Method for constructing multi-effect evaporation model based on counterflow heat exchange mechanism and related equipment

Abstract

A multi-effect evaporation model construction method based on counterflow heat exchange mechanism and related equipment relate to the technical field of evaporator evaporation model. In the method, a consistent evaporation model of the evaporator is established based on the material balance principle, and a multi-effect consistent evaporation model is obtained by cascading the consistent evaporation model based on a preset evaporation effect level. A simplified function ignoring the volume change caused by the mixing of solutions with different densities is constructed. A relationship function is constructed, in which the amount of steam is positively correlated with the heat transfer and negatively correlated with the density of the liquid. The multi-effect evaporation model is obtained by simultaneously solving the multi-effect consistent evaporation model, the simplified function and the relationship function. The multi-effect evaporation model is output, so that the industrial site can refer to the multi-effect evaporation model to regulate and control the evaporation process. The multi-effect evaporation model can accurately reflect the dynamic characteristics of the multi-effect evaporation process and has high accuracy, which can provide strong support for accurate control of the industrial site.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of evaporator evaporation model, and particularly relates to a multi-effect evaporation model construction method based on countercurrent heat exchange mechanism and related equipment. BACKGROUND

[0002] Evaporation is a method of using heating to make the volatile solvent in the dilute solution containing non-volatile solute partially vaporize in the boiling state, so as to realize the concentration of the solution. The operation is widely used in non-ferrous metallurgy, food, medicine, chemical industry, seawater desalination and other fields. The essence is the heat transfer process of shell side vapor condensation and tube side liquid boiling, and the vaporization rate of the solvent completely depends on the heat transfer.

[0003] The driving force of the evaporation process comes from the heat brought by the new steam, and the new steam is converted from electric energy or chemical energy into heat energy to supply the operation of the evaporation process by the power plant, boiler or other ways. The new steam needs to be controlled based on the actual process in the industrial field, and is also a decisive factor of the energy consumption and steam consumption of the evaporation process. The evaporation model can accurately describe the behavior of the material liquid in the evaporation process, and is of great significance to realize the optimization control of the evaporation process, guide the production of enterprises and realize energy saving and consumption reduction.

[0004] However, in some factories, in order to improve the utilization rate of heat and speed up the concentration process of the solution, the evaporation process in the industrial field is often composed of multiple-effect evaporators in series, and the countercurrent feeding process is adopted. For example, five-effect countercurrent evaporation process (reference Figure 2 ), the material liquid is heated by an external heat source to reach the boiling state, and the concentrated material liquid is discharged to the next effect for further concentration. The separated water vapor, i.e. secondary steam, is supplied to the next effect as a heat source. For the material liquid, the raw liquid enters the 5-effect evaporator, and passes through the 4-effect, 3-effect, 2-effect in turn, and is discharged at the 1-effect. The density and temperature of the material liquid continuously increase along the flow direction. For the steam, the new steam is introduced into the 1-effect evaporator, the secondary steam of the 1-effect heats the 2-effect, the secondary steam of the 2-effect heats the 3-effect, the secondary steam of the 3-effect heats the 4-effect, the secondary steam of the 4-effect heats the 5-effect, and the secondary steam of the 5-effect is introduced into the condenser to maintain the vacuum degree of the entire evaporation system, so as to ensure the smooth progress of the evaporation process.

[0005] However, the related art is to establish a consistent model of a single evaporator, and to obtain a consistent cascade model of a multi-effect evaporation process through series connection. Therefore, there is no evaporation model that can accurately reflect the countercurrent heat exchange and mass transfer characteristics of each evaporation unit in the multi-effect evaporator.

[0006] Because in the multiple-effect evaporator, the temperature of the steam gradually decreases along the steam flow direction, and the heat carried also gradually decreases. Therefore, in the multiple-effect evaporation process, the density, temperature, and heat transferred of the material liquid in each evaporator are different, which are closely related to heat and mass transfer, which will lead to individual differences in the heat transfer performance of each evaporator. However, the consistency cascade model in the related art mainly establishes a mechanism model according to process parameters such as flow rate and density, and ignores the effect of energy flow on the change of the state of the material liquid in the evaporation process. Therefore, the consistency cascade model cannot accurately describe the heat and mass transfer behavior of the material liquid in each counter-flow evaporator, and cannot accurately reflect the dynamic characteristics of the process, resulting in an inaccurate model, and further based on the model The control of the scene is also difficult to accurately control the scene, which will lead to the increase of energy consumption and steam consumption, and even the waste or unreasonable use of resources and energy (electricity or chemical energy, heat energy, and evaporation device). Light will increase the production cost, heavy will damage the evaporation equipment, and even cause safety hazards. SUMMARY

[0007] The present application provides a multiple-effect evaporation model construction method based on counter-flow heat exchange mechanism and related equipment, which is used to accurately describe the heat and mass transfer behavior of the material liquid in each counter-flow evaporator, so as to control the scene based on the model. The control provides strong support for the accurate control of the industrial scene.

[0008] In a first aspect, the present application provides a multiple-effect evaporation model construction method based on counter-flow heat exchange mechanism, comprising: establishing a consistency evaporation model of the evaporator based on the material balance principle, and obtaining a multiple-effect consistency evaporation model based on a preset evaporation effect level number cascade consistency evaporation model;

[0009] A simplified function that ignores the volume change caused by the mixing of solutions with different densities is constructed;

[0010] A relationship function is constructed, in which the steam amount is positively correlated with the heat transfer amount, and is negatively correlated with the density of the material liquid;

[0011] The multiple-effect evaporation model is obtained by simultaneously solving the multiple-effect consistency evaporation model, the simplified function, and the relationship function;

[0012] The multiple-effect evaporation model is output, so that the industrial scene can refer to the multiple-effect evaporation model to control the evaporation process.

[0013] In the above embodiment, by constructing the relationship function, it is clear that the steam water amount is positively correlated with the heat transfer amount and negatively correlated with the density of the material liquid. The relationship function fully considers the key role of energy flow in the state change of the material liquid in the evaporation process, can accurately describe the heat and mass transfer behavior of the material liquid in each effect evaporator, and accurately reflect the dynamic characteristics of the multi-effect evaporation process. The multi-effect evaporation model established based on the relationship function has high accuracy and can provide strong support for accurate control in industrial sites. Meanwhile, the simplified function which ignores the volume change caused by the mixing of solutions with different densities is constructed, which can reduce the calculation complexity and improve the practicability of the model while ensuring the accuracy of the model.

[0014] In combination with some embodiments of the first aspect, in some embodiments, the step of constructing the relationship function in which the steam water amount is positively correlated with the heat transfer amount and negatively correlated with the density of the material liquid specifically includes:

[0015] The relationship function is constructed, and the steam water amount is the ratio of the product of the heat transfer amount and the heat transfer amount factor to the product of the density of the material liquid and the density of the material liquid factor.

[0016] In the above embodiment, when constructing the relationship function, the steam water amount is expressed as the ratio of the product of the heat transfer amount and the heat transfer amount factor to the product of the density of the material liquid and the density of the material liquid factor, so as to quantitatively describe the influence degree of the heat transfer amount and the density of the material liquid on the steam water amount, and reflect the correlation between them. At the same time, by reasonably setting the values of the two factors, the weights of the heat transfer amount and the density of the material liquid in the relationship function can be adjusted, so that the model can more accurately reflect the actual multi-effect evaporation process.

[0017] In combination with some embodiments of the first aspect, in some embodiments, after the step of obtaining the multi-effect evaporation model by simultaneously solving the multi-effect consistency evaporation model, the simplified function and the relationship function, the method further includes:

[0018] Adjusting the values of all the heat transfer amount factors and the density of the material liquid factors within a preset number of iterations, and obtaining the difference between the simulation data calculated by the multi-effect evaporation model and the actual data;

[0019] When the difference is smallest, determining the values of all the heat transfer amount factors and the density of the material liquid factors.

[0020] In the above embodiment, by adjusting the values of the heat transfer amount factors and the density of the material liquid factors within a preset number of iterations, and comparing the difference between the model calculation results and the actual data, the dynamic optimization of the model parameters is realized. When the difference is smallest, the values of the heat transfer amount factors and the density of the material liquid factors can make the simulation results of the model closest to the actual situation, to achieve the global optimal solution. This iterative optimization process can significantly improve the accuracy of the multi-effect evaporation model, so that it can better describe the behavior of the material liquid in the evaporation process.

[0021] With reference to some embodiments of the first aspect, in some embodiments, the step of constructing the relationship function in which the steam loss amount is positively correlated with the heat transfer amount and negatively correlated with the density of the material liquid specifically comprises:

[0022] The relationship function is constructed in which the steam loss amount is the ratio of a heat transfer amount function and a material liquid density function, the heat transfer amount function is determined by the product of the heat transfer amount and a heat transfer amount coefficient, and an additional heat transfer amount constant is added to the product, and the material liquid density function is determined by the product of the density of the material liquid and a material liquid density coefficient, and an additional material liquid density constant is added to the product.

