A method for calculating and implanting continuous pyrolysis rate of wood biomass based on thermogravimetric experiment

Abstract

This invention discloses a method for calculating and implanting the continuous pyrolysis rate of lignocellulosic biomass based on thermogravimetric analysis, belonging to the field of energy utilization technology. The method includes: conducting multiple thermogravimetric experiments on lignocellulosic biomass at a specified heating rate, and obtaining the apparent activation energy E based on the Friedman conversion method. α The curve of conversion rate α and the pre-factor A α The continuous curve of the ln value of the product of the reaction mechanism function f(α) and the reaction mechanism function f(α) is obtained, and then the continuous pyrolysis rate is calculated using the Arrhenius formula; a piecewise polynomial is used to calculate E. α -α and ln[A α The pyrolysis rate is recalculated based on the fitted formula, with corrections made for calculation fluctuations and supplementary information for the uncalculated final stage of pyrolysis. The piecewise polynomial is transformed into an array form for embedding, allowing direct embedding of the Arrhenius formula and supplementary equations, thus enabling the calculation and code embedding of the continuous pyrolysis rate of lignocellulosic biomass. This invention provides a methodological reference for calculating the pyrolysis rate during the combustion process of lignocellulosic biomass.

Description

Technical Field

[0001] This invention relates to the field of energy utilization technology, and in particular to a method for calculating and implanting the continuous pyrolysis rate of lignocellulosic biomass based on thermogravimetric analysis. Background Technology

[0002] Biofuels are fuels in liquid, solid, or gaseous states derived from biomass feedstocks. They are a renewable energy source and play a crucial role in zero-carbon initiatives. Biofuels can originate from lignocellulosic biomass, algal biomass, animal residues, or industrial waste. Among these, lignocellulosic biomass, primarily consisting of hemicellulose, cellulose, and lignin, has the widest range of applications. Predicting its pyrolysis process is an important means of improving energy efficiency and combustion systems. The most critical parameter in pyrolysis prediction is the pyrolysis rate, which relates to the predicted rate of product release and degree of pyrolysis, thus affecting prediction accuracy.

[0003] Thermogravimetric analysis (TGA) is a method for studying the thermal behavior of materials using a thermogravimetric analyzer. It can be used for various biofuel quality analyses, including thermal degradation, ignition, burnout, and reactivity. TGA can also cover thermochemical process analysis, such as baking, pyrolysis, gasification, and combustion, and different heating rates or residence times can be applied to study the thermal degradation behavior of substances. This technology plays a crucial role in advancing the development of bio-based material recycling technologies.

[0004] The pyrolysis of lignocellulosic biomass involves numerous decomposition reactions, and its pyrolysis kinetic parameters (apparent activation energy E, pre-conversion factor A, etc.) typically vary with the conversion rate. Conversion methods such as Flynn-Wall-Ozawa (FWO) and Kissinger-Akahira-Sunose (KAS) are commonly used to estimate the apparent activation energy, but they contain significant errors, especially in scenarios where the activation energy varies. The frequency factor is usually calculated using the Kissinger method, which requires assumptions that the chemical reaction follows a first-order chemical reaction model and that the kinetic parameters are constant, thus failing to accurately describe the complex kinetic behavior of the reaction. Using these methods may lead to large errors in the calculated apparent activation energy and frequency factor, thereby affecting the calculation of thermodynamic parameters.

[0005] The method described above for calculating pyrolysis rates has several serious problems: the data between conversion sampling intervals cannot be effectively determined; the calculation of reaction rates using average activation energy and frequency factor introduces significant errors, and incorrect pyrolysis rates can lead to incorrect heat release, potentially amplifying the errors and affecting the accuracy of the calculations. Therefore, the above method has obvious limitations, and a more accurate method for calculating continuous pyrolysis rates is urgently needed. Summary of the Invention

[0006] This invention provides a method for calculating and implanting the continuous pyrolysis rate of lignocellulosic biomass based on thermogravimetric analysis. The conversion rate as a function of time and temperature is obtained through thermogravimetric experiments at different heating rates, and the apparent activation energy E is then obtained through a series of methods. α The curve of conversion rate α and the pre-factor A α The curve and fitting formula of the ln value of the product of the reaction mechanism function f(α) and the conversion rate α can be used to calculate the continuous pyrolysis rate based on the Arrhenius formula. Subsequent code can be implanted based on the fitting formula to facilitate numerical calculation and solve the technical problem of low accuracy in predicting the pyrolysis rate of wood biomass.

