Steam Generator Air Bubble Removal and Heat Exchange Efficiency
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Solution Overview
Problem
In steam generators, the reduction in heat exchange efficiency due to air bubbles carrying over with supply water reduces the amount of heat transferred, leading to increased pressure loss and reduced water flow, especially in the hot side, which affects the overall heat transfer efficiency.
Innovation Solution
A steam generator design that includes a water supply unit at the upper portion of the annular channel to reduce supply water temperature entering the descending-side portion, and an air bubble removing member in the rising-side portion, such as a porous plate with through-holes, to prevent air bubbles from descending with the supply water, combined with optimized tube supporting plates and partitioning to enhance flow resistance and heat exchange.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If water is supplied in a full-scale manner to cool hot water and condense air bubbles, then air bubbles are removed, but supply water transfer pressure is lost and supply water does not flow smoothly in the hot side
Solution Approach 1:
The annular channel is divided into a rising-side portion and a descending-side portion, with water supply restricted to the descending-side portion. This segmentation allows air bubbles to be removed in the rising-side portion without compromising supply water flow in the hot side, as water is supplied separately to the descending-side portion for cooling and condensation.
Solution Approach 2:
Different regions of the annular channel are given different functions: the rising-side portion handles air bubble removal, while the descending-side portion handles water cooling and condensation. This local differentiation allows each region to optimize its specific function without interfering with overall water flow and pressure.
2Stress or pressure
If water is not supplied to the hot side to maintain supply water flow, then supply water transfer pressure is maintained, but air bubbles remain and carry-under occurs
Solution Approach 1:
The annular channel is segmented into rising-side and descending-side portions, with air bubble removal functionality assigned to the rising-side portion and water cooling functionality assigned to the descending-side portion. This allows air bubbles to be removed without requiring full-scale water supply that would compromise pressure.
Solution Approach 2:
The rising-side portion acts as an intermediary zone where air bubbles are removed from hot water before it mixes with supply water in the descending-side portion. This intermediary function allows air bubble removal without requiring extensive water supply that would reduce transfer pressure.
3Productivity
If supply water temperature is reduced in the descending-side portion to increase temperature difference, then heat exchange efficiency is improved, but air bubbles may carry-under with the supply water
Solution Approach 1:
The annular channel is segmented such that the rising-side portion handles air bubble removal while the descending-side portion handles heat exchange. This segmentation allows supply water to be cooled in the descending-side portion to maximize temperature difference with hot water, while air bubbles are removed in the rising-side portion before mixing, preventing carry-under.
Solution Approach 2:
Air bubbles are removed in advance in the rising-side portion before the supply water and hot water mix in the descending-side portion. This preliminary air bubble removal prevents carry-under during the subsequent heat exchange process, allowing aggressive cooling without contamination.
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 design increases heat exchange efficiency in the descending-side portion while maintaining efficiency in the rising-side portion, reducing pressure loss and preventing air bubble carry-under, thus improving the total heat transfer efficiency by creating a larger temperature difference and enhancing water flow.
Implementation Method 1
pressurized high-temperature coolant from a reactor flows through the heat transfer tubes and heats the heat transfer tubes, the water that is in contact with the outer surfaces of the heat transfer tubes is heated
Implementation Method 2
the water that is in contact with the outer surfaces of the heat transfer tubes is heated and moves upward while evaporating
Implementation Method 3
the water is separated by into steam and hot water
Implementation Method 4
the water is separated by into steam and hot water, and the hot water is returned to the annular channel whereas the steam is sent
Implementation Method 5
an air bubble removing member for removing air bubbles is provided in the annular channel
Implementation Method 6
air bubbles or is likely to generate air bubbles by involving ambient air
Data Source
AI summary
A steam generator is provided in which the total heat transfer efficiency can be improved by suppressing a reduction in the amount of heat exchange at an inlet side of heat transfer tubes while maintaining the effect of increasing the amount of heat exchange at an outlet side thereof. A steam generator (1) includes a heat transfer tube group (15) formed of a plurality of heat transfer tubes (13) secured to a tube plate (11); an annular channel (23) that is formed so as to cover the circumference of the heat transfer tube group (15) and that has an opening (25) for communicating with the heat transfer tube group (15) at a lower portion thereof; a water supply box (29) that is disposed at an upper portion of the annular channel (23) and that supplies water to a cold-side portion of the heat transfer tubes (13); and a steam/water separator (31) that is disposed above the heat transfer tube group (15) and that separates water heated while passing from the annular passage (23) along the circumference of the heat transfer tubes (13) into steam and hot water, in which a porous plate (35) for removing air bubbles is provided at an upper portion of the annular channel (23) in the hot-side portion of the heat transfer tubes (13).