Water segregator device for MV-grade PEM hydrogen production system and design method

Abstract

The invention relates to a water segregator device for an MV-level PEM hydrogen production system and a design method. One end of a first-level gas-liquid separation tank is connected with an input pipe, a first-level water outlet is formed in the lower side of the other end of the first-level gas-liquid separation tank, a first-level gas output pipeline is arranged on the upper side of the other end of the first-level gas-liquid separation tank, and a first cross-flow water diversion plate and a second cross-flow water diversion plate are arranged in the first-level gas-liquid separation tank in a staggered mode; the first-stage gas output pipeline is connected with one end of the second-stage gas-liquid separation tank, the other end of the second-stage gas-liquid separation tank is connected with the middle of the third-stage gas-liquid separation tank through the second-stage gas output pipeline, and a second-stage water outlet is formed in the lower side of the middle of the second-stage gas-liquid separation tank; a third-stage gas output pipeline is arranged at the upper end of the third-stage gas-liquid separation tank, a third-stage water outlet is formed in the lower end of the third-stage gas-liquid separation tank, and a separation silk screen is arranged in the upper end of the third According to the invention, three stages of gas-liquid separation tanks are combined, and the structural design of each stage of gas-liquid separation tank is optimized, so that the gas-water separation efficiency is improved, and the stable operation of the MW-stage PEM electrolytic bath can be ensured.

Description

Technical Field

[0001] The invention relates to the technical field of PEM hydrogen production, in particular to a water separator device and a design method for a MV-level PEM hydrogen production system. Background Art

[0002] PEM water electrolysis is an emerging hydrogen production technology. Its working principle is that water molecules are first decomposed into oxygen and hydrogen ions (H+) under the catalytic action of the anode catalyst, and then H+ passes through the PEM membrane between the cathode and the cathode, and then generates hydrogen under the catalysis of the cathode catalyst. Since the hydrogen produced at the cathode and the oxygen produced at the anode are separated by the PEM membrane, PEM water electrolysis has the advantages of high hydrogen purity (>99.99%). At the same time, PEM water electrolysis has the advantages of high energy conversion efficiency, fast response speed, and small footprint.

[0003] Megawatt-class (MW-class) PEM hydrogen production systems, due to their large-scale hydrogen production capacity, have shown great application potential in industrial production, transportation and energy storage. However, during the operation of MW-class PEM hydrogen production systems, how to effectively separate and discharge the water produced during the electrolysis process has become a key issue to ensure the stable operation of the system. Due to the large hydrogen production capacity of megawatt-class (MW-class) PEM hydrogen production systems, when the PEM electrolyzers are running for a long time, in addition to hydrogen and oxygen, more water will be produced by electrolyzing water. If the water is not handled properly, it is easy to cause the humidity inside the electrolyzer to be too high or too low, which in turn affects the electrolysis efficiency and the stability of the electrolyzer. Therefore, the water separator device used in MW-class PEM hydrogen production systems is required to have a higher and more stable efficiency.

[0004] In the prior art, the gas-liquid separation tank used in the PEM hydrogen production system mainly adopts a single tank structure, and uses the principle that liquid falls due to gravity and gas rises to separate the gas and liquid. For example, the patent CN115181997B discloses a gas-liquid separator and a hydrogen production device for hydrogen production, which includes a separator body, and a first separation unit and a second separation unit are arranged in the cavity of the separator body. However, the device performs a second separation on the gas-liquid mixture to significantly reduce the electrolyte mist and / or alkali foam entrained in the gas flowing out of the gas outlet, reduce the number of times the electrolyte is replenished, and improve the separation efficiency of the gas-liquid separator.

[0005] For example, the patent CN221014974U also discloses a gas-liquid separator for electrolytic hydrogen production and its system, which includes a tank body, and the tank body is provided with an independent entry area, a water drop area and a liquid reflux area, and its flow guide mechanism includes a gas-liquid distribution plate arranged in the entry area and an inlet filler arranged between the gas-liquid distribution plate and the water drop area, and its water drop mechanism includes a triangular weir groove arranged inside the water drop area, a water storage tank arranged below the triangular weir groove, and a water drop well connecting the water storage tank and the liquid reflux area. However, the design purpose of this device is to avoid frequent start and stop of the water replenishment port due to liquid level fluctuations, which not only solves the problem of wasting materials but also causes control errors in signal acquisition and PLC control systems.

