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    • 专利摘要:
    The invention relates to a process for the separation and compression of hydrogen from H2-containing gas mixtures using membrane separation processes, which is characterized in that a) the H2-containing gas mixture (f1) first in a conventional manner at least one membrane separation step using at least one H2-selective polymer membrane (Mem_1, Mem_2) is subjected, wherein at least one H2-enriched permeate (p1, p2) is obtained; b) the resulting permeate (p1, p2) is then moistened to a defined degree of moisture; c) the humidified gas mixture (fel) is then subjected to a separation step by means of a proton-transporting electrochemical membrane (Mem_el) with simultaneous pressure increase to obtain a substantially only H2 and H20 comprising permeate (pel); and d) subjecting said permeate (pel) to at least one drying step selected from condensation (Kond 1) and membrane drying (Mem_3) to obtain a substantially pure hydrogen gas stream (prod).
    公开号:AT521106A1
    申请号:T74/2018
    申请日:2018-03-20
    公开日:2019-10-15
    发明作者:Ing Werner Liemberger Dipl；Ing Dr Michael Harasek Dipl；Ing Dr Martin Mittner Dipl
    申请人:Univ Wien Tech；
    IPC主号:
    专利说明:

    The present invention relates to a method for separating and compressing hydrogen from gas mixtures.
    STATE OF THE ART
    The generation of hydrogen from H2-containing gas mixtures is essential in numerous areas of technology. The extraction of pure hydrogen from a natural gas network is a promising approach for the future of environmentally friendly (er) mobility using vehicles powered by hydrogen combustion engines or fuel cells. For this purpose, it is necessary to make the hydrogen as pure and inexpensive as possible, i.e. energy efficient, mainly methane, but also other gases contained in the natural gas network, e.g. to separate lower hydrocarbons (especially from ethane to butane), N2 and CO2.
    On a large industrial scale, hydrogen is primarily produced from natural gas and water vapor via steam reforming. The hydrogen must then be separated from the hydrogen-containing gas produced. Numerous processes are known for this and most of them have been in use for many years. On an industrial scale, this is achieved via pressure swing adsorption (PSA) or cryogenic separation. Pressure swing adsorption is a complex process in terms of equipment, since several cyclically working adsorbers (containers) including many valves are necessary, which is associated with high investment costs. Nevertheless, it is a standard procedure for the provision of high-purity gases. In the cryogenic separation, the gas mixture is partially liquefied and then separated. However, lowering the temperature is very energy and cost intensive.
    In addition to the two separation processes, membrane separation technology using hydrogen-selective membranes is becoming increasingly established, especially for smaller plants due to its high flexibility, good scalability, energy efficiency and simplicity (low expenditure on equipment and control technology). In Liemberger et al., Chem. Eng. Trans. 52, 427-432 (2016), the working group of the present inventors discloses a combination of membrane separation and PSA for the separation of hydrogen from natural gas.
    -1 2/23 • · · · · ··· · • · · · · ··· · · ··· • · · · · ····· · • · · · · Λ · · »· ·· ··· ··· · ···
    In the first step, a partial flow with increased hydrogen concentration is removed from the natural gas network using membrane separation technology. In the course of the subsequent pressure swing adsorption, the required high hydrogen product gas quality is ensured. The remaining gas is compressed to line pressure and fed back into the natural gas network. In Liemberger et al., J. Clean. Prod. 167, 896-907 (2017), the technical feasibility of the technology is shown experimentally.
    More recently, processes using electrochemical proton exchange membranes (PEM) have been described in which the hydrogen is oxidized to protons as it enters the membrane and reduced to molecular hydrogen as it exits. In this context, for example, Friebe et al., Angew. Chem. Int. Ed. Engl. 54 (27), 7790-7794 (2015), an inverted fuel cell by means of which hydrogen can be separated from an exhaust gas mixture in a commercially available PEM fuel cell by applying an electrical voltage, while WO 2014/207388 A1 is a multi-stage electrochemical compressor disclosed.
    A disadvantage of this combination of membrane separation and pressure swing adsorption is the high expenditure on equipment and the associated high investment costs, which are primarily due to the pressure swing adsorption. Another disadvantage is the number of compressors required and their energy consumption.
    Against this background, the aim of the invention was to provide an improved process for obtaining pure hydrogen, by means of which hydrogen in high purity of> 99.97% (which is referred to herein as essentially pure) is obtained with the lowest possible energy expenditure.
