Lubricant drainage system for a hydrogen-cooled generator

Abstract

Hydrogen-cooled generator (2) comprising: a rotating element (8) containing a first end (10) extending to a second end (12); a first lubricant drain system (20) operationally connected to the first end (10) of the rotating element (8); and a second lubricant drain system (22) operationally connected to the second end (12) of the rotating element (8), each lubricant drain system (20, 22) comprising: a drain line (29, 110) having a first end section (30, 111) extending to a second end section (31, 112), the first end section (30, 111) being fluidically connected to the rotating element (8);a hydrogen degassing tank (34, 116) which is fluidically coupled to the second end section (31, 112) of the drain line (29, 110), wherein the hydrogen degassing tank (34, 116) includes a body section (36, 119) with an outer surface (38, 121) and an inner surface (39, 122) which defines a hollow interior (42, 119); a sensor (63, 150) which is operationally mounted in the respective hydrogen degassing tank (34, 116), wherein the sensor (63, 150) is configured and arranged to detect a boundary zone (47, 132) between a quantity of a lubricant (44, 128) and a quantity of a hydrogen gas (45, 129) in the hollow interior (42, 124); a Drain line (50, 137) which is fluidly coupled to the respective hydrogen degassing tank (34, 116), wherein the drain line (50, 137) has a first end section (52, 139) which is exposed in the hollow interior area (42, 124) and a second end section (53, 140);and a valve (58, 146) that is mounted in the respective drain line (50, 137) between the first and the second end section (52, 139; 53, 140), wherein the valve (58, 146) is configured to control the fluid flow through the drain line (50, 137); and a control device (70) which is operationally connected to the sensor (63, 150) in each hydrogen degassing tank (34, 116) and the valve (58, 146) in each drain line (50, 137), wherein the control device (70) is configured and arranged to selectively open each valve (58, 146), thereby enabling a portion of the lubricant quantity (44, 128) to flow out of the hollow interior (42, 124) of the respective hydrogen degassing tank (34, 116) when the boundary zone (47, 132) is located above the first end section (52, 139) of the respective drain line (50, 137);wherein the hydrogen degassing tank (34) of the first lubricant drain system (20) is a first hydrogen degassing tank (34) and the hydrogen degassing tank (116) of the second lubricant drain system (22) is a second hydrogen degassing tank (116), wherein the first hydrogen degassing tank (34) comprises a first riser pipe (80) with a first end (82) and a second end (84), the first end (82) extending into the hollow interior (42) of the first hydrogen degassing tank (34) above the first end section (52) of the drain pipe (50), and the second hydrogen degassing tank (116) comprises a second riser pipe (160) with a first end (162) and a second end (163), the first end (162) extending into the hollow interior (129) of the second hydrogen degassing tank (116). extends above the first end section (139) of the drain pipe (137);wherein the first riser pipe (80) contains a fluid siphon closure (89) which is fluidly connected to the second end (84) of the first riser pipe (80), and the second riser pipe (160) contains a float valve (170) which is fluidly connected to the second end (163) of the second riser pipe (160); and wherein the fluid siphon closure (89) is fluidly connected to the second riser pipe (160) upstream of the float valve (170).

