Method for compressing a water-containing, oxygen-containing stream
The method addresses safety and cost issues in compressing water-containing oxygen streams by using an ejector to flash and separate phases, enabling efficient and economical compression for use in gasifiers.
Patent Information
- Application Number
- JP2025530608
- Authority / Receiving Office
- JP · JP
- Patent Type
- Applications
- Current Assignee / Owner
- Priority Date
- 2022-11-24
- Filing Date
- 2023-11-21
- Publication Date
- 2025-11-14
AI Technical Summary
Existing methods for compressing water-containing, oxygen-containing streams from electrolytic cells face safety issues and require complex, costly equipment.
A method using an ejector to mix a water-containing, oxygen-containing stream with a driving fluid, flash the mixture, separate phases, and sequentially dehydrogenate and dehydrate the gas stream to achieve compression.
This approach allows for simple and cost-effective compression of oxygen-containing streams without safety hazards, using static equipment and lower capital costs.
Smart Images
Figure 2025537387000001_ABST
Abstract
Description
[Technical Field]
[0001] The present invention relates to a method for compressing a water-containing, oxygen-containing stream coming from an electrolytic cell, the compressed oxygen-containing stream obtained being used in particular in a gasifier. [Background technology]
[0002] Compression of gaseous streams is well known in the art. Typically, compression of gaseous streams is achieved by positive displacement devices such as reciprocating or screw compressors, which reduce the volume occupied by the gas and therefore increase its pressure. This type of "dry" compression can also be achieved by centrifugal blowers, compressors, or pumps, which use impellers to accelerate and then decelerate the gas, converting the kinetic energy of the gas into pressure. Typically, multiple compression stages and interstage cooling are required to achieve the desired pressure increase. Summary of the Invention
[0003] It is an object of the present invention to solve, minimize or at least reduce one or more of the above problems. A further object of the present invention is to provide an alternative process for compressing a water-containing, in particular a water-saturated oxygen-containing stream coming from an electrolytic cell, the resulting compressed oxygen-containing stream being used in particular in a gasifier.
[0004] One or more of the above objects or other objects may be achieved in accordance with the present invention by providing a method for compressing a water-containing, oxygen-containing stream originating from an electrolytic cell, the method comprising at least (a) providing a water-containing, oxygen-containing stream; (b) mixing the water-containing, oxygen-containing stream provided in step (a) as a suction fluid in an ejector with the water-containing stream as a driving fluid, thereby obtaining a mixed stream; (c) flashing the mixed stream through an ejector, thereby obtaining a two-phase fluid discharged from the ejector; (d) separating the two-phase fluid discharged from the ejector into an oxygen-containing gas stream and a liquid stream; (e) pressurizing the liquid stream obtained in step (d), thereby obtaining a pressurized liquid stream; (f) using the pressurized liquid stream obtained in step (e) as the driving fluid in step (b); (g) dehydrogenating the oxygen-containing gas stream obtained in step (d), thereby obtaining a dehydrogenated oxygen-containing stream; (h) dehydrating the dehydrogenated oxygen-containing stream obtained in step (g), thereby obtaining a dehydrated dehydrogenated oxygen-containing stream; (i) compressing the dehydrated and dehydrogenated oxygen-containing stream obtained in step (h), thereby obtaining a compressed oxygen-containing stream; (j) using the compressed oxygen-containing stream obtained in step (i), particularly in a gasifier.
[0005] Surprisingly, it has been found according to the present invention that by using a water-containing (preferably water-saturated) oxygen-containing stream originating from an electrolytic cell as suction fluid in an ejector, a pressurized oxygen-containing gas stream can be obtained in a surprisingly simple manner, without the safety problems that are encountered in "dry compression".
[0006] A further advantage of the process according to the invention is that a static piece of equipment can be used to achieve pressure transfer. Such static pieces of equipment are reliable, simple, and require less expensive materials of construction. Ejectors are considered static devices and are generally associated with lower capital and operating costs compared to compressors. Ejectors convert the pressure energy available in the driving fluid into velocity energy, introduce a suction fluid (at low pressure), mix the two fluids, and eject the mixture at an intermediate pressure without the use of rotating or moving parts.
