System and method for estimating the current efficiency of an electrolytic cell

Abstract

An estimation system for estimating the current efficiency of an electrolytic cell includes a data processing system (105). The data processing system (105) calculates the heat loss of the electrolytic cell based on the specific heat capacity of the electrolyte, the flow rate of the electrolyte on the cathode side of the electrolytic cell, the flow rate of the electrolyte on the anode side, the temperature difference (T1c - T0c) between the outlet and the inlet of the electrolyte circulation section on the cathode side, and the temperature difference (T1a - T0a) between the outlet and the inlet of the electrolyte circulation section on the anode side. The current efficiency is estimated based on the difference between the power supplied to the electrolytic cell and the calculated estimated value of the heat loss, and the product of the thermal neutral voltage of the electrolytic cell of the electrolytic cell and the current supplied to the electrolytic cell.

Description

Technical Field

[0001] The present disclosure relates to a system, a method, and a computer program for estimating the current efficiency of an electrolyzer, such as an alkaline water electrolyzer, a proton exchange membrane "PEM" water electrolyzer, or an electrolyzer for brine. Further, the present disclosure relates to an electrolyzer system, a method for controlling the electrolyzer system, and a computer program for controlling the electrolyzer system.

Background Art

[0002] In water electrolysis, water is electrochemically decomposed by electrical energy using two electrodes immersed in an electrolyte. Hydrogen H2 is formed at the cathode and oxygen O2 is formed at the anode. In order for this electrochemical reaction to succeed, protons H + or hydroxide ions OH - must move through an electrolyte, which can be either liquid or solid. Water itself is a poor medium for charge transfer, and thus electrolytes for water electrolysis are enhanced from a conductivity perspective. To improve charge transfer, typically the electrolyte selected is a strong base or a strong acid.

[0003] Alkaline water electrolysis is widely used and is a mature water electrolysis technology. An alkaline water electrolysis cell includes two electrodes that operate in a liquid electrolyte solution such as potassium hydroxide KOH or sodium hydroxide NaOH. The electrodes are separated by a diaphragm that allows hydrogen ions and water to pass through. For system safety, this diaphragm should be thick enough to prevent the mixing of the hydrogen H2 gas and oxygen O2 gas generated at the cathode electrode and the anode electrode, respectively. Hydroxide ions pass through the porous diaphragm and provide the ion mobility required for the electrolysis process.

[0004] A factor that significantly reduces the energy efficiency of an alkaline water electrolysis system is the tendency of stray current to flow. In conventional alkaline water electrolysis, the anolyte circulation section connects all the anode electrodes, and correspondingly, the catholyte circulation section connects all the cathode electrodes through a liquid electrolyte, thereby providing a path for stray current where the current branches (shunts). These stray current paths can cause the DC-connected electrolytic cells to be charged unevenly, leading to a decrease in system performance and an accelerated deterioration of the electrolyzer. Furthermore, the anolyte circulation section and the catholyte circulation section are mixed continuously or periodically, which may minimize the concentration gradients generated during normal alkaline water electrolysis operations. Electrolyte mixing with valve control may also provide an additional path for the flow of charge. The above-described type of stray current, also called shunt current, increases the specific energy consumption of the electrolyzer. Thus, there is a technical need to estimate the current efficiency η C of the electrolyte and enable optimization of the operation of the electrolyzer. Here, the current efficiency η C represents the ratio of the current passing through the electrolytic cell stack composed of electrolytic cells to the total current supplied to the electrolyzer, including both the current passing through the electrolytic cell stack and the stray current.

SUMMARY OF THE INVENTION

[0005] The following presents a simplified overview in order to provide a basic understanding of some aspects of various embodiments. This overview is not an extensive overview of the present invention. Nor is this overview intended to identify key or critical elements of the present invention or to define the scope of the present invention. The following overview merely presents some concepts in a simplified form as a prelude to a more detailed description of exemplary and non-limiting embodiments.

[0006] According to the present invention, a new estimation system for estimating the current efficiency of an electrolyzer is provided. The electrolyzer can be, for example, but not necessarily, an electrolyzer for brine such as an alkaline water electrolyzer, a proton exchange membrane "PEM" water electrolyzer, or a chlor-alkali electrolyzer.

[0007] The estimation system according to the present invention is equipped with temperature sensors at the inlet of the electrolyte circulation section on the cathode side of the electrolytic cell, the outlet of the electrolyte circulation section on the cathode side of the electrolytic cell, the inlet of the electrolyte circulation section on the anode side of the electrolytic cell, and the outlet of the electrolyte circulation section on the anode side of the electrolytic cell, and a data processing system, calculates an estimated value of the heat loss of the electrolytic cell based on the specific heat capacity of the electrolyte, the flow rate of the electrolyte in the electrolyte circulation section on the cathode side, the flow rate of the electrolyte in the electrolyte circulation section on the anode side, the temperature difference of the electrolyte between the outlet and the inlet on the cathode side, and the temperature difference of the electrolyte between the outlet and the inlet on the anode side, and is configured to calculate an estimated value of the current efficiency based on the difference between the power supplied to the electrolytic cell and the calculated estimated value of the heat loss of the electrolytic cell, and the product of the thermal neutral voltage of the electrolytic cell of the electrolytic cell and the current supplied to the electrolytic cell, and includes a data processing system.

[0008] In the above estimation system, the estimated value of the heat loss, which is then used to obtain an estimated value of the current efficiency, is formed by a calorimetric method. The estimated value of the current efficiency makes it possible to control the current supplied to the electrolytic cell, and the current efficiency or other quantities that depend on the current efficiency, such as a specific energy consumption, can be optimized. This optimization can be, for example, the maximization of the current efficiency or the minimization of a specific energy consumption. Therefore, the meaning of the optimization depends on the quantity to be optimized. Furthermore, the estimated value of the current efficiency makes it possible to estimate the production rate of hydrogen H2 without measuring the production flow rate.

