JP2005197108A - Fuel cell power generation hot-water supply system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a fuel cell power generation hot-water supply system capable of exhausting condensed water generated in gas in a heat exchanger in a fuel cell, a fuel processing device, or a tube channel, and preventing outflow of the gas and inflow of off-system air, as to one carrying out a partial-load slave operation. <P>SOLUTION: A condensed water recovery/exhaust device 6 is provided at a position with a high vapor concentration within an anode gas line and a cathode gas line at an inlet and outlet of the fuel cell. The condensed water recovery/exhaust device 6, as an example, fitted to a part or all of outlets of heat exchangers 27 in lines of the anode gas 17 and the cathode gas 19, has a structure of decelerating gas-flow velocity to a tenth or lower, and changing a flowing direction by 90° or more. By using part of condensed water left at the bottom part of a separating room 1 of the condensed water recovery/exhaust device 6 as a sealing material, the condensed water recovered is exhausted without leaking gas inside the system and without letting gas outside the system get mixed. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a fuel cell power generation / hot water supply system using a fuel cell as a main power source, and more particularly, to a fuel cell power generation / hot water supply system suitable for use in homes where electric power demand fluctuation and hot water supply demand fluctuation are large.

  As a configuration of a conventional fuel cell power generation hot water supply system, for example, a configuration described in Japanese Patent Application Laid-Open No. 2001-93550 is known. High demand power is required in some time zones, as in household fuel cell power and hot water supply systems. However, if the demand power is low on average, follow the power demand for efficient operation. It is economical to perform partial load operation.

JP 2001-93550 A

  However, the heat exchange amount in the heat exchanger of the exhaust heat recovery system changes under the partial load following operation condition. Furthermore, since it is operated at a temperature of 100 ° C. or lower and the water vapor concentration of the gas entering and exiting the fuel reformer (PEFC) is high, condensed water is generated and the amount of condensed water also varies. If this condensate is left in the piping, flooding occurs in the PEFC, leading to a decrease in PEFC performance and an increase in auxiliary power. Moreover, if the condensed water is generated in the anode return gas and returned to the reformer, it may cause a misfire. In a domestic fuel cell system, partial load following operation is performed for higher efficiency. For this reason, the generation of condensed water that becomes an obstacle to operation changes from moment to moment, and the condensate recovery and discharge device does not leak the gas in the system correspondingly, and also does not mix the gas outside the system. There is a problem that the condensed water must be discharged.

  An object of the present invention is to discharge the condensed water generated in the gas in the heat exchanger in the fuel cell, the fuel processing device or the pipe line in the domestic fuel cell power generation hot water supply system that performs the partial load following operation, It is another object of the present invention to provide a fuel cell power hot water supply system that can prevent outflow of the gas and inflow of air outside the system.

(1) In order to achieve the above object, according to the present invention, in a fuel cell power hot water supply system having a fuel processing device and a fuel cell, the concentration of water vapor in the anode gas line and the cathode gas line entering and exiting the fuel cell is reduced. A condensed water recovery / discharge device is provided at a high position.
With this configuration, the condensed water generated in the gas in the fuel cell, the fuel processing apparatus, or the heat exchanger in the pipe line can be discharged.

  (2) In the above (1), preferably, the condensed water recovery / discharge device is provided in a part or all of the heat exchanger outlets of the anode gas and cathode gas lines.

  (3) In the above (1), preferably, the condensed water recovery / discharge device is disposed immediately before the outlet of the fuel gas (anode gas) produced by the fuel processing device and the return port of the return anode gas to the fuel processing device. In addition, a condensed water recovery / discharge device is provided.

  (4) In the above (1), preferably, the condensed water collecting / discharging device is provided with a condensed water collecting / discharging device at a part or all of the cathode exhaust gas outlet, the anode gas inlet, or the anode exhaust gas outlet of the fuel cell. It is what I did.

  (5) In any one of the above (2) to (4), preferably, the condensed water recovery / discharge device decelerates a gas flow rate to be equal to or lower than a free falling speed of the condensed water droplets, and a falling direction of the condensed water. In contrast, the flow direction of the gas flow is made different.

  (6) In any one of the above (2) to (4), the condensed water recovery / discharge device includes a valve installed at the bottom or lower part of the separation chamber, and a part of the condensed water is placed at the bottom of the separation chamber. By using it as a sealing material, the recovered condensed water is discharged without leaking the gas in the system and without mixing the gas outside the system.

