Carbonized fiber purity adjustment and detection system and method based on pre-oxidation furnace

Abstract

The present invention discloses a carbonized fiber purity adjustment and detection system and method based on a preoxidation furnace, and relates to the technical field of preoxidation furnace control. The system comprises: driving the preoxidation furnace according to initial control parameters, and performing preoxidation treatment on a precursor fiber of a preset size to obtain carbonized fiber; selecting a carbonized fiber sample for thermal analysis test, and establishing a thermal weight loss curve of the carbonized fiber according to the test results to obtain the carbon content in the carbonized fiber; comparing the carbon content with the standard content to obtain the purity information of the carbonized fiber, and inferring the standard control parameters of the preoxidation furnace according to the purity information and the initial control parameters; driving the preoxidation furnace according to the standard control parameters to perform preoxidation treatment on the precursor fiber to obtain the carbonized fiber after the purity is adjusted. The present invention can accurately monitor and adjust the key variables in the production process by establishing a thermal weight loss curve of the carbonized fiber and analyzing the carbon content.

Description

Technical Field

[0001] The invention relates to the technical field of pre-oxidation furnace control, and in particular to a carbonized fiber purity adjustment and detection system and method based on a pre-oxidation furnace. Background Art

[0002] Precursor fibers usually refer to raw materials used to make carbon fibers, such as polyacrylonitrile (PAN), asphalt or graphene. These precursor materials are converted into carbonized fibers through specific chemical and thermal treatment processes. During this conversion process, the chemical structure and physical properties of the precursor fibers change, ultimately forming high-strength, high-rigidity carbonized fibers.

[0003] During the conversion stage, the precursor fiber is placed in an oxygen-free or low-oxygen pre-oxidation furnace, and the temperature usually reaches over 1000 degrees Celsius, so that non-carbon elements such as hydrogen and nitrogen are gradually removed from the fiber, leaving a stable structure mainly composed of carbon atoms. Carbonized fiber purity detection is a key quality control step used to determine the content and quality of carbon in carbonized fiber materials, which is crucial for evaluating the performance and applicability of carbon fibers.

[0004] However, in the prior art, when performing carbonized fiber oxidation operations, the control parameters of the pre-oxidation furnace cannot be flexibly adjusted according to the size information of the precursor fiber, and the control parameters of the pre-oxidation furnace cannot be guaranteed to be suitable for the corresponding precursor fiber, thereby reducing the purity and quality of the carbonized fiber.

[0005] Currently, no effective solution has been proposed for the problems in the related technologies. Summary of the invention

[0006] In order to solve the above problems, the present invention proposes a carbonized fiber purity adjustment and detection system and method based on a pre-oxidation furnace, which can achieve precise control of the operating parameters of the pre-oxidation furnace and ensure that the purity of the carbonized fiber is under optimal conditions.

[0007] In order to achieve the above object, the present invention adopts the following technical solution:

[0008] In a first aspect, the present invention provides a carbonized fiber purity adjustment and detection system based on a pre-oxidation furnace, the carbonized fiber purity adjustment and detection system comprising:

[0009] A carbonized fiber oxidation unit is used to drive the pre-oxidation furnace according to initial control parameters to perform pre-oxidation treatment on the precursor fiber of a preset size to obtain carbonized fiber. The initial control parameters include temperature, time and atmosphere. The preset size includes fiber density, twist and cross section of the precursor fiber.

[0010] The carbon content acquisition unit is used to select carbonized fiber samples for thermal analysis test, and establish a thermal weight loss curve of the carbonized fiber according to the test results to obtain the carbon content in the carbonized fiber;

[0011] A fiber purity analysis unit, used to compare the carbon content with the standard content to obtain the purity information of the carbonized fiber, and to infer the standard control parameters of the pre-oxidation furnace based on the purity information and the initial control parameters;

[0012] The carbonized fiber adjustment unit is used to drive the preoxidation furnace to perform preoxidation treatment on the precursor fiber according to standard control parameters to obtain carbonized fiber with adjusted purity.

[0013] Preferably, the carbon content acquisition unit comprises:

[0014] The thermal analysis test module is used to place the selected carbonized fiber sample into the thermal analysis instrument to perform the detection operation according to the preset analysis environment, and record the temperature and thermal weight loss during the detection process;

[0015] Steady-state temperature research module, used to generate a thermogravimetric curve based on temperature and thermogravimetric analysis, analyze the mass loss of carbonized fiber, and determine the steady-state temperature of the carbonized fiber sample based on the mass loss condition;

[0016] The carbon content determination module is used to analyze the decomposition information of the carbonized fiber sample under thermal analysis according to the steady-state temperature, and to determine the mass percentage of carbon in the carbonized fiber sample based on the decomposition information to obtain the carbon content.

[0017] Preferably, generating a thermogravimetric curve based on temperature and thermogravimetric loss, analyzing the mass loss of the carbonized fiber, and determining the steady-state temperature of the carbonized fiber sample according to the mass loss condition comprises:

[0018] The thermal analysis temperature is defined as the horizontal axis, and the thermal weight loss is defined as the vertical axis. Then the curve diagram is drawn using data analysis software to obtain the thermal weight loss curve.

[0019] Based on the thermogravimetric curve and thermal analysis temperature, the thermal analysis process is divided into precipitation stage, combustion stage, burnout stage and decomposition stage, and the state of the carbonized fiber samples in each stage is analyzed.

[0020] The mass loss status of the carbonized fiber was analyzed according to the state results, and the temperature range of thermal decomposition was determined according to the mass loss status and the thermal gravimetric curve to obtain the steady-state temperature of the carbonized fiber sample.

[0021] Preferably, the fiber purity analysis unit comprises:

[0022] A purity information calculation module, used to compare the carbon content of the carbonized fiber sample with the standard carbon content, and obtain the purity information corresponding to the carbonized fiber sample based on the comparison result;

[0023] A control parameter analysis module is used to determine the correlation between the precursor fiber size information and the control parameters of the pre-oxidation furnace based on the purity information combined with the correlation analysis method;

[0024] The control parameter generation module is used to define the fuzzy controller structure by combining correlation with control theory technology, and output the control parameters of the pre-oxidation furnace under specific precursor fiber size information according to the fuzzy controller.

[0025] Preferably, the correlation between the precursor fiber size information and the pre-oxidation furnace control parameters is determined based on the purity information in combination with the correlation analysis method, including:

[0026] The purity information is set as the reference sequence, the fiber density, twist and cross section of the preset size of the precursor fiber are set as the reference data sequence, and the temperature, time and atmosphere of the pre-oxidation furnace are set as the comparison data sequence;

[0027] The reference data sequence and the comparison data sequence are dimensionally normalized, and the grey correlation coefficient between each variable in the comparison data sequence and the reference data sequence is obtained by using the correlation analysis method.

