Hydrogen combustion system linked to water electrolysis equipment

Abstract

A hydrogen combustion system according to one embodiment of the present invention may comprise: water electrolysis equipment for producing hydrogen and oxygen from water or steam; combustion equipment for burning the hydrogen and the oxygen; and a boiler in which water is heat-exchanged with exhaust gas discharged from the combustion equipment, thereby generating steam.

Description

Hydrogen combustion system linked with water electrolysis equipment

[0001] The present invention relates to a hydrogen combustion system linked with a high-temperature water electrolysis facility.

[0002] Technologies for producing hydrogen at low cost for carbon neutrality are being proposed, and among them, technologies for producing hydrogen via water electrolysis using electricity generated from sources such as solar power are gaining significant prominence.

[0003] Water electrolysis methods are broadly classified into high-temperature and low-temperature methods. Low-temperature electrolysis involves placing water into an electrolyte and separating it into hydrogen and oxygen through electrolysis, whereas high-temperature electrolysis is a technology that separates hydrogen and oxygen by introducing high-temperature steam into electrolysis cells called SOECs.

[0004] Meanwhile, conventional technology focuses solely on producing hydrogen through water electrolysis and pays little attention to the use of the oxygen produced in the process, so there is a need for technology to capture the additionally generated carbon dioxide.

[0005] Therefore, there is a need to develop technology that utilizes oxygen produced through water electrolysis without the need to capture carbon dioxide.

[0006] One embodiment of the present invention can provide a hydrogen combustion system linked with a water electrolysis facility that reduces fuel consumed in a combustion facility by utilizing oxygen obtained from water electrolysis.

[0007] One embodiment of the present invention can provide a hydrogen combustion system linked with a water electrolysis facility that emits almost no carbon dioxide.

[0008] One embodiment of the present invention can provide a hydrogen combustion system linked with a water electrolysis facility that does not require a separate carbon dioxide capture device.

[0009] The problems of the present invention are not limited to those described above. A person skilled in the art to which the present invention pertains will have no difficulty understanding additional problems of the present invention from the overall contents of this specification.

[0010] A hydrogen combustion system comprising an embodiment of the present invention may include: a water electrolysis facility for producing hydrogen and oxygen from water or steam; a combustion facility for burning the hydrogen and oxygen; and a boiler in which water exchanges heat with the exhaust gas discharged from the combustion facility to generate steam.

[0011] The above hydrogen combustion system may further include a steam flow path that supplies steam heat-exchanged in the boiler to the water electrolysis facility.

[0012] The hydrogen combustion system may further include a flue gas recirculation path that separates at least a portion of the flue gas as recirculated flue gas and mixes the recirculated flue gas with oxygen produced in the water electrolysis facility and supplies it to the combustion facility.

[0013] It may further include a flow control valve for controlling the flow rate of the recirculated exhaust gas flowing through the above exhaust gas recirculation path.

[0014] Hydrogen can be additionally supplied through the above combustion facility.

[0015] Oxygen can be additionally supplied through the above combustion equipment.

[0016] The flow rate of oxygen supplied to the above combustion facility may be greater than the flow rate of hydrogen.

[0017] One embodiment of the present invention can provide a hydrogen combustion system linked with a water electrolysis facility that reduces fuel consumed in a combustion facility by utilizing oxygen obtained from water electrolysis.

[0018] One embodiment of the present invention can provide a hydrogen combustion system linked with a water electrolysis facility that emits almost no carbon dioxide.

[0019] One embodiment of the present invention can provide a hydrogen combustion system linked with a water electrolysis facility that does not require a separate carbon dioxide capture device.

[0020] FIG. 1 is a diagram illustrating an exemplary hydrogen combustion system, which is an embodiment of the present invention.

[0021] Preferred embodiments of the present invention will be described below with reference to the attached drawings. However, embodiments of the present invention may be modified in various other forms, and the scope of the present invention is not limited to the embodiments described below.

[0022] In addition, embodiments of the present invention are provided to more fully explain the present invention to those with average knowledge in the relevant technical field.

