Thermal power plant chlorine balance evaluation method based on principal component analysis

Abstract

The present application relates to the field of environmental protection, and specifically relates to a method for evaluating chlorine balance of a thermal power plant based on principal component analysis, comprising the following steps: S1, data acquisition, real-time sampling of data in multiple links of the thermal power plant, monitoring and analyzing chlorine content of the samples, collecting and establishing original data samples of chlorine content; S2, data processing, checking, cleaning and preliminary statistics of the original data samples; S3, calculation of chlorine balance evaluation indexes, calculating chlorine discharge rate and imbalance rate of the thermal power plant according to the processed data, and establishing chlorine balance evaluation standards; S4, principal component analysis, principal component analysis of the chlorine discharge rate and imbalance rate, and obtaining weights of each principal component; S5, establishment of an evaluation model, based on the results of the principal component analysis, establishing an evaluation model of chlorine balance of the thermal power plant. The present application has the beneficial effect of realizing rapid chlorine balance evaluation and analysis of high-parameter coal-fired thermal power plants through principal component analysis of a large amount of data.

Description

Technical Field

[0001] This invention relates to the field of environmental protection technology, specifically a method for evaluating the chlorine balance of thermal power plants based on principal component analysis. Background Technology

[0002] In today's rapidly developing society, the demand for electricity is increasing year by year. Coal-fired power plants, as the foundation of modern energy industry, provide the vast majority of electricity in my country. However, in recent years, along with the development of the energy industry, environmental issues such as zero wastewater discharge have received increasing attention. For high-parameter coal-fired power plants, chlorine is one of many harmful trace elements. It not only corrodes and clogs boilers and pipes, but also pollutes water resources if discharged indiscriminately. If discharged directly into water bodies without control, it will seriously harm the aquatic environment, affect water quality, disrupt the water balance, and impact freshwater resources, fisheries, and agricultural irrigation. In severe cases, it may even pollute groundwater and drinking water sources.

[0003] Chlorine balance is a crucial concept in thermal power plants, encompassing the distribution and flow of chlorine in various stages, including coal combustion, flue gas, ash, limestone, and desulfurization gypsum. As a trace element, chlorine can undergo numerous chemical reactions and physical changes during power plant operation, thus affecting the overall system's balance and stability. Therefore, monitoring and assessing chlorine balance is essential for ensuring the safe operation of thermal power plants and protecting the environment.

[0004] However, there is currently no specific standard or method for evaluating the chlorine balance of thermal power plants. Power generation companies can only conduct chlorine evaluation and analysis based on their own conditions, lacking a unified analytical and evaluation method. Therefore, it is essential to conduct a comprehensive evaluation of the chlorine balance of thermal power plants. Summary of the Invention

[0005] To address the shortcomings of existing technologies, this invention provides a method for evaluating the chlorine balance of thermal power plants based on principal component analysis. This method utilizes inflow and outflow chlorine content data from already operational thermal power plants to assess the chlorine balance of high-parameter thermal power plants.

[0006] To achieve the above objectives, the present invention adopts the following technical solution:

[0007] The method for evaluating the chlorine balance of thermal power plants based on principal component analysis includes the following steps:

[0008] S1. Data acquisition: Real-time sampling of data from multiple stages of the thermal power plant, monitoring and analyzing the chlorine content of the samples, and collecting and establishing raw data samples of chlorine content.

[0009] S2. Data processing: verifying, cleaning, and performing preliminary statistics on the original data samples;

[0010] S3. Calculation of chlorine balance evaluation index: Calculate the chlorine discharge rate and imbalance rate of thermal power plants based on the treated data, and establish chlorine balance evaluation standards.

[0011] S4. Principal component analysis: Principal component analysis is performed on the chlorine discharge rate and imbalance rate to obtain the weights of each principal component.

[0012] S5. Establish an evaluation model. Based on the results of principal component analysis, establish an evaluation model for the chlorine balance of thermal power plants.

