Apparatus for drying hydrogen

Abstract

An apparatus for treating fluid, in particular for drying hydrogen gas, comprising an inlet (10) for the fluid to be treated to flow in and comprising an outlet (12) for the treated fluid to flow out and also comprising a treatment device (14) provided between the inlet (10) and the outlet (12), characterized in that at least one jet pump (16, 18) is used at least for part of the transport of fluid through at least part of the treatment device (14).

Description

[0001] DEVICE FOR DRYING HYDROGEN

[0002] The invention relates to a device for treating fluid, in particular for drying hydrogen gas, with an inlet for the inflow of the fluid to be treated and with an outlet for the outflow of the treated fluid, as well as a treatment device arranged between the inlet and the outlet.

[0003] WO 2014 / 016057 A1 discloses an electrolyzer for generating the product gases hydrogen and oxygen, wherein a drying unit is provided for drying the product gas hydrogen. The drying unit contains a multi-circuit heat exchanger with a first circuit for cooling the hydrogen and a second circuit for cooling the oxygen, with both circuits of the multi-circuit heat exchanger sharing a common cooling circuit. In this way, the oxygen is cooled along with the hydrogen and thus dried simultaneously. Downstream of the heat exchanger, the cooled and thus dried oxygen contains only a small amount of water, so that any measurement errors when detecting the hydrogen concentration by a hydrogen sensor are significantly reduced.WO 2015 / 197233 A1 discloses a device for drying gases, in particular for drying natural gas, comprising a gas inlet for the inflow of moist gas into the device, a gas outlet for the outflow of dried gas from the device, at least two adsorption chambers for receiving desiccant, an inlet line for connecting the gas inlet to the adsorption chambers, and an outlet line for returning dry gas from the outlet line through at least one of the adsorption chambers into the inlet line. To achieve particularly energy-efficient cooling of the regeneration stream, the known solution proposes providing at least one cooling line for introducing moist gas from the inlet line into one of the regeneration lines.

[0004] For fluid transport, in particular in the form of gas(es), through the respective fluid treatment facility with its individual components, which are regularly connected to one another via pipelines, conveying devices such as hydraulic pumps or compressors are used, which must be regularly maintained and for whose operation conventional lubricants are used, whereby it cannot be ruled out that lubricant and abrasion particles reach the actual transport side and thus contaminate the fluid to be transported, for example in the form of hydrogen gas.

[0005] Based on this prior art, the invention seeks to create a device for treating fluid that is improved over known solutions. This object is achieved by a device having the features of patent claim 1 in its entirety.

[0006] Because, according to the characterizing part of patent claim 1, at least one jet pump, also technically referred to as a "jet pump," is used for at least part of the transport of fluid through at least part of the treatment device, a transport or conveying device for fluid, in particular in the form of hydrogen gas, is created that does not require any drivable components, such as movable pump or compressor parts that are to be lubricated by means of a lubrication device. Preferably, however, several jet pumps, particularly preferably two jet pumps, are used. By eliminating lubrication for movable components, there is also no risk of lubricant or abrasion particles generated during operation accidentally reaching the clean side, i.e., the conveying side of the device containing the fluid to be transported.This prevents contamination from entering the fluid or gas side of the device, and the downstream utilization or processing equipment, such as compressor systems, which can react very sensitively to contamination, is spared, thus enabling their reliable operation. Furthermore, the fluid transport and delivery equipment, in the form of jet pumps, does not need to be driven. In particular, motors for driving pumps and / or compressors are eliminated, which helps save energy.

[0007] Furthermore, the use of at least one, preferably two, jet pumps instead of at least one mechanically driven hydraulic pump or compressor also eliminates static charges that could lead to ignition processes, which would be extremely dangerous in hydrogen applications. The device according to the invention therefore also meets the highest safety standards.

[0008] In a preferred embodiment of the device according to the invention, it is provided that an inlet of the respective jet pump is connected to one part of the treatment device, an outlet to another part of the treatment device, and a suction connection of the respective jet pump is connected to the other part of the treatment device. While a type of pretreatment of the fluid is initiated by one part of the treatment device, a post-treatment can take place via the other part, wherein in a particularly advantageous manner the post-treated fluid is fed to the respective jet pump via the suction connection, at which a negative pressure prevails via the Venturi effect, which is generated by means of the main flow from the inlet to the outlet of the respective jet pump.In a particularly advantageous manner, it is provided that the mentioned pretreatment with one part of the treatment device serves to remove at least one gaseous component from the fluid by means of catalysis in a first station and / or to separate further components from the fluid, such as water, by means of condensation in a second station.

