A karenah cycle power generation system based on orc working pairs and application thereof

Abstract

This invention relates to the field of low-grade thermal power generation technology, and more particularly to a Karina cycle power generation system based on an ORC working fluid pair and its application. The system includes a power generation unit with a circulating working fluid consisting of a first low-boiling-point component and a second high-boiling-point component. An external heat source is introduced into the heat exchange unit to heat the working fluid. A phase change separation unit separates the heated working fluid into a gas phase branch and a liquid phase branch. The gas phase branch is connected to a turbine expander to convert thermal energy into electrical energy. A control device acquires external heat source temperature distribution data and real-time phase change temperature data of the working fluid through a status acquisition module. A temperature difference calculation module generates heat exchange temperature difference data including temperature deviation values. A circulation control module receives the heat exchange temperature difference data and outputs flow regulation commands to a pressurized pumping unit to adjust the circulating flow rate of the working fluid, reduce the heat exchange temperature difference, and improve the thermoelectric conversion efficiency.

Description

Technical Field

[0001] This invention relates to the field of low-grade thermal power generation technology, and in particular to a Karina cycle power generation system based on ORC working fluid pairs and its application. Background Technology

[0002] The organic Rankine cycle is a conventional technology for power generation using low-grade heat energy, primarily employing low-boiling-point organic compounds as the working medium. The working medium absorbs heat from an external heat source within the evaporator and converts it into high-pressure steam. This high-pressure steam then enters a turbine, expands, performs work, and drives a generator to produce electricity. The exhaust steam, having completed its work, condenses into a liquid state inside the condenser and is then pressurized and returned to the evaporator via a working fluid pump, thus completing the thermodynamic cycle. The conventional Karina cycle is also a low-calorific-value energy recovery and utilization technology, primarily using an ammonia-water mixture as the working medium. During the phase change phase, the mixture undergoes both concentration and temperature changes; this variable-temperature phase change characteristic causes the endothermic temperature curve to closely match the heat source exothermic temperature curve.

[0003] Existing conventional pure-medium organic Rankine cycle systems have objective technical defects. The pure single medium maintains a constant temperature during boiling and vaporization under fixed pressure, while the external liquid waste heat fluid continuously decreases in temperature during heat release. This isothermal vaporization phenomenon leads to a large heat transfer temperature difference between the two phases. This large temperature difference directly causes irreversible thermodynamic losses, thereby reducing the overall thermoelectric conversion efficiency of the system. For example, in industrial high-temperature wastewater recovery systems, the wastewater temperature continuously decreases in stages, while the pure organic medium can only undergo phase change vaporization at specific temperature points. This mismatch in heat transfer temperature trajectories results in a large amount of effective heat energy not being fully utilized. Furthermore, the ammonia-water mixture solution used in existing conventional Karina cycles also has technical limitations. Ammonia itself is toxic and corrosive. These toxic and corrosive properties increase the manufacturing cost of pipeline sealing and corrosion protection, and leaks of high-pressure fluids can easily lead to safety accidents. Summary of the Invention

[0004] To address the shortcomings of existing technologies, this invention provides a Karina cycle power generation system based on ORC working fluid pairs and its application, solving the technical problem of large irreversible heat exchange losses caused by the mismatch between the constant-temperature evaporation of a single working fluid and the variable-temperature heat source.

[0005] To solve the above-mentioned technical problems, the specific contents of the present invention are as follows: In a first aspect, the present invention provides a Karina cycle power generation system based on ORC working fluid pairs, including power generation equipment and a control device that establishes a communication connection with the power generation equipment; The power generation equipment circulates a mixed working fluid composed of a first low-boiling-point component and a second high-boiling-point component. The power generation equipment includes a heat exchange unit, a phase change separation unit, a turbine expander, a mixing and condensing unit, and a pressurized pumping unit connected in sequence. The heat exchange unit introduces an external heat source to heat the mixed working fluid. The phase change separation unit separates the heated mixed working fluid into a gas phase branch and a liquid phase branch. The gas phase branch is connected to the turbine expander to convert heat energy into electrical energy. The liquid phase branch and the exhaust steam from the turbine expander are transported to the mixing and condensing unit, where they collect and condense into a liquid fluid. The pressurized pumping unit repressurizes the liquid fluid and transports it back to the heat exchange unit. The control device includes a status acquisition module, a temperature difference calculation module, and a cycle control module; The status acquisition module acquires the temperature distribution data of the external heat source and the real-time phase change temperature data of the mixed working fluid in the heat exchange unit; The temperature difference calculation module retrieves the temperature distribution data and the real-time phase change temperature data for numerical comparison, and generates heat transfer temperature difference data including temperature deviation values. The circulation control module receives the heat exchange temperature difference data. When the temperature deviation value in the heat exchange temperature difference data exceeds the preset value range, it outputs a flow rate adjustment command to the pressurized pumping unit to adjust the circulation speed of the mixed working fluid in the power generation equipment.

[0006] Furthermore, in the Karina cycle power generation system based on ORC working fluid pairs described in this invention, the temperature difference calculation module includes: The curve mapping unit retrieves the temperature distribution data and maps the temperature distribution data according to the preset coordinate node positions to generate a heat release reference curve. The temperature difference comparison unit retrieves the real-time phase change temperature data and compares it with the heat release reference curve at the preset coordinate node position, calculates the temperature deviation value at the preset coordinate node position, and generates the heat exchange temperature difference data. The signal triggering unit extracts the temperature deviation value from the heat exchange temperature difference data, and outputs a trigger signal to the circulation control module when the temperature deviation value is greater than a preset deviation threshold, instructing the circulation control module to output the flow rate adjustment command.

[0007] Furthermore, in the Karina cycle power generation system based on ORC working fluid pairs described in this invention, the power generation equipment further includes a heat recovery unit; the heat recovery unit is connected between the outlet of the pressurized pumping unit, the inlet of the heat exchange unit, the liquid phase outlet of the phase change separation unit, and the inlet of the mixing and condensing unit; the heat recovery unit guides the liquid phase branch to release heat, and guides the liquid fluid output by the pressurized pumping unit to absorb the heat released by the liquid phase branch.