[0007] To solve the above-mentioned technical problems, the present invention provides the following technical solution:

[0008] On one hand, the present invention provides a method for calculating and implanting the continuous pyrolysis rate of lignocellulosic biomass based on thermogravimetric analysis, wherein the method includes:

[0009] Multiple thermogravimetric experiments were conducted on lignocellulosic biomass at a specified heating rate. The weight of the samples as a function of time and temperature was derived, and the apparent activation energy E was obtained based on the Friedman conversion method. α The curve of conversion rate α and the pre-factor A α The curve of the ln value of the product of the reaction mechanism function f(α) and the conversion rate α is obtained. The pyrolysis rate is calculated by the Arrhenius formula to obtain the continuity curve of the pyrolysis rate with the sample conversion rate.

[0010] Using piecewise polynomials to transform E α -α and ln[A] α The pyrolysis rate is fitted by f(α)]-α, and the pyrolysis rate is recalculated based on the fitted formula. The calculation fluctuations are corrected, and the uncalculated end-stage of pyrolysis is supplemented.

[0011] By converting the piecewise polynomial into an array form for embedding, the Arrhenius formula and supplementary equations can be directly embedded, thereby enabling the calculation and code embedding of the continuous pyrolysis rate of lignocellulosic biomass.

[0012] Furthermore, multiple thermogravimetric experiments were conducted on the woody biomass at a specified heating rate to derive the weight variation curves of the samples over time and temperature, including:

[0013] For specific woody biomass, powder is prepared and dried. Multiple thermogravimetric experiments are conducted using a thermogravimetric analyzer at different heating rates. The heating rate is generally set to 5K / min and 10K / min, and nitrogen atmosphere is used. The heating range is determined according to the actual application scenario.

[0014] Based on the sample weight change curves generated by the instrument over time and temperature, the sample conversion rate α is plotted as a function of time and temperature.

[0015] Furthermore, the sample powder needs to be sieved through a mesh screen to ensure that the particle size is less than 0.18 mm, and only about 3-5 mg is needed for a single thermogravimetric experiment; a low heating rate, small sample volume, and fine wood chips are selected to reduce the impact of heat transfer on the measurement results.

[0016] Furthermore, the sample conversion rate is the degree of pyrolysis of the sample. When the sample is not pyrolyzed, its conversion rate is 0, and the conversion rate after complete pyrolysis is 1.

[0017] Furthermore, E is obtained based on the transformation method of Friedman et al. α -α and ln[A] α The continuous curve of f(α)-α is obtained by calculating the pyrolysis rate using the Arrhenius formula, thus obtaining the continuous curve of the pyrolysis rate as a function of sample conversion rate, including:

[0018] Based on thermogravimetric experimental data, the apparent activation energy E of pyrolysis can be solved using the Friedman conversion method. α and frequency factor A α The ln value of the product of the mechanistic function f(α), i.e., ln[A] α ·f(α)]-α, thereby obtaining E α -α and ln[A] α The f(α)-α curve;

[0019] Based on the acquired E α -α and ln[A] α The f(α)-α curve is obtained using the Arrhenius formula dα / dt=Ae -α / R·T ·f(α)=e^{ln[A α ·f(α)]-E α / (R·T α,i The conversion rate dα / dt is calculated, and the pyrolysis rate can be obtained by multiplying the conversion rate by the sample mass, thus obtaining the continuity curve of the pyrolysis rate with the sample conversion rate.

[0020] Furthermore, the Friedman transformation method is a data processing method, specifically as follows:

[0021] Substituting the heating rate β = dT / dt into the Arrhenius formula dα / dt = Ae -E / R·T ·f(α), we get ln[β] i (dα / dt) α,i ] = ln[A α ·f(α)]-Eα / (R·T α,i ), where R is the ideal gas constant, T α,i The temperatures are given at different heating rates i and different conversion rates α.

[0022] Obtain ln(β·dα / dT) and -1000 / (RT) data for different heating rates i and the same conversion rate α. Connect two points with the same conversion rate and calculate the slope and intercept of the line.

[0023] The slope of the straight line is the apparent activation energy E of pyrolysis. α The intercept is ln[A] α ·f(α)]-α.