[0009] In a further preferred embodiment of the device according to the invention, it is provided that the further part of the treatment device has at least two drying devices which can be controlled by means of a common valve device in such a way that a part of the fluid, starting from the respective jet pump, flows through at least one drying device in the direction of the outlet, whereas at least one further drying device can be regenerated starting from this outlet in the direction of the suction connection of a jet pump, preferably in countercurrent.In this way, the fluid can be treated reliably and quasi-continuously by means of at least one dryer device, in the sense of a type of post-treatment, in a predetermined fluid flow direction. At the same time, at least one further dryer device arranged parallel to the one dryer device is regenerated, preferably in countercurrent, in order to then subsequently serve to dry the fluid again by the respective jet pump. In a particularly advantageous manner, it is further provided that a particle cleaning device is connected as a third station in the fluid path between the respective dryer device and the outlet.A dried fluid, such as dried hydrogen, is often contaminated with particles, which are filtered out of the fluid, preferably by means of conventional particle filters, before the thus cleaned fluid is used for further purposes, such as high compression in relevant compressor systems.

[0010] In a further preferred embodiment of the device according to the invention, it is provided that, viewed in the direction of fluid flow, after the third station, a further fluid path opens into a branch before the outlet. A heating device is connected to the fourth station, which supplies heated fluid for the regeneration of at least one of the dryer devices. Particularly when using dryer devices with molecular sieves, it can be advantageous to carry out the regeneration or cleaning at very high temperatures.

[0011] Since liquid, such as water, is produced during the regeneration of the respective dryer device, it is advantageous for the respective dryer device to be connected at its outlet to a fifth station, which serves for condensation drying, during the regeneration process. Within a closed circuit, the outlet of the fifth station can preferably be connected to the suction port of the respective jet pump, viewed in the direction of fluid flow, and the respective jet pump initiates the pumping of fluid during regeneration operation with the associated dryer device and the fifth station.

[0012] In a further preferred embodiment of the device according to the invention, two jet pumps, preferably of equal flow rate, are connected together on the inlet side to the outlet of the second station and can be connected alternately on the outlet side to one of the dryer devices. If the jet pumps do not have the same flow rate, cascading of the fluid flow during pre- and post-treatment can also be achieved using jet pumps of different sizes. If necessary, the device can also be operated with just one jet pump and any other jet pumps can be taken out of operation for maintenance or replacement. The intended flow rate can also be different; for example, one small and one or more larger jet pumps can be used.Likewise, several small jet pumps can be used with a larger jet pump, relative to the flow line.

[0013] The device presented above is preferably used for drying hydrogen gas; however, other gases, including suitable liquids, can also be treated in this way.

[0014] In a method for operating a device as presented above, hydrogen gas can be passed to at least one dryer using at least one jet pump for the purpose of performing a drying process for this gas. At the same time, the purified and highly heated gas flows countercurrently through at least one further dryer. After passing through a condensation drying stage, the gas reaches the inlet side of one dryer for hydrogen gas drying via the suction connection of the respective jet pump. In this way, highly dynamic material flows can be handled.

[0015] The device according to the invention is explained in more detail below using an exemplary embodiment shown in the drawing. The single figure, in a schematic representation not to scale, shows the essential components of the device in the form of a circuit diagram, which also explains the method to be carried out in more detail.

[0016] The device shown in the figure is used to treat fluids, in particular to dry hydrogen gas. The device has an inlet 10 for the inflow of the fluid to be treated and an outlet 12 for the outflow of the treated fluid. A treatment device, designated as a whole by 14, for the respective fluid is arranged between the inlet 10 and the outlet 12. Furthermore, an essential component of the treatment device 14 is at least one jet pump 16, and in the exemplary embodiment shown in the figure, a further jet pump 18 is used, which is preferably of the same design as the first jet pump 16. The flow rate provided for the individual jet pumps can also be different, so that the jet pumps differ in their size. For example, a correspondingly large jet pump can interact with a smaller one or several smaller jet pumps.

