Comprehensive evaporation model construction method based on personalized phase change characteristics and related equipment

Abstract

A method for constructing a comprehensive evaporation model based on personalized phase change characteristics and related equipment relate to the technical field of evaporation model construction. In this method, a multi-effect consistent evaporation model for an evaporator is established; a simplified evaporation function is constructed; an evaporation relationship function is constructed, in which the amount of evaporated water is positively correlated with the heat transfer and negatively correlated with the density of the feed liquid; a multi-effect evaporation model is obtained by combining these functions; a simplified flash evaporation function is established; a flash evaporation relationship function is constructed, in which the amount of evaporated water is positively correlated with the pressure drop and negatively correlated with the density of the feed liquid; a multi-stage flash evaporation model is obtained by combining the multi-effect evaporation model and the multi-stage flash evaporation model to obtain a multi-effect comprehensive model of the evaporation process; the method is used to capture the personalized differences in the phase change characteristics of the feed liquid during the actual evaporation process, making the model more accurate, and then accurately controlling the site based on the regulation of the model.

Description

Technical Field

[0001] The present application relates to the technical field of evaporation model construction, and in particular to a method for constructing a multi-effect comprehensive model of an evaporation process based on personalized phase change characteristics. Background Art

[0002] Evaporation is the process of partially vaporizing the volatile solvent in a dilute solution containing a nonvolatile solute under boiling conditions by heating, thereby concentrating the solution. This process is widely used in nonferrous metallurgy, food, pharmaceuticals, chemicals, and seawater desalination. Essentially, it involves a heat transfer process in which vapor condenses on the shell side and liquid boils on the tube side. The solvent vaporization rate is entirely dependent on the heat transfer. Flash evaporation is a unit operation that concentrates the solution by partially vaporizing the superheated liquid through the pressure reduction effect of a throttle valve. This process is widely used in nonferrous metallurgy, chemicals, energy utilization, and food.

[0003] A comprehensive model combines the evaporation model and the flash evaporation model. The evaporation model accurately describes the behavior of the feed and liquid during the evaporation process, and is crucial for optimizing the evaporation process, guiding production and achieving energy conservation and consumption reduction. The flash evaporation model accurately models the dynamic characteristics of the feed and liquid during the flash evaporation process, laying the foundation for optimal control of the flash evaporation process.

[0004] However, in some factories, in order to improve the efficiency of heat energy utilization and ensure the evaporation effect, the evaporation process of "multi-effect countercurrent evaporation + multi-stage flash evaporation" is adopted. For example, the five-effect countercurrent evaporation + five-stage flash evaporation process (reference Figure 2 ), consisting of five flash evaporators and five evaporators. In the multi-effect evaporation cascade, the feed liquid is heated by an external heat source or secondary steam. The feed liquid absorbs the heat and reaches a boiling state. The concentrated feed liquid is then discharged to the previous effect for further concentration. The separated water vapor, known as secondary steam, is supplied to the next effect as a heat source. In the multi-stage flash evaporation cascade, each flash evaporator stage uses a throttle valve to reduce the pressure of the feed liquid, lowering its boiling point. The superheated feed liquid is then rapidly vaporized within the separation chamber, undergoing gas-liquid separation. The separated feed liquid is then discharged to the next flash evaporator for further flash evaporation. The separated water vapor heats the feed liquid in the evaporator, achieving multi-stage energy utilization.

[0005] However, the related technologies all establish a consistency model for a single evaporator, and obtain a consistent cascade model of a multi-effect evaporation process by connecting them in series. They also establish a consistency model for a single flash evaporator, and obtain a consistent cascade model of a multi-stage flash evaporation process by connecting them in series. Therefore, there is no multi-effect comprehensive model that can accurately reflect the personalized phase change characteristics of the material and liquid in each effect evaporator and each stage of flash evaporators during the actual evaporation process.

[0006] Because in the multi-effect evaporation cascade section of the evaporation process, the density, temperature, steam temperature, heat, etc. of the liquid in each effect evaporator, which are closely related to heat and mass transfer and phase change concentration, are different from the liquid state and steam state; in its multi-stage flash evaporation cascade section, the density, steam volume, steam chamber pressure, pressure drop, etc. of the liquid in each stage of the flash evaporator, which are closely related to flash self-evaporation and phase change thickening, are also different. This will cause the phase change characteristics of the liquid in each effect evaporator and each stage of the flash evaporator to show personalized differences. However, the comprehensive model in the relevant technology cannot capture these personalized differences, resulting in the model being inaccurate, and then the regulation based on the model is also difficult to accurately control the site, which will lead to increased energy consumption and steam consumption, and even waste or irrational use of resources and energy (electrical energy or chemical energy, thermal energy, and evaporation equipment); at the very least, it will increase production costs, and at worst, it will damage the evaporation or flash evaporation equipment and even cause safety hazards. Summary of the Invention

[0007] This application provides a method for constructing a multi-effect comprehensive model of the evaporation process based on personalized phase change characteristics, which is used to capture the personalized differences in the phase change characteristics of the material and liquid, make the model more accurate, and then accurately control the site based on the regulation of the model.

[0008] In a first aspect, the present application provides a method for constructing a multi-effect comprehensive model of an evaporation process based on personalized phase change characteristics, comprising: establishing a consistent evaporation model of an evaporator based on the material balance principle, and cascading the consistent evaporation model based on a preset number of evaporation effect levels to obtain a multi-effect consistent evaporation model;

[0009] Construct a simplified evaporation function that ignores the volume change caused by mixing solutions of different densities;

[0010] Construct an evaporation relationship function, in which the amount of evaporated water is positively correlated with the heat transfer amount and negatively correlated with the density of the feed liquid;

[0011] The multi-effect evaporation model is obtained by combining the multi-effect consistency evaporation model, the evaporation simplified function and the evaporation relationship function;

[0012] A consistent flash evaporator model is established based on the material balance principle, and a multi-stage consistent flash evaporation model is obtained by cascading the consistent flash evaporation models based on the preset number of flash evaporation levels.

[0013] Construct a simplified flash evaporation function that ignores the volume change caused by mixing solutions of different densities;

[0014] Construct a flash evaporation relationship function, in which the amount of water evaporated is positively correlated with the pressure drop and negatively correlated with the density of the feed liquid;

[0015] The multi-stage flash vaporization model is obtained by combining the multi-stage consistent flash vaporization model, the flash vaporization simplified function and the flash vaporization relationship function;

[0016] The multi-effect comprehensive model of the evaporation process is obtained by combining the multi-effect evaporation model and the multi-stage flash evaporation model;

[0017] The multi-effect comprehensive model is outputted so that the industrial site can refer to the multi-effect comprehensive model to regulate the evaporation process and the flash evaporation process.

[0018] In a second aspect, an embodiment of the present application provides a system for constructing a multi-effect comprehensive model of an evaporation process based on personalized phase change characteristics, the system comprising: one or more processors and a memory;

[0019] The memory is coupled to one or more processors, and is used to store computer program code, which includes computer instructions. The one or more processors call the computer instructions to enable the system for constructing a multi-effect comprehensive model of an evaporation process based on personalized phase change characteristics to perform the method described in the first aspect and any possible implementation of the first aspect.

[0020] In a third aspect, an embodiment of the present application provides a computer program product comprising instructions, which, when executed on a server, enables the server to execute the method described in the first aspect and any possible implementation of the first aspect.

[0021] In a fourth aspect, an embodiment of the present application provides a computer-readable storage medium comprising instructions. When the instructions are executed on a system for constructing a multi-effect comprehensive model of an evaporation process based on personalized phase change characteristics, the system for constructing a multi-effect comprehensive model of an evaporation process based on personalized phase change characteristics executes the method described in the first aspect and any possible implementation method of the first aspect.

[0022] It is understood that the system for constructing a multi-effect comprehensive model of an evaporation process based on personalized phase change characteristics 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 method for constructing a multi-effect comprehensive model of an evaporation process based on personalized phase change characteristics provided in the embodiments of this application. Therefore, the beneficial effects achievable by these methods can be referenced to the beneficial effects of the corresponding methods and will not be further elaborated here.

[0023] One or more technical solutions provided in the embodiments of this application have at least the following technical effects or advantages:

[0024] The present application provides a method for constructing a multi-effect comprehensive model of an evaporation process based on personalized phase change characteristics. By constructing an evaporation relationship function, the quantitative relationship between the amount of water evaporated and the heat transfer is positively correlated and the density of the feed liquid is negatively correlated. This evaporation relationship function fully considers the key role of energy flow in the state change of the feed liquid in the multi-effect evaporation cascade section, can accurately describe the heat and mass transfer behavior of the feed liquid in each effect evaporator, and accurately reflect the dynamic characteristics of the multi-effect evaporation cascade section. By constructing a flash evaporation relationship function, the quantitative relationship between the amount of water evaporated and the pressure drop is positively correlated and the density of the feed liquid is negatively correlated. This flash evaporation relationship function fully considers the self-evaporation state differences of each flash evaporator in the multi-stage flash evaporation cascade section, can accurately describe the self-evaporation behavior of the feed liquid in each flash evaporator, and accurately reflect the dynamic characteristics of the multi-stage flash evaporation cascade section. In this way, the personalized differences in the phase change of the feed liquid in each effect evaporator and each stage of the flash evaporator during the evaporation process are captured, making the model more accurate, and then accurately controlling the site based on the regulation of the model. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 A flow chart of the method for constructing a multi-effect comprehensive model of the evaporation process based on personalized phase change characteristics provided in this application.