[0008] Furthermore, in the Karina cycle power generation system based on ORC working fluid pairs described in this invention, the state acquisition module extracts the gas phase branch flow data and the liquid phase branch flow data discharged from the phase change separation unit; the control device further includes a concentration calculation module, which retrieves the gas phase branch flow data and the liquid phase branch flow data, calculates the numerical ratio between the gas phase branch flow data and the liquid phase branch flow data, generates a concentration parameter of the mixed working fluid entering the heat recovery unit, and sends the concentration parameter to the cycle control module.

[0009] Furthermore, in the Karina cycle power generation system based on ORC working fluid pairs described in this invention, the cycle control module includes a liquid replenishment control unit, the mixing and condensing unit is provided with a liquid replenishment port, and the liquid replenishment port is equipped with a regulating valve; the liquid replenishment control unit receives the concentration parameter, calculates the difference data between the concentration parameter and the preset concentration value, and outputs a liquid replenishment valve control command based on the difference data; the liquid replenishment valve control command is sent to the regulating valve, and the mass flow ratio of the first low-boiling-point component and the second high-boiling-point component is adjusted by changing the opening degree of the regulating valve.

[0010] Furthermore, in the Karina cycle power generation system based on ORC working fluid pair described in this invention, the first low-boiling-point component includes a non-azeotropic refrigerant, and the second high-boiling-point component includes an organic solvent, wherein the saturated vapor pressure of the organic solvent at room temperature is lower than a preset pressure value; the non-azeotropic refrigerant and the organic solvent exhibit a state in which the phase change vaporization temperature continuously changes with the liquid phase concentration within the heat exchange unit.

[0011] Furthermore, in the Karina cycle power generation system based on ORC working fluid pair described in this invention, the power generation equipment includes a sensor assembly; the sensor assembly includes a temperature sensor installed at the inlet of the heat exchange unit and a flow sensor installed on the internal connecting pipeline of the power generation equipment; the temperature sensor collects temperature data and converts it into a temperature signal including the temperature distribution data and the real-time phase change temperature data, which is then transmitted to the status acquisition module; the flow sensor collects flow rate data and converts it into a flow signal, which is then transmitted to the status acquisition module.

[0012] Furthermore, in the Karina cycle power generation system based on ORC working fluid pairs described in this invention, the heat exchange unit is connected to an external heat source inlet pipe, and a heat source flow control valve is installed on the external heat source inlet pipe; the turbine expander has an inlet pipe, and the control device further includes a pressure ratio calculation module. The pressure ratio calculation module acquires the high-pressure data at the inlet pipe of the turbine expander and the low-pressure data inside the mixing and condensing unit, and calculates the ratio of the high-pressure data to the low-pressure data to generate a pressure ratio value; when the pressure ratio value is lower than the operating set value, the pressure ratio calculation module outputs an opening command to the heat source flow control valve to increase the inflow of the external heat source.

[0013] Furthermore, in the Karina cycle power generation system based on ORC working fluid pair described in this invention, the power generation equipment further includes a bypass vent valve, which is connected to the inlet pipeline of the turbine expander; the cycle control module has a built-in safety pressure relief unit, which receives the high pressure data and outputs a venting command to the bypass vent valve when the high pressure data exceeds the upper limit of the safety bearing capacity, thereby discharging part of the mixed working fluid to reduce the absolute pressure inside the power generation equipment.

[0014] Secondly, the present invention provides an application of the Karina cycle power generation system based on ORC working fluid pairs, wherein the application is as follows: waste liquid or waste gas with a temperature gradient is introduced into the heat exchange unit as the external heat source, and the turbine expander outputs electrical energy.

[0015] Beneficial effects of this invention; This invention provides a Karina cycle power generation system based on an ORC working fluid pair and its application, representing a substantial technological advancement. A mixed working fluid, composed of a first low-boiling-point component and a second high-boiling-point component, circulates within the power generation equipment. The control device acquires temperature distribution data from an external heat source and real-time phase change temperature data of the mixed working fluid within the heat exchange unit via a status acquisition module. A temperature difference calculation module retrieves the temperature distribution data and real-time phase change temperature data, compares the values, and generates heat exchange temperature difference data including temperature deviation values. A circulation control module receives the heat exchange temperature difference data; when the temperature deviation value exceeds a preset range, it outputs a flow rate adjustment command to the pressurized pumping unit. The pressurized pumping unit adjusts the circulation velocity of the mixed working fluid within the power generation equipment according to the flow rate adjustment command. The hardware power generation equipment and data control logic work closely together, enabling the mixed working fluid, composed of the first low-boiling-point component and the second high-boiling-point component, to undergo a non-isothermal vaporization phase change characteristic within the heat exchange unit. The endothermic temperature rise curve of the mixed working fluid closely matches the exothermic temperature curve of the external heat source through real-time adjustment of the circulation flow rate. This coordinated response mechanism of data control and hardware structure changes the existing conventional pure-medium organic Rankine cycle system's operating model of constant-temperature boiling and vaporization under fixed pressure conditions. At the thermodynamic transfer level, the system effectively reduces the heat transfer temperature difference between the two heat-transferring fluids, completely overcoming the technical defects of existing technologies where the mismatch in heat transfer temperature trajectories due to the isothermal evaporation of a pure single medium leads to severe irreversible thermodynamic losses. By effectively reducing the system's available energy dissipation during the heat exchange process, the power generation system ultimately achieves the objective technical effect of fully utilizing low-grade thermal energy and significantly improving the overall thermoelectric conversion efficiency of the system. Attached Figure Description

[0016] To more clearly illustrate the technical solution of the present invention, the drawings used in the embodiments will be briefly introduced below. Obviously, for those skilled in the art, other drawings can be obtained based on the drawings without creative effort.

