Steam Jet Air Ejector Boundary Layer Separation Reduction
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Solution Overview
Problem
Steam jet air ejectors in nuclear power plants face reduced capacity and efficiency due to boundary layer separation, leading to inadequate removal of non-condensable gases, which can result in reduced power plant output or shutdowns, necessitating frequent maintenance.
Innovation Solution
A steam jet air ejector assembly with a boundary layer separation reduction assembly, featuring vacuum ports along the discharge diffuser and a vacuum source to create a vacuum that withdraws fluid flow, coupled with a flow control device and controller to adjust vacuum levels based on operational characteristics, thereby reducing boundary layer separation and maintaining flow capacity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the steam jet air ejector operates under high cooling water temperatures, high condenser air leakage, and/or high discharge pressure, then the boundary layer separation occurs within the ejector, but the capacity and efficiency of the ejector decline
Solution Approach 1:
The patent extracts the harmful boundary layer by introducing a secondary fluid through injection ports that interact with the primary steam flow. This secondary fluid removes the separated boundary layer from the diffuser walls, preventing the harmful effects of boundary layer separation while maintaining ejector capacity under varying operating conditions
Solution Approach 2:
A secondary fluid acts as an intermediary substance introduced through injection ports into the diffuser. This intermediary fluid mediates between the primary steam flow and the boundary layer, facilitating the removal of separated boundary layer through fluid interaction without directly modifying the primary steam jet
2Productivity
If the ejector capacity is reduced due to boundary layer separation, then the removal of non-condensable gas from the condenser decreases, but power plant output is reduced or shutdown occurs
Solution Approach 1:
The system performs preliminary action by continuously introducing secondary fluid through injection ports to prevent boundary layer separation before it can significantly reduce ejector capacity. This proactive approach maintains steady flow conditions and ensures consistent non-condensable gas removal capability, preventing power plant shutdowns
3Ease of manufacture
If traditional maintenance procedures are initiated to locate and repair sources of decreased efficiency, then the power plant capacity is reduced, but maintenance costs and power generation limitations increase
Solution Approach 1:
The ejector system provides self-service by incorporating the secondary fluid injection mechanism that automatically corrects boundary layer separation issues during operation. This self-correcting capability eliminates the need for frequent shutdowns and maintenance interventions, allowing continuous power generation without manual repairs or capacity reductions
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 solution enhances the stability and efficiency of steam jet air ejectors by reducing boundary layer separation, maintaining flow capacity, and minimizing maintenance needs, thus improving power generation efficiency and reducing costs.
Implementation Method 1
A vacuum source and vacuum ports are provided for creating a vacuum for withdrawing a portion of a flow along an inner surface of the discharge diffuser
Implementation Method 2
A steam jet air ejector includes a boundary layer separation reduction assembly configured to remove a portion of the fluid flow along the inner surface of the discharge diffuser
Data Source
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AI summary
A boundary layer separation reduction assembly (129) for a steam jet air ejector (100) in a nuclear reactor having a discharge diffuser (122) with a plurality of vacuum ports (130) positioned along an inner surface (128) of the discharge diffuser (122) and a vacuum source (132) coupled to the vacuum ports (130).