Treatment of compressed gaseous hydrogen

Abstract

The present invention relates to a system for treating gaseous hydrogen, comprising an inlet (10a) for supplying gaseous hydrogen, a drying unit (30) with an active drying material for removing moisture from the supplied hydrogen, an adsorption unit (50) with an active adsorption material for adsorbing impurities from the dried hydrogen, and an outlet (10b) for drawing off treated hydrogen. According to the invention, the mass ratio between the active drying material and the active adsorption material is in the range of 1.5:1 to 50:1. The invention further relates to a plant comprising such a system for providing compressed treated gaseous hydrogen and a method for treating gaseous hydrogen.

Claims

1. System for treating gaseous hydrogen, comprising: an inlet (10a) for supplying gaseous hydrogen a drying unit (30) with an active drying material for removing moisture from the supplied hydrogen an adsorption unit (50) with an active adsorbent material for adsorbing impurities from the dried hydrogen, and an outlet (10b) for drawing off treated hydrogen wherein the mass ratio between the active drying material and the active adsorption material is in the range of 1.5:1 to 50:1.

2. System according to claim 1, wherein the drying unit (30) comprises, as the active drying material, a molecular sieve or alternative drying materials, such as silica gels.

3. System according to claim 1, wherein the adsorption unit (50) comprises activated carbon as the active adsorption material.

4. System according to claim 1, further comprising at least one pressure dew point sensor (20b) disposed downstream of the drying unit (30).

5. System according to claim 1, further comprising at least one further pressure dew point sensor (20a) disposed upstream of the drying unit (30).

6. System according to claim 4, further comprising a control unit (110) that is coupled to the at least one pressure dew point sensor (20a, 20b) to receive the said sensor data and is adapted to trigger a predefined action when a predefined pressure dew point threshold is exceeded.

7. System according to claim 1, further comprising: a micro-separation unit (40) disposed upstream or downstream of the drying unit (30), and/or a post-drying unit (60) disposed downstream of the adsorption unit (50), and/or a particle filter (70) disposed downstream of the adsorption unit (50) and, if applicable, the post-drying unit (60), and/or a minimum pressure valve (80) disposed downstream of the adsorption unit (50) and, if applicable, the post-drying unit (60) and/or the particle filter (70), and/or a pressure relief unit (90) disposed upstream of the outlet.

8. Plant (100, 200) for providing compressed treated gaseous hydrogen, comprising: a compressor (120) for compressing supplied gaseous hydrogen, and a system for treating the compressed gaseous hydrogen according to claim 1, wherein the compressor (120) is disposed upstream or downstream of the drying unit (30).

9. Plant (100; 200) according to claim 8, wherein the compressor (120) is of multi-stage design; and/or wherein at least one heat exchanger is assigned to the compressor (120), a heat exchanger possibly being placed downstream of each of the compressor stages; and/or a separator unit is provided for separating liquid aerosol components in the gas flow after the heat exchangers.

10. Plant (100; 200) according to claim 8, further comprising a system control unit (110) which is adapted to switch off the compressor (120) when it is detected that the predefined pressure dew point threshold value has been exceeded.

11. Method of treating gaseous hydrogen by means of a system for treating compressed gaseous hydrogen, preferably according to claim 1, or in a plant (100; 200) for providing compressed treated gaseous hydrogen, wherein said plant comprises a compressor (120) for compressing supplied gaseous hydrogen, and a system for treating the compressed gaseous hydrogen according to claim 1, wherein the compressor (120) is disposed upstream or downstream of a drying unit (30), comprising the following steps: feeding the gaseous hydrogen at an inlet of the system (10a) removing moisture from the supplied hydrogen in a drying unit (30) of the system adsorbing impurities from the dried hydrogen in an adsorption unit (50) of the system, and drawing off treated hydrogen at an outlet (10b) of the system.

12. Method according to claim 11, further comprising the triggering of a predefined action when at least one predefined pressure dew point threshold is exceeded.

13. Method according to claim 12, wherein a warning is issued when a first predefined pressure dew point threshold value is exceeded, and a shutdown of the system and/or the plant (100; 200) is initiated when a second predefined pressure dew point threshold value is exceeded.

