US1678067A

US1678067A - Turbine-cooling means

Info

Publication number: US1678067A
Application number: US66831A
Authority: US
Inventors: Carl J Lamb
Original assignee: Westinghouse Electric and Manufacturing Co
Current assignee: CBS Corp
Priority date: 1925-11-04
Filing date: 1925-11-04
Publication date: 1928-07-24
Anticipated expiration: 1945-07-24

Description

July 24, 1928. 1,678,067

c. J; LAMB wumsiun COOLING MEANS Filed Nov. 4, 1925 C .J Lo m b WITNESSES: lNVENTOR I ,M BY 7 ATTORNEY Patented July 24, 1928.

UNITED STATES- FF I I CARL J. LAMB, or IIIILAnELPHIA, PENNSYLVANIA, AssIoNoR' T0 WESTINGHOUSE Iv ELECTRIC AND MANUFACTURING GOMP 'NS A CORPORATION or PENNSYLVANIA.

TURBINE-COOLING :M ANs.

Application filed November 4, 1925. SerialNo.v 66,831.

1 Apparatus embodying features of my inof a turbine having my improved apparatus applied thereto. I In the operation ofpower plants, as is well known, there is ordinarily a variation of power demand in a days operation. During certaln' hours of the daymore power units must be put. in service to supply the, power-demand than .during other hours. It'

follows therefore that in adays operation tone or more .units, are. operated for a part" the other part. I

. time only andare shut down of the'time. r r lVhere elasticflui'd turbines are employed as'prime movers under the circumstances mentioned. difficulties have been encountered due tothe unequal distribution of. heat wit-b in the turbine casingtduring idle periods.

When theturbine is in operation, its rotor or portions thereof, assume the temperav ture ofthe motive fluid,rwhich may be up wards ofTOOf When the turbine is shut.

down and remains idle for several hours the temperature within the casing becomes highor at the top than at the bottom and the idle rotor cools off to a greater extent at the bottom than at the top. The lower part of the rotor being cooler than the upper part,

itcontracts to a greater degree so that. the rotor is caused to bow or bend upwardly due to the differences in temperature. If now the turbine is again started it will be found .to be decidedly out of balance and rubbing of. the parts is liableto occur if itis brought up to its designed speed before the heat-iof the rotor has again become evenly distrib-- utedthroughout its mass. Various ex pedients have been resorted to 111 orderto overcome the before-mentioned difficulty ,that most commonly employed being theprovisionof a separate motor with suitable gearingto keep the rotor ofthe idle 'turbineslowly rotating during its idle pevention is illustrated in the accompanying drawing forminga part of this specification, m which the single figure 1s a sectional view riods. This and other, expedients known to me are obviously expensive and cumbersome.

Another deleterious effect on the turbine which has been foundto follow intermittent,

periods of operation 'is that considerable condensation occurs within the casing during idle periods. Inasmuch as this condensation takes place in the .presenceof air.

serious corrosion of the turbine passages and bladlng follows," particularly when formed" of iron or steel, entailing overhauling and rebladingfbeforeit would otherwise benefcessary.

7 In my application, Serial Number 37,732,,., tiled Jun-e17, 1 925,entitled Turbine cooling means and assigned to the Westinghouse Electric '&. Manufacturing Company, there is disclosed a means for establlshing and maintainingfa circulationof air through the cas- 'ingof an idle turbine'in such a way as to bring about an evenly distributed f cooling of the turbine rotor. ,While the method therein disclosed has proven eminently satisfactory i'n service, I have found that, the same result maybemore quickly obtained by introducing air underla relatively high pressure" into the, casing of an idle turbine,

maintainingthe pressure therein-ata rela- Lively high value, and permitting circulation H of the" air therethroug'h by natural leakage through the glands and the air discharging apparatus of the condenser, where the turbine is running condensing. The air, which is provided under from 4 to 7 heat" more rapidly away from the rotor than where atmospheric pressure is employed and atmospheres I of pressure, hasuthe quality of conveying" the cooling of the rotor is thus more effectually done.

l Referring to the drawing for a better un derstanding of my invention, I show a turbine having a casing 10 and a rotor 11.

.Motivefluid for normally driving the turbine is admitted thereto through an inlet 12 and, is exhausted therefrom into a con denser' 13. In order "to prevent leakage alongthe turbine shaft into or out of the turbine casing when running there are provided at the ends of the rotor, sealing glands 14 and 16,. respectively. ,The sealing glands are of a well known type which operate by reason of centrifugal force acting'on a body of liquid to produce a sealing annulus therearound and arenot here described in detail I It is understood, however, that the sealing quality of this typeof gland depends upon the turbine being in operation and during idle periods a leakage of fluid is permitted therethrough.

