JP2002042841A - Polymer electrolyte type fuel cell cogeneration system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To dispense with a heating means necessary only in starting in a cooling water system for a fuel cell, to reduce the ionization tendency of cooling water in power generation operation, and to miniaturize a cogeneration system. SOLUTION: This cogeneration system is provided with a polymer electrolyte fuel cell generating power using fuel gas and oxidizing agent gas, an inner circulating circuit circulating an inner heat transport medium to the fuel cell, an inner circulating means circulating the inner heat transport medium, a heat exchange means exchanging the heat of the outer heat transport medium with that of the inner heat transport medium, a heat utilization means storing the recovered waste heat of the fuel cell, and a waste heat transport control means. This cogeneration system is so constituted that the waste heat transport control means allows the outer heat transport medium heat-exchanged by the heat exchange means to recover the waste heat, allows the heat utilization means to store it, and transports the waste heat recovered in starting the fuel cell to the fuel cell.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a cogeneration system.

[0002]

2. Description of the Related Art A conventional power generator using a polymer electrolyte fuel cell will be described with reference to the configuration diagram of FIG. In FIG. 5, reference numeral 1 denotes a fuel cell unit, and a fuel processing unit 2 performs steam reforming of a raw material such as natural gas, generates a gas containing hydrogen as a main component, and supplies the gas to the fuel cell 1. The fuel processor 2 includes a reformer 3 for generating a reformed gas, and a carbon monoxide converter 4 for reacting carbon monoxide contained in the reformed gas with water to produce carbon dioxide and hydrogen. ing. The fuel humidifier 5 humidifies the fuel gas supplied to the fuel cell 1. Reference numeral 6 denotes an air supply device, which supplies air of an oxidant to the fuel cell 1. At this time, the supply air is humidified by the oxidizing humidifier 7. Further, an internal circulation circuit for sending water to the fuel cell 1 for cooling, a pump 9 for circulating water in the internal circulation circuit, a cooling radiator 10 for releasing heat generated in the fuel cell 1 to the outside, A heater (heater or the like) 11 for heating water in the internal circulation circuit;

When power is generated using such a device,
In order to prevent the fuel cell 1 from being poisoned with carbon monoxide by a trace amount of carbon monoxide in the reformed gas converted in the carbon monoxide converter 4, it is necessary to keep the temperature of the fuel cell 1 constant. In addition, water is circulated by a pump 9 through a cooling pipe 8, and heat generated in the fuel cell 1 is released to the outside by a radiator 10 for cooling. When the temperature of the fuel cell 1 is raised from the ambient temperature, such as when the fuel cell 1 is started, the heater 11 heats the fuel cell 1 to a temperature suitable for normal operation of the fuel cell (about 70 to 80 ° C.).

[0004]

In the above-mentioned conventional configuration, it is necessary to heat the fuel cell 1 at the time of starting. Further, since the heater 11 is provided in a cooling pipe system of the fuel cell and is composed of a container having a fixed volume and a built-in heater and the like, it is difficult to reduce the size and rationalization of the fuel cell device.

When a heater having a built-in heater is used in the cooling pipe system of the fuel cell 1, if a metal is used for the heater or the container with a built-in heater, corrosion or metal may be removed from a metal joint or a surface depending on the operation time. There has been a problem that the cooling water is ionized due to ion precipitation or the like, and the electric conductivity increases, which hinders the power generation of the fuel cell.

In general, an exhaust heat recovery device for recovering exhaust heat from a cogeneration device is guided by a pipe or the like, and the cogeneration device and the exhaust heat recovery device are separately installed. Heat loss occurred not only in the piping but also in each of the combined heat and power supply device and the exhaust heat recovery device, and the exhaust heat recovery efficiency was reduced. In addition, there is a problem that an installation place for both the cogeneration system and the exhaust heat recovery apparatus is required, and there is a restriction that the installation can be performed only in a house having a sufficient installation place in an urban area or the like.

