Method for establishing a prediction model for co2 mass transfer performance of organic amine solutions and prediction method

Abstract

The present application relates to a method for establishing a prediction model of CO2 mass transfer performance of an organic amine solution and a prediction method, water and an organic amine solution are used as absorbents, CO2 absorption experiments of mixed gas are carried out in a packed tower, and experimental data under N groups of different conditions are obtained; an equation group is established through the experimental data under N groups of different conditions and the values of the corresponding conditions, the equation group is solved, and the specific values of m'1-m'7 are obtained; and the total mass transfer coefficient K G a V of the organic amine solution under the condition is obtained. The prediction model established by the method of the present application has a very high matching degree with the target value in predicting the mass transfer performance, and compared with experience and semi-empirical formula, the prediction model exhibits very excellent prediction performance.

Description

Technical Field

[0001] The present invention relates to a method for establishing a prediction model for CO2 mass transfer performance of an organic amine solution and a prediction method. Background Art

[0002] In response to the greenhouse effect and ocean acidification issues of recent years, countries around the world have increasingly focused on CO2 capture technology. Large amounts of CO2 emissions primarily come from the combustion of fossil fuels, with coal-fired power plants being the primary source. Therefore, capturing and utilizing CO2 emitted by coal-fired power plants is a pressing issue.

[0003] Currently, compared to membrane separation and solid adsorbent separation methods, chemical absorption, primarily using organic amine solutions, has become the most promising CO2 capture method due to its mature technology, rapid absorption rate, and significant absorption effect. Commonly used amine solvents are mainly divided into three categories: primary amines, secondary amines, and tertiary amines. However, due to the significant limitations of using a single solvent, two solvents are often mixed to form a composite solvent to further improve CO2 absorption efficiency.

[0004] In industry, the absorption of CO2 by organic amines is usually carried out in packed towers. This is mainly due to the presence of fillers with high specific surface area, which promotes the contact between the solvent and the gas, thereby effectively improving the mass transfer performance. The absorption of CO2 by organic amine solutions is mainly explored using the double-membrane theory. When gas and liquid come into contact, a gas phase stagnation film and a liquid phase stagnation film, namely a gas film and a liquid film, exist at the interface between the gas phase and the liquid phase respectively. The CO2 in the gas phase enters the liquid phase through molecular diffusion, thereby causing mass transfer behavior, such as Figure 1 As shown. Currently, the volumetric total mass transfer coefficient K is usually used G a v To evaluate the mass transfer performance, it is necessary to accurately predict K G a v It is of great significance for evaluating the mass transfer performance of organic amine systems and the design of packed towers.

[0005] In existing studies, some methods for predicting the K of organic amine solvents in the process of CO2 absorption have been used. G a v Empirical or semi-empirical formulas have been explored, but the results show that there is still a large gap between the predicted value and the actual value, and the accuracy of the model still has a lot of room for improvement. At the same time, most models are not well applicable to the prediction of mass transfer performance of other solvents, and can only meet the experimental system under specific conditions, which has great limitations. The main reason is that when developing the mass transfer model, only the operating parameters are considered, and the chemical reactions that have a significant impact on the mass transfer behavior are ignored, which makes the model only applicable to specific solvent systems. How to further improve K G av The prediction accuracy is a blank in this industry and a technical direction that needs to be studied urgently. Summary of the Invention

[0006] In view of the shortcomings of the prior art, the present invention aims to provide a method for establishing a prediction model for the CO2 mass transfer performance of an organic amine solution and a method for predicting the CO2 mass transfer performance of an organic amine solution, so as to achieve K G a v accurate predictions.

[0007] In order to solve the above technical problems, the technical solutions of the present invention are as follows:

[0008] A method for establishing a prediction model for the CO2 mass transfer performance of an organic amine solution, wherein the organic amine solution is a mixed solution of an organic amine A and an organic amine B, wherein the organic amine A and the organic amine B are of different types, and the total number of hydrogen atoms on the nitrogen atoms of the organic amine A is less than the total number of hydrogen atoms on the nitrogen atoms of the organic amine B. The method comprises the following steps:

[0009] S1. Using water and organic amine solution as absorption liquid, conduct CO2 absorption experiments in mixed gas in a packed tower, and obtain N groups of experimental data under different conditions;

