JP7290543B2 - fuel cell device - Google Patents

Description

The present disclosure relates to fuel cell devices.

2. Description of the Related Art There is known a fuel cell device that generates electric power using air and a fuel gas produced by steam reforming raw fuel gas. In such a fuel cell device, so-called water self-sustaining operation is performed in which condensed water produced by condensing water vapor contained in exhaust gas is used as reforming water. In such a fuel cell device, it becomes difficult to continue operation when the reforming water is insufficient. A fuel cell device that reduces the shortage is disclosed. Further, in recent years, it is also known that when the fuel cell device is disconnected from the commercial power supply system (hereinafter also referred to as the system) due to a power outage or the like, the fuel cell device independently operates independently.

JP 2010-277973 A

By the way, in the cited document 1, there is room for improvement because it does not take into consideration the case where the fuel cell device is disconnected from the commercial power supply system due to a power failure or the like during the operation for suppressing the shortage of the reforming water.

A fuel cell device of the present disclosure is a fuel cell device interconnected to a system,
a fuel cell;
a water tank for storing water collected from the exhaust gas discharged from the fuel cell to be supplied to the fuel cell;
a water level detection device that detects the water level in the water tank;
a water supply device for supplying water to the water tank from the outside;
a control device that controls the operation of the fuel cell,
The control device is
water recovery operation control for increasing the water level of the water tank by suppressing the power generation amount of the fuel cell to a first output that is less than the rated output when the water level of the water tank is detected to be less than a first water level;
a self-sustaining operation control for generating power of the first output or more by the fuel cell alone when the fuel cell is disconnected from the system,
When the water recovery operation control is disconnected from the system during execution of the water recovery operation control, the water recovery operation control is stopped, and the driving of the water supply device and the independent operation control are executed.

According to the fuel cell device of the present disclosure, even when the fuel cell device is disconnected from the system while the water recovery operation control is being executed, the power generation operation can be continued.

1 is a diagram showing a schematic configuration of a fuel cell device according to an embodiment; FIG. 4 is a flowchart for explaining water recovery operation control in the fuel cell device according to the embodiment; 4 is a flowchart for explaining self-sustained operation control in the fuel cell device according to the embodiment; 4 is a flowchart for explaining transition from water recovery operation control to self-supporting operation control in the fuel cell device according to the embodiment; 4 is a flowchart for explaining transition from self-sustained operation control to normal operation control in the fuel cell device according to the embodiment;

A fuel cell device according to an embodiment of the present disclosure will be described below with reference to the drawings. FIG. 1 is a diagram showing a schematic configuration of a fuel cell device according to an embodiment.

A fuel cell device 100 of the embodiment includes a fuel cell 11 , a water tank 6 , a water level detection device 16 , a water supply device 17 and a control device 30 .

The fuel cell 11 generates power using fuel gas and air. The fuel cell 11 may have a cell stack structure including a plurality of fuel cells. The fuel cells may be solid oxide fuel cells. The fuel cell device 100 has a reformer 12 that steam reforms the fuel gas. Further, the fuel cell device 100 has a fuel cell module 1 in which a fuel cell 11 and a reformer 12 are housed in a container 10 .

The fuel gas used for power generation is reformed together with reforming water for reforming the fuel gas through a fuel gas supply device 14 including a fuel gas pump B1 and a pipe F that is a raw fuel gas flow path. introduced into vessel 12 . Air used for power generation is introduced into the fuel cell 11 via an air supply device 15 including an air blower B2 and a pipe G as an air flow path.

The fuel cell device 100 includes a first heat exchanger 2, a heat storage tank 3 that stores a heat medium such as water, a heater 4, a radiator 5, a heat medium pump P1 that circulates the heat medium from the heat storage tank 3, and piping that connects these. It has a first heat circulation system HC1, which is an exhaust heat recovery system.

