Hydrogen reforming system

Abstract

Hydrogen reforming system, comprehensive: a reformer (100) which produces a first mixed gas by means of a reforming reaction between fuel gas and water; a transformer (200) which is fed with the first mixed gas and produces a second mixed gas from which carbon monoxide is removed by means of a water-gas shift reaction; a unit (300) for pressure swing adsorption (PSA) that cleans and separates hydrogen from the second mixed gas generated in the transformer and discharges hydrogen-free exhaust gas; a heat exchanger (400) provided between the reformer and the transformer and between the transformer and the pressure swing adsorption (PSA) unit to control the temperatures of the first mixed gas and the second mixed gas by means of heat exchange with water; a water feeder (500) that communicates with the heat exchanger and supplies water to the heat exchanger and supplies the water exiting the heat exchanger to the reformer; and a control valve (600) which is provided on a line through which water is discharged from the water supply and which adjusts a flow rate of water supplied to the heat exchanger in order to control the first mixed gas and the second mixed gas separately, wherein the heat exchanger (400) comprises a first heat exchanger (410) provided between the reformer (100) and the transformer (200) in which heat exchange takes place between the first mixed gas and water; and a second heat exchanger (420) and a third heat exchanger (430) provided between the transformer (200) and the PSA unit in which heat exchange takes place between the second mixed gas and water, and wherein the water supply (500) comprises a first supply line (510) connected to and supplying water to the first heat exchanger (410), a second supply line (520) connected to and supplying water to the second heat exchanger (420), and a third supply line (530) connected to and supplying water to the third heat exchanger (430), thereby allowing the temperatures of the first mixed gas and the second mixed gas to be controlled separately, wherein the control valve (600) comprises a first control valve (610) provided on the first supply line (510) to control a flow rate of water flowing through the first supply line, and a second control valve (620) provided on the third supply line (530) to control a flow rate of water flowing through the third supply line (530), thereby separately controlling the flow rates of water flowing through the first supply line (510) and the third supply line (530).

Description

1. Technical field

[0001] The present disclosure relates to a hydrogen reforming system in which a water supply line is connected to a heat exchanger and equipped with a control valve for controlling a flow rate of water, so that the mixed gas can be cooled by heat exchange with water in the heat exchanger and the temperature of the mixed gas can be controlled stepwise by means of the control valve. 2. Description of the state of the art

[0002] A fuel cell is a device that converts the chemical energy of a fuel and an oxidant into electrical and thermal energy. Due to the high energy conversion rate of fuel cells compared to conventional power conversion, extensive research and development has been conducted, and fuel cells are considered a next-generation energy generation device. When hydrogen is used as a fuel, the electrochemical reaction is highly active and produces no harmful pollutants, apart from a small amount of nitrogen oxide. Various techniques have been developed for using hydrogen as an energy source, as hydrogen is easily stored in different forms, such as high-pressure gas, liquefied gas, metal hydrides, and the like.

[0003] Steam reforming is a commercialized technology for producing hydrogen. In steam reforming, hydrogen is produced using a reformer, employing natural gas, such as town gas, as fuel. The steam reforming reaction requires water and fuel gas as reactants. After being introduced as a liquid, the fuel gas vaporizes through heat exchange with the mixed gas produced during the reforming process and transitions into the gaseous phase. The temperature of the mixed gas is controlled by heat exchange with water.

[0004] A hydrogen reforming system allows various reactions to take place and operates under different temperature conditions, from a fuel cell feed temperature of 80 °C to a reforming temperature of 800 °C. Therefore, many heat exchangers are equipped to properly control the temperature conditions in a reactor where individual reactions occur. In conventional hydrogen reforming systems, the temperature of the heat exchanger cannot be controlled individually, making it impossible to control the temperature of the mixed gas in each reaction step. There is a need to address the problems of conventional hydrogen reforming systems, where the system is unreliable due to the temperature and state of the water within the system being influenced by the external environment, resulting in low efficiency.

[0005] Document US 2006 O 177 372 A1 is known. It describes how hydrogen generators operating over a range of hydrogen production rates are controlled by switching between a net hydrogen production rate and a net hydrogen loss rate. A hydrogen storage tank (150) is provided, and the amount of hydrogen in the tank determines which hydrogen production rate is used by the hydrogen generator. BRIEF SUMMARY OF THE INVENTION

[0006] The invention aims to provide a hydrogen reforming system in which a water supply line for supplying the hydrogen reforming system with water is connected to each heat exchanger and is equipped with a control valve for controlling a flow rate of water, so that temperatures of the mixed gas can be controlled in each reaction step.

