Flue gas waste heat recovery control method for coal-fired power plant

Abstract

The invention relates to the technical field of power plant flue gas waste heat recovery, in particular to a coal-fired power plant flue gas waste heat recovery control method.The coal-fired power plant generates electric energy with coal as fuel, and the basic process is that coal burns to heat water to generate steam, chemical energy is converted into heat energy, steam pressure pushes a steam turbine to rotate, and the heat energy is converted into mechanical energy; the generator is further driven to convert mechanical energy into electric energy. The waste heat refers to heat energy which can be utilized in production, such as high-temperature waste gas and the like. The waste heat utilization modes are various, steam generated by the waste heat boiler can push the steam turbine to do work or generate electricity, and the device can also be used for heating and hot water production. Waste heat recycling is an effective means for reducing carbon emission, for example, in northern areas, industrial waste heat is recycled for heating, consumption of fossil energy such as coal for heating is reduced, carbon dioxide emission is reduced, and a large amount of water resources are saved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of power plant flue gas waste heat recovery, in particular to a coal-fired power plant flue gas waste heat recovery control method. BACKGROUND

[0002] The coal-fired power plant is a plant that uses coal as fuel to produce electric energy, and its basic production process is: when the fuel is burned, water is heated to generate steam, the chemical energy of the fuel is converted into heat energy, the steam pressure drives the steam turbine to rotate, the heat energy is converted into mechanical energy, and then the steam turbine drives the generator to rotate, and the mechanical energy is converted into electric energy, and the waste heat refers to the heat energy released during the production process, mainly high-temperature waste gas, etc., and the waste heat utilization can generate steam through the waste heat boiler to drive the steam turbine to do mechanical work or generate electricity, or can be used for heating or producing hot water, and the waste heat recovery and utilization is an effective way to reduce carbon emissions. For example, in the northern region, the industrial waste heat recovery for heating, this measure not only reduces the consumption of fossil energy such as coal for heating, reduces the carbon dioxide emissions caused by burning, but also saves a large amount of water resources; the defects and deficiencies of the prior art: the common flue gas waste heat recovery control method cannot deeply understand the characteristics and change law of the flue gas when in use, the information cannot be verified correspondingly, it is difficult to obtain comprehensive and accurate flue gas related parameters, so that the degree of waste heat recovery cannot be adjusted, the waste heat utilization cannot be fully carried out, the reduction of carbon emissions is affected, and unreasonable waste heat extraction leads to abnormal temperature rising speed of the boiler, affecting the normal operation of the boiler, and the utilization potential of the waste heat cannot be fully tapped. Therefore, we propose a coal-fired power plant flue gas waste heat recovery control method. SUMMARY

[0003] The present application proposes a coal-fired power plant flue gas waste heat recovery control method.

[0004] In order to achieve the above purpose, the present application adopts the following technical scheme:

[0005] A coal-fired power plant flue gas waste heat recovery control method, the flue gas waste heat recovery control method comprises the following steps:

[0006] S100, collecting the working process of the coal-fired power plant, analyzing the flue gas temperature change of the waste heat according to the working process of the coal-fired power plant, simultaneously obtaining the flow path of the flue gas, monitoring the flue gas impurity content on the flow path by using a Fourier transform infrared spectrometer, and analyzing the mapping relationship table between the flue gas temperature change and the flue gas impurity content change through a linear regression model;

[0007] S200, recording the temperature change of the boiler when working without extracting waste heat, calculating the temperature rising speed change of the boiler, forming an initial temperature change table, collecting the concentration and flow of carbon emissions, calculating the carbon emission content, and forming an initial emission content;

[0008] S300, control the speed of extracting waste heat, detect the temperature change of the boiler, calculate the temperature rising speed, obtain an extraction temperature change table, judge the influence of different extraction waste heat speeds on the boiler temperature rising speed according to the initial temperature change table and the extraction temperature change table, consider that the extracted waste heat is non-influential waste heat when the boiler temperature rising speed is not reduced, consider that the extracted waste heat is influential waste heat when the boiler temperature rising speed is reduced, and then real-time collect the carbon emission content to obtain an extraction carbon content;