[0024] Furthermore, using piecewise polynomials for E α -α and ln[A] α The pyrolysis rate is then fitted using the formula f(α)-α, and corrected for calculation fluctuations by recalculating the fitted formula. This includes:

[0025] For E α -α and ln[A] α The f(α)-α curve is piecewise polynomial fitted to obtain the fitting formula, and the fitting formula is substituted into the Arrhenius formula to obtain the dα / dt-α curve.

[0026] The linear form of ln[A] based on the Arrhenius formula α ·f(α)]-E α / (R·T α,i The curve fluctuation correction is performed using ln(dα / dt). Specifically, under the same conversion rate, let the ln(dα / dt) values ​​for two different heating rates be C1 and C2, respectively, to obtain E. α =(C1-C2) / [1 / (R·T) α,2 )–1 / (R·T α,1 )],ln[A α ·f(α)]=C1+E α / (R·T α,1 );

[0027] Fit the ln(dα / dt)-α curves and T-α curves for different conversion rates, and substitute the fitting formula into the above equation to solve for E. α andln[A α ·f(α)], thereby correcting the conversion rate data in the fluctuation region.

[0028] Furthermore, the piecewise fitting method is prone to data differences at the endpoints of the segments, resulting in fluctuations in the recalculated dα / dt-α curve.

[0029] Furthermore, supplementary information is provided for the incalculable final stage of pyrolysis, including:

[0030] In the final stage of pyrolysis, the conversion rate is calculated using dα / dt=(dα / dT)·(dT / dt). Specifically, dα / dT is solved based on the thermogravimetric data as a function of temperature, and then the data is simplified piecewise to obtain a simplified linear fitting formula. Finally, dT / dt is solved based on the temperature-time data to calculate the pyrolysis rate in the final stage of pyrolysis.

[0031] Furthermore, piecewise polynomial fitting methods cannot be used in the final stage of pyrolysis: E α andln[A α The value of f(α) becomes negative after the conversion rate reaches a certain value, and the data difference is large. The piecewise fitting method cannot fit the data of the subsequent stage, so the pyrolysis rate of this stage cannot be calculated.

[0032] Furthermore, the piecewise polynomial is transformed into an array form for embedding, allowing the Arrhenius formula and supplementary equations to be directly embedded, including:

[0033] Organize the coefficients of the piecewise polynomial into an array, and transform a large amount of experimental data into an array of polynomial coefficients to facilitate code insertion and correction.

[0034] The Arrhenius formula and its supplementary equations do not require experimental data and can be directly implemented.

[0035] Based on thermogravimetric analysis results of woody biomass, this invention proposes a method for calculating the continuous curve of the product of apparent activation energy, preconditioner, and mechanism function as a function of conversion rate, as well as a piecewise polynomial fitting method for the curve. This method can calculate the continuous pyrolysis rate as a function of conversion rate. The fitting formula is then incorporated for easy calculation, thus providing a reference for predicting the pyrolysis process of woody biomass.

[0036] Compared with the prior art, the beneficial effects of the technical solution provided by the present invention include at least the following:

[0037] 1. Conventional methods for calculating the pyrolysis rate of lignocellulosic biomass typically use the average apparent activation energy and a pre-factor to describe the pyrolysis reaction kinetics. This invention, however, obtains data on the changes in the thermogravimetric mass of lignocellulosic biomass over time and temperature based on thermogravimetric experiments. Then, it uses the Friedman conversion method and the Arrhenius formula to obtain the continuous Et. α -α and ln[A] α The f(α)-α curve has a higher sampling rate, providing a more accurate data basis for calculating the pyrolysis rate.

[0038] 2. This invention uses E α -α and ln[A] α The f(α)-α curve was fitted and corrected using a piecewise polynomial to obtain a coefficient array that is easy to embed into the code, thus avoiding the need to process a large amount of experimental data during the calculation process and improving the calculation efficiency. This invention also provides an effective calculation and embedding method for calculating the pyrolysis rate at the end of the pyrolysis stage, which can provide an important methodological basis for predicting the entire pyrolysis process of woody biomass. Attached Figure Description

[0039] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0040] Figure 1 This is a schematic diagram of the execution flow of the method for calculating and implanting continuous pyrolysis rate of lignocellulosic biomass based on thermogravimetric analysis provided in an embodiment of the present invention.

[0041] Figure 2 These are the TG and DTG curves of the Finnish pine sample generated by the thermogravimetric analyzer provided in this embodiment of the invention.

[0042] Figure 3 This is a conversion rate α and dα / dT curve as a function of temperature, calculated based on TG and DTG data of Finnish pine samples provided in this embodiment of the invention.

