JP2020202009A - Fuel cell device - Google Patents

Abstract

To provide a fuel cell device capable of suppressing the degradation in durability.SOLUTION: A fuel cell device 100 comprises: a fuel cell module 1 which generates electric power from fuel gas and air; a first heat exchanger 2; a reforming water tank 6; a water supply passage S which supplies water to the reforming water tank 6; a reforming water supply valve Vs which is provided in the water supply passage S; a low water level sensor LS1 which detects a low water level, among other water levels, in the reforming water tank 6; and a control device 30. After a water draining mode of the fuel cell device has started, the control device 30 gives a notification on an abnormality related to the water level in the reforming water tank 6 if it detects the abnormality, whereas if it does not detect the abnormality, then it intermittently drives the reforming water supply valve Vs.SELECTED DRAWING: Figure 1

Description

The present disclosure relates to a fuel cell device.

A solid oxide fuel cell (SOFC) that generates electricity using a fuel gas that is a hydrogen-containing gas and air that is an oxygen-containing gas is known. In a fuel cell device including such a fuel cell, energy is efficiently used by supplying hot water using exhaust heat generated by power generation. The fuel cell device is provided with a pipe through which a heat medium such as water flows for hot water supply. During the period when the fuel cell device is stopped, for example, when the surrounding environment becomes low temperature, the heat medium remaining in the piping may freeze. Freezing of the heat medium causes damage to the flow path and reduces the durability of the fuel cell device.

In the heat recovery system described in Patent Document 1, for the purpose of preventing freezing, in order to discharge water in the heat recovery path including the hot water storage tank, water is supplied into a closed hot water storage tank to compress the air. , The heat recovery path is opened to the atmosphere, and the water in the path is forcibly discharged by air pressure.

Japanese Unexamined Patent Publication No. 2008-2028887

In the heat recovery system of Patent Document 1, it is not considered that the water in the flow path for supplying water to the reformed water tank is discharged to prevent freezing. Therefore, freezing of the residual water may damage the flow path or reduce the durability.

The fuel cell apparatus of the present disclosure includes a fuel cell module accommodating a cell that generates power using a fuel gas and an oxygen-containing gas, a heat exchanger that exchanges heat between the exhaust gas of the fuel cell module and a heat medium, and the above. A reformed water tank that stores condensed water generated by a heat exchanger, a water supply flow path that connects a water supply source that supplies water to the reformed water tank from the outside and the reformed water tank, and the water supply flow path. It is provided with a reformed water supply valve provided in the above, a water level sensor for detecting the water level of the reformed water tank, and a control device.
When the drainage mode of the fuel cell device is executed, the control device notifies the abnormality when it detects an abnormality related to the water level of the reforming water tank, and drives the reforming water supply valve when it does not detect it. ..

According to the fuel cell device of the present disclosure, in the drainage mode, the residual amount of water in the water supply flow path can be reduced, the damage to the flow path due to freezing of water is reduced, and the durability is lowered. It can be suppressed.

It is a figure which shows the schematic structure of the fuel cell apparatus of embodiment. It is a perspective view which shows the structure of the fuel cell apparatus in an outer case. It is a schematic diagram which shows the water supply / drainage flow path of a reforming water tank. It is a part of the flowchart showing the drainage control. It is a part of the flowchart showing the drainage control.

Hereinafter, the fuel cell device according to the embodiment of the present disclosure will be described with reference to the drawings. FIG. 1 is a diagram showing a schematic configuration of the fuel cell device of the embodiment, and FIG. 2 is a perspective view showing the configuration of the fuel cell device in the outer case. FIG. 3 is a schematic view showing a water supply / drainage flow path of the reformed water tank. 4 and 5 are flowcharts showing drainage control.

The fuel cell device 100 of the embodiment is a water supply that supplies water to a fuel cell module 1 that generates power with fuel gas and air, a first heat exchanger 2, a reformed water tank 6, and a reformed water tank 6. It includes a flow path S, a reformed water supply valve Vs provided in the water supply flow path S, a low water level sensor LS1 for detecting a low water level among the water levels of the reformed water tank 6, and a control device 30. The fuel cell device 100 is configured to be able to operate by appropriately switching a plurality of types of operation modes.

