US3342406A - Method for preventing damage by corrosion of the adjustable mechanism of guide blading of turbomachines and turbomachine with corrosion prevention device - Google Patents

Description

Sept. 19, 1967 H BAUMANN ET AL 3,342,406

' METHOD FOR PREVENTING DAMAGE BY CORROSION OF THE ADJUSTABLE MECHANISM OF GUIDE BLADING OF TURBOMACHINES AND TURBOMACHINE WITH CORROSION PREVENTION DEVICE 5 Sheets-Sheet 1 Filed May 20, 1965 INVENTORS Hans Baummnn P fier Schmidf-Theuner PM WCPWJQU ATTORNEYS H. BAUMANN ET AL 3,342,406

Sept. 19. 1967 METHOD FOR PREVENTING DAMAGE BY CORROSION OF THE ADJUSTABLE MECHANISM OF GUIDE BLADING OF TURBOMACHINES AND TURBOMACHINE WITH CORROSION PREVENTION DEVICE Y 5 Sheets-Sheet 2.

Filed May 20, 1965 INVENTORS Hans Baumcmn fkfier'5chnfldt-Theuner 1 /P JQL%&PMAV

ATTORNEYS Sept. 19, 1967 BAUMANN ET AL 3,342,406

METHOD FOR PREVENTING DAMAGE BY CORROSION OF THE ADJUSTABLE MECHANISM OF GUIDE BLADING OF TURBOMACHINES AND TURBOMACHINE WITH CORROSION PREVENTION DEVICE Filed May 20, 1965 5 Sheets-Sheet 3 12 f? 5 I -q a 5 "1o l l i n I i 5 j 4 INVENTORS HQhsBcLumQn 7 BY Peter SchmId-bflfi PM W 2 rm ATTORNEYs United States Patent 3,342,406 METHOD FOR PREVENTING DAMAGE BY COR- ROSION OF THE ADJUSTABLE MECHANISM OF GUIDE BLADING 0F TURBOMACHINES AND TURBOMACHINE WITH CORRQSION PREVEN- TION DEVICE Hans Baumann and Peter Schmidt-Theuner, Nussbaumen, Switzerland, assignors to Aktiengesellschaft Brown, Boveri & Cie., Baden, Switzerland, a joint-stock company Filed May 20, 1965, Ser. No. 457,450 Claims priority, application Switzerland, June 23, 1964, 8,201/ 64 6 Claims. (Cl. 230-114) ABSTRACT OF THE DISCLOSURE A turbomachine such as an axial flow air compressor is provided with adjustable guide vanes, and the adjusting mechanism for these vanes is located within a chamber surrounding the wall defining the air flow passageway in which the vaned rotor is located. To block inflow of dust and other contaminants from the air being compressed in the rotor housing around the stems of the guide vanes into the chamber containing the adjusting mechanism, air from the outlet end of the compressor is introduced into this chamber. Since this air is at a higher pressure than the air being compressed, it blocks but flow of air around the stems of the vanes into the chamber. Since this blocking air contains moisture and would otherwise cause corrosion of the vane adjusting mechanism if allowed to condense out on the various parts of the mechanism or on the walls of the chamber, means are provided to maintain its temperature above the dew point within the chamber. The blocking air within the chamber may be supplementarily heated or the walls of the chamber may be insulated or a heat barrier may be installed to prevent a loss of heat from the chamber.

The present invention concerns a method for preventing corrosion'damages on shift mechanisms for guide vanes in turbomachines, particularly in axial compressors with angularly adjustable guide vanes, as well as a turbomachine for carrying out this method.

In axial compressors with angularly adjustable guide vanes, the shift mechanism is frequently arranged in a chamber formed between the guide-vane carrier and the outer housing. In order to prevent the entrance'of dust through the bearing clearances of the guide vanes into this chamber, the latter is admitted with a blocking gas having the end pressure of the compressor. If the conveyed air at the end pressure of the compressor is introduced, for example, as a blocking gas into the shift chamber, corrosion phenomena will appear at the inlet side of the compressor guide vanes, due to condensation of the water carried along, because the compression of the conveyor medium increases not only the air pressure but also the partial vapor pressure and thus the dew point.

