KR20130016217A - Electrochemical process having improved efficiency and related electrochemical reactor such as a high-temperature electrolyser (hte) - Google Patents

Abstract

The present invention is directed to the molecular weight of the initial component (s) in gas or vapor form, which is made to flow the gas or vapor of the initial component (s) in gas or vapor form and the reaction gas is recovered in the path through which the initial component (s) is made to flow. A new electrochemical method for producing a reaction gas of lower molecular weight.
According to the invention at least one vortex is formed in the upstream region from the recovery zone of the reaction gas and the vortices / vortices are still present to allow the initial component (s) still present to undergo an electrochemical process in the upstream region. The reaction gas generated from the component (s) can be separated.
The present invention is applicable to applications in which the hydrogen produced by the vortices / vortices is separated from the residual steam by electrolysis at high temperatures so that the residual steam undergoes an electrolysis process in the electrolysis device itself.

Description

ELECTROCHEMICAL PROCESS HAVING IMPROVED EFFICIENCY AND RELATED ELECTROCHEMICAL REACTOR SUCH AS A HIGH-TEMPERATURE ELECTROLYSER (HTE)}

The present invention relates to the molecular weight of the initial component (s) in gas or vapor form, where the gas or vapor of the initial component (s) in gas or vapor form is made to flow and the reactant gas is recovered in a path through which the initial component (s) is made to flow. Electrochemical methods of producing reaction gases of lower molecular weight.

The present invention is directed to an improvement in the efficiency of this method.

The main application related to the present invention is the electrolysis of water at high temperatures (EHT), also called high temperature steam electrolysis (EVHT).

The electrochemical reactor includes a plurality of base cells formed of a cathode and an anode separated by an electrolyte, wherein the base cell is electrically connected by an interconnecting plate generally disposed between the anode of the base cell and the cathode of the adjacent base cell. Connected in series. Also possible is an anode-anode connection, followed by a cathode-cathode connection. The interconnect plate is an electronically conductive component formed by one or more metal plate (s). These plates hereafter provide separation between the anode fluid flowing in the base cell and the cathode fluid flowing in one base cell.

The anode and cathode are made of a porous material through which gas can flow.

In the case of electrolyzing water to produce hydrogen at high temperatures, steam flows in the cathode where hydrogen can be produced in gaseous form and exhaust gas can flow in the anode thereby collecting oxygen produced in the gaseous form at the anode. . Most high temperature electrolysis devices use air as exhaust gas at the anode.

At this point, the fluid circuit created by the compartments defined by the interconnect plate has a relatively simple architecture.

Generally, the fluid at the outlet of the cathode contains not only the hydrogen to be produced but also the residual vapor left from itself in the electrolysis electrochemical reaction. In other words, the conversion rate of the high temperature electrolysis device is not 100%. In fact, in order to increase the average production density, steam is generally intentionally produced in excess, resulting in losses that achieve high steam consumption (or high hydrogen conversion).

Then, if it is desired to convert almost 100% of the steam to hydrogen, the distribution of the fluid across the surface is very large so far so that the surface of the cell, or whatever path the steam follows from its inlet, is nearly the same. I saw that it was necessary to optimize. The disadvantage of the first option is the reduction in average productivity, while the disadvantage of the second option lies in the implementation (steam circuit to be produced) which can be complex.

Furthermore, many designers of EHT electrolysis devices tend to pay particular attention to the density level of productivity to be achieved as described above from the design stage, and thus the loss of conversion rate.

Finally, for these same designers it is easy to separate the unconverted steam from the hydrogen produced at the outlet of the cathode, for example by installing additional means downstream of the high temperature electrolysis device, where the function of these additional means is Is to separate the remaining steam from the hydrogen produced. In most designs of electrolysis devices produced at the same time, these additional means consist of a condenser fitted outside the electrolysis device to separate the water from the hydrogen. Selective porous membranes have also been mentioned as additional means fitted outside the electrolysis device, which allows hydrogen to pass preferentially over steam.