[0017] Figure 1 This is a system architecture diagram of the Karina cycle power generation system based on ORC working fluid pairs according to the present invention. Detailed Implementation

[0018] To make the technical solution of the present invention clearer, the present invention will be clearly and completely described below with reference to specific embodiments and corresponding drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention. The embodiments of the present invention will be described in detail below with reference to the accompanying drawings. To better understand the purpose of the present invention, the present invention will be described in further detail below.

[0019] Firstly, please refer to Figure 1 The present invention provides a Karina cycle power generation system based on ORC working fluid pair, including power generation equipment and a control device that establishes a communication connection with the power generation equipment; The power generation equipment circulates a mixed working fluid composed of a first low-boiling-point component and a second high-boiling-point component. The power generation equipment includes a heat exchange unit, a phase change separation unit, a turbine expander, a mixing and condensing unit, and a pressurized pumping unit connected in sequence. The heat exchange unit introduces an external heat source to heat the mixed working fluid. The phase change separation unit separates the heated mixed working fluid into a gas phase branch and a liquid phase branch. The gas phase branch is connected to the turbine expander to convert heat energy into electrical energy. The liquid phase branch and the exhaust steam from the turbine expander are transported to the mixing and condensing unit, where they collect and condense into a liquid fluid. The pressurized pumping unit repressurizes the liquid fluid and transports it back to the heat exchange unit. The control device includes a status acquisition module, a temperature difference calculation module, and a cycle control module; The status acquisition module acquires the temperature distribution data of the external heat source and the real-time phase change temperature data of the mixed working fluid in the heat exchange unit; The temperature difference calculation module retrieves the temperature distribution data and the real-time phase change temperature data for numerical comparison, and generates heat transfer temperature difference data including temperature deviation values. The circulation control module receives the heat exchange temperature difference data. When the temperature deviation value in the heat exchange temperature difference data exceeds the preset value range, it outputs a flow rate adjustment command to the pressurized pumping unit to adjust the circulation speed of the mixed working fluid in the power generation equipment.

[0020] Regarding the processing mechanism of the temperature difference calculation module, the underlying data processing path is as follows: the curve mapping unit reads the temperature distribution data sequence, performs spatial position interpolation fitting on the discrete temperature values ​​in the temperature distribution data sequence according to the preset coordinate node position vector, thereby generating a heat release reference curve matrix that is continuously distributed in the heat transfer space domain. As a further optimization of the technical solution of this invention, the above-mentioned spatial position interpolation fitting process is specifically implemented through a pre-deployed lightweight model. Combined with the specific application scenarios of low-grade thermal energy and industrial waste heat cascade recovery, the lightweight model is configured as a multilayer perceptron or a one-dimensional convolutional neural network structure. The input data of the lightweight model is set as a multidimensional feature vector composed of the discrete temperature values ​​and the corresponding preset coordinate node positions, and the output data is set as a continuously distributed exothermic reference curve matrix within the heat transfer spatial domain. In constructing the inherent correlation between the data, the discrete temperature value sequence in the input data objectively reflects the initial thermodynamic boundary conditions of the external heat source. The hidden layer inside the lightweight model extracts the nonlinear temperature gradient physical features between adjacent coordinate node positions by performing matrix multiplication and nonlinear mapping operations on the multidimensional feature vector, thereby outputting a high-precision exothermic reference curve matrix across the entire domain. The necessary steps for training the lightweight model include: collecting discrete temperature sample data of the heat exchange unit under historical operating conditions as the input of the training set; collecting the global high-density measured thermal field temperature matrix corresponding to the discrete temperature sample data as the label of the training set; inputting the discrete temperature sample data into the initial lightweight network structure to obtain the prediction reference curve matrix; constructing the mean square error loss function between the prediction reference curve matrix and the label; and iteratively updating the weight parameters of the lightweight model by calling the backpropagation algorithm until the absolute value of the loss function is lower than a preset convergence threshold, thereby completing the training of the lightweight model.

[0021] The temperature difference comparison unit calls the real-time phase change temperature data array and performs a one-to-one subtraction operation between the values ​​in the real-time phase change temperature data array and the exothermic reference curve matrix at preset coordinate node positions to calculate the set of absolute temperature deviation values ​​at the preset coordinate node positions. This set of absolute temperature deviation values ​​is then encapsulated to generate heat transfer temperature difference data. Further, the signal triggering unit continuously extracts all temperature deviation values ​​from the heat transfer temperature difference data and performs a traversal comparison and judgment. Under the judgment condition that the temperature deviation value at any coordinate node is greater than a preset deviation threshold (e.g., a deviation threshold of 5 degrees Celsius), the signal triggering unit switches from a low-level to a high-level trigger signal and sends it to the circulation control module to instruct the circulation control module to output a flow regulation command.

[0022] In constructing the thermodynamic topology of the heat recovery unit, the specific conversion mechanism is as follows: the heat recovery unit has an internal counter-current heat exchange channel, which is connected to the outlet of the pressurized pumping unit, the inlet of the heat exchange unit, the liquid phase outlet of the phase change separation unit, and the inlet of the mixing and condensing unit. The liquid phase branch separated from the liquid phase outlet of the phase change separation unit has a high sensible enthalpy value and is introduced into the heat release side channel of the heat recovery unit to release heat; simultaneously, the subcooled liquid fluid output from the pressurized pumping unit is introduced into the heat absorption side channel of the heat recovery unit. During the heat transfer process, the liquid fluid absorbs the heat released by the liquid phase branch, causing a temperature rise, before entering the inlet of the heat exchange unit, while the liquid phase branch stripped of heat flows out of the heat recovery unit and merges into the inlet of the mixing and condensing unit for throttling and pressure reduction.

