JP6904114B2 - Fuel cell system - Google Patents

Description

The present invention relates to a fuel cell system.

As a type of fuel cell system, the one shown in Patent Document 1 is known. The fuel cell system of Patent Document 1 includes a water tank for storing reformed water and a device for supplying reformed water to the fuel cell module. The device that supplies the reformed water is a plunger pump.

Japanese Unexamined Patent Publication No. 2016-72055

The plunger pump, which is a device for supplying reformed water in the above-mentioned fuel cell system, has a relatively large number of parts because of its relatively complicated configuration. Therefore, the cost of the device for supplying the reformed water and the fuel cell system becomes high. On the other hand, there is a demand for cost reduction of fuel cell systems for the purpose of improving the penetration rate.

Therefore, the present invention has been made to solve the above-mentioned problems, and an object of the present invention is to reduce the cost in a fuel cell system having a device for supplying reformed water.

In order to solve the above problems, the fuel cell system according to claim 1 includes a fuel cell that generates electricity from fuel and an oxidizing agent gas, an evaporative part that generates steam from reformed water, steam and a raw material for reforming. A reforming unit that generates fuel from the fuel and supplies the fuel to the fuel cell, a water tank that is located above the evaporation unit and stores the reformed water inside, and a water tank and the evaporation unit are connected and reformed. A water flow pipe in which water flows toward the evaporation part, a pressurizing device that draws reformed water to the water flow pipe by feeding gas into the water tank and pressurizing the inside of the water tank, and water. An electromagnetic valve that is placed in the flow pipe and allows the flow of reformed water when it is open and regulates the flow of reformed water when it is closed, and a water level detector that detects the water level in the water tank. , A fuel cell system including at least a control device for controlling the fuel cell, wherein the control device includes a lead-out unit for deriving a driving amount of the pressurizing device according to the amount of power generated by the fuel cell, and a water level detecting device. Using the water level of the water tank detected by, the correction unit that corrects the drive amount of the pressurizing device derived by the lead-out unit and the pressurizing device with the drive amount of the pressurizing device corrected by the correction unit. It is provided with a reformed water supply unit that supplies reformed water from the water tank to the evaporation unit by driving and opening the electromagnetic valve.

According to this, the solenoid valve is opened and the gas is sent into the water tank by the pressurizing device, so that the reformed water is supplied to the evaporation part through the water flow pipe. That is, the device for supplying the reforming water of the present invention is composed of a solenoid valve and a pressurizing device provided so as to be able to deliver gas. Therefore, the apparatus for supplying the reforming water of the present invention can be simplified in configuration as compared with the plunger pump of the prior art, so that the number of parts can be suppressed. Therefore, it is possible to reduce the cost of the device for supplying the reformed water and thus the fuel cell system.

It is a schematic diagram which shows one Embodiment of the fuel cell system by this invention. It is a block diagram of the fuel cell system shown in FIG. It is a third map stored in the storage unit shown in FIG. 2, and shows the correlation between the detected water level detected by the water level detecting device and the first correction coefficient. It is a fourth map stored in the storage unit shown in FIG. 2, and shows the correlation between the detected temperature detected by the temperature sensor and the second correction coefficient. It is a fifth map stored in the storage unit shown in FIG. 2, and shows the correlation between the measurement drive time measured by the measuring device and the third correction coefficient. It is a flowchart of water supply control executed by the control device shown in FIG. It is a flowchart of the water supply control executed by the control device shown in FIG.

Hereinafter, an embodiment of the fuel cell system according to the present invention will be described with reference to the drawings. In this specification, for convenience of explanation, the upper side and the lower side in FIG. 1 will be described as the upper side and the lower side of the fuel cell system 1, respectively, and the left side and the right side will be described as the left side and the right side of the fuel cell system 1, respectively.

As shown in FIG. 1, the fuel cell system 1 includes a main body 10 and a hot water storage tank 21. The main body 10 includes a housing 10a, a fuel cell module 11 (30), a heat exchanger 12, a power conversion device 13, a water tank 14, and a control device 15. The fuel cell module 11 includes at least a fuel cell 34, which will be described later.

The heat exchanger 12 is a heat exchanger in which combustion exhaust gas (described later) exhausted from the fuel cell module 11 is supplied, hot water is supplied from the hot water storage tank 21, and the combustion exhaust gas and hot water are exchanged for heat. is there.

An exhaust pipe 11d from the fuel cell module 11 is connected (penetrated) to the heat exchanger 12. The heat exchanger 12 is connected to a condensed water supply pipe 12a connected to a water tank 14 described later. Further, the heat exchanger 12 is arranged above the water tank 14.

The hot water storage tank 21 stores hot water, and a hot water storage water circulation line 22 through which the hot water is circulated (circulated in the direction of the arrow in the figure) is connected. On the hot water storage water circulation line 22, the hot water storage water circulation pump 22a and the heat exchanger 12 are arranged in order from the lower end to the upper end.

