JP2005332604A - Fluid heating system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a fluid heating system capable of suitably heating fluid like water by efficiently utilizing heat generated at a fuel cell and a reformer. <P>SOLUTION: The fluid heating system comprises a case 10 having an outside space 11A with water circulating inside, composed of an external case 11 and an internal case 12; an FC stack 4; a reformer supplying hydrogen to the FC stack 4; and a heat exchanger 7 connected to a downstream side of the FC stack 4 and the reformer 3, exchanging heat between cathode off-gas, reformer exhaust gas, and water. The fluid heating system is characterized by arranging the FC stack 4, the reformer 3, and the heat exchanger 7 in the case 10. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a fluid heating system that heats a fluid such as water using heat generated in a fuel cell and / or a reformer.

  In recent years, fuel cells have been actively developed as household power supplies and industrial power supplies. A fuel cell generates electric power and heat. Thus, a system for recovering and using heat has been proposed in order to increase energy efficiency during operation of the fuel cell. For example, it is a hot water supply system that uses this heat to heat water and provide hot water (see Patent Document 1 and Patent Document 2).

  As shown in FIG. 3, a conventional hot water supply system 101 includes a fuel cell unit 101A (hereinafter referred to as an FC unit) and a hot water storage tank 101B attached to the fuel cell unit 101A. The FC unit 101A mainly includes a reformer 103 that generates hydrogen from fuel gas such as city gas and LPG, water and air, and a fuel cell stack 104 (hereinafter referred to as an FC stack) formed by stacking fuel cells. The heat exchanger 107 that heats water using the heat of the reformer 103 and the FC stack 104 and the inverter 108 are configured.

  When the hot water supply system 101 is operated, the FC stack 104 generates electricity by causing the hydrogen supplied from the reformer 103 and oxygen in the air to act to generate electric power. This electric power is guided to the output terminal 108a through the inverter 108. As the electric power is generated, the FC stack 104 generates heat, and the cathode off gas, which is part of the heat, is discharged from the cathode side (fuel electrode side) of the FC stack 104. And this cathode off gas is discharged | emitted outside via the piping 104f. Further, the FC stack 104 is maintained at a predetermined temperature by a cooling medium that flows through a pipe 105b having a circulation pump at an intermediate position. Furthermore, the exhaust gas having the operating heat (hereinafter referred to as reformer exhaust gas) is discharged from the reformer 103 to the outside through the pipe 103f.

The heat exchanger 107 has a part of the pipe 121f that has a part of the pipe 103f, a part of the pipe 104f, a part of the pipe 105b, and a circulation pump 121a in the middle, and circulates the water in the hot water storage tank 101B. And a portion.
Therefore, by operating the circulation pump 121a during the power generation of the FC stack 104, the heat of the reformer exhaust gas flowing through the pipe 103f, the heat of the cathode offgas flowing through the pipe 104f, and the cooling medium flowing through the pipe 105b This heat is transferred to the water flowing through the pipe 121 so that the water can be heated to a predetermined level and returned as hot water to the hot water storage tank 101B.
In this way, the water in the hot water storage tank 101B can be heated to a predetermined level and stored as hot water in the hot water storage tank 101B.
JP 2002-289242 A (0015-0029, FIG. 1) JP 2002-289234 A (0011-0022, FIG. 1)

However, the hot water supply system 101 has a problem that heat loss occurs because the heat generated in the reformer 103 and the FC stack 104 is recovered through the heat exchanger 107 disposed between them. That is, since the reformer 103 and the FC stack 104 are separated from the hot water storage tank 101B, the radiant heat radiated from the reformer 103 and the FC stack 104 cannot be used.
Moreover, in order to circulate the water in the hot water storage tank 101B, the circulation pump 121a must be provided as a power source, which is a cause of deterioration in energy efficiency of the hot water supply system 101.

  Therefore, in order to solve the above problems, the present invention aims to provide a fluid heating system that efficiently uses heat generated in a fuel cell and a reformer and can suitably heat a fluid such as water. And

  As means for solving the above-mentioned problems, the present invention comprises a housing having a space through which a fluid flows and a heating element comprising at least one of a fuel cell and a reformer that supplies hydrogen to the fuel cell. A fluid heating system provided, wherein the heating element is arranged in the housing.

  According to such a fluid heating system, since the heating element including at least one of the fuel cell and the reformer is disposed in the casing, the radiant heat generated from the heating element includes a power source such as a circulation pump. Without being transmitted to the fluid flowing through the inside of the housing, heat loss is less likely to occur. Therefore, it is possible to efficiently use the heat generated by the heating element composed of at least one of the fuel cell and the reformer to heat the fluid.