Since, on the other hand, the blade support is cooled by the intake air at the inlet to ambient temperature, and partly also the housing part surrounding the shift chamber, the temperature of the air returned into the chamber as blocking air drops below the dew point, so that condensate is formed, which has a corrosive effect. While with lower pressure ratios the vane carrier and the housing are sufficiently heated from the hot part of the pressure side to prevent these condensation phenomena, this separation of moisture appears on the vane carrier and on the housing at high pressure ratios, which leads to corrosion.

The object of the present invention is to eliminate these disadvantages.

The method according to the invention for preventing corrosion damages is characterized in that at least a part of the shift mechanism and the surrounding stationary parts are protected against cooling.

The turbomachine for carrying out the method according to the invention is characterized by means to prevent the cooling of stationary machine parts. Due to this measure, cooling of the dust blocking air below the dew point is avoided, so that no liquid is separated and corrosion is therefore prevented.

The foregoing as well as other objects and advantages inherent in the invention will become more apparent from the following detailed description of several embodiments thereof and from the accompanying drawings wherein:

FIG. 1 is a side view of an axial flow type turbocompressor with part of the casing broken away to show in section an embodiment of the invention wherein undesired cooling of the critical wall areas below the dew point is prevented by means of heat produced electrically by heater elements installed on the guide vane carrier;

FIG. 2 is a view similar to FIG. 1 illustrating an embodiment of the invention similar to that depicted in FIG. 1 but wherein the electrical heater units are installed in the wall of the housing surrounding the guide vane carrier;

FIG. 3 is a sectional view of a somewhat difierent embodiment wherein the dust blocking air introduced into the shift chamber is in a heated state and is guided along the critical wall areas of the shift chamber to prevent cooling thereof;

FIG. 4 is a sectional view of an embodiment wherein a layer of insulating material is applied to the inside wall of the end face of the housing defining the shift chamber;

FIG. 5 is a sectional view of an embodiment similar to FIG. 4 but wherein the insulating layer is applied to the outside wall of the chamber defining the shift chamber; and

FIG. 6 is a sectional view of still another embodiment wherein an insert of insulating material is arranged in the wall at the front end of the stationary vane carrier.

With reference now to the drawing and to FIG. 1 in particular, an axial-flow type turbo compressor with angularly adjustable guide vanes for compressing air is seen to include a compressor casing 1 which surrounds a vane carrier 2 provided with rows of guide vanes 6. The compressor rotor is indicated at 3 and is seen to be provided with rows of vanes 19. The inlet collar for air entering the compressor is indicated at 17. Vane carrier 2 serves to support the guide vanes in such manner as to permit them to be rotationally adjusted about their axes to different angular positions to suita particular operating condition. This adjustment is effected by means of shift levers 5 secured to shafts on which the guide vanes 6 are mounted, these shift levers for the rows of guide vanes being, in turn, actuated simultaneously by means of a shift member 4 to which one end of each lever is connected.

The compressor casing 1 is equipped with a pipe connection 7 for introducing a blocking medium, for example, compressed air, into chamber 10 between housing 14 and vane carrier 2 to exclude dust from the chamber, the dust blocking air being taken after the last compression stage.

In the vane carrier 2 are arranged electrical heating rods 8 which are provided with energy from the outside over connection plugs '9 in order to keep the end of the vane carrier 2 at the air inlet side and the adjoining parts of the compressor casing at a predetermined temperature. This has the result that the blocking gas entering the vane shift chamber 10 is not cooled below the dew point of the vapor carried along, which prevents the formation of condensation Water on the walls defining the chamber for the shift mechanism and on the shift mechanism 4, 5 for the guide vanes 6 as well as on the guide vanes themselves. The corrosion phenomena are thus prevented and the expensive shift mechanism of the guide vanes is protected.

As it can be seen from FIG. 2, the electrical heating rods 8 can also be arranged on the suction side of the side wall of the housing 14 in order to heat these parts and to prevent condensation on the housing parts cooled by the entering dust blocking medium.