In the heat exchanger 12, the combustion exhaust gas from the fuel cell module 11 is introduced into the heat exchanger 12 through the exhaust pipe 11d, and heat is exchanged with the hot water to be cooled and the combustion exhaust gas is cooled. The water vapor contained in it is condensed. The flue gas after cooling is discharged to the outside through the exhaust pipe 11d. Further, the condensed condensed water is replenished as reformed water to the water tank 14 described later through the condensed water supply pipe 12a by the water replenishment control described later.

One end (upper end) of the condensed water supply pipe 12a is connected to the heat exchanger 12, and the other end (lower end) of the condensed water supply pipe 12a is connected to the water tank 14. A water purification unit 12a1 and a first solenoid valve 12a2 are arranged in the condensed water supply pipe 12a. The water purification unit 12a1 is arranged in the condensed water supply pipe 12a and purifies water with an ion exchange resin.

The first solenoid valve 12a2 is arranged in the condensed water supply pipe 12a, allows the flow of condensed water when it is in the open state, and regulates the flow of condensed water when it is in the closed state. The first solenoid valve 12a2 is a normally closed type solenoid valve. The first solenoid valve 12a2 is in the open state when it is energized, and is in the closed state when it is not energized. The first solenoid valve 12a2 is switched between an open state and a closed state by switching between an energized state and a non-energized state by a control command from the control device 15.

The waste heat recovery system 20 is configured from the heat exchanger 12, the hot water storage tank 21, and the hot water storage water circulation line 22 described above. The waste heat recovery system 20 collects and stores the waste heat of the fuel cell module 11 in the hot water storage water.

Further, the power conversion device 13 inputs a DC voltage output from the fuel cell 34, converts it into a predetermined AC voltage, and is connected to an AC system power supply 16a and an external power load 16c (for example, an electric appliance). Output to line 16b.

Further, the power conversion device 13 inputs the AC voltage from the system power supply 16a via the power supply line 16b, converts it into a predetermined DC voltage, and outputs it to the auxiliary machine or the control device 15.

The control device 15 controls at least the fuel cell 34. The control device 15 drives an auxiliary machine (pump or blower) to control the operation of the fuel cell system 1. The control device 15 controls the generated power of the fuel cell 34 so as to consume the external power load 16c during the power generation operation of the fuel cell system 1 (load follow-up operation).

The fuel cell module 11 (30) is a solid oxide fuel cell module. The fuel cell module 30 includes a casing 31, an evaporation unit 32, a reforming unit 33, and a fuel cell 34. The casing 31 is made of a heat insulating material and is formed in a box shape.

In the fuel cell module 30, one end is connected to the supply source Gs and the other end of the reforming raw material supply pipe 11a to which the reforming raw material is supplied is connected to the evaporation unit 32. Examples of the reforming raw material include natural gas (methane gas), city gas, reforming gas fuel such as LPG (liquefied petroleum gas), and reforming liquid fuel such as kerosene, gasoline, and methanol. The supply sources Gs are, for example, a gas supply pipe for city gas and a gas cylinder for LP gas. The raw material supply pipe 11a for reforming is provided with a raw material pump 11a1. The raw material pump 11a1 is a pump that sends a reforming raw material.

Further, one end (upper end) of the evaporation unit 32 is connected to the water tank 14, and the other end of the water flow pipe 11b to which reformed water is supplied is connected.

The water tank 14 is arranged above the evaporation unit 32 and stores the reformed water inside. The water tank 14 is provided so as to lead the reformed water to the water flow pipe 11b by pressurizing the inside by the pressurizing device 14b described later. Specifically, the water tank 14 is formed in a box shape and stores reformed water in a closed state.

The water flow pipe 11b is a pipe that connects the water tank 14 and the evaporation unit 32 and allows the reformed water to flow toward the evaporation unit 32. One end (upper end) of the water tank 14 is connected to the bottom of the water tank 14. The position of the connection portion of the water flow pipe 11b with the water tank 14 is located above the position of the connection portion of the water flow pipe 11b with the evaporation portion 32. A regulation unit 11b1 and a second solenoid valve 11b2 (corresponding to the solenoid valve of the present invention) are arranged in the water flow pipe 11b.

The regulating unit 11b1 is arranged between the water tank 14 and the second solenoid valve 11b2, and regulates the flow of the fluid from the second solenoid valve 11b2 toward the water tank 14. Specifically, the regulation unit 11b1 is a U-shaped portion where the water flow pipe 11b opens upward. By collecting the reformed water in the lower part of the regulating section 11b1, the flow of the fluid (for example, the reformed water, the steam in the evaporation section 32 and the reforming raw material) from the second solenoid valve 11b2 to the water tank 14 is regulated. To.

The second solenoid valve 11b2 is arranged in the water flow pipe 11b to allow the flow of reformed water when it is in the open state and regulate the flow of reformed water when it is in the closed state. The second solenoid valve 11b2 is a normally closed type solenoid valve. The second solenoid valve 11b2 is in the open state when it is energized, and is in the closed state when it is not energized. The second solenoid valve 11b2 is switched between an open state and a closed state by switching between an energized state and a non-energized state by a control command from the control device 15.

