JP2013216555A - Hydrogen generating device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To solve the problems wherein, whereas a hydrodesulfurization method is used as a desulfurization method for removing sulfur compounds in a raw material which are harmful to a hydrogen generator, when using generated gas from the hydrogen generator as hydrogen for hydrogenation, such a problem is generated that steam in the generated gas is condensed in a pipe for supplying hydrogen to a hydrodesulfurizer to thereby clog a passage, and in order to remove steam as a countermeasure, a cooling device, a gas-liquid separation vessel, a drain discharge valve and the like are required, to thereby complicate a constitution.SOLUTION: A membrane separator is used as a separation removal means of steam. Gas including separated steam is introduced into a burner and processed.

Description

  The present invention relates to a fuel cell power generator that generates power using a hydrocarbon compound as a raw material. More specifically, the present invention relates to a hydrogen generator that removes water contained in hydrogen gas for hydrodesulfurization supplied to a hydrodesulfurizer that removes sulfur compounds contained in raw materials.

  A fuel cell power generator includes a fuel cell, a hydrogen generator that supplies fuel gas containing hydrogen to the fuel cell, an inverter circuit that converts DC power generated by the fuel cell into AC power, and a control device that controls them Etc. Various types of fuel cells are used. Currently, polymer electrolyte fuel cells are in widespread use. As a hydrogen generator, for example, a steam reforming system in which hydrogen is obtained by catalytic reaction of a hydrocarbon compound as a raw material and steam at a high temperature is widely used. As raw materials, city gas made of natural gas, LP gas, kerosene, biogas and the like are used. Among these, a sulfur compound added as an odorant or a sulfur compound derived from a raw material originally contained in the raw material may be mixed. These sulfur compounds can poison the catalyst used in the hydrogen generator and deprive it of its activity. Therefore, the sulfur compound in the raw material must be removed by a desulfurizer before being supplied to the hydrogen generator. The raw material-derived sulfur compound contains various components, and depending on the raw material, there are those containing a high concentration.

  A hydrodesulfurization method is used as a technique for removing various sulfur compounds contained in a high concentration. In this method, hydrogen is added to the raw material, and a sulfur compound contained in the raw material is hydrogenated to hydrogen sulfide by a hydrogenation catalyst heated to about 200 ° C. to 300 ° C., and this hydrogen sulfide is adsorbed and removed. To be desulfurized. As hydrogen to be added to this raw material, hydrogen generated by a hydrogen generator can be recycled and used. However, since this recycle gas contains a large amount of water vapor, there is a problem that the water vapor condenses in the pipe for supplying the recycle gas to the hydrodesulfurizer, thereby blocking the flow path. If the flow path is blocked and the hydrodesulfurization hydrogen gas is not supplied, the hydrodesulfurizer will not function, and undesulfurized raw material will be supplied to the hydrogen generator. If so, the catalyst of the hydrogen generator is poisoned with sulfur compounds, and the function of the hydrogen generator is degraded.

  Therefore, in the prior art, as shown in Patent Document 1, water vapor contained in the hydrodesulfurization hydrogen gas is condensed and separated.

Japanese Patent No. 4493257

However, in the method of condensing and separating water vapor contained in the recycle gas, for example, a cooling device, a gas-liquid separation container, and an on-off valve for extracting condensed water from the gas-liquid separation container are required, and the configuration is complicated. There was a problem of becoming
The present invention solves the above-described conventional problems, and proposes a hydrogen generator capable of removing water vapor from hydrogen gas for hydrodesulfurization with a simple configuration.

In order to solve the above-described conventional problems, the hydrogen generator of the present invention includes a supply path for supplying a raw material containing hydrocarbons, a supply source of hydrogen gas for hydrodesulfurization added to the raw material, and the hydrogenation. A desulfurizer that removes sulfur compounds from the raw material to which hydrogen gas for desulfurization is added to obtain a desulfurized raw material, a hydrogen generator that generates fuel gas containing hydrogen as a main component from the desulfurized raw material, and a hydrogen generator that is generated A fuel cell that generates electric power using the generated fuel gas, and steam that reduces the water vapor in the hydrodesulfurization hydrogen gas through a water vapor separation means using the hydrogen generator as a supply source for the hydrodesulfurization hydrogen gas And a separator.

