Industrial heat pump coupled flue gas waste heat cascade recovery method and system

Abstract

The invention discloses an industrial heat pump coupled flue gas waste heat cascade recovery method and system, and particularly relates to the technical field of flue gas waste heat recovery. Through flue gas pretreatment, vapor-liquid separation, heat pump temperature raising, vapor compression, heat energy integration, liquid phase waste heat secondary recovery and intelligent PID cooperative control, different grades of heat energy of industrial flue gas are fully utilized, and multi-stage efficient gradient utilization of flue gas waste heat is achieved. The steam heat energy quality is improved through industrial heat pump circulation, the steam pressure energy level is improved in combination with a centrifugal compressor, liquid-phase low-grade heat is effectively utilized through a low-temperature-level waste heat recovery heat exchanger, the recovery process is accurately adjusted through a multivariable fuzzy PID algorithm, and the overall efficiency and stability of flue gas waste heat utilization are improved.

Description

Technical Field

[0001] This invention relates to the field of flue gas waste heat recovery technology, and more specifically, to a method and system for cascaded recovery of flue gas waste heat coupled with an industrial heat pump. Background Technology

[0002] Currently, industrial flue gas waste heat recovery generally suffers from problems such as single-level heat energy utilization, low recovery rate of low-temperature waste heat, and lag in control response. Under complex operating conditions, high- and low-grade waste heat cannot be utilized in a coordinated manner, resulting in a large amount of wasted recoverable energy and low overall energy efficiency. At the same time, traditional waste heat recovery devices mostly adopt a single heat exchange path and static control strategy, which makes it difficult to dynamically match heat source fluctuations and load demands, and cannot achieve multi-level heat energy extraction and dynamic optimization control. Summary of the Invention

[0003] In order to overcome the above-mentioned defects of the prior art, the embodiments of the present invention provide a method and system for cascade recovery of flue gas waste heat coupled with an industrial heat pump to solve the problems mentioned in the background art.

[0004] To achieve the above objectives, the present invention provides the following technical solution:

[0005] A method for cascade recovery of waste heat from flue gas coupled with an industrial heat pump includes the following steps:

[0006] S1: Collect temperature, flow rate and composition information of waste heat flue gas, perform preprocessing, and output preprocessed flue gas characteristic data;

[0007] S2: Based on flue gas characteristic data, a flash evaporator steam-liquid separation method is used to obtain flash steam parameters and separated liquid phase parameters respectively;

[0008] S3: For flash steam parameters, an industrial heat pump cycle is used for primary temperature increase to generate primary preheated steam parameters;

[0009] S4: For flash steam parameters, a centrifugal compressor is used for intermediate compression to output intermediate pressure steam parameters;

[0010] S5: The primary preheated steam parameters and intermediate pressure steam parameters are integrated in the coupled heat exchanger and intermediate reheater to generate high-grade steam parameters.

[0011] S6: The separated liquid phase parameters are subjected to secondary cascade heat recovery using a low-temperature waste heat recovery heat exchanger to generate secondary low-temperature heat recovery parameters;

[0012] S7: The high-grade steam parameters and the secondary low-temperature heat recovery parameters are monitored and adjusted using a multivariable fuzzy PID algorithm, and real-time adjustment and control commands are output.

[0013] In a preferred embodiment, S1 specifically refers to:

[0014] At the outlet of the industrial flue gas heat exchanger, collect temperature, flow rate and composition information of the waste heat flue gas.

[0015] Noise filtering is performed on temperature, flow rate, and flue gas composition information;

[0016] Deviation correction is performed on temperature information, flow rate information, and flue gas composition information;

[0017] The temperature, flow, and flue gas composition information after deviation correction are formatted into a predefined standard data format;

[0018] The formatted temperature, flow rate, and flue gas composition information are used as preprocessed flue gas characteristic data.

[0019] In a preferred embodiment, S2 specifically refers to:

[0020] Based on the temperature, flow and composition information in the flue gas characteristic data, the set working pressure value of the flash evaporator is calculated.

[0021] Calculate the saturated evaporation temperature of the flash evaporator based on the working pressure and temperature information;

[0022] Based on the saturated evaporation temperature value and temperature information, the flash evaporator is controlled to perform steam-water separation on the waste heat flue gas.

[0023] The flash steam state parameters are obtained at the flash evaporator outlet and used as flash steam parameters.

[0024] The state parameters of the separated liquid phase are obtained at the bottom drain port of the flash evaporator and used as the parameters of the separated liquid phase.

[0025] In a preferred embodiment, S3 specifically refers to:

[0026] The latent heat of vaporization in flash steam parameters is extracted using an absorber from an industrial heat pump cycle.

[0027] The compressor of the industrial heat pump cycle converts the low-grade heat energy output from the absorber into high-grade heat energy.

[0028] High-grade heat energy is input into flash steam using a condenser that utilizes an industrial heat pump cycle.

[0029] A temperature sensor is installed at the condenser outlet of the industrial heat pump cycle to obtain the steam temperature value after the temperature is raised.

[0030] A pressure gauge is installed at the condenser outlet of the industrial heat pump cycle to obtain the steam pressure value after the temperature is raised;

[0031] The temperature and pressure of the heated steam are combined to form the primary preheating steam parameters.

[0032] In a preferred embodiment, S4 specifically refers to:

[0033] Calculate the compression ratio control coefficient based on the steam flow rate and initial pressure values ​​in the flash steam parameters;

[0034] The centrifugal compressor is driven by a compression ratio control coefficient to compress flash steam;

[0035] The temperature of the compressed steam is obtained at the outlet of the centrifugal compressor and is used as the temperature of the compressed steam.

[0036] The compressed steam pressure is obtained at the outlet of the centrifugal compressor and is used as the compressed steam pressure.

[0037] The temperature and pressure of the compressed steam are combined to form the intermediate pressure steam parameters.

[0038] In a preferred embodiment, S5 specifically refers to:

[0039] Steam corresponding to the first-stage preheating steam parameters is introduced into the first input terminal of the coupled heat exchanger.

[0040] Steam corresponding to the intermediate pressure steam parameters is introduced into the second input terminal of the intermediate reheater.

[0041] Reheated steam is generated by heating the steam corresponding to the intermediate pressure steam parameters through an intermediate reheater.

[0042] Reheated steam is introduced into the second input end of the coupled heat exchanger to exchange heat with steam corresponding to the parameters of the first-stage preheated steam.

[0043] The steam temperature and steam pressure values ​​after heat exchange are obtained at the outlet of the coupled heat exchanger.

[0044] The temperature and pressure values ​​of the steam after heat exchange are combined to form the parameters of high-grade steam.

[0045] In a preferred embodiment, S6 specifically refers to:

[0046] Based on the liquid phase temperature and liquid phase flow rate in the separated liquid phase parameters, the low-temperature waste heat recovery heat exchanger is controlled to transfer heat energy to the separated liquid phase.

[0047] The temperature of the medium after heat recovery is obtained at the secondary side outlet of the low-temperature waste heat recovery heat exchanger.

[0048] The pressure value of the medium after heat recovery is obtained at the secondary side outlet of the low-temperature waste heat recovery heat exchanger.

[0049] The combined temperature and pressure values ​​of the medium after heat recovery are used to form the secondary low-temperature heat energy recovery parameters.