Further, a water level detecting device 14a and a pressurizing device 14b are arranged in the water tank 14.
The water level detecting device 14a detects the water level of the water tank 14. The water level detection device 14a is a capacitance type water level sensor in the present embodiment. The water level of the water tank 14 detected by the water level detection device 14a is output to the control device 15 as a detection signal.

The pressurizing device 14b sends gas into the water tank 14 to pressurize the inside of the water tank 14. The gas is the air inside the housing 10a. The pressurizing device 14b is a pressurizing pump that sends out air by rotationally driving in the first direction. The pressurizing device 14b and the water tank 14 are connected via an air flow pipe 14b1. When the pressurizing device 14b is rotationally driven in the first direction, the air in the housing 10a is sent into the water tank 14 via the air flow pipe 14b1, and the pressure inside the water tank 14 increases.

By pressurizing the inside of the water tank 14 in this way, the reformed water is led out to the water flow pipe 11b toward the evaporation unit 32. Further, since the water tank 14 is arranged above the evaporation section 32, the reforming water is led out to the water flow pipe 11b toward the evaporation section 32 by the weight of the reforming water in the water tank 14 (details). Will be described later).

Further, the pressurizing device 14b is provided so as to rotationally drive in the second direction opposite to the first direction. When the pressurizing device 14b is rotationally driven in the second direction, the air inside the water tank 14 is led out to the outside of the water tank 14 via the air flow pipe 14b1, and the pressure inside the water tank 14 is reduced.

The evaporation unit 32 generates steam from the reformed water. The evaporating unit 32 is heated by the combustion gas described later to evaporate the reformed water to generate steam (steam for reforming). Further, the evaporation unit 32 preheats the reforming raw material. The evaporation unit 32 mixes the steam generated by evaporating the condensed water (reforming steam) and the preheated reforming raw material and leads them out to the reforming unit 33.

The reforming unit 33 generates fuel from steam and a reforming raw material, and supplies the fuel to the fuel cell 34. The fuel is a reformed gas in which the reforming raw material is reformed. Specifically, the reforming unit 33 is heated by the combustion gas described later and is supplied with the heat required for the steam reforming reaction, so that the mixed gas (raw material for reforming, steam) supplied from the evaporating unit 32 is supplied. ) To generate reformed gas and derive it.

The reforming section 33 is filled with a catalyst (for example, a Ru or Ni-based catalyst), and the mixed gas reacts with the catalyst and is reformed to produce a reformed gas containing hydrogen gas, carbon monoxide, and the like. It is produced (so-called steam reforming reaction). The reformed gas includes hydrogen, carbon monoxide, carbon dioxide, steam, unreformed natural gas (methane gas), and reformed water (steam) that was not used for reforming. The steam reforming reaction is an endothermic reaction.

The fuel cell 34 generates electricity using fuel (reforming gas) and oxidant gas. The fuel cell 34 is configured by stacking a plurality of cells 34a composed of a fuel electrode, an air electrode (oxidizing agent electrode), and an electrolyte interposed between the two electrodes. The fuel cell 34 of the present embodiment is a solid oxide fuel cell, and uses zirconium oxide, which is a kind of solid oxide, as an electrolyte.

A reformed gas (hydrogen, carbon monoxide, methane gas, etc.) is supplied as fuel to the fuel electrode of the fuel cell 34. A fuel flow path 34b through which fuel (reformed gas) flows is formed on the fuel electrode side of the cell 34a. An air flow path 34c through which air (cathode air), which is an oxidant gas, flows is formed on the air electrode side of the cell 34a. The fuel cell 34 generates electricity at a relatively high operating temperature (about 700 ° C.).

The fuel cell 34 is provided on the manifold 35. The reformed gas from the reforming section 33 is supplied to the manifold 35 via the reforming gas supply pipe 38. The lower end (one end) of the fuel flow path 34b is connected to the fuel outlet (not shown) of the manifold 35 so that the reformed gas derived from the fuel outlet is introduced from the lower end and led out from the upper end. It has become.

The air in the housing 10a is supplied into the fuel cell module 30 as an oxidant gas (cathode air) by being sent out by the cathode air blower 11c1 via the cathode air supply pipe 11c. This oxidant gas is introduced from the lower end of the air flow path 34c and led out from the upper end.

Further, a combustion unit 36 is provided between the fuel cell 34, the evaporation unit 32, and the reforming unit 33. In the combustion unit 36, the anode off gas (fuel off gas) from the fuel cell 34 and the cathode off gas (oxidizer off gas) from the fuel cell 34 are burned to generate combustion gas (flame 37). The combustion gas heats the evaporation unit 32 and the reforming unit 33.

In the combustion unit 36, the anode off gas is burned to generate a relatively high temperature combustion exhaust gas. The relatively high temperature combustion exhaust gas is led out to the heat exchanger 12. Further, the combustion unit 36 sets the temperature inside the fuel cell module 30 as the operating temperature of the fuel cell 34.

