Methane Index Determination via Viscosity and Density Correlation
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Solution Overview
Problem
Current methods for determining the methane number of fuel gas mixtures, particularly natural gas and biogas, are complex and require precise knowledge of component proportions, making them inefficient for rapidly fluctuating gas compositions in energy storage systems.
Innovation Solution
A method that determines the methane number using measured variables such as viscosity, density, pressure, and temperature, allowing for correlation calculations without needing precise component proportions, and includes optional measurements for thermal conductivity to account for hydrogen content.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If component proportion analysis methods are used to determine methane number, then measurement precision is improved, but device complexity and measurement time increase significantly
Solution Approach 1:
The patent extracts only the essential physical properties (density and viscosity) needed for methane number determination, eliminating the need for complex component-by-component analysis. By focusing on these two key properties that directly correlate with knock resistance, the method achieves accurate methane number determination without requiring complete compositional knowledge of the gas mixture.
Solution Approach 2:
The patent replaces complex chemical analysis systems with simple physical measurement systems. Instead of using chromatography or spectroscopy equipment to analyze component proportions, the invention uses straightforward density and viscosity measurements combined with empirical correlations to determine methane number, significantly simplifying the measurement apparatus.
2Measurement precision
If component proportion analysis is performed for fluctuating gas compositions, then measurement accuracy is maintained, but productivity and response time decrease
Solution Approach 1:
The patent establishes pre-determined empirical correlations between physical properties (density, viscosity) and methane number based on extensive experimental data. These correlations are prepared in advance and stored as lookup tables or mathematical models, allowing rapid determination of methane number through simple property measurements without requiring real-time component analysis.
Solution Approach 2:
The patent transitions from measuring component concentrations to measuring physical properties (density and viscosity) that change with composition. This parameter transformation enables faster measurements because physical property measurements are inherently quicker than compositional analysis, while still providing accurate methane number determination through the established correlations.
3Device complexity
If simple physical property measurements are used, then device complexity is reduced, but measurement precision for hydrogen-containing gases deteriorates
Solution Approach 1:
The patent develops a universal measurement approach that works for both traditional natural gas and hydrogen-containing gas mixtures. By using density and viscosity measurements combined with empirical correlations that account for different gas compositions, the single measurement system accurately determines methane number across varying hydrogen contents without requiring separate measurement systems or complex calibration procedures.
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 a simple and robust determination of the methane number, improving burner control and knock resistance assessment in internal combustion engines by directly correlating viscosity and density-dependent parameters, thus simplifying the process and reducing measurement complexity.
Implementation Method 1
a vibronic sensor for determining the viscosity or the density of the measuring medium
Implementation Method 2
a sensor for determining a first thermal-physical property, selected from the thermal conductivity, the thermal conductivity or the specific heat capacity of the measuring medium
Data Source
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AI summary
The invention relates to a method (100) for determining the methane index of a hydrocarbon-containing combustion gas mixture which has natural gas or biogas in particular, having the steps: allowing the combustion gas mixture to flow through a measuring assembly; determining a first measurement value (110) of a first measurement variable which is based on the viscosity of the flowing combustion gas mixture; determining a second measurement value (110) of a second measurement variable which is based on the density of the flowing combustion gas mixture; determining a pressure measurement value (110) of the flowing combustion gas mixture, said measurement value belonging to the first measurement value and the second measurement value, and determining (110) a temperature measurement value of the flowing combustion gas mixture, said temperature measurement value belonging to the first measurement value and the second measurement value; and determining the methane index (190) as a function of the first measurement value, the second measurement value, the pressure measurement value, and the temperature measurement value.