  By using the technique of the present invention, water vapor contained in the recycle gas can be separated and removed with a simple configuration.

Schematic configuration diagram of a hydrogen generator in Embodiment 1 of the present invention Schematic configuration diagram of steam separator Schematic configuration diagram of steam separator Schematic configuration diagram of steam separator Schematic configuration diagram of a hydrogen generator in Embodiment 2 of the present invention Schematic configuration diagram of a hydrogen generator in Embodiment 3 of the present invention Schematic configuration diagram of a hydrogen generator in Embodiment 4 of the present invention Schematic configuration diagram of a hydrogen generator in Embodiment 5 of the present invention Schematic configuration diagram of steam separator Schematic configuration diagram of steam separator

  Table 1 shows examples of gas permeability coefficients of silicone rubber that can be used as the water vapor separation membrane of the present invention. A substance with a larger gas permeability coefficient is more likely to penetrate silicone rubber. It can be seen from Table 1 that among the components contained in the recycle gas, water vapor is easily transmitted by orders of magnitude compared to hydrogen and methane. That is, the present inventors have found that silicone rubber has excellent performance as a separation membrane material for separating water vapor from recycled gas. By using the water vapor separation membrane having selective water vapor permeation characteristics in this way, it is possible to separate the water vapor without condensing it, so that it is possible to separate the water vapor with a simpler structure than the conventional technology.

  The hydrogen generating apparatus of the present invention includes a supply path for supplying a raw material containing hydrocarbons, a supply source of hydrogen gas for hydrodesulfurization added to the raw material, and sulfur from the raw material to which the hydrogen gas for hydrodesulfurization is added. A desulfurizer that removes a compound to obtain a desulfurized raw material, a hydrogen generator that generates a fuel gas mainly composed of hydrogen from the desulfurized raw material, and a fuel cell that generates electric power using the fuel gas generated from the hydrogen generator And a steam separator that uses the hydrogen generator as a supply source of the hydrogen gas for hydrodesulfurization and reduces the water vapor in the hydrogen gas for hydrodesulfurization through a water vapor separation means.

  As the water vapor separation means, a water vapor separation membrane can be used.

  The hydrogen generator of the present invention further includes a burner that heats the hydrogen generator using off-gas discharged from the fuel cell as fuel, and a combustion air supply device that supplies combustion air to the burner, and the steam separation The vessel may be configured to move the water vapor in the hydrodesulfurization hydrogen gas into the combustion air through the water vapor separation means.

  As shown in Table 1, although the separation membrane is a small amount together with water vapor, flammable substances such as hydrogen pass through the separation membrane. Therefore, by using the above configuration, the permeated combustible material such as hydrogen can be burned by the burner together with the combustion air, and the permeated combustible material can be safely processed and used as fuel for the burner.

  As a more specific configuration, it has a combustion air flow path configured to supply at least a part of the combustion air discharged from the combustion air supply device to the burner after being introduced into the water vapor separator. May be.

  Alternatively, a suction device is provided between the water vapor separator and the combustion air supply device, a water vapor transmission / outflow side of the water vapor separator is connected to a suction side of the suction device, and a discharge side of the suction device and the combustion air The suction side of the supply device may be connected.

  Alternatively, a combustion air supply device operable at a low suction pressure is provided between the water vapor separator and the burner, and the water vapor permeation outflow side of the water vapor separator is connected to a combustion air suction side pipe of the combustion air supply device In addition, the discharge side of the combustion air supply device and the burner may be connected.

  As the material for the water vapor separation membrane, it is preferable to use a polymer material containing at least one of silicone rubber, polytrimethylsilylpropylene, polyolefin, polysulfone, polyvinylidene fluoride, and polyimide. These polymer materials have the advantage of being inexpensive.