In the first heat exchanger 2, heat is exchanged between the exhaust gas from the fuel cell module 1 and the heat medium, and moisture contained in the exhaust gas is condensed to produce condensed water. The generated condensed water is collected through the condensed water flow path C and stored in the water tank 6 . Exhaust gas from which moisture has been removed is discharged to the outside through an exhaust gas passage E. The condensed water stored in the water tank 6 is supplied to the reformer 12 through the reforming water flow path R and the reforming water pump P2, and is used as reforming water for steam reforming the fuel gas. . The heat storage tank 3 stores the heat medium that has exchanged heat with the exhaust gas from the fuel cell module 1 .

The water tank 6 is provided with a water level detector 16 for monitoring the amount of water in the water tank 6 . The water level detector 16 detects whether the water level in the water tank 6 is equal to or higher than the first water level H. The first water level H is, for example, the high water level in the water tank 6 . As the water level detection device 16, a known water level sensor such as a float sensor can be used.

The water supply device 17 includes a water supply pipe W connecting a water supply source for supplying water from the outside and the water tank 6, a water supply valve V, and the like. When it is necessary to supply water to the water tank 6, water can be supplied from the water supply source to the water tank 6 via the water supply pipe W. The water supply source is, for example, the water supply, and the water supplied from the water supply source is tap water. The water supply pipe W may be provided with a purifier 18 such as an ion exchange resin to remove impurities such as chlorine contained in the tap water.

The water supply pipe W is connected to the top of the water tank 6, for example. The water supply valve V is arranged in the water supply pipe W between the water tank 6 and the water supply source. When the water supply valve V is opened, the water flowing through the water supply pipe W is supplied to the water tank 6 . When the water supply valve V is closed, water flow through the water supply valve V stops.

The water supply valve V is composed of, for example, an electromagnetic valve, and is opened and closed according to an electric signal output from the control device 30 . The control device 30 outputs an electric signal for controlling to open the water supply valve V when it is necessary to supply water to the water tank 6, and closes the water supply valve V when it is not necessary to supply water to the water tank 6. Outputs an electrical signal to control the closing.

The fuel cell device 100 may include a second heat circulation system HC2 having a second heat exchanger 7, a heat supply pump P3 for circulating the heat medium from the heat storage tank 3, and piping connecting these. In the second heat exchanger 7, heat is exchanged between the high-temperature heat medium stored in the heat storage tank 3 and the low-temperature tap water supplied from the tap water supply via the supply flow path Kin. The tap water (also referred to as hot water) heated by the second heat exchanger 7 is supplied to the hot water supply device 60 via the supply flow path Kout.

The hot water supply device 60 uses the heat stored in the heat storage tank 3 to provide hot water. The hot water supply device 60 discharges the hot water supplied through the supply channel Kout to, for example, a bath, a kitchen, a washbasin, and the like in the home. The discharged hot water is used as domestic water.

The fuel cell device 100 may further include various components necessary for power generation, hot water supply, and the like. Each configuration shown above is an example, and is an arbitrary configuration other than the configuration required for various controls described later.

In addition to the fuel cell module 1 and the like, the fuel cell device 100 includes a power conditioner 20, a control device 30, an operation board (not shown) including a display device and an operation panel, etc. as auxiliary devices for assisting the power generation operation. . The power conditioner 20 supplies the electric power generated by the fuel cell 11 to an external load in connection with the system power supply. The power conditioner 20 can detect when power supply from the grid stops.

The fuel cell system 100 then includes a controller 30, including at least one processor, memory, etc., to provide control and processing power to perform various functions, as described in detail below.

According to various embodiments, at least one processor may be implemented as a single integrated circuit or as multiple communicatively coupled integrated and/or discrete circuits. The at least one processor can be implemented according to various known techniques.

In one embodiment, a processor includes one or more circuits or units configured to perform one or more data computing procedures or processes, such as by executing instructions stored in associated memory. In other embodiments, the processor may be firmware, eg, discrete logic components, configured to perform one or more data computing procedures or processes.

