Hydrogen vent system

Abstract

The present invention provides a hydrogen vent system for discharging hydrogen generated in a high-temperature water electrolysis stack to the outside, comprising: a first pipe unit connected to the high-temperature water electrolysis stack and having a curved portion; a drain line which is connected to the first pipe unit and through which condensed water is drained; and a discharge unit which is connected to the first pipe unit and which releases hydrogen upward into the air, wherein a surge tank that maintains pressure and moves the condensed water to the drain line is disposed in the first pipe unit.

Description

Hydrogen vent system

[0001] The present invention relates to a hydrogen vent system for a high-temperature water electrolysis stack.

[0002] The hydrogen vent pipe is designed so that the hydrogen concentration is below the explosive limit when the hydrogen emitted during normal or emergency operation is not combusted and is released into the atmosphere.

[0003] In the case of hydrogen discharge generated from a high-temperature water electrolysis stack, the temperature of the hydrogen that has passed through the rear cooler of the high-temperature water electrolysis stack is 15 to 30°C, and because high-temperature gas is discharged, condensation occurs in the vent pipe.

[0004] At this time, to minimize the condensate content within the vent pipe, hydrogen is discharged in a dry state through a heat exchanger and cooler. Even so, perfectly controlling the condensate content of the vent gas remains challenging due to factors such as the performance of the heat exchanger used for cooling and the temperature of the cooling water resulting from seasonal temperature differences.

[0005] Since the high-temperature electrolysis stack piping is connected to the inlet and outlet pipes, if the vent pipe becomes pressurized due to condensate, this can directly lead to a decrease in the performance of the entire high-temperature electrolysis stack.

[0006] Therefore, there is a need for a hydrogen vent system that can treat the above condensate and maintain the high-temperature water electrolysis stack in normal operation.

[0007] (Patent Document 1) Korean Patent No. 10-1309952 (September 11, 2013)

[0008] The present invention is intended to solve the above problems and to provide a hydrogen vent system capable of efficiently removing condensate.

[0009] In order to achieve the above-mentioned purpose, the present invention provides a hydrogen vent system formed as follows.

[0010] A hydrogen vent system according to one embodiment of the present invention is a hydrogen vent system in which hydrogen generated in a high-temperature water electrolysis stack is discharged to the outside, and includes a first pipe part connected to the high-temperature water electrolysis stack and having a curved portion formed therein, a drain line connected to the first pipe part and draining condensate, and a discharge part connected to the first pipe part and discharging hydrogen into the air, and a surge tank for maintaining pressure and moving the condensate to the drain line is arranged in the first pipe part.

[0011] Additionally, it may include a second pipe section positioned between the first pipe section and the discharge section and having a downward slope toward the first pipe section.

[0012] Additionally, a plurality of surge tanks may be provided.

[0013] Additionally, at least a portion of the drain line may be formed of a transparent tube.

[0014] Additionally, the discharge portion and the second pipe portion may be installed outdoors, and the second pipe portion may be wrapped with insulating material.

[0015] Additionally, in the first pipe section, a pump positioned at the front end of the surge tank and a valve positioned at the front end of the pump may be arranged.

[0016] Additionally, at least one of the first pipe section, the second pipe section, and the discharge section may be formed of a material including stainless steel.

[0017] Additionally, the first pipe section, the second pipe section, and the discharge section can be connected by welding.

[0018] In addition, the sub-pipe, which is included in the first pipe section and is a pipe connecting the second pipe section and the first pipe section and the surge tank, may be formed with a downward slope or without a slope toward the surge tank.

[0019] The present invention effectively treats condensate generated in a hydrogen vent pipe through the above structure, thereby maintaining normal operation of a high-temperature water electrolysis stack, thereby extending its lifespan and maintaining the performance of high-temperature water electrolysis.

[0020] Figure 1 shows a time-voltage graph showing a long-term evaluation of a high-temperature electrolysis stack.

[0021] FIG. 2 is a schematic diagram briefly illustrating a hydrogen vent system according to one embodiment of the present invention.

[0022] FIG. 3 is a graph for showing the effect of a hydrogen vent system according to the present invention, where A represents the pressure of a hydrogen pipe according to one embodiment of the present invention, and B represents the pressure of a conventional hydrogen pipe.

[0023] Hereinafter, specific embodiments of the present invention will be described with reference to the attached drawings. However, the spirit of the present invention is not limited to the presented embodiments, and those skilled in the art who understand the spirit of the present invention will be able to easily propose other regressive inventions or other embodiments included within the scope of the spirit of the present invention by adding, modifying, or deleting other components within the scope of the same spirit. However, this will also be considered to be included within the scope of the spirit of the present invention.

