Optical hydrogen detector employing controlled water vapor concentration over catalyst

A molecular hydrogen detector, comprising:

• an inlet configured to receive sample gas that includes naturally-occurring water vapor and sample molecular hydrogen;
• a gas dyer configured to dry the sample gas;
• a flow controller configured to add an amount of humid gas to the sample gas or an amount of a mixture containing hydrogen or a hydrogen-containing water-convertible species to the sample gas to produce controlled water vapor, to cause a level of controlled water vapor in the sample gas to be substantially equal to a target mixing ratio;
• a catalytic oven including a catalyst configured to convert hydrogen in the sample gas to water vapor to produce converted sample gas;
• an optical detection cell configured to use optical absorption spectroscopy to measure water vapor in the converted sample gas to produce a water vapor signal;
• and
• a processor configured to separate the water vapor signal into a controlled water vapor signal that describes the controlled water vapor and a sample hydrogen-derived water vapor signal that describes sample hydrogen-derived water vapor and output a hydrogen signal that describes sample molecular hydrogen in the sample gas that is based on the sample hydrogen-derived water vapor signal.

A method for detecting molecular hydrogen, comprising:

• receiving sample gas that includes naturally-occurring water vapor and sample molecular hydrogen;
• drying the sample gas;
• adding an amount of a mixture containing hydrogen or a hydrogen-containing water-convertible species to the sample gas;
• converting hydrogen in the sample gas to water vapor to produce converted sample gas having a level of controlled water vapor substantially equal to a target mixing ratio, wherein the converting converts both the sample molecular hydrogen and hydrogen or hydrogen-containing water-convertible species contained in the added mixture to water vapor, and the hydrogen or hydrogen-containing water-convertible species of the added mixture becomes controlled water vapor;
• measuring water vapor in the converted sample gas to produce a water vapor signal;
• separating the water vapor signal into a controlled water vapor signal that describes the controlled water vapor and a sample hydrogen-derived water vapor signal that describes sample hydrogen-derived water vapor;
• and
• outputting a hydrogen signal that describes sample molecular hydrogen in the sample gas that is based on the sample hydrogen-derived water vapor signal.

A molecular hydrogen detector, comprising:

• means for receiving sample gas that includes naturally-occurring water vapor and sample molecular hydrogen;
• means for drying the sample gas;
• means for adding an amount of a mixture containing hydrogen or a hydrogen-containing water-convertible species to the sample gas;
• means for converting hydrogen in the sample gas to water vapor to produce converted sample gas having a level of controlled water vapor substantially equal to a target mixing ratio, wherein the means for converting is configured to convert both the sample molecular hydrogen and hydrogen or hydrogen-containing water-convertible species contained in the added mixture to water vapor, and the hydrogen or hydrogen-containing water-convertible species of the added mixture becomes controlled water vapor;
• means for measuring water vapor in the converted sample gas to produce a water vapor signal;
• and
• means for separating the water vapor signal into a controlled water vapor signal that describes the controlled water vapor and a sample hydrogen-derived water vapor signal that describes sample hydrogen-derived water vapor, and for outputting a hydrogen signal that describes sample molecular hydrogen in the sample gas that is based on the sample hydrogen-derived water vapor signal.