[0017] In the present embodiment, the inlet 10 is to be connected to an outlet of an electrolyzer 20, which is only symbolically represented in the figure in the form of a block diagram. The electrolyzer 20 used here serves to generate hydrogen gas, which is delivered to the inlet 10 of the treatment device 14. Due to its design, the electrolyzer 20 can deliver different volume and mass flows of hydrogen. In addition, the hydrogen delivered by the electrolyzer 20 contains a wide variety of impurities, such as oxygen, but also particulate contaminants. The contaminated hydrogen obtained from the electrolysis is passed on via the inlet 10 to a first station 22 of the treatment device 14. In this first station 22, the oxygen content is converted with hydrogen to water, assisted by a suitable catalyst.The principle of catalytic gas purification is heterogeneous catalysis on fixed catalysts. Heterogeneous catalytic reactions are significantly influenced by the adsorption behavior of gas molecules on catalytic surfaces. Precious metal catalysts such as platinum, palladium, or ruthenium have proven particularly suitable for the aforementioned conversion. They are particularly suitable for removing oxygen from a hydrogen stream by means of catalytic gas purification, converting the oxygen into the harmless compound water. The water thus produced in the first station 22 can be discharged from the first station 22 via an outlet point 24, for example, by gravity separation.

[0018] During the pretreatment, remaining fluid from the first station 22 then passes into the second station 26. In this second treatment stage, the gas stream is condensed via a cooling system and the condensate produced in this way, usually in the form of water, is in turn separated in an associated separation device and discharged to the outside of the second station 26 via an outlet point 28.

[0019] As can also be seen from the figure, an inlet 30 of the respective jet pump 16, 18 is connected to a part of the treatment device 14, here in the form of the two stations 22 and 26. The fluid flow or the gas flow is shown in the figure with its flow direction using arrows. An outlet 32 ​​of the respective jet pump 16, 18 is in turn connected to another part of the treatment device 14, which includes post-treatment of the gas flow. Furthermore, the respective jet pump 16, 18 has a suction connection 34, which is also connected to the other part of the treatment device 14, which will be explained in more detail below. The aforementioned arrow representation, with its individual arrows, is also intended to indicate that a pipe connection (not shown in detail) exists from one component to the next component.Such a structure using pipes or fluid lines is common, so it will not be discussed in more detail here.

[0020] Two valves 36 are connected to the connecting line between the outlet of the second station 26 and the respective inlet 30 of the two jet pumps 16, 18, which control the fluid connection in this respect.

[0021] The two outlets 32 of the two jet pumps 16, 18 open into a common discharge line, which in turn divides into two fluid paths 38, 40. Each fluid path 38, 40 is associated with a valve 42, 44. Starting from the two valves 42, 44, the fluid paths 38 and 40 open onto the inlet side of an associated dryer device 46, 48.

[0022] Furthermore, a connecting line 50 with two further valves 52, 54 is connected between the two fluid paths 38, 40.

[0023] The respective dryer device 46, 48 is a so-called adsorption dryer filled with a suitable desiccant. The drying process in question operates according to the so-called sorption principle. A bed of zeolite A, for example, can serve as the desiccant. The gas coming from the jet pumps 16, 18 flows through the active dryer device 46 or 48 in the flow direction, i.e., from bottom to top as viewed in the figure, and leaves it largely dry. The inactive dryer device 46 or 48 is then regenerated with a partial flow in the opposite flow direction, which will be explained in more detail below. As a rule, one dryer or dryer device 46 or 48 is always loaded up to the load limit, and the other dryer device 48 or 46 is then regenerated.By switching the valves 42, 44, 52 and 54 accordingly, it is possible to switch back and forth between the drying devices 46, 48, so that one of the two is always loaded and the other is always regenerated.

[0024] The respective upper outlet of the dryer devices 46, 48 in turn opens into an associated outlet-side fluid path 56, 58, which in turn each have a valve 60, 62 at their ends. Upstream in the direction of flow, two further valves 66 and 68 are located in a further intermediate line 64. After passing the two valves 60, 62, the two outlet-side fluid paths 56 and 58 open into a common connecting line leading to a third station 70. This third station 70 consists of an optional cooling unit with a downstream particle filter, which, as a type of gas filter, removes any unwanted particulate contaminants that may arise during the process from the gas stream, in particular the hydrogen stream.Fluid, such as hydrogen gas, which has been dried in this way and cleaned of particulate contamination, then enters via the outlet 12 into a further application area 72, which is again symbolically represented in a block diagram and which can consist, for example, of a conventional compressor system with which the hydrogen can be liquefied at a high compression level.