[0009] S400, calculate the decline amplitude of the boiler temperature rising speed, analyze the electric energy required to restore the boiler temperature rising speed, obtain excess supplementary electric energy, and then calculate the excess supplementary price according to the excess supplementary electric energy and the current electricity price;

[0010] S500, collectively refer to the non-influential waste heat and the influential waste heat as recovered waste heat, analyze the position of receiving the waste heat, control the recovered waste heat to act on different waste heat positions, record the changes of different waste heat positions, obtain the waste heat effect, analyze the electric energy required to achieve the same waste heat effect, and calculate the waste heat value according to the current electricity price of the electric energy;

[0011] S600, calculate the difference between the excess supplementary price and the waste heat value, analyze the gap between the extracted carbon content and the initial emission content, and generate an adjustment scheme for the speed of extracting waste heat according to the calculated difference and the gap between the extracted carbon content and the initial emission content.

[0012] Beneficial effects: 1. By monitoring the flue gas impurity content through the Fourier transform infrared spectrometer, and analyzing the mapping relationship table through the linear regression model, the related parameters of the flue gas and their change rules can be comprehensively and accurately mastered, so that the influence of different extraction waste heat speeds has a comparable standard, the accuracy and reliability of the judgment are improved, the adverse effects of waste heat recovery on the boiler operation are avoided, the cost and value of waste heat recovery are quantified, the economic benefits of waste heat recovery are compared and evaluated intuitively, which helps to reduce the additional fossil fuel combustion caused by ineffective waste heat recovery, thereby reducing carbon emissions, improving the efficiency and economy of waste heat recovery, and helping to fully tap the utilization potential of waste heat and improve the comprehensive utilization level of waste heat;

[0013] 2、The application verifies the accuracy by the mapping relationship table obtained by the linear regression model analysis, if the deviation between the predicted value and the actual value is large, it indicates that the model may have problems or the data collection is wrong, which can be adjusted and optimized in time, avoiding subsequent analysis and decision based on the wrong mapping relationship, thereby ensuring the accuracy of mastering the change rule of the flue gas parameters, and through mutual verification, the change of the flue gas temperature and the change of the flue gas impurity content can be further accurately obtained, the reliability of the data is improved, the temperature change table is more accurately reflected the dynamic process of the boiler temperature change, the speed of the boiler temperature rise can be accurately quantified, and based on the accurately calculated temperature rise speed, the change of the boiler temperature under different extraction waste heat speeds can be more accurately analyzed;

[0014] 3、The application extracts the peak time in the standard and extraction temperature change table, analyzes the difference ratio to calculate the extension index of the extraction peak time, can intuitively reflect the influence of the extraction waste heat on the appearance time of the peak value of the boiler temperature rise speed, ensures the accuracy and repeatability of the calculation result, ensures that the recovered waste heat is accurately used in the most suitable position, improves the waste heat utilization efficiency, avoids waste of waste heat or cannot achieve the expected effect due to improper position, and realizes efficient utilization of waste heat. BRIEF DESCRIPTION OF DRAWINGS

[0015] Figure 1 is a schematic view of the present application. DETAILED DESCRIPTION

[0016] The specific embodiments of the present application will be further described below in conjunction with the accompanying drawings, and it should be noted that the description of these embodiments is used to help understand the present application, but does not constitute a limitation on the present application.

[0017] In addition, the technical features involved in each embodiment of the present application described below can be combined with each other as long as they do not conflict with each other.

[0018] Example one:

[0019] A coal-fired power plant flue gas waste heat recovery control method, in the daily production and operation process of the coal-fired power plant, efficient use of energy and cost reduction is a crucial goal, in this process, waste heat recovery becomes a key link, when the coal is burned in the boiler to produce high-temperature flue gas, these flue gases carry a large amount of waste heat, if these waste heat is not reasonably recovered and utilized, not only will cause waste of energy, increase the operation cost of the power plant, but also may cause thermal pollution to the surrounding environment due to waste heat emission;

