Gas Burner Intermediate Tube Flashback Prevention
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Gas-combustion hand tool burners with long lances are prone to flashback when the length-to-diameter ratio is low, posing a risk of destruction, while shortening the lance for ergonomics increases the risk of flashback, and existing solutions fail to address this without compromising flame shape or efficiency.
Innovation Solution
Incorporating an intermediate tube with a smaller diameter and additional air intake near the injector, which allows for dual air-gas mixing paths, reducing the risk of flashback by adjusting air suction and dilution rates based on pressure, maintaining flame efficiency and shape.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the lance length is reduced for better ergonomics, then the ergonomics of the tool is improved, but the risk of flashback increases
Solution Approach 1:
The mixing process is segmented into two distinct zones: an intermediate tube for primary mixing and the lance for secondary mixing. This segmentation allows the lance to be shorter while maintaining adequate mixing length through the intermediate tube, thus improving ergonomics without increasing flashback risk.
Solution Approach 2:
An intermediate tube is introduced as a mediator between the injector and the lance. This intermediate structure provides a dedicated mixing zone that compensates for the reduced lance length, enabling shorter overall lance length while maintaining safe flashback margins.
2Reliability
If the lance length is increased to reduce flashback risk, then the flashback risk is reduced, but the ergonomics of the tool deteriorates
Solution Approach 1:
The mixing function is divided between the intermediate tube and the lance, allowing the lance to be shorter than traditional designs while maintaining sufficient mixing length through the intermediate tube segment.
Solution Approach 2:
The mixing process is extended into a new dimensional space by adding the intermediate tube as a separate structural element between the injector and lance, effectively increasing the mixing path length without increasing the lance length itself.
3Productivity
If the lance cross-section is increased relative to its length, then the mixing capacity is improved, but the flashback risk increases
Solution Approach 1:
The mixing process is divided into two stages with different cross-sectional characteristics: rapid initial mixing in the intermediate tube followed by continued mixing in the lance, allowing optimized cross-sections for each stage that balance mixing capacity with flashback prevention.
Solution Approach 2:
Different cross-sectional dimensions are applied at different locations: the intermediate tube has a cross-section optimized for initial mixing capacity, while the lance maintains dimensions suitable for continued mixing and flame stability, with each zone having locally optimized properties.
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 reduces the risk of flashback by optimizing air-gas mixing, allowing for a shorter lance without increasing flashback risk, while maintaining flame efficiency and ergonomics, as demonstrated by comparative tests showing a significant reduction in flashback pressure and length.
Implementation Method 1
the gas leaving the injector mixes with this air inside the lance, along the latter
Implementation Method 2
the gas leaving the injector mixes with this air inside the lance
Implementation Method 3
where the mixture ignites
Implementation Method 4
the gas leaving the injector mixes with this air
Data Source
Figure 1
Figure 2
Figure 3~5
AI summary
A burner (7) for a gas-powered hand tool comprises a tubular lance (21) associated on one end with a high-pressure gas injector (13) and, on the other, with a combustion zone (25). The lance (21) has at least one first ambient air inlet. The burner (7) further comprises an intercalated tube (55), housed at least partially inside the lance (21), between the injector (13) and the combustion zone (25). This intercalated tube (55) has a second ambient air inlet, this second inlet being located near the first and the injector (13).