Automatic control method and system for air-cooled condenser fan

Abstract

The present invention relates to an automatic control method for an air-cooled condenser fan, the method comprising: obtaining characteristic parameters of the working state of the air-cooled condenser; wherein the characteristic parameters are the position of the temperature transition interface or the deviation of the position of the temperature transition interface; using the characteristic parameters as input signals, and converting them into fan frequency signals, fan voltage signals or fan current signals after processing to perform fan closed-loop control until they match the target characteristic parameters. The system comprises an air-cooled condenser temperature transition interface capture device, a signal conversion device and a control device; the air-cooled condenser temperature transition interface capture device comprises a temperature measuring element, a data acquisition device and a data processing device. The present invention uses the characteristic parameters or temperature parameters of the working state of the air-cooled condenser as the input signals of the control system to realize closed-loop control of the air-cooled condenser fan, thereby achieving the purpose of optimizing the operation of the cold end, saving fan power consumption and preventing the air-cooled condenser from freezing, and simplifying the control system.

Description

Technical Field

[0001] The present invention relates to the technical field of thermal power generation, and in particular to an automatic control method and system for a fan of an air-cooled condenser. Background Art

[0002] Optimizing the cold end operation of direct air-cooled units is an effective measure to reduce the coal consumption rate of power generation, and the key to achieving optimal cold end operation lies in the automatic control of the air-cooled condenser fan.

[0003] There are many factors related to the air-cooled condenser of a direct air-cooled unit that affect the unit's economic efficiency. In particular, some factors such as wind direction (including occasional crosswinds) and back-of-furnace wind change irregularly and uncertainly. Therefore, it is difficult to give the working status of the condenser based on one or several of these factors, nor is it possible to evaluate the performance of the air-cooled condenser. The lack of online working status monitoring parameters for the air-cooled condenser makes it impossible to achieve automatic control and refined optimization and adjustment of the air-cooled condenser fan. It can be said that what signal is used as the input signal of the air-cooled condenser fan control system to achieve reliable and accurate operation control is the fundamental problem that plagues the optimized operation of the air-cooled condenser fan.

[0004] In previous research and applications, cold-end optimization for direct air-cooled units has been primarily categorized into two main approaches: experimental and model-based. The experimental approach relies on limited online data to determine the optimal unit vacuum under specific loads and ambient temperatures, which is then used to develop fan control methods and strategies. Because these tests can only be conducted under specific operating conditions and parameters, the guiding significance of the test results is weakened or even rendered ineffective when actual operating conditions differ from the test conditions. Furthermore, the limited number of factors considered in the tests makes it impossible to encompass the majority of cold-end factors that affect unit economics, making the conclusions difficult to apply to refined operational optimization.

[0005] Modeling methods typically construct an optimal unit backpressure calculation model, taking into account multiple factors to guide optimal cold-end operation. For example, a unit backpressure optimization model is developed that considers the influence of condensate flow, air temperature, fan speed, and fin tube fouling. An economic backpressure curve model is derived by calculating the unit's slightly increased output characteristics and the fan power consumption characteristics. A mathematical model for air-cooled unit backpressure is developed using optimization algorithms such as particle swarm optimization and neural networks, taking into account the effects of load, ambient temperature, fan speed, fin tube cleanliness, and vacuum device performance on backpressure. A predictive model for the air outlet temperature distribution of the air-cooled island is developed to adjust the fan frequency. Because some model parameters are unmeasurable, such as condensate flow and fin tube cleanliness, and some parameters interact, such as condensate flow, unit load, and initial and final parameters, current models are often complex, lacking practicality and accuracy, and the control system is also very complex. In addition to these factors, crosswind, after-furnace draft, and wind direction fluctuations in actual operation can affect the heat exchange performance of the air-cooled condenser, which neither experimental nor modeling methods can address.

[0006] In addition to experimental and modeling methods, recent progress has been made in measuring the temperature field of air-cooled condensers (ACs) to monitor their winter operation and prevent freezing. These AC temperature field measurements primarily utilize infrared imaging and digital chip temperature measurement technologies. However, due to limitations in equipment layout and measurement accuracy, most of these technologies are used only for antifreeze monitoring and are unable to utilize temperature data for closed-loop fan control.

[0007] Therefore, finding the state monitoring parameters of the air-cooled condenser, constructing a simple optimization operation model and algorithm for the air-cooled condenser fan control, and simplifying the control system structure are of great significance for realizing the closed-loop control and optimized operation of the air-cooled condenser fan. Summary of the Invention

[0008] The purpose of the present invention is to provide an automatic control method and system for the fan of an air-cooled condenser, which uses the characteristic parameters or temperature parameters of the working state of the air-cooled condenser as the input signal of the control system to realize closed-loop control of the fan, so as to achieve the purpose of optimizing the operation of the cold end and saving the power consumption of the fan.

