High Temperature Gradient Gas Mixer for SCR Reactors
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Solution Overview
Problem
Gas turbine engine exhaust streams with high temperature gradients cause thermal stresses, leading to premature failure of mixers and duct systems when combined with air streams for SCR reactor processing, as the temperature differences result in stratification and non-uniform temperature profiles.
Innovation Solution
A mixing system within the duct system comprising supports, links, and wraps that allow thermal expansion and contraction without mechanical stress, facilitating uniform temperature mixing of exhaust and air streams by directing the momentum change of the streams through a hollow cavity, reducing thermal stresses and ensuring a uniform temperature profile within the predetermined range for effective NOx reduction in SCR reactors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional rigid mixers are used to mix exhaust stream and air stream, then mixing function is achieved, but thermal stresses cause premature failure due to temperature differences
Solution Approach 1:
The mixer is divided into multiple independent segments or components that can expand and contract independently in response to thermal gradients, preventing stress concentration and structural failure while maintaining mixing functionality
Solution Approach 2:
Different portions of the mixer are designed with different thermal expansion characteristics or insulation properties to accommodate local temperature variations, allowing each region to handle its specific thermal conditions without compromising overall structure
Solution Approach 3:
The mixer design incorporates materials or structures with varying thermal expansion coefficients to different regions, allowing the structure to adapt to temperature differences between exhaust stream and air stream without generating excessive thermal stress
2Productivity
If exhaust stream and air stream are combined in duct system, then SCR reactor processing is enabled, but streams stratify due to temperature difference
Solution Approach 1:
The mixer introduces mechanical vibration or turbulence to the stratified streams, disrupting the temperature-driven layering and promoting uniform mixing of exhaust and air streams before they enter the SCR reactor
Solution Approach 2:
The design replaces passive gravitational stratification with active mechanical mixing mechanisms, using rotating elements or baffles to forcibly blend the streams and achieve uniform composition and temperature distribution
3Strength
If rigid structure is used to maintain mixer geometry, then structural integrity is maintained, but thermal expansion causes mechanical stress
Solution Approach 1:
The mixer incorporates dynamic elements that can move or adjust in response to thermal expansion, maintaining structural integrity while accommodating dimensional changes through controlled movement rather than rigid constraint
Solution Approach 2:
The mixer uses flexible materials or thin-walled structures that can elastically deform to accommodate thermal expansion and contraction, maintaining structural integrity without generating excessive mechanical stress
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 mixing system effectively reduces mechanical/thermal stress and achieves a substantially uniform temperature profile, optimizing the NOx reduction reaction in SCR reactors by ensuring the mixed stream operates within the required temperature range, thereby extending the lifespan of the mixer and duct system components.
Implementation Method 1
The at least one wrap is oriented to change an effective direction of momentum of the exhaust stream and the air stream
Implementation Method 2
A mixing system within the duct system comprising supports, links, and wraps that allow thermal expansion and contraction without mechanical stress
Implementation Method 3
facilitating uniform temperature mixing of exhaust and air streams by directing the momentum change of the streams through a hollow cavity
Data Source
Figure 1
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AI summary
A mixing system (13) for a power generation system (9). The power generation system (9) includes a rotary machine (10), an exhaust processing system (15), and a duct system (11). The rotary machine (10) is configured to produce an exhaust stream (17). The exhaust processing system (15) is positioned to receive and process the exhaust stream (17). The duct system (11) is oriented to channel an air stream (21) to the exhaust processing system (15) and to channel the exhaust stream (17) from the rotary machine (10) to the exhaust processing system (15). The mixing system (13) is within the duct system (11). The mixing system (13) includes a plurality of supports (106), a plurality of links (110) extending between at least two of the supports (106), and at least one wrap (114) circumscribing at least two of the links (110). The at least one wrap (114) is oriented to change an effective direction of momentum of the exhaust stream (17) and the air stream (21).