A simulation modeling method for natural uranium extraction and purification system

Abstract

The present invention belongs to the technical field of extraction and purification of natural uranium in the nuclear fuel cycle, and specifically relates to a simulation modeling method for a natural uranium extraction and purification system. The parameter types of the extraction and purification system are determined and divided into process operation parameters and pulse column structural parameters; the process operation parameters are used as input operating variables, and the pulse column structural parameters are used as fixed quantities; the mass transfer models of the extraction column, washing column, and stripping column in the extraction and purification system are respectively established using the unit differential method; the mass transfer models are dimensionless; the dimensionless mass transfer models are solved, and a thermodynamic model of the uranyl nitrate extraction and purification process and a hydraulic model of the pulse column are established. The thermodynamic model and the hydraulic model are combined, that is, the extraction reaction process and the structural characteristics of the pulse column used in the extraction reaction process are combined. This method can realistically simulate the operating results of the natural uranium extraction and purification process, and simulate and calculate the operating results under different two-phase flow ratios, concentrations, acidities, and temperatures.

Description

Technical Field

[0001] The invention belongs to the technical field of extraction and purification of natural uranium in a nuclear fuel cycle, and particularly relates to a simulation modeling method for a natural uranium extraction and purification system. Background Art

[0002] With the development of intelligent industry and the advent of Industry 4.0, intelligent manufacturing has become a trend. The extraction and purification of natural uranium concentrate is a crucial step in the nuclear fuel cycle. The extraction-washing-stripping process removes metallic impurities from the uranyl nitrate solution, ensuring the quality of the final product. This process involves multiple reaction mechanisms and complex operations. To prevent material leakage and nuclear accidents, changes in process conditions are strictly controlled, making it impossible to conduct exploratory experiments to explore the limits of the extraction system.

[0003] Currently, there are no reports on establishing an accurate mathematical model to simulate the operation of industrial-grade extraction columns. Existing extraction column modeling is generally theoretical rather than modeling for real industrial-grade extraction columns. Its accuracy is poor, and it differs greatly from the operating results of industrially applied extraction columns, making it of little guidance for actual production.

[0004] The present invention provides a method for simulating the establishment of a simulation system for the operation of a natural uranium extraction and purification process. The method can simulate the operation of a natural uranium extraction system (extraction-washing-stripping process). The method can simulate the operation of an industrial-grade natural uranium extraction column, and the deviation between the model operation results and the actual results is small. Summary of the Invention

[0005] The purpose of the present invention is to provide a simulation modeling method for a natural uranium extraction and purification system. In combination with the structural characteristics of the pulse column, a matching hydraulic model is established for the extraction column, washing column, and stripping column, and then a thermodynamic model is simulated and established based on the chemical characteristics of the extraction process, washing process, and stripping process. The hydraulic model is combined with the thermodynamic model to comprehensively establish and produce a mathematical model of the uranyl nitrate purification process (extraction-washing-stripping). The operation results of the natural uranium extraction and purification process can be realistically simulated, and the operation results under different two-phase flow ratios, concentrations, acidity, and temperatures can be simulated and calculated. The operation results are real and reliable, with high precision. The calculation results simulated by the system are within 5% of the error of the actual extraction system operation results. The established simulation model can be used to explore process parameters, optimize process parameters, and can also be used to check abnormal working conditions during process operation and solve on-site problems. At the same time, it can also be used for training new process personnel and improving operational levels.

[0006] In order to achieve the above object, the technical solution adopted by the present invention is:

[0007] A simulation modeling method for a natural uranium extraction and purification system.

[0008] Step 1: Determine the parameter types of the extraction and purification system, which are divided into process operation parameters and pulse column structure parameters;

[0009] Step 2: Take the process operation parameters as input operating variables and the pulse column structure parameters as fixed quantities;

[0010] Step 3: Use the unit differential method to establish the mass transfer models of the extraction column, washing column, and stripping column in the extraction and purification system; and make the mass transfer models dimensionless;

[0011] Step 4: Solve the dimensionless mass transfer model to establish a thermodynamic model for the uranyl nitrate extraction and purification process and a hydraulic model for the pulse column. Combine the thermodynamic and hydraulic models to combine the extraction reaction process with the structural characteristics of the pulse column used in the extraction reaction process.