[0009] The present invention provides an automatic control method for a fan of an air-cooled condenser, comprising:

[0010] Step 1: Acquire characteristic parameters of the working state of the air-cooled condenser; wherein the characteristic parameters are the position of the temperature transition interface or the position deviation of the temperature transition interface;

[0011] Step 2: Using the characteristic parameter as an input signal, the signal is converted into a fan frequency signal, a fan voltage signal or a fan current signal after processing to perform fan closed-loop control until the signal matches the target characteristic parameter.

[0012] Furthermore, the method for obtaining the position of the temperature transition interface in step 1 includes:

[0013] The position of the temperature transition interface is determined by comparing the difference in measured data of two adjacent rows of temperature measuring elements in the countercurrent zone:

[0014] When the difference in the measured data of two adjacent rows of temperature measuring elements in the countercurrent zone is significantly greater than the difference in the measured data of other two adjacent rows of temperature measuring elements, the temperature transition interface is determined to be located between the two adjacent rows of temperature measuring elements; when the measured data of the temperature measuring elements in the lower part of the downstream zone are close to the ambient temperature or at least 5°C lower than the steam temperature, the temperature transition interface is determined to be located at the steam side outlet of the downstream zone.

[0015] Furthermore, the method for obtaining the position of the temperature transition interface in step 1 includes:

[0016] By comparing the temperature differences between different measuring points, the position of the temperature transition interface can be determined:

[0017] When the temperature difference between the downstream measuring point and any height measuring point in the countercurrent area exceeds the set value, the temperature transition interface is determined to be located between the most upstream position in the steam flow direction in the air-cooled condenser and its adjacent upstream position among all positions where the temperature difference between the downstream measuring point and the countercurrent measuring point exceeds the set value;

[0018] When the temperature difference between the temperature measuring point at the lower part of the downstream zone and the steam temperature inside the steam distribution pipe exceeds the set value, it is determined that the temperature transition interface is located at the steam side outlet of the downstream zone.

[0019] Furthermore, the method for obtaining the position of the temperature transition interface in step 1 includes:

[0020] An infrared thermal imager is used to measure the temperature field of the air-cooled condenser. Based on the significant color difference between the upstream and downstream parts of the image, the location where the color changes rapidly is identified as the temperature transition interface.

[0021] Furthermore, the control strategy using the temperature transition interface position as an input signal in step 2 includes:

[0022] When the temperature transition interface position is upstream of the temperature transition interface target position, reduce the fan output until the deviation between the temperature transition interface position and the temperature transition interface target position is less than the set value; when the temperature transition interface position is downstream of the temperature transition interface target position, increase the fan output until the deviation between the temperature transition interface position and the temperature transition interface target position is less than the set value; wherein the temperature transition interface target position is located 2m downstream from the steam side outlet of the downstream zone of the air-to-condenser to the steam side outlet of the countercurrent zone. Furthermore, the control strategy using the temperature transition interface position as an input signal in step 2 also includes:

[0023] When the temperature transition interface is located in the downstream area, the output of multiple fans is adjusted simultaneously; when the temperature transition interface is located in the upstream area, the output of one or more fans is adjusted.

[0024] The present invention also provides an automatic control method for an air-cooled condenser fan, comprising:

[0025] Step 1) obtaining temperature parameters of the working state of the air-cooled condenser; wherein the temperature parameters include the difference between the air side outlet temperature of the countercurrent zone or the downstream zone of the air-cooled condenser and the ambient temperature, the difference between the air-cooled condenser extraction temperature and the ambient temperature, the difference between the condensate temperature and the steam temperature, the difference between the steam temperature and the air-cooled condenser extraction temperature, the air-cooled condenser extraction temperature, the air side outlet temperature of the lower part of the downstream zone of the air-cooled condenser, and the air side outlet temperature of the countercurrent zone;

[0026] Step 2) At least one of the temperature parameters is used as an input signal, which is converted into a fan frequency signal, a fan voltage signal or a fan current signal after processing to perform fan closed-loop control until it matches the target temperature parameter.

[0027] Furthermore, in step 2), the control strategy using the difference between the air side outlet temperature of the countercurrent zone or the downstream zone of the air-to-condenser and the ambient temperature as the input signal includes:

[0028] When the difference between the air side outlet temperature of the air condenser in the countercurrent area or the downstream area and the ambient temperature is less than the set low value, the fan power is reduced; when the difference between the air side outlet temperature of the air condenser and the ambient temperature is greater than the set high value, the fan power is increased; when the difference between the air side outlet temperature of the air condenser and the ambient temperature is between the set low value and the set high value, the fan power is maintained unchanged.

[0029] Furthermore, in step 2), the control strategy using the difference between the air-cooled condenser exhaust temperature and the ambient temperature as the input signal includes:

[0030] When the difference between the air-cooled condenser exhaust temperature and the ambient temperature is less than the set low value, the fan power is reduced; when the difference between the air-cooled condenser exhaust temperature and the ambient temperature is greater than the set high value, the fan power is increased; when the difference between the air-cooled condenser exhaust temperature and the ambient temperature is between the set low value and the set high value, the fan power is maintained unchanged.

