JP2007155188A - Heat pump type heat source device using solid oxide fuel cell as power source to carry out driving, and its operating method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To efficiently operate the whole device without applying high stress to a fuel cell in a heat pump type heat source device using the fuel cell as a power source to carry out driving. <P>SOLUTION: In the heat pump type heat source device using the fuel cell as a power source to carry out driving, a solid oxide fuel cell 2 is used as the fuel cell. Output voltage of the solid oxide fuel cell 2 is controlled by a DC-DC converter 3, and it is supplied to a direct-current compressor 5a of a heat pump. The device is provided with a storage battery 7 capable of storing electric power of the solid oxide fuel cell 2, and the compressor 5a of the heat pump can be also operated by electric power from the storage battery 7. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a heat pump type heat source device that drives a fuel cell, particularly a solid oxide fuel cell as a power source, and an operation method thereof.

  A heat pump type heat source device is used as a heat source device of an air conditioning system in a commercial building or the like. Heat pump type heat source devices are broadly classified into those driven by electric power (EHP) and those driven by gas (GHP). Among these, those driven by electric power (EHP) are mainly driven by the AC power from the system, but the AC-driven compressor has a low efficiency of about 80%, and the input power A loss of about 20% occurs. For this reason, in recent years, an AC-DC converter having system AC power inside is converted into DC power, and compared with this, efficiency is improved by driving a high-efficiency DC compressor. However, the conversion efficiency of the AC-DC converter is about 92 to 93%, and it is inevitable that a conversion loss occurs. Although the loss due to such conversion is small per unit, the total amount is very large considering the spread situation.

  There has also been proposed a heat pump type heat source device in which the compressor is driven by using direct current power from a fuel cell instead of system alternating current power as drive power. Patent Documents 1 and 2 describe a fuel cell drive heat pump system in which DC power of a fuel cell is supplied to an AC drive compressor. Patent Document 2 also describes storing a part of surplus power in a battery (secondary battery) via a DC-DC converter. Patent Document 3 describes a refrigeration apparatus used in a cogeneration system, in which a fuel cell can be used as a power generation apparatus, a compressor can be driven by DC power of the power generation apparatus, and the like.

JP-A-8-5190 JP 2003-130491 A JP 2003-222429 A

  In the heat pump heat source device, as described in Patent Document 1, the configuration in which the direct current power of the fuel cell is converted into alternating current to drive the alternating current drive compressor is the efficiency of the alternating current drive compressor as described above. Is not high from the viewpoint of thermal efficiency. As proposed in Patent Document 3, it is expected that high thermal efficiency can be obtained by driving a DC compressor with DC power from a fuel cell.

  However, in heat pump heat source devices used in air conditioning systems, etc., the fuel cell operation is corresponding to the fact that the ON / OFF is frequently repeated under actual operation and the output fluctuation range on the air conditioning system side is large. When it is difficult to perform control properly, and when the operating power of a relatively large air conditioning system such as a commercial building is provided by the power generated from the fuel cell, a fuel cell with high power generation efficiency is not used. However, there are still many problems to be solved in the heat pump type heat source device that drives the fuel cell as a power source because it cannot obtain high operating efficiency enough to withstand practical use as a whole. The situation is not reached.

  The present invention has been made in view of the circumstances as described above, and is easy to control the operation of the entire apparatus including the fuel cell, and can achieve high operating efficiency. The fuel cell is driven as a power source. An object of the present invention is to provide a heat pump type heat source device and an operation method thereof.

  The present invention is a heat pump heat source device that drives a fuel cell as a power source, the fuel cell is a solid oxide fuel cell, and includes a DC-DC converter that controls the output voltage of the solid oxide fuel cell, The compressor of the heat pump is a DC compressor that is driven by DC power that is voltage-controlled by a DC-DC converter, and includes a storage battery that can store the power of the solid oxide fuel cell. The heat pump compressor is also operable.