[0010] Wherein, N is a positive integer and N≥6; the factors of the condition include L, G, P CO2 , T, the experimental data include W A 、W B 、W total , K G a V ′ and K G a V水 , L is the feed flow rate of the absorption liquid (i.e. the flow rate of the absorption liquid when it enters the packed tower), G is the feed flow rate of the mixed gas (i.e. the flow rate of the mixed gas when it enters the packed tower), P CO2 is the initial partial pressure of CO2 in the mixed gas (i.e., the initial partial pressure of CO2 before the mixed gas enters the packed tower), T is the feed temperature of the absorption liquid, W A is the molar fraction of organic amine A in the organic amine solution, W B is the molar fraction of organic amine B in the organic amine solution, W total is the total molar fraction of organic amine A and organic amine B in the organic amine solution, K G a V ′ is the experimental value of the volumetric total mass transfer coefficient of the organic amine solution in the CO2 absorption mass transfer process under the corresponding conditions, K G a V水 is the experimental value of the volumetric total mass transfer coefficient of water in the CO2 absorption mass transfer process under corresponding conditions; the mixed gas consists of an inert gas and carbon dioxide;

[0011] In each group of conditions and experimental data, L, G, P CO2 , T, W A 、W B 、W total The values ​​of at least one of are different;

[0012] S2. Substituting the experimental data under the N groups of different conditions and the values ​​of the corresponding conditions into Formula I to establish a system of equations;

[0013]

[0014] Solve the above equations to obtain the specific values ​​of m′1 to m′7;

[0015] S3, the specific values ​​of m'1~m'7 obtained in S2, L, G, P under certain conditions CO2 , T and K G a V水 Substituting into formula I, the volume total mass transfer coefficient K of organic amine solutions with different molar compositions under this condition is obtained: G a V The prediction model is:

[0016]

[0017] Furthermore, in S1, K under different conditions is calculated according to formula ⅠⅠ G a V ′:

[0018]

[0019] Among them, Y A is the mole fraction of CO2 in the mixed gas at the corresponding tower height; Z is the tower height; P is the total pressure of the mixed gas; y A is the volume concentration of CO2 in the mixed gas at the corresponding tower height; y A * The volume concentration of CO2 in the mixed gas when absorption equilibrium is reached.

[0020] Furthermore, in S1, for certain conditions and organic amine solution, the K values ​​at M tower heights are calculated. G a V ′1, K G a V ′2, ..., K G a V ′M, and then calculate their geometric mean to obtain

[0021] Wherein, M is a positive integer, and 5≤M≤10.

[0022] Furthermore, in S1, K under different conditions is calculated according to formula ⅠⅠⅠ G a V水 :

[0023]

[0024] Among them, Y A is the mole fraction of CO2 in the mixed gas; Z is the tower height; P is the total pressure of the mixed gas; y A is the volume concentration of CO2 in the mixed gas at the corresponding tower height; y A * The volume concentration of CO2 in the mixed gas when absorption equilibrium is reached.

[0025] Furthermore, in S1, for certain conditions, the K values ​​of H tower height positions are calculated. G a V水 1. K G a V水 2. ..., K G a V水 H, and then calculate their geometric mean to obtain

[0026] Wherein, H is a positive integer, and 5≤H≤10.

[0027] Optionally, the organic amine A is one of 1DMA2P, DEEA, and DMEA.

[0028] Optionally, the organic amine B is one of EAE, HMDA, and AEEA.

[0029] Optionally, the molar fraction of the organic amine A is 0.02-0.08.

[0030] Optionally, the molar fraction of the organic amine B is 0.01-0.06.

[0031] Optionally, the diameter of the packed tower is 0.02-0.05 m, and the height of the packing is 0.85-2.00 m.

[0032] Based on the same inventive concept, the present invention also provides a method for predicting the CO2 mass transfer performance of an organic amine solution, comprising the following steps:

[0033] (1) Establish the volumetric total mass transfer coefficient K of organic amine solutions with different molar compositions under certain conditions by the method described above G a V ″Prediction model;

[0034] (2) The W of the organic amine solution to be predicted A 、W B 、Wtotal Substitute into the prediction model, solve, and obtain K G a V ″.

[0035] The present invention improves on the basis of Sheng model, and the prediction model established can more accurately predict the volume total mass transfer coefficient K of organic amine solutions with different molar compositions under certain conditions. G a V ′, the average absolute error AAD of the predicted value is no higher than 0.64%, which can be used to better evaluate the CO2 mass transfer performance of an organic amine solution with a certain molar composition, and can also be used for the development and selection of organic amine solutions.

