Compressor Seal Gas Distributor for Thermal Deformation
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Solution Overview
Problem
In turbo machines, particularly centrifugal compressors, the continuous supply of hot seal gas during temporary shutdowns can cause uneven heating and thermal deformation of the rotor shaft, leading to vibrations and potential damage upon startup, due to localized impingement and heat absorption.
Innovation Solution
A seal gas delivery system with a cylindrical seal gas distributor having multiple holes around the rotor shaft to evenly distribute seal gas, preventing hotspots and deformation, which can be retrofitted without altering the compressor's configuration or weight, and includes an option for inclined gas flow to enhance swirl and uniform heating.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If hot seal gas is continuously supplied to the dry gas seal during temporary shutdown, then seal performance is maintained, but uneven heating and thermal deformation of the rotor shaft occur
Solution Approach 1:
The seal gas supply is segmented from a single point delivery (port 30) to multiple distributed outlets (first and second seal gas outlets) positioned at different locations around the rotor shaft. This segmentation allows the hot seal gas to be distributed more evenly, preventing localized hotspots and thermal deformation while maintaining seal performance during temporary shutdowns.
Solution Approach 2:
Different regions of the rotor shaft receive seal gas through specifically positioned outlets tailored to their heating needs. The first seal gas outlet is positioned to address heating in a first region, while the second seal gas outlet addresses a second region, creating localized quality improvements in heat distribution matched to the specific thermal characteristics of each shaft region.
2Device complexity
If seal gas is delivered through a single port, then the delivery system is simple, but localized impingement causes hotspots and shaft deformation
Solution Approach 1:
The single seal gas delivery port is segmented into multiple outlets (first and second seal gas outlets) positioned at different locations. This increases device complexity slightly but dramatically improves manufacturing precision by preventing localized hotspots that cause shaft deformation, ensuring dimensional stability during and after temporary shutdowns.
3Productivity
If the compressor is restarted after temporary shutdown, then operation resumes, but vibrations occur due to shaft deformation from uneven heating
Solution Approach 1:
The seal gas outlets are positioned and configured to preemptively distribute hot seal gas evenly during the temporary shutdown period before restart. This preliminary action prevents the formation of thermal deformation and hotspots that would otherwise cause vibrations during subsequent startup, ensuring rotating assembly stability and maintaining productivity.
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
The system ensures even heat distribution around the rotor shaft, preventing thermal deformation and vibrations, facilitating easier compressor restarts and reducing the risk of damage, while maintaining existing operation and cost-effectiveness.
Implementation Method 1
heat generated by the compression process and other processes to which the process gas is subjected oftentimes generate a significant amount of heat which may be absorbed by the seal (process) gas
Implementation Method 2
the temperature of the seal gas may be further increased during a temporary compressor shutdown due to the absorption of residual heat, for example, from stationary compressor components
Implementation Method 3
seal gas may additionally be heated by a dedicated device, such as a heater or heat exchanger to aid in the prevention or suppression of condensation which may arise during or before the expansion of the seal gas within the dry gas seal
Implementation Method 4
prevention or suppression of condensation which may arise during or before the expansion of the seal gas
Implementation Method 5
grooves (not shown) in the dry gas rotor seal rings 26 and stator seal rings 28 may generate a fluid dynamic force to create a running gap which provides a sealing function without contact between the sealing rings
Implementation Method 6
one or more such hotspots may cause a deformation, e.g., bending, warping, etc., in the rotor shaft
Implementation Method 7
During subsequent compressor startup, a vibration in the rotating assembly may be induced as a consequence of the deformation
Data Source
Figure 1~2
Figure 3~4
Figure 5~6
AI summary
A seal gas delivery system for an end seal on a turbo machine rotor shaft includes a seal gas passageway (122) for delivering a seal gas to the end seal and a seal gas distributor (140) for receiving at least a portion of the seal gas from the seal gas passageway (122), the seal gas distributor (140) having a plurality of holes (160) for distributing the seal gas about the rotor shaft (120) during turbo machine standstill; the holes are located on a cylindrical surface and are typically arranged all around said rotor shaft, preferably regularly all around said rotor shaft.