    DISCLOSURE OF THE INVENTION
    This object is achieved by the present invention by providing a process for the separation and compression of hydrogen from H2-containing gas mixtures using membrane separation processes, which is characterized in that
    -23 / 23 • ·
    a) the H2-containing gas mixture is first subjected in a manner known per se to at least one membrane separation step using at least one HC-selective polymer membrane (wherein at least one permeate enriched in H2 is obtained;
    b) the permeate thus obtained is then moistened to a defined degree of moisture;
    c) the moistened gas mixture is then subjected to a separation step by means of a proton-transporting electrochemical membrane with simultaneous pressure increase in order to obtain a permeate which essentially comprises only H2 and H2O; and
    d) this permeate is subjected to at least one drying step, selected from condensation and membrane drying, in order to obtain a gas stream comprising essentially pure hydrogen.
    Through this previously unknown combination of two different membrane separation steps, i.e. gas membranes and electrochemical membranes, with additional humidification and final drying, it is surprisingly possible to produce hydrogen in an extremely high purity of practically 100%, namely> 99.99% by volume, from a hydrogen containing only 4% by volume Natural gas flow, e.g. from a natural gas network.
    As the later examples demonstrate by means of preferred embodiments, an Hk product stream can be obtained according to this method, in which only the slightest traces of H2O and no CPU are contained. At the same time, a methane stream with a purity of up to 99.9% is obtained, which can be fed back into the natural gas network without any problems.
    In such preferred embodiments of the invention, the HC-containing gas mixture in step a) is subjected at least in part, but preferably in whole, to two membrane separation steps using two Pk-selective polymer membranes, at least part of the permeate of the first membrane, preferably the entire permeate , is fed as feed to a second membrane and the permeate
    -34 / 23 • * • · · · the second separation step is fed to the humidification step. In this way, the proportion of hydrogen in the retentate (the second membrane separation stage), i.e. in the off-stream, which in practice can be returned to the natural gas network. In the examples, a residual amount of H2 in the methane of only 5 ppm was achieved.
    Furthermore, in preferred embodiments, the permeate of the electrochemical membrane separation step c) is subjected to drying by means of a condenser and also by means of a third, HhO-selective membrane, in order to achieve the extremely low HbO content mentioned above. All conventional condensation dryers can be used as condensers, but preferably tube bundle or plate heat exchangers with suitable condensate discharge are used.
    According to the present invention, the currently customary, commercially available, highly selective aromatic polyimide membranes are generally used as hh-selective polymer membranes in step a), but ceramic membranes could possibly also serve this purpose in the future, provided that it succeeds in the next few years to eliminate known mechanical stability problems in order to make them suitable for continuous operation.
    In step c), the proton-transporting electrochemical membrane used is preferably a Nafion membrane, more preferably with a noble metal catalyst, in particular a platinum catalyst, as is known in principle in order to achieve high throughputs through the electrochemical membrane.
    In step d), commercially available HbO-selective membranes can also be used in the membrane drying stage, preferably also in this case aromatic polyimide membranes which are commercially available with high selectivities.
    Taken together, this means that no novel membranes are required for the practice of the present invention, but in all steps
    -45 / 23 • · • ···: j ι: ···.
    • · »· · • · ······ commercially available products can be used. All the more surprising were the concrete results disclosed in the examples herein.
    According to natural gas network regulations, natural gas may only have a very low residual moisture. If water vapor is present in the natural gas network, this is enriched together with the hydrogen in the first membrane separation step, but the moisture level required for the electrochemical membrane is not reached. Therefore, in step b) of the process according to the invention, the gas mixture is preferably humidified to a degree of moisture which corresponds to at least 40%, more preferably at least 50%, in particular at least 60% and not more than 99%, of the relative humidity at the respective temperature of the gas mixture . This ensures undisturbed operation of the proton-transporting electrochemical membrane even at high throughputs.
    The type of humidification is not particularly restricted and can be done, for example, by injecting water vapor or by means of a separate humidification membrane.
    To ensure stable and safe operation of the electrochemical membrane, water management plays a crucial role, since i) the transport process through the membrane does not work as desired if the relative humidity is too low and ii) the risk of flooding the relative humidity Membrane exists. This increases the specific energy consumption related to the product hydrogen.
    It is further preferred according to the present invention that the water separated in the drying step d) is recycled to the moistening step b), which minimizes the water consumption and ideally lowers it to zero.
    -56 / 23 • ·
    BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 schematically shows a simplified method of carrying out the present invention. 2 shows schematically somewhat more complex procedures according to preferred embodiments of the present invention, in which the drying step d) was carried out by a combination of a condenser and a drying membrane. Several such embodiments were computer simulated and calculated in the following examples.