Therefore, the disadvantages of the high temperature electrolysis device according to the prior art as described above can be summarized as follows: the efficiency is not complete due to the remaining steam at the outlet and the operation is the steam left from the electrolysis reaction itself. It requires the use of additional downstream means to separate the hydrogen produced therefrom.

One object of the present invention is therefore to compensate for all or part of the disadvantages of the prior art and thus to propose a solution which allows at least the hydrogen productivity efficiency to be improved in high temperature electrolysis devices.

A more general object of the present invention is an initial component (s) in gas or vapor form, in which a gas or vapor of initial component (s) in gas or vapor form is made to flow and the reactant gas is recovered in a path through which the initial component (s) flows. It is to propose a solution that can improve the efficiency of the electrochemical process in order to produce a reaction gas of molecular weight less than the molecular weight).

To achieve this, one object of the present invention is a gas or vapor, in which a gas or vapor of the initial component (s) in gaseous or vapor form is made to flow and the reaction gas is recovered in a path through which the initial component (s) is made to flow. An electrochemical method for producing a reaction gas of molecular weight less than the molecular weight of the initial component (s) in the form, wherein at least one vortex is formed in the upstream region from the recovery region of the reaction gas, wherein the vortex is still present Wherein the initial component (s) can separate the reaction gas produced from the initial component (s) in order to undergo an electrochemical process in the upstream region.

It is obvious that the region upstream from the reaction gas recovery zone should be considered to be a reaction zone where conversion from steam to hydrogen in a broad sense.

Thus, the present invention essentially slows the output of the initial component (s) relative to the gas derived from the reaction, which can be output directly because it is less dense, while the initial component (s) tangential to the outside of the vortex Direction and thus again undergoes the electrochemical process in the region upstream from the outlet.

From one aspect, the present invention provides a method of high temperature electrolysis of water embodied by at least one basic electrolysis cell formed of a cathode, an anode and an electrolyte inserted between the cathode and the anode according to the method described above. Vapor at least in contact with the inlet end is made to flow from the inlet end to the outlet end whereby hydrogen produced is recovered and thus at least one vortex is formed in the upstream region from the outlet end, the vortices / vortices still present Relates to a method for high temperature electrolysis of water, which is capable of separating hydrogen produced from steam still present in order to undergo an electrolytic process in the upstream region.

The means for forming the vortex according to the invention are therefore incorporated in the high temperature electrolysis device itself, thus increasing the output of hydrogen and slowing the output of the steam by venting out of the vortex.

The formation of vortices (or vortices) makes it possible to achieve high centripetal acceleration and thus to apply centripetal forces of different densities depending on the species. The term "high temperature" is understood in the context of the present invention to mean a temperature of at least 450 ° C, generally from 700 ° C to 1000 ° C.

This integration makes it possible to produce a high temperature electrolysis device (EHT) having one outlet for the generated hydrogen and an inlet for the steam since the residual steam is once again converted to hydrogen near the outlet. The electrochemical reactor thus electrolyzing water completely converts the steam provided at the inlet as long as the steam remains for a sufficiently long time. Therefore, by forming one or more vortices, water molecules can be retained for a longer period of time in the active electrochemical reaction zone by centrifugal force, thereby increasing the likelihood that they can be converted to hydrogen.

Electrolysis of water associated with the present invention is preferably achieved at temperatures of 700 ° C to 1000 ° C.

Advantageously, a number of vortices are formed in the region upstream from the outlet end in parallel or in series with respect to one another in order to improve the performance, ie the electrochemical efficiency.

Each vortex is preferably formed at a tangential velocity of at least 80 m / s, preferably in excess of 100 m / s.

Also preferably each vortex is formed such that it can achieve an acceleration exceeding 10 ⁶ m / s ² .

The present invention also provides a reaction gas having a molecular weight less than the molecular weight of the initial component (s), which is in the form of a gas or vapor having a stack of basic electrochemical cells each formed of a cathode, an anode, and an electrolyte interposed between the cathode and the anode. An electrochemical reactor intended to produce, wherein at least one interconnect plate is sandwiched between two adjacent base cells and one electrode of one of the two base cells and one of the other of the two base cells In electrical contact with an electrode of the interconnecting plate, the interconnecting plate defining at least one cathode compartment and at least one anode compartment for allowing fluid to flow in the cathode and the anode, respectively, which is the outlet of the cathode compartment and / or the anode compartment. Means for forming at least one vortex in the region upstream from the end, the vortices / vortices still It is directed to an electrochemical reactor capable of separating the reaction gas produced from the initial component (s) still present in order for the initial component (s) present to undergo an electrochemical process in the upstream region.