[0006] For example, the patent CN118987920A discloses a gas-liquid separation device for electrolytic hydrogen production, which includes a separation tank, and a gas-liquid mixture discharge pipe is fixedly installed on one side of the bottom of the separation tank, a liquid discharge pipe is fixedly installed on the other side of the bottom of the separation tank, a connecting tank is fixedly installed on the top of the outer surface of the separation tank, and two special-shaped boxes are provided at the connecting tank. However, the device uses a drying device to drive the bamboo fiber cloth from the inside of the two special-shaped boxes, and can also heat and dry the bamboo fiber cloth in time. The bamboo fiber cloth can absorb the water vapor mixed in the hydrogen during the transmission process. At the same time, the two bamboo fiber cloths are used together, which has a better effect on water vapor absorption and realizes a more effective and thorough separation of gas and liquid. The structure of the device is relatively complex.

[0007] In the prior art Summary of the invention

[0008] The object of the present invention is to provide a water separator device and design method for an MV-level PEM hydrogen production system, which adopts a three-stage gas-liquid separation tank combination and optimizes the structural design of each stage of the gas-liquid separation tank, thereby improving the gas-water separation efficiency, ensuring the stable operation of the MW-level PEM electrolyzer, and extending the overall service life of the system.

[0009] The objective of the present invention is achieved through the following technical solutions:

[0010] A water separator device for an MV-level PEM hydrogen production system comprises a primary gas-liquid separation tank, a secondary gas-liquid separation tank and a tertiary gas-liquid separation tank, wherein the primary gas-liquid separation tank and the secondary gas-liquid separation tank are arranged in parallel, and the tertiary gas-liquid separation tank is arranged vertically to the secondary gas-liquid separation tank, one end of the primary gas-liquid separation tank is connected to an input pipe, a primary drain outlet is arranged at the lower side of the other end, and a primary gas output pipeline is arranged at the upper side, a first cross-flow water separator plate and a second cross-flow water separator plate are staggered inside the primary gas-liquid separation tank along the length direction, and the first cross-flow water separator plate is staggered along the length direction of the first cross-flow water separator plate ... A first gap is provided at the upper end of the water plate, a second gap is provided at the lower end of the second cross-flow water distribution plate, a water flow through hole is provided on the first cross-flow water distribution plate, the first-level gas output pipeline is connected to one end of the second-level gas-liquid separation tank, the other end of the second-level gas-liquid separation tank is connected to the middle of the tertiary gas-liquid separation tank through the second-level gas output pipeline, a second-level drain port is provided on the lower side of the middle of the second-level gas-liquid separation tank, a third-level gas output pipeline is provided at the upper end of the tertiary gas-liquid separation tank, a third-level drain port is provided at the lower end, and a separation screen is provided inside the upper end of the tertiary gas-liquid separation tank.

[0011] The diameter D of the primary gas-liquid separation tank T Determined according to the following formula:

[0012]

[0013] In the above formula (1), C = L T / D T , D T , L T are the diameter and length of the first-stage gas-liquid separation tank respectively; V L is the volume flow rate of the liquid; t is the residence time; A is the variable liquid area, A = A TOT -(Aa+Ab), middle A TOT is the total cross-sectional area of ​​the primary gas-liquid separation tank, Aa is the cross-sectional area of ​​the gas portion, and Ab is the cross-sectional area occupied by the liquid when the liquid level is the lowest.

[0014] The distance L between the inlet of the first-level gas-liquid separation tank connected to the input pipe and the first-level drain port N Determined according to the following formula:

[0015]

[0016] In the above formula (2), a is the height of the gas space; V G is the gas flow rate; ρL , ρG are the liquid density and gas density respectively; R = τs / τT, where τs is the time required for a droplet with a diameter of d* to pass through the gas space height a; τT is the gas residence time.

