JP6454874B2 - Fuel cell system and operation method thereof - Google Patents

Description

  The present invention relates to a fuel cell system that generates power using an oxidant gas and a fuel gas, and an operation method thereof.

  A fuel cell system usually has a hydrogen production apparatus (hereinafter referred to as a reformer) having a reformer that generates a hydrogen-containing gas (hereinafter referred to as reformed gas) from natural gas or LPG, which is a general raw material infrastructure. ) And a fuel cell stack that generates power using the reformed gas.

  A fuel cell system including a fuel cell that generates power by reacting a fuel gas and an oxidant gas as a power generation unit is a mechanism for cooling heat generated in the fuel cell power generation unit (for example, using cooling water) in order to perform stable power generation. A circulating circuit and a cooling water tank for storing cooling water).

  Then, water generated by condensing water vapor contained in oxidant off-gas discharged from the cathode of the fuel cell power generation unit, anode off-gas discharged from the anode of the fuel cell, combustion off-gas discharged from the burner, etc. 2. Description of the Related Art A fuel cell power generation device including a condensed water tank that collects and stores is known. The collected condensed water is used again as reformed water, and can continue to generate electricity independently without replenishing water from the outside.

  However, in the state where power generation is not performed at the time of installation and construction, there is no generation of water, and it is necessary to add these cooling water and reforming water manually or automatically. At this time, when city water such as tap water is introduced, the conductivity of the cooling water is increased, and the separator constituting the fuel cell power generation unit may be damaged, and the tap water has an appropriate conductivity. May be purified.

  For example, Patent Literature 1 discloses a fuel cell system that includes a cooling water path, a cooling water tank, a water supply unit, and a purification unit, and performs a purification operation after the water is supplied to the cooling water tank.

JP 2014-135125 A

  In the fuel cell system used in the above-described conventional technology, when performing a test operation when the fuel cell system is installed, or when draining water for maintenance and performing a test operation after the maintenance is completed, a cooling water tank of the fuel cell system is used. It is necessary to perform the power generation operation after performing the purification operation with the purifier after the city water is supplied.

  In addition, depending on the quality of the city water supplied, it takes a considerable amount of time for the purification operation, and there is a problem that the construction worker's restraint time increases and the construction cost increases.

  Further, in order to perform the purification operation in a short time, a pump and a purifier capable of processing a large flow rate are required, resulting in an increase in cost.

The present invention has been made in view of the above-described problems, and has an object to provide a fuel cell system and a method for operating the fuel cell system that reduce the restraint time of an operator when water is supplied to the fuel cell system. To do.

  In order to achieve the above object, the present invention provides heat generated by a fuel cell in at least one of a case where a fuel cell system is installed and a test operation is performed, and a case where a test operation after maintenance is performed. Operates the circulator that circulates the cooling water after the supply of water to the cooling water tank in the circulation path through which the cooling water to be absorbed starts and before the purification operation to purify the cooling water with the purifier Thus, the pre-purification power generation operation for starting the power generation of the fuel cell is performed.

  Thereby, it becomes possible to shorten the trial run time at the time of installation and the restraint time of the installer by a lower cost and simple method.

  According to the present invention, it is possible to reduce the trial run time at the time of installation and the restraint time of the installer by a lower cost and simple method.

Schematic diagram of a fuel cell system in an embodiment of the present invention The flowchart which shows the driving | operation operation | movement of the fuel cell system in embodiment of this invention. The flowchart which shows a part of driving | operation operation | movement of the fuel cell system in embodiment of this invention in detail

  1st invention is arrange | positioned on the said circulation path, the fuel cell which produces electric power using oxidant gas and fuel gas, the circulation path through which the cooling water which absorbs the heat which the said fuel cell generate | occur | produces circulates, A cooling water tank configured to be supplied with cooling water via a water supply unit; a circulator disposed on the circulation path for circulating the cooling water; a purifier for purifying the cooling water; A controller that performs a purifying operation for purifying the cooling water with the purifier, and the controller performs at least a test operation when a fuel cell system is installed and a test operation after maintenance. In any one of the cases, after the water supply to the cooling water tank is started and before the purification operation is performed, the pre-purification power generation operation is performed in which the circulator is operated to start the power generation of the fuel cell. To control the fuel A pond system.

