Hydrogen vent system

Abstract

The present invention relates to a hydrogen vent system for discharging hydrogen generated in a high-temperature water electrolysis stack to the outside, comprising a first piping section connected to the high-temperature water electrolysis stack and having a curved portion formed therein, a drain line connected to the first piping section for draining condensate, and a discharge section connected to the first piping section for discharging hydrogen into the air, wherein a surge tank is disposed in the first piping section to maintain pressure and move the condensate to the drain line.

Description

Technology Field

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

[0002] Hydrogen vent piping is designed so that the hydrogen concentration released into the atmosphere without combustion treatment during normal or emergency operation is below the explosion limit.

[0003] In the case of hydrogen discharge generated in a high-temperature water electrolysis stack, the temperature of the hydrogen passing through the downstream cooler of the high-temperature water electrolysis stack is 15 to 30°C, and since high-temperature gas is discharged, condensation occurs in the vent pipe.

[0004] At this stage, to minimize the condensate content within the vent piping, hydrogen is discharged in a dry state after passing through a heat exchanger and a cooler. Even so, it is difficult to perfectly control the condensate content of the vent gas due to factors such as the performance of the heat exchanger used for cooling and the cooling water temperature caused by seasonal temperature differences.

[0005] Since the inlet and outlet pipes of the high-temperature water electrolysis stack piping are connected, if pressure builds up in the vent pipe due to condensate, it can result in a direct degradation of the performance of the entire high-temperature water electrolysis stack.

[0006] Therefore, there is a need for a hydrogen vent system capable of treating the aforementioned condensate to maintain the high-temperature water electrolysis stack in normal operation. Prior art literature

[0007] Korean Registered Patent No. 10-1309952 (September 11, 2013) The problem to be solved

[0008] The present invention aims to solve the above problems and provides a hydrogen vent system capable of efficiently removing condensate. means of solving the problem

[0009] The present invention provides a hydrogen vent system formed as follows to achieve the above objectives.

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

[0011] In addition, it may include a second pipe section located between the first pipe section and the discharge section, and sloped downward toward the first pipe section.

[0012] In addition, the surge tanks mentioned above may be provided in multiple numbers.

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

[0014] In addition, the discharge section and the second piping section are installed outdoors, and the second piping section may be wrapped with insulation material.

[0015] In addition, a pump located upstream of the surge tank and a valve located upstream of the pump may be disposed in the first piping section.

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

[0017] In addition, the first piping section, the second piping section, and the discharge section may be connected by welding.

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

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

[0020] Figure 1 shows a time-voltage graph evaluating a high-temperature water electrolysis stack over a long period. FIG. 2 is a schematic diagram briefly illustrating a hydrogen vent system according to an embodiment of the present invention. FIG. 3 is a graph showing the effect of the hydrogen vent system according to the present invention, where A is the pressure of the hydrogen pipe according to one embodiment of the present invention and B is the pressure of the conventional hydrogen pipe. Specific details for implementing the invention

[0021] Specific embodiments of the present invention will be described below with reference to the attached drawings. However, the concept of the present invention is not limited to the presented embodiments, and those skilled in the art who understand the concept of the present invention may easily propose other inventions that are inferior or other embodiments included within the scope of the concept of the present invention by adding, changing, or deleting other components within the same scope of the concept, and such are also to be considered to be included within the scope of the concept of the present invention.

[0023] Figure 1 shows a time-voltage graph of a high-temperature water electrolysis stack evaluated over a long period of time.

[0024] A vent stack refers to a facility installed to safely release gases or vapors released during normal or emergency operation into the atmosphere without incineration.

[0025] Solid Oxide Electrolysis Cell (SOEC) technology, which produces hydrogen and oxygen by directly electrolyzing high-temperature steam, is more efficient than the electrolysis of room-temperature or low-temperature water. This is because the energy required for electrolysis is lower when using high-temperature steam compared to room-temperature water; in fact, the higher the temperature, the less energy is consumed. Therefore, if an inexpensive heat source capable of raising the temperature of room-temperature water can be secured, SOEC technology can theoretically become the most efficient hydrogen production technology.

[0026] Preventing pressure imbalance between the inlet and outlet of a high-temperature water electrolysis stack can be an important factor for stable long-term operation of the stack.

[0027] If hydrogen resulting from high-temperature water electrolysis is not fully utilized and is released, abnormal behavior occurs in the high-temperature water electrolysis stack (hereinafter referred to as the stack) due to moisture condensation in the hydrogen vent piping (hereinafter referred to as the vent piping) included in the hydrogen vent stack used; if this phenomenon accumulates, stable long-term operation becomes impossible. Ultimately, this leads to problems where the performance and efficiency of the stack deteriorate.

[0028] Referring to Fig. 1, 650–750℃, 0.7–1.4A / cm 2 In the operating environment, excellent performance is maintained with a degradation rate of less than 0.4% / h up to 800 hours, but beyond that, due to pressure rise caused by pipe freezing, the degradation rate deteriorates by more than tenfold to 4.93%. This deterioration in the degradation rate can be determined by the behavior of the pressure sensor, and it can be seen that the balance between the inlet and outlet pressures of the stack can have a significant impact on extending the lifespan of the stack. Therefore, the present invention aims to minimize pressure fluctuations by treating the condensate in the vent pipe to balance the inlet and outlet pressures of the stack.