[0023] In the above embodiments, when constructing the relationship function, the expression forms of the heat transfer amount function and the material liquid density function are further refined. In addition to introducing the heat transfer amount coefficient and the material liquid density coefficient to describe the influence degree of the heat transfer amount and the density of the material liquid, the heat transfer amount constant term and the material liquid density constant term are also added to the function. By adjusting the numerical value of the constant term, the output result of the heat transfer amount function and the material liquid density function can be fine-tuned while keeping the heat transfer amount coefficient and the material liquid density coefficient unchanged, and then the model can be locally optimized without changing the overall form of the function, which is helpful to further improve the model precision.

[0024] With reference to some embodiments of the first aspect, in some embodiments, after the step of obtaining the multi-effect evaporation model by simultaneously combining the multi-effect consistency evaporation model, the simplified function, and the relationship function, the method further comprises:

[0025] adjusting the numerical values of all the heat transfer amount coefficients, heat transfer amount constants, material liquid density coefficients, and material liquid density constants within a preset number of iterations, and obtaining the difference between the simulation data calculated by the multi-effect evaporation model and the actual data;

[0026] when the difference is the smallest, determining the numerical values of all the heat transfer amount coefficients, heat transfer amount constants, material liquid density coefficients, and material liquid density constants.

[0027] In the above embodiments, by adjusting the numerical values of these parameters within a preset number of iterations and comparing the difference between the model calculation result and the actual data, dynamic optimization of each parameter in the relationship function can be realized. Through iterative optimization, the best parameter combination can be selected in part selection, and the numerical values of each parameter at the time when the difference is the smallest are obtained. Compared with optimizing a certain type of parameter alone, this comprehensive optimization method can more comprehensively consider the relationship between the parameters, so that the multi-effect evaporation model reaches the optimal solution as a whole, improves the precision of the multi-effect evaporation model, and makes it more accurately reflect / describe the behavior of the material liquid in the evaporation process.

[0028] With reference to some embodiments of the first aspect, in some embodiments, the step of establishing the consistency evaporation model of the evaporator based on the material balance principle specifically comprises:

[0029] According to the feed liquid amount, the inlet feed liquid mass flow rate, the outlet feed liquid mass flow rate and the steam water amount, a balance equation is constructed, and the balance equation is:

[0030]

[0031] In the formula, M i is the feed liquid amount in the i-th evaporator, G in,i is the inlet feed liquid mass flow rate of the i-th evaporator, G out,i is the outlet feed liquid mass flow rate of the i-th evaporator, V i is the steam water amount of the i-th evaporator;

[0032] An analytical equation of the feed liquid amount, the inlet feed liquid mass flow rate and the outlet feed liquid mass flow rate is constructed, and the analytical equation is:

[0033] M i = ρ i A i h i

[0034] G in,i = ρ in,i F in,i

[0035] G out,i = ρ i F out,i

[0036] In the formula, M i is the feed liquid amount in the i-th evaporator, ρ i is the feed liquid density of the i-th evaporator, A i is the effective cross-sectional area of the i-th evaporator, h i is the liquid level of the i-th evaporator, G in,i is the inlet feed liquid mass flow rate of the i-th evaporator, ρ in,i is the inlet feed liquid density of the i-th evaporator, F in,i is the inlet feed liquid volume flow rate of the i-th evaporator, G out,i is the outlet feed liquid mass flow rate of the i-th evaporator, F out,i is the outlet feed liquid volume flow rate of the i-th evaporator;

[0037] The consistent evaporation model is obtained by combining the analytical equation and the balance equation, and the consistent evaporation model is:

[0038]

[0039] In the formula, ρ i is the feed liquid density of the i-th evaporator, t is time, h iLiquid level of the i-th evaporator, A i Effective cross-sectional area of the i-th evaporator, F in,i Inlet feed liquid density of the i-th evaporator, F in,i Inlet feed liquid volumetric flow rate of the i-th evaporator, F out,i Outlet feed liquid volumetric flow rate of the i-th evaporator, V i Evaporated water amount of the i-th evaporator.

[0040] In the above embodiments, the balance equation accurately describes the dynamic balance relationship of the material in the multi-effect evaporator based on the law of conservation of mass. By introducing the feed liquid amount, the real-time inventory change of the material in the evaporator can be reflected; the inlet and outlet feed liquid mass flow rates reflect the input and output processes of the material; the introduction of the evaporated water amount considers the influence of the evaporation process on the material balance. The analytical equation introduces key parameters such as feed liquid density, evaporator effective cross-sectional area, liquid level, and feed liquid volumetric flow rate to describe the material characteristics of the multi-effect evaporation process. Among them, the introduction of the feed liquid density and the liquid level reflects the influence of the material properties and the geometric structure of the evaporator on the material inventory; the inlet feed liquid density and the volumetric flow rate determine the input rate of the material; and the outlet feed liquid volumetric flow rate reflects the output process of the material.

[0041] In combination with some embodiments of the first aspect, in some embodiments, the simplified function is:

[0042]

[0043] In the formula, h i Liquid level of the i-th evaporator, t is time, A i Effective cross-sectional area of the i-th evaporator, F in,i Inlet feed liquid volumetric flow rate of the i-th evaporator, F out,i Outlet feed liquid volumetric flow rate of the i-th evaporator, V i Evaporated water amount of the i-th evaporator, F w Density of water;

[0044] The multi-effect evaporation model is:

[0045]

[0046] In the formula, F i Feed liquid density of the i-th evaporator, t is time, A i Effective cross-sectional area of the i-th evaporator, h i Liquid level of the i-th evaporator, F in,i Inlet feed liquid volumetric flow rate of the i-th evaporator, F in,i Inlet feed liquid density of the i-th evaporator, F i Outlet feed liquid density of the i-th evaporator, Qi heat transfer amount of the i th evaporator, a i heat transfer coefficient of the i th evaporator, b i heat transfer constant of the i th evaporator, c i feed liquid density coefficient of the i th evaporator, d i feed liquid density constant of the i th evaporator, p w density of water.

[0047] In the above embodiment, on the basis of the consistency evaporation model, a simplified processing of ignoring the difference in feed liquid density is further introduced. Considering that there may be a difference in feed liquid density between different effect evaporators, directly using these feed liquid volume flow rates for material balance calculation may introduce errors. In order to simplify the complexity of the model and improve the calculation efficiency, the volume change caused by the density difference is appropriately ignored in the modeling process. Although this simplification sacrifices some accuracy, it highlights the main research problem of the model, making the material balance relationship clearer and easier to solve. Through reasonable simplifying assumptions, the calculation amount and time cost can be greatly reduced while ensuring the practicability of the model.

[0048] In a second aspect, the embodiments of the present application provide a multi-effect evaporation model construction system based on the counterflow heat exchange mechanism, which comprises one or more processors and a memory.

[0049] The memory is coupled to the one or more processors, and the memory is configured to store computer program code comprising computer instructions, and the one or more processors are configured to invoke the computer instructions to enable the multi-effect evaporation model construction system based on the counterflow heat exchange mechanism to perform the method described in the first aspect and any possible implementation manner of the first aspect.

[0050] In a third aspect, the embodiments of the present application provide a computer program product comprising instructions, which, when executed on a server, enable the server to perform the method described in the first aspect and any possible implementation manner of the first aspect.

[0051] In a fourth aspect, the embodiments of the present application provide a computer readable storage medium comprising instructions, which, when executed on a multi-effect evaporation model construction system based on the counterflow heat exchange mechanism, enable the multi-effect evaporation model construction system based on the counterflow heat exchange mechanism to perform the method described in the first aspect and any possible implementation manner of the first aspect.

[0052] It can be understood that the multi-effect evaporation model construction system based on the counter-flow heat exchange mechanism provided in the second aspect, the computer program product provided in the third aspect, and the computer storage medium provided in the fourth aspect are all used to execute the multi-effect evaporation model construction method based on the counter-flow heat exchange mechanism provided in the embodiments of the present application. Therefore, the beneficial effects that can be achieved are referable to the beneficial effects in the corresponding method, which will not be repeated here.

