A direct air-cooling unit cold end comprehensive performance improvement system

Abstract

The embodiment of the disclosure provides a kind of direct air cooling unit cold end comprehensive performance promotion system, including the output of measuring point arrangement module and the input of multichannel data acquisition and transmission module are connected, the output of multichannel data acquisition and transmission module is respectively connected with the input of air cooling unit finned tube bundle heat exchange calculation module, air cooling condenser overall pressure calculation module, the input of air cooling unit finned tube bundle heat exchange calculation module, air cooling condenser overall pressure calculation module is connected with the input of cold end operating state intelligent analysis module, the input of DCS integrated display and interactive module is connected with the output of cold end operating state intelligent analysis module.There is advantage in realizing the multi-form integrated display of cold end operating data, abnormal state real-time sound-light early warning and closed-loop interaction of control instruction.

Description

Technical Field

[0001] The embodiments disclosed herein belong to the technical field of cold-end operation of direct air-cooled thermal power units, specifically relating to a comprehensive performance improvement system for the cold end of a direct air-cooled unit. Background Technology

[0002] Direct air cooling technology, with its significant water-saving advantages, has been widely applied in thermal power plants in coal-rich but water-scarce regions of northern China, becoming the mainstream cooling technology for newly built units in the area. The direct air cooling system uses an axial flow fan to force ambient air onto the surface of the finned tube bundle, where it exchanges heat with the turbine exhaust steam inside the tubes, causing the exhaust steam to condense into water, thus maintaining the vacuum state of the condenser. However, the cooling capacity of the direct air cooling system is affected by a combination of factors, including ambient temperature, wind speed, wind direction, solar radiation, and unit operating conditions, resulting in extremely complex operating characteristics and posing a significant challenge to the safe and economical operation of the unit. Summary of the Invention

[0003] The embodiments disclosed herein aim to at least solve one of the technical problems existing in the prior art, and provide a system for improving the overall performance of the cold end of a direct air-cooled unit.

[0004] The embodiments of this disclosure provide a system for improving the overall performance of the cold end of a direct air-cooled unit, including a measuring point layout module, a multi-channel data acquisition and transmission module, an air-cooled unit finned tube bundle heat exchange calculation module, an air-cooled condenser overall pressure calculation module, a cold end operating status intelligent analysis module, and a DCS integrated display and interaction module. The output of the measuring point layout module is connected to the input of the multi-channel data acquisition and transmission module. The output of the multi-channel data acquisition and transmission module is connected to the input of the air-cooled unit finned tube bundle heat transfer calculation module and the air-cooled condenser overall pressure calculation module, respectively. The outputs of the air-cooled unit finned tube bundle heat transfer calculation module and the air-cooled condenser overall pressure calculation module are both connected to the input of the cold end operation status intelligent analysis module. The output of the cold end operation status intelligent analysis module is connected to the input of the DCS integrated display and interaction module.

[0005] Optionally, the measuring point arrangement module includes inlet air temperature measuring point, outlet air temperature measuring point, heat dissipation tube bundle wall temperature measuring point, condensate temperature measuring point and condensate pressure measuring point respectively set in each air-cooled unit. The inlet air temperature measuring point is located at the center of the air inlet side of the air-cooled unit, the outlet air temperature measuring point is located at the four corners and the center of the air outlet side of the air-cooled unit, the heat dissipation tube bundle wall temperature measuring point is evenly distributed on the surface of the co-current and counter-current tube bundles of the air-cooled unit, and the condensate temperature measuring point and condensate pressure measuring point are located at the condensate lower header of each air-cooled unit.

[0006] Optionally, the multi-channel data acquisition and transmission module includes an analog input unit, a data preprocessing unit, a real-time transmission unit, and a data storage unit; The analog input unit receives the analog signals from each measuring point output by the measuring point layout module, converts them into digital signals, and transmits them to the data preprocessing unit. The data preprocessing unit filters, denoises, and performs range conversion on the digital signals to generate standardized operating parameter data. The real-time transmission unit transmits the standardized operating parameter data to the air-cooled unit finned tube bundle heat exchange calculation module and the air-cooled condenser overall pressure calculation module, respectively. The data storage unit stores all collected and processed operating parameter data in a time-series format.

[0007] Optionally, the heat transfer calculation module for the air-cooled unit finned tube bundle is built based on the heat balance principle that the heat released by the steam inside the finned tube is equal to the heat absorbed by the air outside the tube. Its calculation process includes the calculation of the main condensate volume, the calculation of the dynamic steam condensation volume, and the calculation of the air outlet temperature. The main condensate volume is calculated using the following formula: (1) (2) (3) (4) In the formula: Main condensate volume; This represents the total steam flow rate inside the finned tube. This refers to the dynamic condensation rate of steam. The heat released by the steam inside the finned tube; For convective heat transfer; The overall heat transfer coefficient; This refers to the heat exchange area of ​​the cooling unit; This refers to the enthalpy of vapor. This refers to the enthalpy of condensate. The temperature difference is the logarithmic mean.

[0008] Optionally, the logarithmic mean temperature difference is calculated using the mean temperature difference calculation method for mixed flow, and is calculated by the following formula: (5) In the formula: This is a correction factor for mixed flow; This represents the maximum temperature difference between the fluids inside and outside the finned tube. This represents the minimum temperature difference between the fluids inside and outside the finned tube. The dynamic condensation rate of steam is calculated using the following formula: (6) In the formula: The dynamic condensation coefficient; The saturated steam temperature corresponding to the pressure of the air condenser; The saturated water temperature corresponding to the pressure of the air condenser.