[0026] Figure 2 Schematic diagram of the five-effect countercurrent evaporation + five-stage flash evaporation process provided in this application.

[0027] Figure 3 The working principle diagram of the tubular falling film evaporator provided for this application.

[0028] Figure 4 Working principle diagram of the flash evaporator provided for this application.

[0029] Figure 5 A schematic diagram for comparing the relevant multi-effect comprehensive model with the multi-effect comprehensive model of the evaporation process provided in this application.

[0030] Figure 6 A lower-level flow chart of the method for constructing a multi-effect comprehensive model of the evaporation process based on personalized phase change characteristics provided in this application.

[0031] Figure 7 Schematic diagram of the physical device of the evaporation process multi-effect comprehensive model construction system based on personalized phase change characteristics provided in this application. DETAILED DESCRIPTION

[0032] 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 limit the present application.

[0033] For ease of understanding, the following are explanations of the professional terms that appear in the article:

[0034] 1. Multiple-effect evaporator: A multiple-effect evaporator is a device that continuously evaporates and concentrates a solution through multiple evaporation and condensation processes. It consists of multiple evaporators connected in series, each called an "effect." The first-effect evaporator is heated with high-temperature steam, and the resulting secondary steam flows to the next-effect evaporator as a heating source, and so on.

[0035] 2. Multi-stage flash evaporator: A multi-stage flash evaporator is a device that uses the principle of self-evaporation to flash evaporate and condense liquids. It consists of multiple flash chambers connected in series, with the pressure in each chamber decreasing sequentially. High-temperature, high-pressure liquid first enters the first-stage flash chamber. Due to the sudden drop in pressure, some of the liquid evaporates into steam. The remaining liquid enters the next-stage flash chamber, where the pressure drops further, causing further self-evaporation. This process repeats in each flash chamber until the final stage.

[0036] 3. Personalized phase change characteristics: In multi-effect evaporation and multi-stage flash evaporation, the liquid density, temperature, steam temperature, heat, and other liquid states and vapor states that are closely related to heat and mass transfer and phase change concentration in each effect evaporator are different; the liquid density, steam volume, steam chamber pressure, pressure drop, and other states that are closely related to flash self-evaporation and phase change thickening in each stage of the flash evaporator are also different. These differences in state will not only lead to differences in phase change concentration caused by the personalized heat transfer characteristics in each effect evaporator, but also lead to different degrees of phase change thickening caused by the personalized self-evaporation behavior in each stage of the flash evaporator.

[0037] For ease of understanding, the following will explain the usage scenarios of the method for constructing a multi-effect comprehensive model of the evaporation process based on personalized phase change characteristics provided by this application and the defects of the existing model in the scenarios.

[0038] The plant needs to use a multi-effect comprehensive model to optimize and adjust the parameters of the evaporator and flash evaporator. The usual practice is to select the outlet liquid density of a certain effect evaporator or a certain stage flash evaporator (obtained through model calculation) as the control target, and adjust the parameters of the evaporator and flash evaporator according to its deviation from the theoretical value; however, in related technologies, a consistency model of a single evaporator is established, and a consistency cascade model of the multi-effect evaporation process is obtained by connecting them in series, and a consistency model of a single flash evaporator is established, and a consistency cascade model of the multi-stage flash evaporation process is obtained by connecting them in series; therefore, it is difficult to accurately control the site based on the regulation of this model, which will lead to increased energy and steam consumption, and even waste or unreasonable use of resources and energy (electricity or chemical energy, heat energy, and evaporation equipment); at the very least, it will increase production costs, and at worst, it will damage the evaporation equipment and even cause safety hazards.

[0039] For ease of understanding, the causes of the above defects are further explained below.

[0040] Take the five-effect countercurrent evaporation + five-stage flash evaporation process as an example (refer to Figure 2 ), the feed liquid and steam exhibit different flow and change characteristics in the system. The evaporated raw liquid first enters the 5-effect evaporator, and then passes through the 4-effect, 3-effect, 2-effect and 1-effect evaporators in sequence to achieve step-by-step concentration. After leaving the 1-effect evaporator, the feed liquid enters the 1-stage, 2-stage, 3-stage and 4-stage flash evaporators in sequence, and finally obtains the final product in the 5-stage flash evaporator and is discharged from the system. In the multi-effect evaporation cascade section, as the feed liquid flows step by step, its density and temperature continue to increase. After entering the multi-stage flash evaporation cascade section, the feed liquid density continues to increase, but the temperature decreases step by step. New steam is introduced into the 1-effect evaporator to provide heat for the evaporation process. The secondary steam generated by the 1st effect evaporator is used to heat the 2nd effect evaporator. The secondary steam generated by the 2nd effect evaporator and the 1st flash evaporator jointly heat the 3rd effect evaporator. The secondary steam generated by the 3rd effect evaporator and the 2nd flash evaporator jointly heat the 4th effect evaporator. The secondary steam generated by the 4th effect evaporator and the 3rd flash evaporator jointly heat the 5th effect evaporator. The secondary steam generated by the 5th effect evaporator is introduced into the condenser to maintain the vacuum degree of the entire evaporation system.

[0041] Taking the outlet density of the fifth-effect flash evaporator as an example, the problems existing in the relevant multi-effect comprehensive model are explained. In the actual five-effect countercurrent evaporation + five-stage flash evaporation process, the density, temperature, vapor temperature, heat, and other liquid and vapor states closely related to heat and mass transfer, phase change concentration, etc. in each effect evaporator are different. The density, distillation water volume, steam chamber pressure, pressure drop, and other states closely related to flash self-evaporation and phase change thickening in each flash evaporator are also different. These differences in state not only lead to differences in phase change concentration caused by the individual heat transfer characteristics in each effect evaporator, but also lead to different degrees of phase change thickening caused by the individual self-evaporation behavior in each flash evaporator. The comprehensive model in the relevant technology cannot capture these individual differences, resulting in inaccurate models.

[0042] The above has described and derived the usage scenarios of the method for constructing a multi-effect comprehensive model of the evaporation process based on personalized phase change characteristics, as well as the defects and problems of the related multi-effect comprehensive models. The following describes the method for constructing a multi-effect comprehensive model of the evaporation process based on personalized phase change characteristics in this embodiment:

[0043] like Figure 1 As shown, Figure 1 A flow chart of the method for constructing a multi-effect comprehensive model of the evaporation process based on personalized phase change characteristics provided in this application.

[0044] S101. Establish a consistent evaporation model for 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.

[0045] It is worth noting that the preset evaporation effect level number refers to the number of evaporators in the multi-effect evaporation system, which is commonly referred to as the "effect number".

[0046] In a multi-effect evaporation process, each evaporator follows the principle of material balance, which states that 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 material flow and phase change processes within it.

[0047] In a simple example, for a single-effect evaporator, based on the material balance principle, the following consistent evaporation model can be established:

[0048] F i =V i +L i

[0049] In the formula, F i is the feed flow rate of the i-th effect evaporator, V i is the evaporation capacity of the i-th effect evaporator, L i is the discharge flow rate of the i-effect evaporator.

[0050] It should be noted that the above embodiment is only a conventional implementation method provided for simply illustrating the general process of establishing a consistent evaporation model of an evaporator based on the material balance principle, and is not limited here.

[0051] In a preferred embodiment, an evaporation balance equation is constructed based on the feed liquid amount, the inlet feed liquid mass flow rate, the outlet feed liquid mass flow rate, and the steam water amount. The evaporation balance equation is:

[0052]

[0053] In the formula, M i is the amount of liquid in the i-effect evaporator, G in,i is the inlet liquid mass flow rate of the i-th effect evaporator, G out,i is the outlet liquid mass flow rate of the i-th effect evaporator, V i is the amount of water evaporated by the i-effect evaporator;

[0054] As can be seen, based on the material balance principle, an evaporation balance equation was constructed that includes the feed-liquid volume, inlet feed-liquid mass flow rate, outlet feed-liquid mass flow rate, and distilled water volume. Based on the law of conservation of mass, this equation accurately describes the dynamic equilibrium relationship of materials within the multiple-effect evaporator. The inclusion of the feed-liquid volume reflects the real-time changes in the material inventory within the evaporator; the inlet and outlet feed-liquid mass flow rates reflect the material input and output processes; and the inclusion of the distilled water volume accounts for the impact of the evaporation process on the material balance.