[0024] Figure 1 shows a time-voltage graph showing a long-term evaluation of a high-temperature electrolysis stack.

[0025] A vent stack is a facility installed to safely release gases or vapors released during normal or emergency operation into the atmosphere without incineration.

[0026] High-temperature water electrolysis (Solid Oxide Electrolysis Cell, SOEC) technology directly electrolyzes high-temperature steam to produce hydrogen and oxygen, offering higher efficiency than the electrolysis of room-temperature or low-temperature water. This is because high-temperature steam consumes less electrolysis energy than room-temperature water, and the higher the temperature, the less electrolysis energy is consumed. Therefore, if a low-cost heat source can be secured to raise the temperature of room-temperature water, high-temperature water electrolysis could theoretically become the most efficient hydrogen production technology.

[0027] For stable long-term operation of a high-temperature water electrolysis stack, preventing pressure imbalance at the inlet and outlet of the high-temperature water electrolysis stack may be an important factor.

[0028] If the hydrogen resulting from high-temperature electrolysis is not fully utilized and is released, abnormal behavior may occur in the high-temperature electrolysis stack (hereinafter referred to as the "stack") due to condensation of moisture in the hydrogen vent pipe (hereinafter referred to as the "vent pipe") included in the hydrogen vent stack. If this phenomenon accumulates, stable long-term operation becomes impossible. Ultimately, this leads to problems such as deterioration in the stack's performance and efficiency.

[0029] Referring to Figure 1, 650~750℃, 0.7~1.4A / cm 2 In the driving environment, it has excellent performance with a deterioration rate of less than 0.4% / h for up to 800 hours, but beyond that, the deterioration rate worsens by more than ten times to 4.93% due to pressure increase caused by pipe freezing. This deterioration in the deterioration rate can be judged from the behavior of the pressure sensor, and it can be seen that the pressure balance at the inlet and outlet of the stack can have a great influence on the extension of the stack's lifespan. Therefore, the purpose of the present invention is to minimize pressure changes by treating the condensate in the vent pipe in order to balance the inlet and outlet pressures of the stack.

[0030] FIG. 2 is a schematic drawing of a hydrogen vent system according to an embodiment of the present invention.

[0031] A hydrogen vent system according to one embodiment of the present invention is a piping system for discharging hydrogen generated in a high-temperature water electrolysis stack to the outside, and includes a first piping section (L1), a drain line (DL), and a discharge section (L3).

[0032] In the drawing, the space within the broken line is indoor (R), and the outside can indicate the outdoors.

[0033] The first pipe section (L1) is connected to the stack and a bent portion (E) is formed.

[0034] The vent pipe through which hydrogen is discharged is connected to the high-temperature electrolysis stack, and includes a curved section in the section connected to the stack to prevent the stack from being directly affected as much as possible in the event of a problem such as a flame in the hydrogen gas.

[0035] The first pipe section (L1) is located indoors and may not be equipped with insulation material for heat preservation.

[0036] Additionally, the first pipe section (L1) may be connected to a hydrogen storage unit where hydrogen generated from the stack is stored, or may be connected to a branch pipe of a transport pipe that transports hydrogen from the stack to a location where it is used. Since it is difficult to store unused hydrogen, the pipe may be included in a hydrogen vent system for releasing it into the air.

[0037] In the case where there are multiple hydrogen vent pipes, the distance between the first pipe sections (L1) should be at least 5 m so that even if a fire or explosion occurs in one pipe, they can be arranged so that they have little influence on each other.

[0038] According to one embodiment of the present invention, a surge tank (ST1, ST2) may be positioned in the first pipe section (L1).

[0039] The surge tank (ST1, ST2) is placed in the first pipe section (L1), maintains the pressure of the first pipe section (L1) within the first pipe section (L1), and removes condensate formed in the first pipe section (L1).

[0040] The surge tank (ST1, ST2) is formed as a tank having a free water surface to remove condensate, and when a sudden pressure change occurs in the first pipe section (L1), water is discharged from the surge tank (ST1, ST2) to regulate the pressure change.

[0041] For example, multiple surge tanks (ST1, ST2) may be provided.

[0042] By arranging multiple surge tanks (ST1, ST2) in the first pipe section (L1), it can be formed so that condensate can be removed from sufficient points regardless of the length of the first pipe section (L1). In particular, the surge tanks (ST1, ST2) positioned close to the second pipe section (L2) to be described below can also remove condensate formed in the second pipe section (L2).

[0043] According to one embodiment of the present invention, a pump (P) and a valve (V1) may be further positioned in the first pipe section (L1).

