A gas-liquid cascade separation device and method for strengthening bubble separation of electrolyte

Abstract

This invention provides a gas-liquid cascade separation device and method for enhanced electrolyte bubble separation. The gas-liquid cascade separation device includes an alkaline electrolyzer, a centrifugal pump, a gas-liquid separation device, a gas purification device, a gas collection device, and a filtration device. The hydrocyclone separator and the coalesced fiber membrane are located inside the gas-liquid separation device to achieve cascaded deep separation of electrolytes with high gas content. The fiber membrane has a continuous weave pattern and employs multi-layer spacing. The gas-liquid cascade separation method includes steps such as primary separation using a hydrocyclone, preliminary separation of the gas and liquid phases, secondary separation using the coalesced fiber membrane, and collection and recovery of the gas and liquid phases. This gas-liquid cascade separation device and method not only significantly reduces the gas content in the electrolyte but also optimizes the structure of the gas-liquid separation equipment, reducing equipment usage and maintenance costs. It is expected to be coupled with my country's industrial hydrogen production industry, and has significant implications for the development of my country's green hydrogen industry and the realization of its carbon neutrality strategy.

Description

Technical Field

[0001] This invention relates to the field of alkaline water electrolysis for hydrogen production, specifically to an apparatus and method for using a swirling centrifugal force field and microfiber stepped depth separation of high gas content electrolyte. Background Technology

[0002] Hydrogen energy is a green energy source characterized by its pollution-free nature, renewability, and high calorific value. It has wide applications in industrial production, including petroleum refining, metal smelting, and new energy vehicles. Currently, alkaline water electrolysis is the only technologically mature green hydrogen production method capable of large-scale, long-cycle production. Its equipment structure mainly consists of two electrolytic plates connected in series, separated by an asbestos membrane. During electrolysis, the membrane's obstruction prevents the mixing of gases produced at the cathode and anode.

[0003] In water electrolysis for hydrogen production, the electrolysis products hydrogen and oxygen flow out of the electrolyzer along with the electrolyte. Efficient and rapid separation of these gases from the electrolyte is crucial for the electrolysis system. Traditional gas-liquid separators use gravity settling, which is slow, inefficient, requires large equipment space, and is expensive. In particular, it is almost impossible to separate the microbubbles dissolved in the electrolyte. As the power of industrial electrolyzers continues to increase, the gas content of the electrolyte also increases. If efficient gas-liquid separation is not achieved in high-gas-content electrolytes, the electrolyte returning to the electrolyzer will have an excessively high gas content, easily causing gas backmixing and posing a safety hazard to the electrolyzer. Therefore, developing a highly efficient and rapid method to enhance microbubble separation is of great significance for the safe and stable operation of high-power alkaline water electrolysis hydrogen production systems.

[0004] Chinese patent CN202223424019.8 discloses a novel gas-liquid separator for water electrolysis. It utilizes a suspended rotor, a scraper assembly, and a drip-collecting net. Airflow entering through the inlet sleeve drives the turbine blades, causing the shaft to rotate, which in turn rotates the guide ring and brush plate, scraping away the water film condensed on the surface of the drain sleeve. Simultaneously, a sealing plug, a suspended airbag, and a heat exchange tube are used in conjunction, utilizing the low-temperature heat exchange tube to contact the gas, accelerating the condensation of water vapor in the gas and ensuring effective gas-liquid separation. However, this method is not very effective for gas-liquid separation of electrolytes with high gas content, and the use of low-temperature tubes and a refrigeration unit increases equipment costs.

[0005] Chinese patent CN202121591904.8 discloses an electrolyte conveying gas-liquid separation device. The liquid entering the separator first undergoes preliminary separation through gravity settling in a U-shaped tube. The remaining liquid enters a hollow fiber membrane in a vacuum chamber from the other end of the U-shaped tube. Under negative pressure, dissolved gases are released, thus achieving gas-liquid separation. This method has good separation efficiency, but the increase in the vacuum chamber correspondingly increases the cost of the power equipment. Furthermore, the high gas content of the electrolyte entering the hollow fiber membrane easily causes fiber blockage, reducing separation efficiency and hindering long-term operation of the separation equipment.

[0006] Therefore, there is an urgent need for a device and method for microbubble-enhanced separation that can significantly improve the gas-liquid separation efficiency of high gas content electrolytes, while optimizing the equipment structure and reducing the cost of equipment use and maintenance. Summary of the Invention

[0007] To address the aforementioned problems, this invention provides a gas-liquid staged separation device and method for enhancing electrolyte bubble separation. The separation device and method first utilize a hydrocyclone for preliminary rapid gas-liquid separation, then utilize microfibers to induce bubble coalescence, achieving deep gas-liquid separation. This reduces the microbubble content in the electrode liquid, significantly lowering the gas content of the high-gas-content electrolyte, reducing the electrolyte resistivity, and significantly improving electrolysis efficiency.