[0031] Furthermore, in step 2), the control strategy using the air-cooled condenser extraction temperature as the input signal includes:

[0032] When the air-cooled condenser exhaust temperature is lower than the set low value, the fan power is reduced; when the air-cooled condenser exhaust temperature is higher than the set high value, the fan power is increased; when the air-cooled condenser exhaust temperature is between the set low value and the set high value, the fan power is maintained unchanged.

[0033] Furthermore, in step 2), the control strategy using the air side outlet temperature of the air condenser as the input signal includes:

[0034] When the air side outlet temperature of the air condenser is lower than the set low value, the fan power is reduced; when the air side outlet temperature of the air condenser is higher than the set high value, the fan power is increased; when the air side outlet temperature of the air condenser is between the set low value and the set high value, the fan power is maintained unchanged.

[0035] The present invention also provides an automatic control system for a fan of an air-conditioning condenser, comprising an air-conditioning condenser temperature transition interface capture device, a signal conversion device, and a control device; the condenser temperature transition interface capture device comprises a temperature measuring element, a data acquisition device, and a data processing device, which are arranged on the air outlet side of the air-conditioning condenser and span the downstream and upstream zones; the temperature measuring element, the data acquisition device, the data processing device, the signal conversion device, and the control device are connected in sequence, and the control device is connected to the fan of the air-conditioning condenser;

[0036] The data acquisition device is used to collect temperature measurement data of the temperature measuring element and transmit the temperature measurement data to the data processing device;

[0037] The data processing device is used to obtain the temperature transition interface position information according to the temperature measurement data, and transmit the temperature transition interface position information to the signal conversion device;

[0038] The signal conversion device is used to convert the temperature transition interface position information into a fan frequency signal, a fan voltage signal or a fan current signal, and transmit the converted signal to the control device;

[0039] The control device is used to use the fan frequency signal, fan voltage signal or fan current signal output by the signal conversion device as an input signal to execute the following fan closed-loop control strategy:

[0040] When the temperature transition interface position is upstream of the temperature transition interface target position, reduce the fan output until the deviation between the temperature transition interface position and the temperature transition interface target position is less than the set value; when the temperature transition interface position is downstream of the temperature transition interface target position, increase the fan output until the deviation between the temperature transition interface position and the temperature transition interface target position is less than the set value.

[0041] By means of the above scheme, through the air-cooled condenser fan automatic control method and system, the characteristic parameters or temperature parameters of the air-cooled condenser working state are used as the input signals of the control system, and the closed-loop control of the air-cooled condenser fan is realized, which solves the problem that the air-cooled condenser fan has not been able to achieve closed-loop automatic control, simplifies the control model and control system structure, reduces investment and operation difficulty, and improves the control accuracy and reliability of the air-cooled condenser fan, so as to achieve the purpose of optimizing the operation of the cold end, saving fan power consumption and anti-freezing of the air-cooled condenser.

[0042] The above description is only an overview of the technical solution of the present invention. In order to more clearly understand the technical means of the present invention and implement it according to the contents of the specification, the following is a detailed description of the preferred embodiments of the present invention with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] Figure 1 The present invention is a flow chart of an embodiment of an automatic control method for an air-cooled condenser fan.

[0044] Figure 2 This is a flow chart of another embodiment of an automatic control method for an air-cooled condenser fan of the present invention;

[0045] Figure 3 This is a structural schematic diagram of an embodiment of an automatic control system for an air-cooled condenser fan of the present invention;

[0046] Figure 4 Schematic diagram of four typical positions of the temperature transition interface in an automatic control system of an air-cooled condenser fan of the present invention.

[0047] Numbers in the figure:

[0048] 1-steam distribution pipe; 2-downstream area; 3-countercurrent area; 4-exhaust pipe; 5-condensate pipe; 6-temperature measuring element; 7-temperature transition interface position; 8-fan; 9-temperature transition interface target position; 10-data acquisition device; 11-data processing device; 12-signal conversion device; 13-control device. DETAILED DESCRIPTION

[0049] The following embodiments of the present invention are described in further detail with reference to the accompanying drawings and examples. The following examples are used to illustrate the present invention but are not intended to limit the scope of the present invention.

[0050] Ginseng Figure 1 As shown, this embodiment provides an automatic control method for an air-cooled condenser fan, comprising:

[0051] Step S11, obtaining characteristic parameters of the working state of the air-cooled condenser; wherein the characteristic parameters are the temperature transition interface position or the temperature transition interface position deviation (the distance difference between the temperature transition interface position and the specific position);

[0052] In step S12, the characteristic parameter is used as an input signal, and is converted into a fan frequency signal, a fan voltage signal or a fan current signal after processing to perform fan closed-loop control until it matches the target characteristic parameter.

