Cavitation Bubble Nucleation for Methane Extraction
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Solution Overview
Problem
The existing methane extraction methods from deep lakes, such as Lake Kivu, face inefficiencies due to delays in bubble germination and chemical diffusion barriers, which reduce the volume of free gas collected, especially in waters with low germ concentrations and high carbon dioxide levels.
Innovation Solution
Incorporating a high-velocity water injector with capillary holes in the extraction column to create a cloud of micro-bubbles through cavitation, enhancing the exsolution process by initiating bubble formation near the saturation depth, thereby increasing the volume of free gas and improving the autosiphon process efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If natural exsolution process is used for methane extraction, then energy consumption is reduced, but bubble germination is delayed and extraction efficiency is lowered
Solution Approach 1:
The invention introduces a gas injection device that pre-injects gas bubbles into the water column before the natural exsolution process begins. This preliminary action provides immediate nucleation sites for bubble formation, eliminating the delay in natural germination while maintaining the self-sustaining nature of the process without requiring continuous external energy input.
Solution Approach 2:
The invention uses injected gas bubbles as intermediary nucleation sites that facilitate the exsolution process. These intermediary bubbles serve as templates for methane bubble formation, accelerating the transition from dissolved gas to gaseous phase without requiring significant energy input, thus resolving the contradiction between energy efficiency and extraction efficiency.
2Productivity
If gas is injected to initiate bubble formation, then bubble germination is accelerated, but external energy is required
Solution Approach 1:
The invention designs the gas injection device to utilize the natural exsolution process and buoyancy forces to sustain bubble formation. Once initial gas is injected to create nucleation sites, the system becomes self-sustaining, using the natural rise of bubbles and exsolution of dissolved gas to maintain the process without continuous external energy input, thus achieving self-service operation.
Solution Approach 2:
The invention leverages the phase transition of dissolved gas to gaseous phase through natural exsolution. By injecting a small amount of gas to initiate the phase transition, the system exploits the natural thermodynamic drive for gas exsolution to sustain bubble formation, converting chemical potential energy stored in dissolved gas into kinetic energy of rising bubbles without additional external energy input.
3Quantity of substance
If water is raised from deep layers, then methane concentration increases, but hydrostatic pressure reduces bubble stability
Solution Approach 1:
The invention segments the water column into distinct zones: a deep layer where water is extracted with high methane concentration, and an upper layer where pressure reduction enables bubble formation. The gas injection device creates localized low-pressure zones that facilitate bubble stability despite the overall high hydrostatic pressure environment, allowing segmentations of the pressure field to accommodate both high concentration and bubble stability.
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
The bubble nucleation device significantly enhances methane extraction efficiency by increasing the number and size of bubbles, promoting faster gas exsolution and maintaining self-sustaining circulation without external energy, thus improving the overall performance of the methane extraction process.
Implementation Method 1
a bubble nucleation device, the bubble nucleation device comprises at least one high-velocity water injector arranged in the extraction column to create bubbles by cavitation
Implementation Method 2
The two-phase liquid-gas mixture, due to its lower density than the liquid, therefore develops an Archimedean energy which naturally drives the entire column upwards
Implementation Method 3
Outlet 7 of this extraction column 3 is connected to a water/gas separator 9. The separator is for example a metal cylinder at the heart of which the gas, in particular methane, separates from the water
Data Source
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AI summary
The gas extraction installation comprises an extraction column of which an inlet opens into water layer containing gas to be extracted dissolved in high concentration and an outlet is connected to a water/gas separator, and a device for bubble nucleation comprising a high velocity water injector (17) laid in the extraction column to create cavitation bubbles. The bubbles contain methane. The high velocity water injector is placed just above the depth of saturation. The device for nucleating bubbles comprises a high pressure pump connected to the injector. The gas extraction installation comprises an extraction column of which an inlet opens into water layer containing gas to be extracted dissolved in high concentration and an outlet is connected to a water/gas separator, and a device for bubble nucleation comprising a high velocity water injector (17) laid in the extraction column to create cavitation bubbles. The bubbles contain methane. The high velocity water injector is placed just above the depth of saturation. The device for nucleating bubbles comprises a high pressure pump connected to the injector. The injector comprises a hole in the extraction column, and a tube (19) laid in the extraction column and having capillary holes (23). The tube is inserted into the extraction column through a lateral opening. The holes are evenly distributed on the periphery of the tube and located in a central zone of the extraction column away from walls, and have a diameter of 0.5 mm. The injector is immersed in the extraction column. The high pressure pump is made of a block with the injector, and immersed with that in the extraction column at the saturation depth. A control unit of the methane flow rate product is arranged with a control unit of the injector of water at high velocity of the device for nucleation of bubbles.