[0050] In a preferred embodiment, S7 specifically refers to:

[0051] Based on the parameters of high-grade steam and secondary low-temperature heat recovery, the steam temperature deviation, steam pressure deviation, medium temperature deviation, and medium pressure deviation are calculated.

[0052] Input the steam temperature deviation, steam pressure deviation, medium temperature deviation, and medium pressure deviation into the multivariable fuzzy PID controller;

[0053] The three-channel regulation is executed synchronously by a multivariable fuzzy PID controller, and the real-time regulation control command is output.

[0054] On the other hand, the present invention provides an industrial heat pump coupled flue gas waste heat cascade recovery system, comprising:

[0055] Flue gas treatment module: Collects temperature, flow rate and composition information of waste heat flue gas, performs preprocessing, and outputs preprocessed flue gas characteristic data;

[0056] Vapor-liquid separation module: Based on flue gas characteristic data, a flash evaporator vapor-liquid separation method is used to obtain flash steam parameters and separated liquid phase parameters respectively;

[0057] Heat pump temperature boosting module: The flash steam parameters are boosted by an industrial heat pump cycle to generate primary preheated steam parameters;

[0058] Steam compression module: The flash steam parameters are compressed intermediately using a centrifugal compressor to output intermediate pressure steam parameters;

[0059] Thermal energy integration module: The primary preheated steam parameters and intermediate pressure steam parameters are integrated in a coupled heat exchanger and intermediate reheater to generate high-grade steam parameters;

[0060] Liquid phase recovery module: The separated liquid phase parameters are recovered in a secondary cascade heat recovery stage using a low-temperature waste heat recovery heat exchanger to generate secondary low-temperature heat recovery parameters;

[0061] Intelligent control module: It uses a multivariable fuzzy PID algorithm to monitor and regulate the parameters of high-grade steam and secondary low-temperature heat recovery, and outputs real-time control commands.

[0062] The technical effects and advantages of the present invention regarding a method and system for cascade recovery of waste heat from flue gas coupled with an industrial heat pump are as follows:

[0063] Preprocessing of flue gas temperature, flow rate, and composition information ensures data accuracy and stability; efficient steam-liquid separation is achieved using a flash evaporator to obtain steam and liquid phase parameters; an industrial heat pump cycle is introduced to increase the flash steam temperature, improving the quality of heat energy utilization; a centrifugal compressor is used to increase steam pressure to meet high-pressure steam requirements; energy integration of the two-stage steam in a coupled heat exchanger and intermediate reheater enhances heat utilization efficiency; low-temperature waste heat recovery is performed on the flash liquid phase to fully exploit the value of low-grade heat sources; a multivariable fuzzy PID control strategy is adopted to dynamically monitor and finely adjust high-grade steam and low-temperature recovery parameters, achieving rapid response and automatic optimization. Attached Figure Description

[0064] Figure 1 This is a schematic diagram of a flue gas waste heat recovery method coupled with an industrial heat pump according to the present invention.

[0065] Figure 2 This is a schematic diagram of the structure of an industrial heat pump coupled flue gas waste heat cascade recovery system according to the present invention. Detailed Implementation

[0066] 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. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0067] Example 1

[0068] Figure 1 This invention discloses a method for cascade recovery of waste heat from flue gas coupled with an industrial heat pump, comprising the following steps:

[0069] S1: Collect temperature, flow rate and composition information of waste heat flue gas, perform preprocessing, and output preprocessed flue gas characteristic data;

[0070] S2: Based on flue gas characteristic data, a flash evaporator steam-liquid separation method is used to obtain flash steam parameters and separated liquid phase parameters respectively;

[0071] S3: For flash steam parameters, an industrial heat pump cycle is used for primary temperature increase to generate primary preheated steam parameters;

[0072] S4: For flash steam parameters, a centrifugal compressor is used for intermediate compression to output intermediate pressure steam parameters;

[0073] S5: The primary preheated steam parameters and intermediate pressure steam parameters are integrated in the coupled heat exchanger and intermediate reheater to generate high-grade steam parameters.

[0074] S6: The separated liquid phase parameters are subjected to secondary cascade heat recovery using a low-temperature waste heat recovery heat exchanger to generate secondary low-temperature heat recovery parameters;

[0075] S7: The high-grade steam parameters and the secondary low-temperature heat recovery parameters are monitored and adjusted using a multivariable fuzzy PID algorithm, and real-time adjustment and control commands are output.

[0076] S1: Collect temperature, flow rate, and composition information of the waste heat flue gas, perform preprocessing, and output preprocessed flue gas characteristic data, including:

[0077] At the outlet of the industrial flue gas heat exchanger, collect temperature, flow rate and composition information of the waste heat flue gas.

[0078] Noise filtering is performed on temperature, flow rate, and flue gas composition information;

[0079] Deviation correction is performed on temperature information, flow rate information, and flue gas composition information;

[0080] The temperature, flow, and flue gas composition information after deviation correction are formatted into a predefined standard data format;

[0081] The formatted temperature, flow rate, and flue gas composition information are used as preprocessed flue gas characteristic data.

[0082] Specifically, multiple high-precision temperature sensors, flow measurement devices, and online flue gas composition analyzers are installed at the outlet of the industrial flue gas heat exchanger to collect temperature, flow rate, and composition information of the waste heat flue gas. The temperature sensors are preferably platinum resistance temperature sensors, such as the Pt1000 model, which are installed on the inner wall of the flue gas duct or inserted into the center of the flue gas flow field to collect flue gas temperature information. The flow measurement device uses a thermal mass flow meter with low pressure loss characteristics, such as the MFC500 model, to ensure accurate flue gas flow information without affecting the flue gas flow characteristics. The online flue gas composition analyzer uses a non-dispersive infrared analyzer, such as the NDIR-500 model, to analyze and record the components and corresponding concentrations of carbon dioxide, carbon monoxide, oxygen, etc., in the flue gas in real time, obtaining real-time flue gas composition information.

[0083] Noise filtering is performed on temperature, flow rate, and flue gas composition information to eliminate potential high-frequency interference or measurement noise. For example, for temperature information, a median filtering algorithm is used with a processing cycle of 5 seconds to remove occasional fluctuations. If a significant anomaly in temperature deviates from the overall data range within a certain time window, the median filtering algorithm discards it and replaces it with adjacent normal data, making the temperature data more stable and reliable. For flow rate information, a low-pass filtering method is used, such as a first-order Butterworth filter with a cutoff frequency of 0.2Hz, to eliminate transient high-frequency noise during measurement. Through processing, the flow rate information exhibits a smooth and continuous trend over a longer time scale, avoiding misleading the waste heat recovery control process. For flue gas composition information, especially the signal generated by the online flue gas composition analyzer, Kalman filtering can be used. Through continuous iterative estimation, measurement errors and environmental interference factors are eliminated, resulting in accurate flue gas composition information. For example, when the carbon dioxide concentration monitoring value shows a brief abnormal fluctuation, Kalman filtering can predict and correct the abnormal data in a timely manner, making the flue gas composition information more realistic and accurate.