The operation modes of the present embodiment include at least an operation mode for generating power, a stop mode for stopping power generation, and water supply / drainage of water as a heat medium in the reforming water tank 6 and the reforming water tank 6 for the purpose of preventing freezing. A drainage mode is included to drain the water in the flow path out of the device. The operation mode may further include a rated operation mode, a partial load operation mode, and the like.

As indicated by reference numeral HC1 in FIG. 1, the first heat is an exhaust heat recovery system having a first heat exchanger 2, a heat storage tank 3, a cooler 5, a heat medium pump P2, a circulation flow path connecting them, and the like. It has a circulation system (heat cycle). As indicated by reference numeral HC2 in FIG. 1, a second heat exchanger 4 (also referred to as a clean water heat exchanger), a circulation pump P3 for circulating a heat medium from the above-mentioned heat storage tank 3, a flow path pipe connecting these, and the like. It is provided with a second heat circulation system which is an exhaust heat recovery system having the above.

Using the high-temperature heat medium stored in the heat storage tank 3 described above, water such as tap water supplied from the outside via the supply flow path Kin was heated by the second heat exchanger 4 to be heated. Water is supplied to an external reheating device such as a water heater via the supply flow path Kout.

The fuel cell module 1 includes a fuel cell 11 and a reformer 12 housed in a storage container 10. The fuel cell 11 may be any as long as it generates electricity with fuel gas and air, and may have a cell stack structure in which a plurality of fuel cell cells are arranged, for example. The fuel cell 11 having a cell stack structure is configured by fixing the lower end of each fuel cell to a manifold with an insulating joining material such as a glass sealing material.

Further, the fuel gas and air required for power generation of the fuel cell 11 are supplied from the lower end side of the fuel cell. The fuel cells 11 are arranged in a state in which columnar fuel cell cells having a gas flow path through which gas flows along the longitudinal direction are erected, and electricity is supplied between adjacent fuel cell cells via a current collecting member. It is configured by connecting in series. Various fuel cell cells are known as the fuel cell, but when the partial load operation mode is included as the operation mode, the solid oxide fuel cell may be used.

The exhaust gas discharged from the fuel cell module 1 is heat-exchanged with a heat medium such as water or a refrigerant flowing in the first heat exchanger 2 in the first heat exchanger 2. At this time, the water contained in the exhaust gas condenses to generate condensed water. The generated condensed water is collected via the condensed water flow path C and stored in the reforming water tank 6.

The exhaust gas from which the water has been removed is exhausted to the outside of the fuel cell device via the exhaust gas flow path E. Further, the reformed water stored in the reformed water tank 6 is supplied to the reformer 12 in the fuel cell module 1 via the reformed water flow path R and the reformed water pump P1, and the steam of the raw fuel gas. Used for reforming.

The reformed water tank 6 is provided with a water level sensor for monitoring the amount of heat medium stored in the tank. The water level sensor detects a relatively high water level, which indicates the minimum amount of water required for operating the fuel cell device, a low water level sensor LS1 that detects a relatively low water level, and a full water level of the reforming water tank 6. Includes high water level sensor LS2.

The water supply flow path S includes a flow path pipe connecting the water supply source for supplying water from the outside to the reforming water tank 6 and the reforming water tank 6. At the start of operation of the fuel cell device 100, the reformed water is supplied from the water supply source to the reformed water tank 6 by using the water supply flow path S in order to reform the raw fuel gas with steam.

The water supply source may be, for example, a water supply. A water supply valve V1 is provided at the water supply source side end of the water supply flow path S. When the water supply valve V1 is opened, tap water is supplied from the water supply source water supply to the water supply flow path S, and when the water supply valve V1 is closed, the supply of tap water is stopped. In the present embodiment, the water valve V1 is opened and closed manually, and the water valve V1 is open during operation.

