Energy-saving control method and system of capacitive deionization equipment and medium

Abstract

The invention discloses an energy-saving control method and system for capacitive deionization equipment and a medium, and the method comprises the steps: building a dynamic equivalent circuit for the capacitive deionization equipment which comprises a DC / DC converter and two CDI devices, setting the capacitance value of an equivalent electric double-layer capacitor, the resistance value of an equivalent parallel resistor and the initial value of an equivalent series resistor of the CDI devices, and establishing a correction model of the equivalent series resistance when the conductivity of the electrolyte solution changes in the energy recovery process, integrating the correction model of the equivalent series resistance and the charge-discharge rate and ohmic loss of the electric double-layer capacitor of the CDI equipment in the energy recovery process, and obtaining the reference current required by the DC / DC converter for energy recovery control by using the dynamic equivalent circuit. The invention aims to solve the problem that energy loss caused by the change of solution conductivity is not considered in the energy recovery process of the traditional capacitive deionization equipment, and the energy recovery efficiency is improved, the system operation energy consumption is reduced and efficient energy recovery is realized by dynamically optimizing the energy transmission process.

Description

Technical Field

[0001] The present invention relates to the technical field of water treatment, and in particular to an energy-saving control method, system and medium for capacitor deionization equipment. Background Art

[0002] Capacitive deionization (CDI), also known as electrosorption technology, can be used for the treatment of seawater, sewage and wastewater. Electrosorption technology drives the ions in the solution to migrate toward the oppositely charged electrode by applying a stable external electric field, and temporarily stores the ions in the electrical double layer (EDL) formed on the electrode surface and the micropores of the porous electrode. In this process, the flow of the solution purifies the water quality, thereby obtaining fresh water with a low salt concentration. When the double layer adsorption reaches saturation, disconnect the external power supply, reverse the power supply or short-circuit the two ends of the electrode to desorb, so that the adsorbed ions return to the main body of the solution again, and flow out of the CDI equipment with the flow of the solution to obtain concentrated water with a high salt concentration.

[0003] It is worth noting that a key feature of electrosorption technology is that it has a supercapacitor-like energy storage capacity, allowing the use of double-layer energy storage during the desalination process and recovery during the desorption stage. During the adsorption process of the CDI device, most of the input energy of the applied external electric field will be stored in the double layer formed at the interface between the electrode and the solution. As the adsorption proceeds, the number of ions accumulated on the double layer formed increases. The adsorption process can also be equivalent to the process of charging the double-layer capacitor. During the desorption process of the CDI device, ions return from the double layer of the interface and the micropores of the porous electrode to the middle flow channel, and the double layer formed at the interface of the electrode and the solution gradually disappears. It can be equivalent to the discharge of the formed double-layer capacitor. Existing experimental studies have shown that under the condition of formulating a reasonable membrane capacitive deionization (MCDI) unit energy recovery plan, the energy recovery rate for capacitor charging can reach 83%, and the energy recovery rate of the CDI unit can reach 62.1%. Recovering the energy released by the CDI device during the desorption process will directly improve the energy efficiency of the CDI device. Before the introduction of DC / DC (direct current) converters, the energy recovery process of CDI equipment is often difficult to control. When energy is transferred from one CDI series unit to another, the transferred current may be too large in an instant, causing system instability and even permanent damage to the equipment and electrodes. In addition, when the voltages of the two CDI devices reach the same level, the energy transfer will automatically stop, making the desalination process unable to continue, resulting in energy waste. To overcome the above problems, the introduction of DC / DC converters can accurately control the energy recovery and transfer process, which not only avoids the problem of excessive current, but also maintains effective energy transfer under different voltage conditions.

[0004] Existing studies have not proposed a comprehensive adjustment strategy for the reference current, so that the adjustment of the reference current cannot fully reflect the actual needs of the energy recovery process, which leads to unstable energy recovery efficiency and the possibility of causing large energy losses. Existing studies usually discuss the energy recovery rate, loss distribution and energy recovery rate experimental results under different working conditions using different reference currents. When mentioning the method of dynamically adjusting the reference current, it only focuses on achieving the evaluation and calculation of a certain performance indicator, and has not proposed an adjustment strategy that takes into account both the energy recovery rate and the recovery efficiency. This means that under different working conditions, the adjustment of the reference current often cannot fully reflect the actual needs of the energy recovery process, resulting in unstable energy recovery efficiency and possible large losses. Summary of the invention

[0005] Technical problem to be solved by the present invention: In view of the above-mentioned problems in the prior art, an energy-saving control method, system and medium for capacitor deionization equipment are provided. The present invention aims to solve the problem of energy loss caused by changes in solution conductivity that are not taken into account in the energy recovery process of traditional capacitor deionization equipment, and to improve energy recovery efficiency by dynamically optimizing the energy transmission process, reduce system operating energy consumption, and achieve efficient energy recovery.

[0006] In order to solve the above technical problems, the technical solution adopted by the present invention is: A method for energy saving control of capacitor deionization equipment comprises the following steps: S1, establishing a dynamic equivalent circuit for a capacitor deionization equipment including a DC / DC converter and two CDI devices, wherein each CDI device is equivalent to an equivalent double-layer capacitor, an equivalent parallel resistor and an equivalent series resistor, the equivalent parallel resistor and the equivalent double-layer capacitor are connected in parallel and then connected in series with the equivalent series resistor, the DC / DC converter is equivalent to an inductor L, a sensor resistor Rsensor, two equivalent power electronic switches and a controller, one end of the two CDI devices is directly connected and the other end is connected through two equivalent power electronic switches, the series branch formed by the inductor L and the sensor resistor Rsensor is connected in parallel between the loops of the two CDI devices, and the control ends of the two equivalent power electronic switches are connected to the controller; S2, setting the capacitance value of the equivalent double-layer capacitor, the resistance value of the equivalent parallel resistor and the initial value of the equivalent series resistor of the CDI device, and establishing a correction model of the equivalent series resistor when the conductivity of the electrolyte solution changes during the energy recovery process; S3, combining the correction model of equivalent series resistance and the charge and discharge rate and ohmic loss of the double-layer capacitor of the CDI device during the energy recovery process, and using the dynamic equivalent circuit to obtain the reference current required for the DC / DC converter to perform energy recovery control; The functional expression of the correction model of the equivalent series resistance in step S2 is: , in, For the The equivalent series resistance of CDI devices in this round The correction value of For the The initial value of the equivalent parallel resistance of each CDI device, is the distance between the electrodes of the CDI device, is the electrode surface area of ​​the CDI device, For the The initial electrolyte solution conductivity of each CDI device, For the CDI equipment in this round The conductivity of the electrolyte solution.

