Compressor Seal Gas Layout for Axial Thrust Reduction
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Solution Overview
Problem
Centrifugal compressors face high thrust forces that increase the load on thrust supporting members, necessitating higher sliding resistance and stronger components, which is undesirable.
Innovation Solution
A compressor design incorporating a rotary shaft, impellers, a casing, first and second seal portions, a gas supply path, and a gas outflow path, where the impeller includes a first and second impeller configuration, allowing the working fluid to act as a seal gas and reduce thrust force by differential pressure management.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If the thrust force is strong, then the impeller compression capability is improved, but the load on the thrust supporting member increases and sliding resistance increases
Solution Approach 1:
A seal gas is introduced into the seal portion between the impeller and casing to act as an intermediary medium. This seal gas generates pressure that counteracts the thrust force acting on the impeller, thereby reducing the load on the thrust supporting member and sliding resistance during rotation
Solution Approach 2:
The harmful thrust force is extracted and counterbalanced by introducing seal gas into the seal portion. The seal gas pressure is specifically designed to offset the axial thrust, separating the thrust support function from the main thrust bearing system and reducing energy loss from sliding resistance
2Force
If a separate seal gas system is provided, then thrust force is reduced, but device complexity increases
Solution Approach 1:
The seal gas system is merged with the working fluid system. The working fluid that has already been compressed by the impeller is redirected through a communication path to serve as the seal gas in the seal portion. This eliminates the need for a separate seal gas supply system while maintaining the thrust reduction benefit
Solution Approach 2:
The working fluid serves multiple functions: it is compressed by the impeller for the primary compression task, and then the same working fluid is utilized as seal gas in the seal portion to counteract thrust force. This multi-functional use of the working fluid simplifies the overall system by eliminating dedicated seal gas infrastructure
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 design effectively reduces thrust force, eliminates the need for separate seal gases, and optimizes energy use by integrating the working fluid into the seal system, thereby reducing operational costs and maintaining efficiency.
Implementation Method 1
a gas outflow path that is provided in the second seal portion and communicates with a pressure space having a pressure lower than that of the seal gas to allow at least some of the seal gas to flow out from the first seal portion to the pressure space
Implementation Method 2
a gas outflow path that is provided in the second seal portion and communicates with a pressure space having a pressure lower than that of the seal gas to allow at least some of the seal gas to flow out from the first seal portion to the pressure space
Data Source
Figure 1
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Figure 3
AI summary
A rotating machine (10) includes a first seal portion (50) that seals a portion between a rotary shaft (13) and a casing (11) with a seal gas, a second seal portion (60B) that is disposed between an impeller (14B) and the first seal portion (50) and seals a portion between the rotary shaft (13) and the casing (11), a gas supply path (100B) through which the seal gas is introduced into the first seal portion (50), and a gas outflow path (110) that is provided in the second seal portion (60B) and communicates with a pressure space having a pressure lower than that of the seal gas to allow at least some of the seal gas to flow out from the first seal portion (50) to the pressure space.