[0053] In this embodiment, the temperature transition interface refers to a region of rapidly changing temperature located somewhere within the finned tubes of an air-cooled condenser. Upstream of this region, along the direction of steam flow within the finned tubes, the steam temperature within the finned tubes is close to the saturation temperature and remains essentially constant; downstream of this region, the steam temperature within the finned tubes is close to the ambient temperature and also remains essentially constant. The distance from the inlet to the outlet of this region along the length of the finned tubes is very short, and the temperature rapidly decreases from near the steam saturation temperature upstream to near the ambient temperature downstream, resulting in a very large temperature gradient. Given the extremely short axial distance of this region along the finned tubes, it is referred to herein as the temperature transition interface. The position of this temperature transition interface varies with the heat exchange conditions of the air-cooled condenser, directly reflecting its heat exchange state and serving as a crucial characteristic parameter. In this embodiment, the actual position of the temperature transition interface is used as an input signal for the fan control system. This control can adjust the fan output to adjust the temperature transition interface to the desired target position, achieving closed-loop control of the air-cooled condenser fan, thereby optimizing cold-end operation and reducing fan power consumption.

[0054] In this embodiment, the method for obtaining the temperature transition interface position in step S11 includes:

[0055] The position of the temperature transition interface is determined by comparing the difference in measured data of two adjacent rows of temperature measuring elements in the countercurrent zone:

[0056] When the difference in the measured data of two adjacent rows of temperature measuring elements in the countercurrent zone is significantly greater than the difference in the measured data of other two adjacent rows of temperature measuring elements, the temperature transition interface is determined to be located between the two adjacent rows of temperature measuring elements; when the measured data of the temperature measuring elements at the lower part of the downstream zone are close to the ambient temperature, the temperature transition interface is determined to be located at the steam side outlet of the downstream zone.

[0057] In this embodiment, the method for obtaining the temperature transition interface position in step S11 may also be:

[0058] By comparing the temperature differences between different measuring points, the position of the temperature transition interface can be determined:

[0059] When the temperature difference between the downstream measuring point and any highly countercurrent measuring point exceeds the set value, the temperature transition interface is determined to be located between the most upstream position in the steam flow direction of the air-cooled condenser and its adjacent upstream position among all positions where the temperature difference between the downstream measuring point and the countercurrent measuring point exceeds the set value;

[0060] When the temperature difference between the temperature measuring point at the lower part of the downstream zone and the steam temperature inside the steam distribution pipe exceeds the set value, it is determined that the temperature transition interface is located at the steam side outlet of the downstream zone.

[0061] In a specific example, when using a thermocouple, thermal resistor, or digital chip temperature measuring element to measure temperature, based on the temperature distribution pattern upstream and downstream of the temperature transition interface, by comparing the temperature difference between the downstream zone measuring point and any highly countercurrent zone measuring point, when the temperature difference exceeds δt (e.g., 3°C), the countercurrent zone measuring point can be considered to be downstream of the temperature transition interface. Among all locations where the temperature difference between the downstream zone measuring point and the countercurrent zone measuring point exceeds δt (3°C), the most upstream position along the steam flow direction in the air-cooled condenser and its adjacent upstream position are respectively located downstream and upstream of the temperature transition interface, and the temperature transition interface can be determined to be located between the two. The temperature difference can also be the difference between the steam temperature inside the steam distribution pipe and the temperature of the countercurrent zone measuring point; when the temperature measured by the temperature measuring device at the lower part of the downstream zone differs from the steam temperature inside the steam distribution pipe by more than δt (3°C), the temperature transition interface is determined to be located at the lower part of the downstream zone.

[0062] In this embodiment, the method for obtaining the temperature transition interface position in step S11 may also be:

[0063] An infrared thermal imager is used to measure the temperature field at the outlet of the air-cooling island. Based on the significant difference in color between the upstream and downstream parts of the image, the location where the color changes rapidly is identified as the temperature transition interface.

[0064] In this embodiment, the control strategy using the temperature transition interface position as an input signal in step S12 includes:

[0065] When the temperature transition interface is upstream of the target temperature transition interface position, reduce the fan output until the deviation between the temperature transition interface position and the target temperature transition interface position is less than the set value. When the temperature transition interface is downstream of the target temperature transition interface position, increase the fan output until the deviation between the temperature transition interface position and the target temperature transition interface position is less than the set value. The target temperature transition interface position is located 2 meters downstream from the downstream steam outlet of the air-to-condenser to the upstream steam outlet.

[0066] In this embodiment, the control strategy using the temperature transition interface position as an input signal in step S12 further includes:

[0067] When the temperature transition interface is located in the downstream area, the output of multiple fans is adjusted simultaneously; when the temperature transition interface is located in the upstream area, the output of one or more fans is adjusted.

[0068] Ginseng Figure 2 As shown, in another embodiment, a method for automatically controlling a fan of an air-cooled condenser includes:

[0069] Step S21, obtaining temperature parameters of the working state of the air-cooled condenser; wherein the temperature parameters include the difference between the air side outlet temperature of the countercurrent zone or the downstream zone of the air-cooled condenser and the ambient temperature, the difference between the air-cooled condenser extraction temperature and the ambient temperature, the difference between the condensate temperature and the steam temperature, the difference between the steam temperature and the air-cooled condenser extraction temperature, the air-cooled condenser extraction temperature, the air side outlet temperature of the lower part of the downstream zone of the air-cooled condenser, and the air side outlet temperature of the countercurrent zone;

[0070] In step S22, at least one of the temperature parameters is used as an input signal, and is converted into a fan frequency signal, a fan voltage signal, or a fan current signal after processing to perform fan closed-loop control until the temperature matches the target temperature parameter.