  Thereby, since the test run is performed without performing the purification operation, the time required for the test run can be shortened.

  In a second aspect of the invention, in particular, in the first aspect of the invention, the controller controls the purification operation to be executed after the pre-purification power generation operation is stopped and before the next power generation is started. Thereby, purification operation | movement can be performed during a stop and there is no generation | occurrence | production of the waiting time of a constructor by purification operation.

  According to a third aspect of the invention, in particular, in the second aspect of the invention, when the controller receives a predetermined operation input related to power generation from a user after the power generation operation before purification is stopped, the purification operation is executed. Is to control. Thereby, when draining and water filling are performed immediately after purification, it is possible to prevent wasteful consumption of the ion exchange resin used in the purifier.

According to a fourth aspect of the present invention, in particular, when the controller in any one of the first to third aspects of the present invention includes a pre-purification power generation operation in which an integrated time exceeds a preset first time, the pre-purification The power generation operation is not performed, and the circulator is operated to start power generation after the purification operation. Thereby, tap water power generation time can be limited and corrosion and elution of a fuel cell (for example, a separator) can be suppressed.

  In a fifth aspect of the invention, in particular, in any one of the first to fourth aspects of the invention, when the time of the pre-purification power generation operation per time exceeds a preset second time, The trial operation is controlled to stop. Thereby, the tap water power generation time per time can be limited, and corrosion and elution of a fuel cell (for example, a separator) can be suppressed.

  In a sixth aspect of the invention, in particular, the controller according to any one of the first to fifth aspects of the invention controls the output of the fuel cell in the pre-purification power generation operation to be a predetermined output or more. is there. Thereby, the voltage of the fuel cell stack can be lowered, and corrosion and elution of the fuel cell (for example, a separator) can be suppressed.

  In a seventh aspect of the invention, in particular, the controller according to any one of the first to sixth aspects of the invention controls the control temperature of the fuel cell in the pre-purification power generation operation to be lower than that in normal operation. Is. Thereby, the operating temperature of the fuel cell stack can be lowered, and corrosion and elution of the fuel cell (for example, a separator) can be suppressed.

  The eighth invention is disposed on the circulation path, a fuel cell that generates power using oxidant gas and fuel gas, a circulation path through which cooling water that absorbs heat generated by the fuel cell circulates, A cooling water tank configured to be supplied with cooling water via a water supply unit; a circulator disposed on the circulation path for circulating the cooling water; a purifier for purifying the cooling water; When the fuel cell system is installed and a test operation is performed, and when at least one of a test operation after maintenance is performed, the cooling water tank is supplied to the cooling water tank. After water supply is started, after the step of performing the pre-purification power generation operation for operating the circulator and starting the power generation of the fuel cell, and the step of performing the pre-purification power generation operation, the cooling water is supplied to the purifier. Clean Performing a cleaning operation for, it is provided with a.

  Thereby, since the test run is performed without performing the purification operation, the time required for the test run can be shortened.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. Note that the present invention is not limited to the present embodiment.

(Embodiment 1)
Embodiment 1 of the present invention will be described below. 1 is a configuration diagram of a fuel cell system including a purifier, a hydrogen production apparatus, a fuel cell power generation unit, a cooling water tank, and a condensed water tank according to Embodiment 1 of the present invention.

  In FIG. 1, a constituent element indicated by reference numeral 1 is a raw material pump that pressurizes and supplies a raw material gas, a constituent element indicated by reference numeral 2 is a reforming water pump that supplies reforming water used for steam reforming, and a reference numeral 3 indicates The constituent element shown is a raw material / water mixing section in which the raw material gas and the reforming water are mixed, and the constituent element indicated by reference numeral 4 is a fuel processor that produces hydrogen from the raw material and the reforming water by a reforming reaction.

  Further, a component indicated by reference numeral 5 is a fuel cell power generation unit anode inlet pipe for supplying fuel from the fuel processor 4 to the fuel cell power generation unit (fuel cell) 19, and a component indicated by reference numeral 6 is a fuel cell power generation unit anode. The component indicated by reference numeral 7 in the outlet pipe is an anode exhaust gas heat exchanger that exchanges heat between the anode off-gas discharged from the fuel cell power generation unit 19 and the exhaust heat recovery path 23.