[0043] Figure 4 These are the ln(β·dα / dT) and -1000 / (RT) data provided in the embodiments of the present invention for different heating rates i and the same conversion rate α;

[0044] Figure 5 This is the calculation curve of the conversion rate dα / dt provided in the embodiments of the present invention;

[0045] Figure 6 This is the conversion rate dα / dt curve calculated based on the fitting formula provided in this embodiment of the invention;

[0046] Figure 7 This is the corrected and supplemented conversion rate dα / dt curve provided in the embodiments of the present invention. Detailed Implementation

[0047] To make the objectives, technical solutions, and advantages of the present invention clearer, the embodiments of the present invention will be described in further detail below with reference to the accompanying drawings.

[0048] First, it should be noted that in the embodiments of the present invention, the words "exemplarily," "for example," etc., are used to indicate that they are examples, illustrations, or descriptions. Any embodiment or design scheme described as "exemplary" in the present invention should not be construed as being more preferred or advantageous than other embodiments or design schemes. Specifically, the use of the term "exemplarily" is intended to present the concept in a specific manner. Furthermore, in the embodiments of the present invention, the meaning expressed by "and / or" can be both, or it can be either one or the other.

[0049] Furthermore, in the embodiments of the present invention, the terms "image" and "picture" may sometimes be used interchangeably. It should be noted that, without emphasizing the distinction between them, their intended meanings are consistent. Similarly, the terms "of," "corresponding (relevant)," and "corresponding" may sometimes be used interchangeably. It should be noted that, without emphasizing the distinction between them, their intended meanings are consistent.

[0050] Furthermore, in embodiments of the present invention, sometimes a subscript (such as W1) may be mistakenly written as a non-subscript form (such as W1). Without emphasizing the difference, the meaning they express is the same.

[0051] Example

[0052] This embodiment provides a method for calculating and implanting the continuous pyrolysis rate of lignocellulosic biomass based on thermogravimetric analysis. This method can be implemented by an electronic device, which can be a terminal or a server. The execution flow of this method for calculating and implanting the continuous pyrolysis rate of lignocellulosic biomass based on thermogravimetric analysis is shown in the figure, including:

[0053] S1. Perform multiple thermogravimetric experiments on woody biomass at a specified heating rate and derive the curve of the sample weight change with time and temperature.

[0054] Specifically, in this embodiment, the implementation process of S1 is as follows:

[0055] S11 is a powder made from specific woody biomass and then dried.

[0056] The sample powder needs to be sieved through a mesh screen, and its particle size is less than 0.18 mm. Only about 3-5 mg is needed for one thermogravimetric experiment.

[0057] S12. Multiple thermogravimetric experiments were conducted using a thermogravimetric analyzer at different heating rates. The heating rate was generally set to 5K / min and 10K / min. Nitrogen was used in the atmosphere, and the heating range was determined according to the actual application scenario.

[0058] Among these measures, a low heating rate, a small sample size, and fine wood chips were selected to reduce the impact of heat transfer on the measurement results.

[0059] S13. Based on the sample weight change curve generated by the instrument over time and temperature, plot the sample conversion rate α over time and temperature.

[0060] S2, Obtaining the apparent activation energy E based on Friedman et al.'s conversion method. α The curve of conversion rate α and the pre-factor A α The curve of the ln value of the product of the reaction mechanism function f(α) and the conversion rate α is obtained. The pyrolysis rate is calculated by the Arrhenius formula to obtain the continuity curve of the pyrolysis rate with the sample conversion rate.

[0061] Specifically, in this embodiment, the implementation process of S2 is as follows:

[0062] S21, based on thermogravimetric experimental data, the apparent activation energy E of pyrolysis can be solved using the Friedman conversion method, etc. α and frequency factor A α The ln value of the product of the mechanistic function f(α), i.e., ln[A] α ·f(α)]-α, thereby obtaining E α -α and ln[A] α The f(α)-α curve;

[0063] Among them, the Friedman transformation method is a data processing method, and the specific method is as follows:

[0064] Substituting the heating rate β = dT / dt into the Arrhenius formula dα / dt = Ae -E / R·T ·f(α), we get ln[β] i (dα / dt) α,i ] = ln[A α ·f(α)]-E α / (R·T α,i ), where R is the ideal gas constant, T α,i The temperatures are given at different heating rates i and different conversion rates α.

