JP4660888B2 - Fuel cell power generation system and operation method thereof - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention provides a fuel for generating power by steam-reforming a fuel such as natural gas to produce a fuel gas containing hydrogen gas and electrochemically reacting the fuel gas with an oxidizing gas such as oxygen in the air. The present invention relates to a power generation system using a battery and an operation method thereof.
[0002]
[Prior art]
In general, in a fuel cell power generation system, cooling water that adjusts the temperature in the fuel cell is used to maintain high power generation efficiency in the fuel cell. The cooling water is usually used after being subjected to a treatment such as desalting.
FIG. 5 shows a conventional fuel cell power generation system. This fuel cell power generation system includes a fuel cell 1, a feed water storage tank 2 for storing feed water as cooling water for the fuel cell 1, and a feed water storage tank 2. A water treatment system 3 that purifies the feed water and supplies it to the fuel cell 1 as cooling water, an exhaust heat recovery heat exchanger 4 that heats the water using the exhaust heat of the fuel cell 1, and a heat exchanger 4 The hot water storage tank 5 which stores the hot water obtained by using and the supplementary water supply path 41 which supplies supplementary water to the feed water storage tank 2 are provided.
[0003]
The fuel cell 1 includes an exhaust gas condensed water recovery heat exchanger 17 that recovers water vapor in the exhaust gas discharged from the fuel cell 1 as condensed water.
The water treatment system 3 includes a water treatment device 19 such as an ion exchange desalination treatment device and a liquid feed pump P1.
The hot water storage tank 5 is configured to supply hot water in the tank to heat utilization equipment (not shown).
[0004]
In the fuel cell power generation system, in the fuel cell 1, fuel such as natural gas is steam reformed to generate a fuel gas containing hydrogen gas, and this fuel gas is combined with an oxidizing gas such as oxygen in the air and electrochemically. The exhaust gas condensed water recovery heat exchanger 17 cools and condenses the water vapor in the exhaust gas, collects it, collects it, and stores it in the feed water storage tank 2. In addition, supply water such as city water is supplied into the supply water storage tank 2 through the supply water supply path 41 as necessary.
In the feed water storage tank 2, ions (carbonate ions, metal ions, etc.) derived from make-up water such as city water and impurities such as solids are mixed, so the feed water in the feed water storage tank 2 is a water treatment system. After the impurities are removed by the water treatment apparatus 19 of No. 3, the fuel cell 1 is supplied as cooling water. As a result, scale generation and the like in the cooling water circulation path can be prevented.
[0005]
[Problems to be solved by the invention]
However, in the fuel cell power generation system, since the load applied to the water treatment device 19 is large, it is necessary to use a complicated and large-sized water treatment device 19 and there is a problem that the equipment cost increases. Moreover, when using an ion exchange type desalting apparatus, there existed a problem that operation costs, such as a regeneration processing cost, increased.
The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a fuel cell power generation system and an operation method thereof capable of reducing facility costs and operation costs.
[0006]
[Means for Solving the Problems]
The fuel cell power generation system of the present invention includes a fuel cell having a cooling water circulation system, a feed water storage tank that stores feed water that serves as cooling water for the fuel cell, and a fuel cell that serves as cooling water by processing the feed water in the feed water storage tank A water treatment system for supplying water, a heating means for heating water, a hot water storage tank for storing hot water obtained by the heating means, and condensed water obtained by condensing water vapor from the hot water in the hot water storage tank Is provided with a condensed water supply system for supplying water to the feed water storage tank.
The heating means can be configured to heat water using heat generated during power generation in the fuel cell.
The condensed water supply system includes a condensed water recovery heat exchanger that condenses and recovers water vapor from the hot water in the hot water storage tank, and a condensed water supply path that supplies the condensed water recovered in the heat exchanger to the feed water storage tank. The condensate water recovery heat exchanger can be configured to be able to cool and condense the water vapor from the hot water in the hot water storage tank with the makeup water to the hot water storage tank.