  Further, as the water vapor separation means, a water vapor adsorbent that repeats adsorption and desorption can be used. For example, porous oxide materials typified by zeolite, porous silica, silica gel and the like are frequently used as water vapor adsorbents, and in the present invention, water vapor in hydrodesulfurization hydrogen gas is separated and removed. be able to. Even in this method, the water vapor can be separated without condensing, so that the water vapor can be separated with a simpler structure than the conventional technique.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the following, the same or corresponding elements are denoted by the same reference numerals throughout all the drawings, and redundant description thereof is omitted.

(Embodiment 1)
Hereinafter, an embodiment of a hydrogen generator according to the present invention will be described with reference to FIG.

FIG. 1 is a schematic configuration diagram of a hydrogen generator 1 according to Embodiment 1 of the present invention. The hydrogen generator 1 generates hydrogen using city gas as a raw material gas. The raw material gas supplied from the raw material gas supply source 2 is pressurized by the compressor 3 and its flow rate is adjusted, and is sent to the hydrodesulfurizer 5. A recycle pipe 4 is connected upstream of the compressor 3, and the raw material gas is mixed with hydrodesulfurization hydrogen gas called recycle gas supplied through the recycle pipe 4 and sent to the hydrodesulfurizer 5. The hydrodesulfurizer 5 is filled with a pellet-shaped desulfurization catalyst mainly composed of copper and zinc oxides, and is heated to about 250 to 300 ° C. by a heating means (not shown). City gas, which is a raw material gas, contains a sulfur compound added as an odorant and a sulfur compound originally contained in the raw material. These sulfur compounds react with hydrogen in the recycle gas in the hydrodesulfurizer 5 to change into hydrogen sulfide, and are adsorbed and removed by a desulfurization catalyst. The desulfurized raw material gas is sent to the hydrogen generator 6 and reacts with separately supplied water vapor (not shown) at a high temperature to contain hydrogen, carbon dioxide, carbon monoxide, water vapor, and unreacted raw material. To produce fuel gas. The hydrogen generator 6 has a function of reducing and removing carbon monoxide concentration harmful to the fuel cell 7 therein, and fuel gas whose carbon monoxide concentration is reduced to 10 ppm or less is supplied to the fuel through the fuel gas pipe 8. The battery 7 is supplied. The fuel cell 7 generates electric power using this fuel gas. Unused fuel gas called off-gas that has not been consumed in the fuel cell 7 is burned by the burner 10 in the hydrogen generator 6 through the off-gas pipe 9 and used as fuel for heating the hydrogen generator 6. Air necessary for combustion of the burner 10 is supplied by a combustion fan 11, and combustion exhaust gas is exhausted through a combustion gas pipe 12.

  In the present invention, the recycle gas supplied to the hydrodesulfurizer 5 is branched from the recycle upstream pipe 13 connected to the fuel gas pipe 8, and the on-off valve 14, the water vapor separator 15, the flow control throttle device 16, the recycle. It is supplied via the pipe 4. The steam separator 15 is provided with a flow path through which recycled gas flows and a flow path through which air supplied by the air fan 17 flows. The air supply pipe 18 and the air outlet pipe 19 are air flow pipes supplied by the air fan 17.

  Here, the configuration of the water vapor separator 15 will be described with reference to FIG. The fuel gas supplied from the recycle upstream pipe 13 branches and flows into the plurality of silicone rubber pipes 20 in the water vapor separator 15, and then merges again and flows out from the recycle pipe 4. As described above, silicone rubber is suitable as a water vapor separation membrane because it has excellent separation performance as a water vapor separation membrane material for separating water vapor from fuel gas, and is easily available and inexpensive. An air supply pipe 18 and an air outlet pipe 19 are connected to the outside of the silicone rubber pipe 20. Here, the in-tube channel 21 of the silicone rubber tube 20 is referred to as a supply-side channel, and the extra-tube channel 22 of the silicone rubber tube 20 is referred to as a permeate-side channel.