  Further, the constituent element indicated by reference numeral 8 is an off-gas combustor that burns unused fuel or the like contained in the anode off-gas, and the constituent element indicated by reference numeral 9 is the exhaust gas burned by the off-gas combustor 8 and the exhaust heat recovery path Combustion exhaust gas heat exchanger for exchanging heat between them, a component indicated by reference numeral 10 is an exhaust port for discharging the combustion exhaust gas to the outside of the fuel cell system.

  Further, a constituent element indicated by reference numeral 11 is a condensed water tank for collecting and storing the produced water condensed in the anode off-gas heat exchanger 7 and the combustion exhaust gas heat exchanger 9, and a constituent element indicated by reference numeral 12 is condensed water. The purifier for purifying the supplied city water and the like, and the component indicated by reference numeral 13 is a reforming water solenoid valve for guiding the reforming water supplied from the reforming water pump 2 to the fuel processor 4. is there.

  Further, a component indicated by reference numeral 14 is a water supply electromagnetic valve for guiding water pumped up from the condensed water tank 11 by the reforming water pump 2 to the cooling water tank 15, and a component indicated by reference numeral 16 is the cooling water tank 15. The component indicated by reference numeral 17 is a cooling water heat exchanger that is connected to the cooling water tank 15 and exchanges heat between the cooling water circulation path 18 and the exhaust heat recovery path 23. .

  Further, a component indicated by reference numeral 20 is a cooling water circulation pump for circulating water in the cooling water circulation path 18, and a component indicated by reference numeral 21 is for guiding water overflowing from the cooling water tank 15 to the condensed water tank 11. A component indicated by reference numeral 22 is a condensed water drainage path for guiding the generated water condensed by the anode offgas heat exchanger 7 or the like to the condensed water tank 11.

  A component indicated by reference numeral 24 monitors signals from each actuator, values of sensors, etc., and controls the actuator. A control unit indicated by reference numeral 25 circulates the exhaust heat recovery path 23. This is a waste heat recovery water circulation pump.

  In consideration of simplification of the drawing and ease of understanding, the monitoring control unit 24 and the sensors and actuators are not connected in FIG. 1 but are not shown in the figure. The necessary sensors and actuators are all connected to the monitoring control unit 24. It is connected.

  The configuration of FIG. 1 is an example, and for example, the purifier 12 may be in a position where the recovered water or supplied city water can be purified. From the condensed water drainage path 22 and the combustion exhaust gas heat exchanger 9, These condensed water and cooling water drainage paths 21 may be merged and disposed between the path and the condensed water tank 11, or may be disposed downstream of the reforming water pump 2.

  Further, the fuel cell power generation unit 19, the cooling water heat exchanger 17, the cooling water tank 15, and the cooling water circulation pump 20 disposed in the cooling water circulation path 18 circulate the cooling water through the cooling water circulation path 18, and the fuel cell power generation unit 19. The cooling water may be cooled and the heat exchange with the exhaust heat recovery path 23 may be performed. For example, the cooling water circulation pump 20 may be disposed between the cooling water tank 15 and the cooling water heat exchanger 17. The cooling water heat exchanger 17 may be disposed downstream of the fuel cell power generation unit 19.

  Although not shown, an exhaust air heat exchanger that collects heat in the oxidant gas exhausted from the cathode outlet of the fuel cell power generation unit 19 and condenses the generated water is installed to condense the condensed water. It may be stored in a water tank.

  Hereinafter, the operation of the fuel cell system in the present embodiment will be described. The source gas is boosted by the source pump 1, and the flow rate is controlled to an appropriate value so that the amount of hydrogen generated by the fuel processor 4, the amount of hydrogen used by the fuel cell power generation unit 19, and the fuel utilization rate are obtained. Similarly, the reforming water flow rate is controlled by the reforming water pump 2 so as to obtain an appropriate S / C ratio. The fuel containing hydrogen generated by the fuel processor 4 is supplied to the fuel cell power generation unit 19 through the anode inlet pipe 5.

