A control system for detecting zinc-bromine flow battery reservoir level

Abstract

A control system for detecting the liquid level of a zinc-bromine flow battery storage tank, comprising: a stack; a storage tank; a circulating pump; at least two first pressure sensors; at least one second pressure sensor; a detection module, comprising: a density measurement unit, which processes the received first measurement signal and the height difference between the two first pressure sensors according to a preset instruction to obtain the density value of the electrolyte in the current state; a liquid level measurement unit, which processes the first measurement signal, the second measurement signal, and the density value obtained by the density measurement unit according to a preset instruction, and obtains the true liquid level of the electrolyte in the current state. The two first pressure sensors with height difference are used to detect the pressure value, which is processed by a preset instruction to obtain the density of the electrolyte at different times during charging and discharging. The true liquid level of the electrolyte is obtained by using the density and the liquid phase pressure value, which can accurately determine the electrolyte liquid level in the positive and negative electrolyte storage tanks during the charging and discharging of the stack, and better manage the state of the battery monomer.

Description

Technical Field

[0001] This utility model relates to the field of battery technology, specifically to a control system for detecting the liquid level in a zinc-bromine flow battery storage tank. Background Technology

[0002] A flow battery consists of a stack unit, electrolyte, electrolyte storage and supply unit, and management and control unit. It is a high-performance battery that utilizes separate positive and negative electrolytes for independent circulation. It features high capacity, wide range of applications, and long cycle life, and is a new energy product.

[0003] A conventional flow battery mainly consists of three parts: a storage tank, a stack, and piping. The electrolyte circulation is storage tank-pump-stack-storage tank. The electrolyte is primarily stored in the storage tank. However, because the material properties (density, viscosity, temperature) of the positive and negative electrode electrolytes in zinc-bromine flow batteries constantly change during charging and discharging, the liquid level in the storage tank cannot be independently detected using conventional level sensors. In other words, existing level sensors are not accurate in measuring the liquid level, leading to a discrepancy between the actual and measured levels. This hinders effective management of the individual battery cells' condition.

[0004] For example, Chinese patent CN 116759683 A discloses a battery cell, an electrolyte level height testing method, a battery, and an electrical device. This method consistently employs a level sensor, utilizing a substrate and a detection electrode. The detection electrode is positioned on the substrate, and at least a portion of the substrate surface in contact with the electrolyte is designated as a flow-guiding surface. This flow-guiding surface guides the electrolyte away from the substrate, thus reducing the possibility of errors in electrolyte level measurement caused by some electrolyte adhering to the substrate surface. However, this method still relies on a level sensor for electrolyte level height detection, only designing the sensor's structure to minimize errors. This approach is costly and always introduces a certain degree of error. Utility Model Content

[0005] In view of the shortcomings of the existing technology, the purpose of this utility model is to provide a control system for detecting the liquid level of the storage tank of zinc-bromine flow battery.

[0006] To achieve the above objectives, the present invention provides the following technical solution: A control system for detecting the liquid level in a zinc-bromine flow battery storage tank, comprising: fuel cell stack; There are two sets of storage tanks, one for storing the positive electrode electrolyte and the other for storing the negative electrode electrolyte, and they are connected to the positive electrode inlet and the other for storing the negative electrode electrolyte of the fuel cell stack respectively. Two sets of circulating pumps are installed between the outlets of the positive / negative electrode storage tanks and the positive / negative electrode inlets of the fuel cell stack, respectively, to provide power for electrolyte circulation; At least two first pressure sensors are installed on the side wall of the storage tank, located below the electrolyte level, to acquire pressure values ​​at different heights inside the storage tank and output a first measurement signal containing the pressure values; At least one second pressure sensor is installed on the top wall of the liquid storage tank to acquire the gas phase pressure value in the liquid storage tank and output a second measurement signal containing the gas phase pressure value; A detection module is used to obtain the actual liquid level of the electrolyte in the storage tank. The detection module includes: The density measurement unit processes the received first measurement signal according to preset instructions to obtain the density value of the electrolyte in the current state. The liquid level measurement unit processes the first measurement signal, the second measurement signal, and the density value obtained by the density measurement unit according to preset instructions, and obtains the true liquid level of the electrolyte under the current state.

[0007] A four-way reversing valve is installed between the outlet and inlet pipes of the storage tank used to store the positive electrode electrolyte.

[0008] The distance between the two first pressure sensors is a fixed value.

[0009] The outlet of the storage tank is located on the lower side wall of the storage tank.

[0010] The inlet of the liquid storage tank is located on the upper side of the liquid storage tank.

[0011] The beneficial effects of this utility model are as follows: By using two first pressure sensors with a height difference to detect pressure values, and processing them through preset instructions, the density of the electrolyte at different charging and discharging times can be obtained. The density and liquid phase pressure values ​​can be used to obtain the current true liquid level of the electrolyte. This enables accurate judgment of the electrolyte level in the positive and negative electrode storage tanks during the charging and discharging process of the battery stack, thus better managing the state of the battery cells. Attached Figure Description

[0012] Figure 1 This is a schematic diagram illustrating the principle of this utility model. Detailed Implementation

[0013] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present utility model, and not all embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the protection scope of the present utility model.

[0014] It should be noted that all directional indicators (such as up, down, left, right, front, back, etc.) in this utility model embodiment are only used to explain the relative positional relationship and movement of each component in a certain specific posture (as shown in the figure). If the specific posture changes, the directional indicator will also change accordingly.