In addition, a partition wall is provided in the hot water storage tank to partition the tank into a plurality of tank spaces, and the partition wall is introduced into one of the tank spaces by the warm water heated by the heating means, and It is possible to adopt a configuration in which water vapor from the hot water in the tank space is supplied to the condensed water supply system.
Moreover, in this invention, when driving | operating the said fuel cell power generation system, the driving | running method which supplies the condensed water which condensed the water vapor | steam from the warm water in a warm water storage tank to a feed water storage tank can be taken.
[0007]
DETAILED DESCRIPTION OF THE INVENTION
1 and 2 show a first embodiment of a fuel cell power generation system of the present invention. The fuel cell power generation system shown here stores a fuel cell 1 and water supply serving as cooling water for the fuel cell 1. A water supply storage tank 2 to be purified, a water treatment system 3 to purify the water supplied to the water supply storage tank 2 and supply it to the fuel cell 1 as cooling water, and heating to heat the water using the exhaust heat of the fuel cell 1 Waste heat recovery heat exchanger 4 that is means, hot water storage tank 5 that stores hot water obtained using the heat exchanger 4, and condensed water obtained by condensing water vapor from the hot water in the hot water storage tank 5 A condensed water supply system 6 for supplying the storage tank 2 is provided.
[0008]
As shown in FIG. 2, the fuel cell 1 includes a fuel cell main body 11, a reformer 12 for steam reforming the fuel, a cooling water circulation path 13 for circulating cooling water for cooling the fuel cell main body 11, and reforming. A steam separator 14 serving as a supply source of steam used in the vessel 12, a heat exchanger 15 that cools the cooling water, a circulation path 16 of the internal water that exchanges heat with the cooling water in the heat exchanger 15, An exhaust gas condensed water recovery heat exchanger 17 that condenses and recovers water vapor in the exhaust gas discharged from the fuel cell 1 is a main component.
[0009]
The fuel cell main body 11 is configured such that a fuel electrode 21 and an air electrode 22 are arranged via electrode plates 24 and 25 so as to sandwich an electrolyte 23.
The water vapor separator 14 is provided in the cooling water circulation path 13 and can separate water vapor from the cooling water.
The reformer 12 can reform the fuel supplied from the fuel supply path 26 with the steam supplied from the steam separator 14 through the steam supply path 27 to generate a fuel gas containing hydrogen. ing.
[0010]
The exhaust gas condensed water recovery heat exchanger 17 is provided in the in-system water circulation path 16 and cools the water vapor in the exhaust gas discharged from the reformer 12 and the air electrode 22 through the discharge paths 28 and 29 by the in-system water. It can be condensed and recovered.
[0011]
As shown in FIG. 1, the water treatment system 3 includes a water treatment device 19 and a liquid feed pump P1.
As the water treatment device 19, a treatment device that removes impurities such as ions and solids can be used. An ion exchange type desalination treatment device using an ion exchange resin and a membrane separation type desalination method using a reverse osmosis membrane. A device, a membrane separation device using an ultrafiltration membrane, or the like can be used.
[0012]
As shown in FIGS. 1 and 2, the exhaust heat recovery heat exchanger 4 is provided in the in-system water circulation path 16, and the water supplied from the hot water storage tank 5 through the supply path 30 a of the hot water circulation path 30 is It can be heated with water in the system.
[0013]
The hot water storage tank 5 can supply hot water in the tank to heat utilization equipment (not shown).
As shown in FIG. 1, the hot water storage tank 5 is connected to a supplementary water supply path 36 for supplying makeup water into the hot water storage tank 5, and the hot water is stored by supplying hot water to a heat utilization facility (not shown). When the amount of water in the tank 5 is insufficient, makeup water can be supplied into the hot water storage tank 5.
[0014]
In the fuel cell power generation system of the present embodiment, the condensate supply system 6 is recovered by the hot water condensate recovery heat exchanger 7 that condenses and recovers steam from the hot water in the hot water storage tank 5 and the heat exchanger 7. And a condensed water supply path 8 for supplying the condensed water to the feed water storage tank 2.
