An air preheater heat exchange capacity evaluation method and device and a storage medium

Abstract

The present application relates to the technical field of air preheater performance evaluation, and particularly relates to an air preheater heat exchange capacity evaluation method, comprising: obtaining air preheater environment data, and obtaining an actual working condition ratio based on the air preheater environment data and a heat balance function; presetting air preheater environment data, obtaining a preset working condition ratio based on the preset air preheater environment data and the heat balance function; correcting the air preheater heat exchange efficiency based on the actual working condition ratio and the preset working condition ratio by using a counterflow heat exchange model, and obtaining the corrected air preheater heat exchange efficiency; and correcting the flue gas side heat exchange efficiency based on the heat transfer effectiveness-heat transfer unit number by using the counterflow heat exchange model, which can provide a more accurate air preheater heat exchange capacity calculation result, so that test personnel and operation personnel can more accurately understand the actual operation of the air preheater, and the air preheater can reach the optimal operation efficiency.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of air preheater performance evaluation, in particular to an air preheater heat exchange capacity evaluation method, device, equipment and storage medium. BACKGROUND

[0002] In order to reduce the exhaust gas temperature, improve the boiler efficiency and increase the combustion air temperature, air preheaters are set in thermal power plants. The air preheaters in thermal power plants are mainly divided into tubular air preheaters and rotary air preheaters. Large-capacity high-parameter units mainly adopt rotary air preheaters, and small-capacity low-parameter units mainly adopt tubular air preheaters. In the air preheater, high-temperature flue gas is used to heat low-temperature air for heat exchange. The flue gas side heat exchange efficiency is a parameter used to evaluate the heat exchange capacity and operation level of the air preheater. In actual operation, under the premise that the inlet flue gas temperature and the inlet air temperature of the air preheater remain unchanged, if the air quantity or the flue gas quantity deviates from the design value, the flue gas side heat exchange efficiency will change accordingly. If the air flow through the air preheater is too small or the flue gas flow is too large, the outlet flue gas temperature of the air preheater will rise, and the flue gas side heat exchange efficiency will decrease significantly. When the operating conditions are inconsistent with the design conditions, after heat exchange through the air preheater, the flue gas fails to achieve sufficient temperature drop, at which time the performance of the air preheater itself cannot be evaluated as not meeting the standard. Therefore, it is necessary to design an air preheater efficiency evaluation method to correct the heat exchange capacity. SUMMARY

[0003] The purpose of the present application is to provide an air preheater heat exchange capacity evaluation method to solve the problem that the heat exchange capacity of the air preheater cannot be accurately evaluated in the prior art.

[0004] To solve the above technical problems, the present application provides an air preheater heat exchange capacity evaluation method, comprising:

[0005] obtaining air preheater environment data, and obtaining an actual working condition ratio based on the air preheater environment data and a heat balance function;

[0006] presetting air preheater environment data, and obtaining a preset working condition ratio based on the preset air preheater environment data and the heat balance function;

[0007] correcting the air preheater heat exchange efficiency based on the actual working condition ratio and the preset working condition ratio using a counterflow heat exchange model, to obtain a corrected air preheater heat exchange efficiency.

[0008] Preferably, the obtaining of the air preheater environment data and the actual working condition ratio based on the air preheater environment data and the heat balance function comprises:

[0009] obtaining the inlet flue gas temperature, the outlet flue gas temperature, the inlet air temperature and the outlet air temperature.

[0010] a flue gas side heat capacity based on the inlet flue gas temperature and the outlet flue gas temperature;

[0011] a heat exchange temperature difference based on the inlet flue gas temperature and the inlet air temperature;

[0012] an air side heat capacity based on the inlet air temperature and the outlet air temperature;

[0013] the actual operating ratio is obtained by using the flue gas temperature difference and the air temperature difference.

[0014] Preferably, the flue gas side heat exchange efficiency is obtained by using the flue gas temperature difference and the heat exchange temperature difference, and the calculation formula is:

[0015]

[0016] wherein, η G is the flue gas side heat exchange efficiency, T Ao is the outlet air temperature, T Gi is the inlet flue gas temperature, T Go is the inlet air temperature, T Ai is the inlet air temperature.

