Integrated liquid hydrogen transmission pipeline gas-liquid separation device

Abstract

The present invention discloses an integrated gas-liquid separation device for a liquid hydrogen delivery pipeline. The present invention comprises an inlet pipeline, a separator pipeline, a liquid outlet pipeline, and a gas outlet pipeline. The inlet pipeline is divided into two paths after passing through the separator pipeline, one being a liquid outlet pipeline and the other being a gas outlet pipeline. The liquid outlet pipeline is coaxial with the inlet pipeline, and the gas outlet pipeline is perpendicular to the liquid outlet pipeline. The separator pipeline adopts a Venturi structure, and cavitation occurs in the separator pipeline, thereby enhancing the gas-liquid separation effect of liquid hydrogen. The Venturi structure separator, lyophilic coating, and gasophilic coating of the present invention can effectively separate gas and liquid in a two-phase flow of liquid hydrogen. The gas-liquid separator has no moving parts and requires no maintenance.

Description

Technical Field

[0001] The present invention relates to a gas-liquid separation device, in particular to an integrated liquid hydrogen delivery pipeline gas-liquid separation device. Background Art

[0002] Liquid hydrogen easily vaporizes and has an extremely high volume expansion rate. Therefore, cryogenic conditions must be maintained during storage and transportation, and safe exhaust components must be designed. When liquid hydrogen flows through a pipeline, changes in temperature or pressure can easily cause it to vaporize, overpressurizing the pipeline. This increased pressure can cause vibration, blockage, or even explosion, compromising the reliability and safety of the pipeline system. A gas-liquid separator is a device that generally separates gas-liquid two-phase flow into liquid and gas phases. To ensure pipeline safety, a gas-liquid separator must be installed at certain locations in the liquid hydrogen pipeline to discharge the gases generated during the liquid hydrogen flow process. This separator plays a vital role in ensuring the safe operation of the pipeline system.

[0003] Gas-liquid separation is primarily accomplished by gravity separation and cyclone separation. Gravity separation utilizes the gravity difference between the different densities of gas and liquid. This method requires a relatively long downtime, generally occupies a large area, is bulky, and has high initial investment and subsequent maintenance costs. It is generally not used for pipeline gas-liquid separation. Cyclone separation utilizes the centrifugal forces generated by the swirling flow of a gas-liquid mixture to separate gas and liquid, and is available in a variety of methods. However, since hydrogen is prone to hydrogen embrittlement, which significantly affects components involved in the cyclone, there are relatively few dedicated hydrogen gas-liquid separation methods for this purpose.

[0004] Existing hydrogen gas-liquid separation is mostly achieved through separation boxes and separation tanks, which use gravity separation or cyclone separation. These devices are relatively large and installed in pipelines as separate equipment, requiring subsequent inspection and maintenance. Few technologies can achieve gas-liquid separation with small, maintenance-free devices in pipelines. Summary of the Invention

[0005] In view of the deficiencies of the prior art, the present invention provides an integrated gas-liquid separation device for a liquid hydrogen transportation pipeline.

[0006] The present invention comprises an inlet pipe, a separator pipe, a liquid outlet pipe and an air outlet pipe; the inlet pipe is divided into two pipes after passing through the separator pipe, one is a liquid outlet pipe and the other is an air outlet pipe; the liquid outlet pipe is coaxial with the inlet pipe, and the air outlet pipe is perpendicular to the liquid outlet pipe;

[0007] The separator pipeline adopts a Venturi structure, and cavitation occurs in the separator pipeline, thereby enhancing the gas-liquid separation effect of liquid hydrogen.

[0008] Beneficial effects of the present invention: The Venturi structure separator, lyophilic coating and gas-philic coating of the present invention can effectively separate gas and liquid in liquid hydrogen two-phase flow, and the gas-liquid separator has no moving parts and does not require maintenance. BRIEF DESCRIPTION OF THE DRAWINGS

[0009] The exemplary embodiments and descriptions of the present invention are intended to explain the present invention and do not constitute undue limitations on the present invention. This specification includes the following drawings:

[0010] Figure 1 It is a schematic diagram of the three-dimensional structure of the gas-liquid separation device of the present invention;

[0011] Figure 2 The pressure diagrams of the middle axis of the numerical simulation of liquid hydrogen cavitation for each model are shown. The pressure diagrams of the middle axis of the numerical simulation of cavitation for the contraction sections are 0.56D, 0.60D, 0.68D, and 0.76D, respectively. The speed of pressure drop affects the cavitation effect of liquid hydrogen.