[0036] The mass transfer performance of organic amine solutions predicted by the prediction model established by the method of the present invention has a high degree of match with the target value, and at the same time, compared with other empirical and semi-empirical formulas, it shows very excellent prediction performance. The prediction model of the present invention is suitable for the CO2 mass transfer performance K of organic amine solutions. G a v The prediction fills the gap in the field and can play an important role in related research and applications such as carbon capture and utilization.

[0037] Compared with the prior art, the present invention has the following advantages:

[0038] (1) The mass transfer performance predicted by the prediction model established by the method of the present invention has a high degree of match with the target value. At the same time, compared with other empirical and semi-empirical formulas, it shows very excellent prediction performance.

[0039] (2) The prediction model established by the method of the present invention has strong applicability and prediction accuracy, and the AAD of its prediction value is 0.64%.

[0040] (3) The prediction model established by the method of the present invention is applicable to the CO2 mass transfer performance K of organic amine solution G a v The prediction fills the gap in the field and can play an important role in related research and applications such as carbon capture and utilization. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] Figure 1 Schematic diagram of CO2 absorption by amine solution based on the dual-mode theoretical model. DETAILED DESCRIPTION

[0042] The present invention will be described in detail below with reference to the embodiments. It should be noted that the embodiments and features of the embodiments of the present invention can be combined with each other without conflict.

[0043] Example 1

[0044] A method for establishing a prediction model for CO2 mass transfer performance of an organic amine solution, wherein the organic amine solution (amine concentration is 3 mol / L) is a mixed solution of organic amine A (DEEA) and organic amine B (HMDA); comprising the following steps:

[0045] S1. Using water and organic amine solution as absorption liquid, the absorption experiment of CO2 in the mixed gas was carried out in a packed tower to obtain N groups of experimental data under different conditions. The relevant experimental data are specifically shown in Table 1;

[0046] Wherein, N is 20; the factors of the conditions include L, G, P CO2 , T, the experimental data include W A 、W B 、W total , K G a V ′ and K G a V水 , L is the flow rate of the absorption liquid, G is the flow rate of the mixed gas, P CO2 is the initial partial pressure of CO2 in the mixed gas, T is the feed temperature of the absorption liquid, W A is the molar fraction of organic amine A in the organic amine solution, W B is the molar fraction of organic amine B in the organic amine solution, W total is the total molar fraction of organic amine A and organic amine B in the organic amine solution, K G a V ′ is the experimental value of the volumetric total mass transfer coefficient of the organic amine solution in the CO2 absorption mass transfer process under the corresponding conditions, K G a V水 is the experimental value of the total volume mass transfer coefficient of water in the process of absorbing CO2 under the corresponding conditions; the mixed gas consists of inert gas (N2) and carbon dioxide; in each group of conditions and experimental data, L, G, P CO2 , T, W A 、W B 、W total The values ​​of at least one of are different;

[0047]

[0048]

[0049]

[0050] Among them, n A 、n B 、n W 、n total are the amounts of DEEA, HMDA, solvent (water) and total amines (DEEA+HMDA), respectively.

[0051] The mass transfer process of CO2 absorbed by organic amine solution and water was carried out in a double-mode theoretical model in a packed tower (tower diameter of 0.026m, packing height of 0.97m) loaded with DX-1000 structured packing (see Figure 1 ) simulation test;

[0052] Table 1 Experimental data under different conditions

[0053]

[0054]

[0055] S2. Substituting the N groups of experimental data and the values ​​of corresponding conditions into Formula I to establish a system of equations;

[0056]

[0057] The above equations were solved using Matlab software to obtain the specific values ​​of m′1 to m′7, see Table 2;

[0058] Table 2

[0059]

[0060] S3, the specific values ​​of m'1 to m'7 obtained in S2, L = 0.06 L / min, G = 5.3 L / min, P CO2 =15kPa, T=313K and K G a V水 =0.1266 kmol / (m 2 ·h·kPa) into formula I to obtain the volume total mass transfer coefficient K of organic amine solutions with different molar compositions under this condition. G a V ′’s prediction model:

[0061]

[0062] In S1, K under different conditions is calculated according to formula ⅠⅠ G a V ′:

[0063]

[0064] Among them, Y A is the mole fraction of CO2 in the mixed gas; Z is the tower height (i.e. the height distance from the lowest position of the packing to the target position); P is the total pressure of the mixed gas; y A is the volume concentration of CO2 in the mixed gas at the corresponding tower height; y A *The volume concentration of CO2 in the mixed gas when the absorption equilibrium is reached. By measuring the gas phase CO2 concentration at different packing layer heights and fitting it with the corresponding tower height, the fitting curve YZ is obtained. The derivative of Z can be used to obtain dY at different heights. A / dZ.