[0017] Preferably, the actual operating ratio is obtained by using the flue gas temperature difference and the air temperature difference, which includes:

[0018] the actual operating ratio is obtained by using the ratio of the air side heat capacity to the flue gas side heat capacity, and according to the heat balance equation, and the calculation formula is:

[0019]

[0020] wherein, XR is the operating ratio, is the air side heat capacity, is the flue gas side heat capacity.

[0021] Preferably, the actual operating ratio is obtained by using the actual operating ratio and the preset operating ratio to correct the air preheater heat exchange efficiency, and the corrected heat exchange efficiency includes:

[0022] the heat transfer effectiveness of the air preheater is obtained by using the flue gas side heat capacity being less than the air side heat capacity in the air preheater heat transfer process based on the heat transfer effectiveness;

[0023] the corrected heat exchange efficiency is obtained by using the counterflow heat exchange model to correct the air preheater heat exchange efficiency based on the heat transfer effectiveness of the air preheater.

[0024] Preferably, the heat transfer effectiveness calculation formula of the air preheater is:

[0025]

[0026] Wherein, ε G is the heat transfer effectiveness of the air preheater, T Ao is the outlet air temperature, T Gi is the inlet flue gas temperature, T Go is the inlet air temperature, T Ai is the inlet air temperature;

[0027] Based on the flue gas side heat transfer efficiency and the actual working condition ratio, the heat transfer effectiveness calculation formula of the air preheater is converted to obtain:

[0028]

[0029] Wherein, XR is the working condition ratio, η G is the flue gas side heat transfer efficiency.

[0030] Preferably, based on the heat transfer effectiveness of the air preheater, the counterflow heat transfer model is used to correct the air preheater heat transfer efficiency to obtain the corrected heat transfer efficiency, which includes:

[0031] Based on the heat transfer effectiveness of the air preheater, the counterflow heat transfer model is used to correct the air preheater heat transfer efficiency, and the calculation formula is:

[0032]

[0033] Wherein, NTU is the number of heat transfer units;

[0034] Based on the relationship of NTU=f(XR, η G ), the following is obtained:

[0035]

[0036] The NTU value of the air preheater before and after correction is fixed, and based on the actual working condition ratio and the preset working condition ratio, the correction relationship is obtained, and the calculation formula is:

[0037]

[0038] Wherein, XR D is the preset working condition ratio, η Gcr is the corrected flue gas side heat transfer efficiency, η GT is the flue gas side heat transfer efficiency, XR T is the actual working condition ratio;

[0039] The coefficient C is introduced to simplify the calculation to obtain:

[0040]

[0041]

[0042]

[0043] wherein, η Gcr is the corrected heat exchange efficiency.

[0044] The application further provides an air preheater heat exchange capacity evaluation device, comprising:

[0045] An actual working condition ratio module obtains air preheater environment data and obtains an actual working condition ratio based on the air preheater environment data and a heat balance function.

[0046] A preset working condition ratio module presets air preheater environment data, and obtains a preset working condition ratio based on the preset air preheater environment data and the heat balance function.

[0047] A corrected heat exchange efficiency module corrects the heat exchange efficiency of the air preheater based on the counterflow heat exchange model, the actual working condition ratio and the preset working condition ratio, and obtains the corrected heat exchange efficiency of the air preheater.

[0048] The application further provides an air preheater heat exchange capacity evaluation device, comprising:

[0049] A memory for storing a computer program.

[0050] A processor for executing the computer program to realize the steps of the air preheater heat exchange capacity evaluation method.

[0051] The application further provides a computer readable storage medium, characterized in that the computer readable storage medium stores a computer program, and the computer program is executed by a processor to realize the steps of the air preheater heat exchange capacity evaluation method.