  The present invention also relates to an operation method of a heat pump heat source apparatus that drives a solid oxide fuel cell as a power source, and the generated power of the solid oxide fuel cell is compressed by a DC of the heat pump via a DC-DC converter. The power generated by the solid oxide fuel cell is stored in the storage battery, and the load from the heat pump is reduced by supplying the power from the storage battery to the compressor of the heat pump. The output power leveling during the operation of the solid oxide fuel cell is made possible.

  In the present invention, a solid oxide fuel cell (SOFC) is employed as the fuel cell. The reason is that solid oxide fuel cells have higher power generation efficiency compared to other types of fuel cells such as polymer electrolyte fuel cells (PEFC) and phosphoric acid fuel cells (PAFC). Moreover, if city gas is reformed to methane, it can be used as fuel gas, and it can be operated at low cost with a simple system configuration.

  In the present invention, a DC-DC converter for controlling the output voltage of the solid oxide fuel cell is provided, and the DC compressor of the heat pump is driven by DC power in a state where the input / output voltage is adapted. Since the conversion efficiency of the DC-DC converter is high and the thermal efficiency of the DC compressor is higher than that of the AC-driven compressor, a heat pump heat source device and operation method with extremely high operation efficiency can be obtained.

  On the other hand, the solid oxide fuel cell has a high operating temperature of 700 to 1000 ° C., is difficult to repeat on / off like power generation, power generation stop, and re-power generation, and has low resistance to load fluctuations. When a solid oxide fuel cell is used as a power source for a heat pump heat source device, a large stress is applied to the solid oxide fuel cell and operation may become unstable. In order to avoid this and stably operate the solid oxide fuel cell, the apparatus of the present invention is provided with a storage battery capable of storing the power of the solid oxide fuel cell, and the power from the storage battery is used. Has also made it possible to operate the compressor of the heat pump.

  With this configuration, for example, a. When the solid oxide fuel cell does not reach steady operation, such as when the heat pump heat source device is started up, it is operated with only the electric power from the storage battery or with the shortage supplemented with the electric power from the storage battery, b. When the solid oxide fuel cell is in steady operation, all the necessary power is supplied from the fuel cell, c. When surplus power is generated when the heat pump is stopped, etc., the heat pump heat source device is operated for a long time without applying excessive stress to the solid oxide fuel cell, such as storing the power in the storage battery. This makes it possible to stabilize the operation of the solid oxide fuel cell. That is, it becomes possible to level the solid oxide fuel cell operation with respect to load fluctuations.

  In the apparatus and method of the present invention, an AC-DC converter is further provided, and if necessary, the DC compressor is driven by DC power obtained by controlling the voltage of the system power supply, and if necessary, the solid oxide fuel cell It is a preferable aspect that the surplus power can be output as AC power by grid connection or the like.

  In this aspect, when it is predicted that a peak load that cannot be dealt with by the power supplied from the solid oxide fuel cell and / or the storage battery will occur, the system power source is used, and the AC-DC is used. It can be converted to DC power by a converter and supplied to the compressor of the heat pump, and when the air conditioning load suddenly decreases, the power supplied from the solid oxide fuel cell is connected to the grid (for example, It is also possible to provide means for converting to AC power by a DC-AC converter (inverter) and supplying it to the power system or AC load. As a result, the entire system can be operated without significantly stressing the solid oxide fuel cell.

  In the apparatus of the present invention, as a storage battery, in addition to a storage battery capable of storing surplus power from a solid oxide fuel cell, for example, a storage battery for storing regenerative power for storing regenerative power of an elevator is further provided, and both storage batteries are provided. You may be able to share it. In this mode, for example, the power from the solid oxide fuel cell stored at night and the regenerative power on the elevator side can be used in the elevator hoist along with the compressor of the heat pump. Therefore, each system can be operated effectively and efficiently. Even if the regenerative power can be stored in the storage battery that stores the surplus power of the solid oxide fuel cell, the same effect can be obtained.