FIG. 3 represents a solution where the dust blocking air, introduced into the shift chamber 10 through the connection 7, is heated and thus also used to heat the critical vane carrier and housing parts, the hot air being taken from the discharge outlet of the compressor (not represented). For this purpose is provided a baffle plate 11, which has the effect that the heated blocking air introduced at 7 flows along the critical parts of the walls, keeping them at a temperature exceeding the dew point temperature of the blocking air. In this manner condensation and thus corrosion phenomena, particularly on the shift mechanism 4, 5 are likewise prevented.

FIG. 4 shows a solution of the problem where cooling, particularly of the end faces of the compressor casing 1 and of the adjoining housing parts, is prevented by means of an insulating layer 12 held against the inner face of wall 14 by a casing 13, so that the temperatures of the wall parts which define the shift chamber 10, do not drop anywhere near the critical dew point temperature.

FIG. 5 shows a design similar to FIG. 4, but in this embodiment the insulating layer 12 is arranged on the outside of the compressor housing wall part 14. This solution has the advantage that the insulating material can be permeable to steam. However, application of an outer insulating layer is only possible with relativley large sized turbomachines since this insulating layer occupies a part, though only a small one, of the useful cross section of the air intake.

Due to the compression of the conveyor medium, the vane carrier 2 of the guide vanes 6 undergoes considerable heating on the pressure side. The generated heat flows to a great extent through the vane carrier 2 toward the inlet collar 17, which is cooled constantly by the entering air so that it is kept at a critical temperature below the condensation temperature. Thus, certain parts surrounding the shift chamber 10 would be likewise cooled below the dew point, which could lead to the dreaded condensation of water with the subsequent corrosion phenomena. To prevent this from happening, FIG. 6 represents a solution where the air inlet collar 17 is separated from the vane carrier 2 to establish a heat gap and an insulating insert 16 is arranged in the front end of the vane carrier 2 which functions as a heat barrier to prevent the heat of compression generated on the pressure side from flowing off into the collar 17. In this manner it is possible to keep the critical wall areas of the housing part 14 at a temperature above the dew point.

Naturally, it is also possible to combine the measures represented in the various embodiments according to FIGS. 1-6, for example, the measures according to FIGS. 1, 4, 5 and 6, or those according to FIGS. 3-6, 2-6 or 4-6, in a given case.

Thorough tests have shown that it is of advantage to provide both heating and insulation, for example, of the vane carrier and/or partly of the housing. The possibility of heating ensures protection against corrosion not only during the operation, but also during the standstill of the machine.

We claim:

1. A turbomachine such as an axial flow compressor comprising an outer casing, a rotor within said casing having rows of vanes, a guide vane carrier surrounding said rotor, said guide vane carrier supporting rows of adjustable guide vanes between which run the rows of vanes on said rotor, a shift member located in a chamber established between the outer casing and said guide vane carrier, mechanical connections between said shift member and said guide vanes for adjusting the angle of the latter as said shift member is actuated, means for introducing a dust-blocking water vapor containing gas into said chamber, and means for heating the wall parts defining said chamber to prevent cool-off to such temperature as would otherwise result in condensation of the water vapor on said Wall parts.

2. A turbomachine as defined in claim 1 wherein said means for heating said wall parts to prevent cool-off is constituted by electrical heater means carried by said wall parts.

3. A turbomachine such as an axial flow compressor comprising an outer casing, a rotor within said casing having rows of vanes, a guide vane carrier surrounding said rotor, said guide vane carrier supporting rows of adjustable guide vanes between which run the rows of vanes on said rotor, a shift member located in a chamber established between the outer casing and said guide vane carrier, mechanical connections between said shift memher and said guide vanes for adjusting the angle of the latter as said shift member is actuated, means for introducing a dust-blocking water vapor containing gas into said chamber, and a layer of insulation applied to the inside surface of the wall parts defining said chamber at the gas entrance end to said rotor to prevent cool-ofif to such temperature as would otherwise result in condensation of the water vapor content of said dust blocking gas in said chamber.

