JPH0824053B2 - Fuel cell water treatment device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application] The present invention can efficiently remove ammonia or methanol contained in condensed fuel reforming water produced in a fuel cell power generation system. The present invention relates to a water treatment device for a fuel cell.

(Prior Art) Generally, hydrogen used as a fuel gas of a fuel cell is obtained as follows. That is, using hydrocarbons such as natural gas or naphtha as a raw material, after adding steam, reforming into hydrogen and carbon dioxide by a catalyst at high temperature, then introducing into a contact cooler, cooling and gas-liquid separation are simultaneously performed, and steam And other impurities are separated and collected as fuel reforming system condensed water. On the other hand, the hydrogen-rich gas discharged from the contact cooler is supplied to the fuel cell main body as fuel gas.

By the way, in the presence of a catalyst under the high temperature as described above,
Methanol is produced as a by-product in the reaction of reforming hydrocarbons and steam into hydrogen, and ammonia is produced as a by-product when the raw material contains nitrogen. Since it is almost impossible to suppress such side reactions, it is inevitable that ammonia or methanol is contained as an impurity in the condensed water of the fuel reforming system.

The property of the condensed water of the fuel reforming system changes depending on the operating conditions of the fuel cell power plant, but the temperature is approximately
At 90 to 130 ℃, the maximum impurity amount is thought to be several hundred ppm of ammonia and one thousand and several hundred ppm of methanol.

In addition, generally, in a fuel cell power generation system, water generated in the system such as cathode condensed water or fuel reforming system condensed water generated in the cell body by power generation is treated as water without being discarded and reused as water. I will use it
There is no need to supply water from the outside, which is a feature and advantage of the fuel cell.

However, the water used for the fuel cell power generation system is
Since high-purity water is required, high-purity treatment of ion exchange resin or the like is performed, but the presence of ammonia, methanol, or the like at this time causes a heavy load.

Conventionally, in systems other than fuel cells, various physical, chemical or biological methods have been studied as methods for removing ammonia or methanol. For example, the ammonia treatment method includes a distillation method, an alkali addition-stripping method, an ion exchange method, a biological denitrification method, and the like, and the methanol treatment method includes a distillation method, an activated sludge biological method, and UV (ultraviolet). There is an oxidative decomposition method using hydrogen peroxide and the like, which is industrially used.

However, in the fuel cell power generation system, it is desired that the water treatment device has the following requirements. That is, 1) unmanned and easy to automate and highly reliable 2) low initial / running cost 3) simple equipment and small installation area 4) little wastewater and water loss associated with water treatment 5) The purity of treated water is high and the load on post-treatment is small. However, when the current method is applied to a fuel cell power generation system, there are advantages and disadvantages in terms of treatment performance, treatment efficiency, cost, etc. I was not satisfied.

(Problems to be Solved by the Invention) As described above, in the conventional fuel cell water treatment device, ammonia or methanol contained in the fuel reforming system condensed water or the like cannot be efficiently removed.

The present invention has been proposed in order to eliminate the above drawbacks, and an object thereof is to efficiently remove ammonia or methanol contained in fuel reforming system condensed water or the like, and to obtain highly pure water. It is to provide a water treatment device for a fuel cell capable of performing.

[Structure of the Invention] (Means for Solving Problems) The present invention relates to a water treatment device intended for water used in a fuel cell power generation system, a normal low-temperature purification device using an ion exchange resin, and a fuel. The wet oxidation device is capable of removing ammonia and methanol contained in the reformed condensed water.

(Operation) According to the water treatment device for a fuel cell of the present invention, before being introduced into a normal low temperature purification device using an ion exchange resin, a wet oxidation device is used so that the water is contained in the fuel reforming system condensed water. Ammonia and methanol can be removed efficiently.

(Embodiment) An embodiment of the present invention will be specifically described below with reference to FIGS. 1 and 2.

* Structure of Embodiment * In this embodiment, as shown in the block diagram of FIG. 1, a wet matter oxidizer 1 is used as a main constituent element of a water treatment device of a fuel cell. This dissolved material wet oxidation apparatus 1 is a fixed bed in which a fuel reforming system condensed water (hereinafter referred to as raw water) 2 is filled with an air injection device 3 for injecting air necessary for oxidative decomposition, a superheater 4, and a catalyst. The wet oxidation decomposition column 5 and the gas-liquid decomposition device 6 are sequentially connected and arranged, and the gas-liquid separation device 6 is connected.
The liquid phase component separated by is sent to a conventionally used low temperature purification device.

