Method and unit for extracting components from a gas mixture, and method for transporting a gas, in particular hydrogen or ammonium

Abstract

The present invention relates to an extraction unit for extracting hydrogen from a gas mixture, the extraction unit comprising: a pipe or vessel having a transition channel for passing the gas mixture in a feed direction from a receiving opening to a distribution opening, the pipe or vessel being arranged to be received in-line within a gas transport pipe; and at least one membrane electrode assembly having at least one anode, a membrane, and a cathode being arranged within the pipe or vessel, the membrane electrode assembly having an anode surface facing the transition channel and a cathode surface facing away from the transition channel and toward a drain separated from the transition channel, the anode and cathode being provided with connectors for a voltage source.

Description

Technical Field

[0001] The present invention relates to a method and unit for extracting components from a gas mixture, and a method for transporting a gas, in particular hydrogen or ammonium.

Background Art

[0002] Hydrogen is becoming increasingly popular as an energy source, and the ability to transport hydrogen is becoming ever more important. At present, a fine-meshed hydrogen distribution network is rare, and hydrogen is delivered by truck, which can transport 200 to 400 kilograms each time, corresponding to the amount required by a vehicle hydrogen filling station in half a day. Although it is not impossible to build a new distribution network for hydrogen, it is more beneficial to use the existing (gas) distribution network for hydrogen transport. This allows the gas distribution network to be used for its original purpose, i.e., the distribution of existing gas, while hydrogen is injected at specific points within the gas distribution network. One of the problems faced in this case is to recover hydrogen from the gas mixture thus created to a level where at least end-users can use their equipment unchanged without difficulty or hindrance. This applies not only to hydrogen but also to all gases that can be selectively transported through a membrane, such as ammonium.

Summary of the Invention

Problems to be Solved by the Invention

[0003] One object of the present invention is to provide an extraction device for extracting components, in particular hydrogen, from a gas mixture. A further object of the present invention is to provide a method for transporting a gas.

Means for Solving the Problems

[0004] According to the present invention, an amount of 1% to 60% by volume of a component, particularly hydrogen, can be added to the gas in the natural gas network. This component is injected into the distribution system at a specific point in the natural gas network and extracted at the point where this component is required. In the case of hydrogen, when the remaining hydrogen after extracting hydrogen from the gas mixture is less than 20%, preferably less than 10%, the end-user equipment (mostly heating and cooking devices) is seen to operate smoothly without change.

[0005] For this purpose, the present invention proposes an extraction unit installed at or near the location where a component, particularly hydrogen, is required. This extraction unit is a pipe or container having a transition channel for passing the gas mixture in the feed direction from the receiving opening to the distribution opening, and is a pipe or container arranged to be received in-line in the gas transport pipe, and at least one membrane-electrode assembly (MEA) arranged in the pipe or container having at least one anode, membrane, and cathode, wherein the anode surface faces the transition channel and the cathode surface is arranged to face a drain separated from the transition channel in the other direction from the transition channel, and voltage source connectors are provided on the anode and the cathode.

[0006] Since the membrane only allows protons to pass through, the component can be selectively extracted from the mixed gas. The proton exchange membrane of the membrane-electrode assembly can be sized such that only a specific component is extracted from the gas mixture.

[0007] The actual proportion of the component extracted from the gas mixture depends on several parameters such as the length and area of the anode and the speed at which the gas mixture flows along the anode surface. It has been shown that it is possible to achieve a reduction of hydrogen to 1% remaining according to the present invention.

[0008] Extraction is, in most cases, accompanied by a gas mixture with a low hydrogen content (5% - 50%). According to the present invention, components between preferably 5% and 25%, more preferably between 8% and 15% can be added. This component content further decreases because while this component is removed as the gas mixture passes through the MEA, the other components of the gas mixture remain. To achieve a sufficiently high recovery rate (% extracted hydrogen), a significant decrease in hydrogen concentration is inevitable. For example, for a 60% recovery rate, the initial hydrogen concentration in the bulk must decrease from (for example) 10% to 4%.

[0009] The extraction unit according to the present invention can also be applied, for example, to purify synthesis gas obtained by gasifying coal or biomass with water, or to extract hydrogen from a helium / hydrogen mixture. In the latter case, hydrogen can be regarded as an impurity of helium obtained from natural sources.

[0010] Another application of the extraction unit according to the present invention may be to extract hydrogen from a nitrogen / hydrogen mixture. In this case, this extraction unit is involved in the cracking of liquefied ammonia into N2 and H2. Ammonia is used as a means of transportation in this case. Ammonia is obtained (preferably from renewable energy) and shipped to locations where hydrogen is required. The liquefied ammonia is catalytically cracked into gas, and then hydrogen is purified from the resulting nitrogen / hydrogen gas mixture.