According to various embodiments, the processor is one or more processors, controllers, microprocessors, microcontrollers, application specific integrated circuits, digital signal processors, programmable logic devices, field programmable gate arrays, or any of these devices or Any combination of configurations or combinations of other known devices and configurations may be included to perform the functions described below.

The control device 30 is connected to a storage device and a display device (both not shown), various components and various sensors that constitute the fuel cell device 100, and controls the entire fuel cell device 100 including these functional units. control and manage; The control device 30 acquires a program stored in a storage device attached thereto and executes the program, thereby realizing various functions of each part of the fuel cell device 100 .

When transmitting control signals or various types of information from the control device 30 to other functional units or devices, the control device 30 and other functional units may be connected by wire or wirelessly. The control characteristic of this embodiment performed by the control device 30 will be described later. In the present embodiment, the control device 30 particularly controls various auxiliary devices such as the fuel gas pump B1 based on instructions and commands from external devices connected to the fuel cell device, and instructions and measurement values from the various sensors described above. Control. In some cases, the illustration of connection lines connecting the control device 30 and each device and each sensor constituting the fuel cell is omitted in the drawing.

A storage device (not shown) can store programs and data. The storage device may also be used as a work area for temporarily storing processing results, and stores flags and the like used in heat medium high temperature suppression control and fuel cell high temperature suppression control, which will be described later. A storage device includes a recording medium. The recording medium may include any non-transitory storage medium such as semiconductor storage media and magnetic storage media. Also, the storage device may include multiple types of storage media. The storage device may include a combination of a portable storage medium, such as a memory card, optical disk, or magneto-optical disk, and a storage reader. The storage device may include a storage device such as RAM (Random Access Memory) that is used as a temporary storage area.

Note that the control device 30 and the storage device of the fuel cell device can also be implemented as a configuration provided outside the fuel cell device 100 . Furthermore, it is also possible to implement as a control method including characteristic control steps in the control device 30 according to the present disclosure, or as a control program for causing a computer to execute the above steps.

The control device 30 appropriately switches and executes a plurality of controls for controlling the power generation operation of the fuel cell 11 . The multiple controls include normal operation control, water recovery operation control and isolated operation control.

Normal operation control is to control the power generation operation of the fuel cell 11 when the fuel cell 11 is interconnected with the system. Normal operation control may include a rated operation mode and a partial load operation mode. The rated operation mode is an operation mode in which power generation operation is performed at the rated output E0, and fuel gas and air are supplied to the fuel cell 11 based on a predetermined supply amount for performing power generation operation at the rated output E0, Operate so that the rated output E0 is obtained. The partial load operation mode is an operation mode in which the output is varied in accordance with changes in the external load.

The water recovery operation control is control that gives priority to the recovery efficiency of condensed water. The water recovery operation control is started, for example, when the water level detection device 16 detects that the water level of the water tank 6 is less than the first water level H. In the water recovery operation control, the control device 30 suppresses the output of the fuel cell 11 to a first output E1 that is less than the rated output E0, and also controls other auxiliary equipment to continue the power generation operation of the fuel cell 11. do. The control device 30 supplies the fuel gas and air to the fuel cell 11 based on a predetermined supply amount for power generation operation at the first output E1, and operates the fuel cell 11 so as to achieve the first output E1. . When the water level detector 16 detects that the water level in the water tank 6 is equal to or higher than the first water level H, the water recovery operation control is stopped and the suppression of the output of the fuel cell 11 is released.

In water recovery operation control, in addition to suppressing the output of the fuel cell 11, the control device 30 controls the first Control may be performed to increase the operating duty ratio of the pump and fan of the thermal circulation system HC1. Furthermore, in order to decrease the fuel utilization rate and increase the oxygen utilization rate, the control device 30 controls the gas flow rate, which is the delivery rate of the fuel gas pump B1 that feeds the raw fuel to the reformer, and the air to the cell stack. Control may be performed to increase the operating duty ratio of the raw material supply system pump and blower, such as by controlling the air flow rate, which is the air delivery rate of the air blower B2. These controls can further improve the efficiency of collecting condensed water.