A reforming water supply valve Vs is provided between the reforming water tank 6 and the water supply valve V1 in the water supply flow path S. When the reformed water supply valve Vs is opened with the tap water valve V1 open, the tap water that has flowed through the water supply flow path S is supplied to the reformed water tank 6. When the reformed water supply valve Vs is closed, the flow of tap water is stopped by the reformed water supply valve Vs.

The reformed water supply valve Vs is composed of, for example, an electromagnetic valve, and is opened and closed according to an electric signal output from the control device 30. When it is not necessary to supply tap water to the reforming water tank 6 during operation, the reforming water supply valve Vs is controlled to be closed. It should be noted that driving the valve Vs means a valve opening operation, and stopping driving the valve Vs means a valve closing operation.

A tank drainage channel D is connected to the lower part of the reforming water tank 6. A tank drain valve V2 is provided at the end of the tank drainage flow path D on the opposite side of the reforming water tank 6. When the tank drain valve V2 is opened, the reformed water stored in the reformed water tank 6 is drained to the outside through the tank drain flow path D.

When the tank drain valve V2 is closed, drainage from the tank drain flow path D is stopped. In the present embodiment, the tank drain valve V2 is opened and closed manually, and the tank drain valve V2 is closed during operation.

The air used for power generation in the fuel cell module 1 is introduced into the fuel cell 11 by the air supply device 13 including the blower B2 and the pipe F which is an air flow path. The raw material fuel gas is introduced into the reformer 12 together with the reforming water passing through the reforming water flow path R via the fuel gas pump B1 and the pipe G which is the raw material fuel gas flow path.

The fuel cell device 100 may further include various configurations required for power generation, hot water supply, and the like. Each configuration shown above is an example, and is an arbitrary configuration except for the configuration required for drainage control described later.

In addition to the fuel cell module 1 and the like described above, the fuel cell device 100 includes a power conditioner 20, a control device 30, an operation board 40 including a display device and an operation panel, and the like as auxiliary machines for assisting the power generation operation thereof. The fuel cell device 100 is arranged in a case 50 including each frame 51 and each exterior panel 52, as shown in FIG. 2, for example.

Then, the fuel cell device 100 includes a control device 30 including at least one processor, a storage device, and the like in order to provide control and processing capacity for performing various functions, as described in detail below.

According to various embodiments, the at least one processor may be run as a single integrated circuit or as multiple communicable integrated and / or discrete circuits. At least one processor can be run according to a variety of known techniques.

In one embodiment, the processor comprises, for example, one or more circuits or units configured to perform one or more data calculation procedures or processes by executing instructions stored in the associated memory. In other embodiments, the processor may be firmware, eg, a discrete logic component, configured to perform one or more data computation 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 devices thereof or Any combination of configurations, or other known device and configuration combinations, 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 constituting the fuel cell device 100, and includes each of these functional units and the entire fuel cell device 100. To control and manage. The control device 30 acquires a program stored in a storage device attached to the control device 30, and executes this program to realize various functions related to each part of the fuel cell device 100.

When a control signal or various kinds of information is transmitted from the control device 30 to another functional unit or device, the control device 30 and the other functional unit may be connected by wire or wirelessly. The control characteristic of the present embodiment performed by the control device 30 will be described later. In the figure, the illustration of the connection line connecting the control device 30, each device constituting the fuel cell, and each sensor may be omitted.

A storage device (not shown) can store programs and data. The storage device may also be used as a work area for temporarily storing the processing result. The storage device includes a recording medium. The recording medium may include any non-transitory storage medium such as a semiconductor storage medium and a magnetic storage medium.

Further, the storage device may include a plurality of types of storage media. The storage device may include a combination of a portable storage medium such as a memory card, an optical disk, or a magneto-optical disk, and a storage reader. The storage device may include a storage device used as a temporary storage area such as a RAM (Random Access Memory).