[0009] According to the present invention, a new electrolytic cell system is also provided. The electrolytic cell system includes one or more electrolytic cells, each comprising an electrolytic cell stack having an electrolytic cell containing an electrolyte, and One or more controllable power supplies, each configured to supply a controllable DC voltage to one of the electrolytic cells such that each of the electrolytic cells is powered by one of the controllable power supplies. An estimation system according to the present invention for estimating the current efficiency associated with each of the electrolytic cells. A control system configured to control the DC voltage of each of the controllable power supplies to optimize the estimated current efficiency of the electrolytic cell powered by the controllable power supply or other quantity dependent on the estimated current efficiency.

[0010] According to the present invention, a new estimation method for estimating the current efficiency of an electrolytic cell is also provided. The estimation method according to the present invention comprises: Measuring the temperature of the electrolyte at the inlet of the electrolyte circulation section on the cathode side of the electrolytic cell, the temperature of the electrolyte at the outlet of the electrolyte circulation section on the cathode side of the electrolytic cell, the temperature of the electrolyte at the inlet of the electrolyte circulation section on the anode side of the electrolytic cell, and the temperature of the electrolyte at the outlet of the electrolyte circulation section on the anode side of the electrolytic cell. Forming an estimated value of the heat loss of the electrolytic cell by a data processing system based on the specific heat capacity of the electrolyte, the flow rate of the electrolyte in the electrolyte circulation section on the cathode side, the flow rate of the electrolyte in the electrolyte circulation section on the anode side, the temperature difference of the electrolyte between the outlet and the inlet on the cathode side, and the temperature difference of the electrolyte between the outlet and the inlet on the anode side. Forming an estimated value of the current efficiency by a data processing system based on the difference between the power supplied to the electrolytic cell and the calculated estimated value of the heat loss of the electrolytic cell, and the product of the thermal neutral voltage of the electrolytic cell of the electrolytic cell and the current supplied to the electrolytic cell.

[0011] According to the present invention, a new control method for controlling an electrolytic cell system is also provided, and the electrolytic cell system comprises: One or more electrolytic cells, each comprising an electrolytic cell stack having an electrolytic cell containing an electrolyte. One or more controllable power supplies, each configured to supply a controllable DC voltage to one of the electrolytic cells such that each of the electrolytic cells is powered by one of the controllable power supplies, and a control method according to the present invention for controlling the above electrolytic cell system, Performing an estimation method according to the present invention for estimating the current efficiency of each of the electrolytic cells, Controlling, by a control system, the DC voltage of each of the controllable power supplies to optimize the estimated current efficiency of the electrolytic cell powered by the controllable power supply or another quantity dependent on the estimated current efficiency,

[0012] According to the present invention, a new computer program for estimating the current efficiency of an electrolytic cell is also provided. The computer program according to the present invention includes computer-executable instructions for controlling a programmable data processing system, and the computer-executable instructions are For receiving temperature values indicating the temperature of the electrolyte at the inlet of the electrolyte circulation section on the cathode side of the electrolytic cell, the temperature of the electrolyte at the outlet of the electrolyte circulation section on the cathode side of the electrolytic cell, the temperature of the electrolyte at the inlet of the electrolyte circulation section on the anode side of the electrolytic cell, and the temperature of the electrolyte at the outlet of the electrolyte circulation section on the anode side of the electrolytic cell, For forming an estimated value of the heat loss of the electrolytic cell based on the specific heat capacity of the electrolyte, the flow rate of the electrolyte in the electrolyte circulation section on the cathode side, the flow rate of the electrolyte in the electrolyte circulation section on the anode side, the temperature difference of the electrolyte between the outlet and the inlet on the cathode side, and the temperature difference of the electrolyte between the outlet and the inlet on the anode side, and For calculating an estimated value of the current efficiency based on the difference between the power supplied to the electrolytic cell and the calculated estimated value of the heat loss of the electrolytic cell and the product of the thermal neutral voltage of the electrolytic cell of the electrolytic cell and the current supplied to the electrolytic cell.

[0013] According to the present invention, there is also provided a new computer program for controlling an electrolytic cell system. The electrolytic cell system includes one or more electrolytic cells, each including an electrolytic cell stack having an electrolytic cell containing an electrolyte, and one or more controllable power sources, each configured to supply a controllable DC voltage to one of the electrolytic cells such that each of the electrolytic cells is powered by one of the controllable power sources.

[0014] The computer program according to the present invention for controlling the above-described electrolytic cell system includes a computer program according to the present invention for estimating the current efficiency of each of the electrolytic cells of the electrolytic cell system, and computer-executable instructions for controlling a programmable data processing system, the instructions being for controlling the DC voltage of each of the controllable power sources to optimize the estimated current efficiency of the electrolytic cell powered by the controllable power source or another quantity depending on the estimated current efficiency.

[0015] According to the present invention, there is also provided a new computer program. This computer program product includes a non-transitory computer-readable medium, such as a compact disc "CD", encoded with the computer program according to the present invention.

[0016] Exemplary and non-limiting embodiments are described in the accompanying dependent claims.

[0017] Exemplary and non-limiting various embodiments of both the structure and the method of operation will be best understood from the following description of specific exemplary and non-limiting embodiments, together with the accompanying drawings, with their additional objects and advantageous features.

[0018] The verbs "comprising" and "including" are used in this document as open limitations that do not exclude and do not require the presence of features not described.

[0019] The features described in the dependent claims may be freely combined with each other unless otherwise explicitly stated.

[0020] Furthermore, it should be understood that the use of "a" or "an" throughout this document, i.e., the use of the singular form, does not exclude a plurality.

[0021] Exemplary and non - limiting embodiments and their advantageous aspects will be described in more detail hereinafter by way of example with reference to the accompanying drawings.

Brief Description of the Drawings

[0022]

Figure 1

Figure 2

Figure 3

Embodiments for Carrying Out the Invention

[0023] The specific examples provided in the description given hereinafter should not be construed as limiting the scope and / or applicability of the appended claims. The lists and groups of examples provided in the description given hereinafter are not exclusive unless explicitly stated otherwise.

