Duct Probe With Filtered Optical Cavity for Gas Analysis
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Solution Overview
Problem
Existing optical methods for constituent gas analysis in sample streams face challenges such as precise alignment requirements, particulate-induced errors, and the need for continuous purge gas, which increase costs and measurement inaccuracies.
Innovation Solution
A probe with an optical cavity within the duct allows for in situ analysis by drawing filtered gas samples through a filter, eliminating the need for continuous purge gas and enabling accurate, fast measurements with integrated flow sensors for monitoring and calibration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If open path cross stack gas absorption monitoring is used, then gas concentration analysis can be performed, but high precision alignment and installation costs increase
Solution Approach 1:
The optical path is segmented into separate components: an optical source positioned in the duct, a filter assembly that samples gas, and a detector assembly. This segmentation eliminates the need for precise alignment between source and detector across the entire duct, as each component operates independently at its own location.
Solution Approach 2:
A filter assembly acts as an intermediary between the sample gas stream and the optical detector. The filter samples gas from the duct and directs it through an optical path to the detector, mediating the interaction between the gas and light while eliminating direct line-of-sight alignment requirements.
2Reliability
If continuous purge gas is used to protect optical elements, then optical elements are protected from particulates, but costs and gas supply requirements increase
Solution Approach 1:
The harmful particulates are extracted and removed from the optical path by positioning the optical detector behind a filter assembly. The filter captures particulates before they can reach and damage the optical elements, eliminating the need for continuous purge gas to protect them.
Solution Approach 2:
The filter assembly serves itself by continuously capturing particulates from the gas stream that pass through it. This self-cleaning function protects the optical elements without requiring external purge gas supply systems.
3Reliability
If purge gas flow rate changes occur, then optical element cleaning may improve, but measurement errors increase
Solution Approach 1:
The optical detector is extracted from the direct gas stream and positioned behind the filter assembly. This extraction isolates the optical elements from the gas flow variations, ensuring that measurement accuracy is not affected by changes in gas flow rate while the filter continues to protect the optics.
4Productivity
If particulates are present in the sample stream, then gas sampling can proceed, but optical absorption path is decreased and resolution deteriorates
Solution Approach 1:
The system segments the gas sampling function from the optical measurement function. The filter assembly handles the particulate-laden gas sampling, while the optical detector operates in a protected environment, allowing continuous sampling without compromising measurement resolution.
Solution Approach 2:
The filter assembly serves as an intermediary that allows particulate-containing gas to pass through to the sampling system while blocking particulates from reaching the optical path, thus maintaining both sampling continuity and measurement precision.
5Adaptability or versatility
If optical elements are positioned in the sample stream, then in situ analysis is enabled, but optical elements require continuous purging
Solution Approach 1:
The filter assembly acts as an intermediary that enables the optical detector to operate in situ within the duct while protecting it from the sample stream. The filter mediates between the harsh particulate environment and the sensitive optical elements, eliminating the need for purge gas arrangements.
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 solution reduces installation time, minimizes measurement errors, and allows for accurate, fast gas analysis with reduced maintenance, while ensuring a particulate-free environment for optical elements, enhancing detection sensitivity and response time.
Implementation Method 1
by pulling a gas sample through a filter
Implementation Method 2
optical absorption method by pulling a gas sample through a filter by aspiration or other means into an optical cavity housed within the probe where analysis occurs
Data Source
AI summary
The present invention relates to a probe having an elongated main body with a proximal end for attachment to a wall of a duct or volume and a distal end that is disposed on the interior of the duct, such that the main body forms a measurement space through which the fluid is drawn for analysis.