[0007] In this regard, it is noted that ejectors have been known per se for several decades, but have not been proposed for use in compressing a water-containing, oxygen-containing stream coming from an electrolyzer, the compressed oxygen-containing stream being used as a product, for example, in a gasifier.
[0008] As a very recent example, WO 2022 / 069906(A1) discloses the use of an ejector, inter alia, for condensing CO2. WO 2022 / 069906(A1) proposes various fluids (i.e., water, methane, ethane, propane, ethylene, propylene, methanol, ethanol, acetone, nitrous oxide) to be used as the driving fluid and the gas to be compressed (see page 4, lines 8-11), but makes no mention of an oxygen-containing stream (typically also containing hydrogen) coming from an electrolyzer being used as the suction fluid in the ejector.
[0009] As a further example of the use of an ejector, Patent Publication No. 2003105577(A) discloses a fuel cell hybrid system that includes a gas generation section (using electrolysis of water) for producing hydrogen and oxygen, and a fuel cell section for generating electricity using the hydrogen and / or oxygen generated in the gas generation section within the fuel cell section.
[0010] Furthermore, WO 2020 / 035470 A1 discloses a gas power cycle for generating electricity using an ejector. WO 2020 / 035470 A1 does not mention that the water-containing, oxygen-containing stream originates from an electrolyzer.
[0011] In step (a) of the method according to the invention, a water-containing, oxygen-containing stream is provided. The water-containing, oxygen-containing stream provided in step (a) is not limited in any way (with respect to composition, temperature, pressure, etc.) so long as it contains oxygen (O) and water (HO) and originates from an electrolytic cell.
[0012] Typically, and preferably, the water-containing, oxygen-containing stream provided in step (a) is a gaseous stream, and preferably a water-saturated stream, and may even contain some liquid water carryover (up to 1.0% by volume).
[0013] Preferably, the water-containing, oxygen-containing stream provided in step (a) comprises at least 80 mol% O, preferably at least 90 mol% O, more preferably at least 95 mol% O. Preferably, the water-containing, oxygen-containing stream provided in step (a) comprises at most 99 mol% O, more preferably at most 98 mol% O.
[0014] Furthermore, it is preferred that the water-containing, oxygen-containing stream provided in step (a) contains 2.0 to 20 mol% H2O, preferably 3.0 mol% to 10.0 mol% H2O. The water-containing, oxygen-containing stream provided in step (a) typically also contains hydrogen (H2). Preferably, the water-containing, oxygen-containing stream provided in step (a) contains 0.3 to 2.0 mol% H2.
[0015] Preferably, the water-containing, oxygen-containing stream provided in step (a) has a pressure of from 0.1 bara to 2.5 bara, preferably from 0.5 bara to 1.5 bara. The pressure of the water-containing, oxygen-containing stream provided in step (a) may be referred to as the "first pressure."
[0016] Furthermore, it is preferred that the water-containing, oxygen-containing stream provided in step (a) has a temperature of 20 to 90°C, preferably 40 to 80°C. Where appropriate, the water-containing, oxygen-containing stream provided in step (a) may be pre-treated to obtain the desired composition and conditions.
[0017] In step (b) of the method according to the invention, the water-containing, oxygen-containing stream provided in step (a) is mixed in an ejector as a suction fluid with a water-containing stream as a driving fluid, thereby obtaining a mixed stream.
[0018] Ejectors are known in the art and will not be described in further detail herein. Ejectors are described, for example, in Perry's Chemical Engineers' Handbook, 6th Edition, 1985, pp. 5-21 to 5-22 and 6-31 to 6-33. Ejectors are considered static devices and are generally associated with lower capital and operating costs compared to compressors.
[0019] Preferably, the driving fluid in step (b) comprises at least 80 mol%, preferably at least 90 mol%, more preferably at least 95 mol% HO. Typically, the driving fluid in step (b) comprises up to 99 mol% HO. The driving fluid in step (b) may also contain some O and H. Typically, the driving fluid comprises less than 0.5 mol% O.
[0020] Those skilled in the art will readily appreciate that the pressure of the "drive fluid" is higher than the pressure of the "suction fluid" used in the ejector. Preferably, the pressure of the drive fluid is at least 10 bar higher than the suction fluid, preferably at least 20 bar higher, more preferably at least 50 bar higher, and even more preferably at least 80 bar higher.