  The apparatus of the present invention is preferably an operation state prediction means for predicting the operation state of the heat pump, and an operation control means for controlling at least the start of charging of the storage battery and the start of power supply from the storage battery to the compressor based on information from the operation state prediction means. And further comprising. The power supply control means may further include an adjustment means for adjusting the output of the solid oxide fuel cell based on information from the operating state prediction means.

  By providing such prediction means and operation control means, it becomes even easier to operate the solid oxide fuel cell stably at the rated value. As an example of the operation state prediction means, for example, when the heat pump heat source device is an air conditioning system, the means for capturing room environment data such as room temperature and humidity and the load data of the building in the past will be compared in the future. And a predicting means including a means for predicting the driving pattern. In addition, a means for predicting a subsequent driving pattern from representative or unique load data for each season is also included.

  The operation control means controls the charging start timing of the storage battery and the power supply start timing from the storage battery to the compressor based on the information from the operating state prediction means. For example, the rated operation of the solid oxide fuel cell Below, when the operation state predicting means predicts an increase in load, prepare to enable power supply from the storage battery, and start power supply from the storage battery to the compressor when the load increases, or load When a decrease is predicted, the storage battery is prepared for storage, and when the load decreases and surplus power is generated, control is performed such that the surplus power is immediately diverted to storage in the storage battery. By providing such means, it becomes easy to integrate and control the solid oxide fuel cell and the storage battery, and the solid oxide fuel cell can be operated stably and efficiently.

According to the present invention, it is possible to use the power from the solid oxide fuel cell as the base power and continue the stable operation of the solid oxide fuel cell. A CO ₂ reduction effect and an energy saving effect are also brought about, which is environmentally friendly.

  In addition, the heat pump type heat source device that drives the fuel cell according to the present invention as a power source and the operation method thereof can be applied to a heat source device such as a refrigeration showcase as well as an air conditioning system, and can be widely applied. .

  According to the present invention, in a heat pump heat source device that drives a fuel cell as a power source, the entire device can be controlled without applying high stress to the fuel cell, and high operating efficiency can be obtained. For this reason, the heat pump heat source device according to the present invention has extremely high practicality while using the power of the fuel cell as a base drive source.

  Hereinafter, the present invention will be described based on embodiments with reference to the drawings. FIG. 1 is a block diagram showing an example of a system configuration when the heat pump heat source apparatus according to the present invention is used for air conditioning, and FIG. 2 explains the state of a storage battery when using regenerative power in the system configuration shown in FIG. It is a figure to do. FIG. 3 is a block diagram in the case where an example of the operation state prediction means is provided in the system configuration shown in FIG. 1, and FIG. 4 is a flowchart showing an outline of the operation sequence of the system shown in FIG.

  In FIG. 1, reference numeral 1 denotes a solid oxide fuel cell (SOFC) facility, and a solid oxide fuel cell 2 generates and supplies power as a base in this air conditioner. Although not limited, city gas is used as fuel gas, and the supplied city gas is reformed into methane in the solid oxide fuel cell facility 1, and the fuel of the solid oxide fuel cell 2. Sent to the pole.

  A DC-DC converter 3 adjusts the voltage of the direct-current power generated by the solid oxide fuel cell 2. Reference numeral 4 denotes an outdoor unit for air conditioning, which has a heat pump provided with a DC compressor 5a. The direct current power controlled by the DC-DC converter 3 is supplied to the direct current compressor 5a. Although not shown, the illustrated outdoor unit 4 for air conditioning is provided with a second DC compressor 5 b, and the system power is supplied via an AC-DC converter (bidirectional inverter) 6 during peak load, for example. Supplied. Further, when the air conditioning load suddenly decreases, the power supplied from the solid oxide fuel cell 2 is converted into AC power by the DC-AC converter 6 and supplied to the power system and AC load.

