Heat source system, heat source system operation method

Abstract

To easily and efficiently utilize the mixed gas mainly composed of hydrocarbon and hydrogen.SOLUTION: A heat-source machine system 10A includes: a fuel-cell cell stack 20 in which the mixture gas containing the mixed gas mainly composed of hydrocarbon and hydrogen is supplied from a gas conduit G to a fuel electrode 20A without being reformed; and a heat source machine 30 having a burner 32 which burns the fuel electrode off-gas discharged from the fuel electrode 20A of the fuel-cell cell stack 20, and a heat exchanger 34 which performs the heat exchange between the combustion heat by the burner 32 and the fluid to be heated.SELECTED DRAWING: Figure 1

Description

Technical Field

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[0001] The present invention relates to a heat source machine system and a method for operating a heat source machine system.

Background Art

[0002] In order to realize a low-carbon society, it has been considered to use a mixed gas in which hydrogen is mixed with a hydrocarbon-based gas mainly composed of methane such as conventional city gas. When supplying such a mixed gas from a gas conduit, the handling on the user side becomes a problem.

[0003] In Patent Documents 1 and 2, when hydrogen fuel equipment and existing gas combustion equipment coexist, in order to use both equipment without problems, hydrogen and hydrocarbon-based gas in the mixed gas are separated, and the separated unused gas that cannot be used by the equipment is returned to the conduit and supplied to other consumers.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0005] When returning the separated gas to the gas conduit as in Patent Documents 1 and 2, variations occur in the hydrogen and hydrocarbon concentrations of the gas at the return destination, and the gas conduit system becomes large-scale. On the other hand, although it is also conceivable to burn the mixed gas with existing gas combustion equipment, hydrogen cannot be efficiently utilized. When hydrogen fuel equipment users and existing gas combustion equipment users coexist on the consumer side, a method for simply and efficiently using the mixed gas is required.

[0006] This invention was made in consideration of the above facts, and aims to provide a simple and efficient way to utilize a mixed gas mainly composed of hydrocarbons and hydrogen. [Means for solving the problem]

[0007] The heat source system according to claim 1 comprises a fuel cell that supplies a mixed gas mainly composed of hydrocarbons and hydrogen from a gas conduit to a fuel electrode without reforming, and uses the hydrogen in the mixed gas to generate electricity in a power generation reaction; a burner that burns the fuel electrode off-gas discharged from the fuel electrode of the fuel cell; and a heat exchanger that performs heat exchange between the combustion heat from the burner and the fluid to be heated.

[0008] In the heat source system according to claim 1, a mixed gas mainly composed of hydrocarbons and hydrogen from a gas conduit is supplied to the fuel electrode of a fuel cell without reforming, and the hydrogen in the mixed gas is used for power generation in the fuel cell. The fuel electrode off-gas, which is discharged from the fuel electrode without being used for power generation, is used for combustion in the burner of the heat source unit, and heat exchange takes place in the heat exchanger between the combustion heat from the burner and the fluid to be heated, thereby heating the fluid to be heated.

[0009] According to the heat source system of claim 1, hydrogen in the mixed gas is utilized in the fuel cell, and unused hydrocarbons and hydrogen are utilized in the heat source unit. Therefore, compared to the case where hydrogen and hydrocarbons are burned and utilized only in the heat source unit, the amount of energy obtained is greater relative to the energy supplied, and the mixed gas can be utilized efficiently.

[0010] Furthermore, since hydrogen and hydrocarbons are utilized without separating them from the mixed gas, and the mixed gas supplied to the fuel cell is unreformed, separation devices and reformers are not required, resulting in a simple configuration.

[0011] The heat source system according to claim 2 includes an electric heater positioned upstream of the heat exchanger in the flow path of the fluid to be heated to heat the fluid to be heated, and the electricity generated by the fuel cell is supplied to the user's power consumption, with any surplus being supplied to the electric heater.

[0012] According to the heat source system of claim 2, the surplus electricity generated by the fuel cell is supplied to an electric heater, and the fluid to be heated is heated upstream of the heat exchanger. This allows for efficient utilization of surplus electricity.