[0007]

Means for Solving the Problems To solve the above problems, a cogeneration system according to the present invention comprises a polymer electrolyte fuel cell for generating electric power using a fuel gas and an oxidizing gas, and an internal fuel cell. An internal circulation circuit for circulating the heat transport medium,
An internal circulation means for circulating the internal heat transport medium, a heat exchange means for exchanging heat of the internal heat transport medium with an external heat transport medium, and an external heat transport medium heat-exchanged by the heat exchange means And a waste heat transport control means for recovering and storing the waste heat in the heat utilization means and transporting the waste heat recovered by the heat utilization means to the fuel cell when the fuel cell is started.

Further, the thermoelectric supply device of the present invention includes a heat conducting means for heat conducting coupling between the fuel cell and the heat utilization means,
Here, the fuel cell, the heat utilization means, and the heat conduction means are included in heat insulation means.

With the above configuration, when the polymer electrolyte fuel cell system is started, the external heat transport medium is transported in a direction opposite to that in the recovery of the exhaust heat, and the exhaust heat already recovered by the heat utilization means is discharged. By heating and circulating the internal heat transport medium of the fuel cell through the heat exchange means by the control means,
The temperature of the fuel cell can be raised.

[0010]

Embodiments of the present invention will be described below with reference to the drawings.

(Embodiment 1) FIG. 1 is a block diagram of a cogeneration system according to an embodiment of the present invention. The cogeneration system includes a polymer electrolyte type fuel cell 1 that generates electric power using a fuel gas and an oxidizing gas, and a fuel processing device 2 that generates a fuel gas by steam reforming and carbon monoxide conversion of a raw material fuel. A humidifier 5 for humidifying a fuel gas supplied to the fuel cell 1, an air supply device 6 for supplying air of an oxidant to the fuel cell 1, and an oxidizing humidifier 7 for humidifying supply air
Are configured as a gas system necessary for power generation of the fuel cell 1.

The fuel processor 2 includes a reformer 3 that reforms a raw fuel by steam to generate a reformed gas mainly composed of hydrogen.
It comprises a carbon monoxide converter 4 which converts carbon monoxide contained in the reformed gas and supplies it to the fuel cell 1 as a fuel gas.

The internal heat transport system for controlling the temperature of the fuel cell 1 by sending an internal heat transport medium such as antifreeze to the fuel cell 1 includes a cooling pipe 8 and an internal heat transport medium in the cooling pipe 8. Heat exchange means such as a pump 9 for causing heat, a radiator 10 for releasing heat generated in the fuel cell 1 to the outside, and a heat exchanger for exchanging heat of the internal heat transport medium flowing through the cooling pipe 8 with the external heat transport medium. 12 and flow control valves 13 and 14 as flow control means for controlling the flow rate of the internal heat transport medium flowing through the radiator 10 and the heat exchange means 12.

The external heat transport system for recovering the exhaust heat of the fuel cell by the external heat transport medium (such as city water) heat-exchanged by the heat exchange means 12 includes an exhaust heat recovery pipe 15a,
Exhaust heat from the heat exchange means 12 is stored in a heat utilization means 16 (a tank as a hot water supply terminal, hereinafter referred to as a hot water storage tank) such as a hot water storage tank via the heat exchange means 15b, and at the time of starting the fuel cell, in a direction opposite to the time of exhaust heat recovery Heat transfer control means 17 for transferring heat from the external heat transfer medium to the fuel cell 1 through the heat exchange means 12 and transferring the waste heat recovered by the heat utilization means 16 (the flow direction is changed by forward and reverse rotation to change the outflow direction). A fluid transporting means having a pump for inverting (hereinafter referred to as a forward / reverse pump) and varying the flow rate.

In order to control the flow rate of the external heat transport medium, a heat exchanger inlet temperature detecting means 18 (hereinafter referred to as a heat exchanger inlet thermistor 18) is provided at the inlet and outlet of the heat exchanger 12 respectively.
) And a heat exchanger outlet temperature detecting means 19 (hereinafter, referred to as a heat exchanger outlet thermistor 19), and are connected to output a detection signal to the exhaust heat transport control means 17.

The components described above are given the same reference numerals as those of the conventional power generating device shown in FIG. 5, and those functions are described in detail in the conventional power generating device shown in FIG. According to Further, the cooling pipe 8, the pump 9, the radiator 10, the heat exchange means 12, and the flow control valves 13 and 14 constitute an internal circulation circuit of the present embodiment.

