Multi-layer Flame Screen Burner Assembly for Combustion Control
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Solution Overview
Problem
Current flame screens for burners, especially those using small apertures or fibrous materials, face issues with high pressure loss, increased costs, and susceptibility to blockages, while traditional pressed metal designs are unreliable due to temperature changes and require intricate shaping.
Innovation Solution
A multi-layer flame screen burner assembly using thin sheet metal plates with specific finger and slot configurations, and gas distribution plates to control flame patterns and stability, allowing for efficient heat exchange and reduced blockages, with options for various configurations such as planar, circular, or rectangular shapes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If very small apertures are used in a flame screen, then flame control and safety are improved, but pressure loss increases and system cost increases
Solution Approach 1:
The flame screen is segmented into multiple layers with different aperture sizes and patterns. The first layer has larger apertures to minimize pressure loss, while subsequent layers have progressively smaller apertures to provide flame control. This segmentation allows each layer to perform its specific function optimally without requiring all layers to have small apertures.
Solution Approach 2:
Different regions of the flame screen have different aperture characteristics. The apertures vary in size, shape, and distribution across the screen surface to create local zones with different flow and flame control properties. This allows optimization for both pressure loss and flame control in different local areas simultaneously.
2Reliability
If very small apertures are used in a flame screen, then flame control is improved, but manufacturing cost and system complexity increase
Solution Approach 1:
The complex flame control function is segmented across multiple layers, with each layer having a simpler aperture pattern that is easier to manufacture. This divides the overall complexity into manageable sections that can be produced using standard manufacturing techniques rather than requiring a single complex layer.
Solution Approach 2:
The aperture parameters (size, shape, distribution) are systematically varied across different layers to achieve flame control. This parametric approach allows for standardized manufacturing processes where only the aperture dimensions need to be changed between layers, rather than requiring completely different screen designs.
3Area of stationary object
If fibrous flame screens are used, then flow area is increased and heat transfer is improved, but susceptibility to blockages increases and maintenance requirements increase
Solution Approach 1:
The invention uses porous metal screens with controlled aperture sizes and distributions instead of fibrous materials. These porous screens provide adequate flow area while maintaining smooth surfaces that resist particle accumulation and blockages. The porous structure allows gas passage while the solid metal construction prevents the blocking issues associated with fibrous materials.
Solution Approach 2:
The multi-layer construction combines screens with different aperture characteristics to create a composite structure that achieves both adequate flow area and resistance to blockages. The combination of different screen types in sequence provides the benefits of each while mitigating their individual weaknesses.
4Reliability
If pressed metal strips are laminated to create long narrow passages, then flame arresting capability is improved, but manufacturing reliability decreases due to temperature changes
Solution Approach 1:
Instead of creating long narrow passages through lamination, the invention segments the flame arresting function across multiple separate layers. Each layer provides flame control through its aperture pattern, eliminating the need for thermally unstable laminated constructions while achieving the same safety objective.
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 flame control and stability, reduces maintenance, and provides a compact, cost-effective solution with improved reliability and resistance to blockages, suitable for difficult gases like hydrogen, while maintaining high combustion efficiency and minimizing undesirable by-products like CO and NOx.
Implementation Method 1
the flame screen burner assembly functions by causing a temperature loss in a flame attempting to return into the fuel and oxygen mixture; the reduced temperature and aperture will thus prevent the flame passing through the screen. The screen will be cooled by the action of the cold combustible gas mixture passing therethrough
Implementation Method 2
In a combustion process for a gaseous or liquid fuel, the leading edge of the flame is usually referred to as a flame front
Data Source
AI summary
A multi-layer flame screen burner assembly comprising first and second outer layers 10,11, at least one flame layer 15 having a plurality of fingers 19 defined by slots 20 provided in the flame layer which open along one edge of the flame layer, and at least one gas distribution layer 16 overlying the flame layer 15 and defining an aperture 23 which is in communication with the slots 20 between the fingers 19 of the adjacent flame layer 15. The overlying flame and gas distribution layers are disposed between the outer layers and the burner assembly has at least one port 14 for the admission of combustible gas to the aperture 23 of the gas distribution layer 16, whereby gas supplied to the port is fed through the aperture to the slots between the fingers of the flame layer. The assembly may be essentially planar or formed into a cylindrical or other shapes and may be located in a plenum chamber, the combustible gas being supplied to the chamber interior and thence to the aperture in the flame layer.