DE102016215482A1 - Thrust bearing arrangement for mounting a turbine rotor - Google Patents

Abstract

The invention relates to a thrust bearing arrangement (1) for mounting a turbine rotor (2), wherein the thrust bearing arrangement (1) has a track disc (3) connected in a rotationally fixed manner to the turbine rotor (2), which is axially movable between two thrust bearings (4, 4) fixedly secured in a housing. 5) is arranged and wherein the respective gaps (6, 7) between the track disc (3) and the respective thrust bearing (4, 5) can be acted upon with lubricant. The respective amount of lubricant which is supplied to the respective gap (6, 7) between the track disc (3) and the respective thrust bearing (4, 5) is a function of the axial track disc position.

Description

The invention relates to a thrust bearing assembly for supporting a turbine rotor according to the preamble of independent claim 1. Furthermore, the invention relates to a method for operating such a thrust bearing assembly according to claim 6 and a turbomachine with such a thrust bearing assembly according to claim 8.

Turbines, for example gas or steam turbines, have a turbine blades equipped with rotatably mounted rotor. The turbine blades are impinged by a flow medium, in which case the kinetic energy of the flow medium is converted into rotational energy. Due to the flow of the flow medium, an axial force is exerted on the rotor. The resulting axial forces acting on the rotor are called axial thrust. This axial thrust causes the rotor to be displaced relative to the surrounding turbine housing. In order to avoid tarnishing of the turbine blade on the turbine housing and thus a possible destruction of essential turbine parts, the axial thrust or caused by this greater deflection of the rotor must be counteracted. For this purpose, the turbine has a thrust bearing arrangement for axial bearing of the rotor.

The thrust bearing assembly comprises a non-rotatably connected to the rotor track pulley, which is arranged axially movable between two in the axial direction left and right next to the track disc fixedly mounted in a housing radial bearings and thereby form a first and a second bearing side. Between the respective radial bearings and the track disc, a bearing gap is present, which can be acted upon by a lubricant. As a lubricant, a bearing oil is usually used. As bearings usually find segment bearings application.

The track disc is positioned as centrally as possible between the two radial bearings, i. Depending on the load point, the first or the second bearing side are loaded. The bearing sides are therefore symmetrical in terms of segment and lubricant feed geometry. The lubricant supplied to the respective bearing gaps is distributed 50% on the loaded bearing side and 50% on the unloaded bearing side, irrespective of the track disc position. Consequently, the unloaded bearing side is subjected to an excessive amount of lubricant, which causes increased lubricant consumption and greater friction losses in the bearings.

The object of the present invention is therefore to provide a thrust bearing assembly for supporting a turbine rotor, which has a reduced lubricant consumption and in which the friction losses are reduced in the bearings. It is another object of the present invention to provide a method for operating such a thrust bearing assembly.

The object is achieved in terms of thrust bearing assembly by the features of independent claim 1 and in terms of the method by the features of independent claim 6.

Further embodiments of the invention, which are used individually or in combination with each other, are the subject of the dependent claims.

The thrust bearing arrangement according to the invention for supporting a turbine rotor, wherein the thrust bearing assembly has a rotatably connected to the turbine rotor track disc, which is arranged axially movable between two fixedly mounted in a housing thrust bearing and wherein the respective gaps between the track disc and the respective thrust bearing are acted upon with lubricant records is characterized in that the respective amount of lubricant which is supplied to the respective gap between the track disc and the respective thrust bearing is a function of the axial track disc position.

The supply of lubricant quantity is thus for the first time no longer divided independently of the position of the track disc within the thrust bearing assembly into 50% each on first and 50% on the second bearing side. The lubricant supply is rather distributed as needed to the respective bearing side. This can save considerable amounts of lubricant. In addition, friction losses within the radial bearing assembly are significantly reduced due to the reduction of lubricant quantities.

An embodiment of the invention provides that increases with decreasing gap width, between the track disc and the respective radial bearing, the supplied amount of lubricant and with increasing gap width, between the track disc and the respective radial bearing, the supplied amount of lubricant is reduced. If the track disc is in its center position, the lubricant is distributed 50% to the first and 50% to the second bearing side. If there is a displacement of the track disc due to an axial thrust, then the gap, which is reduced due to the radial displacement, a larger amount of lubricant supplied as the gap, due to the axial displacement of the Enlarged track disc. Due to the higher supply of lubricant in the narrower gap, a compensation of the axial thrust is achieved and the track disc is moved again in the direction of its central position. This demand-based supply of lubricant to the respective gap results in a reduction of the lubricant throughput within the thrust bearing assembly compared to conventional thrust bearing assembly of up to 40%. With large thrust bearing arrangements, it is thus possible to save up to 200 liters per minute and more. Due to the lower supply of lubricant in each larger gap also the friction losses can be significantly reduced. First calculations have shown that the total power loss of the thrust bearing assembly can be reduced by up to 40% compared to conventional thrust bearing arrangements. With larger thrust bearing arrangements, it is thus possible to save up to 100 kilowatts and more.