[0023] In drawings, the shapes and sizes of elements may be exaggerated for clearer explanation.

[0024] In describing the embodiments of the present invention, if it is determined that a detailed description of known technology related to the present invention may unnecessarily obscure the essence of the present invention, such detailed description will be omitted. Furthermore, the terms described below are defined considering their functions in the present invention, and these may vary depending on the intentions or conventions of the user or operator. Therefore, such definitions should be based on the content throughout this specification. The terms used in the detailed description are merely for describing the embodiments of the present invention and should not be limited in any way. Unless explicitly stated otherwise, expressions in the singular form include the meaning of the plural form.

[0025] In this description, expressions such as “include” or “equipped” are intended to refer to certain characteristics, numbers, steps, actions, elements, parts or combinations thereof, and should not be interpreted to exclude the existence or possibility of one or more other characteristics, numbers, steps, actions, elements, parts or combinations thereof other than those described.

[0026] Unless otherwise specifically defined in the specification of the present invention, % units mean weight %.

[0027] In this specification, terms such as 'top', 'upper', 'upper surface', 'lower', 'lower surface', 'lower surface', and 'side surface' are based on the drawings and may actually vary depending on the direction in which the elements or components are arranged.

[0028] Additionally, throughout the specification, when it is said that one part is 'connected' to another part, this includes not only cases where they are 'directly connected,' but also cases where they are 'indirectly connected' with other elements in between.

[0029] The present invention will be described in detail below through each embodiment or example of the invention. It should be noted that each embodiment or example described in this specification is not limited to a single embodiment or example, but may also be combined with other embodiments or examples. Accordingly, the citation of claims in the patent claims is merely an example of an embodiment, and the technical concept of the present invention should not be interpreted as being limited only to a combination with the cited claims; rather, combinations with various claims are also included within the scope of the technical concept of the present invention.

[0030] One embodiment of the present invention can provide a hydrogen combustion system (10) linked with a water electrolysis facility that can reduce fuel consumed in a combustion facility by using oxygen obtained from water electrolysis, emits almost no carbon dioxide, and does not require a separate carbon dioxide capture device.

[0031] FIG. 1 is a diagram illustrating an exemplary hydrogen combustion system (10) which is an embodiment of the present invention.

[0032] Referring to FIG. 1, a hydrogen combustion system (10) which is an embodiment of the present invention may include a water electrolysis facility (100) that produces hydrogen and oxygen from water or steam; a combustion facility (200) that burns the hydrogen and oxygen; and a boiler (300) in which water is heat-exchanged with the exhaust gas discharged from the combustion facility to generate steam.

[0033] The above water electrolysis facility (100) may be a facility that produces hydrogen and oxygen by electrolyzing water using electricity produced from conventional electricity or sunlight, etc.

[0034] The above-mentioned water electrolysis facility (100) may be a low-temperature water electrolysis facility that produces hydrogen and oxygen by electrolyzing water containing an electrolyte, or a high-temperature water electrolysis facility that produces hydrogen and oxygen by putting steam at 700 to 800°C into a water electrolysis cell called SOEC (solid oxide electrolysis cells) and electrolyzing it.

[0035] Meanwhile, since the purity of hydrogen or oxygen may be somewhat low in low-temperature water electrolysis, the water electrolysis facility (100) may preferably be a high-temperature water electrolysis facility.

[0036] The above-described water electrolysis facility (100) can produce high-purity oxygen, i.e., pure oxygen, by electrolyzing water or steam (H2O). For example, the oxygen produced by the above-described water electrolysis facility (100) may have a purity of 90% or more, 95% or more, 99% or more, or 99.99% on a molar % basis.

[0037] The oxygen produced in the above-mentioned water electrolysis facility (100) can be introduced into the above-mentioned combustion facility (200) and used to burn fuel. In addition, the hydrogen produced in the above-mentioned water electrolysis facility (100) can be introduced into the above-mentioned combustion facility (200) and used to burn fuel.