[0055] Construct the evaporation analytical equation of the feed liquid volume, inlet feed liquid mass flow rate, and outlet feed liquid mass flow rate. The evaporation analytical equation is:

[0056] M i =ρ i A i h i

[0057] G in,i =ρ in,i F in,i

[0058] G out,i =ρ i F out,i

[0059] In the formula, M i is the amount of liquid in the i-effect evaporator, ρ i is the liquid density of the i-effect evaporator, A i is the effective cross-sectional area of ​​the i-th effect evaporator, h i is the liquid level of the i-effect evaporator, G in,i is the inlet liquid mass flow rate of the i-th effect evaporator, ρ in,i is the inlet liquid density of the i-th effect evaporator, F in,i is the volume flow rate of the inlet liquid of the i-th effect evaporator, G out,i is the outlet liquid mass flow rate of the i-th effect evaporator, F out,i is the outlet liquid volume flow rate of the i-th effect evaporator;

[0060] As can be seen, an analytical evaporation equation has been constructed for the feed liquid quantity, inlet feed liquid mass flow rate, and outlet feed liquid mass flow rate. This analytical evaporation equation incorporates key parameters such as feed liquid density, evaporator effective cross-sectional area, liquid level, and feed liquid volume flow rate to describe the material characteristics of the multi-effect evaporation process. The inclusion of feed liquid density and liquid level reflects the influence of feed liquid properties and evaporator geometry on material inventory; the inlet feed liquid density and volume flow rate determine the material input rate; and the outlet feed liquid volume flow rate reflects the material output process.

[0061] The consistent evaporation model is obtained by combining the evaporation analytical equation and the evaporation equilibrium equation. The consistent evaporation model is:

[0062]

[0063] In the formula, ρ i is the liquid density of the evaporator in the first effect, t is the time, h i is the liquid level of the i-effect evaporator, A i is the effective cross-sectional area of ​​the i-th effect evaporator, ρ in,i is the inlet liquid density of the i-th effect evaporator, Fin,i is the volume flow rate of the inlet liquid of the i-th effect evaporator, F out,i is the outlet liquid volume flow rate of the i-th effect evaporator, V i is the amount of water evaporated from the i-effect evaporator.

[0064] Continuing with the above example, taking the 5-effect evaporation model as an example, a multi-effect consistent evaporation model is obtained based on the preset evaporation effect level number (effect number) cascade consistency evaporation model. The multi-effect consistent evaporation model is:

[0065]

[0066] In the formula, ρ1 is the density of the liquid in the first-effect evaporator, t is the time, h1 is the liquid level in the first-effect evaporator, A1 is the effective cross-sectional area of ​​the first-effect evaporator, ρ in,1 is the inlet liquid density of the first-effect evaporator, F in,1 is the volume flow rate of the inlet liquid of the first effect evaporator, F out,1 is the outlet liquid volume flow rate of the first effect evaporator, V1 is the distillation water volume of the first effect evaporator; ρ2 is the liquid density of the second effect evaporator, h2 is the liquid level of the second effect evaporator, A2 is the effective cross-sectional area of ​​the second effect evaporator, ρ in,2 is the inlet liquid density of the second-effect evaporator, F in,2 is the volume flow rate of the inlet liquid of the second-effect evaporator, F out,2 is the outlet liquid volume flow rate of the second effect evaporator, V2 is the distillation water volume of the second effect evaporator; ρ3 is the liquid density of the third effect evaporator, h3 is the liquid level of the third effect evaporator, A3 is the effective cross-sectional area of ​​the third effect evaporator, ρ in,3 is the inlet liquid density of the third-effect evaporator, F in,3 is the volume flow rate of the inlet liquid of the third-effect evaporator, F out,3 is the outlet liquid volume flow rate of the third-effect evaporator, V3 is the distillation water volume of the third-effect evaporator; ρ4 is the liquid density of the fourth-effect evaporator, h4 is the liquid level of the fourth-effect evaporator, A4 is the effective cross-sectional area of ​​the fourth-effect evaporator, ρ in,4 is the inlet liquid density of the fourth-effect evaporator, F in,4 is the volume flow rate of the inlet liquid of the fourth-effect evaporator, F out,4 is the outlet liquid volume flow rate of the 4th effect evaporator, V4 is the distillation water volume of the 4th effect evaporator; ρ5 is the liquid density of the 5th effect evaporator, h5 is the liquid level of the 5th effect evaporator, A5 is the effective cross-sectional area of ​​the 5th effect evaporator, ρ in,5 is the inlet liquid density of the fifth-effect evaporator, F in,5 is the volume flow rate of the inlet liquid of the fifth-effect evaporator, F out,5 is the outlet liquid volume flow rate of the fifth-effect evaporator, and V5 is the distillation volume of the fifth-effect evaporator.

[0067] In actual use, there is a problem: the density of the liquids in different effects may vary. When these liquids with different densities are mixed, the volume changes, affecting the material balance. To simplify the model complexity and improve computational efficiency, the effect of this volume change can be appropriately ignored during modeling.

[0068] S102. Construct a simplified evaporation function that ignores the volume change caused by mixing solutions of different densities.

[0069] It should be noted that the volumes before and after mixing are considered equal, thus eliminating the effect of volume change from the model.

[0070] In some preferred embodiments, the evaporation simplified function is:

[0071]

[0072] In the formula, h i is the liquid level of the i-th effect evaporator, t is the time, A i is the effective cross-sectional area of ​​the i-effect evaporator, F in,i is the volume flow rate of the inlet liquid of the i-th effect evaporator, F out,i is the outlet liquid volume flow rate of the i-th effect evaporator, V i is the water distillation capacity of the i-th effect evaporator, ρ w is the density of water.

[0073] It should be noted that the above simplified evaporation function is only a preferred embodiment. In other embodiments, other methods may be adopted, which are not limited here.

[0074] As can be seen, based on the consistency evaporation model, a simplified treatment that ignores differences in feed and liquid density is further introduced. Considering that the feed and liquid density may vary between evaporators of different effects, directly using these feed and liquid volume flow rates for material balance calculations may introduce errors. To simplify the model complexity and improve computational efficiency, the volume changes caused by these density differences are appropriately ignored during the modeling process. Although this simplification sacrifices a certain degree of accuracy, it highlights the model's main research issues, making the material balance relationship clearer and easier to solve. By making reasonable simplifying assumptions, the computational workload and time cost can be greatly reduced while ensuring the practicality of the model.

[0075] S103. Construct an evaporation relationship function, in which the amount of evaporated water is positively correlated with the heat transfer and negatively correlated with the density of the feed liquid.

[0076] refer to Figure 3 , Figure 3The working principle diagram of the tubular falling film evaporator provided in this application is as follows to explain the working principle of the evaporator in order to accurately characterize the personalized heat and mass transfer behavior of the feed liquid in each effect evaporator.

[0077] The evaporation process is usually carried out using Figure 3 The tubular falling film evaporator shown here achieves feed liquid concentration. First, the feed liquid is pumped to the top of the evaporator by a circulating pump. After being evenly distributed by the film distributor, it flows downward along the inner wall of the heating tube in the form of a film. Next, the hot steam distributed outside the heating tube transfers heat through the tube wall, causing the liquid film to vaporize as it flows. The high-temperature feed liquid evaporated in the heating chamber and the secondary steam generated are then separated in the separation chamber. The separated secondary steam is sent to the next-stage evaporator as a heat source, while the feed liquid is discharged from the bottom of the separation chamber and sent to the previous stage via the discharge pump for further concentration.

[0078] An analysis of the operating principle of an evaporator reveals that the primary driving force behind liquid concentration comes from the evaporator's heat transfer. The greater the evaporator's heat transfer, the more energy is supplied to the liquid per unit time. This energy is used to raise the liquid's temperature and internal energy, allowing more water molecules to reach the energy state required for evaporation. Therefore, an increase in heat transfer inevitably leads to an increase in evaporation, and the two are positively correlated. Liquid density reflects the relative concentration of solutes and water molecules per unit volume. Higher density means greater solute concentration and a corresponding decrease in free water content. Given the same heat transfer rate, a high-density liquid has fewer water molecules available for evaporation, so evaporation decreases as density increases. Therefore, the amount of water evaporated from an evaporator is positively correlated with heat transfer and negatively correlated with liquid density.

[0079] In some embodiments, the evaporation relationship function is:

[0080]

[0081] In the formula, V i is the steam volume of the i-effect evaporator, Q i is the heat transfer of the i-effect evaporator, ρ i is the outlet liquid density of the i-effect evaporator, A′ i 、C i is the coefficient.