[0023] Regarding the flow characteristics at the outlet of the phase change separation unit, the calculation path for the underlying physical property parameters is as follows: The state acquisition module extracts the gas phase branch flow data of the gas phase branch flowing in the gas phase pipeline of the phase change separation unit, and extracts the liquid phase branch flow data of the liquid phase branch flowing in the liquid phase pipeline of the phase change separation unit, according to a preset sampling frequency. The concentration calculation module then calls the acquired flow mass matrix and executes the component mass conservation calculation logic. Specifically, it multiplies the gas phase branch flow data by the concentration coefficient of the low-boiling point component in the gas phase, adds the liquid phase branch flow data multiplied by the concentration coefficient of the low-boiling point component in the liquid phase, and then divides by the sum of the two flow data. Through the above division calculation, the numerical ratio of the combined gas phase branch flow data and the liquid phase branch flow data is obtained, generating a concentration parameter reflecting the actual physical property components of the mixed working fluid entering the heat recovery unit, and sending the concentration parameter to the circulation control module in the form of a digital signal.

[0024] The status acquisition module reads the real-time separation temperature data and real-time separation pressure data generated in the flow channel chamber of the phase change separation unit at the front end of physical operation; at the same time, the concentration calculation module has a physical property status assessment model pre-configured in the program storage medium.

[0025] To establish the data mapping architecture, the physical property state assessment model employs a multinomial regression mathematical model, which is constructed based on the gas-liquid phase equilibrium equation. The physical property state assessment model receives input data of a specific dimension, explicitly defined as a two-dimensional feature vector. This two-dimensional feature vector is combined with real-time separation temperature and pressure data to generate the output data. The output data, generated through logical operations, is defined as the concentration coefficients of low-boiling-point components in the gas phase and the liquid phase.

[0026] In the numerical calculation step, the physical property state assessment model receives two-dimensional eigenvectors and performs variable analysis, calling the activity coefficient state equation preset by the polynomial regression mathematical model. Based on the activity coefficient state equation, the physical property state assessment model calculates the phase equilibrium constant of the mixed working fluid under the current real-time separation temperature and pressure conditions; then, it combines the phase equilibrium constants and performs an algebraic solution operation to obtain the concentration coefficients of the gas phase low-boiling point components and the liquid phase low-boiling point components generated by physical separation at the outlet of the phase change separation unit.

[0027] The process involves regulating the concentration of the mixed working fluid. Specifically, the control and operation chain is as follows: The replenishment control unit within the circulation control module receives the concentration parameter input value, calls the built-in proportional-integral-differential algorithm to perform a difference calculation, and calculates the difference between the concentration parameter and a preset concentration value (e.g., a set rated concentration mass fraction of 0.45) pre-written in the memory. Based on the calculated difference, the replenishment control unit outputs a replenishment valve control command pulse signal with a change in duty cycle. This command is sent to the regulating valve actuator installed at the replenishment port of the mixing and condensing unit. By expanding or reducing the opening cross-sectional area of ​​the regulating valve, the flow rate of the external liquid source entering the mixing and condensing unit is adjusted, thereby achieving dynamic intervention and rebalancing of the total mass flow ratio of the first low-boiling-point component and the second high-boiling-point component in the pipeline circulation.

[0028] Regarding the underlying thermophysical framework of the mixed working fluid, the phase change matching mechanism of the core components is as follows: The mixed working fluid system integrates two working fluids with significantly different properties. The first low-boiling-point component uses a non-azeotropic refrigerant with high latent heat of vaporization and extremely low standard boiling point to form a highly efficient heat-absorbing carrier for the system. The second high-boiling-point component uses an organic solvent with a saturated vapor pressure at room temperature lower than a preset pressure value (e.g., lower than 0.01 MPa) as a low-volatility absorbent medium. When the miscible non-azeotropic refrigerant and organic solvent absorb heat from the external heat source in the heat exchange unit, the vaporization process no longer follows the isothermal boiling law of the pure working fluid, but exhibits a large-span temperature glide phenomenon between the bubble point temperature and the dew point temperature. It shows a state in which the phase change vaporization temperature continuously and synchronously increases as the concentration of the liquid phase component decreases, so that the heat absorption and temperature rise evolution law inside the mixed working fluid closely matches the sensible heat cooling trajectory of the external heat source liquid.

[0029] In the construction of the sensing and monitoring data link, the underlying hardware data acquisition and conversion mechanism is as follows: The sensor components installed on the power generation equipment constitute the sensing front end of the closed-loop control. The temperature sensor installed at the inlet of the heat exchange unit uses a thermistor sensitive element to sense the intensity of the thermal motion of fluid molecules flowing through its cross-section. The temperature sensor converts the measured temperature into a weak analog voltage signal, which is then processed by an analog-to-digital converter into a digital temperature signal containing temperature distribution data and real-time phase change temperature data, and transmitted to the status acquisition module. In addition, the flow sensor installed on the internal connecting pipeline of the power generation equipment uses the Coriolis mass flow measurement principle to sense the Coriolis force torsional deformation of the fluid flowing through the pipeline, and converts the collected flow rate into a standard pulse form flow signal and transmits it to the status acquisition module.

[0030] In the monitoring and feedback adjustment of the power efficiency of turbine power equipment, the calculation path of the underlying parameters is as follows: the heat exchange unit of the power generation equipment is connected to an external heat source inlet pipe, and a heat source flow control valve is connected in series on the external heat source inlet pipe. The pressure ratio calculation module extracts high-pressure data measured by the absolute pressure sensor distributed at the inlet pipe of the turbine expander in real time, and simultaneously extracts low-pressure data measured by the absolute pressure sensor distributed in the internal chamber of the mixing and condensing unit; the pressure ratio calculation module performs a mathematical division operation on the two sets of pressure values ​​to generate a pressure ratio value that reflects the available thermodynamic work capacity. When the pressure ratio value is determined to be lower than the operating set value (for example, the lower limit of the safe working pressure ratio is set to 4.5), the pressure ratio calculation module outputs an analog opening command to the heat source flow control valve installed on the external heat source inlet pipe, thereby increasing the valve core displacement to increase the inflow of external heat source and increase the total enthalpy value of the input system.

