Gas-Permeable PTFE Measuring Channel for Laser Spectrometry
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Solution Overview
Problem
Conventional optical measurement technologies, such as laser spectrometers, are ineffective in measuring gas concentrations in gas streams with high particle content, particularly in the production of silica, where particle levels exceed 50 g/m³, leading to uncertain measurement results and safety concerns due to low laser transmission and particle interference.
Innovation Solution
A method using a gas-permeable PTFE measuring channel with a diameter of 55 mm and average pore size of 5 µm, surrounding a laser spectrometer, to guide the measurement beam, keeping solid particles away from the laser and ensuring accurate gas concentration measurement in high-particle-content gas streams.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional optical measurement technology (laser spectrometer) is used in gas streams with high particle content (>50 g/m³), then measurement can be performed, but laser transmission is blocked and measurement results become unreliable
Solution Approach 1:
The measuring channel is divided into two distinct zones: an inner measurement section where the laser beam travels through particle-free gas, and an outer region where particles are excluded by the porous wall structure. This segmentation isolates the sensitive measurement process from harmful particles while maintaining system integrity.
Solution Approach 2:
The porous channel wall acts as an intermediary structure that selectively transmits gas molecules to the measurement zone while blocking solid particles. The wall material and pore size are specifically chosen to allow gas permeation while excluding particles larger than the pore dimensions, thus mediating between the particle-laden gas stream and the particle-free measurement environment.
2Object-affected harmful factors
If displacement bodies or blocking devices are used to deflect solid particles, then particle interference is reduced, but turbulence and reverse currents cause particles to reach behind deflection plates and impair laser beam
Solution Approach 1:
The harmful solid particles are extracted from the gas stream by the porous wall structure before they can reach the measurement section. The wall continuously removes particles from the gas phase, creating a particle-free environment in the inner measurement zone while the bulk gas flow continues uninterrupted.
Solution Approach 2:
The channel wall is constructed from porous material with specifically controlled pore size and distribution. The porous structure allows gas molecules to pass through while physically blocking solid particles, providing reliable particle exclusion without creating turbulence or reverse currents that would compromise measurement reliability.
3Speed
If measuring channel walls are made thin to reduce particle accumulation, then response time is improved, but structural integrity and particle filtration capability are compromised
Solution Approach 1:
The wall thickness and pore size parameters are optimized to achieve the desired balance between response time and structural integrity. By carefully selecting specific parameter ranges for wall thickness and porosity, the system achieves both rapid particle exclusion and sufficient mechanical strength to withstand operating conditions.
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 approach provides stable and accurate gas concentration measurements, maintaining high transmission rates and preventing particle interference, thus enabling reliable process control and safety monitoring in industrial processes like silica production, even at high particle loads.
Implementation Method 1
a measuring channel (3) with walls (4) made of a gas-permeable material
Implementation Method 2
a tube made of gas-permeable PTFE having a wall thickness of 5 to 7 mm, a diameter of 55 mm and a mean pore size of 5 μm
Implementation Method 3
Another method for measuring oxygen is the use of diode laser spectrometers. A detector measures the absorption of the laser light by the gas molecules.
Data Source
Figure 1
AI summary
The method involves utilizing a flowing gas mixture with solids having predefined size distribution. Gas concentration in the flowing gas mixture is measured using an optical spectrometer (2) i.e. laser spectrometer, and a measurement beam of the optical spectrometer is guided by a measurement channel (3) during measurement. The solids comprising flame-hydrolyzed silica particles and concentration of oxygen in the flowing gas mixture are determined, and a gas-permeable material is selected from a group consisting of polymers, sintered ceramics, sintered metal and PTFE. The flowing gas mixture comprises gas that is selected from a group consisting of anhydrous ammonia, hydrogen chloride, chlorine, hydrogen fluoride, hydrogen sulfide, oxygen, carbon monooxide, carbon dioxide, nitric oxide, nitrogen oxides, nitrous oxide and methane. An independent claim is also included for a device for determining gas concentration of a solid-containing gas mixture of an industrial plant.