[0082] In other preferred embodiments, the evaporation relationship function is:

[0083]

[0084] In the formula, V i is the steam volume of the i-effect evaporator, Q i is the heat transfer of the i-effect evaporator, ρ i is the outlet liquid density of the i-effect evaporator, ai 、c i is the coefficient, b i d i is a constant.

[0085] It should be noted that the above evaporation relationship function only provides a few embodiments. In other embodiments, other methods may be adopted, which are not limited here.

[0086] S104. The multi-effect consistency evaporation model, the evaporation simplified function, and the evaporation relationship function are combined to obtain a multi-effect evaporation model.

[0087] Simultaneous equations are the combination of multiple equations or inequalities to form a single equation.

[0088] It should be noted that multiple implementation methods are provided for steps S101 to S103. This step merely exemplarily selects one preferred combination of steps S101 to S103, but is not limited to the only implementation path.

[0089] Preferred consistent evaporation model:

[0090]

[0091] Preferred simplified evaporation function:

[0092]

[0093] Preferred evaporation relationship function:

[0094]

[0095] The multi-effect evaporation model is:

[0096]

[0097] In the formula, ρ i is the liquid density of the i-effect evaporator, t is the time, A i is the effective cross-sectional area of ​​the i-th effect evaporator, h i is the liquid level of the i-effect evaporator, F in,i is the volume flow rate of the inlet liquid of the i-th effect evaporator, ρ in,i is the inlet liquid density of the i-effect evaporator, Q i is the heat transfer of the i-effect evaporator, a i is the heat transfer coefficient of the i-effect evaporator, b i is the heat transfer constant of the i-effect evaporator, c i is the density coefficient of the evaporating liquid of the i-th effect evaporator, d i Density constant of the evaporating liquid in the i-th effect evaporator, ρ w is the density of water.

[0098] refer to Figure 2 It should be noted that the above model is only a general way of writing. In actual use, it is still determined by the number of effects of the evaporator. Take the 5-effect evaporation model as an example:

[0099] Because for the feed liquid, the evaporated raw liquid enters the 5-effect evaporator, passes through the 4th effect, 3rd effect, and 2nd effect in turn, and is discharged at the 1st effect. For steam, new steam enters the 1st effect evaporator, the secondary steam of the 1st effect heats the 2nd effect, the secondary steam of the 2nd effect heats the 3rd effect, the secondary steam of the 3rd effect heats the 4th effect, the secondary steam of the 4th effect heats the 5th effect, and the secondary steam of the 5th effect is introduced into the condenser.

[0100] Therefore, the model of the 5-effect evaporation cascade section in the evaporation process is:

[0101]

[0102] Wherein, F0 is the inlet feed liquid volume flow rate of the 5th effect evaporator, F5 is the inlet feed liquid volume flow rate of the 4th effect evaporator, F4 is the inlet feed liquid volume flow rate of the 3rd effect evaporator, F3 is the inlet feed liquid volume flow rate of the 2nd effect evaporator, and F2 is the inlet feed liquid volume flow rate of the 1st effect evaporator.

[0103] It should be noted that step S104 and step S105 are not in a sequential relationship. Step S104 can be executed first and then step S105. Similarly, step S105 can be executed first and then step S104. They can also be performed simultaneously, which is not limited here.

[0104] S105. Establish a consistent flash evaporation model of the flash evaporator based on the material balance principle, and cascade the consistent flash evaporation models based on a preset number of flash evaporation levels to obtain a multi-stage consistent flash evaporation model.

[0105] It is worth noting that the preset number of flash stages refers to the number of flash evaporators in the multi-stage flash system, which is commonly referred to as the "number of stages".

[0106] In a multi-stage flash evaporation process, each stage follows the principle of mass balance, which states that the total amount of material entering the flash evaporator is equal to the total amount of material leaving the flash evaporator. Based on this principle, a mathematical model of a single-stage flash evaporator can be developed to describe the material flow and phase change processes within it.

[0107] In a simple embodiment, for a single-stage flash evaporator, based on the material balance principle, the following consistent flash evaporation model can be established:

[0108] F i =V i +L i

[0109] In the formula, Fi is the feed flow rate of the i-th stage flash evaporator, V i is the water distillation capacity of the i-th stage flash evaporator, L i is the discharge flow rate of the i-th stage flash evaporator.

[0110] It should be noted that the above embodiment is only a conventional implementation method provided for simply illustrating the general process of establishing a consistent flash evaporation model of a flash evaporator based on the material balance principle, and is not limited here.

[0111] In a preferred embodiment, a flash equilibrium equation is constructed based on the feed liquid amount, the inlet feed liquid mass flow rate, the outlet feed liquid mass flow rate, and the steam water amount. The flash equilibrium equation is:

[0112]

[0113] In the formula, M j S is the amount of liquid in the j-th stage flash evaporator, is the inlet liquid mass flow rate of the j-th stage flash evaporator, is the outlet liquid mass flow rate of the j-th stage flash evaporator, is the amount of water evaporated by the j-th stage flash evaporator;

[0114] As can be seen, based on the material balance principle, a flash evaporation equilibrium equation was constructed that includes the feed-liquid volume, inlet feed-liquid mass flow rate, outlet feed-liquid mass flow rate, and distilled water volume. Based on the law of conservation of mass, this equation accurately describes the dynamic equilibrium relationship of materials within a multi-stage flash evaporator. The inclusion of the feed-liquid volume reflects the real-time inventory changes within the flash evaporator; the inlet and outlet feed-liquid mass flow rates reflect the material input and output processes; and the inclusion of the distilled water volume accounts for the impact of the flash evaporation process on the material balance.

[0115] Construct the flash evaporation analytical equation of the feed liquid volume, inlet feed liquid mass flow rate, and outlet feed liquid mass flow rate. The flash evaporation analytical equation is:

[0116]

[0117] In the formula, is the amount of liquid in the j-th stage flash evaporator, is the density of the liquid in the j-th stage flash evaporator, is the effective cross-sectional area of ​​the j-th stage flash evaporator, is the liquid level of the j-th stage flash evaporator, is the inlet liquid mass flow rate of the j-th stage flash evaporator, is the inlet liquid density of the j-th stage flash evaporator, is the volume flow rate of the inlet liquid of the j-th stage flash evaporator, is the outlet liquid mass flow rate of the j-th stage flash evaporator, is the outlet liquid volume flow rate of the j-th stage flash evaporator;

[0118] As can be seen, analytical flash evaporation equations for feed liquid quantity, inlet feed liquid mass flow rate, and outlet feed liquid mass flow rate have been constructed. These analytical flash evaporation equations incorporate key parameters such as feed liquid density, flash evaporator effective cross-sectional area, liquid level, and feed liquid volume flow rate, describing the material characteristics of the multi-stage flash evaporation process. The inclusion of feed liquid density and liquid level reflects the influence of feed liquid properties and flash evaporator geometry on material inventory; the inlet feed liquid density and volume flow rate determine the material input rate; and the outlet feed liquid volume flow rate reflects the material output process.

[0119] The consistent flash evaporation model is obtained by combining the flash evaporation analytical equation and the flash evaporation equilibrium equation. The consistent flash evaporation model is:

[0120]

[0121] In the formula, is the density of the liquid in the j-th stage flash evaporator, t is the time, is the liquid level of the j-th stage flash evaporator, is the effective cross-sectional area of ​​the j-th stage flash evaporator, is the inlet liquid density of the j-th stage flash evaporator, is the volume flow rate of the inlet liquid of the j-th stage flash evaporator, is the outlet liquid volume flow rate of the j-th stage flash evaporator, V j S is the amount of water evaporated in the j-th stage flash evaporator.

[0122] Continuing with the above example, taking the 5-level flash model as an example, based on the preset number of flash levels, the cascade consistency flash model is cascaded to obtain a multi-level consistency flash model. The multi-level consistency flash model is:

[0123]

[0124] In the formula, is the liquid density of the first stage flash evaporator, t is the time, is the liquid level of the first-stage flash evaporator, is the effective cross-sectional area of ​​the first-stage flash evaporator, is the inlet liquid density of the first stage flash evaporator, is the inlet liquid volume flow rate of the first stage flash evaporator, is the outlet liquid volume flow rate of the first stage flash evaporator, is the amount of water evaporated in the first stage flash evaporator; is the liquid density of the second-stage flash evaporator, is the liquid level of the second-stage flash evaporator, is the effective cross-sectional area of ​​the second-stage flash evaporator, is the inlet liquid density of the second-stage flash evaporator, is the volume flow rate of the inlet liquid of the second-stage flash evaporator, is the outlet liquid volume flow rate of the second-stage flash evaporator, is the water distillation capacity of the second-stage flash evaporator, is the density of the liquid in the third-stage flash evaporator, is the liquid level of the third-stage flash evaporator, is the effective cross-sectional area of ​​the third-stage flash evaporator, is the inlet liquid density of the third-stage flash evaporator, is the volume flow rate of the inlet liquid of the third-stage flash evaporator, is the outlet liquid volume flow rate of the third-stage flash evaporator, is the water distillation capacity of the third-stage flash evaporator, is the liquid density of the 4th stage flash evaporator, is the liquid level of the 4th stage flash evaporator, is the effective cross-sectional area of ​​the 4th stage flash evaporator, is the inlet liquid density of the 4th stage flash evaporator, is the inlet liquid volume flow rate of the 4th stage flash evaporator, is the outlet liquid volume flow rate of the 4th stage flash evaporator, is the water distillation capacity of the 4th stage flash evaporator, is the density of the liquid in the fifth-stage flash evaporator, is the liquid level of the 5th stage flash evaporator, is the effective cross-sectional area of ​​the fifth-stage flash evaporator, is the inlet liquid density of the fifth-stage flash evaporator, is the volume flow rate of the inlet liquid of the fifth-stage flash evaporator, is the outlet liquid volume flow rate of the fifth-stage flash evaporator, is the amount of water evaporated in the 5th stage flash evaporator.