[0028] Based on the grey correlation coefficient and purity information, the Euclidean distance is used to characterize the change approximation rate between the reference data sequence and the comparison data sequence to obtain the Euclidean correlation degree, and the fuzzy correlation similarity matrix is ​​constructed according to the Euclidean correlation degree and the cosine theorem.

[0029] Based on the fuzzy correlation similarity matrix analysis, the dynamic change proximity between each variable in the data sequence and the reference data sequence is compared, and the fuzzy membership is obtained according to the analysis results;

[0030] The correlation between each variable in the comparison data sequence and the reference data sequence is obtained based on the fuzzy membership degree and the Euclidean correlation degree, and the highest ranked variable is used as the direct variable affecting the purity information after the correlation is sorted.

[0031] The process of oxidation of precursor fibers in a pre-oxidation furnace was simulated based on factor design technology and direct variables, and the variable relationship between the direct variable distribution and the control parameters of the pre-oxidation furnace was explored according to the oxidation results.

[0032] Preferably, the process of simulating the oxidation of the precursor fiber in the preoxidation furnace based on the factor design technology and the direct variable, and exploring the variable relationship between the direct variable distribution and the control parameters of the preoxidation furnace according to the oxidation results include:

[0033] Obtain the atmosphere chemical reaction path, reaction rate and atmosphere purity in the pre-oxidation furnace to obtain the atmosphere influencing parameters, and analyze the heat capacity of the pre-oxidation furnace and the temperature influencing parameters generated by the distribution points of the heating components;

[0034] The reaction rate equation of the pre-oxidation furnace is obtained based on the atmosphere influencing parameters and the temperature influencing parameters, and the thermal stability equation is generated according to the temperature rising rate of the pre-oxidation furnace;

[0035] The dimensional condition values ​​are set based on direct variables, and the reaction rate equation and thermal stability equation are solved by combining the Kutta algorithm to analyze the heat transfer law of the pre-oxidation furnace;

[0036] Based on the initial size conditions and heat transfer laws, the factor design technique is used to generate a set of temperature, atmosphere and time control parameters to simulate the oxidation process of precursor fibers in a pre-oxidation furnace under limited size condition values.

[0037] The mass transfer efficiency of the pre-oxidation furnace is analyzed based on the simulation results, the control parameters corresponding to the maximum value of the mass transfer efficiency are selected as the best match for the dimensional condition value, and the variable relationship between the best match and the dimensional condition value is analyzed.

[0038] Preferably, the reaction rate equation is expressed as:

[0039]

[0040] The expression of thermal stability equation is:

[0041]

[0042] Wherein, T represents the reaction rate of the pre-oxidation furnace, W represents the thermal stability of the pre-oxidation furnace, α represents the distribution point of the heating components of the pre-oxidation furnace, δ represents the heat capacity of the pre-oxidation furnace, σ represents the temperature load in the pre-oxidation furnace, υ represents the chemical reaction path of the atmosphere in the pre-oxidation furnace, p represents the reaction rate of the atmosphere in the pre-oxidation furnace, t represents the purity of the atmosphere in the pre-oxidation furnace, φ represents the adiabatic index, ω represents the temperature rise rate of the pre-oxidation furnace, e represents the atmosphere circulation rate in the pre-oxidation furnace, and β represents the gas constant of the atmosphere in the pre-oxidation furnace.

[0043] Preferably, the fuzzy controller structure is defined by combining correlation with control theory technology, and the control parameters of the pre-oxidation furnace under the specific precursor fiber size information output by the fuzzy controller include:

[0044] Based on the oxidation demand of carbonized fiber and the control principle of pre-oxidation furnace, the fuzzy controller structure is defined, and the fuzzy controller structure includes an inference unit, a fuzzification processor, a fuzzy inference unit and a defuzzifier;

[0045] Using sensor data collected by sensors in the pre-oxidation furnace as a control instruction start-up item, and obtaining size information of the precursor fiber when it enters the pre-oxidation furnace based on the sensor data;

[0046] Based on the size information and the correlation results, the oxidation demand of the pre-oxidation furnace when performing the oxidation work is inferred, and the control parameters of the pre-oxidation furnace are processed according to the fuzzy controller structure.

[0047] Preferably, the oxidation demand of the pre-oxidation furnace when performing oxidation work is inferred based on the size information and the correlation result, and the oxidation demand is processed according to the fuzzy controller structure. The control parameters of the pre-oxidation furnace include:

[0048] According to the variable relationship between the size information of the precursor fiber and the control parameters of the pre-oxidation furnace, the oxidation demand required by the pre-oxidation furnace during the oxidation operation of the precursor fiber is analyzed;

[0049] The oxidation demand is input into the fuzzy processor to perform a ratio conversion operation so that the oxidation demand belongs to the corresponding domain, and the reasoner is used to perform fuzzy reasoning on the oxidation demand after the ratio conversion;

[0050] The fuzzy control quantity is generated based on the fuzzy reasoning result, and the defuzzifier is used to defuzzify the fuzzy control quantity to obtain the actual control quantity. The actual control quantity is combined with the PID controller to obtain the operating parameters of the pre-oxidation furnace during the execution process.

[0051] In a second aspect, the present invention further provides a carbonized fiber purity adjustment and detection method based on a pre-oxidation furnace, the carbonized fiber purity adjustment and detection method comprising the following steps:

[0052] The pre-oxidation furnace is driven according to initial control parameters to perform pre-oxidation treatment on the precursor fiber of a preset size to obtain carbonized fiber, wherein the initial control parameters include temperature, time and atmosphere, and the preset size includes fiber density, twist and cross section of the precursor fiber;

[0053] Select carbonized fiber samples for thermal analysis test, and establish a thermal weight loss curve of carbonized fiber based on the test results to obtain the carbon content in the carbonized fiber;

[0054] The carbon content is compared with the standard content to obtain the purity information of the carbonized fiber, and the standard control parameters of the pre-oxidation furnace are inferred based on the purity information and the initial control parameters;

[0055] The preoxidation furnace is driven according to standard control parameters to perform preoxidation treatment on the precursor fiber to obtain carbonized fiber with adjusted purity.

[0056] The beneficial effects of the present invention are:

[0057] 1. The present invention can accurately monitor and adjust key variables in the production process by establishing a thermal weight loss curve of carbonized fiber and analyzing the carbon content, and accurately control the operating parameters of the pre-oxidation furnace based on the key variables to ensure that the purity of the carbonized fiber is under optimal conditions, reduce the waste of energy and raw materials, and adjust the purity of the carbonized fiber according to the adjustment result of the pre-oxidation furnace, thereby improving the high quality of the carbonized fiber product and the efficiency of the carbonized fiber production process.