Self-sustained operation control is control that prioritizes power supply to an external load. Self-sustained operation control is started, for example, when the fuel cell 11 is disconnected from the system due to a power failure or the like. In self-sustained operation control, the control device 30 operates the fuel cell 11 with an output equal to or greater than the first output E1, and supplies the generated power to an external load. The output equal to or higher than the first output E1 may be the rated output E0 of the fuel cell 11 . When the fuel cell 11 is re-connected to the system, the self-sustained operation control is stopped.

When the self-sustained operation control is started, the control device 30 increases the flow rate of the fuel gas supplied to the fuel cell module 1 in order to recover the output of the fuel cell 11, and uses the internal load to generate an output equal to or higher than the first output E1. The fuel cell 11 is controlled to perform power generation operation at . As an internal load, for example, the heater 4 of the first thermal circulation system HC1 can be used. After confirming that the power generation operation can be performed with an output equal to or greater than the first output E1, the control device 30 restarts the output to the external load. When outputting to the external load, priority may be given to outputting to the hot water supply device 60 .

In self-sustained operation control, the controller 30 increases the flow rate of the fuel gas supplied to the fuel cell module 1 . Therefore, surplus fuel gas that is not used for power generation tends to be generated, and the amount of heat flowing through the first heat exchanger 2 increases. Furthermore, since the heater 4 is used as an internal load, the heat generated from the heater 4 heats the heat medium, and the temperature of the heat medium tends to rise. Moreover, since the surplus fuel gas is burned in the combustion section between the fuel cell 11 and the reformer 12, the temperature of the fuel cell 11 tends to rise. For these reasons, the heat exchange efficiency between the exhaust gas and the heat medium in the first heat exchanger 2 tends to decrease during the self-sustained operation control. As a result, the efficiency of collecting condensed water is lowered, and water for steam reforming the fuel gas may be insufficient.

Therefore, when the fuel cell 11 is disconnected from the system during execution of the water recovery operation control, the control device 30 stops the water recovery operation control and also executes the driving of the water replenishing device 17 and self-sustained operation control. As a result, power generation operation can be continued. As a result, it becomes possible to improve the convenience for the user.

When the fuel cell 11 is disconnected from the system during execution of water recovery operation control, the control device 30 drives the water supply device 17 until the water level in the water tank 6 reaches the first water level H or higher. Replenishment of water to the water tank 6 may be performed. That is, the control device 30 may open the water supply valve V of the water supply device 17 until it detects that the water level in the water tank 6 has reached the first water level H or higher. As a result, it is possible to prevent the reforming water from becoming insufficient during execution of the self-sustained operation control.

Further, when the fuel cell 11 is disconnected from the system during execution of the water recovery operation control, the control device 30 stops the water recovery operation control and executes self-sustained operation control. Even if the control device 30 detects that the water level in the water tank 6 is less than the first water level H during execution of the self-sustaining operation control, the control device 30 does not execute the water recovery operation control and continues the self-sustaining operation control. good. This makes it possible to continuously supply power to the external load. Note that rated operation may be continued in self-sustained operation control.

If the water level in the water tank 6 is less than the first water level when the fuel cell 11 is reconnected to the system, the control device 30 drives the water supply device 17 so that the water level in the water tank 6 reaches the first water level H. Water supply to the water tank 6 may be executed until the water level reaches the above level. That is, when the control device 30 detects that the water level in the water tank 6 is less than the first water amount when the fuel cell 11 is reconnected to the system, the water level in the water tank 6 is equal to or higher than the first water level H. The water supply valve V of the water replenishment device 17 may be opened until it is detected. The control device 30 stops the isolated operation control when the fuel cell 11 is reconnected to the grid. , condensed water may not be collected sufficiently. When the water level of the water tank 6 is less than the first water amount when reconnecting to the system, reforming water is insufficient by supplying water to the water tank 6 until the water level becomes equal to or higher than the first water level H. It becomes possible to suppress doing.