[0008] Therefore, the first objective of this invention is to provide a gas-liquid cascade separation device that utilizes a swirling centrifugal force field and microfiber-enhanced electrolyte bubble separation, comprising an alkaline electrolytic cell, a gas-liquid separation device connected to the outlet of the alkaline electrolytic cell via a centrifugal pump, a gas purification device and a gas collection device sequentially connected after the gas phase outlet of the gas-liquid separation device, and a filtration device connected to the liquid phase outlet of the gas-liquid separation device, wherein a swirling separator and a coalescing fiber membrane layer are arranged vertically inside the gas-liquid separation device; wherein:

[0009] The gas phase outlet and liquid phase outlet of the gas-liquid separator are respectively located at the top and bottom of the gas-liquid separator.

[0010] The cyclone separator has a mixed phase inlet in the middle, a concave bowl-shaped top cover at the top, and a double inner cone core at the bottom.

[0011] The coalescing fiber membrane layer is located below the hydrocyclone separator. The fiber weave pattern of the fiber membrane layer is a continuous weave, the diameter of the woven fibers is 100-200 μm, and the porosity is 0.70-0.85. The fiber membrane layer is arranged in multiple layers with spacing, and the number of layers is 5-10.

[0012] The filtration device is connected via pipelines to the liquid phase outlet of the gas-liquid separator and the inlet of the alkaline electrolytic cell, respectively.

[0013] According to the present invention, the hydrocyclone separator is a vertical column cavity structure, wherein a mixed phase inlet and a liquid phase outlet are respectively provided in the middle and bottom of the vertical column cavity, wherein the mixed phase inlet and the liquid phase outlet of the hydrocyclone separator are both tangential.

[0014] Furthermore, the mixed phase inlet of the cyclone separator is a rectangular nozzle; the number of liquid phase outlets of the cyclone separator is set to 2, which are horizontally symmetrically distributed, and their bottom surfaces are on the same horizontal plane as the bottom surface of the cyclone separator.

[0015] Furthermore, the inner diameters of the mixed phase inlet and liquid phase outlet of the cyclone separator are both 15-20 mm, the column cavity diameter of the cyclone separator is 60-80 mm, and the column cavity height is 480-640 mm; the diameter of the gas-liquid separation device tank is 0.5-1.0 m, and the height is 3-4 m.

[0016] According to the present invention, the top of the cyclone separator is provided with a gas phase outlet, and the gas phase outlet of the cyclone separator is provided with a tapered overflow pipe inside the vertical column cavity. The tapered overflow pipe is arranged in an offset manner, and its central axis is offset from the central axis of the gas-liquid separation device.

[0017] Furthermore, the tapered overflow pipe is fixed to the surrounding wall using a trapezoidal thick wall, and the top inner diameter and bottom inner diameter of the tapered overflow pipe are 10-15 mm and 15-20 mm, respectively.

[0018] According to the present invention, the bottom of the double inner conical core is configured as a column, and its bottom surface is on the same horizontal plane as the bottom surface of the liquid phase outlet of the cyclone separator.

[0019] Furthermore, the upper cone of the double inner conical core of the cyclone separator has a cone angle of 40°, the lower cone has a taper of 20°, the total height of the upper and lower cones is 125-150mm, and the diameter of the cone bottom is 0.4-0.6 times the diameter of the separator; the height of the column at the bottom of the double inner conical core is 0.1-0.3 times the height of the cone.

[0020] According to the present invention, the coalesced fiber membrane layer is arranged at an angle of 25° to 40° with respect to the horizontal plane.

[0021] According to the present invention, the woven fiber material used in the coalesced fiber membrane layer is polytetrafluoroethylene.

[0022] The second objective of this invention is to provide a gas-liquid stepwise separation method based on the enhanced electrolyte bubble separation device of this invention, the gas-liquid stepwise separation method comprising the following steps:

[0023] Step 1: First-stage separation using a hydrocyclone:

[0024] After electrolysis in a high-power alkaline electrolytic cell, the electrolyte becomes a gas-liquid mixture with high gas content and microbubbles. Driven by a centrifugal pump, the gas-liquid mixture enters the mixed phase inlet of the hydrocyclone separator tangentially from the pipeline. Inside the hydrocyclone separator, it is subjected to the centrifugal force field of the cyclone separator, achieving the effect of primary separation, in which larger bubbles are removed.

[0025] Step 2: Preliminary separation of the gas and liquid phases:

[0026] Subsequently, the gas and liquid phases are discharged from the gas phase outlet and liquid phase outlet of the hydrocyclone separator, respectively. During the upward movement of the gas phase containing trace amounts of electrolyte, the liquid phase is removed due to the action of the bowl-shaped top cover baffle; the liquid phase then enters the inner cavity of the gas-liquid separator downward, achieving the initial separation of the liquid and gas phases.

[0027] Step 3: Secondary separation using coalesced fiber membranes:

[0028] The liquid electrolyte entering the inner cavity of the gas-liquid separator contains a certain amount of microbubbles. When the electrolyte flows through the coalescing fiber membrane, the bubbles coalesce due to the turbulent action of the coalescing fibers. Bubbles that have coalesced to a certain extent rise from the fiber surface under the action of buoyancy, and coalesce with other bubbles in the fiber during this process, eventually forming larger bubbles that detach from the electrolyte. This achieves a two-stage deep separation effect, and the microbubbles in the electrolyte are removed.

