A high-efficiency evaporator for low-temperature flue gas waste heat power generation and a parameter optimization method

Abstract

This invention discloses a high-efficiency evaporator for low-temperature flue gas waste heat power generation and a parameter optimization method, relating to the field of evaporator technology. It solves the problems of low heat exchange utilization, large flue gas pressure drop loss, inability to intelligently optimize traditional structural parameters in existing low-temperature flue gas waste heat evaporators, and the problems of easy ash accumulation, rapid heat exchange decay, and poor operational stability under high dust and highly corrosive conditions in aluminum electrolysis flue gas. The key technical solution includes a shell, heat exchange tube bundle, gas-liquid separation device, and monitoring and sensing components. This invention utilizes a horizontal shell-and-tube direct heat exchange structure, eliminating the traditional intermediate heat exchange medium. Combined with finned heat exchange enhancement and baffle turbulence structure, it effectively improves the heat exchange utilization rate of low-temperature flue gas. A multi-objective parameter optimization method is adopted, using equipment quality and flue gas pressure drop as dual objectives for structural parameter optimization. Combined with real-time operating data dynamic model calibration and intelligent soot blowing control strategy, it achieves optimal matching of evaporator structural parameters and long-term stable operation.

Description

Technical Field

[0001] This invention relates to the field of evaporator technology, and in particular to a high-efficiency evaporator for low-temperature flue gas waste heat power generation and a parameter optimization method. Background Technology

[0002] The aluminum electrolysis industrial production process generates a large amount of low-temperature flue gas, with the flue gas temperature generally ranging from 120℃ to 180℃. The flue gas contains acidic corrosive media and fine dust particles, and is characterized by low temperature, large fluctuation, strong corrosiveness, and high dust content.

[0003] Currently, conventional waste heat evaporators in the industry mostly adopt indirect heat exchange structures, which have cumbersome heat exchange processes, high thermal resistance, and extremely low heat utilization in the low-temperature section. At the same time, the fixed structure of traditional evaporators means that the tube bundle structure parameters cannot be adapted to complex fluctuating flue gas conditions. Long-term operation can easily lead to problems such as fin dust accumulation, heat exchange attenuation, and excessive flue gas pressure drop. In addition, existing optimization methods mostly adopt single-objective optimization approaches, only pursuing the improvement of heat exchange efficiency while ignoring the equipment's weight and operating energy consumption. This results in high evaporator manufacturing costs and poor overall economic efficiency. Moreover, conventional optimization algorithms have weak search capabilities and are prone to getting trapped in local optima, failing to obtain the optimal structural parameters that balance lightweight, low flow resistance, and high heat exchange performance. Summary of the Invention

[0004] To address the above shortcomings, this invention provides a high-efficiency evaporator for low-temperature flue gas waste heat power generation and a parameter optimization method. It can be adapted to the high-temperature, high-dust, and corrosive low-temperature flue gas conditions of aluminum electrolysis. It adopts a direct heat exchange structure to reduce heat exchange losses and uses a multi-objective optimization algorithm to intelligently optimize the evaporator structural parameters, thereby reducing the equipment weight and flue gas pressure drop while ensuring heat exchange efficiency.

[0005] To achieve the above objectives, the present invention adopts the following technical solution: On one hand, the present invention provides a high-efficiency evaporator for low-temperature flue gas waste heat power generation, including a shell, a heat exchange tube bundle, a gas-liquid separation device and a monitoring and sensing component; the shell is a horizontal tube shell structure, and end caps are fixedly connected to both ends of the shell; a tube sheet is fixedly disposed on the inner wall of one of the end caps; The heat exchange tube bundle consists of multiple sets of parallel U-shaped heat exchange tubes arranged horizontally inside the shell. The U-shaped heat exchange tube openings are fixedly installed on the tube sheet inside the end cap. The shell is provided with a flue gas inlet pipe and a flue gas outlet pipe. A working fluid feed pipe and a gas-liquid separation device are symmetrically connected to the outside of one of the end caps. The outer wall of the heat exchange tube bundle is provided with heat exchange fins to enhance heat exchange. Preferably, the monitoring and sensing components include a temperature sensor, a pressure sensor, and a flue gas flow sensor. The temperature sensor and pressure sensor are fixedly installed on the outside of the shell with their probes extending into the shell for real-time acquisition of organic working fluid operating parameters. The flue gas flow sensor is installed on the outer surface of the flue gas inlet pipe for real-time acquisition of flue gas flow data.

