Fiber Gas Sensor with Pd Alloy Coating for Harsh Environment Monitoring
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Solution Overview
Problem
Conventional H2 sensing technologies are unsuitable for direct online monitoring of H2 concentration in fuel streams used by gas turbines due to saturation issues and inability to operate in harsh environments, limiting effective control of combustion performance and efficiency.
Innovation Solution
A fiber gas sensor system utilizing a combination of long-period and short-period fiber gratings with a sensing layer made of nano-PdOx, nano-Pd(x)Au(y)Ni(1-x-y), and nano-Pd/Au/WOx materials, capable of providing temperature-corrected gas concentration measurements, allowing for real-time monitoring in harsh environments.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional combustible gas sensors are used for H2 concentration monitoring, then they can detect gas presence, but they get saturated by high concentration of H2 and cannot provide accurate online measurements
Solution Approach 1:
The patent replaces conventional electrical/chemical gas sensors with an optical sensing system based on fiber optic gratings. The long-period fiber grating (LPFG) and short-period fiber grating (SPFG) structures detect H2 concentration through optical wavelength shifts caused by refractive index changes in the sensing layer, eliminating saturation issues inherent in conventional sensors.
Solution Approach 2:
The invention uses temperature-corrected measurement parameters to compensate for environmental variations. By monitoring both the resonance wavelength shift (related to H2 concentration) and the grating wavelength shift (related to temperature), the system calculates corrected H2 concentration values that are independent of temperature effects.
2Measurement precision
If spectroscope-based instruments are used for H2 concentration measurement, then they can provide accurate offline analysis, but they are bulky and cannot be deployed for real-time online monitoring in harsh environments
Solution Approach 1:
The patent extracts the essential sensing function from complex spectrometry systems and implements it using compact fiber optic grating structures. The LPFG and SPFG sensors can be directly installed in harsh environments like gas turbines and coal gasifiers, providing real-time monitoring without the bulk and complexity of conventional spectroscope-based instruments.
Solution Approach 2:
The fiber optic grating structures act as intermediaries between the H2-rich gas environment and the measurement system. The sensing layer coated on the grating structures interacts with H2 molecules, translating concentration information into optical wavelength shifts that can be remotely detected and analyzed.
3Adaptability or versatility
If conventional sensors are deployed in harsh environments of coal gasifier and Syngas combustors, then they can monitor fuel composition, but they cannot operate reliably due to harsh environmental conditions
Solution Approach 1:
The patent replaces conventional electrical sensors with optical fiber-based sensing systems that are inherently resistant to harsh environmental conditions including high temperature, high pressure, and corrosive gases. The fiber optic gratings and sensing layers are designed to withstand these conditions while maintaining measurement accuracy.
4Adaptability or versatility
If optical methods requiring transparent medium and thermal sensitive optical parts are used, then they can analyze H2-rich Syngas, but they cannot be deployed in harsh environments due to thermal sensitivity issues
Solution Approach 1:
The patent implements temperature compensation by using the SPFG as a reference sensor that measures only temperature-induced wavelength shifts. This reference measurement is then used to correct the LPFG measurements, eliminating thermal sensitivity issues and enabling reliable operation in harsh thermal environments.
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
Enables accurate, real-time monitoring of H2 concentration and temperature, improving combustion efficiency and reducing emissions by providing a practical solution for online Syngas analysis in gas turbines and other power generation systems.
Implementation Method 1
a first refractive index periodic modulated grating structure having a first amplitude modulation profile positioned about the fiber core for sensing a localized gas concentration
Implementation Method 2
a second refractive index periodic modulated grating structure having a second amplitude modulation profile positioned about the fiber core at a distance along the longitudinal axis with respect to the first refractive index periodic modulated grating structure for sensing a localized temperature
Implementation Method 3
the sensing layer including a sensing material made of a group consisting of nano-PdOx, nano-Pd(x) Au(y)Ni(1-x-y) and nano-Pd/Au/WOx
Implementation Method 4
the sensing layer including a sensing material made of a group consisting of nano-PdOx, nano-Pd(x) Au(y)Ni(1-x-y) and nano-Pd/Au/WOx
Data Source
AI summary
A fiber gas sensor includes a fiber core with first and second refractive index periodic modulated grating structures having different amplitude modulation profiles positioned about the fiber core. A fiber cladding is positioned about the first and second refractive index periodic modulated grating structures. A sensing layer is positioned about the fiber cladding of one of the refractive index periodic modulated grating structures. The sensing layer includes a sensing material made of a Pd-based alloy, such as nano-PdOx, nano-Pd(x)Au(y)Ni(1-x-y) or nano-Pd/Au/WOx. The fiber gas sensor provides a measurement of localized, temperature-corrected gas concentration and composition from a combustion environment. A reflection-based or a transmission-based sensing system with an array of one or more fiber gas sensors is also described.