[0029] Step 4: Collection and recovery of gas and liquid phases

[0030] The separated gas phase flows through the gas phase outlet of the gas-liquid separator to the gas purification device for drying, and finally enters the gas collection device for collection; the liquid phase flows through the liquid phase outlet of the gas-liquid separator to the pipeline, and after passing through the filtration device and adding an appropriate amount of pure water, it can be recycled back into the electrolytic cell.

[0031] According to the present invention, in step one, the electrolyte has a gas content of 30% to 40% and the bubble diameter is 50 μm to 1 mm.

[0032] According to the present invention, the electrolyte in the electrolytic cell 1 in step one is a KOH solution with a mass concentration of 25-30% and a pH of 13.2-13.8.

[0033] According to the present invention, the pressure of the gas-liquid mixture at the inlet of the cyclone separator in step one is 0.6 to 0.8 MPa, and the inlet velocity is 2.8 to 3.2 m / s.

[0034] According to the present invention, in step two, the volume of electrolyte in the gas-liquid separation device is controlled to be 70-80% of the volume of the gas-liquid separation device.

[0035] The present invention has the following beneficial effects:

[0036] 1. This invention utilizes a hydrocyclone separator and coalescing fibers to achieve graded gradient enhanced electrolyte bubble separation. The electrolyte with high gas content first enters the hydrocyclone separator, where large bubbles are initially and rapidly separated under the action of the swirling centrifugal force field. Subsequently, the microbubbles in the electrolyte are agglomerated into large bubbles under the induction of the coalescing fibers. Finally, under the action of buoyancy, they rise continuously and detach from the electrolyte, achieving deep separation of microbubbles. This significantly reduces the gas content in the electrolyte and increases the electrolysis efficiency of the electrolytic cell.

[0037] 2. This provides a feasible solution for the gas-liquid separation of electrolytes with high gas content in current high-power industrial electrolyzers. It overcomes the problems of low gas-liquid separation efficiency and incomplete separation in traditional gas-liquid separation devices, ensuring that the gas content of the electrolyte flowing back to the electrolyzer is less than 0.0001%, thereby ensuring the safe and efficient operation of the entire system. Attached Figure Description

[0038] Figure 1 This is a schematic diagram of the process apparatus for enhancing microbubble separation according to the present invention.

[0039] Figure 2 This is a schematic diagram of the gas-liquid cascade separation device of the present invention.

[0040] Figure 3 This is a schematic diagram of the structure of the cyclone separator 4 of the present invention.

[0041] Figure 4 This is a schematic diagram of the structure of the double inner cone core 34 of the present invention.

[0042] Figure 5 These are three views of the hydrocyclone top cover 36 of the present invention, wherein Figure 5 'a' is the front view. Figure 5 b is a side view. Figure 5 c is the top view.

[0043] Figure 6 This is a schematic diagram of the fiber weaving pattern of the coalesced fiber membrane layer 5 of the present invention.

[0044] Drawing number explanation:

[0045] 11-Alkaline electrolytic cell; 12-Electrolytic cell inlet; 2-Centrifugal pump; 3-Gas-liquid separation device; 31-Gas phase outlet of gas-liquid separation device; 32-Liquid phase outlet of gas-liquid separation device; 4-Cyclone separator; 41-Mixed phase inlet of cyclone separator; 42-Gas phase outlet of cyclone separator; 43-Gradually constricting overflow pipe; 44-Double inner cone core; 45-Liquid phase outlet of cyclone separator; 46-Bowl-shaped top cover; 5-Coalescing fiber membrane layer; 6-Gas purification device; 7-Gas collection device; 8-Filtration device. Detailed Implementation

[0046] The present invention will be further described in detail below with reference to embodiments. It should be understood that the following embodiments are only used to further illustrate the present invention and should not be construed as limiting the scope of protection of the present invention. Some non-essential improvements and adjustments made by those skilled in the art based on the content of the present invention still fall within the scope of protection of the present invention.

[0047] Example 1: Gas-liquid cascade separation device for enhanced electrolyte bubble separation

[0048] like Figures 1-2 As shown, the process apparatus of the present invention, which employs a hydrocyclone separator and a graded gradient enhancement method for electrolyte bubble separation, includes an alkaline electrolytic cell 1, a gas-liquid separation device 3 connected to the outlet 11 of the alkaline electrolytic cell 1 via a centrifugal pump 2, a gas purification device 6 and a gas collection device 7 sequentially connected after the gas phase outlet 31 of the gas-liquid separation device 3, and a filter device 8 connected to the liquid phase outlet 32 ​​of the gas-liquid separation device 3. The gas-liquid separation device 3 contains a hydrocyclone separator 4 and a coalesced fiber membrane layer 5 arranged vertically. Wherein:

[0049] The centrifugal pump 2 is used to transport the high gas content electrolyte from the alkaline electrolytic cell 1 to the cyclone separator 4 of the gas-liquid separation device 3 for gas-liquid separation.

[0050] The gas phase outlet 31 and liquid phase outlet 32 ​​of the gas-liquid separation device are respectively located at the top and bottom of the gas-liquid separation device 3, and are used to transport the gas phase and liquid phase after the first-stage cyclone separation treatment.