[0011] As a further application, extraction of hydrogen from steam, which is carried out by a process such as SMR (steam methane reforming) from fossil raw materials (natural gas, light oil, etc.), can be considered.

[0012] Generally, the extraction unit according to the present invention offers the advantages of in-line applicability, low pressure loss and high capacity, as well as economic feasibility. By separating extraction from compression, in combination with a single compressor unit for compressing pure components, such as hydrogen, an inexpensive extraction unit with a large anode surface is sufficient. Instead of the three to five electrochemical compressor stacks required by the prior art to extract and compress components in one step to 40 - 900 bar, the extraction unit according to the present invention allows compression with a single compressor stack in addition to this extraction unit.

[0013] A further advantage is that no hydraulic sealing system such as that in a compressor is required, since the extraction unit according to the present invention can operate in-line, particularly in a pipeline, with little pressure difference. This gives more freedom in material selection. Unlike solid compressors, the extraction unit according to the present invention does not require high-pressure steel. This significantly reduces the cost of the unit even when a larger area of membrane / MEA surface is required. When operating with a low differential pressure, little additional energy is required to overcome the Nernst voltage applicable in the case of a compressor.

[0014] Yet another advantage is that a relatively large amount of gas passes through the membrane and the membrane can be passively cooled by this gas flow. As a result, no water cooling circuit is required within the cell, simplifying the design and reducing costs.

[0015] To increase the device efficiency, the anode surface can extend non-linearly between the receiving opening and the distribution opening so as to increase the contact surface for passing gas by increasing the contact length. Suitable configurations include, for example, a configuration in which the anode surface is serpentine, or a configuration in which the anode surface is oriented in a zigzag serrated shape. Such a shape has a longer actual length compared to the length of the tube or container, so that the gas mixture can contact the anode, and at the same time, hydrogen can be extracted. Furthermore, a better distribution of the current across the entire membrane is achieved in this way, and thus better heat and water management and lower energy consumption are achieved.

[0016] To create a space for a relatively large anode surface, there may be an expansion in the cross-section of the tube or container between the receiving opening and the anode surface. Also, there may be a taper in the cross-section of the tube or container between the anode surface and the distribution opening so that the extraction unit can be incorporated into a standard gas delivery network.

[0017] Also, at least one baffle extending in a direction component perpendicular to the feeding direction for moving the gas mixture along the anode can be located within the transition channel. The extraction unit can further include a component compressor such as a compressor for the components connected to the discharge channel, particularly a solid compressor, and can further be provided with a voltage source connected to the anode and the cathode.

[0018] The cathode can preferably be provided with a channel structure for a coolant. In the first usage form of the extraction unit according to the present invention, a coolant such as H2O can be circulated using the channel structure.

[0019] The present invention also relates to a method for extracting components such as hydrogen from a gas mixture, the method including passing the gas mixture through the above extraction unit, applying a voltage between the anode and the cathode by a voltage source, and passing the components extracted from the gas mixture through the discharge channel.

[0020] Components such as hydrogen can be inserted into the gas or gas mixture, and this method can further include transporting the gas or gas mixture together with hydrogen through a gas transport pipe, passing the gas or gas mixture together with hydrogen through an extraction unit, and removing hydrogen from the gas or gas mixture.

[0021] The average surface current density of the entire membrane is 1.0 A / cm 2 less than, particularly 0.5 A / cm 2 and can be set.

[0022] The present invention also relates to the above method including supplying components such as oxygen to the cathode side to wet the membrane to improve efficiency, or removing contaminants from the catalyst to improve the efficiency of the device.

[0023] The present invention will be described in more detail with reference to the following drawings.

Brief Description of the Drawings

[0024]

Figure 1

Figure 2

Figure 3

Modes for Carrying Out the Invention

[0025] Figure 1 shows a cross-sectional view of an extraction unit according to the present invention. This extraction unit is a tube or container having a transition channel 6 for passing a gas mixture in a feed direction from an inlet opening 1 to a distribution opening 8, the tube or container being arranged to be received in-line within a gas transport pipe, and at least one membrane electrode assembly 4 arranged within the tube or container and having at least one anode, a membrane, and a cathode, the anode surface facing the transition channel and the cathode surface being arranged to face a drain 5 separated from and away from the transition channel, and voltage source connectors being provided for the anode and the cathode. The anode surface extends non-linearly between the inlet opening and the distribution opening so as to increase the contact surface for passing gas by increasing the contact length. The anode surface is oriented to meander. There is an expansion 2 in the cross-section of the tube or container between the inlet opening and the anode surface, and a taper 7 in the cross-section of the tube or container between the anode surface and the distribution opening. Furthermore, within the transition channel, there is a baffle 3 extending in a direction component perpendicular to the feed direction.