[0065] Obtain ln(β·dα / dT) and -1000 / (RT) data for different heating rates i and the same conversion rate α. Connect two points with the same conversion rate and calculate the slope and intercept of the line.

[0066] The slope of the straight line is the apparent activation energy E of pyrolysis. α The intercept is ln[A] α ·f(α)]-α.

[0067] S22, based on the acquired E α -α and ln[A] αThe f(α)-α curve is obtained using the Arrhenius formula dα / dt=Ae -α / R·T ·f(α)=e^{ln[A α ·f(α)]-E α / (R·T α,i The conversion rate dα / dt is calculated, and the pyrolysis rate can be obtained by multiplying the conversion rate by the sample mass, thus obtaining the continuity curve of the pyrolysis rate with the sample conversion rate.

[0068] S3, using piecewise polynomials to transform E α -α and ln[A] α The pyrolysis rate is then fitted using the formula f(α)-α, and the pyrolysis rate is recalculated based on the fitted formula to correct for any fluctuations in the calculation.

[0069] Specifically, in this embodiment, the implementation process of S3 is as follows:

[0070] S31, for E α -α and ln[A] α The f(α)-α curve is piecewise polynomial fitted to obtain the fitting formula, and the fitting formula is substituted into the Arrhenius formula to obtain the dα / dt-α curve.

[0071] S32, based on the linear form of the Arrhenius formula, ln[A α ·f(α)]-E α / (R·T α,i The curve fluctuation correction is performed using ln(dα / dt). Specifically, under the same conversion rate, let the ln(dα / dt) values ​​for two different heating rates be C1 and C2, respectively, to obtain E. α =(C1-C2) / [1 / (R·T) α,2 )–1 / (R·T α,1 )],ln[A α ·f(α)]=C1+E α / (R·T α,1 );

[0072] S33, fit the ln(dα / dt)-α curve and the T-α curve under different conversion rates, and substitute the fitting formula into the above equation to solve for E. α andln[A α ·f(α)], thereby correcting the conversion rate data in the fluctuation region.

[0073] S4, supplements the uncalculated final stage of pyrolysis;

[0074] Specifically, in this embodiment, the implementation process of S4 is as follows:

[0075] S41. In the final stage of pyrolysis, the conversion rate is calculated using dα / dt=(dα / dT)·(dT / dt). The specific method is to solve dα / dT based on the thermogravimetric data of temperature change, and then perform piecewise simplification to obtain a simplified linear fitting formula.

[0076] Piecewise polynomial fitting methods cannot be used in the final stage of pyrolysis: E α andln[A α The value of f(α) becomes negative after the conversion rate reaches a certain value, and the data difference is large. The piecewise fitting method cannot fit the data of the subsequent stage, so the pyrolysis rate of this stage cannot be calculated.

[0077] S42, based on the temperature change data over time, solves dT / dt to calculate the pyrolysis rate at the end of the pyrolysis stage.

[0078] S5 converts the piecewise polynomial into an array form for implantation, and the Arrhenius formula and supplementary equations can be directly implanted.

[0079] Specifically, in this embodiment, the implementation process of S5 is as follows:

[0080] S51 organizes the coefficients of the piecewise polynomial into an array, transforming a large amount of experimental data into an array of polynomial coefficients, which facilitates code insertion and correction.

[0081] S52, the Arrhenius formula, and the supplementary equations do not require experimental data and can all be directly implemented.

[0082] The following embodiment illustrates the application process of the method of the present invention using a practical application scenario.

[0083] This embodiment uses Finnish pine as the research object and performs calculations and implantation of Finnish pine based on thermogravimetric analysis. The initial thermogravimetric temperature in this embodiment is 14℃, and the thermogravimetric experiment termination temperature is 800℃. Based on this, the specific implementation process of the method of this invention is as follows:

[0084] (1) Making Finnish pine samples

[0085] Approximately 4.5 mg of dried Finnish pine wood was prepared and sieved through an 80-mesh sieve, with a particle size of less than 0.18 mm.

[0086] The apparent density of the Finnish pine sample used was 491.4 kg / m³. 3 .

[0087] (2) Conduct thermogravimetric analysis of Finnish pine wood and derive the experimental data.

[0088] Thermogravimetric analysis was performed using a thermogravimetric analyzer, which mainly consists of a temperature-controlled furnace, a crucible and a crucible support, and a high-precision thermal balance connected to the crucible support.