[0009] Optionally, the air outlet temperature is calculated based on the principle of conservation of heat transfer between the fluids inside and outside the finned tube, and the heat transfer equation for the air outside the finned tube is: (7) In the formula: It absorbs heat from the air; Air mass flow rate; The specific heat capacity of air at constant pressure; This refers to the inlet air temperature of the cooling unit. This refers to the outlet air temperature of the cooling unit. The windward area of ​​a single finned tube; The unit's frontal wind speed; The density of air in the external environment; The conservation equation for heat transfer between the fluids inside and outside the finned tube is: (8) In the formula: The mass of the fluid inside the finned tube; This represents the enthalpy of the fluid inside the finned tube. For time; The mass flow rate of steam entering the finned tube; The enthalpy of the vapor entering the finned tube; The mass flow rate of the fluid exiting the finned tube; The enthalpy of the fluid flowing out of the finned tube; The heat released by the steam is: (9) The amount of heat absorbed by the air is: (10) The dynamic calculation equation for the air outlet temperature of the air-cooled unit is as follows: (11) In the formula: for The air temperature at the outlet of the air-cooled unit at all times; To calculate the time step; The mass of the inertial link of air.

[0010] Optionally, the overall pressure calculation module of the air-cooled condenser is constructed based on the ideal gas law, and its calculation process includes steam inventory calculation, steam partial pressure calculation, air inventory calculation, air partial pressure calculation, and condenser total pressure calculation; the steam inventory inside the air-cooled condenser is calculated using the following formula: (12) The steam inlet flow rate to the air-cooled condenser is as follows: (13) In the formula: The amount of steam stored inside the air-cooled condenser; The steam inlet flow rate to the air condenser; Steam outflow from the air condenser; This refers to the steam turbine exhaust volume; The dynamic evaporation rate of condensate; the saturated water temperature under the steam partial pressure in the air-cooled condenser. The temperature is lower than that in the water collection tank. hour, , The dynamic evaporation coefficient of steam; The steam outflow rate of the air-cooled condenser is: (14) In the formula: This represents the total steam condensation rate of all air-cooled units. The steam flow rate extracted by the water ring vacuum pump; Vapor partial pressure is calculated using the following formula: (15) In the formula: for Vapor partial pressure at any given time; for Vapor partial pressure at any given time; The average gas constant of the vapor; The thermodynamic temperature of steam; This represents the total volume of the condenser.

[0011] Optionally, the air partial pressure is calculated using the following formula: (16) In the formula: for The partial pressure of air at any given moment; for The partial pressure of air at any given moment; The amount of non-condensable gas in the condenser is calculated using the following formula: (17) (18) In the formula: The amount of non-condensable gas remaining in the condenser; This is the net inflow of non-condensable gases into the condenser. This refers to the amount of air leaking into the vacuum breaker valve. This is normal leakage rate; This refers to the leakage rate of the shaft seal. This represents the amount of air leakage due to the fault. This refers to the steam extraction rate of the vacuum pump. This represents the percentage of air mass inside the condenser. The total pressure of the condenser is equal to the sum of the partial pressure of steam and the partial pressure of air, and is calculated using the following formula: (19) In the formula: This is the condenser full pressure.

[0012] Optionally, the intelligent analysis module for cold end operating status includes an online cooling capacity assessment unit, a back pressure operating deviation analysis unit, a heat dissipation pipe wall temperature distribution analysis unit, and a quantitative assessment unit for equipment cleanliness. The online cooling capacity evaluation unit is based on the overall heat transfer coefficient output by the air-cooled unit finned tube bundle heat transfer calculation module. The total condenser pressure output by the air-cooled condenser overall pressure calculation module The real-time cooling capacity of each air-cooled unit and the entire air-cooled island is calculated; the back pressure operation deviation analysis unit will calculate the total condenser pressure. Compare the back pressure value with the design back pressure value to analyze the causes of back pressure operation deviation; The heat dissipation pipe wall temperature distribution analysis unit generates a wall temperature distribution cloud map of the entire air-cooled island based on data from the wall temperature measurement points of each heat dissipation pipe bundle, identifying localized areas of abnormal temperature; the equipment cleanliness status quantitative assessment unit is based on the overall heat transfer coefficient. By analyzing the changing trends and combining environmental parameters with operating conditions, the degree of fouling of finned tubes can be quantitatively assessed.

[0013] Optionally, the DCS integrated display and interaction module includes a data visualization display unit, an anomaly warning unit, and a control command interaction unit; The data visualization display unit integrates and displays the cooling capacity, back pressure deviation, wall temperature distribution, and cleanliness data output by the cold end operation status intelligent analysis module in the form of numerical values, curves, and cloud maps on the DCS control screen; the abnormality early warning unit issues an audible and visual early warning signal when it detects that the back pressure deviation exceeds the set threshold, the local wall temperature is lower than the antifreeze threshold, or the equipment cleanliness is lower than the set level; the control command interaction unit receives parameter adjustment commands issued by the operators through the DCS and transmits them to the unit control system, while receiving feedback signals from the unit control system to realize closed-loop interaction between monitoring and control.