Further, the fuel cell system 1 further includes a current detecting device 40, a temperature sensor 50, and a measuring device 60.

The current detection device 40 detects the current value of the electric power output from the fuel cell 34. The current detection device 40 is arranged in the power conversion device 13. The detected current value, which is the current value detected by the current detecting device 40, is output to the control device 15.

The temperature sensor 50 detects the temperature of the pressurizing device 14b. The temperature sensor 50 is arranged at a predetermined position on the outer shell of the pressurizing device 14b. The temperature sensor 50 detects the temperature at a predetermined position. The predetermined position is a position where the temperature of the drive unit (not shown) that is rotationally driven in the pressurizing device 14b can be detected. The detected temperature, which is the temperature detected by the temperature sensor 50, is output to the control device 15.

The measuring device 60 measures the driving time of the pressurizing device 14b. The measuring device 60 measures the time when the electric power for driving the pressurizing device 14b from the power conversion device 13 is supplied to the pressurizing device 14b as the driving time of the pressurizing device 14b. The driving time of the pressurizing device 14b is measured with the time when the fuel cell system 1 is installed as zero. The measuring device 60 is arranged in the power conversion device 13. The measured drive time, which is the drive time measured by the measuring device 60, is output to the control device 15.

Further, as shown in FIG. 2, the control device 15 includes a water supply control unit 15a and a water supply control unit 15b. The water supply control unit 15a executes water supply control for supplying reformed water from the water tank 14 to the evaporation unit 32 during the power generation operation of the fuel cell system 1 (details will be described later). The water replenishment control unit 15b executes water replenishment control for replenishing the water tank 14 with condensed water as reformed water (details will be described later).

The water supply control unit 15a includes a setting unit 15a1, a lead-out unit 15a2, a correction unit 15a3, a storage unit 15a4, and a reforming water supply unit 15a5.

The setting unit 15a1 sets a target flow rate, which is a target flow rate of the reforming water. The setting unit 15a1 sets a target flow rate according to the amount of power generated by the fuel cell 34 during the power generation operation of the fuel cell system 1 in which the fuel cell 34 generates power.

Specifically, the setting unit 15a1 sets a target flow rate corresponding to the detected current value detected by the current detecting device 40 by using the first map (not shown). The first map shows the correlation that the target flow rate of reformed water increases as the detected current value increases.

The lead-out unit 15a2 derives the first drive amount (corresponding to the drive amount of the present invention) of the pressurizing device 14b according to the power generation amount of the fuel cell 34. The first drive amount is a drive amount when the pressurizing device 14b is rotationally driven in the first direction. Specifically, the derivation unit 15a2 derives the first drive amount corresponding to the target flow rate set by the setting unit 15a1 using the second map (not shown). The second map shows the correlation that the first drive amount increases as the target flow rate increases.

The correction unit 15a3 uses the water level of the water tank 14 detected by the water level detection device 14a (hereinafter, also referred to as a detected water level) to correct the first drive amount of the pressurizing device 14b led out by the lead-out unit 15a2. Is what you do. Specifically, the correction unit 15a3 corrects by multiplying the first drive amount of the pressurizing device 14b led out by the lead-out unit 15a2 by the first correction coefficient C1.

The correction unit 15a3 derives the first correction coefficient C1 corresponding to the first drive amount of the pressurizing device 14b derived by the out-licensing unit 15a2 using the third map M3 (see FIG. 3). The third map M3 shows a correlation in which the first correction coefficient C1 decreases as the detected water level increases. The first correction coefficient C1 is set to be "1" when the detected water level is the reference water level H0 (zero in the present embodiment).

As described above, the reformed water in the water tank 14 is led out to the water flow pipe 11b by the drive of the pressurizing device 14b and the weight of the reformed water in the water tank 14. As the water level in the water tank 14 rises, the weight of the reformed water in the water tank 14 increases, so that the flow rate of the reformed water led out to the water flow pipe 11b is increased by the weight of the reformed water in the water tank 14. To increase. On the other hand, the flow rate of the reforming water led out from the water tank 14 to the water flow pipe 11b by the weight of the reforming water in the water tank 14 for the first drive amount of the pressurizing device 14b led out by the lead-out unit 15a2. The first correction coefficient C1 is set so as to reduce the amount corresponding to.

Further, the correction unit 15a3 derives using the temperature detected by the temperature sensor 50 (hereinafter, also referred to as the detected temperature) and the driving time measured by the measuring device 60 (hereinafter, also referred to as the measurement driving time). The first drive amount of the pressurizing device 14b led out by the unit 15a2 is further corrected. Specifically, the correction unit 15a3 corrects by further multiplying the first drive amount derived by the out-licensing unit 15a2 by not only the first correction coefficient C1 but also the second correction coefficient C2 and the third correction coefficient C3. To do.