[0065] In S1, for certain conditions and organic amine solution, calculate K at 10 tower height positions. G a V ′1, K G a V ′2, ..., K G a V ′10, and then calculate their geometric mean to obtain This helps to obtain a more accurate K G a V ′.

[0066] In S1, K under different conditions is calculated according to formula ⅠⅠⅠ G a V水 :

[0067]

[0068] Among them, Y A is the mole fraction of CO2 in the mixed gas at the corresponding tower height; Z is the tower height; P is the total pressure of the mixed gas; y A is the volume concentration of CO2 in the mixed gas at the corresponding tower height; y A * The volume concentration of CO2 in the mixed gas when absorption equilibrium is reached.

[0069] In S1, for a certain condition, calculate K for 10 tower height positions. G a V水 1. K G a V水 2. ..., K G a V水 10, and then calculate their geometric mean to obtain This helps to obtain a more accurate K G a V水 .

[0070] The method for predicting the CO2 mass transfer performance of an organic amine solution comprises the following steps:

[0071] (1) The volumetric total mass transfer coefficient K of organic amine solutions with different molar compositions under certain conditions was established by the above method. G a V ″Prediction model;

[0072] (2) The W of the organic amine solution to be predictedA 、W B 、W total Substitute the prediction model into the above-mentioned model and use Matlab software in combination with the prediction model to calculate the K of organic amine solutions with different molar compositions. G a V ″ Make predictions and obtain K G a V ″, see Table 3.

[0073] Table 3 K of organic amine solutions with different molar compositions G a V ″Situation Table

[0074]

[0075] By fitting the prediction results, we can get the K predicted by the model. G a V ″ value and K calculated by experiment G a V The deviation (AAD) between the ' values ​​is only 0.64%.

[0076]

[0077] Where n is the number of experiments; p i and t i are the predicted value and experimental value of the i-th experiment respectively.

[0078] Similarly, the above method can be used to calculate the K of each group of conditions shown in Table 1. G a V The prediction results are shown in Table 4.

[0079] Table 4

[0080]

[0081] Comparative Example 1

[0082] Example 1 was repeated, except that: in S2, N groups of experimental data were substituted into formula ⅠⅠⅠ to establish the equation system:

[0083]

[0084] The above equations were solved using Matlab software to obtain the specific values ​​of m1 to m6, see Table 5;

[0085] Table 5

[0086]

[0087] S3, the specific values ​​of m1 to m6 obtained in S2, L = 0.06 L / min, G = 5.3 L / min, P CO2 =15kPa, T=313K are substituted into formula ⅠⅠⅠ to obtain the volume total mass transfer coefficient K of organic amine solutions with different molar compositions under this condition. G a V ″′ prediction model:

[0088]

[0089] Subsequently, Matlab software was used in combination with the prediction model to calculate the K values ​​of organic amine solutions with different molar compositions shown in Table 6. G a V The prediction results are shown in Table 6.

[0090] Table 6 K of organic amine solutions with different molar compositions G a V ″′ Situation Table

[0091]

[0092] By fitting the prediction results, we can get the K predicted by the above model. G a V The K value calculated by experiment G a V The deviation between the ' values ​​is 3.7%.

[0093] From the calculation results, the deviation between the predicted value and the experimental value is not large, but the error between the predicted value and the experimental value is still quite obvious. G a V The calculation results of the relationship between the variables are not very accurate.

[0094] By comparison, the prediction model of Example 1 is effective for K G a V The prediction results of the Sheng model have been greatly improved compared with the improved Sheng model, and the error of the calculation results has been greatly reduced. It can be seen that the prediction model established by the method of the present invention can more accurately predict the K of organic amine solution. G a V .

[0095] In subsequent actual predictions, substitute the K of the water mass transfer process under the prediction conditions G a V水 The K of organic amine solutions with different molar compositions under these conditions can be predicted by using the value G a V , under the conditions of fixed L, P, T, G, etc., obtain K under these conditionsG a V水 After that, the K of organic amine solutions with different molar compositions under this condition can be predicted. G a V Therefore, the prediction process can be simplified, and the K of a mixed amine solution of two organic amines under different molar ratios can be easily determined. G a V , in order to determine the best ratio and facilitate research and development or production.