[0089] The heating rates were set to 5 K / min and 10 K / min, the atmosphere was N2, and the flow rate was 30 mL / min.

[0090] During the experiment, a specified gas is introduced into the equipment, and the sample is heated under this atmosphere according to a specified time-temperature program. During heating, a balance monitors the sample mass data, and thermocouples record the temperature data, thereby obtaining the mass loss data of the sample over time or temperature, and generating TG and DTG curves, such as... Figure 2 As shown.

[0091] (3) Plot the sample conversion rate α as a function of time and temperature.

[0092] The curve generated by the instrument is actually composed of dense data points with sampling intervals between them.

[0093] When generating the sample conversion rate α curve as a function of time and temperature based on the original curve, mathematical operations were performed based on the data points.

[0094] The conversion rate is defined as 0 corresponding to the initial mass of the sample. The conversion rate is obtained by dividing the mass loss by the initial mass. Plotting the calculated data points as a curve yields the curve of the sample conversion rate α as a function of time and temperature, as shown below. Figure 3 As shown.

[0095] (4) Obtain E α -α and ln[A] α The f(α)-α curve.

[0096] Based on thermogravimetric experimental data, the apparent activation energy E of pyrolysis was solved using the Friedman conversion method. α and frequency factor A α The ln value of the product of the mechanistic function f(α), i.e., ln[A] α ·f(α)]-α;

[0097] Among them, the Friedman transformation method is a data processing method, and the specific method is as follows:

[0098] Substituting the heating rate β = dT / dt into the Arrhenius formula dα / dt = Ae -E / R·T ·f(α), we get ln[β] i (dα / dt) α,i ] = ln[A α ·f(α)]-E α / (R·Tα,i ), where R is the ideal gas constant, T α,i The temperatures are given at different heating rates i and different conversion rates α.

[0099] Obtain ln(β·dα / dT) and -1000 / (RT) data for different heating rates i and the same conversion rate α. Connect the two points with the same conversion rate and calculate the slope and intercept of the line. The slope of the line is the apparent activation energy E of pyrolysis. α The intercept is ln[A] α ·f(α)]-α, such as Figure 4 As shown.

[0100] (5) Obtain the continuity curve of pyrolysis rate as a function of sample conversion rate.

[0101] Based on the acquired E α -α and ln[A] α The f(α)-α curve is obtained using the Arrhenius formula dα / dt=Ae -α / R·T ·f(α)=e^{ln[A α ·f(α)]-E α / (R·T α,i )} Calculate the conversion rate dα / dt, such as Figure 5 As shown, the pyrolysis rate is obtained by multiplying the conversion rate by the sample mass, and the continuity curve of the pyrolysis rate with the sample conversion rate is obtained.

[0102] (6) Fitting E α -α and ln[A] α The f(α)-α curve.

[0103] Among them, for E α -α and ln[A] α The f(α)-α curve is fitted with a piecewise polynomial to obtain the fitting formula;

[0104] Substituting the fitting formula into the Arrhenius formula yields the dα / dt-α curve. Figure 6 ;

[0105] (7) Perform curve fluctuation correction.

[0106] Transform the Arrhenius formula into the linear form ln[A] α ·f(α)]-E α / (R·T α,i ) = ln(dα / dt);

[0107] At the same conversion rate, let the values ​​of ln(dα / dt) for two different heating rates be C1 and C2, respectively, and obtain E α=(C1-C2) / [1 / (R·T) α,2 )–1 / (R·T α,1 )],ln[A α ·f(α)]=C1+E α / (R·T α,1 );

[0108] Fit the ln(dα / dt)-α curves and T-α curves for different conversion rates;

[0109] Substituting the fitting formula into the above equation, we can solve for E. α andln[A α ·f(α)], thereby correcting the conversion rate data in the fluctuation region.

[0110] (8) Supplement the method for calculating the pyrolysis rate and curve fitting in the final stage of pyrolysis.

[0111] The conversion rate is calculated using dα / dt=(dα / dT)·(dT / dt) at the end of the pyrolysis stage;

[0112] The specific method is to first solve dα / dT based on the thermogravimetric data of temperature variation;

[0113] Segmentation and simplification are performed to derive the simplified linear fitting formula.

[0114] The dT / dt ratio is calculated based on temperature-time variation data to determine the pyrolysis rate at the end of the pyrolysis phase. The corrected and supplemented curve is shown below. Figure 7 As shown.

[0115] (9) Implantation procedure.