[0012] Step 5: Establish a thermodynamic model for the uranyl nitrate extraction and purification process;

[0013] ① Thermodynamic model of uranyl nitrate extraction process in extraction column:

[0014]

[0015] Among them, [U] ORG ——Concentration of uranyl nitrate in the extract, gU / L; [TBP] AQ ——The volume percentage of TBP in the extractant, [NO3] AQ ——nitric acidity in the extraction solution, mol / L; [U] AQ ——Uranyl nitrate concentration in the extraction solution, gU / L; T——Uranyl nitrate extraction process temperature, K;

[0016] ② Thermodynamic model of the washing process of uranyl nitrate in the washing column:

[0017]

[0018] Among them, [U] ORG ——Concentration of uranyl nitrate in the organic phase after washing, gU / L; [NO3] AQ ——nitric acid acidity in the washing solution, mol / L; [U] AQ ——Concentration of uranyl nitrate in the washing solution, gU / L;

[0019] ③ Thermodynamic model of uranyl nitrate stripping process in stripping column:

[0020]

[0021] Among them, [U] AQ——Concentration of uranyl nitrate in the stripping solution, gU / L; [NO3] ORG ——Acidity of the organic phase at the inlet of the pulse sieve plate stripping column, mol / L; [U] ORG ——Concentration of uranyl nitrate in the organic phase at the inlet of the pulse sieve plate stripping column, gU / L; T——Reaction temperature of the stripping process, °C;

[0022] Step 6: Establish the hydraulic model of the pulse column;

[0023] ① The dispersed phase holdup model of the pulse extraction column and pulse washing column is as follows:

[0024]

[0025]

[0026] Wherein, xd is the volume of dispersed phase; Af is the pulse intensity of pulse baffle extraction column, m / s; v ... pulse intensity of pulse baffle extraction column, m / s d ——dispersed phase velocity, m / s; v c ——continuous phase velocity, m / s; Δρ——density difference between dispersed phase and continuous phase, kg / m 3 ρ d ——Dispersed phase density, kg / m 3 ρ c ——continuous phase density, kg / m 3 ;μ d ——Viscosity of dispersed phase, Pas; μ c ——Continuous phase viscosity, Pas; α——Pulse baffle extraction column annular void ratio; γ——Dispersed phase surface tension, N / m; (Af) m ——Average pulse intensity of pulse baffle extraction column, m / s; g-gravitational acceleration, kg / N;

[0027] ②The dispersed phase holdup model of the pulse stripping column is as follows:

[0028] x d =1.1*10 6 *exp[50.56*|Af-(Af) m |]*v d 0.86 *(v c +v d ) 0.28 *Δρ- 0.3 *ρ d -0.93 *μ d 0.77

[0029] *α -0.56 *h -0.56 *0.55

[0030]

[0031] Among them, x d ——dispersed phase holdup; Af——pulse intensity of pulse sieve plate stripping column, m / s; v d ——dispersed phase velocity, m / s; v c ——continuous phase velocity, m / s; Δρ——density difference between dispersed phase and continuous phase, kg / m 3 ρ d ——Dispersed phase density, kg / m 3 ;μ d ——dispersed phase viscosity, Pas; α——pulse sieve plate stripping column sieve plate opening ratio; γ——dispersed phase surface tension, N / m; h——pulse sieve plate stripping column sieve plate spacing, m; (Af) m ——Average pulse intensity of pulse sieve plate stripping column m / s;

[0032] Step 7: Combine the mass transfer models corresponding to the extraction column, washing column, and stripping column with the corresponding thermodynamic model and hydraulic model to obtain the final accurate model of the uranyl nitrate extraction and purification system;

[0033] In the eighth step, the process operating parameters determined in the first step are introduced into the final accurate model of the uranyl nitrate extraction and purification system, and the Jung-Kutta method is used to solve the uranyl nitrate concentration results at the aqueous phase outlet and the organic phase outlet required for the model simulation results.

