High efficiency modular fuel cell system

Abstract

This high efficiency modular fuel cell system is provided, the system comprising: a fuel cell stack; a reformer which is integrated with a burner and directly utilizes the heat generated from the burner to reform the fuel from the outside into hydrogen; and a plurality of heat exchangers for receiving the burner-off gas from the reformer through a hot line and continuously processing the burner-off gas, wherein the reformer and the heat exchangers are modularized in a space adjacent to the fuel cell stack.

Description

High-efficiency modular fuel cell system

[0001] The present invention relates to a high-efficiency modular fuel cell system. More specifically, it relates to a high-efficiency modular fuel cell system that maximizes thermal efficiency by arranging heat exchanger modules and fuel cell stack modules in series as a single system.

[0002] The existing solid oxide fuel cell (SOFC) is a power generation system that converts solid oxide into electrical energy and thermal energy through a catalytic reaction at high temperatures to produce electricity.

[0003] The structure of the above SOFC consists of a cold box that supplies an energy source, a hot box that reforms the supplied energy source at high temperatures, a stack that converts the reformed solid fuel into electrical energy, and an inverter that extracts and supplies electricity.

[0004] However, it is necessary to develop a new system technology that maximizes thermal efficiency by considering the heat duty of the heat exchanger of the stack and hot box.

[0005] Therefore, the problem that the present invention seeks to solve is to provide a new fuel cell system that maximizes thermal efficiency.

[0006] In order to solve the above problem, the present invention provides a high-efficiency modular fuel cell system, comprising: a fuel cell stack; a reformer integrated with a burner, which directly utilizes heat generated from the burner and reforms fuel into hydrogen from the outside; and a plurality of heat exchangers which receive burner off gas from the reformer through a hot line and continuously process the same, wherein the reformer and the heat exchanger are modularized in a space adjacent to the fuel cell stack.

[0007] In one embodiment of the present invention, the heat exchanger includes a first heat exchanger, a second heat exchanger, a third heat exchanger, and a fourth heat exchanger, and the burner off gas sequentially passes through the first heat exchanger, the second heat exchanger, the third heat exchanger, and the fourth heat exchanger and exchanges heat with the hot line.

[0008] In one embodiment of the present invention, air supplied to the cathode of the fuel cell stack sequentially passes through the fourth heat exchanger and the first heat exchanger and exchanges heat with the cold line.

[0009] In one embodiment of the present invention, the high-efficiency modular fuel cell system further includes an eighth heat exchanger between the first heat exchanger and the fourth heat exchanger, wherein the eighth heat exchanger receives an anode off-gas from the anode of the fuel cell stack through a hot line and heats the air passing through the fourth heat exchanger before entering the first heat exchanger.

[0010] In one embodiment of the present invention, the burner heats the reformer and simultaneously generates the burner off-gas to heat the cathode of the fuel cell stack.

[0011] In one embodiment of the present invention, the burner is supplied with air and fuel, a portion of the air is pre-mixed with the fuel flowing into the burner, and the remaining portion of the air is supplied to the side of the burner.

[0012] In one embodiment of the present invention, the remaining portion of the air is introduced into the middle side of the burner chamber to control the height of the flame of the burner.

[0013] According to the present invention, a fuel cell with high thermal efficiency can be realized by sequentially connecting each off-gas to a heat exchanger and modularizing the hot box. Furthermore, by integrating the burner and reforming reaction, the burner off-gas can be utilized from the initial stage of operation, enabling simultaneous temperature increase of the reformer and fuel cell. Furthermore, by configuring the air inlet line for the burner integrated with the reformer to the side of the burner, the height of the flame at the bottom of the reformer can be effectively controlled.

[0014] FIG. 1 is a block diagram of a fuel cell system according to one embodiment of the present invention.

[0015] Figure 2 is a process flow diagram of a fuel cell system according to one embodiment of the present invention.

[0016] FIG. 3 is a drawing illustrating a process of heating air supplied to a cathode according to one embodiment of the present invention.

[0017] Figure 4 is a cross-sectional schematic diagram of a burner of a fuel cell system according to one embodiment of the present invention.

[0018] Figure 5 is a perspective view of a burner according to one embodiment of the present invention.

[0019] Hereinafter, a preferred embodiment of the present invention will be described in detail with reference to the attached drawings.

[0020] Before describing the present invention in detail, it should be noted that the terms or words used in this specification should not be interpreted as being unconditionally limited to their usual or dictionary meanings, and the inventor of the present invention may appropriately define and use the concepts of various terms in order to describe his or her invention in the best possible manner.

[0021] Furthermore, it should be noted that these terms and words should be interpreted with meanings and concepts that are consistent with the technical idea of ​​the present invention.

[0022] That is, the terms used in this specification are only used to describe preferred embodiments of the present invention, and are not intended to specifically limit the contents of the present invention.

[0023] It should be noted that these terms are defined taking into account the various possibilities of the present invention.