[0058] 2. The present invention can evaluate the thermal stability of carbonized fibers by monitoring the thermal weight loss of carbonized fiber samples and analyzing their behaviors at different temperatures, and accurately determine the carbon content in carbonized fiber samples based on thermal analysis technology, thereby determining the purity information of carbonized fibers and ensuring that the products meet the required quality standards. At the same time, based on the thermal analysis results, it helps to understand the relationship between different precursor materials and processing conditions and the quality and purity of carbonized fibers, laying a foundation for the subsequent adjustment of the purity of carbonized fibers.

[0059] 3. The present invention compares the actual carbon content with the standard, and finds the relationship between the precursor fiber size information and the pre-oxidation furnace control parameters based on the comparison result and the correlation analysis method. At the same time, through the fuzzy controller, it can flexibly respond to the variable fluctuations and uncertainties in the production process. The fuzzy controller dynamically adjusts the control parameters according to the input precursor fiber size information and carbon fiber purity data to ensure the purity of the carbonized fiber in the later oxidation process. BRIEF DESCRIPTION OF THE DRAWINGS

[0060] The accompanying drawings in the specification, which constitute a part of the present invention, are used to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute improper limitations on the present invention.

[0061] Figure 1 is a principle block diagram of a carbonized fiber purity adjustment and detection system based on a pre-oxidation furnace according to an embodiment of the present invention;

[0062] Figure 2 The present invention is a flowchart of a method for adjusting and detecting the purity of carbonized fibers based on a pre-oxidation furnace according to an embodiment of the present invention.

[0063] In the figure:

[0064] 1. Carbonized fiber oxidation unit; 2. Carbon content acquisition unit; 3. Fiber purity analysis unit; 4. Carbonized fiber adjustment unit. DETAILED DESCRIPTION

[0065] The present invention will be further described below in conjunction with the accompanying drawings and embodiments.

[0066] It should be noted that the following detailed descriptions are exemplary and are intended to provide further explanation of the present invention. Unless otherwise specified, all technical and scientific terms used in the present invention have the same meanings as those commonly understood by those skilled in the art to which the present invention belongs.

[0067] It should be noted that the terms used herein are only for describing specific embodiments, and are not intended to limit exemplary embodiments according to the present invention. As used herein, unless the context clearly indicates otherwise, the singular form is also intended to include the plural form. In addition, it should be understood that the terms "include" and "have" and any of their variations are intended to cover non-exclusive inclusions, for example, a process, method, system, product or device comprising a series of steps or units is not necessarily limited to those steps or units clearly listed, but may include other steps or units that are not clearly listed or inherent to these processes, methods, products or devices.

[0068] In the absence of conflict, the embodiments of the present invention and the features of the embodiments may be combined with each other.

[0069] See also Figure 1 The present invention provides a carbonized fiber purity adjustment and detection system based on a pre-oxidation furnace, and the carbonized fiber purity adjustment and detection system comprises:

[0070] The carbonized fiber oxidation unit 1 is used to drive the pre-oxidation furnace according to the initial control parameters to perform pre-oxidation treatment on the precursor fiber of a preset size to obtain the carbonized fiber.

[0071] In this embodiment, when the pre-oxidation furnace is driven according to the initial control parameters and the precursor fibers of a preset size are pre-oxidized to obtain carbonized fibers, suitable precursor fibers can be selected and ensured to have preset sizes, including fiber density, twisting degree and cross-section size information of the precursor fibers. After the temperature, time and atmosphere of the pre-oxidation furnace are set according to the initial control parameters, the precursor fibers are fed into the pre-oxidation furnace. In the pre-oxidation furnace, the precursor fibers are heated under the set temperature and atmosphere conditions. This process causes partial oxidation of the fibers to form a stable structure to obtain carbonized fibers.

[0072] The carbon content acquisition unit 2 is used to select a carbonized fiber sample for thermal analysis test, and to establish a thermal weight loss curve of the carbonized fiber according to the test result to obtain the carbon content in the carbonized fiber.

[0073] In this embodiment, the carbon content acquisition unit 2 includes:

[0074] The thermal analysis test module is used to place the selected carbonized fiber sample into the thermal analysis instrument to perform the detection operation according to the preset analysis environment, and record the temperature and thermal weight loss during the detection process;

[0075] Steady-state temperature research module, used to generate a thermogravimetric curve based on temperature and thermogravimetric analysis, analyze the mass loss of carbonized fiber, and determine the steady-state temperature of the carbonized fiber sample based on the mass loss condition;

[0076] The carbon content determination module is used to analyze the decomposition information of the carbonized fiber sample under thermal analysis according to the steady-state temperature, and to determine the mass percentage of carbon in the carbonized fiber sample based on the decomposition information to obtain the carbon content.

[0077] In this embodiment, when the selected carbonized fiber sample is placed in the thermal analysis instrument to perform the detection operation according to the preset analysis environment, and the temperature and thermal weight loss during the detection process are recorded, the carbonized fiber sample can be accurately measured and cut to the required specifications in advance to ensure that the sample represents the overall material properties. Then, temperature calibration and baseline calibration are performed to ensure that the thermal analysis instrument is correctly calibrated. The required test conditions are set on the thermal analysis instrument, including the heating rate, maximum temperature, and atmosphere (such as nitrogen or air). The carbonized fiber sample is placed in the sample tray of the thermal analysis instrument, the instrument is started to start heating and record data, and the temperature of the sample and the mass change with temperature are monitored and recorded.

[0078] In this embodiment, when a thermal gravimetric curve is generated based on temperature and thermal gravimetric loss, the mass loss of carbonized fiber is analyzed, and the steady-state temperature of the carbonized fiber sample is determined according to the mass loss status, the thermal analysis temperature can be defined as the horizontal axis, the thermal gravimetric loss can be defined as the vertical axis, and then a curve diagram can be drawn using data analysis software to obtain the thermal gravimetric curve; based on the thermal gravimetric curve and the thermal analysis temperature, the thermal analysis process is divided into precipitation stage, combustion stage, burnout stage and decomposition stage, and the state of the carbonized fiber sample in each stage is analyzed; according to the state results, the mass loss status of the carbonized fiber is analyzed, and the temperature range of thermal decomposition is determined according to the mass loss status and the thermal gravimetric curve to obtain the steady-state temperature of the carbonized fiber sample.

[0079] Specifically, use data analysis software (such as MATLAB or special thermal analysis software), input the temperature and thermal weight loss data collected by the thermal analysis instrument, set the horizontal axis as temperature and the vertical axis as thermal weight loss percentage, draw a thermal weight loss curve to observe the slope change of the thermal weight loss curve, and identify different thermal reaction stages (precipitation stage, combustion stage, burnout stage and decomposition stage);

[0080] Precipitation stage: Located in the low temperature zone, the material may release low molecular weight volatiles.