  Reference numeral 7 denotes a storage battery, which supplies DC power to the compressor 5a when the solid oxide fuel cell 2 has not reached steady operation, such as at startup. When the solid oxide fuel cell 2 reaches steady operation, the power supply from the storage battery 7 is stopped. When the load on the air conditioning side is reduced during the steady operation of the solid oxide fuel cell 2 and surplus power is generated in the power generation amount of the solid oxide fuel cell 2, the surplus power is stored in the storage battery 7, and then Prepare.

  In commercial buildings, etc., air conditioning is sometimes stopped at night, but even in that case, the solid oxide fuel cell 2 cannot stop power generation due to its characteristics, and must be operated at the minimum output. It becomes. The electric power is stored in the storage battery 7. When the air conditioning in the building is started, the solid oxide fuel cell 2 is in a low output state and cannot supply the necessary power to the compressor 5a quickly. The stored battery 7 is supplied to the compressor 5a. As a result, a sufficient start-up operation is possible on the air conditioning side, and excessive stress due to load fluctuations can be avoided on the solid oxide fuel cell 2 side. In addition, it is possible to avoid intermittently interrupting the operation of the solid oxide fuel cell 2 and to stably operate the solid oxide fuel cell 2.

  The solid oxide fuel cell 2 has high power generation efficiency, the conversion loss of the DC-DC converter 3 is extremely small, and the efficiency of the DC compressor 5a is extremely large. Therefore, the above air conditioner can be operated with high efficiency as a whole. In addition, since the solid oxide fuel cell 2 can be stably operated continuously, it is possible to perform an air conditioning operation at a low cost over a long period of time.

  As described above, the apparatus shown in FIG. 1 includes the second DC compressor 5b, and when the peak load exceeding the design value is temporarily applied to the air conditioning side, the second power is supplied from the system power supply. The DC compressor 5b is also operated. Thereby, an excessive peak load can be overcome without applying excessive stress to the solid oxide fuel cell 2. In addition, the reverse is also possible, and when the air conditioning load suddenly decreases, surplus power from the fuel cell is supplied to the system side via the storage battery 7 or the AC-DC converter (bidirectional inverter) 6. Is also possible.

  Further, in the apparatus shown in FIG. 1, moisture is recovered from exhaust gas or air from the solid oxide fuel cell 2 by the refrigerant used in the heat pump of the outdoor unit 4 for air conditioning, and this is recovered on the solid oxide fuel cell 2 side. It is used as water for reforming city gas. This can also improve the thermal efficiency of the entire system.

  An elevator is provided in a commercial building, and a storage battery for storing regenerative electric power at the time of unloading generated from the elevator hoisting machine is usually provided. When the heat pump heat source device according to the present invention is used for air conditioning equipment in the same building, such a storage battery for elevator regenerative power storage can be shared with the storage battery 7 for the heat pump heat source device. Further, as shown in FIG. 2, the regenerative electric power from the elevator hoisting machine 8 may be directly stored in the storage battery 7 for the heat pump heat source device. By making the power from the solid oxide fuel cell 2 stored at night and the regenerative power on the elevator side available to the elevator hoist 8 together with the compressor 5a, each system can be effectively and efficiently used. It is possible to drive well.

  FIG. 3 shows another example of the case where the heat pump heat source device according to the present invention is used for an air conditioner. Here, the operation state prediction means for predicting the operation state of the heat pump and the information from the operation state prediction means are used. And an operation control means for controlling the start of charging of the storage battery and the start of power supply from the storage battery to the compressor. In the example shown, these means are shown as CPUs. In FIG. 3, the same members as those shown in FIG.

  In this example, the CPU includes information related to indoor environment data (for example, temperature and humidity) in an area to be air-conditioned, information related to building load data according to general operation patterns and operation patterns based on past operation history, and storage battery data. Information relating to (for example, the remaining amount of power storage, voltage Vb) and information relating to DC-DC converter data (eg, outlet voltage Vs) are captured. The CPU compares the indoor environment data with the building load data and predicts a future driving pattern.