[0051] The cyclone separator 4 is provided with a mixed phase inlet 41 in the middle, which is used to receive high gas content electrolyte from the alkaline electrolyzer 1; the coalescing fiber membrane layer 5 is located below the cyclone separator 4, which is used to induce the coalescence of microbubbles in the water to achieve gas-liquid separation.

[0052] The gas purification device 6 is used to receive gas from the cyclone separator 4, dry and purify the gas, and then transport it to the gas collection device 7 for collection.

[0053] The filtration device 8 is connected to the liquid phase outlet 32 ​​of the gas-liquid separator 3 and the electrolytic cell inlet 12 of the alkaline electrolytic cell 1 via pipelines. It is used to receive the low gas content electrolyte after separation and filter it, so as to return the filtered electrolyte to the alkaline electrolytic cell 1.

[0054] Furthermore, such as Figure 3 As shown, the cyclone separator 4 is a vertical columnar cavity structure. The middle and bottom of the vertical columnar cavity are respectively provided with a mixed phase inlet 41 and a liquid phase outlet 45. The mixed phase inlet 41 and the liquid phase outlet 45 are tangential, which is used to allow the gas-containing electrolyte to enter the cyclone separator 4 in the tangential direction to form a cyclone. Preferably, the mixed phase inlet 41 is a rectangular nozzle as the optimal structure to further optimize the separation performance. The number of liquid phase outlets 45 of the cyclone separator is set to 2, which are horizontally symmetrically distributed, and their bottom surfaces are on the same horizontal plane as the bottom surface of the cyclone separator 4 to further improve the liquid transport efficiency.

[0055] Furthermore, the top of the cyclone separator 4 is provided with a gas phase outlet 42, and the gas phase outlet 42 is provided with a tapered overflow pipe 43 inside the vertical column cavity. The tapered overflow pipe 43 is offset, and its central axis is offset from the central axis of the gas-liquid separation device 3, which is used to provide the separation force required for bubble separation under low pressure loss. The tapered overflow pipe 43 is fixed to the surrounding wall with a trapezoidal thick wall.

[0056] Furthermore, the bottom of the cyclone separator 4 is provided with an inner core 44, which adopts a double inner cone structure to support the residual gas in the electrolyte after cyclone separation. The bottom of the inner core 44 is set as a column, and its bottom surface is on the same horizontal plane as the bottom surface of the liquid phase outlet 45 of the cyclone separator 4.

[0057] Preferably, the inner diameters of the mixed-phase inlet 41 and the liquid-phase outlet 45 of the cyclone separator 4 are both 15-20 mm, the top inner diameter and bottom inner diameter of the converging overflow pipe 43 are 10-15 mm and 15-20 mm respectively, the length-to-diameter ratio of the column cavity of the cyclone separator 4 is approximately 8, the column cavity diameter is 60-80 mm, and the column cavity height is 480-640 mm. Correspondingly, the diameter of the gas-liquid separation device 3 tank is 0.5-1.0 m, and the height is 3-4 m.

[0058] Preferred, such as Figure 4 As shown, the upper cone section of the inner core 44 of the cyclone separator has a cone angle of 40°, the lower cone section has a taper of 20°, the height of the upper and lower cone sections is 125-150mm, and the diameter of the cone bottom is 0.4-0.6 times the diameter of the separator; the height of the column at the bottom of the inner core 44 is 0.1-0.3 times the height of the cone section.

[0059] Furthermore, such as Figure 5 As shown, a concave bowl-shaped top cover 46 is provided at the top of the hydrocyclone separator to separate the trace amount of liquid-containing gas discharged from the gas phase outlet 42 at the top of the hydrocyclone separator 4. Due to the obstruction of the top cover 46, the liquid phase's movement direction is deflected, while the gas phase is discharged from the gas phase outlet 31 at the top of the gas-liquid separation device 3 within the top cavity. The four vertices of the plane of the top cover 46 are welded to the top of the hydrocyclone using a bracket.

[0060] Furthermore, such as Figure 6 As shown, the coalesced fiber membrane layer 5 has a continuous weave pattern, which is beneficial for better capturing bubbles and promoting rapid bubble coalescence. This induces the coalescence of residual microbubbles in the electrolyte after initial separation, thereby achieving further gas-liquid separation. The coalesced fiber membrane layer 5 is spaced apart with a spacing of 0.05–0.1 m and a membrane thickness of 0.1–0.15 m.

[0061] Preferably, the diameter of the woven fibers is 100-200 μm and the porosity is 0.70-0.85, which is used to increase the probability of bubble collision while providing a large throughput.

[0062] Preferably, the coalesced fiber membrane layer 5 is arranged at an angle of 25° to 40° with respect to the horizontal plane, which is beneficial to enhancing the turbulence of the liquid.

[0063] Preferably, the woven fiber material used in the coalesced fiber membrane layer 5 is a high molecular organic material, such as polytetrafluoroethylene (PTFE), which is resistant to strong alkalis.