[0020] At present, the common waste heat recovery mode has many problems, for example, it is difficult to accurately grasp the relationship between the temperature change and the impurity content in the flue gas, which leads to low waste heat recovery efficiency, in the process of extracting waste heat, the influence on the operation of the boiler is not fully considered, sometimes it will make the boiler temperature rising speed abnormal, affect the power generation efficiency and equipment life, and in the aspect of waste heat utilization, lack of scientific planning, waste heat cannot be accurately used in the right place, it is difficult to realize the maximum value of waste heat;

[0021] Therefore, in order to effectively solve the above problems, the present application proposes a coal-fired power plant flue gas waste heat recovery control method, as shown in the accompanying drawings Figure 1 The flue gas waste heat recovery control method comprises the following steps:

[0022] S100, collecting the working process of the coal-fired power plant, analyzing the temperature change of the waste heat flue gas according to the working process of the coal-fired power plant, obtaining the flow path of the flue gas, monitoring the impurity content of the flue gas on the flow path by using the Fourier transform infrared spectrometer, and analyzing the mapping relationship table between the temperature change of the flue gas and the impurity content change of the flue gas by using the linear regression model;

[0023] S200, recording the temperature change of the boiler when it is working without extracting waste heat, calculating the temperature rising speed change of the boiler, forming an initial temperature change table, collecting the concentration and flow of carbon emissions, calculating the carbon emission content, and forming an initial emission content;

[0024] S300, controlling the speed of extracting waste heat, detecting the temperature change of the boiler, calculating the temperature rising speed, obtaining an extraction temperature change table, judging the influence of different extraction waste heat speed on the temperature rising speed of the boiler according to the initial temperature change table and the extraction temperature change table, when the temperature rising speed of the boiler is not reduced, considering that the extracted waste heat is non-influence waste heat, when the temperature rising speed of the boiler is reduced, considering that the extracted waste heat is influence waste heat, at this time, the carbon emission content is collected in real time, and the extraction carbon content is obtained;

[0025] Avoiding the decrease of the operation efficiency of the boiler caused by unreasonable extraction of waste heat, and reducing the carbon emissions caused by the additional energy consumption of the boiler;

[0026] S400, calculating the decline range of the temperature rising speed of the boiler, analyzing the electric energy required to restore the temperature rising speed of the boiler, obtaining the excess supplementary electric energy, and then calculating the excess supplementary price according to the excess supplementary electric energy and the current electricity price;

[0027] S500, combining the non-influence waste heat and the influence waste heat into recovered waste heat, analyzing the position of receiving the waste heat, controlling the recovered waste heat to act on different waste heat positions, recording the changes of different waste heat positions, obtaining the waste heat effect, analyzing the electric energy required to achieve the same waste heat effect, and calculating the waste heat value according to the current electricity price of the electric energy.

[0028] S600: Calculate the difference between the excess supplement price and the waste heat value, analyze the gap between the extracted carbon content and the initial emission content, and generate an adjustment plan for the waste heat extraction rate based on the calculated difference and the gap between the extracted carbon content and the initial emission content.

[0029] Fourier transform infrared spectrometers use an internal infrared light source to emit continuous infrared light. After passing through an interferometer, the intensity of the light changes over time, forming an interferogram. When this interferometric light shines on a flue gas sample, different impurities in the flue gas will have different reactions such as absorption and transmission to infrared light of a specific wavelength. The light transmitted through the sample is received by a detector, which converts the optical signal into an electrical signal. The electrical signal is then converted into a digital signal through analog-to-digital conversion. Finally, using a Fourier transform algorithm, the interferogram is converted into an infrared spectrum. From the different absorption peak positions and intensities in the spectrum, the types and contents of impurities in the flue gas can be analyzed.

[0030] A linear regression model collects relevant data, estimates parameters using the least squares method, minimizes the sum of squared errors between actual and predicted values, establishes a model after determining the parameters, and can predict the dependent variable by inputting new independent variable values. Finally, by comparing the errors between predicted and actual values, the accuracy and reliability of the model are evaluated, and its effectiveness is determined.

[0031] The least squares method measures the overall deviation between the model's predicted values ​​and the actual observed values. The smaller the value of this overall deviation, the better the model fits the data.