[0052] The air preheater heat exchange capacity evaluation method provided by the application can correct the heat exchange efficiency of the flue gas side based on the counterflow heat exchange model and the heat transfer effectiveness-heat transfer unit number, and can provide a more accurate air preheater heat exchange capacity calculation result, so that the actual operation of the air preheater can be more accurately understood by the test personnel and the operation personnel, and the air preheater can achieve optimal operation efficiency. BRIEF DESCRIPTION OF DRAWINGS

[0053] The above and / or additional aspects and advantages of the present application will become apparent and more readily appreciated from the following description, taken in conjunction with the following drawings of which:

[0054] Figure 1 A flow chart of a first specific embodiment of the air preheater heat exchange capacity evaluation method provided by the present application;

[0055] Figure 2 An air preheater heat exchange capacity evaluation method calculation flow chart;

[0056] Figure 3 A structural block diagram of an air preheater heat exchange capacity evaluation device provided by an embodiment of the present application. DETAILED DESCRIPTION

[0057] The core of the present application is to provide an air preheater heat exchange capacity evaluation method, device, equipment and storage medium, to correct the flue gas side heat exchange efficiency based on the heat transfer effectiveness-heat transfer unit number in the countercurrent heat exchange model, so that the air preheater reaches the optimal operating efficiency.

[0058] In order to enable personnel in the technical field to better understand the present application scheme, the present application will be further described in detail below in combination with the drawings and specific embodiments. Obviously, the described embodiments are only some of the embodiments of the present application, not all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor are within the scope of protection of the present application.

[0059] Reference should be made to Figure 1 , Figure 1 A flow chart of a first specific embodiment of the air preheater heat exchange capacity evaluation method provided by the present application; the specific operation steps are as follows:

[0060] Step S101: obtaining air preheater environment data, and obtaining an actual working condition ratio based on the air preheater environment data and a heat balance function;

[0061] The obtaining of the air preheater environment data and the actual working condition ratio based on the air preheater environment data and the heat balance function comprises:

[0062] Obtaining the inlet flue gas temperature, the outlet flue gas temperature, the inlet air temperature and the outlet air temperature;

[0063] Based on the inlet flue gas temperature and the outlet flue gas temperature, obtaining the flue gas side heat capacity;

[0064] Based on the inlet flue gas temperature and the inlet air temperature, obtaining the heat exchange temperature difference;

[0065] Based on the import air temperature and the export air temperature, an air side heat capacity is obtained;

[0066] By using the flue gas temperature difference and the air temperature difference, the actual working condition ratio is obtained;

[0067] Based on the flue gas side heat exchange efficiency, by using the ratio of the air side heat capacity and the flue gas side heat capacity, and according to the heat balance equation, the actual working condition ratio can be obtained, and the calculation formula is:

[0068]

[0069] Wherein, XR is the working condition ratio, is the air side heat capacity, is the flue gas side heat capacity, T Ao is the export air temperature, T Gi is the import flue gas temperature, T Go is the import air temperature, T Ai is the import air temperature.

[0070] Step S102: preset air preheater environment data is obtained, based on the preset air preheater environment data and the heat balance function, the preset working condition ratio is obtained;

[0071] Step S103: based on the counterflow heat exchange model, the working condition ratio and the preset working condition ratio are used to correct the air preheater heat exchange efficiency, and the air preheater corrected heat exchange efficiency is obtained.

[0072] By using the flue gas temperature difference and the heat exchange temperature difference, the flue gas side heat exchange efficiency is obtained, and the calculation formula is:

[0073]

[0074] Wherein, η G is the flue gas side heat exchange efficiency, T Ao is the export air temperature, T Gi is the import flue gas temperature, T Go is the import air temperature, T Ai is the import air temperature.

[0075] The actual working condition ratio and the preset working condition ratio are used to correct the air preheater heat exchange efficiency based on the counterflow heat exchange model, and the corrected heat exchange efficiency is obtained, including:

[0076] Based on the heat transfer effectiveness, in the air preheater heat transfer process, by using the flue gas side heat capacity is less than the air side heat capacity, the heat transfer effectiveness of the air preheater is obtained;

[0077] The calculation formula of the heat transfer effectiveness of the air preheater is:

[0078]

[0079] wherein ε G is the heat transfer effectiveness of the air preheater, T Ao is the outlet air temperature, T Gi is the inlet flue gas temperature, T Go is the inlet air temperature, T Ai is the inlet air temperature;

[0080] Based on the flue gas side heat exchange efficiency and the operating ratio, the heat transfer effectiveness formula of the air preheater is converted to obtain:

[0081]

[0082] wherein XR is the operating ratio, τ G is the flue gas side heat exchange efficiency.