[0034] Step 9: Verify the calculation results, obtain the final calculation results for the outputs that meet the requirements, and return to the calculation again for those that do not meet the requirements.

[0035] The process operation parameters include the flow rate, concentration, and acidity of the pulse column aqueous phase inlet material, and the concentration and flow rate of the organic phase inlet material.

[0036] The structural parameters of the pulse column include the pulse column height and diameter.

[0037] By conducting uranyl nitrate extraction equilibrium experiments, the thermodynamic equilibrium data of uranyl nitrate was obtained, and the thermodynamic equilibrium equation of uranyl nitrate was established. Through planning and solving, the thermodynamic model of the uranyl nitrate extraction and purification process was established.

[0038] The beneficial effects achieved by the present invention are:

[0039] 1) This method has for the first time achieved the establishment of a mathematical model for the natural uranium extraction and purification system. The modeling method is highly accurate, with an error of less than 5% from the actual extraction system operation results.

[0040] 2) This patent describes for the first time a method for establishing a simulation model of an industrial-grade natural extraction column uranium purification system. It can simulate the operation of an industrial-grade natural uranium extraction and purification system rather than a simple theoretical simulation, with high reliability and small error.

[0041] 3) Through software simulation calculation, it has certain reference significance for optimizing equipment structure, equipment amplification, expanding production capacity, and theoretical research on uranium purification production line.

[0042] 4) The model established by this method has multiple controllable parameters and can simulate and calculate operating results under different two-phase flow ratios, concentrations, acidity, and temperatures. It has multiple functions such as process parameter exploration and optimization, process troubleshooting, and process personnel training. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] Figure 1 This is a flow chart of the simulation modeling method for a natural uranium extraction and purification system. DETAILED DESCRIPTION

[0044] The present invention will be described in detail below with reference to the accompanying drawings and specific embodiments.

[0045] A simulation modeling method for a natural uranium extraction and purification system. The specific process is as follows:

[0046] Step 1: Determine the parameters of the extraction and purification system, categorizing them into process operating parameters and pulse column structural parameters. Process operating parameters refer to those parameters that can be varied during the extraction and purification system design process to achieve process control. These parameters include the flow rate, concentration, and acidity of the pulse column aqueous inlet, and the concentration and flow rate of the organic phase inlet. Pulse column structural parameters in the extraction and purification system refer to parameters related to the pulse column's physical structure, such as height, diameter, and other geometric dimensions.

[0047] Step 2: Based on the classification in Step 1, process operating parameters are treated as input variables and used as operating variables in the entire extraction and purification system modeling process. The structural parameters of the pulse column are treated as fixed quantities and cannot be changed or modified once determined.

[0048] Step 3: Using the unit differential method, mass transfer models for the extraction column, wash column, and stripping column in the extraction and purification system were established. To ensure that process operating parameters are not included in the mass transfer model calculation, which complicates the model solution due to inconsistent units of the process operating parameters, the mass transfer model was dimensionless to eliminate the influence of different process parameter units, thus forming a dimensionless mass transfer model.

[0049] Step 4: Solve the dimensionless mass transfer model. In order to improve the precision and accuracy of the mass transfer model solution, a thermodynamic model of the uranyl nitrate extraction and purification process and a hydraulic model of the pulse column are specially established. The thermodynamic model and the hydraulic model are combined, that is, the extraction reaction process and the structural characteristics of the reactor (pulse column) used in the extraction reaction process are combined to improve the accuracy of the model.

[0050] Step 5: Establishment of thermodynamic model of uranyl nitrate extraction and purification process.