[0081] Combustion stage: The temperature is higher and the thermal weight loss is accelerated, indicating that the main combustion reaction occurs.

[0082] Burnout stage: Thermal weight loss tends to stabilize, indicating that most of the combustible materials have been burned out.

[0083] Decomposition stage: further thermal decomposition at the highest temperature, accompanied by further carbonization of the structure.

[0084] Calculate the mass change in each stage, analyze its impact on the final performance of the carbonized fiber, determine which stages of mass loss are critical to the structure and performance of the fiber, and determine the temperature range of each stage based on the thermal gravimetric curve. By comparing the mass loss and temperature change in each stage, infer the thermal stability of the carbonized fiber sample in each stage, and determine the stable interval with the smallest temperature change on the thermal gravimetric curve, which is the steady-state temperature of the carbonized fiber sample.

[0085] In this embodiment, when the decomposition information of the carbonized fiber sample under thermal analysis is analyzed according to the steady-state temperature, and the mass percentage of carbon in the carbonized fiber sample is determined based on the decomposition information to obtain the carbon content, the chemical and physical changes of the carbonized fiber sample can be analyzed in the steady-state temperature range to determine the type and amount of the decomposition products. Before determining the carbon content, ensure that the sample is in an appropriate chemical state from the steady-state temperature analysis, select the CHN analyzer carbon content determination method, and place the treated sample in the selected test instrument to determine the carbon content in the sample.

[0086] In order to facilitate understanding of the above technical solution of the present invention, the carbon content determination process in the actual process of the present invention is described in detail below.

[0087] Step 1: Obtaining carbonized fiber:

[0088] Select polyacrylonitrile (PAN) as the precursor fiber, and obtain the corresponding size information according to polyacrylonitrile (PAN), including fiber density: 1.18g / cm 3 , twist: 1000 turns / m, cross section size: 10 μm;

[0089] The temperature of the pre-oxidation furnace is set to 240°C, the oxidation time is set to 90 minutes, and the atmosphere is an air environment with an oxygen concentration of 21%. The precursor fiber is sent into the pre-oxidation furnace for heat treatment to partially oxidize the fiber and form a stable structure to obtain carbonized fiber.

[0090] Step 2: Obtaining carbon content:

[0091] Cut the carbonized fiber sample to the required specifications, set the heating rate of the thermal analysis instrument to 10℃ / min, and the maximum temperature to 800℃ to obtain the temperature of the sample and the mass change with temperature. Set the temperature as the horizontal axis and the thermal weight loss as the vertical axis. Use MATLAB software to draw the thermal weight loss curve. According to the thermal weight loss curve, we know:

[0092] Precipitation stage: occurs at about 250°C to 350°C, mainly the release of low molecular weight volatiles.

[0093] Combustion stage: When heated from 350℃ to 500℃, the rate of thermal weight loss increases rapidly.

[0094] Burnout stage: 500℃ to 650℃, thermal weight loss tends to be stable.

[0095] Decomposition stage: 650℃ to 850℃, the material structure is further carbonized and pyrolyzed.

[0096] Based on the above analysis, the steady-state temperature range was determined to be 700°C to 750°C, and carbonized fiber samples were taken from 700°C to 750°C, and the samples were weighed between milligrams to tens of milligrams to ensure sample representativeness and sufficient mass for analysis.

[0097] The weighed sample is placed in the sample chamber of the CHN analyzer. The sample is placed in a small combustion boat, which will be placed in the combustion furnace of the instrument. At high temperature (usually over 1000°C), the sample is completely burned in an oxygen environment. This process will completely convert the carbon in the sample into carbon dioxide.

[0098] The gas produced by combustion passes through the gas separation system of the instrument, and a gas chromatography column is usually used to separate combustion products such as carbon dioxide, water vapor and nitrogen. The concentration of carbon dioxide is measured by an infrared detector or a thermal conductivity detector, and the carbon content in the sample can be accurately calculated. The instrument software automatically processes the data and calculates the carbon content of the sample based on the calibration curve and the amount of carbon dioxide detected. The output result is usually expressed as the mass percentage of carbon.

[0099] Therefore, by monitoring the thermal weight loss of carbonized fiber samples and analyzing their behavior at different temperatures, the thermal stability of carbonized fibers can be evaluated. By accurately determining the carbon content in carbonized fiber samples based on thermal analysis technology, the purity information of carbonized fibers can be determined to ensure that the product meets the required quality standards.

[0100] The fiber purity analysis unit 3 is used to compare the carbon content with the standard content to obtain the purity information of the carbonized fiber, and to infer the standard control parameters of the pre-oxidation furnace based on the purity information and the initial control parameters.

[0101] In this embodiment, the fiber purity analysis unit 3 includes:

[0102] A purity information calculation module, used to compare the carbon content of the carbonized fiber sample with the standard carbon content, and obtain the purity information corresponding to the carbonized fiber sample based on the comparison result;

[0103] A control parameter analysis module is used to determine the correlation between the precursor fiber size information and the control parameters of the pre-oxidation furnace based on the purity information combined with the correlation analysis method;

[0104] The control parameter generation module is used to define the fuzzy controller structure by combining correlation with control theory technology, and output the control parameters of the pre-oxidation furnace under specific precursor fiber size information according to the fuzzy controller.

[0105] In this embodiment, when the carbon content of the carbonized fiber sample is compared with the standard carbon content and the purity information corresponding to the carbonized fiber sample is obtained based on the comparison result, the standard carbon content percentage of the carbonized fiber can be determined according to the standard or industry specification of the carbonized fiber product, and the carbon content measurement result of the sample is compared with the standard carbon content. If the carbon content of the sample is close to or equal to the standard carbon content, it can be considered that the purity of the sample is high. If the carbon content of the sample is significantly lower than the standard carbon content, it may indicate that impurities or incompletely carbonized precursor fibers are present in the sample.

[0106] In this embodiment, when judging the correlation between the precursor fiber size information and the pre-oxidation furnace control parameters based on the purity information combined with the correlation analysis method, the purity information can be set as the reference sequence, the precursor fiber preset size fiber density, twist and cross section as the reference data sequence, and the pre-oxidation furnace temperature, time and atmosphere as the comparison data sequence; the reference data sequence and the comparison data sequence are dimensionally normalized, and the correlation analysis method is applied to obtain the grey correlation coefficient between each variable in the comparison data sequence and the reference data sequence; based on the grey correlation coefficient and the purity information, the Euclidean distance is used to characterize the change approximation rate between the reference data sequence and the comparison data sequence to obtain Euclidean correlation, and construct a fuzzy correlation similarity matrix based on the Euclidean correlation and the cosine theorem; analyze the dynamic changes between each variable in the comparison data sequence and the reference data sequence based on the fuzzy correlation similarity matrix, and obtain the fuzzy membership based on the analysis results; obtain the correlation between each variable in the comparison data sequence and the reference data sequence based on the fuzzy membership and Euclidean correlation, and then sort the correlations and take the variable with the highest ranking as the direct variable affecting the purity information; simulate the process of oxidation of precursor fiber in the pre-oxidation furnace based on factor design technology and direct variables, and explore the variable relationship between the direct variable distribution and the control parameters of the pre-oxidation furnace according to the oxidation results.