[0024] FIG. 1 shows an electrolytic cell system including an electrolytic cell 112 and an estimation system according to an exemplary and non-limiting embodiment for estimating the current efficiency of the electrolytic cell 112. The electrolytic cell 112 includes an electrolytic cell stack 106 including electrolytic cells containing an electrolyte. The electrolyte can be, for example, an alkaline liquid electrolyte for alkaline water electrolysis. The alkaline liquid electrolyte can include an aqueous solution of potassium hydroxide “KOH” or an aqueous solution of sodium hydroxide “NaOH” or the like. However, the electrolytic cell may contain other electrolytes in some cases. In this exemplary electrolytic cell system, each electrolytic cell includes an anode, a cathode, and a porous diaphragm that divides the electrolytic cell into a cathode compartment including the cathode and an anode compartment including the anode. This diaphragm prevents the mixing of hydrogen H2 gas and oxygen O2 gas generated at the cathode electrode and the anode electrode, respectively. Hydroxide ions permeate through the porous diaphragm, thereby providing the ion mobility required for the electrolysis process. This electrolytic cell may include, for example, dozens or hundreds of electrolytic cells. However, the electrolytic cell may contain 1 to 10 electrolytic cells in some cases. In the exemplary electrolytic cell stack 106 shown in FIG. 1, the electrolytic cells are electrically connected in series. However, according to an exemplary and non-limiting embodiment, the electrolytic cells of the electrolytic cell system may be electrically connected in parallel, or the electrolytic cells may be arranged to form a group of electrolytic cells connected in series in parallel with a group of electrolytic cells connected in parallel, or the electrolytic cells may be electrically connected to each other in other ways.

[0025] The electrolyzer 112 includes a hydrogen separation tank 113 and a piping from the cathode compartment of the electrolytic cell to the hydrogen separation tank 113. The electrolyzer 112 includes an oxygen separation tank 114 and a piping from the anode compartment of the electrolytic cell to the oxygen separation tank 114. The electrolyzer 112 includes a circulation piping 110 and a circulation pump 120 configured to circulate a liquid electrolyte from the lower part of the hydrogen separation tank 113 to the lower part of the cathode compartment of the electrolytic cell. The electrolyzer 112 includes a circulation piping 111 and a circulation pump 121 configured to circulate a liquid electrolyte from the lower part of the oxygen separation tank 114 to the lower part of the anode compartment of the electrolytic cell. The electrolyte in the circulation piping 110 and the electrolyte in the circulation piping 111 constitute a path for a stray current, i.e., a shunt current, that bypasses the electrolyzer stack 106. Therefore, the current I supplied to the electrolyzer 112 branch does not entirely contribute to the decomposition of water in the electrolyzer stack 106. The current I flowing through the electrolyzer stack 106 and contributing to the decomposition of water stack is I stack = η C I branch where η C is the current efficiency of the electrolyzer 112. Correspondingly, the stray current I stray is (1 - η C )I branch . Furthermore, the electrolyte on the anode side and the electrolyte on the cathode side may be mixed continuously or periodically, which may minimize the concentration gradient generated in alkaline water electrolysis. Valve-controlled electrolyte mixing may provide an additional stray current path. The valve for mixing is not shown in FIG. 1. In the exemplary electrolyzer system shown in FIG. 1, the current I branch is supplied to the electrolyzer 112 using a controllable power source 107 connected to the three-phase power grid 109.

[0026] The current efficiency η CThe estimation system for estimation includes a temperature sensor 101 configured to measure the temperature T0c of the electrolyte at the inlet of the electrolyte circulation section on the cathode side of the electrolytic cell 112, a temperature sensor 102 configured to measure the temperature T1c of the electrolyte at the outlet of the electrolyte circulation section on the cathode side, a temperature sensor 103 configured to measure the temperature T0a of the electrolyte at the inlet of the electrolyte circulation section on the anode side of the electrolytic cell 112, and a temperature sensor 104 configured to measure the temperature T1a of the electrolyte at the outlet of the electrolyte circulation section on the anode side of the electrolytic cell 112.

[0027] The estimation system includes a data processing system 105 configured to receive data indicating the above temperatures T0c, T1c, T0a, and T1a. The data processing system 105 calculates an estimated value of the heat loss Q loss in the electrolytic cell 112 based on a specific heat capacity C e of the electrolyte, a flow rate q ca of the electrolyte in the electrolyte circulation section on the cathode side, a flow rate q an of the electrolyte in the electrolyte circulation section on the anode side, a temperature difference ΔT c = T1c - T0c between the outlet and inlet on the cathode side, and a temperature difference ΔT a = T1c - T0c between the outlet and inlet on the anode side. The data processing system 105 calculates an estimated value of the current efficiency η C based on the difference between the power U stack ×I branch supplied to the electrolytic cell 112 and the calculated estimated value of the heat loss Q loss of the electrolytic cell, and the product of the total thermoneutral voltage of the electrolytic cells of the electrolytic cell and the current I branch supplied to the electrolytic cell 112.

[0028] In the estimation system according to an exemplary and non-limiting embodiment, the data processing system 105 is configured to estimate the current efficiency η C according to the following formula.

[0029]

Equation

[0030] In the above formula, N is the number of cells in series in the electrolyzer stack 106, and U tn is the thermoneutral voltage of each electrolytic cell. In the estimation system according to an exemplary and non-limiting embodiment, the data processing system 105 is configured to estimate the thermoneutral voltage Utn according to the formula given below (R. L. LeRoy, C. T. Bowen, D. J. LeRoy: The thermodynamics of aqueous water electrolysis, J. Elechem. Soc. 127, 9, 1980 pp. 1954-1962).

[0031] [Number]

[0032] In the above formula, T is the temperature of the electrolytic cell. The temperature T may be a predetermined mathematical function of the temperature values given by, for example, the temperature sensors 101-104, and may be, for example, their arithmetic mean. Also, one or more temperature sensors may be present inside the electrolytic cell.