Next, FIG. 2 shows a specific example of the dissolved substance wet oxidation apparatus having the above-mentioned configuration. That is, the fuel reforming condensed water 2 which is the water to be treated is introduced into the air injecting device 3 through the raw water pump 10, and this air injecting device 3 is passed through the heating device 4 which uses the excess steam or hot water 11 as a heat source. The treated water discharged from the upper part of the wet oxidative decomposition column 5 is introduced from the lower part of the contact cooler 14 filled with the filling material 13 via the pressure reducing valve 12. A low temperature purifying device (not shown) for reusing the treated water 16 via the treated water pump 15 is provided under the contact cooler 14.
A system for connecting to is provided. On the other hand, a system for discharging the exhaust gas 17 is provided at the upper part.

The following is used as the catalyst 18 packed in the wet oxidative decomposition column 5. That is, granular, block-shaped or fibrous shaped nickel, simple metal such as titanium, stainless steel, alloy steel such as corrosion resistant heat resistant alloy, or alumina, zirconia, titania, to a heat resistant water-based carrier selected from ceramics such as ferrite, It is possible to use a noble metal such as platinum, palladium, rhodium, or ruthenium, which has an oxidation-promoting property, a non-metal simple substance such as nickel, cobalt, iron, manganese, or copper, or a solid catalyst carrying these metal compounds.

* Operation of Embodiment * In the water treatment apparatus for a fuel cell of this embodiment having such a configuration, the fuel reforming system condensed water 2 which is the water to be treated is pressurized by the raw water pump 10 and pressurized air 19 Is introduced into the air injection device 3. Here, the raw water and the oxidizing air are mixed and mixed, and then sent to the heating device 4 that uses excess steam or hot water 11 as a heat source, and the temperature required for the wet oxidation reaction by the catalyst, for example, up to 150 to 250 ° C. Raise the temperature of raw water.

The raw water after the temperature rise is introduced from the lower part of the wet oxidative decomposition column 5, which is a fixed bed filled with the solid catalyst 18. Here, ammonia and methanol, which are dissolved impurities in the raw water, are completely oxidatively decomposed by air in the presence of the catalyst.

 The reaction formula is shown below.

4NH ₃ + 3O ₂ → 2N ₂ + 6H ₂ O 2CH ₃ OH + 3O ₂ → 2CO ₂ + 4H ₂ O Then, the treated water derived from the upper part of the wet oxidative decomposition column 5 is pressure-reduced to a predetermined pressure via the pressure reducing valve 12,
It is introduced from the lower part of the contact cooler 14 filled with the filling material 13. The high-temperature treated water introduced is separated into steam and water, and the steam rises from below the filler 13 to above together with other nitrogen gas, injected air, and carbon dioxide, but sprinkles it from the sprinkler pipe 20 installed at the top. The cooling water is cooled by the cooling water flowing down, and the water vapor is condensed, taken out from the lower part of the contact cooler 14 together with the cooling water, passed through the treated water pump 15, and sent to the low temperature purification device for reuse as treated water 16.

On the other hand, the nitrogen gas, the injected air, and the carbon dioxide gas are cooled by the cooling water sprayed while the filler 13 is rising, and are discharged from the upper part of the contact cooler 14 into the atmosphere as exhaust gas 17. In addition, the water to be sprinkled branches a part of the treated water sent from the treated water pump 15, introduces it into a water-cooled cooler 22 using cooling water 21, and reuses it after cooling it to a predetermined temperature. To be done.

As described above, in the present embodiment, ammonia or methanol contained in the fuel reforming system condensed water can be efficiently removed, and the treated water is sent to the low temperature purification device, and the water treatment by the ion exchange resin is further performed. Because,
Water with high purity can be obtained.

Further, in the water treatment in the low temperature purification device using the ion exchange resin, the ammonia or methanol that has been a load can be removed, so that the efficiency of the water treatment can be improved.

Furthermore, each of the above-mentioned requirements desired as a water treatment device in a fuel cell power generation system can be provided. That is, 1) unmanned, easy to automate and highly reliable 2) low initial / running cost 3) simple equipment, small installation area 4) small amount of waste water and water loss associated with water treatment 5) treatment It has the advantage that the purity of water is high and the load on post-treatment is small.

Thus, by using the water treatment device of this embodiment,
High efficiency simultaneous treatment of ammonia and methanol is possible,
It is possible to realize a low-cost treatment that requires no chemicals for treatment and has no water loss.

