Evaluation Method and Device for Heat Transfer Efficiency of Vacuum Heat Pipe Low-Temperature Economizer

Abstract

The present invention provides a method and device for evaluating the heat transfer efficiency of a vacuum heat pipe low-temperature economizer. The actual heat transfer coefficients and theoretical heat transfer coefficients of each economizer are calculated and fitted to obtain a fitting curve. The difference sequence between each actual heat transfer coefficient and the fitting curve is calculated and fitted to obtain a difference sequence curve. Based on the difference sequence curve, it is determined whether the heat transfer efficiency has decreased. If so, the operating parameters are input into the leakage classification model, and a leakage mark or non-leakage mark corresponding to the operating parameters is output. When the non-leakage mark is output, the corresponding text is calculated and output based on the resistance coefficients of each vacuum heat pipe low-temperature economizer. In this solution, when it is measured that the heat transfer efficiency has decreased, the pre-constructed leakage classification model is used to evaluate whether the vacuum heat pipe low-temperature economizer leaks. If not, the text characterizing the factors affecting the heat transfer efficiency is obtained by analyzing the resistance coefficients, so as to achieve the purpose of quickly and accurately analyzing the reason for the decrease in the heat transfer efficiency of the vacuum heat pipe low-temperature economizer.

Description

Technical Field

[0001] The present invention relates to the technical field of flue gas treatment, and particularly relates to a method and device for evaluating the heat transfer efficiency of a vacuum heat pipe low-temperature economizer. Background Art

[0002] As the operation time of the vacuum heat pipe low-temperature economizer increases, the problem of heat pipe failure will occur. Therefore, it is necessary to regularly evaluate the heat transfer efficiency of the heat pipe.

[0003] At present, the evaluation of the heat transfer efficiency of the vacuum heat pipe low-temperature economizer relies on manual regular inspection of various operation parameters of the economizer, and determines whether the heat transfer efficiency of the economizer has decreased by comparing the operation parameters with historical data. This method of manual inspection not only takes time and effort, but is also prone to misjudgment, and when the heat transfer efficiency decreases, the reason for the decrease in heat transfer efficiency cannot be analyzed in time.

[0004] Therefore, in the current process of manually evaluating the heat transfer efficiency of the vacuum heat pipe low-temperature economizer, the problems of time-consuming, laborious, prone to misjudgment, and inability to analyze the reason for the decrease in heat transfer efficiency in time are urgent problems to be solved at present. Summary of the Invention

[0005] In view of this, embodiments of the present invention provide a method and device for evaluating the heat transfer efficiency of a vacuum heat pipe low-temperature economizer, so as to achieve the purpose of quickly and accurately analyzing the reason for the decrease in the heat transfer efficiency of the vacuum heat pipe low-temperature economizer.

[0006] To achieve the above purpose, embodiments of the present invention provide the following technical solutions:

[0007] The first aspect of the embodiments of the present invention discloses a method for evaluating the heat transfer efficiency of a vacuum heat pipe low-temperature economizer, including:

[0008] Obtain the operation parameters during the operation period of the vacuum heat pipe low-temperature economizer;

[0009] Based on the operation parameters and the photothermal balance formula, calculate the actual heat transfer coefficients of the vacuum heat pipe low-temperature economizer at preset time intervals during the operation period;

[0010] Based on the thermal resistance parameters of the vacuum heat pipe low-temperature economizer, calculate the theoretical heat transfer coefficients of the vacuum heat pipe low-temperature economizer at preset time intervals during the operation period;

[0011] Use the least squares method to fit the theoretical heat transfer coefficient and the actual heat transfer coefficient to obtain a fitting curve;

[0012] Calculate the difference sequence between each actual heat transfer coefficient and the fitting curve, and fit the difference sequence to obtain a difference sequence curve;

[0013] Based on the difference sequence curve and the difference sequence curve when the heat transfer efficiency of the vacuum heat pipe low-temperature economizer decreases, determine whether the heat transfer efficiency of the vacuum heat pipe low-temperature economizer decreases;

[0014] If the heat transfer efficiency of the vacuum heat pipe low-temperature economizer decreases, input the operating parameters into a pre-constructed leakage classification model for analysis, and output a leakage mark or a non-leakage mark corresponding to the operating parameters; the leakage mark is used to indicate that the vacuum heat pipe low-temperature economizer leaks, and the non-leakage mark is used to indicate that the vacuum heat pipe low-temperature economizer does not leak;

[0015] When the leakage classification model outputs a non-leakage mark, calculate the respective resistance coefficients of the vacuum heat pipe low-temperature economizer during the operating period based on the operating parameters;

[0016] Output corresponding text information based on the respective resistance coefficients, and the text information is used to characterize the factors for the decrease in the heat transfer efficiency of the vacuum heat pipe low-temperature economizer.

[0017] Preferably, the determining whether the heat transfer efficiency of the vacuum heat pipe low-temperature economizer decreases based on the difference sequence curve and the difference sequence curve when the heat transfer efficiency of the vacuum heat pipe low-temperature economizer decreases includes:

[0018] Compare the data set of the difference sequence curve in a two-dimensional coordinate with a preset target data set to obtain the deviation degree of the difference sequence curve;

[0019] Obtain the difference sequence curve when the heat transfer efficiency of the vacuum heat pipe low-temperature economizer decreases from historical data;

[0020] Calculate the similarity between the difference sequence curve and the difference sequence curve when the heat transfer efficiency decreases based on the dynamic time warping algorithm;

[0021] Perform a weighted calculation on the deviation degree and the similarity to obtain a weighted calculation result;

[0022] If the weighted calculation result exceeds a preset threshold, determine that the heat transfer efficiency of the vacuum heat pipe low-temperature economizer decreases.

[0023] Preferably, the calculating the respective resistance coefficients of the vacuum heat pipe low-temperature economizer during the operating period based on the operating parameters when the leakage classification model outputs a non-leakage mark includes:

[0024] When the leakage classification model outputs a non-leakage mark, calculate the resistance coefficients of the vacuum heat pipe low-temperature economizer at preset time intervals during the operating period based on the principles of fluid mechanics and the flue gas differential pressure, flue gas density, and flue gas flow rate in the operating parameters.

[0025] Preferably, corresponding text information is output based on each resistance coefficient, and the text information is used to characterize the factors causing the decline in the heat transfer efficiency of the vacuum heat pipe low-temperature economizer, including:

[0026] Based on each resistance coefficient during the operation period, the change trend of each resistance coefficient is obtained;

[0027] When the resistance coefficient shows an upward trend, text information indicating that the decline in the heat transfer efficiency of the vacuum heat pipe low-temperature economizer is caused by excessive ash accumulation is output;

[0028] When the resistance coefficient has no change trend, text information indicating that the decline in the heat transfer efficiency of the vacuum heat pipe low-temperature economizer is caused by the generation of non-condensable gases is output.