[0024] Additionally, in this specification, a singular expression may include a plural expression unless the context clearly indicates a different meaning.

[0025] Also, it should be noted that even if similarly expressed in plural, it can contain singular meaning.

[0026] Throughout this specification, whenever a component is described as "including" another component, it may mean that the component may further include any other component, rather than excluding any other component, unless specifically stated otherwise.

[0027] Furthermore, if a component is described as being "internal to, connected to, or installed within" another component, it is understood that the component may be directly connected to, or installed in contact with, the other component.

[0028] As used herein, a “hot line” is a line connected to a heat exchanger and supplies heat through a medium, and a “cold line” is a line connected to a heat exchanger and supplies heat from the medium of the hot line and through which a heated medium flows.

[0029] In order to solve the above-described problem, the present invention provides a high-efficiency modular fuel cell system, comprising: a fuel cell stack; a reformer integrated with a burner, which directly utilizes heat generated from the burner and reforms fuel into hydrogen from the outside; and a heat exchanger system which receives burner off gas from the reformer through a hot line and continuously processes the same.

[0030] In particular, the present invention has a structure in which the stack and hot box (reformer and heat exchanger) are adjacent as separate modules in a single system. As used herein, "module" refers to a unit system directly connected to a distinct space (e.g., a plate) within a single system, and "adjacent" refers to each module being arranged sideways or above and below each other.

[0031] FIG. 1 is a block diagram of a fuel cell system according to one embodiment of the present invention.

[0032] Referring to FIG. 1, a fuel cell system according to one embodiment of the present invention includes a Cold Box (10) configured as a device for supplying solid oxide fuel; a Hot Box (20) for converting fuel supplied from the Cold Box into thermal energy; a Stack (30) for receiving raw materials that have undergone a reforming and temperature-increasing process from the Hot Box and producing electricity; and an Inverter (40) for transmitting and transferring the produced electricity.

[0033] The present invention has the advantage of being able to maximize thermal efficiency by minimizing heat exchange lines and installing the stack and hot box adjacently in a modularized space within a single system, and also being easy to maintain and manage.

[0034] In one embodiment of the present invention, the hot box includes a reformer coupled with a burner and a plurality of heat exchangers connected in series. In particular, in one embodiment of the present invention, the burner integrated with the reformer performs the function of providing the amount of heat required for the reforming reaction of the reformer while increasing the temperature of the air supplied to the stack, which will be described in more detail below.

[0035] Figure 2 is a process flow diagram of a fuel cell system according to one embodiment of the present invention.

[0036] Referring to FIG. 2, a fuel cell system according to the present invention includes a reformer (100) in which a burner (BN) and a reforming reactor (SR) are integrated, and a fuel cell stack unit (200) that receives hydrogen from the reformer and produces electricity. The fuel cell includes a cathode and an anode.

[0037] The present invention also includes a first heat exchanger (HEX-1) that receives off-gas (hereinafter referred to as burner-off-gas (BOG)) generated from a burner through a hot line, and a second heat exchanger (HEX-2), a third heat exchanger (HEX-3), and a fourth heat exchanger (HEX-4) connected in series with the first heat exchanger (HEX-1).

[0038] That is, the BOG generated after ignition of the burner integrated with the reforming reactor is gradually cooled as it sequentially passes through the first heat exchanger, the second heat exchanger, the third heat exchanger, and the fourth heat exchanger as a hot line (red line in Fig. 2).

[0039]

[0040] *The present invention focuses on the point that the air supplied to the cathode is heated to a high temperature immediately beforehand, and connects the first heat exchanger that receives the highest temperature BOG through the hot line (H1) and the air injection line (L1) immediately before the cathode, thereby supplying the air heated to the highest temperature to the cathode of the fuel cell.

[0041] Thereafter, the present invention supplies water to a second heat exchanger (HEX2) connected to the first heat exchanger to steam water requiring a second high heat load, thereby steaming the water. In addition, the present invention includes a mixer (MIXER) for mixing steam and fuel, so that steam and fuel generated by being heated in the second heat exchanger can be mixed and supplied to the reformer (100).

[0042] FIG. 3 is a drawing illustrating a process of heating air supplied to a cathode according to one embodiment of the present invention.

[0043] Referring to FIG. 3, the air that is heated in the first heat exchanger (HEX-1) and supplied to the cathode through the L5 line is heated for the first time in the fourth heat exchanger (HEX-4) downstream of the BOG hot line before flowing from the first heat exchanger (HEX-1) to the cathode. That is, the BOG that has passed through the third heat exchanger (HEX-3) in the BOG line heats the outside air for the first time in the fourth heat exchanger. Thereafter, the first-heated air is heated for the second time through the eighth heat exchanger (HEX-8) through the line (L3), and then is finally heated for the third time in the first heat exchanger (HEX-1). That is, while passing through L2-L3-L4-L5, the air goes through the first temperature increase, second temperature increase, and third temperature increase processes, and depending on the heat load, the air is heated a second time in the 8th heat exchanger with the anode off gas (AOG) coming out of the stack unit (200), which takes into account the actual temperature increase conditions of the air and the heat load of each BOG and AOG.