[0013] Furthermore, S1 includes real-time sampling of data from multiple stages of the thermal power plant, including real-time sampling of coal, flue gas, ash, limestone, and desulfurization gypsum.

[0014] Furthermore, real-time sampling in S1 includes the chlorine content entering and leaving the plant; the chlorine entering the thermal power plant includes chlorine in the coal fed into the furnace, desulfurization process water and limestone, and the chlorine leaving the thermal power plant includes chlorine in desulfurization wastewater, gypsum, flue gas, ash and slag.

[0015] Furthermore, in S2, the R language is used to verify, clean, and perform preliminary statistical preprocessing on the chlorine content dataset.

[0016] Furthermore, the following formula is used to calculate the chlorine discharge rate and imbalance rate of thermal power plants in S3:

[0017] Chlorine discharge rate = a / b × 100%

[0018] The chlorine imbalance rate = 2 × (ba) / (b + a) × 100%

[0019] In the formula, a represents the total amount of chlorine flowing out of the thermal power plant; b represents the total amount of chlorine entering the thermal power plant.

[0020] In S3, the evaluation criteria are:

[0021] When the chlorine discharge rate is ≥95% and the chlorine imbalance rate is ≤5%, the chlorine balance evaluation is excellent.

[0022] When the chlorine discharge rate is ≥80% and the chlorine imbalance rate is ≤8%, the chlorine balance is rated as good.

[0023] When the chlorine discharge rate is ≥70% and the chlorine imbalance rate is ≤12%, the chlorine balance is rated as medium.

[0024] When the chlorine discharge rate is ≥60% and the chlorine imbalance rate is ≤20%, the chlorine balance evaluation is qualified.

[0025] When the chlorine discharge rate is <60% or the chlorine imbalance rate is >20%, the chlorine balance evaluation is unqualified.

[0026] Furthermore, in S4, principal component analysis was performed using R language to analyze the chlorine content entering and leaving the thermal power plant.

[0027] The following steps are performed for data preprocessing: The `scale` function in R is used to standardize the data; the `rownames` function defines the names of each row as the first column of the data file; the `as.data.frame` function converts the array into a data frame for principal component analysis (PCA) of chlorine discharge rate and imbalance rate; the `prin1` function in R is used to perform PCA starting from the correlation matrix R; the `summary` function lists the main results of PCA, reducing multiple variables to a few principal components; the `loadings` function in R lists the coefficients corresponding to each principal component and the normalized and orthogonalized eigenvectors of the correlation matrix R; the `screeplot` function in R plots the scree plot of the principal components; and the `biplot` function plots the scatter plot of the data about the first two principal components and the orientation of the original coordinates under the principal components.

[0028] Furthermore, in S5, after using principal component analysis, several principal components with a cumulative contribution rate of 90% of the variance were extracted and used as input variables to construct an evaluation model of the influencing factors of chlorine balance.

[0029] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0030] 1. This invention proposes a method for evaluating chlorine balance, providing an analytical means for evaluating chlorine balance in high-parameter thermal power plants, solving the problem of lacking chlorine balance evaluation, and enabling rapid evaluation and analysis of chlorine balance in high-parameter coal-fired power plants through principal component analysis of a large amount of data.

[0031] 2. Principal component analysis was used to simplify the data and identify the main influencing factors for evaluating the chlorine balance of thermal power plants. Attached Figure Description

[0032] Figure 1 This is a flowchart of a specific embodiment of the principal component analysis-based method for evaluating the chlorine balance of thermal power plants according to the present invention;

[0033] Figure 2 This is a scree diagram of the principal components in a specific embodiment of the principal component analysis-based method for evaluating the chlorine balance of thermal power plants according to the present invention.