[0012] Figure 3 The pressure diagrams of the middle axis of the numerical simulation of hydrogen condensation in each model are shown. The pressure diagrams of the middle axis of the numerical simulation of condensation in the contraction sections are 0.56D, 0.60D, 0.68D, and 0.76D, respectively. The speed of pressure drop affects the condensation effect of hydrogen.

[0013] Figure 4 1. It is a schematic diagram of separator pipeline parameters of the gas-liquid separation device of the present invention;

[0014] Figure 5 It is a schematic cross-sectional view of the gas-liquid separation device of the present invention;

[0015] Figure 6 It is a partial cross-sectional view of the upper half of the separator pipeline of the present invention;

[0016] Figure 7 It is a partial cross-sectional view of the lower half of the separator pipeline of the present invention;

[0017] The following are marked in the figure:

[0018] 1. Inlet pipe; 2. Contraction section; 3. Throat; 4. Diffusion section; 5. Air outlet pipe; 6. Liquid outlet pipe; 7. Liquid-philic coating; 8. Air-philic coating; 9. Insulation layer; 10. Anti-corrosion paint. DETAILED DESCRIPTION

[0019] In order to help those skilled in the art better understand the present invention, the specific embodiments of the present invention are further described in conjunction with the accompanying drawings.

[0020] The device of the present invention comprises an inlet pipe, a separator pipe, a liquid outlet pipe and a gas outlet pipe. The entire device is horizontally installed on an industrial production pipeline.

[0021] The inlet pipe is tightly connected to the liquid hydrogen gas-liquid two-phase flow inlet pipe, the liquid outlet pipe is tightly connected to the liquid hydrogen outlet pipe, and the gas outlet pipe is tightly connected to the hydrogen and other waste gas outlet pipes, and flows out vertically upward.

[0022] The separator pipeline is connected between the inlet pipeline, the liquid outlet pipeline and the gas outlet pipeline, that is, a one-inlet and two-outlet form.

[0023] In a possible implementation, the separator pipe is a Venturi structure, which includes a contraction section, a throat section, and a diffusion section. Cavitation occurs in the separator pipe, which improves the effect of liquid hydrogen gas-liquid separation.

[0024] In a possible implementation process, the cross-sectional area of ​​the contraction section becomes smaller, and its flow rate is inversely proportional to the flow cross-section. According to Bernoulli's principle, the increase in flow rate is accompanied by a decrease in fluid pressure. When the pressure drops to the saturated vapor pressure of the liquid, gasification occurs and hydrogen is produced.

[0025] In one possible implementation process, the throat has the smallest cross-sectional area, the fastest fluid flow rate, the lowest pressure, and is most likely to vaporize. The throat outlet flow channel begins to expand, where the flow channel changes from gradually contracting to gradually expanding, so that the fluid starts to decelerate from accelerating. Due to flow inertia, two flow vortices are easily formed on the upper and lower walls near the throat. The pressure at the center of the vortex is low, making it easy for liquid hydrogen to vaporize at the center.

[0026] In one possible implementation, the diffuser section has a larger cross-section, which reduces the average velocity of the gas-liquid two-phase flow, increases the average pressure, and raises the liquid's saturation temperature, making it less likely to vaporize. The diffuser section design increases the pressure, creating a certain degree of subcooling for the liquid hydrogen, ensuring that it is less likely to vaporize as it flows through the downstream pipeline.

[0027] In a preferred example, the liquid hydrogen gas-liquid separation device is entirely made of austenitic stainless steel, which effectively avoids the occurrence of hydrogen embrittlement of liquid hydrogen and increases the durability of the separator.

[0028] In a preferred embodiment, the outer surface of the pipeline of the liquid hydrogen separation device is coated with anti-corrosion paint, which effectively prevents water vapor from penetrating the steel and causing cracks, thereby protecting the integrity of the pipeline.

[0029] In a preferred example, the pipeline of the liquid hydrogen gas-liquid separation device includes an insulation layer, which has a total of 5 layers, each layer is 2 mm thick, and each layer is composed of 0.05 mm thick aluminum foil and 0.20 mm thick alkali-free glass fiber cloth cross-overlapping. The separator pipeline is not used to transport low-temperature liquid hydrogen over long distances, but is only used for a short time, so the insulation layer does not need to be very large, and this insulation layer can keep the pipeline low temperature.

[0030] In one preferred embodiment, to enhance the fluid's wall adhesion and minimize flow separation, the gas-liquid separator is coated with both an aerophilic and a lyophilic coating. When the pipes are positioned horizontally, the upper half of the inlet pipe's inner wall, the upper half of the separator pipe's inner wall, and the gas outlet pipe are coated with the aerophilic coating; the lower half of the inlet pipe's inner wall, the lower half of the separator pipe's inner wall, and the liquid outlet pipe's inner wall are coated with the lyophilic coating, and these coatings cannot be reversed. The aerophilic and lyophilic layers ensure that liquid flows closer to the bottom of the pipe and gas flows closer to the top, further facilitating gas-liquid separation.