[0013] Claim 1 The heat source system comprises a fuel supply unit that supplies the mixed gas to the fuel cell, and a control unit that controls the fuel supply unit so that the mixed gas is supplied to the fuel electrode only when there is a request to operate the heat source.

[0014] Claim 1 According to the heat source system described above, the mixed gas is supplied to the fuel electrode only when there is a request to operate the heat source. Here, "when there is a request to operate the heat source" means when there is a request to operate the heat source and the heat source is operating in response to the request. Therefore, a situation will not occur where only the fuel cell is operating and the heat source is not, and the fuel electrode off-gas, which contains hydrocarbons and unused hydrogen emitted from the fuel cell, can be properly treated in the heat source.

[0015] Claim 3 In the heat source system relating to this, the control unit controls the fuel cell so that power generation operation of the fuel cell is started when it determines that the operating time of the heat source unit is equal to or greater than a predetermined power generation time.

[0016] Claim 3 According to the heat source system described above, when it is determined that the operating time of the heat source is equal to or greater than a predetermined power generation time, the fuel cell power generation operation is started, thus suppressing inefficient short-term power generation operation of the fuel cell.

[0017] Claim 4The method for operating a heat source machine system according to this invention supplies, without reforming, a mixed gas mainly composed of hydrocarbon and hydrogen supplied from a gas conduit to the fuel electrode of a fuel cell, generates electricity using the hydrogen in the mixed gas, sends the fuel electrode off-gas discharged from the fuel electrode of the fuel cell to a heat source machine, and heats a fluid to be heated with the combustion heat generated by burning in the burner of the heat source machine. Furthermore, the mixed gas is supplied to the fuel electrode only when there is a request to operate the heat source unit.

[0018] Claim 4 In the method for operating a heat source machine system according to this invention, electricity is generated using the hydrogen in a mixed gas containing hydrocarbon and hydrogen supplied from a gas conduit, the fuel electrode off-gas discharged from the fuel electrode of the fuel cell is burned in the burner of the heat source machine, and a fluid to be heated is heated with the combustion heat. Therefore, the mixed gas can be utilized more efficiently as compared with the case where only the heat source machine burns and utilizes hydrogen and hydrocarbon.

[0019] Moreover, since the mixed gas supplied to the fuel cell is not reformed, a reformer is not required and a simple configuration can be achieved.

Advantages of the Invention

[0020] According to the heat source machine system and the method for operating a heat source machine system of the present invention, a mixed gas mainly composed of hydrocarbon and hydrogen can be utilized simply and efficiently.

Brief Description of the Drawings

[0021] [Figure 1] It is a configuration diagram of a heat source machine system according to the first embodiment. [Figure 2] It is a configuration diagram related to control of a heat source machine system according to the first embodiment. [Figure 3] It is a flowchart of power generation control processing. [Figure 4] It is a configuration diagram of a heat source machine system according to the second embodiment.

Modes for Carrying Out the Invention

[0022] <First Embodiment> A first embodiment of the present invention will be described with reference to the drawings.

[0023] The heat source system 10A is a system installed in a user's home or apartment building, etc., for heating a fluid to be heated, such as water, and is a device that serves as a heat source for hot water supply equipment and hot water floor heating equipment. Figure 1 shows an overview of the main components of the heat source system 10A according to an embodiment of the present invention. The heat source system 10A according to an embodiment of the present invention mainly comprises a power generation unit 12 and a heat source unit 30.

[0024] The heat source system 10A is supplied with a mixed gas from a gas pipeline G that supplies gas to a designated area. The mixed gas is mainly composed of hydrogen and hydrocarbons, and as an example, a gas obtained by mixing hydrogen with city gas can be used. Also, as an example, the hydrogen concentration in the mixed gas can be set to about 0.1% to 10%, and the methane concentration to about 90% to 99.9%. A fuel supply pipe P1 is provided branching off from the gas pipeline G, and the mixed gas is supplied to the heat source system 10A via the fuel supply pipe P1.

[0025] The power generation unit 12 is a device that generates electricity using hydrogen from a mixed gas, and includes a desulfurizer 14, a fuel cell stack 20, an air supply blower 22, a fuel supply blower 24, and a power conditioner 26.

