JP5228575B2 - Fuel cell power generator - Google Patents

Description

  The present invention relates to a fuel cell power generation apparatus that circulates and uses water generated therein by deionizing with an electric deionization apparatus.

Fuel cell exhaust gas discharged from the fuel cell main body and combustion exhaust gas discharged from the combustion section of the reformer contain moisture, and water self-sustained within the system of the fuel cell power generation device (accepts supplementary water from outside) In order to maintain a state in which the operation is continued without any trouble, it is a common practice to collect condensed water from fuel cell exhaust gas or combustion exhaust gas and reuse it. The condensed water contains carbonate ions, metal ions eluted from the piping, etc., and these ions may adversely affect the electrode catalyst and reforming catalyst. After processing, it is reused.
As a method for deionizing condensed water, attempts have been made in recent years to deionize condensed water using an electric deionization device, for example, as disclosed in Patent Documents 1 to 3 below.
JP 2001-232394 A JP-A-2005-116184 JP 2005-149947 A

The electric deionization apparatus is a water treatment apparatus having a demineralization chamber and a concentration chamber partitioned by an ion exchange membrane between an anode and a cathode, and the demineralization chamber is filled with an ion exchange resin. The ions flowing into the desalting chamber react with the ion exchange resin based on the affinity, concentration and ionic strength, move in the direction of the potential gradient, and reach the ion exchange membrane. The cations permeate the cation exchange membrane and the anions permeate the anion exchange membrane and move to the concentration chamber. Thereby, the condensed water can be separated into deionized water and concentrated water.
By the way, stainless steel pipes are mainly used for piping of fuel cell power generators, but chromium may elute from the stainless steel pipes, and hexavalent chromium may be generated by a combustion process in the combustion section. It was. In particular, the vicinity of the outlet of the anode electrode of the fuel cell body is a hydrogen-rich reducing atmosphere in which an oxide film is difficult to form. In the case of a phosphoric acid fuel cell, phosphoric acid accompanying the off gas of the cell stack is connected to the piping. Since it adheres to the inside, the overall corrosion tends to proceed and chromium tends to be eluted.
In the deionization process using an electric deionizer, ions contained in the condensed water move to the water flowing through the concentrating chamber, so if the condensed water used in the treatment contains hexavalent chromium, it is discharged from the concentrating chamber. Water (concentrated water) contains a high concentration of hexavalent chromium, and the concentrated water may not be discharged out of the system as it is. In order to maintain water independence, it is necessary to reuse the concentrated water, but if the condensed water continues to be reused, hexavalent chromium will concentrate in the system, so the hexavalent chromium concentration will not exceed the wastewater standard value. There was a problem that the wastewater treatment cost was exceeded.

  Accordingly, an object of the present invention is to provide a fuel cell power generator capable of decondensing condensed water using an electric deionizer and preventing concentration of hexavalent chromium in the system. .

In order to achieve the above object, a fuel cell power generator of the present invention has a reforming catalyst layer that steam-reforms hydrocarbons to generate a hydrogen-containing gas, and a combustion section that supplies reaction heat to the reforming catalyst layer. A reformer, a fuel cell main body that generates power by reaction with the hydrogen-containing gas and the oxidant gas, a water tank that collects and stores condensed water from exhaust gas from the combustion section and the fuel cell main body, and the condensation An electric deionization device for deionizing water, wherein a downstream side of a concentrated water drain line extending from a concentrated water drain port side of the electric deionization device is the water tank. Adsorption removal means (excluding activated carbon) that adsorbs hexavalent chromium contained in the condensed water is connected to the upstream side and adsorbs hexavalent chromium contained in the condensed water at one or more locations selected from the condensed water distribution line, the condensed water drainage line, and the water tank. Arranged It is characterized by.
According to the present invention, hexavalent chromium adsorption / removal means for adsorbing hexavalent chromium contained in condensed water is disposed at one or more locations selected from a condensed water distribution line, a condensed water drainage line, and a water tank. Thus, hexavalent chromium can be removed from the condensed water. For this reason, it can prevent that hexavalent chromium concentrates in a system, and can reduce the cost and labor which drainage processing requires.
The water tank of the fuel cell power generator according to the present invention comprises a drain pipe for draining water outside the system when the water level of the water tank exceeds a predetermined height, and the adsorption removing means is disposed in the drain pipe. Preferably it is. According to this aspect, since the hexavalent chromium concentration in the condensed water drained out of the system can be efficiently reduced, labor and cost required for the wastewater treatment can be reduced.

