Steam-Water Riser Slits and Swirl Vane for Carryunder Reduction
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Solution Overview
Problem
Conventional steam-water separators in pressurized water reactors face inefficiencies due to the carryunder phenomenon, where water escapes with steam, reducing the separation efficiency.
Innovation Solution
A steam-water separator design featuring a steam-water riser pipe with horizontal slits at the upper end, a swirl vane, and a downcomer barrel forming an annular space, with specific aperture ratios, slit heights, and swirl vane angles to effectively separate steam and water, preventing carryover and carryunder.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional steam-water separator with a downcomer barrel and riser is used, then steam can be separated and discharged, but water escapes from the top of the downcomer barrel and is carried out with steam, reducing separation efficiency
Solution Approach 1:
The riser is segmented by forming multiple openings (slits) on its upper end surface, dividing the single riser outlet into multiple smaller discharge paths. This segmentation allows better control of the two-phase flow and prevents water from being carried over with steam by creating a more distributed and controlled discharge pattern through the openings.
Solution Approach 2:
Different regions of the riser are given different functions: the lower part handles two-phase flow upward movement, the upper end surface with openings controls water discharge, and the specific aperture ratio (30-70%) optimizes the local flow characteristics to separate steam and water effectively while preventing carryover.
2Productivity
If the aperture ratio of openings on the riser is too small, then water carryover is reduced, but steam discharge efficiency decreases; if too large, then steam discharge improves but water escapes more
Solution Approach 1:
The aperture ratio of the openings on the riser upper end surface is optimized to a specific range (30-70%). This parameter change balances the competing requirements: it is large enough to allow efficient steam discharge but small enough to prevent excessive water escape, achieving optimal separation efficiency within this defined range.
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
Enhances steam-water separating efficiency by ensuring steam is discharged through the orifice while water falls into the downcomer space, improving the reliability of the separation process.
Implementation Method 1
two-phase flow of the steam and the water generated by the steam generator is introduced into each riser at its lower end, moving upward, and is lifted upward while whirling by the swirl vane
Implementation Method 2
the water deposits on the inner wall face of the riser and moves upward while becoming a liquid film flow and the steam moves upward while whirling at the upper part of the riser
Implementation Method 3
the water escapes out of the riser through an opening between the upper end of the riser and the deck plate, flowing into the downcomer barrel and then flows downward
Implementation Method 4
The steam is delivered above the deck plate mainly through the orifice and the vent, and the water escapes out of the riser through an opening between the upper end of the riser and the deck plate
Data Source
Figure 1
Figure 2
Figure 3~4
AI summary
In a steam-water separator, a swirl vane (52) is provided inside a riser (51), an annular downcomer space (54) is formed by providing a downcomer barrel (53) outside the riser (51), a deck plate (55) is arranged above the riser (51) and the downcomer barrel (53) with a predetermined space therefrom, an orifice (56) and vents (57) are formed, and aperture ratios of plural slits (58a, 58b, 58c, and 58d) formed on the riser (51) are set at from 30% to 70%. Accordingly, the steam and the water is appropriately separated, and the separated steam is reliably discharged upward from the orifice while the separated water is allowed to reliably flow down through the downcomer space, thereby enhancing steam-water separating efficiency.