[0125] In actual use, there is a problem: the density of the liquids in different stages may vary. When these liquids with different densities are mixed, the volume changes, affecting the material balance. To simplify the model complexity and improve computational efficiency, the effect of this volume change can be appropriately ignored during modeling.

[0126] S106. Construct a simplified flash evaporation function that ignores the volume change caused by mixing solutions of different densities.

[0127] It should be noted that the volumes before and after mixing are considered equal, thus eliminating the effect of volume change from the model.

[0128] In some preferred embodiments, the flash evaporation simplified function is:

[0129]

[0130] In the formula, is the liquid level of the j-th stage flash evaporator, t is the time, is the effective cross-sectional area of ​​the j-th stage flash evaporator, is the volume flow rate of the inlet liquid of the j-th stage flash evaporator, is the outlet liquid volume flow rate of the j-th stage flash evaporator, V j S is the water distillation capacity of the j-th stage flash evaporator, ρ w is the density of water;

[0131] It should be noted that the above simplified flash evaporation function is only a preferred embodiment. In other embodiments, other methods may be adopted, which are not limited here.

[0132] It can be seen that on the basis of the consistent flash evaporation model, a simplified treatment of ignoring the difference in feed and liquid density is further introduced. Considering that the feed and liquid density between different stages of flash evaporators may be different, directly using these feed and liquid volume flow rates for material balance calculations may introduce errors. In order to simplify the complexity of the model and improve the calculation efficiency, the volume changes caused by this density difference are appropriately ignored during the modeling process. Although this simplified treatment sacrifices a certain degree of accuracy, it highlights the main research issues of the model and makes the material balance relationship clearer and easier to solve. Through reasonable simplified assumptions, the practicality of the model can be ensured while greatly reducing the amount of calculation and time cost.

[0133] S107. Construct a flash evaporation relationship function, in which the amount of evaporated water is positively correlated with the pressure drop and negatively correlated with the density of the feed liquid.

[0134] refer to Figure 4 , Figure 4 The working principle diagram of the flash evaporator provided in this application is as follows to explain the working principle of the flash evaporator in order to accurately characterize the personalized self-evaporation behavior of the liquid in each level of the flash evaporator.

[0135] The flash evaporation process is usually carried out using Figure 4 The flash evaporator shown realizes the concentration of the feed liquid. The flash evaporator consists of a throttle valve and a separation chamber, which can realize the rapid boiling and gasification of the high-temperature and high-pressure feed liquid.

[0136] The flash evaporation process works as follows: First, the high-temperature, high-pressure liquid passes through a throttle valve, where its pressure is instantly reduced, lowering its boiling point and causing it to superheat. The superheated liquid then enters a separation chamber, where it rapidly boils and vaporizes, separating the vapor and liquid phases and achieving self-evaporation. Steam is discharged from the top of the separation chamber, while the concentrated liquid exits from the bottom. Multi-stage flash evaporation is based on the principle of single-stage flash evaporation. The liquid passes through multiple flash evaporators in series, undergoing pressure reduction, self-evaporation, and vapor-liquid separation within each stage, achieving progressive concentration.

[0137] An analysis of the operating principle of a flash evaporator reveals that the greater the pressure drop across the flash evaporator, the lower the boiling point of the feed liquid after depressurization. The more sensible heat released by the superheated feed liquid upon reaching saturation after depressurization, the more heat the feed liquid absorbs as latent heat, resulting in a greater amount of water vapor generated through self-evaporation. Therefore, the water vapor output of a flash evaporator is positively correlated with its pressure drop. The higher the density of the feed liquid, the more latent heat is required to evaporate a unit mass of water, which in turn creates a greater resistance to the self-evaporation process and results in a relatively lower amount of water vapor generated. Consequently, the water vapor output of a flash evaporator is negatively correlated with the density of the feed liquid.

[0138] In some embodiments, the flash relationship function is:

[0139]

[0140] In the formula, is the water distillation capacity of the j-th stage flash evaporator, is the pressure drop of the j-th stage flash evaporator, is the outlet liquid density of the j-th stage flash evaporator, is the coefficient.

[0141] In other preferred embodiments, the flash relationship function is:

[0142]

[0143] In the formula, is the water distillation capacity of the j-th stage flash evaporator, is the pressure drop of the j-th stage flash evaporator, is the outlet liquid density of the j-th stage flash evaporator, is the coefficient, is a constant.

[0144] It should be noted that the above flash vaporization relationship function only provides a few embodiments. In other embodiments, other methods may be adopted, which are not limited here.

[0145] S108. Combine the multi-stage consistent flash vaporization model, the flash vaporization simplified function, and the flash vaporization relationship function to obtain a multi-stage flash vaporization model.

[0146] Simultaneous equations are the combination of multiple equations or inequalities to form a single equation.

[0147] It should be noted that multiple implementation methods are provided for steps S101 to S103. This step merely exemplarily selects one preferred combination of steps S101 to S103, but is not limited to the only implementation path.

[0148] Preferred consistency flash model:

[0149]

[0150] Preferred flash simplification function:

[0151]

[0152] Preferred flash relationship function:

[0153]

[0154] The multi-stage flash evaporation model is:

[0155]

[0156] In the formula, is the liquid density of the i-th stage flash evaporator, t is the time, is the effective cross-sectional area of ​​the i-th stage flash evaporator, is the liquid level of the i-th stage flash evaporator, is the volume flow rate of the inlet liquid of the i-th stage flash evaporator, is the inlet liquid density of the i-th stage flash evaporator, is the pressure drop of the i-th stage flash evaporator, is the pressure drop coefficient of the i-th stage flash evaporator, is the pressure drop constant of the i-th stage flash evaporator, is the density coefficient of the flash liquid in the i-th stage flash evaporator, The density constant of the flash liquid in the i-th stage flash evaporator, ρ w is the density of water.

[0157] refer to Figure 2 It should be noted that the above model is only a general way of writing. In actual use, it is still determined by the number of flash evaporator stages. Take the 5-stage flash evaporation model as an example:

[0158] Because for the liquid, the flash evaporation liquid enters from the 1st stage flash evaporator, passes through the 2nd stage flash evaporator, the 3rd stage flash evaporator, the 4th stage flash evaporator in sequence, and is discharged from the 5th stage flash evaporator. Therefore, the 5-stage flash evaporation model is:

[0159]

[0160] Where F1 is the volume flow rate of the inlet liquid of the first stage flash evaporator, is the volume flow rate of the inlet liquid of the second-stage flash evaporator, is the volume flow rate of the inlet liquid of the third-stage flash evaporator, is the inlet liquid volume flow rate of the 4th stage flash evaporator, is the volume flow rate of the inlet liquid of the 5th stage flash evaporator, ρ1 is the density of the inlet liquid of the 1st stage flash evaporator.

[0161] S109. Combine the multi-effect evaporation model and the multi-stage flash evaporation model to obtain a multi-effect comprehensive model of the evaporation process.

[0162] Continuing from the above example, the 5-effect evaporation model is:

[0163]

[0164]

[0165] The 5-stage flash model is:

[0166]

[0167] Combined to get:

[0168]

[0169] S110. Output a multi-effect comprehensive model of the evaporation process, so that the industrial site can refer to the multi-effect comprehensive model to regulate the evaporation process and the flash evaporation process.

[0170] refer to Figure 5 , Figure 5 A schematic diagram for comparing the relevant multi-effect comprehensive model with the multi-effect comprehensive model of the evaporation process provided in this application.