[0007] Optionally, step S3 includes: S3.1, Initialize iteration variables =1, detect and obtain the initial voltage of the desorption and energy release CDI device and electrolyte solution conductivity , and the initial voltage of the adsorption energy CDI device and electrolyte solution conductivity ; S3.2, calculation of this round Reference current : , in, is the initial voltage value of the desorption and energy release CDI device, is the double-layer capacitance value of the desorption energy release CDI device, The expected duration of the energy recovery project; S3.3, use this round Reference current Control DC / DC converter in this round Cycle Perform energy recovery operation within; detect and obtain this round Cycle The parameters at the end include: desorption and energy release of CDI equipment in this round Voltage and electrolyte solution conductivity , and adsorption energy CDI equipment in this round Voltage and electrolyte solution conductivity ; If the desorption energy release CDI equipment is Voltage If the value is less than the preset threshold, the process ends and exits; otherwise, the process jumps to step S3.5; S3.4, according to this round Cycle Parameter calculation at the end of this round Ohmic loss Ideal voltage for CDI equipment ; S3.5, if this round Ohmic loss Greater than or equal to the previous round Ohmic loss , then reduce the current round Reference current To get the next round Reference current ; If this round Ohmic loss Less than the previous round Ohmic loss , and desorption and energy release CDI equipment in this round Voltage Less than the ideal voltage for desorption and energy release CDI equipment , then reduce the current round Reference current To get the next round Reference current ; If this round Ohmic loss Less than the previous round Ohmic loss , and desorption and energy release CDI equipment in this round Voltage Greater than or equal to the ideal voltage of the desorption and energy release CDI equipment , then increase this round Reference current To get the next round Reference current ; Iterate over the variable Add 1 and jump to step S3.3.

[0008] Optionally, in step S3.4, this round n Ohmic loss The calculation function expression is: , in, and The equivalent series resistance of the desorption energy release CDI equipment and the adsorption energy use CDI equipment is The loss value, and The equivalent parallel resistance of the desorption energy release CDI equipment and the adsorption energy use CDI equipment in this round The loss value, and They are the capacitance values ​​of the double-layer capacitors of the desorption energy-releasing CDI equipment and the adsorption energy-using CDI equipment, respectively. and They are desorption energy release CDI equipment and adsorption energy use CDI equipment. The voltage is: , , in, For the The equivalent series resistance of CDI devices in this round The loss value, For this round The reference current, For the The equivalent series resistance of CDI devices in this round n The correction value of To adjust the interval time parameters, For the The equivalent parallel resistance of CDI devices in this round The loss value, For the CDI equipment in this round The voltage, The value is 1 or 2. When it is 1, it means desorption and energy release CDI equipment, When it is 2, it indicates adsorption energy CDI equipment.

[0009] Optionally, in step S3.4, this round n The ideal voltage for desorption and release of CDI equipment The calculation function expression is: , in, For the previous round n- 1 Ideal voltage for desorption and energy release CDI equipment, For this round n The reference current, To adjust the interval time parameters, It is the capacitance value of the double-layer capacitor of the desorption energy-releasing CDI device.

[0010] Optionally, in step S3.5, the current round is reduced Reference current To get the next round Reference current The function expression is: , in, An adjustment scale factor less than 1.

[0011] Optionally, in step S3.5, the current round is increased Reference current To get the next round Reference current The function expression is: , in, An adjustment scale factor less than 1.

[0012] In addition, the present invention also provides an energy-saving control system for capacitive deionization equipment, comprising a microprocessor and a memory connected to each other, wherein the microprocessor is programmed or configured to execute the energy-saving control method for the capacitive deionization equipment.

[0013] In addition, the present invention also provides a computer-readable storage medium, in which a computer program or instruction is stored. The computer program or instruction is programmed or configured to execute the energy-saving control method of the capacitive deionization equipment through a processor.

[0014] In addition, the present invention also provides a computer program product, including a computer program or instructions, wherein the computer program or instructions are programmed or configured to execute the energy-saving control method of the capacitive deionization equipment through a processor.

[0015] Compared with the prior art, the present invention mainly has the following advantages: the method of the present invention includes establishing a correction model of the equivalent series resistance when the conductivity of the electrolyte solution changes during the energy recovery process, integrating the dynamic change characteristics of the electrolyte conductivity, and comprehensively considering the charging and discharging rate and ohmic loss of the double-layer capacitor of the CDI equipment during the energy recovery process. The reference current required for the DC / DC converter to perform energy recovery control is obtained by using a dynamic equivalent circuit. The energy loss problem caused by the change in solution conductivity that is not considered during the energy recovery process of traditional capacitor deionization equipment can be solved, and the energy recovery efficiency can be improved by dynamically optimizing the energy transmission process, reducing the system operation energy consumption, and achieving efficient energy recovery. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 Schematic diagram of the basic flow of the method of the embodiment of the present invention.

[0017] Figure 2 It is a schematic diagram of the structure of the capacitive deionization equipment in an embodiment of the present invention.