[0017] The air velocity u on the separation wire mesh GDetermined according to the following formula:

[0018] u G =c·m·u0 (7);

[0019] In the above formula (7), c is the safety factor, u0 is the critical flow rate, and m is the correction factor, which can be obtained by looking up the table:

[0020]

[0021] In the above formula (8), g is the acceleration of gravity, ε is the mesh porosity, and ρ is L , G are the densities of liquid and gas respectively, a' is the specific surface area of ​​the wire mesh, μL is the liquid viscosity and the N coefficient is obtained by looking up the table.

[0022] A design method for a water separator device for a MV-level PEM hydrogen production system comprises the following steps:

[0023] Step 1: Design the primary gas-liquid separation tank, specifically:

[0024] Step 1.1: Determine the diameter D of the primary gas-liquid separation tank T :

[0025]

[0026] In the above formula (1), C = L T / D T , D T , L T are the diameter and length of the first-stage gas-liquid separation tank respectively; V L is the volume flow rate of the liquid; t is the residence time; A is the variable liquid area, that is: A = A TOT -(A a +A b ), all expressed as percentages, of which A TOT A is the total cross-sectional area of ​​the primary gas-liquid separation tank, a is the gas partial cross-sectional area, A b is the cross-sectional area occupied by the liquid when the liquid level is at its lowest;

[0027] When calculating, first take A = m1%, and according to the actual working conditions, assume that the gas space area Aa is m2%, and the minimum liquid area Ab is m3%, and then calculate D according to the above formula (1) T , then according to D T and A a The height of the gas space is obtained as a, a=D T ×A a, the value of a is not less than the set value h. If it is less than h, a new diameter calculation is required using the value of A<m1% until the value of a is greater than h;

[0028] Step 1.2: Determine the distance L between the inlet of the primary gas-liquid separation tank connected to the input pipe and the primary drain outlet N :

[0029]

[0030] In the above formula (2), a is the height of the gas space; V G is the gas flow rate; ρ L , G are the liquid density and gas density respectively; R = τs / τT, where τs is the time required for a droplet with a diameter of d* to pass through the gas space height a; τT is the gas residence time.

[0031] Step 2: Structural design of the secondary gas-liquid separation tank, specifically:

[0032] Step 2.1: According to the following formula (3), the floating velocity V of the material in the secondary gas-liquid separation tank is approximately estimated: t :

[0033]

[0034] In the above formula (3), V t is the floating flow velocity, ρ L , G is the density of liquid and gas, K S is the coefficient determined according to the liquid diameter d*;

[0035] Step 2.2: Accurately calculate V t :

[0036] First assume a Re number and calculate a V according to the following formula (4): t 'value:

[0037]

[0038] In the above formula (4), d* is the droplet diameter, g is the gravitational acceleration, and Cw is the drag coefficient;

[0039] Then calculate R according to the following formula (5): e :

[0040]

[0041] In the above formula (5), μ G is the gas viscosity;

[0042] According to the calculated Re, the new CW , substitute into the above formula (4), and repeat the calculation until the Re numbers of the two iterations are equal, at which point Vt′=Vt;

[0043] Then take the gas flow rate ue≤Vt in the secondary gas-liquid separation tank;

[0044] Step 2.3: Determine the diameter D of the secondary gas-liquid separation tank according to the following formula (6):

[0045]

[0046] In the above formula (6), V G max is the maximum volume flow rate of gas;

[0047] Step 3: Determine the gas flow rate of the separation screen at the upper end of the third-stage separation tank 6 uG :

[0048] u G =c·m·u0 (7);

[0049] In the above formula (7), c is the safety factor, u0 is the critical flow rate, and m is the correction factor, which can be obtained by looking up the table:

[0050]

[0051] In the above formula (8), g is the acceleration of gravity, ε is the mesh porosity, and ρ is L , G are the densities of liquid and gas respectively, a' is the specific surface area of ​​the wire mesh, μ L is the liquid viscosity and the N coefficient is obtained by looking up the table.