[0031] Regarding the boundary conditions of power generation equipment operating under extreme high-pressure conditions, the underlying hardware safety pressure relief logic is as follows: A bypass vent valve added within the power generation equipment is connected in parallel between the inlet pipe of the turbine expander and the condensate return pipe network. The safety pressure relief unit built into the circulation control module continuously receives and monitors high-pressure data with the highest interrupt priority. Upon detecting a critical condition where the high-pressure data exceeds the pre-programmed safety bearing limit value (e.g., a pressure limit set at 2.5 MPa), the safety pressure relief unit immediately bypasses the conventional proportional-integral-derivative (PID) control link and directly outputs a venting command in the form of the maximum drive current to the bypass vent valve's solenoid coil. The bypass vent valve is adjusted to its maximum opening, guiding the high-temperature, high-pressure gaseous fluid around the turbine rotor and directly into the low-pressure zone. This reduces the absolute pressure borne by the internal pipe network of the power generation equipment by discharging part of the mixed working fluid, preventing metal yielding and bursting damage to the mechanical structure.

[0032] The temperature difference calculation module has a preset deviation threshold of 5 degrees Celsius. This 5-degree Celsius threshold has a clear physical meaning, primarily used to balance the heat transfer driving force and irreversible thermodynamic losses between the heat exchange fluids. The circulation control module has a preset target operating range, defined as 5 to 10 degrees Celsius. Maintaining the system operating conditions within this target range ensures a stable surface heat transfer coefficient for the fluid flowing inside the heat exchange unit.

[0033] The working fluid, composed of a first low-boiling-point component and a second high-boiling-point component, is regulated by a replenishment control unit. The replenishment control unit pre-writes a preset concentration value in its memory, specifically set to a mass fraction of 0.45. This preset concentration of 0.45 promotes phase transition temperature glide matching between the first low-boiling-point component and the second high-boiling-point component. Simultaneously, the replenishment control unit monitors the lower limit of the mass fraction of the first low-boiling-point component, which is set at 0.40. If the mass fraction of the first low-boiling-point component falls below 0.40, the overall bubble point temperature of the working fluid will rise significantly. Furthermore, the saturated vapor pressure of the second high-boiling-point component at room temperature needs to be lower than a preset pressure value, set at 0.01 MPa. This preset pressure value of 0.01 MPa is used to suppress excessive volatilization of the second high-boiling-point component within the mixing and condensing unit's internal chamber.

[0034] The work capacity of the turboexpander is logically determined by the pressure ratio calculation module, which sets the operating setpoint to 4.5. Under extreme operating conditions, the pressure ratio calculation module sets a lower limit of 4.0 for the safe work pressure ratio. The underlying physical basis for the operating setpoint and the lower limit of the safe work pressure ratio depends entirely on the aerodynamic design parameters of the mechanical rotor blades inside the turboexpander. When the pressure ratio of the mixed working fluid is below 4.0, physical airflow separation will occur in the flow channels inside the turboexpander. In addition, the safety pressure relief unit pre-programs the upper limit of the safe load into the control chip, which is defined as between 2.5 MPa and 3.0 MPa. The calculation of the upper limit of the safe load is based on the physical parameters of the yield strength of the metal pipelines arranged inside the power generation equipment.

[0035] The lightweight model sets clear numerical accuracy boundaries during the data network training phase. The absolute value of the loss function must be lower than a pre-set convergence threshold of 0.001. This constraint of a pre-set convergence threshold of 0.001 ensures that the exothermic reference curve matrix output by the lightweight model achieves the numerical accuracy required for engineering prediction calculations.

[0036] The temperature difference comparison unit performs node difference calculation at the preset coordinate node position, and the formula called is the temperature deviation calculation formula.

[0037] The formula for calculating temperature deviation is:

[0038] In the formula for calculating temperature deviation, This represents the temperature deviation value at the preset coordinate node position; This represents the reference temperature value at the preset coordinate node position of the exothermic reference curve matrix; This represents the phase transition temperature value of the real-time phase transition temperature data array at the preset coordinate node position. Substituting the reference temperature value of 90 degrees Celsius and the phase transition temperature value of 70 degrees Celsius into the temperature deviation calculation formula, the temperature deviation value is found to be 20 degrees Celsius. The cyclic control module determines that the temperature deviation value of 20 degrees Celsius is greater than the preset deviation threshold of 5 degrees Celsius, and the signal triggering unit switches from a low level to a high level trigger signal and sends it to the cyclic control module. The concentration calculation module executes the component mass conservation calculation logic and calls the formula for calculating the concentration parameter.

[0039] The formula for calculating the concentration parameter is:

[0040] In the formula for calculating concentration parameters, This parameter represents the concentration of the mixed working fluid entering the heat recovery unit. Gas phase branch flow rate data representing the gas phase branch discharged from the phase change separation unit; concentration coefficient of low-boiling-point gas phase components contained in the gas phase branch; Liquid phase branch flow rate data representing the liquid phase branch discharged from the phase change separation unit; This represents the concentration coefficient of the low-boiling-point component in the liquid phase branch. Substituting the gas phase branch flow rate data of 20 kg / s, the low-boiling-point component concentration coefficient of 90%, the liquid phase branch flow rate data of 30 kg / s, and the low-boiling-point component concentration coefficient of 15% into the concentration parameter calculation formula, the resulting concentration parameter is 45%. The replenishment control unit compares the 45% concentration parameter with the lower limit setting value of 40% and determines that the concentration parameter is not lower than the lower limit setting value. The physical property state assessment model calls the activity coefficient state equation to calculate the phase equilibrium constant using the same formula as the phase equilibrium constant calculation formula.