  Furthermore, it is preferable that the said adsorption removal means is arrange | positioned at the concentrated water drainage line. Since the concentrated water discharged from the electric deionizer contains a relatively high concentration of hexavalent chromium, it is possible to efficiently remove hexavalent chromium by placing adsorption removal means on the concentrated water drainage line. It can be reduced by adsorption removal.

  According to the present invention, hexavalent chromium can be prevented from being concentrated in the system, and the cost and labor required for wastewater treatment can be reduced.

Hereinafter, embodiments of a fuel cell power generator according to the present invention will be described based on the drawings. In FIG. 1, the schematic block diagram of embodiment of the fuel cell electric power generating apparatus of 1st embodiment of this invention is shown.
In the figure, reference numeral 1 denotes a fuel cell body, which is a cooling system 1d having an anode electrode 1a and a cathode electrode 1b sandwiching an electrolyte 1c, and a cooling pipe disposed each time a plurality of unit cells made of these are stacked. It consists of and.
A reformed gas supply line L1 extending from the reformer 3 is connected to the reformed gas supply side of the anode electrode 1a. The reformed gas supply line L1 is provided with a reformed gas drain trap Q1, and the reformed gas condensate water supply line L2 extends from the condensate storage part of the reformed gas drain trap Q1 to decarboxylate. It is connected to the device 5.
An anode off-gas discharge line L3 extends from the anode off-gas discharge side of the anode electrode 1a, and the tip side thereof is connected to the combustion fuel supply line L12. In addition, an anode offgas drain trap Q2 is arranged in the middle of the anode offgas discharge line L3, and the anode offgas condensed water supply line L4 extends from the condensed water storage part of the anode offgas drain trap Q2, so that a decarbonation device is provided. 5 is connected.
An air supply line L5 extending from an air supply source is connected to the air supply side of the cathode electrode 1b. The humidifier 2 is disposed in the air supply line L5.

A cathode offgas discharge line L6 extends from the cathode air discharge side of the cathode electrode 1b and is connected to the water tank 4. A cathode offgas heat exchanger Q3 is disposed in the cathode offgas discharge line L6.
A battery coolant supply line L7 extending from the battery coolant tank 12 is connected to the coolant supply side of the cooling system 1d.
A battery cooling water discharge line L8 extends from the cooling water discharge side of the cooling system 1d and is connected to the battery cooling water tank 12.
The reformer 3 includes a reforming catalyst layer 3a filled with a steam reforming catalyst and a combustion section 3b in which a burner is disposed, and combustion heat and combustion exhaust gas generated when combustion fuel is burned by the burner. Thus, the reforming catalyst layer 3a is heated.
A raw material supply line L9 extending from the raw fuel source and a reforming water supply line L10 extending from the battery cooling water tank 12 are connected to the reforming raw material input side of the reforming catalyst layer 3a.
From the reformed gas discharge side of the reformed catalyst layer 3a, the reformed gas supply line L1 extends and is connected to the anode electrode 1a.
A combustion fuel supply line L12 and a combustion air supply line L11 are connected to the combustion fuel inlet side of the combustion section 3b, and fuel fuel and combustion air are supplied to a burner disposed in the combustion section 3b. It is configured to be able to. The anode offgas discharge line L3 and the raw fuel supply line L9 are connected to the upstream side of the combustion fuel supply line L12.

A combustion exhaust gas line L13 extends from the combustion exhaust gas exhaust side of the combustion section 3b and is connected to the decarbonation device 5. A combustion exhaust gas heat exchanger Q4 is disposed in the combustion exhaust gas line L13.
The decarbonation device 5 is disposed adjacent to the upper portion of the water tank 4 and communicates via the drain port 6. In the upper part of the decarboxylation device 5, the concentrated gas discharge extending from the reforming gas condensate supply line L 2, the anode off-gas condensate supply line L 4, the combustion exhaust gas line L 13, and the concentration chamber of the electric deionization device 10 described later. Line L21 is connected. Further, an exhaust line L17 extends from the decarboxylation device 5.
The decarbonation device 5 is not particularly limited, and a device that can degas by condensing condensed water and decarbonation air to diffuse carbon dioxide in the condensed water in the air can be preferably used. The deaeration device having such a configuration includes a deaeration part filled with a SUSCH ring or the like, supplies condensed water to the upper part of the deaeration part, and supplies decarbonation air from the lower part of the deaeration part. Supplying and condensing water by gravity falling, contacting with decarbonation air and decarboxylation treatment, for example, a porous material as disclosed in JP-A-2007-323969 The degassing part in which the inclined plate is arranged is provided, decarbonation air is circulated from the lower side of the inclined plate to the upper side, and condensed water is allowed to flow downward from the upper side of the inclined plate, An example of such a structure that decarboxylates the condensed water is given as an example.