[0025] As the figure further shows, after the third station 70, viewed in the direction of fluid flow, a branch 74 may be present upstream of the outlet 12, which in turn opens into a fluid path 76 leading to a fourth station 78, in the form of a heating device. This heating device, in the form of station 78, provides heated fluid for the regeneration of one of the two dryer devices 46 or 48. The fourth station 78 is essentially a gas flow heater, and thus a connection in the form of branch 74 is located at the system outlet 12, from which a partial flow of gas can be raised via the flow heater of the fourth station 78 to the temperature level required for dryer regeneration, quite easily in a range of 200 to 300°C.The gas heated by the fourth station 78 then passes via a discharge line 80 to a connection point 82 between the two valves 66, 68 in the further intermediate line 64. Furthermore, a supply line 84 engages in the connecting line 50 at a connection point 86 between the two valves 52, 54. The supply line 84 leads on the inlet side to a fifth station 88, which in turn serves to cool the gas stream, and any condensate that occurs is separated in a separation device, comparable to that already described for the second station 26. Both the two dryer devices 46, 48 and the fifth station 88 can have comparable outlet points 24, 26, as already shown for the first station 22 and the second station 26, respectively.

[0026] In particular, the fifth station 88 consists of a cooler with a downstream condensate separator. Here, the gas coming from the regeneration is cooled, and the resulting condensate is separated. It then flows to the jet pumps 16, 18 on the outlet side due to the pressure gradient generated by the jet pumps 16, 18. After entering, it is reunited with the main flow via the respective suction port 34. During operation of the device, the main flow flows from the inlet 30 to the outlet 32 ​​of each jet pump 16, 18. A valve 92, 94 is connected to the corresponding outlet-side fluid path 90 between the fifth station 88 and the two suction ports 34.

[0027] All valves 36, 42, 44, 52, 54, 60, 62, 66, 68 as well as 92 and 94 belong to a valve device designated as a whole by 96, which can be controlled centrally by an electronic control device 98, which is connected in the usual way to actuating magnets of these valves via a cable connection 100 in order to control the individual valves.

[0028] The alternating drying and regeneration operation is now explained in more detail using an example. For drying operation, initially with the dryer device 46, valve 42 is opened and valve 44 remains closed. Furthermore, valves 52 and 66 are closed, with valve 60 open and valve 62 closed. In this way, fluid then reaches the inlet side of the dryer device 46 via the respective outlet 32 ​​of the two jet pumps 16, 18 and, after passing through the latter, via valve 60 to the third station 70. The thus very dry hydrogen gas, with a dew point of approximately -70°C, is then discharged via outlet 12 for further use, and a portion reaches the fourth station 78 in the form of the heating device via branch 74 and fluid path 76.When the valve 68 in the further intermediate line 64 is open, the highly heated gas then flows via the discharge line 80 and the connection point 82, as well as via a portion of the right-hand fluid path 58, to a pressure inlet side of the second dryer device 48, through which it flows from top to bottom as viewed in the figure, thereby regenerating. For further treatment of the regeneration stream discharged by the second dryer device 48, the valve 54 is opened, and the regeneration stream flows via the connection point 86 and the supply line 84 to the fifth station 88. After treatment by the fifth station 88, with the valves 92 and 94 open, the regeneration stream, as already described, flows via the respective suction connection 34 of the two jet pumps 16, 18 into the respective main stream from inlet 30 to outlet 32, and then recirculates, as already described, to the first dryer device 46.Valves 52 and 66 are closed during regeneration. As soon as the maximum loading condition for the dryer device 46 is reached, the previously regenerated dryer device 48 is activated for drying the gas stream by switching the aforementioned valves via the control device 98, and the dryer device 46 previously used for drying enters regeneration mode.

[0029] For drying by means of the dryer device 48, valves 44 and 62 are now open, while valves 42, 54, 60, and 68 are closed. For regeneration of the dryer device 46, however, valves 66, 52, 92, and 94 are open, and valves 54 and 68, as well as valves 42 and 60, are closed. Essentially, the two jet pumps 16, 18 form a type of pump cascade. As the gas flows through the two jet pumps 16, 18, a vacuum is created at the lateral inlet or suction port 34. This vacuum creates a pressure gradient within the jet pump cascade and is used to divert a partial flow of the gas to regenerate one of the two dryer devices 46, 48.In addition to the two jet pumps 16, 18 shown, more jet pumps (not shown) can also be used. These can be switched on and off using the controllable valve device 96 to always keep the volume flow required for regeneration at a required minimum value. This allows the regeneration flow to be adapted to the variable volume flow prevailing at the system inlet. The effectiveness of the dryer load and its regeneration is thus optimized.