[0029] Preferably, the construction process of the leakage classification model includes:

[0030] Obtain the historical operation parameters of the vacuum heat pipe low-temperature economizer;

[0031] Based on the information recorded in the historical maintenance log, screen out the first sample data with a leakage mark from the historical operation parameters, and the leakage mark is used to indicate that the vacuum heat pipe low-temperature economizer has a leakage;

[0032] Based on the information recorded in the historical maintenance log, screen out the second sample data with a non-leakage mark from the historical operation parameters, and the non-leakage mark is used to indicate that the vacuum heat pipe low-temperature economizer has no leakage;

[0033] Split the first sample data and the second sample data to obtain multiple first sample data segments with a preset length and multiple second sample data segments;

[0034] Input multiple first sample data segments or multiple second sample data segments into the initial convolutional layer for training, and output corresponding abstract features;

[0035] Input the abstract features into the initial LeakyRelu function layer for training, and output abstract features with increased non-linearity;

[0036] Input the abstract features with increased non-linearity into the initial max-pooling layer for training, and output the data features corresponding to the data segments;

[0037] Input the data features into the initial fully connected layer for training, and output the first mark corresponding to the first sample data segment or the second mark corresponding to the second sample data segment;

[0038] Determine whether the first marker is a leakage marker or whether the second marker is a non - leakage marker;

[0039] If both are, obtain a leakage classification model constructed by a convolutional layer, a LeakyRelu function layer, a max - pooling layer, and a fully - connected layer;

[0040] If either is not, perform iterative training on the convolutional layer, the LeakyRelu function layer, the max - pooling layer, and the fully - connected layer until the first marker output by the leakage classification model constructed by the convolutional layer, the LeakyRelu function layer, the max - pooling layer, and the fully - connected layer is a leakage marker, or the second marker output is a non - leakage marker.

[0041] In the second aspect of the embodiments of the present invention, an evaluation device for the heat transfer efficiency of a vacuum heat pipe low - temperature economizer is disclosed, including:

[0042] An acquisition unit, configured to acquire the operating parameters during the operation period of the vacuum heat pipe low - temperature economizer;

[0043] A first calculation unit, configured to calculate, based on the operating parameters and the light - heat balance formula, the respective actual heat transfer coefficients of the vacuum heat pipe low - temperature economizer at preset time intervals during the operation period;

[0044] A second calculation unit, configured to calculate, based on the thermal resistance parameters of the vacuum heat pipe low - temperature economizer, the respective theoretical heat transfer coefficients of the vacuum heat pipe low - temperature economizer at preset time intervals during the operation period;

[0045] A first fitting unit, configured to fit the theoretical heat transfer coefficients and the actual heat transfer coefficients using the least - squares method to obtain a fitting curve;

[0046] A second fitting unit, configured to calculate a difference sequence between each actual heat transfer coefficient and the fitting curve, and fit the difference sequence to obtain a difference sequence curve;

[0047] A judgment unit, configured to judge whether the heat transfer efficiency of the vacuum heat pipe low - temperature economizer has decreased based on the difference sequence curve when the heat transfer efficiency of the vacuum heat pipe low - temperature economizer decreases and the difference sequence curve;

[0048] An analysis unit, configured to, if the heat transfer efficiency of the vacuum heat pipe low - temperature economizer has decreased, input the operating parameters into a pre - constructed leakage classification model for analysis, and output a leakage marker or a non - leakage marker corresponding to the operating parameters; the leakage marker is used to indicate that the vacuum heat pipe low - temperature economizer has leaked, and the non - leakage marker is used to indicate that the vacuum heat pipe low - temperature economizer has not leaked;

[0049] A third calculation unit, configured to calculate, based on the operating parameters, each resistance coefficient of the vacuum heat pipe low-temperature economizer during the operating period when the leakage classification model outputs an un-leakage mark;

[0050] An output unit, configured to output corresponding text information based on each resistance coefficient, where the text information is used to characterize factors causing a decrease in the heat transfer efficiency of the vacuum heat pipe low-temperature economizer.

[0051] Preferably, the determination unit includes:

[0052] A comparison subunit, configured to compare a data set of the difference sequence curve in a two-dimensional coordinate with a preset target data set to obtain the deviation degree of the difference sequence curve;

[0053] An acquisition subunit, configured to acquire the difference sequence curve when the heat transfer efficiency of the vacuum heat pipe low-temperature economizer decreases from historical data;

[0054] A first calculation subunit, configured to calculate the similarity between the difference sequence curve and the difference sequence curve when the heat transfer efficiency decreases based on the dynamic time warping algorithm;

[0055] A second calculation subunit, configured to perform weighted calculation on the deviation degree and the similarity to obtain a weighted calculation result;

[0056] A determination subunit, configured to determine that the heat transfer efficiency of the vacuum heat pipe low-temperature economizer decreases when the weighted calculation result exceeds a preset threshold.

[0057] Preferably, the third calculation unit is specifically configured to:

[0058] When the leakage classification model outputs an un-leakage mark, calculate the resistance coefficient of the vacuum heat pipe low-temperature economizer at preset time intervals during the operating period based on the principle of fluid mechanics and the flue gas differential pressure, flue gas density, and flue gas flow rate in the operating parameters.

[0059] Preferably, the output unit is specifically configured to:

[0060] Based on each resistance coefficient during the operating period, obtain the change trend of each resistance coefficient; when the resistance coefficient shows an upward trend, output text information indicating that the decrease in the heat transfer efficiency of the vacuum heat pipe low-temperature economizer is caused by excessive ash accumulation; when the resistance coefficient has no change trend, output text information indicating that the decrease in the heat transfer efficiency of the vacuum heat pipe low-temperature economizer is caused by the generation of non-condensable gases.

[0061] Preferably, it further includes:

[0062] A preprocessing unit for obtaining historical operation parameters of the vacuum heat pipe low-temperature economizer; screening out first sample data with a leakage mark from the historical operation parameters based on information recorded in the historical maintenance log, where the leakage mark is used to indicate that the vacuum heat pipe low-temperature economizer has a leakage; screening out second sample data with a non-leakage mark from the historical operation parameters based on information recorded in the historical maintenance log, where the non-leakage mark is used to indicate that the vacuum heat pipe low-temperature economizer has no leakage; splitting the first sample data and the second sample data to obtain multiple first sample data segments and multiple second sample data segments of a preset length;

[0063] A training unit for sequentially inputting multiple first sample data segments or multiple second sample data segments into an initial convolutional layer for training and outputting corresponding abstract features; inputting the abstract features into an initial LeakyRelu function layer for training and outputting abstract features with increased non-linearity; inputting the abstract features with increased non-linearity into an initial max pooling layer for training and outputting data features corresponding to the data segments; inputting the data features into an initial fully connected layer for training and outputting a first mark corresponding to the first sample data segment or a second mark corresponding to the second sample data segment; determining whether the first mark is a leakage mark or the second mark is a non-leakage mark; if both are, obtaining a leakage classification model constructed by a convolutional layer, a LeakyRelu function layer, a max pooling layer, and a fully connected layer; if either is not, performing iterative training on the convolutional layer, the LeakyRelu function layer, the max pooling layer, and the fully connected layer until the first mark output by the leakage classification model constructed by the convolutional layer, the LeakyRelu function layer, the max pooling layer, and the fully connected layer is a leakage mark or the second mark output is a non-leakage mark.