[0052] The advantages and positive effects of the present invention are:

[0053] 1. The present invention adopts a three-stage gas-liquid separation tank combination and optimizes the structural design of each stage of the gas-liquid separation tank, thereby improving the gas-water separation efficiency, ensuring the stable operation of the MW-level PEM electrolyzer, and extending the service life of the entire system.

[0054] 2. When the present invention is working, the gas is always in a flowing state in the gas-liquid separation tanks at each level, thereby being able to meet the large output requirements of the MW-level PEM hydrogen production system.

[0055] 3. The overall structure of the present invention is simple and compact, and will not significantly increase the manufacturing cost of the equipment. BRIEF DESCRIPTION OF THE DRAWINGS

[0056] Figure 1 It is a structural schematic diagram of the present invention,

[0057] Figure 2 for Figure 1An enlarged schematic diagram of the first cross-flow water distribution plate and the second cross-flow water distribution plate in FIG.

[0058] Figure 3 for Figure 1 The enlarged schematic diagram of the separation screen in

[0059] Figure 4 Schematic diagram of the relationship between the separation efficiency and gas velocity of the three-stage gas-liquid separation tank of the present invention.

[0060] Among them, 1 is an input pipe, 2 is a primary gas-liquid separation tank, 201 is a first cross-flow water distribution plate, 202 is a second cross-flow water distribution plate, 203 is a primary drain outlet, 204 is a first gap, 205 is a second gap, 3 is a primary gas output pipeline, 4 is a secondary gas-liquid separation tank, 401 is a secondary drain outlet, 5 is a secondary gas output pipeline, 6 is a tertiary gas-liquid separation tank, 601 is a tertiary drain outlet, and 7 is a separation screen. DETAILED DESCRIPTION

[0061] The present invention will be further described below in conjunction with the accompanying drawings.

[0062] like Figures 1 to 3 As shown, the present invention includes a primary gas-liquid separation tank 2, a secondary gas-liquid separation tank 4 and a tertiary gas-liquid separation tank 6, wherein the primary gas-liquid separation tank 2 and the secondary gas-liquid separation tank 4 are arranged in parallel, and the tertiary gas-liquid separation tank 6 is arranged vertically to the secondary gas-liquid separation tank 4, one end of the primary gas-liquid separation tank 2 is connected to the input pipe 1, and the lower side of the other end is provided with a primary drain port 203, and the upper side is provided with a primary gas output pipeline 3, and the first cross-flow water distribution plate 201 and the second cross-flow water distribution plate 202 are staggered inside the primary gas-liquid separation tank 2 along the length direction, and a first air gap is provided between the upper end of the first cross-flow water distribution plate 201 and the inner wall of the primary gas-liquid separation tank 2 A second gap 204 is provided between the lower end of the second cross-flow water-dividing plate 202 and the inner wall of the primary gas-liquid separation tank 2, a water flow through hole is provided on the first cross-flow water-dividing plate 201, the primary gas output pipeline 3 is connected to one end of the secondary gas-liquid separation tank 4, the other end of the secondary gas-liquid separation tank 4 is connected to the middle of the tertiary gas-liquid separation tank 6 through the secondary gas output pipeline 5, a secondary drain port 401 is provided on the lower side of the middle of the secondary gas-liquid separation tank 4, a tertiary gas output pipeline is provided at the upper end of the tertiary gas-liquid separation tank 6, a tertiary drain port 601 is provided at the lower end, and a separation screen 7 is provided inside the upper end of the tertiary gas-liquid separation tank 6.

