Hydrogen Flame Ionization Detector Nozzle Tapered Geometry
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Solution Overview
Problem
In hydrogen flame ionization detectors (FID), the collection efficiency of ions and the stability of the hydrogen flame are compromised when the nozzle enters the collector too deeply, reducing the opening area for combustion gas and leading to unstable flame formation.
Innovation Solution
The FID design incorporates a nozzle with a first tapered surface at its upper end and a collector with a second tapered surface at its lower end, where the second taper angle is larger than the first, ensuring a sufficient opening area for combustion gas even when the nozzle is deeply inserted.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the nozzle is positioned deeper inside the collector to improve ion collection efficiency, then the detection sensitivity improves, but the opening area for combustion gas is reduced, causing unstable flame formation
Solution Approach 1:
The collector is designed with different surface characteristics at different locations: the lower end has a tapered surface with a larger taper angle to guide combustion gas and maintain flame stability, while the upper end has a smaller inner diameter to improve ion collection efficiency. This local differentiation allows the nozzle to be positioned deeper without compromising flame stability.
Solution Approach 2:
The taper angle of the collector's inner surface is changed as a key parameter. By making the taper angle larger at the lower end compared to the upper end, the design optimizes both combustion gas flow and ion collection. This parameter variation resolves the contradiction between deep nozzle positioning for sensitivity and sufficient opening area for flame stability.
2Measurement precision
If the inner diameter of the collector is made smaller than the maximum outer diameter of the nozzle to improve collection efficiency, then the detection sensitivity improves, but it becomes difficult to cause the nozzle to enter the collector
Solution Approach 1:
The collector's inner surface features a tapered (curved/conical) geometry rather than a straight cylindrical shape. This curvature allows the nozzle to smoothly enter and position itself within the collector, overcoming the size mismatch between the nozzle outer diameter and collector inner diameter.
3Ease of operation
If a tapered surface with the same taper angle as the nozzle is provided on the collector to facilitate nozzle entry and stabilize flame, then the ease of operation improves, but when the nozzle enters too much, the opening area for combustion gas becomes small, reducing flame stability
Solution Approach 1:
The collector's tapered surface is designed with asymmetric taper angles: a larger angle at the lower end for easy nozzle entry and flame stabilization, and a smaller angle at the upper end to maintain sufficient opening area for combustion gas even when the nozzle is deeply inserted. This asymmetric design resolves the contradiction between ease of operation and flame stability.
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 ion collection efficiency while stabilizing the hydrogen flame by maintaining a sufficient opening area for combustion gas, thus improving detection sensitivity and flame stability.
Implementation Method 1
a hydrogen flame is formed at an upper end of the nozzle to ionize components in the sample gas
Implementation Method 2
a potential difference of about 100 to several 100 V is usually provided between the nozzle and the collector in order to improve the collection efficiency with the collector by directing the jumping direction of the ions generated by the hydrogen flame toward the collector side
Implementation Method 3
a hydrogen flame is formed at an upper end of the nozzle
Data Source
AI summary
The present invention includes a housing (2) including an internal space (3) to which a combustion gas is supplied, a nozzle (4) provided with an ejection port (18) at an upper end, the nozzle (4) being configured to eject a mixed gas of a sample gas and a combustion support gas from the ejection port (18) to form a hydrogen flame at the upper end, and a collector (8) having a hollow cylindrical shape and provided above the nozzle (4) with a central axis facing a vertical direction to collect components in the sample gas ionized by a hydrogen flame formed at the upper end of the nozzle (4), wherein the nozzle (4) is provided with a first tapered surface (22) at an upper end part, the first tapered surface (22) being inclined with a first taper angle (θ1), the first tapered surface (22) reducing an outer diameter of the nozzle (4) toward the upper end, and the collector (8) is provided with a second tapered surface (24) inside a lower end part, the second tapered surface (24) being inclined with a second taper angle (θ2) larger than the first taper angle (θ1), the second tapered surface (24) reducing an inner diameter of the collector (8) upward from a lower end.