[0032] The mapping relationship table is a quantitative representation of the relationship between changes in flue gas temperature and changes in flue gas impurity content, based on a linear regression model.

[0033] This helps reduce the additional burning of fossil fuels due to the ineffective recovery of waste heat, thereby reducing carbon emissions, because if waste heat is not recovered, more coal may need to be burned to meet production needs, resulting in more carbon dioxide emissions.

[0034] Specifically, the working process of the coal-fired power plant is collected, the flue gas temperature change of the waste heat is analyzed according to the working process of the coal-fired power plant, the flow path of the flue gas is obtained, the Fourier transform infrared spectrometer is used to monitor the impurity content of the flue gas on the flow path, the mapping relationship table between the flue gas temperature change and the flue gas impurity content change is analyzed, the temperature change of the boiler during work is recorded without extracting the waste heat, the temperature rise speed change of the boiler is calculated, the initial temperature change table is formed, the concentration and flow of carbon emissions are collected, the carbon emission content is calculated, the initial emission content is formed, the speed of extracting the waste heat is controlled, the temperature change of the boiler is detected, the temperature rise speed is calculated, the influence of different waste heat extraction speeds on the temperature rise speed of the boiler is judged according to the initial temperature change table and the extraction temperature change table, when the temperature rise speed of the boiler is not reduced, it is considered that the extracted waste heat is non-influential waste heat, when the temperature rise speed of the boiler is reduced, it is considered that the extracted waste heat is influential waste heat, the electric energy required to restore the temperature rise speed of the boiler is analyzed, the excess supplement price is calculated according to the excess supplement electric energy and the current electricity price, the position of receiving the waste heat is analyzed, the recovered waste heat is controlled to act on different waste heat positions, the changes of different waste heat positions are recorded, the electric energy required to achieve the same waste heat effect is analyzed, and the waste heat value is calculated according to the current electricity price, the difference between the excess supplement price and the waste heat value is calculated, and the difference between the extracted carbon content and the initial emission content is analyzed, and the adjustment scheme of the extraction speed of the waste heat is generated according to the calculated difference and the difference between the extracted carbon content and the initial emission content.

[0035] Embodiment two:

[0036] In S100, after obtaining the mapping relationship table between the flue gas temperature change and the flue gas impurity content change, different flue gas temperature change values and flue gas impurity content change values are substituted into the linear regression model to obtain corresponding flue gas impurity content prediction values and flue gas temperature prediction values, the flue gas impurity content change and the flue gas temperature change are taken as actual values, at this time the flue gas impurity content prediction values are compared with the flue gas impurity content change, the flue gas temperature prediction values are compared with the flue gas temperature change, and the error between the prediction values and the actual values is judged;

[0037] In S100, when the error between the prediction values and the actual values is judged, the error between the prediction values and the actual values is collectively referred to as a verification difference, an error range is set, and then the error range, the prediction values and the actual values are used to realize mutual verification between the gas temperature change and the flue gas impurity content change, so as to more accurately obtain the gas temperature change and the flue gas impurity content change;

[0038] In S300, when calculating the temperature rising speed, a time interval threshold is established, and then different boiler temperatures are extracted according to the time interval threshold, the extracted temperature change table is perfected, the turning point time and the turning point temperature are obtained, and they are recorded in the extracted temperature change table in time sequence, the interval time between the turning point time and the last time interval threshold is analyzed, and it is included in the time interval threshold;

[0039] In S300, the Xth temperature in the extracted temperature change table is W X , the X+1th temperature in the extracted temperature change table is W X+1 , the temperature rising speed is W S , and the time interval from the last time interval threshold is S Y .