[0041] The formula for calculating the phase equilibrium constant is:

[0042] In the formula for calculating the phase equilibrium constant, This represents the phase equilibrium constant of the mixed working fluid under the current real-time separation temperature and pressure conditions. This represents the saturated vapor pressure of the mixed working fluid at the real-time separation temperature. The liquid phase activity coefficient represents the mixed working fluid under real-time separation temperature and real-time separation pressure conditions; This represents the real-time separation pressure data of the mixed working fluid. Substituting the saturated vapor pressure of 0.5 MPa, the liquid phase activity coefficient of 1.2, and the real-time separation pressure of 0.6 MPa into the phase equilibrium constant calculation formula, the phase equilibrium constant is found to be 1.0. Based on the phase equilibrium constant of 1.0, the physical property assessment model calculates the concentration coefficients of the low-boiling-point components in the gas phase and liquid phase generated by physical separation at the outlet of the phase change separation unit. The pressure ratio calculation module performs mathematical division on the high-pressure and low-pressure data, calling the pressure ratio calculation formula.

[0043] The formula for calculating the pressure ratio is:

[0044] In the formula for calculating pressure ratio, The pressure ratio represents the pressure ratio that reflects the work capacity of a turbine expander; This represents the high-pressure data at the inlet pipe of the turboexpander; This represents the low-pressure data inside the mixing and condensing unit. Substituting the high-pressure data of 2.0 MPa and the low-pressure data of 0.4 MPa into the pressure ratio calculation formula, the pressure ratio value is 5.0. The pressure ratio calculation module determines that the pressure ratio value of 5.0 is greater than the operating set value of 4.5, and stops outputting analog opening commands to the heat source flow control valve on the external heat source inlet pipe.

[0045] As a further extension of the technical solution of the present invention, the following is a specific embodiment focusing on the application scenario of high-temperature wastewater waste heat recovery in steel plants: In the application scenario of high-temperature wastewater waste heat recovery in steel plants, the external heat source is industrial wastewater fluid with a continuously decreasing temperature. After the heat exchange unit of the power generation equipment is connected to the aforementioned industrial wastewater fluid, the status acquisition module continuously acquires temperature distribution data through temperature sensors. This temperature distribution data specifically includes the initial high temperature value at the inlet of the industrial wastewater fluid entering the heat exchange unit, multiple transitional cooling values ​​as it flows through the middle channel of the heat exchange unit, and the final low temperature value at the outlet of the heat exchange unit. Simultaneously, the status acquisition module acquires real-time phase change temperature data of the mixed working fluid within the heat exchange unit. This real-time phase change temperature data specifically includes the bubble point temperature value when the mixed working fluid begins to boil, the dew point temperature value when it completely transforms into a vapor state, and discrete node temperature values ​​during the gas-liquid two-phase coexistence stage. Subsequently, the temperature difference calculation module reads the temperature distribution data sequence of the industrial wastewater fluid and the real-time phase change temperature data array of the mixed working fluid, and performs a one-to-one node subtraction operation on the two data arrays in the same spatial coordinate system. The calculation result generates heat transfer temperature difference data, which visually reflects the actual heat transfer gradient between fluids at different spatial locations within the heat exchange unit.

[0046] The circulation control module receives the aforementioned heat exchange temperature difference data and extracts each set of temperature deviation values ​​within the data to perform boundary judgment. Taking a set heat exchange node as an example, if the industrial wastewater fluid temperature is 90 degrees Celsius and the phase change temperature of the mixed working fluid at the corresponding node is 70 degrees Celsius, the difference between the two yields a temperature deviation value of 20 degrees Celsius. The circulation control module then determines that the 20-degree Celsius temperature deviation value exceeds the preset target operating range of 5 to 10 degrees Celsius. After recognizing the objective state that the temperature deviation value exceeds the target operating range, the circulation control module outputs a flow regulation command to the pressurized pumping unit to increase the electrical frequency. The variable frequency motor inside the pressurized pumping unit increases the rotor speed based on the command, thereby increasing the circulating volume flow rate of the mixed working fluid inside the power generation equipment; by increasing the flow velocity of the medium, the heat exchange is enhanced, making the heat absorption temperature curve of the mixed working fluid closer to the heat release reference curve of the industrial wastewater fluid, thereby reducing local irreversible heat transfer losses.

[0047] The phase change separation unit separates the partially vaporized mixed working fluid into a gas phase branch and a liquid phase branch. Subsequently, the status acquisition module extracts the flow rate data of the gas phase branch and the liquid phase branch discharged from the phase change separation unit. The gas phase branch flow rate data specifically represents the instantaneous mass flow rate of the gaseous fluid rich in the first low-boiling-point component, while the liquid phase branch flow rate data represents the instantaneous mass flow rate of the liquid fluid rich in the second high-boiling-point component. The concentration calculation module retrieves the two mass flow rate values ​​and performs mathematical proportional conversion to calculate the comprehensive mass fraction ratio of the mixed working fluid entering the heat recovery unit, thereby generating a concentration parameter. After the above concentration parameter is input to the liquid replenishment control unit in the circulation control module, the liquid replenishment control unit compares the input concentration parameter with the system's rated ratio value. When the input concentration parameter shows that the mass fraction of the low-boiling-point component is lower than the lower limit setting value of 40%, the liquid replenishment control unit outputs a liquid replenishment valve control command to the regulating valve installed at the liquid replenishment port of the mixing and condensing unit to change the duty cycle. After receiving the command, the valve core of the regulating valve generates a linear displacement to expand the opening cross-sectional area, introduces the first low-boiling-point component liquid from the external reserve, and finally dynamically reconstructs the original mass flow ratio of the mixed working fluid at the pipeline network level.