Next, the operation and operation will be described. During operation (power generation) of the cogeneration system, the flow control valve 13 is closed,
14, the heat generated by the fuel cell is circulated through the pump 9 by the internal heat transport medium (antifreeze, etc.), and the external heat transport medium (city water, etc.) by the heat exchange means 12.
Heat transfer. Heat utilization means 16 (hereinafter, hot water storage tank 1
6), the heat exchanged by the exhaust heat transport control means 17 with the external heat transport medium is recovered through the exhaust heat recovery pipes 15a and 15b.

When the cogeneration system is started, the flow control valve 13
Is closed and 14 is opened, the internal heat transport medium of the fuel cell is circulated by the pump 9, and the exhaust heat transport control means 17 reverses the circulation direction of the external heat transport medium during operation (power generation) and transports it. .

As described above, in the present invention, the hot water storage tank 16
The heat stored during operation in the exhaust heat recovery pipes 15a, 15
The temperature of the fuel cell 1 can be raised by heat-transferring to the fuel cell 1 side via the heat exchange means 12 and b.

At this time, the circulating flow rate of the external heat transport medium by the exhaust heat transport control means 17 depends on the heat exchanger outlet thermistor 1
9 so that the temperature of the external heat transfer medium after the heat exchange by the heat exchange means 12 becomes sufficiently low, that is, by the difference between the return temperature to the hot water storage tank 16 and the temperature of the fluid (such as city water) below the hot water storage tank 16. The flow rate is controlled so that convection in the tank 16 does not occur.

Therefore, in the present embodiment, the heat exchanger inlet thermistor 18 at the time of power generation causes a predetermined hot water storage temperature (6
0 to 80 ° C.), the hot water stored in a stacked state from the upper part of the hot water storage tank 16 by the forward rotation operation of the exhaust heat transport control means 17 is operated in the reverse rotation operation of the exhaust heat transport control means 17 at startup. Thereby, the hot water is maintained without convective mixing with the lower cold water and without lowering the hot water storage temperature.

The waste heat of the combined heat and power supply is used as heat utilizing means 1.
When it is no longer necessary to recover the heat through the fuel cell 1, the heat generated in the fuel cell 1 is radiated by opening the flow control valve 13 and closing the flow control valve 14 and activating the radiator 10 to thereby reduce the internal heat. The transport medium can exchange heat with the outside air and release heat to the outside. At this time, by controlling the performance of the radiator 10, the temperature of the internal heat transport medium can be controlled within a predetermined temperature range.

(Embodiment 2) FIG. 2 is a block diagram of a cogeneration system according to Embodiment 2 of the present invention. Components having the same functions as those of the power generating apparatus in FIG. 1 are denoted by the same reference numerals, and details of their configurations and functions are the same as in the first embodiment.

In FIG. 2, the exhaust heat transport control means 17 comprises:
An external heat transport medium circulating means (hereinafter, referred to as a circulation pump 20) provided in a path of the exhaust heat recovery pipes 15a, 15b, and a flow path switching means (hereinafter, referred to as a circulating pump) for switching a flow path of the external heat transport medium.
Flow path switching valves 21 and 22) and branch joints 23 and 2
4 is provided. During exhaust heat recovery, the flow rate of the circulation pump 20 is controlled to store hot water in a stacked manner from the top of the hot water storage tank 16, and when the fuel cell 1 is started, the flow path switching valve 21
The flow path of the external heat transport medium (water or the like) is switched via 22, and the hot water in the hot water storage tank 16 is connected to the heat exchange means 12.

With this configuration, at the time of exhaust heat recovery, the exhaust heat transport control means switches the flow path of the exhaust heat recovery pipe via the flow path switching means and controls the flow rate of the external heat transport medium circulating means to store hot water. Hot water can be stored in a stacked manner from the upper part of the tank, and the temperature of the hot water can be ensured at a high temperature (about 60 to 80 ° C.) in a normal piping configuration in which a hot water supply pipe opening is taken out from the upper part of the hot water storage tank. In addition, even when the hot water tank is used up and the hot water runs out, the required minimum hot water storage amount can be secured in a short time. Therefore, hot water of an available temperature can be obtained in a short time as compared with a case where the temperature of the entire tank is uniformly increased.