[0033] In the estimation system according to an exemplary and non-limiting embodiment, the data processing system 105 is configured to calculate the heat loss Q of the electrolyzer 112 according to the following formula loss .

[0034] [Number]

[0035] In the above formula, C e is the specific heat capacity of the electrolyte, q ca is the flow rate of the electrolyte in the electrolyte circulation part on the cathode side, ΔT c =T1c-T0c is the temperature difference between the outlet and the inlet on the cathode side, q anis the flow rate of the electrolyte in the electrolyte circulation section on the anode side, and ΔT a = T1c - T0c is the temperature difference between the outlet and the inlet on the anode side, and k is a constant. The flow rate q ca and q an are volumetric flow rates expressed in L / h. In an exemplary example where a specific heat capacity C e is expressed in kJ / kg°C, the constant k is the density ρ of the electrolyte expressed in kg / L. The flow rates q ca and q an are mass flow rates expressed in kg / h. In an exemplary example where a specific heat capacity C e is expressed in kJ / kg°C, the constant k is 1.

[0036] The heat loss Q of the electrolytic cell 112 loss is a value of a separate specific heat capacity and can be calculated more accurately using the value of the specific heat capacity of the electrolyte on the cathode side, i.e., the specific heat capacity of the catholyte, and the value of the specific heat capacity of the electrolyte on the anode side, i.e., the specific heat capacity of the anolyte. According to an estimation system according to an exemplary and non-limiting embodiment, the data processing system 105 is configured to calculate the heat loss Q of the electrolytic cell 112 loss according to the following formula.

[0037]

Equation

[0038] In the above formula, C e_ca is the specific heat capacity of the electrolyte on the cathode side, i.e., the specific heat capacity of the catholyte, and C e_an is the specific heat capacity of the electrolyte on the anode side, i.e., the specific heat capacity of the anolyte.

[0039] In an estimation system according to an exemplary and non-limiting embodiment, the data processing system 105 is configured to determine the specific heat capacity C e_ca as a function of the temperature of the catholyte, which is the electrolyte on the cathode side, and correspondingly, to determine the specific heat capacity C e_an as a function of the temperature of the anolyte, which is the electrolyte on the anode side. The values of C e_ca and C e_an are for C e_caand C e_an can be determined with the aid of a look-up table or equation that indicates them as a function of those temperatures.

[0040] Furthermore, C e_ca and C e_an values may depend on the chemicals of the anolyte and catholyte respectively. Since the chemicals of the anolyte and catholyte are positive for the redox reaction at the electrodes, they may change over time. Furthermore, the number of starts and stops and / or the operating time may affect the chemicals of the anolyte and catholyte and thus their thermodynamic properties, thereby affecting the C e_ca and C e_an values. In an exemplary and non-limiting embodiment of the estimation system, the data processing system 105 is configured to determine a specific heat capacity C e_ca as a multivariate function of the temperature of the catholyte, the number of starts and stops, and / or the operating time. Correspondingly, the data processing system 105 is configured to determine a specific heat capacity C e_an as a multivariate function of the temperature of the anolyte, the number of starts and stops, and / or the operating time. The C e_ca and C e_an values may be determined with the aid of a look-up table or equation that indicates C e_ca and C e_an as the above multivariate functions.

[0041] The ideal stack heat loss corresponding to the case where all the current supplied to the electrolytic cell stack 106 participates in the electrolysis reaction is as follows.

[0042]

Equation

[0043] In the above equation, η C I branch is the current supplied to the electrolytic cell stack 106. The heat loss Q loss of the electrolytic cell 112 is Q ideal +U stack (1 - η C )Ibranch That is, it is obtained by adding the heat loss of the stray current path to the heat loss of the ideal stack. That is, it is as shown in the following formula.

[0044]

Number

[0045] From [Number 5] to η C By solving, the formula [Number 1] of the current efficiency η presented above C is given.

[0046] In the electrolytic cell system according to an exemplary and non-limiting embodiment, the data processing system 105 is configured to estimate the hydrogen H2 generation rate, for example, in mol / s, using the following formula.

[0047]

Number

[0048] In the above formula, z is the valence of hydrogen H2 = 2, and F is the Faraday constant 96485 C / mol. [Number 6] is the Faraday efficiency η in hydrogen generation F can be estimated using the current efficiency η C , and is based on the requirement that the hydrogen generation rate is proportional to the current η C I branch of the electrolytic cell stack 106.

[0049] In the electrolytic cell system according to an exemplary and non-limiting embodiment, the data processing system 105 is configured to calculate the specific energy consumption E s of the electrolytic cell 112, for example, in W / mol, according to the following formula.

[0050]

Number

[0051] The electrolysis cell system is a control system 108 that controls the DC voltage U supplied to the electrolysis cell 112 stack to optimize a quantity that depends on the estimated current efficiency η C of the electrolysis cell 112. For example, the DC voltage U stack can be charged in small steps as long as the optimization of the quantity becomes better or as long as other suitable optimization methods can be used. The quantity to be optimized can be, for example, the estimated current efficiency η C itself, or the specific energy consumption E according to [Equation 7] s , or other suitable quantities that depend on the estimated current efficiency η C .