[0048] A gas-phase branch connects to the turbine expander, converting thermal energy into mechanical energy and driving a generator to output electrical energy. During operation, the pressure ratio calculation module acquires high-pressure data at the turbine expander's inlet pipe and low-pressure data inside the mixing and condensing unit. The high-pressure data specifically reflects the absolute pressure scale of the high-temperature, high-pressure steam entering the turbine expander, while the low-pressure data specifically reflects the back pressure scale during the exhaust steam condensation stage within the mixing and condensing unit. The pressure ratio calculation module divides the high-pressure data by the low-pressure data to obtain a pressure ratio value reflecting the work capacity. When the pressure ratio value drops below 4.0, the pressure ratio calculation module outputs an analog opening command to the heat source flow control valve on the external heat source inlet pipe. The heat source flow control valve then increases the mass flow rate of the industrial wastewater, increasing the heat energy supply to the power generation equipment. When the industrial wastewater flow rate surges, causing the high-pressure data to exceed the 3.0 MPa load limit setting, the safety pressure relief unit built into the circulation control module executes a coordinated pressure relief program; the safety pressure relief unit outputs a discharge command to the bypass vent valve connected to the turbine expander's inlet pipe. The bypass vent valve opens the bypass pressure relief channel, directly introducing the overloaded gas phase branch into the mixing and condensing unit, thereby quickly releasing the absolute pressure accumulated inside the power generation equipment and preventing metal bursting damage to the mechanical structure.

[0049] Secondly, the present invention provides an application of the Karina cycle power generation system based on ORC working fluid pairs, wherein the application is as follows: waste liquid or waste gas with a temperature gradient is introduced into the heat exchange unit as the external heat source, and the turbine expander outputs electrical energy.

[0050] This embodiment provides a specific application scenario for a Karina cycle power generation system based on an ORC working fluid pair, in which exhaust gas with a temperature gradient is introduced into the heat exchange unit of the power generation equipment as an external heat source. The power generation equipment circulates a mixed working fluid composed of a first low-boiling-point component (e.g., a non-azeotropic refrigerant) and a second high-boiling-point component (e.g., an organic solvent with a saturated vapor pressure below a preset pressure value at room temperature).

[0051] During the initial heat transfer and monitoring phase of system operation, chemical waste gas enters the heat exchange unit to heat the mixed working fluid. The status acquisition module in the control device acquires the temperature distribution data of the external heat source through a temperature sensor installed at the inlet of the heat exchange unit, and simultaneously acquires the real-time phase change temperature data of the mixed working fluid within the heat exchange unit. The curve mapping unit in the temperature difference calculation module retrieves the aforementioned temperature distribution data and maps it according to preset coordinate node positions to generate a heat release reference curve. Subsequently, the temperature difference comparison unit retrieves the real-time phase change temperature data and compares it with the heat release reference curve at preset coordinate node positions to calculate the temperature deviation value at the preset coordinate node positions, thereby generating heat transfer temperature difference data.

[0052] During the dynamic matching and control phase of the thermodynamic cycle, when the signal triggering unit detects a temperature deviation exceeding a preset deviation threshold in the heat exchange temperature difference data, it outputs a trigger signal to the cycle control module. The cycle control module then outputs a flow regulation command to the pressurized pumping unit, adjusting its operating frequency to change the circulation velocity of the mixed working fluid within the power generation equipment. This dynamic control ensures that the non-azeotropic refrigerant and organic solvent exhibit a continuous change in phase change vaporization temperature with liquid concentration within the heat exchange unit, resulting in a heat absorption temperature curve of the mixed working fluid closely matching the exothermic reference curve of the chemical waste gas.

[0053] In the gas-liquid separation and internal heat recovery stage, the heated mixed working fluid enters the phase change separation unit, where it is separated into a gas phase branch and a liquid phase branch. The heat recovery unit installed in the power generation equipment guides the liquid phase branch to the exothermic side to release heat, while simultaneously guiding the subcooled liquid fluid output by the pressurized pumping unit to the absorbent side to absorb the heat released by the liquid phase branch. After completion, the liquid fluid enters the heat exchange unit, while the liquid phase branch is transported to the mixing and condensation unit.

[0054] During the working fluid concentration calculation and proportioning balance stage, the status acquisition module extracts the gas phase branch flow data and liquid phase branch flow data discharged from the phase change separation unit through flow sensors installed on the internal connecting pipeline of the power generation equipment. The concentration calculation module retrieves the above two flow data and calculates their numerical ratio to generate a concentration parameter reflecting the real-time state of the mixed working fluid, and sends this concentration parameter to the circulation control module. The liquid replenishment control unit in the circulation control module calculates the difference between this concentration parameter and the preset concentration value, and outputs a liquid replenishment valve control command to the regulating valve installed at the liquid replenishment port of the mixing and condensing unit based on the difference data; by changing the opening of the regulating valve, the system realizes the physical adjustment of the mass flow ratio of the first low-boiling-point component and the second high-boiling-point component.

[0055] During the turbine power generation and extreme condition safety protection phases, the gas-phase branch connects to the turbine expander to convert thermal energy into mechanical energy and output electrical energy. The exhaust steam and the cooled liquid-phase branch converge and condense into a liquid fluid in the mixing and condensation unit. During operation, the pressure ratio calculation module of the control device acquires real-time high-pressure data at the turbine expander inlet pipe and low-pressure data inside the mixing and condensation unit, calculating the ratio to generate a pressure ratio value. When the pressure ratio value is lower than the operating set value, the pressure ratio calculation module outputs an opening command to the heat source flow control valve on the external heat source inlet pipe, increasing the inflow of chemical waste gas to enhance heat source supply. Conversely, when the high-pressure data exceeds the safe bearing limit due to heat source fluctuations or other factors, the safety pressure relief unit built into the circulation control module immediately intervenes, outputting a discharge command to the bypass exhaust valve connected to the turbine expander inlet pipe, discharging part of the mixed working fluid to reduce the absolute pressure inside the power generation equipment and prevent overpressure damage to the mechanical structure.

