Emissions Correction Using Humidity-Based Dilution Factor
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Solution Overview
Problem
In high-dilution air environments, particularly in industrial settings with hydrogen or hydrogen blend burners, existing methods struggle to accurately correct emissions due to sensitivity to measurement uncertainties, especially when oxygen concentrations approach atmospheric levels, and CO2 corrections are ineffective for fuels generating little to no CO2.
Innovation Solution
A system utilizing humidity measurements, specifically relative humidity sensors and a microcomputer to calculate the dilution factor based on water vapor content in pre- and post-combustion gases, providing a more stable correction method compared to oxygen-based corrections.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If oxygen-based correction is used to measure dilution factor, then correction can be applied for conventional fuels, but measurement uncertainty becomes exponentially sensitive when stack oxygen concentration approaches atmospheric oxygen concentration
Solution Approach 1:
The patent changes the measurement parameter from oxygen concentration to water vapor concentration. Instead of using O2 levels to determine dilution factor, the system measures H2O concentration in the exhaust stream, which remains reliably different from ambient levels even in high-dilution scenarios, thereby eliminating the exponential sensitivity problem.
Solution Approach 2:
The patent introduces water vapor as an intermediary substance for measuring dilution. Rather than directly measuring oxygen (which becomes unreliable), the system uses water vapor concentration as a proxy indicator that maintains measurement reliability across all dilution conditions.
2Measurement precision
If CO2-based correction is used for dilute air streams, then emissions can be corrected with less sensitivity to measurement uncertainty, but this method does not work when flue gas contains only trace amounts of CO2 as in high hydrogen or pure hydrogen fuel blends
Solution Approach 1:
The patent creates a universal correction method based on water vapor measurement that works across all fuel types including hydrogen, hydrogen blends, natural gas, and other combustibles. Unlike CO2-based methods that fail with hydrogen fuels, the H2O-based approach maintains adaptability and versatility for all fuel compositions.
3Object-generated harmful factors
If high dilution air is used to reduce as-measured pollutant concentration, then stack pollutant concentration decreases, but the dilution correction factor increases indicating non-compliance with regulations
Solution Approach 1:
The patent replaces the traditional mechanical/O2-based correction system with a water vapor measurement system. This substitution provides more accurate tracking of true emissions levels because H2O concentration directly reflects the combustion process and dilution amount without the exponential sensitivity issues of oxygen-based methods.
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 reduces measurement uncertainty and effectively corrects emissions for hydrogen and hydrogen blend burners, achieving accuracy comparable to CO2 correction methods while being less sensitive to experimental uncertainties, especially when humidity sensors have low uncertainty.
Implementation Method 1
a first sensor that measures the relative humidity of a sample of air not containing an exhaust gas
Implementation Method 2
a second sensor that measures the relative humidity of the exhaust gas
Implementation Method 3
a microcomputer that calculates a mass of water vapor in the sample of air measured by the first sensor and in the exhaust gas measured by the second sensor
Data Source
AI summary
A device and method for correcting emissions can include a first sensor that measures a sample of air not containing an exhaust gas, and a second sensor, wherein the exhaust gas enters a settling chamber and a relative humidity of the exhaust gas is measured by the second sensor. A microcomputer can calculate a mass of water vapor in the sample of air measured by the first sensor and in the exhaust gas measured by the second sensor and can determine a dilution factor of the measured exhaust gas. The dilution factor can be used for correcting emissions based on the measurements of the exhaust gas made by the first sensor and the second sensor. The first and second sensors can comprise one or more of, for example, a relative humidity sensor, a dew point sensor, a trace water vapor sensor and/or other types of sensors.