  ADVANTAGE OF THE INVENTION According to this invention, the fluid heating system which utilizes heat efficiently and enables fluids, such as water, to be heated suitably can be provided.

  Next, an embodiment of the present invention will be described in detail with reference to FIG. FIG. 1 is a diagram illustrating a configuration of a hot water supply system according to the present embodiment.

≪Configuration of hot water supply system≫
As shown in FIG. 1, a hot water supply system 1 (fluid heating system) according to the present embodiment uses water as a fluid in claims and uses heat generated in the reformer 3 and the FC stack 4 to produce water. It is a system to heat. The hot water supply system 1 mainly includes a housing 10, a reformer 3 and an FC stack 4 that are heating elements, and a heat exchanger 7.
In the present embodiment, the exhaust fluid in the claims corresponds to the reformer exhaust gas discharged from the reformer 3 and the cathode off-gas discharged from the FC stack 4.

<Housing>
The casing 10 includes an outer casing 11 having a hollow inside and a cylindrical outer shape, and an inner casing 12 disposed inside and hollow inside and having a cylindrical outer shape. That is, the housing 10 has a double structure of a space 11 </ b> A (hereinafter referred to as an outer space) formed between the outer housing 11 and the inner housing 12 and a cavity in the inner housing 12. A pipe 11a serving as an inlet for water is provided at the lower part of the outer casing 11, and a pipe 11b serving as an outlet for heated water (that is, hot water) is provided at the upper part of the outer casing 11, respectively. Has come to circulate. The upstream side of the pipe 11a is connected to a water source such as a water supply via an on-off valve (not shown), and the downstream side of the pipe 11b uses hot water such as a bathtub via an on-off valve (not shown). Connected to the equipment. Therefore, hot water can be stored in the outer space 11A by operating the two on-off valves.
The inner casing 12 has a partition wall 12a therein, and the cavity is divided into an upper chamber 12A and a lower chamber 12B. The outer casing 11 and the inner casing 12 are preferably formed from a material having high thermal conductivity and corrosion resistance.

<Reformer>
The reformer 3 is a device that generates hydrogen and is disposed in the lower chamber 12B. On the upstream side of the reformer 3, a pipe 3a for introducing a fuel gas such as city gas and LPG, a pipe 3b for introducing water, and a pipe 3c for introducing air are respectively connected. Inside the reformer 3, a catalyst is loaded, and in the presence of this catalyst, hydrogen is generated by the action of fuel gas, water and oxygen in the air by catalytic combustion reaction, partial oxidation reaction, etc. It is possible.
On the other hand, on the downstream side of the reformer 3, a pipe 3e that guides the generated hydrogen to the FC stack 4 and reformer exhaust gas (exhaust fluid) such as carbon dioxide generated by the reforming reaction is discharged to the outside. The pipe 3f is connected.

  Further, the lower chamber 12B is filled with a heat insulating material (not shown) so that the water is not excessively heated by the heat of the reformer 3 operating at a high temperature. That is, it is preferable not to completely block the heat generated in the reformer 3 and prevent the water from being heated, but to adjust the filling amount of the heat insulating material so that the water is heated to a predetermined level. . In some cases, the wall of the inner casing 12 may be thinned so that the heat of the reformer 3 is easily transferred to water.

<FC stack>
The FC stack 4 according to this embodiment is formed by stacking a plurality of polymer electrolyte fuel cells (PEFC).
On the upstream side of the FC stack 4, a pipe 3 e that leads hydrogen generated in the reformer 3 to the anode side (fuel electrode side) of the FC stack 4 and a midway position of the pipe 3 c are connected to the cathode side of the FC stack 4. A pipe 4a for guiding air to the (air electrode side) is connected. The FC stack 4 generates electric power by generating an electrochemical reaction with hydrogen and oxygen in the air, and can generate heat. A wiring through an inverter (not shown) is connected to an output terminal (not shown) of the FC stack 4 so that a current can be taken out. On the downstream side of the FC stack 4, a pipe 4 e for supplying an anode off gas containing unreacted hydrogen discharged from the anode side to the reformer 3 and a cathode off gas (exhaust fluid) discharged from the cathode side to the outside. A pipe 4f for guiding is connected.
Further, in order to cool (adjust) the FC stack 4 that generates heat to a predetermined temperature during operation, a cooling medium circulates inside and a pipe 5b having a circulation pump 5a is provided in the FC stack 4 in the middle position. Then, the FC stack 4 can be cooled (adjusted) to a predetermined level by operating the circulation pump 5a during the operation of the FC stack 4.
Furthermore, a humidifier may be provided in the middle of the pipe 4a, and the humidified air may be supplied to the cathode side of the FC stack 4 to operate the FC stack 4 stably.