[0053] The one or more technical solutions provided in the embodiments of the present application have at least the following technical effects or advantages:

[0054] 1. The multi-effect evaporation model construction method based on the counter-flow heat exchange mechanism provided in the present application explicitly determines the quantitative relationship between the steam production and the heat transfer, which is positively correlated with the heat transfer and negatively correlated with the density of the feed liquid, by constructing a relationship function. This relationship function fully considers the key role of energy flow in the state change of the feed liquid in the evaporation process, can accurately describe the heat and mass transfer behavior of the feed liquid in each effect evaporator, and accurately reflects the dynamic characteristics of the multi-effect evaporation process. The multi-effect evaporation model established based on the relationship function has high accuracy and can provide strong support for accurate control in industrial sites. Meanwhile, a simplified function that ignores the volume change caused by the mixing of solutions with different densities is constructed, which can reduce the calculation complexity and improve the practicability of the model while ensuring the accuracy of the model.

[0055] 2. The multi-effect evaporation model construction method based on the counter-flow heat exchange mechanism provided in the present application realizes dynamic optimization of the model parameters by adjusting the values of the heat transfer factor and the feed liquid density factor within a preset number of iterations and comparing the differences between the model calculation results and the actual data. When the difference is smallest, the values of the heat transfer factor and the feed liquid density factor determined can make the simulation results of the model closest to the actual situation to achieve the global optimal solution. This iterative optimization process can significantly improve the accuracy of the multi-effect evaporation model and enable it to better describe the behavior of the feed liquid in the evaporation process.

[0056] 3. The multi-effect evaporation model construction method based on the counter-flow heat exchange mechanism provided in the present application realizes dynamic optimization of the parameters in the relationship function by adjusting the values of these parameters within a preset number of iterations and comparing the differences between the model calculation results and the actual data. Through iterative optimization, the best parameter combination can be selected from the partial selection to obtain the values of each parameter when the difference is smallest. Compared with optimizing a certain type of parameter alone, this comprehensive optimization method can more comprehensively consider the relationship between parameters, enabling the multi-effect evaporation model to achieve an optimal solution as a whole and improving the accuracy of the multi-effect evaporation model, which enables it to better describe the behavior of the feed liquid in the evaporation process. BRIEF DESCRIPTION OF DRAWINGS

[0057] Figure 1A flowchart of the method for constructing the multi-effect evaporation model based on the counterflow heat exchange mechanism is provided in the present application.

[0058] Figure 2 A five-effect counterflow evaporation process diagram is provided in the present application.

[0059] Figure 3 A working principle diagram of the tubular falling film evaporator is provided in the present application.

[0060] Figure 4 A comparison diagram of the multi-effect evaporation model provided in the related art and the multi-effect evaporation model constructed in the present application is provided.

[0061] Figure 5 A lower flowchart of the method for constructing the multi-effect evaporation model based on the counterflow heat exchange mechanism is provided in the present application.

[0062] Figure 6 Another lower flowchart of the method for constructing the multi-effect evaporation model based on the counterflow heat exchange mechanism is provided in the present application.

[0063] Figure 7 A schematic diagram of the entity device of the multi-effect evaporation model construction system based on the counterflow heat exchange mechanism is provided in the present application. DETAILED DESCRIPTION

[0064] The terms used in the following embodiments of the present application are only for the purpose of describing specific embodiments and are not intended to be limiting of the present application. As used in the specification and the appended claims of the present application, the singular forms "a," "an" and "the" are intended to include both singular and plural forms, unless the context clearly indicates otherwise. It will be further understood that the terms "and / or" as used herein refers to any or all possible combinations of one or more of the associated listed items.

[0065] Hereinafter, the terms "first" and "second" are only for the purpose of description, and cannot be understood as implying or suggesting relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined with "first" and "second" can explicitly or implicitly include one or more of the features, and in the description of the embodiments of the present application, the meaning of "a plurality of" is two or more, unless otherwise specified.

[0066] For the convenience of understanding, the professional terms appearing in the text will be explained as follows:

[0067] 1. Counter-current heat exchange mechanism: Counter-current heat exchange refers to the process in which two fluids (usually a hot fluid and a cold fluid) enter the heat exchanger from opposite directions and flow in opposite directions, thereby exchanging heat. Under this flow pattern, the outlet temperature of the hot fluid can be lower than that of the cold fluid, thus achieving higher heat exchange efficiency.

[0068] 2. Multi-Effect Evaporator: A multi-effect evaporator is a device that utilizes multiple evaporation and condensation processes to achieve continuous evaporation and concentration of solutions. It consists of multiple evaporators connected in series, each evaporator being called an "effect". The first-effect evaporator is heated by high-temperature steam, and the resulting secondary steam enters the next-effect evaporator as a heating source, and so on.

[0069] 3. Fresh Steam: Fresh steam specifically refers to the power steam provided by an external heat source (such as a boiler, power plant, or other process) to drive the operation of the entire multi-effect evaporation system. That is, the steam entering the multi-effect evaporator; in this application, it refers to the steam introduced into the single-effect evaporator.

[0070] To facilitate understanding, the following will explain the application scenarios of the multi-effect evaporation model construction method based on countercurrent heat transfer mechanism provided in this application, as well as the shortcomings of related models in these scenarios.

[0071] This plant needs to utilize a multi-effect evaporation model to optimize and adjust the supply of fresh steam. The usual practice is to select the outlet liquid density of a single-effect evaporator (obtained through model calculations) as the control target and adjust the fresh steam based on its deviation from the theoretical value. However, related technologies typically establish consistent models for individual evaporators, which are then connected in series to obtain a consistent cascade model of the multi-effect evaporation process. Therefore, control based on this model is difficult to precisely manage on-site, leading to increased energy and steam consumption, and even waste or inefficient use of resources and energy (electrical, chemical, or thermal energy, as well as the evaporation equipment). This can range from increasing production costs to damaging evaporation equipment and even posing safety hazards.

[0072] To facilitate understanding, the reasons for the aforementioned defects will be further explained below.

[0073] Taking the five-effect countercurrent evaporation process as an example (reference) Figure 2), the feed liquid in the evaporator is heated by an external heat source, the feed liquid absorbs heat to reach a boiling state, and the concentrated feed liquid is discharged to the previous effect for further concentration. The separated water vapor, i.e. secondary steam, is supplied to the next effect as a heat source. For the feed liquid, the original evaporation liquid enters the 5th evaporator, and then passes through the 4th, 3rd, 2nd and 1st evaporators in sequence. The density and temperature of the feed liquid increase along the flow direction. For the steam, the new steam enters the 1st evaporator, the secondary steam of the 1st evaporator heats the 2nd evaporator, the secondary steam of the 2nd evaporator heats the 3rd evaporator, the secondary steam of the 3rd evaporator heats the 4th evaporator, the secondary steam of the 4th evaporator heats the 5th evaporator, and the secondary steam of the 5th evaporator is introduced into the condenser to maintain the vacuum degree of the entire evaporation system, thereby ensuring the smooth progress of the evaporation process.

[0074] However, in the multi-effect evaporator, the temperature of the steam gradually decreases along the flow direction, and the heat carried also gradually decreases. Therefore, the density, temperature, and heat transferred of the feed liquid in each evaporator are different in the multi-effect evaporation process, which leads to individual differences in the heat transfer performance of each evaporator.

[0075] Taking the density of the outlet feed liquid of the 5th evaporator as an example, the problems of the related multi-effect evaporation model are explained. In the actual multi-effect evaporation process, there is a step-by-step cascade relationship between each effect: the new steam first enters the 1st evaporator, the secondary steam of the 1st evaporator heats the 2nd evaporator, the secondary steam of the 2nd evaporator heats the 3rd evaporator, and so on, until the secondary steam of the 4th evaporator heats the 5th evaporator. However, the related model usually directly uses the new steam as the heat source of the 5th effect, ignoring the cascade transfer process of the intermediate effects. Therefore, the related multi-effect evaporation model cannot accurately describe the heat and mass transfer behavior of the feed liquid in each counter-flow evaporator, and cannot accurately reflect the dynamic characteristics of the process, leading to the problem of inaccurate model.

[0076] The use scenarios of the multi-effect evaporation model construction method based on the counter-flow heat exchange mechanism, and the defects and problems of the related model in the scenarios have been described and deduced above. The multi-effect evaporation model construction method based on the counter-flow heat exchange mechanism in the present embodiment is described as follows:

[0077] As shown in Figure 1 , a flowchart of the multi-effect evaporation model construction method based on the counter-flow heat exchange mechanism provided in the present application is shown in Figure 1 .

[0078] S101, a consistent evaporation model of the evaporator is established based on the material balance principle, and a multi-effect consistent evaporation model is obtained by cascading the consistent evaporation model based on a preset number of evaporation effect levels.

[0079] It is worth noting that the preset number of evaporation effect levels refers to the number of evaporators in the multi-effect evaporation system, i.e. the commonly used "number of effects".

[0080] In the multi-effect evaporation process, each effect evaporator follows the principle of material balance, that is, the total amount of material entering the evaporator is equal to the total amount of material leaving the evaporator. Based on this principle, a mathematical model of a single-effect evaporator can be established to describe the internal material flow and phase change process.