[0071] This embodiment uses the temperature parameter of the air-conditioning condenser working state as the input signal of the control system to realize the closed-loop control of the fan, which can also achieve the purpose of optimizing the operation of the cold end, saving the power consumption of the fan and preventing the air-conditioning condenser from freezing.

[0072] In this embodiment, the control strategy in step S22 using the difference between the air side outlet temperature of the counterflow zone or the downstream zone of the air-to-condenser and the ambient temperature as the input signal includes:

[0073] When the difference between the air outlet temperature of the air condenser in the upstream or downstream area and the ambient temperature is less than the set low value (such as 3°C), the fan power is reduced; when the difference between the air outlet temperature of the air condenser and the ambient temperature is greater than the set high value (such as 8°C), the fan power is increased; when the difference between the air outlet temperature of the air condenser and the ambient temperature is between the set low value and the set high value, the fan power is maintained unchanged. To improve the accuracy of control, two sets of temperature difference signals can be used simultaneously.

[0074] In this embodiment, the control strategy of using the difference between the air-cooled condenser extraction temperature and the ambient temperature as the input signal in step S22 includes:

[0075] When the difference between the condenser exhaust temperature and the ambient temperature is less than the set low value (e.g., 25°C), the fan power is reduced. When the difference between the condenser exhaust temperature and the ambient temperature is greater than the set high value (e.g., 40°C), the fan power is increased. When the difference between the condenser exhaust temperature and the ambient temperature is between the set low and set high values, the fan power is maintained unchanged. The ambient temperature can also be replaced by the condenser fan outlet temperature or the air temperature around the air-cooled island.

[0076] In this embodiment, the control strategy using the air-cooled condenser extraction temperature as the input signal in step 22 includes:

[0077] When the air-cooled condenser exhaust temperature is lower than the set low value (such as 28°C), reduce the fan power; when the air-cooled condenser exhaust temperature is higher than the set high value (such as 42°C), increase the fan power; when the air-cooled condenser exhaust temperature is between the set low value and the set high value, maintain the fan power unchanged.

[0078] In this embodiment, the control strategy using the air side outlet temperature of the air-cooled condenser as an input signal in step 22 includes:

[0079] When the air-cooled condenser temperature transition interface is located upstream of its target position, the fan power is reduced; when the air-cooled condenser temperature transition interface is located downstream of its target position, the fan power is increased; when the air-cooled condenser temperature transition interface is located at its target position, the fan power is maintained unchanged.

[0080] It should be noted that because the steam inside the air-cooled condenser is wet steam, its temperature remains essentially unchanged during the condensation process. Therefore, upstream of the temperature transition interface, the difference between the internal steam temperature of the air-cooled condenser and the ambient temperature is essentially a constant value, which is equal to the sum of the difference between the air-cooled condenser's air-side outlet temperature and the ambient temperature and the difference between the internal steam temperature of the air-cooled condenser and the air-cooled condenser's air-side outlet temperature. Therefore, using the difference between the steam temperature and the ambient temperature as a signal, using the difference between the steam temperature and the exhaust temperature as a signal, using the difference between the air-cooled condenser's air-side outlet temperature and the ambient temperature as a signal, and using the difference between the steam temperature and the air-cooled condenser's air-side outlet temperature as a signal are essentially the same, and all utilize the principle of significant temperature differences upstream and downstream of the temperature transition interface proposed in the present invention to achieve closed-loop fan control.

[0081] In addition, the fan is controlled with the exhaust temperature or the air-side outlet temperature of the air-cooled condenser as the input parameter. The control strategy formulated by comparing the difference between the exhaust temperature and the steam temperature or the difference between the air-cooled condenser air-side outlet temperature and the ambient temperature, the difference between the air-cooled condenser air-side outlet temperature and the steam temperature, the deviation between the temperature transition interface position and the target position, etc., also utilizes the principle of significant temperature difference upstream and downstream of the temperature transition interface proposed in the present invention to achieve closed-loop control of the fan.

[0082] Similarly, because the steam inside the air-cooled condenser is wet steam, its pressure and temperature correspond one to one. The steam pressure can be converted into steam temperature instead of the aforementioned direct measurement of steam temperature to achieve the same purpose, which will not be described in detail here.

[0083] Ginseng Figure 3 As shown, an automatic control system for an air-cooled condenser fan includes an air-cooled condenser temperature transition interface capture device, a signal conversion device 12 and a control device 13; the air-cooled condenser is mainly composed of a steam distribution pipe 1, a downstream area 2 composed of finned tubes, a countercurrent area 3 composed of finned tubes, a condensate pipe 5, an exhaust pipe 4, and a fan 8.