    EXAMPLES
    The present invention is described below in detail by means of concrete examples. This is a computer simulation of the process sequence selected in the respective example under the following general conditions:
    Output feed f1: natural gas flow from 96 vol.% Methane and 4 vol.% Hydrogen with a pressure of 51 bar and a temperature of 300 K; 0.725 m 3 / h or 725 m 3 / h.
    General overview
    In Examples 1 to 3 it was assumed that a hydrogen-enriched permeate stream p1 is separated from a very weak volume flow (0.73 m 3 / h; see Table 4) of an H2-containing natural gas feed f1 in a first membrane separation stage Mem_1. The rest of the gas, retentate r1, is kept at the line pressure level and combined with the (retentate) stream r2 resulting from the process and consisting of almost pure methane, before it is returned to the natural gas network. It must therefore be ensured that the total humidity of this combined current to be recycled, the current off, corresponds to the criteria of the grid regulation before the feed back, for which purpose the dryer_2 shown in FIG. 1 is provided.
    The permeate p1 from Mem_1 is either fed as an input stream b1 to a mixer Mix_1, where it is partially saturated with a defined amount of water vapor
    -67 / 23 ··· · (Fig. 1), or p1 is at least partially fed as a sweep gas flow s2 to a second membrane separation stage Mem_2. The permeate p2 formed there is then - together with the rest of p1 or instead of p1 - fed to the mixer Mix_1 for moistening (FIG. 2).
    The humidified gas is then fed as feed to the electrochemical membrane separation stage Mem_el. In this separation stage, the majority of the hydrogen, including some of the moisture, is separated off as permeate pel and, depending on the design, compressed at the same time. The remaining gas leaves the electrochemical membrane Mem_el as retentate rel with the same pressure level.
    In order to achieve the necessary product gas qualities, the permeate pel must be dried, for which purpose dryer_1 (FIG. 1) or condenser Kond_2 (FIG. 2) is provided. The separated water can then be returned and returned to the process as water stream w3.
    The retentate rel of the electrochemical membrane separation stage must be compressed to the natural gas line pressure level, for which purpose the compressor Komp_1 is provided in all embodiments. It may also need to be dried before it can be fed back into the natural gas network. For this purpose, dryer_2 is provided in FIG. 1 and condenser_1 in FIG. 2. The water generated here can also be reused in the process as water flow w2. Both recirculated water streams w2 and w3 can be combined and fed to a flow divider Spilt_1, from where they are either removed from the process (wout) or mixed as water recyclate stream wr in a mixer Mix_2, if necessary with water win fed in from outside, but in any case as stream w1 to the humidifier (Fig. 1) or mixer Mix_1 (Fig. 2) can be supplied.
    Moisture management plays a crucial role in the process. It is therefore envisaged that initially or additional water can be introduced from outside (water inlet flow win) or excess water can be drawn off
    -78 / 23 ···· · can (water output current wout). This means that you can react flexibly to moisture requirements.
    In addition to the simplest process control from FIG. 1 with only one gas membrane separation stage Mem_1, an alternative with two additional gas membrane separations (Mem_2 and Mem_3) is indicated in FIG. 2 as a preferred embodiment of the invention. In both separation stages, the focus is on moisture recovery. However, in the event that not all of the hydrogen has been separated off by the electrochemical membrane Mem_el, at least some of the hydrogen contained in its retentate rel can be separated off by means of Mem_2 and returned to the process. This increases the overall process yield of hydrogen. To further optimize the yield, optional sweep gas flows s2, s3 are provided for Mem_2 and Mem_3. As can be seen from FIG. 2, a part of the product gas retentate stream r3 from Mem_3 can be fed back to the membrane Mem_3 as sweep stream s3.
    example 1
    This — like examples 2 to 6 — shown schematically in FIG. 2 is based on the assumption that the permeate p1 from the first membrane stage Mem 1 is fed entirely as sweep stream s2 to a second membrane separation stage Mem_2 before the second permeate obtained in the process p2 is moistened in mixer Mix_1.
    The water vapor mixed with permeate p1 in Mix_1 is only added initially from the outside. During operation, however, a large part of the water required is recycled from condenser Kond_2 and possibly from condenser Kond_1. This reuse of the auxiliary moisture greatly reduces the fresh water requirement of the process.