An embodiment of the invention provides that there is a linear function between the supplied amount of lubricant and the gap width between the track disc and the respective radial bearing. This means that with decreasing gap width, the amount of lubricant supplied increases linearly and, in turn, the lubricant quantity for the opposing widened gap is reduced linearly. Overall, so that the total amount of lubricant supplied remains the same, this total amount of lubricant compared to a conventional thrust bearing assembly is significantly reduced.

A further embodiment of the invention provides that the track disc position is determined by means of an axial monitor. The axial vector is used as standard for most turbines, eliminating the need for additional sensors to determine the position of the pulley. As a result, the cost of such a thrust bearing assembly can be kept low.

A further embodiment of the invention provides that bearing oil is used as the lubricant. Bearing oil has a good lubricating property and a high temperature resistance.

• – Bestimmung der Spurscheibenposition innerhalb der Axiallageranordnung;
• – Ermittlung der axialen Auslenkung der Spurscheibe aus ihrer Mittenlage;
• – Zuführung von Schmiermittel zwischen dem jeweiligen Spalt, zwischen der Spurscheibe und dem jeweiligen Radiallager, wobei die zugeführte Schmierstoffmenge eine Funktion der Spurscheibenposition ist.

The method according to the invention for operating a thrust bearing arrangement is characterized by the following method steps:

• - Determining the pulley position within the thrust bearing assembly;
• - Determination of the axial deflection of the track disc from its center position;
• - Supply of lubricant between the respective gap, between the track disc and the respective radial bearing, wherein the supplied amount of lubricant is a function of the pulley position.

The method according to the invention thus differs from the prior art in that the lubricant quantity supply to the corresponding gaps between the track disc and the respective radial bearing depends on the corresponding position or the axial configuration of the track disc and does not take place as hitherto independently thereof.

The inventive method thus allows a targeted supply of lubricant to the respective gap, which can save considerable amounts of lubricant and the friction losses can be reduced within the radial bearing assembly.

An embodiment of the method for operating the thrust bearing assembly is characterized in that the amount of lubricant on the side increases with decreasing gap width and is reduced on the opposite side with increasing gap width. This results in a particularly high savings of lubricant, and minimizes friction losses.

Furthermore, the invention comprises a turbomachine with a corresponding thrust bearing arrangement.

The invention and further advantages of the invention will be described below with reference to the figures.

It shows:

- 1 the basic structure of a radial bearing assembly according to the invention;

- 2 the supply of lubricant quantities as a function of the axial position of the track disc within the radial bearing assembly.

The same or functionally identical components are cross-figurative provided with the same reference numerals. The illustrations in the figures are schematic and not necessarily true to scale.

1 shows the basic structure of a thrust bearing arrangement according to the invention for supporting a turbine rotor. The thrust bearing assembly 1 includes a track disc 3 the non-rotatable with the turbine rotor 2 connected is. The track disc 3 For this purpose, for example, in one piece with the turbine rotor 2 be formed or shrunk by means of a shrink connection on the turbine rotor. The track disc 3 is axially movable between two fixedly mounted in a housing radial bearings 4 . 5 arranged. The radial bearings 4 . 5 are designed as segment bearings. The radial bearings 4 . 5 have axial blocks 8th . 9 on that out White metal exist and wear or removal of the radial bearing when rubbing the track disc 3 should prevent. Between the respective radial bearing 4 . 5 and the wheel disc 3 is a gap 6 . 7 available. The gap 6 . 7 are supplied with a lubricant usually a bearing oil, so that the lowest possible friction between the moving and the stationary components exists. The position of the track disc 3 will have one in the 1 Axial monitor, not shown, monitored. The axial monitor is a sensor which determines the position of the track disc 3 can determine exactly. The track disc 3 should preferably be in its middle position during storage operation. The maximum axial displacement of the track disc between the two thrust bearings 4 . 5 is called axial play. The center position of the track disc 3 is characterized in that the columns 6 . 7 are the same size. As soon as the track disc 3 removed from their center position, measures must be taken, the track disc 3 to bring it back to its center position for a touch of the track disc 3 on one of the thrust bearings 4 . 5 to prevent. For this lubricant is in the column 6 . 7 between the radial bearings 4 . 5 and the wheel disc 3 introduced and thus generates an axial force, which counteracts the axial thrust, which is responsible for the axial displacement. The respective amount of lubricant, which the respective gap 6 . 7 between the track disc 3 and the respective radial bearing 4 . 5 is supplied is a function of the pulley position. At the center of the pulley position, the two bearing sides and thus the respective columns 6 . 7 each supplied the same amount of lubricant. Moves the track disc 3 due to an axial thrust in the direction of the first bearing side and thus reduces the first gap 7 , so is on this side of the thrust bearing assembly 1 supplied more lubricant and at the same time the amount of lubricant supplied to the second gap 6 reduced. As a result, an axial force is generated, which counteracts the axial thrust and the track disc 3 brings back in their midst situation. Due to the need-based supply of lubricant arise over the prior art in which two columns, left and right of the track disc 3 each supplied with the same amount of lubricant are significant advantages. On the one hand, due to the reduction in the amount of lubricant on the unloaded side (larger gap) a significant amount of lubricant can be saved. The lubricant throughput can be reduced by up to 40% compared to conventional designs. With a larger thrust bearing can thus be saved 200 liters per minute and more. At the same time, the frictional losses in the thrust bearing assembly are also reduced due to the lower filling of the gap of the unloaded bearing side. Initial calculations have shown that the axial bearing arrangement according to the invention makes it possible to reduce the total power loss of the thrust bearing arrangement by up to 40%, which may be 100 kilowatts or more for larger thrust bearings.