[0171] Figure 5 The upper "wavy line" segment in the figure is the actual outlet liquid density of the 5-stage flash evaporator, the other "wavy line" segment above is the outlet liquid density of the 5-effect flash evaporator predicted by the multi-effect evaporation model of the evaporation process provided by this application, and the lower "wavy line" segment is the outlet liquid density of the 5-effect flash evaporator predicted by the multi-effect evaporation model provided by the related art. It can be seen that the actual average outlet liquid density of the 5-stage flash evaporator is 1348.2 kg / m 3 The actual average density of the outlet liquid of the 5-effect flash evaporator predicted by the multi-effect evaporation model of the evaporation process provided in this application is 1348 kg / m 3 The actual average density of the outlet liquid of the 5-effect flash evaporator predicted by the multi-effect evaporation model provided by the relevant technology is 1298.4g / m 3It can be seen that the data predicted by the multi-effect comprehensive model of the evaporation process provided by the present application is more accurate than the data predicted by the multi-effect evaporation model provided by the related art.

[0172] It can be seen that by constructing the evaporation relationship function, a quantitative relationship is clearly established: the amount of water evaporated is positively correlated with the heat transfer rate and negatively correlated with the density of the feed liquid. This evaporation relationship function fully considers the key role of energy flow in the change of the feed liquid state during the evaporation process, can accurately describe the heat and mass transfer behavior of the feed liquid in each effect evaporator, and accurately reflect the dynamic characteristics of the multi-effect evaporation process. By constructing the flash evaporation relationship function, a quantitative relationship is clearly established: the amount of water evaporated is positively correlated with the pressure drop and negatively correlated with the density of the feed liquid. This flash evaporation relationship function fully considers the differences in the self-evaporation state of each flash evaporator in the multi-stage flash evaporation process, can accurately describe the self-evaporation behavior of the feed liquid in each flash evaporator, and accurately reflect the dynamic characteristics of the multi-stage flash evaporation process. In this way, these individual differences are captured, making the model more accurate, and then precise control of the site is achieved based on the regulation of this model.

[0173] A preferred embodiment is provided below:

[0174] refer to Figure 6 , Figure 6 A lower-level flow chart of the method for constructing a multi-effect comprehensive model of the evaporation process based on personalized phase change characteristics provided in this application.

[0175] S601. Establish a consistent evaporation model for 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.

[0176] The consistent evaporation model is:

[0177]

[0178] It should be noted that the principle and process of this step have been specifically disclosed in step S101. The relevant principles and processes can be referred to step S101 and will not be repeated here.

[0179] S602. Construct a simplified evaporation function that ignores the volume change caused by mixing solutions of different densities.

[0180] The simplified evaporation function is:

[0181]

[0182] It should be noted that the principle and process of this step have been specifically disclosed in step S102. The relevant principles and processes can be referred to step S102 and will not be repeated here.

[0183] S603. Construct an evaporation relationship function, in which the amount of evaporated water is the ratio of the heat transfer function to the density function of the feed liquid. The heat transfer function is determined by multiplying the heat transfer function by the heat transfer coefficient and adding a heat transfer constant to the product. The density function of the feed liquid is determined by multiplying the density of the feed liquid by the evaporation feed liquid density coefficient and adding an evaporation feed liquid density constant to the product.

[0184] The evaporation relationship function is:

[0185]

[0186] It should be noted that the principle and process of this step have been specifically disclosed in step S103. The relevant principles and processes can be referred to step S103 and will not be repeated here.

[0187] As can be seen, the expression of the heat transfer function and the liquid density function has been further refined when constructing the evaporation relationship function. In addition to introducing the heat transfer coefficient and the evaporation liquid density coefficient to describe the influence of heat transfer and liquid density, a heat transfer constant term and an evaporation liquid density constant term have also been added to the function. By adjusting the value of the constant term, the output of the heat transfer function and the liquid density function can be fine-tuned while maintaining the heat transfer coefficient and the evaporation liquid density coefficient unchanged. This allows for local optimization of the model without changing the overall form of the function, which helps to further improve model accuracy.

[0188] In other embodiments, the amount of evaporated water in the evaporation relationship function is the ratio of the product of the heat transfer and the heat transfer factor to the product of the density of the feed liquid and the evaporation feed liquid density factor, which is not limited here.

[0189] It can be seen that when constructing the evaporation relationship function, the amount of steam evaporated in the evaporator is expressed as the ratio of the product of the heat transfer and the heat transfer factor to the product of the feed liquid density and the evaporation feed liquid density factor. This is used to quantitatively describe the degree of influence of the heat transfer and feed liquid density on the amount of steam evaporated in the evaporator, reflecting the correlation between them.

[0190] S604. The multi-effect consistency evaporation model, the evaporation simplified function, and the evaporation relationship function are combined to obtain a multi-effect evaporation model.

[0191] The multi-effect evaporation model is:

[0192]

[0193] S605: Establish a consistent flash evaporation model of the flash evaporator based on the material balance principle, and cascade the consistent flash evaporation models based on a preset number of flash evaporation levels to obtain a multi-stage consistent flash evaporation model.

[0194] The consistent flash model is:

[0195]

[0196] It should be noted that the principle and process of this step have been specifically disclosed in step S105. The relevant principles and processes can be referred to step S105 and will not be repeated here.

[0197] S606. Construct a simplified flash evaporation function that ignores the volume change caused by mixing solutions of different densities.

[0198] The flash evaporation simplified function is:

[0199]

[0200] It should be noted that the principle and process of this step have been specifically disclosed in step S106. The relevant principles and processes can be referred to step S106 and will not be repeated here.

[0201] S607. Construct a flash evaporation relationship function. In the flash evaporation relationship function, the amount of water evaporated is the ratio of the pressure reduction function to the density function of the feed liquid. The pressure reduction function is determined by multiplying the pressure reduction by the pressure reduction coefficient and adding a pressure reduction constant to the product. The density function of the feed liquid is determined by multiplying the density of the feed liquid by the flash evaporation feed liquid density coefficient and adding a flash evaporation feed liquid density constant to the product.

[0202] The flash relationship function is:

[0203]

[0204] It should be noted that the principle and process of this step have been specifically disclosed in step S107. The relevant principles and processes can be referred to step S107 and will not be repeated here.

[0205] It can be seen that adding a constant term to the existing pressure drop coefficient and flash evaporation liquid density coefficient allows for fine-tuning of the output of the pressure drop and evaporation liquid density functions without changing the overall form of the functions. This fine-tuning can compensate for errors introduced by model simplification and parameter estimation, enabling the flash evaporation relationship function to more accurately describe the relationship between flash evaporation water yield, pressure drop, and evaporation liquid density in the multi-effect integrated evaporation process.

[0206] In other embodiments, the amount of water evaporated in the flash evaporation relationship function is the ratio of the product of the pressure drop and the pressure drop factor to the product of the density of the feed liquid and the flash evaporation feed liquid density factor.

[0207] S608 , combining the multi-level consistent flash vaporization model, the flash vaporization simplified function, and the flash vaporization relationship function to obtain a multi-level flash vaporization model.

[0208] The multi-stage flash evaporation model is:

[0209]

[0210] S609. Adjust the values ​​of all heat transfer coefficients, heat transfer constants, evaporation feed liquid density coefficients, evaporation feed liquid density constants, pressure drop coefficients, pressure drop constants, flash feed liquid density coefficients, and flash feed liquid density constants within a preset number of iterations, and obtain the difference between the simulated data calculated by the multi-effect comprehensive model of the evaporation process and the actual data.

[0211] Taking the 5-effect comprehensive model (5-effect evaporation model + 5-stage flash evaporation model) as an example, this step is described in detail.

[0212] The 5-effect comprehensive model is:

[0213]

[0214] The parameter identification problem of the evaporation process can be transformed into an optimization problem to be solved, and its goal is to minimize the difference between the simulated data obtained by estimating the parameters and the actual data;

[0215] The parameter identification and optimization problem of the multi-effect comprehensive process of evaporation process is:

[0216]

[0217] The error function of each pair of simulated data and actual data is defined by the following formula:

[0218]

[0219] In the formula, F′ obj (x) is the root mean square error between the 5-flash simulated discharge density obtained by identifying the N sample data and the actual discharge density, that is, the objective function of the parameter identification optimization problem. x is the personalized phase change characteristic parameter to be identified in the multi-effect comprehensive model of the evaporation process, that is, the decision variable of the parameter identification optimization problem. N is the number of data pairs used for parameter identification. is the error between the simulated data and the actual data obtained for the i-th data pair, is the kinetic model of the above five-effect five-flash comprehensive evaporation process, p 5,i represents the feed liquid density of the i-th data pair, represents the discharge liquid density of the i-th data pair; In order to perform the integration operation on the above five-effect five-flash comprehensive model in period T1, the density of the discharge liquid corresponding to the comprehensive evaporation process of the i-th data pair is obtained according to the parameter x obtained by identification. The analog value of is the discharge liquid density p of the five-effect five-flash comprehensive evaporation process corresponding to the i-th data pair obtained based on the parameter x obtained by identification 5,i The difference between the simulated value and the actual value.