[0007] According to the invention, a hydrogen reforming system is provided which comprises the features according to claim 1.

[0008] Furthermore, the hydrogen reforming system can also include a control unit that controls the control valve based on received feedback about the temperatures of the first and second mixed gases, thereby controlling the flow rate of water.

[0009] The controller can regulate the flow rate of water by adjusting the control valve depending on a load applied to the system.

[0010] The heat exchanger may include a fourth heat exchanger provided at an inlet of the PSA unit into which the second mixed gas is introduced, the fourth exchanger being operated selectively depending on the temperature of the second mixed gas.

[0011] The hydrogen reforming system may further include: a first temperature sensor that measures a temperature of the first mixed gas; and a second temperature sensor that measures a temperature of the second mixed gas, wherein the first control valve is given feedback on a measurement from the first temperature sensor to control a flow rate of the first supply line, and the second control valve is given feedback on a measurement from the second temperature sensor to control a flow rate of the first supply line.

[0012] The heat exchanger may further comprise a fifth heat exchanger provided at an inlet of the reformer; and the water supply line may comprise a fourth supply line formed downstream of the heat exchanger behind the first supply line towards the third supply line in order to supply the fifth heat exchanger with heated water through it.

[0013] The hydrogen reforming system can further include a fuel gas supply line through which fuel gas is supplied to the second supply line, so that the second mixed gas undergoes heat exchange with water and the fuel gas and water.

[0014] The water feeder may include a fourth supply line formed downstream of the heat exchanger behind the first supply line towards the third supply line, with the heated water being fed through the fourth supply line into the fifth heat exchanger, and the fuel gas exiting the second heat exchanger being recovered together with water through the fourth supply line.

[0015] The fuel gas supply line can be equipped with a gas control valve to control the flow rate of fuel gas and with a third temperature sensor that measures the temperature of the second mixed gas flowing out of the second heat exchanger, the gas control valve receiving feedback on measurements from the third temperature sensor to control the flow rate in the fuel gas supply line.

[0016] The heat exchanger may further comprise: a sixth heat exchanger between the second heat exchanger and the third heat exchanger, in which the second mixed gas undergoes a heat exchange with the fuel gas; and a fuel gas supply line through which fuel gas is supplied to the sixth heat exchanger to enable the second mixed gas to undergo a heat exchange with the fuel gas.

[0017] The fuel gas supply line can be equipped with a gas control valve to control the flow rate of fuel gas and with a third temperature sensor to measure the temperature of the second mixed gas passing through the sixth heat exchanger, the gas control valve receiving feedback from a measurement by the third temperature sensor to control the flow rate in the fuel gas supply line.

[0018] As previously described, the hydrogen reforming system of the present disclosure is designed to control the temperature of the mixed gas in each reaction step by adjusting the flow rates of water. Thus, even under changing external conditions, the system can consistently control the temperature of the mixed gas and exhibit improved stability and efficiency.

[0019] In one embodiment where fuel gas is used as a coolant, the fuel gas is heated before being introduced into the reformer, which can improve the efficiency of the system.

[0020] Furthermore, the operation of the heat exchanger, which uses cooling water as a coolant, is stopped after the temperature of the mixed gas using water as a coolant has fallen below a predetermined point, thereby increasing production efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] The foregoing and other aspects, features, and advantages of the present disclosure will become more apparent from the following detailed description in conjunction with the accompanying drawings. These show: Fig. 1 (STATE OF THE ART) a schematic view of a conventional hydrogen reforming system; Fig. 2 a schematic view of a hydrogen reforming system according to a first embodiment of the present disclosure; Fig. 3 a schematic view of a hydrogen reforming system according to a second embodiment of the present disclosure; and Fig. 4 a schematic view of a hydrogen reforming system according to a third embodiment of the present disclosure. DETAILED DESCRIPTION OF EXAMPLE EXECUTION FORMS

[0022] It is understood that the term "vehicle" or "vehicle-..." or any other similar term as used herein includes motor vehicles in general, such as passenger cars, including SUVs, buses, trucks, various commercial vehicles, watercraft, including a range of boats and ships, aircraft and the like, and hybrid vehicles, electric vehicles, plug-in hybrid electric vehicles, hydrogen-powered vehicles and vehicles using other alternative fuels (e.g., fuels derived from resources other than petroleum). A hybrid vehicle such as those referred to herein is a vehicle that has two or more sources of propulsion, for example, vehicles with both gasoline and electric propulsion.