[0107] It is necessary to explain that when applying the grey correlation analysis method and the fuzzy correlation similarity matrix method to determine the influence of the size information of the precursor fiber and the control parameters of the pre-oxidation furnace on the purity, the purity data of the carbonized fiber, the size-related parameters of the precursor fiber, including the fiber density, twist and cross section, and the control parameters of the pre-oxidation furnace, including the temperature setting, heating duration and atmosphere conditions, are obtained as the benchmark sequence, reference data sequence and comparison data sequence;

[0108] To ensure the accuracy and consistency of the data, the Z-score standardization method is used to process all data sequences, as follows:

[0109]

[0110] In the formula, standardized(a) represents the standardized result of the original sequence, a represents the original sequence, m represents the mean value of the original sequence, and n represents the standard deviation of the original sequence.

[0111] After the processing is completed, the grey correlation analysis method is applied to calculate the correlation coefficient between each variable in the comparison data sequence and the reference data sequence. The obtained coefficient reflects the similarity between different variables, as follows:

[0112]

[0113] In the formula, r(i, j) represents the similarity between the i-th sequence in the comparison sequence and the j-th data in the reference data sequence, b0(j) represents the j-th data in the reference data sequence, and b i (j) represents the jth data in the comparison sequence, l represents the resolution coefficient, which is 0.5 in this embodiment, It represents the minimum difference between the i-th sequence in the comparison sequence and the j-th data in the reference data sequence. It represents the maximum difference between the i-th sequence in the comparison sequence and the j-th data in the reference data sequence.

[0114] In this embodiment, when simulating the process of oxidizing precursor fibers in a preoxidation furnace based on factor design technology and direct variables, and exploring the variable relationship between the direct variable distribution and the control parameters of the preoxidation furnace according to the oxidation results, the chemical reaction path, reaction rate and atmosphere purity of the atmosphere in the preoxidation furnace can be obtained to obtain the atmosphere influencing parameters, and the heat capacity and heating component distribution points of the preoxidation furnace are analyzed to generate the temperature influencing parameters; the reaction rate equation of the preoxidation furnace is obtained based on the atmosphere influencing parameters and the temperature influencing parameters, and the thermal stability equation is generated according to the temperature rise rate of the preoxidation furnace; the size condition value is set based on the direct variable, and the reaction rate equation and the thermal stability equation are solved in combination with the Kutta algorithm to analyze the heat transfer law of the preoxidation furnace; based on the initial size condition and the heat transfer law, the factor design technology is used to generate a set of temperature, atmosphere and time control parameters to simulate the process of oxidizing precursor fibers in a preoxidation furnace under the condition of limited size condition values; the mass transfer efficiency of the preoxidation furnace is analyzed based on the simulation results, and the control parameters corresponding to the maximum mass transfer efficiency are selected as the best match of the size condition value, and the variable relationship between the best match and the size condition value is analyzed.

[0115] It should be explained that the atmosphere influencing parameters are data on the chemical reaction path, reaction rate and atmosphere purity of the atmosphere inside the pre-oxidation furnace; the temperature influencing parameters are data on the distribution and heat capacity of the heating elements. If the heating elements are distributed in the upper, middle and lower regions of the furnace body, the heat capacity is 500 J / kg·K.

[0116] Furthermore, the reaction rate equation is expressed as:

[0117]

[0118] The expression of thermal stability equation is:

[0119]

[0120] Wherein, T represents the reaction rate of the pre-oxidation furnace, W represents the thermal stability of the pre-oxidation furnace, α represents the distribution point of the heating components of the pre-oxidation furnace, δ represents the heat capacity of the pre-oxidation furnace, σ represents the temperature load in the pre-oxidation furnace, υ represents the chemical reaction path of the atmosphere in the pre-oxidation furnace, p represents the reaction rate of the atmosphere in the pre-oxidation furnace, t represents the purity of the atmosphere in the pre-oxidation furnace, φ represents the adiabatic index, ω represents the temperature rise rate of the pre-oxidation furnace, e represents the atmosphere circulation rate in the pre-oxidation furnace, and β represents the gas constant of the atmosphere in the pre-oxidation furnace.

[0121] The Kutta algorithm is used to solve the thermal stability equation and the reaction rate equation to obtain the heat transfer law, and the parameters of temperature, atmosphere and time are set through factor design technology, such as the temperature range from 850 to 1150, and the oxidation time from 30 to 120 minutes.

[0122] The Kutta algorithm, also known as the Runge-Kutta method, is a numerical method for solving ordinary differential equations. The basic idea of ​​the Kutta algorithm is to approximate the solution of the differential equation piecewise within a time step, by calculating the slope of the function at different points, and using these slopes to predict the value of the function at the next time point.

[0123] In this embodiment, when the fuzzy controller structure is defined by combining correlation with control theory technology, and the control parameters of the pre-oxidation furnace are determined based on the fuzzy controller output of specific precursor fiber size information, the fuzzy controller structure can be defined based on the oxidation demand of the carbonized fiber and the control principle of the pre-oxidation furnace. The fuzzy controller structure includes an inference unit, a fuzzification processor, a fuzzy inference unit and a defuzzifier. The sensor data collected by the sensor in the pre-oxidation furnace is used as a control instruction start-up item, and the size information of the precursor fiber when entering the pre-oxidation furnace is obtained based on the sensor data. The oxidation demand of the pre-oxidation furnace when performing the oxidation work is inferred based on the size information and the correlation results, and the oxidation demand is processed according to the fuzzy controller structure to obtain the control parameters of the pre-oxidation furnace.

[0124] In this embodiment, when the oxidation demand of the pre-oxidation furnace when performing the oxidation work is inferred based on the size information and the correlation results, and the control parameters of the pre-oxidation furnace are processed according to the fuzzy controller structure, the oxidation demand required by the pre-oxidation furnace in the process of performing the oxidation operation on the precursor fiber can be analyzed according to the variable relationship between the size information of the precursor fiber and the control parameters of the pre-oxidation furnace; the oxidation demand is input into the fuzzification processor to implement a proportional conversion operation so that the oxidation demand belongs to the corresponding domain, and the reasoner is used to perform fuzzy reasoning on the proportionally converted oxidation demand; based on the fuzzy reasoning result, a fuzzy control quantity is generated, and the defuzzifier is used to de-fuzzify the fuzzy control quantity to obtain the actual control quantity, and the actual control quantity is combined with the PID controller to obtain the operating parameters of the pre-oxidation furnace during the execution process.