[0220] In other specific embodiments, further technical solutions are provided to solve the parameter identification problem of the above-mentioned multi-effect comprehensive evaporation process;

[0221] The specific steps are as follows:

[0222] S1. Randomly generate an initial population in the decision space, where each individual represents a solution (decision variable);

[0223] The decision space refers to the set of all feasible solutions to the optimization problem, and each solution consists of a set of values ​​of decision variables.

[0224] The initial population refers to the set of feasible solutions in the optimization problem, each of which consists of a set of values ​​of decision variables.

[0225] This step is the starting point of the CJAYA algorithm, providing initial search points for subsequent optimization. In parameter identification problems, decision variables typically correspond to the model parameters to be identified. Randomly generating the initial population means randomly selecting a certain number of points within the decision space as the starting search locations. This has the advantage of increasing population diversity and preventing the algorithm from prematurely falling into local optima.

[0226] S2. For each solution in the population, the fitness value is calculated according to its corresponding decision variable. The fitness value is calculated by the objective function of the defined optimization problem. The optimization goal of parameter identification is:

[0227]

[0228] The fitness value refers to the objective function value corresponding to each candidate solution.

[0229] For the parameter identification problem, we hope to find a set of parameters that makes the output of the model as close as possible to the actual measured data. Therefore, the fitness function should be designed as a measure of the error between the simulated value and the measured value.

[0230] S3. Set the number of iterations or other termination conditions so that the algorithm stops when certain conditions are met;

[0231] S4. For each individual in the population, generate a new individual and calculate the fitness value (objective function) of the new individual.

[0232] However, in the decision space of parameter identification problems, different dimensions have different search ranges, making the entire decision space complex and variable. When optimizing algorithms to solve such problems, they may over-search some decision dimensions and under-search others. This imbalanced search can affect the algorithm's convergence speed and solution quality, making it difficult to find the global optimal solution.

[0233] Therefore, step S4 may 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.

[0234] Then in some specific embodiments: the CJAYA algorithm uses a dynamic clustering weight strategy to generate new individuals. Specifically, CJAYA divides the population into several subgroups through a clustering learning model, and determines the optimal value and the worst value within each class. Other individuals within the class learn from the optimal, worst, global optimal, and global worst individuals with a certain probability to determine the direction of evolution. At the same time, the algorithm introduces dynamic weights to adaptively adjust the learning intensity of individuals within the class, so that individuals of different categories have different learning strategies and learning steps. In this way, the algorithm can carry out effective searches in various dimensions of the decision variables, and find high-quality solutions that meet the optimization goals by exploring different parameter combinations. The dynamic clustering weight strategy can balance the global exploration and local development capabilities of the algorithm, and improve the search efficiency and solution quality of the algorithm in complex decision spaces.

[0235] However, taking the multi-effect integrated model of the evaporation process as an example, the multi-effect integrated model consists of 10 cascaded differential equations. For a sample data pair, calculating the simulated value of the discharge density based on the input density and the parameters to be identified requires the continuous solution of 10 differential equations. This process is not only highly nonlinear, but also involves a large number of parameters. Changes in any parameter may have a significant impact on the results. Therefore, solving such highly nonlinear optimization problems is very difficult. When dealing with such problems, traditional optimization algorithms often have difficulty escaping local optimality or have a slow convergence speed, resulting in poor optimization performance.

[0236] 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;

[0237] In some specific embodiments, the CJAYA algorithm uses a multi-experience learning strategy to generate new individuals. To solve this problem, the algorithm clusters the entire population into several subspaces. Within each cluster subspace, the current individual learns from other individuals in the cluster to varying degrees, including learning from the optimal individual in the cluster, learning from randomly selected high-quality individuals, and learning from the global optimal individual. By comprehensively utilizing multiple learning experiences, individuals can escape local optimality 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 rationally scheduling different learning modes, which helps the algorithm converge to the global optimal solution more accurately, thereby achieving good solution performance.

[0238] In other embodiments, step S4 may 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 to simultaneously solve the above problems.

[0239] S5. Update the corresponding individuals in the current population according to the fitness value of the new individuals produced;

[0240] The optimal solution plays a crucial role in the parameter identification search process, as it guides and attracts other individuals to its region. However, for the multimodal parameter identification problem of the evaporation process, 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, causing the algorithm to converge prematurely and fail to find the global optimal solution. This phenomenon seriously affects the algorithm's optimization performance and solution quality.

[0241] Therefore, in some embodiments, the method further includes: S6, updating the optimal solution of the population according to the designed “chaotic elite strategy”;

[0242] A chaotic elite learning strategy is introduced to adjust the quality of the optimal solution. The chaotic sequence has randomness and ergodicity, which is conducive to generating new elite individuals to improve the quality of the solution.

[0243] The implementation process of the chaotic elite learning strategy is as follows: First, a chaotic sequence is generated based on the optimal individual in the current population. This chaotic sequence is then used to perturb the decision variables of the optimal individual to generate several new elite individuals. These new elite individuals are then compared with the original optimal individual, and the individual with the highest fitness value is selected as the new optimal solution. In this way, the algorithm can continuously generate new solutions of higher quality while retaining the original optimal solution, effectively escaping from local optima.

[0244] S7. According to the predefined stopping condition (maximum number of iterations), determine whether to terminate the algorithm. 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.

[0245] S610. When the difference is minimum, determine the values ​​of all heat transfer coefficients, heat transfer constants, evaporation liquid density coefficients, evaporation liquid density constants, pressure drop coefficients, pressure drop constants, flash liquid density coefficients, and flash liquid density constants.

[0246] 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, dynamic optimization of the parameters in the evaporation relationship function can be achieved. Through iterative optimization, the optimal parameter combination can be selected from a subset of choices, obtaining the values ​​of each parameter with the smallest differences. Compared with optimizing a single parameter type, this comprehensive optimization method can more comprehensively consider the relationship between various parameters, enabling the multi-effect comprehensive model of the evaporation process to achieve the optimal solution overall, improving the accuracy of the multi-effect comprehensive model and thereby capturing the individual differences in the phase change characteristics of the material and liquid during the evaporation process.

[0247] S611. Combine the multi-effect evaporation model and the multi-stage flash evaporation model to obtain a multi-effect comprehensive model of the evaporation process.

[0248] The 5-effect comprehensive model is:

[0249]

[0250]

[0251] S612. Output a multi-effect comprehensive model of the evaporation process so that the industrial site can refer to the multi-effect comprehensive model to regulate the evaporation process and the flash evaporation process.

[0252] Reference Figure 7 , which is a schematic diagram of the physical device of the system for constructing a multi-effect comprehensive model of an evaporation process based on personalized phase change characteristics provided in this application. The computer 700 may 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.

[0253] Among them, the communication bus 702 is used to realize the connection and communication between these components. The user interface 703 may include a display screen (Display), a camera (Camera), and the network interface 704 may optionally include a standard wired interface, a wireless interface (such as a WI-FI interface). The processor 701 may include one or more processing cores. The processor 701 uses various interfaces and lines to connect the various parts of the entire server, and executes 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. Figure 7 , the memory 705 as a computer storage medium may include an operating system, a network communication module, a user interface module, and an application program constructed based on a multi-effect comprehensive model of personalized phase change characteristics.

[0254] exist Figure 7 In the computer 700 shown, the user interface 703 is mainly used to provide an input interface for the user and obtain data input by the user; and the processor 701 can be used to call the application program stored in the memory 705 for constructing a multi-effect comprehensive model of the evaporation process based on personalized phase change characteristics. When executed by one or more processors 701, the computer 700 executes one or more methods in the above-mentioned embodiments.

[0255] If the integrated unit is implemented in the form of a software functional unit and sold or used as an independent product, it can be stored in a computer-readable memory.

[0256] In the above embodiments, when implemented using software, they may be implemented in whole or in part 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, the processes or functions described in the embodiments of the present application are generated in whole or in part.

Claims

1. A method for constructing a multi-effect comprehensive model of evaporation process based on personalized phase change characteristics, characterized in that: include: A consistent evaporation model of the evaporator is established based on the material balance principle, and the consistent evaporation model is cascaded based on a preset number of evaporation effect levels to obtain a multi-effect consistent evaporation model; Construct a simplified evaporation function that ignores the volume change caused by mixing solutions of different densities; Constructing an evaporation relationship function, in which the amount of evaporated water is positively correlated with the heat transfer amount and negatively correlated with the density of the feed liquid; The multi-effect consistency evaporation model, the evaporation simplified function, and the evaporation relationship function are combined to obtain a multi-effect evaporation model; A consistent flash evaporation model of a flash evaporator is established based on the material balance principle, and the consistent flash evaporation model is cascaded based on a preset number of flash evaporation levels to obtain a multi-stage consistent flash evaporation model; Construct a simplified flash evaporation function that ignores the volume change caused by mixing solutions of different densities; Constructing a flash evaporation relationship function, wherein the amount of water evaporated is positively correlated with the pressure drop and negatively correlated with the density of the feed liquid; The multi-stage consistent flash vaporization model, the flash vaporization simplified function, and the flash vaporization relationship function are combined to obtain a multi-stage flash vaporization model; Combining the multi-effect evaporation model and the multi-stage flash evaporation model to obtain a multi-effect comprehensive model of the evaporation process; The multi-effect comprehensive model is outputted so that the industrial site can regulate the evaporation process and the flash evaporation process by referring to the multi-effect comprehensive model.