[0014] The direct air-cooled unit cold-end comprehensive performance improvement system of the embodiments of this disclosure has the following beneficial effects: By scientifically configuring key measuring points such as inlet air temperature, outlet air temperature, heat dissipation tube bundle wall temperature, condensate temperature, and condensate pressure in each air-cooled unit, a high-density multi-parameter monitoring network covering the entire air-cooled island is constructed. This solves the problems of insufficient measuring point coverage and the inability to reflect unit-level operational differences in existing monitoring systems, enabling comprehensive and accurate acquisition of the actual operating status of each air-cooled unit.

[0015] Based on the principle of heat balance and the ideal gas law, a heat transfer calculation model for the finned tube bundle of an air-cooled unit considering dynamic condensation and air inertia effects, and an overall pressure calculation model for the air-cooled condenser considering the influence of non-condensable gases, were constructed. Compared with traditional steady-state calculation models, the calculation models disclosed herein can accurately reflect the heat transfer process and pressure changes under dynamic operating conditions, significantly improving calculation accuracy and providing a reliable data foundation for in-depth optimization control of the cold-end system.

[0016] The intelligent analysis module for cold-end operation status can assess the cooling capacity of each air-cooled unit and the entire air-cooled island online, accurately analyze the causes of back pressure operation deviations, monitor the wall temperature distribution of the heat dissipation tube bundle in real time, and quantitatively assess the degree of fouling of the finned tubes. These analytical results provide operators with comprehensive and scientific decision support, enabling them to shift from traditional experience-based operations to data-driven, refined operations.

[0017] Through the DCS integration display and interaction module, all monitoring data and analysis results are seamlessly integrated into the unit's existing DCS control screen, allowing operators to fully grasp the operating status of the cold end system without switching systems. Simultaneously, this module also achieves closed-loop interaction with the unit's control system, receiving control commands from operators and providing feedback on their execution, laying the foundation for future fully automated optimized control of the cold end system. Attached Figure Description

[0018] Figure 1 This is a system module diagram of a direct air-cooled unit cold-end comprehensive performance improvement system according to an embodiment of the present disclosure; Figure 2 This is a schematic diagram of a measuring point arrangement module according to another embodiment of the present disclosure; Figure 3 This is a schematic diagram of a multi-channel data acquisition and transmission module according to another embodiment of the present disclosure; Figure 4 This is a schematic diagram of a monitoring scheme for the equipment status of an air-cooled island unit according to another embodiment of this disclosure. Detailed Implementation

[0019] To enable those skilled in the art to better understand the technical solutions of this disclosure, the disclosure will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0020] Currently, cold-end monitoring systems for direct air-cooled units in related technologies generally suffer from a severe shortage of measuring points and extremely limited monitoring range. Traditional monitoring systems only set temperature and pressure measuring points at a few global locations such as the condensate header, vacuum header, and the main air inlet of the air-cooled island, completely neglecting to configure measuring points for each individual air-cooled unit. This extensive monitoring mode makes it impossible for operators to obtain the actual operating parameters of each air-cooled unit, making it difficult to accurately assess the differences in heat exchange performance between different units. They can only rely on personal experience to uniformly adjust the entire fan group of the air-cooled island, failing to achieve fine-grained zonal control.

[0021] The limitations of the existing monitoring system directly lead to a series of operational problems: First, during the high-temperature period in summer, because it is impossible to identify units with poor heat exchange performance, operators can only reduce the unit's back pressure by increasing the speed of all fans, resulting in a significant increase in fan power consumption, with the air-cooled power consumption rate even reaching over 1.5%, severely reducing the unit's operational economy. Second, during low-temperature operation in winter, relying solely on the temperature of the condensate header for antifreeze protection fails to detect localized overcooling of the tube bundles in time, frequently leading to freezing of the heat dissipation tube bundles. In severe cases, this can even cause tube bundle rupture, vacuum system leaks, and other serious accidents, threatening the safe and stable operation of the unit. Third, due to the lack of real-time calculation of the heat transfer coefficient of each unit, it is impossible to accurately quantify the impact of dust and dirt accumulation on the finned tube surface on cooling capacity, resulting in extremely unreasonable timing of cleaning. Either cleaning is not timely, causing a continuous decline in heat exchange efficiency, or cleaning is too frequent, resulting in a huge waste of water and electricity. Furthermore, existing monitoring systems cannot provide comprehensive and accurate unit-level data support for cold-end optimization control, making it difficult to effectively implement advanced control strategies such as optimal back pressure automatic adjustment and intelligent zone antifreeze, thus limiting further improvement in the operating performance of direct air-cooled units.

[0022] In view of this, please refer to Figures 1 to 4 To address the aforementioned technical problems, the inventors proposed a system for improving the overall cold-end performance of a direct air-cooled unit. This system includes a measuring point layout module, a multi-channel data acquisition and transmission module, an air-cooled unit finned tube bundle heat exchange calculation module, an air-cooled condenser overall pressure calculation module, a cold-end operating status intelligent analysis module, and a DCS integrated display and interaction module. The output of the measuring point layout module is connected to the input of the multi-channel data acquisition and transmission module. The output of the multi-channel data acquisition and transmission module is connected to the inputs of both the air-cooled unit finned tube bundle heat exchange calculation module and the air-cooled condenser overall pressure calculation module. The outputs of both modules are connected to the input of the cold-end operating status intelligent analysis module, and the output of this module is connected to the input of the DCS integrated display and interaction module.