[0081] In a simple embodiment, for a single-effect evaporator, a consistent evaporation model can be established based on the principle of material balance as follows:

[0082] F i = V i + L i

[0083] In the formula, F i is the feed flow rate of the i-th effect evaporator, V i is the evaporation amount of the i-th effect evaporator, and L i is the discharge flow rate of the i-th effect evaporator.

[0084] It should be noted that the above embodiment is only to simply illustrate the general process of establishing a consistent evaporation model of an evaporator based on the principle of material balance, and a conventional implementation is provided, which is not limited herein.

[0085] Taking a 3-effect evaporation model as an example, according to the actual number of effects (i.e., the number of evaporators) of a multi-effect evaporation system, multiple single-effect models are connected in the order of material flow to form a whole mathematical model of the multi-effect evaporation system.

[0086] F3 = V3 + L3

[0087] L3 = F2

[0088] F2 = V2 + L2

[0089] L2 = F1

[0090] F1 = V1 + L1

[0091] In the formula, F3 is the feed flow rate of the 3rd effect evaporator, V3 is the evaporation amount of the 3rd evaporator, L3 is the discharge flow rate of the 3rd effect evaporator, F2 is the feed flow rate of the 2nd effect evaporator, V2 is the evaporation amount of the 2nd evaporator, L2 is the discharge flow rate of the 2nd effect evaporator, F1 is the feed flow rate of the 1st effect evaporator, V1 is the evaporation amount of the 1st evaporator, and L1 is the discharge flow rate of the 1st effect evaporator.

[0092] In a preferred embodiment, a balance equation is constructed according to the amount of liquid, the inlet liquid mass flow rate, the outlet liquid mass flow rate, and the steam water amount, and the balance equation is:

[0093]

[0094] M i is the liquid amount in the i-th evaporator, G in,i is the inlet liquid mass flow rate of the i-th evaporator, G out,i is the outlet liquid mass flow rate of the i-th evaporator, V i is the steam water amount of the i-th evaporator;

[0095] It can be seen that, according to the material balance principle, the balance equation including the liquid amount, the inlet liquid mass flow rate, the outlet liquid mass flow rate and the steam water amount is constructed. The equation accurately describes the dynamic balance relationship of the material in the multi-effect evaporator based on the law of conservation of mass. By introducing the liquid amount, the real-time inventory change of the material in the evaporator can be reflected; the inlet and outlet liquid mass flow rates reflect the input and output processes of the material; the introduction of the steam water amount considers the influence of the evaporation process on the material balance.

[0096] The analytical equation of the liquid amount, the inlet liquid mass flow rate and the outlet liquid mass flow rate is constructed, and the analytical equation is:

[0097] M i = ρ i A i h i

[0098] G in,i = ρ in,i F in,i

[0099] G out,i = ρ i F out,i

[0100] M i is the liquid amount in the i-th evaporator, ρ i is the liquid density of the i-th evaporator, A i is the effective cross-sectional area of the i-th evaporator, h i is the liquid level of the i-th evaporator, G in,i is the inlet liquid mass flow rate of the i-th evaporator, ρ in,i is the inlet liquid density of the i-th evaporator, F in,i is the inlet liquid volume flow rate of the i-th evaporator, G out,i is the outlet liquid mass flow rate of the i-th evaporator, F out,i is the outlet liquid volume flow rate of the i-th evaporator;

[0101] As can be seen, analytical equations were constructed for the feed volume, inlet feed mass flow rate, and outlet feed mass flow rate. These equations incorporate key parameters such as feed density, effective cross-sectional area of ​​the evaporator, liquid level, and feed volumetric flow rate to describe the material characteristics of the multi-effect evaporation process. Specifically, the introduction of feed density and liquid level reflects the influence of feed properties and evaporator geometry on the material inventory; inlet feed density and volumetric flow rate determine the material input rate; and outlet feed volumetric flow rate reflects the material output process.

[0102] Combining the analytical equations and the equilibrium equations, we obtain the uniform evaporation model, which is as follows:

[0103]

[0104] In the formula, ρ i Let t be the feed liquid density of the i-th effect evaporator, and t be the time, h. i Let A be the liquid level of the i-th effect evaporator. i ρ is the effective cross-sectional area of ​​the i-th effect evaporator. in,i F is the inlet feed density of the i-th effect evaporator. in,i F is the inlet feed volume flow rate of the i-th effect evaporator. out,i V is the outlet liquid volume flow rate of the i-th effect evaporator. i The amount of water evaporated by the i-th effect evaporator.

[0105] Continuing with the previous example, taking the 5-effect evaporation model as an example, a multi-effect consistent evaporation model is obtained based on the cascaded consistent evaporation model with a preset number of evaporation effect levels (effects). The multi-effect consistent evaporation model is as follows:

[0106]

[0107] In the formula, ρ1 is the feed liquid density of the first-effect evaporator, t is time, h1 is the liquid level of the first-effect evaporator, A1 is the effective cross-sectional area of ​​the first-effect evaporator, and ρ in,1 F is the inlet liquid density of the first-effect evaporator. in,1 F is the inlet feed volume flow rate of the first-effect evaporator. out,1 V1 is the outlet liquid volumetric flow rate of the first-effect evaporator, V2 is the water distillation rate of the first-effect evaporator, h2 is the liquid level of the second-effect evaporator, and A2 is the effective cross-sectional area of ​​the second-effect evaporator. in,2 F is the inlet liquid density of the second-effect evaporator. in,2 F is the inlet liquid volumetric flow rate of the second-effect evaporator. out,2V2 is the volume flow rate of the outlet liquid of the 2nd evaporator, V2 is the steam water amount of the 2nd evaporator; ρ3 is the density of the inlet liquid of the 3rd evaporator, h3 is the liquid level of the 3rd evaporator, A3 is the effective cross-sectional area of the 3rd evaporator, ρ in,3 V2 is the volume flow rate of the outlet liquid of the 2nd evaporator, V2 is the steam water amount of the 2nd evaporator; ρ3 is the density of the inlet liquid of the 3rd evaporator, h3 is the liquid level of the 3rd evaporator, A3 is the effective cross-sectional area of the 3rd evaporator, ρ in,3 V2 is the volume flow rate of the outlet liquid of the 2nd evaporator, V2 is the steam water amount of the 2nd evaporator; ρ3 is the density of the inlet liquid of the 3rd evaporator, h3 is the liquid level of the 3rd evaporator, A3 is the effective cross-sectional area of the 3rd evaporator, ρ out,3 V2 is the volume flow rate of the outlet liquid of the 2nd evaporator, V2 is the steam water amount of the 2nd evaporator; ρ3 is the density of the inlet liquid of the 3rd evaporator, h3 is the liquid level of the 3rd evaporator, A3 is the effective cross-sectional area of the 3rd evaporator, ρ in,4 V2 is the volume flow rate of the outlet liquid of the 2nd evaporator, V2 is the steam water amount of the 2nd evaporator; ρ3 is the density of the inlet liquid of the 3rd evaporator, h3 is the liquid level of the 3rd evaporator, A3 is the effective cross-sectional area of the 3rd evaporator, ρ in,4 V2 is the volume flow rate of the outlet liquid of the 2nd evaporator, V2 is the steam water amount of the 2nd evaporator; ρ3 is the density of the inlet liquid of the 3rd evaporator, h3 is the liquid level of the 3rd evaporator, A3 is the effective cross-sectional area of the 3rd evaporator, ρ out,4 V2 is the volume flow rate of the outlet liquid of the 2nd evaporator, V2 is the steam water amount of the 2nd evaporator; ρ3 is the density of the inlet liquid of the 3rd evaporator, h3 is the liquid level of the 3rd evaporator, A3 is the effective cross-sectional area of the 3rd evaporator, ρ in,5 V2 is the volume flow rate of the outlet liquid of the 2nd evaporator, V2 is the steam water amount of the 2nd evaporator; ρ3 is the density of the inlet liquid of the 3rd evaporator, h3 is the liquid level of the 3rd evaporator, A3 is the effective cross-sectional area of the 3rd evaporator, ρ in,5 V2 is the volume flow rate of the outlet liquid of the 2nd evaporator, V2 is the steam water amount of the 2nd evaporator; ρ3 is the density of the inlet liquid of the 3rd evaporator, h3 is the liquid level of the 3rd evaporator, A3 is the effective cross-sectional area of the 3rd evaporator, ρ out,5 V2 is the volume flow rate of the outlet liquid of the 2nd evaporator, V2 is the steam water amount of the 2nd evaporator; ρ3 is the density of the inlet liquid of the 3rd evaporator, h3 is the liquid level of the 3rd evaporator, A3 is the effective cross-sectional area of the 3rd evaporator, ρ

[0108] In actual use, there is a problem that the densities of the liquids in different effects may be different. When these liquids of different densities are mixed, the volume changes, thereby affecting the material balance. In order to simplify the complexity of the model and improve the calculation efficiency, the influence of the volume change can be appropriately ignored when modeling.