The hot water condensate recovery heat exchanger 7 is provided in a makeup water supply path 36 that supplies makeup water to the warm water storage tank 5, and is in the gas in the warm water storage tank 5 that is led out through a lead-out path 37 in the upper part of the storage tank 5. The water vapor is cooled and condensed by the make-up water flowing through the make-up water supply path 36, and can be recovered as condensed water.
[0015]
Hereinafter, a method of using the fuel cell power generation system will be described.
As shown in FIG. 2, in this fuel cell power generation system, fuel such as desulfurized natural gas and naphtha is supplied to the reformer 12 through the fuel supply path 26, and this fuel is supplied from the steam separator 14 to the steam. The fuel gas is reformed by the steam supplied through the supply path 27 to generate a fuel gas containing hydrogen.
This fuel gas is supplied to the fuel electrode 21 of the fuel cell main body 11 through a fuel gas supply path 31 via a carbon monoxide transformer or the like (not shown), and an oxidizing gas such as air is supplied to the oxidizing gas supply path 32. The fuel gas and the oxidizing gas are electrochemically reacted to generate electricity.
[0016]
The fuel system exhaust gas from the reformer 12 is discharged out of the system through the exhaust path 28 through the exhaust gas condensed water recovery heat exchanger 17. Further, the oxidizing exhaust gas from the air electrode 22 merges with the fuel exhaust gas in the discharge path 28 through the discharge path 29, and is discharged outside the system through the condensed water recovery heat exchanger 17.
[0017]
In the cooling water circulation path 13, the cooling water is circulated to cool the fuel cell main body 11 so as to maintain a preset temperature. At this time, the cooling water is heated to a high temperature and introduced into the water vapor separator 14. Is done.
In the steam separator 14, the steam is separated from the cooling water, and a part thereof is supplied to the reformer 12 through the steam supply path 27.
The cooling water having passed through the water vapor separator 14 is cooled by exchanging heat with the system water flowing through the system water circulation path 16 in the heat exchanger 15 and then introduced into the fuel cell main body 11 again. Is repeated.
[0018]
The in-system water flowing through the in-system water circulation path 16 cools the cooling water in the heat exchanger 15 and cools the fuel system and the oxidation system exhaust gas in the discharge path 28 in the exhaust gas condensed water recovery heat exchanger 17. Water vapor in the exhaust gas is condensed.
The condensed water recovered in the exhaust gas condensed water recovery heat exchanger 17 is sent to the feed water storage tank 2 through the condensed water recovery path 33.
[0019]
The in-system water heated in the heat exchangers 15 and 17 heats the water supplied from the supply path 30a by the liquid feed pump P2 in the exhaust heat recovery heat exchanger 4. The heated warm water is sent to the warm water storage tank 5 through the return path 30b.
As described above, in the exhaust heat recovery heat exchanger 4, water is exchanged by heat exchange with the system water heated by the cooling water heated to high temperature by heat (exhaust heat) generated during power generation in the fuel cell body 11. Heating is performed.
[0020]
Further, when the amount of water in the hot water storage tank 5 is insufficient due to the supply of hot water to a heat utilization facility (not shown), supply water such as city water is supplied into the hot water storage tank 5 through the supply water supply path 36.
[0021]
A part of the cooling water flowing through the cooling water circulation path 13 is separated as water vapor in the water vapor separator 14 and is led out from the cooling water circulation path 13 through the path 27, so that it is necessary to replenish the insufficient cooling water.
For this reason, the feed water in the feed water storage tank 2 is introduced into the water treatment device 19 by the liquid feed pump P1 to remove impurities, and the obtained treated water is supplied as cooling water to the cooling water circulation path 13 through the cooling water supply path 35. Supply.