[0125] It should be explained that the fuzzification processor converts precise input into fuzzy values, the fuzzy reasoner is used to reason according to the fuzzy rule base and output fuzzy results, and the defuzzifier can convert the fuzzy reasoning results into specific control instructions.

[0126] Variable processing: The oxidation demand is calculated based on the sensor data. Assuming that the fiber diameter and the reaction chamber temperature are the key variables, the oxidation demand = diameter × temperature coefficient.

[0127] Fuzzification: Convert the oxidation demand into values ​​in a fuzzy set, for example, divide the oxidation demand into three fuzzy sets of "low", "medium" and "high".

[0128] Fuzzy reasoning: Generate fuzzy control quantity according to the set fuzzy logic rules (assuming the demand is high, increase the temperature setting).

[0129] Defuzzification: Convert the fuzzy control quantity into specific operation instructions, then:

[0130]

[0131] In the formula, Y represents the control output, η represents the control amount, Indicates the degree of membership.

[0132] The defuzzified control output is input into the PID controller for precise adjustment to ensure that the pre-oxidation furnace operates stably according to the predetermined parameters. The proportional (P), integral (I), and differential (D) parameters of the PID are set according to the defuzzification results to optimize the control effect.

[0133] The carbonized fiber adjustment unit 4 is used to drive the preoxidation furnace to perform preoxidation treatment on the precursor fiber according to standard control parameters to obtain carbonized fiber with adjusted purity.

[0134] In this embodiment, when the pre-oxidation furnace is driven according to standard control parameters to perform pre-oxidation treatment on the precursor fiber to obtain carbonized fiber with adjusted purity, parameters such as temperature, atmosphere and time can be adjusted according to the characteristics of the precursor fiber and the standard control parameters of the pre-oxidation furnace. The temperature in the furnace is controlled to gradually increase, usually between 200°C and 300°C, to achieve the purpose of pre-oxidation. The pre-oxidation treatment time is usually maintained from tens of minutes to several hours to ensure that the precursor fiber is fully oxidized.

[0135] In order to facilitate understanding of the above technical solution of the present invention, the pre-oxidation furnace control process in the actual process of the present invention is described in detail below.

[0136] Assuming that the standard carbon content percentage of carbonized fiber is set to 95%, the carbon content of the carbonized fiber sample is measured to be 92%. The carbon content of the sample is slightly lower than the standard carbon content, indicating that a small amount of impurities or incompletely carbonized precursor fibers may exist in the sample, so the purity information of the sample is "low".

[0137] Purity information is used as the reference sequence, set to X0 = [lower], and the precursor fiber preset size information is used as the reference data sequence: fiber density is ρ = 1.3 g / cm 3 , the twist is T = 5°, and the cross section is A = 0.01 cm 2 .

[0138] Pre-oxidation furnace control parameters as comparison data sequence:

[0139] Temperature T furnace =[200°C, 250°C, 300°C];

[0140] Time t furnace =[30min, 60min, 90min];

[0141] Atmosphere tmosphere =[Air, O2, N2].

[0142] Data standardization processing (Z-score standardization): (taking fiber density as an example) standardized value = (ρ-mean value) / standard deviation = (1.3-1.3) / 0.05 = 0; calculate the grey correlation coefficient between the comparison data sequence and the reference data sequence, apply Euclidean distance and cosine theorem to construct a fuzzy correlation similarity matrix, analyze the fuzzy membership, and sort the correlation accordingly.

[0143] Result: Temperature has the highest correlation with purity information and is set as a direct variable.

[0144] The chemical reaction path among the atmosphere influencing parameters is mainly the reaction between O2 and fiber, the reaction rate k=0.05mol / min, and the atmosphere purity is 99% O2.

[0145] Among the temperature influencing parameters, heat capacity C=500J / kg·K, and the heating components are distributed in three areas: upper, middle and lower.

[0146] Factorial design techniques generate a set of control parameters:

[0147] Temperature: 850℃, 950℃, 1050℃, 1150℃;

[0148] Time: 30min, 60min, 90min, 120min;

[0149] Atmosphere: 99% O2;

[0150] The oxidation process was simulated, and the control parameters corresponding to the maximum value of mass transfer efficiency were selected as the best match. The best match was obtained as temperature 1050°C, time 60min, and atmosphere 99% O2.

[0151] The structure of the fuzzy controller is defined to include the inference unit, the fuzzification processor, the fuzzy inference unit and the defuzzification unit.

[0152] Sensor data collection: Precursor fiber diameter d = 0.01 cm, temperature coefficient k temp =0.1.

[0153] Oxidation demand calculation: O Q =d*k temp =0.01*0.1=0.001, fuzzy processing O Q It belongs to the "low" fuzzy set. According to the rules, the fuzzy control quantity "increase temperature" is output. The actual control quantity is obtained by defuzzification, and the temperature is increased by 50℃. The PID parameters are set in combination with the PID controller to optimize the control effect.

[0154] The pre-oxidation furnace was driven according to standard control parameters: the temperature was set to 1050°C (adjusted according to the fuzzy controller output), the time was 60 min, and the atmosphere was 99% O2.

[0155] The precursor fiber is placed in a pre-oxidation furnace and pre-oxidized according to the set temperature, time and atmosphere parameters to obtain carbonized fiber with adjusted purity;

[0156] Take out the treated carbonized fiber sample and conduct purity test to confirm whether the carbon content is close to or reaches the standard value of 95%.

[0157] Therefore, by comparing the actual carbon content with the standard, and finding the relationship between the precursor fiber size information and the pre-oxidation furnace control parameters based on the comparison results and the correlation analysis method, and at the same time using the fuzzy controller to flexibly respond to variable fluctuations and uncertainties in the production process, the fuzzy controller dynamically adjusts the control parameters according to the input precursor fiber size information and carbon fiber purity data to ensure the purity of the carbonized fiber in the later oxidation process.

[0158] See also Figure 2 The present invention also provides a carbonized fiber purity adjustment and detection method based on a pre-oxidation furnace, and the carbonized fiber purity adjustment and detection method comprises the following steps:

[0159] The pre-oxidation furnace is driven according to initial control parameters to perform pre-oxidation treatment on the precursor fiber of a preset size to obtain carbonized fiber, wherein the initial control parameters include temperature, time and atmosphere, and the preset size includes fiber density, twist and cross section of the precursor fiber;

[0160] Select carbonized fiber samples for thermal analysis test, and establish a thermal weight loss curve of carbonized fiber based on the test results to obtain the carbon content in the carbonized fiber;

[0161] The carbon content is compared with the standard content to obtain the purity information of the carbonized fiber, and the standard control parameters of the pre-oxidation furnace are inferred based on the purity information and the initial control parameters;

[0162] The preoxidation furnace is driven according to standard control parameters to perform preoxidation treatment on the precursor fiber to obtain carbonized fiber with adjusted purity.