[0026] The fuel cell stack 20 is a cell stack having multiple stacked fuel cell cells. The fuel cell stack 20 is an example of a fuel cell in the present invention, and each fuel cell has an electrolyte layer (not shown), and fuel electrodes 20A and air electrodes 20B stacked on the front and back surfaces of the electrolyte layer, respectively. Various fuel cells can be applied as the fuel cell stack 20, such as solid oxide fuel cells (SOFCs), molten carbonate fuel cells (MCFCs), and polymer electrolyte fuel cells (PEFCs). In this embodiment, a PEFC will be used as an example.

[0027] A fuel supply pipe P1 is connected to the inlet side of the fuel electrode 20A, and an air supply pipe P2 is connected to the inlet side of the air electrode 20B. A fuel supply blower 24 and a desulfurizer 14 are provided in the fuel supply pipe P1, in order from the upstream side. The fuel supply blower 24 sends the mixed gas toward the fuel electrode 20A at a specified flow rate. The desulfurizer 14 removes the sulfur component, which acts as an odorant, from the mixed gas. The mixed gas from which the sulfur component has been removed contains hydrogen and methane and is supplied to the fuel electrode 20A of the fuel cell cell stack 20 without being reformed. An air supply blower 22 is provided in the air supply pipe P2, and air is supplied to the air electrode 20B by the air supply blower 22.

[0028] A fuel electrode off-gas pipe P3 is connected to the outlet side of the fuel electrode 20A, and an air electrode off-gas pipe P4 is connected to the outlet side of the air electrode 20B. The downstream end of the fuel electrode off-gas pipe P3 is connected to a burner 32 of the heat source unit 30, which will be described later. The air electrode off-gas discharged from the air electrode 20B is released into the atmosphere through the air electrode off-gas pipe P4. The fuel electrode off-gas discharged from the fuel electrode 20A is supplied to the burner 32 via the fuel electrode off-gas pipe P3.

[0029] A power conditioner 26 is electrically connected to the fuel cell stack 20. The power conditioner 26 controls the power output of the fuel cell stack 20 and supplies power to the user.

[0030] The heat source unit 30 is a device that heats the fluid to be heated using fuel electrode off-gas discharged from the fuel electrode 20A of the fuel cell stack 20 of the power generation unit 12 as fuel, and has a burner 32 and a heat exchanger 34. Tap water is supplied to the heat exchanger 34 from the water supply pipe P5.

[0031] A fuel electrode off-gas pipe P3 is connected to the burner 32, and fuel electrode off-gas discharged from the fuel electrode 20A of the fuel cell cell stack 20 is supplied to it. The burner 32 is located adjacent to the heat exchanger 34. The burner 32 burns the combustible components in the fuel electrode off-gas, and the heat of combustion heats the tap water supplied to the heat exchanger 34.

[0032] The tap water heated in the heat exchanger 34 is sent out through piping P7 and supplied for hot water supply and underfloor heating. Combustion exhaust gas from the burner 32 is discharged through exhaust pipe P6.

[0033] Figure 2 shows a schematic block diagram of the control system for the heat source system 10A. The heat source system 10A is equipped with a controller 40, which controls the power generation unit 12 and the heat source 30.

[0034] As shown in Figure 2, the controller 40 includes a CPU (Central Processing Unit) 41, a ROM (Read Only Memory) 42, a RAM (Random Access Memory) 43, an input / output interface (I / F) 44, and a storage unit 45.

[0035] The CPU 41, ROM 42, RAM 43, and I / F 44 are connected to each other via the bus 46. Each functional unit, including the memory unit 45, is connected to the I / F 44. These functional units are able to communicate with the CPU 41 via the I / F 44.

[0036] For the storage unit 45, for example, an HDD (Hard Disk Drive), SSD (Solid State Drive), or flash memory may be used. The storage unit 45 stores control programs for controlling each part of the heat source system 10A, as well as various data. These control programs and data may also be stored in the ROM 42.

[0037] In this embodiment, a power generation control processing program and the like are stored as part of the control program. Furthermore, power generation condition information I and the like are stored as data used in this processing.