[0023] The terminology used herein serves only to describe certain embodiments and is not intended to limit the disclosure. The singular forms "ein", "eine" and "der", "die", "das" used herein are also intended to include the plural forms, unless clearly indicated otherwise in the context.

[0024] Furthermore, it is understood that terms such as "includes" and / or "comprehensive" as used in this patent specification indicate the presence of specified features, integers, steps, operations, elements, and / or components, but do not exclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and / or groups thereof. The term "and / or" used herein includes any and all combinations of one or more of the assigned, listed items. Throughout this patent specification, unless expressly stated otherwise, the word "includes" and variations such as "includes" or "comprehensive" are to be understood as signifying the inclusion of specified elements, but not the exclusion of any other elements.Additionally, the terms “unit”, “er”, “-or” and “module”, which are described in the patent specification, refer to units for processing at least one function and operation, and can be implemented using hardware components or software components and combinations thereof.

[0025] Furthermore, the control logic of the present disclosure can be implemented as non-volatile, computer-readable media on a computer-readable medium containing executable program instructions that are executed by a processor, controller, or the like. Examples of computer-readable media include, but are not limited to, read-only memory (ROM), random-access memory (RAM), compact disc ROMs (CD-ROMs), magnetic tapes, floppy disks, flash drives, smart cards, and optical data storage devices. The computer-readable medium can also be distributed in networked computer systems, allowing computer-readable media to be stored and executed in a distributed manner, for example, by means of a telematics server or a CAN (controller area network).

[0026] Specific structural or functional descriptions relating to embodiments according to the present disclosure and disclosed in the present patent specification or application are merely illustrative for the purpose of describing embodiments of the present disclosure. The embodiments of the present disclosure can be implemented in various forms and should not be interpreted as being limited to the embodiments described in the present patent specification or application.

[0027] The embodiments according to the present disclosure can be modified in various ways and can have different forms, so specific embodiments are to be illustrated in the drawings and described in detail in the present patent specification or application. However, it should be understood that these embodiments are not intended to limit the embodiments based on the concept of the present disclosure to specific forms of disclosure, and that they include all modifications, equivalents, or variations that are encompassed within the inventive concept and scope of the present disclosure.

[0028] The terms "first" and "second" can be used to describe different components, but these components are not intended to be restricted by the terms. The terms are used merely to distinguish one component from other components, and a first component may be designated as a second component and a second component may similarly be designated as a first component without deviating from the scope based on the concept of the present disclosure.

[0029] Embodiments of the present disclosure are described in detail below with reference to the attached drawings. The same reference numerals are used in the different drawings to identify identical or similar components.

[0030] Fig. Figure 1 (STATE OF THE ART) is a schematic design view of a conventional hydrogen reforming system.

[0031] With reference to Fig. In Figure 1, the conventional hydrogen reforming system is designed such that water, after being supplied from a water feeder 20, is heated to become steam as it successively passes through a third heat exchanger 430, a second heat exchanger 420, and a first heat exchanger 410. In a reformer 100, steam and fuel gas undergo a reforming reaction to produce a mixed gas containing hydrogen. The mixed gas undergoes a purification process and then enters a fourth heat exchanger 440, where the purified gas is cooled by heat exchange with cooling water before being fed to a pressure swing adsorption (PSA) unit 300.

[0032] The coolant used in the first heat exchanger 410, the second heat exchanger 420, and the third heat exchanger 430 is the water supplied from the water feeder 20, whereas the coolant in the fourth heat exchanger 440 is separately supplied cooling water. In the conventional hydrogen reforming system, the temperature and state of the water are influenced by the external environment, making temperature control of the mixed gas unreliable. The difficulty of stable temperature control therefore leads to unreliable control of the entire system and reduces its efficiency.

[0033] The present disclosure relates to a hydrogen reforming system that can precisely control the temperature of the mixed gas by controlling the flow rates of water supplied to a plurality of heat exchangers. Even if the external environment changes, the hydrogen reforming system of the present disclosure can control the temperature of the mixed gas at each step and therefore has the technical effect of being able to produce hydrogen efficiently and stably.