[0023] Specifically, the measuring point arrangement module includes inlet air temperature measuring points, outlet air temperature measuring points, heat dissipation tube bundle wall temperature measuring points, condensate temperature measuring points, and condensate pressure measuring points respectively set in each air-cooled unit; the inlet air temperature measuring point is arranged at the center of the air-cooled unit's air inlet side, the outlet air temperature measuring point is arranged at the four corners and the center of the air-cooled unit's air outlet side, the heat dissipation tube bundle wall temperature measuring points are evenly arranged on the surfaces of the co-current and counter-current tube bundles of the air-cooled unit, and the condensate temperature measuring point and condensate pressure measuring point are arranged at the condensate lower header of each air-cooled unit (specifically, they can be arranged in the middle of the condensate lower header).

[0024] The multi-channel data acquisition and transmission module includes an analog input unit, a data preprocessing unit, a real-time transmission unit, and a data storage unit. The analog input unit receives analog signals from each measuring point output by the measuring point layout module, converts them into digital signals, and transmits them to the data preprocessing unit. The data preprocessing unit filters, denoises, and performs range conversion on the digital signals to generate standardized operating parameter data. The real-time transmission unit transmits the standardized operating parameter data to the air-cooled unit finned tube bundle heat exchange calculation module and the air-cooled condenser overall pressure calculation module, respectively. The data storage unit stores all acquired and processed operating parameter data in a time-series format.

[0025] The heat transfer calculation module for the air-cooled unit's finned tube bundle is built upon the heat balance principle that the heat released by the steam inside the finned tubes is equal to the heat absorbed by the air outside the tubes. Its calculation process includes calculating the main condensate volume, the dynamic steam condensation rate, and the air outlet temperature. The main condensate volume is calculated using the following formula: (1) (2) (3) (4) In the formula: Main condensate volume; This represents the total steam flow rate inside the finned tube. This refers to the dynamic condensation rate of steam. The heat released by the steam inside the finned tube; For convective heat transfer; The overall heat transfer coefficient; This refers to the heat exchange area of ​​the cooling unit; This refers to the enthalpy of vapor. This refers to the enthalpy of condensate. The temperature difference is the logarithmic mean.

[0026] Furthermore, the logarithmic mean temperature difference is calculated using the mean temperature difference calculation method for mixed flow, through the following formula: (5) In the formula: This is a correction factor for mixed flow; This represents the maximum temperature difference between the fluids inside and outside the finned tube. This represents the minimum temperature difference between the fluids inside and outside the finned tube. The dynamic condensation rate of steam is calculated using the following formula: (6) In the formula: The dynamic condensation coefficient; The saturated steam temperature corresponding to the pressure of the air condenser; The saturated water temperature corresponding to the pressure of the air condenser.

[0027] The air outlet temperature is calculated based on the principle of conservation of heat transfer between the fluids inside and outside the finned tube. The heat transfer equation for the air outside the finned tube is as follows: (7) In the formula: It absorbs heat from the air; Air mass flow rate; The specific heat capacity of air at constant pressure; This refers to the inlet air temperature of the cooling unit. This refers to the outlet air temperature of the cooling unit. The windward area of ​​a single finned tube; The unit's frontal wind speed; The density of air in the external environment; The conservation equation for heat transfer between the fluids inside and outside the finned tube is: (8) In the formula: The mass of the fluid inside the finned tube; This represents the enthalpy of the fluid inside the finned tube. For time; The mass flow rate of steam entering the finned tube; The enthalpy of the vapor entering the finned tube; The mass flow rate of the fluid exiting the finned tube; The enthalpy of the fluid flowing out of the finned tube; The heat released by the steam is: (9) The amount of heat absorbed by the air is: (10) The dynamic calculation equation for the air outlet temperature of the air-cooled unit is as follows: (11) In the formula: for The air temperature at the outlet of the air-cooled unit at all times; To calculate the time step; The mass of the inertial link of air.

[0028] The overall pressure calculation module for the air-cooled condenser is based on the ideal gas law. Its calculation process includes steam inventory calculation, steam partial pressure calculation, air inventory calculation, air partial pressure calculation, and condenser total pressure calculation. The steam inventory inside the air-cooled condenser is calculated using the following formula: (12) The steam inlet flow rate to the air-cooled condenser is as follows: (13) In the formula: The amount of steam stored inside the air-cooled condenser; The steam inlet flow rate to the air condenser; Steam outflow from the air condenser; This refers to the steam turbine exhaust volume; The dynamic evaporation rate of condensate; the saturated water temperature under the steam partial pressure in the air-cooled condenser. The temperature is lower than that in the water collection tank. hour, , The dynamic evaporation coefficient of steam; The steam outflow rate of the air-cooled condenser is: (14) In the formula: This represents the total steam condensation rate of all air-cooled units. The steam flow rate extracted by the water ring vacuum pump; Vapor partial pressure is calculated using the following formula: (15) In the formula: for Vapor partial pressure at any given time; for Vapor partial pressure at any given time; The average gas constant of the vapor; The thermodynamic temperature of steam; This represents the total volume of the condenser.

[0029] Furthermore, the partial pressure of air is calculated using the following formula: (16) In the formula: for The partial pressure of air at any given moment; for The partial pressure of air at any given moment; The amount of non-condensable gas in the condenser is calculated using the following formula: (17) (18) In the formula: The amount of non-condensable gas remaining in the condenser; This is the net inflow of non-condensable gases into the condenser. This refers to the amount of air leaking into the vacuum breaker valve. This is normal leakage rate; This refers to the leakage rate of the shaft seal. This represents the amount of air leakage due to the fault. This refers to the steam extraction rate of the vacuum pump. This represents the percentage of air mass inside the condenser. The total pressure of the condenser is equal to the sum of the partial pressure of steam and the partial pressure of air, and is calculated using the following formula: (19) In the formula: This is the condenser full pressure.