[0083] Based on the heat transfer effectiveness of the air preheater, the counterflow heat exchange model is used to correct the air preheater heat exchange efficiency to obtain the corrected heat exchange efficiency;

[0084] Based on the heat transfer effectiveness of the air preheater, the counterflow heat exchange model is used to correct the air preheater heat exchange efficiency, and the calculation formula is:

[0085]

[0086] wherein NTU is the heat transfer unit number;

[0087] Based on the relationship of NTU=f(XR, η G ), the following is obtained:

[0088]

[0089] The NTU value of the air preheater before and after correction is anchored, and the correction relationship is obtained based on the actual operating ratio and the preset operating ratio, and the calculation formula is:

[0090]

[0091] wherein XR D is the preset operating ratio, is the corrected flue gas side heat exchange efficiency, η GT is the flue gas side heat exchange efficiency, XR T is the actual operating ratio;

[0092] The coefficient C is introduced to simplify the calculation to obtain:

[0093]

[0094]

[0095]

[0096] wherein, is to correct the heat exchange efficiency.

[0097] The embodiment provides an air preheater heat exchange capacity evaluation method. In the air preheater, low-temperature air is heated by high-temperature flue gas to perform heat exchange. The flue gas inlet corresponds to the air outlet, and the flue gas outlet corresponds to the air inlet. The flue gas and the air basically present a counterflow heat exchange model. Therefore, the flue gas side heat exchange efficiency is corrected based on the heat transfer effectiveness-heat transfer unit number in the counterflow heat exchange model. Compared with the uncorrected, the method can provide a more accurate air preheater heat exchange capacity calculation result, so that the test personnel and the operation personnel can more accurately understand the actual operation of the air preheater. The flue gas side heat exchange efficiency after correction is used as a basis to adjust the ratio of the air quantity to the flue gas quantity. The air quantity is adjusted by setting the primary and air blower opening offset. The flue gas quantity is adjusted by setting the induced draft fan opening offset. The optimal air quantity to flue gas quantity ratio is achieved, so that the air preheater reaches the optimal operation efficiency.

[0098] Based on the above embodiment, the embodiment describes the air preheater heat exchange capacity evaluation method, as shown in Figure 2 , and the specific steps are as follows.

[0099] Parameter acquisition: inlet flue gas temperature, outlet flue gas temperature, inlet air temperature, outlet air temperature.

[0100] The inlet flue gas temperature is subtracted from the outlet flue gas temperature to obtain the flue gas temperature drop. The inlet flue gas temperature is subtracted from the inlet air temperature to obtain the heat exchange temperature difference. The flue gas temperature drop is divided by the heat exchange temperature difference to obtain the flue gas side heat exchange efficiency.

[0101] The outlet air temperature is subtracted from the inlet air temperature to obtain the air temperature rise. The flue gas temperature drop is divided by the air temperature rise to obtain the operating condition ratio (X-ratio XRT).

[0102] Parameter acquisition: preset inlet flue gas temperature, preset outlet flue gas temperature, preset inlet air temperature, preset outlet air temperature.

[0103] The preset inlet flue gas temperature is subtracted from the preset outlet flue gas temperature to obtain the preset flue gas temperature drop,

[0104] The preset outlet air temperature is subtracted from the preset inlet air temperature to obtain the preset air temperature rise. The preset flue gas temperature drop is divided by the preset air temperature rise to obtain the preset operating condition ratio (X-ratio XRD).

[0105] The parameter C is calculated by using the formula .

[0106] The parameter C is calculated by using the formula The corrected flue gas side heat exchange efficiency ηcr is calculated.

