Operating method for operating an electrolysis system and electrolysis system

Abstract

The presented invention relates to an operating method (100) for operating an electrolysis system (200), wherein the operating method (100) comprises: - converting (101) reactants into products by means of an electrochemical cell (201) with the supply of electric current, - Providing (103) a pulsating mass flow with which a number of reactants are supplied to an anode subsystem (203) of the cell (201).

Description

[0001] The presented invention relates to an operating method for operating an electrolysis system and an electrolysis system for converting energy, according to the appended claims. State of the art

[0002] Low-temperature electrolyzers, such as proton exchange membrane (PEM), anion exchange membrane (AEM) or alkaline water electrolysis (AEL), require at least pure water or potassium hydroxide solution (KOH) as a reactant or starting material on the anode side for the electrochemical reaction to produce hydrogen.

[0003] By applying an electric current, oxygen is produced at the anodic phase boundary of the electrochemical cell and hydrogen at the cathodic phase boundary. Thus, a solid, liquid, and gas phase typically exists at both phase boundaries.

[0004] By diffusion through the porous structures of the two electrodes, the products hydrogen and oxygen are transported to the outlet of each cell and further processed downstream of the electrolysis system, for example by removal / separation / drying / compression, etc.

[0005] The supply and removal of the reactants, such as water or potassium hydroxide solution, and the products hydrogen and oxygen can be realized in the cell either in a targeted manner via a so-called “flow field” or via a porous structure or a free space in the cell.

[0006] Rapid removal of the product gases is particularly advantageous, since the gas bubbles formed at the phase boundaries block active centers of, for example, catalyst material or adjacent electrochemically active areas.

[0007] Accordingly, the resulting gas bubbles should be rapidly desorbed from the phase boundaries and removed in optimized cell structures. Gas bubble desorption is based on purely thermodynamic and hydraulic principles. However, the blockage of electrochemically active centers by resulting gas bubbles during operation is considered to be a significant contributor to cell resistance. The blockage of active material by growing oxygen gas bubbles at the anode is considered to be particularly influential. Disclosure of the invention

[0008] Within the scope of the invention presented, an electrolysis system and an operating method for operating the electrolysis system are presented. Further features and details of the invention emerge from the respective subclaims, the description, and the drawings. Features and details described in connection with the operating method according to the invention naturally also apply in connection with the electrolysis system according to the invention, and vice versa, so that with regard to the disclosure of the individual aspects of the invention, reference is always made to each other.

[0009] The invention presented serves in particular to provide a possibility for energy-efficient and robust operation of an electrolysis system.

[0010] Thus, according to a first aspect of the invention presented, an operating method for operating an electrolysis system is presented.

[0011] The presented operating method comprises the conversion of reactants into products by means of an electrochemical cell or cell stack with the supply of electrical current and the provision of a pulsating mass flow with which a number of reactants are supplied to an anode subsystem of the electrochemical cell or cell stack.

[0012] In the context of the invention presented, a pulsating mass flow is understood to mean a mass flow from a fluid, in particular a liquid, whose strength or size or amplitude changes with a predetermined frequency.

[0013] The presented invention is based on the principle of changing or influencing the mass flow with which a number of reactants move in a pipe system of an electrolyzer. By changing or influencing the mass flow, the mass flow is pulsated at least temporarily and applies a mechanical-hydraulic force to the anode subsystem that changes over time.

[0014] In particular, the pulsating mass flow induces a shaking of the anode subsystem, through which gas bubbles adhering to the anode subsystem are released from the anode subsystem and accordingly discharged from the electrolysis system.

[0015] It may be provided that, in order to provide the pulsating mass flow, a valve in a line system for directing the mass flow to the anode subsystem or away from the anode subsystem is repeatedly opened and closed at a predetermined frequency.

[0016] By opening and closing a valve, the hydraulic resistance opposing the mass flow can be changed. Accordingly, repeated opening and closing of the valve leads to a change in the strength, size, or amplitude of the mass flow.