Description

BACKGROUND OF THE INVENTIONThe subject matter disclosed herein relates to the field of hydrogen cooled generators, and more particularly to a lubricant discharge system for a hydrogen cooled generator.Hydrogen cooled generators include a sealing oil or lubricant discharge system that includes a degassing tank. The degassing tank allows entrained hydrogen to escape from the lubricant. After the hydrogen is discharged, the lubricant is supplied again to the generator. In operation, the lubricant flows along circumferential components of the generator and receives hydrogen before entering the degassing tank. In the degassing tank, the hydrogen escapes or rises from the lubricant. The lubricant collects and optionally flows via a riser and passes to a recycling tank. Before it reaches the recycling tank, the lubricant passes a float valve. During normal operating conditions, when the lubricant pressure is above 15 psi, the float valve prevents any hydrogen that can pass along with the lubricant via the riser from advancing to the recycle tank.During startup phases, when the lubricant pressure is below 5 psi, the float valve will not function properly. During such times, a manual override system is employed. In particular, during start-up or other low operating pressure times, an operator must manually operate a valve that blocks the lubricant from the recycle tank. The valve includes a sight glass that allows the operator to monitor lubricant flow. When the operator recognizes hydrogen (in the form of bubbles or foam) in the lubricant, the valve is adjusted to maintain a level of lubricant in the sight glass. Besides the need for manual operation, the above system allows lubricant having relatively high amounts of hydrogen to permeate to the recycle tank. That is, while the float valve prevents gaseous hydrogen from entering the recycle tank, some hydrogen gas is further carried in the hydrogen flowing over the riser. When the lubricant entering the riser is in contact with the hydrogen gas in the degassing tank, the amounts of hydrogen in the lubricant remain high.US 5 186 277 A discloses a hydrogen cooled generator having a rotary element and a lubricant discharge system comprising a discharge line, a hydrogen degassing tank, a sensor for detecting a boundary zone between an amount of lubricant and an amount of hydrogen gas inside the hydrogen degassing tank, a discharge line having a discharge valve therein, and a control unit operatively connected to the sensor and the discharge valve, the sensor causing actuation of the discharge valve when the level in the tank is too high.US 4 969 796 A discloses a hydrogen cooled generator comprising first and second lubricant discharge systems operatively connected to the first and second ends of a shaft of the generator and each comprising a hydrogen degassing tank, a tank discharge line and first and second riser extending into the interior of the respective hydrogen degassing tank. The riser pipes of the first and second lubricant discharge systems are connected to one another in terms of flow, wherein a fluid siphon closure is provided in the connection of the riser pipes.BRIEF DESCRIPTION OF THE INVENTIONAccording to the invention there is provided a hydrogen cooled generator having the features of independent claim 1. Particularly preferred embodiments of the invention are set forth in the dependent claims.These and other advantages and features will become more apparent from the following description taken in conjunction with the drawings.BRIEF DESCRIPTION OF THE DRAWINGSThe subject matter which is considered to be the invention is particularly pointed out and distinctly claimed in the claims at the conclusion of the specification. The foregoing and other features and advantages of the invention will become apparent from the following detailed description when taken in conjunction with the accompanying drawings, in which: FIG. 1 is a schematic view of a hydrogen cooled generator including a lubricant discharge system according to an example embodiment; and FIG. 2 is a block diagram illustrating a controller for the lubricant discharge system of FIG. 1.The detailed description explains embodiments of the invention together with advantages and features on the basis of an example with reference to the drawings.DETAILED DESCRIPTION OF THE INVENTIONReferring to FIG. 1, a hydrogen cooled generator constructed in accordance with an exemplary embodiment is indicated generally at 2. The hydrogen cooled generator 2 includes a body 4 having a rotating element or rotating shaft 8 which includes a first or turbine end 10 and a second or collector end 12. The turbine end 10 includes a first seal 14, while the collector end 12 includes a second seal 15. The first and second seals 14 and 15 require a lubricant, such as sealing oil, which is directed to a drain system in a manner described in more detail below. The sealing oil prevents hydrogen gas from escaping from the generator 2, in particular in a region around the first and second seals 14 and 15. In the illustrated exemplary embodiment, the hydrogen cooled generator 2 includes a first drain system 20 fluidly connected to the first seal 14 and a second drain system 