[0018] Figure 3 Schematic diagram of the circuit principle of the dynamic equivalent circuit in the embodiment of the present invention.

[0019] Figure 4 Schematic diagram of the process of energy recovery control in an embodiment of the present invention.

[0020] Figure 5 is the inductor current of the DC / DC converter in the embodiment of the present invention Schematic diagram of the curve.

[0021] Figure 6 Schematic diagram of the change of the solution concentration at the outlet of the CDI equipment in three schemes in the embodiments of the present invention.

[0022] Figure 7It is a comparison chart of the results of four indicators, namely, energy recovery time, ion removal amount, ion removal rate, and energy recovery rate, of the three schemes in the embodiment of the present invention. DETAILED DESCRIPTION

[0023] The present invention aims to take into account the influence of changes in electrolyte solution concentration on energy loss during the energy recovery process of CDI (Capacitive Deionization) equipment, dynamically control and optimize the reference current size in the DC / DC converter, and achieve more efficient energy recovery. The existing method guides the adjustment of the DC / DC converter reference current by electrical modeling of the CDI device, but does not consider the influence of changes in solution concentration on ion loss and resistance, and uses fixed equivalent values ​​for calculation. This approach results in inaccurate adjustment of the reference current, which may cause distortion of the energy recovery efficiency and cause energy waste. In order to enable those skilled in the art to better understand the technical solution of the present invention, the technical solution of the present invention will be further described in detail below in conjunction with the drawings in the embodiments of the present invention.

[0024] like Figure 1 As shown, the energy-saving control method of the capacitor deionization equipment in this embodiment includes the following steps: S1, establish a dynamic equivalent circuit for a capacitive deionization setup consisting of a DC / DC converter and two CDI devices.

[0025] S2, setting the capacitance value of the equivalent double-layer capacitor, the resistance value of the equivalent parallel resistor and the initial value of the equivalent series resistor of the CDI device, and establishing a correction model of the equivalent series resistor when the conductivity of the electrolyte solution changes during the energy recovery process; S3, a modified model of equivalent series resistance and the charge and discharge rate and ohmic loss of the double-layer capacitor of the CDI device during the energy recovery process are integrated, and a dynamic equivalent circuit is used to obtain the reference current required for the DC / DC converter to perform energy recovery control.

[0026] like Figure 2As shown, the capacitive deionization equipment of this embodiment includes a DC / DC converter and two CDI devices. Raw water is respectively sent to the two CDI devices through water pumps. One of the two CDI devices is used as a desorption and energy-releasing CDI device, and the other is used as an adsorption and energy-using CDI device. The raw water is processed by the desorption and energy-releasing CDI device to obtain concentrated water with a higher ion concentration than the raw water, and directionally moving electrons are generated and sent to the DC / DC converter. Under the action of the DC / DC converter, a reference current is generated and applied to the electrodes of the adsorption and energy-using CDI device to generate a potential difference so as to process the raw water flowing into the adsorption and energy-using CDI device to obtain fresh water with a lower ion concentration than the raw water. The double electric layer formed at the interface between the electrode and the solution in the desorption energy-releasing CDI device gradually disappears, and the ions return to the middle flow channel from the double electric layer at the interface and the micropores of the porous electrode, driving the metal collector plate to generate directionally moving electrons to supply the DC / DC buck-boost converter device. Under the action of the DC / DC buck-boost converter device, the output reference current is applied to the electrodes of the adsorption energy-releasing CDI device, thereby generating a certain potential difference between its electrodes. The adsorption energy-releasing CDI device begins to adsorb ions in the solution and stores most of the input energy in the double electric layer formed at the interface between the electrode and the solution.

[0027] During the operation of the multi-capacitor deionization equipment, one end of the desorption and energy release CDI equipment and the adsorption and energy use CDI equipment are both fed with raw water to be treated, and the other end treated by the desorption and energy release CDI equipment will obtain concentrated water with a higher ion concentration than the raw water, and the other end treated by the adsorption and energy use CDI equipment will obtain fresh water with a lower ion concentration than the raw water. The capacitor deionization equipment may further include a raw water storage tank, an electric pump, a concentrated water storage tank and a fresh water storage tank. The raw water stored in the raw water storage tank is fed into the two CDI equipments by an electric pump. The outlet of the desorption and energy release CDI equipment in the two CDI equipments is connected to the concentrated water storage tank, and the outlet of the adsorption and energy use CDI equipment is connected to the fresh water storage tank. The raw water, concentrated water and fresh water are stored in different storage tanks, and an electric pump is used to pump the solution into the desorption and energy release CDI equipment and the adsorption and energy use CDI equipment. In this embodiment, the DC / DC converter is composed of two power electronic switches connected in series.