[0040]

[0041] The temperature rising speed is calculated by the above formula;

[0042] When the verification difference is in the error range, it means that the flue gas temperature change and the flue gas impurity content change can verify each other after being obtained, so that the acquisition of the flue gas temperature change is more accurate;

[0043] When the verification difference is not in the error range, it means that the flue gas temperature change and the flue gas impurity content change are abnormal, and the staff is notified to check;

[0044] Specifically, different flue gas temperature change values and flue gas impurity content change values are substituted into the linear regression model to obtain corresponding flue gas impurity content prediction values and flue gas temperature prediction values, the flue gas impurity content change and the flue gas temperature change are taken as actual values, then the flue gas impurity content prediction values are compared with the flue gas impurity content change, the flue gas temperature prediction values are compared with the flue gas temperature change, the error between the prediction values and the actual values is judged, the error range is set, and then the error range, the prediction values and the actual values are used to realize the mutual verification between the flue gas temperature change and the flue gas impurity content change, the flue gas temperature change and the flue gas impurity content change are more accurately obtained, a time interval threshold is established, then different boiler temperatures are extracted according to the time interval threshold, the extracted temperature change table is perfected, the turning point time and the turning point temperature are obtained, and they are recorded in the extracted temperature change table in time sequence, the interval time between the turning point time and the last time interval threshold is analyzed, and it is included in the time interval threshold, and the temperature rising speed is calculated.

[0045] Example three:

[0046] In S400, the decline range of the boiler temperature rising speed is calculated by extracting the peak time in the initial temperature change table and the extraction temperature change table, obtaining the standard peak time and the extraction peak time, and analyzing the difference ratio of the standard peak time and the extraction peak time, and calculating the extension index of the extraction peak time;

[0047] In S400, the extension index of the extraction peak time is calculated by setting the peak time value in the initial temperature change table as B F , setting the peak time of the extraction temperature change table as C F , and setting the extension index of the extraction peak time as Y Z :

[0048]

[0049] The extension index of the extraction peak time is calculated by the above formula;

[0050] In S400, the excess supplement price is calculated by setting the excess supplement electric energy as G B , setting the current electricity price as D J , and setting the excess supplement price as G J :

[0051] G J =G B ·D J

[0052] The excess supplement price is calculated by the above formula;

[0053] In S500, when the recovered waste heat is applied to different waste heat positions, the target temperature required by different waste heat positions is analyzed, and the heat range required by the current temperature of different waste heat positions to reach the target temperature is analyzed to obtain the target heat range. At this time, the target heat range corresponding to the recovered waste heat is matched to obtain the execution heat range. At this time, a waste heat position is selected from the execution heat range, and the recovered waste heat is applied to the corresponding waste heat position;

[0054] The extension index of the peak time refers to the ratio between the difference of two peak times and the peak time value in the initial temperature change table, wherein the difference of two peak times is the numerator;

[0055] Specifically, the peak time in the initial temperature change table and the extraction temperature change table is extracted to obtain a standard peak time and an extraction peak time, then the difference ratio of the standard peak time and the extraction peak time is analyzed, the extension index of the extraction peak time is calculated, the extension index of the extraction peak time and the excessive supplement price are calculated, the target temperature required to be reached by different waste heat positions is analyzed, the heat range required by the current temperature of different waste heat positions to reach the target temperature is analyzed to obtain a target heat range, the target heat range corresponding to the recovered waste heat is matched to obtain an execution heat range, then a waste heat position is selected from the execution heat range, and the recovered waste heat is applied to the corresponding waste heat position.

[0056] Working principle:

