Venturi Equilibrator for Continuous Methane Detection in Groundwater
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Solution Overview
Problem
Current methods for detecting methane in water are limited by long equilibration times and inability to provide real-time, continuous measurements, which complicates the assessment of stray gas migration and groundwater contamination near oil and gas production areas.
Innovation Solution
A system comprising a venturi tube and static mixer in series, with a gas-tight plenum for rapid gas-water separation, allowing continuous measurement of methane concentrations by passing water through a venturi orifice and introducing air bubbles to enhance mass transfer, achieving separation and analysis within minutes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional equilibration methods are used to detect methane in water, then measurement accuracy is improved, but equilibration time becomes excessively long and continuous measurement is not achieved
Solution Approach 1:
The system divides the water flow into multiple streams and processes them through parallel equilibration chambers, allowing simultaneous processing of multiple samples. This segmentation enables continuous measurement while maintaining accuracy by processing discrete portions of water flow through the equilibration system.
Solution Approach 2:
The system implements continuous water flow through the equilibration chambers rather than batch processing. Water is constantly pumped through the system, allowing uninterrupted methane detection. The continuous flow ensures that equilibration occurs continuously, eliminating idle time between measurements while maintaining measurement precision through steady-state operation.
2Measurement precision
If discrete sampling methods are used, then laboratory analysis accuracy is improved, but real-time continuous monitoring capability is lost
Solution Approach 1:
The system replaces manual discrete sampling and laboratory analysis with an automated in-situ equilibration and detection system. Water samples are continuously pumped through equilibration chambers where methane is extracted and detected by sensors, eliminating the need for manual sampling, sample preservation, transport, and laboratory analysis while maintaining measurement accuracy through controlled equilibration conditions.
Solution Approach 2:
The system performs self-monitoring by continuously pumping water through the equilibration chambers and detecting methane concentrations in real-time. The automated system requires minimal human intervention, continuously acquiring, processing, and reporting data without manual sampling or laboratory analysis, thereby achieving both accuracy and real-time productivity.
3Reliability
If purging is performed to remove stagnant water, then sample representativeness is improved, but concentration variability increases due to purging effects
Solution Approach 1:
The system performs preliminary purging by pumping water through the equilibration chambers before actual measurements begin. This initial flow removes stagnant water and primes the system, ensuring that subsequent measurements are taken from representative flowing water. The preliminary action establishes steady-state conditions that eliminate purging-induced concentration variability during the measurement phase.
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 rapid and continuous separation of methane from water, providing real-time data on methane concentrations, improving the detection of groundwater contamination and reducing the need for discrete sampling and laboratory analysis.
Implementation Method 1
a venturi tube having a venturi orifice and configured to pass a liquid stream therethrough and introduce air bubbles into the liquid stream
Implementation Method 2
the gas in the liquid diffuses into the carrier medium as the liquid and carrier medium transit the apparatus
Implementation Method 3
passing the liquid and the bubbles through a free overfall stream within the plenum, whereby the bubbles exit the liquid to form a free gas comprising the first constituent over the liquid
Data Source
AI summary
A rapid and continuous separator or equilibrator to separate a gas from a liquid includes a venturi and injector, a mixer and a free overfall stream to separate a gas from a liquid. The injector introduces a carrier medium into the liquid which provides a reservoir for the gas to diffuse into as the liquid and carrier make a single transit through the apparatus. The separator was developed to enable real-time estimation of methane concentrations in ground water during purging. Real-time monitoring allows evaluation of trends during water well purging, spatial trends between water wells, and temporal comparisons between sampling events. These trends may be a result of removal of stored casing water, pre-purge ambient borehole flow, formation physical and chemical heterogeneity, or vertical flow outside of well casing due to poor bentonite or cement seals. Real-time information in the field can help focus an investigation, aid in determining when to collect a sample, save money by limiting costs (e.g. analytical, sample transport and storage), and provide an immediate assessment of local methane concentrations, Four domestic water wells, one municipal water well, and one agricultural water well were sampled for traditional laboratory analysis and compared to the field separator or equilibrator results. Applying a paired t-test comparing the new separator or equilibrator method and traditional laboratory analysis yielded a p-value 0.383, suggesting no significant difference between the two methods for the current study. Additional field and laboratory-based experimentation and potential modification of this device are necessary to justify use beyond screening at this time. However, early separator or equilibrator use suggests promising results and applications.