[0084] After noise filtering, the temperature, flow rate, and flue gas composition information are corrected for deviations to eliminate errors and measurement drift. Taking temperature as an example, temperature sensors may experience measurement drift during long-term operation, which is corrected through periodic instrument calibration. For instance, every 200 hours of operation, a standard temperature source (e.g., a standard heat source generator, model STS-1000) is used to calibrate the temperature sensor's measurement information. The measured temperature is compared with the output value of the standard temperature source to calculate the temperature measurement deviation, and a temperature correction function is established to mathematically compensate for the temperature information. For flow rate deviation correction, the flow measurement device can be calibrated periodically. For example, using a high-precision sonic nozzle method, calibration can be performed every 300 hours of operation. The flow rate deviation is calculated based on the actual calibration value, and a flow rate correction curve is constructed to correct the real-time flow measurement data, eliminating measurement errors accumulated over long-term operation. For flue gas composition information, the online flue gas composition analyzer can be calibrated using a standard gas calibration method. For example, the instrument can be calibrated monthly using a standard gas of known concentration. The measured data can be compared with the standard gas concentration value to obtain the deviation of the flue gas composition information. A flue gas composition information deviation correction model can then be constructed to correct the real-time measurement results. After calibration, the deviation errors of temperature information, flow rate information, and flue gas composition information are controlled within the allowable range.

[0085] After deviation correction, the corrected temperature, flow rate, and flue gas composition information are uniformly formatted and converted into a predefined standard data format. This predefined standard data format uses a standard data structure from a database, represented as a structured array. Temperature information is formatted and saved as a "temperature value - acquisition timestamp" structure, for example, "150℃ - January 10, 2025, 08:30:00". Flow rate information is formatted and saved as a "flow rate value - acquisition timestamp" structure, for example, "2500 Nm³ / h - January 10, 2025, 08:30:00". Flue gas composition information is formatted and saved as a "component name - concentration - acquisition timestamp" structure, for example, "carbon dioxide - 15% - January 10, 2025, 08:30:00". The formatted temperature, flow rate, and flue gas composition information are uniformly encoded into the flue gas characteristic data storage unit.

[0086] S2: Based on flue gas characteristic data, a flash evaporator steam-liquid separation method is used to obtain flash steam parameters and separated liquid phase parameters, including:

[0087] Based on the temperature, flow and composition information in the flue gas characteristic data, the set working pressure value of the flash evaporator is calculated.

[0088] Calculate the saturated evaporation temperature of the flash evaporator based on the working pressure and temperature information;

[0089] Based on the saturated evaporation temperature value and temperature information, the flash evaporator is controlled to perform steam-water separation on the waste heat flue gas.

[0090] The flash steam state parameters are obtained at the flash evaporator outlet and used as flash steam parameters.

[0091] The state parameters of the separated liquid phase are obtained at the bottom drain port of the flash evaporator and used as the parameters of the separated liquid phase.

[0092] Specifically, based on the temperature, flow rate, and composition information contained in the pre-processed flue gas characteristic data, a thermodynamic calculation method is used to determine the set operating pressure value required for the flash evaporator under the current flue gas conditions. The process of calculating the working pressure value using temperature, flow rate, and flue gas composition information is as follows: Based on the pre-processed temperature information, for example, when the temperature value in the flue gas characteristic data is 180 degrees Celsius, the initial value of the saturated pressure of water vapor at this temperature is determined by referring to the thermodynamic properties table of water vapor or the IAPWS-IF97 industrial standard steam table; then, the flow rate information is used for correction. For example, when the flue gas flow rate is 3000 Nm³ / h, the initial value of the saturated pressure is adjusted using the mass conservation and energy conservation equations to obtain a working pressure value suitable for the current flue gas flow rate; the working pressure value is further corrected by referring to the proportions of non-water vapor components such as carbon dioxide, carbon monoxide, and oxygen in the flue gas composition information; for example, when the content of a specific component in the flue gas, such as carbon dioxide, is high, reaching more than 20%, since the gas-liquid phase equilibrium characteristics of carbon dioxide are different from those of water vapor, a non-ideal gas state equation, such as the Peng-Robinson equation, needs to be used, combined with the actual component proportions, to recalculate the working pressure value of the flash evaporator, thereby ensuring that the working pressure value is suitable for the actual flue gas characteristic data. The calculation and determination of the above working pressure values ​​directly affect the energy recovery effect of the flash evaporator on flue gas, ensure the operational stability and efficiency of flash steam-water separation, and meet the overall performance requirements of flue gas waste heat recovery.

[0093] Based on the operating pressure and temperature information, the corresponding saturated evaporation temperature during flash evaporator operation is calculated. For example, when the operating pressure of the flash evaporator is determined to be 0.3 MPa, the corresponding saturated evaporation temperature is found to be 133.52 degrees Celsius based on known thermodynamic data (such as the IAPWS-IF97 standard steam table). The actual temperature of the flue gas (such as 180 degrees Celsius after pretreatment) is compared with the saturated evaporation temperature to analyze the temperature difference. The temperature difference reflects the thermal potential of the flue gas heat energy available for steam-water separation. The saturated evaporation temperature is the core basis for the flash evaporator to achieve steam-water separation operation, providing a stable and reliable control target temperature parameter, which facilitates the effective management of the flash evaporator's automated control system on the actual operating status. If the flue gas temperature fluctuates during actual operation, for example, from 180 degrees Celsius to 170 degrees Celsius, the saturated evaporation temperature needs to be recalculated and updated to maintain the optimal steam-water separation conditions in real time, thereby ensuring that the steam-water separation effect of the flash evaporator remains stable at its best.

[0094] Based on the saturated evaporation temperature and the actual flue gas temperature, the flash evaporator is automatically controlled in real time to ensure a stable steam-water separation process within the flash evaporator. Specifically, the control system employs a PID closed-loop control method to automatically adjust the opening of the flash evaporator's inlet valve, ensuring that the steam generation process remains stable near the calculated saturated evaporation temperature. For example, when the actual detected flue gas temperature is 20 degrees Celsius higher than the target saturated evaporation temperature, the control system automatically increases the valve opening, allowing more flue gas to enter the flash evaporator and release heat, thereby increasing the intensity of steam-water separation. Conversely, when the actual flue gas temperature is lower than the target saturated evaporation temperature, the valve opening is automatically decreased to reduce the amount of flue gas entering, preventing a decrease in separation efficiency or even droplet entrainment. The control operation ensures that the flash evaporator is in a stable and effective steam-water separation condition in real time, thereby achieving a stable output of high-quality flash steam and separated liquid phase.

[0095] After stabilizing and controlling the steam-water separation process, a steam state monitoring instrument, such as a pressure sensor (e.g., model EJA530A pressure sensor) and a temperature sensor (e.g., Pt1000 platinum resistance temperature sensor), is installed at the top outlet of the flash evaporator to monitor and acquire the state parameters of the flash steam, such as temperature, pressure, and dryness, in real time. For example, the steam temperature at the outlet may be 135 degrees Celsius, the pressure may be 0.28 MPa, and the dryness may reach 95%. The parameters collected in real time are combined to form complete flash steam parameters.