[0084] The condenser temperature transition interface capture device includes a temperature measuring element 6, a data acquisition device 10, and a data processing device 11, which are arranged at the air side outlet of the air-to-condenser and span the downstream area 2 and the upstream area 3; the temperature measuring element 6, the data acquisition device 10, the data processing device 11, the signal conversion device 12, and the control device 13 are connected in sequence, and the control device 13 is connected to the fan 8 of the air-to-condenser;

[0085] The data acquisition device 10 is used to collect temperature measurement data of the temperature measuring element 6 and transmit the temperature measurement data to the data processing device 11;

[0086] The data processing device 11 is used to obtain the temperature transition interface position 7 information according to the temperature measurement data, and transmit the temperature transition interface position 7 information to the signal conversion device 12;

[0087] The signal conversion device 12 is used to convert the temperature transition interface position 7 information into a fan frequency signal, a fan voltage signal or a fan current signal, and transmit the converted signal to the control device 13;

[0088] The control device 13 is used to use the converted temperature transition interface position 7 signal as an input signal and to implement the following fan closed-loop control strategy by adjusting the fan 8 frequency:

[0089] When temperature transition interface position 7 is upstream of temperature transition interface target position 9, reduce fan output until the deviation between temperature transition interface position 7 and temperature transition interface target position 9 is less than the set value. When temperature transition interface position 7 is downstream of temperature transition interface target position 9, increase fan output until the deviation between temperature transition interface 7 and temperature transition interface target position 9 is less than the set value. Temperature transition interface target position 9 is located 2 meters downstream from the steam outlet of downstream zone 2 of the air-to-condenser to the steam outlet of the upstream zone.

[0090] Through this air-cooled condenser fan automatic control system, the fan output can be controlled to adjust the temperature transition interface to the ideal target position, realizing closed-loop control of the air-cooled condenser fan, thereby achieving the purpose of optimizing the operation of the cold end and saving fan power consumption.

[0091] Ginseng Figure 4As shown, on the air side, the outside air, driven by the air-cooled condenser fan 8, exchanges heat with the condenser downstream zone 2 and countercurrent zone 3. The outside air is heated and the steam in the condenser is cooled. On the steam side, the turbine exhaust steam enters the air-cooled condenser downstream zone 2 through the steam distribution pipe 1. The steam is cooled by the outside air and condensed into condensate. The condensate and the uncondensed steam flow downward in the same direction and enter the lower condensate pipe 5, while the uncondensed steam enters the countercurrent zone 3 together with the non-condensable gas. In the countercurrent zone 3, the steam continues to be cooled by the outside air, continuously cooling and condensing into condensate. The condensate flows downward into the condensate pipe 5 under the action of gravity. The remaining non-condensable gas and a very small amount of steam enter the upper exhaust pipe 4 and are extracted. When the frequency of fan 8 is high and the power consumption is high, the steam inside the air-cooled condenser may be condensed at the bottom entrance of the countercurrent zone 3, or even condensed in the middle and lower part of the downstream zone 2. In this case, a large part of the energy consumed by fan 8 is wasted, and part of the air it outputs fails to play the due cooling role, which is not conducive to energy saving. In addition, when the ambient temperature is very low, it is easy to cause the inside of the air-cooled condenser to freeze and be damaged.

[0092] During the steam condensation process, the temperature transition interface position 7 will appear in four different positions:

[0093] 7-1 indicates that the temperature transition interface is located at the top of counterflow zone 3, downstream of target temperature transition interface position 9 (in the direction of internal steam flow). This indicates that the ACC fan frequency needs to be increased to enhance heat exchange between the steam inside the ACC and the external air, and the temperature transition interface position is adjusted back to target temperature transition interface position 9. At this point, the fan frequency of all ACCs can be increased (e.g., 2Hz); all counterflow fans can be increased to a certain frequency (e.g., 5Hz), while the downstream fan frequency remains unchanged; or all ACC fans in the unit can be adjusted differently.

[0094] 7-2 indicates that when the temperature transition interface is located in the middle of counterflow zone 3 and just inside the temperature transition interface target position 9, the air-cooled condenser is in a safe and economical state. At this time, it is recommended that the fan frequency of all air-cooled condensers remain unchanged.

[0095] 7-3 indicates that the temperature transition interface is at the bottom of counterflow zone 3, upstream of target temperature transition interface position 9. This indicates that the frequency of air-cooled condenser fan 8 is too high, resulting in insufficient energy conservation. In this case, it is recommended to reduce the frequency of all counterflow fans (e.g., 3Hz) or adjust all fans synchronously or differentially.

[0096] 7-4 indicates that the temperature transition interface is located at the bottom of downstream zone 2, indicating that there is significant potential for energy savings in the air-cooling island. In this case, it is recommended to lower the fan frequency of all ACCs (e.g., 5 Hz) or perform differential fan adjustments on all ACCs (e.g., 3 Hz for downstream fans and 10 Hz for reverse fans).

[0097] The above is the air-cooled condenser fan adjustment strategy for a stable unit load and minimal environmental fluctuations. However, when the unit load changes rapidly or the environment changes suddenly, the air-cooled condenser fan adjustment strategy will be quickly adjusted according to the actual situation to meet the unit's safety and economic needs.

