Description:4. DESCRIPTION

Technical Field of the invention

The present invention relates to the field of fluid dynamics, specifically focusing on the generation of nanobubbles in liquids. More particularly, it pertains to system and method using hydrodynamic cavitation to produce and manage nano -sized gas bubbles for enhanced gas transfer and mixing applications.

Background of the invention

A variety of techniques, including the use of pump or blower systems, stirrer are being employed to infuse gas into a liquid medium to achieve a specific level of gas saturation. Gas saturation is defined as the ratio of dissolved gas concentration in the liquid medium to the maximum capacity for gas dissolution under equilibrium conditions. Aeration systems typically involve circulating liquid, such as water, using pumps or blowers to infuse air in the water to aid in gas dissolution.

For example, the amount of dissolved oxygen in a water source is a key indicator of water quality, as many organisms depend on this oxygen supply. It is essential to maintain optimal oxygen levels in liquids, and in some cases, increasing dissolved oxygen content in water is advantageous.

One limitation of current systems is their lack of feasibility in certain situations. Traditional aeration systems may struggle to effectively treat large bodies of water or extensive liquid volumes. Additionally, challenges or limitations in pumping to circulate significant water volumes can lead to inefficiencies or equipment accessibility issues. Therefore, there is a growing need for alternative methods to enhance oxygen saturation, particularly in such complex conditions.
Nanobubbles, also known as ultrafine bubbles, are nanoscale gas-filled structures that exhibit unique physical and chemical properties due to their small size and high internal pressure. These bubbles typically range in diameter from a few to hundreds of nanometers, making them significantly smaller than microbubbles or conventional bubbles. Unlike microbubbles, also known as fine bubbles, which range in diameter from less than 100 µm to over 2 µm, rise to the water surface, and rely on buoyancy to float suspended solids, nanobubbles exhibit remarkable stability, longevity, and high internal pressure, which sets them apart from larger bubbles that tend to rise to the surface and dissipate quickly. This stability is attributed to various theories related to dissolved gas, unusually high surface tension, and surface charges. Unlike microbubbles, nanobubbles do not float and can remain stable in liquid for a relatively much longer time.

Nanobubbles have shown promise in a wide range of applications across different fields, including:
1. Water Treatment: Nanobubbles are being explored for improving the efficiency of processes such as dissolved air flotation, ozonation, and water purification. Their high surface area-to-volume ratio and long residence time in water make them effective for removing contaminants and improving water quality.
2. Medical and Pharmaceutical Applications: Nanobubbles are being investigated for drug delivery, diagnostic imaging, and therapeutic applications in medicine. Their small size and ability to carry drugs to targeted areas in the body make them attractive for enhancing the efficacy and specificity of treatments.
3. Agriculture: Nanobubbles hold potential for improving soil structure, enhancing nutrient uptake in plants, and controlling pathogens in agricultural systems. They can be used in irrigation systems, nutrient solutions, and foliar sprays to promote crop growth and increase agricultural productivity.
4. Food and Beverage Industry: Nanobubbles are being explored for applications in food processing, preservation, and packaging. They can potentially improve the shelf life of products, enhance flavor profiles, and provide antimicrobial effects to reduce spoilage.

Furthermore, Nanobubbles are utilized in various applications, including flotation, aeration, hydroponics, drip irrigation, cleaning, disinfecting, drinking water treatment, environmental remediation, and decontamination. They are also valuable in mining and the chemical industry, where gas-liquid reactions are essential.

In various prior arts, different techniques have been described for generating nanobubbles either by exerting shear stress in static mixers or in motor-driven generators on larger size bubbles until they become nanosized or by ultrasound, shock wave or by creating some swirling motion of the liquid.

JP 2017/176924 describes a micro-nanobubble generator that mixes gas into water supplied from an inlet and outputs water containing gaseous micro-nanobubbles through an outlet. This generator features a first mixing chamber and a second mixing chamber, both aligned along the flow path from the water supply inlet to the output port. The cross-sections of these chambers narrow towards their respective inlet and outlet ends.

