Dry Gas Seal Pressure Staging for Turbomachine Axial Thrust
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Solution Overview
Problem
Turbomachines face challenges in axial load balancing due to static and dynamic forces exerted by the process medium, which require significant axial bearings, increasing costs and installation space.
Innovation Solution
The turbomachine design incorporates a dry gas seal with a flushing chamber and an intermediate chamber, featuring sealing surfaces at different radii, creating graded pressure levels to reduce axial thrust moments, and an overpressure system in the flushing chamber to compensate for dynamic forces, allowing for adjustable axial thrust compensation without dedicated axial bearings.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional sealing arrangements are used in turbomachines, then the axial bearings must be designed to absorb static and dynamic axial forces, but this increases costs and installation space
Solution Approach 1:
The patent introduces an intermediate chamber as a mediator between the high-pressure side and the sealing arrangement. This intermediate chamber, equipped with its own sealing surface at a smaller radius, acts as a buffer zone that helps balance axial thrust forces by creating a pressure distribution that counteracts the axial loads on the rotor, thereby reducing the burden on axial bearings
Solution Approach 2:
The patent changes the pressure parameter distribution by creating an intermediate chamber with controlled pressure between the high-pressure side and the sealing arrangement. By adjusting the pressure in this intermediate chamber through additional sealing surfaces at different radii, the axial thrust forces are modified to reduce the load on axial bearings
2Force
If sealing surfaces are arranged at different radii to create graded pressure levels, then axial thrust moments are reduced, but the sealing arrangement becomes more complex
Solution Approach 1:
The sealing arrangement is segmented into multiple sealing surfaces located at different radii (first sealing surface at first radius, second sealing surface at second radius, third sealing surface at third radius). This segmentation creates distinct pressure zones that generate balanced axial thrust moments, reducing the net axial load while distributing the sealing function across multiple components
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
This design reduces the need for extensive axial bearings, minimizes leakage losses, and effectively balances axial thrust forces, even in high-pressure and multi-stage turbomachines, thereby reducing costs and installation space.
Implementation Method 1
there are several graded pressure levels in the turbomachine at the transition from the housing interior to the high-pressure side of the turbo stage
Implementation Method 2
Axial thrust moments can occur at the pressure stages due to the differential pressure. In the case of shaft seals, these are essentially dependent on the effective radii of the sealing surfaces. This is also commonly referred to as the piston effect.
Implementation Method 3
the overpressure of the scavenging chamber can thus be used to at least partially compensate for this thrust moment
Data Source
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AI summary
The invention relates to a turbomachine (1) with a housing (2) and a rotor (3) rotatably mounted in the housing (2) about an axis of rotation (x), which comprises a turbo stage (6, 6') with a high-pressure side (9) and a low-pressure side (8). A dry gas seal (11) is arranged between the high-pressure side (9) and an interior space (10) of the housing, which has a purge chamber (11a) with an inner seal (11b) facing the high-pressure side (9) and an outer seal (11c) facing away from the high-pressure side (9). An intermediate chamber (14) is arranged between the dry gas seal (11) and the high-pressure side (9), which is separated from the high-pressure side (9) by an intermediate seal (15). The intermediate seal (15) has a first sealing surface (16a) arranged in a first radius (R1) about the axis of rotation (x). The inner seal (11b) has a second sealing surface (16b) arranged in a second radius (R2) around the axis of rotation (x).The outer seal (11c) has a third sealing surface (16a) arranged at a third radius (R3) around the axis of rotation (x). According to the invention, the first radius (R1) is smaller than the second radius (R2) and/or than the third radius (R3).