4. A turbomachine such as an axial flow compressor comprising an outer casing, a rotor within said casing having rows of vanes, a guide vane carrier surrounding said rotor, said guide vane carrier supporting rows of adjustable guide vanes between which run the rows of vanes on said rotor, a shift member located in a chamber established between the outer casing and said guide vane carrier, mechanical connections between said shift member and said guide vanes for adjusting the angle of the latter as said shift member is actuated, means for introducing a dust-blocking water vapor containing gas into said chamber, and a layer of insulation applied to the outside surface of the wall parts defining said chamber at the gas entrance end to said rotor to prevent coolofi to such temperature as would otherwise result in condensation of the water vapor content of said dust blocking gas in said chamber.

5. A turbomachine such as an axial flow compressor comprising an outer casing, a rotor within said casing having rows of vanes, a guide vane carrier surrounding said rotor, said guide vane carrier supporting rows of adjustable guide vanes between which run the rows of vanes on said rotor, a shift member located in a chamber established between the outer casing and said guide vane carrier, mechanical connections between said shift member and said guide vanes for adjusting the angle of the latter as said shift member is actuated, a bafile plate located in said chamber in spaced relation to the wall part thereof adjacent the gas entrance end to said rotor to establish a passageway therebetween, and means for passing a hot dust-blocking water vapor containing gas through said passageway to prevent cool-off of said wall part to such temperature as would otherwise result in condensation of the water vapor content on said wall part.

6. A turbomachine such as an axial flow compressor comprising an outer casing, a rotor within said casing having rows of vanes, a guide vane carrier surrounding said rotor, said guide vane carrier supporting rows of adjustable guide vanes between which run the rows of vanes on said rotor, a gas guiding inlet collar located at the gas entrance end to said rotor and which is spaced from the end of said guide vane carrier to establish a gap inhibiting heat transfer, a shift member located in a chamber established between the outer casing and said guide vane carrier, mechanical connections between said shift member and said guide vanes for adjusting the angle of the latter as said shift member is actuated, means for introducing a dust-blocking Water vapor containing gas into said chamber, and a heat insulating insert located Within that part of the wall of said guide vane carrier adjacent said inlet collar to prevent cool-01f of the carrier to such extent as would otherwise result in condensation thereon of the Water vapor content of said dust blocking gas.

References Cited UNITED STATES PATENTS 2,139,416 12/1938 McLane 230--114 2,404,275 7/ 1946 Clark et al. 230122 2,823,890 2/1958 Oechslin 230-133 FOREIGN PATENTS 109,472 1/1940 Australia.

708,400 5/1954 Great Britain.

864,604 4/ 1961 Great Britain.

364,581 11/ 1962 Switzerland.

DONLEY J. STOCKING, Primary Examiner. HENRY F. RADUAZO, Examiner.

Claims (1)

1. A TURBOMACHINE SUCH AS AN AXIAL FLOW COMPRESSOR COMPRISING AN OUTER CASING, A ROTOR WITHIN SAID CASING HAVING ROWS OF VANES, A GUIDE VANE CARRIER SURROUNDING SAID ROTOR, SAID GUIDE VANE CARRIER SUPPORTING ROWS OF ADJUSTABLE GUIDE VANES BETWEEN WHICH RUN THE ROWS OF VANES ON SAID ROTOR, A SHIFT MEMBER LOCATED IN A CHAMBER ESTABLISHED BETWEEN THE OUTER CASING AND SAID GUIDE VANE CARRIER, MECHANICAL CONNECTIONS BETWEEN SAID SHIFT MEMBER AND SAID GUIDE VANES FOR ADJUSTING THE ANGLE OF THE LATTER AS SAID SHIFT MEMBER IS ACTUATED, MEANS FOR INTRODUCING A DUST-BLOCKING WATER VAPOR CONTAINING GAS INTO SAID CHAMBER, AND MEANS FOR HEATING THE WALL PARTS DEFINING SAID CHAMBER TO PREVENT COOL-OFF TO SUCH TEMPERATURE AS WOULD OTHERWISE RESULTS IN CONDENSATION OF THE WATER VAPOR ON SAID WALL PARTS.

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