The correction unit 15a3 derives the second correction coefficient C2 corresponding to the detected temperature using the fourth map M4 (see FIG. 4). The fourth map M4 shows a correlation in which the second correction coefficient C2 decreases as the detection temperature increases. The second correction coefficient C2 is set to be "1" when the detection temperature is the reference temperature Th0 (for example, 20 ° C.).

As the temperature of the pressurizing device 14b increases, the resistance to the drive of the pressurizing device 14b generated by the lubricant (for example, grease) of the pressurizing device 14b decreases. The actual drive amount of the corresponding pressurizing device 14b increases.

On the other hand, the first drive amount derived by the lead-out unit 15a2 is increased or decreased by the amount corresponding to the fluctuation of the actual drive amount of the pressurizing device 14b due to the temperature change from the reference temperature Th0. (2) The correction coefficient C2 is set. In other words, the first drive amount is corrected by the second correction coefficient C2 so that the actual drive amount of the pressurizing device 14b becomes the drive amount corresponding to the case where the detection temperature is the reference temperature Th0.

The correction unit 15a3 derives a third correction coefficient C3 corresponding to the measurement drive time using the fifth map M5 (see FIG. 5). The fifth map M5 shows a correlation in which the third correction coefficient C3 increases as the measurement drive time increases. The third correction coefficient C3 is set to be "1" when the measurement drive time is the reference measurement drive time Tm0 (zero in the present embodiment).

As the drive time of the pressurizing device 14b becomes longer, the aging of the pressurizing device 14b progresses, so that the actual driving amount of the pressurizing device 14b corresponding to the first driving amount led out by the out-licensing unit 15a2 decreases. To do. On the other hand, the third correction is made so that the first drive amount derived by the out-licensing unit 15a2 is increased by the amount corresponding to the decrease in the actual drive amount of the pressurizing device 14b due to the aging of the pressurizing device 14b. The coefficient C3 is set. In other words, the first drive amount is corrected by the third correction coefficient C3 so that the actual drive amount of the pressurizing device 14b becomes the drive amount corresponding to the case where the drive time of the pressurizing device 14b is zero. To.

The storage unit 15a4 stores data and the like used when executing the program. The storage unit 15a4 stores the first map to the fifth map M5. The first map to the fifth map M5 are actually measured and derived by experiments in advance. The environmental temperature when this experiment is performed is the reference temperature Th0.

The reforming water supply unit 15a5 is modified by driving the pressurizing device 14b with the first drive amount of the pressurizing device 14b corrected by the correction unit 15a3 and opening the second solenoid valve 11b2. The quality water is supplied from the water tank 14 to the evaporation unit 32. The reforming water supply unit 15a5 outputs the first drive amount corrected by the correction unit 15a3 to the pressurizing device 14b as a control command value. Further, the reforming water supply unit 15a5 outputs a control command value for opening the second solenoid valve 11b2 to the second solenoid valve 11b2.

The water supply control unit 15b includes a water level determination unit 15b1 and a reformed water supply unit 15b2.
The water level determination unit 15b1 uses the water level of the water tank 14 detected by the water level detection device 14a to determine whether or not the water level of the water tank 14 is equal to or lower than the first predetermined water level. The first predetermined water level is set to the water level of the water tank 14 when the amount of reformed water inside the water tank 14 is a predetermined amount. The predetermined amount is the amount of reformed water required for the power generation of the fuel cell 34 to continue for a predetermined time (for example, 24 hours). The determination result of the water level determination unit 15b1 is output to the reformed water supply unit 15b2.

Further, the water level determination unit 15b1 uses the water level of the water tank 14 detected by the water level detection device 14a to determine whether or not the water level of the water tank 14 is equal to or higher than the second predetermined water level. The second predetermined water level is the water level of the water tank 14 higher than the first predetermined water level. Specifically, the second predetermined water level is set at a position slightly lower than the upper surface in the water tank 14.

The reformed water supply unit 15b2 replenishes the water tank 14 with reformed water when the water level determination unit 15b1 determines that the water level of the water tank 14 is equal to or lower than the first predetermined water level. In this case, the reforming water supply unit 15b2 specifically outputs a control command value for opening the first solenoid valve 12a2 to the first solenoid valve 12a2.

Further, in this case, the reforming water supply unit 15b2 outputs the second drive amount of the pressurizing device 14b to the pressurizing device 14b as a control command value. The second drive amount is the drive amount of the pressurizing device 14b when the pressurizing device 14b is rotationally driven in the second direction. The rotation speed of the second drive amount is set to be constant at a predetermined rotation speed. The predetermined rotation speed is the rotation speed required to make the inside of the water tank 14 negative pressure with respect to the atmospheric pressure.

Further, the reformed water supply unit 15b2 stops replenishing the reformed water to the water tank 14 when the water level determination unit 15b1 determines that the water level of the water tank 14 is equal to or higher than the second predetermined water level. In this case, the reforming water replenishment unit 15b2 specifically outputs a control command value for closing the first solenoid valve 12a2 to the first solenoid valve 12a2. Further, in this case, the reforming water supply unit 15b2 outputs a control command value for setting the second drive amount of the pressurizing device 14b to zero to the pressurizing device 14b.