[0109] S102, construct a simplified function ignoring the volume change caused by mixing of solutions of different densities.

[0110] It should be noted that the volumes before and after mixing are considered equal, so that the influence of the volume change is removed from the model.

[0111] In some preferred embodiments, the simplified function is:

[0112]

[0113] In the formula, h i is the liquid level of the i th evaporator, t is time, A i is the effective cross-sectional area of the i th evaporator, F in,i is the volume flow rate of the inlet liquid of the i th evaporator, F out,i is the volume flow rate of the outlet liquid of the i th evaporator, V i is the steam water amount of the i th evaporator, ρw Density of water.

[0114] It should be noted that the above simplified function is only a preferred embodiment, and in other embodiments, other ways can be taken, which are not limited here.

[0115] It can be seen that on the basis of the consistency evaporation model, a simplified treatment of ignoring the density difference of the feed liquid is further introduced. Considering that there may be a difference in the density of the feed liquid between different efficient evaporators, directly using these feed liquid volume flow rates for material balance calculation may introduce errors. In order to simplify the complexity of the model and improve the calculation efficiency, the volume change caused by the density difference is appropriately ignored in the modeling process. Although this simplification sacrifices some accuracy, it highlights the main research problem of the model, making the material balance relationship more clear and easy to solve. Through reasonable simplifying assumptions, the calculation amount and time cost can be greatly reduced while ensuring the practicability of the model.

[0116] S103, a relationship function is constructed, in which the steam generation amount is positively correlated with the heat transfer amount and negatively correlated with the density of the feed liquid.

[0117] Reference Figure 3 , Figure 3 The working principle diagram of the tubular falling film evaporator provided in the present application, in order to accurately represent the individualized heat transfer and mass transfer behavior of the feed liquid in each efficient evaporator, the working principle of the evaporator is explained as follows.

[0118] The evaporation process often uses a tubular falling film evaporator as shown in Figure 3 First, the feed liquid is sent to the top of the evaporator by the circulating pump, uniformly distributed by the film distributor, and flows downward along the inner wall of the heating pipe in the form of a film; then, the hot steam distributed outside the heating pipe transfers heat through the pipe wall, causing the liquid film to vaporize while flowing; then, the high-temperature feed liquid after evaporation in the heating chamber and the generated secondary steam are subjected to gas-liquid separation in the separation chamber, the separated secondary steam is sent to the next efficient evaporator as a heat source, and the feed liquid is discharged from the bottom of the separation chamber and sent to the previous efficient evaporator for further concentration by the discharge pump.

[0119] The working principle of the evaporator is analyzed, and it is found that the power for realizing the concentration of the feed liquid in the evaporator mainly comes from the heat transfer amount of the evaporator. The greater the heat transfer amount of the evaporator, the more energy is supplied to the feed liquid per unit time. This part of energy will be used to increase the temperature and internal energy of the feed liquid, so that more water molecules reach the energy state required for evaporation. Therefore, the increase of the heat transfer amount will inevitably lead to the increase of the evaporation amount, and the two are positively correlated. The density of the feed liquid reflects the relative content of solutes and water molecules per unit volume. The higher the density, the greater the solute concentration, and the lower the free water content. Under the condition of the same heat transfer amount, the number of water molecules available for evaporation in the high-density feed liquid is less, so the evaporation amount will decrease with the increase of the density of the feed liquid. Therefore, the evaporation amount of the evaporator is positively correlated with the heat transfer amount and negatively correlated with the density of the feed liquid.

[0120] In some embodiments, the relationship function is:

[0121]

[0122] In the formula, V i is the evaporation amount of the i-th evaporator, Q i is the heat transfer amount of the i-th evaporator, p i is the outlet feed liquid density of the i-th evaporator, a ′ i , c i are coefficients.

[0123] In other preferred embodiments, the relationship function is:

[0124]

[0125] In the formula, V i is the evaporation amount of the i-th evaporator, Q i is the heat transfer amount of the i-th evaporator, p i is the outlet feed liquid density of the i-th evaporator, a i , c i are coefficients, b i , d i are constants.

[0126] It should be noted that the above relationship functions only provide several embodiments, and in other embodiments, other ways can be adopted, which are not limited herein.

[0127] S104, the multi-effect evaporation model is obtained by combining the multi-effect consistency evaporation model, the simplified function and the relationship function.

[0128] Combination refers to combining multiple equations or inequalities together to form an equation.

[0129] It should be noted that steps S101 to S103 provide multiple implementation manners, and this step only exemplarily selects one preferred combination of steps S101 to S103, but is not limited to the only implementation path.

[0130] The preferred consistency evaporation model is:

[0131]

[0132] The preferred simplified function is:

[0133]

[0134] The preferred relationship function is:

[0135]

[0136] The multi-effect evaporation model is:

[0137]

[0138] In the formula, ρ i is the feed liquid density of the i-th effect evaporator, t is time, A i is the effective cross-sectional area of the i-th effect evaporator, h i is the liquid level of the i-th effect evaporator, F in,i is the inlet feed liquid volume flow of the i-th effect evaporator, ρ in,i is the inlet feed liquid density of the i-th effect evaporator, Q i is the heat transfer amount of the i-th effect evaporator, a i is the heat transfer coefficient of the i-th effect evaporator, b i is the heat transfer constant of the i-th effect evaporator, c i is the feed liquid density coefficient of the i-th effect evaporator, d i is the feed liquid density constant of the i-th effect evaporator, ρ w is the density of water.

[0139] Referring to Figure 2 , it should be noted that the above model is only a general writing, and in actual use, it is still determined according to the number of effects of the evaporator. Taking a 5-effect evaporation model as an example:

[0140] Because for the feed liquid, the original liquid enters the 5-effect evaporator, passes through the 4-effect, 3-effect, 2-effect in turn, and is discharged at the 1-effect, and for the steam, the new steam is introduced into the 1-effect evaporator, the secondary steam of the 1-effect heats the 2-effect, the secondary steam of the 2-effect heats the 3-effect, the secondary steam of the 3-effect heats the 4-effect, the secondary steam of the 4-effect heats the 5-effect, and the secondary steam of the 5-effect is introduced into the condenser.

[0141] Therefore, the 5-effect evaporation model is:

[0142]

[0143] In the formula, F0 is the inlet feed liquid volume flow rate of the 5th evaporator, F5 is the inlet feed liquid volume flow rate of the 4th evaporator, F4 is the inlet feed liquid volume flow rate of the 3rd evaporator, F3 is the inlet feed liquid volume flow rate of the 2nd evaporator, and F2 is the inlet feed liquid volume flow rate of the 1st evaporator.

[0144] S105, outputting the multi-effect evaporation model, so that the industrial site can refer to the multi-effect evaporation model to regulate the evaporation process.

[0145] Reference Figure 4 , Figure 4 A comparison diagram of the related multi-effect evaporation model and the multi-effect evaporation model provided by the application based on the counterflow heat exchange mechanism.

[0146] Figure 4 The "wavy line" section with relatively large fluctuations is the actual acquired outlet feed liquid density of the 5th evaporator, the "wavy line" section with relatively small fluctuations is the outlet feed liquid density of the 5th evaporator predicted by the multi-effect evaporation model provided by the application, and the "wavy line" section with a downward trend is the outlet feed liquid density of the 5th evaporator predicted by the multi-effect evaporation model provided by the related art. It can be seen that the data predicted by the multi-effect evaporation model provided by the application is more accurate than the data predicted by the multi-effect evaporation model provided by the related art.

[0147] It can be seen that by constructing the relationship function, the quantitative relationship that the steam production is positively correlated with the heat transfer and negatively correlated with the feed liquid density is determined. The relationship function fully considers the key role of energy flow in the change of the state of the feed liquid in the evaporation process, can accurately describe the heat and mass transfer behavior of the feed liquid in the evaporator, and accurately reflect the dynamic characteristics of the multi-effect evaporation process. The multi-effect evaporation model established based on the relationship function has high accuracy and can provide strong support for the accurate control of the industrial site. Meanwhile, the simplified function that ignores the volume change caused by the mixing of solutions with different densities is constructed, which can reduce the calculation complexity and improve the practicability of the model while ensuring the accuracy of the model.

[0148] A specific embodiment is provided below:

[0149] Reference Figure 5 , Figure 5 A lower process diagram of the multi-effect evaporation model construction method provided by the application based on the counterflow heat exchange mechanism.