The means for forming the vortices / vortices is advantageously a hole pierced in at least one interconnecting plate upstream from the outlet end of the cathode compartment. This solution is simple to implement and can easily be applied to all types of interconnect plates.

The diameter of the hole is preferably less than 1 mm, given the customary flow rate found in the EHT electrolysis device and the cell size of the electrolysis device.

Finally, the present invention relates to a plate intended to be used as an interconnecting plate in a reactor as described above, comprising two partially buckled plates that form grooved recessed recesses. Consisting of an assembled assembly, the assembly having at least one opening, each opening traversing two assembled metal plates and being made in a differently concave region at the end of the groove, the hole being one of the two metal plates And made in a differently concave region at the end of the groove, the hole is distributed around the opening, the diameter of the hole is about 1 mm or less, and in the differently concave region the assembly of the metal plate is two metal plates. Define the passage between the opening and the hole in between and around them.

The number of holes is preferably even. This increases the alternate rotation of the vortex.

Again preferably, the end of the groove is made such that a mixture of gas and vapor or a gas jet is formed at the end, where the jet also has an outflow tangential to one of the holes. Vortex phenomena are increased by causing jets in a tangential direction in this way.

According to the present invention, the hydrogen productivity efficiency in the high temperature electrolysis device can be improved.

Other features and advantages will become more apparent when reading the detailed description made with reference to the drawings.
1 is a side view of one embodiment of a high temperature electrolysis reactor in accordance with the present invention.
5 is a cross-sectional view of the plane AA of the reactor of FIG.
1B is a cross-sectional view of the plane BB of the reactor of FIG. 1.
2 is a plan view of an interconnecting plate according to the invention used in a high temperature electrolysis reactor.
2A is a detailed cross-sectional view of FIG. 2 along axis AA.
3 is a schematic diagram of a physical phenomenon according to the present invention;
4 shows a graph of the change in average productivity as a function of the flow rate of steam at the inlet of an EHT electrolysis device according to the present invention and the prior art.

The present invention is described in terms of the architectural type of a high temperature water electrolysis device to produce hydrogen. The present invention may be applied to other architectures, and also first there is a reaction product that is less dense than the initial product (s), where the conversion reaction requires time "and reconcentration" and other devices that can be inserted into this reactor. It is obvious that it may be applied to chemical or electrochemical reactors. The high temperature at which the illustrated electrolysis device operates is between 700 ° C and 1000 ° C.

The terms "upstream" and "downstream" are interpreted as being used with respect to the flow direction of hydrogen and vapor produced at the cathode.

It is understood that the representation of the different elements is not drawn to scale.

In FIG. 1 an EHT electrolysis device according to the invention is shown having a plurality of stacked basic cells (C1, C2, etc.).

Each base cell has an electrolyte located between the cathode and the anode.

In the remainder of this description, the cells C1 and C2 and their boundaries are described in detail.

Cell C1 has a cathode 2.1 and an anode 4.1 between which is generally 100 μm thick for a cell called an “electrolyte supported” cell and a few μm for a cell called a “cathode supported” cell. A thick electrolyte (6.1), for example a solid electrolyte, is placed.

The cell C2 has a cathode 2.2 and an anode 4.2 between which an electrolyte 6.2 is placed. All electrolytes are of solid type.

The cathodes (2.1, 2.2) and the anodes (4.1, 4.2) are made of porous material and are generally on the order of 1 mm and 40 μm, respectively, for example exceeding 500 μm thickness.

The anode 4.1 of the cell C1 is electrically connected to the cathode 2.2 of the cell C2 by an interconnecting plate 8 in contact with the anode 4.1 and the cathode 2.2. In addition, this allows the anode 4.1 and the cathode 2.2 to be electrically powered.