    The gas mixture moistened in Mix_1 and enriched in H2 is subsequently fed as feed to the electrochemical membrane Mem_el, where the hydrogen oxidizes H2 to protons H + , is passed through the membrane in proton form and, when it emerges from the membrane, is reduced again to H2 as permeate becomes.
    -89 / 23 • · · · · ·
    This permeate is first fed to a condenser Kond_2, in which a first drying takes place by condensation of the water vapor contained in the H2 stream. The resulting water is obtained as stream w3, which is either fed to a splitter_1 as a recycled stream wr to another mixer Mix_2, where it is either mixed with an external water feed win or directly as stream w1 without external water feed Mixer Mix_1 can be initiated to further reduce the need for fresh water or, if necessary, can also be discarded at Split_1 as a current wout. Both in the present example 1 and in the following example 2 it was assumed that - apart from an initial feed of fresh water - the water requirement in the process can be covered entirely by recycling the two condensate streams w3 and w2.
    In this preferred embodiment of the invention, the already almost pure Fh gas stream f3 dried in the condenser Kond_2 is subjected to a further gas membrane separation using an FhO-selective membrane Mem_3, the practically 100% pure hydrogen being obtained here as retentate r3 and as Product gas stream prod can be obtained. In the event that the moisture in the retentate r3 is too high, the separation efficiency of the membrane separation stage Mem_3 can be increased by separating a partial stream of the product as a sweep gas stream s3. The separated gas mixture of hydrogen and small amounts of water vapor is fed back into the process. In the present example 1, this optimization measure was taken, as can be seen from the values in table 1.
    Furthermore, in preferred embodiments of the invention, the retentate rel of the electrochemical membrane separation stage can be fed to a compressor Komp_1 and subsequently as a compressed stream c1 to a condenser Kond_1, where it is dried and introduced as feed f2 into the second membrane separation stage Mem_2 in order to reduce the overall process yield at H2 to increase. The water accumulating in the condenser Kond_1 is also supplied as current w2 to the current divider Split__1 and possibly recycled. This was taken into account in the present example 1 as well
    -910 / 23 also a recycling of the permeate p3 of the third gas membrane separation stage Mem_3 to Mix_1 in order to subject it again to the electrochemical separation at Mem_el.
    From the results of this embodiment of the invention listed in Table 1 - with a permeate from Mem_1 completely separated again in Mem_2 - it can be seen that with this procedure a large part of the hydrogen contained in f1, namely around 71%, is obtained by the calculation ( nH2 in stream f1 / πη2 in stream prod) x 100, can be continuously separated and recovered.
    Table 1 - Accounting data for example 1
    H2 1 ch 4 h 2 o TOTAL n X n X n X n X mol / s mol / s mol / s mol / s electricity fl 3.60E-04 4.00E-02 8,64E-03 9.60E-01 6.93E-07 7.70E-05 9.00E-03 1 win 1.50E-06 1, 00E + 00 1.50E-06 1 prod 2.54E-04 1, 00E + 00 2,34E-09 9.21E-06 2.54E-04 1 off l, 06E-04 l, 22E-02 8,64E-03 9.88E-01 4.52 E-08 5.17E-06 8,75E-03 1 rl 1, 04E-04 l, 22E-02 8.42 E-03 9.88E-01 3.93E-08 4,61E-06 8.52E-03 1 Pl 2.56E-04 5.37E-01 2.20E-04 4,62E-01 6.54E-07 1.37E-03 4.77E-04 1 s2 2.56E-04 5.37E-01 2.20E-04 4.62 E-01 6.54E-07 1.37E-03 4.77E-04 1 bl wl l, 08E-05 1, 00E + 00 l, 08E-05 1 fei 3.93E-04 6.29E-01 2.20E-04 3.52E-01 l, 16E-05 j 1.85E-02 6.25E-04 1 pel 2,95E-04 1, 00E + 00 l, 23E-07 4.18 E-04 2,95E-04 1 rel 9.84E-05 2.98E-01 2.20E-04 6.67E-01 l, 14E-05 3.47 E-02 3.30E-04 1 f3 2,95E-04 1, 00E + 00 4,53E-08 i, 54E-04 2.95 E-04 1 w3 7.81E-08 1, 00E + 00 7.81E-08 1 r3 2.54E-04 1, 00E + 00 2,34E-09 9.21E-06 2.54E-04 1 s3 2.54E-08 1, 00E + 00 2.34E-13 9.21E-06 2.54E-08 1 P3 4.14E-05 9.97E-01 l, 21E-07 2.92E-03 4.15E-05 1 wr 9,32E-06 1, 00E + 00 9,32E-06 1 cl 9.84E-05 2.98E-01 2.20E-04 6.67E-01 l, 14E-05 3.47E-02 3.30E-04 1 w2 l, 08E-05 1, 00E + 00 l, 08E-05 1 f2 9.84E-05 3.09E-01 2.20E-04 6.91E-01 5,07E-08 l, 59E-04 3.19 E-04 1 r2 2,34E-06 1.05E-02 2.20E-04 9.89E-01 5.98E-09 2.69E-05 2.22E-04 1 P2 3,52E-04 6.15E-01 2.20E-04 3.84E-01 6.99 E-07 l, 22E-03 5.73E-04 1 wout 2,15E-06 1, 00E + 00 2,15E-06 1
