Horizontal Once-Through Evaporator for HRSG Thermal Head Constraints
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Solution Overview
Problem
The existing heat recovery steam generators (HRSGs) with vertical evaporator tubes face design limitations due to thermal head constraints, requiring additional heating loops and maintenance, which increase costs and reduce productivity due to temperature imbalances and non-uniform fluid distribution.
Innovation Solution
A once-through evaporator design with substantially horizontal tubes that allow for uniform working fluid flow and counterflow heat transfer, eliminating the need for additional heating loops and reducing maintenance by ensuring all tubes experience a consistent heat profile.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If vertical evaporator tubes are used in HRSG, then the structure is simple and easy to manufacture, but thermal head limitations require additional heating loops and mixers which increase device complexity and maintenance needs
Solution Approach 1:
The patent inverts the conventional vertical tube arrangement by using substantially horizontal tubes inclined at 0-15 degrees. This inversion eliminates the need for vertical head space, allowing the evaporator to be installed in confined spaces while maintaining effective heat transfer through the inclined horizontal configuration.
Solution Approach 2:
The patent transitions from vertical to horizontal dimensioning of the evaporator tubes. By arranging tubes horizontally with a slight incline rather than vertically, the design utilizes the horizontal dimension for heat transfer while minimizing vertical space requirements, thereby eliminating the need for additional heating loops and mixing devices.
2Device complexity
If vertical evaporator tubes are used, then initial design is simpler, but temperature gradients and non-uniform fluid distribution require additional heating loops and mixers increasing operational complexity
Solution Approach 1:
The patent applies local quality by creating uniform heat distribution across all tubes through the inclined horizontal arrangement. Each tube receives consistent heat exposure along its length, ensuring uniform fluid heating and vapor generation without the temperature gradients that plague vertical tube designs, thereby eliminating the need for additional heating loops.
Solution Approach 2:
The patent changes the geometric parameter of tube orientation from vertical to substantially horizontal with a 0-15 degree incline. This parameter change fundamentally alters the heat transfer characteristics and fluid flow patterns, resulting in uniform heating throughout the evaporator and eliminating the need for complex mixing and re-heating systems.
3Temperature
If additional heating loops and mixers are added to vertical evaporator systems, then thermal limitations are overcome, but maintenance needs increase and productive functioning time decreases
Solution Approach 1:
The patent extracts and eliminates the unnecessary components (mixers and additional heating loops) from the vertical evaporator system. By using inclined horizontal tubes, the design achieves uniform heat distribution and continuous flow naturally, removing the need for these auxiliary components and thereby reducing maintenance requirements while maintaining effective temperature control.
4Ease of manufacture
If vertical evaporator tubes are used, then installation is straightforward, but space requirements increase due to vertical head limitations
Solution Approach 1:
The patent inverts the conventional vertical arrangement by using substantially horizontal tubes with a slight incline. This inversion transforms the space requirement from vertical head space to a compact horizontal footprint, allowing the evaporator to be installed in confined spaces with limited vertical clearance while maintaining installation simplicity.
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 enhances efficiency and reduces maintenance needs by ensuring uniform fluid distribution and heat transfer, minimizing temperature gradients and operational costs.
Implementation Method 1
a working fluid (e.g., water) is transported to an inlet manifold 105 from a source 106. The working fluid is fed from the inlet manifold 105 to an inlet header 112 and then to a first heat exchanger 104, where it is heated by hot gases from a furnace (not shown) flowing in the horizontal direction. The hot gases heat tube sections 104 and 108 disposed between the duct walls 111. A portion of the heated working fluid is converted to a vapor
Implementation Method 2
A portion of the heated working fluid is converted to a vapor and the mixture of the liquid and vaporous working fluid is transported to the outlet manifold 103
Data Source
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AI summary
Disclosed herein is a once-through evaporator comprising an inlet manifold; one or more inlet headers in fluid communication with the inlet manifold; one or more tube stacks, where each tube stack comprises one or more substantially horizontal evaporator tubes; the one or more tube stacks being in fluid communication with the one or more inlet headers; one or more outlet headers in fluid communication with one or more tube stacks; and an outlet manifold in fluid communication with the one or more outlet headers.