[0052] FIG. 2 shows an electrolytic cell system according to an exemplary and non-limiting embodiment. The electrolytic cell system includes M electrolytic cell systems, three of which are illustrated in FIG. 2 with reference numerals 212a, 212b, and 212c. Each electrolytic cell can be, for example, like the electrolytic cell 112 shown in FIG. 1. The electrolytic cell system includes a controllable power supply, and the controllable power supply is configured to supply a controllable DC voltage to each of one of the electrolytic cells such that each electrolytic cell is supplied by one of the controllable power supplies. In FIG. 2, three of the controllable power supplies are illustrated with reference numerals 207a, 207b, and 207c. The electrolytic cell system includes a control system configured to control the DC voltage of each of the controllable power supplies. The DC voltage of each electrolytic cell is controlled to optimize a quantity that depends on the current efficiency of the electrolytic cell under consideration. The quantity to be optimized may be, for example, the current efficiency itself, the specific energy consumption of the electrolytic cell under consideration, or other suitable quantity that depends on the current efficiency. In this exemplary case, the control system includes dedicated controllers for the electrolytic cells, each configured to control one of the power supplies. In FIG. 2, three of the controllers are illustrated with reference numerals 208a, 208b, and 208c. In some cases, the control system may be implemented as a single central controller configured to control all of the controllable power supplies.

[0053] The electrolytic cell system has a current efficiency η of the electrolytic cell C,1 , …, η C,n , …, η C,MIt is provided with an estimation system for []. In this exemplary case, the estimation system includes a temperature sensor and a dedicated data processing system for the electrolytic cell for estimating the current efficiency of the electrolytic cell based on the measured temperature and the voltage and current supplied to the electrolytic cell. In FIG. 2, three of the data processing systems are illustrated with reference numerals 205a, 205b, and 205c. These data processing systems may each be of the kind shown, for example, as the data processing system 105 in FIG. 1. For example, the data processing system 205a receives the measured temperatures T0a_1, T1a_1, T0c_1, T1c_1, the data processing system 205b receives the measured temperatures T0a_n, T1a_n, T0c_n, T1c_n, and the data processing system 205c receives the measured temperatures T0a_M, T1a_M, T0c_M, T1c_M. The estimation system C,1 , …, η C_M can also be implemented as a single central processor configured to estimate.

[0054] In the electrolytic cell system shown in FIG. 2, the electrolytic cells can be individually controlled, and the operation of each electrolytic cell can be optimized independently of the other electrolytic cells. This improves the performance of the entire electrolytic cell system.

[0055] Each of the data processing systems 105, 205a - 205c and each of the controllers 108, 208a - 208c shown in FIGS. 1 and 2 may include one or more analog circuits, one or more digital processing circuits, or a combination thereof. Each digital processing circuit may be a programmable processing circuit with appropriate software, a dedicated hardware processor such as an ASIC, or a configurable hardware processor such as an FPGA. Further, each of the data processing systems and each of the controllers may include one or more memory circuits, and each of them may be, for example, a RAM circuit. Note that the data processing systems and controllers shown in FIGS. 1 and 2 are functional entities. These functional entities can be implemented in various ways. For example, these functional entities may be implemented to have separate hardware elements, or a single hardware element may be used to implement two or more of the functional entities, or, for example, the data processing system 105 and the control system 108 shown in FIG. 1 may be implemented to have the same hardware element or separate hardware elements.

[0056] FIG. 3 shows a flowchart of an exemplary and non - limiting estimation method for estimating the current efficiency η C of an electrolytic cell. This estimation method includes the following actions. Action 301. Measure the temperature of the electrolyte at the inlet of the electrolyte circulation section on the cathode side of the electrolytic cell, the temperature of the electrolyte at the outlet of the electrolyte circulation section on the cathode side of the electrolytic cell, the temperature of the electrolyte at the inlet of the electrolyte circulation section on the anode side of the electrolytic cell, and the temperature of the electrolyte at the outlet of the electrolyte circulation section on the anode side of the electrolytic cell. Action 302. Form an estimated value for the heat loss Q loss of the electrolytic cell based on a specific heat capacity C e of the electrolytic cell, the flow rate q ca of the electrolyte in the electrolyte circulation section on the cathode side, the flow rate q an of the electrolyte in the electrolyte circulation section on the anode side, the temperature difference ΔT ca between the outlet and the inlet of the electrolyte on the cathode side, and the temperature difference ΔT an between the outlet and the inlet of the electrolyte on the anode side. Action 303. Current efficiency η C The estimated value for is based on the difference between the power U stack ×I branch supplied to the electrolytic cell and the calculated estimated value of the heat loss Q loss of the electrolytic cell, and the product of the thermoneutral voltage N×U tn of the electrolytic cell of the electrolytic cell and the current I branch supplied to the electrolytic cell.

[0057] The estimation method according to an exemplary and non-limiting embodiment includes estimating the current efficiency η C as follows.

[0058]

Equation

[0059] In the above equation, U stack is the voltage across the electrolytic cell, I branch is the current supplied to the electrolytic cell, N is the number of series-connected electrolytic cells in the electrolytic cell, and U tn is the thermoneutral voltage of each of the electrolytic cells.

[0060] The estimation method according to an exemplary and non-limiting embodiment includes estimating the above thermoneutral voltage U tn as follows. In the following equation, T is the temperature of the electrolytic cell.

[0061]

Equation

[0062] The estimation method according to an exemplary and non-limiting embodiment includes estimating the temperature T of the electrolytic cell as a pre-determined mathematical function, for example, estimating it as the arithmetic mean of the electrolyte temperature values at the inlet and outlet on the cathode side and the temperature values at the inlet and outlet on the anode side.

[0063] The estimation method according to an exemplary and non-limiting embodiment includes calculating the heat loss Q of the electrolytic cell according to the following formula loss including.

[0064]

Number

[0065] In the above formula, C e is the specific heat capacity of the electrolyte, q ca is the flow rate of the electrolyte in the electrolyte circulation part on the cathode side, ΔT ca is the temperature difference between the outlet and the inlet on the cathode side, q an is the flow rate of the electrolyte in the electrolyte circulation part on the anode side, ΔT ca is the temperature difference between the outlet and the inlet on the anode side, and k is a constant.

[0066] The estimation method according to an exemplary and non-limiting embodiment includes calculating the heat loss Q of the electrolytic cell according to the following formula loss including.

[0067]

Number

[0068] In the above formula, C e_ca is the specific heat capacity of the electrolyte on the cathode side, that is, the specific heat capacity of the cathode liquid, and C e_an is the specific heat capacity of the electrolyte on the anode side, that is, the specific heat capacity of the anode liquid.