  Further, the CPU compares the current operation mode, the predicted future operation pattern, and the storage battery data, and selects an operation state in which the solid oxide fuel cell 2 is not excessively stressed. More specifically, as described above, whether the solid oxide fuel cell 2 or the storage battery 7 should be operated with priority, or whether it is appropriate to supply power from both sides, etc. select. In addition, it is also determined at what point it is necessary to store electricity depending on the storage status of the storage battery.

  Whether the solid oxide fuel cell 2 or the storage battery 7 is preferentially operated can be determined, for example, by the CPU by adjusting the outlet voltage Vs of the DC-DC converter data 3 by the CPU. If the outlet voltage Vs> the storage battery voltage Vb, the solid oxide fuel cell is preferentially operated. In the opposite case, that is, if the outlet voltage Vs <the storage battery voltage Vb, the storage battery is preferentially operated.

  Further, the CPU adjusts the operation output of the solid oxide fuel cell 2 so that an optimum operation output state can be obtained according to the predicted future operation pattern and storage battery state.

  In this way, by performing operation control that takes into account future operation patterns, it is possible to realize stable operation of the solid oxide fuel cell 2 and energy-saving operation that effectively uses the storage battery 7.

  An example of the operation sequence of the heat pump heat source apparatus will be described in more detail with reference to the flowchart shown in FIG. FIG. 4 shows an example of a system in which a solid oxide fuel cell (SOFC) 2, a storage battery 7, and a heat pump type heat source device are combined. Based on this, it is also possible to add exchange with system AC power. .

  In S1, the CPU confirms the operation mode. It is determined whether or not the system is stopped (S2). If the system is stopped, the state of charge of the storage battery is confirmed (S3). The confirmation is made based on whether or not the storage battery 7 is fully charged (S4). When the battery is fully charged and the system continues to be stopped, the operation of the SOFC is stopped (S5). If the battery is not fully charged, the operation at the minimum load of the SOFC 2 is continued (S6), and the battery is waited until it is fully charged.

  If the system is operating, the CPU determines whether it is running (S11). In the case of activation, the CPU determines whether or not a large operation change rate is predicted, that is, whether or not the activation is in the initial stage (S31). When a large change is predicted (in the initial stage of startup), the storage battery charging status is confirmed (S32). The presence / absence of charge is determined (S33). If the battery is charged, power supply from the storage battery to the DC-DC converter 3 is started (S34), and the operation is continued. If the battery is not charged, it is predicted that excessive stress will be applied to the SOFC 2, so the activation is stopped (S 35).

  When the rate of change predicted in S31 is not large, that is, in the late stage of startup, the CPU similarly checks the storage battery charging status (S36), determines whether or not charging is performed (S37), and if charged. Then, power supply from the storage battery to the DC-DC converter 3 is started (S38), and the operation is continued. If the battery is not charged, the SOFC 2 has started up late and no significant stress is applied to the SOFC 2 even if the operation is continued. Therefore, while the power supply by the SOFC 2 is started, the storage battery is charged (S40). ) Continue driving.

  In the process of steady operation after startup as described above, the CPU predicts the operation change rate of the heat pump heat source device (S36). Whether or not there is an increase in output is predicted (S13), and when a large increase in output is predicted, the state of charge of the storage battery is confirmed (S14). The confirmation is made based on whether or not the storage battery 7 is fully charged (S15). If the storage battery is fully charged, the battery is kept on standby (continues operation), and when the load increases, the storage battery 7 is discharged to supply power to the compressor 5a. Additional supply is performed (S16). Continue driving in that state. If the battery is not fully charged in S15, the operation of the SOFC 2 is continued and the storage battery is also charged (S17). Continue driving in that state.

  Even when it is predicted that there is no increase or small output in S13, the CPU confirms the state of charge of the storage battery (S18). In this case, the confirmation is made based on whether or not the storage battery 7 is charged (S19). If the storage battery 7 is charged, power is supplied from the storage battery 7 while the operation is continued, and the storage battery 7 is almost discharged (S20). ). This is a preparation for accumulating surplus power from the SOFC 2 when the load is reduced. By taking this step, it is possible to avoid operation control that reduces the output of the SOFC 2 when the load is reduced. If the storage battery 7 is not charged in S19, the operation with the SOFC 2 is continued as it is (S21).