  (7) In the above (6), preferably, the condensed water recovery / discharge device is provided with a water level meter and a control means for opening and closing the valve based on a signal from the water level meter.

  (8) In the above (6), preferably, the condensed water recovery / discharge device includes a plurality of water level gauges and a control means for opening and closing the valve based on signals from these water level gauges. is there.

  According to the present invention, in a domestic fuel cell power generation hot water supply system that performs a partial load following operation, condensed water generated in a gas in a fuel cell, a fuel processing device, or a heat exchanger in a pipeline can be discharged, Further, the outflow of the gas and the inflow of air outside the system can be prevented.

Initially, the structure of the fuel cell power generation hot water supply system by one Embodiment of this invention is demonstrated using FIG.
FIG. 1 is a system configuration diagram showing the configuration of a fuel cell power hot water supply system according to an embodiment of the present invention.

  In the fuel cell power generation and hot water supply system according to the present embodiment, a plurality of condensate recovery / discharge devices 6 are provided for efficient operation.

The fuel processor 12 generates an anode gas 17 containing hydrogen and a combustion exhaust gas 18 from the city gas 13, the air 14, and the return anode gas 15. The fuel cell 20 generates electricity by reacting the anode gas 17 from the fuel processor 12 and the air 19 flowing in from the cathode. The fuel cell cooling water system 22 includes a water storage tank 21 and a heat exchanger 27-2, and cools the fuel cell 20.
The heat exchanger 27-1 is used to bring the anode gas 17 from the fuel reformer 12 to a temperature suitable for entering the anode of the fuel cell 20. The heat exchanger 27-2 is used to recover heat from the fuel cell cooling water system 22. The heat exchanger 27-3 is used to heat the cathode air 19 supplied to the fuel cell 20 with the cathode exhaust gas 24 from the fuel cell 20. The heat exchanger 27-4 is provided to recover heat from the cathode exhaust gas 26 from the heat exchanger 27-3 and from the anode exhaust gas 25 from the fuel cell 20.

  The valve 28-1 is for the fuel cell cooling water 22 to bypass the heat exchanger 27-2. The valve 28-2 is for the tap water 29 to bypass the heat exchanger 27-2.

  Furthermore, in this embodiment, the condensed water collection | recovery discharge apparatus 6-1,6-2, ..., 6-8 installed in the location where condensed water generate | occur | produces is provided. The condensed water collection / discharge device 6-1 is installed downstream of the heat exchanger 27-1, collects condensed water from the anode gas 17, and discharges it. The condensed water recovery / discharge device 6-2 is installed downstream of the fuel cell 20 and recovers and discharges the condensed water from the return anode gas 25. The condensed water recovery / discharge device 6-3 is installed upstream of the fuel processing device 12, and recovers and discharges the condensed water from the return anode gas gas 15. The condensed water recovery / discharge device 6-4 is installed downstream of the fuel cell 20, recovers condensed water from the sword off gas 24, and discharges it. The condensed water collection / discharge device 6-5 is installed downstream of the heat exchanger 27-3, collects condensed water from the cathode off gas 24, and discharges it. The condensed water recovery / discharge device 6-6 is installed upstream of the fuel cell 20, recovers condensed water from the anode gas 17, and discharges it. The condensed water recovery / discharge device 6-7 is installed downstream of the heat exchanger 27-4, recovers condensed water from the anode off gas 25, and discharges it. The condensed water recovery / discharge device 6-8 is installed at the outlet of the fuel gas (anode gas) produced by the fuel processing device 12, collects condensed water from the anode gas 17, and discharges it.

  It should be noted that all of the condensed water recovery / discharge devices 6-1, 6-2,..., 6-8 should preferably be installed. It can be omitted. For example, the condensed water recovery / discharge device 6-1 can be covered by the condensed water recovery / discharge device 6-6, and the condensed water recovery / discharge device 6-1 can be omitted. Further, the condensed water recovery / discharge device 6-3 can cover the condensed water recovery / discharge device 6-7 and omit the condensed water recovery / discharge device 6-7.