[0028] Figure 3 FIG. 2 is a schematic diagram of the circuit principle of the dynamic equivalent circuit in this embodiment. Figure 3As shown, the dynamic equivalent circuit of the capacitor deionization system containing the buck-boost converter established in this embodiment includes: an equivalent circuit of a CDI device that is desorbing and releasing energy, an equivalent circuit of a CDI device that is absorbing and using energy, and an equivalent circuit of a DC / DC converter. Among them, the test methods of the equivalent circuit configuration and parameters when the capacitor deionization device is desorbing and releasing energy or absorbing and using energy are consistent, except that the capacitor deionization devices are differentiated in their working states, one of which belongs to equivalent discharge and the other to equivalent charging. The parameter values ​​of the capacitor deionization equivalent circuit components should be obtained based on the performance differences of the equipment itself and the operating conditions. Figure 3 The parameters of the equivalent circuit components of the desorption and energy release CDI module are marked with the subscript number 1, and the parameters of the equivalent circuit components of the adsorption and energy use CDI module are marked with the subscript number 2. In the dynamic equivalent circuit of this embodiment, each CDI device is equivalent to an equivalent double-layer capacitor, an equivalent parallel resistor and an equivalent series resistor. The equivalent parallel resistor and the equivalent double-layer capacitor are connected in parallel and then connected in series with the equivalent series resistor. This equivalent circuit model is widely used in the performance evaluation of CDI equipment, energy recovery efficiency analysis, and system optimization research due to its reasonable simplification of real complex circuit parameters and high generalization of CDI system behavior. Among them, the equivalent series resistor in the capacitor deionization equivalent circuit is a key time-varying parameter in the energy recovery optimization process. It is used to equalize the various constant resistances or stable resistances generated by the equipment circuit wires and their connection points, the contact between the collector and the electrode porous medium in the operation of the CDI equipment, and the ion resistance of the directional migration of ions in the electrolyte solution under the action of the electric field. This value should be corrected in real time with the energy recovery. The equivalent parallel resistance is used to equalize the non-ideal behavior in the actual system, such as leakage on the double-layer capacitor. This value can be regarded as a constant in the process of energy recovery. The equivalent double-layer capacitor is used for the charge distribution and storage capacity between the electrode and the solution. Its value describes the charge storage characteristics at the interface between the electrode and the electrolyte. It is also the specific equivalent element of the specific effect of the CDI device on the adsorption of ions in the solution. This value can be regarded as a constant in the process of energy recovery. The current input or output on the double-layer capacitor is called the double-layer current. Without considering more complex ion effects and losses, the amount of charge transferred by the double-layer current can be approximated by Faraday's law to obtain the number of ions adsorbed by the CDI device (Faraday's law is: ,in: is the amount of charge transferred by the double layer current, unit, coulomb; is the number of ions adsorbed by the CDI device, in moles; is the Faraday constant, approximately 96485, unit, coulomb per mole).

[0029] In this embodiment, the DC / DC converter is equivalent to a bidirectional buck-boost step-up / down circuit, which includes an inductor L, a sensor resistor Rsensor, two equivalent power electronic switches (MOSFET 1 and MOSFET 2) and a controller. One end of the two CDI devices is directly connected, and the other end is connected through two equivalent power electronic switches. The series branch formed by the inductor L and the sensor resistor Rsensor is connected in parallel between the loops of the two CDI devices, and the control ends of the two equivalent power electronic switches are connected to the controller; when the capacitor deionization system recovers energy, one of the capacitor deionization devices desorbs and releases energy, and the other capacitor deionization device absorbs and uses energy, and transfers energy through the buck-boost step-up / down circuit. In addition to MOSFET, the power electronic switch can also use IGBT. The test method of the equivalent circuit parameters of the capacitor deionization device when desorbing energy or adsorbing energy is the same, except that the capacitor deionization device is distinguished in the working state, one of which belongs to equivalent discharge and the other belongs to equivalent charging, and the parameter values ​​of the capacitor deionization equivalent circuit components vary according to the differences in the equipment itself and the operating conditions. In the energy transfer process, the DC / DC buck-boost converter uses a feedback control system (such as a PID controller) to adjust the switching frequency and duty cycle, thereby adjusting the relationship between the input voltage and the output voltage in real time. In this embodiment, the controller controls the switching state of MOSFET1 and MOSFET2 by outputting a PWM signal generated by the PID controller to ensure that the current through the inductor L is close to the set reference current value, and then controllably adjusts the transfer current size of the CDI device when recovering energy. The bidirectional buck-boost buck-boost circuit constitutes a switching power supply, which is widely used in modern electronic devices because of its high efficiency, small size and strong adaptability, covering almost all fields that require power conversion. It can not only provide stable output, but also has good regulation ability. In this embodiment, the switching power supply can effectively manage energy during the charging and discharging process of the device, wherein one capacitor deionization device is used for energy desorption and the other capacitor deionization device is used for energy absorption, and the energy is transferred through the buck-boost converter.

[0030] The capacitance value of the equivalent double-layer capacitor of the CDI device is regarded as a constant value. The corresponding equivalent capacitance value can be equivalently obtained by using the change information of the potential of the device during the stable adsorption operation. The acquisition method is as follows: In the adsorption stage of the capacitive deionization device, a constant DC current source I is applied to the capacitive deionization device for adsorption and desalination. Its voltage rises almost linearly with time. It is considered that the voltage rises linearly due to the constant current charging of the equivalent double-layer capacitor. According to the formula: , in, is the voltage value of the CDI device at time t, is the voltage value of the CDI device after t=0 (i.e., the voltage value after the overvoltage jump occurs), is the constant DC current value, is the capacitance value of the equivalent double layer capacitor, = time, use an oscilloscope or voltmeter to obtain the slope K of the diagonal line in the graph of the voltage change over time Vt (voltage-time) of the capacitor deionization device, and obtain the capacitance value of the equivalent double-layer capacitor .

[0031] The resistance value of the equivalent parallel resistance of the CDI device is a constant value, which is used to equalize the non-ideal behavior in the actual system, such as the leakage phenomenon on the double-layer capacitor. The method of obtaining it is as follows: In the adsorption stage of the capacitive deionization device, the capacitance value of the equivalent double-layer capacitor can be considered to be When the voltage change is sufficient to obtain the slope K of the diagonal line in the above-mentioned graph of the voltage change over time Vt of the capacitor deionization device, the capacitance value of the equivalent double-layer capacitor can be derived. After that, the conductivity fluctuation of the solution in the capacitive deionization device channel is still relatively mild. At this time, the external DC current source can be disconnected, and the charged double-layer capacitor is regarded as discharging to the equivalent parallel resistor. According to the voltage formula of the RC circuit capacitor discharge: , in, is the initial voltage value when the external power supply is disconnected and discharged, e is the base of the natural logarithm, t is the time, Cdl is the measured equivalent double-layer capacitance value, is the equivalent parallel resistance. The voltage value of the capacitor deionization device at the corresponding time t can be calculated to calculate the equivalent parallel resistance The numerical value of .