[0038] It is generally known that using pure oxygen as an oxidizer can achieve a 50% reduction in fuel consumption.

[0039] Accordingly, a hydrogen combustion system (10) according to one embodiment of the present invention can increase energy efficiency by using oxygen obtained from a water electrolysis facility (100) as an oxidizing agent.

[0040] The above combustion facility (200) may be a combustion furnace. More specifically, the above combustion furnace may be a facility selected from the group consisting of a drying furnace for drying and removing moisture from raw materials such as coal, an incinerator for burning waste, a heating furnace for heating steel slabs, and a forging furnace for heating materials for forging, but is not limited thereto.

[0041] The combustion facility (200) can burn hydrogen and oxygen. By burning hydrogen and oxygen, the combustion facility (200) may emit almost no carbon dioxide and may not require an additional carbon dioxide capture device.

[0042] The hydrogen and oxygen introduced into the combustion facility (200) may each be hydrogen and oxygen produced from the water electrolysis facility (100).

[0043] The flow rate of oxygen supplied to the combustion facility (200) may be greater than the flow rate of hydrogen. The combustion facility (200) can ensure that there are no unburned components in hydrogen combustion by having a higher flow rate of oxygen than hydrogen.

[0044] If necessary, additional hydrogen can be supplied to the combustion facility (200). Additionally, if necessary, additional oxygen can be supplied to the combustion facility (200).

[0045] The above combustion facility (200) can discharge exhaust gas generated after combustion. The exhaust gas may be steam, may contain some oxygen and nitrogen, and may contain a very small amount of carbon dioxide depending on the air intake.

[0046] Meanwhile, the hydrogen combustion system (10) according to one embodiment of the present invention uses oxygen obtained from the water electrolysis facility (100) as an oxidizing agent, so the NOx content contained in the flue gas can be reduced. Accordingly, the flue gas discharged from the combustion facility (200) may contain some O2 that did not participate in the oxidation reaction.

[0047] A hydrogen combustion system (10) in one embodiment of the present invention may include a boiler (300). The boiler (300) may produce steam or electricity using steam recovered from exhaust gas discharged from the combustion facility (200).

[0048] The above boiler (300) can efficiently recover exhaust gas by generating steam through heat exchange between water and exhaust gas discharged from the combustion facility (200), and can prevent problems such as reduced durability of the system due to high heat, heat loss, and NOx generation by discharging high-temperature exhaust gas at a low temperature.

[0049] Referring to FIG. 1, a hydrogen combustion system (10) according to one embodiment of the present invention may further include a steam path (400).

[0050] The steam heat-exchanged in the boiler (300) can be supplied to the water electrolysis facility (100) through the steam path (400). Since the water electrolysis facility (100) requires a temperature of about 700°C or higher for the electrolysis of water, energy can be saved by minimizing additional heating by supplying water or steam heat-exchanged in the boiler (300).

[0051] The steam supplied to the steam path (400) may additionally be supplied with steam. Additionally, the boiler (300) may additionally include control equipment for controlling the pressure and temperature of the steam that has been heat-exchanged with the flue gas in the boiler (300).

[0052] Referring to FIG. 1, a hydrogen combustion system (10) according to one embodiment of the present invention may further include an exhaust gas recirculation path (500).

[0053] The above exhaust gas recirculation path (500) can separate a portion of the exhaust gas as recirculated exhaust gas and mix the recirculated exhaust gas with oxygen produced in the water electrolysis facility (100) and supply it to the combustion facility (200). The oxygen produced in the water electrolysis facility (100) may be at a high temperature of about 500°C or higher and has high oxidizing properties, which can reduce the durability of the combustion facility (200).

[0054] Accordingly, if the temperature of the oxygen introduced into the combustion facility (200) is lowered, not only can the oxidation of the combustion facility (200) be prevented, but the generation of NOx, which is an oxide of nitrogen introduced by the outside air during the combustion process, can also be suppressed, so that some of the gas in the exhaust gas recirculation path (500) can be mixed with the oxygen produced in the water electrolysis facility (100).