  The fuel gas flowing into the supply-side flow path 21 from the recycle upstream pipe 13 contains about 20% to 30% of water vapor in terms of molar fraction. When this large amount of moisture condenses in the recycle pipe 4 or the flow rate adjusting throttle device 16, the recycle flow path is blocked, and the hydrodesulfurization hydrogen gas is not supplied to the hydrodesulfurizer 5, resulting in desulfurization. The problem of being unable to do so arises.

  Therefore, in this embodiment, water vapor is separated from the fuel gas flowing in the supply side flow path 21 by selectively permeating the permeation side flow path 22 through the pipe surface of the silicone rubber tube 20, and the water vapor concentration in the recycle gas is reduced. Is reduced. The water vapor that has permeated the permeate side flow path 22 is scavenged by the air flowing through the permeate side flow path, and is released from the air outlet pipe 19 into the atmosphere. The present invention eliminates the need for a recycle gas cooling device, a gas-liquid separation container, and an on-off valve for extracting condensed water from the gas-liquid separation container, which are indispensable in the prior art. The problem of being blocked by water can be solved.

  FIG. 3 shows another configuration example of the water vapor separator. In the water vapor separator 15 of FIG. 2, the supply-side flow path 21 is branched using a plurality of silicone rubber tubes 20. On the other hand, in the water vapor separator 15 ′ of FIG. 3, in order to further simplify the configuration, one silicone rubber tube 23 is spirally molded and arranged. The reason why the silicone rubber tube 23 is spirally formed is to increase the surface area of the silicone rubber tube 23 and increase the water vapor transmission area to ensure a sufficient water vapor transmission rate.

  FIG. 4 shows another configuration example of the water vapor separator. In the water vapor separator shown in FIGS. 2 and 3, since the outside air is directly introduced into the permeate side flow path 22, the water vapor may be condensed in the silicone rubber tube when the outside air temperature is low. Therefore, in the water vapor separator 15 ″ in FIG. 4, a baffle plate 24 is provided in the permeate side flow path 22 so that the outside air does not directly cool the silicone rubber tube 23. In addition, what is necessary is just to employ | adopt suitably the shape of this baffle plate 24 suitably.

  Although not shown, it may be used as a plate instead of the above-described tubular silicone rubber.

(Embodiment 2)
Next, the hydrogen generator in Embodiment 2 of this invention is demonstrated using FIG. In FIG. 5, the same reference numerals are assigned to the same components as those in the above-described embodiment.

  The difference between the second embodiment shown in FIG. 5 and the first embodiment shown in FIG. 1 described above is that the air fan 17 is eliminated, the discharge pipe of the combustion fan 11 is branched into two, and one of them is a throttle for flow rate adjustment. It is connected to the air supply pipe 18 of the water vapor separator 15 through the device 16, and the other pipe 25 is connected to the air outlet pipe 19 and the pipe 26 and connected to the combustion air supply section of the burner 10. . Of course, this configuration eliminates the need for the air fan 17, but a part of the combustion air is used as scavenging air for the permeate side flow path 22 of the water vapor separator 15 and separated from the fuel gas together with the water vapor. Gas can be fed into the flame of the burner 10. As shown in Table 1, the water vapor separator 15 using the silicone rubber as the water vapor separation membrane also permeates hydrogen and methane, though slightly. In order to safely process these combustible gases, the separated gas is burned by the burner 10 in the present embodiment. In addition, although the water vapor | steam isolate | separated from the fuel gas will also be supplied to the burner 10, since it is a small quantity in quantity, it does not have a bad influence on the combustion characteristic of the burner 10.

(Embodiment 3)
Next, the hydrogen generator in Embodiment 2 of this invention is demonstrated using FIG. In FIG. 6, the same numbers are assigned to the same components as those in the above-described embodiment.