[0021] Preferably, the driving fluid in step (b) has a pressure in the range of 60 to 300 bara, preferably 80 bara to 200 bara. Furthermore, the driving fluid in step (b) has a temperature of 20 to 70°C, preferably 30 to 50°C.
[0022] As already mentioned above, the suction fluid (the water-containing, oxygen-containing stream used as) has a pressure of 0.1 bara to 2.5 bara, preferably 0.5 bara to 1.5 bara. In step (c) of the method according to the invention, the mixed stream is flashed by an ejector, thereby obtaining a two-phase fluid that is discharged from the ejector. Typically, the flashing is performed in the throat of the ejector, thereby obtaining a two-phase fluid while leaving the ejector.
[0023] As a result of the flashing, the pressure of the mixed stream decreases. Preferably, the two-phase fluid obtained in step (c) has a pressure of 2.0 bara to 10.0 bara, preferably 3.0 bara to 6.0 bara. The pressure of the two-phase fluid obtained in step (c) may be referred to as the "second pressure." This second pressure is higher than the "first pressure" (of the water-containing, oxygen-containing stream provided in step (a)).
[0024] In step (d) of the method according to the invention, the two-phase fluid discharged from the ejector is separated into an oxygen-containing gas stream and a liquid stream. This separation in step (d) is not particularly limited and is typically carried out in a conventional gas-liquid separator.
[0025] The oxygen-containing gas stream obtained in step (d), which is at the increased second pressure, may be further processed (e.g., dehydrogenated, dehydrated, and further compressed) and used as a product, for example, in a gasifier.
[0026] In step (e) of the method according to the invention, the liquid stream obtained in step (d) is pressurized, thereby obtaining a pressurized liquid stream. Those skilled in the art will readily appreciate that this pressurization can be carried out in many ways, for example by using a pump, to obtain the desired pressure for use as a driving fluid.
[0027] In step (f) of the method according to the invention, the pressurized liquid stream obtained in step (e) is used as the driving fluid in step (b). In step (g) of the process according to the present invention, the oxygen-containing gas stream obtained in step (d) is dehydrogenated, thereby obtaining a dehydrogenated oxygen-containing stream. Those skilled in the art are familiar with dehydrogenation, and therefore, it will not be described in detail here. Dehydrogenation can be carried out, for example, by catalytic H2 / O2 combustion. When such catalytic H2 / O2 combustion is used, the reactor temperature is in the range of 70-150°C.
[0028] The dehydrogenated oxygen-containing stream preferably has an H2 content of less than 1 mole %, preferably less than 10 ppm, more preferably less than 5 ppm. In step (h) of the process according to the invention, the dehydrated oxygen-containing stream obtained in step (g) is dehydrated, thereby obtaining a dehydrated dehydrogenated oxygen-containing stream. Those skilled in the art are familiar with dehydration, so it will not be described in detail here. Typically, the dehydrated dehydrogenated oxygen-containing stream contains less than 10 ppm HO.
[0029] In step (i) of the process according to the invention, the dehydrated and dehydrogenated oxygen-containing stream obtained in step (h) is compressed to obtain a compressed oxygen-containing stream. Typically, the compressed oxygen-containing stream has a pressure in the range of 6 to 70 bara, preferably 30 to 60 bara.
[0030] In step (j) of the method according to the invention, the compressed oxygen-containing stream obtained in step (i) is used in a gasifier, among other things. Those skilled in the art are familiar with gasifiers, which will not be described in further detail here. Suitable gasifiers are disclosed, for example, in WO 2017 / 102942 A1. Typically, gasifiers form part of syngas and fossil-based hydrogen production lines, etc.
[0031] Those skilled in the art will readily understand that the method according to the invention may comprise further steps. As an example, some cooling may be performed on the liquid stream obtained in step (d) and / or the pressurized liquid stream obtained in step (e) to obtain the desired temperature or driving fluid used in step (b). Those skilled in the art are familiar with cooling, so this will not be described in detail here. Cooling may be performed, for example, by a heat exchanger, for example, using air or another medium.