[0098] For the scheme of using the temperature parameter of the working state of the air-cooled condenser as the input signal of the control system to realize the closed-loop control of the fan, Figure 3 Based on the control system shown above, the corresponding fan automatic control system is constructed by adding corresponding temperature measurement points. Therefore, a separate illustration is not provided. For example:

[0099] 1. Fan control system with the difference between the air side outlet temperature of the air condenser and the ambient temperature as the input signal:

[0100] The readings of the temperature measuring element 6 and the readings of the ambient temperature measuring point are collected by the data acquisition device 10 and then sent to the data processing device 11. In the data processing device 11, the difference Δt1 between the average temperature of the measuring point downstream of the target position 9 of the temperature transition interface (upper part of the countercurrent zone 3) and the reading of the ambient temperature measuring point is calculated. At the same time, the difference Δt2 between the readings of the steam temperature measuring point and the ambient temperature measuring point is calculated. On this basis, the ratio k of Δt1 and Δt2 is calculated and sent to the signal conversion device 12. The signal conversion device 12 converts the instruction according to the size of the k value. When k≤0.05, the signal conversion device 12 sends a fan frequency reduction signal of 5×(1-k)Hz to the control device 13; when 0.05<k≤0.40, the signal conversion device 12 sends a fan frequency change signal of 0Hz to the control device 13; when k>0.40, the signal conversion device 12 sends a fan frequency increase signal of 5×kHz to the control device 13; the control device 13 controls the operation of the fan 8 according to the received fan frequency change signal.

[0101] In this system, the temperature difference signal can also be replaced by the difference between the average reading of the temperature measuring element at the target position 9 of the temperature transition interface and the ambient temperature; it can also be replaced by the difference between the reading of the steam temperature measuring point and the average reading of the temperature measuring element at the target position 9 of the temperature transition interface; it can also be replaced by the difference between the average reading of the temperature measuring element at the target position 9 of the temperature transition interface and the average reading of the temperature measuring element downstream of the target position 9 of the temperature transition interface. Because the steam inside the air-cooled condenser is wet steam, its pressure and temperature have a one-to-one correspondence, the steam temperature can also be obtained by converting the steam pressure. The temperature measuring element 6 can also be placed simultaneously in the upper part of the countercurrent zone 3 and the lower part of the downstream zone 2.

[0102] 2. Fan control system with the difference between the air-cooled condenser steam temperature and the exhaust temperature as the input signal:

[0103] The data acquisition device 10 collects the readings of the temperature measuring element located on the air condenser exhaust pipe 4 and the readings of the steam temperature measuring point, and then sends them to the data processing device 11. In the data processing device 11, the difference Δt3 between the reading of the steam temperature measuring point and the reading of the exhaust temperature measuring point is calculated, and the difference Δt2 between the reading of the steam temperature measuring point and the reading of the ambient temperature measuring point is calculated. On this basis, the ratio k1 of Δt3 to Δt2 is calculated and sent to the signal conversion device 12. The signal conversion device 12 converts the difference Δt3 between the reading of the steam temperature measuring point and the reading of the ambient temperature measuring point into the value of the ratio k1. According to the size conversion instruction of the k1 value, when k1≤0.25, the signal conversion device 12 sends a fan frequency increase signal 5×(1-k1)Hz to the control device 13; when 0.25<k1≤0.45, the signal conversion device 12 sends a fan frequency change signal 0Hz to the control device 13; when k1>0.45, the signal conversion device 12 sends a fan frequency reduction signal 5×k1Hz to the control device 13; the control device 13 controls the operation of the fan 8 according to the received fan frequency change signal.

[0104] In this system, the temperature difference signal can also be replaced by the difference between the reading of the exhaust temperature measurement point and the ambient temperature. Because the steam inside the air-cooled condenser is wet steam, its pressure and temperature have a one-to-one correspondence, so the steam temperature can also be obtained by converting the steam pressure.

[0105] In this system, the reading of the exhaust temperature measurement point can also be used as the input signal. Because the steam inside the air-cooled condenser is wet steam, its pressure and temperature have a one-to-one correspondence, so the steam temperature can also be obtained by converting the steam pressure.