  The difference between the third embodiment shown in FIG. 6 and the first embodiment shown in FIG. 1 is that the steam separator 15 does not have the air supply pipe 18 and the air outlet pipe 19 is provided with the suction side of the decompression pump 27. Thus, the inside of the permeation side flow path 22 of the water vapor separator 15 is in a reduced pressure state, and a pipe 28 is provided to connect the discharge side of the pressure reduction pump 27 to the suction side of the combustion fan 11. The driving force when the water vapor separator 15 permeates the water vapor permeable membrane is a partial pressure difference between the permeable component and the permeable membrane, so that the permeation side flow path 22 side is reduced in pressure as in the present embodiment. The separation material can permeate the water vapor permeable membrane. In the present embodiment, unlike the above-described embodiment, since the outside air is not allowed to flow into the permeate side flow path 22, the silicone rubber tube is cooled by the outside air, and the water vapor in the fuel gas is condensed in the silicone rubber tube. There is a feature that the problem does not occur.

(Embodiment 4)
Next, the hydrogen generator in Embodiment 4 of this invention is demonstrated using FIG. In FIG. 7 as well, the same constituent elements as those in the above-described embodiment are given the same numbers.

The difference between the fourth embodiment shown in FIG. 7 and the third embodiment shown in FIG. 6 is that the combustion fan 11 shown in FIG. 6 is first changed to a suction pump type air supply device 30. Thereby, even if the suction side pressure is low, the air supply operation can be performed, and the function of the pressure reducing pump 27 of FIG. A suction device 29 is provided on the suction side of the air supply device 30 to lower the suction side pressure below atmospheric pressure. With this configuration, the decompression pump 27 required in the third embodiment can be eliminated, and the apparatus configuration can be further simplified.

(Embodiment 5)
Next, the hydrogen generator in Embodiment 5 of this invention is demonstrated using FIG. In FIG. 8 as well, the same number is assigned to the same component as in the above-described embodiment.

  The difference between the fifth embodiment shown in FIG. 8 and the above-described embodiment is that a water vapor separator 31 using a water vapor adsorbent is used as the water vapor separator. A typical configuration of the water vapor separator 31 is shown in FIG. In the cylindrical steam separator 31, two cylindrical containers filled with pellet-shaped zeolite are arranged at target positions with respect to the central axis of the steam separator 31, and the entire steam separator 31 further rotates. The motor 33 is configured to rotate. Recycle upstream pipe 13 and recycle pipe 4 are connected to the upstream and downstream sides of water vapor adsorbent 32a on the left side of the figure, respectively, and hydrogen gas for hydrodesulfurization flows through water vapor adsorbent 32 to adsorb water vapor. It is supposed to be removed. On the other hand, on the downstream side and upstream side of the water vapor adsorbent 32b on the right side of the figure, there are an air supply pipe 35 for supplying air sent by the blower 34 and an exhaust pipe 36 for exhausting the air that has passed through the water vapor adsorbent 32b. It is connected. Further, a heater 37 for heating the air supplied to the water vapor adsorbent 32b by the air supply pipe 35 is installed.

  The operation of the hydrogen generator in which such a steam separator 31 is configured will be described. The water vapor adsorbent 32a on the left side of the figure adsorbs and removes water vapor contained in the hydrodesulfurization hydrogen gas sent from the recycle upstream pipe 13 during operation of the hydrogen generator, and the dried hydrogen gas is hydrodesulfurized. Recycle to 5. Before the water vapor adsorption capacity of the water vapor adsorbent 32a is saturated, the water vapor separator 31 is rotated by the rotary motor 33 and moves to the position of the water vapor adsorbent 32b. Since the air heated from below is supplied to the water vapor adsorbent 32b, the adsorbed water vapor is desorbed and discharged together with the air from the exhaust pipe 36, and the water vapor adsorbent 32 is regenerated. While the water vapor adsorbent 32b is being regenerated, the water vapor adsorbent 32a adsorbs and removes the water vapor in the hydrodesulfurization hydrogen gas. Thus, the water vapor separator 31 of the present invention continuously removes the water vapor in the hydrodesulfurization hydrogen gas by repeating the adsorption and regeneration of the water vapor. The present invention eliminates the need for a recycle gas cooling device, a gas-liquid separation container, and an on-off valve for extracting condensed water from the gas-liquid separation container, which are indispensable in the prior art. Water vapor in the hydrogen gas can be removed.

