Raman Spectroscopy for Mixed Phase Fluid Composition Analysis
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Solution Overview
Problem
Conventional methods for analyzing mixed phase fluids, such as those in the natural gas industry, face challenges in providing real-time, accurate measurements of gas and liquid phase compositions due to complex sample handling and interference from water vapor and other components, leading to unreliable results.
Innovation Solution
A spectroscopic measurement system using a phase-separating membrane insert in a pipe, with separate Raman probes for gas and liquid phases, allows for simultaneous measurement of gas and liquid compositions without altering the fluid's composition, enabling accurate determination of phase ratios and component concentrations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If gas chromatographs are used for mixed phase fluid analysis, then material composition can be determined, but the method requires complex sample handling and cannot provide real-time measurements
Solution Approach 1:
The patent replaces the mechanical gas chromatograph system with an optical Raman spectroscopy system. The Raman probe uses laser excitation and optical detection to directly measure gas and liquid phase compositions in real-time without requiring mechanical sample handling, pumps, or chromatography columns, thereby achieving both precision and real-time capability
Solution Approach 2:
The patent extracts the gas phase from the mixed phase fluid by directing the Raman probe through a gas sampling port that isolates the gas phase from the liquid phase. This allows separate measurement of gas composition without interference from liquid components, enabling real-time analysis that would be impossible with conventional mixed-phase sampling methods
2Measurement precision
If gas chromatographs analyze mixed phase fluid samples, then composition data can be obtained, but temperature and pressure modifications alter the fluid composition
Solution Approach 1:
The Raman spectroscopy system performs measurements in-situ within the pipeline at the actual process temperature and pressure conditions. The optical probe does not require sample extraction or conditioning, eliminating the temperature and pressure modifications inherent in gas chromatography sample preparation and preserving the true fluid composition
Solution Approach 2:
The patent introduces an optical window or sampling port as an intermediary that allows Raman measurement through the pipeline wall or into a controlled sampling zone. This intermediary enables measurement at process conditions without direct contact with the mixed phase fluid that would require temperature and pressure changes
3Measurement precision
If gas chromatographs measure shale or wet gas, then energy content can be determined, but water vapor and gaseous components impair measurements and damage the analyzer
Solution Approach 1:
The Raman spectroscopy system replaces the vulnerable gas chromatograph analyzer with an optical detection system that is inherently resistant to corrosion from water vapor and gaseous components. The optical probe and detector can withstand harsh environments without the same degradation issues, providing reliable long-term operation for energy content determination
Solution Approach 2:
The patent uses an optical window or sampling port as an intermediary barrier that protects the Raman measurement system from direct exposure to corrosive water vapor and gaseous components. This intermediary allows measurement while preventing damage, enabling reliable determination of energy content in shale and wet gases
4Measurement precision
If gas chromatographs are used for mixed phase analysis, then composition can be determined, but complex sample handling systems are required
Solution Approach 1:
The Raman spectroscopy system replaces the complex mechanical sample handling infrastructure of gas chromatography with a simple optical probe that can be inserted directly into the pipeline. The system eliminates the need for sample extraction pumps, filtration systems, temperature control units, and chromatography columns, reducing device complexity while maintaining composition determination accuracy
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 system provides real-time, accurate measurements of mixed phase fluid compositions, maintaining thermal and pressure equilibrium, thus ensuring reliable determination of both gas and liquid phase compositions without interference, improving upon existing methods by using a phase-separating membrane and separate Raman probes.
Implementation Method 1
a phase separating membrane adapted to enable the gas phase of the fluid flowing through the pipe to diffuse into and out of the measurement chamber and to facilitate coalescing of the liquid phase of the fluid outside the measurement chamber
Implementation Method 2
configured to transmit excitation light into the measurement chamber and to receive a gas Raman signal emanating from the gas sample within the measurement chamber
Data Source
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AI summary
A Raman spectroscopic measurement system (100) for measuring the material composition of a mixed phase fluid (2) flowing in a process pipe (1) and having a gas phase dispersed in a liquid phase or vice versa includes an insert (3) to be inserted into the pipe. The insert includes a measurement chamber (5) partially defined by a phase separating membrane (7) that enables the gas phase to diffuse into and out of the measurement chamber and facilitates coalescing of the liquid phase which into a collector. The system further includes a collector (9) disposed adjacent the measurement chamber such that the coalesced liquid from outside the measurement chamber drains into the collector. The collector has a drain (11) in fluid communication with the pipe for returning the drained liquid to the pipe. A first probe (15) of the system is configured to transmit excitation light into the measurement chamber and to receive a Raman signal emanating from the gas phase therein, and a second probe (17) of the system is configured to transmit excitation light into the drain and to receive a Raman signal emanating from the liquid phase therein. The measurement system further includes a spectrometer (31) to determine the material composition of the fluid from the Raman signals.