The interconnect plate 8 is arranged between the two basic cells C1, C2.

In the example shown, this interconnect plate is disposed between the anode of one base cell and the cathode of an adjacent cell. However, this interconnect plate can be arranged between two anodes or two cathodes.

The interconnect plate 8 defines a channel through which fluid can flow along with adjacent anodes and adjacent cathodes. More specifically, they define an anode compartment 9 dedicated to the flow of gas at the anode 4 and a cathode compartment 11 dedicated to the flow of gas at the cathode 2.

In the example shown, the anode compartment 9 is separated from the cathode compartment 11 by a wall 991. In the example shown, the interconnecting plate 8 further comprises at least one duct 10 defining an anode compartment 9 and a cathode compartment 11, with a wall 991.

In the example shown, the interconnecting plate has a plurality of ducts 10, a plurality of anode compartments 9 and a plurality of cathode compartments 11. Advantageously, the duct 10 and the compartments have hexagonal honeycomb sections that enable to increase the density of the compartments 9, 11 and the duct 10.

As shown in FIG. 1A, steam is circulated at each cathode 2.1, 2.2.

The arrow 12 in FIG. 1A clearly shows the path in the anode compartment 9 and the cathode compartment 11.

As shown in FIG. 1B, the architecture of the electrolysis device also enables the first end 10.1 of the duct 10 to be connected to the supply of steam through another unshown duct and to the second end of the duct 10. 10.2 can be connected to the cathode compartment 11. The arrow 14 shows the return flow of steam from the flow of the duct 10 (arrow 16) towards the cathode compartment 11.

The exhaust gas flowing in the anode compartment 9 may be determined to exhaust oxygen (arrow 13). Arrows 12 and 13 in FIGS. 1A and 1B clearly show simultaneous paths in the anode compartment 9 and the cathode compartment 11. It is obvious that the flow shown in the context of the invention can be shown in the same way in the other directions (opposite of arrows 12 and 13).

The inventors found that the hydrogen and steam remaining in the hydrogen produced at the outlet end of each cathode were mixed: this steam was left in the electrolysis reaction taking place upstream.

Most often it is known to treat this residual steam by separating it from the hydrogen produced by a condenser fitted downstream from the electrolysis device.

The inventors devised the idea of forming one or more vortices / vortices upstream from the outlet, ie upstream from the outlet opening dedicated to collecting the generated hydrogen.

In fact, the relative density between the hydrogen and the steam generated in the mixture reaching near the outlet of each of the main electrolytic cell, while the hydrogen molecular weight of 2g · mol ^-1, the molecular weight of steam 18g · mol ^{- 1,} so 9 to be.

Thus, by forming one or more vortices / vortices in the flow steam of the mixture composed of the produced hydrogen and residual steam, the two types of molecular weights (H ₂ and H ₂ O) are subjected to different centrifugal forces, which are heavy molecules (H ₂ The centrifugal force of O) is increased to extract light molecules (H ₂ ).

This phenomenon of vapor molecules at the outlet occurs stronger as it gets closer to the outlet.

The means for forming the vortex in which the inventors devised the idea in FIGS. 2 and 2a are shown in the architecture of an electrolysis device having the interconnecting plates 8 described above.

Each interconnect plate 8 consists of an assembly of two partially buckled metal plates 8.1, 8.2 forming a recessed recess in the form of a groove 80.

As shown in FIGS. 2 and 2A, the assembly 8 has at least one opening 84, with each opening traversing two assembled metal plates.

This opening 84 is made in the recessed area Z in a different way at the end of the groove 80. This region Z, which is recessed in a different way, may be a non-concave region.

In the region Z concave in a different way at the end of the groove 80, the hole 83 traverses only one of the two metal plates 8. 1 and is regularly distributed around the opening 84.

The diameter of the hole 83 is about 1 mm but may be smaller than this. Preferably the number of holes 83 is even to increase the alternate rotation of the vortex. Thus, as shown in FIG. 2, there are 12 holes 83 regularly spaced around the opening 84.

The assembly of two metal plates 8.1, 8.2 in differently concave regions Z defines a passage 840 between the two metal plates 8.1, 8.2 and between the hole 83 and the opening 84 ( 2a).