In this embodiment, the adsorption removing means 20 is disposed inside the water tank 4. The adsorption removing means 20 is not particularly limited as long as hexavalent chromium can be adsorbed and removed, and activated carbon can be preferably used. Moreover, it is not restricted to activated carbon, The heavy metal adsorption agent which consists of an inorganic material which has adsorption | suction performance with respect to hexavalent chromium etc. may be sufficient.
Activated carbon has a hydroxyl group on the surface of the activated carbon, and hexavalent chromium reacts with this hydroxyl group, and in addition to being chemically adsorbed, a reducing action is also obtained, so hexavalent chromium can be reduced efficiently. . Moreover, since activated carbon can also adsorb metal ions other than hexavalent chromium, the concentration of metal ions contained in the condensed water can be reduced, and the metal ion removal device 9 and the electric deionization device 10 arranged in the subsequent stage can be used. The load applied to the can be further reduced.
The raw material for the activated carbon is not particularly limited, and examples include charcoal, bamboo charcoal, coconut shell charcoal, and bark. Moreover, there is no limitation in particular as a shape of activated carbon, Shapes, such as a granular form, fine powder form, flake form, porous form, and filter form, are mentioned. The specific surface area of the activated carbon is preferably 100 to 1000 m ² / g.
In order to install the activated carbon inside the water tank 4, for example, a method of filling the activated carbon in a net having an opening smaller than the particle size of the activated carbon and placing the activated carbon at the bottom can be used. Alternatively, an adsorbent made of granular porous ceramics may be filled in a net having an opening smaller than the particle size and disposed at the bottom of the water tank 4.

The water tank 4 is connected to a cathode offgas discharge line L6 and a battery cooling water overflow line L18 extending from the battery cooling water tank 12. A tank water overflow line L19 extends on the side wall of the water tank 4 so that the water level in the tank does not exceed a certain level. A recovered water supply line L <b> 20 extends from the lower part of the water tank 4 and is connected to the battery cooling water tank 12. In the recovered water supply line L20, an inlet filter 8, a recovered water pump P1, a metal ion removing device 9, an electric deionizing device 10, and a water treatment resin 11 are arranged from the upstream side.
The recovered water supply line L20 and a concentrated water discharge line L21, which will be described later, constitute the “condensate water distribution line” of the present invention. The tank water overflow line L19 forms the “condensate drainage line” of the present invention.
The inlet filter 8 is not particularly limited as long as it removes impurities such as soot and dust contained in the recovered water collected in the water tank 4, and a metal removal filter, a particulate removal filter, and the like are preferable.
Preferred examples of the metal ion removing device 9 include metal ion adsorption resins and chelate resins contained in condensed water.

The electric deionization apparatus 10 is a water treatment apparatus having a demineralization chamber and a concentration chamber partitioned by an ion exchange membrane between an anode and a cathode, and the demineralization chamber is filled with an ion exchange resin. is there. The ions flowing into the desalting chamber react with the ion exchange resin based on their affinity, concentration and ionic strength, move in the direction of the potential gradient, and reach the ion exchange membrane. The cations permeate the cation exchange membrane and the anions permeate the anion exchange membrane and move to the concentration chamber. As a result, the recovered water can be separated into deionized water and concentrated water, and deionized water with a reduced ion concentration can be recovered from the demineralization chamber of the electric deionization device. Can supply. Further, a concentrated water discharge line L21 extends from the concentration chamber of the electric deionizer 10 and is connected to the decarboxylation device 5 so that the concentrated water is returned to the upstream side of the water tank 4. .
The water treatment resin 11 removes ions that could not be removed by the electric deionization apparatus 10, and an ion exchange resin or the like is preferable.
Next, the operation of the fuel cell power generator of the present invention will be described.
First, in the reformer 3, the raw fuel supplied from the raw fuel supply line L9 is mixed with the reformed water supplied from the reformed water supply line L10 and supplied to the reforming catalyst layer 3a. A reforming gas rich in hydrogen is generated by the reforming reaction. Since the steam reforming reaction is an endothermic reaction, combustion fuel is supplied from the combustion fuel supply line L12 and combustion air from the combustion air supply line L11 to the combustion unit 3b of the reformer 3, and these are combusted. Then, the reforming catalyst layer 3a is heated. At the time of starting the fuel cell power generator, the raw fuel supplied from the raw fuel supply line L9 is mainly used as the combustion fuel, the combustion state in the combustion section 3b is stabilized, and the reforming catalyst layer When 3a is sufficiently heated, anode off-gas is mainly used.