WO 2018/081868 and WO 2017/130680 disclose devices for generating nanobubbles, featuring multiple inner tubes with a tubular shape extending longitudinally. Each tube has a porous section where air contacts the liquid, generating air bubbles. These devices do not create shear forces within the fluid flowing through the tubes, nor do the tubes contain any flow-resisting elements that would generate additional nanobubbles.
While prior arts in US 2016/236158, WO 2017/096444, CN 10792226A, and JP 2013-107060 describes engine-based forced turbulence to generate nanobubbles, CA 3029715 describes a nanobubble generating nozzle that features a nanobubble generating structure located between an introduction section and a jetting section. This structure includes multiple flow paths with varying cross-sectional areas through which the liquid and gas mixture flows. These flow paths are divided and arranged in several stages along the axial direction of the nanobubble generating nozzle.

While these methods can produce nanobubbles under specific conditions, they are not optimal for the broad application of nanobubble technology across various industrial sectors. Existing nanobubble generator designs fail to address several key issues:
• High Flow, High Yield: Generating large volumes of nanobubble-enriched water without significantly increasing power consumption. Current designs have limited yield at larger scales.
• Scalability: Expanding the size or flow-throughput of nanobubble generators without losing their generating capacity or requiring more powerful pumps due to increased pressure drop.
• Durability: Creating designs that do not clog, are easy to maintain or service, and do not rely on fragile and expensive parts.
• Robustness and Versatility: Maintaining nanobubble generating capacity in varying environments and applications by:
o Monitoring conditions.
o Adjusting to changes in stream conditions, including solids content, microbiological conditions, salt concentration, temperature, pressure, flow rate, and other external factors that can significantly impact nanobubble generation.
Taking those into consideration, the present invention describes the design and process of the nanobubble generator that is scalable, easy to plug & play and maintain, highly efficient, low power consumption and can be useful for myriad applications including effluent treatment, water disinfection, aquaculture, agriculture, food industry, drinking water purification and many more.

Brief Summary of the invention

The following presents a simplified summary of the disclosure in order to provide a basic understanding to the reader. This summary is not an extensive overview of the disclosure and it does not identify key/critical elements of the invention or delineate the scope of the invention. Its sole purpose is to present some concepts disclosed herein in a simplified form as a prelude to the more detailed description that is presented later.

It is a primary object of the present invention to design a gas-liquid contacting system that effectively disperses gas into a liquid medium in the form of nanobubbles.

It is yet another object of the invention to create a nanobubble generating system and method that employs hydrodynamic cavitation to generate nanobubbles efficiently.

It is yet another object of the invention to facilitate the operation and generation of nanobubbles with various gases, tailored to the specific needs of different applications.

It is yet another object of the invention to overcome the limitations of traditional aeration and ozone-based disinfection methods by utilizing the advanced capabilities of the nanobubble system and method.

It is yet another object of the invention to provide a versatile and retrofittable system that can be seamlessly integrated into existing or new infrastructure.

The invention introduces a device and method for generating nanobubbles in a liquid medium. The system includes a water inlet to supply the liquid, a high-pressure pump to elevate fluid pressure, and multiple mixing chambers arranged around a longitudinal axis. Each chamber features a venturi configuration that creates a sudden pressure drop, leading to the partial vaporization of the liquid and the generation of nano and microbubbles. Additionally, the device incorporates at least one gas injector to introduce a gas into the flow before it exits the chambers, and a flow collector to capture the outgoing flows.

A hydrodynamic cavitation reactor is consisting of several venturi configurations aligned axially. This design is crucial for generating nanobubbles effectively. The reactor creates a vortex at the inlet, which throws the gas-mixed liquid through the chambers. The process involves rapid pressure drops, vaporization, and a significant increase in heat, followed by collapse and shock waves. These conditions fragment dissolved gases into nanoscale, forming nanobubbles in the liquid.

The nanobubble unit is designed for real-time applications, ensuring continuous operation and effectiveness. It achieves nearly 100% gas infusion and retention over time through a sequence of compression, vaporization, collapse, and shock wave processes.

The system supports various gases, such as oxygen, hydrogen, ozone, and carbon dioxide, depending on the specific application or requirement. This flexibility allows for diverse use cases, including advanced aeration with nano-air or nano-oxygen, and advanced disinfection or oxidation with nano-ozone. It is also engineered as a retrofittable, plug-and-play model, allowing for seamless integration into existing or new systems. This makes it applicable across a range of industries, including water treatment, wastewater management, and advanced oxidation processes.