[0150] S501, establishing a consistent evaporation model of the evaporator based on the material balance principle, and obtaining a multi-effect consistent evaporation model based on a preset evaporation effect level number cascading the consistent evaporation model.

[0151] The uniform evaporation model is as follows:

[0152]

[0153] It should be noted that the principle and process of this step have been specifically disclosed in step S101. The relevant principle and process can be referred to in step S101, and will not be repeated here.

[0154] S502. Construct a simplified function that ignores the volume change caused by mixing solutions of different densities.

[0155] The simplified function is:

[0156]

[0157] It should be noted that the principle and process of this step have been specifically disclosed in step S102. The relevant principle and process can be referred to in step S102, and will not be repeated here.

[0158] S503. Construct a relational function, in which the amount of water evaporated is the ratio of the product of heat transfer and heat transfer factor to the product of the density of the liquid and the density factor of the liquid.

[0159] The relational function is:

[0160]

[0161] It should be noted that the principle and process of this step have been specifically disclosed in step S103. The relevant principle and process can be referred to in step S103, and will not be repeated here.

[0162] As can be seen, when constructing the relationship function, the steaming rate is expressed as the ratio of the product of heat transfer and heat transfer factor to the product of liquid density and liquid density factor. This quantitatively describes the influence of heat transfer and liquid density on the steaming rate, reflecting their correlation. Furthermore, by appropriately setting the values ​​of these two factors, the weights of heat transfer and liquid density in the relationship function can be adjusted, allowing the model to more accurately reflect the actual multi-effect evaporation process.

[0163] S504. By combining the multi-effect consistent evaporation model, simplifying the function, and the relational function, the multi-effect evaporation model is obtained.

[0164] The multi-effect evaporation model is as follows:

[0165]

[0166] S505. Within the preset number of iterations, adjust the values ​​of all heat transfer factors and liquid density factors, and obtain the difference between the simulated data calculated by the multi-effect evaporation model and the actual data.

[0167] It should be noted that the principle and process of this step have been specifically disclosed in step S605, and the relevant principles and processes can be referred to step S605, which will not be repeated here.

[0168] S506, when the difference is smallest, determine the values of all heat transfer factors and feed liquid density factors.

[0169] It can be seen that by adjusting the values of the heat transfer factors and the feed liquid density factors within the preset number of iterations, and comparing the differences between the model calculation results and the actual data, the dynamic optimization of the model parameters is realized. When the difference is smallest, the values of the heat transfer factors and the feed liquid density factors determined can make the simulation results of the model closest to the actual situation to achieve the global optimal solution. This iterative optimization process can significantly improve the accuracy of the multi-effect evaporation model, so that it can better describe the behavior of the feed liquid in the evaporation process.

[0170] S507, output the multi-effect evaporation model, so that the industrial field can refer to the multi-effect evaporation model to regulate and control the evaporation process.

[0171] A preferred embodiment is provided below:

[0172] Reference Figure 6 , Figure 6 Another sub-process schematic diagram of the multi-effect evaporation model construction method based on the counterflow heat exchange mechanism provided in the present application.

[0173] S601, establish a consistent evaporation model of the evaporator based on the material balance principle, and cascade the consistent evaporation model based on a preset number of evaporation effect levels to obtain a multi-effect consistent evaporation model.

[0174] The consistent evaporation model is:

[0175]

[0176] It should be noted that the principle and process of this step have been specifically disclosed in step S101, and the relevant principles and processes can be referred to step S101, which will not be repeated here.

[0177] S602, construct a simplified function that ignores the volume change caused by the mixing of solutions with different densities.

[0178] The simplified function is:

[0179]

[0180] It should be noted that the principle and process of this step have been specifically disclosed in step S102, and the relevant principles and processes can be referred to step S102, which will not be repeated here.

[0181] S603, a relationship function is constructed, the steam amount is the ratio of a heat transfer function and a density function of the material liquid, the heat transfer function is determined by the product of the heat transfer and a heat transfer coefficient, and a heat transfer constant is added to the product, and the density function of the material liquid is determined by the product of the density of the material liquid and a material liquid density coefficient, and a material liquid density constant is added to the product.

[0182] The relationship function is:

[0183]

[0184] It should be noted that the principle and process of this step have been specifically disclosed in step S103, and the related principles and processes can be referred to step S103, which will not be repeated here.

[0185] It can be seen that when the relationship function is constructed, the expression forms of the heat transfer function and the material liquid density function are further refined. In addition to introducing the heat transfer coefficient and the material liquid density coefficient to describe the influence degree of the heat transfer and the material liquid density, the heat transfer constant term and the material liquid density constant term are also added to the function. By adjusting the value of the constant term, the output result of the heat transfer function and the material liquid density function can be fine-tuned while keeping the heat transfer coefficient and the material liquid density coefficient unchanged, and then the model can be locally optimized without changing the overall form of the function, which is helpful to further improve the model precision.

[0186] S604, the multi-effect evaporation model is obtained by simultaneously solving the multi-effect consistency evaporation model, the simplified function and the relationship function.

[0187] The multi-effect evaporation model is:

[0188]

[0189] S605, the values of all heat transfer coefficients, heat transfer constants, material liquid density coefficients and material liquid density constants are adjusted within a preset number of iterations, and the difference between the simulation data obtained by the multi-effect evaporation model and the actual data is obtained.

[0190] Taking a 5-effect evaporation model as an example, the step is specifically described.

[0191] The 5-effect evaporation model is:

[0192]

[0193]

[0194] The parameter identification problem of the evaporation process can be converted into an optimization problem for solution, and the target is to minimize the difference between the simulation data obtained by the estimated parameters and the actual data;

[0195] The parameter identification and optimization problem of the multi-effect evaporation process is:

[0196]

[0197] wherein the error function of each pair of simulation data and actual data is defined by the following formula:

[0198]

[0199] In the formula, F obj (x) is the root mean square error of the simulated discharge density of the first effect and the actual discharge density identified by the N sample data, that is, the objective function of the parameter identification and optimization problem, x is the heat transfer parameter to be identified in the multi-effect evaporation process, that is, the decision variable of the parameter identification and optimization problem, N is the number of data pairs used for identifying the parameters, F i (p 5,i ,ρ 1,i ,x) is the error value of the simulation data and the actual data obtained by the i-th data pair, is the kinetic model of the above-mentioned 5-effect evaporation process, ρ 5,i represents the feed liquid density of the i-th data pair, ρ 1,i represents the discharge liquid density of the i-th data pair; is the integral operation of the above-mentioned 5-effect evaporation model in the period T1, and the obtained simulation value of the discharge liquid density ρ 1,i of the 5-effect evaporation process corresponding to the i-th data pair according to the identified parameters x is obtained; is the difference between the simulation value and the actual value of the discharge liquid density ρ 1,i of the 5-effect evaporation process corresponding to the i-th data pair according to the identified parameters x.

[0200] It should be noted that the above embodiment only exemplarily gives a specific implementation mode, and in other embodiments, other modes can also be adopted, which are not limited here.

[0201] In some specific embodiments, further technical solutions are provided to solve the parameter identification problem of the above-mentioned evaporation process;

[0202] The specific steps are as follows:

[0203] S1, randomly generate an initial population in the decision space, and each individual represents a solution (decision variable);

[0204] The decision space refers to the set of all feasible solutions in the optimization problem, and each solution is composed of a set of values of decision variables.

[0205] The initial population refers to the set of feasible solutions in the optimization problem, and each solution is composed of a set of values of decision variables.

[0206] This step is the starting point of the CJAYA algorithm, and the purpose is to provide an initial search point for the subsequent optimization process. In the parameter identification problem, the decision variables usually correspond to the model parameters to be identified. Randomly generating an initial population means randomly selecting a certain number of points in the decision space as the starting search location. The advantage of this is that it can increase the diversity of the population and avoid the algorithm falling into local optima too early.

[0207] S2, for each solution in the population, calculate the fitness value according to its corresponding decision variable, the fitness value is calculated by the objective function of the defined optimization problem, and the optimization goal of parameter identification is:

[0208]

[0209] The fitness value refers to the objective function value corresponding to each candidate solution.

[0210] For the parameter identification problem, it is hoped to find a set of parameters that make the output of the model as close as possible to the actual measured data, so the fitness function is designed to measure the error between the simulation value and the measured value.

[0211] S3, set the number of iterations or other termination conditions so that the algorithm stops when certain conditions are met;

[0212] S4, for each individual in the population, generate a new individual and calculate the fitness value (objective function) of the new individual.