[0017] It may further be provided that the valve is selected from the following list of valves: chopper valve, solenoid valve, inline check valve.

[0018] In particular, switchable valves have proven to be suitable for carrying out the presented operating procedure.

[0019] For example, the pulsating movement of the mass flow can be limited to a discharge path using a check valve.

[0020] It can further be provided that, in order to provide the pulsating mass flow, a speed of a pump for conveying the mass flow is repeatedly changed at a predetermined frequency.

[0021] By changing the pump speed, the mass flow is subjected to a changing pressure, which is then transferred to the anode subsystem. Accordingly, by changing the pump speed, the force acting on the anode subsystem can be adjusted particularly precisely and directly.

[0022] It can further be provided that, in order to provide the pulsating mass flow, ultrasonic waves are coupled into the mass flow by means of an ultrasonic generator.

[0023] An ultrasonic generator generates a pulsating surface that directly transmits a high-frequency pulsating motion corresponding to the mass flow and reliably detaches the gas bubbles from the anode subsystem. According to a second aspect, the presented invention relates to an electrolysis system for converting energy.

[0024] The electrolysis system presented comprises an electrochemical cell or a cell stack for converting a mass flow of a number of reactants into products by supplying electrical current and a computing unit, wherein the computing unit is configured to carry out a possible embodiment of the presented operating method.

[0025] In the context of the invention presented, a computing unit is understood to mean a computer, a processor, a control unit or any other programmable circuit.

[0026] The presented operating procedure is used in particular for the operation of the presented electrolysis system.

[0027] The electrolysis system presented is in particular a low-temperature electrolysis system, such as a proton exchange membrane (PEM), anion exchange membrane (AEM) or alkaline water electrolysis (AEL) system.

[0028] The electrolysis system presented can use, for example, potassium hydroxide solution or water as a reactant, so that the pulsating mass flow according to the invention is, for example, a potassium hydroxide solution mass flow or a water mass flow.

[0029] It can be provided that the electrolysis system comprises a valve in a conduit system for directing the mass flow to an anode subsystem of the electrolysis system or away from the anode subsystem, and the computing unit is configured to control the valve at a predetermined frequency in order to convert the mass flow into a pulsating movement.

[0030] It may further be provided that the valve is selected from the following list of valves: chopper valve, solenoid valve, inline check valve.

[0031] It can further be provided that the electrolysis system comprises a pump for conveying the mass flow, and the computing unit is configured to repeatedly change a speed of the pump at a predetermined frequency in order to convert the mass flow into a pulsating movement.

[0032] A pump, such as a diaphragm pump or a centrifugal pump, can be adjusted particularly quickly and precisely in its speed, so that the pulsating movement of the mass flow through a pump can be adjusted particularly quickly and precisely.

[0033] It can further be provided that the electrolysis system comprises an ultrasonic generator, and the computing unit is configured to control the ultrasonic generator in order to couple ultrasonic waves into the mass flow and to convert the mass flow into a pulsating movement.

[0034] Advantages that have been described in detail with respect to the operating method for operating an electrolysis system according to the first aspect of the invention equally apply to the electrolysis system for converting energy according to the second aspect of the invention.

[0035] Further advantages, features, and details of the invention will become apparent from the following description, in which exemplary embodiments of the invention are described in detail with reference to the drawings. The features mentioned in the claims and in the description may be essential to the invention individually or in any combination.

[0036] They show schematically: Fig. 1 a possible design of the presented operating procedure, Fig. 2 a possible design of the presented electrolysis system.

[0037] In Fig. 1 shows an operating method 100 for operating an electrolysis system.

[0038] The operating method 100 comprises a conversion step 101 in which reactants are converted into products by means of a cell stack with the supply of electrical current.