[0006] Preferably, multiple sets of arc-shaped baffles are evenly arranged along the length of the shell. The heat exchange tube bundle is fixed inside the baffle openings. The baffles are arranged vertically in an alternating pattern, with adjacent baffles having opposite cut directions, forcing the low-temperature flue gas inside the shell to flow in a serpentine manner. A soot blowing device is fixedly installed on one side of another end cap, and a soot blowing interface is reserved on the shell sidewall. A partition is provided on the inner wall of the shell to divide the tube bundle flow area and balance the working fluid flow distribution. This structure enables real-time monitoring of both flue gas parameters and working fluid parameters, providing accurate data support for subsequent algorithm optimization, operating condition calibration, and soot blowing control, thereby improving the intelligent control level of the equipment.

[0007] The gas-liquid separation device includes a primary cyclone separation chamber, a secondary separation chamber, and a wire mesh demister. The primary cyclone separation chamber adopts a cyclone centrifugal separation structure. Due to the physical limitations of cyclone separation, it can only remove large-diameter droplets, and the residual liquid phase ratio is no higher than 10% under normal industrial conditions. The secondary separation chamber is equipped with a wire mesh demister, which uses the micropores of the wire mesh to adsorb and capture tiny droplets, further reducing the liquid phase ratio of the working fluid to ≤0.5%, meeting the dryness requirements of the expander inlet air and preventing liquid hammer damage to the power equipment. The heat exchange tube bundle is made of acid corrosion resistant alloy steel, suitable for the high temperature, high dust, and corrosive flue gas conditions of aluminum electrolysis. This structure can extend the heat exchange residence time of the flue gas and increase the heat exchange contact area. At the same time, the baffle plate balances the working fluid flow rate to avoid uneven local heat exchange. Combined with the soot blowing structure, dust accumulation can be removed in time to prevent the heat exchange efficiency from decreasing. The two-stage gas-liquid separation can strictly guarantee the dryness of the working fluid, protect the downstream generator expander, and the corrosion-resistant material can extend the service life of the equipment and adapt to harsh industrial flue gas conditions.

[0008] On the other hand, the present invention provides a parameter optimization method for a high-efficiency evaporator for low-temperature flue gas waste heat power generation, applied to the above-mentioned high-efficiency evaporator for low-temperature flue gas waste heat power generation, comprising the following steps: S1. Build a physical simulation model of a horizontal evaporator with shell and heat exchange tube bundle, determine the fin spacing, heat exchange tube diameter, and number of tube rows as decision variables, and limit the operating conditions. S2. Based on the fluctuation characteristics of aluminum electrolysis flue gas, set the range of variable values ​​and randomly generate an initial population containing several individuals; S3. With the minimum assembly mass of the shell and the minimum pressure drop on the flue gas side as the dual objectives, construct a fitness function and calculate the individual objective function value; S4. The population hierarchy is divided using a fast non-dominated sorting algorithm, and the density of individuals is determined by combining the crowding distance formula. S5. A binary tournament selection strategy is used to select high-quality parent individuals, and a simulated binary crossover operator and a polynomial mutation operator are used to generate the offspring population. S6. Merge the parent and offspring populations, perform non-dominant sorting and crowding screening again, and retain elite individuals to complete the population iteration. S7. Iterate repeatedly until the termination condition is met, output the Pareto optimal solution set, and determine the final structural parameters of the shell and heat exchange tube bundle.

[0009] Preferably, in step S4, the crowding distance is the sum of the multi-dimensional normalized distances of adjacent individuals within the same non-dominated level, which represents the distribution density of individuals within the population, maintains the uniformity of population distribution, avoids the optimization parameters of the shell and heat exchange tube bundle from getting trapped in local optima, ensures the uniform distribution of individuals in the population, improves the diversity of the solution set, prevents premature convergence of the algorithm, and enhances the comprehensiveness of multi-objective optimization solutions.