[0213] However, in the decision space of the parameter identification problem, different dimensions have different search ranges, resulting in a complex and variable entire decision space. When solving such problems with optimization algorithms, it may occur that some decision dimensions are over-searched while other dimensions are under-searched. This imbalance in search will affect the convergence speed of the algorithm and the quality of the solution, making it difficult for the algorithm to find a global optimal solution.

[0214] Therefore, step S4 can be: S41, for each individual in the population, generate a new individual according to the "dynamic clustering weight strategy" and calculate the fitness value (objective function) of the new individual.

[0215] In some specific embodiments, the CJAYA algorithm generates new individuals using a dynamic clustering weight strategy. Specifically, CJAYA divides the population into several subgroups by clustering learning mode, and determines the intra-class optimal value and intra-class worst value of each class. Other individuals in the class learn from the intra-class optimal, intra-class worst, global optimal, and global worst individuals with a certain probability to determine the evolution direction. At the same time, the algorithm introduces dynamic weights to adaptively adjust the learning intensity of intra-class individuals, so that individuals of different classes have different learning strategies and learning steps. In this way, the algorithm can effectively search in each dimension of the decision variable and find high-quality solutions that meet the optimization objective by exploring different parameter combinations. The dynamic clustering weight strategy can balance the global exploration and local development capabilities of the algorithm, improving the search efficiency and solution quality of the algorithm in complex decision spaces.

[0216] However, taking the multi-effect evaporation model as an example, the multi-effect evaporation model is composed of five cascaded differential equation groups. For a sample data pair, the simulation value of the discharge density needs to be calculated by continuously solving five differential equation groups according to the feed density and the parameters to be identified. This process not only has a high degree of nonlinearity, but also involves a large number of parameters, and any change in any parameter can have a significant impact on the result, so it is very difficult to solve such a highly nonlinear optimization problem. When dealing with such problems, traditional optimization algorithms often have difficulty escaping local optima or have slow convergence speed, resulting in poor optimization performance.

[0217] Therefore, step S4 can be: S42, for each individual in the population, generate a new individual according to the "multi-experience learning strategy", and calculate the fitness value (objective function) of the new individual;

[0218] Therefore, in some specific embodiments, the CJAYA algorithm generates new individuals using a multi-experience learning strategy. To solve this problem, the algorithm clusters the entire population into several subspaces. Within each clustering subspace, the current individual learns to different degrees from other individuals in the class, including learning from the intra-class optimal individual, learning from a randomly selected high-quality individual, and learning from the global optimal individual. By comprehensively utilizing multiple learning experiences, individuals can escape local optima and accelerate convergence to the global optimal solution. This not only promotes information exchange between individuals in the population, but also draws on the evolutionary experience of other individuals, fully utilizing the advantages of other individuals and avoiding their disadvantages. The multi-experience learning strategy enhances the algorithm's ability to handle highly nonlinear problems by reasonably scheduling different learning modes, which helps the algorithm converge more accurately to the global optimal solution, thereby achieving good solving performance.

[0219] In some embodiments, step S4 can be: S43, for each individual in the population, generate a new individual according to the "dynamic clustering weight strategy" and the "multi-experience learning strategy", and calculate the fitness value (objective function) of the new individual. Thus, the above problems can be solved simultaneously.

[0220] S5, update the corresponding individual in the current population according to the fitness value of the new individual produced;

[0221] In the search process of parameter identification, the optimal solution plays a crucial role, as it can guide and attract other individuals to gather around it. However, for the parameter identification problem of the evaporation process with multi-peak characteristics, the optimal solution is likely to be located near a local optimal region. In this case, other individuals are easily attracted to this local optimal region, leading to premature convergence of the algorithm and failure to find the global optimal solution of the problem. This phenomenon seriously affects the optimization performance and solution quality of the algorithm.

[0222] Therefore, in some embodiments, it further includes: S6, updating the optimal solution of the population according to the designed "chaotic elite strategy";

[0223] The chaotic elite learning strategy is introduced to adjust the quality of the optimal solution. The chaotic sequence has randomness and ergodicity, which is beneficial to generate new elite individuals to improve the quality of the solution.

[0224] The implementation process of the chaotic elite learning strategy is as follows: first, generate a chaotic sequence according to the optimal individual of the current population. Then, use the chaotic sequence to perturb the decision variables of the optimal individual to generate several new elite individuals. Next, compare these new elite individuals with the original optimal individual, and select the individual with the optimal fitness value as the new optimal solution. In this way, the algorithm can continuously generate new solutions with higher quality on the basis of preserving the original optimal solution, effectively escaping from the local optimal region.

[0225] S7, determine whether to terminate the algorithm according to the predefined stopping condition (maximum number of iterations). If the stopping condition is met, the algorithm ends and the parameters to be identified are obtained. Otherwise, return to steps S4, S5, and S6.

[0226] S606, when the difference is the smallest, determine the values of the heat transfer coefficient, the heat transfer constant, the liquid density coefficient, and the liquid density constant.

[0227] It can be seen that by adjusting the values of these parameters within a preset number of iterations and comparing the differences between the model calculation results and the actual data, the dynamic optimization of each parameter in the relationship function can be achieved. Through iterative optimization, the best parameter combination can be selected in the partial selection, and the values of each parameter at the time of the smallest difference are obtained. Compared with optimizing a certain type of parameter alone, this comprehensive optimization method can more comprehensively consider the relationship between each parameter, so that the multi-effect evaporation model achieves the optimal solution as a whole, improves the accuracy of the multi-effect evaporation model, and makes it more accurately reflect / describe the behavior of the feed liquid in the evaporation process.

[0228] S607, outputting the multi-effect evaporation model, so that the industrial field can refer to the multi-effect evaporation model to regulate and control the evaporation process.

[0229] The application also discloses a multi-effect evaporation model construction system based on the countercurrent heat exchange mechanism. Figure 7 , the schematic diagram of the entity device of the multi-effect evaporation model construction system based on the countercurrent heat exchange mechanism provided by the application. The computer 700 can include at least one processor 701, at least one network interface 704, a user interface 703, a memory 705, and at least one communication bus 702.

[0230] The communication bus 702 is used to realize the connection and communication between the components.

[0231] The user interface 703 can include a display screen (Display) and a camera (Camera), and the optional user interface 703 can further include a standard wired interface and a wireless interface.

[0232] The network interface 704 can optionally include a standard wired interface and a wireless interface (such as a WI-FI interface).

[0233] The processor 701 can include one or more processing cores. The processor 701 connects various parts within the server through various interfaces and lines, performs various functions of the server and processes data by running or executing instructions, programs, code sets or instruction sets stored in the memory 705, and calling data stored in the memory 705. Alternatively, the processor 701 can be implemented in at least one of a hardware form of a digital signal processing (DSP), a field-programmable gate array (FPGA), and a programmable logic array (PLA). The processor 701 can integrate a combination of one or more of a central processing unit (CPU), a graphics processing unit (GPU), and a modem. Among them, the CPU mainly processes operating systems, user interfaces, and application programs; the GPU is responsible for rendering and drawing the content to be displayed on the display screen; and the modem is used for processing wireless communication. It can be understood that the above-mentioned modem can also not be integrated into the processor 701, but can be realized by a separate chip.

[0234] The memory 705 can include a random access memory (RAM) and a read-only memory (ROM). Optionally, the memory 705 includes a non-transitory computer-readable storage medium. The memory 705 can be used to store instructions, programs, codes, code sets or instruction sets. The memory 705 can include a program storage area and a data storage area, wherein the program storage area can store instructions for implementing an operating system, instructions for at least one function (such as a touch function, a sound playing function, an image playing function, etc.), instructions for implementing the above-mentioned various method embodiments, etc.; the data storage area can store data involved in the above-mentioned various method embodiments, etc. The memory 705 can also be at least one storage device located away from the aforementioned processor 701. Referring to Figure 7 The memory 705 as a computer storage medium can include an operating system, a network communication module, a user interface module, and an application program based on the multi-effect evaporation model constructed based on the counterflow heat exchange mechanism.

[0235] In Figure 7In the computer 700 shown, the user interface 703 is mainly used to provide an interface for the user to input, and obtain the data input by the user; and the processor 701 can be used to invoke the application program stored in the memory 705 based on the multi-effect evaporation model constructed based on the counterflow heat exchange mechanism, and when executed by one or more processors 701, the computer 700 is caused to perform the method described in one or more of the above embodiments. It should be noted that, for the foregoing method embodiments, in order to simply describe, they are all expressed as a combination of a series of actions, but those skilled in the art should know that the present application is not limited to the order of the actions described, because according to the present application, certain steps can be performed in other order or simultaneously. Secondly, those skilled in the art should know that the embodiments described in the specification all belong to preferred embodiments, and the actions and modules involved are not necessarily required by the present application.

[0236] In the above embodiments, the description of each embodiment has its own focus, and the parts not described in detail in a certain embodiment can be referred to the related description of other embodiments.