[0069] The estimation method according to an exemplary and non-limiting embodiment is suitable for controlling an electrolytic cell system, and the electrolytic cell system includes one or more electrolytic cells each including an electrolytic cell stack having an electrolytic cell containing an electrolyte, one or more controllable power supplies, each configured to supply a controllable DC voltage to one of the electrolytic cells such that each electrolytic cell is powered by one of the controllable power supplies.

[0070] The above control method performs an estimation method according to an exemplary and non - limiting embodiment for estimating the current efficiency of each electrolytic cell, and controls the DC voltage of each controllable power supply so as to optimize a quantity that depends on the estimated current efficiency of the electrolytic cells powered by the controllable power supplies considered.

[0071] The control method according to an exemplary and non - limiting embodiment includes calculating the specific energy consumption of each electrolytic cell according to the following formula [Equation 12], and controlling the DC voltage of each controllable power supply so as to minimize the specific energy consumption of the electrolytic cells powered by the controllable power supplies.

[0072]

Number

[0073] In the above formula, E s,n is the specific energy consumption of the n - th electrolytic cell, U stack,n is the controllable DC voltage supplied to the n - th electrolytic cell, I branch,n is the current supplied to the n - th electrolytic cell, η C,n is the estimated current efficiency of the n - th electrolytic cell, z is the valence of hydrogen H2 = 2, and F is the Faraday constant 96485 C / mol.

[0074] The computer program according to an exemplary and non - limiting embodiment includes computer - executable instructions for controlling a programmable data - processing system to perform actions related to the estimation method and / or control method according to the above - mentioned exemplary and non - limiting embodiments.

[0075] A computer program according to an illustrative and non - limiting embodiment includes a software module for estimating the current efficiency of an electrolytic cell. This software module includes computer - executable instructions that control a programmable processor to receive temperature values indicating the temperature of the electrolyte at the inlet of the electrolyte circulation section on the cathode side of the electrolytic cell, the temperature of the electrolyte at the outlet of the electrolyte circulation section on the cathode side of the electrolytic cell, the temperature of the electrolyte at the inlet of the electrolyte circulation section on the anode side of the electrolytic cell, and the temperature of the electrolyte at the outlet of the electrolyte circulation section on the anode side of the electrolytic cell, form an estimated value of the heat loss of the electrolytic cell based on the specific heat capacity of the electrolyte, the flow rate of the electrolyte in the electrolyte circulation section on the cathode side, the flow rate of the electrolyte in the electrolyte circulation section on the anode side, the temperature difference of the electrolyte between the outlet and the inlet on the cathode side, and the temperature difference of the electrolyte between the outlet and the inlet on the anode side, calculate an estimated value of the current efficiency based on the difference between the power supplied to the electrolytic cell and the calculated estimated value of the heat loss of the electrolytic cell, and the product of the thermoneutral voltage of the electrolytic cell and the current supplied to the electrolytic cell.

[0076] The above - mentioned software module can be a subroutine or function implemented using an appropriate programming language.

[0077] A computer program according to an illustrative and non - limiting embodiment includes a software module for controlling an electrolytic cell system, and the software module one or more electrolytic cells each including an electrolytic cell stack having an electrolytic cell containing an electrolyte, one or more controllable power sources, each configured to supply a controllable DC voltage to one of the electrolytic cells such that each electrolytic cell is powered by a controllable power source.

[0078] The software module of the computer program for controlling the above - mentioned electrolytic cell system A software module of a computer program according to an exemplary and non - limiting embodiment for estimating the current efficiency of each electrolytic cell in an electrolytic cell system, computer - executable instructions for controlling a programmable data processing system to control the DC voltage of each of one or more power sources and to optimize a quantity that depends on the estimated current efficiency of an electrolytic cell powered by a controllable power source being considered,

[0079] A computer program product according to an exemplary and non - limiting embodiment includes a non - transitory computer - readable medium, such as a compact disc "CD", encoded with a computer program according to an embodiment of the present invention.

[0080] A signal according to an exemplary and non - limiting embodiment is encoded to carry information defining a computer program according to an embodiment of the present invention. In this exemplary case, the computer program may be downloadable from a server, which may form part of, for example, a cloud service.

[0081] The specific examples provided in the above description should not be construed as limiting the applicability and / or interpretation of the appended claims. The lists and groups of examples provided in the above description are not exclusive unless expressly stated otherwise.

Claims

1. An estimation system for estimating the current efficiency (η Ｃ ) of an electrolytic cell (112, 212a - 212c), wherein the estimation system includes a temperature sensor (101 - 104) at an inlet of an electrolyte circulation section on the cathode side of the electrolytic cell, an outlet of the electrolyte circulation section on the cathode side of the electrolytic cell, an inlet of an electrolyte circulation section on the anode side of the electrolytic cell, and an outlet of the electrolyte circulation section on the anode side of the electrolytic cell. In the estimation system, the estimation system includes a data processing system (105, 205a - 205c), and the data processing system The estimated value of the heat loss (Q ｌｏｓｓ ) of the electrolytic cell is calculated based on the specific heat capacity (C ｅ , C ｅ＿ｃａ , C ｅ＿ａｎ ) of the electrolyte, the flow rate (q ｃａ ) of the electrolyte in the electrolyte circulation part on the cathode side, the flow rate (q ａｎ ) of the electrolyte in the electrolyte circulation part on the anode side, the temperature difference (ΔT ｃ ) of the electrolyte between the outlet and the inlet on the cathode side, and the temperature difference (ΔT ａ ) of the electrolyte between the outlet and the inlet on the anode side, and The estimated value of the current efficiency (η Ｃ ) is calculated based on the difference between the calculated estimated value of the power supplied to the electrolytic cell (U ｓｔａｃｋ × I ｂｒａｎｃｈ ) and the heat loss (Q ｌｏｓｓ ) of the electrolytic cell, and the product of the thermoneutral voltage (N × U ｔｎ ) of the electrolytic cell of the electrolytic cell and the current (I ｂｒａｎｃｈ ) supplied to the electrolytic cell. The estimation system is characterized by being configured as such.