  Next, operation | movement of the fuel cell power generation hot water supply system of this embodiment is demonstrated. In the fuel cell power hot water supply system, first, the fuel processing device 12 sends hydrogen-rich gas 17 and air 19 into the fuel cell 20 in a predetermined amount, and generates DC power and heat by an electrochemical reaction. Part of this heat is removed by the fuel cell cooling water system 22, and part of the heat of the remaining cathode exhaust gas 24 is returned again to the cathode air 19 by the heat exchanger 27-3, and the rest is heated from the cathode off-gas 26. It collect | recovers with the exchanger 27-4. At the same time, the anode off gas 25 from the fuel cell 20 is also recovered by the heat exchanger 27-4. From the produced anode gas 17 of the fuel processing apparatus 1 which is another heat source, exhaust heat is recovered by the heat exchanger 11-1. Incidentally, the anode gas 6 at the outlet of the heat exchanger 11-1 is not allowed to deviate greatly from a temperature around 70 ° C. because it enters the fuel cell 9.

  In these heat exchangers 27, the exhaust heat recovery temperature is 100 ° C. or less, and the moisture concentration of the gas is high. Therefore, when exhaust heat is recovered, condensed water is generated. If this condensed water is left unattended, not only the pressure loss in the pipe increases, but also flooding occurs in the fuel cell, leading to a decrease in cell performance. Further, when mixed into the anode return gas 15 and enters the fuel processing device 12, the heat of the combustion gas is taken away, making it difficult to burn, and even if combustion is possible, the temperature is lowered and the exhaust heat recovery rate is reduced.

  Therefore, in this embodiment, the condensed water recovery / discharge devices 6-1, 6-2,... By installing, this problem can be solved easily and the efficiency of the entire system can be improved.

  As described above, according to the present embodiment, it is possible to stably follow the partial load operation at a low cost, and it is possible to perform an economical operation without causing deterioration of the performance of the fuel cell.

Next, the configuration of a fuel cell power hot water supply system according to another embodiment of the present invention will be described with reference to FIG.
FIG. 2 is a system configuration diagram showing the configuration of a fuel cell power hot water supply system according to another embodiment of the present invention. The same reference numerals as those in FIG. 1 indicate the same parts.

  In the present embodiment, the heat exchanger 27-3 is removed from the fuel cell power generation hot water supply system shown in FIG. 1, and the condensate recovery / discharge device 6-5 is removed accordingly. When the flow rate of the cathode air is small, the temperature of the air 19 is raised by conduction heat from the fuel cell 20 through a pipe on the way to the fuel cell 20, so that the configuration shown in FIG.

  As described above, according to the present embodiment, it is possible to stably follow the partial load operation at a low cost, and it is possible to perform an economical operation without causing deterioration of the performance of the fuel cell. In addition, the configuration of the fuel cell power hot water supply system can be simplified.

  The present invention is not limited to the fuel cell system, and can be used for a system in which condensed water is generated and must be recovered and removed.

Next, the 1st structure of the condensed water collection | recovery discharge apparatus used for the fuel cell power generation hot water supply system by each embodiment of this invention is demonstrated using FIG.
FIG. 3 is a configuration diagram showing a first configuration of the condensed water recovery / discharge device used in the fuel cell power hot water supply system according to the embodiment of the present invention.

  The condensed water recovery / discharge device 6 includes a separation chamber 1, a solenoid valve 5, a control device 8, and a water level meter 10. A gas stream containing condensed water flows into the separation chamber 1 from a pipe 2 connected to the upper part, and the condensed water is separated from the gas stream containing condensed water. The gas after removing the condensed water flows out from the pipe 3 connected to the upper part of the separation chamber 1 to move to another part. The pipe 4 is connected to the lower part of the separation chamber 1 and is used for discharging condensed water out of the system. The electromagnetic valve 5 is provided in the lower part of the pipe 4 and is used for discharging condensed water accumulated in the separation chamber 4. The discharged condensed water is sent to a condensed water tank (not shown) or the like through a pipe 7 downstream of the electromagnetic valve 5.

  The pipe 9 for attaching the water level gauge is installed so as to connect the pipe 4 connected to the lower part of the separation chamber 1 and the upper side of the separation chamber 1, and a part or the entire surface thereof is made of a transparent member such as glass or acrylic. . A water level gauge 10 is attached to the water level gauge attachment pipe 9. The water level gauge 10 detects the water level in the separation chamber 1 from the transparent portion of the pipe 9 for attaching the water level gauge, and issues a detection signal. The control device 8 obtains a signal from the water level gauge 10 and controls the opening / closing of the electromagnetic valve 5.