[0096] The contents illustrated in the above embodiments should be understood as these embodiments are only used to more clearly illustrate the present invention, and are not used to limit the scope of the present invention. After reading the present invention, various equivalent modifications of the present invention by those skilled in the art shall fall within the scope defined by the claims attached to this application.

Claims

1. A method for establishing a prediction model for CO2 mass transfer performance of an organic amine solution, wherein the organic amine solution is a mixed solution of an organic amine A and an organic amine B, the organic amine A and the organic amine B are of different types, and the total number of hydrogen atoms on the nitrogen atoms of the organic amine A is less than the total number of hydrogen atoms on the nitrogen atoms of the organic amine B; characterized in that: The steps include: S1. Using water and organic amine solution as absorption liquid, conduct CO2 absorption experiments in mixed gas in a packed tower, and obtain N groups of experimental data under different conditions; Wherein, N is a positive integer and N≥6; the factors of the condition include L, G, P CO2 , T, the experimental data include W A 、W B 、W total , K G a V ′ and K G a V水 , L is the feed flow rate of the absorption liquid, G is the feed flow rate of the mixed gas, P CO2 is the initial partial pressure of CO2 in the mixed gas, T is the feed temperature of the absorption liquid, W A is the molar fraction of organic amine A in the organic amine solution, W B is the molar fraction of organic amine B in the organic amine solution, W total is the total molar fraction of organic amine A and organic amine B in the organic amine solution, K G a V ′ is the experimental value of the volumetric total mass transfer coefficient of the organic amine solution in the CO2 absorption mass transfer process under the corresponding conditions, K G a V水 is the experimental value of the total volume mass transfer coefficient of water in the process of absorbing CO2 under the corresponding conditions; the mixed gas consists of inert gas and carbon dioxide; in each group of conditions and experimental data, L, G, P CO2 , T, W A 、W B 、W total The values ​​of at least one of are different; S2. Substituting the experimental data under the N groups of different conditions and the values ​​of the corresponding conditions into Formula I to establish a system of equations; Solve the above equations to obtain the specific values ​​of m′1 to m′7; S3, the specific values ​​of m'1~m'7 obtained in S2, L, G, P under certain conditions CO2 , T and K G a V水 Substituting into formula I, the volume total mass transfer coefficient K of organic amine solutions with different molar compositions under this condition is obtained: G a V The prediction model is:

2. The method according to claim 1, characterized in that In S1, K under different conditions is calculated according to formula ⅠⅠ G a V ′: Among them, Y A is the mole fraction of CO2 in the mixed gas at the corresponding tower height; Z is the tower height; P is the total pressure of the mixed gas; y A is the volume concentration of CO2 in the mixed gas at the corresponding tower height; y A * The volume concentration of CO2 in the mixed gas when absorption equilibrium is reached.

3. The method according to claim 2, characterized in that In S1, for certain conditions and organic amine solution, calculate the K of M tower height positions. G a V ′1, K G a V ′2, ..., K G a V ′M, and then calculate their geometric mean to obtain Wherein, M is a positive integer, and 5≤M≤10.

4. The method according to claim 1, wherein In S1, K under different conditions is calculated according to formula ⅠIII. G a V水 : Among them, Y A is the mole fraction of CO2 in the mixed gas; Z is the tower height; P is the total pressure of the mixed gas; y A is the volume concentration of CO2 in the mixed gas at the corresponding tower height; y A * The volume concentration of CO2 in the mixed gas when absorption equilibrium is reached.

5. The method according to claim 4, characterized in that In S1, for a certain condition, calculate K of H tower height positions G a V水 1. K G a V水 2. ..., K G a V水 H, and then calculate their geometric mean to obtain Wherein, H is a positive integer, and 5≤H≤10.

6. A method for predicting the CO2 mass transfer performance of an organic amine solution, characterized in that: The steps include: (1) Establishing the volume total mass transfer coefficient K of organic amine solutions with different molar compositions under certain conditions by the method described in any one of claims 1 to 5 G a V ″Prediction model; (2) The W of the organic amine solution to be predicted A 、W B 、W total Substitute into the prediction model, solve, and obtain K G a V ″.

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