Groove 80 is a groove dedicated to the collection of generated hydrogen. Similarly, opening 84 is an opening dedicated to the recovery of hydrogen produced by the electrolysis reaction: it conventionally constitutes part of a collection assembly called a supply manifold and through which pipes (not shown) Is installed.

Due to the presence of holes 83 of diameter 1 mm or less and due to the flow rate of the inlet in the zone Z, the mixture (residual vapor and generated hydrogen) reaching this zone Z exceeds 100 m / s. Pass through several vortices in parallel at tangential speed.

This mixture is thus subjected to the acceleration calculated using the following formula:

here

: 가속도,

: Acceleration,

V: tangential velocity,

R: radius of exit hole

, 즉 지상 가속도에 1백만배에 가까운 가속도.or

Acceleration, close to 1 million times over ground acceleration.

At this acceleration, lighter hydrogen molecules tend to be exhausted through the hole 83 in fluid communication with the recovery opening 84 (see arrow 15 in FIG. 2A). The molecular weight of water in the residual vapor, which is heavier than the molecular weight of hydrogen, tends to be discharged outward in its function and is therefore available and subject to an electrolytic process in zone Z, ie in the electrolysis device itself. .

As shown in FIG. 2, the end 800 of the groove 80 upstream from the zone Z is advantageously made such that a jet of hydrogen and vapor is formed at the end 800. Furthermore, at the exit of this end the jet has a flow tangential to the axis of each hole 83. The phenomenon of the vortex formed by the hole 83 is even more increased.

3 schematically shows the appearance of the vapor of hydrogen gas V caused by the vortex formed by the hole 83, where the arrow indicates the scanning direction of the water molecules.

4 shows the increase in overall efficiency caused by the invention in an EHT electrolysis device:

Solid line curve 3 shows the change in average productivity with increasing flow rate of steam in an EHT electrolysis device according to the prior art,

Dashed curve 5 shows the change in average productivity with increasing flow rate of steam in the EHT electrolysis device according to the invention,

The dashed straight line (L _T ) schematically shows the change in average productivity with increasing steam flow rate in the theoretical case where 100% conversion of steam to hydrogen is fully achieved.

It is evident from the invention that the curve 5 is closer than the curve 3 to the theoretical straight line L _T. In other words, forming a vortex in accordance with the present invention results in migration at a vapor conversion rate of nearly 100%.

The present invention as described above thus produces a gas produced from an electrochemical reaction by slowing the exhaust of the reaction gas (H2 in this example) and causing the gas or vapor constituting the initial component (s) to undergo another electrochemical process. One or more vortices / vortices in the upstream region from the recovery region for recovery, i.e. form one or more vortices / vortices tangential to the axis of the hole.

Compared to the various methods of forming vortices in the prior art used to separate the two components, in the present invention there is one inlet of gas / steam and one outlet of gas and the vortices / vortices are the axes of the reaction gas recovery holes. It is defined to be formed in a tangential direction. And, unlike vortices formed according to the prior art, where the lightest molecules are removed to the outside, the vortices in the present invention are formed such that the heaviest molecules, ie molecules of the initial component (s), are removed outward.

The present invention described above provides many advantages.

In fact, the advantages of incorporating vortex forming means directly into the basic electrolysis cell itself are:

-Increase the overall efficiency: in fact, there is no need for more water to flow for a given productivity, so less water must condense,

-Greater efficiency,

-Simplicity of configuration: the holes made in the high temperature electrolysis device itself are simple,

The compactness is improved by having less steam flow and condensate at the outlet, and this makes it possible to reduce the size of the heat exchanger.

Although a high temperature electrolysis device has been described, the solution according to the invention allows the reaction gas to be vaporized so long as the vortices / vortices according to the invention allow the heaviest molecules to be separated by centrifugal force from the initial component (s) of the reaction gas. Or applicable to all electrochemical methods having a lower molecular weight than the initial component (s) in gaseous form. The initial component (s) once again undergo an electrochemical reaction in the upstream region immediately adjacent to the outlet from which the reaction gas is recovered.