[0044] A pump (P) may be positioned in front of the surge tank (ST1, ST2). In case condensate is formed before the bend (E) and cannot naturally move to the surge tank (ST1, ST2), pressure may be applied by electric power to move it to the surge tank (ST1, ST2).

[0045] In addition, a valve (V1) is included at the front end of the pump (P) so that in case of a problem with hydrogen discharge, it can be opened and closed to prevent hydrogen from flowing into the first pipe section (L1).

[0046] The drain line (DL) may be a pipe connected to the first pipe section (L1) and draining condensate formed within the hydrogen vent system.

[0047] The drain line (DL) is connected through the surge tank (ST1, ST2), and thus the surge tank (ST1, ST2) may be configured to connect the drain line (DL) to the first pipe section (L1) so that the condensate can be moved to the drain line (DL).

[0048] If multiple surge tanks (ST1, ST2) are provided, a drain line (DL1, DL2) may be formed from each surge tank (ST1, ST2).

[0049] In the case of connecting the first pipe section (L1) to the drain line (DL) without a surge tank (ST1, ST2), there is a problem of not being able to prepare for rapid pressure changes due to condensate, so a surge tank (ST1, ST2) can be provided to form the pipe so that it moves to the drain line (DL).

[0050] A differential pressure valve (DV1, DV2) can be formed between the drain line (DL) and the surge tank (ST1, ST2), and when the pressure inside the surge tank (ST1, ST2) increases at the differential pressure valve (DV1, DV2), the differential pressure valve (DV1, DV2) can be formed to open toward the drain line (DL), so that it can be formed to move in only one direction.

[0051] For example, at least a portion of the drain line (DL) may be formed of a transparent tube.

[0052] An example of a transparent material would be a tube made of polytetrafluoroethylene (PTFE), or a heat-resistant material such as a non-flammable fluorocarbon resin would be more advantageous.

[0053] The drain line (DL) is transparent, allowing for visual observation of condensate discharge and facilitating maintenance. This helps prevent problems like freezing when the drain line (DL) is connected externally.

[0054] The discharge section (L3) is a chimney connected to the first pipe section (L1) and discharges hydrogen into the air.

[0055] Because the possibility of fire always exists when hydrogen is discharged, a fire may occur at the discharge point (L3). Furthermore, since hydrogen explosion in air is an unavoidable assumption, the discharge point (L3) may be designed to discharge hydrogen into the air, rather than to the ground.

[0056] Unlike the first piping section (L1), the discharge section (L3) is located outdoors. Condensation may also occur within the discharge section (L3), and if the condensate freezes, hydrogen discharge may become difficult, so it may be wrapped with insulating material.

[0057] In addition to its insulating function, it is desirable for the insulation material to be non-flammable and durable. Since a hydrogen explosion can generate a loud noise, it may be advantageous for it to have sound absorption properties.

[0058] When condensation occurs inside the discharge section (L3), the discharge section (L3) is a stacked chimney with a height that allows hydrogen to be discharged upwards, so that it is formed to flow naturally from the inside to the first pipe section (L1).

[0059] A hydrogen vent system according to one embodiment of the present invention further includes a second pipe section (L2) positioned between the first pipe section (L1) and the discharge section (L3).

[0060] The second pipe section (L2) is positioned between the first pipe section (L1) and the discharge section (L3), and is formed to have a downward slope toward the first pipe section (L1). The second pipe section (L2) may be formed outdoors, and forms a downward slope so that condensate generated in the second pipe section (L2) and the discharge section (L3) can easily flow to the surge tank (ST1, ST2) arranged in the first pipe section (L1) and the drain line (DL) connected thereto.

[0061] The second pipe section (L2) may be located outdoors. Therefore, similar to the discharge section (L3), the second pipe section (L2) may be wrapped with insulating material to prevent condensate from freezing inside and clogging the pipe.

[0062] Through this, the pressure of the stack due to condensation can be prevented from increasing, and the discharge portion (L3) can be formed by extending to a point where hydrogen can be released.

[0063] According to one embodiment of the present invention, the first pipe section (L1), the second pipe section (L2), or the discharge section (L3) may be formed of a material including stainless steel.

[0064] For example, it could be a 300 series austenitic stainless steel, and in particular 304 stainless steel, which may be suitable for handling hydrogen at room temperature.

[0065] Since it is a pipe that handles hydrogen, pipes with a low melting point or that are easily corroded by hydrogen may have durability and stability issues, so the pipes may be made of stainless steel.