[0010] Preferably, in step S5, the crossover operator and mutation operator are set with an adaptive adjustment mechanism. When the population iteration stagnates and the convergence index does not improve, the variable asynchronous length and crossover probability are automatically increased to enhance the global search capability of the internal structural parameters of the shell, enhance the adaptive search capability of the algorithm, break the iteration stagnation deadlock, improve the global optimization capability of the algorithm, and improve the accuracy of optimal parameter solution.

[0011] Preferably, in step S7, the iteration termination condition is set to a dual determination of the maximum number of iterations and the stability of the Pareto solution set, so as to avoid excessive iteration, ensure the optimization efficiency and solution accuracy of the shell and heat exchange tube bundle structural parameters, take into account the algorithm's solution accuracy and computational efficiency, avoid ineffective iteration and waste computing power, and quickly obtain stable and reliable optimal structural parameters.

[0012] Preferably, during the optimization process, the temperature sensor, pressure sensor, and flue gas flow sensor inside the monitoring and sensing components are used to collect real-time operating data on the flue gas temperature inside the shell, the inlet and outlet pressure difference, and the dryness of the working fluid. The measured data are then imported into the simulation model to dynamically correct the boundary conditions of the algorithm. This enables adaptive calibration of the shell model under varying operating conditions, conforms to the fluctuating characteristics of aluminum electrolysis flue gas, achieves dynamic calibration of the model, and improves the adaptability of the optimization parameters under actual complex operating conditions.

[0013] Preferably, the optimization method is based on parameter optimization of the direct heat exchange process: low-temperature flue gas enters the shell side of the shell through the flue gas inlet pipe and flows in a serpentine manner under the action of the bow-shaped baffle. The organic working fluid flows into the heat exchange tube bundle through the working fluid feed pipe outside the head, and after completing heat absorption and vaporization, it is discharged into the gas-liquid separation device. By optimizing and eliminating the intermediate heat exchange medium, the existing low-temperature waste heat power generation system of the same type is limited by indirect heat exchange and high thermal resistance, and the thermoelectric conversion efficiency is only maintained at 4%~6%, while the industry average is 5%. This invention optimizes and eliminates the intermediate heat exchange medium, reduces heat exchange thermal resistance, and, combined with simulation test calculations, can improve the system thermoelectric conversion efficiency to more than 10%, reduce intermediate heat exchange thermal resistance, enhance the low-temperature waste heat absorption capacity, and significantly improve the low-temperature flue gas waste heat power generation efficiency.

[0014] Preferably, the optimization method further includes an intelligent soot blowing control strategy during the operation phase: during the operation of the evaporator, the pressure difference change on the flue gas side is monitored in real time by monitoring sensor components. When the pressure difference exceeds a preset threshold, the soot blowing device is automatically triggered to remove dust deposits on the surface of the heat exchange fins through the soot blowing interface, so as to ensure the long-term heat exchange stability inside the shell, avoid heat exchange attenuation and pipeline blockage caused by dust accumulation, and ensure the long-term stable operation of the equipment.

[0015] Compared with the prior art, the beneficial effects of the present invention are: This invention utilizes a horizontal shell-and-tube direct heat exchange structure, eliminating the traditional intermediate heat exchange medium. Combined with finned enhanced heat exchange and baffled flow structures, it effectively improves the heat exchange utilization rate of low-temperature flue gas. An internal two-stage gas-liquid separation structure ensures the dryness of the working fluid, protecting downstream power generation equipment. Furthermore, this invention incorporates multiple monitoring sensors and an intelligent soot blowing control strategy to achieve real-time monitoring of operating conditions, automatic ash removal, and adaptive calibration under varying operating conditions. Its high level of intelligence ensures long-term stable operation. Employing a multi-objective optimization algorithm, with equipment quality and flue gas pressure drop as optimization targets, and combined with adaptive genetic operators and congestion screening mechanisms, it avoids getting trapped in local optima, accurately solving for optimal structural parameters. This reduces equipment weight and operating resistance while maintaining heat exchange performance, thereby reducing manufacturing costs and energy consumption, and achieving good waste heat recovery. Attached Figure Description

[0016] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below.