[0031] like Figure 1 and Figure 5 As shown, the gas-liquid separation device disclosed in this embodiment comprises an inlet pipe 1, an outlet pipe 5, and a liquid outlet pipe 6, serving as the gas-liquid separator's inlet, condensate vapor outlet, and liquid outlet, respectively. The inlet pipe 1 connects to a contracting section 2, followed by a throat 3 and a diverging section 4, before finally connecting to the outlet pipe 5. The entire pipe is wrapped with an insulating layer 9 to maintain a low temperature.

[0032] like Figure 6 and Figure 7 As shown, the inner wall of the gas-liquid separation device is coated, and the lower half surface of the inner wall of the inlet pipe 1, the contraction section 2, the throat 3, the diffusion section 4, the gas outlet pipe 5 and the liquid outlet pipe 6 are coated with a liquid-philic coating 7; the upper surface of the inner wall of the inlet pipe 1, the contraction section 2, the throat 3, and the diffusion section 4 is coated with an air-philic coating 8.

[0033] It is noteworthy that when the gas-liquid separation device is placed horizontally, the inner wall coated with the air-philic coating 8 is always kept at the top.

[0034] Furthermore, the lyophilic coating 7, composed of a water-absorbing resin with a particle size of less than 80 μm, a curing agent, and a thinner, is applied to the inner wall and dried at high temperature. This coating also inhibits frost formation on other condensed liquids in the fluid. A coating thickness of approximately 0.2 mm effectively inhibits frost formation, demonstrating lyophilic properties.

[0035] Furthermore, the aerophilic coating 8 is coated on the required inner wall by a sol-gel method with a silica sol having a particle size of 80-100 nm, and then a layer of carbon is attached by a candle flame, which is repeatedly stacked 4 times, and then modified and dried by chemical vapor deposition to obtain the aerophilic coating 8. This coating has strong stability and has waterproof and self-cleaning effects.

[0036] The outer surface of the stainless steel pipeline of the liquid hydrogen gas-liquid separation device is coated with epoxy coal tar anti-corrosion paint, which has excellent water resistance and prevents water vapor from penetrating into the steel and causing cracks due to condensation expansion. It can effectively protect the pipeline and avoid low-temperature damage.

[0037] Industrial hydrogen two-phase fluid enters the gas-liquid separator from inlet pipe 1. In contraction section 2, the fluid cross-sectional area decreases, increasing the flow rate and decreasing the pressure. Upon entering throat pipe 3, the liquid hydrogen and hydrogen condensate separate, with more pronounced vaporization. As the fluid enters diffusion section 4, the gas extends along the pipe wall. Due to the density difference between gas and liquid, hydrogen, with its lower density, flows along the upper pipe wall into gas outlet pipe 5, while liquid hydrogen flows out through liquid outlet pipe 6, achieving gas-liquid separation.

[0038] like Figure 2 、 Figure 3 and Figure 4 As shown in the figure, to achieve better liquid hydrogen gas-liquid separation, a numerical calculation method is used to calculate the length and angle of the separator pipeline's diffuser section. The maximum pipe diameter r1 of the contraction and diffuser sections is set to D, the throat diameter r2 is set to 0.2D, and the fixed throat length l2 is set to 0.24D. The length of the contraction section l1 is set to 0.56D, 0.60D, 0.68D, and 0.76D, respectively. The shorter the contraction section length, the larger the inlet cone angle ɵ1 and the smaller the outlet cone angle ɵ2.

[0039] Calculation results show that when liquid hydrogen enters the throat, the fluid cross-section decreases and the flow velocity increases, resulting in increased flow velocity and decreased static pressure. Due to the reduced pressure, liquid hydrogen vaporizes on the tube wall, extending all the way to the junction of the diffuser and throat, and extending along the diffuser. Pressure changes vary with the length of the contraction. The calculated gas phase fractions are 0.244%, 0.2%, 0.2%, and 0.181%, respectively. A shorter contraction length l1 corresponds to a larger inlet cone angle ɵ1 and a longer diffuser l2. When the inlet cone angle ɵ1 is small, the pressure change at the throat exit corner is less pronounced, resulting in a low vaporization rate. A larger inlet cone angle ɵ1 increases cavitation. The gas phase fraction is minimized at a contraction length of 0.76D, with inlet and outlet cone angles of 27.76° and 21.8°, respectively.

