Mini-Tube Air-Cooled Steam Condenser for Low Pressure Drop
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Solution Overview
Problem
Current large scale field erected air cooled industrial steam condensers have limited thermal capacity and require significant material and labor for construction, with existing designs not effectively addressing the removal of non-condensable gases and optimizing steam pressure drop.
Innovation Solution
A new tube design with reduced cross-sectional height and optimized fin arrangement, combined with a novel configuration of primary and secondary condensers in a V-shape arrangement, reduces material costs and increases thermal capacity while allowing for easier shipment and minimal field welding.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the tube cross-sectional height is reduced to less than 10 mm, then thermal capacity increases by 30% and material costs decrease, but the steam velocity and pressure drop must be optimized to maintain effective heat transfer
Solution Approach 1:
The patent applies parameter changes by reducing the tube cross-sectional height from the conventional 18.7 mm to less than 10 mm (specifically 4-10 mm in preferred embodiments). This dimensional parameter change increases thermal capacity by 30% while requiring optimization of steam velocity parameters to maintain effective heat transfer despite the smaller cross-section
Solution Approach 2:
The patent implements local quality by creating different tube geometries for different functional requirements. The mini-tubes have reduced height but maintain adequate width (200 mm air travel length) to balance heat transfer efficiency with pressure drop considerations, allowing each tube to be locally optimized for its specific heat exchange function
2Ease of manufacture
If tubes are shortened to fit in shipping containers with factory-welded manifolds, then field welding labor decreases, but the reduced surface area lowers thermal capacity by about 3%
Solution Approach 1:
The patent overcomes the thermal capacity loss from shortened tubes by changing the tube cross-sectional parameters. Instead of using conventional 18.7 mm height tubes, the mini-tubes use reduced height (4-10 mm) with optimized width, allowing more tubes to be packed in the same space while maintaining or increasing total heat transfer surface area
Solution Approach 2:
The patent transitions from optimizing tube length to optimizing tube cross-sectional dimensions. By reducing the height dimension while maintaining the width dimension, the design achieves better space utilization in the vertical dimension while preserving heat transfer area through increased tube density
3Productivity
If 1st stage condenser bundles are used for efficient steam condensation, then heat transfer efficiency increases, but non-condensable gases accumulate and require additional 2nd stage bundles
Solution Approach 1:
The patent applies segmentation by dividing the condenser system into multiple passes or stages. The mini-tube design enables effective condensation in the first pass while incorporating provisions for subsequent passes to handle non-condensable gases, separating the condensation function from the gas removal function into distinct operational stages
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 new design achieves a 30% increase in efficiency and up to 33% gain in steam condensing capacity with reduced material and labor costs, while minimizing field welding and optimizing heat exchange area per shipping container unit.
Implementation Method 1
The fins are usually 18.5 mm tall, spaced at 11 fins per inch. The fin surface has a wavy pattern to enhance heat transfer and help fin stiffness.
Implementation Method 2
Fins are brazed to both flat sides of each tube.
Implementation Method 3
For summer ambient conditions, maximum steam velocity through the tubes can typically be as high as 28 mps, and more typically 23 to 25 mps.
Data Source
AI summary
Large scale field erected air cooled industrial steam condenser having 10 heat exchanger bundles per cell arranged in five pairs in a V-shape, each heat exchanger bundle having four primary heat exchangers and four secondary heat exchangers in which each secondary heat exchanger is paired with a single primary heat exchanger. Four primary condensers are arranged such that the tubes are horizontal, while the inlet steam manifolds at one end of the tubes are perpendicular to the primary condenser tubes, i.e., parallel to the transverse axis of the bundle. Steam enters the small inlet steam manifolds from below. Cross-sectional dimensions of the tubes are 200 mm wide with a cross-section height of less than 10 mm with fins that are 10 mm in height, arranged at 9 to 12 fins per inch.