[0017] Figure 1 This is a schematic diagram of the overall device in this invention; Figure 2 This is a side view of the overall device in this invention; Figure 3 This is a cross-sectional view of the shell structure in this invention; Figure 4This is a schematic diagram of the internal structure of the shell in this invention; Figure 5 This is a schematic diagram of the heat exchange tube bundle in this invention; Figure 6 This is a cross-sectional view of the gas-liquid separation device in this invention; Figure 7 This is a flowchart of the method in this invention.

[0018] Legend: 1. Shell; 101. Flue gas inlet pipe; 102. Flue gas outlet pipe; 103. Bow-shaped baffle; 104. Soot blowing device; 105. Soot blowing interface; 106. Tube sheet; 2. Heat exchange tube bundle; 201. Heat exchange fins; 202. Baffle; 3. Gas-liquid separation device; 301. Primary cyclone separator; 302. Secondary separator; 303. Wire mesh demister; 304. Working fluid feed connecting pipe; 4. Monitoring and sensing components; 401. Temperature sensor; 402. Pressure sensor; 403. Flue gas flow sensor; 5. End cap. Detailed Implementation

[0019] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0020] In the description of this invention, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0021] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances. Furthermore, the technical features involved in the different embodiments of this invention described below can be combined with each other as long as they do not conflict with each other.

[0022] Example 1 Please see Figures 1-6 The present invention provides a high-efficiency evaporator for low-temperature flue gas waste heat power generation, comprising a shell 1, a heat exchange tube bundle 2, a gas-liquid separation device 3, and a monitoring and sensing component 4; The shell 1 is a horizontal tubular shell structure, and end caps 5 are fixedly connected to both ends of the shell 1; Tube sheet 106 is fixedly installed on the inner wall of one of the end caps 5; The heat exchange tube bundle 2 consists of multiple sets of parallel U-shaped heat exchange tubes arranged horizontally inside the shell 1. The U-shaped heat exchange tube openings are fixedly installed on the tube sheet 106 inside the end cap 5. The casing 1 is provided with a flue gas inlet pipe 101 and a flue gas outlet pipe 102, and a working medium feed pipe 304 and a gas-liquid separator 3 are symmetrically connected to the outside of one of the end caps 5. The outer wall of the heat exchange tube bundle 2 is provided with heat exchange fins 201 to enhance heat exchange; The monitoring sensing component 4 includes a temperature sensor 401, a pressure sensor 402, and a flue gas flow sensor 403. The temperature sensor 401 and the pressure sensor 402 are fixedly installed on the outside of the housing 1 and their probes extend into the inside of the housing 1. They are used to collect the operating parameters of the organic working fluid in real time. The flue gas flow sensor 403 is installed on the outer surface of the flue gas inlet pipe 101 and is used to collect the flow data of the flue gas in real time.

[0023] During operation, the low-temperature and high-temperature corrosive flue gas generated during aluminum electrolysis is introduced into the shell side of the casing 1 through the flue gas inlet pipe 101. After completing heat exchange inside the casing 1, the low-temperature flue gas is discharged out through the flue gas outlet pipe 102. The low-temperature liquid organic working medium is introduced into the heat exchange tube bundle 2 through the working medium feed pipe 304 outside the end cap 5. The organic working medium flows inside the U-shaped heat exchange tube bundle 2 and fully absorbs the waste heat of the flue gas to complete vaporization and heating. The vaporized gas-liquid mixture finally flows into the gas-liquid separation device 3 to complete purification and separation. During operation, the monitoring sensor component 4 continuously collects temperature, pressure and flue gas flow data inside the casing, providing a data basis for back-end algorithm optimization and control.