Next, the water supply control executed by the control device 15 will be described with reference to the flowchart shown in FIG. The water supply control is executed when the fuel cell system 1 is in power generation operation.

In step S102, the control device 15 sets a target flow rate according to the amount of power generated by the fuel cell 34 (setting unit 15a1). Subsequently, the control device 15 derives the first drive amount of the pressurizing device 14b corresponding to the target flow rate in step S104 (out-out unit 15a2).

Then, in step S106, the control device 15 corrects the first drive amount of the pressurizing device 14b using the detected water level (correction unit 15a3). As a result, the first drive amount is corrected so as to be reduced by the weight of the reforming water in the water tank 14 by the amount corresponding to the flow rate of the reforming water led out from the water tank 14 to the water flow pipe 11b.

Further, the control device 15 corrects the first drive amount of the pressurizing device 14b by using the detected temperature in step S108 (correction unit 15a3). As a result, the first drive amount is corrected so as to increase or decrease by the amount corresponding to the fluctuation of the actual drive amount of the pressurizing device 14b due to the temperature change from the reference temperature Th0.

Further, the control device 15 corrects the first drive amount of the pressurizing device 14b by using the measurement drive time in step S110 (correction unit 15a3). As a result, the first drive amount is corrected so as to increase by the amount corresponding to the decrease in the actual drive amount of the pressurizing device 14b due to the aging of the pressurizing device 14b.

Then, in step S112, the control device 15 drives the pressurizing device 14b with the corrected first drive amount (modified water supply unit 15a5). Further, the control device 15 opens the second solenoid valve 11b2 in step S114 (reforming water supply unit 15a5). At this time, the reformed water is led out from the water tank 14 to the water flow pipe 11b by the drive of the pressurizing device 14b and the weight of the reformed water in the water tank 14, and passes through the water flow pipe 11b to the evaporation unit 32. Be supplied.

Further, at this time, the first flow rate Q1 of the reforming water supplied to the evaporating unit 32 is the second flow rate Q2 of the reforming water corresponding to the corrected first driving amount and the reforming water in the water tank 14. It is a flow rate including the third flow rate Q3 of the reformed water led out to the water flow pipe 11b by the weight of (Q1 = Q2 + Q3).

Here, the second flow rate Q2 of the reforming water corresponding to the corrected driving amount is determined by the weight of the reforming water in the water tank 14 from the target flow rate of the reforming water corresponding to the driving amount before the correction. It is a flow rate reduced by the third flow rate Q3 of the reforming water led out to the water flow pipe 11b (Q2 = target flow rate −Q3). Therefore, the first flow rate Q1 of the reforming water supplied to the evaporation unit 32 corresponds to the target flow rate (Q1 = Q2 + Q3 = (target flow rate −Q3) + Q3 = target flow rate).

Next, the water supply control executed by the control device 15 will be described with reference to the flowchart shown in FIG. The water supply control is executed when the fuel cell system 1 is activated.

In step S202, the control device 15 determines whether or not the detected water level is equal to or lower than the first predetermined water level (water level determination unit 15b1). If the water level of the water tank 14 is relatively high, or if the detected water level is higher than the first predetermined water level, the control device 15 determines "NO" in step S202, and repeats step S202.

On the other hand, when the reformed water in the water tank 14 is used for power generation and the water level in the water tank 14 drops and the detected water level becomes equal to or lower than the first predetermined water level, the control device 15 moves to step S202. The result is determined as "YES", and the program proceeds to step S204.

Then, the control device 15 drives the pressurizing device 14b with the second drive amount in step S204 (reforming water replenishment unit 15b2), and opens the first solenoid valve 12a2 in step S206 (reformation). Water supply unit 15b2). At this time, since the pressure inside the water tank 14 becomes negative, the condensed water falls from the heat exchanger through the condensed water supply pipe 12a by its own weight and is replenished to the water tank 14 as reformed water. .. As a result, the water level of the water tank 14 rises.

Subsequently, in step S208, the control device 15 determines whether or not the detected water level is equal to or higher than the second predetermined water level (water level determination unit 15b1). When the water level of the water tank 14 is relatively low because the replenishment of the reformed water to the water tank 14 has been started for a relatively short time, the detected water level is lower than the second predetermined water level. In this case, the control device 15 determines "NO" in step S208, and repeats step S208.

On the other hand, when the water level of the water tank 14 rises and the detected water level becomes equal to or higher than the second predetermined water level, the control device 15 determines "YES" in step S208 and advances the program to step S210. The control device 15 stops driving the pressurizing device 14b in step S210, and closes the first solenoid valve 12a2 in step S212 (reforming water supply unit 15b2). As a result, the replenishment of reformed water is stopped.