[0116] Organize the coefficients of the piecewise polynomial into an array, and transform a large amount of experimental data into an array of polynomial coefficients to facilitate code insertion and correction.

[0117] The Arrhenius formula and supplementary equations do not require experimental data and can be directly implemented.

[0118] In summary, this embodiment provides a method for calculating and implanting the continuous pyrolysis rate of lignocellulosic biomass based on thermogravimetric analysis. The conversion rate as a function of time and temperature is obtained through thermogravimetric experiments at different heating rates, and the apparent activation energy E is then obtained through a series of methods. α The curve of conversion rate α and the pre-factor A α The curve and fitting formula of the ln value of the product of the reaction mechanism function f(α) and the conversion rate α can be used to calculate the continuous pyrolysis rate of Finnish pine based on the Arrhenius formula. Subsequent code can be implanted based on the fitting formula, which facilitates numerical calculation and improves the prediction accuracy of the pyrolysis process.

[0119] Finally, it should be noted that the above description represents a preferred embodiment of the present invention. It should be pointed out that although the basic inventive concept of the present invention has been described, several improvements and modifications can be made without departing from the principles described herein, and these improvements and modifications should also be considered within the scope of protection of the present invention. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments as well as all changes and modifications falling within the scope of the embodiments of the present invention.

Claims

1. A method for calculating and implanting the continuous pyrolysis rate of lignocellulosic biomass based on thermogravimetric analysis, characterized in that, The method for calculating and implanting the continuous pyrolysis rate of lignocellulosic biomass based on thermogravimetric analysis includes: Multiple thermogravimetric experiments were conducted on woody biomass at a specified heating rate, and the weight of the samples as a function of time and temperature was derived. The apparent activation energy E was obtained based on the Friedman conversion method. a The curve of change with conversion rate a, and the pre-factor A a The curve of the ln value of the product of the reaction mechanism function f(a) and the conversion rate a is obtained. The pyrolysis rate is calculated by the Arrhenius formula to obtain the continuity curve of the pyrolysis rate with the sample conversion rate. Using piecewise polynomials to transform E a -α and ln[A] a The pyrolysis rate is recalculated based on the fitted formula by fitting f(a)]-a, and the calculation fluctuations are corrected and the uncalculated end-stage of pyrolysis is supplemented. The piecewise polynomial is transformed into an array form for implantation. The Arrhenius formula, correction and supplementary equations can be directly implanted, thereby realizing the calculation and code implantation of the continuous pyrolysis rate of lignobiomass. Among them, piecewise polynomials are used for E a -a and ln[A a The pyrolysis rate is then fitted using the formula f(a)-a, and the pyrolysis rate is recalculated based on the fitted formula. Corrections are made for calculation fluctuations, including: For E a -α and ln[A] a The f(a)-a curve is piecewise polynomial fitted to obtain the fitting formula, and the fitting formula is substituted into the Arrhenius formula to obtain the da / dt-a curve; The linear form of ln[A] based on the Arrhenius formula a ·f(a)]-E a / (R·T a，i The curve fluctuation correction is performed using ln(da / dt). Specifically, under the same conversion rate, let the ln(da / dt) values ​​for two different heating rates be C1 and C2, respectively, to obtain E. a =(C1-C2) / [1 / (R·T) a，2 )-1 / (R·T a，1 )],ln[A a ·f(a)]=C1+E a / (R·T a，1 ); Fit the ln(da / dr)-a curves and Ta curves for different conversion rates, and substitute the fitting formula into the above equation to solve for E. a andln[A a ·f(a)], thereby correcting the conversion rate data in the fluctuation region; This includes supplementing information on the uncalculated final stage of pyrolysis, including: In the final stage of pyrolysis, the conversion rate is calculated using da / dt = (da / dT)·(dT / dt). Specifically, da / dT is solved based on the thermogravimetric data as a function of temperature, and then the data is simplified by segmentation to obtain a simplified linear fitting formula. Finally, dT / dt is solved based on the temperature-time data to calculate the pyrolysis rate in the final stage of pyrolysis.

2. The method for calculating and implanting the continuous pyrolysis rate of lignocellulosic biomass based on thermogravimetric analysis as described in claim 1, characterized in that, Multiple thermogravimetric analyses were conducted on lignocellulosic biomass at a specified heating rate, and the weight of the samples as a function of time and temperature was derived, including: For specific woody biomass, powder is prepared and dried. Multiple thermogravimetric experiments are conducted using a thermogravimetric analyzer at different heating rates. The heating rate is generally set to 5K / min and 10K / min, and nitrogen atmosphere is used. The heating range is determined according to the actual application scenario. Based on the sample weight change curve generated by the instrument over time and temperature, the sample conversion rate α is plotted as a function of time and temperature.