Claims

1. A Kalina cycle power generation system based on ORC working pairs, characterized in that, Includes power generation equipment and control devices that establish a communication connection with the power generation equipment; The power generation equipment circulates a mixed working fluid composed of a first low-boiling-point component and a second high-boiling-point component. The power generation equipment includes a heat exchange unit, a phase change separation unit, a turbine expander, a mixing and condensing unit, and a pressurized pumping unit connected in sequence. The heat exchange unit introduces an external heat source to heat the mixed working fluid. The phase change separation unit separates the heated mixed working fluid into a gas phase branch and a liquid phase branch. The gas phase branch is connected to the turbine expander to convert heat energy into electrical energy. The liquid phase branch and the exhaust steam from the turbine expander are transported to the mixing and condensing unit, where they collect and condense into a liquid fluid. The pressurized pumping unit repressurizes the liquid fluid and transports it back to the heat exchange unit. The control device includes a status acquisition module, a temperature difference calculation module, and a cycle control module; The status acquisition module acquires the temperature distribution data of the external heat source and the real-time phase change temperature data of the mixed working fluid in the heat exchange unit; The temperature difference calculation module retrieves the temperature distribution data and the real-time phase change temperature data for numerical comparison, and generates heat transfer temperature difference data including temperature deviation values. The circulation control module receives the heat exchange temperature difference data. When the temperature deviation value in the heat exchange temperature difference data exceeds the preset value range, it outputs a flow rate adjustment command to the pressurized pumping unit to adjust the circulation rate of the mixed working fluid in the power generation equipment.

2. The ORC working fluid pair based Kalina cycle power generation system according to claim 1, characterized in that, The temperature difference calculation module includes: The curve mapping unit retrieves the temperature distribution data and maps the temperature distribution data according to the preset coordinate node positions to generate a heat release reference curve. The temperature difference comparison unit retrieves the real-time phase change temperature data and compares it with the heat release reference curve at the preset coordinate node position, calculates the temperature deviation value at the preset coordinate node position, and generates the heat exchange temperature difference data. The signal triggering unit extracts the temperature deviation value from the heat exchange temperature difference data, and outputs a trigger signal to the circulation control module when the temperature deviation value is greater than a preset deviation threshold, instructing the circulation control module to output the flow rate adjustment command.

3. The Karina cycle power generation system based on ORC working fluid pairs according to claim 2, characterized in that, The power generation equipment also includes a heat recovery unit; the heat recovery unit is connected between the outlet of the pressurized pumping unit, the inlet of the heat exchange unit, the liquid phase outlet of the phase change separation unit, and the inlet of the mixing and condensing unit; the heat recovery unit guides the liquid phase branch to release heat, and guides the liquid fluid output by the pressurized pumping unit to absorb the heat released by the liquid phase branch.

4. The Karina cycle power generation system based on ORC working fluid pairs according to claim 3, characterized in that, The status acquisition module extracts the gas phase branch flow rate data and the liquid phase branch flow rate data of the gas phase branch discharged from the phase change separation unit; the control device further includes a concentration calculation module, which retrieves the gas phase branch flow rate data and the liquid phase branch flow rate data, calculates the numerical ratio between the gas phase branch flow rate data and the liquid phase branch flow rate data, generates the concentration parameter of the mixed working fluid entering the heat recovery unit, and sends the concentration parameter to the circulation control module.

5. The Karina cycle power generation system based on ORC working fluid pairs according to claim 4, characterized in that, The circulation control module includes a liquid replenishment control unit, and the mixing and condensing unit is provided with a liquid replenishment port, which is equipped with a regulating valve. The liquid replenishment control unit receives the concentration parameter and calculates the difference between the concentration parameter and the preset concentration value, and outputs a liquid replenishment valve control command based on the difference data. The liquid replenishment valve control command is sent to the regulating valve, and the mass flow ratio of the first low-boiling-point component and the second high-boiling-point component is adjusted by changing the opening degree of the regulating valve.

6. The Karina cycle power generation system based on ORC working fluid pairs according to claim 5, characterized in that, The first low-boiling-point component includes a non-azeotropic refrigerant, and the second high-boiling-point component includes an organic solvent. The saturated vapor pressure of the organic solvent at room temperature is lower than a preset pressure value. The non-azeotropic refrigerant and the organic solvent are in a state where the phase change vaporization temperature changes continuously with the liquid phase concentration within the heat exchange unit.

7. The Karina cycle power generation system based on ORC working fluid pairs according to claim 6, characterized in that, The power generation equipment includes a sensor assembly; the sensor assembly includes a temperature sensor installed at the inlet of the heat exchange unit and a flow sensor installed on the internal connecting pipe of the power generation equipment; the temperature sensor collects temperature data and converts it into a temperature signal including the temperature distribution data and the real-time phase change temperature data, and sends it to the status acquisition module; the flow sensor collects flow rate data and converts it into a flow rate signal, and sends it to the status acquisition module.

8. The Karina cycle power generation system based on ORC working fluid pairs according to claim 7, characterized in that, The heat exchange unit is connected to an external heat source inlet pipe, and a heat source flow control valve is installed on the external heat source inlet pipe; the turbine expander has an inlet pipe, and the control device further includes a pressure ratio calculation module. The pressure ratio calculation module acquires the high-pressure data at the inlet pipe of the turbine expander and the low-pressure data inside the mixing and condensing unit, and calculates the ratio of the high-pressure data to the low-pressure data to generate a pressure ratio value; when the pressure ratio value is lower than the operating set value, the pressure ratio calculation module outputs an opening command to the heat source flow control valve to increase the inflow of the external heat source.

9. The Karina cycle power generation system based on ORC working fluid pairs according to claim 8, characterized in that, The power generation equipment also includes a bypass vent valve, which is connected to the inlet pipe of the turbine expander; the circulation control module has a built-in safety pressure relief unit, which receives the high pressure data and outputs a venting command to the bypass vent valve when the high pressure data exceeds the upper limit of the safety bearing capacity, thereby discharging part of the mixed working fluid to reduce the absolute pressure inside the power generation equipment.

10. An application of the Karina cycle power generation system based on ORC working fluid pairs as described in any one of claims 1 to 9, characterized in that, The application is as follows: waste liquid or waste gas with a temperature gradient is introduced into the heat exchange unit as the external heat source, and electrical energy is output by the turbine expander.

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