22 fluidly connected to the second seal 15. As illustrated, the first drain system 20 includes a drain line 29 having a first end portion 30 extending to a second end portion 31. The first end portion 30 is fluidly connected to the first seal 14, while the second end portion 32 is fluidly connected to a hydrogen degassing tank 34. In a manner described in more detail below, the hydrogen degassing tank 34 provides a system for removing hydrogen gas entrained in a lubricant flowing through the hydrogen cooled generator 2. Specifically, hydrogen carried or contained in the sealing oil is removed or allowed to escape into the hydrogen degassing tank 34.The hydrogen degassing tank 34 includes a body portion 36 having an outer surface 38 and an inner surface 39 defining a hollow interior region 42. In the hollow interior 42 there is a quantity of lubricant 44, such as sealing oil, and a quantity of hydrogen gas. The lubricant quantity 44 is separated from the hydrogen gas quantity by a boundary zone 47. A drain line 50 provides a channel for draining a portion of the amount of lubricant 44 from the hollow interior 42. The drain conduit 50 includes a first end portion 52 exposed in the hollow interior 42. The first end portion 52 extends to a second end portion 53 via an intermediate portion 54 and the second end portion 53 is connected to a main drain passage 56 via a control valve 58. The control valve 58 is selectively actuated in a manner described in more detail below to allow a portion of the amount of lubricant 44 to drain from the hydrogen degassing tank 34.According to the exemplary embodiment, the lubricant discharge system includes a sensor 63 disposed in the hydrogen degassing tank 34. The sensor 63, illustrated in the form of a liquid level sensor, provides an indication of a position of the boundary zone 47 relative to the first end portion 52 of the drain line 50. Further, in accordance with the exemplary embodiment, the sensor 63 is operatively connected to a controller 70 which, as best illustrated in FIG. 2, is also connected to the valve 58. The controller 70 receives signals from the sensor 63 indicative of the position of the boundary zone 47 in the hydrogen degassing tank 34. When the sensor 63 signals that the boundary zone 47 is above the first end portion 52, the valve 58 is opened to allow a portion of the amount of lubricant 44 to flow to the main drain passage 56. The controller 70 opens the valve 58 to an extent to control the discharge of the lubricant from the hydrogen degassing tank 34. In particular, the sensor 63 continues to monitor the location of the boundary zone 47 as the lubricant flows to the main drain passage 56. In this arrangement, the control means 70 proportionally adjusts the opening amount of the valve 58 to maintain the lubricant in the hydrogen degassing tank 34 at a predetermined level.In the event that the valve 58 does not open for any reason, the lubricant discharge system 20 includes a riser 80 disposed in the hydrogen degassing tank 34. Riser 80 includes a first end 82 that extends into hollow interior 42 above first end portion 52. The first end 82 extends to a second end 84 via an intermediate portion 85. a fluid siphon seal 89 is provided at the second end 84. With this arrangement, in the event that the amount of lubricant 44 increases the first predetermined distance and reaches the first end 82 without the sensor 63 triggering actuation of the valve 58, a portion of the amount of lubricant 44 will flow through the riser 80 to the main drain passage 56 in a manner which will be described in greater detail below. It is further illustrated that the hydrogen degassing tank 34 includes, in addition to the drain line 50 and the riser 80, a purge line 92 that allows operators to purge a portion of the hydrogen gas 45 for analysis, and a manual purge channel 94 that allows an operator to manually drain the lubricant 44 from the hollow interior 42.In a similar manner as described above, the second lubricant drain system 22 includes a drain line 110 having a first end portion 111 extending to a second end portion 112. The first end portion 111 is fluidly coupled to the second seal 15, while the second end portion 112 is fluidly connected to a hydrogen degassing tank 116. The hydrogen degassing tank 116 includes a body portion 119 having an outer surface 121 and an inner surface 122 defining a hollow interior region 124. A quantity of lubricant 128 and a quantity of hydrogen gas 129 are located within the hollow interior region 124 and are separated from each other by a boundary zone 132. A drain line 137 provides a passage that allows a portion of the amount of lubricant 128 to pass to the main drain passage 56. The drain line 137 includes a first end portion 139 that extends across an intermediate portion 141 to a second end portion 140. The first end portion 139 extends into the hollow interior region 124, while the second end portion 140 is fluidly connected to a valve 146. In a similar manner to that described above, the valve 146 is selectively actuated to allow a portion of the amount of lubricant 128 to pass through the drain line 137 to the main drain passage 56.In a manner similar to that described above, the