According to the present embodiment, the fuel cell system 1 uses fuel from a fuel cell 34 that generates power from fuel and an oxidizing agent gas, an evaporating unit 32 that generates steam from reformed water, and steam and a raw material for reforming. A reforming unit that generates and supplies fuel to the fuel cell 34, a water tank 14 that is arranged above the evaporation unit 32 and stores reformed water inside, and the water tank 14 and the evaporation unit 32 are connected to each other. The reformed water is led out to the water flow pipe 11b by feeding the gas into the water flow pipe 11b through which the reformed water flows toward the evaporation section 32 and the inside of the water tank 14 to pressurize the inside of the water tank 14. The pressurizing device 14b and the second electromagnetic valve 11b2, which are arranged in the water flow pipe 11b and allow the flow of reforming water when it is in the open state and regulate the flow of reforming water when it is in the closed state. A water level detecting device 14a for detecting the water level of the water tank 14 and a control device 15 for controlling at least the fuel cell 34 are provided. The control device 15 uses the lead-out unit 15a2 for deriving the first drive amount of the pressurizing device 14b according to the power generation amount of the fuel cell 34 and the water level of the water tank 14 detected by the water level detection device 14a. The pressurizing device 14b is driven by the correction unit 15a3 that corrects the first drive amount of the pressurizing device 14b led out by the lead-out unit 15a2 and the first drive amount of the pressurizing device 14b corrected by the correction unit 15a3. Further, by opening the second electromagnetic valve 11b2, the reforming water supply unit 15a5 for supplying the reforming water from the water tank 14 to the evaporation unit 32 is provided.

According to this, the second solenoid valve 11b2 is opened, and the gas is sent into the water tank 14 by the pressurizing device 14b, so that the reformed water evaporates through the water flow pipe 11b. It is supplied to 32. That is, the device for supplying the reforming water of the present invention is composed of the second solenoid valve 11b2 and the pressurizing device 14b provided so as to be able to deliver the gas. Therefore, the apparatus for supplying the reforming water of the present invention can be simplified in configuration as compared with the plunger pump of the prior art, so that the number of parts can be suppressed. Therefore, the cost of the device for supplying the reformed water and the fuel cell system 1 can be reduced.

Further, the reformed water is led out from the water tank 14 to the water flow pipe 11b by driving the pressurizing device 14b and the weight of the reformed water in the water tank 14. Then, as the water level of the water tank 14 rises, the flow rate of the reforming water led out from the water tank 14 to the water flow pipe 11b increases due to the weight of the reforming water in the water tank 14. On the other hand, in the control device 15, the pressurizing device 14b increases as the water level of the reforming water detected by the water level detecting device 14a increases, that is, as the weight of the reforming water in the water tank 14 increases. The first drive amount of is corrected so as to be small. Therefore, the fuel cell system 1 can improve the accuracy of the flow rate of the reformed water. Therefore, it is possible to achieve both high accuracy of the flow rate of the reforming water supplied to the evaporation unit 32 and reduction of the cost of the pressurizing device 14b.

Further, the fuel cell system 1 further includes a temperature sensor 50 that detects the temperature of the pressurizing device 14b, and a measuring device 60 that measures the driving time of the pressurizing device 14b. The correction unit 15a3 further corrects the first drive amount of the pressurizing device 14b led out by the lead-out unit 15a2 by using the temperature detected by the temperature sensor 50 and the drive time driven by the measuring device 60.

As the temperature of the pressurizing device 14b increases, the resistance to the drive of the pressurizing device 14b caused by the lubricant of the pressurizing device 14b decreases, so that the actual pressurizing device 14b with respect to the first drive amount of the pressurizing device 14b Drive amount increases. Further, as the driving time of the pressurizing device 14b increases, the aging of the pressurizing device 14b progresses, so that the actual driving amount of the pressurizing device 14b with respect to the first driving amount of the pressurizing device 14b decreases. On the other hand, the correction unit 15a3 corrects the first drive amount of the pressurizing device 14b by using the temperature of the pressurizing device 14b and the driving time of the pressurizing device 14b. Therefore, the fuel cell system 1 can further improve the accuracy of the flow rate of the reformed water supplied to the evaporation unit 32.

Further, the water flow pipe 11b is arranged between the water tank 14 and the second solenoid valve 11b2, and further includes a regulation unit 11b1 that regulates the flow of fluid from the second solenoid valve 11b2 to the water tank 14. ..

According to this, since the flow of the fluid from the second solenoid valve 11b2 to the water tank 14 is regulated by the regulation unit 11b1, the reformed water can be reliably supplied to the evaporation unit 32. Therefore, the fuel cell system 1 can further improve the accuracy of the flow rate of the reformed water supplied to the evaporation unit 32. Further, it is possible to regulate the inflow of steam and the reforming raw material into the water tank 14.