Overall, the invention represents a significant advancement in gas-liquid interaction technology, providing enhanced performance and greater efficiency compared to traditional aeration and disinfection methods.

Brief Description of the Drawings

The invention will be further understood from the following detailed description of a preferred embodiment taken in conjunction with an appended drawing, in which:

Fig. 1 illustrates the entire nanobubble generation process scheme, in accordance with an exemplary embodiment of the present invention.

Fig. 2 illustrates the outside view of the nanobubble generating unit of system, in accordance with an exemplary embodiment of the present invention.

Fig. 3 illustrates the detail entire assembly of nanobubble unit of system, in accordance with an exemplary embodiment of the present invention.

Fig. 4 illustrates the individual venturi unit of system, in accordance with an exemplary embodiment of the present invention.

Detailed Description of the invention

It is to be understood that the present disclosure is not limited in its application to the details of construction and the arrangement of components set forth in the following description or illustrated in the drawings. The present disclosure is capable of other embodiments and of being practiced or of being carried out in various ways. In addition, it is to be understood that the phraseology and terminology used herein is for the purpose of description and should not be regarded as limiting.
The use of “including”, “comprising” or “having” and variations thereof herein is meant to encompass the items listed thereafter and equivalents thereof as well as additional items. The terms “a” and “an” herein do not denote a limitation of quantity, but rather denote the presence of at least one of the referenced items. Further, the use of terms “first”, “second”, and “third”, and the like, herein do not denote any order, quantity, or importance, but rather are used to distinguish one element from another.

According to an exemplary embodiment of the present invention, the system and method of operation of the nanobubble generation unit is disclosed. It comprises of a water inlet for supplying the water to the device, a high pressure pump for increasing fluid pressure, a plurality of mixing chambers preferably distributed around a longitudinal axis of the device, and in communication with the inlet, each chamber comprising a venturi configuration for causing a sudden drop in pressure resulting into partial vaporization of the liquid and generation of nano & microbubbles, , at least one gas injector for injecting a gas into the flow before it leaves the chambers, a flow collector for collecting the flows leaving the chambers.

In accordance with an exemplary embodiment of the present invention, wherein the water reservoir is designed to hold and supply a consistent flow of water to the nanobubble generation system. This reservoir can be either a constructed tank or a natural body of water, depending on the specific requirements of the application. It serves as the primary source of water, ensuring a steady input for the system to process and generate nanobubbles.

In accordance with an exemplary embodiment of the present invention, wherein the water suction pipe is used to transfer water from the reservoir to the high-pressure pump. This pipe is designed to handle the required flow rates and is typically made from durable materials such as PVC or stainless steel. It ensures that water is efficiently drawn from the reservoir and delivered to the pump for pressurization.
In accordance with an exemplary embodiment of the present invention, wherein the high-pressure pump is responsible for increasing the fluid pressure of the water before it enters the nanobubble generation unit. This pump is capable of delivering high pressure, typically measured in bars or psi, to enable effective cavitation. It is connected to both the suction pipe and the nanobubble generation unit, ensuring that water reaches the necessary pressure levels for optimal nanobubble formation.

In accordance with an exemplary embodiment of the present invention, wherein the nanobubble generation unit functions as the core component of the system, responsible for the generation of nanobubbles through hydrodynamic cavitation. This unit comprises several critical sub-components:

In accordance with an exemplary embodiment of the present invention, wherein the mixing chambers are distributed around the longitudinal axis of the device. Each chamber features a venturi configuration that creates a sudden drop in pressure, leading to the partial vaporization of the liquid and the formation of nano and microbubbles. These chambers are designed to facilitate the creation of a vortex and the subsequent bubble generation process.

In accordance with an exemplary embodiment of the present invention, wherein the venturi configuration within the mixing chambers is specifically engineered to cause a rapid pressure drop. This drop in pressure results in the cavitation process, where gas bubbles are formed and subsequently reduced to nanometer scale as the fluid flows through the constricted passage.

In accordance with an exemplary embodiment of the present invention, wherein the gas injector is used to introduce a gas into the water flow before the pump. The gas injector ensures thorough mixing of the gas with the high-pressure water, allowing for effective integration of gases such as oxygen, ozone, or CO2 into the liquid.
In accordance with an exemplary embodiment of the present invention, wherein the flow collector gathers the water carrying nanobubbles as it exits the mixing chambers. This component directs the collected flow to subsequent stages or back to the reservoir, ensuring that the nanobubbles are properly handled and utilized.