[0038] The power generation condition information I is the condition for power generation operation to be performed in the power generation unit 12. In this embodiment, the operation of the heat source unit 30 is the condition for power generation operation, and one of the following conditions is also set: when there is an input from the operation panel 50 to start floor heating, when there is an input to start filling the bathtub, or when the hot water supply time exceeds a predetermined time T. The predetermined time T can be set to be shorter than the time for floor heating or filling the bathtub, such as 10 to 20 seconds, but shorter than the time for floor heating or filling the bathtub, but longer than the time for the user to use hot water. The time for floor heating, the time for filling the bathtub, and the predetermined time T or longer are examples of the power generation possible time in this invention.

[0039] The controller 40 is connected to the air supply blower 22, fuel supply blower 24, power conditioner 26, burner 32, control panel 50, etc. The control panel 50 has a display, lamps, switches, etc., and allows the user to input various instructions and displays the status of the heat source system 10A, etc.

[0040] Next, we will explain the operation of the heat source system 10A.

[0041] When the user turns on the power to the heat source system 10A from the control panel 50, the controller 40 executes the power generation control process shown in Figure 3.

[0042] In step S10, it is determined whether or not there is an instruction to drive the heat source unit 30. If the determination is affirmative, the drive of the heat source unit 30 is started in step S12. If the determination is negative, the system waits until there is an instruction to drive the heat source unit. The instruction to drive the heat source unit 30 is given by the user via input from the control panel 50 (start floor heating, fill the bathtub with hot water, etc.) or by the discharge of tap water exceeding the minimum ignition flow rate.

[0043] When the heat source unit 30 is started, the fuel supply blower 24 is activated, and the mixed gas is supplied from the gas conduit G, unreformed, through the desulfurizer 14 and the fuel electrode 20A of the fuel cell cell stack 20 to the burner 32 of the heat source unit 30. The mixed gas (fuel electrode off-gas) is then burned in the burner 32, and the water, which is the fluid to be heated and supplied to the heat exchanger 34, is heated by the heat of combustion. In this embodiment, water is used as an example of the fluid to be heated, but other fluids such as antifreeze (in the case of floor heating) may also be used.

[0044] In step S14, it is determined whether the power generation conditions are met. Whether or not the power generation conditions are met is determined by whether or not the power generation condition information I stored in the memory unit 45 is met. In this embodiment, the determination is affirmed when there is an input to start floor heating from the operation panel 50, when there is an input to start filling the bathtub, or when the hot water supply time after the tap water comes out is longer than a predetermined time T.

[0045] If it is determined in step S14 that the power generation conditions are met, in step S16 the power generation unit 12 outputs an instruction to start power generation operation. Upon starting power generation, the air supply blower 22 is driven to supply air to the air electrode 20B, and the power conditioner 26 starts the power output of the fuel cell cell stack 20. As a result, the hydrogen in the mixed gas supplied to the fuel cell cell stack 20 is used and consumed in the power generation reaction, and the fuel electrode off-gas after hydrogen consumption is supplied to the burner 32. In the burner 32, the fuel electrode off-gas after hydrogen consumption in the fuel cell cell stack 20 is burned.

[0046] Next, in step S18, the system waits until a stop command is issued for the heat source unit 30. If a stop command is issued for the heat source unit 30, in step S20, the system outputs a stop command for the heat source unit 30, and in step S22, the power generation operation of the power generation unit 12 is stopped.

[0047] In step S24, it is determined whether or not there is a stop command for the heat source system 10A. If the determination is affirmative, this process is terminated. If there is no stop command for the heat source system 10A, the process returns to step S10 and the above process is repeated.

[0048] In the heat source system 10A of this embodiment, hydrogen in the mixed gas is used for power generation in the fuel cell stack 20, and combustible components such as methane that are not used in the fuel cell stack 20 are used in the heat source unit 30. Therefore, the mixed gas can be used more efficiently compared to the case where the mixed gas containing hydrogen and methane is burned and used only in the burner 32 of the heat source unit 30.

[0049] Furthermore, since the mixed gas supplied to the fuel cell stack 20 contains hydrogen, a reformer is not required, allowing for a simpler configuration.

