Hydrogen Premixer Geometry for Fast Mixing and Flashback Prevention
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing premixers are unusable for combusting carbon-free fuels like hydrogen due to issues of lean blow out extinction and flashback, which are exacerbated by hydrogen's extreme reactivity and high flame speed.
Innovation Solution
A rapid mixing device with an elongated revolution body and multiple fuel channels that utilize co-flow jet injection, swirling, and optional pulsation to ensure homogeneous mixing and prevent flashback, featuring additive manufacturing for optimized geometry.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional premixers are used for hydrogen combustion, then mixing of fuel and air is achieved, but lean blow out extinction and flashback occur due to hydrogen's extreme reactivity and high flame speed
Solution Approach 1:
The mixing device segments the fuel injection into multiple separate channels distributed around the perimeter of the revolution body. Each channel independently injects fuel into the air stream, creating multiple discrete fuel jets that mix with air in a controlled manner. This segmentation prevents the formation of large fuel-rich zones that could lead to flashback while ensuring uniform distribution for stable combustion.
Solution Approach 2:
The invention transitions from conventional linear or planar mixing geometries to a three-dimensional revolution body with fuel channels distributed circumferentially. This dimensional change creates a radially symmetric mixing pattern that enhances fuel-air contact surface area and improves mixing efficiency while preventing localized accumulation of reactive mixtures that could cause flashback.
2Productivity
If hydrogen is used as fuel, then carbon-free combustion is achieved, but mixing speed must be extremely fast to prevent flashback
Solution Approach 1:
The mixing device performs preliminary mixing action by pre-distributing fuel through multiple channels before the main combustion process. The fuel is injected and begins mixing with air in controlled zones within the revolution body, creating a more uniform mixture prior to combustion. This preliminary mixing reduces the time required for homogeneous fuel-air mixture formation, preventing flashback while maintaining high combustion efficiency.
Solution Approach 2:
The invention utilizes fluid dynamic principles by designing the revolution body and fuel channels to create specific flow patterns. The geometry promotes turbulent mixing and enhances mass transfer between fuel and air streams. The pneumatic design ensures rapid mixing through controlled turbulence and flow interaction, achieving homogeneous mixing at high speeds suitable for hydrogen combustion.
3Stability of the object's composition
If fuel channels are distributed around the perimeter, then homogeneous mixing is improved, but device complexity increases
Solution Approach 1:
The revolution body serves multiple functions simultaneously: it acts as the structural housing, defines the flow path geometry, provides mounting for fuel channels, and creates the necessary flow patterns for mixing. This multi-functionality reduces the need for additional separate components, thereby limiting the increase in device complexity despite the sophisticated fuel distribution pattern required for homogeneous mixing.
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 device achieves efficient, low-emission combustion of hydrogen by ensuring rapid mixing and reducing the risk of flashback, maintaining stable combustion and minimizing NOx emissions.
Implementation Method 1
multiple fuel channels that utilize co-flow jet injection
Implementation Method 2
ensuring rapid mixing
Implementation Method 3
swirling
Implementation Method 4
optional pulsation
Implementation Method 5
efficient, low-emission combustion of hydrogen
Data Source
Figure 1~2a
Figure 2b~2c
Figure 3~4b
AI summary
1. A mixing device (1) for mixing an air stream with a liquid or gaseous highly reactive fuel, such as hydrogen, comprises an elongated revolution body (10) having an air inlet end (11), an air outlet end (12), and a hollow central space (13) that extends through the revolution body (10) along its elongation. The mixing device (1) comprises multiple fuel channels (14) arranged at the revolution body (10) and distributed around the perimeter of the revolution body (10), wherein the fuel channels (14) extend between the air inlet end (11) and the air outlet end (12) of the revolution body (10), wherein the fuel channels (14) have fuel inlet openings (15) near or at the air inlet end (11) of the revolution body (10) and fuel injection orifices (16) at the air outlet end (12) of the revolution body (10).