  The solenoid valve 5 is not necessarily a solenoid valve, and may be a pneumatic or fluid pressure actuated valve.

  In the condensed water discharge / recovery device 6 configured as described above, first, a gas flow containing condensed water flowing out from a heat exchanger (not shown) or the like passes through the pipe 2 and enters the separation chamber 1. The cross-sectional area of the separation chamber 1 is 10 times or more the cross-sectional area of the pipe 2, and the flow velocity of the gas flow entering the separation chamber 1 is reduced to 1/10 or less. And it makes it lower than the free fall speed of a condensed water droplet. When the droplet size is 1 mm, the free fall velocity is 400 cm / s, and when the droplet size is 2 mm, the free fall velocity is 600 cm / s. Therefore, when the flow rate flowing through the pipe 2 is 300 cm / s, if the cross-sectional area of the separation chamber 1 is 10 times or more the cross-sectional area of the pipe 2, the flow rate of the gas flow entering the separation chamber 1 is 1/10 or less. It becomes 30 cm / s, and the droplet and the gas can be completely separated. In the separation chamber 1, the pipe 2 is provided in the vertical direction, and the liquid droplet moves downward while the gas flow moves upward. It is 180 degrees different from the drop direction of the droplet. Thus, by changing the flow direction of the gas flow and the direction of the liquid droplets, it is possible to easily separate them. At this time, if the flow direction of the gas flow and the falling direction of the droplets are changed by 90 degrees or more, the separation performance of the condensed water is improved. As a result, the gas flow from which the condensed water has been separated stays in the separation chamber 1 for a time sufficient for the condensed water droplets to fall, rises in the separation chamber 1 and exits the separation chamber 1 from the pipe 3. Head for the part. At that time, the condensed water separated from the gas flow is accumulated in the lower part of the separation chamber 1.

  The water level of the condensed water accumulated in the lower part of the separation chamber 1 is optically or electrically detected by the water level gauge 10 through the water level gauge mounting pipe 9. When the water level reaches a predetermined level, a water level detection signal from the water level gauge 10 is input to the control device 8. When the control device 8 receives the detection signal from the water level gauge 10, it sends an open signal to the electromagnetic valve 5, the electromagnetic valve 5 is opened, and the accumulated condensed water is discharged. When the condensed water is discharged and the detection signal of the water level meter is turned off, a closing signal is sent from the control device 8 and the electromagnetic valve 5 is closed. At this time, the gas in the system, the valve opening / closing part and the seal part are not in direct contact with each other through the water, leaving a small amount without completely eliminating condensed water at the lower part of the separation chamber. Then, the system is operated so as not to contact the gas inside and outside the system.

  When the detection signal of the water level meter 10 is turned on, the electromagnetic valve 5 is opened. When the detection signal is turned off, the electromagnetic valve 5 is closed. When the detection signal is turned on, the solenoid valve 5 may be opened and the solenoid valve 5 may be closed after elapse of a predetermined time using a timer or the like.

  In addition, as a condensate drainage device, the use of a float type condensate drainage device used in steam pipes and the like was also examined, but the flow rate is extremely small as in a domestic fuel cell system, and gas When the pressure is almost normal pressure, the pressure for pressing the float against the seal is small, and there is a possibility that a slight amount of gas leakage may occur. In an apparatus that handles gas containing hydrogen gas, although the amount of gas is very small, it is necessary to steadily consider safety. In that respect, gas leakage can be effectively prevented by leaving a certain amount of water remaining in the lower part of the separation chamber and sealing it as in this embodiment.

  As described above, since the condensed water is discharged by opening and closing the solenoid valve by measuring the accumulated amount of condensed water, the gas is not released out of the system regardless of the increase or decrease of the condensed amount due to the partial load following operation, It can be operated reliably without air outside the system. Therefore, since the generated condensed water can be effectively recovered and drained to prevent gas leakage and air mixing, a safe and highly efficient system can be obtained.

Next, the 2nd structure of the condensed water collection | recovery discharge apparatus used for the fuel cell power generation hot water supply system by each embodiment of this invention is demonstrated using FIG.
FIG. 4 is a configuration diagram showing a second configuration of the condensed water recovery / discharge device used in the fuel cell power hot water supply system according to the embodiment of the present invention. In addition, the same code | symbol as FIG. 3 has shown the same part.