[0107] The air preheater heat exchange capacity evaluation method provided by the embodiment of the application is used for heat exchange by heating low-temperature air with high-temperature flue gas in the air preheater, the flue gas inlet corresponds to the air outlet, the flue gas outlet corresponds to the air inlet, and the flue gas and the air basically present a counterflow heat exchange model, so the flue gas side heat exchange efficiency is corrected based on the heat transfer effectiveness-heat transfer unit number in the counterflow heat exchange model. Based on the air preheater heat exchange model, a more accurate air preheater heat exchange capacity calculation result is provided, so that the test personnel and the operation personnel can more accurately understand the actual operation condition of the air preheater, and the ratio of the air quantity to the flue gas quantity is adjusted based on the corrected flue gas side heat exchange efficiency, the air quantity is adjusted by setting the primary air fan opening degree offset, and the flue gas quantity is adjusted by setting the induced draft fan opening degree offset, so that the optimal air quantity to flue gas quantity ratio is achieved, and the air preheater reaches the optimal operation efficiency.

[0108] Based on the above embodiment, the relationship between the heat transfer effectiveness and the heat transfer unit number is described as follows.

[0109] The heat absorption amount of the cold fluid in the counterflow heat exchange is equal to the heat release amount of the hot fluid, and the following heat exchange relationship is present:

[0110] Φ=q m1 c1(t′1-t″1)=q m2 c2(t″2-t′2)

[0111] Wherein, Φ is the heat flow, q m1 c1 is the heat capacity of the hot fluid, q m2 c2 is the heat capacity of the cold fluid, t1 ′ is the initial temperature of the hot fluid, t1 ″ is the final temperature of the hot fluid, t2 ′ is the initial temperature of the cold fluid, t2 ″ is the final temperature of the cold fluid;

[0112]

[0113] Wherein, k is the heat transfer coefficient, and A is the heat exchange area.

[0114] There are mainly three dimensionless quantities for describing the performance of the heat exchanger, i.e., the heat capacity ratio, the heat transfer effectiveness and the heat transfer unit number, and the heat capacity ratio is the ratio of the smaller heat capacity to the larger heat capacity in the heat exchange fluid.

[0115]

[0116] Wherein, R is the heat capacity ratio, (q m c) minFor smaller heat capacity, (q m c max For larger heat capacity;

[0117] The number of heat transfer units is the product of the heat transfer coefficient and the heat transfer area divided by the smaller heat capacity of the two fluids;

[0118]

[0119] Wherein, NTU is the number of heat transfer units;

[0120] The heat transfer effectiveness is the ratio of the actual heat transfer of the heat exchanger to the maximum possible heat transfer;

[0121]

[0122] Wherein, ε is the heat transfer effectiveness, (t ′ -t″) max The larger value of the actual temperature difference of the cold fluid or the hot fluid in the heat exchanger, t′1-t″2 is the maximum temperature difference that can occur in the heat exchanger;

[0123] Given the heat transfer effectiveness, the heat flow can be determined according to the inlet temperature of the cold fluid and the hot fluid;

[0124] Φ = (q m c min (t′-t″) max = ε(q m c min (t′1-t′2)

[0125] For the heat exchanger counterflow heat exchange, assuming q m1 c1<q m2 c2, we know:

[0126] t′1-t″1= ε(t′1-t′2)

[0127]

[0128]

[0129]

[0130]

[0131] When q m1 c1>q m2 c2, similar derivation can be obtained:

[0132]

[0133] Based on the above formula combination processing, we get:

[0134]

[0135] The relationship between the heat capacity ratio, the heat transfer effectiveness and the number of heat transfer units is:

[0136]

[0137] Reference is made to Figure 3 , Figure 3 A structural block diagram of an air preheater heat exchange capacity evaluation device provided by an embodiment of the present application is shown in FIG. 1. The specific device can include:

[0138] An actual working condition ratio module 100 acquires air preheater environment data and obtains an actual working condition ratio based on the air preheater environment data and a heat balance function.

[0139] A preset working condition ratio module 200 presets air preheater environment data and obtains a preset working condition ratio based on the preset air preheater environment data and the heat balance function.

[0140] A corrected heat exchange efficiency module 300 corrects the heat exchange efficiency of the air preheater based on a counterflow heat exchange model, using the actual working condition ratio and the preset working condition ratio, to obtain a corrected heat exchange efficiency of the air preheater.