[0034] Fig. Figure 2 is a schematic view of a hydrogen reforming system according to a first embodiment of the present disclosure.

[0035] With reference to Fig. 2 The hydrogen reforming system according to a first embodiment of the present disclosure can comprise a reformer 100, a transformer 200, a pressure swing adsorption (PSA) unit 300, a heat exchanger 400, a water supply line 500 and a control valve 600.

[0036] Fuel gas, which uses natural gas as a hydrogen source, can be town gas supplied to every house. The fuel gas, supplied from a fuel gas storage tank 10, can be pressurized up to 8 bar by means of a gas compressor (P).

[0037] The Reformer 100 can form a first mixed gas containing hydrogen by means of a reforming reaction. The reforming reaction between fuel gas and water to form the first mixed gas in the Reformer 100 proceeds according to the following reaction formula 1: CH4 + H2O -CO + 3H2 [Reaction formula 1]

[0038] The methane vapor reforming reaction from reaction formula 1 is a strongly endothermic reaction. Therefore, a burner 700 is required to supply the reformer 100 with the necessary heat of reaction, as the reaction actively takes place under high-temperature conditions. The burner 700 can supply the heat required for the reaction by burning the exhaust gas and fuel gas discharged from the PSA unit 300.

[0039] Referring to reaction formula 1, the reforming reaction between hydrocarbon and steam produces a first mixed gas containing hydrogen and carbon monoxide. This first mixed gas is cooled by heat exchange with water in a first heat exchanger 410 and then introduced into a transformer 200.

[0040] The transformer 200 receives the first mixed gas and removes carbon monoxide from it to produce a second mixed gas. A carbon monoxide removal process may be necessary because carbon monoxide is toxic to a catalyst used in an electrode of a fuel cell stack. Generally, carbon monoxide is removed using the water-gas shift reaction, as shown in reaction formula 2 below: CO + H2O → CO2 + H2 [Reaction formula 2]

[0041] Referring to reaction formula 2, the second mixed gas can contain carbon dioxide and hydrogen. The second mixed gas is cooled before being introduced into the PSA unit 300.

[0042] The PSA unit 300 purifies and separates hydrogen from the second mixed gas and discharges exhaust gas containing carbon dioxide. The exhaust gas is fed into the burner 700 and combusted there. The hydrogen purified in the PSA unit 300 is delivered to customer 30.

[0043] A water supply line 500 can function by supplying water from a water feeder 20 to the system. The water can be pure water or ultrapure water for use in the reforming reaction. The water supply line 500 can be equipped with a water supply pump 501, which determines the total flow rate of discharged water.

[0044] A heat exchanger 400 can be installed between the reformer 100 and the transformer-PSA unit 300, and between the transformer 200 and the PSA unit 300. The first and second mixed gases can be cooled by heat exchange with water in the heat exchanger. The heat exchanger 400 is connected to the water supply line 500 and receives water. The water passes through the heat exchanger and enters the reformer 100, where it is used for reforming.

[0045] A control valve 600 is located in the water supply line 500 and adjusts the flow rate of water supplied to the heat exchanger 400. Because the control valve 600 adjusts the water flow rate, the temperatures of the first and second mixed gases can be controlled individually. If it is necessary to further cool the first and second mixed gases, the control valve 600 is opened to increase the water flow rate.

[0046] In addition, the hydrogen reforming system according to the first embodiment can further include a control unit. The control unit receives feedback on the temperatures of the first and second mixed gases in order to control the control valve 600 and thus the temperatures. When it receives the correct temperature ranges, which are set for the first and second mixed gases, the control unit controls the control valve 600 with reference to the set values. The system includes a temperature sensor for measuring the temperatures of the first and second mixed gases.

[0047] If the temperatures of the first and second mixed gases exceed the set values, the controller opens control valve 600 to increase the water flow rate, thereby lowering the mixed gas temperatures. Conversely, if the temperatures of the first and second mixed gases are lower than the set values, the controller closes control valve 600 to decrease the water flow rate, thereby raising the mixed gas temperatures.

[0048] Depending on the system load, the controller can operate the control valve 600 to adjust the water flow rate. For example, when the system is operating at 100% load, the control valve 600 is fully open. When the system is operating at 50% load, the control valve 600 partially closes to reduce the water flow rate.