[0163] In summary, with the help of the above technical scheme of the present invention, the present invention can accurately monitor and adjust the key variables in the production process by establishing the thermal weight loss curve of carbonized fiber and analyzing the carbon content, and accurately control the operating parameters of the pre-oxidation furnace based on the key variables to ensure that the purity of the carbonized fiber is under the best conditions, reduce the waste of energy and raw materials, and adjust the purity of the carbonized fiber according to the adjustment result of the pre-oxidation furnace, thereby improving the high quality of the carbonized fiber product and the efficiency of the carbonized fiber production process. The present invention can evaluate the thermal stability of the carbonized fiber by monitoring the thermal weight loss of the carbonized fiber sample and analyzing its behavior at different temperatures, and accurately determine the carbon content in the carbonized fiber sample based on thermal analysis technology, and can judge the purity information of the carbonized fiber to ensure that the product meets the required quality standards. At the same time, based on the thermal analysis results, it helps to understand the relationship between different precursor materials and processing conditions and the quality and purity of the carbonized fiber, laying a foundation for the later adjustment of the purity of the carbonized fiber. The present invention compares the actual carbon content with the standard, and finds the relationship between the precursor fiber size information and the pre-oxidation furnace control parameters based on the comparison result and the correlation analysis method. At the same time, through the fuzzy controller, it is flexibly cope with the variable fluctuations and uncertainties in the production process. The fuzzy controller dynamically adjusts the control parameters according to the input precursor fiber size information and carbon fiber purity data to ensure the purity of the carbonized fiber in the later oxidation process.

[0164] Those skilled in the art will appreciate that the units, i.e., algorithm steps, of the various examples described in conjunction with this embodiment can be implemented in electronic hardware or in a combination of computer software and electronic hardware. Whether these functions are performed in hardware or software depends on the specific application and design constraints of the technical solution. Professional and technical personnel can use different methods to implement the described functions for each specific application, but such implementation should not be considered to be beyond the scope of this application.

[0165] Although the above describes the specific implementation mode of the present invention in conjunction with the accompanying drawings, it is not intended to limit the scope of protection of the present invention. Those skilled in the art should understand that various modifications or variations that can be made by those skilled in the art on the basis of the technical solution of the present invention without creative work are still within the scope of protection of the present invention.

Claims

1. A carbonized fiber purity adjustment and detection system based on a pre-oxidation furnace, characterized in that: include: A carbonized fiber oxidation unit, used to drive the pre-oxidation furnace according to initial control parameters, and perform pre-oxidation treatment on the precursor fiber of preset size to obtain carbonized fiber, wherein the initial control parameters include temperature, time and atmosphere, and the preset size includes fiber density, twist and cross section of the precursor fiber; The carbon content acquisition unit is used to select carbonized fiber samples for thermal analysis test, and establish a thermal weight loss curve of the carbonized fiber according to the test results to obtain the carbon content in the carbonized fiber; A fiber purity analysis unit, used to compare the carbon content with the standard content to obtain the purity information of the carbonized fiber, and to infer the standard control parameters of the pre-oxidation furnace based on the purity information and the initial control parameters; A carbonized fiber adjustment unit is used to drive a preoxidation furnace to perform preoxidation treatment on the precursor fiber according to standard control parameters to obtain carbonized fibers with adjusted purity; The carbon content acquisition unit comprises: The thermal analysis test module is used to place the selected carbonized fiber sample into the thermal analysis instrument to perform the detection operation according to the preset analysis environment, and record the temperature and thermal weight loss during the detection process; The steady-state temperature research module is used to define the thermal analysis temperature as the horizontal axis and the thermal weight loss as the vertical axis, and then use the data analysis software to draw a curve diagram to obtain the thermal weight loss curve; based on the thermal weight loss curve and the thermal analysis temperature, the thermal analysis process is divided into precipitation stage, combustion stage, burnout stage and decomposition stage, and the state of the carbonized fiber samples in each stage is analyzed; the mass loss status of the carbonized fiber is analyzed according to the state results, and the temperature range of thermal decomposition is determined in combination with the thermal weight loss curve to obtain the steady-state temperature of the carbonized fiber sample.

2. The carbonized fiber purity adjustment and detection system based on the pre-oxidation furnace according to claim 1 is characterized in that: The carbon content acquisition unit also includes: The carbon content determination module is used to analyze the decomposition information of the carbonized fiber sample under thermal analysis according to the steady-state temperature, and to determine the mass percentage of carbon in the carbonized fiber sample based on the decomposition information to obtain the carbon content.

3. The carbonized fiber purity adjustment and detection system based on the pre-oxidation furnace according to claim 1 is characterized in that: The fiber purity analysis unit comprises: A purity information calculation module, used to compare the carbon content of the carbonized fiber sample with the standard carbon content, and obtain the purity information corresponding to the carbonized fiber sample based on the comparison result; A control parameter analysis module is used to determine the correlation between the precursor fiber size information and the control parameters of the pre-oxidation furnace based on the purity information combined with the correlation analysis method; The control parameter generation module is used to define the fuzzy controller structure by combining correlation with control theory technology, and output the control parameters of the pre-oxidation furnace under specific precursor fiber size information according to the fuzzy controller.

4. The carbonized fiber purity adjustment and detection system based on the pre-oxidation furnace according to claim 3 is characterized in that: The method of judging the correlation between the precursor fiber size information and the pre-oxidation furnace control parameters based on the purity information and in combination with the correlation analysis method includes: The purity information is set as the reference sequence, the fiber density, twist and cross section of the preset size of the precursor fiber are set as the reference data sequence, and the temperature, time and atmosphere of the pre-oxidation furnace are set as the comparison data sequence; The reference data sequence and the comparison data sequence are dimensionally normalized, and the grey correlation coefficient between each variable in the comparison data sequence and the reference data sequence is obtained by using the correlation analysis method. Based on the grey correlation coefficient and purity information, the Euclidean distance is used to characterize the change approximation rate between the reference data sequence and the comparison data sequence to obtain the Euclidean correlation degree, and the fuzzy correlation similarity matrix is ​​constructed according to the Euclidean correlation degree and the cosine theorem. Based on the fuzzy correlation similarity matrix analysis, the dynamic change proximity between each variable in the data sequence and the reference data sequence is compared, and the fuzzy membership is obtained according to the analysis results; The correlation between each variable in the comparison data sequence and the reference data sequence is obtained based on the fuzzy membership degree and the Euclidean correlation degree, and the highest ranked variable is used as the direct variable affecting the purity information after the correlation is sorted. The process of oxidation of precursor fibers in a pre-oxidation furnace was simulated based on factor design technology and direct variables, and the variable relationship between the direct variable distribution and the control parameters of the pre-oxidation furnace was explored according to the oxidation results.