3. The method for calculating and implanting the continuous pyrolysis rate of lignocellulosic biomass based on thermogravimetric analysis as described in claim 2, characterized in that, The characteristics of the sample are: The sample powder needs to be sieved through a mesh screen, and its particle size is less than 0.18 mm. Only about 3-5 mg is needed for a single thermogravimetric test. Low heating rate, small sample size, and fine wood chips were selected to reduce the impact of heat transfer on the measurement results.

4. The method for calculating and implanting the continuous pyrolysis rate of lignocellulosic biomass based on thermogravimetric analysis as described in claim 2, characterized in that, The conversion rate of a sample is the degree of pyrolysis of the sample. When the sample is not pyrolyzed, its conversion rate is 0, and when it is completely pyrolyzed, its conversion rate is 1.

5. The method for calculating and implanting the continuous pyrolysis rate of lignocellulosic biomass based on thermogravimetric analysis as described in claim 1, characterized in that, The apparent activation energy E was obtained based on the Friedman conversion method. a The curve of change with conversion rate a, and the pre-factor A a The curve of the ln value of the product of the reaction mechanism function f(a) and the conversion rate a is obtained. The pyrolysis rate is calculated using the Arrhenius formula to obtain the continuity curve of the pyrolysis rate with the sample conversion rate, including: Based on thermogravimetric experimental data, the apparent activation energy E of pyrolysis can be solved using the Friedman conversion method. a and frequency factor A a The ln value of the product of the mechanistic function f(a), i.e., ln[A] a ·f(a)]-a, thereby obtaining E a -a and ln[A a The f(a)-a curve; Based on the acquired E a -α and ln[A] a The curve f(a)-a is obtained using the Arrhenius formula da / dt = Ae -a / R·T ·f(a)=e^{ln[A a ·f(a)]-E a / (R·T a，i The conversion rate da / dt is calculated, and the pyrolysis rate can be obtained by multiplying the conversion rate by the sample mass, thus obtaining the continuity curve of the pyrolysis rate with the sample conversion rate.

6. The method for calculating and implanting the continuous pyrolysis rate of lignocellulosic biomass based on thermogravimetric analysis as described in claim 5, characterized in that, Friedman and other transformation methods are a type of data processing method, specifically as follows: Substituting the heating rate β = dT / dt into the Arrhenius formula da / dt = Ae -E / R·T ·f(a), we get ln[β] i (da / dt) a，i ] = ln[A a ·f(a)]-E a / (R·T a，i ), where R is the ideal gas constant, T a，i Temperatures under different heating rates i and different conversion rates a; Obtain ln(β·da / d 7) and -1000 / (R 7) data for different heating rates i and the same conversion rate a, connect two points with the same conversion rate and calculate the slope and intercept of the line; The slope of the straight line is the apparent activation energy E of pyrolysis. a The intercept is ln[A] a ·f(a)]-a.

7. The method for calculating and implanting the continuous pyrolysis rate of lignocellulosic biomass based on thermogravimetric analysis as described in claim 1, characterized in that, The piecewise fitting method is prone to data differences at the endpoints of the segments, resulting in fluctuations in the recalculated da / dt-a curve.

8. The method for calculating and implanting the continuous pyrolysis rate of lignocellulosic biomass based on thermogravimetric analysis as described in claim 1, characterized in that, Piecewise polynomial fitting methods cannot be used in the final stage of pyrolysis: E a andln[A a The value of f(a) becomes negative after the conversion rate reaches a certain value, and the data difference is large. The piecewise fitting method cannot fit the data of the subsequent stages, so the pyrolysis rate of this stage cannot be calculated.

9. The method for calculating and implanting the continuous pyrolysis rate of lignocellulosic biomass based on thermogravimetric analysis as described in claim 1, characterized in that, The piecewise polynomial is converted into array form for embedding. The Arrhenius formula and supplementary equations can be directly embedded, including: Organize the coefficients of the piecewise polynomial into an array, and transform a large amount of experimental data into an array of polynomial coefficients to facilitate code insertion and correction. The Arrhenius formula and its supplementary equations do not require experimental data and can be directly implemented.

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