[0096] A liquid phase state detection device is installed at the drain port at the bottom of the flash evaporator. For example, a liquid phase temperature sensor (such as a Pt1000 platinum resistance sensor) and a flow measurement device (such as an MFC500 mass flow meter) are set up to measure and acquire the temperature and flow state parameters of the liquid phase discharged from the bottom in real time. For example, the liquid phase temperature detected at the drain port at the bottom of the flash evaporator may be 120 degrees Celsius, and the liquid phase flow rate may be 2000 kg per hour. The measured values ​​are combined to form the separated liquid phase parameters. The separated liquid phase parameters play an important role in the heat recovery of the low-temperature stage waste heat recovery heat exchanger. They provide accurate input parameters, which enable the low-temperature stage waste heat recovery heat exchanger to be optimized and adjusted according to the liquid phase state, ultimately improving the heat recovery efficiency of the entire flue gas waste heat recovery system.

[0097] S3: For flash steam parameters, an industrial heat pump cycle is used for primary temperature boosting to generate primary preheated steam parameters, including:

[0098] The latent heat of vaporization in flash steam parameters is extracted using an absorber from an industrial heat pump cycle.

[0099] The compressor of the industrial heat pump cycle converts the low-grade heat energy output from the absorber into high-grade heat energy.

[0100] High-grade heat energy is input into flash steam using a condenser that utilizes an industrial heat pump cycle.

[0101] A temperature sensor is installed at the condenser outlet of the industrial heat pump cycle to obtain the steam temperature value after the temperature is raised.

[0102] A pressure gauge is installed at the condenser outlet of the industrial heat pump cycle to obtain the steam pressure value after the temperature is raised;

[0103] The temperature and pressure of the heated steam are combined to form the primary preheating steam parameters.

[0104] Specifically, the parameters of flash steam are determined by steam temperature, pressure, and dryness fraction. For example, the flash steam parameters might be a steam temperature of 135 degrees Celsius, a pressure of 0.28 MPa, and a dryness fraction of 95%. The absorber of an industrial heat pump cycle contains heat exchange pipes filled with the heat pump cycle working fluid, such as R245fa refrigerant or other environmentally friendly organic working fluids. After entering the absorber, the flash steam exchanges heat thoroughly with the working fluid in the pipes, gradually condensing and releasing a large amount of latent heat of vaporization into the working fluid. For example, as the steam gradually condenses from an initial 135 degrees Celsius to 120 degrees Celsius, it releases latent heat of vaporization through a phase change process. This heat is continuously absorbed by the working fluid in the pipes and stored within it, increasing the temperature and enthalpy of the working fluid. This is achieved through heat transfer calculations, for example, based on the heat balance equation: Steam heat release = Steam mass flow rate × Steam phase change enthalpy difference. If the steam flow rate is 1500 kg per hour and the phase change enthalpy difference is 2200 kJ per kg, then the heat released by the flash steam is 3300 MJ per hour. All of this heat is transferred into the working fluid, effectively recovering high-value heat energy from the flue gas.

[0105] When the working fluid absorbs heat in the absorber, its temperature may rise to 75 degrees Celsius, but the pressure is relatively low, such as 0.25 MPa. The heat energy obtained at this point is low-grade heat energy and cannot be directly used for high-quality heating needs. Industrial heat pumps use dedicated compressors, such as the HPC-700 high-speed centrifugal compressor, to draw low-pressure, low-grade working fluid vapor into the compressor and perform efficient mechanical compression, for example, compressing the working fluid vapor from 0.25 MPa to 0.6 MPa or higher. Through this mechanical compression process, both the pressure and temperature of the working fluid vapor are increased simultaneously. The temperature of the compressed working fluid may rise to over 130 degrees Celsius, allowing the originally low-grade heat energy to be converted into high-grade heat energy.

[0106] The condenser contains heat pump working fluid pipes and steam pipes, exchanging heat through a partition wall heat exchange mechanism. The high-temperature, high-pressure working fluid steam gradually condenses and releases its latent heat of condensation as it flows through the condenser. This latent heat of condensation is directly transferred through the condenser wall to the flash steam flowing through the other side of the pipe, further raising its temperature. For example, if the initial temperature of the flash steam is 120 degrees Celsius, through heat transfer within the condenser, its temperature may rise to over 150 degrees Celsius, thus increasing the flash steam's energy level. The heat exchange area of ​​the condenser needs to be determined based on actual energy transfer requirements. For example, the heat transfer coefficient calculation formula can be used for thermodynamic design: Heat exchange area = Heat transfer / (Heat transfer coefficient × Average temperature difference). If the total heat transfer provided by the heat pump cycle working fluid is 2800 MJ / h, the heat transfer coefficient is 1200 W / m² / Kelvin, and the average temperature difference is 20 degrees Celsius, the required heat exchange area is approximately 32 square meters to ensure efficient and sufficient heat transfer from the heat pump working fluid side to the steam side.

[0107] To monitor the operation of industrial heat pump cycles, a high-precision temperature sensor, such as a Pt1000 platinum resistance temperature sensor, is installed at the condenser outlet of the industrial heat pump cycle to monitor and obtain the actual temperature value of the steam after being heated by the condenser in real time.

[0108] A high-precision pressure gauge, such as the EJA530A high-precision pressure sensor, is installed at the condenser outlet of the industrial heat pump cycle to measure and obtain the actual pressure value of the steam after it has been heated by the condenser in real time. The pressure value and temperature information together constitute accurate steam state parameters.

[0109] The actual steam temperature and pressure values ​​after being processed by the industrial heat pump cycle are combined to form the primary preheating steam parameters. For example, the primary preheating steam parameters are a temperature of 152 degrees Celsius and a pressure of 0.55 MPa.

[0110] S4: For flash steam parameters, a centrifugal compressor is used for intermediate compression, outputting intermediate pressure steam parameters, including:

[0111] Calculate the compression ratio control coefficient based on the steam flow rate and initial pressure values ​​in the flash steam parameters;

[0112] The centrifugal compressor is driven by a compression ratio control coefficient to compress flash steam;

[0113] The temperature of the compressed steam is obtained at the outlet of the centrifugal compressor and is used as the temperature of the compressed steam.

[0114] The compressed steam pressure is obtained at the outlet of the centrifugal compressor and is used as the compressed steam pressure.

[0115] The temperature and pressure of the compressed steam are combined to form the intermediate pressure steam parameters.

[0116] Specifically, the input data for determining the compression ratio control coefficient is obtained by measuring the steam flow rate of 1500 kg / h and the initial steam pressure of 0.28 MPa in the flash steam parameters.

[0117] The calculation method for the compression ratio control coefficient is as follows: First, determine the target steam pressure to be achieved. The target steam pressure is set according to the requirements of the industrial production heat process. For example, if a specific production process requires a steam pressure of 0.7 MPa to meet the usage requirements, then the target steam pressure is set to 0.7 MPa. The initial compression ratio is defined as the ratio of the target steam pressure to the initial steam pressure, specifically: Initial compression ratio = Target steam pressure / Initial steam pressure. For example, when the target steam pressure is 0.7 MPa and the initial steam pressure is 0.28 MPa, the calculated initial compression ratio is 2.5.