  FIG. 10 shows a modification of the water vapor separator 31. Steam separator 31 In the cylindrical steam separator 31, three or more cylindrical containers filled with pellet-shaped zeolite may be disposed at target positions with respect to the central axis of the steam separator 31.

  Thus, the present invention is not limited to the membrane-type water vapor separation means, but is characterized in that the water vapor is condensed and not separated.

  The hydrogen generator of the present invention can effectively reduce the water vapor in the recycle gas supplied to the hydrodesulfurizer with a simple configuration. Therefore, it is possible to solve a serious problem that the recycle gas pipe is blocked by the condensed water, and it is possible to obtain a hydrogen generator that can be stably desulfurized and used even with a raw material having a high concentration of sulfur compound.

DESCRIPTION OF SYMBOLS 1 Hydrogen generator 2 Raw material gas supply source 3 Compressor 4 Recycle piping 5 Hydrodesulfurizer 6 Hydrogen generator 7 Fuel cell 8 Fuel gas piping 9 Off-gas piping 10 Burner 11 Combustion fan 12 Combustion gas piping 13 Recycling upstream piping 14 On-off valve 15, 15 ′, 15 ″ Steam separator 16 Flow rate adjusting device 17 Air fan 18 Air supply pipe 19 Air outlet pipe 20 Silicone rubber pipe 21 Supply side flow path 22 Permeation side flow path 23 Silicone rubber pipe 24 Baffle plate 25 Piping 26 Piping 27 Pressure reducing pump 28 Piping 29 Throttle device 30 Air supply device 31 Water vapor separator 32 Water vapor adsorbent 33 Rotating motor 34 Blower 35 Air supply piping 36 Exhaust piping 37 Heater

Claims (7)

A supply path for supplying raw materials containing hydrocarbons;
A source of hydrodesulfurization hydrogen gas to be added to the raw material;
A desulfurizer for removing a sulfur compound from the raw material to which the hydrodesulfurization hydrogen gas has been added to obtain a desulfurized raw material;
A hydrogen generator for generating a fuel gas mainly composed of hydrogen from the desulfurization raw material;
A fuel cell that generates electricity using fuel gas generated from the hydrogen generator;
A steam separator that uses the hydrogen generator as a supply source of the hydrodesulfurization hydrogen gas and reduces the water vapor in the hydrodesulfurization hydrogen gas through a steam separation means;
A hydrogen generator comprising:   The hydrogen generator according to claim 1, wherein the water vapor separation means is a water vapor separation membrane. A burner that heats the hydrogen generator using off gas discharged from the fuel cell as a fuel;
A combustion air supply device for supplying combustion air to the burner;
With
The hydrogen generator according to claim 2, wherein the water vapor separator is configured to move water vapor in the hydrodesulfurization hydrogen gas into the combustion air through the water vapor separation means.   The hydrogen generation apparatus according to claim 3, further comprising a combustion air flow path configured to supply at least a part of the combustion air discharged from the combustion air supply device to the burner after being introduced into the water vapor separator. A suction device provided between the water vapor separator and the combustion air supply device;
5. The steam separator according to claim 3, wherein a steam permeation outflow side of the steam separator is connected to a suction side of the suction apparatus, and a suction side of the combustion air supply apparatus is connected to a discharge side of the suction apparatus. Hydrogen generator.   The combustion air supply device is provided between the water vapor separator and the burner, and a water vapor permeation outflow side of the water vapor separator is connected to a combustion air suction side pipe of the combustion air supply device. The hydrogen generator according to claim 3 or 4, wherein the burner is connected to the discharge side of the gas generator.   The hydrogen generator according to claim 1, wherein the water vapor separation means is a water vapor adsorbent that repeats adsorption and desorption.

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