When the fuel cell is started, the flow path is switched by the flow path switching means in a direction opposite to the direction in which the exhaust heat is recovered, so that the external heat transport medium circulating means operates without changing its transport direction, and the hot water storage tank is opened. The temperature of the fuel cell can be raised from above via the exhaust heat recovery pipe and the heat exchange means.

Next, the operation and operation will be described. During operation (power generation) of the cogeneration system, the flow control valve 13 is closed,
When 14 is opened, the heat generated by the fuel cell is circulated by the internal heat transport medium (such as antifreeze) through the pump 9, and the heat is exchanged by the heat exchange means 12 to the external heat transport medium. The exhaust heat transport control means 17 is controlled by an internal circulation pump 20.
The external heat transport medium (city water) sucked from the lower part of the hot water storage tank 16 is heat-exchanged by the heat exchange means (heat exchanger) 12,
The hot water is stored in a stacked state from the top of the hot water storage tank 16. At this time,
The flow path switching valves 21 and 22 are switched so that the flow path of the external heat transport medium flowing inside the exhaust heat recovery pipes 15a and 15b is in the direction of A in FIG.

When the cogeneration system is started, the flow control valve 1
3 is closed, 14 is opened, the internal heat transport medium of the fuel cell is circulated through the pump 9, and the exhaust heat transport control means 17 reverses the circulation direction of the external heat transport medium during operation (power generation). (B direction in FIG. 2) The medium is transported. In other words, the waste heat transport control means 17 circulates the hot water whose heat has already been recovered from the upper part of the hot water storage tank 16 by the internal circulation pump 20 in the opposite direction to that at the time of the waste heat recovery, and causes the heat exchange means 12 to exchange heat. .
At this time, the flow path switching valves 21 and 22 are switched so that the flow path of the external heat transport medium flowing inside the exhaust heat recovery pipes 15a and 15b is in the direction of B in FIG.

At this time, the circulating flow rate of the external heat transport medium by the exhaust heat transport control means 17 depends on the heat exchanger outlet thermistor 1
9 so that the temperature of the external heat transport medium after the heat exchange by the heat exchange means 12 becomes sufficiently low, that is, the difference between the temperature of returning to the hot water storage tank 16 and the temperature of the fluid (city water) below the hot water storage tank 16. The flow rate is controlled so that convection within 16 is not generated.

Therefore, in the present embodiment, the heat exchanger inlet thermistor 18 is used to operate the waste heat transport control means 17 (power generation) so that the predetermined temperature (about 60 to 80 ° C.) is reached by the heat exchanger inlet thermistor 18 during power generation. The hot water stored in a stacked state from the upper portion of the tank 16 does not convectively mix with the lower cold water by the reverse operation of the exhaust heat transport control means 17 at the time of starting the fuel cell, so that the hot water storage temperature does not drop.

(Embodiment 3) FIG. 3 is a block diagram showing the configuration of a cogeneration system according to Embodiment 3 of the present invention. Components having the same functions as those of the power generating apparatus in FIG. 1 are denoted by the same reference numerals, and details of their configurations and functions are in accordance with Embodiments 1 and 2 of the present invention.

In FIG. 3, a lower portion of a polymer electrolyte fuel cell 1 for generating electric power using a fuel gas and an oxidizing gas is provided below.
A heat utilization means 16 (hereinafter, referred to as a hot water storage tank) for storing recovered exhaust heat of the fuel cell is provided, and a heat conduction means (an aluminum sheet or the like) between the fuel cell 1 and the heat utilization means 16 for thermally conducting the two. 25 is sandwiched.

Further, a heat exchange means 12 such as a heat exchanger for exchanging the exhaust heat of the fuel cell with the external heat transport medium is provided near the fuel cell 1, and the exhaust heat recovery pipes 15a and 15b are provided from the heat exchange means 12. Is connected to the hot water storage tank 16 so as to store waste heat water as an external heat transport medium by waste heat transport control means (constituted by a circulating pump or the like) 17. The fuel cell 1, the heat exchange means 12, the hot water storage tank 16, and the heat conduction means 25 are attached so that the heat insulation means (such as glass wool) 26 is included.