[0064] Preferably, the number of coalesced fiber membrane layers 5 is determined according to the power of the alkaline electrolyzer. For the problem of high gas content electrolyte separation caused by high-power electrolyzers in industry, the number of coalesced fiber membrane layers 5 is preferably 5 to 10 layers, wherein the volume occupied by the fibers does not exceed 30% of the total volume of the gas-liquid separation device.

[0065] The device of this invention employs a combination of a hydrocyclone separator and a coalescing fiber membrane layer to enhance bubble separation through a graded gradient, which can greatly improve the gas-liquid separation effect, significantly reduce the number of bubbles in the high-gas-content electrolyte of a high-power industrial electrolyzer, and improve electrolysis efficiency.

[0066] The working principle of the gas-liquid cascade separation device of the present invention is as follows:

[0067] The high-gas-content gas-liquid mixture flowing out of the alkaline electrolyzer 1 is first pressurized by the centrifugal pump 2 and then transported through pipelines to the hydrocyclone separator 4. Subsequently, larger bubbles in the electrolyte rapidly coalesce and separate under the combined action of the centrifugal force field and the pressure field. The separated gas phase is discharged along the gas phase outlet 42 at the top of the hydrocyclone separator 4. At the top cover 46 of the hydrocyclone separator 4, a small amount of incompletely separated liquid phase contained in the gas phase is separated by the obstruction of the top cover 46, resulting in a relatively pure gas. Then, the separated gas is transported through the gas phase outlet 31 at the top of the gas-liquid separation device 3 to the gas purification device 6 for drying and pressurization, and finally transported to the gas collection device 7 for storage.

[0068] The separated liquid phase is discharged from the liquid phase outlet 45 at the bottom of the cyclone separator 4 and enters the middle of the gas-liquid separation device 3. At this time, a small number of microbubbles still exist in the liquid phase. After settling and stabilization, the liquid phase enters the coalescing fiber membrane layer 5. The coalescing fiber membrane layer 5 can further enhance the turbulence of the liquid phase and capture the bubbles, inducing the bubbles to further coalesce. When the bubbles coalesce to a certain volume, they will rise under the action of buoyancy and eventually detach from the electrolyte, achieving deep gas-liquid separation, and smaller bubbles can be removed. The separated electrolyte is discharged from the liquid phase outlet 32 ​​at the bottom of the gas-liquid separation device 3 and transported to the filter device 8 through pipeline to filter out a small number of solid particles in the electrode liquid. Finally, after adding an appropriate amount of pure water, it can be reinjected into the electrolytic cell 1 for recycling. The whole process achieves stepwise deep gas-liquid separation, and the separation effect is more thorough than other separation methods, significantly reducing the gas content in high gas content electrolytes.

[0069] Example 2: A gas-liquid cascade separation method for enhanced electrolyte bubble separation

[0070] Based on the gas-liquid gradient separation device of Example 1, which utilizes a hydrocyclone separator and a coalescing fiber membrane layer gradient to enhance the separation of high gas content electrolyte bubbles, this embodiment provides a gas-liquid gradient separation method. This method can be used to separate alkaline electrolytes with a gas content of 30%–40% and bubble diameters of approximately 50 μm–1 mm. The separation method includes the following steps.

[0071] Step 1: First-stage separation using a hydrocyclone

[0072] After electrolysis in the high-power alkaline electrolytic cell 1, the electrolyte becomes a gas-liquid mixture with high gas content and microbubbles. Driven by the centrifugal pump 2, the gas-liquid mixture enters the mixed phase inlet 41 of the hydrocyclone 4 tangentially from the pipeline. Inside the hydrocyclone 4, it is subjected to the centrifugal force field of the cyclone separator, achieving the effect of primary separation, in which larger bubbles are removed.

[0073] The electrolyte in electrolytic cell 1 is a KOH solution with a mass concentration of 25-30% and a pH of 13.2-13.8. The pressure of the gas-liquid mixture at the inlet of the hydrocyclone 4 is 0.6-0.8 MPa, and the inlet velocity is 2.8-3.2 m / s.

[0074] Step 2: Preliminary separation of gas and liquid phases

[0075] Subsequently, the gas and liquid phases are discharged from the gas phase outlet 42 and the liquid phase outlet 45 of the cyclone separator 4, respectively. During the upward movement of the gas phase containing trace amounts of electrolyte, the liquid phase is removed due to the action of the bowl-shaped top cover baffle. The liquid phase then enters the inner cavity of the gas-liquid separation device 3 downward, achieving the initial separation of the liquid and gas phases.

[0076] The volume of the electrolyte in the gas-liquid separation device 3 is controlled to be 70-80% of the volume of the gas-liquid separation device 3.

[0077] Step 3: Secondary separation using coalesced fiber membranes

[0078] The liquid electrolyte entering the inner cavity of the gas-liquid separator 3 contains a certain amount of microbubbles. When the electrolyte flows through the coalescing fiber membrane layer 5, the bubbles coalesce due to the turbulent action of the coalescing fibers. The bubbles that have coalesced to a certain extent rise from the fiber surface under the action of buoyancy, and coalesce with other bubbles in the fiber during this process, eventually forming larger bubbles that leave the electrolyte. This achieves a two-stage deep separation effect, and the microbubbles in the electrolyte are removed.