14. Method according to claim 11, wherein the treated hydrogen satisfies the requirements of DIN EN 17124 or ISO 14687.

15. Method according to claim 11, comprising the compression of hydrogen to a pressure of up to 350 bar or higher.

Description

[0036] FIG. 1A A process flow chart of a first embodiment of a plant according to the invention,

[0037] FIG. 1B A process flow chart of a second embodiment of a plant according to the invention, and

[0038] FIG. 2A schematic representation of various components of the plants according to the invention shown in FIGS. 1A and 1B.

[0039] FIG. 1A shows a first embodiment of a plant according to the invention by means of a process flow chart, the plant being generally designated by the reference sign 100. At an inlet 10a, gaseous hydrogen produced by electrolysis of water, for example, is fed to the plant 100. The pressure dew point of the delivered hydrogen is first determined by means of a first pressure dew point sensor 20a before the hydrogen is supplied to a drying unit 30. In this drying unit 30, an active drying material is provided for removing moisture from the supplied hydrogen, and after the drying step a second pressure dew point sensor 20b can be used to track the result of the drying step.

[0040] For this purpose, the two dew point sensors 20a and 20b are coupled to a control unit 110 of the plant 100 which is adapted to check the data supplied by the two dew point sensors 20a and 20b in order to determine whether the drying step has been carried out in the desired manner and whether or not, for example, the drying unit 30 is already saturated. This also makes it possible already to monitor the moisture content of the delivered hydrogen and suitable measures can be taken if a predefined acceptable value range is exceeded. Furthermore, the control unit 110 is coupled to the compressor 120 referred to below and may be adapted to shut down the compressor 120 when at least one predefined pressure dew point threshold is exceeded, particularly at the dew point sensor 20b, to prevent compression of insufficiently purified hydrogen.

[0041] The second dew point sensor 20b is now followed by the compressor 120 just mentioned, which can be configured, for example, as a multi-stage compressor, heat exchangers for cooling the compressed hydrogen as well as separator units for separating liquid aerosol components in the gas flow being provided between the individual compression stages. The hydrogen gas compressed in this way is now fed to a final micro-separation unit 40 in which are deposited droplet-shaped aerosols and moisture which can be temporarily stored at arrow 40a and subsequently removed from the plant 100.

[0042] Downstream of the micro-separation unit 40, an adsorption unit 50 is subsequently provided in which an active adsorption material for adsorbing impurities from the dried hydrogen is accommodated, for example activated carbon within a replaceable cartridge or as a user-replaceable bulk material. This is followed by a post-drying unit 60 which, particularly after replacement of the active adsorption material in the adsorption unit 50, can first absorb residual moisture contained therein which has passed into the purified hydrogen gas.

[0043] Similarly, a particle filter 70 is provided downstream of the post-drying unit 60, which may possibly filter out any solid particles remaining in the hydrogen gas at this point, such as may have been entrained from the adsorption unit. Downstream of this is a minimum pressure valve 80, which serves to ensure a necessary dwell time of the hydrogen in the upstream components, in particular the drying unit 30 and the adsorption unit 50.

[0044] Finally, upstream of its outlet 10b, at which the treated compressed hydrogen gas can be drawn off, the plant 100 further comprises a pressure relief unit 90 which allows safe and hazard-free pressure relief in the plant 100 in a manner known per se. Within the plant 100, the components inlet 10a, pressure dew point sensors 20a and 20b, drying unit 30, micro-separation unit 40, adsorption unit 50, post-drying unit 60, particle filter 70, minimum pressure valve 80, pressure relief unit 90 and outlet 10b form a system according to the invention for treating hydrogen, with the control unit 110 also forming at least part of the system with regard to its functionality.

[0045] An alternative second embodiment of a system according to the invention is further shown in FIG. 1B and designated by the reference sign 200. Regarding the description of its individual components, reference should be made to the first embodiment just described. In particular, the plant 200 includes the exact same components as in the embodiment of FIG. 1A, but disposed in a modified sequence.

[0046] It should be noted, in particular, that in the embodiment 200 of FIG. 1B, the compressor 120 is disposed immediately downstream of the first pressure dew point sensor 20a, so that compressed gaseous hydrogen is already fed to the drying unit 30. Consequently, whereas in the embodiment of FIG. 1 the drying unit 30 and the adsorption unit 50 are provided upstream and downstream of the compressor 120 respectively, that is to say, in a low-pressure region and a high-pressure region of the plant 100 respectively, in the embodiment of FIG. 1B both the drying unit 30 and the adsorption unit 50 lie downstream of the compressor 120, that is to say, in a high-pressure region.