[0030] FIG. 2 is a simplified diagram illustrating 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 relates to a piping system for discharging hydrogen generated in a high-temperature water electrolysis stack to the outside, and comprises a first piping section (L1), a drain line (DL), and a discharge section (L3).

[0032] In the drawing, the area inside the dashed line is the indoor (R) space, and the exterior can represent the outdoor space.

[0033] The first piping section (L1) is connected to the stack and a curved section (E) is formed.

[0034] The vent piping through which hydrogen is discharged is connected to the high-temperature water electrolysis stack, and by including a curved section at the connection point, the stack can be prevented from being directly affected in the event of problems such as flames in the hydrogen gas.

[0035] The first piping section (L1) is a part located indoors and may not be equipped with insulation material for thermal insulation.

[0036] Additionally, the first piping section (L1) may be connected to a hydrogen storage section where hydrogen generated in the stack is stored, or to a branch pipe of a transfer pipe that moves hydrogen from the stack to where it is used. Since there are difficulties in storing unused hydrogen, it may be a pipe included in a hydrogen vent system for releasing it into the air.

[0037] In the case of multiple hydrogen vent pipes, the distance between the first pipe sections (L1) is at least 5m or more, so that they can be arranged so that even if there is a fire or explosion in one pipe, there is less mutual influence.

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

[0039] Surge tanks (ST1, ST2) are placed in the first piping section (L1) to maintain the pressure of the first piping section (L1) within the first piping section (L1) and to remove condensate formed in the first piping section (L1).

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

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

[0042] Multiple surge tanks (ST1, ST2) are arranged in the first piping section (L1), so that condensate can be removed at sufficient points regardless of the length of the first piping section (L1). In particular, surge tanks (ST1, ST2) located close to the second piping section (L2), which will be described below, can remove condensate formed in the second piping section (L2) together.

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

[0044] A pump (P) may be located upstream of the surge tanks (ST1, ST2). In case condensate forms before the bend (E) and it is difficult for it to move naturally to the surge tanks (ST1, ST2), pressure can be applied using electricity to move it to the surge tanks (ST1, ST2).

[0045] In addition, a valve (V1) is included at the front end of the pump (P) so that if a problem occurs during hydrogen discharge, it can be opened and closed to prevent hydrogen from flowing through the first piping section (L1).

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

[0047] The drain line (DL) is connected through surge tanks (ST1, ST2), and thus the surge tanks (ST1, ST2) may be configured to connect the drain line (DL) from the first piping section (L1) so as to move condensate to the drain line (DL).

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

[0049] When the first piping section (L1) is connected to the drain line (DL) without surge tanks (ST1, ST2), there is a problem in that it cannot cope with sudden pressure changes caused by condensate, so surge tanks (ST1, ST2) can be provided and configured to move to the drain line (DL).

[0050] A differential pressure valve (DV1, DV2) may be formed between the drain line (DL) and the surge tank (ST1, ST2), and the differential pressure valve (DV1, DV2) may be formed to open toward the drain line (DL) when the pressure inside the surge tank (ST1, ST2) increases, thereby allowing movement in only one direction.

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

[0052] An example of a transparent material may be a tube formed of polytetrafluoroethylene (PTFE), and it may be more advantageous to use a heat-resistant material such as a non-flammable fluoropolymer.

[0053] By making the drain line (DL) transparent, the discharge of condensate can be observed visually, making maintenance easier. Since problems such as freezing can occur when the drain line (DL) is connected externally, this makes it easier to prevent such issues.

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

[0055] Since there is always a possibility of fire when hydrogen is discharged, a fire may occur at the discharge section (L3). In addition, since it is an unavoidable assumption that hydrogen may explode in the air, the discharge section (L3) may be configured to discharge hydrogen into the air rather than to the ground.

[0056] Unlike the first piping section (L1), the discharge section (L3) is provided outdoors. Condensation may occur within the discharge section (L3), and since it may be difficult to discharge hydrogen if the condensation freezes, it may be wrapped with an insulating material.

[0057] In addition to thermal insulation, it is desirable for the insulation material to have non-flammability and durability, and since a loud noise may be generated during a hydrogen explosion, it may be advantageous for it to have sound-absorbing properties.

[0058] When condensation occurs in the discharge section (L3), the discharge section (L3) is a chimney built with a height that allows hydrogen to be discharged into the air, so 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) located between a first pipe section (L1) and a discharge section (L3).

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

[0061] The second piping section (L2) may be located outdoors. Therefore, similar to the discharge section (L3), the second piping section (L2) can be wrapped with insulation to prevent condensation from freezing inside and blocking the pipe.

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

[0064] According to one embodiment of the present invention, the first piping section (L1), the second piping section (L2), or the discharge section (L3) may be formed of a material including stainless steel.