[0118] The steam flow rate is used as a correction parameter in the calculation of the compression ratio control coefficient. For example, when the steam flow rate exceeds a preset threshold, such as 1500 kg / h, the initial compression ratio is corrected by introducing a flow correction coefficient to ensure optimized compressor operation and prevent the compressor from deviating from its rated state due to flow rate changes. For instance, if the steam flow rate is 1500 kg / h, which is within the design operating range, the flow correction coefficient is set to 1.0, meaning no additional correction is needed. However, if the actual steam flow rate increases to 1800 kg / h, the flow correction coefficient is adjusted to 1.1, thereby appropriately increasing the compression ratio to ensure that the compressor can handle the increased flow load.

[0119] Compression ratio control coefficient = initial compression ratio × flow correction coefficient. For example, when the initial compression ratio is 2.5 and the flow correction coefficient is 1.0, the compression ratio control coefficient is 2.5, which serves as the benchmark for controlling the operation of the compressor.

[0120] The centrifugal compressor selected is a high-speed centrifugal compressor specifically designed for steam compression, such as the HPC-700 model. This compressor features continuously adjustable speed and fine pressure regulation to meet the high-efficiency operation requirements under different compression ratios. The compressor operation control system uses the compression ratio control coefficient as the input signal to drive the compressor motor to adjust its speed, thereby adjusting the compressor's compression intensity to achieve the compression of the flash steam. For example, when the compression ratio control coefficient is 2.5, the compressor control unit drives the motor speed to achieve the corresponding operating condition; for example, the motor speed may be adjusted to 15,000 revolutions per minute to achieve the desired compression ratio. When the impeller inside the compressor rotates at high speed, the flash steam moves radially from the inlet to the outlet along the impeller. The mechanical work provided by the impeller rotation converts mechanical energy into steam pressure and temperature energy, significantly increasing the steam pressure and temperature.

[0121] The inlet flash steam pressure is 0.28 MPa and the temperature is 135 degrees Celsius. After a high-speed mechanical compression process, the outlet steam pressure can be increased to 0.7 MPa and the temperature may increase to 180 degrees Celsius or even higher, thus completing the steam energy level upgrade. A temperature sensor, such as a Pt1000 platinum resistance temperature sensor, is installed at the outlet of the centrifugal compressor to measure the temperature of the compressed steam in real time. A high-precision pressure gauge, such as the aforementioned EJA530A pressure sensor, is also installed at the outlet of the centrifugal compressor to measure the pressure of the compressed steam in real time.

[0122] The real-time measured values ​​of compressed steam temperature and steam pressure are combined to form intermediate pressure steam parameters.

[0123] For example, when the real-time measured temperature of the compressed steam is 180 degrees Celsius and the pressure of the compressed steam is 0.7 MPa, the intermediate pressure steam parameters are combined.

[0124] S5: The primary preheated steam parameters and intermediate pressure steam parameters are integrated in a coupled heat exchanger and intermediate reheater to generate high-grade steam parameters, including:

[0125] Steam corresponding to the first-stage preheating steam parameters is introduced into the first input terminal of the coupled heat exchanger.

[0126] Steam corresponding to the intermediate pressure steam parameters is introduced into the second input terminal of the intermediate reheater.

[0127] Reheated steam is generated by heating the steam corresponding to the intermediate pressure steam parameters through an intermediate reheater.

[0128] Reheated steam is introduced into the second input end of the coupled heat exchanger to exchange heat with steam corresponding to the parameters of the first-stage preheated steam.

[0129] The steam temperature and steam pressure values ​​after heat exchange are obtained at the outlet of the coupled heat exchanger.

[0130] The temperature and pressure values ​​of the steam after heat exchange are combined to form the parameters of high-grade steam.

[0131] Specifically, the primary preheating steam parameters include steam temperature and steam pressure values, such as a temperature of 152 degrees Celsius and a pressure of 0.55 MPa. The coupled heat exchanger is equipped with a first input pipe interface, the pipe diameter, material, and design pressure rating of which are matched to the operating conditions of the primary preheating steam parameters. For example, the pipe material is high-temperature resistant 316L stainless steel, and the pipe diameter is designed to be DN100 mm to meet the requirements of steam flow rate and heat transfer performance. After being regulated by the pressure regulating valve and flow control valve of the primary steam pipeline system, the steam is sent to the first input end of the coupled heat exchanger. After entering the coupled heat exchanger, the steam flows evenly along the internal channels of the heat exchange pipe to achieve optimal heat transfer, thereby fully releasing the heat energy in the primary preheating steam parameters and providing an efficient heat exchange basis for the cascade utilization of flue gas waste heat.

[0132] Steam with intermediate pressure parameters is introduced into the second input terminal of the intermediate reheater to improve its thermal quality. Intermediate pressure steam parameters include steam temperature and pressure, for example, a temperature of 180 degrees Celsius and a pressure of 0.7 MPa. The intermediate reheater is equipped with a second input terminal piping interface, also using high-temperature alloy pipes, such as Inconel 625 nickel-based alloy pipes, with a diameter of DN100 mm. The piping system is equipped with flow control valves and pressure monitoring sensors. After entering the intermediate reheater through the second input terminal, the steam undergoes a more efficient heat exchange through an optimized serpentine or finned pipe structure, ensuring rapid temperature and pressure increases upon entering the reheater, thereby effectively improving the energy quality of the intermediate pressure steam.

[0133] An intermediate reheater is equipped with an independent fuel combustion chamber or an external auxiliary heating source, such as a natural gas burner or a high-efficiency electric heating unit, to supplement the heat energy of the steam entering the reheater. For example, if the intermediate pressure steam enters at a temperature of 180 degrees Celsius and a pressure of 0.7 MPa, the intermediate reheater uses the high-temperature flue gas generated by burning natural gas as a heat source to heat the steam, further increasing the steam temperature to above 210 degrees Celsius, while maintaining or slightly increasing the pressure to around 0.72 MPa, producing reheated steam with significantly improved quality. The heat transfer calculation process of the reheating process can be achieved using the law of conservation of energy: Required heat = Steam mass flow rate × Steam specific heat capacity × Temperature rise. For example, if an intermediate reheater processes 1500 kg of steam per hour, and the specific heat capacity of the steam is 2.0 kJ / kg / degree Celsius, and the temperature needs to be increased by 30 degrees Celsius, then the required input heat is 90,000 kJ / hour.

[0134] Reheated steam is introduced into the second input end of the coupled heat exchanger and undergoes efficient heat exchange with the primary preheated steam, which corresponds to the parameters of the primary preheated steam entering the first input end of the coupled heat exchanger. This achieves comprehensive utilization and integration of energy between steams of different temperatures and pressure levels. The coupled heat exchanger adopts a shell-and-tube or plate heat exchange structure with a dual-channel internal pipe design. This allows steam from different input ends to have sufficient contact and heat transfer in a counter-current or cross-flow manner. For example, if the steam temperature at the first input end is 152 degrees Celsius and the reheated steam temperature at the second input end is 210 degrees Celsius, the steam flows counter-currently within the heat exchanger. The higher-temperature reheated steam gradually transfers heat to the primary preheated steam, raising its temperature and ultimately achieving a higher overall heat capacity.

[0135] Temperature sensors, such as the Pt1000 high-precision platinum resistance temperature sensor, and high-precision pressure sensors, such as the EJA530A pressure sensor, are specially installed at the outlet of the coupled heat exchanger to obtain the actual temperature and pressure values ​​of the steam after heat exchange in real time.