[0064] Based on the evaluation method and device for the heat transfer efficiency of a vacuum heat pipe low-temperature economizer provided in the embodiments of the present invention, the operating parameters during the operation period of the vacuum heat pipe low-temperature economizer are obtained; based on the operating parameters and the light-heat balance formula, the actual heat transfer coefficients of the vacuum heat pipe low-temperature economizer at preset time intervals during the operation period are calculated; based on the thermal resistance parameters of the vacuum heat pipe low-temperature economizer, the theoretical heat transfer coefficients of the vacuum heat pipe low-temperature economizer at preset time intervals during the operation period are calculated; the least squares method is used to fit the theoretical heat transfer coefficients and the actual heat transfer coefficients to obtain a fitting curve; the difference sequence between each actual heat transfer coefficient and the fitting curve is calculated, and the difference sequence curve is fitted for the difference sequence; based on the difference sequence curve when the heat transfer efficiency of the vacuum heat pipe low-temperature economizer decreases and the difference sequence curve, it is determined whether the heat transfer efficiency of the vacuum heat pipe low-temperature economizer decreases; if the heat transfer efficiency of the vacuum heat pipe low-temperature economizer decreases, the operating parameters are input into a pre-constructed leakage classification model for analysis, and a leakage mark or non-leakage mark corresponding to the operating parameters is output; when the leakage classification model outputs a non-leakage mark, based on the operating parameters, the resistance coefficients of the vacuum heat pipe low-temperature economizer during the operation period are calculated; corresponding text information is output based on each resistance coefficient, and the text information is used to characterize the factors causing the decrease in the heat transfer efficiency of the vacuum heat pipe low-temperature economizer. In this solution, the heat transfer coefficient is measured based on the operating parameters and compared with historical data to determine whether the heat transfer efficiency of the vacuum heat pipe low-temperature economizer decreases. If the efficiency decreases, a pre-constructed leakage classification model is used to evaluate whether the vacuum heat pipe low-temperature economizer leaks. If there is no leakage, the text characterizing the factors affecting the heat transfer efficiency is obtained by analyzing the resistance coefficients, so as to achieve the purpose of quickly and accurately analyzing the reasons for the decrease in the heat transfer efficiency of the vacuum heat pipe low-temperature economizer. BRIEF DESCRIPTION OF THE DRAWINGS

[0065] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings required for use in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings in the following description are only the embodiments of the present invention. For those of ordinary skill in the art, other drawings can be obtained according to the provided drawings without creative efforts.

[0066] Figure 1 It is a schematic diagram of the heat transfer principle of a vacuum heat pipe low-temperature economizer disclosed in an embodiment of the present invention;

[0067] Figure 2 It is a flowchart of an evaluation method for the heat transfer efficiency of a vacuum heat pipe low-temperature economizer disclosed in an embodiment of the present invention;

[0068] Figure 3Flowchart of a method for constructing a leakage classification model disclosed in an embodiment of the present invention;

[0069] Figure 4 Structural diagram of an evaluation device for the heat transfer efficiency of a vacuum heat pipe low-temperature economizer disclosed in an embodiment of the present invention. Detailed implementation manners

[0070] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0071] In this application, the terms "comprising", "including" or any other variant thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements not only includes those elements, but also includes other elements not expressly listed, or further includes elements inherent to such process, method, article or device. Without further limitation, the element defined by the statement "including one..." does not exclude the existence of additional identical elements in the process, method, article or device including the element.

[0072] As can be seen from the background technology, in the current process of manually evaluating the heat transfer efficiency of a vacuum heat pipe low-temperature economizer, there are problems of time-consuming and laborious, easy misjudgment, and inability to timely analyze the reasons for the decrease in heat transfer efficiency.

[0073] Therefore, an embodiment of the present invention discloses an evaluation method and device for the heat transfer efficiency of a vacuum heat pipe low-temperature economizer. In this solution, by obtaining the operating parameters during the operation period of the vacuum heat pipe low-temperature economizer, calculating based on the operating parameters and comparing with historical data, it is judged whether the heat transfer efficiency of the vacuum heat pipe low-temperature economizer has decreased. If the efficiency has decreased, a pre-constructed leakage classification model is used to evaluate whether the vacuum heat pipe low-temperature economizer is leaking. If there is no leakage, the factors affecting the heat transfer efficiency are analyzed through the resistance coefficient, so as to achieve the purpose of quickly and accurately analyzing the reasons for the decrease in the heat transfer efficiency of the vacuum heat pipe low-temperature economizer. This will be described in detail through the following embodiments.

[0074] As Figure 1 shown, it is a schematic diagram of the heat transfer principle of a vacuum heat pipe low-temperature economizer disclosed in an embodiment of the present invention.

[0075] In an embodiment of the present invention, the vacuum heat pipe low-temperature economizer is composed of a heat pipe 1, a water pipe sleeve 2 and an adiabatic section 3. Among them, a working medium is injected into the heat pipe 1, and the adiabatic section 3 divides the heat pipe 1 into a condensation side and an evaporation side, and a water pipe sleeve 2 is sleeved on the heat pipe 1 on the condensation side.

[0076] The water pipe sleeve 1 uses cooling water to cool the condensation section of the heat pipe 1, causing the vaporous working medium inside the condensation side of the heat pipe 1 to condense into a liquid working medium, which then falls to the evaporation side of the heat pipe 1 under the action of gravity. The evaporation side of the heat pipe 1 is in direct contact with the high-temperature flue gas and absorbs the heat in the flue gas, causing the liquid working medium inside the evaporation side of the heat pipe 1 to vaporize into a vaporous working medium and rise to the condensation section.

[0077] Specifically, the heat exchange process of the vacuum heat pipe low-temperature economizer is as follows:

[0078] Evaporation heat absorption process: When the high-temperature flue gas heats the evaporation section, the working medium inside the heat pipe 1 absorbs the latent heat of vaporization and changes from a liquid to a vapor.

[0079] Condensation heat release process: The vapor automatically rises to the condensation section under the push of the pressure difference inside the heat pipe 1. The vapor condenses into a liquid when it encounters the water-cooled wall surface, and at the same time releases the latent heat of vaporization, and transfers the heat to the cooling water outside the pipe through the pipe wall.

[0080] After condensation, the working medium of the heat pipe 1 automatically returns to the evaporation section under the action of gravity and starts the above evaporation heat absorption process again, repeating the cycle.

[0081] Based on Figure 1 As shown in the heat exchange principle of a certain vacuum heat pipe low-temperature economizer, as Figure 2 shown, it is a flowchart of a method for evaluating the heat exchange efficiency of a vacuum heat pipe low-temperature economizer disclosed in an embodiment of the present invention. This method mainly includes the following steps:

[0082] Step S201: Obtain the operating parameters during the operation period of the vacuum heat pipe low-temperature economizer.

[0083] In step S201, the operating parameters at least include the inlet flue gas temperature of each flue, the outlet flue gas temperature of each flue, the inlet water temperature of the inlet pipe, the outlet water temperature of the return pipe, the flow rate of the inlet pipe, the flow rate of the return pipe, the flue differential pressure, the opening degree of the electric control valve of the heat exchanger inlet pipe, and the corresponding boiler system parameters.

[0084] Among them, the boiler system parameters include parameters such as load and coal consumption.

[0085] Step S202: Based on the operating parameters and the light-heat balance formula, calculate the actual heat transfer coefficients of the vacuum heat pipe low-temperature economizer at preset time intervals during the operation period.