[0044] Accordingly, the present invention sequentially heats up air and water in multiple stages by arranging a plurality of heat exchangers in series and utilizing anode-off gas and burner-off gas, and in particular, through a modular configuration, the line length between units can be minimized, resulting in very high thermal efficiency.

[0045] The fuel cell system according to the present invention integrates a reforming reactor and a burner as described above, supplies fuel and air to the burner to provide the heat of the burner as reforming reaction heat, and at the same time, raises the temperature of the fuel cell with the burner-off gas generated (see the first heat exchanger of FIG. 2).

[0046] Therefore, in the present invention, such burner operation is very important. In the present invention, a portion of the supplied air is mixed with the fuel in advance outside the burner, and the remainder is supplied to the side of the burner to stably maintain the flame generated after ignition. The burner according to the present invention will be described in more detail below using the drawings.

[0047] Figure 4 is a cross-sectional schematic diagram of a burner of a fuel cell system according to one embodiment of the present invention.

[0048] Referring to FIG. 4, a reformer (100) according to one embodiment of the present invention includes a reactor (SR) equipped with a catalyst at the top and a burner (BN) supplied with fuel such as natural gas and air at the bottom and ignited to generate heat.

[0049] The present invention has confirmed that the position of the flame generated after ignition is very important in the reforming reaction, especially under a reformer system in which a separate reforming reactor is provided at the top, and thus a second air supply line (L8) branching from a first air supply line (L7) is connected to a fuel supply line (L6), thereby pre-mixing fuel and air before being supplied to a burner.

[0050] In addition, the present invention connects another third air supply line (L9) branching from the first air supply line (L7) to the middle side of the burner. In this case, the air supplied from the third air supply line (L9) performs the function of suppressing the flame generated in the torch section (not shown) within the burner from rising upward, thereby stably controlling the flame position at the bottom of the reformer.

[0051] Figure 5 is a perspective view of a burner according to one embodiment of the present invention.

[0052] Referring to FIG. 5, it can be seen that L6 (fuel supply line, CH4 supply), L7 (combustion air supply line, air supply), L8 (recovery reformed gas line, AOG recovery), and L9 (air supply line for preventing combustion flame floating, air supply) are connected to a burner according to one embodiment of the present invention.

[0053] As described above, the fuel cell system according to the present invention achieves high thermal efficiency by sequentially connecting each off-gas to a heat exchanger and modularizing the hot box. Furthermore, by integrating the burner and reforming reaction, the burner off-gas can be utilized from the initial stage of operation, enabling simultaneous temperature rise of the reformer and the fuel cell. Furthermore, by configuring the air inlet line for supplying the burner integrated with the reformer to the side of the burner, the height of the flame below the reformer can be effectively controlled.

[0054] The high-efficiency modular fuel cell system according to the present invention has potential for use in the fuel cell industry.

Claims

1. High-efficiency modular fuel cell system, fuel cell stack; and A reformer integrated with a burner that directly utilizes the heat generated from the burner and reforms fuel from the outside into hydrogen; It includes a plurality of heat exchangers that continuously process the burner off gas supplied from the above reformer through a hot line. A high-efficiency modular fuel cell system characterized in that the reformer and heat exchanger are modularized in a space adjacent to the fuel display stack.

2. In paragraph 1, A high-efficiency modular fuel cell system characterized in that the heat exchanger includes a first heat exchanger, a second heat exchanger, a third heat exchanger, and a fourth heat exchanger, and the burner off gas sequentially passes through the first heat exchanger, the second heat exchanger, the third heat exchanger, and the fourth heat exchanger and undergoes heat exchange through a hot line.

3. In paragraph 2, A high-efficiency modular fuel cell system characterized in that the air supplied to the cathode of the fuel cell stack sequentially passes through the fourth heat exchanger and the first heat exchanger and undergoes heat exchange with a cold line.

4. In the third paragraph, the high-efficiency modular fuel cell system, A high-efficiency modular fuel cell system characterized in that it further includes an eighth heat exchanger between the first heat exchanger and the fourth heat exchanger, wherein the eighth heat exchanger receives anode off-gas from the anode of the fuel cell stack through a hot line and heats the air that has passed through the fourth heat exchanger before entering the first heat exchanger.

5. In paragraph 4, A high-efficiency modular fuel cell system characterized in that the burner raises the temperature of the reformer and simultaneously generates the burner off-gas to raise the temperature of the cathode of the fuel cell stack.

6. In paragraph 1, A high-efficiency modular fuel cell system characterized in that air and fuel are supplied to the burner, a portion of the air is pre-mixed with the fuel flowing into the burner, and the remaining portion of the air is supplied to the side of the burner.

7. In paragraph 6, A high-efficiency modular fuel cell system characterized in that the remaining portion of the air is introduced into the middle side of the burner chamber so as to control the height of the flame of the burner.

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