[0051] By conducting uranyl nitrate extraction equilibrium tests, the thermodynamic equilibrium data of uranyl nitrate was obtained, and the thermodynamic equilibrium equation of uranyl nitrate was established. Through planning and solving, the thermodynamic model was established. Therefore, corresponding thermodynamic equilibrium experiments were carried out for the three processes of extraction, washing, and stripping. Through experiments, the unique models of this patent were determined as follows. The proposal of this new mathematical model can effectively improve the accuracy of the operation process:

[0052] ④ Thermodynamic model of the extraction process of uranyl nitrate using the extraction column

[0053]

[0054] Among them, [U] ORG ——Concentration of uranyl nitrate in the extract, gU / L; [TBP] AQ ——The volume percentage of TBP in the extractant, [NO3] AQ ——nitric acidity in the extraction solution, mol / L; [U] AQ ——Uranyl nitrate concentration in the extraction solution, gU / L; T——Temperature of the uranyl nitrate extraction process, K.

[0055] ⑤ Thermodynamic model of the washing process of uranyl nitrate in washing column

[0056]

[0057] Among them, [U] ORG ——Concentration of uranyl nitrate in the organic phase after washing, gU / L; [NO3] AQ ——nitric acid acidity in the washing solution, mol / L; [U] AQ ——Concentration of uranyl nitrate in the washing solution, gU / L.

[0058] ⑥ Thermodynamic model of uranyl nitrate stripping process for stripping column

[0059]

[0060] Among them, [U] AQ ——Concentration of uranyl nitrate in the stripping solution, gU / L; [NO3] ORG——Acidity of the organic phase at the inlet of the pulse sieve plate stripping column, mol / L; [U] ORG ——Concentration of uranyl nitrate in the organic phase at the inlet of the pulse sieve plate stripping column, gU / L; T——Reaction temperature of the stripping process, °C.

[0061] Step 6: Establish the hydraulic model of the pulse column.

[0062] During the hydraulic modeling process, to ensure that the model is more suitable for the structure of the pulse column, models were created for the pulse extraction column, pulse washing column, and pulse stripping column, respectively. At the same time, the pulse column structural parameters corresponding to each column, determined in the first step, were incorporated to perform proprietary optimization of the hydraulic model. The dispersed phase holdup model in this hydraulic model is unique to this patent after optimization:

[0063] ③The dispersed phase holdup model of the pulse extraction column and pulse washing column is as follows:

[0064]

[0065]

[0066] Wherein, xd is the volume of dispersed phase; Af is the pulse intensity of pulse baffle extraction column, m / s; v ... pulse intensity of pulse baffle extraction column, m / s d ——dispersed phase velocity, m / s; v c ——continuous phase velocity, m / s; Δρ——density difference between dispersed phase and continuous phase, kg / m 3 ρ d ——Dispersed phase density, kg / m 3 ρ c ——continuous phase density, kg / m 3 ;μ d ——Viscosity of dispersed phase, Pas; μ c ——Continuous phase viscosity, Pas; α——Pulse baffle extraction column annular void ratio; γ——Dispersed phase surface tension, N / m; (Af) m ——Average pulse intensity of the pulse baffle extraction column, m / s; g-gravitational acceleration, kg / N.

[0067] ④ The dispersed phase holdup model of the pulse stripping column is as follows:

[0068] x d =1.1*10 6 *exp[50.56*|Af-(Af) m |]*v d 0.86 *(v c +v d ) 0.28 *Δρ -0.3 *ρd -0.93 *μ d 0.77

[0069] *α -0.56 *h -0.56 *0.55

[0070]

[0071] Among them, x d ——dispersed phase holdup; Af——pulse intensity of pulse sieve plate stripping column m / s; v d ——dispersed phase velocity m / s; v c ——continuous phase velocity m / s; Δρ——density difference between dispersed phase and continuous phase, kg / m 3 ρ d ——Dispersed phase density, kg / m 3 ;μ d ——dispersed phase viscosity, Pas; α——pulse sieve plate stripping column sieve plate opening ratio; γ——dispersed phase surface tension, N / m; h——pulse sieve plate stripping column sieve plate spacing, m; (Af) m ——Average pulse intensity of pulse sieve plate stripping column m / s.