[0049] With reference to Fig. 2. The heat exchanger 400 can comprise a first heat exchanger 410, a second heat exchanger 420, and a third heat exchanger 430. The first heat exchanger 410 is located between the reformer 100 and the transformer 200 to cool the first mixed gas by heat exchange with water contained therein. The second heat exchanger 420 and the third heat exchanger 430 are located between the transformer 200 and the PSA unit 300 to cool the second mixed gas by heat exchange with water contained therein. The fourth heat exchanger 440 is located at the inlet of the PSA unit 300. After passing through the third heat exchanger 430, water is introduced into the fourth heat exchanger 440 and cooled by heat exchange with cooling water contained therein.

[0050] Each of the first heat exchanger 410, the second heat exchanger 420, and the third heat exchanger 430 can be designed to communicate directly with and receive water from the water supply line 500. As in Fig. As can be seen in Figure 2, the water supply line 500 can include a first supply line 510, a second supply line 520 and a third supply line 530, each of which is connected to the first heat exchanger 410, the second heat exchanger 420 and the third heat exchanger 430 and supplies them with water.

[0051] When pumped by a water pump 501, water moves through the water supply line 500 and then through the first supply line 510, the second supply line 520, and the third supply line 530. The first supply line 510 can be equipped with a first control valve 610 to control the flow rate of water entering the first heat exchanger 410. A second control valve 620 can be installed on the third supply line 530 to control the flow rate of water entering the third heat exchanger 430. The first control valve 610 and the second control valve 620 control the flow rates of water entering the first heat exchanger 410 and the third heat exchanger 430, respectively. The remaining water flows through the second supply line 520 into the second heat exchanger 420.Thus, the flow rate of water in the second supply line 520 is controlled by means of the first control valve 610 and the second control valve 620.

[0052] With reference to Fig. 2. The heat exchanger can include a fourth heat exchanger 440, which is provided at the inlet of the PSA unit 300, into which the second mixed gas is introduced, to cool the second mixed gas by means of heat exchange with the cooling water contained therein. The fourth heat exchanger 440 does not communicate with the water supply line 500, but is supplied with cooling water from a separate cooling water feeder connected to it. The fourth heat exchanger 440 can be operated selectively, depending on the temperature of the second mixed gas. If the temperature of the second mixed gas has been sufficiently reduced by means of the heat exchanger connected to the water supply line 500, the fourth heat exchanger 440 does not operate, which leads to an improvement in the efficiency of the system.

[0053] Furthermore, the hydrogen reforming system according to the first embodiment of the present disclosure can also include a first temperature sensor 611 and a second temperature sensor 621, each measuring the temperatures of the first and second mixed gases.

[0054] With reference to Fig. 2. The first temperature sensor 611 can be provided between the first heat exchanger 410 and the transformer 200 to measure the temperature of the first mixed gas coming from the first heat exchanger 410. Thus, the first temperature sensor 611 can measure the temperature of the first mixed gas from transformer 200.

[0055] The second temperature sensor 621 can be arranged between the third heat exchanger 430 and the PSA unit 300 to measure the temperature of the second mixed gas from the third heat exchanger 430. If the fourth heat exchanger 440 is provided, the second temperature sensor 621 can be positioned between the third heat exchanger 430 and the fourth heat exchanger 440.

[0056] The first control valve 610 receives feedback regarding the temperature of the first mixed gas, measured by the first temperature sensor 611, in order to control the flow rate of water in the first supply line 510. This means that if the temperature measured by the first temperature sensor 611 is higher than the set value for maintaining the correct temperature range of the first mixed gas, the first control valve 610 opens to increase the flow rate of water through the first supply line 510. As the water flow rate increases, the first mixed gas is cooled to the set value for maintaining the correct temperature range. Under this condition, the first control valve 610 can be actuated to decrease the water flow rate.

[0057] The second control valve 620 can receive feedback regarding the temperature of the second mixed gas, measured by the second temperature sensor 621, in order to control the flow rate of water in the second supply line 520. This means that if the temperature measured by the second temperature sensor 621 is higher than the set value for maintaining the correct temperature range of the second mixed gas, the second control valve 620 opens to increase the flow rate of water flowing through the second supply line 520. When the water flow rate is increased, the second mixed gas is cooled to the set value for maintaining the correct temperature range. Under this condition, the second control valve 620 can be actuated to decrease the water flow rate.