The cooling pipe 8, the pump 9, the radiator 1
0, an internal circulation circuit such as a heat exchange means 12 and flow rate regulating valves 13 and 14, a reformer 3 for producing a reformed gas mainly composed of hydrogen by steam reforming a raw material fuel, and a reformed gas. A fuel processing device 2 comprising a carbon monoxide converter 4 which converts carbon monoxide and supplies it to the fuel cell 1 as a fuel gas
Although not shown, is disposed near the hot water storage tank 16 and is connected to the fuel cell 1.

According to this structure, the heat utilization means for storing the exhaust heat recovered from the fuel cell is thermally tightly connected to the fuel cell by the heat conduction means, so that when the operation of the fuel cell is stopped, the heat utilization of the heat utilization means is reduced. The heat insulation means greatly reduces the heat dissipation loss and shortens the startup time at the time of startup.

Next, the operation and operation will be described. During operation (power generation) of the cogeneration system, heat generated by the power generation of the fuel cell is transferred by the heat exchange means 12 to an external heat transport medium (city water). The hot water storage tank transfers the heat exchanged to the external heat transport medium by the exhaust heat transport control means 17 to the exhaust heat recovery pipe 15.
Exhaust heat is recovered via a and 15b.

When the cogeneration system is started, the heat transfer control means 17 causes the external heat transport medium to be transported by reversing the direction of circulation of the external heat transport medium during operation (power generation). Accordingly, the temperature of the fuel cell 1 is increased by transferring the heat stored in the hot water storage tank 16 during operation to the fuel cell 1 through the exhaust heat recovery pipes 15a and 15b and the heat exchange means 12.

The hot water storage tank 16 for storing the exhaust heat recovered from the fuel cell 1 is thermally tightly connected to the fuel cell 1 by the heat conducting means 25 so that the standby temperature is kept low even when the operation of the fuel cell 1 is stopped. It is difficult to cool down due to the conduction heat of the hot water stored in the hot water storage tank 16 from the upper portion, and the start-up time at the time of startup is extremely reduced.

Further, compared with the case where the fuel cell 1 and the hot water storage tank 16 are separately installed, the exhaust heat recovery pipe can be stored in the apparatus shorter, and the exhaust heat recovery pipes 15a and 15b, the fuel cell 1, and the hot water storage tank can be stored. 16 can also reduce the heat loss from each, and the exhaust heat recovery efficiency improves. In addition, since the fuel cell 1 and the hot water storage tank 16 are stacked vertically, the installation area of both the fuel cell 1 and the hot water storage tank 16 is not required.

(Embodiment 4) FIG. 4 is a block diagram of a cogeneration system according to Embodiment 4 of the present invention. Components having the same functions as those of the power generating apparatus in FIG. 1 are denoted by the same reference numerals, and details of their configurations and functions are in accordance with Embodiments 1, 2, and 3 of the present invention. Although not shown, the internal circulation circuit and the fuel processor 2 are disposed near the hot water storage tank 16 and connected to the fuel cell 1 as in the third embodiment of the present invention.

The hot water storage tank 16 and the fuel cell 1 are buried at a predetermined depth from the ground surface 28 without being squeezed from external pressure by the outer case 27. Therefore, since the surroundings are surrounded by soil having a large heat capacity and heat storage properties, the heat radiation loss of the entire cogeneration system can be greatly reduced.

In view of the maintainability of the cogeneration system, the hot water storage tank 16 and the fuel cell 1 are raised by a jack mechanism (not shown) under the hot water storage tank 16 at the time of maintenance so that fault diagnosis can be performed. If the exhaust heat transport pipes and the like are connected by a flexible material, the fuel cell device has good repairability.

As described above, in the present embodiment, the hot water storage tank as the heat utilization means is buried underground, so that the occupied installation area and the ground volume as the cogeneration system can be further reduced, and the heat storage capacity with a large heat capacity is improved. Since the surroundings are surrounded by the soil, the heat loss of the entire cogeneration system can be reduced.