[0024] Please see Figures 1-6In one embodiment, multiple sets of arc-shaped baffles 103 are uniformly arranged along the length of the shell 1. The heat exchange tube bundle 2 is fixed inside the opening of the baffle 103. The baffles 103 are arranged vertically in an alternating manner, and the cut directions of adjacent baffles 103 are opposite, which forces the low-temperature flue gas inside the shell to flow in a serpentine manner. A soot blowing device 104 is fixedly installed on one side of another end cap 5, and a soot blowing interface 105 is reserved on the side wall of the shell 1. The baffles 103 can extend the residence time of the flue gas inside the shell 1, increase the contact heat exchange area between the flue gas and the heat exchange tube bundle 2, and improve the heat exchange efficiency. On the other hand, they can effectively constrain the position of the tube bundle and reduce the tube bundle vibration and wear caused by high-speed flue gas scouring. Another end cap 5 has a soot blowing device 104 fixedly installed on one side, and a soot blowing interface 105 is reserved on the side wall of the shell 1 to facilitate the staff to regularly connect the soot blowing equipment to remove dust. A partition 202 is set on the inner wall of the shell 1 to divide the tube bundle flow area, balance the working fluid flow distribution, and avoid uneven heat exchange caused by excessive local working fluid flow rate.

[0025] Please see Figures 1-6 In one embodiment, the gas-liquid separation device 3 includes a primary cyclone separation chamber 301, a secondary separation chamber 302, and a wire mesh demister 303. The primary cyclone separation chamber 301 adopts a cyclone centrifugal separation structure, which uses centrifugal force to throw out large liquid droplets inside the mixed working fluid, reducing the liquid phase ratio at the working fluid outlet to ≤10%. The secondary separation chamber 302 is equipped with a wire mesh demister 303, which uses the wire mesh to adsorb and capture tiny mist droplets, further reducing the liquid phase ratio of the working fluid to ≤0.5%, strictly ensuring the dryness of the working fluid entering the expander, and preventing liquid hammer damage to the power equipment. The heat exchange tube bundle 2 is made of acid corrosion resistant alloy steel, which has the characteristics of high temperature resistance, dust wear resistance, and acid and alkali corrosion resistance, and can be adapted to the complex and harsh working conditions of high temperature, high dust, and corrosive flue gas in aluminum electrolysis, thus extending the service life of the equipment.

[0026] Specifically, the soot blowing device 104 in this embodiment can be an acoustic soot blower or a shock wave soot blower. When the monitoring and sensing component 4 detects that the pressure difference on the flue gas side exceeds a preset threshold, such as 500Pa, the control system automatically triggers the soot blowing device 104 to emit acoustic waves or shock waves into the housing 1 through the soot blowing interface 105, so that the dust attached to the surface of the heat exchange fins 201 is loosened and falls off and discharged with the flue gas, thereby ensuring that the evaporator is in a high-efficiency heat exchange state for a long time. In addition, the design of the U-shaped heat exchange tube not only facilitates thermal expansion compensation, but also effectively reduces the risk of leakage at the tube sheet.

[0027] In summary, the evaporator adopts a shell-and-tube direct heat exchange structure, with flue gas flowing through the shell side and organic working fluid flowing through the tube side. This eliminates the intermediate heat exchange medium in traditional heat exchange systems, reducing heat exchange losses. At the same time, it is equipped with an external monitoring sensor component 4 to monitor operating parameters in real time, and with the back-end optimization algorithm, it achieves adaptive control under changing operating conditions.

[0028] Example 2 Please see Figure 7 This invention provides a parameter optimization method for a high-efficiency evaporator for low-temperature flue gas waste heat power generation, applied to the aforementioned high-efficiency evaporator for low-temperature flue gas waste heat power generation, comprising the following steps: S1. Build a physical simulation model of the horizontal evaporator consisting of shell 1 and heat exchange tube bundle 2. Determine the fin spacing 201, heat exchange tube diameter, and number of tube rows as decision variables. Set the operating conditions as follows: flue gas temperature 120~180℃, flue gas velocity 1.5~3m / s, and working pressure 0.2~0.5MPa.

[0029] S2. Based on the fluctuation characteristics of aluminum electrolysis flue gas, set the range of variable values ​​and randomly generate an initial population containing several individuals to provide initial samples for iterative optimization.