[0032] The equivalent series resistance of the CDI device is a key time-varying parameter in the energy recovery optimization process, and its initial value must be obtained first. Obtaining the initial value of the equivalent series resistance of the CDI device includes: when the capacitor deionization device begins to enter the adsorption stage, first apply a constant DC current source to it. At the moment when the switch is closed and turned on, it is assumed that the voltage value on the equivalent double-layer capacitor in the equivalent circuit does not change suddenly. Therefore, the instantaneous voltage change value of the capacitor deionization device is measured at t=0 and divided by the applied DC current value to approximately obtain the initial value of the series resistance of the equivalent circuit. Among them, the constant DC current can be provided by a constant current supplier, and the voltage change can be measured by connecting a voltmeter in parallel. Similarly, a constant voltage source can also be applied when entering the adsorption stage. At the moment when the switch is closed and turned on, it is assumed that the voltage value on the equivalent double-layer capacitor Cdl in the equivalent circuit does not change suddenly. Therefore, the instantaneous current change value of the capacitor deionization device is measured at t=0, and the constant voltage source value is divided by the instantaneous current change value to approximately obtain the initial value of the series resistance of the equivalent circuit. Among them, the constant voltage can be provided by a constant current supplier, and the current change value can be measured by connecting an ammeter in series.

[0033] In addition, the inductor L used in the bidirectional buck-boost step-up and step-down circuit can be selected according to experience, and generally a value of 10μH-100μH is selected as needed. The circuit switch composed of the power electronic component IGBT or MOSFET, as well as the sensing resistor, amplifier, controller and other components that meet the use requirements can be used. The correction model of the equivalent series resistance in step S2 includes the functional relationship between the correction value of the equivalent series resistance of the CDI device and the conductivity of the electrolyte solution at different times during the energy recovery process. The functional expression of the correction model of the equivalent series resistance in step S2 of this embodiment is: , in, For the The equivalent series resistance of CDI devices in this round The correction value of For the The initial value of the equivalent parallel resistance of each CDI device, is the distance between the electrodes of the CDI device, is the electrode surface area of ​​the CDI device, For the The initial electrolyte solution conductivity of each CDI device, For the CDI equipment in this round The conductivity of the electrolyte solution. The various constant resistances or stable resistances generated by the circuit wires and their connection points during the operation of the CDI device, the contact between the current collector and the electrode porous medium, and the ion resistance encountered by the directional migration of ions in the electrolyte solution under the action of the electric field. As the desorption energy-releasing CDI device releases electrical energy, the ions adsorbed on the electrode surface return to the interval flow channel of the CDI device, and the concentration of the electrolyte solution increases; as the adsorption energy-consuming CDI device absorbs electrical energy, the electrode surface adsorbs ions in the interval flow channel of the CDI device, and the concentration of the electrolyte solution decreases. Use a conductivity meter to measure the initial solution conductivity of the CDI device and the instantaneous conductivity value of the interval flow channel , input the conductivity value into the correction relationship of equivalent series resistance, and then correct the equivalent series resistance Parameter value.

[0034] In the energy recovery system based on CDI equipment, this embodiment dynamically adjusts the reference current of the bidirectional buck-boost step-up and step-down circuit. Iref To achieve optimal control of energy transmission. During operation, the voltage at the energy input end (i.e., the CDI device that desorbs and releases energy) gradually decreases, while the voltage at the energy output end (i.e., the CDI device that adsorbs and consumes energy) gradually increases. This dynamic change in voltage directly affects the energy transmission efficiency. In addition, as the CDI device operates, the time-varying resistance characteristics of the electrolyte solution cause the system's ohmic loss to change nonlinearly. Therefore, reasonably adjusting the value of the reference current can not only effectively reduce the ohmic loss of the CDI device, but also compensate and eliminate random errors during the operation of the CDI device, so that the equipment can reach the set duration on time. Figure 4 As shown, step S3 in this embodiment includes: S3.1, Initialize iteration variables =1, detect and obtain the initial voltage of the desorption and energy release CDI device and electrolyte solution conductivity , and the initial voltage of the adsorption energy CDI device and electrolyte solution conductivity ; S3.2, calculation of this round Reference current : , in, is the initial voltage value of the desorption and energy release CDI device, is the double-layer capacitance value of the desorption energy release CDI device, The expected duration of the energy recovery project; S3.3, use this round Reference current Control DC / DC converter in this round Cycle Perform energy recovery operation within; detect and obtain this round Cycle The parameters at the end include: desorption and energy release of CDI equipment in this round Voltage and electrolyte solution conductivity , and adsorption energy CDI equipment in this round Voltage and electrolyte solution conductivity ; If the desorption energy release CDI equipment is Voltage If the voltage is less than a preset threshold (e.g. 0.1V), the process ends and exits; otherwise, the process jumps to step S3.5; S3.4, according to this round Cycle Parameter calculation at the end of this round Ohmic loss Ideal voltage for CDI equipment ; S3.5, if this round Ohmic loss Greater than or equal to the previous round Ohmic loss , then reduce the current round Reference current To get the next round Reference current ; If this round Ohmic loss Less than the previous round Ohmic loss , and desorption and energy release CDI equipment in this round Voltage Less than the ideal voltage for desorption and energy release CDI equipment , then reduce the current round Reference current To get the next round Reference current ; If this round Ohmic loss Less than the previous round Ohmic loss , and desorption and energy release CDI equipment in this round Voltage Greater than or equal to the ideal voltage of the desorption and energy release CDI equipment , then increase this round Reference current To get the next round Reference current ; Iterate over the variable Add 1 and jump to step S3.3.

