Multi-Stage Axial Bearing Control for Turbine Thrust Misalignment
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Solution Overview
Problem
Multi-stage axial bearings in steam turbines face misalignment issues due to uneven distribution of axial forces between discs, which existing designs fail to adequately balance, particularly in cases where a single disc is insufficient to counteract residual axial forces.
Innovation Solution
An axial bearing system with a stationary housing, a rotatable shaft, main and auxiliary discs, axial pads, temperature sensors, and a controller that adjusts pressurized actuation based on temperature differences between the discs to regulate axial force distribution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If a single disc is used in the axial bearing, then the structure is simple, but it cannot sufficiently counterbalance residual axial forces in cases with very low exhaust pressure or very high steam parameters
Solution Approach 1:
The axial bearing is divided into multiple discs (main disc and auxiliary disc) arranged axially at different positions. Each disc independently supports axial forces, allowing the system to handle larger residual axial forces that cannot be balanced by a single disc while maintaining reasonable individual disc dimensions.
2Force
If multiple discs are used in the axial bearing, then the axial force balancing capability is improved, but misalignments occur causing undesired irregularities in the distribution of axial forces between discs
Solution Approach 1:
Temperature sensors are installed on each disc to detect temperature differences between discs. The controller receives temperature signals and uses them as feedback to determine whether axial force distribution is uniform. When temperature difference exceeds a threshold, indicating misalignment, the controller activates the pressurized actuation to adjust the auxiliary disc position and restore proper alignment.
Solution Approach 2:
The auxiliary disc is designed with dynamic adjustability through pressurized actuation, allowing it to move axially in response to temperature-based feedback signals. This dynamic adjustment capability enables the system to compensate for misalignments and maintain uniform axial force distribution under varying operating conditions.
3Reliability
If temperature-based control with pressurized actuation is implemented, then axial force distribution is effectively regulated, but the device complexity increases
Solution Approach 1:
Temperature sensors monitor the thermal state of each disc and provide feedback signals to the controller. The controller compares temperature differences between discs and automatically activates the pressurized actuation when misalignment is detected, creating a closed-loop control system that maintains reliable axial force distribution.
Solution Approach 2:
A pressurized actuation system using hydraulic or pneumatic pressure is employed to adjust the position of the auxiliary disc. The pressurized fluid acts on a cavity behind the auxiliary disc, enabling precise and reliable axial position adjustment in response to temperature-based control signals.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Effectively balances thrust forces on the rotational shaft by dynamically adjusting axial forces through temperature-regulated pressurization, ensuring efficient compensation of axial forces and preventing misalignments.
Implementation Method 1
a plurality of temperature sensors for measuring the temperature of the main disc and the auxiliary disc
Implementation Method 2
the pressure in the pressurized cavity being variable for variating the axial force transmitted to the auxiliary disc
Data Source
AI summary
An axial bearing (10) system comprises: a stationary housing (2), a rotational shaft (3), at least one main disc (11) fixed to the rotational shaft (3), at least one auxiliary disc (12) fixed to the rotational shaft (3) and distanced from the main disc (11) along the axis of rotation (X), at least one axial main pad (15) connected to the stationary housing (2), at least one axial auxiliary pad (16) active on an annular face (12b) of the auxiliary disc (12), an axial force transmitted to the auxiliary disc (12) through the axial auxiliary pad (16) being regulatable through a pressurised actuation (18, 19, 21), a plurality of temperature sensors (22) for measuring the temperature of the main disc (11) and the auxiliary disc (12), a controller (25) connected to the pressurised actuation (18, 19, 21) and to the temperature sensors (22) for regulating the axial force transmitted to the auxiliary disc (12) based on the temperature of the main disc (11) and the auxiliary disc (12).