[0030] The intelligent analysis module for cold-end operation status includes an online cooling capacity assessment unit, a back pressure operation deviation analysis unit, a heat dissipation tube wall temperature distribution analysis unit, and a quantitative assessment unit for equipment cleanliness. The online cooling capacity assessment unit is based on the overall heat transfer coefficient output by the air-cooled unit finned tube bundle heat transfer calculation module. The total condenser pressure output by the air-cooled condenser overall pressure calculation module The unit calculates the real-time cooling capacity of each air-cooled unit and the entire air-cooled island; the back pressure operation deviation analysis unit calculates the total condenser pressure. The back pressure value is compared with the design back pressure value to analyze the causes of back pressure operation deviation; the heat dissipation pipe wall temperature distribution analysis unit generates a wall temperature distribution cloud map of the entire air-cooled island based on the data of each heat dissipation pipe bundle wall temperature measurement point, and identifies local temperature anomaly areas; the equipment cleanliness status quantitative assessment unit is based on the overall heat transfer coefficient. By analyzing the changing trends and combining environmental parameters with operating conditions, the degree of fouling of finned tubes can be quantitatively assessed.

[0031] The DCS integrated display and interaction module includes a data visualization display unit, an anomaly warning unit, and a control command interaction unit. The data visualization display unit integrates and displays data on cooling capacity, back pressure deviation, wall temperature distribution, and cleanliness output by the cold end operation status intelligent analysis module in the form of numerical values, curves, and cloud maps on the DCS control screen. The anomaly warning unit issues audible and visual warning signals when it detects that the back pressure deviation exceeds the set threshold, the local wall temperature is lower than the antifreeze threshold, or the equipment cleanliness is lower than the set level. The control command interaction unit receives parameter adjustment commands issued by operators through the DCS and transmits them to the unit control system. At the same time, it receives feedback signals from the unit control system to realize closed-loop interaction between monitoring and control.

[0032] The present disclosure will be described in detail below with reference to a specific embodiment: The direct air-cooled unit cold-end comprehensive performance improvement system of this disclosure includes a measuring point layout module, a multi-channel data acquisition and transmission module, an air-cooled unit finned tube bundle heat transfer calculation module, an air-cooled condenser overall pressure calculation module, a cold-end operating status intelligent analysis module, and a DCS integrated display and interaction module. The output of the measuring point layout module is connected to the input of the multi-channel data acquisition and transmission module. The output of the multi-channel data acquisition and transmission module is connected to the input of the air-cooled unit finned tube bundle heat transfer calculation module and the air-cooled condenser overall pressure calculation module, respectively. The outputs of the air-cooled unit finned tube bundle heat transfer calculation module and the air-cooled condenser overall pressure calculation module are both connected to the input of the cold-end operating status intelligent analysis module. The output of the cold-end operating status intelligent analysis module is connected to the input of the DCS integrated display and interaction module.

[0033] The measurement point layout module arranges one inlet air temperature measurement point at the center of the air inlet side of each air-cooled unit, five outlet air temperature measurement points at the four corners and the center of the air outlet side, twelve heat dissipation tube bundle wall temperature measurement points evenly arranged on the surface of the co-flow and counter-flow tube bundles, and one condensate temperature measurement point and one condensate pressure measurement point arranged in the middle of the condensate manifold.

[0034] The workflow is as follows: Step 1: System Initialization After the system powers on, it first performs a comprehensive initialization process. This includes loading the configuration parameters of each module, establishing communication connections with the unit's DCS system, initializing the timing database, verifying the communication status of each measuring point, and calibrating the initial parameters of the calculation model. Once initialization is complete, the system automatically enters real-time monitoring mode and begins continuously collecting and processing data.

[0035] Step 2: Data Acquisition and Preprocessing The measuring point layout module collects physical parameters at each measuring point in real time and converts them into 4-20mA standard analog signals, which are then output to the analog input unit of the multi-channel data acquisition and transmission module. The analog input unit converts the received analog signals into 16-bit precision digital signals and transmits them to the data preprocessing unit. The data preprocessing unit first uses a moving average filtering algorithm to filter the digital signals, removing high-frequency noise. Then, based on the pre-set range of each measuring point, it converts the digital signals into corresponding physical quantity values. Finally, it verifies the validity of the converted physical quantity data, automatically identifying and marking invalid data that exceeds the range or has an abnormal rate of change. After preprocessing, the standardized operating parameter data is stored in real time in a time-series database and transmitted via a real-time transmission unit at 100ms intervals to the air-cooled unit finned tube bundle heat exchange calculation module and the air-cooled condenser overall pressure calculation module, respectively.

[0036] Step 3: Heat transfer calculation of finned tube bundle in air-cooled unit After receiving the standardized operating parameter data, the heat exchange calculation module of the air-cooled unit finned tube bundle performs calculations in the following order: First, based on the inlet air temperature, outlet air temperature, steam temperature, and condensate temperature, the logarithmic mean temperature difference between the fluids inside and outside the finned tube is calculated using formula (5). Then, based on the predetermined overall heat transfer coefficient... Cooling unit heat exchange area In addition to the steam enthalpy and condensate enthalpy, the main condensate volume is calculated using formula (4). Next, based on the saturated steam temperature and saturated water temperature corresponding to the air-cooled condenser pressure, the dynamic condensation rate of steam is calculated using formula (6). Finally, based on the air mass flow rate, air specific heat capacity at constant pressure, inlet air temperature, main condensate volume, and steam enthalpy difference, the air outlet temperature of the air-cooled unit is calculated using formula (11). The calculation process for each air-cooled unit is performed independently. After the calculation is completed, the main condensate volume is... Overall heat transfer coefficient Air outlet temperature The parameters are output to the cold end operation status intelligent analysis module.