    -1011 / 23 ···· ·
    • · • ·· · · ·
    Water requirements -6.47 E-07 mol / s Circulating water l, 09E-05 mol / s Circulating water based on feed 0.12 % Circulating water based on product 4.30 % Relative humidity in fei 52.06 % Relative humidity in pel 60.00 % Relative humidity in rel 97.58 % H2 yield of the electrochemical membrane 75 % H2 overall yield 70.47 % Specific energy consumption 0.72 kWh / m
    Example 2
    In contrast to Example 1, a larger membrane area was assumed for the first gas membrane separation stage Mem_1 and a smaller area for the second stage Mem_2 (see Table 4 below) - with the same procedure. By increasing the area of Mem_1, it is possible to extract even more hydrogen from the natural gas network, which is then purified, which significantly increases the overall yield, namely to around 93%. However, since more methane is also transported through the first membrane separation stage Mem_1, it has to be compressed again, which increases the total energy consumption. In addition, a larger amount of circulating water is required. The rest of the process was identical to Example 1 and can also be seen in FIG. 2.
    -11 12/23 ·· ···· ··· ·
    Table 2 - Accounting data for example 2
    H 2 ch 4 HzO TOTAL n X n X n X n X mol / s mol / s mol / s mol / s electricity fl 3.60E-04 4.00E-02 8,64E-03 9.60E-01 6.93E-07 7.70E-05 9.00E-03 1 win 3.00E-06 1, 00E + 00 3.00E-06 1 prod 3.34E-04 1, OOE + OO 8.06E-09 2,41E-05 3.34E-04 1 off 2.59E-05 2.99E-03 8,64E-03 9.97E-01 8.56E-09 9.88E-07 8.67E-03 1 rl 2.20E-05 2.69E-03 8.15E-03 9.97E-01 4.49E-10 5.49E-08 8.17E-03 1 pl 3.38E-04 4.07 E-01 4.92 E-04 5.92E-01 6.93E-07 8.34E-04 8.31E-04 1 s2 3.38E-04 4.07E-01 4.92 E-04 5.92 E-01 6.93 E-07 8.34E-04 8.31E-04 1 bl wl 1.86E-05l, 94E-05 1, 00E + 00 1.86E-05 1 fei 5.01E-04 4,95E-01 4.92 E-04 4.86E-01 1.92 E-02 l, 01E-03 1 pel 3,75E-04 1, 00E + 00 l, 57E-07 4.18 E-04 3.76E-04 1 rel l, 25E-04 l, 97E-01 4.92 E-04 7.73E-01 1.93 E-05 3.03 E-02 6.37E-04 1 f3 3,75E-04 1, 00E + 00 5.77 E-08 l, 54E-04 3.76E-04 1 w3 9.94E-08 1, 00E + 00 9.94E-08 1 r3 3.34E-04 1, 00E + 00 8.06E-09 2,41E-05 3.34E-04 1 s3 3.34E-08 1, 00E + 00 8.06E-13 2,41E-05 3.34E-08 1 P3 4.14E-05 9.96E-01 1.49 E-07 3,59E-03 4.15 E-05 1 wr l, 56E-05 1, 00E + 00 l, 56E-05 1 cl l, 25E-04 l, 97E-01 4.92 E-04 7.73E-01 l, 93E-05 3.03E-02 6.37E-04 1 w2 1.86E-05 1, 00E + 00 1.86E-05 1 f2 l, 25E-04 2.03E-01 4.92E-04 7.97E-01 9.77E-08 l, 58E-04 6.17E-04 1 r2 3.96E-06 7.98E-03 4.92E-04 9.92 E-01 8.11E-O9 l, 64E-05 4.96E-04 1 P2 4.59 E-04 4.82 E-01 4.92 E-04 5.17E-01 7.83E-07 8.22 E-04 9.52E-04 1 wout 3,68E-06 1, 00E + 00 3,68E-06 1
    Water requirements -6.78E-07 mol / s Circulating water 1.87 E-05 mol / s Circulating water based on feed 0.21 % Circulating water based on product 5.61 % Relative humidity in fei 53.98 % Relative humidity in pel 60.00 % Relative humidity in rel 85.14 % H 2 yield of the electrochemical membrane 75 % H2 overall yield 92.80 % Specific energy consumption 0.87 kWh / m
    -1213 / 23 · «·· ·· ·· ······ · · · • · · · ··· · ♦ ··· * · · * · ··· ·· · ·· ·· ··· * ·· · ···
    Example 3
    In contrast to the two previous examples, the membrane area of the first gas separation membrane Mem_1 was increased further and thus to the greatest value in Examples 1 to 3 (see Table 4). The membrane area of the second membrane Mem_2 was also increased significantly compared to Example 1. The larger areas make the separation less selective, but in favor of the yield of H2, which has a positive effect on the overall yield, which is increased to around 96%. Of course, the overall energy requirement continues to increase - primarily due to the lower selectivity of the first membrane separation stage Mem_1. As in Example 2, the amount of circulating water also increases. However, the rest of the procedure was identical to Examples 1 and 2 and can also be seen in FIG. 2.