Further, since the reforming water is accumulated in the regulation unit 11b1, the fluid evaporates in the evaporation unit 32 (even when the fuel cell system 1 in which the supply of the reforming water from the water tank 14 is stopped is stopped. Backflow from the fuel cell module 11) to the water tank 14 is suppressed. Further, the regulation unit 11b1 is arranged at a position closer to the evaporation unit 32 than the water tank 14. Therefore, the reformed water stored in the regulating section 11b1 is supplied to the evaporation section 32 in a shorter time than the reformed water in the water tank 14. Therefore, it is possible to shorten the preparation time for supplying the reformed water in the start-up operation of the fuel cell system 1. Therefore, it is possible to shorten the time from the stopped state of the fuel cell system 1 to the start of the power generation operation.

Although an example of the fuel cell system has been shown in the above-described embodiment, the present invention is not limited to this, and other configurations may be adopted. For example, in the above-described embodiment, the gas sent into the water tank 14 is air, but instead of this, an inert gas such as nitrogen or argon may be used.

Further, in the above-described embodiment, the water level detection device 14a is of the capacitance type, but instead of this, the water level detection device 14a may be of the float type.

Further, in the above-described embodiment, the fuel cell system 1 includes both the temperature sensor 50 and the measuring device 60, but instead, the fuel cell system 1 may not include both the temperature sensor 50 and the measuring device 60. good. In this case, the correction unit 15a3 corrects the first drive amount of the pressurizing device 14b by using only the detected water level.

Further, in the above-described embodiment, the fuel cell system 1 includes both the temperature sensor 50 and the measuring device 60, but instead of the fuel cell system 1, one of the temperature sensor 50 and the measuring device 60 may be provided. .. In this case, the correction unit 15a3 corrects the first drive amount of the pressurizing device 14b by using one of the detected temperature and the measurement drive time, and the detected water level.

Further, in the above-described embodiment, the regulation unit 11b1 is provided by forming the water flow pipe 11b in a U shape that opens upward, but instead, the water flow pipe 11b is provided in the water tank 14. The regulating portion 11b1 may be provided by inclining from the upper side to the lower side toward the second solenoid valve 11b2 side from the side.

Further, in the above-described embodiment, the fuel cell 34 is a solid oxide fuel cell, but a solid polymer fuel cell may be used instead.

Further, the shapes of the water flow pipe 11b and the regulation unit 11b1, the arrangement positions of the water tank 14 and the heat exchanger 12, and the type of the water level detection device 14a may be changed without departing from the gist of the present invention. good.

1 ... Fuel cell system, 11 (30) ... Fuel cell module, 11b ... Water flow pipe, 11b1 ... Regulatory part, 11b2 ... Second electromagnetic valve (electromagnetic valve), 12 ... Heat exchanger, 12a ... Condensed water supply pipe, 12a2 ... First electromagnetic valve, 13 ... Power conversion device, 14 ... Water tank, 14a ... Water level detector, 14b ... Pressurizing device, 14b1 ... Air flow pipe, 15 ... Control device, 15a ... Water supply control unit, 15a1 ... Setting unit, 15a2 ... Derivation unit, 15a3 ... Correction unit, 15a4 ... Storage unit, 15a5 ... Modified water supply unit, 15b ... Water supply control unit, 15b1 ... Water level determination unit, 15b2 ... Modified water supply unit, 32 ... Evaporation Part, 33 ... reforming part, 34 ... fuel cell, 50 ... temperature sensor, 60 ... measuring device.

Claims (3)

Fuel cells that generate electricity from fuel and oxidant gas,
The evaporation part that generates steam from the reformed water and
A reforming unit that generates the fuel from the steam and the reforming raw material and supplies the fuel to the fuel cell.
A water tank that is arranged above the evaporation section and stores the reformed water inside,
A water flow pipe that connects the water tank and the evaporation section and allows the reformed water to flow toward the evaporation section.
A pressurizing device that draws out the reformed water to the water flow pipe by feeding gas into the water tank and pressurizing the inside of the water tank.
A solenoid valve arranged in the water flow pipe that allows the flow of the reformed water when it is in the open state and regulates the flow of the reformed water when it is in the closed state.
A water level detection device that detects the water level in the water tank,
A fuel cell system including a control device for at least controlling the fuel cell.
The control device is
A derivation unit that derives the driving amount of the pressurizing device according to the power generation amount of the fuel cell, and
Using the water level of the water tank detected by the water level detection device, a correction unit that corrects the drive amount of the pressurizing device derived by the lead-out unit, and a correction unit.
By driving the pressurizing device with the driving amount of the pressurizing device corrected by the compensating section and opening the solenoid valve in the open state, the reformed water is evaporated from the water tank to the evaporating section. A fuel cell system equipped with a reformed water supply unit to supply to. Further comprising at least one of a temperature sensor for detecting the temperature of the pressurizing device and a measuring device for measuring the driving time of the pressurizing device.
The correction unit
The first aspect of claim 1, wherein at least one of the temperature detected by the temperature sensor and the drive time driven by the measuring device is used to further correct the drive amount of the pressurizing device derived by the lead-out unit. Fuel cell system. The water flow pipe is arranged between the water tank and the solenoid valve, and further includes a regulating unit that regulates the flow of fluid from the solenoid valve to the water tank according to claim 1 or 2. The fuel cell system described in.

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