[0037] Step 4: Overall pressure calculation of the air-cooled condenser The overall pressure calculation module for the air-cooled condenser receives standardized operating parameter data and the main condensate flow rate of each unit output by the heat transfer calculation module for the finned tube bundle of the air-cooled unit. Then, the calculations are performed in the following order: First, based on the turbine exhaust steam volume, the dynamic evaporation of condensate, the total condensate volume, the dynamic condensation of steam, and the vacuum pump extraction steam volume, the rate of change of steam inventory is calculated using formulas (12)-(14). Then, based on the steam partial pressure, average steam gas constant, steam temperature, and total condenser volume of the previous moment, the steam partial pressure at the current moment is calculated using formula (15). Next, based on the various leakage rates of the vacuum system and the steam extraction rate of the vacuum pump, the rate of change of the air inventory is calculated using formulas (17)-(18). Then, based on the air partial pressure at the previous moment, calculate the air partial pressure at the current moment using formula (16). Finally, based on Dalton's law of partial pressures, the total pressure of the condenser is calculated using formula (19). After the calculation is completed, the vapor partial pressure is... partial pressure of air Condenser total pressure The parameters are output to the cold end operation status intelligent analysis module.

[0038] Step 5: Intelligent Analysis of Cold End Operation Status After receiving parameters from the air-cooled unit finned tube bundle heat transfer calculation module and the air-cooled condenser overall pressure calculation module, the cold-end operation status intelligent analysis module allows the four analysis units to work simultaneously in parallel: the online cooling capacity evaluation unit calculates the overall heat transfer coefficient K of each air-cooled unit and the total pressure of the condenser. The cooling capacity index of each unit is calculated, and the cooling capacity of all units is ranked to identify the unit with the worst heat exchange performance. The back pressure operation deviation analysis unit calculates the total condenser pressure. The back pressure deviation is calculated by comparing it with the design back pressure value under the same operating conditions, and the main causes of the high back pressure are determined through correlation analysis. The heat pipe wall temperature distribution analysis unit generates a wall temperature distribution cloud map for the unit based on data from 12 wall temperature measurement points using a bilinear interpolation algorithm. The cloud maps from all units are then stitched together to form the wall temperature distribution cloud map of the entire air-cooled island, automatically identifying local areas where the temperature is below the antifreeze threshold. The equipment cleanliness status quantitative assessment unit calculates the current overall heat transfer coefficient. Compared with the reference heat transfer coefficient under clean conditions Compare and calculate cleaning factors The degree of fouling of the finned tubes is assessed based on the magnitude of the cleaning factor. All analysis results are then uniformly output to the DCS integrated display and interactive module.

[0039] Step 6: DCS Display and Interaction The data visualization unit of the DCS integrated display and interaction module integrates all received monitoring data and analysis results, displaying them intuitively on the DCS control screen. Operators can view detailed parameters for each air-cooled unit, such as inlet air temperature, outlet air temperature, wall temperature distribution, condensate temperature, condensate pressure, main condensate flow rate, and overall heat transfer coefficient. They can also view overall operating parameters for the entire air-cooled island, including condenser total pressure, steam partial pressure, air partial pressure, total cooling capacity, back pressure deviation, and cleanliness. The anomaly warning unit monitors all parameters in real time to ensure they do not exceed set thresholds. When an anomaly is detected, it immediately issues an audible and visual warning signal of the appropriate level and displays an anomaly information window on the DCS screen, showing the anomaly location, parameter value, and suggested handling measures. The control command interaction unit listens to control commands issued by operators through the DCS screen in real time, converts them into a standard communication protocol format, transmits them to the unit control system, and receives feedback signals from the unit control system in real time to confirm the execution status of the commands.

[0040] Step 7: Historical Data Storage and Playback Throughout the entire operation, the system stores all collected raw data, preprocessed data, calculated intermediate parameters, and analysis results in a time-series database in real time with a 100ms time resolution. Operators can use the historical data query function on the DCS screen to query historical data for any time period and replay historical data to reproduce the system's operating status at a specific point in the past. Historical data can also be exported as Excel reports for operational analysis, fault diagnosis, and performance evaluation.

[0041] The direct air-cooled unit cold-end comprehensive performance improvement system of the embodiments of this disclosure has the following beneficial effects: By scientifically configuring key measuring points such as inlet air temperature, outlet air temperature, heat dissipation tube bundle wall temperature, condensate temperature, and condensate pressure in each air-cooled unit, a high-density multi-parameter monitoring network covering the entire air-cooled island is constructed. This solves the problems of insufficient measuring point coverage and the inability to reflect unit-level operational differences in existing monitoring systems, enabling comprehensive and accurate acquisition of the actual operating status of each air-cooled unit.