[0136] The actual steam temperature and pressure values ​​obtained after heat exchange are combined to form the parameters for high-grade steam. For example, the measured temperature is 190 degrees Celsius and the pressure is 0.68 MPa.

[0137] S6: The separated liquid phase parameters are subjected to secondary cascade heat recovery using a low-temperature waste heat recovery heat exchanger to generate secondary low-temperature heat recovery parameters, including:

[0138] Based on the liquid phase temperature and liquid phase flow rate in the separated liquid phase parameters, the low-temperature waste heat recovery heat exchanger is controlled to transfer heat energy to the separated liquid phase.

[0139] The temperature of the medium after heat recovery is obtained at the secondary side outlet of the low-temperature waste heat recovery heat exchanger.

[0140] The pressure value of the medium after heat recovery is obtained at the secondary side outlet of the low-temperature waste heat recovery heat exchanger.

[0141] The combined temperature and pressure values ​​of the medium after heat recovery are used to form the secondary low-temperature heat energy recovery parameters.

[0142] Specifically, the low-temperature waste heat recovery heat exchanger adopts a shell-and-tube heat exchange structure. Its internal heat exchange pipes are made of high thermal conductivity materials, such as 304 stainless steel, with a pipe diameter of DN80 mm to ensure heat exchange efficiency and sufficient heat transfer. The heat exchange medium circulating in the secondary side pipes is selected from media such as heat transfer oil, water, or ethylene glycol aqueous solution to adapt to efficient heat energy absorption within the liquid phase temperature range. Based on the real-time obtained liquid phase temperature and flow rate values, the control unit precisely controls and adjusts the valve opening and pump circulation flow rate to achieve accurate matching between the heat exchange medium flow rate and the heat load of the separated liquid phase. For example, when the liquid phase flow rate is stable at 2000 kg / h and the temperature is 120 degrees Celsius, the control unit calculates the heat that can be released from the liquid phase as: Heat = Liquid phase mass flow rate × Liquid phase heat capacity × Temperature difference. If the liquid phase heat capacity is 4.18 kJ / kg / °C, and the liquid phase needs to be cooled from 120°C to 90°C, then the heat released per hour is 2000 kg × 4.18 kJ / kg / °C × (120 - 90°C) = 250800 kJ. Based on this calculation, the heat exchanger's automatic control unit adjusts the operating status of the secondary circulation pump and valves to ensure the heat exchange medium accurately absorbs the heat released from the separated liquid phase, guaranteeing efficient and stable operation of the entire heat recovery process.

[0143] A high-precision temperature sensor is installed at the secondary side outlet of the low-temperature waste heat recovery heat exchanger to acquire the temperature of the medium after heat recovery in real time, ensuring real-time monitoring and precise control of the heat exchange effect. After sufficient heat exchange between the secondary side heat exchange medium and the separated liquid phase flowing inside the shell-and-tube heat exchanger, the medium temperature rises. For example, if the medium's temperature is 60 degrees Celsius when it enters the heat exchanger, it rises to 85 degrees Celsius after sufficient heat exchange. The real-time measurement results of these medium temperatures are transmitted to the automatic control unit for real-time optimization and adjustment of the secondary side medium flow rate and heat exchanger operating parameters. This ensures that the heat exchange efficiency is always at its optimal operating condition, preventing excessive or insufficient heat exchange and avoiding energy waste and abnormal equipment operation.

[0144] A high-precision pressure measuring device is installed on the secondary side outlet pipeline of the cryogenic waste heat recovery heat exchanger to obtain the pressure value of the medium after heat recovery in real time, and to monitor and control the operating status of the medium and the safe operation of the equipment. The pressure measuring device, for example, uses an EJA530A high-precision pressure sensor to measure the actual operating pressure of the medium as it passes through the heat exchanger outlet. For example, the secondary side medium outlet pressure may be measured as 0.3 MPa in real time. The pressure measurement data is transmitted to the control system in real time to determine whether the secondary side medium is within the normal operating pressure range. If the actual operating pressure of the medium exceeds the set safety upper limit of the equipment, for example, higher than 0.35 MPa, the control system will take measures such as adjusting the opening of the secondary side pipeline valves or the speed of the circulating pump to stabilize the pressure within the safe range.

[0145] The real-time obtained temperature and pressure values ​​of the recovered medium are integrated and combined to form secondary low-temperature heat recovery parameters.

[0146] S7: A multivariable fuzzy PID algorithm is used to monitor and regulate the parameters of high-grade steam and secondary low-temperature heat recovery, outputting real-time control commands, including:

[0147] Based on the parameters of high-grade steam and secondary low-temperature heat recovery, the steam temperature deviation, steam pressure deviation, medium temperature deviation, and medium pressure deviation are calculated.

[0148] Input the steam temperature deviation, steam pressure deviation, medium temperature deviation, and medium pressure deviation into the multivariable fuzzy PID controller;

[0149] The three-channel regulation is executed synchronously by a multivariable fuzzy PID controller, and the real-time regulation control command is output.

[0150] Specifically, target steam temperature setpoints, target steam pressure setpoints, target medium temperature setpoints, and target medium pressure setpoints are pre-stored. For example, the target high-grade steam temperature setpoint might be 195 degrees Celsius, and the steam pressure setpoint might be 0.7 MPa; the target temperature setpoint for the secondary low-temperature heat recovery medium might be 88 degrees Celsius, and the target medium pressure setpoint might be 0.32 MPa. The actual operating parameters are compared with the target setpoints to calculate the deviation values ​​between each parameter. For example, the steam temperature deviation is calculated by subtracting the real-time measured steam temperature value from the target steam temperature setpoint, i.e., 195 degrees Celsius - 190 degrees Celsius = 5 degrees Celsius; the steam pressure deviation is calculated as 0.7 MPa - 0.68 MPa = 0.02 MPa; the medium temperature deviation is calculated as 88 degrees Celsius - 85 degrees Celsius = 3 degrees Celsius; and the medium pressure deviation is calculated as 0.32 MPa - 0.3 MPa = 0.02 MPa. The deviation value directly reflects the degree of deviation between the current actual operating state of the recovery system and the target operating condition, indicating the specific direction and magnitude of the adjustment that needs to be made.

[0151] The multivariable fuzzy PID controller internally sets up multiple independent control channels, each including a control module that combines a fuzzy controller and a PID controller. For example, the steam temperature control channel takes the steam temperature deviation value as input. The fuzzy control algorithm describes the temperature deviation value as a linguistic variable, for example, defining a deviation of 5 degrees Celsius as "slightly low". Then, the fuzzy controller calls the built-in fuzzy rule library and outputs the corresponding combination of PID control parameters, such as proportional, integral, and derivative parameters, thereby driving the PID controller to precisely adjust the controlled object. The same method is applied to the steam pressure control channel, the medium temperature control channel, and the medium pressure control channel, achieving real-time, synchronous, and coordinated adjustment of the four control variables, ensuring optimal system stability and optimization.

