Liquid Tolerant Centrifugal Compressor Impeller Erosion Reduction
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Solution Overview
Problem
Centrifugal compressor impellers experience erosion due to liquid droplets in the gas flow, which is difficult to detect and leads to premature damage and reduced machine uptime, necessitating a method to reduce erosion without penalizing dry operating conditions.
Innovation Solution
The implementation of a converging-diverging bottleneck in the impeller's inlet zone to break up liquid droplets and reduce their mass and size, combined with shaping the internal passages to minimize normal acceleration and deviation of droplets, thereby reducing erosion on the hub surface.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the impeller is designed to receive gas flow at its inlet, then the compressor can operate efficiently during dry conditions, but the impeller surfaces are eroded by liquid droplets in the gas flow
Solution Approach 1:
The patent applies preliminary action by introducing a flow conditioning element at the impeller inlet that breaks up liquid droplets before they reach the impeller surfaces. This preliminary breakdown of droplets into smaller particles prevents the erosion damage that would otherwise occur during compressor operation, allowing efficient dry operation without the harmful erosion effect.
2Duration of action of stationary object
If erosion protection measures are implemented, then impeller lifetime is increased, but operation during dry conditions is excessively penalized
Solution Approach 1:
The patent applies local quality by designing a flow conditioning element with specific geometric features (such as ridges or baffles) that are strategically positioned to interact with liquid droplets only when present. The element's structure is optimized to affect droplet breakup while being transparent or minimal in its interaction with dry gas flow, thus protecting the impeller during wet conditions without penalizing dry operation efficiency.
3Reliability
If the impeller surfaces are exposed to liquid droplet collisions, then droplets erode the hub and blade surfaces, but the erosion is difficult to detect until severe damage occurs
Solution Approach 1:
The patent applies preliminary action by preventing erosion before it can cause severe damage. The flow conditioning element at the inlet breaks up droplets into smaller particles that lack the momentum to cause significant erosion, thereby maintaining impeller integrity throughout its service life without requiring difficult detection methods for early erosion signs.
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 approach increases the lifetime of impellers and uptime of rotary machines by effectively reducing erosion from liquid droplets, while maintaining efficient operation during dry conditions.
Implementation Method 1
a converging-diverging bottleneck is provided in an inlet zone of the impeller (120) so as to break up liquid droplets in an incoming flow of gas
Data Source
Figure 1
Figure 2A~2B
Figure 3~4
AI summary
In order to reduce erosion of an impeller (120,130) due to liquid droplets in an incoming flow of gas, the impeller (120,130) comprises converging-diverging bottlenecks; the incoming flow passes through the bottlenecks so that the speed of the gas at the inlet (122) of the impeller first suddenly and substantially increases and then suddenly and substantially decreases; furthermore, the impeller is configured so that, internally after its inlet, the incoming flow is deviated gradually in the meridional plane.