[0042] Based on the principle of heat balance and the ideal gas law, a heat transfer calculation model for the finned tube bundle of an air-cooled unit considering dynamic condensation and air inertia effects, and an overall pressure calculation model for the air-cooled condenser considering the influence of non-condensable gases, were constructed. Compared with traditional steady-state calculation models, the calculation models disclosed herein can accurately reflect the heat transfer process and pressure changes under dynamic operating conditions, significantly improving calculation accuracy and providing a reliable data foundation for in-depth optimization control of the cold-end system.

[0043] The intelligent analysis module for cold-end operation status can assess the cooling capacity of each air-cooled unit and the entire air-cooled island online, accurately analyze the causes of back pressure operation deviations, monitor the wall temperature distribution of the heat dissipation tube bundle in real time, and quantitatively assess the degree of fouling of the finned tubes. These analytical results provide operators with comprehensive and scientific decision support, enabling them to shift from traditional experience-based operations to data-driven, refined operations.

[0044] Through the DCS integration display and interaction module, all monitoring data and analysis results are seamlessly integrated into the unit's existing DCS control screen, allowing operators to fully grasp the operating status of the cold end system without switching systems. Simultaneously, this module also achieves closed-loop interaction with the unit's control system, receiving control commands from operators and providing feedback on their execution, laying the foundation for future fully automated optimized control of the cold end system.

[0045] It is understood that the above embodiments are merely exemplary embodiments used to illustrate the principles of this disclosure, and this disclosure is not limited thereto. For those skilled in the art, various modifications and improvements can be made without departing from the spirit and substance of this disclosure, and these modifications and improvements are also considered to be within the scope of protection of this disclosure.

Claims

1. A system for improving the overall performance of the cold end of a direct air-cooled unit, characterized in that, It includes a measuring point layout module, a multi-channel data acquisition and transmission module, an air-cooled unit finned tube bundle heat exchange calculation module, an air-cooled condenser overall pressure calculation module, a cold end operation status intelligent analysis module, and a DCS integrated display and interaction module. The output of the measuring point layout module is connected to the input of the multi-channel data acquisition and transmission module. The output of the multi-channel data acquisition and transmission module is connected to the input of the air-cooled unit finned tube bundle heat transfer calculation module and the air-cooled condenser overall pressure calculation module, respectively. The outputs of the air-cooled unit finned tube bundle heat transfer calculation module and the air-cooled condenser overall pressure calculation module are both connected to the input of the cold end operation status intelligent analysis module. The output of the cold end operation status intelligent analysis module is connected to the input of the DCS integrated display and interaction module.

2. The system for improving the overall performance of the cold end of a direct air-cooled unit according to claim 1, characterized in that, The measuring point arrangement module includes inlet air temperature measuring points, outlet air temperature measuring points, heat dissipation tube bundle wall temperature measuring points, condensate temperature measuring points, and condensate pressure measuring points respectively set in each air-cooled unit. The inlet air temperature measuring point is located at the center of the air inlet side of the air-cooled unit, the outlet air temperature measuring point is located at the four corners and the center of the air outlet side of the air-cooled unit, the heat dissipation tube bundle wall temperature measuring point is evenly distributed on the surface of the co-current and counter-current tube bundles of the air-cooled unit, and the condensate temperature measuring point and condensate pressure measuring point are located at the condensate lower header of each air-cooled unit.

3. The system for improving the overall performance of the cold end of a direct air-cooled unit according to claim 1, characterized in that, The multi-channel data acquisition and transmission module includes an analog input unit, a data preprocessing unit, a real-time transmission unit, and a data storage unit. The analog input unit receives the analog signals from each measuring point output by the measuring point layout module, converts them into digital signals, and transmits them to the data preprocessing unit. The data preprocessing unit filters, denoises, and performs range conversion on the digital signals to generate standardized operating parameter data. The real-time transmission unit transmits the standardized operating parameter data to the air-cooled unit finned tube bundle heat exchange calculation module and the air-cooled condenser overall pressure calculation module, respectively. The data storage unit stores all collected and processed operating parameter data in a time-series format.

4. The system for improving the overall performance of the cold end of a direct air-cooled unit according to claim 1, characterized in that, The heat exchange calculation module for the air-cooled unit finned tube bundle is built based on the heat balance principle that the heat released by the steam inside the finned tube is equal to the heat absorbed by the air outside the tube. Its calculation process includes the calculation of the main condensate volume, the calculation of the dynamic steam condensation volume, and the calculation of the air outlet temperature. The main condensate volume is calculated using the following formula: (1) (2) (3) (4) In the formula: Main condensate volume; This represents the total steam flow rate inside the finned tube. This refers to the dynamic condensation rate of steam. The heat released by the steam inside the finned tube; For convective heat transfer; The overall heat transfer coefficient; This refers to the heat exchange area of ​​the cooling unit; This refers to the enthalpy of vapor. This refers to the enthalpy of condensate. The temperature difference is the logarithmic mean.

5. The system for improving the overall performance of the cold end of a direct air-cooled unit according to claim 4, characterized in that, The logarithmic mean temperature difference is calculated using the average temperature difference calculation method for mixed flow, and is calculated by the following formula: (5) In the formula: This is a correction factor for mixed flow; This represents the maximum temperature difference between the fluids inside and outside the finned tube. This represents the minimum temperature difference between the fluid inside and outside the finned tube. The dynamic condensation rate of steam is calculated using the following formula: (6) In the formula: The dynamic condensation coefficient; The saturated steam temperature corresponding to the pressure of the air condenser; The saturated water temperature corresponding to the pressure of the air condenser.