Included in the condenser 13 is a battle 17' At 21 is shown a conduit which connects with a suitable source of air under pressure, not shown, but which may be from the an pressure source commonly maintained 111 power plants. The'conduit 21 is connected to the upper part ofthe turbinecasing at 22 and serves to admit air under a relatively high pressure into the casing for the purpose of cooling the rotor. A valve 23 is provided in the conduit 21 for the purpose of controlling the flow of air through the turbine casing. The conduit 21 should be of such size as to admit a sufficient quantity of air to the casing to permit its being maintained at a relatively high pressure against the natural leakage through the turbine glands and the throat of the ejector.

Inasmuch as dense air under a'relatively high pressure has the quality of conveying heat away very rapidly, the rotor is quickly cooled and the pressure does not have to be maintained within the casing for any great It should further be pointed periodof time. out that the conduit 21 is preferably con nected to the upper part of the turbine casing in order that'the cooling efiect take place in opposition to the natural flow of heat around the rotor, that isfrom the bottom upwardly. j H

From the foregoing description the operation of apparatus made in accordance with my invention will be apparent. Vhenthe turbine is stopped after being in operation, and the rotor is at approximately the tem perature of the motive fluid, the valve 23 in the conduit 21 is opened a. suflicient amount to admit a relatively large volume of air under 4 to 7 atmospheres of pressure into the turbine casing and to maintain the pressure of the air at a relatively high value against the natural leakage through the glands 14 and 16 and the air oft-take 18. Inasmuch as part of the air under pressure passes through the glands 14 to 16 its greater cooling effect is distributed over the upper part of the mass of the turbine rotor. A portion of the air flows downwardly around the turbine rotor out through the exhaust into the condenser 13 and from thence out through the air oil-take l8 and restricted throat 20, exerting a cooling effect around the entire periphery of the rotor. I have found that the dense air under a relatively high pressure sheets a quick cooling-of the turbine rotor and effectually prevents an unbalanced distortion of the rotor taking place when starting.

From the foregoing it will be apparent that I have devised an improved turbine are specifically set 'lortlrin the appended claims.

What I claim is t I 1. In a turbine, the combination of a casing, a rotor having a shaft and mounted within the casing, fluid 1 pressure sealing glands for preventing the flow of elastic fluid to or from the interiorof the casing when running, said glands permitting said flow when the turbine is idle, and means supplying airjunder pressure into the interior of the casing when the turbine isidle for cooling the rotor, whereby air circulates through "the turbi e "and leaks outwardly through the glands. 1'

2. In turbine, the. combination of'a casmg, a rotor havlng a shaft and mounted within the casing, fluid pressure sealing glands for preventing the flow of elastic fluid to-or from the nterior otthe cas ng when runn1ng,sa1d' glands permitting said flow when the turbine is idle, a condenser for H110 and means for introducing air under pres sure into the interior of the turbine, whereby said air circulates through the turbine the turbine, an air off-take for the condenser,

and outwardlythrough the air off-take.

3. In a turbine, the combination of a casing, a rotor having a shaft and mounted within the casing, a condenser for the turbine, an air oil-take from the condenser, and means for introducing air under pressure into the interior of the turbine in the upper part of the casing whereby said air circulates through the turbine ,and outwardly through the air off-take.

. 4. In a turbine, the "combination of a casing, a rotor having a shaft and mounted within the casing, a condenser for the tur bine and arranged below the turbine casing, an airoif-take for the condenser, and means for introducing air under pressure into the interior of the turbine, whereby said 'air circulates through the turbine and downwardly and outwardly through the air ofitake.

5. The method of maintaining an even distribution of heat throughout the mass of a turbine rotor during intermittently idle periods comprising introducing air under a relatively high pressure into the turbine casing, maintaining the air under a relatively high pressure therein, and permitting the leakage of air turbine glands.

6. The method of maintaining an even distribution of heat throughout the mass of a turbine rotor during intermittently idle periods comprising introducing air under a relatively high pressure into the turbine casing, maintaining the air under a relatively high pressure therein, and permitting the leakage of air from the casing through the turbine glands and air discharge apparatus of the condenser.

7. The method of maintaining an even distribution of heat throughout the mass of a turbine rotor during intermittently idle periods comprising introducing air under a pressure of from 4 to 7 atmospheres into the from the casing through the,

turbine casing, maintaining the air under a relatively high pressure therein, and permitting the leakage of air from the casing through the turbine lands.

8. The method 0 maintaining an even distribution of heat throughout the mass of a turbine rotor during intermittently idle periods comprising introducing air under a relatively high pressure into the turbine casing, maintaining the air undera relatively high pressure therein, and permitting the leakage of air from the casing through the air discharge apparatus of the condenser.

9. The method of maintaining an even distribution of heat throughout the mass of a turbine rotor during intermittently idle periods comprising introducing air under a relatively high pressure into the turbine casing, maintaining the air under a relatively high pressure therein, and permitting the leakage of air from the casing through the turbine glands and air discharge apparatus of the condenser.

In testimony whereof, I have hereunto subscribed my name this twenty-ninth day of October, 1925.

CARL J. LAMB.