Equilibrator for rapid and continuous detection of a gas in a liquid
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.
1. An apparatus to separate at least one constituent from a liquid comprising multiple constituents, comprising:
a venturi tube comprising a venturi orifice and configured to pass the liquid through the venturi tube and further configured to introduce a carrier medium into the liquid, whereby a first portion of a first constituent in the liquid diffuses into the carrier medium;
a mixer configured to receive the liquid and the carrier medium from the venturi tube, whereby the mixer mixes the liquid and the carrier medium;
a plenum comprising a first exit and configured to receive the liquid and the carrier medium from the mixer, wherein the plenum is further configured to pass the liquid and the carrier medium through a free overfall stream within the plenum, whereby the carrier medium exits the liquid, and the carrier medium is discharged from the plenum through the first exit; and
a gas analyzer configured to receive the carrier medium from the plenum through the first exit.
2. The apparatus of claim 1 , wherein the first constituent continuously diffuses from the liquid into the carrier medium.
3. The apparatus of claim 2 , wherein the apparatus is configured to discharge the carrier medium comprising the first constituent from the plenum through the first exit in less than about one minute from the carrier medium being introduced into the liquid.
4. The apparatus of claim 2 , wherein the apparatus is configured to discharge the carrier medium comprising the first constituent from the plenum through the first exit in less than about ten seconds from the carrier medium being introduced into the liquid.
5. The apparatus of claim 4 , wherein the carrier medium makes a single pass through the apparatus from the venturi orifice to the first exit of the plenum.
6. The apparatus of claim 1 , wherein the first constituent comprises a hydrocarbon gas.
7. The apparatus of claim 6 , wherein the liquid comprises water and the hydrocarbon gas comprises methane.
8. The apparatus of claim 7 , wherein the venturi tube comprises an injection orifice configured to inject the carrier medium into the liquid.
9. The method of claim 8 , wherein the carrier medium comprises a gas.
10. The apparatus of claim 1 , wherein a second portion of the first constituent diffuses from the liquid into the carrier medium in the mixer.
11. The apparatus of claim 10 , wherein the mixer comprises a static mixer configured to mix the carrier medium and the liquid.
12. The apparatus of claim 1 , wherein a third portion of the first constituent diffuses into the carrier medium from the liquid within the plenum.
13. The apparatus of claim 12 , wherein the plenum comprises a second exit to discharge the liquid from the plenum.
14. A method to separate at least one constituent from a liquid comprising multiple constituents, comprising:
introducing the liquid into the apparatus of claim 1 ;
causing a pressure drop in the liquid;
introducing a carrier medium into the liquid;
diffusing a first constituent of the liquid's multiple constituents into the carrier medium;
mixing the liquid and the carrier medium; and,
moving a portion of the carrier medium out of the liquid.
15. The method of claim 14 , comprising passing the liquid through the venturi orifice.
16. The method of claim 15 , comprising injecting the carrier medium into the liquid in proximity of the venturi orifice.
17. The method of claim 14 , wherein the carrier medium comprises a gas in the form of bubbles, and comprising breaking the bubbles into smaller bubbles.
18. The method of claim 17 , comprising breaking the bubbles into smaller bubbles using the mixer, wherein the mixer comprises a static mixer.
19. The method of claim 17 , comprising moving a portion of the bubbles out of the liquid by passing the liquid and bubbles through the free overfall stream.
20. The method of claim 19 , comprising collecting the bubbles as a free gas over the liquid and passing the free gas into the gas analyzer.
21. The apparatus of claim 2 , wherein the apparatus is configured to discharge the carrier medium comprising the first constituent from the plenum through the first exit in less than one minute from the carrier medium being introduced into the liquid.
22. The apparatus of claim 2 , wherein the apparatus is configured to discharge the carrier medium comprising the first constituent from the plenum through the first exit in less than ten seconds from the carrier medium being introduced into the liquid.