  The fuel gas supplied to the fuel cell power generation unit 19 is consumed by the combined reaction of hydrogen and oxygen inside the fuel cell power generation unit 19, and the unused fuel gas is turned off gas through the anode outlet pipe 6 and the anode off gas heat exchanger 7. The heat is exchanged with the exhaust heat recovery path 23 to condense the moisture contained in the offgas. The condensed water is stored in the condensed water tank 11 through the condensed water drainage path 22.

  The anode offgas containing unused gas that has passed through the anode offgas heat exchanger 7 is supplied to the offgas combustor 8 and used for the combustion reaction to supply heat to the fuel processor 4. The flue gas exhausted from the off-gas combustor 8 exchanges heat between the flue gas and the exhaust heat recovery path 23 in the flue gas heat exchanger 9.

  Moisture contained in the combustion exhaust gas is condensed in the combustion exhaust gas heat exchanger 9 and stored in the condensed water tank 11 through the condensed water drainage path 22, and the exhaust gas is led to the exhaust port 10 and exhausted outside the fuel cell system.

  The cooling water tank 15 is provided with a water supply unit 16. When the water supplied from the water supply unit 16 exceeds the upper limit water level of the cooling water tank 15, it overflows and is distributed to the condensed water tank 11 through the cooling water drainage path 21. .

  The water supply unit 16 may be a water supply port in the case of manual water supply, or an open / close valve such as a solenoid valve when the exhaust heat recovery path 23 is connected to a hot water storage tank or the like and city water can be supplied by water supply pressure. It may be.

  The city water stored in the condensed water tank 11 through the cooling water drainage path 21 supplied to the recovered water or the cooling water tank 15 stored in the condensed water tank 11 is passed through the purifier 12 by the reforming water pump 2 and modified. The quality water electromagnetic valve 13 is closed, the water supply electromagnetic valve 14 is opened, and the water is pumped to the cooling water tank 15. At this time, when flowing through the purifier 12, impurities such as metal ions contained in the city water are purified and purified to a water quality suitable for circulating the fuel cell power generation unit 19.

  The purified water pumped up by the reforming water pump 2 exceeds the upper limit water level of the cooling water tank 15 and is returned to the condensed water tank 11 through the cooling water drainage path 21. By repeating this, the water stored in the cooling water tank 15 and the condensed water tank 11 is sequentially purified.

  Further, at this time, the cooling water circulation pump 20 is operated to purify the purified water and the unpurified water by performing purification while stirring the inside of the cooling water tank 15, for example, in the cooling water tank 15. Prevents bias to the bottom.

  FIG. 2 is a flowchart showing a sequence related to the purification operation and the trial operation in the present embodiment.

  In S101, it is determined whether or not the test run. In the trial operation, the process proceeds to S102, and it is determined whether or not the total power generation time before purification exceeds a preset first time. Here, the total power generation time before purification indicates the total total power generation time when the fuel cell system generates power without purifying the tap water. If the predetermined time has not been exceeded, the process proceeds to S103 and power generation before purification is performed. During power generation before purification, the total power generation time before purification is counted.

  According to the configuration and operation method of this fuel cell system, power generation is performed without performing a purification operation in a test operation after installation or maintenance, so the time required for the test operation is shortened, and the on-site restraint time for the installer and maintenance personnel is reduced. It can be shortened.

  Further, the monitoring control unit 24 may be configured to perform a purification operation after the pre-purification power generation operation is stopped and before the next power generation is started.

  Thereby, purification operation | movement can be performed during a stop and there is no generation | occurrence | production of the waiting time of a constructor by purification operation.

  The monitoring control unit 24 may be configured to perform a purification operation when a predetermined operation input related to power generation is received from the user after the pre-purification power generation operation is stopped.

  Thereby, it is possible to prevent wasteful consumption of the ion exchange resin used in the purifier 12 when draining and water filling are performed immediately after purification.

  In S102, the purification operation is performed when the total power generation time before purification exceeds the first time, and the power generation before purification is determined when it does not exceed the first time. During the first time, when the fuel cell power generation unit 19 is operated with cooling water having high conductivity such as city water, the cooling water path of the fuel cell power generation unit 19 causes corrosion, elution of the base material, etc. It is set so that it does not occur, and is determined by impurities contained in city water, conductivity, and the like.