The control device 30 and the storage device of the fuel cell device can also be realized as a configuration provided outside the fuel cell device 100. Further, it can be realized as a control method including a characteristic control step 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 fuel cell device 100 can execute the drainage mode after executing the stop mode to stop the power generation. The maintenance worker instructs the operation board 40 to execute the drainage mode. If the user is allowed to drain water, the water may be drained by a remote controller (not shown) provided in the user's house that communicates with the fuel cell device.

After instructing the drainage mode, the maintenance worker manually closes the water supply valve V1 and opens the tank drain valve V2. Further, the control device 30 controls the reformed water supply valve Vs based on the water level of the reformed water tank 6.

The water in the reforming water tank 6 is drained from the tank drain valve V2 via the tank drain flow path D. Further, in the water supply flow path S, the water between the reformed water supply valve Vs and the reformed water tank 6 flows into the reformed water tank 6 and drains from the tank drain valve V2 via the tank drainage flow path D. However, the water between the clean water valve V1 and the reformed water supply valve Vs is not drained because the reformed water supply valve Vs is closed and does not flow to the reformed water tank 6.

Therefore, after the drainage mode of the fuel cell device is started, the control device 30 notifies the abnormality when it detects an abnormality related to the water level of the reforming water tank 6, and when it does not detect the abnormality, the reforming water supply valve Vs. Drive to open the valve. If the valve is manually opened and closed by mistake, the water drainage does not proceed normally and an abnormality related to the water level is detected in the reforming water tank 6, so this is notified.

If no abnormality is detected, drainage is proceeding normally. Therefore, by driving the reformed water supply valve Vs to open the valve, the water remaining in the water supply flow path S is reformed. It can be drained to the water tank 6 and drained from the tank drain valve V2 via the tank drain flow path D. As a result, in the drainage mode, the residual amount of water in the water supply flow path S can be reduced, and damage to the flow path piping due to freezing can be reduced.

After driving the reforming water supply valve Vs, the reforming water pump P1 is further driven to supply the water in the reforming water flow path R to the reformer 12 to supply the reforming water flow path R. The residual amount of water in the water can be reduced, and damage to the flow path piping due to freezing can be reduced.

4 and 5 are flowcharts showing drainage control. In the flowchart, "step" is abbreviated as [S], and in the chart, "affirmation" in judgment control is represented by [YES] and "negative" is represented by [NO].

After the fuel cell device 100 executes the stop mode to stop the power generation, the maintenance worker further instructs the execution of the drainage mode to start the drainage control. If draining by the user is permitted, the draining mode may be executed according to the remote control operation of the user. After instructing the drainage mode, the maintenance worker manually closes the water supply valve V1 and opens the tank drain valve V2.

When the drainage control of the present embodiment is started, the control device 30 starts monitoring the water level in the reforming water tank 6. In the following description, the time for determining abnormality, the type of water level sensor to be used, the type of valve, and the operating time can be appropriately set according to the size of the reforming water tank 6.

In [S1], it is determined whether or not the low water level sensor LS1 of the reforming water tank 6 has detected water. When the low water level sensor LS1 detects water [YES], it is determined in [S2] whether or not the first predetermined time T1 has elapsed from the drainage instruction. If T1 has elapsed [YES], the control device 30 notifies an error in [S2] and ends the control.

Here, if the low water level sensor LS1 detects water even after the first predetermined time T1 has elapsed, the work of opening the tank drain valve V2 is not performed, the tank drain valve V2 remains closed, and the reformed water tank. It is assumed that the water is not drained from 6.

In this case, the maintenance worker may open the tank drain valve V2 and execute the drainage control from the operation board 40 again by the error notification. If [NO] does not elapse the first predetermined time T1 from the drainage instruction, the process returns to [S1] to monitor the water level. The first predetermined time T1 can be set to any time, and is, for example, 15 minutes.

When the low water level sensor LS1 does not detect water [NO], in [S4], it is determined whether or not the duration during which the low water level sensor LS1 does not continuously detect water is T2 or more for the second predetermined time.