[0022]
In the fuel cell power generation system of this embodiment, when the amount of water in the feed water storage tank 2 is reduced by replenishing cooling water, the condensed water supply system 6 is used to enter the feed water storage tank 2 as follows. Replenish water.
Since the water in the warm water storage tank 5 is warm water, the water vapor pressure in the gas phase in the warm water storage tank 5 is high, and the gas in the warm water storage tank 5 led out through the lead-out path 37 contains a large amount of steam. .
When the steam-containing gas is introduced into the hot water condensed water recovery heat exchanger 7 through the outlet path 37, the steam in the gas is cooled and condensed into makeup water (city water or the like) flowing through the makeup water supply path 36.
[0023]
This condensed water is supplied to the feed water storage tank 2 as makeup water through the condensed water supply path 8. Since this condensed water is distilled water having a low concentration of impurities such as ions, the amount of impurities mixed into the feed water storage tank 2 is minimized, the impurity concentration in the feed water storage tank 2 is reduced, and the water treatment device A load such as a desalting treatment given to 19 is reduced.
Therefore, the treatment capacity of the water treatment device 19 can be set low, the equipment cost required for the water treatment system 3 can be reduced, and the operation cost such as the regeneration treatment cost of the ion exchange resin can be kept low.
Further, since the treatment capacity of the water treatment device 19 can be set low, the device can be miniaturized and its installation space can be reduced.
[0024]
In addition, the exhaust heat recovery heat exchanger 4 is configured to be able to warm water by using heat generated during power generation in the fuel cell 1 as exhaust heat, so that hot water is obtained by effectively using exhaust heat. Energy efficiency can be improved.
[0025]
Further, the hot water condensed water recovery heat exchanger 7 of the condensed water supply system 6 is configured to be able to cool and condense the water vapor in the gas in the hot water storage tank 5 with the makeup water flowing through the makeup water supply path 36. Therefore, when condensing water vapor in the condensed water supply system 6, it is not necessary to use a separate cooling medium, and the operating cost can be further reduced.
[0026]
FIG. 3 shows a second embodiment of the fuel cell power generation system according to the present invention. In the fuel cell power generation system shown here, the hot water storage tank 5 is divided into two upper spaces, that is, two upper spaces. A partition wall 20 is provided that partitions the spaces 5a and 5b.
[0027]
The partition wall 20 is for maintaining a high temperature of the hot water in the upper space 5a and increasing the amount of water vapor introduced into the hot water condensate recovery heat exchanger 7, and the hot water between the upper space 5a and the lower space 5b. Has a distribution port 20a.
The inner diameter of the circulation port 20a is set so that water in the lower space 5b can be restricted from flowing into the upper space 5a.
The partition wall 20 can be made of a metal such as stainless steel or a synthetic resin such as polyvinyl chloride. In particular, it is preferable to use a synthetic resin having excellent heat insulation performance.
[0028]
The supply path 40a and the return path 40b of the hot water circulation path 40 are respectively connected to the lower part and the upper part of the hot water storage tank 5, and the water heated by the exhaust heat recovery heat exchanger 4 passes through the return path 40b to the upper space 5a. Then, it flows into the lower space 5b through the circulation port 20a and flows from the lower space 5b to the supply path 40a.
A makeup water supply path 38 for supplying makeup water into the lower space 5b is connected to the lower part of the warm water storage tank 5, and the amount of water in the warm water storage tank 5 is reduced by supplying warm water to a heat utilization facility (not shown). In the case of a shortage, makeup water can be supplied into the lower space 5b.
[0029]
In this fuel cell power generation system, hot hot water heated by the exhaust heat recovery heat exchanger 4 and returned to the hot water storage tank 5 through the return path 40 b is introduced into the upper space 5 a above the partition wall 20.
The water vapor obtained by evaporating the high-temperature hot water introduced into the upper space 5a is introduced into the hot water condensed water recovery heat exchanger 7 through the outlet path 37, and is supplied to the feed water storage tank 2 through the condensed water supply pipe 8 as condensed water. The
[0030]
The warm water in the upper space 5a follows the circulation flow in the warm water circulation path 40, passes through the circulation port 20a, and flows into the lower space 5b.
