingly, it-will be seen that the operations of the improved packing protecting means are similar at each end of the pump.

In the operation of the device the pressures and temperatures in the chamber 20 may be 4quite high. For example, the pressure mayv be in excess of 800 pounds per square inch and the temperature above 500 F. By reason of the labyrinthine packing 16, as leakage occurs from the chamber 20 into the chamber 36, the pressure will be very considerably reduced, the effective pressure bel ing controlled by the setting of the relief valve 44 which may, for example, considering a pressure of 800 pounds per square inch in the chamber .20, be set to discharge at 300 pounds per square inch. The temperature within chamber 36 however will be substantially as high as thatin the chamber 20. Accordingly, while the pressure is of a suitable amount which would not harm the packing, the temperature is' still excessive and provision is therefore made to prevent the apf plication of liquid at this high temperature to the soft packing.

` For this purpose the discharge from the first stage through pipe 46 is cooled by means of cooler 48 toa suitable l'ow temperature, for example, l`around 200 F. and is then passed through the regulating valve 52 which will effect a reduction of pressure so that the liquid entering chamber 58 through pipe 54 will have a low temperature and a pressure Just slightly in excess of the pressure in chamber 36. The regulating valve automaticallytakes care of this since the top of the diaphragm is connected to the chamber 58 and the bottom of the diaphragm to the chamber 36 and the spring 68 adjusted so as .to require a pressure in chamber 58 in excess of the pressure in chamber 36 by some predetermined amount. For example, the spring 68 may represent a difference in pressure of 25 pounds per square inch so that if the pressure in chamber 36 is 300 pounds the pressure in chamber 58 will be maintained.

about 325 pounds by reason of the fact that I the valve 52 will remain open until such larger pressure occurs.

By reason of the fact that the pressure in chamber 58 is greater than that in 36, a flow `0f liquidl from the former to the latter will Aequalizing or balancing pipe 34 insures similar initial conditions.

It will beclear that the cooling water may be provided from an outside source as, for instance, by means of a separate cold-water pump.

What I claim and desire to protect by Letters Patent is:

1. A centrifugal pump including a casing having intake and discharge passages a shaft mounted in the casing; packing for the shaft;

impeller means carried by the shaft; a chamber about the shaftv adjacent the impeller means arranged to contain liquid at hlgh temprature and' pressure; avsecond chamber about the yshaft between the packmg and first chamber; means providing .communication between the two chambers and operable to reduce the pressure of liquid owing from the first to the second; a third chamber about the shaft between the packing and the second chamber; and means for supplying the thu-d chamber with liquid at low temperature and at a pressure in excess of the pressure in the second'chamber, said last named means including a conduit between the impeller means and thethird chamber, and pressureresponsivemeans for controlling flow in said conduit to maintain the pressure of liquid in the third chamber higher than the pressure of liquid in the second chamber.J A

2. A cetrifugalvpump includinga casing having intake and discharge passages; a shaft mounted in the casing, packing for the shaft; impeller means carried by the shaft; a chamber about the shaft` adjacent the impeller means arranged to contain' liquid at high temperature and pressure; a second chamber about the shaft between the packing and first vlll,

chamber; means providing vcommunication cluding a conduit between the impeller means and the third chamber, and means for controlling flow in said conduit to maintain the pressure of liquid in the third chamber higher than the pressure `of liquid iii the second chamber, and connections between the flowcontrolling means and the second and third chambers arranged to automatically actuate the flow controlling means in accordance with the pressures in the second and third chambers.

3. A centrifugal pump including a casing having intake and discharge passages; a shaft mounted in the casing, packing for the shaft; impeller means carried by the shaft; a chamber about the shaft adjacent the impeller means arranged to contain liquid at high temperature and pressure; a second chamber about the shaft between the packing and first chamber; means providing communicationbetween the two chambers and operable to reduce the pressure of liquid llowing from the first to the second; a third chamber about the shaft between the packing and the second chamber: and means for supplying the third chamber with liquid at low temperature and at a pressure in excess of the pressure in the second chamber, said last named means including a conduit between the imneller means and the third chamber, means for cooling liquid passing through the conduit, and pressure responsive means for controlling flow in said conduit to maintain the pressure of liquid in the third chamber higher than the pressure ofliquid in the second chamber,

4. A centrifugal pump including a casing having intake and discharge passages; a shaft mounted -in the casing, packing for the shaft; impeller means carried by the shaft; aA chamber about the shaft adjacent the impeller means arranged to contain liquid at high temperature and pressure; a second chamber about the shaft between the packing and first chamber; means providing communication between the two chambers'and operable to reduce thepressure of liquid flowing from first to the second; va third chamber about the shaft between the packing and the second chamber; and means for supplying the third chamber with liquid at low temperature and at a pressure in excess of the pressure in the second chamber, said last named means including a conduit between the impeller means and the third chamber, means for cooling liquid passing through the conduit, and means for controlling flow in said conduit to maintain the pressure of liquid in the third chamber higher V than the pressure of liquid in the second chamber, and connections between the flow controlling means and the second and third chambers arranged to automatically actuatel the flow-controlling means in accordance with .the pressures in the second and. third cham- 5. A centrifugalpump including a casing;

having intake and discharge passages; a shaft mounted in the casing; packing for the shaft; impeller means carried by the shaft; a chamber about the shaft adjacent the impeller means arranged to contain liquid at high temperature and pressure; a second chamber about the shaft between the packing and first chamber; means providing communication between the two lchambers and operable to reduce the pressure of liquid flowing from the first to the' second; means for relieving pressure inthe second chamber; a. third chamber about the shaft between the packing and the second chamber; and means for supplying the third chamber with liquid at low teinperature and at a pressure in excess of the pressure in the second chamber:-

6. A centrifugal pump including a casing having intake and discharge passages; a shaft mounted in the casing; packing forl the shaft; impeller means carried by the shaft; a chamber about the shaft adjacent the iinpeller means arranged to contain liquid at' high temperature and pressure; a second shaft between the Vpacking and the second chamber; and means for supplying the third chamber with liquid at low temperature and at a pressure in excess of the pressure in the second chamber, said last named means including a conduit between the impell'er means and the third chamber, means for cooling liq-` Y uid passing through the conduit, and pressureresponsive means for controlling flow 1n said conduit to maintain the pressure of liquid in the third chamber higher than the 'pressure of liquid in the second chamber.