The FC stack 4 is disposed in the upper chamber 12A of the inner casing 12. Thus, conventionally, in order to keep the operating temperature of the FC stack 4 at a predetermined value, it has been necessary to provide a heat insulating material so as to cover the outer peripheral surface of the FC stack 4. Since water is distributed and stored, and this water functions as a heat insulating layer of the FC stack 4, the heat insulating material is not required, and the hot water supply system 1 can be constructed at low cost.
Further, by not providing the heat insulating material, the radiant heat from the FC stack 4 itself is easily transmitted to the water. Further, even when the hot water supply system 1 is installed in a cold region, the FC stack 4 is prevented from freezing by the water flowing and stored in the outer space 11A surrounding the FC stack 4. Furthermore, even if the outside air temperature of the hot water supply system 1 decreases, the FC stack 4 can be easily started. In addition, since the specific heat of water is high and the temperature of water that has once reached a predetermined temperature is unlikely to decrease, it is possible to prevent a significant reduction in the temperature drop rate of the FC stack 4 when the operation is stopped. It is also possible to reduce the descent and shorten the startup time at the start of operation the next day.

<Heat exchanger>
The heat exchanger 7 is connected to the downstream side of the reformer 3 and the FC stack 4, and is a device that transfers heat generated in the reformer 3 and the FC stack 4 to water flowing through the outer space 11A. The heat exchanger 7 is disposed in the housing 10, and mainly a part of the pipe 3f through which the reformer exhaust gas discharged from the reformer 3 flows and the cathode off-gas discharged from the FC stack 4 flow. And a part of the pipe 5b through which a cooling medium for cooling the FC stack 4 to a predetermined temperature flows. More specifically, the heat exchanger 7 is configured by being spirally arranged in a zigzag so that a part of the heat exchanger 7 covers the outer peripheral surface of the inner casing 12, and covers the outer peripheral surface of the inner casing 12. It has such a cylindrical shape.
Therefore, the reformer exhaust gas, the cathode off gas, and the cooling medium circulate along the outer peripheral surface of the inner casing 12 in a portion that passes through the heat exchanger 7. As a result, the heat of the reformer exhaust gas, the cathode off gas, and the cooling medium is suitably transmitted to the water flowing and stored in the outer space 11A, and as a result, the water can be heated to be hot water. ing.
Thus, in this embodiment, since the power sources, such as the conventional circulation pump 121a (refer FIG. 3), are not required, the operating cost of the hot water supply system 1 can be suppressed.

≪Operation of hot water supply system 1≫
Subsequently, the operation of the hot water supply system 1 will be described.

  When fuel gas, water, or air is introduced into the reformer 3, hydrogen is generated by a catalytic combustion reaction or the like. This hydrogen is supplied to the anode side of the FC stack 4 via the pipe 3e. On the other hand, the reformer exhaust gas generated in the reformer 3 by the catalytic reaction is discharged to the outside of the hot water supply system 1 through the pipe 3f.

  In the FC stack 4, hydrogen supplied from the reformer 3 to the anode side and oxygen in the air supplied to the cathode side via the pipe 4 a cause an electrochemical reaction, and the FC stack 4 generates power. It becomes possible. And if an electric current is taken out via the inverter etc. which are connected to the output terminal of FC stack 4, the said electrochemical reaction will advance and FC stack 4 will generate electric power.

As described above, with the generation of electric power by the power generation of the FC stack 4, the electrochemical reaction is an exothermic reaction, so that the FC stack 4 generates heat. Part of the heat generated in the FC stack 4 is transmitted as radiant heat to the water in the outer space 11A via the inner casing 12, and heats this water. A part of the heat is discharged together with the cathode off gas, and is led to the outside of the hot water supply system 1 through the pipe 4f. Furthermore, a part of the heat is absorbed and circulated by the cooling medium circulating in the pipe 5b.
The anode off-gas containing unreacted hydrogen discharged from the anode side of the FC stack 4 is introduced into the reformer 3 via the pipe 4e and used as fuel in the reformer 3.

  In parallel with such power generation of the FC stack 4, water is introduced from the pipe 11a into the outer space 11A.