hydrogen degassing tank 116 includes a sensor 150 configured and arranged to detect a position of the boundary zone 132 with respect to the first end portion 139 of the drain line 137. The sensor 150 is operatively connected to the controller 70 and the valve 146. The controller 70 opens the valve 146 by an amount to control the discharge of the lubricant from the hydrogen degassing tank 116. In particular, the sensor 150 continues to monitor the location of the boundary zone 132 as the lubricant flows to the main drain passage 56. In this arrangement, the control means 70 proportionally adjusts the opening amount of the valve 146 to maintain the lubricant in the hydrogen degassing tank 116 at a predetermined level.The lubricant discharge system 22 is further illustrated as including a riser 160 fluidly connected to the hydrogen degassing tank 116. Riser 160 includes a first end 162 that extends into hollow interior 124 to a location above first end portion 139 of drain conduit 139. The first end 162 extends over an intermediate portion 164 to a second end 163. In the illustrated embodiment, the second end 163 is fluidly connected to a float valve 170. Similarly, as described above, the riser 160 serves as an auxiliary support for the controller 70. that is, in the event that the valve 146 is not opened when the boundary zone 132 reaches the first predetermined distance above the first end portion 139, the amount of lubricant continues to accumulate in the hollow interior region 124. Once the boundary zone 132 reaches the first end 162, a portion of the amount of lubricant flows into the riser 160 toward the float valve 170. The float valve 170 prevents gaseous hydrogen, which may pass through the riser 160, from reaching the main drain passage 56 in a manner known in the art. As further illustrated, according to the exemplary embodiment, fluid siphon closure 89 is connected to intermediate portion 164 of riser 160. In this manner, although both the first and second lubricant discharge systems 20 and 22 are coupled to the main discharge passage 56, the fluid siphon seal 89 separates the hydrogen degassing tank 34 from the hydrogen degassing tank 116. Finally, the hydrogen degassing tank 116 is illustrated as including a purge line 176, a manual drain channel 177, and a vent 179 fluidly connected to the float valve 170.At this point, it should be understood that the exemplary embodiments describe a system for determining a boundary zone between the amount of a lubricant and a hydrogen gas in a hydrogen degassing tank. When the boundary zone is at a predetermined level above an outlet from the degassing tank, a valve is automatically opened to allow the lubricant to flow to a main discharge passage and be returned to the hydrogen cooled generator 2. In this arrangement, the lubricant is removed from the hydrogen degassing tank below the boundary zone. As such, the discharged lubricant contains substantially no hydrogen gas. That is, unlike current systems where lubricant passes to the drain passage at the boundary zone, with the lubricant still containing an amount of hydrogen, the present invention removes the lubricant from a location spaced well below the boundary zone such that any (lubricant) passing through the drain passage contains little or no hydrogen. At this point, it should be understood that in addition to systems having multiple hydrogen degassing tanks physically connected together as illustrated, the present invention is also applicable to systems including hydrogen degassing tanks located remote from each other.While the invention has been described in detail in connection with only a limited number of embodiments, it should be readily understood that the invention is not limited to such disclosed embodiments. Rather, the invention may be modified to incorporate any number of changes, modifications, substitutions or equivalent arrangements not heretofore described, but which are within the scope and spirit of the invention. In addition, while various embodiments of the invention have been described, it is to be understood that aspects of the invention may include only some of the described embodiments. Accordingly, the invention is not to be considered as limited by the foregoing description, but is limited only by the scope of the appended claims.A hydrogen cooled generator 2 includes a lubricant discharge system 20, and the lubricant discharge system 20 includes a hydrogen degassing tank 34 having a hollow interior 42. A sensor 63 is operatively mounted in the hydrogen degassing tank 34. The sensor 63 is configured and arranged to sense a boundary zone 47 between an amount of lubricant and an amount of hydrogen gas in the hollow interior region 42. A drain line 50 is fluidly connected to the hydrogen degassing tank 34. The drain line 50 includes a first end portion 52 exposed in the hollow interior 42 and a second end portion 53. A controller 70 is operatively connected to the sensor 63 and the valve 58. The controller 70 is configured to selectively open the valve 58, thereby allowing a portion of the amount of lubricant to flow out of the hollow interior region 42 when the boundary zone 47 is above the first end portion 52 of the drain line 