[0015] As shown in the figure, a control system for detecting the liquid level in a zinc-bromine flow battery storage tank includes: The fuel cell stack 1 includes a positive electrode inlet and a negative electrode inlet and outlet, which are used for electrochemical reactions to generate direct current. The storage tank 2 consists of two sets, which are used to store the positive and negative electrolytes respectively, and are connected to the positive and negative inlets and outlets of the fuel cell stack respectively. The fuel cell stack and the storage tank are connected through positive and negative pipelines, so that the electrolyte can circulate between the fuel cell stack and the storage tank. Two sets of circulating pumps 3 are respectively installed between the outlet of the positive / negative electrode storage tank and the positive / negative electrode inlet of the fuel cell stack to provide power for electrolyte circulation; At least two first pressure sensors 4 are installed on the side wall of the storage tank, located below the electrolyte level, to acquire pressure values ​​at different heights inside the storage tank and output a first measurement signal containing the pressure value; The height difference between the two first pressure sensors is determined when the first pressure sensors are installed.

[0016] At least one second pressure sensor 5 is installed on the top wall of the liquid storage tank to acquire the gas phase pressure value in the liquid storage tank and output a second measurement signal containing the gas phase pressure value. The detection module, used to obtain the actual liquid level of the electrolyte in the storage tank, includes: The density measurement unit processes the received first measurement signal and the height difference between the two first pressure sensors according to preset instructions to obtain the density value of the electrolyte in the current state. That is, the first measurement signals output by the two first pressure sensors are used by the density measurement unit to calculate the current electrolyte density value according to the set instructions. Specifically, based on Bernoulli's equation, a preset instruction is set, and with a determined height difference ΔH, the current electrolyte density ρ can be calculated from the pressure values ​​P1 and P2 measured by the two first pressure sensors. A preset instruction is established, using the pressure values ​​P1 and P2 of the two first pressure sensors as the first input, the height difference between the two first pressure sensors as the second input, and the current density of the electrolyte as the output, for the density measurement unit to obtain the current electrolyte density.

[0017] The liquid phase pressure at the first pressure sensor on the lower side is obtained by subtracting the gas phase pressure value measured by the second pressure sensor from the pressure value measured by the first pressure sensor on the lower side.

[0018] The liquid level measurement unit processes the first measurement signal, the second measurement signal, and the density value obtained by the density measurement unit according to preset instructions, and obtains the true liquid level of the electrolyte under the current state.

[0019] Using the liquid phase pressure value and density ρ based on preset commands, the liquid level measurement unit can obtain the height H1 of the electrolyte surface from the first pressure sensor. Adding this to the height h of the lower first pressure sensor, the true height of the electrolyte surface can be obtained. Similarly, based on Bernoulli's equation, preset commands are set, with the difference between the pressure value of the lower first pressure sensor and the gas phase pressure value as the first input, and the current electrolyte density ρ as the second input, resulting in the output height H1. This height H1, combined with the height h of the lower first pressure sensor, yields the true electrolyte level.

[0020] A four-way reversing valve 6 is installed between the outlet and inlet pipes of the storage tank used to store the positive electrode electrolyte. The flow reversing valve is used to switch the flow direction.

[0021] The distance between the two primary pressure sensors is a fixed value, which better adapts to the preset instructions and makes the acquisition of the true liquid level more accurate.

[0022] The outlet of the storage tank is located on the lower side wall, while the inlet is located on the upper side. This top-in, bottom-out design allows for better electrolyte circulation. The outlet's location on the side wall, at a certain height from the bottom of the storage tank, ensures the outlet will not be blocked, thus facilitating better electrolyte circulation.

[0023] The embodiments should not be regarded as limitations on the present invention, but any improvements made based on the spirit of the present invention should be within the protection scope of the present invention.

Claims

1. A control system for detecting the liquid level in a zinc-bromine flow battery storage tank, characterized in that: It includes: fuel cell stack; There are two sets of storage tanks, one for storing the positive electrode electrolyte and the other for storing the negative electrode electrolyte, and they are connected to the positive electrode inlet and the other for storing the negative electrode electrolyte of the fuel cell stack respectively. Two sets of circulating pumps are installed between the outlets of the positive / negative electrode storage tanks and the positive / negative electrode inlets of the fuel cell stack, respectively, to provide power for electrolyte circulation; At least two first pressure sensors are installed on the side wall of the storage tank, located below the electrolyte level, to acquire pressure values ​​at different heights inside the storage tank and output a first measurement signal containing the pressure values; At least one second pressure sensor is installed on the top wall of the liquid storage tank to acquire the gas phase pressure value in the liquid storage tank and output a second measurement signal containing the gas phase pressure value; A detection module is used to obtain the actual liquid level of the electrolyte in the storage tank. The detection module includes: The density measurement unit processes the received first measurement signal according to preset instructions to obtain the density value of the electrolyte in the current state. The liquid level measurement unit processes the first measurement signal, the second measurement signal, and the density value obtained by the density measurement unit according to preset instructions, and obtains the true liquid level of the electrolyte under the current state.

2. The control system for detecting the liquid level of a zinc-bromine flow battery storage tank according to claim 1, characterized in that: A four-way reversing valve is installed between the outlet and inlet pipes of the storage tank used to store the positive electrode electrolyte.

3. The control system for detecting the liquid level of a zinc-bromine flow battery storage tank according to claim 1, characterized in that: The distance between the two first pressure sensors is a fixed value.

4. The control system for detecting the liquid level of a zinc-bromine flow battery storage tank according to claim 1, characterized in that: The outlet of the storage tank is located on the lower side wall of the storage tank.

5. The control system for detecting the liquid level of a zinc-bromine flow battery storage tank according to claim 1, characterized in that: The inlet of the liquid storage tank is located on the upper side of the liquid storage tank.

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