[0106] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the technical principles of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. An automatic control method for an air-cooled condenser fan, characterized in that: include: Step 1, obtaining characteristic parameters of the working state of the air-cooled condenser; wherein, the characteristic parameters are the position of the temperature transition interface or the position deviation of the temperature transition interface; wherein, the temperature transition interface refers to a temperature rapidly changing area somewhere in the fin tube of the air-cooled condenser, along the steam flow direction in the fin tube, upstream of the area, the steam temperature in the fin tube is close to the saturation temperature and basically unchanged; downstream of the area, the steam temperature in the fin tube is close to the ambient temperature and also basically unchanged; the distance from the inlet to the outlet of the area along the length direction of the fin tube is very short, and the temperature drops rapidly from the upstream close to the steam saturation temperature to the downstream close to the ambient temperature, and the temperature gradient is very large; since the axial distance of the area along the fin tube is very short, it is called the temperature transition interface here; the temperature transition interface position deviation is the distance difference between the temperature transition interface position and the target position of the temperature transition interface; Step 2: Using the characteristic parameter as an input signal, the signal is converted into a fan frequency signal, a fan voltage signal, or a fan current signal after processing to perform fan closed-loop control until the signal matches the target characteristic parameter. The method for obtaining the temperature transition interface position in step 1 includes: The position of the temperature transition interface is determined by comparing the difference in measured data of two adjacent rows of temperature measuring elements in the countercurrent zone: When the difference in the measured data of two adjacent rows of temperature measuring elements in the countercurrent zone is significantly greater than the difference in the measured data of other two adjacent rows of temperature measuring elements, the temperature transition interface is determined to be located between the two adjacent rows of temperature measuring elements; when the measured data of the temperature measuring elements in the lower part of the downstream zone are close to the ambient temperature or at least 5°C lower than the steam temperature, the temperature transition interface is determined to be located at the steam side outlet of the downstream zone.

2. The air-cooled condenser fan automatic control method according to claim 1, characterized in that: The method for obtaining the position of the temperature transition interface in step 1 includes: By comparing the temperature differences between different measuring points, the position of the temperature transition interface can be determined: When the temperature difference between the downstream measuring point and any height measuring point in the countercurrent area exceeds the set value, the temperature transition interface is determined to be located between the most upstream position in the steam flow direction in the air-cooled condenser and its adjacent upstream position among all positions where the temperature difference between the downstream measuring point and the countercurrent measuring point exceeds the set value; When the temperature difference between the temperature measuring point at the lower part of the downstream zone and the steam temperature inside the steam distribution pipe exceeds the set value, it is determined that the temperature transition interface is located at the steam side outlet of the downstream zone.

3. The automatic control method for the air-cooled condenser fan according to claim 1, characterized in that: The method for obtaining the position of the temperature transition interface in step 1 includes: An infrared thermal imager is used to measure the temperature field of the air-cooled condenser. Based on the significant color difference between the upstream and downstream parts of the image, the location where the color changes rapidly is identified as the temperature transition interface.

4. The automatic control method for the air-cooled condenser fan according to claim 1, characterized in that: The control strategy in step 2 using the temperature transition interface position as an input signal includes: When the temperature transition interface position is upstream of the temperature transition interface target position, reduce the fan output until the deviation between the temperature transition interface position and the temperature transition interface target position is less than the set value; when the temperature transition interface position is downstream of the temperature transition interface target position, increase the fan output until the deviation between the temperature transition interface position and the temperature transition interface target position is less than the set value; wherein, the temperature transition interface target position is located 2m downstream from the steam side outlet of the downstream area of the air-to-condenser to the steam side outlet of the countercurrent area.

5. The automatic control method for the air-cooled condenser fan according to claim 4, characterized in that: The control strategy using the temperature transition interface position as an input signal in step 2 further includes: When the temperature transition interface is located in the downstream area, the output of multiple fans is adjusted simultaneously; when the temperature transition interface is located in the upstream area, the output of one or more fans is adjusted.

6. An automatic control system for an air-cooled condenser fan, characterized in that: It includes an air-to-condenser temperature transition interface capture device, a signal conversion device, and a control device; the condenser temperature transition interface capture device includes a temperature measuring element, a data acquisition device, and a data processing device arranged at the air-to-condenser air-side outlet across the downstream and upstream areas; the temperature measuring element, the data acquisition device, the data processing device, the signal conversion device, and the control device are connected in sequence, and the control device is connected to the fan of the air-to-condenser; The data acquisition device is used to collect temperature measurement data of the temperature measuring element and transmit the temperature measurement data to the data processing device; The data processing device is used to obtain temperature transition interface position information based on the temperature measurement data, and transmit the temperature transition interface position information to the signal conversion device; wherein, the temperature transition interface refers to a temperature rapidly changing area somewhere in the fin tube of the air-cooled condenser. Along the steam flow direction in the fin tube, upstream of the area, the steam temperature in the fin tube is close to the saturation temperature and basically unchanged; downstream of the area, the steam temperature in the fin tube is close to the ambient temperature and also basically unchanged; the distance from the inlet to the outlet of the area along the length direction of the fin tube is very short, and the temperature drops rapidly from the upstream close to the steam saturation temperature to the downstream close to the ambient temperature, and the temperature gradient is very large; given that the axial distance of this area along the fin tube is very short, it is referred to as the temperature transition interface here; The signal conversion device is used to convert the temperature transition interface position information into a fan frequency signal, a fan voltage signal or a fan current signal, and transmit the converted signal to the control device; The control device is used to use the fan frequency signal, fan voltage signal or fan current signal output by the signal conversion device as an input signal to execute the following fan closed-loop control strategy: When the temperature transition interface position is upstream of the temperature transition interface target position, reduce the fan output until the deviation between the temperature transition interface position and the temperature transition interface target position is less than the set value; when the temperature transition interface position is downstream of the temperature transition interface target position, increase the fan output until the deviation between the temperature transition interface position and the temperature transition interface target position is less than the set value.

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