[0063] When the present invention is working, the gas first enters the primary gas-liquid separation tank 2 through the input pipe 1. The first cross-flow water diversion plate 201 and the second cross-flow water diversion plate 202 inside the primary gas-liquid separation tank 2 cool the high-temperature gas and condense the water. The liquid after the water condenses is deposited downward under the action of gravity, and the liquid deposited at the bottom of the primary gas-liquid separation tank 2 can flow through the water flow holes at the bottom of the first cross-flow water diversion plate 201 and the second gap 205 on the lower side of the second cross-flow water diversion plate 202, and finally discharged from the primary drain port 203, and the gas goes upward and enters the secondary gas-liquid separation tank 4 through the primary exhaust pipeline 3.

[0064] The gas is separated in the secondary gas-liquid separation tank 4 mainly by gravity, wherein the heavier liquid and gas are separated again and fall to the bottom of the secondary gas-liquid separation tank 4 and are discharged through the secondary drain port 401, and the gas is output through the secondary gas output pipeline 5 into the tertiary gas-liquid separation tank 6.

[0065] After entering the tertiary gas-liquid separation tank 6 , the gas rises and passes through the separation screen 7 for separation again and is output from the tertiary gas output pipeline at the upper end of the tertiary gas-liquid separation tank 6 . The separated liquid sinks and is discharged through the tertiary drain port 601 .

[0066] The present invention realizes gas-liquid separation through the above three-stage structure to ensure a more efficient gas-liquid separation effect, thereby meeting the requirements of a large-capacity MW-level PEM hydrogen production system.

[0067] In addition, the prior art usually uses a tank for separation, and the start and stop of the front and rear control valves are used to ensure that the gas can stay in the tank for a sufficient time, thereby fully separating the gas and liquid. However, since the gas and liquid always coexist in the same tank, it is difficult to further improve the gas-liquid separation efficiency with this structure. Compared with the prior art, the present invention designs a three-stage separation tank, and the gas is always in a flowing state in each stage of the separation tank. When the gas and liquid flow to the output end of the tank, they will be separated immediately, so that they will not stay in the same tank for a long time, affecting the separation effect.

[0068] However, the present invention requires sufficient calculation, analysis and design of each component, especially to ensure that the gas can stay in each tank for a long enough time to meet the gas-liquid separation requirements when the gas flows.

[0069] The design method of the present invention comprises the following steps:

[0070] Step 1: Design the primary gas-liquid separation tank 2, specifically:

[0071] Step 1.1: Determine the diameter D of the primary gas-liquid separation tank 2 T .

[0072] The calculation basis of the primary gas-liquid separation tank 2 is the liquid flow rate and the residence time. Only by ensuring a sufficient residence time can a sufficient gas-liquid separation effect be achieved. In addition, the liquid in the primary gas-liquid separation tank 2 flows directly through the water flow holes at the bottom of the first cross-flow water diversion plate 201 and the second gap 205 on the lower side of the second cross-flow water diversion plate 202. The cross-flow water diversion plate is mainly used to cool the gas to condense the water, so it will not affect the following diameter and length calculations.

[0073] Diameter D of primary gas-liquid separation tank 2 T Determined according to the following formula:

[0074]

[0075] In the above formula (1):

[0076] C=L T / D T =2~4 (the recommended value is 2.5);

[0077] D T , L T are the diameter and length of the cylindrical part of the primary gas-liquid separation tank 2 respectively;

[0078] V L is the volume flow rate of the liquid;

[0079] t is the residence time;

[0080] A is the variable liquid area (in percentage), that is:

[0081] A=A TOT -(A a +A b ), all expressed as percentages, of which A TOT A is the total cross-sectional area of ​​the primary gas-liquid separation tank 2, a is the gas partial cross-sectional area, A b It is the cross-sectional area occupied by the liquid when the liquid level is at its lowest.

[0082] When calculating, first take A = m1%, and according to the actual working conditions, assume that the gas space area Aa is m2%, and the minimum liquid area Ab is m3%. When selecting the C value, the weldability (wall thickness) and transportability (diameter, length) of the container must be considered, and then calculate D according to the above formula (1): T , then according to D T and A a The height of the gas space is obtained as a, a=D T ×A a , the a value should not be less than the set value h. If it is less than h, a new diameter calculation should be performed using the value A<m1% until the a value is greater than h.