[0047] Here it should be noted, however, that in both of the shown embodiments of FIGS. 1A and 1B, the mass ratio according to the invention between the active drying material of the drying unit 30 and the active adsorption material of the adsorption unit 50 is in the same range of between 1.5:1 and 50:1, while the provision of the pressure dew point sensors 20a and 20b similarly makes it possible to monitor the gas quality of the hydrogen in the manner described.

[0048] It should further be noted that not all of the components just described are necessarily present in all possible embodiments. For example, if an active adsorption material is used that does not tend to release residual moisture to the gas flow, the downstream provision of a post-drying unit could be omitted. Furthermore, it should be noted that in other possible variants of systems according to the invention, the corresponding components may also be disposed in different sequences. For example, the drying unit 30 and the adsorption unit 50 could be disposed directly one after the other, in which case it would even be conceivable to integrate the two units, for example in a single housing or even a single cartridge, if the corresponding active materials are disposed in a suitable manner one after the other in the flow direction of the hydrogen gas.

[0049] For further explanation of the components used in the plants 100 and 200, reference is further made to FIG. 2, in which various components are schematically shown in cross-sectional views, in particular the drying unit 30 and the adsorption unit 50, the micro-separator 40 and the particle filter 70.

[0050] It should be noted here that the drying unit 30 and the adsorption unit 50 may each be formed in a similar manner by a pressure filter vessel as shown in FIG. 2 above. This comprises a pressure-tight housing 32 having an inlet 34 and an outlet 36, a corresponding cartridge being insertable into the housing 32. Thus, either the drying unit 30 or the adsorption unit 50 can be implemented in this way by inserting into the housing 32 either a drying cartridge 38 filled with a molecular sieve or other suitable desiccant, for example silica gel, or an adsorption cartridge 58 filled with, for example, activated carbon. Consequently, two similarly constructed pressure filter vessels can be used in the plants 100 and 200 respectively, which act as the drying unit 30 and the adsorption unit 50, depending on the cartridge with which they are equipped.

[0051] In both cases, the corresponding components act in such a way that the gas flow entering through inlet 34 flows freely upward and then passes downward through the layers of molecular sieve or activated carbon provided in the corresponding cartridges 38 and 58 respectively. The hydrogen gas treated in this way then exits the housing 32 at the outlet 36 and can be further treated in the next component of the system. At this point it should also be mentioned that, in certain variants of the system according to the invention, it is also possible to integrate the drying unit 30 and the adsorption unit 50 in such a way that the upper layers of the corresponding cartridge shown in FIG. 2 through which the hydrogen gas first flows contain the active drying material and the lower layers contain the active adsorption material. In this way, both components can be accommodated in a single housing 32, which on the one hand saves space and expense, but on the other hand only allows the two active materials to be replaced together and is therefore less flexible. For the sake of completeness, at this point it should also be mentioned that in alternative embodiments, especially in larger plants, active drying and adsorption materials in the form of bulk material in appropriate containers can also be used instead of the cartridges shown here.

[0052] FIG. 2, bottom left, shows the micro-separator 40 in a similar manner. This also comprises a housing 42 having an inlet 44 and an outlet 46, plus a coalescing filter 48 disposed in the housing 42. This separates the aerosols contained in the gas flow from the gaseous phase, so that the purified gas flow can be removed at the outlet 46 and fed to the next component of the plant 100 or 200, while the aerosols accumulate at the bottom of the vessel and can be removed at point 40a at a suitable time, as already mentioned above.

[0053] Lastly, FIG. 2, lower right, shows the particle filter 70 which also includes a housing 72, an inlet 74, and an outlet 76. Similar to the drying unit 30 and the adsorption unit 50, here the hydrogen gas to be purified enters the housing 72 from below, flows freely upwards, passes a filter cartridge which is equipped with a suitable filter medium, and then leaves the particle filter 70 via the outlet 76 in order to be subsequently fed to the next component of the plant 100 or 20