[0030] In any case, the gas stream coming from the second station 26 is combined with the regeneration gas from the fifth station 88 via the two jet pumps 16, 18 and flows into the treatment device 14, as described. Overall, this creates a closed process, so that no gas losses can occur. Unlike feed pumps and compressors, including compressors, the two jet pumps 16, 18 have pressure-resistant housings, so there are essentially no limitations on their use at high pressures and temperatures.

[0031] In particular, automatic pressure control is achieved by means of the respective jet pumps 16, 18, so that independent pressure control is not required. In addition to high operating dynamics due to the free selection of possible jet pump combinations, very high gas purities are achieved at outlet 12, and no additional contamination occurs at outlet 12 due to the operation of the treatment device 14. Overall, the device according to the invention, together with the associated operating method, achieves precise dimensioning within the framework of the Venturi effect for the respective jet pumps 16, 18, so that the effectiveness of drying the gas, here in the form of hydrogen, is guaranteed at every operating point.

[0032] The above-mentioned device and method can also be used to separate and purify other gases; under certain circumstances, it may also be used in the treatment of liquids.

Claims

Patent claims 1 . Device for treating fluid, in particular for drying hydrogen gas, with an inlet (10) for the inflow of the fluid to be treated and with an outlet (12) for the outflow of the treated fluid and a treatment device (14) arranged between the inlet (10) and the outlet (12), characterized in that at least one jet pump (16, 18) is used for at least part of the transport of fluid through at least part of the treatment device (14).

2. Device according to claim 1, characterized in that - an inlet (30) of the respective jet pump (16, 18) to one part of the treatment device (14), an outlet (32) to another part of the treatment device (14), and - a suction connection (34) of the respective jet pump (16, 18) is connected to the further part of the treatment device (14).

3. Device according to claim 1 or 2, characterized in that with one part of the treatment device (14) a pretreatment of the fluid can be carried out, such as the removal of at least one gaseous component from the fluid by means of catalysis in a first station (22) and / or the separation of further components from the fluid, such as water, by means of condensation in a second station (26).

4. Device according to one of the preceding claims, characterized in that the further part of the treatment device (14) has at least two drying devices (46, 48) which are connected by means of a valve device (96) with a plurality of individual valves (36, 42, 44, 52, 54, 60, 62, 66, 68, 92 and 94) can be controlled in such a way that a part of the fluid, starting from the respective jet pump (16, 18), flows through at least one dryer device (46, 48) in the direction of the outlet (12), whereas at least one further dryer device (48, 46) can be regenerated, starting from this outlet (12) in the direction of the suction connection (34) of a jet pump (16, 18), preferably in countercurrent.

5. Device according to one of the preceding claims, characterized in that a particle cleaning device is connected as a third station (70) in a fluid path (56, 58) between the respective drying device (46, 48) and the outlet (12).

6. Device according to one of the preceding claims, characterized in that, viewed in the direction of fluid flow, after the third station (70) a further fluid path (76) opens into a branch (74) before the outlet (12), into which a heating device is connected as the fourth station (78), which passes heated fluid for the regeneration of at least one of the drying devices (46, 48) to the latter.

7. Device according to one of the preceding claims, characterized in that the respective drying device (46, 48) is connected on the output side to a fifth station (88) during the regeneration, which station serves for the condensation drying of the fluid produced during the regeneration of the respective drying device (46, 48).

8. Device according to one of the preceding claims, characterized in that, viewed in the fluid flow direction, the outlet of the fifth station (88) is connected to the suction connection (34) of the respective jet pump (16, 18).

9. Device according to one of the preceding claims, characterized in that at least two jet pumps (16, 18), preferably of the same flow rate, are connected jointly on the inlet side to the outlet of the second station (26) and can be connected alternately on the outlet side to one of the drying devices (46, 48).

10. A method for operating a device according to one of the preceding claims, characterized in that, using at least one jet pump (16, 18), hydrogen gas can be passed on to at least one dryer device (46, 48) for the purpose of carrying out a drying process for this gas, and that at the same time, in countercurrent, at least one further dryer device (48, 46) is flowed through by purified and heated gas, which, after passing through a condensation drying (88), is supplied via the suction connection (34) of the respectively assignable jet pump (16, 18) to the Inlet side of a drying device (46, 48) for hydrogen gas drying.

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