[0237] In several embodiments provided by the present application, it should be understood that the disclosed device can be implemented in other ways. For example, the device embodiments described above are only schematic. The division of the units is only a logical function division. There can be another division manner for actual implementation, for example, a plurality of units or components can be combined or integrated into another system, or some features can be ignored or not executed. In addition, the coupling or direct coupling or communication connection between the units shown or discussed can be indirect coupling or communication connection through some other services interface, device or unit, and can be electrical or other forms.

[0238] The units described as separate components can or can not be physically separate, and the components shown as units can or can not be physical units, that is, they can be located in one place, or can be distributed on a plurality of network units. Some or all of the units can be selected according to actual needs to achieve the purpose of the embodiment.

[0239] In addition, each functional unit in each embodiment of the present application can be integrated into a processing unit, or each unit can exist physically, or two or more units can be integrated into one unit. The integrated unit can be realized in the form of hardware, or in the form of a software functional unit.

[0240] The integrated unit, if implemented in the form of a software function unit and sold or used as an independent product, can be stored in a computer readable memory. Based on such understanding, the technical solutions of the present application essentially or the part that contributes to the prior art or the whole or part of the technical solutions can be embodied in the form of a software product. The computer software product is stored in a memory and includes a plurality of instructions for causing a computer device (which can be a personal computer, a server or a network device, etc.) to execute all or part of the steps of the embodiments of the present application. The aforementioned memory includes: a U disk, a mobile hard disk, a magnetic or optical disk, and various media that can store program codes.

[0241] In the above embodiments, all or part can be implemented by software, hardware, firmware or any combination thereof. When implemented by software, all or part can be implemented in the form of a computer program product. The computer program product includes one or more computer instructions. When the computer program instructions are loaded and executed on a computer, all or part of the processes or functions described in the embodiments of the present application are generated. The computer can be a general-purpose computer, a special-purpose computer, a computer network, or other programmable devices. The computer instructions can be stored in a computer readable storage medium or transferred from one computer readable storage medium to another, for example, the computer instructions can be transferred from one website, computer, server or data center to another website, computer, server or data center through wired (such as coaxial cable, optical fiber, digital subscriber line) or wireless (such as infrared, wireless, microwave, etc.) mode. The computer readable storage medium can be any available medium that can be accessed by a computer or a data storage device such as a server, data center, etc. integrated with one or more available media. The available media can be magnetic media (such as floppy disk, hard disk, magnetic tape), optical media (such as DVD), or semiconductor media (such as solid state disk), etc.

[0242] The above is only an exemplary embodiment of the present disclosure, and cannot limit the scope of the present disclosure. That is, any equivalent changes and modifications made in accordance with the teachings of the present disclosure are still within the scope of the present disclosure. Other embodiments of the present disclosure will be readily apparent to those skilled in the art upon considering the specification and practicing the true disclosure.

[0243] The present application is intended to cover any variations, uses or adaptive changes of the present disclosure, which follow the general principles of the present disclosure and include common knowledge or conventional technical means in the technical field not described in the present disclosure. The specification and examples are only considered as exemplary, and the scope and spirit of the present disclosure are defined by the claims.

Claims

1. A method for constructing a multi-effect evaporation model based on counter-current heat exchange mechanism, characterized in that, The method comprises the following steps: A consistent evaporation model of an evaporator is established based on a material balance principle, and a multi-effect consistent evaporation model is obtained by cascading the consistent evaporation model based on a preset evaporation effect level; wherein: a balance equation is constructed according to a material liquid amount, an inlet material liquid mass flow, an outlet material liquid mass flow, and a steam water amount, and the balance equation is: In the formula, M i is the amount of feed liquid in the i-th evaporator, G in,i is the inlet feed liquid mass flow rate of the i-th evaporator, G out,i is the outlet feed liquid mass flow rate of the i-th evaporator, V i is the amount of steam in the i-th evaporator; An analytical equation of the material liquid amount, the inlet material liquid mass flow, and the outlet material liquid mass flow is constructed, and the analytical equation is: M i = p i A i h i G in,i = p in,i F in,i G out,i = p i F out,i where p i is the feed liquid density of the i-th evaporator, A i is the effective cross-sectional area of the i-th evaporator, h i is the liquid level of the i-th evaporator, p in,i is the inlet feed liquid density of the i-th evaporator, F in,i is the inlet feed liquid volumetric flow rate of the i-th evaporator, F out,i is the outlet feed liquid volumetric flow rate of the i-th evaporator; The analytical equation and the balance equation are combined to obtain a consistent evaporation model, and the consistent evaporation model is: In the formula, t is time; A simplified function ignoring volume changes caused by mixing of solutions with different densities is constructed; A relationship function is constructed, and in the relationship function, the steam water amount is positively correlated with the heat transfer amount and negatively correlated with the density of the material liquid; The multi-effect consistent evaporation model, the simplified function, and the relationship function are combined to obtain a multi-effect evaporation model; The multi-effect evaporation model is output, so that an industrial site can refer to the multi-effect evaporation model to control an evaporation process.

2. The method for constructing a multiple-effect evaporation model based on counter-current heat exchange mechanism according to claim 1, characterized in that, The step of constructing the relationship function, in which the steam water amount is positively correlated with the heat transfer amount and negatively correlated with the density of the material liquid, specifically comprises: A relationship function is constructed, and in the relationship function, the steam water amount is a ratio of a product of the heat transfer amount and a heat transfer amount factor to a product of the density of the material liquid and a material liquid density factor.

3. The method for constructing a multiple-effect evaporation model based on counter-current heat exchange mechanism according to claim 2, characterized in that, After the step of combining the multi-effect consistent evaporation model, the simplified function, and the relationship function to obtain a multi-effect evaporation model, the method further comprises: Within a preset number of iterations, the values of all the heat transfer amount factors and the material liquid density factors are adjusted, and a difference between simulation data calculated by the multi-effect evaporation model and actual data is obtained; When the difference is the smallest, the values of all the heat transfer amount factors and the material liquid density factors are determined.

4. The method for constructing a multiple-effect evaporation model based on counter-current heat exchange mechanism according to claim 1, characterized in that, The step of constructing the relationship function, in which the steam water amount is positively correlated with the heat transfer amount and negatively correlated with the density of the material liquid, specifically comprises: A relationship function is constructed, and in the relationship function, the steam water amount is a ratio of a heat transfer amount function to a density function of the material liquid, the heat transfer amount function is determined by a product of the heat transfer amount and a heat transfer amount coefficient, and an additional heat transfer amount constant is added to the product, and the density function of the material liquid is determined by a product of the density of the material liquid and a material liquid density coefficient, and an additional material liquid density constant is added to the product.

5. The method for constructing a multiple-effect evaporation model based on counter-current heat exchange mechanism according to claim 4, characterized in that, After the step of combining the multi-effect consistent evaporation model, the simplified function, and the relationship function to obtain a multi-effect evaporation model, the method further comprises: Within a preset number of iterations, the values of all the heat transfer amount factors, the heat transfer amount constant, the material liquid density coefficient, and the material liquid density constant are adjusted, and a difference between simulation data calculated by the multi-effect evaporation model and actual data is obtained; When the difference is the smallest, the values of all the heat transfer amount factors, the heat transfer amount constant, the material liquid density coefficient, and the material liquid density constant are determined.

6. The method for constructing a multiple-effect evaporation model based on counter-current heat exchange mechanism as claimed in claim 1, wherein, The simplified function is: In the formula, p w is the density of water; The multi-effect evaporation model is: In the formula, Q i is the heat transfer of the i-th evaporator, a i is the heat transfer coefficient of the i-th evaporator, b i is the heat transfer constant of the i-th evaporator, c i is the feed liquid density coefficient of the i-th evaporator, d i is the feed liquid density constant of the i-th evaporator.

7. A multi-effect evaporation model building system based on counter-current heat exchange mechanism, characterized in that, The method comprises the following steps: One or more processors and memories; The memory is coupled to the one or more processors, and the memory is configured to store computer program code comprising computer instructions to cause the multi-effect evaporation model construction system based on counter-current heat exchange mechanism to perform the method of any one of claims 1-6.

8. A computer-readable storage medium comprising instructions, characterized in that, The instructions, when executed on the multi-effect evaporation model construction system based on counter-current heat exchange mechanism, cause the multi-effect evaporation model construction system based on counter-current heat exchange mechanism to perform the method of any one of claims 1-6.

9. A computer program product, characterised in that, The computer program product, when executed on the multi-effect evaporation model construction system based on counter-current heat exchange mechanism, causes the multi-effect evaporation model construction system based on counter-current heat exchange mechanism to perform the method of any one of claims 1-6.

Images