  Then, in the heat exchanger 7, heat is exchanged between the reformer exhaust gas, the cathode off gas, and the cooling medium circulating in the pipe 5b and water. That is, the heat of the reformer exhaust gas, the cathode off gas, and the cooling medium moves to water, and the water is heated to become hot water.

  More specifically, since the operating temperature of the polymer electrolyte fuel cell (PEFC) constituting the FC stack 4 is generally 70 to 80 ° C., a cathode off gas of 70 to 80 ° C. circulates in the pipe 4f. The cooling medium having the same temperature flows through the pipe 5b. Water is heated by these and the reformer exhaust gas flowing through the pipe 3f to be hot water of 60 to 70 ° C.

  And hot water is discharged | emitted outside from the piping 11b, for example, is used as hot water for bathrooms, or hot water for floor heating.

  As described above, according to the hot water supply system 1, since the conventional circulation pump 121a (see FIG. 3) is not required, not only can it be operated at a low cost, but also the radiant heat from the reformer 3 and the FC stack 4 can be reduced. Can be used. Further, since the heat exchanger 7 is provided in the casing 10 and on the outer peripheral surface of the inner casing 12, the heat of the reformer exhaust gas, the cathode off gas, and the cooling medium can be suitably used to heat water. That is, since heat generated in the reformer 3 and the FC stack 4 can be used without waste, almost no heat loss occurs.

  As mentioned above, although an example was described about suitable embodiment of this invention, this invention is not limited to the said embodiment, In the range which does not deviate from the meaning of this invention, it can change suitably.

  In the above-described embodiment, the fuel cell is a polymer electrolyte fuel cell (PEFC). However, the type of the fuel cell is not limited to this, and for example, a solid oxide fuel cell (SOFC), a molten carbonate, etc. A fuel cell (MCFC), a phosphoric acid fuel cell (PAFC), etc. may be used.

  In the above-described embodiment, the heating target is water, but the heating target is not limited to this, and for example, air, oil, or the like may be used.

  In the above-described embodiment, the vertical (tower-type) hot water supply system 1 in which the FC stack 4 is disposed in the upper chamber 12A and the reformer 3 is disposed in the lower chamber 12B is described, but the FC stack 4, the reformer 3, However, the horizontal hot water supply system 1 in which the FC stack 4 and the reformer 3 are horizontally disposed in the inner casing 12 may be used.

  In the above-described embodiment, as shown in FIG. 1, water is heated to a predetermined temperature by the heat exchanger 7 after being discharged from the pipe 11 a to the outer space 11 </ b> A. As described above, the pipe P may be connected to the downstream side of the pipe 11a, and the pipe P may be disposed so as to discharge water to the outer space 11A after passing through the heat exchanger 7. When the pipe P is provided in this way, the heat exchange rate is further increased. In addition, the water discharged from the downstream end of the pipe P is likely to stir the water stored in the outer space 11 </ b> A, and the temperature difference of the hot water is less likely to occur in the housing 10.

  In the above-described embodiment, both the FC stack 4 and the reformer 3 that are heating elements are arranged in the inner casing 12, but at least one of the FC stack 4 and the reformer 3 is in the casing 10. Should just be arranged.

  In the above-described embodiment, the hot water supply system 1 is configured by arranging the reformer 3 and the FC stack 4 inside the inner casing 12 of the casing 10 having a double structure. Alternatively, the reformer 3 and the FC stack 4 may be appropriately sealed to have a waterproof specification, and may be disposed inside the housing 10 as it is.

It is a figure which shows the structure of the hot water supply system which concerns on this embodiment. It is a figure which shows the modification of the hot water supply system which concerns on this embodiment. It is a figure which shows the structure of the conventional hot water supply system.

Explanation of symbols

1 Hot water supply system 3 Reformer (heating element)
4 FC stack (heating element)
7 Heat exchanger 10 Housing

Claims (4)

A housing having a space through which fluid flows;
A fluid heating system comprising a fuel cell and a heating element comprising at least one of a reformer for supplying hydrogen to the fuel cell,
The fluid heating system, wherein the heating element is disposed in the housing.   A heat exchanger connected to the downstream side of the heating element and disposed in the housing and exchanging heat between a fluid discharged from the heating element and a fluid flowing through the housing; The fluid heating system according to claim 1.   3. The pipe according to claim 2, further comprising a pipe that circulates the fluid in the heat exchanger and exchanges heat between the fluid and the exhausted fluid, and then supplies the fluid into the housing. Fluid heating system.   The fluid heating system according to any one of claims 1 to 3, wherein the fluid is water.

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