[0032] In a further aspect, the present invention relates to an apparatus for compressing a water-containing stream, in particular a water-saturated oxygen-containing stream, originating from an electrolytic cell, comprising: an electrolytic cell for electrolyzing a water-containing stream, thereby obtaining at least a (water-containing, in particular water-saturated) H2-containing stream and a water-containing (in particular water-saturated) oxygen-containing stream; an ejector for mixing a water-containing, oxygen-containing stream as a suction fluid with a water-containing stream as a driving fluid, thereby obtaining a mixed stream, and flashing the mixed stream, thereby obtaining a two-phase fluid that is discharged from the ejector; a separator for separating the two-phase fluid discharged from the ejector into an oxygen-containing gas stream and a liquid stream; a pressure increaser, in particular a pump, for pressurizing the liquid flow and thereby obtaining a pressurized liquid flow; a recirculation line for recirculating at least a portion of the pressurized liquid flow used as a driving fluid in the ejector; a dehydrogenator for dehydrogenating the oxygen-containing gas stream, thereby obtaining a dehydrogenated oxygen-containing stream; a dehydrator for dehydrating the dehydrogenated oxygen-containing stream, thereby obtaining a dehydrated dehydrogenated oxygen-containing stream; at least one compressor for compressing the dehydrated dehydrogenated oxygen-containing stream, thereby obtaining a compressed oxygen-containing stream; a gasifier in which a compressed oxygen-containing stream is used.
[0033] There may also be a water bleed or make-up for the recirculation line (to remove or add water as needed). [Brief explanation of the drawings]
[0034] The invention will now be further illustrated by the following non-limiting figures, in which: [Figure 1] FIG. 1 is a schematic flow diagram of part of a process for compressing a water-saturated oxygen-containing stream originating from an electrolytic cell according to the present invention. [Figure 2] 2 is a schematic detail view of an exemplary, non-limiting embodiment of an ejector that can be used in the method according to the present invention; FIG. [Figure 3] 2 shows a schematic representation of an alternative embodiment of a part of the method according to the invention, further comprising a cooler downstream of the pump 4 of FIG. 1. [Figure 4] 2 shows a schematic representation of an alternative embodiment of the method according to the invention, further comprising a cooler upstream of the pump 4 of FIG. 1. FIG. [Figure 5] FIG. 4 shows a schematic diagram of an exemplary method according to the present invention (based on FIG. 3), also showing a dehydrogenator, a dehydrator, a compressor, and a gasifier.
[0035] For purposes of this description, the same reference numbers refer to the same or similar components. DETAILED DESCRIPTION OF THE INVENTION
[0036] The flow diagram in Figure 1 is generally referred to by the reference numeral 1 and shows an ejector 2, a gas-liquid separator 3, and a pump 4. Preferably, one of the inlets of the ejector 2 ("2b" in Figure 2) is connected to the outlet of an electrolyzer (not shown) for the water-saturated oxygen-containing stream 10 used in the ejector 2. Of course, there may be a g / l separator and / or a cooler between the outlet of the electrolyzer and the inlet of the ejector 2 (2b in Figure 2).
[0037] 1, a water-saturated oxygen-containing stream 10 is mixed as a suction fluid in ejector 2 with a water-containing stream 20 as a driving fluid, thereby obtaining a mixed stream. The mixed stream is flashed through ejector 2, thereby obtaining a two-phase fluid 30 that is discharged from ejector 2.
[0038] A more detailed diagram of (a non-limiting embodiment of) ejector 2 is shown in FIG. 2 and described below. In ejector 2, water-saturated oxygen-containing stream 10 is mixed with driving fluid 20 as a suction fluid, thereby obtaining a mixed stream (not shown in FIG. 1, "25" in FIG. 2). The mixed stream is flashed by ejector 2 while leaving ejector 2, thereby obtaining a two-phase fluid 30 that is discharged from ejector 2.
[0039] The two-phase fluid 30 discharged from the ejector 2 is separated into an oxygen-containing gas stream 40 and a liquid stream 50 in a conventional gas-liquid separator 3. A portion of the liquid stream 50 may be used as a bleed stream (not shown in FIG. 1; see stream 60 in FIG. 3).
[0040] The oxygen-containing gas 40 (which is at an increased pressure compared to the water-saturated oxygen-containing stream 10) may be sent for further compression and purification (e.g., dehydrogenation, dehydration, etc.) before end use, for example in a gasifier (see also FIG. 5 below).