[0079] Step 4: Collection and recovery of gas and liquid phases

[0080] The separated gas phase flows along the gas phase outlet 31 of the gas-liquid separator 3 to the gas purification device 6 for drying, and finally enters the collection device 7 for collection; the liquid phase flows along the liquid phase outlet 32 ​​of the gas-liquid separator 3 to the pipeline, and after passing through the filter device 8 and adding an appropriate amount of pure water, it can be recycled back into the electrolytic cell 1.

[0081] Example 3: Comparative experiment on the gas-liquid separation effect of the gas-liquid staged separation device of the present invention and Comparative Example 1.

[0082] This embodiment is used to verify the advancements of the gas-liquid staged separation device and method of the present invention in enhancing electrolyte bubble separation, thereby improving the gas-liquid separation effect. In the comparative experiment of this embodiment, the gas-liquid staged separation device described in Embodiment 1 of the present invention is used, and its specific structural dimensions are as follows:

[0083] The vertical tank of the gas-liquid separator 3 has a diameter of 0.6m and a height of 2.5m. The volume of the electrolyte in the gas-liquid separator 3 is controlled at 3 / 4 of its capacity. The mixed phase inlet 41 and liquid phase outlet 45 of the cyclone separator 4 both have an inner diameter of 15mm. The top and bottom inner diameters of the tapered overflow pipe are 10mm and 15mm, respectively. The length-to-diameter ratio of the tube cavity of the cyclone separator 4 is approximately 8, the cavity diameter is 60mm, and the cavity height is 480mm. The tank of the gas-liquid separator 3 has a diameter of 0.6m and a height of 3m.

[0084] The coalesced fiber membrane layer 5 is arranged at an angle of 30° to the horizontal plane. The diameter of the woven fiber is 100-200 μm and the porosity is 0.8. It is composed of 5 fiber membrane layers arranged at intervals, with each membrane layer spaced 0.1 m apart and the membrane layer thickness is 0.12 m.

[0085] The specific experimental conditions for the gas-liquid stepwise separation method described in Embodiment 2 of the present invention are as follows: the electrolyte in the electrolytic cell 1 is a KOH solution with a mass concentration of 30% and a pH of 13.8; the gas content in the electrolyte discharged from the alkaline electrolytic cell is 40%, and the diameter of the bubbles is 50 μm to 1 mm; the pressure of the gas-liquid mixture at the inlet of the cyclone separator 4 is 0.8 MPa, and the inlet velocity is 3 m / s.

[0086] Comparative Example 1 did not include a hydrocyclone separator or coalescing fiber membrane layer; it only used a conventional gas-liquid separation device. The electrolytic mixture directly entered the gas-liquid separation device, and the electrolyte inlet conditions were the same as in the Example. The Reynolds number of the flowing electrolyte was 2000. The gas holdup was determined by measuring the content of microbubbles or large bubbles in the electrolytes recovered from the Examples and Comparative Examples. The results are shown in Table 1.

[0087] Table 1. Gas-liquid separation effect of Examples and Comparative Example 1

[0088]

[0089] As shown in Table 1, the final liquid product electrolyte discharged from the gas-liquid separation device of this embodiment has very low microbubble and large bubble content, with a gas content of only 0.0001%. In contrast, in Comparative Example 1, some gas could not be separated from the electrolyte, and the gas content of the liquid product electrolyte discharged from the gas-liquid separation device was 5%. Therefore, the effect of using a hydrocyclone separator and coalescing fibers to achieve graded gradient enhanced electrolyte bubble separation is very significant. The hydrocyclone separator achieves rapid separation of larger bubbles in the electrolyte in the first stage, while the coalescing fiber membrane layer achieves deep separation of microbubbles in the electrolyte in the second stage. Thus, for the problem of high gas content gas-liquid separation caused by high-power alkaline electrolysis at present, the gas-liquid graded separation device and method of this invention have the advantages of high separation efficiency, thorough separation, and easy installation.

[0090] Example 4: Comparative experiment on the gas-liquid separation effect of the gas-liquid cascade separation device of the present invention and Comparative Example 2.

[0091] This embodiment is used to verify the advancements of the gas-liquid cascade separation device and method of the present invention in inducing the coalescence of microbubbles, thereby improving the gas-liquid separation effect. In the comparative experiment of this embodiment, the gas-liquid cascade separation device and method described in Example 3 are used, while Comparative Example 2 does not have a coalescing fiber membrane layer and only uses a hydrocyclone separator for degassing. After the electrolytic mixture enters the hydrocyclone separator, some bubbles are removed under the action of the cyclone centrifugal force field. The electrolyte inlet conditions are the same as in the embodiment, and the Reynolds number of the flowing electrolyte is 2000. The gas content of the recovered electrolyte in the embodiments and comparative examples is measured to detect its gas holdup, and the results are shown in Table 2.