For example, in a fuel cell of the PEMFC type, the reaction occurring at the cathode is recorded as follows:

_{^{O 2 + 4H + + 4e -}} → 2 H 2 O.

At the cathode outlet it may be considered to exhaust the generated steam more easily than the oxygen supplied by forming a vortex according to the invention.

Claims (13)

Less than the molecular weight of the initial component (s) in gaseous or vapor form, which causes the gas or vapor of the initial component (s) in gaseous or vapor form to flow and the reactant gas is recovered in the path through which the initial component (s) is made to flow. As an electrochemical method of producing a reaction gas of molecular weight,
At least one vortex is formed in the upstream region from the recovery zone of the reaction gas, where the vortex is still present initial component (s) to still undergo the electrochemical process in the upstream region. Electrochemical method, characterized in that the generated reaction gas can be separated from. A method of electrolyzing water at high temperatures according to claim 1,
At least one basic electrolysis cell (C1, C2, ..., Cn) formed of a cathode (2.1, 2.2), an anode (4.1, 4.2) and an electrolyte (6.1, 6.2) inserted between the cathode and the anode. Wherein the vapor at least in contact with the cathode is made to flow from the inlet end to the outlet end and hydrogen generated through the end is recovered and at least one vortex is formed in the upstream region from the outlet end and the vortex / vortex They are capable of separating the hydrogen produced from the still present steam in order for the still present steam to undergo an electrolytic process in the upstream region. The electrolysis method according to claim 2, wherein the electrolysis is at a temperature of 700 ° C to 1000 ° C. 4. The method of claim 2 or 3, wherein a plurality of vortices are formed in the upstream region from the outlet end in parallel with each other. 4. The method of claim 2 or 3, wherein a plurality of vortices are formed in the upstream region from the outlet end in series with respect to each other. 6. The method of claim 1, wherein each vortex is formed at a tangential velocity of at least 80 m / s, preferably greater than 100 m / s. 7. 7. The method of any one of the preceding claims, wherein each vortex is formed to achieve an acceleration in excess of 10 ⁶ m / s ² . An electrochemical reactor comprising a stack of basic electrolysis cells (C1, C2, ..., Cn), each cell having a cathode (2.1, 2.2), an anode (4.1, 4.2) and between the cathode and the anode And an at least one interconnecting plate 8 sandwiched between two adjacent base cells and having one electrode of one of the two base cells and one of the two base cells Electrical contact with one electrode of another cell, the interconnecting plate defining at least one cathode compartment 11 and at least one anode compartment 9 for fluid to flow in the cathode and the anode, respectively; In a chemical reactor,
And means (83) for forming at least one vortex in the upstream zone (Z2) from the cathode compartment and / or the outlet end (82) of the anode compartment. 9. An electrochemical reactor according to claim 8, wherein the means for forming the vortices / vortices is advantageously comprised of a hole (83) perforated in at least one interconnection plate upstream from the outlet end of the cathode compartment. . 10. The electrochemical reactor of claim 9, wherein the diameter of the hole is less than 1 mm. Two partially buckled as plates 8 intended for use as interconnecting plates in the reactor according to any one of claims 8 to 10 and forming a recessed recess in the form of grooves 80. Consisting of an assembly of buckled plates (8.1, 8.2), the assembly having at least one opening (84), each opening traversing two assembled metal plates and having an end (800) of the groove. In a recessed region Z in a different manner in which a hole 83 traverses a plate 8.1 of one of the two metal plates, the hole also being made in a different recessed region at the end of the groove In the periphery of the opening 84, the diameter of the hole is on the order of 1 mm or less, and in the differently concave area the assembly of the two metal plates is between the two metal plates 8.1, 8.2 and the hole 83 ) And the hole is made Plate, characterized in that to limit the passage 840 between the opening (84) in the area. 12. The plate according to claim 11, wherein the number of holes (83) is even. 13. The groove 800 according to claim 11 or 12, wherein the end 800 of the groove is made such that a mixture of gas and vapor or a gas jet is formed at the end, the jet also tangentially to one of the holes 83. A plate characterized by having an outflow.

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