[0058] Accordingly, the hydrogen reforming system of the present disclosure can perform more stable temperature control than conventional systems, since the first control valve 610 and the second control valve 620 each control the flow rates of water depending on the temperatures of the first and second mixed gases, respectively. To control the flow rates of water based on the temperatures of the mixed gas, an electrical connection can be established between the first temperature sensor 611 and the first control valve 610, as well as between the second temperature sensor 621 and the second control valve 620.

[0059] Additionally, the water supply line 500 can include a fourth supply line 540, which is formed downstream of the heat exchanger behind the first supply line 510, the second supply line 520, and the third supply line 530. The water, heated by heat exchange as it passes through the first heat exchanger 410, the second heat exchanger 420, and the third heat exchanger 430, is fed through the fourth supply line 540 into a fifth heat exchanger 450, which is located at the inlet of the reformer 100. The water flowing through the water supply line 500 is heated and vaporized by heat exchange with the first and second mixed gases, and the vapor thus formed is supplied via the fourth supply line 540 to the reformer 100, where the reforming takes place.

[0060] The fifth heat exchanger 450 can be located at the inlet of the reformer 100. Fuel gas and steam are supplied to the fifth heat exchanger 450. The burner 700 combusts the fuel gas and exhaust gas to generate thermal energy, which is then fed into the fifth heat exchanger 450 to achieve the elevated temperature required for reforming. A mixture of water and steam is conveyed to the fifth heat exchanger 450 via the fourth supply line 540.

[0061] The fourth heat exchanger 440 can be arranged between the third heat exchanger 430 and the PSA unit 300. The fourth heat exchanger 440 cools the second mixed gas, which flows out of the third heat exchanger 430, by means of heat exchange with cooling water and can be operated selectively depending on the temperature of the second mixed gas. After being discharged from the transformer 200, the second mixed gas is cooled by means of heat exchange with water as it passes through the second heat exchanger 420 and the third heat exchanger 430. If the temperature of the second mixed gas is low enough, the fourth heat exchanger 440 does not need to be operated. In this case, the second mixed gas is fed directly into the PSA unit 300.

[0062] The temperature of the second mixed gas flowing into the PSA unit 300 can be controlled by operating the fourth heat exchanger 440, which uses cooling water as a coolant. Therefore, the operation of the fourth heat exchanger 440 is included in the basic operating mode of the hydrogen reforming system. However, the hydrogen reforming system of this disclosure can control the temperatures of the first and second mixed gases by means of the first control valve 610 and the second control valve 620. In the event that the second mixed gas flowing out of the third heat exchanger 430 is cooled to a temperature at which the second mixed gas can flow directly into the PSA unit 300, the hydrogen reforming system switches to an optimal efficiency mode in which the fourth heat exchanger 440 is not operated. Accordingly, the hydrogen reforming system makes maximum use of the internal heat to increase the overall efficiency.

[0063] Fig. Figure 3 is a schematic view of a hydrogen reforming system according to a second embodiment of the present disclosure. With reference to Fig. 3. According to a second embodiment of the present disclosure, the hydrogen reforming system can be configured to use fuel gas as a coolant. The system can further comprise a fuel gas supply line 800 through which fuel gas is supplied to the second supply line 520, so that the fuel gas undergoes heat exchange with the second mixed gas.

[0064] After passing through supply line 800 and into the second supply line 520, the fuel gas, along with water, can flow into the second heat exchanger 420. In the second heat exchanger 420, the water and the fuel gas are used as a coolant to cool the second mixed gas. After passing through the fuel gas supply line 800, the fuel gas is mixed with water in the second supply line 520, and the mixture is introduced into the second heat exchanger 420, where the second mixed gas can be thermally exchanged, with the water and fuel gas serving as the coolant.

[0065] The fuel gas thermally exchanged in the second heat exchanger 420 is heated by heat exchange with the second mixed gas and, together with water, can be recovered via the fourth supply line 540. The fourth supply line 540 is connected to the inlet of the reformer 100, so that the heated water and fuel gas can be used in the reforming reaction. The water and fuel gas recovered via the fourth supply line 540 are further heated by the burner 700 and then introduced into the reformer 100, where the reforming reaction takes place. The use of fuel gas as a coolant makes it possible to increase the temperature of the fuel gas using the heat from the mixed gas, thereby improving the overall thermal efficiency of the entire system.