6. The system for improving the overall performance of the cold end of a direct air-cooled unit according to claim 4, characterized in that, The air outlet temperature is calculated based on the principle of conservation of heat transfer between the fluids inside and outside the finned tube. The heat transfer equation for the air outside the finned tube is as follows: (7) In the formula: It absorbs heat from the air; Air mass flow rate; The specific heat capacity of air at constant pressure; This refers to the inlet air temperature of the cooling unit. This refers to the outlet air temperature of the cooling unit. The windward area of ​​a single finned tube; The unit's frontal wind speed; The density of air in the external environment; The conservation equation for heat transfer between the fluids inside and outside the finned tube is: (8) In the formula: The mass of the fluid inside the finned tube; This represents the enthalpy of the fluid inside the finned tube. For time; The mass flow rate of steam entering the finned tube; The enthalpy of the vapor entering the finned tube; The mass flow rate of the fluid exiting the finned tube; The enthalpy of the fluid flowing out of the finned tube; The heat released by the steam is: (9) The amount of heat absorbed by the air is: (10) The dynamic calculation equation for the air outlet temperature of the air-cooled unit is as follows: (11) In the formula: for The air temperature at the outlet of the air-cooled unit at all times; To calculate the time step; The mass of the inertial link of air.

7. The system for improving the overall performance of the cold end of a direct air-cooled unit according to claim 1, characterized in that, The overall pressure calculation module for the air-cooled condenser is based on the ideal gas law. Its calculation process includes steam inventory calculation, steam partial pressure calculation, air inventory calculation, air partial pressure calculation, and condenser total pressure calculation. The steam inventory inside the air-cooled condenser is calculated using the following formula: (12) The steam inlet flow rate to the air-cooled condenser is as follows: (13) In the formula: The amount of steam stored inside the air-cooled condenser; The steam inlet flow rate to the air condenser; Steam outflow from the air condenser; This refers to the steam turbine exhaust volume; The dynamic evaporation rate of condensate; the saturated water temperature under the steam partial pressure in the air-cooled condenser. The temperature is lower than that in the water collection tank. hour, , The dynamic evaporation coefficient of steam; The steam outflow rate of the air-cooled condenser is: (14) In the formula: This represents the total steam condensation rate of all air-cooled units. The steam flow rate extracted by the water ring vacuum pump; Vapor partial pressure is calculated using the following formula: (15) In the formula: for Vapor partial pressure at any given time; for Vapor partial pressure at any given time; The average gas constant of the vapor; The thermodynamic temperature of steam; This represents the total volume of the condenser.

8. A system for improving the overall performance of the cold end of a direct air-cooled unit according to claim 7, characterized in that, The air partial pressure is calculated using the following formula: (16) In the formula: for The partial pressure of air at any given moment; for The partial pressure of air at any given moment; The amount of non-condensable gas in the condenser is calculated using the following formula: (17) (18) In the formula: The amount of non-condensable gas remaining in the condenser; This is the net inflow of non-condensable gases into the condenser. This refers to the amount of air leaking into the vacuum breaker valve. This is normal leakage rate; This refers to the air leakage rate of the shaft seal. This represents the amount of air leakage due to the fault. This refers to the steam extraction rate of the vacuum pump; This represents the percentage of air mass inside the condenser. The total pressure of the condenser is equal to the sum of the partial pressure of steam and the partial pressure of air, and is calculated using the following formula: (19) In the formula: This is the condenser full pressure.

9. A system for improving the overall performance of the cold end of a direct air-cooled unit according to claim 1, characterized in that, The intelligent analysis module for cold end operation status includes an online cooling capacity assessment unit, a back pressure operation deviation analysis unit, a heat pipe wall temperature distribution analysis unit, and a quantitative assessment unit for equipment cleanliness. The online cooling capacity evaluation unit is based on the overall heat transfer coefficient output by the air-cooled unit finned tube bundle heat transfer calculation module. The total condenser pressure output by the air-cooled condenser overall pressure calculation module The real-time cooling capacity of each air-cooled unit and the entire air-cooled island is calculated; the back pressure operation deviation analysis unit will calculate the total condenser pressure. Compare the back pressure value with the design back pressure value to analyze the causes of back pressure operation deviation; The heat dissipation pipe wall temperature distribution analysis unit generates a cloud map of the overall wall temperature distribution of the air-cooled island based on the data from the wall temperature measurement points of each heat dissipation pipe bundle, and identifies local temperature anomaly areas. The equipment cleanliness quantitative assessment unit is based on the overall heat transfer coefficient. By analyzing the changing trends and combining environmental parameters with operating conditions, the degree of fouling of finned tubes can be quantitatively assessed.

10. A system for improving the overall performance of the cold end of a direct air-cooled unit according to claim 1, characterized in that, The DCS integrated display and interaction module includes a data visualization display unit, an anomaly warning unit, and a control command interaction unit. The data visualization display unit integrates and displays the cooling capacity, back pressure deviation, wall temperature distribution, and cleanliness data output by the cold end operation status intelligent analysis module in the form of numerical values, curves, and cloud maps on the DCS control screen; the abnormality early warning unit issues an audible and visual early warning signal when it detects that the back pressure deviation exceeds the set threshold, the local wall temperature is lower than the antifreeze threshold, or the equipment cleanliness is lower than the set level; the control command interaction unit receives parameter adjustment commands issued by the operators through the DCS and transmits them to the unit control system, while receiving feedback signals from the unit control system to realize closed-loop interaction between monitoring and control.

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