[0034] Figure 3 This is a daily component graph with the first principal component as the horizontal axis and the second principal component as the vertical axis. Detailed Implementation

[0035] The present invention will be further described in conjunction with specific embodiments. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of the invention. Furthermore, it should be understood that after reading the teachings of this invention, those skilled in the art can make various alterations or modifications to the invention, and these equivalent forms also fall within the scope defined in this application.

[0036] The method for evaluating the chlorine balance of thermal power plants based on principal component analysis includes the following steps:

[0037] S1. Data Acquisition: Real-time sampling of data from multiple stages of the thermal power plant, monitoring and analyzing the chlorine content of the samples, and collecting and establishing raw data samples of chlorine content; Real-time sampling of data from multiple stages of the thermal power plant includes real-time sampling of coal, flue gas, ash, limestone, and desulfurization gypsum, and real-time sampling includes the chlorine content entering and leaving the thermal power plant; Chlorine entering the thermal power plant includes chlorine in the coal fed into the furnace, desulfurization process water, and limestone, and chlorine leaving the thermal power plant includes chlorine in desulfurization wastewater, gypsum, flue gas, ash, and slag.

[0038] S2. Data processing: R language is used to verify, clean, and perform preliminary statistics on the original data sample;

[0039] S3. Calculation of chlorine balance evaluation index: Calculate the chlorine discharge rate and imbalance rate of thermal power plants based on the treated data, and establish chlorine balance evaluation standards.

[0040] Furthermore, the following formula is used to calculate the chlorine discharge rate and imbalance rate of thermal power plants in S3:

[0041] Chlorine discharge rate = a / b × 100%

[0042] The chlorine imbalance rate = 2 × (ba) / (b + a) × 100%

[0043] In the formula, a represents the total amount of chlorine flowing out of the thermal power plant; b represents the total amount of chlorine entering the thermal power plant.

[0044] In S3, the evaluation criteria are:

[0045] When the chlorine discharge rate is ≥95% and the chlorine imbalance rate is ≤5%, the chlorine balance evaluation is excellent.

[0046] When the chlorine discharge rate is ≥80% and the chlorine imbalance rate is ≤8%, the chlorine balance is rated as good.

[0047] When the chlorine discharge rate is ≥70% and the chlorine imbalance rate is ≤12%, the chlorine balance is rated as medium.

[0048] When the chlorine discharge rate is ≥60% and the chlorine imbalance rate is ≤20%, the chlorine balance evaluation is qualified.

[0049] When the chlorine discharge rate is <60% or the chlorine imbalance rate is >20%, the chlorine balance evaluation is unqualified.

[0050] S4. Principal component analysis: Principal component analysis is performed on the chlorine discharge rate and imbalance rate to obtain the weights of each principal component.

[0051] S5. Establish an evaluation model, using the selected principal components as input variables, to construct an evaluation model of the factors affecting chlorine balance;

[0052] Furthermore, in S2, the R language is used to verify, clean, and perform preliminary statistical preprocessing on the chlorine content dataset.

[0053] Furthermore, in S4, principal component analysis (PCA) of the chlorine content entering and leaving the thermal power plant is performed using R. Specifically, the "scale" function in R is used to standardize the data; the "rownames" function defines the names of each row of data as the first column of the data file; the "as.data.frame" function converts the array into a data frame for PCA preprocessing of chlorine discharge rate and imbalance rate; the "prin1" function in R is used to perform PCA starting from the correlation matrix R; the "summary" function lists the main results of PCA, reducing multiple variables to a few principal components; the "loadings" function in R lists the coefficients corresponding to each principal component and the normalized and orthogonalized eigenvectors of the correlation matrix R; the "screeplot" function in R plots the scree plot of the principal components; and the "biplot" function plots the scatter plot of the data about the first two principal components and the orientation of the original coordinates under the principal components.

[0054] Furthermore, in S5, an evaluation model is established based on the results of principal component analysis to create an evaluation model for the chlorine balance of thermal power plants.