  For example, in the case of using cooling water with a certain conductivity of tap water in a certain area, the potential applied to the cooling water path by power generation and the corrosion current derived from the conductivity and the amount of corrosion derived from the corrosion current are Set a value that will not hinder operation due to damage to the seal or flow path.

  In this way, by limiting the total power generation time before purification to the first time or less, it is possible to prevent corrosion and elution (for example, corrosion and elution of separator material) of the fuel cell power generation unit 19 that may occur due to power generation before purification. .

  If the test operation is not performed in S101, it is determined in S105 whether the purification is completed. If purification is complete, perform normal operation. If purification has not been completed, a determination is made in S107 to perform the purification operation when the fuel cell system is not generating power and the user's power generation mode setting is set to other than power generation inhibition.

  If purification is performed while power generation is stopped, the user will not be kept waiting for the purification operation. In addition, since the user intends not to generate power when the power generation prohibition setting is performed, there is a possibility that the fuel cell system may be suspended, and the fuel cell system water before the fuel cell power generation unit 19 is suspended. There is a high possibility of unplugging.

  Therefore, by detecting that the user has set the power generation mode other than power generation prohibition and performing the purification operation, the user may perform the purification operation again by draining or filling with water immediately after purifying the water by the purification operation. As a result, useless consumption of the ion exchange resin of the purifier 12 can be avoided.

  FIG. 3 shows a detailed sequence of the power generation before purification in the trial operation in S103 in FIG. When the pre-purification power generation exceeds the preset second time in S201, the process proceeds to S202, the pre-purification power generation is stopped, and the process proceeds to S205 to cancel the trial operation.

  This is because the main purpose of the trial operation is to confirm that the fuel cell system operates soundly after installation and maintenance, and it is not necessary to generate power for a long time.

  On the other hand, there is a possibility that the installer or the maintenance staff leaves the site without releasing the trial run while the trial run is operated, and does not return as it is. Therefore, after stopping the power generation before purification, the trial operation is canceled and the standby state is entered.

  The second time for limiting power generation before purification per time is determined by the first time for limiting the total power generation time before purification in total and how many trial runs are assumed. For example, when the first time is set to 1000 hours, if the maximum number of trial runs required from when the fuel cell system is installed until it is removed is, for example, 50 times, the power generation time before purification per time is limited. The second time is 20 hours.

  The maximum number of trial runs required is the number of trial runs from installation to delivery to the user, how many consumables are exchanged before removal, drainage and water supply, etc. It is determined by multiplying an assumption such as how many times a necessary failure occurs.

  In this way, by limiting the power generation time before purification per time, it is possible to set an appropriate and allowable total number of trial runs, so that corrosion of the fuel cell power generation unit 19 due to power generation before purification (for example, a separator) (Corrosion of materials) can be suppressed, and troubles in operation can be prevented. Moreover, even when the installer and the installer leave the site without canceling the trial run, the power generation can be stopped appropriately and the trial run can be canceled.

  In S201 in FIG. 2, if the power generation time before purification does not exceed the second time per time and the total power generation time before purification does not exceed the first time in S203, low corrosion power generation in S204 is performed.

  The higher the potential applied to the coolant path of the fuel cell power generation unit 19, the higher the corrosion current. For this reason, during power generation before purification, power generation is performed such that the potential applied to the cooling water path of the fuel cell power generation unit 19 is low. For example, when the fuel cell power generation unit 19 is a multi-stacked stack of power generation cells, the stack cooling unit path closest to the terminals is most likely to be applied with electric potential.

  For this reason, a high current density operation is performed as an operation in which the voltage between the stack terminals is the lowest. If the current density increases, the voltage between terminals decreases from the current-voltage characteristics of the fuel cell. When the fuel cell system performs AC output target control, the operation is performed so that the output target is larger than a specific value.

  Thus, during power generation before purification, the fuel cell power generation unit 19 is generating power before purification by reducing the terminal voltage of the fuel cell power generation unit 19 by setting the output of the fuel cell power generation unit 19 to a predetermined value or more. The amount of corrosion by the cooling water can be reduced.

