CN117797645B - Method for predicting internal current of bipolar membrane electrodialysis membrane reactor device - Google Patents

Abstract

The present invention relates to the technical field of bipolar membrane electrodialysis membrane stacks, and specifically, to a method for predicting the internal current of a bipolar membrane electrodialysis membrane stack device. The method comprises the following steps: S1, calculating the differential operator of the leakage current of the acid chamber, S2, calculating the differential operator of the leakage current of the material chamber, S3, calculating the differential operator of the leakage current of the alkali chamber, S4, calculating the leakage current of each compartment cloth/water collection trough part flowing through the first unit, S5, calculating the leakage current of each compartment cloth/water collection trough part flowing through the second unit, S6, calculating the leakage current of each compartment cloth/water collection trough part flowing through the Kth unit, S7, calculating the leakage current of each compartment cloth/water collection hole part flowing through the Kth unit, and S8, calculating the effective current of each compartment effective area part flowing through the Kth unit. The present method can accurately and reliably predict the leakage current and the effective current, and further optimize the configuration design of the membrane stack device to improve the process efficiency.

Description

A method for predicting internal current of a bipolar membrane electrodialysis stack device

Technical Field

The present invention relates to the technical field of bipolar membrane electrodialysis membrane stacks, and in particular to a method for predicting the internal current of a bipolar membrane electrodialysis membrane stack device.

Background technique

Bipolar membrane electrodialysis is a new type of electrodialysis technology that can convert low-value inorganic/organic salts into corresponding acids and bases in situ. At the same time, bipolar membrane electrodialysis technology has the characteristics of simple process, low energy consumption and environmental friendliness, so this technology is widely used in many fields such as chemical industry, food, medicine and environment. The core component of the bipolar membrane electrodialysis system is the membrane stack device, which contains a large number of non-metallic materials such as diaphragms and partitions. The non-metallic components in the membrane stack device can not only constitute the liquid circuits that work relatively independently, but also form corresponding ohmic circuits with the input of external current. The current flowing through the effective area of the membrane stack device can be called the effective current, and the current flowing through the cloth/water collection tank and cloth/water collection hole is called the leakage current. The current flowing through the above parts is inevitably converted into Joule heat, thereby reducing the energy efficiency ratio of the device, and in severe cases, it damages the safety of the equipment. According to the survey, the internal thermal effect of the industrial-scale bipolar membrane electrodialysis membrane stack device is significant, which seriously affects the safe and stable operation of the equipment. However, a method for predicting the internal current of the bipolar membrane electrodialysis membrane stack device has not yet been established.

Summary of the invention

The purpose of the present invention is to provide a method for predicting the internal current of a bipolar membrane electrodialysis membrane stack device in view of the above problems. The prediction is accurate and reliable and can be used for subsequent indicator prediction.

To achieve the above object, the present invention discloses a method for predicting the internal current of a bipolar membrane electrodialysis membrane stack device, the method comprising the following steps:

S1, collecting acid chamber cloth/water collection hole resistance ,Ω, acid chamber cloth/water collection tank resistance/> ,Ω and membrane stack unit resistance ,Ω, membrane stack unit resistance/> Including acid chamber resistance, material chamber resistance, alkali chamber resistance, anion exchange membrane resistance, cation exchange membrane resistance and bipolar membrane resistance, determine the acid chamber leakage current differential operator/> 、/> ;

S2, collection chamber cloth/water collection hole resistance ,Ω, chamber cloth/water collection tank resistance/> , Ω, determine the chamber leakage current differential operator/> 、/> ;

S3, collect the resistance of alkali chamber cloth/water collection hole ,Ω; resistance of alkali chamber cloth/water collection tank/> , Ω; Determine the differential operator of the alkali chamber leakage current/> 、/> ;

S4, the number of membrane stack units N; the sum of the acid chamber resistance and the anion exchange membrane resistance ,Ω; the sum of the resistance of the material chamber and the resistance of the cation exchange membrane/> ,Ω; the sum of the base chamber resistance and the bipolar membrane resistance/> ,Ω; input current I,A; the sum of the membrane potentials of the membrane stack units/> , the sum of the membrane potentials of the membrane stack units/> Including the membrane potential of the anion exchange membrane, the membrane potential of the cation exchange membrane and the membrane potential of the bipolar membrane, V, to determine the leakage current flowing through the acid chamber/water collection tank at the first unit/> , A; leakage current flowing through the material chamber cloth/water collection tank at the first unit/> , A; leakage current flowing through the alkali chamber cloth/water collection tank of the first unit/> , A;