[0086] In step S202, the light-heat balance formula is as follows:

[0087] Q = KAAt1 (1)

[0088] Among them, Q is the heat exchange power of the heat exchanger, K is the actual heat transfer coefficient of the vacuum heat pipe low-temperature economizer, A is the heat transfer area on the flue gas side of the vacuum heat pipe low-temperature heat exchanger, Δt1 is the logarithmic mean temperature difference for heat transfer, and the calculation formula for Δt1 is:

[0089]

[0090] In formula (2), t1 is the inlet flue gas temperature, t2 is the outlet flue gas temperature, t3 is the inlet water temperature, and t4 is the outlet water temperature.

[0091] In the process of specifically implementing step S202, every preset time interval, for example, every five minutes, the actual heat transfer coefficient K is calculated once based on the currently real-time obtained operating parameters of the vacuum heat pipe low-temperature economizer and formula (1). The specific calculation process for each calculation of the actual heat transfer coefficient K is as follows:

[0092] Formula (1) can be converted into:

[0093] Q = C Ps × m s × Δt2 (3)

[0094] Among them, C Ps is the water heat ratio at the qualitative water temperature of the vacuum heat pipe low-temperature economizer, that is, c Ps = f(t s ), t s is the qualitative water temperature, generally taking the arithmetic mean temperature of the inlet water temperature and the outlet water temperature, that is C can be calculated through the inlet water temperature and the outlet water temperature in the operating parameters Ps ; Δt2 is the difference between the inlet water temperature and the outlet water temperature, that is, Δt2 = t4 - t3, and Δt2 can be calculated through the inlet water temperature and the outlet water temperature in the operating parameters.

[0095] m s is the total amount of water passing through the vacuum heat pipe low-temperature economizer, and the calculation unit of m s is kg / s, and the calculation formula is:

[0096]

[0097] Among them, m s* is the amount of water passing through each module of the vacuum heat pipe low-temperature economizer, θ * is the distribution coefficient, and the calculation formula for θ * is:

[0098]

[0099] Among them, OP1 to OP i represent the valve openings of each module, which can be obtained from the operating parameters and substituted into formula (5) to calculate the distribution coefficient θ* The value of

[0100] Substitute the distribution coefficient θ * into formula (4), and the total water volume m of the vacuum heat pipe low-temperature economizer can be obtained. s .

[0101] Combining formula (1) and formula (3), it can be obtained that:

[0102]

[0103] Among them, the heat transfer area A on the flue gas side of the vacuum heat pipe low-temperature heat exchanger can be obtained through actual measurement and calculation. The temperature difference Δt1 between the inlet water temperature and the outlet water temperature is obtained by substituting the inlet flue gas temperature, outlet flue gas temperature, inlet water temperature and outlet water temperature in the operating parameters into formula (2).

[0104] Substitute the heat transfer area A on the flue gas side of the vacuum heat pipe low-temperature heat exchanger, the logarithmic mean temperature difference Δt1 of heat transfer, the water heat ratio C at the qualitative water temperature of the vacuum heat pipe low-temperature economizer Ps , the temperature difference Δt2 between the inlet water temperature and the outlet water temperature, and the total water volume m passing through the vacuum heat pipe low-temperature economizer s into formula (6), and calculate the actual heat transfer coefficient K of the vacuum heat pipe low-temperature economizer at the current time point.

[0105] Step S203: Based on the thermal resistance parameters of the vacuum heat pipe low-temperature economizer, calculate the respective theoretical heat transfer coefficients of the vacuum heat pipe low-temperature economizer at preset time intervals during the operation period.

[0106] In step S203, the thermal resistance parameters include the flue gas thermal resistance, fouling thermal resistance, flue gas side tube wall thermal resistance, evaporation thermal resistance, condensation thermal resistance, water side tube wall thermal resistance and water side thermal resistance of the vacuum heat pipe low-temperature economizer.

[0107] In the specific process of implementing step S203, the calculation formula for the theoretical heat transfer coefficient K0 at any time point during the operation period is:

[0108]

[0109] Among them, R y is the flue gas thermal resistance, R h is the fouling thermal resistance, R b1 is the flue gas side tube wall thermal resistance, R zf is the evaporation thermal resistance, R ln is the condensation thermal resistance, R b2 is the water side tube wall thermal resistance, R s is the water side thermal resistance.

[0110] Specifically, R y and R h are calculated together, and the calculation formula is as follows:

[0111]

[0112] Among them, α y2 The heat transfer coefficient is based on the light tube, and the calculation formula is:

[0113] α y2 =η×α y1 (9)

[0114] Where η is the finning ratio, which is the multiple of the surface area of the light tube after the fins are added, and α is the ratio of the surface area of the light tube after the fins are added. y1 α is the heat transfer coefficient after considering the structure, dust pollution and radiation of the light tube. y1 The calculation formula is:

[0115] α y1 =f(ω y , t y ) (10)

[0116] Among them, ω y is the net flow velocity of the heat exchanger tube section, t y As the qualitative smoke temperature, take the arithmetic mean temperature of the inlet water temperature and the outlet water temperature, that is, ω y The calculation formula is:

[0117]

[0118] Among them, FR y is the working flue gas flow rate, FR y The calculation formula is:

[0119]

[0120] Among them, FR y0 is the standard flue gas flow rate, FR y0 The calculation formula is:

[0121] FR y0 =FR y0b ×0.96 (13)

[0122] Among them, FR y0b It is the measurement point value of the flue gas flow at the inlet of FGD, i.e., flue gas desulfurization device.

[0123] In formula (12), ρ y is the smoke density, ρ y The calculation formula is:

[0124]

[0125] Among them, ty is the same as the qualitative flue gas temperature in formula (10). The calculation method can be found in formula (10). y

[0126] Combining the calculations of formulas (8) to (14), R can be obtained. y +R h value.

[0127] In formula (7), the expression of the water-side thermal resistance R s is as follows:

[0128] R s = f(α s ) (15)

[0129] where α s is the water-side heat transfer coefficient. The expression of α s is as follows:

[0130] α s = f(w s , λ s ) (16)

[0131] where w s is the water flow velocity in the water-side pipe sleeve. The calculation formula of w s is:

[0132]

[0133] where FR s is the water-side volume flow rate. The calculation formula of FR s is:

[0134]

[0135] where ρ s is the density of the water working medium. The calculation formula of ρ s is:

[0136]

[0137] In formula (16), λ s is the thermal conductivity of the water working medium. The calculation formula of λ s is:

[0138]

[0139] The t s in formulas (19) and (20) is the qualitative water temperature mentioned above, generally taking the arithmetic mean temperature of the inlet water temperature and the outlet water temperature.

[0140] ​Combined with formulas (15) to (20), the water-side thermal resistance R of the vacuum heat pipe low-temperature economizer is calculated s .

[0141] The flue gas-side tube wall thermal resistance R in formula (7) b1 , the evaporation thermal resistance R zf , the condensation thermal resistance R ln , and the water-side tube wall thermal resistance R b2 are all well-known constant thermal resistances. Substitute these constant thermal resistances, the value of R y + R h obtained above, and the water-side thermal resistance R s obtained above into formula (7) to calculate the theoretical heat transfer coefficient K0 at the current time point.

[0142] Step S204: Use the least squares method to fit the theoretical heat transfer coefficient and the actual heat transfer coefficient to obtain a fitting curve.