The operation and operation are the same as in the third embodiment of the present invention.

[0045]

As described above, according to the present invention, a part of the exhaust heat stored in the heat utilization means as the exhaust heat recovery device is used only at the time of starting the fuel cell. Provided is a simple and rational configuration of a cogeneration system that can ensure the operation of a fuel cell at a high temperature and has improved exhaust heat recovery efficiency. The cogeneration system of the present invention can prevent the performance of a fuel cell from deteriorating due to carbon monoxide poisoning, and has a configuration using a metal heater or a container as a heater having a built-in heater in a cooling piping system of the fuel cell. Since this does not take place, it is possible to reduce problems such as a decrease in fuel cell power generated due to an increase in electric conductivity due to ionization of the cooling water according to the operation time.

[Brief description of the drawings]

FIG. 1 is a block diagram of a cogeneration system according to a first embodiment of the present invention.

FIG. 2 is a block diagram of a cogeneration system according to Embodiment 2 of the present invention;

FIG. 3 is a block diagram of a cogeneration system according to a third embodiment of the present invention;

FIG. 4 is a block diagram of a cogeneration system according to a fourth embodiment of the present invention;

FIG. 5 is a configuration diagram showing a power generation device using a conventional polymer electrolyte fuel cell.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Fuel cell 2 Fuel processor 3 Reformer 4 Carbon monoxide converter 5 Fuel humidifier 6 Air supply device 7 Oxidation humidifier 8 Internal circulation circuit 9 Internal circulation means 10 Heat radiator 12 Heat exchange means 13,14 Flow rate Control valves 15a, 15b Exhaust heat recovery pipe 16 Heat utilization means (hot water storage tank) 17 Exhaust heat transport control means 20 External heat transport medium circulation means 21, 22 Flow path switching means 25 Heat conduction means 26 Thermal insulation means

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Yoshiaki Yamamoto, Inventor 1006 Kadoma Kadoma, Kadoma City, Osaka Prefecture Matsushita Electric Industrial Co., Ltd. Terms (reference) 5H026 AA06 5H027 AA06 BA01 BA17 DD06 MM16

Claims (4)

[Claims] 1. A polymer electrolyte fuel cell that generates power using a fuel gas and an oxidizing gas, an internal circulation circuit that circulates an internal heat transport medium to the fuel cell, and circulates the internal heat transport medium. Combined heat and power supply comprising: internal circulation means; heat exchange means for exchanging heat of the internal heat transport medium with an external heat transport medium; heat utilization means for storing recovered exhaust heat of the fuel cell; and exhaust heat transport control means. An apparatus, wherein the exhaust heat transport control means recovers exhaust heat by an external heat transport medium heat-exchanged by the heat exchange means, stores the exhaust heat in heat utilization means, and when the fuel cell starts up, the exhaust heat recovered. A cogeneration system for transferring heat to the fuel cell. 2. The exhaust heat transport control means includes: an external heat transport medium circulating means in a path of an exhaust heat recovery pipe; and a flow path switching means for switching a flow path of the external heat transport medium. Is water, the heat utilization means is a hot water storage tank, and at the time of exhaust heat recovery, hot water is stored in a stacked manner from the top of the hot water storage tank by controlling the flow rate of the external heat transport medium circulation means,
2. The combined heat and power supply apparatus according to claim 1, wherein, when the fuel cell is started, the flow path of the external heat transport medium is switched by the flow path switching means, and the hot water in the hot water storage tank is transported to the heat exchange means. 3. The fuel cell system according to claim 1, further comprising a heat conducting means for thermally conducting coupling between the fuel cell and the heat utilizing means, wherein the fuel cell, the heat utilizing means and the heat conducting means are included in a heat insulating means. Cogeneration unit. 4. A hot water storage tank in which the heat utilization means is buried underground, an external heat transport medium circulating means is provided in a path of the exhaust heat recovery pipe, and a flow rate of the external heat transport medium circulating means is controlled to control the flow rate of the external heat transport medium circulating means. The combined heat and power supply device according to claim 3, further comprising a waste heat transport control unit that stores the hot water in a more stacked shape.