When the duration is T2 or more [YES], the control device 30 sends an electric signal instructing to drive the valve to open the valve to the reformed water supply valve Vs in [S5], and [S6]. ], It is determined whether or not the third predetermined time T3 has elapsed since the reformed water supply valve Vs was driven.

Here, by driving (opening) the reformed water supply valve Vs, the water between the water supply valve V1 and the reformed water supply valve Vs flows into the reformed water tank 6 and is drained from the tank drain valve V2. To.

The drive of the reformed water supply valve Vs is, for example, intermittent drive. The intermittent drive operates so that the reformed water supply valve Vs repeats the open state and the closed state. For example, the open state is continued for 1 second and then the closed state is continued for 10 seconds.

In [S4], if the duration is less than T2 [NO], the process returns to [S1] to monitor the water level. The second predetermined time T2 can be set to any time having a length equal to or less than the first predetermined time T1, and is, for example, 15 minutes. The third predetermined time T3 can also be set to any time, but is, for example, 3 minutes.

If T3 has not elapsed since the reformed water supply valve Vs was opened [NO], it is determined in [S7] whether or not the low water level sensor LS1 of the reformed water tank 6 has detected water.

When the low water level sensor LS1 detects water [YES], in [S8], the control device 30 transmits an electric signal instructing to close the valve to the reformed water supply valve Vs, and in [S9], Notify an error and end control.

Here, when the low water level sensor LS1 detects water before the third predetermined time T3 elapses after driving the reformed water supply valve Vs, the reformed water is not closed without closing the water supply valve V1. It is assumed that tap water was supplied to the reforming water tank 6 from the water supply flow path S because the water supply valve Vs was opened.

In this case, the maintenance worker may close the water valve V1 by the error notification and execute the drainage control from the operation board 40 again. If the low water level sensor LS1 does not detect water [NO], the process returns to [S6] to monitor the water level.

By setting the second predetermined time T2 to a time shorter than the first predetermined time T1, the time required for draining water can be shortened. However, when the valve is manually operated as in the present embodiment, it is necessary to consider the valve operating time at the second predetermined time T2.

Since the maintenance worker operates the valve after instructing the drainage mode, the reformed water supply valve Vs opens before closing the water supply valve V1 when the valve operation time is not taken into consideration at the second predetermined time T2. This is because water flows into the reforming water tank 6.

If [YES] elapses from the third predetermined time T3 after the reformed water supply valve Vs is driven (opened), the driving of the reformed water supply valve Vs is stopped (closed) in [S10]. Further, in [S11], the control device 30 drives the reforming water pump P1 to supply the water in the reforming water flow path R to the reformer 12.

In [S12], it is determined whether or not the fourth predetermined time T4 has elapsed since the reforming water pump P1 was driven. When T4 has not elapsed since the reforming water pump P1 was driven [NO], it is determined in [S13] whether or not the reforming water pump P1 is supplying water.

In [S13], if the reforming water pump P1 is [NO] for supplying water, the process returns to [S12].

In [S12], if T4 has elapsed since the reforming water pump P1 was driven [YES], the reforming water pump P1 is stopped in [S14], and an error is notified and controlled in [S15]. To finish.

Here, in [S13], when the reforming water pump P1 does not supply water [YES], the reforming water tank 6 and the reforming water pump P1 in the reforming water flow path R The water remaining in the flow path is sent out into the flow path from the reforming water pump P1 to the reformer 12, and the water remains in the flow path between the reforming water tank 6 and the reforming water pump P1. It is assumed that the amount has decreased to less than a certain amount.

Further, in [S13], when the reforming water pump P1 is supplying water [NO], a constant amount of water is contained in the flow path between the reforming water tank 6 and the reforming water pump P1. It is assumed that the above remains. Therefore, if the reforming water pump P1 is still supplying water even after the fourth predetermined time T4 has elapsed since the reforming water pump P1 was driven ([S13] is [NO]), the reforming water It is assumed that water cannot be sent out due to a failure of the pump P1 or the tank drain valve V2 is not sufficiently opened, and the residual amount of water in the reforming water tank 6 is large.