[0143] In the specific implementation of step S204, use the least squares method to fit each theoretical heat transfer coefficient and each actual heat transfer coefficient at preset time intervals during the operation period to obtain a fitting curve. The expression of the fitting curve is as follows:

[0144]

[0145] where, a0 to a n are the fitting curve coefficients, and their values are calculated by fitting the scatter points of the theoretical heat transfer coefficient and the actual heat transfer coefficient.

[0146] Step S205: Calculate the difference sequence between each actual heat transfer coefficient and the fitting curve, and fit the difference sequence to obtain a difference sequence curve.

[0147] In step S205, the calculation formula for the difference sequence S is:

[0148] S = K - f(K0) (22)

[0149] In the specific implementation of step S205, based on formula (22), calculate the difference between the actual heat transfer coefficient and the corresponding value of the fitting curve at each time point during the operation period to obtain a difference sequence, and fit it into a difference sequence curve S.

[0150] Step S206: Based on the difference sequence curve and the difference sequence curve when the heat transfer efficiency of the vacuum heat pipe low-temperature economizer decreases, determine whether the heat transfer efficiency of the vacuum heat pipe low-temperature economizer has decreased.

[0151] In step S206, the difference sequence curve when the heat transfer efficiency of the vacuum heat pipe low-temperature economizer decreases is obtained from historical operation data.

[0152] In the process of specifically implementing step S206, the data set of the difference sequence curve in the two-dimensional coordinate is compared with the preset target data set, and the deviation degree of the difference sequence curve deviating from the target data set is calculated.

[0153] Compare the difference sequence curve when the heat transfer efficiency of the vacuum heat pipe low-temperature economizer decreases with the current difference sequence curve, and calculate the similarity between the two. The similarity calculation method is as follows:

[0154] Assume that the current difference sequence curve is S = (s1, s2,..., s n ), and the difference sequence curve when the heat transfer efficiency of the vacuum heat pipe low-temperature economizer decreases is S a = (s a1 , s a2 ,..., s am ). Using formula (23), calculate the Euclidean distance between the two. Formula (23) is as follows:

[0155] d(i, j) = Distance(s1, s a1 ) (23)

[0156] Based on the conversion of formula (23), it can be obtained:

[0157]

[0158] Among them, is the distorted curve. t pairs of corresponding points can be obtained from the two curves S and S a with different lengths. Finally, the similarity DTW between S and S a can be calculated using formula (25). Formula (25) is as follows:

[0159] DTW(S, S a ) = mind φ (S, S a ) (25)

[0160] Finally, perform weighted calculation on the deviation degree and the similarity. When the weighted calculation result exceeds the preset threshold, it is determined that the heat transfer efficiency of the vacuum heat pipe low-temperature economizer has decreased. When the weighted calculation result does not exceed the preset threshold, it is determined that the heat transfer efficiency of the vacuum heat pipe low-temperature economizer is normal.

[0161] Step S207: If the heat transfer efficiency of the vacuum heat pipe low-temperature economizer decreases, input the operating parameters into the pre-constructed leakage classification model for analysis, and output the leakage mark or non-leakage mark corresponding to the operating parameters.

[0162] In step S207, the leakage mark is used to indicate that the vacuum heat pipe low-temperature economizer has leaked, and the non-leakage mark is used to indicate that the vacuum heat pipe low-temperature economizer has not leaked.

[0163] Step S208: When the leakage classification model outputs an un-leakage mark, calculate the respective resistance coefficients of the vacuum heat pipe low-temperature economizer during the operation period based on the operating parameters.

[0164] In the specific process of implementing step S208, when the leakage classification model outputs an un-leakage mark, calculate the respective resistance coefficients at preset time intervals during the operation period.

[0165] Specifically, the calculation process of the resistance coefficient at each time point is as follows:

[0166] Based on the flue gas differential pressure, flue gas density, and flue gas flow velocity in the current operating parameters, and in combination with the principles of fluid mechanics, substitute the flue gas differential pressure, flue gas density, and flue gas flow velocity into formula (26) to calculate the resistance coefficient at the current time point, where formula (26) is:

[0167]

[0168] where, ΔP is the flue gas differential pressure, ρ y is the flue gas density, ω y is the net flow velocity of the heat exchanger tube cross-section.

[0169] Step S209: Output corresponding text information based on the respective resistance coefficients.

[0170] In step S209, the text information is used to characterize the factors causing the decline in the heat transfer efficiency of the vacuum heat pipe low-temperature economizer.

[0171] In the specific implementation of step S209, judge the change trend of the resistance coefficient of the vacuum heat pipe low-temperature economizer during the operation period.

[0172] When the resistance coefficient shows an upward trend, output text information indicating that the decline in the heat transfer efficiency of the vacuum heat pipe low-temperature economizer is due to excessive ash accumulation.

[0173] When the resistance coefficient has no change trend, output text information indicating that the decline in the heat transfer efficiency of the vacuum heat pipe low-temperature economizer is due to the generation of non-condensable gases.

[0174] For example, when in the initial operation period, the resistance coefficient is within the range of 1 to 5, and when at the end of the operation period, the resistance coefficient rises to the range of 15 to 20, it is determined that the resistance coefficient shows an upward trend.

[0175] Based on the method for evaluating the heat transfer efficiency of a vacuum heat pipe low-temperature economizer disclosed in the above embodiments of the present invention, in this solution, by obtaining the operating parameters during the operation period of the vacuum heat pipe low-temperature economizer, calculating based on the operating parameters and comparing with historical data, it is determined whether the heat transfer efficiency of the vacuum heat pipe low-temperature economizer has decreased. Further, if the efficiency has decreased, the operating parameters are input into a pre-constructed leakage classification model for evaluation to determine whether the vacuum heat pipe low-temperature economizer is leaking. If there is no leakage, by analyzing the resistance coefficient, text information characterizing the factors causing the decrease in heat transfer efficiency is output, so as to achieve the purpose of quickly and accurately analyzing the reasons for the decrease in the heat transfer efficiency of the vacuum heat pipe low-temperature economizer.

[0176] Based on the above embodiments of the present invention, as Figure 3 shown, it is a flowchart of a method for constructing a leakage classification model disclosed in an embodiment of the present invention. This method mainly includes the following steps:

[0177] Step S301: Obtain the historical operating parameters of the vacuum heat pipe low-temperature economizer;

[0178] Step S302: Based on the information recorded in the historical maintenance log, screen out the first sample data with a leakage mark and the second sample data with a non-leakage mark from the historical operating parameters.

[0179] In step S302, the leakage mark is used to indicate that the vacuum heat pipe low-temperature economizer has leaked, and the non-leakage mark is used to indicate that the vacuum heat pipe low-temperature economizer has not leaked.

[0180] Step S303: Split the first sample data to obtain multiple first sample data segments with a preset length, and split the second sample data to obtain multiple second sample data segments with a preset length.

[0181] Step S304: Input multiple first sample data segments with a preset length into the initial leakage classification model for training, and output the first mark corresponding to the first data segment. Input multiple second sample data segments with a preset length into the initial leakage classification model for training, and output the second mark corresponding to the second data segment.

[0182] In step S304, the initial leakage classification model includes an initial convolutional layer, a LeakyRelu function layer, a max pooling layer, and a fully connected layer.