2. The data processing system is, 【Number 1】 in accordance with which the current efficiency (η Ｃ ) is configured to be estimated, U ｓｔａｃｋ is the voltage across the electrolytic cell, I ｂｒａｎｃｈ is the current supplied to the electrolytic cell, N is the number of electrolytic cells connected in series in the electrolytic cell, and U ｔｎ is the thermal neutral voltage of each of the electrolytic cells, the estimation system according to claim 1.

3. The data processing system is, 【Number 2】 According to, the thermoneutral voltage (U ｔｎ ) is configured to be estimated, The estimation system according to claim 1 or 2, wherein T is the temperature of the electrolytic cell.

4. The estimation system according to claim 3, wherein the data processing system is configured to calculate the temperature of the electrolytic cell as a predetermined mathematical function of the temperature value given by the temperature sensor.

5. The data processing system is, [Number 3] According to, the heat loss (Q ｌｏｓｓ ) of the electrolytic cell is configured to be calculated, C ｅ＿ｃａ is the specific heat capacity of the electrolyte on the cathode side, C ｅ＿ａｎ is the specific heat capacity of the electrolyte on the anode side, q ｃａ is the flow rate of the electrolyte in the electrolyte circulation section on the cathode side, ΔT ｃ is the temperature difference between the outlet and the inlet on the cathode side, q ａｎ is the flow rate of the electrolyte in the electrolyte circulation section on the anode side, ΔT ａ is the temperature difference between the outlet and the inlet on the anode side, and k is a constant. The estimation system according to any one of claims 1 to 4.

6. An electrolytic cell system, comprising: one or more electrolytic cells (112, 212a - 212c), each of which comprises an electrolytic cell stack (106, 206a - 206c) having an electrolytic cell containing an electrolyte; One or more controllable power supplies (107, 207a - 207c), each configured to supply a controllable DC voltage (U ｓｔａｃｋ，ｎ ) to one of the electrolytic cells such that each of the electrolytic cells is powered using one of the controllable power supplies, and one or more controllable power supplies (107, 207a - 207c). A control system (108, 208a - 208c) that controls the DC voltage of each of the one or more controllable power supplies to optimize a quantity that depends on the current efficiency (η Ｃ ) of the electrolytic cell powered by the controllable power supply, and a control system (108, 208a - 208c) configured as such, in an electrolytic cell system. The electrolytic cell system includes the estimation system according to any one of claims 1 to 5 for estimating the current efficiency (η Ｃ ) of each of the electrolytic cells.

7. The data processing system of the estimation system is configured to calculate a specific energy consumption associated with each of the electrolytic cells according to [Equation 4], and the control system controls the DC voltage (U ｓｔａｃｋ，ｎ ) of each of the controllable power supplies to minimize the specific energy consumption associated with the electrolytic cells powered by the controllable power supplies. 【Number 4】 and, E ｓ，ｎ is the specific energy consumption of the n-th electrolytic cell among the electrolytic cells, U ｓｔａｃｋ，ｎ is the controllable DC voltage supplied to the n-th electrolytic cell among the electrolytic cells, I ｂｒａｎｃｈ，ｎ is the current supplied to the n-th electrolytic cell among the electrolytic cells, η Ｃ，ｎ is the current efficiency of the n-th electrolytic cell among the electrolytic cells, z is the valence of hydrogen H ２ = 2, and F is the Faraday constant 96485 C / mol. The electrolytic cell system according to claim 6.

8. Estimation method for estimating the current efficiency (η Ｃ ) of an electrolytic cell, wherein the estimation method comprises: In an estimation method, the method includes measuring (301) the temperature (T0c) of the electrolyte at the inlet of the electrolyte circulation part on the cathode side of the electrolytic cell, the temperature (T1c) of the electrolyte at the outlet of the electrolyte circulation part on the cathode side of the electrolytic cell, the temperature (T0a) of the electrolyte at the inlet of the electrolyte circulation part on the anode side of the electrolytic cell, and the temperature (T1a) of the electrolyte at the outlet of the electrolyte circulation part on the anode side of the electrolytic cell. The estimation method is, A data processing system determines a specific heat capacity (C ｅ , ｅ＿ｃａ , C ｅ＿ａｎ ) of the electrolyte, a flow rate (q ｃａ ) of the electrolyte in the electrolyte circulation section on the cathode side, a flow rate (q ａｎ ) of the electrolyte in the electrolyte circulation section on the anode side, a temperature difference (ΔT ｃａ ) of the electrolyte between the outlet and the inlet on the cathode side, a temperature difference (ΔT ａｎ ) of the electrolyte between the outlet and the inlet on the anode side, and forms an estimated value (302) for heat loss (Q ｌｏｓｓ ) of the electrolytic cell based thereon. Based on the difference between the estimated value of the power (U ｓｔａｃｋ × I ｂｒａｎｃｈ ) supplied to the electrolytic cell by the data processing system and the calculated estimated value of the heat loss (Q ｌｏｓｓ ) of the electrolytic cell, and the product of the thermoneutral voltage (N × U ｔｎ ) of the electrolytic cell and the current (I ｂｒａｎｃｈ ) supplied to the electrolytic cell, forming an estimated value for the current efficiency (η Ｃ ) (303), the estimation method is characterized by including this.

9. The estimation method is, 【Number 5】 According to, the current efficiency (η Ｃ ) is estimated, and U ｓｔａｃｋ is the voltage across the electrolytic cell, I ｂｒａｎｃｈ is the current supplied to the electrolytic cell, N is the number of electrolytic cells connected in series in the electrolytic cell, and U ｔｎ is the thermoneutral voltage of each of the electrolytic cells, the estimation method according to claim 8.

