Catalytic Burner Mixing Unit for Hydrogen Combustion Control
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Solution Overview
Problem
Existing catalytic burners in auxiliary power units face issues with uncontrolled combustion of hydrogen and air upstream of the catalyst, leading to pipe damage and inhomogeneous mixing, which can result in hotspot formation and unwanted emissions.
Innovation Solution
A catalytic burner arrangement comprising a mixing unit and a catalytic burner unit, where the fuel and oxidant are mixed in a specific geometry to prevent uncontrolled ignition, featuring a pipe-shaped fuel-oxidant outlet that extends into the mixing chamber, and staggered inlets to ensure a homogeneous mixture and redirect fluid streams, preventing oxidant entry into the fuel inlet.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If fuel and oxidant are introduced directly into the reaction chamber without a mixing unit, then the device complexity is reduced, but uncontrolled combustion occurs upstream of the catalyst and inhomogeneous mixing results
Solution Approach 1:
The burner is divided into two separate functional units: a mixing unit where fuel and oxidant are combined, and a catalytic burner unit where controlled combustion occurs. This segmentation prevents uncontrolled combustion by ensuring mixing occurs in a dedicated chamber before the reaction chamber, while maintaining relatively simple overall structure through modular design.
2Device complexity
If fuel and oxidant are mixed in a simple configuration, then the device complexity is reduced, but inhomogeneous mixing occurs leading to hotspots in the catalyst
Solution Approach 1:
The mixing chamber employs curved streamlines and swirler elements that create rotational flow patterns. This curvature-induced mixing enhances homogeneity by promoting radial and axial mixing, ensuring uniform fuel-oxidant distribution before entering the catalytic burner, while avoiding complex mechanical mixing devices.
Solution Approach 2:
The mixing unit utilizes fluid dynamic principles where fuel and oxidant streams are introduced at specific angles and velocities to create natural turbulence and mixing. The swirler geometry converts pressure energy into rotational kinetic energy, enhancing mixing efficiency through pneumatic design rather than mechanical means.
3Manufacturing precision
If oxidant inlet is positioned before fuel inlet, then mixing is improved, but oxidant may enter the fuel inlet causing uncontrolled ignition
Solution Approach 1:
The mixing chamber is designed with three-dimensional flow paths where fuel and oxidant are introduced at different spatial locations and angles. The swirler creates radial and axial velocity components, allowing the oxidant to be positioned upstream in the flow direction while the chamber geometry prevents direct back-flow into the fuel inlet, solving the contradiction through spatial arrangement.
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 solution effectively prevents uncontrolled ignition and achieves a homogeneous mixture of air and fuel, reducing the risk of pipe damage and emissions, while ensuring efficient heat production for steam generation in fuel cell systems.
Implementation Method 1
The housing incorporates a catalyst, which is arranged downstream of the inlets, where hydrogen and air catalytically react with each other
Implementation Method 2
fuel and oxidant are guided in a swirl around the fuel-oxidant-outlet and are forced to stream upwards and to change stream direction
Implementation Method 3
air and excess hydrogen exiting the fuel cell stack are combusted over a catalyst to release energy
Data Source
Figure 1
Figure 2~3
Figure 4~5
AI summary
Catalytic Burner Arrangement Abstract: Disclosed is a catalytic burner arrangement (110) comprising at least a catalytic burner unit (10) with a housing (12) having a reaction chamber (13) in which a catalyst (14) is arranged, wherein the catalyst (14) is adapted to react a fuel, particularly a hydrogen containing fluid, with an oxidant, particularly air, for producing heat, said housing (12) having a fluid inlet (14) for supplying a fluid stream into the housing (12) and a fluid outlet (18) for exiting a fluid stream from the housing (12), and said catalytic burner arrangement (110) further comprises a mixing unit (20) forming a mixing chamber (26) in which fuel and oxidant are mixed, wherein said mixing device comprises a fuel inlet (22), an oxidant inlet (24) and an fuel-oxidant- mixture outlet, and wherein the fluid inlet (14) of the catalytic burner unit (10) merges with the fuel-oxidant- outlet (28) of the mixing unit (20) for transferring the fuel-oxidant-mixture from the mixing chamber (26) to the reaction chamber (13) of the catalytic burner unit (10) wherein said fuel inlet (22) of the mixing chamber (26) is arranged upstream of said oxidant inlet (24) of the mixing unit (20).