[0083] In this embodiment, A=80% is taken at the beginning of the calculation, and it is assumed that the gas space area Aa is 14%, the minimum liquid area Ab is 6%, and C is 2.5. First, calculate D according to the above formula (1): T , then according to D T and A a The height of the gas space is obtained as a, a=D T ×A a , the a value should not be less than the set value h=300mm. If it is less than 300mm, recalculate.

[0084] Step 1.2: According to the gas space A a The separation of the droplets is verified by a time ratio R (i.e., the ratio of the settling time required for the droplets to pass through the gas space height to the gas residence time), and then the distance L between the inlet and outlet pipes of the primary gas-liquid separation tank 2 is determined. N The design purpose of this step is to make the distance between the inlet and outlet of the primary gas-liquid separation tank 2 as large as possible, that is, L N ≈L T and L T =C·D T .in:

[0085]

[0086] In the above formula (2):

[0087] L N , D T , a are the distance between the inlet and outlet, the diameter of the primary gas-liquid separation tank 2 and the height of the gas space respectively;

[0088] V G is the gas flow rate;

[0089] ρ L , G are the density of liquid and the density of gas respectively;

[0090] A a is the cross-sectional area of ​​the gas portion;

[0091] R = τs / τT, where τs is the time required for a droplet with a diameter of d* to pass through the gas space height a; τT is the gas residence time.

[0092] Step 2: Design the secondary gas-liquid separation tank 4. Since the secondary gas-liquid separation tank 4 mainly realizes gas-liquid separation by gravity, the design basis of the secondary gas-liquid separation tank 4 is mainly the gas velocity u in the secondary gas-liquid separation tank 4. e , specifically:

[0093] Step 2.1: Approximately estimate the floating (settling) flow rate V of the material in the secondary gas-liquid separation tank 4 according to the following formula (3):t :

[0094]

[0095] In the above formula (3):

[0096] V t is the floating (settling) velocity, ρ L , G is the density of liquid and gas, K S is the coefficient, where the droplet diameter is d* = 200 μm, K S =0.0512; when the droplet diameter is d*=350μm, K S =0.0675.

[0097] The approximate estimation method is to first estimate based on the material flow process in the water distributor, that is, first set a gas flow rate u e As the gas velocity in the secondary gas-liquid separation tank 4, and the ue value should be less than V t However, the actual material flow state may be significantly different from the assumed value, which will cause inaccurate calculation results and require further calculation of Vt.

[0098] Step 2.2: Accurately calculate V t .

[0099] From the equilibrium condition of the floating droplet, the value Vt' is calculated according to the following formula (4):

[0100]

[0101] In the above formula (4), d* is the droplet diameter, g is the gravitational acceleration, and Cw is the drag coefficient. Here, we assume that R e Number, and look up the table to get C W , and then calculate a Vt', and then calculate R according to the following formula (5): e :

[0102]

[0103] In the above formula (5), μ G is the gas viscosity.

[0104] According to the calculated R e， Check the table to get the new C W , substitute into the above formula (4), and repeat the calculation until the Re numbers of the two iterations are equal, at which time Vt′=Vt.

[0105] Then take the gas flow rate u e ≤V t .

[0106] Step 2.3: Determine the diameter D of the secondary gas-liquid separation tank 4 according to the following formula (6):

[0107]

[0108] In the above formula (6), V Gmax is the maximum volume flow rate of gas.

[0109] Since the moisture content of the gas entering the secondary gas-liquid separation tank 4 is greatly reduced after the initial separation, the secondary gas-liquid separation tank 4 is adjusted according to the gas flow rate u e By designing a suitable length and diameter D, it can be ensured that the residence time of the gas in the tank meets the separation requirements.

[0110] Step 3: Determine the gas flow rate u of the separation screen 7 at the upper end of the third-stage separation tank 6 G .

[0111] The interception method of the separation screen 7 includes:

[0112] 1. Direct interception: When the airflow passes through the wire mesh, the droplets in the airflow whose diameter is larger than the mesh aperture are intercepted by the holes and separated out.