2 shows a diagram representing the lubricant flow rate through the respective bearing side as a function of the pulley position. Bearing side 1 denotes the bearing side located in the axial direction right of the track disc and bearing side 2 located on the left of the track disc bearing side. With a central track disc position, the gap is equal to the left and right sides. With a shift of the track disc to the left, the gap on the left side decreases and at the same time the gap on the right side increases. When the track disc is shifted to the right, the gap on the right side decreases while the gap on the left side increases. If an axial displacement of the track disc position from the center position is detected by the axial straightener, then the quantity of lubricant which is supplied to the respective gap is changed accordingly, depending on the direction of the axial displacement. When shifting the track disc to the left side, for example, the bearing gap on the left bearing side more lubricant is supplied, while reducing the amount of lubricant on the opposite right bearing side. As a result, an axial force is generated, which shifts the track disc again in the direction of its center position. If the track disc is in its center position, then 50% of the total lubricant quantity is supplied to both sides of the bearing. In order to ensure adequate lubrication of the respective bearing side, each bearing side must always be supplied with a minimal amount of lubricant, ie even with a maximum displacement of the track disc in one direction must be supplied to the opposite gap a certain amount of lubricant. This should preferably not be less than 10% of the total lubricant quantity. The im 2 shown linear control of the lubricant flow has shown a good controllability of the axial position of the track disc. In principle, however, the invention is not limited to a linear function. It is also conceivable any other function of the amount of lubricant as a function of the pulley position within the thrust bearing assembly.

In summary, it can be stated that the thrust bearing assembly according to the invention, due to their need-based supply of lubricant to the respective bearing sides a significant saving of oil flow to the thrust bearing arrangement allows whereby large amounts of lubricant can be saved, while reducing the frictional losses can be realized at the same time significant reduction in overall power loss.

Claims (8)

Thrust bearing arrangement ( 1 ) for supporting a turbine rotor ( 2 ), wherein the thrust bearing assembly ( 1 ) a rotationally fixed with the turbine rotor ( 2 ) connected track disc ( 3 ), which axially movable between two fixedly mounted in a housing thrust bearings ( 4 . 5 ) and the respective column ( 6 . 7 ) between the track disc ( 3 ) and the respective thrust bearing ( 4 . 5 ) can be acted upon with lubricant, characterized in that the respective amount of lubricant, which the respective gap ( 6 . 7 ) between the track disc ( 3 ) and the respective thrust bearing ( 4 . 5 ) is a function of the axial track disc position. Thrust bearing arrangement ( 1 ) according to claim 1, characterized in that with decreasing gap ( 6 . 7 ), between the track disc ( 3 ) and the respective thrust bearing ( 4 . 5 ), increases the amount of lubricant supplied and with increasing gap ( 6 . 7 ), between the track disc ( 3 ) and the respective thrust bearing ( 4 . 5 ), the amount of lubricant supplied is reduced. Thrust bearing arrangement ( 1 ) according to claim 1 or 2, characterized in that a linear function between the supplied amount of lubricant and the gap width between the track disc ( 3 ) and the respective thrust bearing ( 4 . 5 ) consists. Thrust bearing arrangement ( 1 ) according to one of the preceding claims, characterized in that the track disc position is determined by means of an axial guard. Thrust bearing arrangement ( 1 ) according to one of the preceding claims, characterized in that bearing oil is used as the lubricant. Method for operating a thrust bearing assembly ( 1 ) according to one of claims 1 to 5, characterized by the following method steps: - Determining the track disc position - Determining the axial deflection of the track disc ( 3 ) from its center position - supply of lubricant between the respective gap ( 6 . 7 ), between the track disc ( 3 ) and the respective thrust bearing ( 4 . 5 ), wherein the amount of lubricant supplied is a function of the pulley position. Method for operating a thrust bearing assembly ( 1 ) according to claim 6, characterized in that the amount of lubricant on the side increases with decreasing gap width and is reduced on the opposite side with increasing gap width. Turbomachine, characterized in that the turbomachine has a thrust bearing arrangement ( 1 ) according to one of claims 1 to 5.

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