[0041] The liquid stream 50 coming from the gas-liquid separator 3 is pressurized in a pump 4 , thereby obtaining a pressurized liquid stream which is used as the driving fluid 20 in the ejector 2 . FIG. 2 shows a more detailed view of an ejector that can be used as ejector 2 of FIG.
[0042] As can be seen in FIG. 2, the ejector 2 comprises an inlet 2a for the driving fluid 20, an inlet 2b for the suction fluid 10, a nozzle 2c within the ejector 2 for the driving fluid, a throat 2d having a diffuser section 2e, and an outlet 2f for the discharged fluid 30.
[0043] The driving fluid 20 and the suction fluid 10 are mixed in the ejector 2 (just after the nozzle 2c) to form a mixed flow 25. The mixed flow 25 is then flashed by (the throat 2d of) the ejector 2, thereby obtaining a two-phase fluid 30 that is discharged from (the outlet 2f of) the ejector 2.
[0044] Figures 3 and 4 show schematically alternative embodiments of the method according to the invention, in which a cooler 5 is used downstream (Figure 3) or upstream (Figure 4) of the pump 4 of Figure 1. Of course, the cooler may be present both downstream and upstream of the pump 4. In the embodiment of Figures 3 and 4, the cooler 5 is in the form of an indirect heat exchanger.
[0045] In the embodiment of Figure 3, cooler 5 cools the pressurized liquid stream (designated "45" in Figure 3) exiting pump 4. The cooled pressurized liquid stream coming from cooler 5 is then used as motive flow 20 in ejector 2. Additionally, Figure 3 shows the presence of a bleed flow 60.
[0046] In the embodiment of FIG. 4, cooler 5 cools the liquid stream 50 obtained in gas-liquid separator 3, which cooled liquid stream is then sent to pump 4 as stream "55". FIG. 5 provides a more complete overview of the flow diagram of the method according to the invention (based on the embodiment of FIG. 3), and also shows the dehydrogenator 6 , the dehydrator 7 , the compressor 8 and the gasifier 9 .
[0047] In use of the flow diagram of FIG. 5, oxygen-containing gas stream 40 is dehydrogenated in dehydrogenator 6, thereby providing dehydrogenated oxygen-containing stream 70. This dehydrogenated oxygen-containing stream 70 is subsequently dehydrated in a dehydrator 7, thereby obtaining a dehydrated dehydrogenated oxygen-containing stream 80, which is compressed in one or more compressors 8, thereby obtaining a compressed oxygen-containing stream 90.
[0048] The compressed oxygen-containing stream 90 may be used, inter alia, in the gasifier 9 . [Example]
[0049] Example 1 The flow diagram in Figure 3 was used to illustrate the compression of a gaseous, water-saturated, oxygen-containing stream originating from an electrolytic cell. The compositions and conditions of the fluid (i.e., gas and liquid) streams in the various flow lines are shown in Table 1 below.
[0050] In ejector 2, P吸引 is 1.1 bara, while P 排出 was 6.0 bara.
[0051] [Table 1]
[0052] Consideration As can be seen from Table 1, the process according to the invention allows an effective way to compress the water saturated oxygen-containing stream coming from the electrolytic cell.
[0053] A significant advantage of the present invention is that by using a water-saturated oxygen-containing stream as the suction fluid in the ejector, a pressurized oxygen-containing gas stream can be obtained in a surprisingly simple manner, without the safety issues encountered with "dry compression", which can then be used in the gasifier.
[0054] Those skilled in the art will readily appreciate that many modifications may be made without departing from the scope of the present invention. Furthermore, those skilled in the art will readily appreciate that, although the present invention has been described in some instances with reference to particular combinations of features and means, many of these features and means are functionally independent of other features and means provided in each embodiment and may be equally or similarly applied independently in other embodiments.