  In this example, a water level gauge 11 is added to the configuration of FIG. When condensed water accumulates and exceeds the set water level of the water level gauge 11, a signal is sent from the water level gauge 11 to the control device 8, and the electromagnetic valve 5 is opened by the control device 8 based on the signal. As a result, when the condensed water is discharged and the water level drops and falls below the set water level of the water level meter 10, a signal is sent from the water level meter 10 to the control device 8, and the control device 8 closes the solenoid valve 5 by the signal. Do. As a result, the gas in the system and the valve opening / closing part and the seal part do not directly contact with each other through the water, leaving a small amount without completely eliminating condensed water at the lower part of the separation chamber. Thus, since a certain amount of condensed water can be retained as a sealing material, a safer system can be constructed.

With the above configuration, the generated condensed water can be effectively recovered and drained to prevent gas leakage and air mixing, so that a safe and highly efficient system can be obtained.

1 is a system configuration diagram showing a configuration of a fuel cell power hot water supply system according to an embodiment of the present invention. It is a system block diagram which shows the structure of the fuel cell power generation hot water supply system by other embodiment of this invention. It is a block diagram which shows the 1st structure of the condensed water collection | recovery discharge apparatus used for the fuel cell power generation hot water supply system by one Embodiment of this invention. It is a block diagram which shows the 2nd structure of the condensed water collection | recovery discharge apparatus used for the fuel cell power generation hot water supply system by one Embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Separation chamber 2 ... Piping 3 ... Piping 4 ... Piping 5 ... Solenoid valve 6 ... Condensate collection / discharge device 7 ... Piping 8 ... Control device 9 ... Piping for water level meter 10 ... Water level meter 11 ... Water level meter 12 ... Fuel processing Equipment 13 ... City gas 14 ... Air 15 ... Return anode gas 17 ... Anode gas 18 ... Combustion exhaust gas 19 ... Cathode air 20 ... Fuel cell 21 ... Water tank 22 ... Fuel cell cooling water system 24 ... Cathode exhaust gas 25 ... Anode exhaust gas 26 ... Cathode Exhaust gas 27 ... Heat exchanger 28 ... Valve 29 ... Tap water

Claims (8)

In a fuel cell power generation and hot water supply system having a fuel processing device and a fuel cell,
A fuel cell power generation hot water supply system comprising a condensate recovery / discharge device at a position having a high water vapor concentration in the anode gas line and the cathode gas line in and out of the fuel cell. In the fuel cell power generation hot water supply system according to claim 1,
The condensate recovery and discharge device is provided in a part or all of the heat exchanger outlets of the anode gas line and the cathode gas line. In the fuel cell power generation hot water supply system according to claim 1,
The condensate recovery and discharge device is provided immediately before the outlet of the fuel gas (anode gas) produced by the fuel processing device and the return port of the return anode gas to the fuel processing device. Hot water system. In the fuel cell power generation hot water supply system according to claim 1,
The condensate recovery / discharge device is provided at a part or all of a cathode exhaust gas outlet, an anode gas inlet, or an anode exhaust gas outlet of the fuel cell. In the fuel cell power generation hot water supply system according to any one of claims 2 to 4,
The condensed water collecting / discharging device has a configuration in which the gas flow rate is reduced to be equal to or lower than the free falling speed of the condensed water droplets, and the flow direction of the gas flow is made different from the falling direction of the condensed water. Fuel cell power hot water supply system. In the fuel cell power generation hot water supply system according to any one of claims 2 to 4,
The condensed water recovery / discharge device includes a valve installed at the bottom or lower part of the separation chamber,
A fuel cell characterized in that a part of condensed water remains at the bottom of the separation chamber and is used as a sealing material to discharge recovered condensed water without leaking gas in the system and without mixing gas outside the system. Power generation hot water system. In the fuel cell power generation hot water supply system according to claim 6,
The condensate recovery and discharge device is provided with a water level meter and a control means for opening and closing the valve based on a signal from the water level meter. In the fuel cell power generation hot water supply system according to claim 6,
The condensate recovery and discharge device is provided with a fuel cell power hot water supply system comprising a plurality of water level gauges and a control means for opening and closing the valve based on signals from these water level gauges.

Images