[0065] For example, it may be 300 series austenitic stainless steel, and in particular, 304 stainless steel may be suitable for handling hydrogen at room temperature.

[0066] Since the piping handles hydrogen, pipes with low melting points or properties susceptible to easy corrosion by hydrogen may cause issues with durability and stability; therefore, the piping may be made of stainless steel.

[0067] According to one embodiment of the present invention, the first piping section (L1), the second piping section (L2), and the discharge section (L3) can be connected by welding.

[0068] Since hydrogen flows through the first piping section (L1), the second piping section (L2), and the discharge section (L3), a connection section (C1, C2) connected by welding can be formed. Since hydrogen leakage in the middle can cause safety issues, the connection can be made by welding to prevent hydrogen leakage. If welding is difficult, the connection can be made in a way that allows for a tight connection.

[0069] According to one embodiment of the present invention, if the pipe located in the part connecting the connection section (C1) connecting the first pipe section (L1) and the second pipe section (L2) and the 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).

[0070] In order for the condensate formed in the second piping section (L2) and the discharge section (L3) in the surge tank (ST1, ST2) connected to the sub-pipe (SL) to be smoothly discharged, it can be formed so as to be directed toward the surge tank (ST1, ST2) or at least parallel to it so that the condensate does not flow backward.

[0071] The first piping section (L1) may be divided into multiple sub-pipes, for example, a first sub-pipe (SL1) between the stack and the pump (P), a second sub-pipe (SL2) which is the piping between the pump (P) and the first surge tank (ST1), a third sub-pipe (SL3) which is the piping between the first surge tank (ST1) and the second surge tank (ST2), and a sub-pipe (SL) which is the piping between the second surge tank (ST2) and the connection section (C1). A gradient may also be formed in the sub-pipes so that the condensate formed in the first piping section (L1) can be moved to the first surge tank (ST1) or the second surge tank (ST2).

[0072] The above description is exemplary and is not limited to the numbers, shapes, etc. mentioned above, but includes all scopes that a person skilled in the art can easily modify.

[0074] Figure 3 is a graph illustrating the effect of the hydrogen vent system according to the present invention.

[0075] A is illustrated as a case where a hydrogen vent system according to one embodiment of the present invention is formed, and B is illustrated as a case where a hydrogen vent system is formed to allow hydrogen to be discharged directly without surge tanks (ST1, ST2), etc., as in the conventional method, thereby indicating the pressure within the system.

[0076] In case A, the pressure is formed at approximately 1.0 bar, which is similar to atmospheric pressure, and it can be seen that there is no pressure difference between the inlet and outlet pipes of the water 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 degradation rate and has an adverse effect on long-term operation.

[0077] In this way, according to one embodiment of the present invention, condensate generated in the hydrogen vent pipe can be effectively treated to maintain normal operation of the high-temperature water electrolysis stack, thereby extending its lifespan and providing the effect of maintaining the performance of the high-temperature water electrolysis.

[0079] Although the present invention has been described above with reference to embodiments, the present invention is not limited to the embodiments described above, and it is understood that it can be modified and implemented by those skilled in the art without changing the technical concept of the present invention as claimed in the claims. Explanation of the symbols

[0080] L1: 1st Piping Section L2: 2nd Piping Section L3: Discharge section DL: Drain line ST1, ST2: Surge Tank

Claims

Claim 1 A hydrogen vent system for discharging hydrogen generated in a high-temperature water electrolysis stack to the outside, comprising: a first pipe section connected to the high-temperature water electrolysis stack and having a curved portion formed therein; a drain line connected to the first pipe section and draining condensate; and a discharge section connected to the first pipe section and discharging hydrogen into the air; wherein a surge tank is disposed in the first pipe section to maintain pressure and move the condensate to the drain line. Claim 2 A hydrogen vent system according to claim 1, comprising a second pipe section positioned between the first pipe section and the discharge section and sloped downward toward the first pipe section. Claim 3 In claim 1, the surge tank is a hydrogen vent system equipped with a plurality of surge tanks. Claim 4 A hydrogen vent system according to claim 1, wherein at least a portion of the drain line is formed as a transparent tube. Claim 5 A hydrogen vent system according to paragraph 2, wherein the discharge section and the second piping section are installed outdoors, and the second piping section is wrapped with an insulating material. Claim 6 In paragraph 3, a hydrogen vent system is provided in which a pump located upstream of the surge tank and a valve located upstream of the pump are disposed in the first piping section. Claim 7 A hydrogen vent system according to paragraph 2, wherein at least one of the first piping section, the second piping section, and the discharge section is formed of a material including stainless steel. Claim 8 In paragraph 2, the hydrogen vent system in which the first piping section, the second piping section, and the discharge section are connected by welding. Claim 9 In paragraph 2, the sub-pipe, which is included in the first piping section and is a connecting section connecting the second piping section and the first piping section and a pipe connecting the surge tank, is a hydrogen vent system formed with a downward slope or without a slope toward the surge tank.

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