Here, if a large amount of water in the reforming water tank 6 is supplied to the reformer 12 by draining water, deterioration of the reforming catalyst filled in the reformer 12 is expected to occur. Therefore, the fourth predetermined time T4 needs to be appropriately set according to the feeding capacity of the reforming water pump P1 and the like, and in the present embodiment, it is, for example, 2 minutes.

Whether or not the reforming water pump P1 is supplying water can be determined by detecting, for example, the driving voltage of the reforming water pump P1. Further, an acceleration sensor may be attached to the reforming water pump P1 to determine the water supply from the detected acceleration.

In [S13], when the reforming water pump P1 is not supplying water [YES], in [S16], the control device 30 drives the reforming water pump P1 a predetermined number of times or more to end the control. .. By driving the reforming water pump P1 more than a predetermined number of times, the water remaining in the reforming water flow path R from the reforming water pump P1 to the reformer 12 is supplied to the reformer 12. As a result, the amount of water remaining in the flow path is reduced.

The predetermined number of times to drive the reforming water pump P1 may be appropriately set according to the flow path volume (maximum value of the residual amount of water) from the reforming water pump P1 to the reformer 12.

By such drainage control, the water remaining in the water supply flow path S is drained from the tank drain valve V2 to reduce the residual amount of water in the water supply flow path S and remain in the reformed water flow path R. By supplying water to the reformer 12, the residual amount of water in the reforming water flow path R can be reduced.

By reducing the residual amount of water in the water supply flow path S in the drainage mode, damage to the flow path piping due to freezing can be reduced, and further, the residual amount of water in the reformed water flow path R can be reduced. By reducing the amount of water, damage to the flow path piping due to freezing can be reduced.

In the present embodiment, the case where the tank drain valve V2 is manually opened and closed has been described, but the same effect can be obtained even if the solenoid valve is opened and closed according to the electric signal output from the control device 30. Obtainable. In this case, a step [S0] for opening the tank drain valve V2 is added before [S1].

1 Fuel cell module 2 1st heat exchanger 6 Modified water tank 30 Control device 100 Fuel cell device LS1 Low water level sensor S Water supply flow path Vs Modified water water supply valve

Claims (5)

A fuel cell module that houses a cell that generates electricity using fuel gas and oxygen-containing gas,
A heat exchanger that exchanges heat between the exhaust gas of the fuel cell module and the heat medium,
A reformed water tank that stores the condensed water generated by the heat exchanger,
A water supply path connecting the water supply source for supplying water from the outside to the reformed water tank and the reformed water tank, and
The reformed water supply valve provided in the water supply flow path and
A water level sensor that detects the water level of the reformed water tank and
The control device includes a control device, and when the drainage mode of the fuel cell device is executed, the control device notifies the abnormality when it detects an abnormality related to the water level of the reforming water tank, and reforms when it does not detect it. A fuel cell device that drives a water supply valve. The control device is
When the water level of the reformed water tank is continuously detected for the first predetermined time, an abnormality is notified, and when the water level of the reformed water tank is not continuously detected for the second predetermined time, the reformed water supply valve is used. The fuel cell device according to claim 1, wherein the second predetermined time is a length equal to or less than the first predetermined time. A reformer that reforms fuel using the water in the reformed water tank,
A reformed water supply flow path connecting the reformed water tank and the reformer,
A reformed water pump provided in the reformed water supply flow path and supplying the water of the reformed water tank to the reformer is further provided.
The fuel cell device according to claim 1 or 2, wherein the control device drives the reformed water pump after a lapse of a third predetermined time after driving the reformed water supply valve. The fuel cell device according to claim 3, wherein the control device stops driving the reformed water supply valve before the reforming water pump starts driving. The fuel cell device according to claim 3 or 4, wherein the control device continuously drives a predetermined number of times or more when the reforming water pump is driven when a predetermined first condition is satisfied.