The hot water in the hot water storage tank 5 is cooled by the outside air and its temperature gradually decreases. Therefore, in the lower space 5b corresponding to the downstream side of the hot water circulation flow in the hot water storage tank 5, the upper space 5a corresponding to the upstream side. The temperature of hot water is lower than
The hot water in the lower space 5b that has become relatively low temperature is supplied to the exhaust heat recovery heat exchanger 4 through the supply path 40a.
[0031]
In the fuel cell power generation system of the present embodiment, the load applied to the water treatment system 3 by reducing the concentration of impurities in the feed water supplied to the water treatment system 3 as in the fuel cell power generation system of the first embodiment. Can be reduced, the apparatus can be miniaturized, and the equipment cost and operation cost can be kept low.
Furthermore, in the fuel cell power generation system of the present embodiment, by providing the partition wall 20 that divides the hot water storage tank 5 into upper and lower spaces 5a and 5b, the temperature of the hot water in the upper space 5a is maintained high, and the upper space The water vapor pressure in the gas phase in 5a can be increased, the water vapor content in the gas introduced into the hot water condensate recovery heat exchanger 7 can be increased, and the condensate recovery efficiency in the heat exchanger 7 can be improved.
Therefore, the supply amount of the condensed water, which is distilled water having a low impurity concentration, to the feed water storage tank 2 is increased, the impurity concentration in the feed water storage tank 2 is lowered, and the load such as the desalination treatment given to the water treatment device 19 is reduced. Can be reduced.
Therefore, the treatment capacity of the water treatment device 19 can be set low, and the equipment cost and operation cost can be further reduced.
[0032]
In the fuel cell power generation system of the above embodiment, the exhaust heat recovery heat exchanger 4 that uses the exhaust heat of the fuel cell 1 is provided as the heating means. However, in the fuel cell power generation system of the present invention, the heat utilization facility is provided. The heating means for heating the water to be supplied to the fuel cell is not limited to one that uses the exhaust heat of the fuel cell 1.
For example, as shown in FIG. 4, instead of the exhaust heat recovery heat exchanger 4, a heater 51 for heating the water in the tank can be provided in the hot water storage tank 5.
[0033]
In the fuel cell power generation system of the above embodiment, the configuration in which the feed water recovered by the exhaust gas condensate recovery heat exchanger 17 can be used as cooling water is shown, but the fuel cell power generation system of the present invention is not limited to this, It is also possible to employ a configuration in which makeup water such as city water is exclusively used as water supply without collecting water vapor in the exhaust gas.
Moreover, in the fuel cell power generation system of the present invention, since the impurity concentration in the supply water supplied to the water treatment system can be kept low, the water treatment system can be omitted.
In the present invention, the cooling water circulation path may be configured such that the cooling water is introduced into the feed water storage tank 2 through the fuel cell body 11 and the water vapor separator 14 and through the condensed water recovery path 33.
[0034]
【The invention's effect】
As described above, the fuel cell power generation system of the present invention includes a condensed water supply system that supplies condensed water obtained by condensing water vapor from hot water in the hot water storage tank to the feed water storage tank. Condensed water, which is distilled water having a low concentration of impurities such as substances, can be supplied to the feed water storage tank as make-up water, and the load such as desalting treatment applied to the water treatment system can be reduced.
Accordingly, the treatment capacity of the water treatment system can be set low, and the equipment cost and operation cost can be kept low.
[0035]
Further, by configuring the heating means so that water can be heated using heat generated during power generation in the fuel cell, warm water can be obtained by effectively using the exhaust heat generated in the fuel cell, Energy efficiency can be improved.