The control of the fuel cell device 100 executed by the control device 30 will be described below with reference to the flow charts shown in FIGS. In the flowchart, "step" is abbreviated as "S", and in the chart, "positive" (computer flag = 1) in judgment control is [Yes], and "no" (computer flag = 0 zero) is [ No].

FIG. 2 is a flowchart for explaining water recovery operation control in the fuel cell device according to the embodiment. The flow chart in FIG. 2 [starts] when the power generation operation of the fuel cell 11 is started.

In [S21], it is determined whether or not the water level detection device 16 has detected the water level, that is, whether or not the water level in the water tank 6 is less than the first water level H. In [S21], if the water level detection device 16 has not detected the water level [Yes], that is, if the water level in the water tank 6 is less than the first water level H, in [S22], the water recovery operation control is started. Subsequently, in [S23], the output of the fuel cell 11 is suppressed to the first output E1, which is less than the rated output E0, and the process proceeds to the determination of [S24]. In [S21], if the water level detection device 16 detects the water level [No], that is, if the water level in the water tank 6 is equal to or higher than the first water level H, this flow chart ends.

In [S24], it is determined whether or not the water level detection device 16 is detecting the water level, that is, whether or not the water level of the water tank 6 is equal to or higher than the first water level H. In [S24], if the water level detector 16 detects the water level [Yes], that is, if the water level in the water tank 6 is equal to or higher than the first water level H, the water recovery operation control is stopped in [S25]. Subsequently, in [S26], the suppression of the output of the fuel cell 11 is released, and this flow chart ends. In [S24], if the water level detection device has not detected the water level [No], that is, if the water level in the water tank 6 is less than the first water level H, the water recovery operation control is executed and waits.

FIG. 3 is a flowchart for explaining self-sustained operation control in the fuel cell device according to the embodiment. The flow chart of FIG. 3 [starts] when the power generation operation of the fuel cell 11 is started.

In [S31], it is determined whether or not the fuel cell 11 is disconnected from the system. In [S31], if the fuel cell 11 is disconnected from the system [Yes], in [S32], self-sustained operation control is started. Subsequently, in [S33], the output of the fuel cell 11 is restored to the rated output E0, and the process proceeds to the determination of [S34]. In [S31], if the fuel cell 11 has not been disconnected [No], this flow chart ends.

In [S34], it is determined whether or not the fuel cell 11 has been reconnected to the system. In [S34], if the fuel cell 11 has been re-connected to the system [Yes], in [S35] the self-sustained operation control is stopped, and this flow chart ends. In [S34], if the fuel cell 11 has not been re-connected to the system [No], the system waits while the self-sustained operation control is executed.

FIG. 4 is a flowchart for explaining the transition from water recovery operation control to self-supporting operation control in the fuel cell device according to the embodiment. The flow chart of FIG. 4 [starts] when the power generation operation of the fuel cell 11 is started.

In [S41], it is determined whether or not water recovery operation control is being executed. In [S41], if the water recovery operation control is being executed [Yes], the process proceeds to the determination of [S42]. In [S41], if the water recovery operation control is not being executed [No], this flow chart ends.

In [S42], it is determined whether or not the fuel cell 11 is disconnected from the system. In [S42], if the fuel cell 11 is disconnected from the system [Yes], in [S43] the water recovery operation control is stopped, and in [S44] the output suppression of the fuel cell 11 is released (that is, the self-sustaining (execute driving control). Subsequently, in [S45], the water replenishing device 17 is driven to start replenishing water to the water tank 6, and the process proceeds to the determination of [S46]. In [S42], if the fuel cell 11 has not been disconnected from the system [No], the process returns to the determination of [S42].