[0030] S3. With the minimum assembly mass of shell 1 and the minimum pressure drop on the flue gas side as the dual objectives, a fitness function is constructed and the individual objective function values ​​are calculated to establish an optimization mathematical model. Subsequently, the objective values ​​are solved through refined mathematical formulas.

[0031] S4. The population hierarchy is divided using a fast non-dominated sorting algorithm. The density of individuals is determined by the crowding distance formula, and superior and inferior individuals are distinguished to complete the population hierarchy screening.

[0032] S5. A binary tournament selection strategy is used to select high-quality parent individuals, retain excellent genes, and generate a new offspring population by combining simulated binary crossover operator and polynomial mutation operator.

[0033] S6. Merge the parent and offspring populations, perform non-dominant sorting and crowding screening again, remove inferior individuals, and retain elite individuals to complete the population iteration update.

[0034] S7. Iterate repeatedly until the termination condition is met, output the Pareto optimal solution set, and determine the final structural parameters of shell 1 and heat exchange tube bundle 2 by comprehensively considering heat exchange performance and manufacturing cost.

[0035] Furthermore, the crowding distance is the sum of the multi-dimensional normalized distances of adjacent individuals within the same non-dominated level, which characterizes the distribution density of individuals within the population, maintains the uniformity of population distribution, and avoids the optimization parameters of shell 1 and heat exchange tube bundle 2 from getting trapped in local optimum clustering. The standardized crowding distance calculation formula is used for individual screening to ensure the uniformity of population distribution.

[0036] Furthermore, the crossover and mutation operators are equipped with an adaptive adjustment mechanism. When the population iteration stagnates and the convergence index does not improve, the variable asynchronous length and crossover probability are automatically increased to enhance the global search capability of the internal structural parameters of shell 1.

[0037] Furthermore, the iteration termination condition is set as a dual criterion of the maximum number of iterations and the stability of the Pareto solution set to avoid excessive iteration and ensure the optimization efficiency and solution accuracy of the structural parameters of shell 1 and heat exchange tube bundle 2.

[0038] Furthermore, during the optimization process, the temperature sensor 401, pressure sensor 402, and flue gas flow sensor 403 inside the monitoring and sensing component 4 are used to collect real-time operating data of flue gas temperature, inlet and outlet pressure difference, and working fluid dryness inside the shell 1. The measured data are then imported into the simulation model to dynamically correct the algorithm boundary conditions and achieve adaptive calibration of the shell 1 model under varying operating conditions.

[0039] Furthermore, the optimization method is based on parameter optimization of the direct heat exchange process: low temperature flue gas enters the shell side of the shell 1 through the flue gas inlet pipe 101 and flows in a serpentine manner under the action of the bow-shaped baffle 103. The organic working medium flows into the heat exchange tube bundle 2 through the working medium feed pipe 304 outside the end cap 5. After completing heat absorption and vaporization, it is discharged into the gas-liquid separation device 3. By optimizing and eliminating the intermediate heat exchange medium, the system thermoelectric conversion efficiency is increased to more than 10%.

[0040] Furthermore, the optimization method also includes an intelligent soot blowing control strategy during the operation phase: during the operation of the evaporator, the pressure difference change on the flue gas side is monitored in real time by the monitoring sensor component 4. When the pressure difference exceeds the preset threshold, the soot blowing device 104 is automatically triggered to remove the dust adhering to the surface of the heat exchange fins 201 through the soot blowing interface 105, so as to ensure the long-term heat exchange stability inside the shell 1.

[0041] In step S3, the fitness function is constructed, specifically including establishing a thermodynamic calculation model and a pressure drop calculation model for the heat exchanger, and using the total mass of the heat exchanger as the basis for calculation. and flue gas side pressure drop These are two minimization optimization objectives.

[0042] Objective function 1: Total mass of the heat exchanger, calculated using the following formula: In the formula, The decision variable vector includes fin spacing, pipe diameter, and number of pipe rows. , These are the number of heat exchange tubes and the number of fins, respectively. The density of the material; The volume of a single tube or a single fin. For the mass of the shell (1), Objective function two: Flue gas side pressure drop, calculated using the following formula: In the formula, The friction drag coefficient is related to the Reynolds number. It is related to the fin structure parameters. Number of pipe rows; The density of the flue gas; This represents the maximum flow velocity of the flue gas at the minimum flow cross section.