[0035] In step S3.1 of this embodiment, =0.51 V (volts), =0 V (volts), =0.32S / m (Siemens per meter), =0.28 S / m (Siemens per meter); the expected duration of the energy recovery in step S3.2 can be determined according to actual needs. For example, in this embodiment, ; Initial reference current 0.04 A (ampere). Initial ohmic loss in step S3.5 =0.2.

[0036] In addition, in response to the problem of the lack of a comprehensive multi-factor adjustment strategy for the reference current, this embodiment proposes a dynamic adjustment strategy based on real-time calculation of two key indicators: ohmic efficiency and energy recovery rate. In this strategy, ohmic efficiency reflects the resistance loss under the current adjustment cycle, while the energy recovery rate measures whether the energy recovery meets expectations. By taking these two indicators into consideration, the reference current can be adjusted more accurately to maximize the energy recovery efficiency while ensuring the stability and continuity of the energy recovery process. This comprehensive control method takes into account both the energy conversion efficiency of the system and the energy recovery speed. It is a more reasonable and scientific reference current adjustment method, thereby optimizing the energy recovery performance of the CDI system.

[0037] In step S3.4 of this embodiment, this round n Ohmic loss The calculation function expression is: , in, and The equivalent series resistance of the desorption energy release CDI equipment and the adsorption energy use CDI equipment is The loss value, and The equivalent parallel resistance of the desorption energy release CDI equipment and the adsorption energy use CDI equipment in this round The loss value, and They are the capacitance values ​​of the double-layer capacitors of the desorption energy-releasing CDI equipment and the adsorption energy-using CDI equipment, respectively. and They are desorption energy release CDI equipment and adsorption energy use CDI equipment. The voltage is: , , in, For the The equivalent series resistance of CDI devices in this round The loss value, For this round The reference current, For the The equivalent series resistance of CDI devices in this round n The correction value of To adjust the interval time parameters, For the The equivalent parallel resistance of CDI devices in this round The loss value, For the CDI equipment in this round The voltage, The value is 1 or 2. When it is 1, it means desorption and energy release CDI equipment, When it is 2, it indicates adsorption energy CDI equipment.

[0038] In step S3.4 of this embodiment, this round n The ideal voltage for desorption and release of CDI equipment The calculation function expression is: , in, For the previous round n- 1 Ideal voltage for desorption and energy release CDI equipment, For this round n The reference current, To adjust the interval time parameters, It is the capacitance value of the double-layer capacitor of the desorption energy-releasing CDI device.

[0039] It should be noted that in step S3.5, the current round is reduced Reference current To get the next round Reference current The desired implementation method can be adopted as needed, such as multiplying by a coefficient less than 1 or subtracting an increment, etc., where the increment can be a constant or a dynamically changing value. As an optional implementation method, in step S3.5 of this embodiment, the current round is reduced. Reference current To get the next round Reference current The function expression is: , in, It is an adjustment proportional factor less than 1, and can be set according to actual needs. For example, in this embodiment, the value is 0.05.

[0040] It should be noted that the increase in this round in step S3.5 Reference current To get the next round Reference current The desired implementation method can be adopted as needed, such as multiplying by a coefficient greater than 1 or adding an increment, where the increment can be a constant or a dynamically changing value. As an optional implementation method, in step S3.5 of this embodiment, the current round is increased Reference current To get the next round Reference current The function expression is: , in, An adjustment scale factor less than 1.

[0041] In the bidirectional buck-boost step-up and step-down circuit, the reference current value needs to be adjusted in real time to control the transfer current size of the energy input and output ends. During operation, the voltage of the energy input end, i.e., the desorption and release CDI device, will become lower and lower, and the voltage of the energy output end, i.e., the adsorption and use CDI device, will become higher and higher. The energy transmission loss varies at each stage, depending on the operation of the CDI device, especially the change in the resistance of the electrolyte solution. The adjustment interval time parameters are determined according to the accuracy of sampling instruments such as voltmeters and conductivity meters. (Unit: seconds, s), the reference current value is After a certain period of time, an evaluation adjustment is performed, so The value of the reference current is adjusted to adjust the frequency. In this embodiment s. The energy recovery adjustment cycle is named , ,…, ,in n is the number of rounds, and so on until the voltage value of the desorption and energy release CDI device is less than 0.1V (volt), the energy recovery phase is considered to be over, and the power adjustment is ended. At the beginning of the energy recovery phase, the adjustment cycle begins after the initial parameters are determined, where the initial parameters include: the initial reference current value estimated by the expected total recovery time: , Initial voltage value of desorption and energy release CDI equipment: , Initial voltage value of adsorption energy CDI equipment: (Generally 0V, the voltage value is measured by a voltmeter), initial electrolyte solution conductivity of the desorption and energy release CDI equipment: , conductivity of initial electrolyte solution of adsorption energy CDI equipment: (Conductivity value measured by conductivity meter), and initial reference ohmic loss (This value can be selected based on experience.) During the energy recovery process, the system will obtain real-time solution conductivity, current, and potential data to calculate and control the reference current in the DC / DC converter in real time. Until the output voltage of the desorption and energy release CDI device is less than 0.1V, it is considered that the double-layer capacitor can no longer drive the system to recover energy and the energy recovery is terminated.