    Table 3 - Accounting data for example 3
    H 2 ch 4 HzO TOTAL n X n X n X n X mol / s mol / s mol / s mol / s electricity fl 3.60E-04 4, O0E-O2 8,64E-03 9.60E-01 6.93 E-07 7.70E-05 9.00E-03 1 win 3.00E-06 1, 00E + 00 3.00E-06 1 prod 3.46E-04 1, 00E + 00 9.23E-09 2.67E-05 3.46E-04 1 off l, 44E-05 l, 66E-03 8,64E-03 9.98E-01 8.77E-09 l, 01E-06 8,65E-03 1 rl 9.96E-06 l, 24E-03 8.02 E-03 9.99E-01 4.01E-ll 4.99E-09 8.03 E-03 1 pl 3,50E-04 3.62E-01 6.16 E-04 6.37E-01 6.93 E-07 7.17 E-04 9.67E-04 1 s2 3,50E-04 3.62E-01 6.16E-04 6.37E-01 6.93E-07 7.17E-04 9.67E-04 1 bl wl 2,33E-05 1, 00E + 00 2.33 E-05 1 fei 5.16E-04 4,46E-01 6.16E-04 5.33E-01 2.42 E-05 2.09E-02 l, 16E-03 1 pel 3.87E-04 1, 00E + 00 1.62 E-07 4.18 E-04 3.87 E-04 11 rel l, 29E-04 l, 68E-01 6.16E-04 8.01E-01 2.40E-05 3.12E-02 7,69E-04 f3 3.87 E-04 1, 00E + 00 5,95E-08 l, 54E-04 3.87 E-04 11111 w3 1.02 E-07 1, 00E + 00 1.02 E-07 r3 3.46 E-04 1, 00E + 00 9.23E-09 2.67E-05 3.46E-04 s3 3.46E-08 1, 00E + 00 9.23E-13 2.67E-05 3.46E-084.15E-05 p3 4.14E-05 9.96E-01 l, 53E-07 3.67 E-03 wr 2.03E-05 1, 00E + 00 2.03 E-05 1
    -1314 / 23 ···· · ·· ·· • · · · • · · «• · · · • * · ·
    9 9
    99 9 9 999
    9999 · · · ·
    999 9 999
    cl l, 29E-04 l, 68E-01 6.16E-04 8.01E-01 2.40E-05 3.12E-02 7,69E-04 1 w2 2,33E-05 1, 00E + 00 2,33E-05 1 f2 l, 29E-04 l, 73E-01 6.16 E-04 8.27E-01 l, 18E-07 l, 58E-04 7.45 E-04 1 r2 4,40E-06 7.10E-03 6.16 E-04 9.93E-01 8.73E-09 l, 41E-05 6.20E-04 1 P2 4,75E-04 4,35E-01 6.16 E-04 5.64E-01 8.03 E-07 7.35E-04 1.09 E-03 1 wout 3,67E-06 1, 00E + 00 3,67E-06 1 Water requirements -6.72E-07 mol / s Circulating water 2,35E-05 mol / s Circulating water based on feed 0.26 % Circulating water based on product 6.80 % Relative humidity in fei 58.86 % Relative humidity in pel 60.00 % Relative humidity in rel 87.90 % H 2 yield of the electrochemical membrane 75 % H2 overall yield 96.01 % Specific energy consumption 0.96 kWh / m 3
    Table 4 - Membrane areas and volume flows of Examples 1 to 3
    example 1 Example 2 Example 3 Areas in m zA (Mem l) 0.036 0.08 0.1 A (Mem 2) 0.02125 0.017 0.17 A (Mem 3) 0.000085 0.000085 0.000085 Areas based on A (Mem 1) from Example 1 A (Mem l) 100.0% 222.2% 277.8% A (Mem 2) 59.0% 47.2% 472.2% A (Mem 3) 0.2% 0.2% 0.2% Area ratio A (Mem 2) / A (Mem l) 0.59 0.21 1.70 A (Mem 3) / A (Mem l) 0.0024 0.0011 0.0009 Standard volume flows in m 3 / h fl 0.73 0.73 0.73 pi 0.04 0.07 0.08 prod 0.02 0.03 0.03
    -1415 / 23 • · ·· ·· • · · · · · · · * ♦ · · • · · · ·· · · ···· · • ··· • · · · · ··· ···
    As can be seen from Table 4, as already mentioned, a very weak volume flow of only 0.73 m 3 / h was assumed as output feed f1, which would be sufficient for a small hydrogen filling station in a private household, for example.