[0066] According to one embodiment of the present invention, the first pipe section (L1), the second pipe section (L2), and the discharge section (L3) can be connected by welding.

[0067] Since hydrogen flows through the first pipe section (L1), the second pipe section (L2), and the discharge section (L3), connections (C1, C2) can be formed by welding. Since hydrogen leakage from the middle can cause safety issues, welding can be used to prevent hydrogen leakage. If welding is difficult, a method that allows for a close connection can be used.

[0068] According to one embodiment of the present invention, if a pipe located at a portion connecting a connection portion (C1) connecting a first pipe portion (L1) and a second pipe portion (L2) and a surge tank (ST1, ST2) is defined as a sub-pipe (SL), the sub-pipe (SL) may be formed with a downward slope or without a slope toward the surge tank (ST1, ST2).

[0069] In order to smoothly discharge the condensate formed in the second pipe section (L2) and the discharge section (L3) in the surge tank (ST1, ST2) connected to the sub-pipe (SL), the surge tank (ST1, ST2) may be formed facing or at least parallel to the surge tank (ST1, ST2) so that the condensate does not flow in the opposite direction.

[0070] The first pipe section (L1) may be divided into a plurality of sub-pipes, for example, a first sub-pipe (SL1) between the stack and the pump (P), a second sub-pipe (SL2) which is a pipe between the pump (P) and the first surge tank (ST1), a third sub-pipe (SL3) which is a pipe between the first surge tank (ST1) and the second surge tank (ST2), a sub-pipe (SL) between the second surge tank (ST2) and the connection (C1), etc. A gradient may also be formed in the sub-pipes so that the condensate formed in the first pipe section (L1) can move to the first surge tank (ST1) or the second surge tank (ST2).

[0071] The above description is exemplary and includes all ranges that can be easily changed by a person skilled in the art, including numbers, shapes, etc. mentioned above.

[0072] Figure 3 is a graph showing the effect of the hydrogen vent system according to the present invention.

[0073] A case where a hydrogen vent system according to an embodiment of the present invention is formed is illustrated as A, and a case where a hydrogen vent system is formed so that hydrogen is discharged directly without a surge tank (ST1, ST2) as in the past is illustrated as B, indicating the pressure within the system.

[0074] In case A, the pressure is formed at approximately 1.0 bar, which is almost similar to atmospheric pressure, and it can be seen that there is no pressure difference between the inlet and outlet pipes of the electrolysis stack. However, in case B, the pressure is close to 1.3 bar, so a higher pressure is applied to the outlet side, which increases the deterioration rate and has a negative impact on long-term operation.

[0075] In this way, according to one embodiment of the present invention, it is possible to effectively treat condensate generated in a hydrogen vent pipe to maintain normal operation of a high-temperature water electrolysis stack, thereby extending its lifespan and maintaining the performance of high-temperature water electrolysis.

[0076] Although the present invention has been described above with reference to examples, the present invention is not limited to the above-described examples, and it goes without saying that modifications can be made and implemented by those skilled in the art without changing the technical idea of ​​the present invention as claimed in the claims.

Claims

1. In the hydrogen vent system where hydrogen generated in the high temperature water electrolysis stack is discharged to the outside, A first piping section connected to a high temperature water electrolysis stack and having a curved section formed therein; A drain line connected to the first pipe section and draining condensate; and A discharge unit connected to the first pipe unit and discharging hydrogen into the air; A hydrogen vent system in which a surge tank is arranged in the first pipe section to maintain pressure and move the condensate to the drain line.

2. In paragraph 1, A hydrogen vent system including a second pipe section positioned between the first pipe section and the discharge section and sloping downward toward the first pipe section.

3. In paragraph 1, The above surge tank is a hydrogen vent system equipped with multiple units.

4. In paragraph 1, A hydrogen vent system wherein at least a portion of the above drain line is formed of a transparent tube.

5. In paragraph 2, A hydrogen vent system in which the above discharge portion and the second pipe portion are installed outdoors, and the second pipe portion is wrapped with insulating material.

6. In paragraph 3, A hydrogen vent system in which a pump located at the front end of the surge tank and a valve located at the front end of the pump are arranged in the first pipe section.

7. In paragraph 2, A hydrogen vent system, wherein at least one of the first pipe section, the second pipe section, and the discharge section is formed of a material including stainless steel.

8. In paragraph 2, A hydrogen vent system in which the first pipe section, the second pipe section, and the discharge section are connected by welding.

9. In paragraph 2, A hydrogen vent system in which a sub-pipe, which is included in the first pipe section and connects the second pipe section and the first pipe section and the surge tank, is formed with a downward slope or no slope toward the surge tank.

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