[0113] 2. Inertial impact: When the airflow flows through the wire mesh filter element, the gas phase changes direction. Due to inertia, the droplets cannot follow the gas phase streamline in time, so they hit the wire mesh and are captured.

[0114] 3. Diffusion interception: Small droplets (less than 1 μm in diameter) are freed from the gas streamlines by irregular Brownian motion, increasing the probability of hitting the fiber structure and being separated.

[0115] Gas flow rate u on the free cross-sectional area of ​​the wire mesh G The calculation is as follows:

[0116] u G =c·m·u0 (7);

[0117] In the above formula (7), c is the safety factor, which is 0.7 to 0.9, u0 is the critical velocity, and m is the correction factor, which can be obtained by looking up the table:

[0118]

[0119] In the above formula (8), g is the acceleration of gravity, ε is the mesh porosity, and ρ is L , G are the densities of liquid and gas respectively, a' is the specific surface area of ​​the wire mesh, μ L is the viscosity of the liquid, and the N coefficient is obtained by looking up the table. In this embodiment, 0.7 is taken for calculation.

[0120] The relationship between the separation efficiency and gas velocity of the three-stage gas-liquid separation tank 3 of the present invention is shown in the figure Figure 4 As shown in the figure, too high or too low gas velocity will affect the separation efficiency.

[0121] Some other domestic wire mesh separator parameters are shown in the following table. The present invention determines the appropriate gas flow rate u according to the parameters in the following table and the equipment design requirements. G .

[0122]

Claims

1. A water separator device for a MV-level PEM hydrogen production system, characterized in that: The invention comprises a primary gas-liquid separation tank (2), a secondary gas-liquid separation tank (4) and a tertiary gas-liquid separation tank (6), wherein the primary gas-liquid separation tank (2) and the secondary gas-liquid separation tank (4) are arranged in parallel, and the tertiary gas-liquid separation tank (6) is arranged vertically to the secondary gas-liquid separation tank (4); one end of the primary gas-liquid separation tank (2) is connected to an input pipe (1), a primary drain outlet (203) is arranged at the lower side of the other end, and a primary gas output pipeline (3) is arranged at the upper side; a first cross-flow water distribution plate (201) and a second cross-flow water distribution plate (202) are arranged alternately inside the primary gas-liquid separation tank (2) along the length direction, and a first gap (203) is arranged at the upper end of the first cross-flow water distribution plate (201). 04), a second gap (205) is provided at the lower end of the second cross-flow water separation plate (202), a water flow through hole is provided on the first cross-flow water separation plate (201), the first gas output pipeline (3) is connected to one end of the second gas-liquid separation tank (4), the other end of the second gas-liquid separation tank (4) is connected to the middle of the third gas-liquid separation tank (6) through the second gas output pipeline (5), a second drain port (401) is provided at the lower side of the middle of the second gas-liquid separation tank (4), a third gas output pipeline is provided at the upper end of the third gas-liquid separation tank (6), a third drain port (601) is provided at the lower end, and a separation screen (7) is provided inside the upper end of the third gas-liquid separation tank (6).

2. The water separator device for MV-level PEM hydrogen production system according to claim 1, characterized in that: The diameter D of the primary gas-liquid separation tank (2) T Determined according to the following formula: In the above formula (1), C = L T / D T , D T , L T are the diameter and length of the primary gas-liquid separation tank (2) respectively; V L is the volume flow rate of the liquid; t is the residence time; A is the variable liquid area, A = A TOT -(A a +A b ), Middle A TOT is the total cross-sectional area of ​​the primary gas-liquid separation tank (2), A a is the gas partial cross-sectional area, A b It is the cross-sectional area occupied by the liquid when the liquid level is at its lowest.

3. The water separator device for MV-level PEM hydrogen production system according to claim 2, characterized in that: The distance L between the inlet of the primary gas-liquid separation tank (2) connected to the input pipe (1) and the primary drain outlet (203) is N Determined according to the following formula: In the above formula (2), a is the height of the gas space; V G is the gas flow rate; ρ L , G are the liquid density and gas density respectively; R = τs / τT, where τs is the time required for a liquid droplet with a diameter of d* to pass through the gas space height a; τT is the gas residence time.