[0055] To clearly illustrate this method, the following data will be used for detailed explanation:

[0056] S1. The chlorine content entering and leaving a high-parameter thermal power plant over a month was collected. The chlorine content in the daily consumed coal, desulfurization process water, and limestone was recorded; the chlorine content in the produced desulfurization wastewater, gypsum, flue gas, ash, and slag was also recorded, and the results are presented in Table 1 below:

[0057] Table 1 Chlorine content at the entrance and exit of thermal power plants

[0058]

[0059] Continued from Table 1

[0060]

[0061] S2. Data processing: R language is used to verify, clean, and perform preliminary statistics on the original data sample;

[0062] S3. Using the recorded data, calculate the daily chlorine discharge rate and imbalance rate of the thermal power plant. The daily chlorine discharge rate and imbalance rate are presented in Table 2 below:

[0063] Table 2 Chlorine discharge rate and imbalance rate

[0064]

[0065] When the chlorine discharge rate is ≥95% and the chlorine imbalance rate is ≤5%, the chlorine balance evaluation is excellent.

[0066] When the chlorine discharge rate is ≥80% and the chlorine imbalance rate is ≤8%, the chlorine balance is rated as good.

[0067] When the chlorine discharge rate is ≥70% and the chlorine imbalance rate is ≤12%, the chlorine balance is rated as medium.

[0068] When the chlorine discharge rate is ≥60% and the chlorine imbalance rate is ≤20%, the chlorine balance evaluation is qualified.

[0069] When the chlorine discharge rate is <60% or the chlorine imbalance rate is >20%, the chlorine balance evaluation is unqualified.

[0070] According to the established chlorine balance evaluation standard, the chlorine balance of this thermal power plant is rated as excellent.

[0071] S4. Use the "scale" function in R to standardize the data. Since the chlorine content in limestone is extremely low, it can be ignored. Use the "rownames" function to define the names of each row of data as the first column of the data file. Use the "as.data.frame" function to convert the array into a data frame and perform principal component analysis data preprocessing for chlorine discharge rate and imbalance rate.

[0072] Principal component analysis (PCA) was performed using the R language function "prin1" from the correlation matrix R. The "summary" function listed the main results of the PCA, reducing multiple variables to a few principal components. The results are shown in Table 3. In the main output, Standard deviation represents the standard deviation of the principal components, which is the square root of the eigenvalues. Proportion of Variance and Cumulative Proportion represent the contribution rate and cumulative contribution rate of the variance, respectively.

[0073] Table 3 Importance of components

[0074]

[0075]

[0076] Continued from Table 3

[0077]

[0078] The coefficients of each principal component and the normalized orthogonalized eigenvectors of the correlation matrix R are listed using the "loadings" function in R. The coefficients of each principal component are shown in Table 4 below.

[0079] Table 4. Coefficients corresponding to each principal component

[0080] Total load / MW 0.370 0.355 0.135 Chlorine in coal / t 0.373 0.335 Chlorine in process water / t 0.373 0.324 Chlorine in ash / t 0.351 0.347 -0.309 -0.782 Chlorine in slag / t 0.250 -0.864 -0.391 -0.106 Chlorine in gypsum / t 0.363 0.238 -0.367 0.195 Chlorine in flue gas / t 0.359 0.209 -0.423 0.565 Chlorine in desulfurization wastewater / t 0.372 -0.138 0.308

[0081] Continued from Table 4

[0082]

[0083] Use the `screeplot` function in R to plot the scree plot of the principal components; use the `biplot` function to plot the scatter plot of the data about the first two principal components and the orientation of the original coordinates under the principal components, such as... Figure 2 , Figure 3 As shown.

[0084] S5. After using principal component analysis, multiple influencing factors are extracted into several principal factors. The following principal components, which account for 90% of the cumulative contribution rate of variance, are identified:

[0085]

[0086] The first few factors with larger eigenvalues ​​can basically cover all the information of the original variable comprehensively. Using them as input variables, an evaluation model of the factors affecting chlorine balance can be constructed. This model can be established using multiple linear regression analysis.