[0039] Furthermore, the operating method 100 comprises a provision step 103 in which a pulsating mass flow is provided with which a number of reactants are supplied to an anode subsystem of the cell stack.

[0040] In Fig. 2 shows an electrolysis system 200 for converting energy.

[0041] The electrolysis system 200 comprises an electrochemical cell 201 with an anode subsystem 203 and a cathode subsystem 205.

[0042] Furthermore, the electrolysis system 200 comprises a computing unit 205 which is configured to carry out the operating method 100 according to Fig. 1 to execute.

[0043] A pump 207 supplies a mass flow of reactants consisting of demineralized water and / or potassium hydroxide or potassium hydroxide solution from a tank 217 to a filter 209 and finally to the anode subsystem 203 of the electrochemical cell 201.

[0044] By means of a valve 211, the mass flow can be influenced so that it is converted into a pulsating movement and the anode subsystem 203 is subjected to a varying mechanical hydraulic force, by means of which gas bubbles adhering to the anode subsystem 203 are released and discharged from the electrolysis system 200 via a gas separator 213.

[0045] To carry out the electrolysis process, the electrochemical cell 201 is supplied with electrical current by an inverter or a DC voltage supply 215.

[0046] An optional ultrasonic generator 219 can be used alternatively or additionally to convert the mass flow into a pulsating movement.

[0047] Furthermore, the electrolysis system 200 comprises a computing unit 221 which controls the components of the electrolysis system 200.

Claims

[1] Operating method (100) for operating an electrolysis system (200), the operating method (100) comprising: - converting (101) reactants into products by means of an electrochemical cell (201) with the supply of electric current, - Providing (103) a pulsating mass flow with which a number of reactants are supplied to an anode subsystem (203) of the cell (201). [2] Operating method (100) according to claim 1, characterized by in that, to provide the pulsating mass flow, a valve (211) in a line system for conducting the mass flow to the anode subsystem (203) or away from the anode subsystem (203) is repeatedly opened and closed at a predetermined frequency. [3] Operating method (100) according to claim 2, characterized by that the valve (211) is selected from the following list of valves: Chopper valve, solenoid valve, inline check valve. [4] Operating method (100) according to one of the preceding claims, characterized by in that, in order to provide the pulsating mass flow, a rotational speed of a pump (207) for conveying the mass flow is repeatedly changed at a predetermined frequency. [5] Operating method (100) according to one of the preceding claims, characterized by in that, in order to provide the pulsating mass flow, ultrasonic waves are coupled into the mass flow by means of an ultrasonic generator (219). [6] Electrolysis system (200) for converting energy, wherein the electrolysis system (200) comprises: - an electrochemical cell (201) for converting a mass flow of a number of reactants into products by supplying electric current, - a computing unit (221), wherein the computing unit (221) is configured to perform an operating method (100) according to one of claims 1 to 5. [7] Electrolysis system (200) according to claim 6, characterized by , that the electrolysis system (200) comprises a valve (211) in a conduit system for directing the mass flow to an anode subsystem (203) of the electrolysis system (200) or away from the anode subsystem (203), and the computing unit (221) is configured to control the valve (211) at a predetermined frequency in order to convert the mass flow into a pulsating movement. [8] Electrolysis system (200) according to claim 7, characterized by that the valve (211) is selected from the following list of valves: Chopper valve, solenoid valve, inline check valve. [9] Electrolysis system (200) according to one of claims 6 to 8, characterized by , that the electrolysis system (200) comprises a pump (207) for conveying the mass flow, and the computing unit (221) is configured to repeatedly change a rotational speed of the pump (207) at a predetermined frequency in order to convert the mass flow into a pulsating movement. [10] Electrolysis system (200) according to one of claims 6 to 9, characterized by that the electrolysis system (200) comprises an ultrasonic generator, and the computing unit (221) is configured to control the ultrasonic generator in order to couple ultrasonic waves into the mass flow and to convert the mass flow into a pulsating movement.

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