The reformed gas generated by the reformer 3 is supplied to the anode electrode 1a through the reformed gas supply line L1. Condensed water contained in the reformed gas is recovered by the reformed gas drain trap Q1 disposed in the middle of the reformed gas supply line L1, and supplied to the decarbonation device 5 through the reformed gas condensed water supply line L2. Is done.
In the fuel cell main body 1, the reformed gas supplied to the anode electrode 1a and the air supplied to the cathode electrode 1b are electrochemically reacted at the interface of the electrolyte 1c to generate power, and this generated output is supplied to the power system. .
The cathode offgas discharged from the cathode electrode 1b is cooled by the cathode offgas heat exchanger Q3 and supplied to the water tank 4 through the cathode offgas discharge line L6 together with the cathode offgas condensed water and the cathode gas.
The anode off gas discharged from the anode electrode 1a is supplied to the combustion unit 3b through the anode off gas discharge line L3 and used as a combustion fuel. The condensed water contained in the anode off gas is recovered by an anode off gas drain trap Q2 disposed in the middle of the anode off gas discharge line L3, and is supplied to the decarbonation device 5 through the anode off gas condensed water supply line L4.

The combustion exhaust gas discharged from the combustion unit 3b of the reformer 3 is cooled by the combustion exhaust gas heat exchanger Q4 and supplied to the decarbonation device 5 together with the combustion exhaust gas.
The condensed water collected in the water tank 4 is subjected to removal of impurities such as soot and dust by the inlet filter 8, and is then subjected to metal ion removal processing by the metal ion removal device 9. The treated water that is sent to the deionization apparatus 10 and subjected to deionization treatment and discharged from the demineralization chamber of the electric deionization apparatus 10 is further deionized with the water treatment resin 11, and then the battery cooling water tank 12. And used for battery cooling water, humidified water, reformed water and the like. On the other hand, the concentrated water discharged from the concentration chamber of the electric deionizer 10 is returned to the decarbonator 5 through the concentrated water discharge line L21.
By the way, as described above, the stainless steel member is mainly used for the piping of the fuel cell power generation device. However, chromium is eluted from the stainless steel member, and hexavalent chromium is produced by the combustion process in the combustion part. It was sometimes generated. In particular, the condensed water recovered from the combustion exhaust gas tended to contain a large amount of hexavalent chromium. Hexavalent chromium can hardly be removed by the metal ion removal device 9, the electric deionization device 10, the water treatment resin 11, and the like, and if the condensed water is continuously reused, the hexavalent chromium may be concentrated. It was.

However, in the present invention, the hexavalent chromium contained in the condensed water can be reduced by arranging the adsorption removing means 20.
Moreover, in this embodiment, since the adsorption removal means 20 is disposed in the water tank 4, the contact time between the adsorption removal means 20 and the condensed water can be ensured for a relatively long time, so hexavalent chromium can be efficiently removed. Can be reduced.
A second embodiment of the fuel cell power generator of the present invention will be described with reference to FIG. Hereinafter, the same portions as those in the first embodiment are denoted by the same reference numerals, and the description thereof is omitted.
This embodiment is different from the first embodiment in that the adsorption removing means 20 is arranged on the recovered water supply line L20 on the upstream side of the electric deionization apparatus 10. In this embodiment, filter-like activated carbon is used as the adsorption removal means 20.
A third embodiment of the fuel cell power generator of the present invention will be described with reference to FIG.
This embodiment is different from the first embodiment in that the adsorption removing unit 20 is disposed in the concentrated water discharge line L21.
In this embodiment, as in the second embodiment, when activated carbon is used as the adsorption removing means 20, it is preferably used in the form of a filter.