Claims
1. 1. A method for compressing a water-containing, oxygen-containing stream originating from an electrolytic cell, comprising at least (a) providing a water-containing, oxygen-containing stream (10) originating from an electrolytic cell; (b) mixing the water-containing, oxygen-containing stream (10) provided in step (a) as a suction fluid in an ejector (2) with a water-containing stream (20) as a driving fluid, thereby obtaining a mixed stream; (c) flashing the mixed flow through the ejector (2), thereby obtaining a two-phase fluid (30) discharged from the ejector (2); (d) separating the two-phase fluid (30) discharged from the ejector (2) into an oxygen-containing gas stream (40) and a liquid stream (50); (e) pressurizing the liquid stream (50) obtained in step (d), thereby obtaining a pressurized liquid stream; (f) using the pressurized liquid stream obtained in step (e) as the driving fluid (20) in step (b); (g) dehydrogenating said oxygen-containing gas stream (40) obtained in step (d), thereby obtaining a dehydrogenated oxygen-containing stream (70); (h) dehydrating the dehydrogenated oxygen-containing stream (70) obtained in step (g), thereby obtaining a dehydrated dehydrogenated oxygen-containing stream (80); (i) compressing the dehydrated and dehydrogenated oxygen-containing stream (80) obtained in step (h), thereby obtaining a compressed oxygen-containing stream (90); (j) using said compressed oxygen-containing stream (90) obtained in step (i), in particular in a gasifier (9).
2. The water-containing oxygen-containing stream (10) provided in step (a) is at least 80 mol % O ２ , preferably at least 90 mol % O ２ , more preferably at least 95 mol % O ２ The method of claim 1 , comprising:
3. The water-containing oxygen-containing stream (10) provided in step (a) contains 2.0 to 20 mole % H ２ O, preferably 3.0 mol % to 10.0 mol % H ２ The method of claim 1 or 2, comprising:
4. The water-containing oxygen-containing stream (10) provided in step (a) contains 0.3 to 2.0 mole % H ２ 3. The method of claim 1 or 2, comprising:
5. The method according to any one of claims 1 to 4, wherein the water-containing, oxygen-containing stream (10) provided in step (a) has a pressure of from 0.1 bara to 2.5 bara, preferably from 0.5 bara to 1.5 bara.
6. The process according to any one of the preceding claims, wherein the water-containing, oxygen-containing stream (10) provided in step (a) has a temperature of from 20 to 90°C, preferably from 40 to 80°C.
7. The driving fluid (20) in step (b) is at least 80 mol %, preferably at least 90 mol %, more preferably at least 95 mol % H ２ The method of any one of claims 1 to 6, comprising O.
8. A method according to any one of the preceding claims, wherein the driving fluid (20) in step (b) has a pressure in the range of 60 to 300 bara, preferably 80 bara to 200 bara.
9. The method according to any one of the preceding claims, wherein the driving fluid (20) in step (b) has a temperature of 20 to 70°C, preferably 30 to 50°C.
10. The method according to any one of the preceding claims, wherein the two-phase fluid (30) obtained in step (c) has a pressure between 2.0 bara and 10.0 bara, preferably between 3.0 bara and 6.0 bara.
11. An apparatus (1) for compressing a water-containing, oxygen-containing stream (10) coming from an electrolytic cell, comprising at least: - electrolyzing a water-containing stream, thereby producing at least H ２ an electrolytic cell for obtaining a water-containing stream and a water-containing oxygen-containing stream (10); an ejector (2) for mixing said water-containing, oxygen-containing stream (10) as suction fluid with a water-containing stream (20) as driving fluid, thereby obtaining a mixed stream (25), and for flashing said mixed stream (25), thereby obtaining a two-phase fluid (30) discharged from said ejector (2); a separator (3) for separating the two-phase fluid (30) discharged from the ejector (2) into an oxygen-containing gas stream (40) and a liquid stream (50); a pressure booster (4), in particular a pump, for pressurizing said liquid flow (50) and thereby obtaining a pressurized liquid flow; a recirculation line for recirculating at least a portion of the pressurized liquid flow used as the driving fluid (20) in the ejector (2); a dehydrogenator (6) for dehydrogenating said oxygen-containing gas stream (40), thereby obtaining a dehydrogenated oxygen-containing stream (70); a dehydrator (7) for dehydrating said dehydrogenated oxygen-containing stream (70), thereby obtaining a dehydrated dehydrogenated oxygen-containing stream (80); at least one compressor (8) for compressing said dehydrated and dehydrogenated oxygen-containing stream (80), thereby obtaining a compressed oxygen-containing stream (90); a gasifier (9) in which said compressed oxygen-containing stream (90) is used.