Steam Separation System with Moisture Trap for Nuclear Reactors
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Solution Overview
Problem
High two-phase flow velocity and high steam separator inlet moisture content lead to increased moisture carry-over in nuclear reactors, resulting in elevated radioactivity levels and maintenance costs due to flow-accelerated corrosion in the main steam line and turbine.
Innovation Solution
A steam separation system comprising steam separators and a steam dryer system with moisture traps, including a housing with a tortuous flow path and anti-fouling coatings, along with flow diverters to direct gas-liquid two-phase flows effectively through moisture traps for enhanced moisture removal.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If steam separator inlet moisture content is high, then the steam generation efficiency is improved, but moisture carry-over increases leading to radioactivity and corrosion problems
Solution Approach 1:
The steam separation system is divided into multiple functional segments: steam separators for initial liquid-gas separation, steam dryer bank assemblies with vanes for moisture removal, and moisture traps for final moisture capture. Each segment handles a specific aspect of moisture removal, allowing the system to process high-moisture steam effectively while preventing carry-over to the turbine.
Solution Approach 2:
The moisture trap acts as an intermediary component between the steam dryer bank assemblies and the turbine. It provides an additional stage of moisture removal using a tortuous flow path that causes liquid droplets to impinge on surfaces and be collected, serving as a protective barrier that prevents moisture carry-over while allowing steam generation to proceed at high efficiency.
2Speed
If two-phase flow velocity is high, then steam generation rate increases, but moisture carry-over increases causing radioactivity and maintenance cost issues
Solution Approach 1:
The system incorporates dynamic flow control elements including flow diverters that can redirect two-phase flow at different angles, and a tortuous flow path in the moisture trap that adapts to high-velocity flows. The chevron-shaped vanes in the steam dryer bank assemblies are designed to effectively remove moisture even at high flow velocities by creating optimal flow patterns that enhance liquid droplet separation.
3Reliability
If multiple steam separators and dryers are installed, then moisture removal efficiency is improved, but system complexity and maintenance costs increase
Solution Approach 1:
The moisture trap is integrated with the existing steam dryer bank assemblies, combining multiple moisture removal functions into a unified structure. The flow diverter is attached to the steam separator outlet to directly guide flow into the moisture trap, creating a compact integrated system that achieves high moisture removal efficiency without requiring completely separate, complex systems for each function.
4Object-affected harmful factors
If moisture carry-over is reduced, then radioactivity and corrosion are minimized, but system complexity increases due to additional components
Solution Approach 1:
The moisture trap is strategically positioned at the outlet of the steam dryer bank assemblies, focusing moisture removal efforts at the critical point where steam exits the separation system and enters the main steam line. The tortuous flow path and impingement surfaces are located specifically in regions where moisture carry-over is most problematic, providing targeted protection against radioactivity and corrosion without requiring complex systems throughout the entire steam generation pathway.
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 effectively reduces moisture carry-over, minimizing radioactivity and maintenance costs by improving moisture removal efficiency and reducing degradation in reactor components.
Implementation Method 1
an interior of the housing provides a tortuous flow path for the gas-liquid two-phase FS
Implementation Method 2
The moisture trap includes a housing having a plurality of inlet orifices, and an interior of the housing provides a tortuous flow path for the gas-liquid two-phase FS
Implementation Method 3
Each of the steam dryer bank assemblies is configured to separate liquid of the gas-liquid two-phase FS exiting the steam separators
Implementation Method 4
at least one of the steam separators includes a flow diverter at an outlet thereof, the flow diverter configured to divert the gas-liquid two-phase FS exiting the steam separator in a desired direction
Data Source
AI summary
In one embodiment, the steam separation system includes a plurality of steam separators configured to separate liquid from a gas-liquid two-phase flow stream; and a steam dryer system disposed above the steam separators. The steam dryer system includes a plurality of steam dryer bank assemblies and at least one moisture trap. Each of the steam dryer bank assemblies is configured to separate liquid of the gas-liquid two-phase flow stream exiting the steam separators. The moisture trap is disposed next to one of the steam dryer bank assemblies and is configured to remove liquid from the gas-liquid two-phase flow stream.