Boiling-Water Reactor Steam-Water Separator Design
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Solution Overview
Problem
In steam-water separators, particularly those used in natural circulation boiling-water reactors, the fluid containing steam and water experiences significant pressure loss due to changes in flow direction, leading to reduced flow and potential decreases in cooling performance.
Innovation Solution
The steam-water separator design includes a diffuser with an enlarged cross-sectional area, an inner and outer cylinder with discharge outlets, a protruding portion, and an opening to facilitate fluid flow, along with a swirler to enhance centrifugal separation, allowing for easier fluid passage and reduced pressure loss.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the fluid flow direction is changed in the annular flow channel, then steam-water separation is achieved, but pressure loss increases significantly
Solution Approach 1:
The annular flow channel is segmented into multiple sections: an upper section where steam-water separation occurs and a lower section where fluid is discharged. The separation function is localized to the upper part while the lower part handles discharge, reducing the need for sharp flow direction changes throughout the entire channel.
Solution Approach 2:
Instead of discharging fluid from the side walls of the annular flow channel as in conventional designs, this invention inverts the discharge approach by providing discharge outlets at the lower end of the annular flow channel, allowing fluid to exit downward while maintaining separation efficiency.
2Reliability
If steam flows into the annular flow channel due to high inlet quality, then separation occurs, but carry under increases and cooling performance decreases
Solution Approach 1:
Different sections of the steam-water separator are designed with different functional qualities: the upper annular flow channel section is optimized for steam-water separation with appropriate diameter and length, while the lower discharge section is designed for efficient water discharge. This local optimization ensures that each section performs its specific function effectively.
Solution Approach 2:
The design parameters of the annular flow channel (diameter, length, discharge outlet configuration) are optimized to change the flow characteristics and reduce carry under. By adjusting these parameters, the separator can handle high inlet quality conditions while maintaining effective cooling performance.
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 enables efficient fluid flow with reduced pressure loss, maintaining natural circulation and preventing carry-under issues, thereby enhancing cooling performance and power generation efficiency.
Implementation Method 1
swirl velocity is given to the fluid by a swirler (swirl vane) in a diffuser, and steam and water are separated by a centrifugal force using a gas-liquid density difference
Implementation Method 2
a diffuser with an enlarged cross-sectional area, an inner and outer cylinder with discharge outlets
Implementation Method 3
steam and water are separated by a centrifugal force using a gas-liquid density difference
Implementation Method 4
a circulation force due to a density difference between fluids inside and outside a shroud is increased, and cooling water flows into the core
Data Source
AI summary
Provided is a reactor that allows a fluid to easily flow. A reactor includes a reactor pressure vessel, a core provided in the reactor pressure vessel and loaded with a fuel assembly, and a steam-water separator provided in the reactor pressure vessel separates water and steam from a fluid containing the steam and the water generated in the core. The steam-water separator includes an annular flow channel through which the fluid flows from an upper side to a lower side and which opens to the lower side of the steam-water separator, and an opening that discharges air bubbles in the fluid flowing through the annular flow channel a side of the steam-water separator.