Claims

1. A method for evaluating the chlorine balance of thermal power plants based on principal component analysis, characterized in that, Includes the following steps: S1. Data acquisition: Real-time sampling of data from multiple stages of the thermal power plant, monitoring and analyzing the chlorine content of the samples, and collecting and establishing raw data samples of chlorine content. S2. Data processing: verifying, cleaning, and performing preliminary statistics on the original data samples; S3. Calculation of chlorine balance evaluation index: Calculate the chlorine discharge rate and imbalance rate of thermal power plants based on the treated data, and establish chlorine balance evaluation standards. S4. Principal component analysis: Principal component analysis is performed on the chlorine discharge rate and imbalance rate to obtain the weights of each principal component. S5. Establish an evaluation model. Based on the results of principal component analysis, establish an evaluation model for the chlorine balance of thermal power plants. The following formula is used to calculate the chlorine discharge rate and imbalance rate of thermal power plants in S3: Chlorine discharge rate = a / b × 100% The chlorine imbalance rate = 2 × (ba) / (b + a) × 100% In the formula, 'a' represents the total amount of chlorine flowing out of the thermal power plant; b represents the total amount of chlorine entering the thermal power plant; In S3, the evaluation criteria are: When the chlorine discharge rate is ≥95% and the chlorine imbalance rate is ≤5%, the chlorine balance evaluation is excellent. When the chlorine discharge rate is ≥80% and the chlorine imbalance rate is ≤8%, the chlorine balance is rated as good. When the chlorine discharge rate is ≥70% and the chlorine imbalance rate is ≤12%, the chlorine balance is rated as medium. When the chlorine discharge rate is ≥60% and the chlorine imbalance rate is ≤20%, the chlorine balance evaluation is qualified. When the chlorine discharge rate is <60% or the chlorine imbalance rate is >20%, the chlorine balance evaluation is unqualified. In S4, principal component analysis (PCA) of chlorine content entering and leaving the thermal power plant was performed using R. The "scale" function in R was used to standardize the data; the "rownames" function defined the names of each row as the first column of the data file; the "as.data.frame" function converted the array into a data frame for PCA preprocessing of chlorine discharge rate and imbalance rate; the "prin1" function in R was used to perform PCA starting from the correlation matrix R; the "summary" function listed the main results of the PCA, reducing multiple variables to a few principal components; the "loadings" function in R listed the coefficients corresponding to each principal component and the normalized and orthogonalized eigenvectors of the correlation matrix R; the "screeplot" function in R plotted the scree plot of the principal components; and the "biplot" function plotted the scatter plot of the data about the first two principal components and the orientation of the original coordinates under the principal components.

2. The method for evaluating the chlorine balance of thermal power plants based on principal component analysis according to claim 1, characterized in that, S1 performs real-time sampling of data from multiple stages of a thermal power plant, including real-time sampling of coal, flue gas, ash, limestone, and desulfurization gypsum.

3. The method for evaluating the chlorine balance of thermal power plants based on principal component analysis according to claim 2, characterized in that, Real-time sampling in S1 includes the chlorine content entering and leaving the plant; the chlorine entering the thermal power plant includes chlorine in the coal fed into the furnace, desulfurization process water and limestone, and the chlorine leaving the thermal power plant includes chlorine in desulfurization wastewater, gypsum, flue gas, ash and slag.

4. The method for evaluating the chlorine balance of thermal power plants based on principal component analysis according to claim 1, characterized in that, In S2, the R language is used to verify, clean, and perform preliminary statistical preprocessing on the chlorine content dataset.

5. The method for evaluating the chlorine balance of thermal power plants based on principal component analysis according to claim 1, characterized in that, S5. After using principal component analysis, several principal components with a cumulative contribution rate of 90% of the variance were extracted and used as input variables to construct an evaluation model of the factors affecting chlorine balance.

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