[0026] Figure 2 shows a schematic view of the operating principle of the extraction unit according to the present invention. This figure shows a transition channel 12 for passing a gas mixture, a membrane electrode assembly comprising an anode 9, a membrane 10, and a cathode 11, and a drain 14 separated from the transition channel, and voltage source connectors being provided for the anode and the cathode. Hydrogen 13 is extracted from the transition channel 12.

[0027] Figure 3 shows further detailed configurations of the configuration of Figure 2 corresponding to the first usage form of the extraction unit according to the present invention. In this example, a component such as hydrogen is added to a gas or gas mixture, and this gas mixture is transported through a tube or container 16 provided with an anode. The membrane 17 is configured to selectively pass a component, in this example hydrogen, when a voltage is applied between the cathode and the anode. The cathode 18 is provided with a channel structure, and water is provided as a coolant to this channel structure by a pump 20, and the coolant is drained again from this channel structure. A component, for example hydrogen, is extracted from the gas mixture and dried by a dryer 21. This component can be compressed to a higher pressure in a further processing step, for example to fill a vehicle tank.

Claims

1. An extraction unit for extracting a contained component from a gas mixture fed through a gas transport pipe, comprising: A pipe or container having a transition channel for passing the gas mixture in a feed direction from an inlet opening to a distribution opening, the pipe or container being arranged to be received in-line within the gas transport pipe; At least one membrane electrode assembly having at least one anode, a membrane, and a cathode, the at least one membrane electrode assembly being disposed within the pipe or container; In the membrane electrode assembly, the surface of the anode faces the transition channel, and the surface of the cathode faces a drain separated from the transition channel, and electrical connectors are provided on the anode and the cathode; An extraction unit, wherein at least one baffle extending in a direction perpendicular to the feed direction is provided within the transition channel.

2. The electrical connector is for connection to a power source, and the anode surface extends non-linearly between the inlet opening and the distribution opening so as to increase a contact surface for passing gas by increasing a contact length, the anode surface being serpentine or provided with a zigzag serration, the extraction unit according to claim 1.

3. The extraction unit according to claim 1 or 2, wherein there is an expansion in a cross-section of the pipe or container between the inlet opening and the anode surface.

4. The extraction unit according to any one of claims 1 to 3, wherein there is a taper in a cross-section of the pipe or container between the anode surface and the distribution opening.

5. The extraction unit according to any one of claims 1 to 4, comprising a compressor for the contained component connected to the drain.

6. The extraction unit according to any one of claims 1 to 5, comprising a voltage source connected to the anode and the cathode.

7. The extraction unit according to any one of claims 1 to 6, wherein the cathode has a coolant channel structure.

8. The extraction unit according to any one of claims 1 to 7, wherein the cathode has a channel structure for wetting the membrane.

9. A method for extracting hydrogen from a gas mixture, comprising passing the gas mixture through the extraction unit according to any one of claims 1 to 8, applying a voltage between the anode and the cathode by a voltage source, and passing the contained component extracted from the gas mixture through the drain.

10. The method according to claim 9, wherein the gas mixture is a mixture containing helium and hydrogen generated from the extraction of helium from natural sources.

11. The method according to claim 9, wherein the gas mixture is a mixture containing ammonia that decomposes into nitrogen and hydrogen.

12. The gas mixture is H ２ and CO ２ and CO, and is a mixture formed by a steam methane reforming process from fossil raw materials such as natural gas and / or light oil. The method according to claim 9.

13. A method for transporting a contained component contained in a gas mixture, comprising supplying the contained component to a gas or gas mixture, transporting the gas or gas mixture together with the contained component through a gas transport pipe, and passing the gas or gas mixture together with the contained component through the extraction unit according to any one of claims 1 to 8, and extracting the contained component from the gas or gas mixture according to the method according to claim 9.

14. The method according to claim 13, wherein the volume percentage of the contained component in the gas mixture is between 5% and 25%.

15. The current density of the entire membrane is 0.5 A / cm ２The method according to any one of claims 9 to 14, which is less than.

16. The method according to any one of claims 9 to 15, comprising supplying oxygen at the cathode side to wet the membrane or removing contaminants from the catalyst to enhance the efficiency of the extraction unit.

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