  By operating the heat pump heat source device according to the present invention through the steps as described above, a solid oxide fuel cell (SOFC) 2 that is difficult to start and stop and has low load fluctuation resistance can be obtained in accordance with load fluctuations. Thus, the solid oxide fuel cell (SOFC) 2 can be operated most stably and efficiently, that is, the operation can be leveled, without frequent interruption or large output adjustment. Further, by controlling the solid oxide fuel cell (SOFC) 2 and the storage battery 7 in an integrated manner, the operation of the storage battery can be leveled.

The block diagram which shows an example of the system configuration at the time of using the heat pump type heat source apparatus by this invention for an air conditioning. The figure explaining the state of a storage battery in the case of using regenerative electric power in the system configuration | structure shown in FIG. The block diagram at the time of further providing the driving | running state prediction means in the system configuration | structure shown in FIG. The flowchart which shows the outline | summary of the driving | operation sequence of the system shown in FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Solid oxide fuel cell (SOFC) equipment, 2 ... Solid oxide fuel cell (SOFC), 3 ... DC-DC converter, 4 ... Outdoor unit for air conditioning, 5a, 5b ... DC compressor for heat pump, 6 ... AC-DC converter (bidirectional inverter), 7 ... Storage battery, 8 ... Elevator hoisting machine

Claims (8)

  A heat pump heat source device that drives a fuel cell as a power source, the fuel cell being a solid oxide fuel cell, comprising a DC-DC converter that controls the output voltage of the solid oxide fuel cell, and a heat pump compressor Is a DC compressor that is driven by DC power that is voltage-controlled by a DC-DC converter, and has a storage battery that can store the power of the solid oxide fuel cell. The heat pump can also be compressed by the power from the storage battery. A heat pump heat source device characterized in that the machine is operable.   An AC-DC converter is further provided, and the DC compressor is driven by DC power whose voltage is controlled by the system power supply as required, and surplus power of the solid oxide fuel cell is supplied by system interconnection as necessary. The heat pump type heat source device according to claim 1, wherein the heat pump type heat source device can be output as AC power.   The storage battery for regenerative power storage is further provided, and the storage battery for storing regenerative power and the storage battery for storing the power of the solid oxide fuel cell can be used in common. Heat pump type heat source device.   The heat pump heat source apparatus according to claim 1 or 2, wherein the storage battery capable of storing electric power of the solid oxide fuel cell is also configured to store regenerative power.   An operation state prediction means for predicting the operation state of the heat pump, and an operation control means for controlling at least the start of charging of the storage battery and the start of power supply from the storage battery to the compressor based on information from the operation state prediction means, The heat pump type heat source device according to any one of claims 1 to 4.   6. The heat pump heat source apparatus according to claim 5, wherein the power supply control means further includes adjustment means for adjusting the output of the solid oxide fuel cell based on information from the operating state prediction means.   An operation method of a heat pump heat source device that drives a solid oxide fuel cell as a power source, and supplies generated power of the solid oxide fuel cell to a DC compressor of the heat pump via a DC-DC converter, The power generated by the solid oxide fuel cell is stored in a storage battery, and for the load fluctuation of the heat pump, the power from the storage battery is supplied to the compressor of the heat pump, so that the solid oxide fuel cell against the load fluctuation An operation method of a heat pump heat source device, characterized in that the operation can be leveled.   An AC-DC converter is further provided, and the DC compressor is driven by DC power whose voltage is controlled by the system power supply as required, and surplus power of the solid oxide fuel cell is supplied by system interconnection as necessary. It outputs as alternating current power, The operating method of the heat pump type heat source apparatus of Claim 7 characterized by the above-mentioned.

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