[0057] First, the working process of the coal-fired power plant is collected, the flue gas temperature change of the waste heat is analyzed according to the working process of the coal-fired power plant, the flow path of the flue gas is obtained, the Fourier transform infrared spectrometer is used to monitor the impurity content of the flue gas on the flow path, the mapping relationship table between the flue gas temperature change and the flue gas impurity content change is analyzed, the concentration and flow of carbon emission are collected, the carbon emission content is calculated, the initial emission content is formed, different flue gas temperature change values and flue gas impurity content change values are substituted into the linear regression model to obtain the corresponding flue gas impurity content prediction value and flue gas temperature prediction value, the flue gas impurity content change and the flue gas temperature change are taken as actual values, then the flue gas impurity content prediction value is compared with the flue gas impurity content change, the flue gas temperature prediction value is compared with the flue gas temperature change, the error between the prediction value and the actual value is judged, the error range is set, then the error range, the prediction value and the actual value are used to realize the mutual verification between the flue gas temperature change and the flue gas impurity content change, and the flue gas temperature change and the flue gas impurity content change are more accurately obtained, the temperature change of the boiler during work is recorded without extracting the waste heat, and the temperature rise speed change of the boiler is calculated to form an initial temperature change table, the speed of extracting the waste heat is controlled, the temperature change of the boiler is detected, the temperature rise speed is calculated, the influence of different extraction speeds of the waste heat on the temperature rise speed of the boiler is judged according to the initial temperature change table and the extraction temperature change table, when the temperature rise speed of the boiler does not decrease, it is considered that the extracted waste heat is non-influential waste heat, when the temperature rise speed of the boiler decreases, it is considered that the extracted waste heat is influential waste heat, a time interval threshold is established, then different boiler temperatures are extracted according to the time interval threshold, the extraction temperature change table is improved, the turning point time and the turning point temperature are obtained and recorded in the extraction temperature change table in time sequence, the interval time between the turning point time and the last time interval threshold is analyzed and included in the time interval threshold, the temperature rise speed is calculated, the electric energy required to restore the temperature rise speed of the boiler is analyzed, the excess supplement price is calculated according to the excess supplement electric energy and the current electric price, the peak time in the initial temperature change table and the extraction temperature change table is extracted, the standard peak time and the extraction peak time are obtained, then the difference ratio of the standard peak time and the extraction peak time is analyzed, the extension index of the extraction peak time is calculated, the extension index of the extraction peak time and the excess supplement price are calculated, the position of receiving the waste heat is analyzed, the target temperature required to be reached by different waste heat positions is analyzed, the heat range required for the current temperature of different waste heat positions to reach the target temperature is analyzed, the target heat range is obtained, then the target heat range corresponding to the recovered waste heat is matched to obtain the execution heat range, then a waste heat position is selected from the execution heat range, and the recovered waste heat is applied to the corresponding waste heat position, meanwhile the change of different waste heat positions is recorded, the electric energy required to achieve the same waste heat effect is analyzed, and the waste heat value is calculated according to the current electric energy price, the difference between the excess supplement price and the waste heat value is calculated, and the difference between the extracted carbon content and the initial emission content is analyzed.And according to the calculated difference and the difference between the extraction carbon content and the initial emission content, an adjustment scheme of the extraction waste heat speed is generated, and the whole workflow ends.

[0058] Although the present application is disclosed in preferred embodiments as above, it is not intended to limit the present application, and any person skilled in the art can make possible changes and modifications without departing from the spirit and scope of the present application. Therefore, any modification, equivalent change and modification made to the above embodiments according to the technical essence of the present application without departing from the technical solutions of the present application, all fall within the protection scope defined by the claims of the present application.

Claims

1. A control method for flue gas heat recovery in a coal-fired power plant, characterized in that, The flue gas waste heat recovery control method comprises the following steps: S100, collecting the working process of the coal-fired power plant, analyzing the flue gas temperature change of the waste heat according to the working process of the coal-fired power plant, simultaneously acquiring the flow path of the flue gas, monitoring the flue gas impurity content on the flow path by using a Fourier transform infrared spectrometer, and analyzing the mapping relationship table between the flue gas temperature change and the flue gas impurity content change through a linear regression model; S200, recording the temperature change of the boiler when the boiler is working without extracting the waste heat, calculating the temperature rise speed change of the boiler to form an initial temperature change table, collecting the concentration and flow of carbon emissions, calculating the carbon emission content to form an initial emission content; S300, controlling the speed of extracting the waste heat, detecting the temperature change of the boiler, calculating the temperature rise speed, obtaining an extraction temperature change table, judging the influence of different waste heat extraction speeds on the temperature rise speed of the boiler according to the initial temperature change table and the extraction temperature change table, considering that the extracted waste heat is non-influential waste heat when the temperature rise speed of the boiler is not reduced, considering that the extracted waste heat is influential waste heat when the temperature rise speed of the boiler is reduced, collecting the carbon emission content in real time to obtain the extraction carbon content; S400, calculating the decrease amplitude of the temperature rise speed of the boiler, analyzing the electric energy required to restore the temperature rise speed of the boiler, obtaining the excess supplementary electric energy, and then calculating the excess supplementary price according to the excess supplementary electric energy and the current electricity price; S500, combining the non-influential waste heat and the influential waste heat into recovered waste heat, analyzing the position of the received waste heat, controlling the recovered waste heat to act on different waste heat positions, recording the changes of different waste heat positions, obtaining the waste heat effect, analyzing the electric energy required to achieve the same waste heat effect, and calculating the waste heat value according to the current electricity price; S600, calculating the difference between the excess supplementary price and the waste heat value, simultaneously analyzing the gap between the extraction carbon content and the initial emission content, and generating an adjustment scheme of the speed of extracting the waste heat according to the calculated difference and the gap between the extraction carbon content and the initial emission content.