[0152] Three-channel regulation is synchronously executed through a multivariable fuzzy PID controller, including: regulating the opening of the heat medium flow valve in the coupled heat exchanger; regulating the opening of the fuel supply valve in the intermediate reheater; and regulating the opening of the heat transfer medium valve in the cryogenic waste heat recovery heat exchanger. The first channel regulates the heat medium flow valve in the coupled heat exchanger, for example, using a high-precision electric regulating valve, such as the VFM-600 electric valve, regulated by the output signal of the PID controller. If the steam temperature deviation is 5 degrees Celsius, and it is determined that the heat medium flow needs to be increased, the controller sends a valve opening signal, gradually increasing the valve opening, for example, from 60% to 65%, thereby increasing the heat medium flow, increasing the heat supply, and achieving an increase in steam temperature. The second channel regulates the fuel supply valve in the intermediate reheater, for example, a VFG-300 gas-fired electric valve. When the steam pressure deviation is 0.02 MPa, the control system increases the opening of the fuel supply valve, increasing the burner heat output, and gradually bringing the steam pressure to the set target value. The third channel controls the heat transfer medium valve of the low-temperature waste heat recovery heat exchanger, such as the VFO-200 electric heat transfer medium valve. When the medium temperature deviation is 3 degrees Celsius, the controller adjusts the heat transfer medium flow rate in real time to improve the secondary low-temperature waste heat recovery effect and gradually bring the medium temperature closer to the set value. The adjustment actions of the above three channels are executed synchronously, and each adjusts the valve opening of the corresponding equipment in real time according to the actual deviation value to ensure the efficient and stable operation of the overall flue gas waste heat recovery system.

[0153] The system outputs real-time control signals for the coupled heat exchanger valves, intermediate reheater valves, and cryogenic waste heat recovery heat exchanger valves as real-time regulation and control commands. These control signals are output in standard 4-20mA or 0-10V industrial signal format and transmitted in real-time to the corresponding electric valve actuators via signal transmission lines, enabling rapid valve response. For example, the control signal for the coupled heat exchanger's heat medium flow valve is 12mA, corresponding to a valve opening of 65%; the intermediate reheater's fuel valve control signal is 13mA, corresponding to a valve opening of 70%; and the cryogenic heat exchanger's heat transfer medium valve control signal is 11mA, corresponding to a valve opening of 55%. This real-time output of regulation and control commands not only ensures timely response and adjustment of the valve equipment but also provides the foundation for the automated control of the entire industrial heat pump coupled flue gas waste heat recovery system. It ensures that the temperature, pressure, and flow parameters throughout the entire flue gas waste heat recovery process remain continuously optimized and highly stable, achieving efficient, economical, environmentally friendly, and safe utilization of flue gas waste heat resources.

[0154] Example 2

[0155] The difference between Embodiment 2 and Embodiment 1 is that this embodiment introduces an industrial heat pump coupled flue gas waste heat cascade recovery system.

[0156] Figure 2 A schematic diagram of an industrial heat pump coupled flue gas waste heat cascade recovery system according to the present invention is provided. The industrial heat pump coupled flue gas waste heat cascade recovery system includes:

[0157] Flue gas treatment module: Collects temperature, flow rate and composition information of waste heat flue gas, performs preprocessing, and outputs preprocessed flue gas characteristic data;

[0158] Vapor-liquid separation module: Based on flue gas characteristic data, a flash evaporator vapor-liquid separation method is used to obtain flash steam parameters and separated liquid phase parameters respectively;

[0159] Heat pump temperature boosting module: The flash steam parameters are boosted by an industrial heat pump cycle to generate primary preheated steam parameters;

[0160] Steam compression module: The flash steam parameters are compressed intermediately using a centrifugal compressor to output intermediate pressure steam parameters;

[0161] Thermal energy integration module: The primary preheated steam parameters and intermediate pressure steam parameters are integrated in a coupled heat exchanger and intermediate reheater to generate high-grade steam parameters;

[0162] Liquid phase recovery module: The separated liquid phase parameters are recovered in a secondary cascade heat recovery stage using a low-temperature waste heat recovery heat exchanger to generate secondary low-temperature heat recovery parameters;

[0163] Intelligent control module: It uses a multivariable fuzzy PID algorithm to monitor and regulate the parameters of high-grade steam and secondary low-temperature heat recovery, and outputs real-time control commands.

[0164] The above formulas are all dimensionless calculations. The formulas are derived from software simulations based on a large amount of collected data to obtain the most recent real-world results. The preset parameters and thresholds in the formulas are set by those skilled in the art according to the actual situation.

[0165] The above embodiments can be implemented, in whole or in part, by software, hardware, firmware, or any other combination thereof. When implemented using software, the above embodiments can be implemented, in whole or in part, as a computer program product. The computer program product includes one or more computer instructions or computer programs. When the computer instructions or computer programs are loaded or executed on a computer, all or part of the processes or functions described in the embodiments of this application are generated. The computer can be a general-purpose computer, a special-purpose computer, a computer network, or other programmable device. The computer instructions can be stored in a computer-readable storage medium or transmitted from one computer-readable storage medium to another. For example, the computer instructions can be transmitted from one website, computer, server, or data center to another website, computer, server, or data center via wired (e.g., infrared, wireless, microwave, etc.) means. The computer-readable storage medium can be any available medium that a computer can access or a data storage device such as a server or data center that includes one or more sets of available media. The available medium can be a magnetic medium (e.g., floppy disk, hard disk, magnetic tape), an optical medium (e.g., DVD), or a semiconductor medium. The semiconductor medium can be a solid-state drive.

[0166] Those skilled in the art will recognize that the modules and algorithm steps of the various examples described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, or a combination of computer software and electronic hardware. Whether these functions are implemented in hardware or software depends on the specific application and design constraints of the technical solution. Those skilled in the art can use different methods to implement the described functions for each specific application, but such implementation should not be considered beyond the scope of this application.

[0167] Those skilled in the art will understand that, for the sake of convenience and brevity, the specific working processes of the systems, devices, and modules described above can be referred to the corresponding processes in the foregoing method embodiments, and will not be repeated here.

[0168] In the several embodiments provided in this application, it should be understood that the disclosed systems, apparatuses, and methods can be implemented in other ways. For example, the apparatus embodiments described above are merely illustrative; for instance, the division of modules is only a logical functional division, and in actual implementation, there may be other division methods. For example, multiple modules or components may be combined or integrated into another system, or some features may be ignored or not executed. Furthermore, the coupling or direct coupling or communication connection shown or discussed may be through some interfaces; the indirect coupling or communication connection between apparatuses or modules may be electrical, mechanical, or other forms.

[0169] The modules described as separate components may or may not be physically separate. The components shown as modules may or may not be physical modules; they may be located in one place or distributed across multiple network modules. Some or all of the modules can be selected to achieve the purpose of this embodiment according to actual needs.

[0170] In addition, the functional modules in the various embodiments of this application can be integrated into one processing module, or each module can exist physically separately, or two or more modules can be integrated into one module.

[0171] If the aforementioned functions are implemented as software functional modules and sold or used as independent products, they can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of this application, in essence, or the part that contributes to the prior art, or a portion of the technical solution, can be embodied in the form of a software product. This computer software product is stored in a storage medium and includes several instructions to cause a computer device (which may be a personal computer, server, or network device, etc.) to execute all or part of the steps of the methods described in the various embodiments of this application. The aforementioned storage medium includes various media capable of storing program code, such as USB flash drives, portable hard drives, read-only memory (ROM), random access memory (RAM), magnetic disks, or optical disks.