[0040] Calculation results show that hydrogen does not condense after entering the throat under these operating conditions. Analysis of the pressure along the mid-axis shows that the shorter the contraction section, the earlier the pressure drop occurs and the smaller the pressure recovery slope. Slower pressure recovery reduces the conditions for liquid hydrogen condensation, further suppressing condensation.

[0041] Through the above simulation analysis, the separator pipeline dimensions are as follows: the maximum pipe diameter r1 of the contraction section and the diffusion section is D, the throat diameter r2 is 0.20D, the contraction section length l1 is 0.76D, the throat length l2 is 0.24D, the diffusion section length l3 is D, and when the total length of the separator pipeline is 2D, the liquid hydrogen gas-liquid separation effect is better, the liquid hydrogen will not be excessively separated, and the liquid hydrogen in the pipeline is effectively retained.

[0042] The directional words such as up and down involved in the above content are defined based on the horizontal orientation of the gas-liquid separator inlet pipe 1 and the liquid outlet pipe 6, and the vertically upward orientation of the outlet direction of the gas outlet pipe 5. It should be understood that the use of the directional words should not limit the scope of protection requested in this application.

[0043] The above describes the basic operating methods of the gas-liquid separation device. Specific parameters can be selected for this liquid-hydrogen gas-liquid separation device based on specific operating conditions, including separator pipe diameter, pipe length, vacuum insulation layer thickness, and the selection of liquid- and gas-philic coating materials and anti-corrosion paint. Any non-substantial improvements utilizing the method concepts and technical solutions of the present invention, or the direct application of the above-mentioned concepts and technical solutions to other applications without modification, fall within the scope of protection of the present invention.

Claims

1. An integrated gas-liquid separation device for liquid hydrogen transportation pipeline, characterized by: Including inlet pipe, separator pipe, liquid outlet pipe and gas outlet pipe; The inlet pipe is divided into two parts after passing through the separator pipe, one is a liquid outlet pipe and the other is a gas outlet pipe; the liquid outlet pipe is coaxial with the inlet pipe, the gas outlet pipe is perpendicular to the liquid outlet pipe, and the gas outlet pipe is arranged vertically upward; The separator pipeline adopts a Venturi structure, which includes a contraction section, a throat section and a diffusion section. Liquid hydrogen undergoes cavitation in the separator pipeline, thereby enhancing the gas-liquid separation effect of the liquid hydrogen.

2. The integrated gas-liquid separation device for liquid hydrogen transportation pipeline according to claim 1 is characterized in that: An air-friendly coating is applied on the upper half surface of the inner wall of the inlet pipe, the upper half surface of the inner wall of the separator pipe and the inner wall of the outlet pipe; The lower half surface of the inner wall of the inlet pipe, the lower half surface of the inner wall of the separator pipe and the inner wall of the liquid outlet pipe are coated with a lyophilic coating.

3. The integrated gas-liquid separation device for liquid hydrogen transportation pipeline according to claim 2 is characterized in that: The lyophilic coating is composed of a water-absorbing resin with a particle size of less than 80 μm, a curing agent and a thinner, and the coating thickness is 0.2 mm.

4. The integrated gas-liquid separation device for liquid hydrogen transportation pipeline according to claim 2 is characterized in that: The aerophilic coating is prepared by coating a silicon dioxide sol with a particle size of 80-100 nm using a sol-gel method, and then attaching a layer of carbon using a candle flame, followed by chemical vapor deposition modification and drying to obtain the aerophilic coating.

5. The integrated gas-liquid separation device for liquid hydrogen transportation pipeline according to any one of claims 1 to 4, characterized in that: The entire device is made of austenitic stainless steel.

6. The integrated gas-liquid separation device for liquid hydrogen transportation pipeline according to claim 5, characterized in that: The outer surface of the device is coated with epoxy coal tar anti-corrosion paint.

7. The integrated gas-liquid separation device for liquid hydrogen transportation pipeline according to claim 5, characterized in that: The device is provided with a heat insulation layer, which has 5 layers in total, each layer is 2 mm thick, and each layer is composed of 0.05 mm thick aluminum foil and 0.20 mm thick alkali-free glass fiber cloth cross-over and overlap.

8. The integrated gas-liquid separation device for liquid hydrogen transportation pipeline according to claim 5, characterized in that: Assume that the maximum diameter of the contraction section and the diffusion section is D , then the throat diameter is 0.20 D , the length of the contraction section is 0.76 D , the throat length is 0.24 D The length of the diffusion section is D , the total length of the separator pipeline is 2 D .

9. The integrated gas-liquid separation device for liquid hydrogen transportation pipeline according to claim 8, characterized in that: The entire device is installed horizontally on the industrial production pipeline.

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