[0072] Step 7: After completing the thermodynamic model of the uranyl nitrate extraction and purification process and the hydraulic model of the pulse column, the mass transfer models corresponding to the extraction column, washing column, and stripping column are combined with the corresponding thermodynamic model and hydraulic model to obtain the final accurate model of the uranyl nitrate extraction and purification system.

[0073] In the eighth step, the process operating parameters determined in the first step are brought into the final precise model of the uranyl nitrate extraction and purification system, and the Jung-Kutta method is used to solve the uranyl nitrate concentration results at the aqueous phase outlet and the organic phase outlet required for the model simulation results.

[0074] Step 9: After completing the calculation, verify the calculation results. For the output that meets the requirements, obtain the final calculation results. For those that do not meet the requirements, return them to the model calculation unit for recalculation.

[0075] The software model established by this simulation method has two types of inputs: the concentration, flow rate, acidity, and temperature of the pulse column's aqueous phase inlet; and the concentration and flow rate of the organic phase inlet. Correspondingly, the outputs also include two types: the concentration of the pulse column's aqueous phase; and the concentration of the organic phase at its outlet.

[0076] The model established by this method can be used to perform process simulation calculations on the extraction column, washing column or stripping column in the extraction and purification system separately, or it can be used to simulate the entire extraction and purification system. Therefore, in the process of model establishment, separate models of the extraction column, washing column and stripping column are established, and then the models are combined to enable the model to have the ability to perform independent and joint calculations. The model diagram is shown below. Figure 1 shown.

[0077] This system uses TBP-hydrogenated kerosene as the extractant and uranyl nitrate solution as the extraction solution. The system simulates the uranyl nitrate concentration distribution throughout the extraction-washing-stripping process for uranium concentrations in the extraction solution range of 0-450 g / L. The extraction-washing-stripping process employed is designed for industrial applications. The extraction and washing columns are annular pulsed baffle columns with diameters of 880 mm and 830 mm, respectively. The stripping column is a pulsed sieve plate column with a diameter of 1050 mm. The system consists of an input and output interface and a mathematical model backend. The simulated results are within 5% of the actual extraction system run time. Inputs include the aqueous phase inlet concentration, flow rate, acidity, and temperature at the extraction, washing, and stripping columns, as well as the organic phase inlet concentration, flow rate, and temperature at the extraction, washing, and stripping columns. Outputs include the aqueous and organic phase outlet concentrations and extraction yields at each column. The software system is written in Visual Basic Application (VBA) and can be flexibly modified and upgraded. The calculation results are clearly and intuitively output, including data tables and graphs. It has multiple functions, including process parameter exploration and optimization, process troubleshooting, and process personnel training.