[0055] The above-mentioned recirculated flue gas may be a gas containing 80% or more, 90% or more, 95% or more, 99% or more, or 100% H2O on a molar % basis.

[0056] Accordingly, the exhaust gas recirculation path (500) can lower the concentration and temperature of oxygen introduced into the combustion facility (200) by mixing the recirculated exhaust gas with oxygen produced in the water electrolysis device. Accordingly, the flame temperature inside the combustion facility (200) that has become excessively high can be lowered to prevent deterioration of the combustion facility (200) and reduce the amount of NOx generated.

[0057] Additionally, the above-mentioned flue gas recirculation path (500) can recycle unburned hydrogen contained in part of the flue gas by reintroducing it into the combustion facility (200). If the final exhaust gas contains unburned hydrogen, additional oxygen can be supplied to the combustion facility (200) to remove the unburned hydrogen.

[0058] A hydrogen combustion system (10) according to one embodiment of the present invention may further include a flow control valve for controlling the flow rate of recirculated exhaust gas flowing through the exhaust gas recirculation path (500).

[0059] A hydrogen combustion system (10) according to one embodiment of the present invention can achieve a fuel saving effect by controlling the flow rate of recirculated exhaust gas through the flow control valve, while simultaneously preventing deterioration of the combustion equipment (200) and reducing the amount of NOx generated.

[0060] In addition, a hydrogen combustion system (10) according to one embodiment of the present invention may further include a temperature measuring device for measuring the temperature of the exhaust gas discharged from the boiler (300), i.e., the outlet temperature of the combustion facility.

[0061] A hydrogen combustion system (10) according to one embodiment of the present invention measures the outlet temperature of the boiler (300) and can adjust the flow rate of the exhaust gas flowing through the exhaust gas recirculation path (500) according to the measured outlet temperature of the combustion facility (200).

[0062] A hydrogen combustion system (10) according to one embodiment of the present invention can increase efficiency by about 10% compared to existing water electrolysis facilities by recovering waste heat obtained from high-temperature exhaust gas and supplying it to a water electrolysis facility (100).

[0063] In addition, a hydrogen combustion system (10) according to one embodiment of the present invention can maximize the overall system efficiency by using hydrogen fuel that can obtain a high temperature compared to hydrocarbon fuel and using oxygen as an oxidizer to improve heat transfer by additional high temperature and reduce sensible heat loss by reducing the amount of exhaust gas.

[0064] (Explanation of symbols)

[0065] 10: Hydrogen Combustion System

[0066] 100: Water electrolysis equipment

[0067] 200: Combustion equipment

[0068] 300: Boiler

[0069] 400: Steam Euro

[0070] 500: Flue gas recirculation path

Claims

1. Water electrolysis equipment for producing hydrogen and oxygen from water or steam; Combustion equipment for burning the above hydrogen and the above oxygen; and A hydrogen combustion system comprising a boiler in which water exchanges heat with exhaust gas discharged from the combustion facility to generate steam.

2. In Paragraph 1, The above hydrogen combustion system further comprises a steam path that supplies steam heat-exchanged in the boiler to the water electrolysis facility.

3. In Paragraph 1, The hydrogen combustion system further comprises a flue gas recirculation path that separates at least a portion of the flue gas as recirculated flue gas and mixes the recirculated flue gas with oxygen produced in the water electrolysis facility and supplies it to the combustion facility.

4. In Paragraph 3, A hydrogen combustion system further comprising a flow control valve for controlling the flow rate of recirculated exhaust gas flowing through the above exhaust gas recirculation path.

5. In Paragraph 1, A hydrogen combustion system that additionally supplies hydrogen to the above combustion facility.

6. In Paragraph 1, A hydrogen combustion system that additionally supplies oxygen to the above combustion facility.

7. In Paragraph 1, A hydrogen combustion system in which the flow rate of oxygen supplied to the above combustion facility is greater than or equal to the flow rate of hydrogen.

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