[0172] The above description is merely a specific embodiment of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

[0173] In conclusion, the above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for cascade recovery of waste heat from flue gas coupled with an industrial heat pump, characterized in that, Includes the following steps: S1: Collect temperature, flow rate and composition information of waste heat flue gas, perform preprocessing, and output preprocessed flue gas characteristic data; S2: Based on flue gas characteristic data, a flash evaporator steam-liquid separation method is used to obtain flash steam parameters and separated liquid phase parameters respectively; S3: For flash steam parameters, an industrial heat pump cycle is used for primary temperature increase to generate primary preheated steam parameters; S4: For flash steam parameters, a centrifugal compressor is used for intermediate compression to output intermediate pressure steam parameters; S5: The primary preheated steam parameters and intermediate pressure steam parameters are integrated in the coupled heat exchanger and intermediate reheater to generate high-grade steam parameters. S6: The separated liquid phase parameters are subjected to secondary cascade heat recovery using a low-temperature waste heat recovery heat exchanger to generate secondary low-temperature heat recovery parameters; S7: The high-grade steam parameters and the secondary low-temperature heat recovery parameters are monitored and adjusted using a multivariable fuzzy PID algorithm, and real-time adjustment and control commands are output.

2. The method for cascade recovery of flue gas waste heat coupled with an industrial heat pump according to claim 1, characterized in that, S1, specifically: At the outlet of the industrial flue gas heat exchanger, collect temperature, flow rate and composition information of the waste heat flue gas. Noise filtering is performed on temperature, flow rate, and flue gas composition information; Deviation correction is performed on temperature information, flow rate information, and flue gas composition information; The temperature, flow, and flue gas composition information after deviation correction are formatted into a predefined standard data format; The formatted temperature, flow rate, and flue gas composition information are used as preprocessed flue gas characteristic data.

3. The method for cascade recovery of flue gas waste heat coupled with an industrial heat pump according to claim 2, characterized in that, S2, specifically: Based on the temperature, flow and composition information in the flue gas characteristic data, the set working pressure value of the flash evaporator is calculated. Calculate the saturated evaporation temperature of the flash evaporator based on the working pressure and temperature information; Based on the saturated evaporation temperature value and temperature information, the flash evaporator is controlled to perform steam-water separation on the waste heat flue gas. The flash steam state parameters are obtained at the flash evaporator outlet and used as flash steam parameters. The state parameters of the separated liquid phase are obtained at the bottom drain port of the flash evaporator and used as the parameters of the separated liquid phase.

4. The method for cascade recovery of flue gas waste heat coupled with an industrial heat pump according to claim 3, characterized in that, S3, specifically: The latent heat of vaporization in flash steam parameters is extracted using an absorber from an industrial heat pump cycle. The compressor of the industrial heat pump cycle converts the low-grade heat energy output from the absorber into high-grade heat energy. High-grade heat energy is input into flash steam using a condenser that utilizes an industrial heat pump cycle. A temperature sensor is installed at the condenser outlet of the industrial heat pump cycle to obtain the steam temperature value after the temperature is raised. A pressure gauge is installed at the condenser outlet of the industrial heat pump cycle to obtain the steam pressure value after the temperature is raised; The temperature and pressure of the heated steam are combined to form the primary preheating steam parameters.

5. The method for cascade recovery of flue gas waste heat coupled with an industrial heat pump according to claim 4, characterized in that, S4, specifically: Calculate the compression ratio control coefficient based on the steam flow rate and initial pressure values ​​in the flash steam parameters; The centrifugal compressor is driven by a compression ratio control coefficient to compress flash steam; The temperature of the compressed steam is obtained at the outlet of the centrifugal compressor and is used as the temperature of the compressed steam. The compressed steam pressure is obtained at the outlet of the centrifugal compressor and is used as the compressed steam pressure. The temperature and pressure of the compressed steam are combined to form the intermediate pressure steam parameters.

6. The method for cascade recovery of flue gas waste heat coupled with an industrial heat pump according to claim 5, characterized in that, S5, specifically: Steam corresponding to the first-stage preheating steam parameters is introduced into the first input terminal of the coupled heat exchanger. Steam corresponding to the intermediate pressure steam parameters is introduced into the second input terminal of the intermediate reheater. Reheated steam is generated by heating the steam corresponding to the intermediate pressure steam parameters through an intermediate reheater. Reheated steam is introduced into the second input end of the coupled heat exchanger to exchange heat with steam corresponding to the parameters of the first-stage preheated steam. The steam temperature and steam pressure values ​​after heat exchange are obtained at the outlet of the coupled heat exchanger. The temperature and pressure values ​​of the steam after heat exchange are combined to form the parameters of high-grade steam.

7. The method for cascade recovery of flue gas waste heat coupled with an industrial heat pump according to claim 6, characterized in that, S6, specifically: Based on the liquid phase temperature and liquid phase flow rate in the separated liquid phase parameters, the low-temperature waste heat recovery heat exchanger is controlled to transfer heat energy to the separated liquid phase. The temperature of the medium after heat recovery is obtained at the secondary side outlet of the low-temperature waste heat recovery heat exchanger. The pressure value of the medium after heat recovery is obtained at the secondary side outlet of the low-temperature waste heat recovery heat exchanger. The combined temperature and pressure values ​​of the medium after heat recovery are used to form the secondary low-temperature heat energy recovery parameters.

8. The method for cascade recovery of flue gas waste heat coupled with an industrial heat pump according to claim 7, characterized in that, S7, specifically: Based on the parameters of high-grade steam and secondary low-temperature heat recovery, the steam temperature deviation, steam pressure deviation, medium temperature deviation, and medium pressure deviation are calculated. Input the steam temperature deviation, steam pressure deviation, medium temperature deviation, and medium pressure deviation into the multivariable fuzzy PID controller; The three-channel regulation is executed synchronously by a multivariable fuzzy PID controller, and the real-time regulation control command is output.

9. An industrial heat pump coupled flue gas waste heat cascade recovery system, used to implement the industrial heat pump coupled flue gas waste heat cascade recovery method according to any one of claims 1-8, characterized in that, include: Flue gas treatment module: Collects temperature, flow rate and composition information of waste heat flue gas, performs preprocessing, and outputs preprocessed flue gas characteristic data; Vapor-liquid separation module: Based on flue gas characteristic data, a flash evaporator vapor-liquid separation method is used to obtain flash steam parameters and separated liquid phase parameters respectively; Heat pump temperature boosting module: The flash steam parameters are boosted by an industrial heat pump cycle to generate primary preheated steam parameters; Steam compression module: The flash steam parameters are compressed intermediately using a centrifugal compressor to output intermediate pressure steam parameters; Thermal energy integration module: The primary preheated steam parameters and intermediate pressure steam parameters are integrated in a coupled heat exchanger and intermediate reheater to generate high-grade steam parameters; Liquid phase recovery module: The separated liquid phase parameters are recovered in a secondary cascade heat recovery stage using a low-temperature waste heat recovery heat exchanger to generate secondary low-temperature heat recovery parameters; Intelligent control module: It uses a multivariable fuzzy PID algorithm to monitor and regulate the parameters of high-grade steam and secondary low-temperature heat recovery, and outputs real-time control commands.

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