Claims

1. A simulation modeling method for a natural uranium extraction and purification system, characterized by: Step 1: Determine the parameter types of the extraction and purification system, which are divided into process operation parameters and pulse column structure parameters; Step 2: Take the process operation parameters as input operating variables and the pulse column structure parameters as fixed quantities; Step 3: Use the unit differential method to establish the mass transfer models of the extraction column, washing column, and stripping column in the extraction and purification system; and make the mass transfer models dimensionless; Step 4: Solve the dimensionless mass transfer model to establish a thermodynamic model for the uranyl nitrate extraction and purification process and a hydraulic model for the pulse column. Combine the thermodynamic and hydraulic models to combine the extraction reaction process with the structural characteristics of the pulse column used in the extraction reaction process. Step 5: Establish a thermodynamic model for the uranyl nitrate extraction and purification process; ① Thermodynamic model of uranyl nitrate extraction process in extraction column: Among them, [U] ORG ——Concentration of uranyl nitrate in the extract, gU / L; [TBP] AQ ——The volume percentage of TBP in the extractant, [NO3] AQ ——nitric acidity in the extraction solution, mol / L; [U] AQ ——Uranyl nitrate concentration in the extraction solution, gU / L; T——Uranyl nitrate extraction process temperature, K; ② Thermodynamic model of the washing process of uranyl nitrate in the washing column: Among them, [U] ORG ——Concentration of uranyl nitrate in the organic phase after washing, gU / L; [NO3] AQ ——nitric acid acidity in the washing solution, mol / L; [U] AQ ——Concentration of uranyl nitrate in the washing solution, gU / L; ③ Thermodynamic model of uranyl nitrate stripping process in stripping column: Among them, [U] AQ ——Concentration of uranyl nitrate in the stripping solution, gU / L; [NO3] ORG ——Acidity of the organic phase at the inlet of the pulse sieve plate stripping column, mol / L; [U] ORG ——Concentration of uranyl nitrate in the organic phase at the inlet of the pulse sieve plate stripping column, gU / L; T——Reaction temperature of the stripping process, °C; Step 6: Establish the hydraulic model of the pulse column; ① The dispersed phase holdup model of the pulse extraction column and pulse washing column is as follows: Wherein, xd is the volume of dispersed phase; Af is the pulse intensity of pulse baffle extraction column, m / s; v ... pulse intensity of pulse baffle extraction column, m / s d ——dispersed phase velocity, m / s; v c ——continuous phase velocity, m / s; Δρ——density difference between dispersed phase and continuous phase, kg / m 3 ρ d ——Dispersed phase density, kg / m 3 ρ c ——continuous phase density, kg / m 3 ;μ d ——Viscosity of dispersed phase, Pas; μ c ——Continuous phase viscosity, Pas; α——Pulse baffle extraction column annular void ratio; γ——Dispersed phase surface tension, N / m; (Af) m ——Average pulse intensity of pulse baffle extraction column, m / s; g-gravitational acceleration, kg / N; ②The dispersed phase holdup model of the pulse stripping column is as follows: x d =1.1*10 6 *exp[50.56*|Off-(Off) m |]*v d 0.86 *(v c +v d ) 0.28 *Δρ -0.3 *ρ d -0.93 *μ d 0.77 *α -0.56 *h -0.56 *0.55 Among them, x d ——dispersed phase holdup; Af——pulse intensity of pulse sieve plate stripping column, m / s; v d ——dispersed phase velocity, m / s; v c ——continuous phase velocity, m / s; Δρ——density difference between dispersed phase and continuous phase, kg / m 3 ρ d ——Dispersed phase density, kg / m 3 ;μ d ——dispersed phase viscosity, Pas; α——pulse sieve plate stripping column sieve plate opening ratio; γ——dispersed phase surface tension, N / m; h——pulse sieve plate stripping column sieve plate spacing, m; (Af) m ——Average pulse intensity of pulse sieve plate stripping column m / s; Step 7: Combine the mass transfer models corresponding to the extraction column, washing column, and stripping column with the corresponding thermodynamic model and hydraulic model to obtain the final accurate model of the uranyl nitrate extraction and purification system; In the eighth step, the process operating parameters determined in the first step are introduced into the final accurate model of the uranyl nitrate extraction and purification system, and the Jung-Kutta method is used to solve the uranyl nitrate concentration results at the aqueous phase outlet and the organic phase outlet required for the model simulation results. Step 9: Verify the calculation results, obtain the final calculation results for the outputs that meet the requirements, and return to the calculation again for those that do not meet the requirements.

2. The simulation modeling method of the natural uranium extraction and purification system according to claim 1, characterized in that: The process operation parameters include the flow rate, concentration, and acidity of the pulse column aqueous phase inlet material, and the concentration and flow rate of the organic phase inlet material.

3. The simulation modeling method of the natural uranium extraction and purification system according to claim 1, characterized in that: The structural parameters of the pulse column include the pulse column height and diameter.

4. The simulation modeling method of the natural uranium extraction and purification system according to claim 1, characterized in that: By conducting uranyl nitrate extraction equilibrium experiments, the thermodynamic equilibrium data of uranyl nitrate was obtained, and the thermodynamic equilibrium equation of uranyl nitrate was established. Through planning and solving, the thermodynamic model of the uranyl nitrate extraction and purification process was established.

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