[0042] This embodiment uses an experimentally verified electrochemical-fluid dynamics coupled multi-physics field simulation model to verify the energy-saving control method, and sets up three comparative experimental schemes. The system parameters, initial voltage, inlet flow rate (0.42 ml / min in this embodiment) and other settings of the desorption energy-releasing CDI device and the adsorption energy-using CDI device used in the three groups of schemes are the same. Scheme 1 is a direct energy transmission mode without a DC / DC converter. The output voltage of the desorption energy-releasing CDI device is Input voltage of CDI equipment Directly connect, the energy recovery termination condition is: = ±0.01V (voltage balance threshold). Solution 2 is to configure the constant current control mode of the bidirectional buck-boost converter, use the DC / DC buck-boost converter to recycle energy between CDI devices, set the constant reference current value to 0.04±2%A (ampere), and the energy recovery termination condition is ≤0.1V±5mV measurement error. Solution 3 is to configure the dynamic current regulation mode of the bidirectional buck-boost converter, use the DC / DC buck-boost converter to recycle energy between CDI devices, and set the initial reference current =0.04A (ampere), dynamically adjust the reference current according to the double-layer capacitor charge and discharge rate and ohmic loss index of the energy recovery system The value of Figure 5 FIG. 4 is a schematic diagram showing the reference current of the DC / DC converter after dynamic current regulation operation. Figure 6The figure shows the change of the outlet concentration C of the adsorption energy CDI equipment with the adsorption time t under the above three different schemes. With Scheme 1, the energy transfer process can be regarded as stopped after about 300s, and the concentration at the outlet is finally maintained at about 16mM, and the concentration decreases at a faster rate. The time efficiency of this scheme is high, but the outlet concentration curve fluctuates and has an inflection point, indicating that the energy transfer process is not stable and controllable enough. With Scheme 2, the energy transfer process can be regarded as stopped after about 500s, which is a certain deviation from the expected duration of 600s. The concentration at the outlet continues to drop to about 14mM, and the concentration decreases at a uniform rate. After 200s of adsorption, the outlet concentration can be considered to be linearly decreasing, reflecting the high adsorption stability of this scheme. Using scheme three, the energy transfer process can be considered to have stopped after about 610s, which is very close to the expected duration of 600s. The concentration at the outlet continues to drop to about 12mM, and the rate of concentration drop is more uniform. After 200s of adsorption, the concentration at the outlet can be considered to have a linear decline, reflecting the high adsorption stability of this scheme. The dynamic adjustment of the reference current has an effect on improving the system efficiency and controlling the double-layer discharge rate. Figure 7 Shown is a comparison chart of the results of energy recovery time, ion removal amount, ion removal rate and energy recovery rate under the above three different schemes. Among them, Scheme 2 and Scheme 3 equipped with a DC / DC converter have increased ion removal amount and energy recovery rate compared with Scheme 1. And Scheme 3 with a dynamic current regulation mode is superior to the other two groups of schemes in ion removal amount, ion removal rate and energy recovery rate. In this embodiment, the scheme with a DC / DC converter in dynamic current regulation mode improves the energy recovery rate by 7.8%, the ion removal rate by 1.9%, and the ion removal amount by 1.36 times compared with the scheme without a DC / DC converter. It improves the energy recovery rate by 6.1%, the ion removal rate by 4.5%, and the ion removal amount by 0.7 times compared with the scheme with a constant current mode DC / DC converter, and is consistent with the expected working time. The error is only 2%, which proves that the method of this embodiment can effectively improve the energy utilization rate of capacitive deionization equipment and achieve efficient energy recovery and reuse.

[0043] In addition, this embodiment also provides an energy-saving control system for capacitive deionization equipment, including a microprocessor and a memory connected to each other, and the microprocessor is programmed or configured to execute the energy-saving control method for the capacitive deionization equipment.

[0044] In addition, this embodiment also provides a computer-readable storage medium, in which a computer program or instruction is stored. The computer program or instruction is programmed or configured to execute the energy-saving control method of the capacitive deionization equipment through a processor.

[0045] In addition, this embodiment also provides a computer program product, including a computer program or instructions, which are programmed or configured to execute the energy-saving control method of the capacitive deionization equipment through a processor.

[0046] Those skilled in the art should understand that the technical solutions provided by the embodiments of the present invention may be in the form of methods, systems, or computer program products. Therefore, the present invention may take the form of a complete hardware embodiment, a complete software embodiment, or an embodiment combining software and hardware. Moreover, the present invention may take the form of a computer program product implemented on one or more computer-readable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) containing computer-usable program codes. The present invention is described with reference to flowcharts and / or block diagrams of methods, devices (systems), and computer program products according to embodiments of the present invention. It should be understood that each process and / or box in the flowchart and / or block diagram, as well as the combination of processes and / or boxes in the flowchart and / or block diagram, may be implemented by computer program instructions. These computer program instructions may be provided to a processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing device to produce a machine, so that instructions executed by the processor of a computer or other programmable data processing device generate instructions for implementing the functions in the process. Figure 1 A process or multiple processes and / or boxes Figure 1 These computer program instructions can also be stored in a computer-readable memory that can guide a computer or other programmable data processing device to work in a specific way, so that the instructions stored in the computer-readable memory produce a product including an instruction device, which implements the functions specified in the process. Figure 1 A process or multiple processes and / or boxes Figure 1 These computer program instructions can also be loaded onto a computer or other programmable data processing device, so that a series of operation steps are executed on the computer or other programmable device to produce a computer-implemented process, so that the instructions executed on the computer or other programmable device provide for implementing the process in the process. Figure 1 A process or multiple processes and / or boxes Figure 1 A step that specifies a function in one or more boxes.

[0047] The above is only a preferred embodiment of the present invention, and the protection scope of the present invention is not limited to the above embodiments. All technical solutions under the concept of the present invention belong to the protection scope of the present invention. It should be pointed out that for ordinary technicians in this technical field, some improvements and modifications without departing from the principle of the present invention should also be regarded as the protection scope of the present invention.

