The present invention relates to a method and a system for generating gas-filled bubbles in water where the bubble diameters are in the nanometer and micrometer domain.
During recent years, various types of nano- and microbubble generators have been demonstrated, in response to perceived needs in a rapidly expanding range of applications that include waste water treatment, industrial flocculation processes, conditioning of habitats for aquatic flora and fauna, medical procedures, ultrasonic imaging, disinfection and cleaning, etc. Bubble generators may be based on generic principles such as venturi, liquid swirl, high pressure dissolution, ultrasonic vibration, electrolysis and nanopores. Of some relevance in the present context is a device described in U.S. Pat. No. 6,382,601 B1 by H. Ohnari: “Swirling fine-bubble generator”. Here, a swirling stream of water is mixed with air in a conical chamber before being ejected at high speed into surrounding water, causing vortex kinks and creating the fine bubbles. However, this device and most generator devices reported so far share a fundamental problem, namely high energy consumption and low capacity. This is a serious problem in many potential and important areas of application.
The Chinese utility application CN209065520U relates to the field of sewage treatment stirring aeration equipment, in particular to a full tooth blade swirl aerator. The Korean patent KR101947084B B1 relates to a nano-micro bubble generator having a structure designed to enhance collision and friction, two main factors in generating bubbles, and make introduced gas well dissolved into fluid. Both documents present traditional solutions for cavitation promoting materials such as machined, cast or woven edge, knife and mesh structures. For the importance of surface chemistry on nanobubble formation, see e.g.: S. Yang et al.: “Characterization of Nanobubbles on Hydrophobic Surfaces in Water”, Langmuir 2007, 23, 13, 7072-7077; https://doi.orq/10.1021/Ia070004i.
A first aspect of the invention is a fine bubbles generation system for converting gas into fine bubbles in liquid where the system comprises
Optionally, the nanocellulose is derived from tunicates.
Optionally, the second step fine bubbles have a diameter less than 50 micrometers, or more less than 1 micrometer.
Optionally, the reactor vessel comprises a cylinder which can have a circular cross section and can be vertically arranged.
Optionally, the gas input means comprises a gas input opening in the reactor vessel and a fan or an impeller arranged in the reactor vessel between the gas input opening and the agitation means.
Optionally, the liquid input means comprises multiple injection nozzles arranged along wall a wall of the reactor vessel, where the multiple injections nozzles optionally are arranged for inputting the liquid in the reactor vessel there the agitation means are arranged.
Optionally, the agitation means comprises a cyclone comprising a driving impeller arranged in the reactor vessel and at least parts of the surrounding reactor wall, where optionally at least parts of the cyclone means being exposed within the reactor vessel, are topographically structured, and further optionally, at least parts of the cyclone means being exposed within the reactor vessel, are covered with asperity- and/or pore-containing materials. Optionally, the materials are fibrous and/or porous, and can optionally be nanocellulose, steel wool, glass or carbon fibers.
Optionally, the mechanical interaction means comprise multiple mutually angled or inclined surfaces arranged for cascading impacts with first step gas-laden liquid, and further optionally, at least parts of the mechanical interaction means are covered with asperity- and/or pore-containing materials. Optionally, the materials are fibrous and/or porous, and can optionally be nanocellulose, steel wool, glass or carbon fibers. Further optionally, the materials are nanocellulose in the form of cellulose nanofibers (CNF) and/or cellulose nanocrystals (CNC).
Optionally, the driving impeller is of a vornado type.
Optionally, the mechanical interaction means are arranged in a cavitation zone, and comprise pressure controlling impellers.
Optionally, the system comprises a bubble pump arranged to lift ejected water from the reactor vessel in a body of water.
A further aspect of the invention is a fine bubbles generation method for converting gas into fine bubbles in liquid, where the method comprises the following steps:
Optionally, the second step fine bubbles have a diameter less than 50 micrometers, and more preferably less than 1 micrometer.
The above and further features of the invention are set forth with particularity in the appended claims and together with advantages thereof will become clearer from consideration of exemplary embodiments of the invention given with reference to the accompanying drawing.
Embodiments of the present invention will now be described, by way of example only, with reference to the following diagram, wherein:
The following reference numbers refer to the drawing:
Number Designation
Various aspects of the disclosure are described more fully hereinafter with reference to the accompanying drawings. This disclosure may, however, be embodied in many different forms and should not be construed as limited to any specific structure or function presented throughout this disclosure. Rather, these aspects are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the disclosure to those skilled in the art. Based on the teachings herein one skilled in the art should appreciate that the scope of the disclosure is intended to cover any aspect of the disclosure disclosed herein, whether implemented independently of or combined with any other aspect of the disclosure. For example, an apparatus may be implemented, or a method may be practiced, using any number of the aspects set forth herein. In addition, the scope of the disclosure is intended to cover such an apparatus or method which is practiced using other structure, functionality, or structure and functionality in addition to or other than the various aspects of the disclosure set forth herein. It should be understood that any aspect of the disclosure disclosed herein may be embodied by one or more elements of a claim.
According to the present invention a gas flow is converted into an aggregate of nano- and microbubbles in water, by carrying out the following steps:
A first preferred embodiment of the invention is shown in
In a preferred embodiment of the present invention, induction of gas into the reactor vessel and establishment of a vortex is achieved by means of a vornado type impeller, i.e. a dual function impeller where the vanes are shaped to transport gas axially while at the same time to set up an azimuthal circulation.
In another preferred embodiment of the present invention, the cavitation zone comprises a liquid conduit, e.g. a tube, which is loosely packed with a plug of fibers or particles made from one or more of the following: nanocellulose from tunicates or wood, fibers of metal, glass, carbon or minerals. The fibers or particles may be coated with chemically functional materials, e.g. hydrophobic. The packing shall be loose to ensure that the flow resistance through the cavitation zone is low.
In another preferred embodiment of the present invention, one or more impellers are positioned along the fluid path through the cavitation zone and optionally at its exit, creating local pressure drops associated with the impact surfaces, to promote creation of cavitation bubbles. The impellers may comprise surfaces that are covered by or consist of nanocellulose.
Fine bubbles generation systems according to the present invention may be located virtually anywhere, provided access to large volumes of water. In cases where the reactor is located in a body of water, energy can be saved by exploiting hydrostatic pressure in the surrounding water to force water injection into the reactor. However, bubble laden water ejected from the exit of the reactor shall take place against a hydrostatic pressure, consuming energy. One strategy to mitigate this problem is to exploit the fraction of entrained gas bubbles with sizes larger than the fine size fractions sought by the present invention: By transporting the bubble laden water ejected from the exit of the reactor in a vertical riser tube to the surface, the buoyancy of the large bubbles shall cause the riser tube to act as a bubble pump, as is well known in the art.
Number | Date | Country | Kind |
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20201274 | Nov 2020 | NO | national |
Filing Document | Filing Date | Country | Kind |
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PCT/NO2021/050239 | 11/16/2021 | WO |