In accordance with an exemplary embodiment of the present invention, wherein the flow meter is employed to measure the flow rate of the water carrying nanobubbles. Positioned at the outlet of the nanobubble generation unit, the flow meter monitors the volume of water being processed, allowing for accurate control and optimization of the system's performance.

In accordance with an exemplary embodiment of the present invention, wherein the discharge pipe is used to return the processed water with nanobubbles back to the reservoir. This pipe is designed to manage the flow rate and pressure of the outgoing water, ensuring efficient recirculation and continuous operation of the system.

In accordance with an exemplary embodiment of the present invention, wherein the water inlet (dummy) provides an entry point for water into the nanobubble generating unit. Located at the top of the unit, it helps in directing water tangentially into the system, facilitating the initial mixing and vortex creation necessary for effective bubble generation.

In accordance with an exemplary embodiment of the present invention, wherein the SS drum facilitates the initial mixing of water and the creation of a vortex. Made of stainless steel, this drum directs the water into the nanobubble generating unit tangentially, aiding in the generation of a vortex effect that enhances the cavitation process.

In accordance with an exemplary embodiment of the present invention, wherein the cone pipe and reducer shaft transition the flow of water within the system. The cone pipe connects the SS drum to the reducer shaft, which then manages the flow dynamics and pressure changes as the water progresses through the nanobubble generating unit.

In accordance with an exemplary embodiment of the present invention, wherein connecting rods and flanges provide structural support and connectivity between various components of the nanobubble generation unit. These elements ensure stability and proper alignment of the components, facilitating efficient operation and maintenance of the system.

In accordance with an exemplary embodiment of the present invention, wherein the individual venturi units are designed to create localized pressure drops for bubble generation. Each unit features a narrowing section followed by an expansion area, which causes rapid pressure changes and cavitation, resulting in the formation of nano and micro-sized bubbles.

In accordance with an exemplary embodiment of the present invention, wherein an IoT facility provides real-time monitoring and control of the nanobubble generation system. This integration allows for remote monitoring of water quality and system performance, enabling adjustments and ensuring that the system operates within desired parameters.

Referring to figures, Fig. 1 illustrates the entire nanobubble generation process scheme according to the exemplary embodiment of the present invention. This figure depicts a comprehensive flow diagram showing the components involved in the system. It includes a water reservoir (1), which supplies water via a suction pipe (3) to a high-pressure pump (4). The high-pressure pump increases the water pressure and delivers it through a line to the nanobubble generation unit (6), a hydrodynamic cavitation unit. The gas source (9) is connected to the system upstream of the pump at 5 bar pressure. A valve (11) controls the gas flow rate, and a pressure gauge (5) measures the gas pressure. The gas and water mixture enters the nanobubble generation unit tangentially, creating a vortex that induces centrifugal force and directs the liquid through multiple venturi chambers. The process results in the formation of nanobubbles due to pressure drops, vaporization, heat increase, and collapse. The flow of water carrying micro and nanobubbles is measured by a flow meter (7) and recirculated back to the water reservoir through a discharge pipe (8). The water in the reservoir becomes cloudy over time due to nanobubble accumulation, and larger bubbles escape to the air (12) at the water interface.

Fig. 2 illustrates the external view of the nanobubble generating unit according to the exemplary embodiment of the present invention. This figure shows the external configuration of the nanobubble unit, including a water inlet (13) on the top surface connected to a stainless steel drum (14). A tangential water inlet feed pipe (15) directs water into the drum. The water then flows into a cone pipe (16) and proceeds through a reducer shaft (18) joined by a connecting flange (17). Additional connecting rods (19, 21) and flanges (20, 22, 23) are used to assemble the unit. The design allows for modular adjustments by adding or removing connecting rods (25) and flanges (24) to optimize the length and efficiency of the multi-venturi configurations.

Fig. 3 illustrates the detailed internal assembly and design of the nanobubble generation unit according to the exemplary embodiment of the present invention. This figure provides an internal view of the hydrodynamic cavitation system, showcasing the axial arrangement of multiple venturi configurations within the unit. It highlights how the water and gas mixture flows through the unit, interacting with the venturi configurations to generate nanobubbles through cavitation processes.