S5. Determine the leakage current flowing through the acid chamber/water collection tank at unit 2 , A; leakage current flowing through the material chamber cloth/water collection tank at the second unit/> , A; leakage current flowing through the alkali chamber/water collection tank of the second unit/> , A;

S6. Determine the leakage current flowing through the acid chamber/water collection tank at unit K. , A; leakage current flowing through the material chamber cloth/water collection tank at unit K/> , A; leakage current flowing through the alkali chamber/water collection tank at unit K/> , A;

S7. Determine the leakage current flowing through the acid chamber/water collection hole at unit K. , A; leakage current flowing through the material chamber cloth/water collection hole at the Kth unit/> , A; leakage current flowing through the alkali chamber/water collection hole at unit K/> , A;

S8. Determine the effective current flowing through the effective area of the acid chamber at unit K. , A; effective current flowing through the effective area of the material chamber at the Kth unit/> , A; effective current flowing through the effective area of the alkali chamber at the Kth unit/> ,A.

Preferably, in step S1, the acid chamber leakage current differential operator 、/> The calculation formula is as follows:

;(1);

in, 、/> is the root of formula (1).

Preferably, in step S2, the chamber leakage current differential operator 、/> The calculation formula is as follows:

;(2);

in, 、/> is the root of formula (2).

Preferably, in step S3, the alkali chamber leakage current differential operator 、/> The calculation formula is as follows:

; (3);

in, 、/> is the root of formula (3).

Preferably, in step S4, the calculation formula for the leakage current flowing through each compartment cloth/water collecting trough at the first unit is as follows:

; (4);

; (5);

; (6);

Among them, A ^-1 is the inverse matrix of matrix A; For/> ; /> For/> ; /> For/> ; /> for ; /> For/> ; /> For/> ; /> For/> ; For/> ; /> For/> .

Preferably, in step S5, the calculation formula for the leakage current flowing through each compartment/water collecting tank at the second unit is as follows:

; (7).

Preferably, in step S6, the calculation formula for the leakage current flowing through each compartment/water collection tank at the Kth unit is as follows:

;(8);

;(9);

; (10).

Preferably, in step S7, the calculation formula for the leakage current flowing through each compartment cloth/water collection hole at the Kth unit is as follows:

; (11);

; (12);

; (13).

Preferably, in step S8, the effective current flowing through the effective area of each compartment at the Kth unit is calculated as follows:

; (14);

; (15);

. (16).

In summary, the beneficial effects of the present invention are: the present method can be used to accurately and reliably predict the leakage current of each compartment layout/water collection hole and the effective current of each compartment effective area, which can be used for subsequent indicator prediction and further optimize the configuration design of the membrane stack device to improve process efficiency.

BRIEF DESCRIPTION OF THE DRAWINGS

Fig. 1 is a schematic diagram of the principle of a 1-unit BP-A-C three-compartment bipolar membrane electrodialysis system;

Fig. 2 is a schematic diagram of the structure of a three-compartment bipolar membrane electrodialysis system using an N-unit BP-A-C;

FIG3 is a schematic diagram of the structure of a membrane stack in a BP-A-C three-compartment bipolar membrane electrodialysis system using an N-unit;

Figure 4 is a schematic diagram of the structure of the partition in the N-unit BP-A-C three-compartment bipolar membrane electrodialysis system.

Detailed ways

The specific implementation of the present invention is further described in detail below in conjunction with the accompanying drawings and examples. The following examples are used to illustrate the present invention, but are not intended to limit the scope of the present invention.

As shown in FIGS. 1 to 4 , a method for predicting the internal current of a bipolar membrane electrodialysis stack device comprises the following steps:

S1, collecting acid chamber cloth/water collection hole resistance ,Ω, acid chamber cloth/water collection tank resistance/> ,Ω and membrane stack unit resistance ,Ω, membrane stack unit resistance/> Including acid chamber resistance, material chamber resistance, alkali chamber resistance, anion exchange membrane resistance, cation exchange membrane resistance and bipolar membrane resistance, determine the acid chamber leakage current differential operator/> 、/> ;

S2, collection chamber cloth/water collection hole resistance ,Ω, chamber cloth/water collection tank resistance/> , Ω, determine the chamber leakage current differential operator/> 、/> ;

S3, collect the resistance of alkali chamber cloth/water collection hole ,Ω; resistance of alkali chamber cloth/water collection tank/> , Ω; Determine the differential operator of the alkali chamber leakage current/> 、/> ;