5. The carbonized fiber purity adjustment and detection system based on the pre-oxidation furnace according to claim 4 is characterized in that: The process of simulating the oxidation of precursor fibers in a pre-oxidation furnace based on factor design technology and direct variables, and exploring the variable relationship between the direct variable distribution and the control parameters of the pre-oxidation furnace according to the oxidation results include: Obtain the atmosphere chemical reaction path, reaction rate and atmosphere purity in the pre-oxidation furnace to obtain the atmosphere influencing parameters, and analyze the heat capacity of the pre-oxidation furnace and the temperature influencing parameters generated by the distribution points of the heating components; The reaction rate equation of the pre-oxidation furnace is obtained based on the atmosphere influencing parameters and the temperature influencing parameters, and the thermal stability equation is generated according to the temperature rising rate of the pre-oxidation furnace; The dimensional condition values ​​are set based on direct variables, and the reaction rate equation and thermal stability equation are solved by combining the Kutta algorithm to analyze the heat transfer law of the pre-oxidation furnace; Based on the initial size conditions and heat transfer laws, the factor design technique is used to generate a set of temperature, atmosphere and time control parameters to simulate the oxidation process of precursor fibers in a pre-oxidation furnace under limited size condition values. The mass transfer efficiency of the pre-oxidation furnace is analyzed based on the simulation results, the control parameters corresponding to the maximum value of the mass transfer efficiency are selected as the best match for the dimensional condition value, and the variable relationship between the best match and the dimensional condition value is analyzed.

6. The carbonized fiber purity adjustment and detection system based on the pre-oxidation furnace according to claim 5 is characterized in that: The reaction rate equation is expressed as: ； The expression of the thermal stability equation is: ； In the formula, T represents the reaction rate of the pre-oxidation furnace, W Indicates the thermal stability of the pre-oxidation furnace, α Indicates the distribution points of heating components of the pre-oxidation furnace, δ represents the heat capacity of the pre-oxidation furnace, σ Indicates the temperature load in the pre-oxidation furnace, υ Indicates the chemical reaction path of the atmosphere in the pre-oxidation furnace, p Indicates the reaction rate of the atmosphere in the pre-oxidation furnace, t Indicates the purity of the atmosphere in the pre-oxidation furnace. φ represents the adiabatic index, ω Indicates the temperature rise rate of the pre-oxidation furnace, e Indicates the atmosphere circulation rate in the pre-oxidation furnace, β Represents the gas constant of the atmosphere in the pre-oxidation furnace.

7. The carbonized fiber purity adjustment and detection system based on the pre-oxidation furnace according to claim 6 is characterized in that: The fuzzy controller structure is defined by combining the correlation with the control theory technology, and the control parameters of the pre-oxidation furnace under the specific precursor fiber size information output by the fuzzy controller include: A fuzzy controller structure is defined based on the oxidation demand of carbonized fiber and the control principle of the pre-oxidation furnace, wherein the fuzzy controller structure includes an inference unit, a fuzzification processor, a fuzzy inference unit and a defuzzifier; Using sensor data collected by sensors in the pre-oxidation furnace as a control instruction start-up item, and obtaining size information of the precursor fiber when it enters the pre-oxidation furnace based on the sensor data; Based on the size information and the correlation results, the oxidation demand of the pre-oxidation furnace when performing the oxidation work is inferred, and the control parameters of the pre-oxidation furnace are processed according to the fuzzy controller structure.

8. The carbonized fiber purity adjustment and detection system based on the pre-oxidation furnace according to claim 7 is characterized in that: The oxidation demand of the pre-oxidation furnace when performing oxidation work is inferred based on the size information and the correlation result, and the oxidation demand is processed according to the fuzzy controller structure. The control parameters of the pre-oxidation furnace include: According to the variable relationship between the size information of the precursor fiber and the control parameters of the pre-oxidation furnace, the oxidation demand required by the pre-oxidation furnace during the oxidation operation of the precursor fiber is analyzed; The oxidation demand is input into the fuzzy processor to perform a ratio conversion operation so that the oxidation demand belongs to the corresponding domain, and the reasoner is used to perform fuzzy reasoning on the oxidation demand after the ratio conversion; The fuzzy control quantity is generated based on the fuzzy reasoning result, and the defuzzifier is used to defuzzify the fuzzy control quantity to obtain the actual control quantity. The actual control quantity is combined with the PID controller to obtain the operating parameters of the pre-oxidation furnace during the execution process.

9. A method for adjusting and detecting the purity of carbonized fibers based on a preoxidation furnace, used to implement the operation of a system for adjusting and detecting the purity of carbonized fibers based on a preoxidation furnace according to any one of claims 1 to 8, characterized in that: The carbonized fiber purity adjustment and detection method comprises the following steps: Driving the pre-oxidation furnace according to initial control parameters to pre-oxidize the precursor fiber of a preset size to obtain carbonized fiber, wherein the initial control parameters include temperature, time and atmosphere, and the preset size includes fiber density, twist and cross section of the precursor fiber; Select carbonized fiber samples for thermal analysis test, and establish a thermal weight loss curve of carbonized fiber based on the test results to obtain the carbon content in the carbonized fiber; The carbon content is compared with the standard content to obtain the purity information of the carbonized fiber, and the standard control parameters of the pre-oxidation furnace are inferred based on the purity information and the initial control parameters; The preoxidation furnace is driven according to standard control parameters to perform preoxidation treatment on the precursor fiber to obtain carbonized fiber with adjusted purity; The step of selecting a carbonized fiber sample for thermal analysis testing and establishing a thermal weight loss curve of the carbonized fiber according to the test results to obtain the carbon content in the carbonized fiber includes: The selected carbonized fiber sample is placed in a thermal analysis instrument to perform the detection operation according to the preset analysis environment, and the temperature and thermal weight loss during the detection process are recorded; The thermal analysis temperature is defined as the horizontal axis and the thermal weight loss is defined as the vertical axis, and then a curve diagram is drawn using data analysis software to obtain a thermal weight loss curve; based on the thermal weight loss curve and the thermal analysis temperature, the thermal analysis process is divided into precipitation stage, combustion stage, burnout stage and decomposition stage, and the state of the carbonized fiber samples in each stage is analyzed; the mass loss status of the carbonized fiber is analyzed according to the state results, and the temperature range of thermal decomposition is determined in combination with the thermal weight loss curve to obtain the steady-state temperature of the carbonized fiber sample.

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