[0043] The optimization process must meet the following constraints: Heat transfer constraints: This ensures that the actual heat exchange meets the system's required heat load. Structural constraints: The manufacturing limits for pipe diameter and fin spacing are defined. Flow velocity constraints: This prevents ash accumulation due to excessively low flue gas velocity or erosion and wear of the tube bundle due to excessively high flow velocity.

[0044] In step S4, the congestion distance The calculation formula is: In the formula, Let be the crowding distance of the i-th individual. The number of objective functions is set to 2. , The objective function value of adjacent individuals is used to determine the density of the population.

[0045] In step S5, the calculation formula for generating offspring individuals using the simulated binary crossover operator is as follows: In the formula , For the parent generation, , For offspring individuals, It is a random distribution coefficient used to regulate the amplitude of population variation.

[0046] Through the specific mathematical models and algorithm operators described above, this embodiment can accurately search for the Pareto optimal combination of structural parameters that minimizes the weight of the evaporator and reduces its operating energy consumption, while meeting the heat exchange requirements.

[0047] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A high-efficiency evaporator for low-temperature flue gas waste heat power generation, characterized in that, It includes a shell (1), a heat exchange tube bundle (2), a gas-liquid separation device (3), and a monitoring and sensing component (4); The shell (1) is a horizontal tubular shell structure, and end caps (5) are fixedly connected to both ends of the shell (1). Tube sheet (106) is fixedly installed on the inner wall of one of the end caps (5); The heat exchange tube bundle (2) consists of multiple sets of parallel U-shaped heat exchange tubes arranged horizontally inside the shell (1), and the U-shaped heat exchange tube openings are fixedly installed on the tube sheet (106) inside the end cap (5); The shell (1) is provided with a flue gas inlet pipe (101) and a flue gas outlet pipe (102), and a working medium feed pipe (304) and a gas-liquid separation device (3) are symmetrically connected to the outside of one of the end caps (5). The outer wall of the heat exchange tube bundle (2) is provided with heat exchange fins (201) to enhance heat exchange. The monitoring and sensing component (4) includes a temperature sensor (401), a pressure sensor (402), and a flue gas flow sensor (403). The temperature sensor (401) and the pressure sensor (402) are fixedly installed on the outside of the housing (1) and the probes extend into the inside of the housing (1) to collect the operating parameters of the organic working fluid in real time. The flue gas flow sensor (403) is installed on the outer surface of the flue gas inlet pipe (101) to collect the flow data of the flue gas in real time.

2. The high-efficiency evaporator for low-temperature flue gas waste heat power generation according to claim 1, characterized in that, Multiple sets of bow-shaped baffles (103) are evenly arranged along the length of the shell (1). The heat exchange tube bundle (2) is fixed inside the opening of the baffle (103). The baffles (103) are arranged vertically in an alternating manner. The cut directions of adjacent baffles (103) are opposite, which forces the low-temperature flue gas inside the shell to flow in a serpentine manner. A soot blowing device (104) is fixedly installed on one side of another end cap (5), and a soot blowing interface (105) is reserved on the side wall of the shell (1). A partition (202) is provided on the inner wall of the shell (1) to divide the tube bundle flow area and balance the working fluid flow distribution.

3. The high-efficiency evaporator for low-temperature flue gas waste heat power generation according to claim 1, characterized in that, The gas-liquid separation device (3) includes a primary cyclone separation chamber (301), a secondary separation chamber (302), and a wire mesh demister (303). The primary cyclone separation chamber (301) adopts a cyclone centrifugal separation structure. The secondary separation chamber (302) is equipped with a wire mesh demister (303). The heat exchange tube bundle (2) is made of acid corrosion resistant alloy steel, which is suitable for high temperature, high dust and corrosive flue gas conditions in aluminum electrolysis.