S4, the number of membrane stack units N; the sum of the acid chamber resistance and the anion exchange membrane resistance ,Ω; the sum of the resistance of the material chamber and the resistance of the cation exchange membrane/> ,Ω; the sum of the base chamber resistance and the bipolar membrane resistance/> ,Ω; input current I,A; the sum of the membrane potentials of the membrane stack units/> , the sum of the membrane potentials of the membrane stack units/> Including the membrane potential of the anion exchange membrane, the membrane potential of the cation exchange membrane and the membrane potential of the bipolar membrane, V, to determine the leakage current flowing through the acid chamber/water collection tank at the first unit/> , A; leakage current flowing through the material chamber cloth/water collection tank at the first unit/> , A; leakage current flowing through the alkali chamber cloth/water collection tank of the first unit/> , A;

S5. Determine the leakage current flowing through the acid chamber/water collection tank at unit 2 , A; leakage current flowing through the material chamber cloth/water collection tank at the second unit/> , A; leakage current flowing through the alkali chamber/water collection tank of the second unit/> , A;

S6. Determine the leakage current flowing through the acid chamber/water collection tank at unit K. , A; leakage current flowing through the material chamber cloth/water collection tank at unit K/> , A; leakage current flowing through the alkali chamber/water collection tank at unit K/> , A;

S7. Determine the leakage current flowing through the acid chamber/water collection hole at unit K. , A; leakage current flowing through the material chamber cloth/water collection hole at the Kth unit/> , A; leakage current flowing through the alkali chamber/water collection hole at unit K/> , A;

S8. Determine the effective current flowing through the effective area of the acid chamber at unit K. is, A; the effective current flowing through the effective area of the material chamber at the Kth unit/> , A; effective current flowing through the effective area of the alkali chamber at the Kth unit/> ,A.

In step S1, the acid chamber leakage current differential operator 、/> The calculation formula is as follows:

;(1);

in, 、/> is the root of formula (1).

In step S2, the chamber leakage current differential operator 、/> The calculation formula is as follows:

;(2);

in, 、/> is the root of formula (2).

In step S3, the alkali chamber leakage current differential operator 、/> The calculation formula is as follows:

; (3);

in, 、/> is the root of formula (3).

In step S4, the leakage current flowing through each compartment/water collection tank at the first unit is calculated as follows:

; (4);

; (5);

; (6);

Among them, A ^-1 is the inverse matrix of matrix A; For/> ; /> For/> ; /> For/> ; /> for ; /> For/> ; /> For/> ; /> For/> ; For/> ; /> For/> .

In step S5, the calculation formula for the leakage current flowing through each compartment/water collection tank at the second unit is as follows:

; (7).

In step S6, the calculation formula of the leakage current flowing through each compartment/water collection tank at the Kth unit is as follows:

;(8);

;(9);

; (10).

In step S7, the calculation formula for the leakage current flowing through each compartment/water collection hole at the Kth unit is as follows:

; (11);

; (12);

; (13).

In step S8, the effective current flowing through the effective area of each compartment at the Kth unit is calculated as follows:

; (14);

; (15);

; (16).

A 5-unit BP-AC three-compartment bipolar membrane electrodialysis system was used. 0.5mol/L NaCl solution was used as the acid, alkali, and material chamber circulating solution. The membrane surface flow rate of the solution in the membrane stack was 5cm/s, and the current density applied to the membrane stack was 30mA/ ^cm2 . Platinum wire probes were inserted at positions 1, 3, and 5 of the membrane stack water collection tank to measure the voltage across the water collection tank, and then converted into the leakage current flowing through the water collection tank according to Ohm's theorem. The experimentally measured water collection tank leakage current and the model-predicted leakage current results are shown in Table 1. The results show that the experimental value of the water collection tank leakage current is basically consistent with the model, indicating that the model is accurate and reliable and can be used for subsequent indicator prediction.

Table 1. Comparison of the experimental and model prediction results of the sump leakage current of the BP-A-C three-compartment bipolar membrane electrodialysis membrane stack device.

A 5-unit BP-AC three-compartment bipolar membrane electrodialysis system was used. A 1.0 mol/L NaCl solution was used as the circulating solution in the material chamber, deionized water was used as the initial circulating solution in the acid and alkali chambers, the membrane surface flow rate of the solution in the membrane stack was 5 cm/s, and the current density applied to the membrane stack was 50 mA/cm ² . Real-time data of the bipolar membrane electrodialysis operation for 15 minutes was collected online. The results of predicting the internal current of the BP-AC three-compartment bipolar membrane electrodialysis membrane stack device according to the prediction method of the present invention are shown in Table 2.