Claims

1. A method for energy saving control of capacitor deionization equipment, characterized in that: The steps include: S1, establishing a dynamic equivalent circuit for a capacitor deionization equipment including a DC / DC converter and two CDI devices, wherein each CDI device is equivalent to an equivalent double-layer capacitor, an equivalent parallel resistor and an equivalent series resistor, the equivalent parallel resistor and the equivalent double-layer capacitor are connected in parallel and then connected in series with the equivalent series resistor, the DC / DC converter is equivalent to an inductor L, a sensor resistor Rsensor, two equivalent power electronic switches and a controller, one end of the two CDI devices is directly connected and the other end is connected through two equivalent power electronic switches, the series branch formed by the inductor L and the sensor resistor Rsensor is connected in parallel between the loops of the two CDI devices, and the control ends of the two equivalent power electronic switches are connected to the controller; S2, setting the capacitance value of the equivalent double-layer capacitor, the resistance value of the equivalent parallel resistor and the initial value of the equivalent series resistor of the CDI device, and establishing a correction model of the equivalent series resistor when the conductivity of the electrolyte solution changes during the energy recovery process; S3, combining the modified model of equivalent series resistance and the charge and discharge rate and ohmic loss of the double-layer capacitor of the CDI device during the energy recovery process, and using the dynamic equivalent circuit to obtain the reference current required for the DC / DC converter to perform energy recovery control; The functional expression of the correction model of the equivalent series resistance in step S2 is: ， in, For the The equivalent series resistance of CDI devices in this round The correction value of For the The initial value of the equivalent parallel resistance of each CDI device, is the distance between the electrodes of the CDI device, is the electrode surface area of ​​the CDI device, For the The initial electrolyte solution conductivity of each CDI device, For the CDI equipment in this round The conductivity of the electrolyte solution.

2. The energy-saving control method for capacitive deionization equipment according to claim 1, characterized in that: Step S3 includes: S3.1, Initialize iteration variables =1, detect and obtain the initial voltage of the desorption and energy release CDI device and electrolyte solution conductivity , and the initial voltage of the adsorption energy CDI device and electrolyte solution conductivity ; S3.2, calculation of this round Reference current : ， in, is the initial voltage value of the desorption and energy release CDI device, is the double-layer capacitance value of the desorption and energy release CDI device, The expected duration of the energy recovery project; S3.3, use this round Reference current Control DC / DC converter in this round Cycle Perform energy recovery operation within; detect and obtain this round Cycle The parameters at the end include: desorption and energy release of CDI equipment in this round Voltage and electrolyte solution conductivity , and adsorption energy CDI equipment in this round Voltage and electrolyte solution conductivity ; If the desorption energy release CDI equipment is Voltage If the value is less than the preset threshold, the process ends and exits; otherwise, the process jumps to step S3.5; S3.4, according to this round Cycle The parameters at the end of this round are calculated Ohmic loss Ideal voltage for desorption and energy release CDI equipment ; S3.5, if this round Ohmic loss Greater than or equal to the previous round Ohmic loss , then reduce the current round Reference current To get the next round Reference current ; If this round Ohmic loss Less than the previous round Ohmic loss , and desorption and energy release CDI equipment in this round Voltage Less than the ideal voltage for desorption and energy release CDI equipment , then reduce the current round Reference current To get the next round Reference current ; If this round Ohmic loss Less than the previous round Ohmic loss , and desorption and energy release CDI equipment in this round Voltage Greater than or equal to the ideal voltage of the desorption and energy release CDI equipment , then increase this round Reference current To get the next round Reference current ; Iterate over the variable Add 1 and jump to step S3.

3.

3. The energy-saving control method for capacitive deionization equipment according to claim 2, characterized in that: In step S3.4, this round Ohmic loss The calculation function expression is: ， in, and The equivalent series resistance of the desorption energy-releasing CDI equipment and the adsorption energy-using CDI equipment is The loss value, and The equivalent parallel resistance of the desorption energy release CDI equipment and the adsorption energy use CDI equipment in this round The loss value, and They are the capacitance values ​​of the double-layer capacitors of the desorption energy-releasing CDI equipment and the adsorption energy-using CDI equipment, respectively. and They are desorption energy release CDI equipment and adsorption energy use CDI equipment. The voltage is: ， ， in, For the The equivalent series resistance of CDI devices in this round The loss value, For this round The reference current, For the The equivalent series resistance of CDI devices in this round n The correction value of To adjust the interval time parameters, For the The equivalent parallel resistance of CDI devices in this round The loss value, For the CDI equipment in this round The voltage, The value is 1 or 2. When it is 1, it means desorption and energy release CDI equipment, When it is 2, it indicates adsorption energy CDI equipment.

4. The energy-saving control method for capacitive deionization equipment according to claim 2, characterized in that: In step S3.4, this round n The ideal voltage for desorption and release of CDI equipment The calculation function expression is: ， in, For the previous round n- 1 Ideal voltage for desorption and energy release CDI equipment, For this round n The reference current, To adjust the interval time parameters, It is the capacitance value of the double-layer capacitor of the desorption energy-releasing CDI device.

5. The energy-saving control method for capacitive deionization equipment according to claim 2, characterized in that: In step S3.5, reduce the current round Reference current To get the next round Reference current The function expression is: ， in, An adjustment scale factor less than 1.

6. The energy-saving control method for capacitive deionization equipment according to claim 2, characterized in that: Add this round in step S3.5 Reference current To get the next round Reference current The function expression is: ， in, An adjustment scale factor less than 1.

7. An energy-saving control system for capacitor deionization equipment, comprising a microprocessor and a memory connected to each other, characterized in that: The microprocessor is programmed or configured to execute the energy-saving control method for capacitive deionization equipment according to any one of claims 1 to 6.

8. A computer-readable storage medium having a computer program or instruction stored therein, characterized in that: The computer program or instruction is programmed or configured to execute the energy-saving control method for capacitive deionization equipment according to any one of claims 1 to 6 through a processor.

9. A computer program product comprising a computer program or instructions, characterized in that The computer program or instruction is programmed or configured to execute the energy-saving control method for capacitive deionization equipment according to any one of claims 1 to 6 through a processor.

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