In [S46], it is determined whether or not the water level detection device 16 is detecting the water level, that is, whether or not the water level in the water tank 6 is equal to or higher than the first water level H. In [S46], if the water level detection device 16 detects the water level [Yes], that is, if the water level in the water tank 6 is equal to or higher than the first water level H, the process proceeds to [S47]. In [S46], if the water level detection device 16 has not detected the water level [No], that is, if the water level in the water tank 6 is less than the first water level H, the water supply device 17 is driven and waits.

In [S47], it is determined whether or not the water level detection device 16 has continuously detected the water level for the first time T1. In [S47], if the water level detection device 16 detects the water level continuously for the first time T1 [Yes], the driving of the water replenishment device 17 is stopped, and this flow chart ends. In [S47], if the water level detection device 16 has not detected the water level continuously for the first time T1 [No], the process returns to the determination of [S46]. The first time T1 can be appropriately set according to the capacity of the water tank 6, and is, for example, 30 seconds to 120 seconds.

FIG. 5 is a flowchart for explaining the transition from self-sustained operation control to normal operation control in the fuel cell device according to the embodiment. The flowchart in FIG. 5 [starts] when the fuel cell 11 is reconnected to the system.

In [S51], it is determined whether or not the water level detection device 16 has detected the water level, that is, whether or not the water level in the water tank 6 is lower than the first water level H. In [S51], if the water level detector 16 has not detected the water level [Yes], that is, if the water level in the water tank 6 is less than the first water level H, in [S52] the water supply device 17 is driven to Replenishment of water to the tank 6 is started, and the process proceeds to the judgment of [S53]. In [S51], if the water level detection device 16 detects the water level [No], that is, if the water level in the water tank 6 is equal to or higher than the first water level H, this flow chart ends.

In [S53], it is determined whether or not the water level detection device 16 is detecting the water level. In [S53], if the water level detection device 16 detects the water level [Yes], the process proceeds to the determination of [S54]. In [S53], if the water level detection device 16 has not detected the water level [No], the water supply device 17 is kept on standby.

In [S54], it is determined whether or not the water level detection device 16 has continuously detected the water level for the second time T2. In [S54], if the water level detection device 16 detects the water level continuously for the second time T2 [Yes], the driving of the water replenishment device 17 is stopped, and this flow chart ends. In [S54], if the water level detection device 16 has not detected the water level continuously for the second time T2 [No], the process returns to the determination of [S53]. The second time T2 can be appropriately set according to the capacity of the water tank 6, and is, for example, 30 seconds to 120 seconds.

6 water tank 11 fuel cell 16 water level detection device 17 water supply device 30 control device 100 fuel cell device

Claims (3)

A fuel cell device connected to a system,
a fuel cell;
a water tank for storing water collected from the exhaust gas discharged from the fuel cell to be supplied to the fuel cell;
a water level detection device that detects the water level in the water tank;
a water supply device for supplying water to the water tank from the outside;
a control device that controls the operation of the fuel cell,
The control device is
water recovery operation control for increasing the water level of the water tank by suppressing the power generation amount of the fuel cell to a first output that is less than the rated output when the water level of the water tank is detected to be less than a first water level;
a self-sustaining operation control for generating power of the first output or more by the fuel cell alone when the fuel cell is disconnected from the system,
A fuel cell device that, when disconnected from the system during execution of the water recovery operation control, stops the water recovery operation control, and executes the driving of the water supply device and the independent operation control. The control device drives the water replenishment device to perform replenishment to a water level equal to or higher than the first water level when disconnected from the system during execution of the water recovery operation control, and during execution of the independent operation control. 2. The fuel cell device according to claim 1, wherein the water recovery operation control is not executed even if the water level is detected to be less than the first water level. When the water level of the water tank is less than the first water level when reconnecting to the system, the control device drives the water replenishing device to perform replenishment to a water level equal to or higher than the first water level. 3. A fuel cell device according to claim 2.

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