    Table 5 below, on the other hand, shows the corresponding values for Examples 4 to 6 according to the invention, in which the output feed f1 is a volume flow of 725 m 3 / h, which is 1000 times stronger, and membrane areas for the membranes of the three gas membrane separation stages Mem_1, Mem_2, each 1000 times larger and Mem_3 were accepted. These embodiments of the invention are representative, for example, for a large-scale plant for hydrogen purification from a contaminated natural gas stream or for a public hydrogen filling station.
    Table 5 - Membrane areas and volume flows of Examples 4 to 6
    Example 4 Example 5 Example 6 Areas in m 2A (Mem l) 36.00 80.00 100.00 A (Mem 2) 21.25 17.00 170.00 A (Mem 3) 0.085 0.085 0.085 Areas based on A (Mem 1) from Example 4 A (Mem l) 100.0% 222.2% 277.8% A (Mem 2) 59.0% 47.2% 472.2% A (Mem 3) 0.2% 0.2% 0.2% Area ratio A (Mem 2) / A (Mem l) 0.59 0.21 1.70 A (M e m 3) / A (M e m l) 0.0024 0.0011 0.0009 Standard volume flows in m 3 / h fl 725.76 725.76 725.76 pi 38.45 67.00 77.96 prod 20.46 26.94 27.87
    For these examples 4 to 6, the amounts of substances in the respective streams and the water requirement in Tables 1 to 3 each increase by a factor of 1000, of course. The other, relative values such as the proportions of substance and before
    -1516 / 23 ·· ·· · ···· · ···· ······· · · • · · · · ··· · · ··· • ·· · · ·· «·· On the other hand, the respective volume-related energy requirements remain the same, so that in example 6, as before in analogous example 3, hydrogen with the highest Yield of over 96% can be separated - and this with an energy requirement which is only relatively slight compared to the examples with a smaller area of the first separation membrane Mem_1 (Examples 1 and 2 or Examples 4 and 5).
    In any case, the examples above show that depending on the process design, a different overall yield can be achieved with different energy consumption. The moisture that may be present in the natural gas network preferably permeates through the first membrane separation stage Mem_1. Since the water should ultimately only be present in traces in the product and offgas, it must be removed. This is reflected in the negative water requirement. However, a certain amount of circulating water is required for stable operation. The amount of this circulation quantity depends on the process design and the overall yield. From the examples it can be seen that more moisture is required to achieve a higher overall yield.
    The above computer simulated examples thus clearly demonstrate that by the method of the present invention a stream of practically pure hydrogen, i.e. > 99.9% pure H2, since the molar fraction x of H2 in the product stream is rounded to 1.00, can be branched off from an urban natural gas network, while at the same time methane with a purity of up to 99.9% can be fed back into the The grid can be fed in, as can be seen from the substance proportions x of CH4 in the current off of 0.988.0.997 and 0.998.
    Such a high separation efficiency and purity of the separated gas streams cannot be achieved according to the prior art.