2. The control method of flue gas waste heat recovery of a coal-fired power plant according to claim 1, characterized in that: In the S100, after obtaining the mapping relationship table between the flue gas temperature change and the flue gas impurity content change, different flue gas temperature change values and flue gas impurity content change values are substituted into the linear regression model to obtain corresponding flue gas impurity content prediction values and flue gas temperature prediction values, the flue gas impurity content change and the flue gas temperature change are taken as actual values, at this time, the flue gas impurity content prediction values are compared with the flue gas impurity content change, the flue gas temperature prediction values are compared with the flue gas temperature change, and the error between the prediction values and the actual values is judged.

3. The control method of claim 2, wherein: In the S100, when the error between the prediction values and the actual values is judged, the error between the prediction values and the actual values is combined into a verification difference value, an error range is set, and then the error range, the prediction values and the actual values are used to realize mutual verification between the flue gas temperature change and the flue gas impurity content change, so that the flue gas temperature change and the flue gas impurity content change are more accurately obtained.

4. The method for controlling the flue gas waste heat recovery of a coal-fired power plant according to claim 1, characterized in that: In the S300, when calculating the temperature rising speed, a time interval threshold is established, and then different boiler temperatures are extracted according to the time interval threshold, the extracted temperature change table is perfected, the turning point time and the turning point temperature are obtained, and they are recorded in the extracted temperature change table in time sequence, the interval time between the turning point time and the last time interval threshold is analyzed, and it is included in the time interval threshold.

5. A method of controlling the heat recovery of flue gases from a coal-fired power plant according to claim 4, characterized in that: In the S300, after the temperature change table is obtained, the Xth temperature in the temperature change table is set as W X , the X+1th temperature in the temperature change table is set as W X+1 , the temperature rising speed is set as W S , the time interval threshold value from the last time is set as S Y : The temperature rising speed is calculated by the above formula.

6. A method of controlling flue gas heat recovery in a coal-fired power plant according to claim 1, characterized in that: In the S400, when calculating the falling range of the boiler temperature rising speed, the peak time in the initial temperature change table and the extracted temperature change table is extracted, the standard peak time and the extracted peak time are obtained, the difference ratio of the standard peak time and the extracted peak time is analyzed, and the extension index of the extracted peak time is calculated.

7. The control method of flue gas waste heat recovery of a coal-fired power plant according to claim 6, characterized in that: In the S400, the extension index of the peak time is calculated by setting the peak time value in the initial temperature change table as B F , setting the peak time of the extracted temperature change table as C F , and setting the extension index of the peak time as Y Z . The extension index of the peak time is calculated by the above formula.

8. The control method of claim 7, wherein: In the S400, the excess supplement price is calculated by setting the excess supplement electric energy as G B , setting the current electricity price as D J , setting the excess supplement price as G J : G J = G B ·D J The excess supplement price is calculated by the above formula.

9. The control method of flue gas waste heat recovery of a coal-fired power plant according to claim 1, characterized in that: In the S500, when the recovered waste heat acts on different waste heat positions, the target temperature required by different waste heat positions is analyzed, the heat range required by the current temperature of different waste heat positions to reach the target temperature is analyzed, the target heat range is obtained, the target heat range corresponding to the recovered waste heat is matched, the execution heat range is obtained, one waste heat position is selected from the execution heat range, and the recovered waste heat acts on the corresponding waste heat position.

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