[0141] The air preheater heat exchange capacity evaluation device of the embodiment is used to implement the air preheater heat exchange capacity evaluation method described above, and thus the specific embodiments of the air preheater heat exchange capacity evaluation device can refer to the embodiment part of the air preheater heat exchange capacity evaluation method described above, for example, the actual working condition ratio module 100, the preset working condition ratio module 200, and the corrected heat exchange efficiency module 300, which are respectively used to implement steps S101, S102, and S103 of the air preheater heat exchange capacity evaluation method described above. Therefore, the specific embodiments can refer to the description of the corresponding embodiment part, and will not be described here again.

[0142] In the description of the present specification, the description of the terms "one embodiment", "some embodiments", "an example", "a specific example", or "some examples" and the like means that the specific features, structures, materials or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present application. In the present specification, the illustrative description of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any appropriate manner in any one or more embodiments or examples. In addition, the person skilled in the art can combine and combine the different embodiments or examples described in the present specification and the features of the different embodiments or examples without contradiction.

[0143] In addition, the terms "first", "second", etc. are used only for descriptive purposes and do not connote or imply relative importance or a quantity of the indicated technical features. Thus, a feature defined with "first", "second", etc. can include at least one of the features explicitly or implicitly. In the description of the present application, the meaning of "a plurality" is at least two, for example, two, three, etc., unless otherwise explicitly and specifically limited.

[0144] Any process or method descriptions or blocks in flow charts described herein and elsewhere can be understood as representing modules, segments, or portions of code which include one or more executable instructions for implementing specific logical functions or steps in the process. Alternate implementations are included within the scope of the preferred embodiments of the present application in which additional functionality can be added or where functions can be implemented in differing orders or in different manners.

[0145] The various embodiments described in the specification are progressive in nature, and each embodiment highlights the differences from other embodiments. The same or similar parts between various embodiments can be mutually referred to. For the device disclosed in the embodiments, since it corresponds to the method disclosed in the embodiments, the description is relatively simple, and the relevant parts can be referred to the method part.

[0146] The above provides a detailed introduction to the air preheater heat exchange capacity evaluation method, device, equipment and storage medium provided by the present application. The principles and implementation modes of the present application are described by using specific examples. The above embodiment description is only used to help understand the method of the present application and its core idea. It should be pointed out that, for ordinary skilled persons in the technical field, without departing from the principles of the present application, the present application can be improved and modified in several ways. These improvements and modifications also fall within the protection scope of the claims of the present application.

[0147] It should be understood that the parts of the present application can be realized by hardware, software, firmware or their combination. In the above embodiments, the plurality of steps or methods can be realized by software or firmware stored in the memory and executed by the appropriate instruction execution system. For example, if realized by hardware and in another embodiment, it can be realized by any one or their combination of the following technologies known in the art: discrete logic circuit with logic gate circuit for implementing logic function on data signal, special integrated circuit with appropriate combination logic gate, programmable gate array (PGA), field programmable gate array (FPGA) and the like.

[0148] Those skilled in the art of the present technology can understand that all or part of the steps carried out by the above-mentioned embodiment methods can be completed by programs instructing relevant hardware, and the programs can be stored in a computer readable storage medium. When the program is executed, it includes one of the steps of the method embodiment or a combination thereof.

[0149] In addition, each functional unit in each embodiment of the present application can be integrated into one processing module, or each unit can exist physically independently, or two or more units can be integrated into one module. The integrated module can be realized in the form of hardware or in the form of a software functional module. The integrated module, if realized in the form of a software functional module and sold or used as an independent product, can also be stored in a computer readable storage medium.