2. The method for constructing a multi-effect comprehensive model of an evaporation process based on personalized phase change characteristics according to claim 1, characterized in that: The step of constructing an evaporation relationship function, wherein the amount of evaporated water is positively correlated with the heat transfer amount and negatively correlated with the density of the feed liquid, specifically includes: Constructing an evaporation relationship function, wherein the amount of evaporated water is the ratio of the product of the heat transfer and the heat transfer factor to the product of the density of the feed liquid and the evaporation feed liquid density factor; The step of constructing a flash evaporation relationship function, wherein the amount of water evaporated is positively correlated with the pressure drop and negatively correlated with the density of the feed liquid, specifically includes: A flash evaporation relationship function is constructed, in which the amount of water evaporated is the ratio of the product of the pressure drop and the pressure drop factor to the product of the density of the feed liquid and the flash evaporation feed liquid density factor.

3. The method for constructing a multi-effect comprehensive model of an evaporation process based on personalized phase change characteristics according to claim 2, characterized in that: Before the step of combining the multi-effect evaporation model and the multi-stage flash evaporation model to obtain a multi-effect comprehensive model of the evaporation process, the method further includes: Adjusting the values ​​of all the heat transfer factors, the evaporation liquid density factors, the pressure drop factors, and the flash liquid density factors within a preset number of iterations, and obtaining the difference between the simulated data calculated by the multi-effect comprehensive model of the evaporation process and the actual data; When the difference is minimum, the values ​​of all the heat transfer factors, the evaporation liquid density factors, the pressure drop factors and the flash liquid density factors are determined.

4. The method for constructing a multi-effect comprehensive model of an evaporation process based on personalized phase change characteristics according to claim 1, characterized in that: The step of constructing an evaporation relationship function, wherein the amount of evaporated water is positively correlated with the heat transfer amount and negatively correlated with the density of the feed liquid, specifically includes: Constructing an evaporation relationship function, wherein the amount of evaporated water is a ratio of a heat transfer function to a density function of the feed liquid, wherein the heat transfer function is determined by multiplying the heat transfer function by a heat transfer coefficient and adding a heat transfer constant to the product, and the density function of the feed liquid is determined by multiplying the density of the feed liquid by a density coefficient of the evaporating feed liquid and adding an evaporating feed liquid density constant to the product; The step of constructing a flash evaporation relationship function, wherein the amount of water evaporated is positively correlated with the pressure drop and negatively correlated with the density of the feed liquid, specifically includes: A flash evaporation relationship function is constructed, in which the amount of water evaporated is the ratio of a pressure drop function to a density function of the feed liquid. The pressure drop function is determined by multiplying the pressure drop by a pressure drop coefficient and adding a pressure drop constant to the product. The density function of the feed liquid is determined by multiplying the density of the feed liquid by the flash evaporation feed liquid density coefficient and adding a flash evaporation feed liquid density constant to the product.

5. The method for constructing a multi-effect comprehensive model of an evaporation process based on personalized phase change characteristics according to claim 4, characterized in that: Before the step of combining the multi-effect evaporation model and the multi-stage flash evaporation model to obtain a multi-effect comprehensive model of the evaporation process, the method further includes: Adjusting the values ​​of all the heat transfer coefficients, the heat transfer constants, the evaporation feed liquid density coefficients, the evaporation feed liquid density constants, the pressure drop coefficients, the pressure drop constants, the flash feed liquid density coefficients, and the flash feed liquid density constants within a preset number of iterations, and obtaining the difference between the simulated data calculated by the multi-effect integrated model of the evaporation process and the actual data; When the difference is minimum, the values ​​of all the heat transfer coefficient, the heat transfer constant, the evaporation liquid density coefficient, the evaporation liquid density constant, the pressure drop coefficient, the pressure drop constant, the flash liquid density coefficient and the flash liquid density constant are determined.

6. The method for constructing a multi-effect comprehensive model of an evaporation process based on personalized phase change characteristics according to claim 4 or 5, characterized in that: The steps for establishing a consistent evaporation model for an evaporator based on the material balance principle include: The evaporation balance equation is constructed based on the feed liquid amount, the inlet feed liquid mass flow rate, the outlet feed liquid mass flow rate, and the steam water amount. The evaporation balance equation is: In the formula, M i is the amount of liquid in the i-effect evaporator, G in,i is the inlet liquid mass flow rate of the i-th effect evaporator, G out,i is the outlet liquid mass flow rate of the i-th effect evaporator, V i is the amount of water evaporated by the i-effect evaporator; An evaporation analytical equation of the feed liquid amount, the inlet feed liquid mass flow rate, and the outlet feed liquid mass flow rate is constructed. The evaporation analytical equation is: M i =ρ i A i h i G in,i =ρ in,i F in,i G out,i =ρ i F out,i In the formula, ρ i is the liquid density of the i-effect evaporator, 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, ρ in,i is the inlet liquid density of the i-th effect evaporator, F in,i is the volume flow rate of the inlet liquid of the i-th effect evaporator, F out,i is the outlet liquid volume flow rate of the i-th effect evaporator; The consistent evaporation model is obtained by combining the evaporation analytical equation and the evaporation equilibrium equation. The consistent evaporation model is: In the formula, t is time; The steps for establishing a consistent flash evaporation model for a flash evaporator based on the material balance principle include: The flash equilibrium equation is constructed based on the feed liquid amount, the inlet feed liquid mass flow rate, the outlet feed liquid mass flow rate, and the steam water amount. The flash equilibrium equation is: In the formula, M j S is the amount of liquid in the j-th stage flash evaporator, is the inlet liquid mass flow rate of the j-th stage flash evaporator, is the outlet liquid mass flow rate of the j-th stage flash evaporator, is the amount of water evaporated by the j-th stage flash evaporator; A flash evaporation analytical equation of the feed liquid amount, the inlet feed liquid mass flow rate, and the outlet feed liquid mass flow rate is constructed. The flash evaporation analytical equation is: In the formula, is the density of the liquid in the j-th stage flash evaporator, is the effective cross-sectional area of ​​the j-th stage flash evaporator, is the liquid level of the j-th stage flash evaporator, is the inlet liquid density of the j-th stage flash evaporator, is the volume flow rate of the inlet liquid of the j-th stage flash evaporator, is the outlet liquid volume flow rate of the j-th stage flash evaporator; The flash evaporation analytical equation and the flash evaporation equilibrium equation are combined to obtain a consistent flash evaporation model, which is:

7. The method for constructing a multi-effect comprehensive model of an evaporation process based on personalized phase change characteristics according to claim 6, characterized in that: The simplified evaporation function is: In the formula, ρ w is the density of water; The multi-effect evaporation model is: In the formula, ρ i is the outlet liquid density of the i-th effect evaporator, Q i is the heat transfer of the i-effect evaporator, a i is the heat transfer coefficient of the i-effect evaporator, b i is the heat transfer constant of the i-effect evaporator, c i is the density coefficient of the evaporating liquid of the i-th effect evaporator, d i Density constant of the evaporating liquid of the i-th effect evaporator; The flash evaporation simplified function is: The multi-stage flash evaporation model is: In the formula, is the outlet liquid density of the j-th stage flash evaporator, is the pressure drop of the j-th stage flash evaporator, is the pressure drop coefficient of the j-th stage flash evaporator, is the pressure drop constant of the j-th stage flash evaporator, is the density coefficient of the flash liquid of the j-th stage flash evaporator, The density constant of the flash liquid in the j-th flash evaporator.

8. A system for constructing a multi-effect comprehensive model of evaporation process based on personalized phase change characteristics, characterized in that: include: one or more processors and memory; The memory is coupled to the one or more processors, and the memory is used to store computer program code, wherein the computer program code includes computer instructions. The one or more processors call the computer instructions to enable the system for constructing a multi-effect comprehensive model of an evaporation process based on personalized phase change characteristics to execute the method according to any one of claims 1 to 7.

9. A computer-readable storage medium comprising instructions, characterized in that: When the instruction is executed on a system for constructing a multi-effect comprehensive model of an evaporation process based on personalized phase change characteristics, the system is enabled to execute the method according to any one of claims 1 to 7.

10. A computer program product, characterized in that When the computer program product is run on a system for constructing a multi-effect comprehensive model of an evaporation process based on personalized phase change characteristics, the system is enabled to execute the method according to any one of claims 1 to 7.

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