7. A centrifugal pump including a casing having intake and discharge passages; a shaft mounted in the casing; multistage impeller means carried by the shaft; packing arrangements on opposite sides of vthe im-.

peller means, each of said acking arrangeu ments including packing or the shaft, a chamber about the shaft adjacent the iinpeller meansA high temperature and pressure, chamber about the shaft between the packing and first chamber, means providing coin- -munication between the two chambers and operable to reduce the pressure of liquid flow-ing from the lirst to the second, and a third chamber about the shaft between the packing and the second chamber; and means for supplying each of the third chambers with liquid at low temperature and at a pressure in excess of the pressure in its corre-A sponding second chamber, said last mentioned means including a conduit between a lll() arranged to contain liquid at l a second` low pressure stage of the impeller means and both of the third chambers, and pressure responsive means for controlling flow in said ,conduit to maintain the pressure of liquid in each 'of the third chambers higher than the pressure of liquid in its correspondingsecond chamber.

8. A centrifugal pump including a casing having intake and discharge passages; a shaft mounted in the casin multistage impeller means carried bythe s aft; packing arrangements on opposite sides of the impeller means, each of said packing arrangements including packing for the shaft, a chamber about the shaft adjacent the impeller means arranged to contain liquid at high temperature and pressure, a second chamber about the shaft between the packing and first chamber, means providing communication between the'two chambers and operable to reduce the pressure of liquid flowing from the first to the second, and a thirdchamber about the shaft between the packing and the, second chamber; an equalizing connection between the first mentioned chambers; and means for supplying each of the third chambers with liquid at low temperature and at a pressure in excess of the pressure in its corresponding second chamber.

9. A centrifugal pump including a casing having intake and discharge passages; a shaft mounted in the casing; multistage impeller means carried by the shaft; packing arrangements on opposite sides of the impeller means, each of said packing arrangements including packing for the shaft, a chamber aboutv the shaft adjacent the im'- peller means arranged to contain liquid at high 'temperature and pressure, a secdnd chamber about the shaft between the packing andfirst chamber, means providing communication between the two'chambers and operable to reduce the pressure of liquid flowing from the first to the second, and a third chamber about the shaft between the packing and first chamber; means providing communication between the two chambers and operable to reduce the pressure ofliquid flowing from the first to the second; a third chamber about the shaft between the packing and the second chamber; and means for supplying the third chamber with liquid at low temperature and at a pressure in excess of the pressure in the second chamber, said last named means including a conduit between the impeller means and the third chamber, and means responsive to differences in pressure in the second and third chambers for controlling-fionr In said conduit to maintain the pressure of liquid in the third chamber higher than the pressure of liquid in the second chambern l1. centrifugal pump including a casing having intake and discharge passages; a shaft mounted in the casing; multistage impeller means carried by the shaft; packing arrangements on opposite-sides of the impeller means, each of said packing arrangements including packing for the shaft, a chamber about the shaft adjacent the impeller means arranged to contain liquid at high temperature and pressure, a second chamber about the shaft between the packing and first chamber means providing communication between the two chambers and operable to reduce the pressure of liquid flowing from the first to the second, and a third chamber about the shaft between the packing and the second chamber; and moans for supplying each of the third chambers with liquid at low temperature and at a pressure in excess of the pressure in its corresponding second chamber, said last mentioned means including a conduit between a low-pressure stage of the impeller means and both of the third chambers, and means responsive to differences in pressure in the second and third chambers for controlling flow in said conduit chamber about the shaft between the packing to maintain the pressure of liquid in each of and the second chamber; an equalizing connection between the first mentioned chambers; and means' for supplying each of the third chambers with liquid at low temperature and at a pressure in excess of the pressure in its corresponding second chamber, said last mentioned means including a conduit between a low-pressure -stage of the impeller means and both of the third chambers, and means in said conduit for maintaining the pressure of liquid in each of the third chambers higher than the pressure of liquid in its corresponding second chamber.

10. A centrifugal pump including a casing having intake and discharge passages; a shaft mounted in the casing; packing for the shaft; impeller means carried by the shaft; a chamber about -the shaft adjacent the impeller means arranged to contain liquid at high temperture and pressure; a second the third chambers higher than the pressure gf liquid in its corresponding second cham- 12. A centrifugal pump including a casing having intake and discharge passages; a shaft mounted in the casing; packing for the y shaft; impeller means carried by the shaft; a chamber about the shaft adjacent the impeller means arranged to contain liquid at high temperature and pressure; a second chamber about the shaft between the packing and first chamber; means providing communication between the two chambers and operable to reduce the pressure of liquid fiowing from the first to the second; a third chamber about the shaft vbetween the packingand the secat a pressure in excess of the pressure in the second chamber; and means responsive to sey, on this 30th day of Janna differences in pressure in the second and third chambers for controlling the supplyingV means to maintain the pressure of liquid in the third chamber higher than the pressure of liquid in the second chamber..

rIn testimony of which invention, I have hereunto set my hand,at Trenton, New Jer- 1931. ARVID PET RSON. a