[0183] Specifically, the process of inputting multiple first sample data segments with a preset length into the initial leakage classification model for training and outputting the first mark corresponding to the first data segment includes the following steps:

[0184] Step S11: Input multiple first sample data segments into the initial convolutional layer in sequence for training, and output the corresponding abstract features.

[0185] In step S11, the convolutional layer includes multiple 5*5 convolutional kernels.

[0186] Step S12: Input the abstract features into the initial LeakyRelu function layer for training, and output the abstract features with increased non-linearity.

[0187] In step S12, the expression of the LeakyRelu activation function used in the LeakyRelu function layer is: f(x) = max(0, x) + leak * min(0, x), where leak is a constant term.

[0188] Step S13: Input the abstract features with increased non-linearity into the initial max pooling layer for training, and output the data features corresponding to the data segments.

[0189] Step S14: Input the data features into the initial fully connected layer for training, and output the first label corresponding to the first sample data segment.

[0190] Specifically, the process of inputting multiple second sample data segments of preset lengths into the initial leakage classification model for training and outputting the second label corresponding to the second data segment includes the following steps:

[0191] Step S21: Input multiple second sample data segments into the initial convolutional layer for training in sequence, and output the corresponding abstract features.

[0192] In step S21, the convolutional layer includes multiple 5*5 convolutional kernels.

[0193] Step S22: Input the abstract features into the initial LeakyRelu function layer for training, and output the abstract features with increased non-linearity.

[0194] In step S22, the expression of the LeakyRelu activation function used in the LeakyRelu function layer is: f(x) = max(0, x) + leak * min(0, x), where leak is a constant term.

[0195] Step S23: Input the abstract features with increased non-linearity into the initial max pooling layer for training, and output the data features corresponding to the data segments.

[0196] Step S24: Input the data features into the initial fully connected layer for training, and output the second label corresponding to the second sample data segment.

[0197] Step S305: Determine whether the first label is a leakage label. If so, execute step S306; if not, execute step S307.

[0198] Step S306: Determine whether the second tag is an un-leaked tag. If so, obtain the leakage classification model; if not, execute Step S307.

[0199] It should be noted that the execution order of Step 305 and Step S306 is not limited. As long as it is determined through judgment that the first tag is a leaked tag and the second tag is an un-leaked tag, the leakage classification model can be obtained; otherwise, execute S307 to iteratively train the leakage classification model.

[0200] Step S307: Iteratively train the leakage classification model until the first tag output by the leakage classification model is a leaked tag and the second tag output is an un-leaked tag.

[0201] Based on the leakage classification model construction method disclosed in the embodiments of the present invention above, in this solution, sample data is obtained from historical data, and the initial leakage classification model is iteratively trained using the sample data until the leakage classification model outputs corresponding classification tags, and finally the trained leakage classification model is obtained.

[0202] Corresponding to the evaluation method of the heat transfer efficiency of the vacuum heat pipe low-temperature economizer disclosed in the embodiments of the present invention above, as Figure 4 shown, it is a structural diagram of an evaluation device for the heat transfer efficiency of a vacuum heat pipe low-temperature economizer disclosed in an embodiment of the present invention. The device includes: an acquisition unit 401, a first calculation unit 402, a second calculation unit 403, a first fitting unit 404, a second fitting unit 405, a judgment unit 406, an analysis unit 407, a third calculation unit 408, and an output unit 409.

[0203] The acquisition unit 401 is configured to acquire the operating parameters during the operation period of the vacuum heat pipe low-temperature economizer.

[0204] The first calculation unit 402 is configured to calculate, based on the operating parameters and the photothermal balance formula, the respective actual heat transfer coefficients of the vacuum heat pipe low-temperature economizer at preset time intervals during the operation period.

[0205] The second calculation unit 403 is configured to calculate, based on the thermal resistance parameters of the vacuum heat pipe low-temperature economizer, the respective theoretical heat transfer coefficients of the vacuum heat pipe low-temperature economizer at preset time intervals during the operation period.

[0206] The first fitting unit 404 is configured to fit the theoretical heat transfer coefficient and the actual heat transfer coefficient using the least squares method to obtain a fitting curve.

[0207] The second fitting unit 405 is configured to calculate the difference sequence between each actual heat transfer coefficient and the fitting curve, and fit the difference sequence to obtain a difference sequence curve.

[0208] A judgment unit 406, configured to judge whether the heat exchange efficiency of the vacuum heat pipe low-temperature economizer decreases based on the difference sequence curve and the difference sequence curve when the heat exchange efficiency of the vacuum heat pipe low-temperature economizer decreases.

[0209] In one embodiment, the judgment unit 406 includes: a comparison subunit, configured to compare the data set of the difference sequence curve in a two-dimensional coordinate with a preset target data set to obtain the deviation degree of the difference sequence curve.

[0210] An acquisition subunit, configured to acquire the difference sequence curve when the heat exchange efficiency of the vacuum heat pipe low-temperature economizer decreases from historical data.

[0211] A first calculation subunit, configured to calculate the similarity between the difference sequence curve and the difference sequence curve when the heat exchange efficiency decreases based on the dynamic time warping algorithm.

[0212] A second calculation subunit, configured to perform a weighted calculation on the deviation degree and the similarity to obtain a weighted calculation result.

[0213] A determination subunit, configured to determine that the heat exchange efficiency of the vacuum heat pipe low-temperature economizer decreases when the weighted calculation result exceeds a preset threshold.

[0214] An analysis unit 407, configured to input the operating parameters into a pre-constructed leakage classification model for analysis if the heat exchange efficiency of the vacuum heat pipe low-temperature economizer decreases, and output a leakage mark or a non-leakage mark corresponding to the operating parameters.

[0215] Wherein, the leakage mark is used to indicate that the vacuum heat pipe low-temperature economizer leaks, and the non-leakage mark is used to indicate that the vacuum heat pipe low-temperature economizer does not leak.

[0216] A third calculation unit 408, configured to calculate each resistance coefficient of the vacuum heat pipe low-temperature economizer during the operation period based on the operating parameters when the leakage classification model outputs a non-leakage mark.

[0217] Specifically, when the leakage classification model outputs a non-leakage mark, calculate the resistance coefficient of the vacuum heat pipe low-temperature economizer at a preset time interval during the operation period based on the fluid mechanics principle and the flue differential pressure, flue gas density and flue gas flow rate in the operating parameters.

[0218] An output unit 409, configured to output corresponding text information based on each resistance coefficient, and the text information is used to characterize the factors for the decrease of the heat exchange efficiency of the vacuum heat pipe low-temperature economizer.

[0219] Specifically, based on the resistance coefficients during the operation period, the change trends of the resistance coefficients are obtained; when the resistance coefficient shows an upward trend, text information indicating that the heat transfer efficiency of the vacuum heat pipe low-temperature economizer decreases due to excessive ash accumulation is output; when the resistance coefficient has no change trend, text information indicating that the heat transfer efficiency of the vacuum heat pipe low-temperature economizer decreases due to the generation of non-condensable gases is output.

[0220] In one embodiment, the heat transfer efficiency evaluation device of the vacuum heat pipe low-temperature economizer further includes a preprocessing unit, which is used to obtain the historical operation parameters of the vacuum heat pipe low-temperature economizer; based on the information recorded in the historical maintenance log, the first sample data with a leakage mark is screened out from the historical operation parameters; based on the information recorded in the historical maintenance log, the second sample data with no leakage mark is screened out from the historical operation parameters; the first sample data and the second sample data are segmented to obtain multiple first sample data segments with a preset length and multiple second sample data segments.