[0092] Table 2. Gas-liquid separation effect of Examples and Comparative Example 2

[0093]

[0094] The results in Table 2 show that the liquid product electrolyte discharged from the gas-liquid separation device of the embodiment has very low contents of both microbubbles and large bubbles, with a gas content of only 0.0001%; ​​while Comparative Example 2 has less large bubble content and more microbubbles, with a gas content of 0.6%. This indicates that using a hydrocyclone separator to enhance bubble separation is effective for removing larger bubbles. However, the presence of the coalescing fiber membrane can induce the coalescence of microbubbles, significantly improving the removal efficiency of microbubbles.

[0095] Example 5: Comparative experiment on the gas-liquid separation effect of the gas-liquid staged separation device of the present invention and Comparative Example 3.

[0096] This embodiment is used to verify the advancements of the gas-liquid cascade separation device and method of the present invention in inducing efficient and rapid detachment of bubbles, thereby improving the gas-liquid separation effect. In the comparative experiment of this embodiment, the gas-liquid cascade separation device and method described in Example 3 are used. Comparative Example 3 does not use a cyclone separator, but only a coalesced fiber membrane layer for degassing. When the electrolytic mixture enters the gas-liquid separation device and comes into contact with the coalesced fiber membrane layer, the microbubbles continuously coalesce into large bubbles, and finally rise and detach from the electrolyte under the action of buoyancy. The electrolyte inlet conditions are the same as in Example 1, and the Reynolds number of the flowing electrolyte is 2000. The gas content of the recovered electrolyte in the embodiments and comparative examples is measured to detect its gas holdup, and the results are shown in Table 3.

[0097] Table 3. Gas-liquid separation effect of Examples and Comparative Example 3

[0098]

[0099] Table 3 shows that the liquid product electrolyte discharged from the gas-liquid separation device of the embodiment has very low contents of both microbubbles and large bubbles, with a gas content of only 0.0001%; ​​while the content of large bubbles in Comparative Example 2 is relatively low, while the content of microbubbles is significantly increased, with a gas content of 0.9%. This indicates that using only coalesced fiber membranes to enhance microbubble separation is relatively ineffective. Since the porosity of the fibers is constant, for electrolytes with high gas content, a large number of bubbles in the electrolyte can easily cause fiber blockage, resulting in poor degassing and hindering the efficient and rapid detachment of bubbles from the electrolyte.

[0100] In summary, the gas-liquid gradient separation device and method for high gas content electrolytes of the present invention achieves graded gradient enhanced electrolyte bubble separation by combining a swirling centrifugal force field with a coalescing fiber membrane layer. In this invention, the high gas content electrolyte first undergoes initial rapid separation of large bubbles under the action of the swirling centrifugal force field; subsequently, microbubbles in the electrolyte coalesce, continuously rise, and detach from the electrolyte under the induction of the coalescing fibers, achieving deep separation of microbubbles. The gas-liquid gradient separation device and method of the present invention not only ensures that the gas content of the electrolyte returning to the electrolyzer is less than 0.0001%, significantly reducing the gas content in the electrolyte and thus ensuring the safe and efficient operation of the entire system and increasing the electrolysis efficiency of the electrolyzer; it also optimizes the structure of the gas-liquid separation equipment, making it easy to install and reducing equipment usage and maintenance costs.

[0101] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely illustrative of the principles of the invention. Various changes and modifications can be made to the invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the present invention as claimed. The scope of protection of this invention is defined by the appended claims and their equivalents.

Claims

1. A gas-liquid cascade separation device for enhancing electrolyte bubble separation, characterized in that, The system includes an alkaline electrolytic cell, a gas-liquid separation device connected to the outlet of the alkaline electrolytic cell via a centrifugal pump, a gas purification device and a gas collection device connected sequentially after the gas phase outlet of the gas-liquid separation device, and a filtration device connected to the liquid phase outlet of the gas-liquid separation device. The gas-liquid separation device contains a hydrocyclone separator and a coalescing fiber membrane layer arranged vertically inside; wherein: The gas phase outlet and liquid phase outlet of the gas-liquid separator are respectively located at the top and bottom of the gas-liquid separator. The hydrocyclone separator is a vertical columnar cavity structure. The middle and bottom of the vertical columnar cavity are respectively provided with a mixed phase inlet and a liquid phase outlet. The top of the hydrocyclone separator is provided with a concave bowl-shaped top cover, and the bottom is provided with a double inner cone core. The coalescing fiber membrane layer is located below the hydrocyclone separator. The fiber weave pattern of the coalescing fiber membrane layer is a continuous weave, the diameter of the woven fibers is 100-200 μm, and the porosity is 0.70-0.

85. The coalescing fiber membrane layer is arranged in multiple layers with intervals, and the number of layers is 5-10. The filtration device is connected to the liquid phase outlet of the gas-liquid separator and the inlet of the alkaline electrolytic cell via pipelines. The bottom of the double inner cone core is set as a column, and its bottom surface is on the same horizontal plane as the bottom surface of the liquid phase outlet of the hydrocyclone separator. The upper cone of the double inner conical core of the cyclone separator has a cone angle of 40°, the lower cone has a taper of 20°, the total height of the upper and lower cones is 125-150mm, and the diameter of the cone bottom is 0.4-0.6 times the diameter of the cyclone separator; the height of the column at the bottom of the double inner conical core is 0.1-0.3 times the height of the cone.