4. The water separator device for MV-level PEM hydrogen production system according to claim 1, characterized in that: The air velocity u on the separation screen (7) G Determined according to the following formula: u G =c·m·u0 (7); In the above formula (7), c is the safety factor, u0 is the critical flow rate, and m is the correction factor, which can be obtained by looking up the table: In the above formula (8), g is the acceleration of gravity, ε is the mesh porosity, and ρ is L , G are the densities of liquid and gas respectively, a' is the specific surface area of ​​the wire mesh, μL is the viscosity of the liquid, and the N coefficient is obtained by looking up the table.

5. A design method for a water separator device for a MV-level PEM hydrogen production system, characterized in that: The steps include: Step 1: Design the primary gas-liquid separation tank (2), specifically: Step 1.1: Determine the diameter D of the primary gas-liquid separation tank (2) T : In the above formula (1), C = L T / D T , D T , L T are the diameter and length of the primary gas-liquid separation tank (2) respectively; V L is the volume flow rate of the liquid; t is the residence time; A is the variable liquid area, that is: A = A TOT -(Aa+Ab), all expressed as percentages, where A TOT is the total cross-sectional area of ​​the primary gas-liquid separation tank (2), Aa is the cross-sectional area of ​​the gas portion, and Ab is the cross-sectional area occupied by the liquid when the liquid level is at its lowest; When calculating, first take A = m1%, and according to the actual working conditions, assume that the gas space area Aa is m2%, and the minimum liquid area Ab is m3%, and then calculate D according to the above formula (1) T , then according to D T and Aa to obtain the height of the gas space a, a=D T ×Aa, a value should not be less than the set value h. If it is less than h, a new diameter calculation should be performed using the value of A<m1% until a value is greater than h. Step 1.2: Determine the distance L between the inlet of the primary gas-liquid separation tank (2) connected to the input pipe (1) and the primary drain outlet (203) N : In the above formula (2), a is the height of the gas space; V G is the gas flow rate; ρ L , G are the liquid density and gas density respectively; R = τs / τT, where τs is the time required for a liquid droplet with a diameter of d* to pass through the gas space height a; τT is the gas residence time. Step 2: Structural design of the secondary gas-liquid separation tank (4), specifically: Step 2.1: Estimate the floating velocity V of the material in the secondary gas-liquid separation tank (4) approximately according to the following formula (3): t : In the above formula (3), V t is the floating (settling) velocity, ρ L , G is the density of liquid and gas, K S is the coefficient determined according to the liquid diameter d*; Step 2.2: Accurately calculate V t : First assume a Re number and calculate a V according to the following formula (4): t 'value: In the above formula (4), d* is the droplet diameter, g is the gravitational acceleration, and Cw is the drag coefficient; Then calculate R according to the following formula (5): e : In the above formula (5), μ G is the gas viscosity; According to the calculated R e， Check the table to get the new C W , substitute into the above formula (4), and repeat the calculation until the Re numbers of the two iterations are equal, at which point Vt′=Vt; Then take the gas flow rate u in the secondary gas-liquid separation tank (4) e ≤V t ; Step 2.3: Determine the diameter D of the secondary gas-liquid separation tank (4) according to the following formula (6): In the above formula (6), V Gmax is the maximum volume flow rate of gas; Step 3: Determine the gas flow rate u of the separation screen (7) at the upper end of the third-stage separation tank 6 G : u G =c·m·u0 (7); In the above formula (7), c is the safety factor, u0 is the critical flow rate, and m is the correction factor, which can be obtained by looking up the table: In the above formula (8), g is the acceleration of gravity, ε is the mesh porosity, and ρ is L , G are the densities of liquid and gas respectively, a' is the specific surface area of ​​the wire mesh, μ L is the liquid viscosity and the N coefficient is obtained by looking up the table.

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