[0036]
The condensed water supply system includes a condensed water recovery heat exchanger that condenses and recovers steam from the hot water, and a condensed water supply path that supplies the recovered condensed water to the feed water storage tank. However, it is necessary to use a separate cooling medium when condensing the water vapor in the condensed water supply system by configuring so that the water vapor from the hot water can be cooled and condensed by the makeup water to the hot water storage tank. The operating cost can be further reduced.
[0037]
In addition, a partition wall is provided in the hot water storage tank to partition the tank into a plurality of tank spaces, and the partition wall is introduced into one of the tank spaces by the warm water heated by the heating means, and By adopting a configuration in which steam from the hot water in the tank space is supplied to the condensed water supply system, the temperature of the hot water in the tank space in which the steam is supplied to the condensed water supply system is maintained high. It is possible to increase the water vapor pressure in the gas phase in the tank space, increase the water vapor content in the gas introduced into the condensed water supply system, and improve the recovery efficiency of the condensed water.
Therefore, it is possible to increase the supply amount of the condensed water having a low impurity concentration to the feed water storage tank, reduce the load such as the desalination treatment given to the water treatment system, and further reduce the equipment cost and the operation cost.
[Brief description of the drawings]
FIG. 1 is a configuration diagram showing a first embodiment of a fuel cell power generation system of the present invention.
FIG. 2 is a configuration diagram showing a fuel cell of the fuel cell power generation system shown in FIG. 1;
FIG. 3 is a configuration diagram showing a second embodiment of the fuel cell power generation system of the present invention.
FIG. 4 is a configuration diagram showing a third embodiment of the fuel cell power generation system of the present invention.
FIG. 5 is a configuration diagram showing an example of a conventional fuel cell power generation system.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Fuel cell, 2 ... Water supply storage tank, 3 ... Water treatment system, 4 ... Waste heat recovery heat exchanger (heating means), 5 ... Hot water storage tank, 5a ... -Upper space (space in the tank), 5b ... Lower space (space in the tank), 6 ... Condensate supply system, 7 ... Hot water condensate recovery heat exchanger (Condensate recovery heat exchanger), 8 ... Condensed water supply path, 13 ... Cooling water circulation path, 20 ... Partition, 51 ... Heater (heating means)

Claims (5)

A fuel cell having a coolant circulation system, a feed water storage tank for storing feed water that serves as cooling water for the fuel cell, a water treatment system for processing the feed water in the feed water storage tank and supplying it to the fuel cell as cooling water, In a fuel cell power generation system comprising a heating means for heating the water and a hot water storage tank for storing hot water obtained by the heating means,
A fuel cell power generation system comprising a condensed water supply system that supplies condensed water obtained by condensing water vapor from hot water in a hot water storage tank to a feed water storage tank. The fuel cell power generation system according to claim 1, wherein the heating means is configured to be able to heat water using heat generated during power generation in the fuel cell. The condensed water supply system includes a condensed water recovery heat exchanger that condenses and recovers water vapor from the hot water in the hot water storage tank, and a condensed water supply path that supplies the condensed water recovered in the heat exchanger to the feed water storage tank. With
The condensed water recovery heat exchanger is configured to be able to cool and condense the water vapor from the hot water in the hot water storage tank with the makeup water to the hot water storage tank. 3. The fuel cell power generation system according to 2. In the hot water storage tank, a partition that partitions the tank into a plurality of tank spaces is provided,
The partition wall is configured such that warm water heated by a heating means is introduced into one of the tank spaces, and water vapor from the warm water in the tank space is supplied to a condensed water supply system. The fuel cell power generation system according to any one of claims 1 to 3, wherein: A fuel cell having a cooling water circulation system, a feed water storage tank for storing feed water serving as cooling water for the fuel cell, a water treatment system for processing the feed water in the feed water storage tank and supplying it to the fuel cell as cooling water, A method of operating a fuel cell power generation system comprising a heating means for warming and a warm water storage tank for storing warm water obtained by the warming means,
An operation method of a fuel cell power generation system, characterized in that condensed water obtained by condensing water vapor from hot water in a hot water storage tank is supplied to a water supply storage tank.

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