[0050] In this embodiment, the mixed gas is supplied to the fuel cell only when there is an operation request for the heat source unit 30. However, the mixed gas may also be supplied to the fuel cell when the heat source unit 30 is not in operation, and power generation may be performed in the power generation unit 12. In this case, a combustor or the like is provided to appropriately treat the fuel electrode off-gas containing combustible components discharged from the fuel cell cell stack 20. As in this embodiment, by supplying the mixed gas to the fuel cell only when there is an operation request for the heat source unit 30, the fuel electrode off-gas containing combustible components discharged from the fuel cell cell stack 20 can be appropriately treated in the heat source unit 30 without being discharged to the outside. Note that the supply of the mixed gas to the fuel electrode 20A here includes cases where power generation operation of the power generation unit 12 is not performed.

[0051] Furthermore, in this embodiment, the power generation operation of the fuel cell stack 20 is started when it is determined that the operating time of the heat source unit 30 is equal to or greater than the floor heating time, the bathtub filling time, and a predetermined time T, thereby suppressing inefficient power generation operation of the fuel cell stack 20. However, it is not necessarily required that the power generation operation of the fuel cell stack 20 be started only when it is determined that the operating time of the heat source unit 30 is equal to or greater than the floor heating time, the bathtub filling time, and a predetermined time T; the power generation operation of the fuel cell stack 20 may be started simultaneously with the operation of the heat source unit 30.

[0052] <Second Embodiment> Next, a second embodiment of the present invention will be described. In this embodiment, parts similar to those in the first embodiment are denoted by the same reference numerals, and their detailed descriptions will be omitted.

[0053] The heat source system 10B of this embodiment differs from the first embodiment in that it mainly has a heater 52, as shown in Figure 4. The heater 52 is an electric heater and is connected to a water supply pipe P5. The heater 52 heats the tap water from the water supply pipe P5 and sends it to the heat exchanger 34.

[0054] The power conditioner 26 supplies power to the user according to the load power, and if surplus power is generated, it supplies that surplus power to the heater 52.

[0055] In this embodiment, the surplus electricity generated by the fuel cell cell stack 20 is supplied to the heater 52, and the tap water, which is the fluid to be heated, is heated upstream of the heat exchanger 34. Therefore, the surplus electricity can be utilized efficiently.

[0056] Although embodiments of the present invention have been described above, the present invention is not limited to those described above, and it is of course possible to implement it in various modified forms without departing from the spirit of the invention. [Explanation of Symbols]

[0057] 10A, 10B Heat Source System 20 Fuel cell stack (fuel cell) 20A fuel electrode 24. Fuel supply blower (fuel supply unit) 30 Heat source machine 32 burners 34 Heat exchanger 40 Controller (Control Unit) 52 Heater (Electric Heater) G Gas pipeline P5 Water supply pipe (flow channel)

Claims

1. A fuel cell is supplied to a fuel electrode without reforming a mixed gas mainly composed of hydrocarbons and hydrogen, which is supplied from a gas conduit, and uses the hydrogen in the mixed gas to generate electricity in a power generation reaction. A heat source unit having a burner for burning fuel electrode off-gas discharged from the fuel electrode of the fuel cell, and a heat exchanger for performing heat exchange between the combustion heat from the burner and the fluid to be heated, A fuel supply unit that supplies the mixed gas to the fuel cell, A control unit controls the fuel supply unit so that the mixed gas is supplied to the fuel electrode only when there is a request to operate the heat source unit, A heat source system equipped with a heat source unit.

2. The flow path of the fluid to be heated includes an electric heater positioned upstream of the heat exchanger to heat the fluid to be heated, The electricity generated by the fuel cell is supplied to the user's power consumption, and any surplus is supplied to the electric heater. The heat source system according to claim 1.

3. The control unit controls the fuel cell so that power generation operation of the fuel cell is started when it determines that the operating time of the heat source unit is equal to or greater than a predetermined power generation time. The heat source system according to claim 2.

4. A mixed gas mainly composed of hydrocarbons and hydrogen, supplied from a gas pipeline, is supplied unreformed to the fuel electrode of a fuel cell, and electricity is generated using the hydrogen in the mixed gas. A method for operating a heat source system, comprising sending fuel electrode off-gas discharged from the fuel electrode of the fuel cell to a heat source unit, and heating a fluid to be heated with the heat of combustion generated by burning the fuel electrode in the burner of the heat source unit, The mixed gas is supplied to the fuel electrode only when there is a request to operate the heat source unit. Operating method for a heat source system.

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