Claims

1. A method for evaluating heat exchange capacity of an air preheater, characterized by, The method comprises the following steps: acquiring air preheater environment data, and obtaining an actual working condition ratio based on the air preheater environment data and a heat balance function; presetting air preheater environment data, and obtaining a preset working condition ratio based on the preset air preheater environment data and the heat balance function; correcting the air preheater heat exchange efficiency based on the actual working condition ratio and the preset working condition ratio according to a counterflow heat exchange model, to obtain a corrected air preheater heat exchange efficiency; the step of acquiring the air preheater environment data and obtaining the actual working condition ratio based on the air preheater environment data and the heat balance function comprises: acquiring an inlet flue gas temperature, an outlet flue gas temperature, an inlet air temperature and an outlet air temperature; obtaining a flue gas side heat capacity based on the inlet flue gas temperature and the outlet flue gas temperature; obtaining a heat exchange temperature difference based on the inlet flue gas temperature and the inlet air temperature; obtaining an air side heat capacity based on the inlet air temperature and the outlet air temperature; obtaining the actual working condition ratio by using the flue gas side heat capacity and the air side heat capacity; obtaining a flue gas side heat exchange efficiency by using the flue gas side heat capacity and the heat exchange temperature difference, and the calculation formula is: wherein η G is the heat exchange efficiency of the flue gas side, T Gi is the inlet flue gas temperature, T Go is the outlet flue gas temperature, T Ai is the inlet air temperature; the step of obtaining the actual working condition ratio by using the flue gas side heat capacity and the air side heat capacity comprises: obtaining the actual working condition ratio by using the ratio of the air side heat capacity to the flue gas side heat capacity and according to a heat balance equation, and the calculation formula is: where XR is the operating ratio, is the air-side heat capacity, is the flue gas-side heat capacity, T Ao is the outlet air temperature.

2. The heat exchange capacity evaluation method of an air preheater according to claim 1, wherein the step of correcting the air preheater heat exchange efficiency based on the actual working condition ratio and the preset working condition ratio according to the counterflow heat exchange model to obtain the corrected heat exchange efficiency comprises: obtaining an air preheater heat transfer effectiveness by using the fact that the flue gas side heat capacity is less than the air side heat capacity in the air preheater heat transfer process; correcting the air preheater heat exchange efficiency according to the counterflow heat exchange model based on the air preheater heat transfer effectiveness, to obtain the corrected heat exchange efficiency.

3. The heat exchange capacity evaluation method of an air preheater according to claim 2, wherein the calculation formula of the air preheater heat transfer effectiveness is: where ε G is the heat transfer effectiveness of the air preheater, T Ao is the outlet air temperature, T Gi is the inlet flue gas temperature, and T Ai is the inlet air temperature. the calculation formula of the air preheater heat transfer effectiveness is converted based on the flue gas side heat exchange efficiency and the actual working condition ratio, to obtain: wherein XR is the operating ratio, η G is the flue gas side heat transfer efficiency.

4. The heat exchange capacity evaluation method of an air preheater according to claim 3, wherein the step of correcting the air preheater heat exchange efficiency according to the counterflow heat exchange model based on the air preheater heat transfer effectiveness comprises: correcting the air preheater heat exchange efficiency according to the counterflow heat exchange model based on the air preheater heat transfer effectiveness, and the calculation formula is: wherein, NTU is a heat transfer unit number; Based on the relationship of NTU = f(XR, η G ), we have: the NTU value of the air preheater before and after correction is unchanged, and a correction relationship is obtained based on the actual working condition ratio and the preset working condition ratio, and the calculation formula is: wherein, XR D is a preset operating ratio, is a corrected flue gas side heat exchange efficiency, η GT is a flue gas side heat exchange efficiency, XR T is an actual operating ratio; a coefficient C is introduced to simplify the calculation, and the calculation formula is: wherein to correct the heat exchange efficiency.

5. An air preheater heat exchange capacity evaluation device characterized by comprising: The device is used to implement the air preheater heat exchange capacity evaluation method according to claim 1, and the device comprises: an actual working condition ratio module, which acquires air preheater environment data, and obtains an actual working condition ratio based on the air preheater environment data and a heat balance function; a preset working condition ratio module, preset air preheater environment data, and a preset working condition ratio obtained based on the preset air preheater environment data and a heat balance function; a correction heat exchange efficiency module, which corrects the heat exchange efficiency of the air preheater based on the counterflow heat exchange model and the actual working condition ratio and the preset working condition ratio to obtain a corrected heat exchange efficiency of the air preheater.

6. An air preheater heat exchange capacity evaluation device characterized by, The method comprises the following steps: a memory for storing a computer program; a processor for executing the computer program to implement the steps of the air preheater heat exchange capacity evaluation method according to any one of claims 1 to 4.

7. A computer-readable storage medium, characterized in that, The computer program is stored on the computer readable storage medium and is executed by the processor to implement the steps of the air preheater heat exchange capacity evaluation method according to any one of claims 1 to 4.

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