2. The gas-liquid cascade separation device for enhanced electrolyte bubble separation according to claim 1, characterized in that, The mixed phase inlet and liquid phase outlet of the cyclone separator are both tangential.

3. The gas-liquid cascade separation device for enhanced electrolyte bubble separation according to claim 2, characterized in that, The mixed phase inlet of the cyclone separator is a rectangular nozzle; the number of liquid phase outlets of the cyclone separator is set to 2, which are horizontally symmetrically distributed, and their bottom surfaces are on the same horizontal plane as the bottom surface of the cyclone separator.

4. The gas-liquid staged separation device for enhanced electrolyte bubble separation according to claim 2, characterized in that, The inner diameters of the mixed phase inlet and liquid phase outlet of the cyclone separator are both 15-20 mm, the column cavity diameter of the cyclone separator is 60-80 mm, and the column cavity height is 480-640 mm; the diameter of the tank of the gas-liquid separation device is 0.5-1.0 m, and the height is 3-4 m.

5. The gas-liquid cascade separation device for enhanced electrolyte bubble separation according to claim 1, characterized in that, The top of the cyclone separator is provided with a gas phase outlet. The gas phase outlet of the cyclone separator is provided with a tapered overflow pipe inside the vertical column cavity. The tapered overflow pipe is arranged in an offset manner, and its central axis is offset from the central axis of the gas-liquid separation device.

6. The gas-liquid cascade separation device for enhanced electrolyte bubble separation according to claim 5, characterized in that, The tapered overflow pipe is fixed to the surrounding wall using a trapezoidal thick wall. The top inner diameter and bottom inner diameter of the tapered overflow pipe are 10-15 mm and 15-20 mm, respectively.

7. The gas-liquid cascade separation device for enhanced electrolyte bubble separation according to claim 1, characterized in that, The coalesced fiber membrane layer is arranged at an angle of 25° to 40° with respect to the horizontal plane.

8. The gas-liquid staged separation device for enhanced electrolyte bubble separation according to claim 1, characterized in that, The coalesced fiber membrane layer uses polytetrafluoroethylene as its braided fiber material.

9. A gas-liquid staged separation method, employing the gas-liquid staged separation device for enhanced electrolyte bubble separation as described in any one of claims 1-8, characterized in that, The gas-liquid stepwise separation method includes the following steps: Step 1: Perform primary separation using a hydrocyclone separator: After electrolysis in a high-power alkaline electrolytic cell, the electrolyte becomes a gas-liquid mixture with high gas content and microbubbles. Driven by a centrifugal pump, the gas-liquid mixture enters the mixed phase inlet of the hydrocyclone separator tangentially from the pipeline. Inside the hydrocyclone separator, it is subjected to the centrifugal force field of the cyclone separator, achieving the effect of primary separation, in which larger bubbles are removed. Step 2: Preliminary separation of the gas and liquid phases: Subsequently, the gas and liquid phases are discharged from the gas phase outlet and liquid phase outlet of the hydrocyclone separator, respectively. During the upward movement of the gas phase containing trace amounts of electrolyte, the liquid phase is removed due to the action of the bowl-shaped top cover baffle. The liquid phase then flows downwards into the inner cavity of the gas-liquid separator, achieving preliminary separation of the liquid and gas phases; Step 3: Secondary separation using coalesced fiber membranes: The liquid electrolyte entering the inner cavity of the gas-liquid separator contains a certain amount of microbubbles. When the electrolyte flows through the coalescing fiber membrane, the bubbles coalesce due to the turbulent action of the coalescing fibers. Bubbles that have coalesced to a certain extent rise from the fiber surface under the action of buoyancy, and coalesce with other bubbles in the fiber during this process, eventually forming larger bubbles that detach from the electrolyte. This achieves a two-stage deep separation effect, and the microbubbles in the electrolyte are removed. Step 4: Collection and recovery of gas and liquid phases The separated gas phase flows along the gas phase outlet of the gas-liquid separator to the gas purification unit for drying, and finally enters the gas collection unit for collection; The liquid phase flows through the liquid phase outlet of the gas-liquid separator to the pipeline, and after passing through the filtration device and being supplemented with an appropriate amount of pure water, it can be recycled back into the electrolytic cell.

10. The gas-liquid stepwise separation method according to claim 9, characterized in that, In step one, the electrolyte contains 30% to 40% gas, and the bubble diameter is 50 μm to 1 mm.

11. The gas-liquid stepwise separation method according to claim 9, characterized in that, In step one, the electrolyte in the electrolytic cell is a KOH solution with a mass concentration of 25-30% and a pH of 13.2-13.

8.

12. The gas-liquid stepwise separation method according to claim 9, characterized in that, The pressure of the gas-liquid mixture at the inlet of the cyclone separator in step one is 0.6–0.8 MPa, and the inlet velocity is 2.8–3.2 m / s.

13. The gas-liquid stepwise separation method according to claim 9, characterized in that, In step two, the volume of the electrolyte in the gas-liquid separation device is controlled to be 70-80% of the volume of the gas-liquid separation device.

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