* Other Embodiments * The present invention is not limited to the above-described embodiments. As shown in FIG. 3, as a heating device, natural gas, which is the fuel of the fuel cell, is injected and You may use what uses the heat of oxidation reaction. In this case, it can be heated to a higher temperature than the embodiment shown in FIG.

That is, as shown in FIG. 3, the fuel injection device 30 is connected to the air injection device 3, and the gas or liquid fuel 31 is introduced into the fuel injection device 30, where the heating fuel is mixed with the raw water.
Be mixed. Further, a heat exchanger 32 is connected to the fuel injection device 30, where the temperature is raised by heat exchange, and then the solid catalyst
Wet oxidative decomposition column 5 packed with 18 to form a fixed bed
Is introduced from the bottom.

Then, the high temperature treated water after the injected fuel and the dissolved impurities of ammonia and methano are completely oxidatively decomposed in the wet oxidative decomposition column 5 is discharged from the upper part of the wet oxidative decomposition column and sent to the heat exchanger 32 again. After being cooled by heat exchange with the raw water, it is sent to a water cooling cooler 34 using cooling water 33 and cooled to a predetermined temperature.

Next, it is sent to the gas-liquid separator 35 through the pressure reducing valve 12 and separated into a gas phase and a liquid phase, and a gas phase component such as nitrogen gas, injecting air, carbon dioxide gas is discharged into the atmosphere as an exhaust gas 17 from above. It On the other hand, the treated water 16 of the liquid phase from which the vapor phase has been removed is drawn out from the lower portion and is sent to the low temperature purification device by the treated water pump 15.

Also in this case, ammonia or methanol can be efficiently removed as in the above-described embodiment.

[Advantages of the Invention] As described above, according to the present invention, by using the dissolved substance wet oxidation device as the water treatment device of the fuel cell, the harmful ammonia and methanol contained in the fuel reforming system condensed water can be efficiently treated. It is possible to provide a water treatment device for a fuel cell, which can be well removed and can obtain highly pure water.

[Brief description of drawings]

FIG. 1 is a block diagram showing an embodiment of a water treatment device for a fuel cell of the present invention, and FIGS. 2 and 3 are concrete sequences of a dissolved matter wet oxidation device constituting the water treatment device for a fuel cell of the present invention. FIG. 1 ... Wet oxidizer for dissolved substances, 2 ... Condensate of fuel reforming system,
3 ... Air injection device, 4 ... Heating device, 5 ... Wet oxidation decomposition column, 6 ... Gas-liquid separation device, 10 ... Raw water pump,
11 …… Excess steam or hot water, 12 …… Reducing valve, 13 …… Filling material, 14 …… Contact cooler, 15 …… Treatment water pump, 16 …… Treatment water, 17 …… Exhaust gas, 18 …… Catalyst, 19 ……
Pressurized air, 20 ... Sprinkling pipe, 21 ... Cooling water, 22 ... Water cooling cooler, 30 ... Fuel injection device, 31 ... Gas or liquid fuel, 32 ... Heat exchanger, 33 ... Cooling water, 34 …… water-cooled cooler, 35 …… gas-liquid separator.

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Claims (3)

[Claims] 1. A fuel reforming system condensed water produced when reforming a fuel supplied to a fuel cell is treated by a low temperature purifying device using an ion exchange resin and reused as water for use in a fuel cell power generation system. In the water treatment device for a fuel cell configured to perform, an air injecting device for injecting air necessary for oxidative decomposition into the fuel reforming system condensed water, and the fuel solution in which air is injected by the air injecting device. A heating device for heating the quality system condensed water by using the exhaust heat of the fuel cell, and a solid catalyst having an oxidation accelerating substance supported on a heat-resistant water carrier as a fixed bed, and the fuel reforming from the heating device. Wet oxidative decomposition column for removing ammonia and methanol contained in the system condensed water, treated water from which the ammonia and methanol have been removed by the wet oxidative decomposition column, and acid by the wet oxidative decomposition column Water treatment device for a fuel cell, wherein a and a decomposed gas separated the treated water had a wet oxidation apparatus comprising a gas-liquid separator for guiding the cryogenic purifier. 2. The water of a fuel cell according to claim 1, wherein the heating device of the wet oxidation device uses surplus steam generated in the fuel cell power generation system as its overheat source. Processing equipment. 3. The water treatment of a fuel cell according to claim 1, wherein the heating device of the wet oxidation device uses a fuel used in a fuel cell power generation system as its superheat source. apparatus.