Table 2. Prediction results of the internal current of the BP-A-C three-compartment bipolar membrane electrodialysis membrane stack device.

The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and substitutions can be made without departing from the technical principles of the present invention. These improvements and substitutions should also be regarded as the scope of protection of the present invention.

Claims (2)

1. A method for predicting the internal current of a bipolar membrane electrodialysis membrane stack device, characterized in that it comprises the following steps: S1, collecting acid chamber cloth/water collection hole resistance ,Ω, acid chamber cloth/water collection tank resistance/> ,Ω and membrane stack unit resistance/> ,Ω, membrane stack unit resistance/> Including acid chamber resistance, material chamber resistance, alkali chamber resistance, anion exchange membrane resistance, cation exchange membrane resistance and bipolar membrane resistance, determine the acid chamber leakage current differential operator/> 、/> ; S2, collection chamber cloth/water collection hole resistance ,Ω, chamber cloth/water collection tank resistance/> , Ω, determine the chamber leakage current differential operator/> 、/> ; S3, collect the resistance of alkali chamber cloth/water collection hole ,Ω; resistance of alkali chamber cloth/water collection tank/> , Ω; Determine the differential operator of the alkali chamber leakage current/> 、/> ; S4, the number of membrane stack units N; the sum of the acid chamber resistance and the anion exchange membrane resistance ,Ω; the sum of the resistance of the material chamber and the resistance of the cation exchange membrane/> ,Ω; the sum of the base chamber resistance and the bipolar membrane resistance/> ,Ω; input current I,A; the sum of the membrane potentials of the membrane stack units/> , the sum of the membrane potentials of the membrane stack units/> Contains the membrane potential of the anion exchange membrane, the membrane potential of the cation exchange membrane and the membrane potential of the bipolar membrane, V, to determine the leakage current flowing through the acid chamber/water collection tank at the first unit/> , A; leakage current flowing through the material chamber cloth/water collecting trough at the first unit/> , A; leakage current flowing through the alkali chamber cloth/water collection tank of the first unit/> , A; S5. Determine the leakage current flowing through the acid chamber/water collection tank at unit 2 , A; leakage current flowing through the material chamber cloth/water collection tank at the second unit/> , A; leakage current flowing through the alkali chamber/water collection tank of the second unit/> , A; S6. Determine the leakage current flowing through the acid chamber/water collection tank at unit K. , A; leakage current flowing through the material chamber cloth/water collection tank at unit K/> , A; leakage current flowing through the alkali chamber/water collection tank at unit K/> , A; S7. Determine the leakage current flowing through the acid chamber/water collection hole at unit K. , A; leakage current flowing through the material chamber cloth/water collection hole at the Kth unit/> , A; leakage current flowing through the alkali chamber/water collection hole at unit K/> , A; S8. Determine the effective current flowing through the effective area of the acid chamber at unit K. , A; effective current flowing through the effective area of the material chamber at the Kth unit/> , A; effective current flowing through the effective area of the alkali chamber at the Kth unit/> , A; In step S1, the acid chamber leakage current differential operator 、/> The calculation formula is as follows: ;(1); in, 、/> is the root of formula (1); In step S2, the chamber leakage current differential operator 、/> The calculation formula is as follows: ;(2); in, 、/> is the root of formula (2); In step S3, the alkali chamber leakage current differential operator 、/> The calculation formula is as follows: ; (3); in, 、/> is the root of formula (3); In step S4, the leakage current flowing through each compartment/water collection tank at the first unit is calculated as follows: ; (4); ; (5); ; (6); Among them, A ^-1 is the inverse matrix of matrix A; For/> ; /> For/> ; /> For/> ; /> for ; /> For/> ; /> For/> ; /> For/> ; For/> ; /> For/> ; In step S5, the calculation formula for the leakage current flowing through each compartment/water collection tank at the second unit is as follows: ; (7); In step S6, the calculation formula of the leakage current flowing through each compartment/water collection tank at the Kth unit is as follows: ;(8); ;(9); ; (10); In step S8, the effective current flowing through the effective area of each compartment at the Kth unit is calculated as follows: ; (14); ; (15); ; (16). 2. The current prediction method according to claim 1, characterized in that in step S7, the leakage current flowing through each compartment/water collection hole at the Kth unit is calculated as follows: ; (11); ; (12); ; (13).