[0221] Among them, the leakage mark is used to indicate that the vacuum heat pipe low-temperature economizer leaks, and the no-leakage mark is used to indicate that the vacuum heat pipe low-temperature economizer does not leak.

[0222] The training unit is used to sequentially input multiple first sample data segments or multiple second sample data segments into the initial convolutional layer for training, and output the corresponding abstract features; input the abstract features into the initial LeakyRelu function layer for training, and output the abstract features with increased non-linearity; input the abstract features with increased non-linearity into the initial max pooling layer for training, and output the data features corresponding to the data segments; input the data features into the initial fully connected layer for training, and output the first mark corresponding to the first sample data segment or the second mark corresponding to the second sample data segment; determine whether the first mark is a leakage mark or the second mark is a no-leakage mark; if both are, obtain a leakage classification model constructed by the convolutional layer, LeakyRelu function layer, max pooling layer and fully connected layer; if either is not, perform iterative training on the convolutional layer, LeakyRelu function layer, max pooling layer and fully connected layer until the first mark output by the leakage classification model constructed by the convolutional layer, LeakyRelu function layer, max pooling layer and fully connected layer is a leakage mark, or the second mark output is a no-leakage mark.

[0223] Based on the vacuum heat pipe low-temperature economizer heat transfer efficiency evaluation device disclosed in the above embodiments of the present invention, in this solution, by obtaining the operating parameters during the operation period of the vacuum heat pipe low-temperature economizer, calculating based on the operating parameters and comparing with historical data, it is determined whether the heat transfer efficiency of the vacuum heat pipe low-temperature economizer has decreased. If the efficiency has decreased, a pre-constructed leakage classification model is used to evaluate whether the vacuum heat pipe low-temperature economizer is leaking. If there is no leakage, the factors affecting the heat transfer efficiency are analyzed through the resistance coefficient, so as to achieve the purpose of quickly and accurately analyzing the reasons for the decrease in the heat transfer efficiency of the vacuum heat pipe low-temperature economizer.

[0224] Each embodiment in this specification is described in a progressive manner. The same or similar parts among the embodiments can be referred to each other, and the differences between each embodiment and other embodiments are emphasized. In particular, for the system or system embodiment, since it is basically similar to the method embodiment, it is described relatively simply, and the relevant parts can refer to the partial description of the method embodiment. The systems and system embodiments described above are merely illustrative. The units described as separate components may or may not be physically separated, and the components shown as units may or may not be physical units, that is, they may be located in one place or distributed to multiple network units. Some or all of the modules can be selected according to actual needs to achieve the purpose of the solution of this embodiment. Those of ordinary skill in the art can understand and implement it without creative work.

[0225] Those skilled in the art can further realize that the units and algorithm steps of each example described in combination with the embodiments disclosed herein can be implemented by electronic hardware, computer software, or the combination of the two. To clearly illustrate the interchangeability of hardware and software, the composition and steps of each example have been generally described according to functions in the above description. Whether these functions are executed in hardware or software depends on the specific application and design constraints of the technical solution. Those skilled in the art can use different methods to implement the described functions for each specific application, but such implementation should not be considered to exceed the scope of the present invention.

[0226] The above description of the disclosed embodiments enables those skilled in the art to implement or use the present invention. Various modifications to these embodiments will be obvious to those skilled in the art, and the general principles defined herein can be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to the embodiments shown herein, but will conform to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for evaluating the heat exchange efficiency of a vacuum heat pipe low-temperature economizer, characterized in that: include: Obtaining the operating parameters of the vacuum heat pipe low-temperature economizer during the operating period; Based on the operating parameters and the light-heat balance formula, the actual heat transfer coefficients of the vacuum heat pipe low-temperature economizer at preset time intervals within the operating period are calculated; Based on the thermal resistance parameter of the vacuum heat pipe low-temperature economizer, various theoretical heat transfer coefficients of the vacuum heat pipe low-temperature economizer at preset time intervals within the operating period are calculated; The theoretical heat transfer coefficient and the actual heat transfer coefficient are fitted using the least squares method to obtain a fitting curve; Calculating a difference sequence between each actual heat transfer coefficient and the fitting curve, and fitting the difference sequence to obtain a difference sequence curve; Based on the difference sequence curve when the heat exchange efficiency of the vacuum heat pipe low-temperature economizer decreases and the difference sequence curve, determining whether the heat exchange efficiency of the vacuum heat pipe low-temperature economizer decreases; If the heat exchange efficiency of the vacuum heat pipe low-temperature economizer decreases, the operating parameters are input into a pre-built leakage classification model for analysis, and a leakage mark or a non-leakage mark corresponding to the operating parameters is output; the leakage mark is used to indicate that the vacuum heat pipe low-temperature economizer has leaked, and the non-leakage mark is used to indicate that the vacuum heat pipe low-temperature economizer has not leaked; When the leakage classification model outputs a non-leakage mark, calculating each resistance coefficient of the vacuum heat pipe low-temperature economizer during the operating period based on the operating parameters; Corresponding text information is output based on each resistance coefficient, and the text information is used to characterize factors causing a decrease in heat exchange efficiency of the vacuum heat pipe low-temperature economizer.

2. The method according to claim 1, characterized in that The determining whether the heat exchange efficiency of the vacuum heat pipe low-temperature economizer decreases based on the difference sequence curve when the heat exchange efficiency of the vacuum heat pipe low-temperature economizer decreases and the difference sequence curve includes: Comparing the data set of the difference sequence curve in two-dimensional coordinates with a preset target data set to obtain the deviation of the difference sequence curve; Obtaining a difference sequence curve when the heat exchange efficiency of the vacuum heat pipe low-temperature economizer decreases from historical data; Calculating the similarity between the difference sequence curve and the difference sequence curve when the heat exchange efficiency decreases based on a dynamic time normalization algorithm; Performing weighted calculation on the deviation and the similarity to obtain a weighted calculation result; If the weighted calculation result exceeds a preset threshold, it is determined that the heat exchange efficiency of the vacuum heat pipe low-temperature economizer has decreased.

3. The method according to claim 1, characterized in that When the leakage classification model outputs a non-leakage mark, each resistance coefficient of the vacuum heat pipe low-temperature economizer during the operation period is calculated based on the operating parameters, including: When the leakage classification model outputs a no-leakage mark, the resistance coefficient of the vacuum heat pipe low-temperature economizer at preset time intervals within the operating period is calculated based on the principles of fluid mechanics and the flue differential pressure, flue gas density and flue gas flow rate among the operating parameters.

4. The method according to claim 1, wherein The output of corresponding text information based on each resistance coefficient, wherein the text information is used to characterize factors causing a decrease in heat exchange efficiency of the vacuum heat pipe low-temperature economizer, includes: Based on the respective drag coefficients during the operation period, obtaining a change trend of the respective drag coefficients; When the resistance coefficient shows an upward trend, outputting text information indicating that the heat exchange efficiency of the vacuum heat pipe low-temperature economizer is reduced due to excessive ash accumulation; When the resistance coefficient has no changing trend, text information is outputted indicating that the heat exchange efficiency of the vacuum heat pipe low-temperature economizer is reduced due to the generation of non-condensable gas.