Fig. 4 illustrates an individual venturi unit according to the exemplary embodiment of the present invention. This figure focuses on the structure and operation of a single venturi unit within the nanobubble generation system. It shows the sequential compression and expansion processes, including the narrowing section where pressure drops, resulting in the formation of cavitation bubbles. The bubbles are subsequently compressed and collapsed, generating shock waves that splinter the dissolved gas into nano-scale bubbles.
, C , Claims:CLAIMS
I/We Claim:
1. A gas-liquid mixing system for generating nanobubbles, comprising:
a water reservoir (1) for supplying water;
a water suction pipe (3) connected to the water reservoir (1);
a high-pressure pump (4) connected to the water suction pipe (3) and configured to elevate the fluid pressure of the liquid medium, with a pressure gauge (5) measuring the fluid pressure;
a nanobubble generation unit (6) connected to the delivery line of the high-pressure pump (4) with multiple venturi configurations arranged axially to create vortices and induce cavitation;
a gas source (9) connected to the system upstream of the high-pressure pump (4) through a gas inlet (10), being pressurized at 5 bar;
a valve (11) controlling the gas flow rate, with the gas pressure measured through a pressure gauge (5);
a flow meter (7) positioned at the outlet of the nanobubble generation unit (6) to measure the flow of water carrying nanobubbles;
a discharge pipe (8) configured to return the processed water with nanobubbles back to the water reservoir (1);
wherein the nanobubble generation unit includes a hydrodynamic cavitation reactor with an axial arrangement of multiple venturi configurations that create vortices and induce cavitation to fragment gas into nanobubbles.

2. The gas-liquid mixing system as claimed in claim 1, wherein the hydrodynamic cavitation reactor comprises a plurality of venturi configurations arranged axially, creating a vortex in the water inlet to centrifugally expel the gas-mixed liquid through the chambers, causing expansion, vaporization, heat increase, and collapse of bubbles to form nanobubbles.

3. The gas-liquid mixing system as claimed in claim 1, wherein the nanobubbles generated in the liquid medium achieve a gas infusion and retention efficiency of approximately 100%, resulting in an oxygen transfer efficiency greater than 85%.

4. The gas-liquid mixing system as claimed in claim 1, wherein the nanobubbles remain suspended in the liquid and disperse throughout the liquid volume, providing continuous gas transfer until collapse.

5. The gas-liquid mixing system as claimed in claim 1, wherein the system is retrofittable and adaptable to existing or new infrastructure.

6. The gas-liquid mixing system as claimed in claim 1, further comprising a stainless steel drum (14) connected to the water inlet dummy (13), having a tangentially placed water inlet feed pipe (15) that directs water into the drum to create a centrifugal force before proceeding to the cone pipe (16) and reducer shaft (18).

7. The gas-liquid mixing system as claimed in claim 1, wherein the cone pipe (16) and reducer shaft (18) are joined through a connecting flange (17), and additional connecting rods (19, 21) and flanges (20, 22) allow for modular adjustments to the length and efficiency of the multi-venturi configurations.

8. The gas-liquid mixing system as claimed in claim 1, wherein the flow of the processed water with nanobubbles is recirculated through the discharge pipe (8) back to the water reservoir (1), maintaining a cloudy appearance due to nanobubble accumulation and allowing larger bubbles to escape to the air (12) at the water interface.

9. The gas-liquid mixing system as claimed in claim 1, further comprising an Internet of Things (IoT) facility (13) for real-time monitoring and control of the system’s performance, including water quality and gas infusion efficiency.
10. A method for generating nanobubbles in a liquid, comprising:
supplying water and gas to a high-pressure pump (4);
increasing the fluid pressure of the water using the high-pressure pump (4);
passing the high-pressure water through a nanobubble generation unit (6) comprising a hydrodynamic cavitation reactor with multiple mixing chambers and venturi configurations arranged axially;
injecting a gas into the high-pressure water flow before pump;
creating a vortex in the water inlet to centrifugally expel the gas-mixed liquid through the chambers, resulting in a sudden pressure drop, vaporization, heat increase, and collapse of bubbles to form nanobubbles;
collecting the flow of water carrying nanobubbles;
measuring the flow of water using a flow meter and recirculating it back to the reservoir.