  The corrosion rate of the cooling water path of the fuel cell power generation unit 19 greatly depends on the conductivity of the cooling water. Further, it has been found that the conductivity of cooling water containing metal ions such as tap water and hypochlorite ions strongly depends on the temperature, and the conductivity increases as the temperature increases. For this reason, during the low-corrosion operation of S204, the amount of corrosion can be reduced by lowering the control temperature compared to the normal temperature control of the fuel cell power generation unit 19.

  Specifically, during the low-corrosion operation, the exhaust heat recovery water circulation pump 25 and the cooling water circulation pump 20 are controlled with an operation amount or a rotational speed higher than that in the normal operation, and control for lowering the operation temperature of the fuel cell power generation unit 19 is performed.

Thus, by performing the operation of lowering the control temperature of the fuel cell power generation unit 19 during power generation before purification, the amount of corrosion of the fuel cell power generation unit 19 by the cooling water during power generation before purification can be reduced.

  As described above, the fuel cell system according to the present invention can reduce the waiting time of the installer when performing a test operation, and thus can be applied to applications such as a stationary fuel cell cogeneration system.

DESCRIPTION OF SYMBOLS 1 Raw material pump 2 Reformed water pump 4 Fuel processor 5 Anode inlet piping 6 Anode outlet piping 7 Anode offgas heat exchanger 8 Offgas combustor 9 Combustion exhaust gas heat exchanger 10 Exhaust port 11 Condensate water tank 12 Purifier 13 Reformer water Solenoid valve 14 Water supply solenoid valve 15 Cooling water tank 16 Water supply unit 17 Cooling water heat exchanger 18 Cooling water circulation path 19 Fuel cell power generation unit 20 Cooling water circulation pump 21 Cooling water drainage path 22 Condensate drainage path 23 Waste heat recovery path 24 Monitoring control Part 25 Waste heat recovery water circulation pump

Claims (8)

A fuel cell that generates power using oxidant gas and fuel gas;
A circulation path through which cooling water that absorbs heat generated by the fuel cell circulates;
A cooling water tank disposed on the circulation path and configured to be supplied with cooling water via a water supply unit;
A circulator disposed on the circulation path for circulating the cooling water;
A purifier for purifying the cooling water;
A controller for performing a purifying operation for purifying the cooling water with the purifier;
With
In the case where at least one of the case where the fuel cell system is installed and a test operation is performed, and the case where a test operation after maintenance is performed, the controller is configured to start supplying water to the cooling water tank, And before performing the purification operation, control to perform the pre-purification power generation operation of operating the circulator and starting the power generation of the fuel cell,
Fuel cell system.   2. The fuel cell system according to claim 1, wherein the controller performs control so that the purification operation is executed after the pre-purification power generation operation is stopped and before the next power generation is started.   3. The fuel cell system according to claim 2, wherein the controller performs control so as to execute the purification operation when a predetermined operation input related to power generation is received from a user after the pre-purification power generation operation is stopped. .   The controller does not perform the power generation operation before purification when the accumulated time of the power generation operation before purification exceeds a preset first time, and operates the circulator after the purification operation to generate power. The fuel cell system according to claim 1, wherein the fuel cell system is controlled to start.   5. The controller according to claim 1, wherein when the time of the pre-purification power generation operation per time exceeds a preset second time, the controller performs control so as to stop the trial operation. The fuel cell system described.   6. The fuel cell system according to claim 1, wherein the controller controls the output of the fuel cell in the pre-purification power generation operation to be equal to or higher than a predetermined output.   The fuel cell system according to any one of claims 1 to 6, wherein the controller controls the control temperature of the fuel cell in the pre-purification power generation operation to be lower than that in a normal operation. A fuel cell that generates power using oxidant gas and fuel gas;
A circulation path through which cooling water that absorbs heat generated by the fuel cell circulates;
A cooling water tank disposed on the circulation path and configured to be supplied with cooling water via a water supply unit;
A circulator disposed on the circulation path for circulating the cooling water;
A purifier for purifying the cooling water;
A method for operating a fuel cell system comprising:
In at least one of the case where the fuel cell system is installed and a test operation is performed, and the case where a test operation after maintenance is performed, the circulator is installed after water supply to the cooling water tank is started. Performing a pre-purification power generation operation to operate and start power generation of the fuel cell;
After the step of performing the pre-purification power generation operation, performing a purification operation of purifying the cooling water with the purifier;
A method for operating a fuel cell system.

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