5. The method according to any one of claims 1 to 4, characterized in that The construction process of the leakage classification model includes: Obtaining historical operating parameters of the vacuum heat pipe low-temperature economizer; Based on information recorded in a historical maintenance log, first sample data having a leakage mark is screened from the historical operating parameters, the leakage mark being used to indicate that a leakage occurs in the vacuum heat pipe low-temperature economizer; Based on the information recorded in the historical maintenance log, second sample data with a non-leakage mark is filtered out from the historical operating parameters, wherein the non-leakage mark is used to indicate that the vacuum heat pipe low-temperature economizer has not leaked; Segmenting the first sample data and the second sample data to obtain a plurality of first sample data segments of preset lengths and a plurality of second sample data segments; Inputting the plurality of first sample data segments or the plurality of second sample data segments into the initial convolutional layer in sequence for training, and outputting corresponding abstract features; The abstract features are input into the initial LeakyRelu function layer for training, and the output adds nonlinear abstract features; Inputting the abstract features with added nonlinearity into the initial maximum pooling layer for training, and outputting the data features corresponding to the data segments; Inputting the data features into an initial fully connected layer for training, and outputting a first label corresponding to the first sample data segment, or outputting a second label corresponding to the second sample data segment; determining whether the first mark is a leak mark, or whether the second mark is a non-leak mark; If yes, a leakage classification model constructed by convolutional layer, LeakyRelu function layer, maximum pooling layer and fully connected layer is obtained; If any one of them is no, the convolution layer, LeakyRelu function layer, maximum pooling layer and fully connected layer are iteratively trained until the first mark output by the leakage classification model constructed by the convolution layer, LeakyRelu function layer, maximum pooling layer and fully connected layer is a leakage mark, or the second mark output is a non-leakage mark.

6. A device for evaluating the heat exchange efficiency of a vacuum heat pipe low-temperature economizer, characterized in that: include: An acquisition unit, used for acquiring operating parameters of the vacuum heat pipe low-temperature economizer during an operating period; A first calculation unit is configured to calculate, based on the operating parameters and a light-heat balance formula, actual heat transfer coefficients of the vacuum heat pipe low-temperature economizer at preset time intervals within the operating period; A second calculation unit is configured to calculate, based on the thermal resistance parameter of the vacuum heat pipe low-temperature economizer, various theoretical heat transfer coefficients of the vacuum heat pipe low-temperature economizer at preset time intervals within the operating period; A first fitting unit is used to fit the theoretical heat transfer coefficient and the actual heat transfer coefficient using a least squares method to obtain a fitting curve; A second fitting unit is used to calculate a difference sequence between each actual heat transfer coefficient and the fitting curve, and fit the difference sequence to obtain a difference sequence curve; a judgment unit, configured to judge whether the heat exchange efficiency of the vacuum heat pipe low-temperature economizer decreases based on a difference sequence curve when the heat exchange efficiency of the vacuum heat pipe low-temperature economizer decreases and the difference sequence curve; an analysis unit, configured to input the operating parameters into a pre-built leakage classification model for analysis if the heat exchange efficiency of the vacuum heat pipe low-temperature economizer decreases, and output a leakage mark or a non-leakage mark corresponding to the operating parameters; The leakage mark is used to indicate that the vacuum heat pipe low-temperature economizer has leaked, and the non-leakage mark is used to indicate that the vacuum heat pipe low-temperature economizer has not leaked; a third calculation unit, configured to calculate, based on the operating parameters, each resistance coefficient of the vacuum heat pipe low-temperature economizer during the operating period when the leakage classification model outputs a no-leakage mark; The output unit is used to output corresponding text information based on each resistance coefficient, and the text information is used to characterize the factors that reduce the heat exchange efficiency of the vacuum heat pipe low-temperature economizer.

7. The device according to claim 6, characterized in that The judging unit includes: a comparison subunit, configured to compare the data set of the difference sequence curve in two-dimensional coordinates with a preset target data set to obtain a deviation of the difference sequence curve; An acquisition subunit, configured to acquire, from historical data, a difference sequence curve when the heat exchange efficiency of the vacuum heat pipe low-temperature economizer decreases; A first calculation subunit is configured to calculate the similarity between the difference sequence curve and the difference sequence curve when the heat exchange efficiency decreases based on a dynamic time normalization algorithm; A second calculation subunit is configured to perform weighted calculation on the deviation and the similarity to obtain a weighted calculation result; The determination subunit is configured to determine that the heat exchange efficiency of the vacuum heat pipe low-temperature economizer decreases when the weighted calculation result exceeds a preset threshold.

8. The device according to claim 6, characterized in that The third computing unit is specifically configured to: When the leakage classification model outputs a no-leakage mark, the resistance coefficient of the vacuum heat pipe low-temperature economizer at preset time intervals within the operating period is calculated based on the principles of fluid mechanics and the flue differential pressure, flue gas density and flue gas flow rate among the operating parameters.

9. The device according to claim 6, characterized in that The output unit is specifically used for: Based on the various resistance coefficients within the operating period, a change trend of each resistance coefficient is obtained; when the resistance coefficient is on an upward trend, text information is output indicating that the heat exchange efficiency of the vacuum heat pipe low-temperature economizer is reduced due to excessive ash accumulation; when the resistance coefficient has no change trend, text information is output indicating that the heat exchange efficiency of the vacuum heat pipe low-temperature economizer is reduced due to the generation of non-condensable gas.

10. The device according to any one of claims 6 to 9, characterized in that Also includes: a preprocessing unit configured to obtain historical operating parameters of the vacuum heat pipe low-temperature economizer; and based on information recorded in a historical maintenance log, filter out first sample data having a leakage mark from the historical operating parameters, wherein the leakage mark is used to indicate that the vacuum heat pipe low-temperature economizer has a leakage; Based on the information recorded in the historical maintenance log, second sample data with a non-leakage mark is filtered out from the historical operating parameters, wherein the non-leakage mark is used to indicate that the vacuum heat pipe low-temperature economizer has not leaked; Segmenting the first sample data and the second sample data to obtain a plurality of first sample data segments of preset lengths and a plurality of second sample data segments; A training unit, configured to sequentially input a plurality of the first sample data segments or a plurality of the second sample data segments into an initial convolutional layer for training, and output corresponding abstract features; input the abstract features into an initial LeakyRelu function layer for training, and output abstract features with added nonlinearity; Inputting the abstract features with added nonlinearity into the initial maximum pooling layer for training, and outputting data features corresponding to the data segment; inputting the data features into the initial fully connected layer for training, and outputting a first label corresponding to the first sample data segment, or outputting a second label corresponding to the second sample data segment; and determining whether the first label is a leak label, or whether the second label is a non-leak label; If both are yes, a leakage classification model constructed by a convolutional layer, a LeakyRelu function layer, a maximum pooling layer and a fully connected layer is obtained; if any one of them is no, the convolutional layer, the LeakyRelu function layer, the maximum pooling layer and the fully connected layer are iteratively trained until the first mark output by the leakage classification model constructed by the convolutional layer, the LeakyRelu function layer, the maximum pooling layer and the fully connected layer is a leakage mark, or the second mark output is a non-leakage mark.

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