    权利要求:
    Claims (12)
    [1]
    A process for the separation and compression of hydrogen from H2-containing gas mixtures using membrane separation processes, characterized in that
    a) the H2-containing gas mixture (f1) is first subjected in a manner known per se to at least one membrane separation step using at least one H2-selective polymer membrane (Mem_1, Mem_2) to obtain at least one H2-enriched permeate (p1, p2);
    b) the resulting permeate (p1, p2) is then moistened to a defined degree of humidity;
    c) the humidified gas mixture (fei) is then subjected to a separation step by means of a proton-transporting electrochemical membrane (Mem_el) with simultaneous pressure increase to obtain a substantially only H2 and H2O comprehensive permeate (pel); and
    d) subjecting said permeate (pel) to at least one drying step selected from condensation (Kond 1) and membrane drying (Mem_3) to obtain a substantially pure hydrogen gas stream (prod).
    [2]
    2. The method according to claim 1, characterized in that the H2-containing gas mixture (f1) in step a) at least partially subjected to two membrane separation steps using two H2-selective polymer membranes (Mem_1, Mem_2), wherein at least a portion of the permeate ( p1) is fed to the first membrane (Mem_1) as feed (s2) to a second membrane (Mem_2) and the permeate (p2) of the second separation step is fed to the moistening step.
    [3]
    3. The method according to claim 1 or 2, characterized in that the permeate (pel) of the electrochemical membrane separation step c) is subjected to both a drying by means of condenser (Kond_1) and by means of a third, H2O-selective membrane (Mem_3).
    -1818 / 23 *
    • ··········· ······ ····
    [4]
    4. The method according to any one of claims 1 to 3, characterized in that in step a) as Fk-selective polymer membranes (Mem_1, Mem_2) aromatic polyimide membranes are used.
    [5]
    5. The method according to any one of claims 1 to 4, characterized in that in step c) as a proton-transporting electrochemical membrane (Mem_el) a Nafion membrane is used.
    [6]
    6. The method according to any one of claims 1 to 5, characterized in that in step c) in the proton-transporting electrochemical membrane (Mem_el) a noble metal catalyst is used.
    [7]
    7. The method according to claim 6, characterized in that a platinum catalyst is used.
    [8]
    8. The method according to any one of claims 1 to 7, characterized in that in step b) the gas mixture is moistened to a degree of moisture which corresponds to at least 40% of the relative humidity at the respective temperature of the gas mixture.
    [9]
    9. The method according to claim 8, characterized in that the gas mixture to at least 50% r. F. is moistened.
    [10]
    10. The method according to claim 9, characterized in that the gas mixture to at least 60% r. F. is moistened.
    [11]
    11. The method according to claim 10, characterized in that the gas mixture to not more than 95% r. F. is moistened.
    [12]
    12. The method according to any one of claims 1 to 11, characterized in that in the drying step d) separated water for moistening step b) is recycled.
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    同族专利:
    公开号 | 公开日
    AT521106B1|2020-03-15|
    EP3953297A1|2022-02-16|
    WO2019180032A1|2019-09-26|
    引用文献:
    公开号 | 申请日 | 公开日 | 申请人 | 专利标题
    US7947117B2|2007-07-20|2011-05-24|IFP Energies Nouvelles|Hydrogen purification process that uses a combination of membrane separation units|
    DE102013220939A1|2013-10-16|2015-04-16|Robert Bosch Gmbh|Process for the distribution of hydrogen gas to an end user, extraction unit and device for the distribution of hydrogen gas|
    US20100243475A1|2009-03-27|2010-09-30|H2 Pump Llc|Electrochemical Hydrogen Reclamation System|
    DE102012015021A1|2012-02-10|2013-08-14|Alexander Emhart|Apparatus, useful for separating hydrogen from gas mixtures, comprises separating element, electron conducting material containing anode, electron conducting material containing cathode, and gas-tight, proton exchange membrane|
    US20140332405A1|2013-05-08|2014-11-13|Satish S. Tamhankar|Hydrogen production process with carbon dioxide recovery|WO2021198102A1|2020-03-30|2021-10-07|Basf Se|Method for electrochemical hydrogen separation from natural-gas pipelines|
    法律状态:
    优先权:
    申请号 | 申请日 | 专利标题
    ATA74/2018A|AT521106B1|2018-03-20|2018-03-20|Process for the separation and compression of hydrogen from gas mixtures|ATA74/2018A| AT521106B1|2018-03-20|2018-03-20|Process for the separation and compression of hydrogen from gas mixtures|
    EP19716081.5A| EP3953297A1|2018-03-20|2019-03-19|Method for separating hydrogen from gas mixtures|
    PCT/EP2019/056863| WO2019180032A1|2018-03-20|2019-03-19|Method for separating hydrogen from gas mixtures|
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