4. A parameter optimization method for a high-efficiency evaporator for low-temperature flue gas waste heat power generation, as described in any one of claims 1-3, characterized in that, Includes the following steps: S1. Build a physical simulation model of the horizontal evaporator with shell (1) and heat exchange tube bundle (2), determine the fin spacing (201), heat exchange tube diameter and tube row number as decision variables, and limit the operating conditions. S2. Based on the fluctuation characteristics of aluminum electrolysis flue gas, set the range of variable values ​​and randomly generate an initial population containing several individuals; S3. With the minimum assembly mass of the shell (1) and the minimum pressure drop on the flue gas side as the dual objectives, construct the fitness function and calculate the individual objective function value; S4. The population hierarchy is divided using a fast non-dominated sorting algorithm, and the density of individuals is determined by combining the crowding distance formula. S5. A binary tournament selection strategy is used to select high-quality parent individuals, and a simulated binary crossover operator and a polynomial mutation operator are used to generate the offspring population. S6. Merge the parent and offspring populations, perform non-dominant sorting and crowding screening again, and retain elite individuals to complete the population iteration. S7. Iterate repeatedly until the termination condition is reached, output the Pareto optimal solution set, and determine the final structural parameters of the shell (1) and the heat exchange tube bundle (2).

5. The parameter optimization method for a high-efficiency evaporator for low-temperature flue gas waste heat power generation according to claim 4, characterized in that, In step S4, the crowding distance is the sum of the multidimensional normalized distances of adjacent individuals within the same non-dominated level, which characterizes the distribution density of individuals within the population, maintains the uniformity of population distribution, and avoids the optimization parameters of the shell (1) and heat exchange tube bundle (2) from falling into local optimum aggregation.

6. The parameter optimization method for a high-efficiency evaporator for low-temperature flue gas waste heat power generation according to claim 4, characterized in that, In step S5, the crossover operator and mutation operator are set with an adaptive adjustment mechanism. When the population iteration stagnates and the convergence index does not improve, the variable asynchronous length and crossover probability are automatically increased to enhance the global search capability of the internal structural parameters of the shell (1).

7. The parameter optimization method for a high-efficiency evaporator for low-temperature flue gas waste heat power generation according to claim 4, characterized in that, In step S7, the iteration termination condition is set to a dual determination of the maximum number of iterations and the stability of the Pareto solution set, to avoid excessive iteration and ensure the optimization efficiency and solution accuracy of the structural parameters of the shell (1) and heat exchange tube bundle (2).

8. The parameter optimization method for a high-efficiency evaporator for low-temperature flue gas waste heat power generation according to claim 4, characterized in that, During the optimization process, the temperature sensor (401), pressure sensor (402), and flue gas flow sensor (403) inside the monitoring and sensing component (4) are used to collect real-time operating data of flue gas temperature, inlet and outlet pressure difference, and working fluid dryness inside the shell (1). The measured data are then imported into the simulation model to dynamically correct the algorithm boundary conditions and achieve adaptive calibration of the shell (1) model under varying operating conditions.

9. The parameter optimization method for a high-efficiency evaporator for low-temperature flue gas waste heat power generation according to claim 4, characterized in that, The optimization method is based on the direct heat exchange process for parameter optimization: low temperature flue gas enters the shell side of the shell (1) through the flue gas inlet pipe (101) and flows in a serpentine manner under the action of the bow-shaped baffle (103). The organic working medium flows into the heat exchange tube bundle (2) through the working medium feed pipe (304) outside the end cap (5) and is discharged into the gas-liquid separation device (3) after completing heat absorption and vaporization.

10. The parameter optimization method for a high-efficiency evaporator for low-temperature flue gas waste heat power generation according to claim 4, characterized in that, The optimization method also includes an intelligent soot blowing control strategy during the operation phase: during the operation of the evaporator, the pressure difference change on the flue gas side is monitored in real time by the monitoring sensor component (4). When the pressure difference exceeds the preset threshold, the soot blowing device (104) is automatically triggered to remove the dust adhering to the surface of the heat exchange fins (201) through the soot blowing interface (105) to ensure the long-term heat exchange stability inside the shell (1).

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