50.Parts List:2 Hydrogen cooled generator 4 Body 8 Rotating shaft 10 First / turbine side end 12 Second / collector side end 14 First bearing 15 Second bearing 20 First lubrication system 22 Second lubrication system 29 Discharge pipe 30 First end portion 32 Second end portion 34 Hydrogen degassing tank 36 Body portion 38 Outer surface 39 Inner surface 42 Hollow interior 44 Lubricant amount 45 H gas amount 47 Boundary zone 50 Discharge pipe 52 First end portion 53 Second end portion 54 Intermediate part 56 Main discharge passage 58 Valve 63 Sensor 70 Controllers 80 Riser pipe 82 First end 84 Second end 85 Intermediate portion 87 Cover 89 Fluid siphon cap 92 Purge pipe 94 Manual discharge passage 110 Discharge pipe 111 First end portion 112 Second end portion 116 Hydrogen degassing tank 119 Body portion 121 Outer surface 122 Inner surface 124 Hollow inner portion 128 Lubricant amount 129 Hydrogen gas amount 132 Boundary zone 137 Drain pipe 139 First end portion 140 Second end portion 142 Intermediate part 146 Valve 150 Sensor 160 Riser pipe 162 First end 163 Second end 164 Intermediate part 167 Cover 170 Float valve 176 Purge pipe 177 Manual drain passage 179 Vent float valve

Claims

A hydrogen cooled generator (2) comprising: a rotary member (8) including a first end (10) extending to a second end (12); a first lubricant drain system (20) operatively connected to the first end (10) of the rotary member (8) and a second lubricant drain system (22) operatively connected to the second end (12) of the rotary member (8), each lubricant drain system (20, 22) including: a drain line (29, 110) having a first end portion (30, 111) extending to a second end portion (31, 112), the first end portion (30, 111) being fluidly connected to the rotary member (8); a hydrogen degassing tank (34, 116) fluidly coupled to the second end portion (31, 112) of the discharge conduit (29, 110), the hydrogen degassing tank (34, 116) including a body portion (36, 119) having an outer surface (38, 121) and an inner surface (39, 122) defining a hollow interior region (42, 119); a sensor (63, 150) operatively mounted in the respective hydrogen degassing tank (34, 116), the sensor (63, 150) being configured and arranged to detect a boundary zone (47, 132) between an amount of lubricant (44, 128) and an amount of hydrogen gas (45, 129) in the hollow interior region (42, 124); a drain line (50, 137) fluidly coupled to the respective hydrogen degassing tank (34, 116), the drain line (50, 137) having a first end portion (52, 139) exposed in the hollow interior region (42, 124) and a second end portion (53, 140); and a valve (58, 146) mounted in the respective drain line (50, 137) between the first and second end portions (52, 139; 53, 140), the valve (58, 146) configured to control fluid flow through the drain line (50, 137); and a controller (70) operatively connected to the sensor (63, 150) in each hydrogen degassing tank (34, 116) and the valve (58, 146) in each drain line (50, 137), the controller (70) being arranged and arranged to selectively open each valve (58, 146), thereby allowing a portion of the amount of lubricant (44, 128) to flow out of the hollow interior (42, 124) of the respective hydrogen degassing tank (34, 116) when the boundary zone (47, 132) is above the first end portion (52, 139) of the respective drain line (50, 137); wherein the hydrogen degassing tank (34) of the first lubricant discharge system (20) is a first hydrogen degassing tank (34) and the hydrogen degassing tank (116) of the second lubricant discharge system (22) is a second hydrogen degassing tank (116), wherein the first hydrogen degassing tank (34) contains a first riser pipe (80) having a first end (82) and a second end (84), wherein the first end (82) extends into the hollow interior region (42) of the first hydrogen degassing tank (34) above the first end section (52) of the discharge pipe (50), and the second hydrogen degassing tank (116) contains a second riser pipe (160) having a first end (162) and a second end (163), wherein the first end (162) extends into the hollow interior (129) of the second hydrogen degassing tank (116) above the first end portion (139) of the drain line (137); wherein the first riser (80) includes a fluid siphon seal (89) fluidly connected to the second end (84) of the first riser (80) and the second riser (160) includes a float valve (170) fluidly connected to the second end (163) of the second riser (160); and wherein the fluid siphon seal (89) is fluidly connected to the second riser (160) upstream of the float valve (170).The hydrogen cooled generator (2) of claim 1, wherein the sensor (63, 150) is a liquid level sensor.The hydrogen cooled generator (2) of claim 1, wherein the controller (70) selectively opens the valve (158, 146) in a drain line (50, 137) when the boundary zone (47, 132) in the respective hydrogen degassing tank (34, 116) is above the first end portion (52, 139) of the drain line (50, 137) and below the first end of the respective riser (80, 160).The hydrogen cooled generator (2) of claim 1, wherein the first hydrogen degassing tank (34) is physically connected to the second hydrogen degassing tank (116).

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