10. The estimation method is, 【Number 6】 According to, estimating the thermoneutral voltage (U ｔｎ ), and including The estimation method according to claim 8 or 9, wherein T is the temperature of the electrolytic cell.

11. The estimation method according to claim 10, wherein the method includes estimating the temperature of the electrolytic cell as a predetermined mathematical function of the temperature values of the electrolyte at the inlet and outlet on the cathode side and the inlet and outlet on the anode side.

12. The estimation method is, 【Number 7】 According to, the heat loss (Q ｌｏｓｓ ) of the electrolytic cell is calculated, and C ｅ＿ｃａ is the specific heat capacity of the electrolyte on the cathode side, C ｅ＿ａｎ is the specific heat capacity of the electrolyte on the anode side, q ｃａ is the flow rate of the electrolyte in the electrolyte circulation section on the cathode side, ΔT ｃａ is the temperature difference between the outlet and the inlet on the cathode side, q ａｎ is the flow rate of the electrolyte in the electrolyte circulation section on the anode side, ΔT ｃａ is the temperature difference between the outlet and the inlet on the anode side, and k is a constant. The estimation method according to any one of claims 8 to 11.

13. A control method for controlling an electrolytic cell system, the electrolytic cell system comprising: one or more electrolytic cells (112, 212a - 212c), each of which comprises an electrolytic cell stack (106, 206a - 206c) having an electrolytic cell containing an electrolyte;

14. One or more controllable power supplies (107, 207a - 207c), each configured to supply a controllable DC voltage (U ｓｔａｃｋ，ｎ ) to one of the electrolytic cells such that each of the electrolytic cells is powered by one of the controllable power supplies, and one or more controllable power supplies (107, 207a - 207c). The control method includes controlling, by a control system, the DC voltage of each of the one or more controllable power supplies to optimize a quantity that depends on the current efficiency (η Ｃ ) of the electrolytic cell powered by the controllable power supply. In the control method, the control method includes executing the estimation method according to any one of claims 8 to 12 for estimating the current efficiency (η Ｃ ) of each of the electrolytic cells. A control method characterized by this. and, The control method calculates, according to [Equation 8], the specific energy consumption of each of the electrolytic cells, and controls the DC voltage (U ｓｔａｃｋ，ｎ ) of each of the controllable power supplies to minimize the specific energy consumption of the electrolytic cells powered by the controllable power supplies, and includes: 【Number 8】

15. E ｓ，ｎ is the specific energy consumption of the n-th electrolytic cell among the electrolytic cells, U ｓｔａｃｋ，ｎ is the controllable DC voltage supplied to the n-th electrolytic cell among the electrolytic cells, I ｂｒａｎｃｈ，ｎ is the current supplied to the n-th electrolytic cell among the electrolytic cells, η Ｃ，ｎ is the current efficiency of the n-th electrolytic cell among the electrolytic cells, z is the valence of hydrogen H ２ = 2, and F is the Faraday constant 96485 C / mol. The control method according to claim 13. ​ Computer program for estimating the current efficiency (η Ｃ ) of an electrolytic cell, wherein the computer program is computer-executable instructions for controlling a programmable data processing system, In a computer program including computer-executable instructions for receiving temperature values indicating the temperature (T0c) of the electrolyte at the inlet of the electrolyte circulation section on the cathode side of the electrolytic cell, the temperature (T1c) of the electrolyte at the outlet of the electrolyte circulation section on the cathode side of the electrolytic cell, the temperature (T0a) of the electrolyte at the inlet of the electrolyte circulation section on the anode side of the electrolytic cell, and the temperature (T1a) of the electrolyte at the outlet of the electrolyte circulation section on the anode side of the electrolytic cell. The computer program is computer-executable instructions for controlling the programmable data processing system, The specific heat capacity (C ｅ , ｅ＿ｃａ , C ｅ＿ａｎ ) of the electrolyte, the flow rate (q ｃａ ) of the electrolyte in the electrolyte circulation section on the cathode side, the flow rate (q ａｎ ) of the electrolyte in the electrolyte circulation section on the anode side, the temperature difference (ΔT ｃａ ) of the electrolyte between the outlet and the inlet on the cathode side, and the temperature difference (ΔT ａｎ ) of the electrolyte between the outlet and the inlet on the anode side are used to form an estimated value of the heat loss (Q ｌｏｓｓ ) of the electrolytic cell, and The power (U ｓｔａｃｋ × I ｂｒａｎｃｈ ) supplied to the electrolytic cell and the difference between the calculated estimated value of the heat loss (Q ｌｏｓｓ ) of the electrolytic cell, and the product of the thermoneutral voltage (N × U ｔｎ ) of the electrolytic cell of the electrolytic cell and the current (I ｂｒａｎｃｈ ) supplied to the electrolytic cell, are used to calculate an estimated value for the current efficiency (η Ｃ ). A computer program characterized by including computer-executable instructions.

16. A computer program for controlling an electrolytic cell system, the electrolytic cell system comprising: One or more electrolytic cells (212a - 212c), each comprising an electrolytic cell stack (106, 206a - 206c) having an electrolytic cell containing an electrolyte. One or more controllable power sources (207a - 207c), each of the electrolytic cells being configured to be supplied with a controllable DC voltage (U ｓｔａｃｋ，ｎ ) by using one of the controllable power sources, and one or more controllable power sources (207a - 207c) each configured to supply power in this way. The computer program controls the DC voltage (U ｓｔａｃｋ，ｎ ) of each of the one or more controllable power supplies to optimize a quantity that depends on the current efficiency (η Ｃ ) of the electrolytic cell powered by the controllable power supply, and includes computer-executable instructions for controlling a programmable data processing system. In the computer program, the computer program for controlling the electrolytic cell system includes the computer program according to claim 15 for estimating the current efficiency (η Ｃ ) of each of the electrolytic cells. A computer program, characterized by this.

17. A non-transitory computer-readable medium encoded with the computer program according to claim 15 or 16.

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