Since the concentrated water discharged from the concentration chamber of the electric deionizer 10 contains a relatively high concentration of hexavalent chromium, the adsorption / removal means 20 is disposed in the concentrated water discharge line L21, so that Valent chromium can be reduced efficiently.
And in this embodiment, since the adsorption removal means 20 is not arrange | positioned on the liquid feed line of condensed water, a pressure loss arises and it is hard to reduce the distribution | circulation of condensed water. For this reason, the amount of water supplied to each chamber of the electric deionizer 10 is less likely to fluctuate, and the condensed water can be efficiently deionized.
A fourth embodiment of the fuel cell power generator of the present invention will be described with reference to FIG.
This embodiment is different from the first embodiment in that the adsorption removing means 20 is disposed in the tank water overflow line L19.
In this embodiment, it is preferable to use activated carbon on a filter as the adsorption removal means 20 as in the second and third embodiments.
When hexavalent chromium is concentrated in the system, the condensed water drained by overflowing from the water tank 4 may contain a relatively high concentration of hexavalent chromium, so the tank water overflow line L19. By disposing the adsorption removing means 20 on the top, it is possible to prevent hexavalent chromium exceeding the drainage standard value from flowing out of the system.

  And like this said 3rd embodiment, since the adsorption | suction removal means 20 is not arrange | positioned on the liquid feed line of condensed water, a pressure loss cannot raise easily and there is little possibility that the distribution | circulation of condensed water deteriorates.

1 is a schematic configuration diagram of a first embodiment of a fuel cell power generator of the present invention. It is a schematic block diagram of 2nd embodiment of the fuel cell electric power generating apparatus of this invention. It is a schematic block diagram of 3rd embodiment of the fuel cell electric power generating apparatus of this invention. It is a schematic block diagram of 4th embodiment of the fuel cell power generator of this invention.

Explanation of symbols

1: Fuel cell body 1a: Anode electrode 1b: Cathode electrode 1c: Electrolyte 1d: Cooling system 2: Humidifier 3: Reforming device 3a: Reforming catalyst layer 3b: Combustion unit 4: Water tank 5: Decarbonation device 6: Drain port 8: Inlet filter 9: Metal ion removal device 10: Electric deionization device 11: Water treatment resin 12: Battery cooling water tank 20: Adsorption removal means L1: Reformed gas supply line L2: Reformed gas condensed water supply Line L3: Anode off gas discharge line L4: Anode off gas condensate supply line L5: Air supply line L6: Cathode off gas discharge line L7: Battery cooling water supply line L8: Battery cooling water discharge line L9: Raw fuel supply line L10: Reforming Water supply line L11: Combustion air supply line L12: Fuel supply line for combustion L13: Combustion exhaust gas line L17: Exhaust line L18: Battery cooling Water overflow line L19: Tank water overflow line L20: Recovered water supply line L21: Concentrated water discharge line P1: Recovered water pump Q1: Reformed water drain trap Q2: Anode offgas drain trap Q3: Cathode offgas heat exchanger Q4: Combustion exhaust gas Heat exchanger

Claims (3)

Reaction of a reforming catalyst layer for steam reforming hydrocarbons to produce a hydrogen-containing gas, a reformer having a combustion section for supplying reaction heat to the reforming catalyst layer, and the hydrogen-containing gas and oxidant gas A fuel cell main body that generates electric power, a water tank that collects and stores condensed water from exhaust gas of the combustion section and the fuel cell main body, and an electric deionization device that deionizes the condensed water. A fuel cell power generator,
The downstream side of the concentrated water drainage line extending from the concentrated water drainage side of the electric deionizer is connected to the upstream side of the water tank,
Fuel characterized in that adsorption removal means (excluding activated carbon) that adsorbs hexavalent chromium contained in condensed water is arranged at one or more locations selected from a condensed water distribution line, a condensed water drainage line, and a water tank. Battery power generator.   The said water tank is equipped with the drain pipe which drains water outside a system when the water level of this water tank exceeds predetermined height, The said adsorption removal means is arrange | positioned at this drain pipe. Fuel cell power generator. Wherein the suction removal means to the concentrated water discharge line is disposed, the fuel cell power generator according to claim 1.

Images