[0066] Furthermore, the fuel gas supply line 800 can be equipped with a gas control valve 810 for controlling the fuel gas flow rate. The gas control valve 810 can control the temperature of the second mixed gas by adjusting the flow rate of fuel gas supplied to the second supply line 520.

[0067] A third temperature sensor 811 can be installed at the rear end of the second heat exchanger 420 to measure the temperature of the second mixed gas flowing out of the second heat exchanger 420. Since it receives feedback from the measurements of the third temperature sensor 811, the gas control valve 810 can control the flow rate in the fuel gas supply line 800. For example, if the temperature of the second mixed gas is higher than a set value, as measured by the third temperature sensor 811, cooling is required. In this case, the control valve 810 increases the flow rate of the fuel gas. Conversely, if the temperature of the second mixed gas is lower than a set value, as measured by the third temperature sensor 811, the gas control valve 810 decreases the flow rate of the fuel gas.

[0068] To facilitate understanding of this disclosure, a description with numerical examples is provided. However, it should be understood that the temperature values ​​are given for illustrative purposes and do not limit the present disclosure.

[0069] The correct temperatures are set to 300 °C for the first mixed gas exiting the first heat exchanger 410, 180 °C for the second mixed gas exiting the second heat exchanger 420, and 120 °C for the second mixed gas exiting the third heat exchanger 430. Temperatures within permissible deviations from the correct temperatures are defined as setpoints.

[0070] The first mixed gas exiting reformer 100 is cooled by heat exchange with water in the first heat exchanger 410. Since the first mixed gas to be introduced into transformer 200 should have the correct temperature of 300 °C, the first control valve 610 can be operated based on a comparison between the reading of the first temperature sensor 611 and the set value. The first control valve 610 can control the temperature of the first mixed gas by adjusting the flow rate of water flowing through the first supply line 510.

[0071] After it is discharged from the transformer 200, the second mixed gas can be cooled in the second heat exchanger 420 and the third heat exchanger 430.

[0072] If a reading in the third temperature sensor 811 deviates from the set value, which is defined around the reference value of 180 °C, the second control valve 620 controls the flow rate of water in the second supply line 520. Similarly, if a reading in the third temperature sensor 621 deviates from the set value, which is defined around the reference value of 120 °C, the third control valve controls the flow rate of water in the third supply line 530.

[0073] In the event that the system is operating in an optimal efficiency mode, the third control valve will operate in such a way that the flow rate of water through the third supply line 530 remains unchanged, even if a reading in the third temperature sensor 811 is below 120 °C. If a reading in the third temperature sensor 811 drops to 40 °C or less, the inflow of cooling water is stopped to terminate the operation of the fourth heat exchanger 440. In this case, the system is operating in an optimal efficiency mode, utilizing internal heat to increase efficiency.

[0074] As described herein, the control unit can actuate the control valve.

[0075] Fig. Figure 4 is a schematic view of a hydrogen reforming system according to a third embodiment of the present disclosure. With reference to Fig.4. According to a third embodiment of the present disclosure, the hydrogen reforming system may further comprise a sixth heat exchanger 460.

[0076] The sixth heat exchanger 460 can be positioned between the second heat exchanger 420 and the third heat exchanger 430. The sixth heat exchanger 460 communicates with the fuel gas supply line 800. In the sixth heat exchanger 460, which receives fuel gas, the second mixed gas exiting the second heat exchanger 420 can be cooled by heat exchange with the fuel gas. In contrast to the second configuration, the third configuration further includes the sixth heat exchanger 460, which uses only fuel gas as a coolant and can therefore provide more precise temperature control.

[0077] In the third embodiment, the fuel gas supply line 800 can also be equipped with a gas control valve 810 for controlling the fuel gas flow rate, and a third temperature sensor 811 can be installed at the rear end of the sixth heat exchanger 460. Since it receives feedback on measurements from the third temperature sensor 811 regarding the temperatures of the second mixed gas, the control valve 810 can control the fuel gas flow rates.

[0078] A detailed description of other embodiments and technical advantages other than those described separately in the second and third embodiments of the present disclosure has been omitted, since these are the same as in the first embodiment.

[0079] Although embodiments of the present disclosure have been disclosed for illustrative purposes, the person skilled in the art will recognize that various modifications, additions, and substitutions are possible without deviating from the scope and inventive concept of the disclosure as disclosed in the accompanying claims. Therefore, the technical scope of the present disclosure should be defined by the technical concept and scope of the accompanying claims.

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