Dissolved Hydrogen Measurement Using Vacuum Gas Sampling and Thermal Conductivity Detection
Solution Overview
Problem
Conventional methods for measuring the concentration of dissolved hydrogen in aqueous solutions, such as oxidation-reduction potential, fail to accurately isolate and quantify hydrogen due to measuring the sum of oxidation and reduction powers of all materials, leading to unclear hydrogen concentration measurements.
Innovation Solution
A method using gas chromatography with a selected carrier gas having a predetermined difference in thermal conductivity and a thermal conductivity detector (TCD) to separate and detect hydrogen, combined with a vacuum gas sampling bottle method for sample preparation, allowing for improved sensitivity and accuracy in measuring hydrogen concentration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If oxidation-reduction potential method is used to measure dissolved hydrogen concentration, then measurement can be performed, but the measurement accuracy deteriorates because all materials having oxidation and reduction influence are measured, not only hydrogen
Solution Approach 1:
The patent segments the measurement process into distinct stages: sample preparation where hydrogen is separated from the aqueous solution, followed by specific detection of hydrogen using a hydrogen-selective electrode. This segmentation isolates hydrogen measurement from other oxidizing/reducing materials, resolving the contradiction between performability and accuracy.
Solution Approach 2:
The patent extracts hydrogen from the aqueous solution through degasification before measurement. By removing hydrogen gas from the solution and measuring it in the gas phase separately, the method isolates hydrogen concentration data from interference by other materials present in the aqueous solution.
2Productivity
If conventional measurement methods are used, then measurement can be performed, but measurement time increases and sensitivity decreases
Solution Approach 1:
The patent performs preliminary degasification of the aqueous solution to separate hydrogen from the liquid phase before measurement. This preliminary action concentrates hydrogen in the gas phase and removes interfering substances, enabling both faster measurement and higher sensitivity detection in subsequent steps.
Solution Approach 2:
The patent introduces a hydrogen-selective electrode as an intermediary detection device that specifically responds to hydrogen concentration. This intermediary component enables rapid and sensitive hydrogen measurement without interference from other materials, resolving the contradiction between measurement speed and sensitivity.
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 enables precise measurement of hydrogen concentration by enhancing detection sensitivity and reducing measurement time, while also reducing costs through the use of nitrogen as a carrier gas and minimizing contamination from impurities.
Implementation Method 1
a thermal conductivity detector (TCD), which converts the difference in thermal conductivity between hydrogen and the carrier gas into a voltage difference to detect the difference in thermal conductivity
Implementation Method 2
a separation process for separating hydrogen from the aqueous solution sample on the basis of equilibrium in adsorption and distribution between the aqueous solution sample introduced in the mobile phase and a stationary phase of a column
Data Source
AI summary
The present invention is configured of: a gas control step in which a carrier gas that differs in thermal conductivity from hydrogen by a given value is chosen, and the flow rate thereof is controlled; a sample introduction step in which an aqueous solution sample is prepared and introduced into the carrier gas serving as a mobile phase and which is characterized in that the preparation of an aqueous solution sample comprises injecting an aqueous solution sample into a vessel, the inside of which is kept vacuum, to thereby conduct gas-liquid separation and collecting the gas-phase portion as a sample to be introduced; a separation step in which the hydrogen is separated from the aqueous solution sample on the basis of an adsorption/distribution equilibrium between the aqueous solution sample introduced into the mobile phase and the fixed phase of the column; a detection step; and a data processing step.